A selection of circuits and a description of the operation of the power regulator on triacs and not only. Triac power control circuits are well suited for extending the life of incandescent lamps and for adjusting their brightness. Or for powering non-standard equipment, for example, at 110 volts.
The figure shows a circuit of a triac power controller, which can be changed by changing the total number of network half-cycles skipped by the triac for a certain time interval. On the elements of the DD1.1.DD1.3 chip, the oscillation period of which is about 15-25 network half-cycles.
The duty cycle of the pulses is regulated by the resistor R3. Transistor VT1, together with diodes VD5-VD8, is designed to bind the moment the triac is turned on during the transition of the mains voltage through zero. Basically, this transistor is open, respectively, "1" is supplied to the input DD1.4 and the transistor VT2 with the triac VS1 is closed. At the moment of zero crossing, transistor VT1 closes and opens almost immediately. In this case, if the output of DD1.3 was 1, then the state of the elements DD1.1.DD1.6 will not change, and if the output of DD1.3 was "zero", then the elements DD1.4.DD1.6 will generate a short pulse, which will be amplified by the transistor VT2 and open the triac.
As long as the generator output is a logical zero, the process will go cyclically after each transition of the mains voltage through the zero point.
The basis of the circuit is a foreign triac mac97a8, which allows you to switch high power connected loads, and used an old Soviet variable resistor to adjust it, and used a regular LED as an indication.
The triac power controller uses the principle of phase control. The operation of the power regulator circuit is based on a change in the moment the triac is turned on relative to the transition of the mains voltage through zero. At the initial moment of the positive half-cycle, the triac is in the closed state. With increasing mains voltage, capacitor C1 is charged through the divider.
The increasing voltage on the capacitor is phase shifted from the mains by an amount depending on the total resistance of both resistors and the capacitance of the capacitor. The capacitor is charged until the voltage across it reaches the “breakdown” level of the dinistor, approximately 32 V.
At the moment the dinistor is opened, the triac will also open, a current will flow through the load connected to the output, depending on the total resistance of the open triac and the load. The triac will be open until the end of the half cycle. Resistor VR1 sets the opening voltage of the dinistor and triac, thereby adjusting the power. At the moment of action of the negative half-cycle, the algorithm of the circuit is similar.
Circuit variant with minor modifications for 3.5 kW
The regulator circuit is simple, the load power at the output of the device is 3.5 kW. With this DIY ham radio you can control lights, heating elements and more. The only significant drawback of this circuit is that it is impossible to connect an inductive load to it in any case, because the triac will burn out!
Radio components used in the design: Triac T1 - BTB16-600BW or similar (KU 208 il VTA, VT). Dinistor T - type DB3 or DB4. Capacitor 0.1uF ceramic.
Resistance R2 510 Ohm limits the maximum volts on the capacitor to 0.1 uF, if you put the regulator slider in the 0 Ohm position, then the circuit resistance will be about 510 Ohms. The capacitance is charged through resistors R2 510Ω and variable resistance R1 420kΩ, after U on the capacitor reaches the opening level of the DB3 dinistor, the latter will generate a pulse that unlocks the triac, after which, with a further passage of the sinusoid, the triac is locked. The opening-closing frequency T1 depends on the level U on the 0.1 μF capacitor, which depends on the resistance of the variable resistor. That is, by interrupting the current (at a high frequency) the circuit thereby regulates the output power.
With each positive half-wave of the input AC voltage, capacitance C1 is charged through a chain of resistors R3, R4, when the voltage across capacitor C1 becomes equal to the opening voltage of the dinistor VD7, it will breakdown and discharge the capacitance through the diode bridge VD1-VD4, as well as resistance R1 and control electrode VS1. To open the triac, an electrical circuit of diodes VD5, VD6 of capacitor C2 and resistance R5 is used.
It is required to select the value of the resistor R2 so that at both half-waves of the mains voltage, the regulator triac reliably operates, and it is also required to select the values of the resistances R3 and R4 so that when the variable resistance knob R4 is rotated, the voltage at the load changes smoothly from minimum to maximum values. Instead of the triac TS 2-80, you can use TS2-50 or TS2-25, although there will be a slight loss in allowable power in the load.
KU208G, TS106-10-4, TS 112-10-4 and their analogues were used as a triac. At that moment in time when the triac is closed, the capacitor C1 is charged through the connected load and resistors R1 and R2. The charge rate is changed by resistor R2, resistor R1 is designed to limit the maximum charge current
When the threshold voltage on the capacitor plates is reached, the key opens, the capacitor C1 quickly discharges to the control electrode and switches the triac from the closed state to the open state, in the open state the triac shunts the circuit R1, R2, C1. At the moment the mains voltage passes through zero, the triac closes, then the capacitor C1 is charged again, but with a negative voltage.
Capacitor C1 from 0.1 ... 1.0 uF. Resistor R2 1.0 ... 0.1 MΩ. The triac is turned on by a positive current pulse to the control electrode at a positive voltage at the conditional anode output and a negative current pulse to the control electrode at a negative voltage of the conditional cathode. So the key element for the regulator is to be bidirectional. You can use a bidirectional dinistor as a key.
Diodes D5-D6 are used to protect the thyristor from possible reverse voltage breakdown. The transistor operates in the avalanche breakdown mode. Its breakdown voltage is about 18-25 volts. If you do not find P416B, then you can try to find a replacement for it.
The pulse transformer is wound on a ferrite ring with a diameter of 15 mm, grade H2000. The thyristor can be replaced with KU201
The circuit of this power regulator is similar to the circuits described above, only the interference suppression circuit C2, R3 is introduced, and the switch SW makes it possible to break the charging circuit of the control capacitor, which leads to instant blocking of the triac and disconnection of the load.
C1, C2 - 0.1 uF, R1-4k7, R2-2 mOhm, R3-220 Ohm, VR1-500 kOhm, DB3 - dinistor, BTA26-600B - triac, 1N4148/16 V - diode, any LED.
The regulator is used to adjust the load power in circuits up to 2000 W, incandescent lamps, heaters, a soldering iron, asynchronous motors, a car charger, and if you replace the triac with a more powerful one, you can use it in the current regulation circuit in welding transformers.
The principle of operation of this power regulator circuit is that the load receives a half-cycle of mains voltage after a selected number of missed half-cycles.
The diode bridge rectifies the alternating voltage. Resistor R1 and zener diode VD2, together with the filter capacitor, form a 10 V power supply for powering the K561IE8 chip and the KT315 transistor. The rectified positive voltage half-cycles passing through the capacitor C1 are stabilized by the zener diode VD3 at a level of 10 V. Thus, pulses with a frequency of 100 Hz follow the counting input C of the K561IE8 counter. If switch SA1 is connected to output 2, then the transistor base will always have a logic-one level. Because the reset pulse of the microcircuit is very short and the counter has time to restart from the same pulse.
Pin 3 will be set to logic 1. The thyristor will be open. All power will be allocated to the load. In all subsequent positions of SA1 at pin 3 of the counter, one pulse will pass through 2-9 pulses.
The K561IE8 chip is a decimal counter with a positional decoder at the output, so the logical unit level will be periodically at all outputs. However, if the switch is set to output 5 (pin 1), then the count will only occur up to 5. When the pulse passes output 5, the microcircuit will be reset. The count will start from zero, and a logical one level will appear at pin 3 for the duration of one half-cycle. At this time, the transistor and thyristor open, one half-cycle passes into the load. In order to make it clearer, I give vector diagrams of the operation of the circuit.
If you want to reduce the load power, you can add another counter chip by connecting pin 12 of the previous chip to pin 14 of the next. By installing another switch, it will be possible to adjust the power up to 99 missed pulses. Those. you can get about a hundredth of the total power.
The KR1182PM1 microcircuit has two thyristors and a control unit for them in its internal composition. The maximum input voltage of the KR1182PM1 chip is about 270 volts, and the maximum load can reach 150 watts without using an external triac and up to 2000 watts using, and also taking into account that the triac will be installed on a radiator.
To reduce the level of external interference, capacitor C1 and inductor L1 are used, and capacitance C4 is required to smoothly turn on the load. Adjustment is carried out using the resistance R3.
A selection of fairly simple regulator circuits for a soldering iron will make life easier for a radio amateur
Combination consists in combining the convenience of using a digital regulator and the flexibility of adjusting a simple one.
The considered power regulator circuit works on the principle of changing the number of periods of the input alternating voltage going to the load. This means that the device cannot be used to adjust the brightness of incandescent lamps due to the blinking visible to the eye. The circuit makes it possible to adjust the power within eight preset values.
There are a huge number of classic thyristor and triac controller circuits, but this controller is made on a modern element base and, moreover, was a phase one, i.e. it does not pass the entire half-wave of the mains voltage, but only some of it, thereby limiting the power, because the opening of the triac occurs only at the desired phase angle.
The thyristor charging unit by Krasimir Rilchev is intended for charging the batteries of trucks and tractors. It provides a continuously adjustable (by resistor RP1) charging current up to 30 A. The principle of regulation is phase-pulse based on thyristors, which provides maximum efficiency, minimum power dissipation and does not require rectifier diodes. The network transformer is made on a magnetic circuit with a cross section of 40 cm2, the primary winding contains 280 turns of PEL-1.6, the secondary 2x28 turns of PEL-3.0. The thyristors are mounted on 120x120 mm radiators. ...
For the "Thyristor turn signal relay" circuit
Automotive electronicsThyristor turn signal relay Kazan A. STAKHOV A non-contact relay for signaling turns of a car can be designed using silicon controlled diodes - thyristors. The diagram of such a relay is shown in the figure. The relay is a conventional multivibrator on transistors T1 and T2;, the switching frequency of which determines the frequency of flashing lamps, since the same multivibrator controls the DC switch on thyristors D1 and D4. Any low-power low-frequency transistors can work in the multivibrator. When the switch P1 is connected to the signal lamps of the front and rear sidelights, the multivibrator signal opens the thyristor D1 and the battery voltage is applied to the signal lamps. In this case, the right plate of the capacitor C1 is charged positively (relative to the left plate) through the resistor R5. When the triggering pulse of the multivibrator is applied to the thyristor D4, the same thyristor opens and the charged capacitor C1 is connected to the thyristor D1 so that it instantly receives a reverse voltage between the anode and cathode. How to check the k174ps1 chip This reverse voltage closes the thyristor D1, which interrupts the current in the load. The next triggering pulse of the multivibrator again opens the thyristor D1 and the whole process is repeated. Diodes D223 are used to limit negative current surges and improve the start-up of thyristors. Any low-power thyristors with any letter indices can be used in a DC switch. When using KU201A, the current consumed by signal lamps should not exceed 2 A; for KU202A, it can reach up to 10 a. The relay can also work from the on-board network with a voltage of 6 V. RADIO N10 1969 34 ...
For the circuit "POWER AMPLIFIER FOR CB-RADIO"
HF power amplifiersPOWER AMPLIFIER FOR SV-RADIO STATION. KOTYUK (EU2001), Minsk. In the manufacture of a power amplifier, radio amateurs face the question - what active component to use in it. The advent of transistors led to the creation of a large number of designs based on them. However, designing on such an element base at home is problematic for most radio amateurs. in the output stages of powerful modern metal-glass or metal-ceramic lamps of the GU-74B type, etc. difficult due to their high cost. The output is widely used lamps, for example 6P45S, used in color TVs. The idea of the proposed amplifier is not new, and was described in [I]. A simple current regulator It is made on two beam tetrodes 6P45S, connected according to the scheme with grounded grids. Technical characteristics: Power gain - 8 Maximum anode current - 800 mA Anode voltage - 600 Equivalent amplifier resistance - 500 ohm Switching to transmission occurs by applying a control voltage on the relay Kl, K2. In the absence of such a voltage in the CB-station, it is possible to make an electronic receive / transmit key, as is done in. Details and Construction The LI, L5 chokes have a 200 µH inductance and must be rated for 800 mA. The inductor L6, L7 is wound on a ring 50 VCh-2 K32x20x6 with two MGShV wires with a cross section of 1 mm2. Coils L2, L3 contain 3 turns each and are wound with wire 0 1 mm on Rl, R2, respectively. The P-loop coil L4 is wound with a wire with a diameter of 2.5 mm. Amplifier capacitors - type KSO for an operating voltage of 500 V. For forced ...
For the circuit "TURNING ON POWERFUL SEVEN-ELEMENT LED INDICATORS"
For the scheme "Push-pull converters (simplified calculation)"
Power supply Push-pull converters (simplified calculation) A. PETROV, 212029, Mogilev, Schmidt Ave., 32 - 17. Push-pull converters are very critical to the asymmetric remagnetization of the magnetic circuit, therefore, in bridge circuits, in order to avoid saturation of the magnetic circuits (Fig. 1) and as a result - the occurrence of through currents, special measures must be taken to balance the hysteresis loop, or in the simplest version Puc.1 - to introduce an air gap and a capacitor in series with the primary winding of the transformer. organization of natural electromagnetic processes in converters, in which switching of keys occurs at currents equal to or close to zero. In this case, the current spectrum decays faster and the power of radio interference is significantly weakened, which simplifies the filtering of both the input and output voltages. Triac ts112 and circuits on it Its advantages include the absence of a constant current component in the primary winding of the power transformer due to the capacitive divider. Fig.2 The half-bridge circuit provides power conversion of 0.25 ... 0.5 kW in one cell. The voltages on closed transistors do not exceed the supply voltage. The inverter has two PIC circuits: - one - for current (proportional-current control); - the second - for voltage. in proportion...
For the scheme "Application of an integral timer for automatic voltage control"
For the circuit "Power amplifier, made according to the bridge circuit."
AUDIO technique A bridged power amplifier. It has an output power of 60 W with a unipolar +40 V supply. powerful transistors is still quite small. One of the ways to increase the output power is the series-parallel connection of the same type of transistors, but this complicates the design of the amplifier and its tuning. Meanwhile, there is a way to increase the output power to avoid application hard-to-reach elements and do not increase the voltage of the power source. This method is contained in the use of two identical power amplifiers connected so that the input signal is applied to their inputs in antiphase, and the load is connected directly between the outputs of the amplifiers (amplifier bridge circuit). VHF circuit A power amplifier made according to such a bridge circuit has the following main technical characteristics: Rated output power ....... 60 W Harmonic factor .......... 0.5% ........ 10 ... 25,000 Hz Supply voltage ........... 40 V Quiescent current .......... 50 mA The circuit diagram of such an amplifier is shown in Fig. .1. Changing the phase of the input signal is achieved by applying it to the inverting input of one and the non-inverting input of another amplifier. The load is connected directly between the outputs of the amplifiers. To ensure temperature stabilization of the quiescent current of the output transistors, diodes VD1-VD4 are placed on a common heat sink with them. Fig.1Before switching on, check the correct installation and connections of the amplifier. After connecting the power supply with resistor R14, a voltage of no more than ...
For the scheme "Simple current regulator of the welding transformer"
An important design feature of any welding machine is the ability to adjust the operating current. In industrial devices, different methods of current regulation are used: shunting with the help of various types of chokes, changing the magnetic flux due to the mobility of the windings or magnetic shunting, stores of active ballast resistances and rheostats. The disadvantages of such an adjustment include the complexity of the design, the bulkiness of the resistances, their strong heating during operation, and inconvenience when switching. The most optimal option is to make it with taps even when winding the secondary winding and, by switching the number of turns, change the current. However, this method can be used to adjust the current, but not to adjust it over a wide range. In addition, adjusting the current in the secondary circuit of the welding transformer is associated with certain problems. So, significant currents pass through the control device, which leads to its bulkiness, and for the secondary circuit it is almost impossible to select such powerful standard switches that they can withstand currents up to 200 A. The ts112 triac and the circuits on it Another thing is the primary winding circuit, where the currents five times less. After a long search, through trial and error, the best solution to the problem was found - a spaciously popular thyristor controller, the circuit of which is shown in Fig. 1. With the utmost simplicity and availability of the element base, it is easy to manage, does not require settings and has proven itself in work - it works just like a "watch". Power control occurs when the primary winding of the welding transformer is periodically switched off for a fixed period of time at each half-cycle of the current (Fig. 2). In this case, the average role of the current decreases. The main elements of the regulator (thyristors) are connected opposite and parallel to each other. They alternately open...
For the scheme "Application of tunnel diodes"
Radio amateur-designer of tunnel diodes In fig. 1, 2 and 3 show three different circuit applications of the tunnel diode oscillator. The FM transmitter shown in Fig. 1 is very simple and provides reliable reception within a radius of 10-30 m when using a whip antenna and an FM receiver of medium sensitivity. Due to the fact that the transmitter modulation scheme is the simplest, the output signal is somewhat distorted, and, in addition to frequency modulation, obtained by changing the natural frequency of the generator synchronously with the microphone signal, there is significant amplitude modulation. It is impossible to greatly increase the output power of such a transmitter, since it is a source of interference. Such a transmitter can be used as a portable radio microphone, a call or intercom for short distances. Fig. 1. 1. The simplest tunnel diode transmitter. Ham Radio Converter Circuits Coil L contains 10 turns of PEL 0.2 wire. The operating principle of the local oscillator (Fig. 2) is the same as the previous transmitter. Its distinctive feature is the incomplete inclusion of the circuit. This is produced with the stated goal of improving the shape and stability of the generated vibrations. An ideal sine wave can be obtained when, in practice, small non-linear distortions are unavoidable. Fig. 1. 2. Local oscillator on a tunnel diode L = 200 μH. Depicted in fig. 3 tuning fork generator can be used as a standard for tuning musical instruments or a telegraph buzzer. The generator can also operate on diodes with lower maximum currents. In this case, the number of turns in the coils must be increased, and the dynamic loudspeaker is turned on through an amplifier. For the normal functioning of the generator, the total ohmic resistance ...
For the circuit "TRANSISTOR-LAMP AM TRANSMITTER"
Radio transmitters and radio stations For greater efficiency, reduction in weight and dimensions, transistors are widely used in them. In this case, for more or less radio stations, circuits are used that use a generator radio tube in the output stage of the transmitter. The anode voltage for it usually comes from a voltage converter. These schemes are complex and not economical enough. The proposed scheme has increased efficiency and simplicity of design. It uses a powerful modulator and a rectifier as an anode voltage source (see figure). The modulation transformer has two step-up windings - modulation and supply. The voltage taken from the supply winding is rectified and fed through the modulation winding to the anode of the output stage operating in the anode-screen modulation mode. Phase-pulse power controller on kmop The modulator operates in mode B and has a high efficiency (up to 70%). Since the anode voltage is proportional to the modulation voltage, controlled carrier modulation (CLC) is carried out in this circuit, which significantly increases efficiency./img/tr-la-p1.gif .7 MHz) and gives an excitation voltage of approximately 25-30 V. It should be noted that transistor T1 operates at a slightly increased collector voltage, so a special selection of workable specimens may be required. Inductor Dr1 is wound on a resistor VS-2 with a conductive layer removed and has 250 turns of PEL 0.2 wire. Coils L1 and L2 each contain 12 turns of PEL 1.2 wire. Coil diameter 12 mm, winding length - 20 mm. Branches in cat...
When developing a regulated power supply without a high-frequency converter, the developer faces such a problem that with a minimum output voltage and a high load current on the regulating element, the stabilizer dissipates a lot of power. Until now, in most cases, this problem was solved as follows: they made several taps at the secondary winding of the power transformer and divided the entire range of output voltage adjustment into several subranges. This principle is used in many serial power supplies, for example, UIP-2 and more modern ones. It is clear that the use of a power supply with multiple subranges becomes more complicated, and the remote control of such a power supply, for example, from a computer, also becomes more complicated.
The solution seemed to me to be the use of a controlled rectifier on a thyristor, since it becomes possible to create a power source controlled by one output voltage setting knob or one control signal with an output voltage adjustment range from zero (or almost zero) to the maximum value. Such a power supply can be made from commercially available parts.
To date, controlled rectifiers with thyristors have been described in great detail in books on power supplies, but are rarely used in practice in laboratory power supplies. In amateur designs, they are also rare (except, of course, for car battery chargers). I hope that this work will help change this state of affairs.
In principle, the circuits described here can be used to stabilize the input voltage of a high-frequency converter, for example, as is done in Elektronika Ts432 TVs. The circuits shown here can also be used to make laboratory power supplies or chargers.
I give the description of my works not in the order in which I carried them out, but more or less ordered. Let's look at general issues first, then "low-voltage" designs such as power supplies for transistor circuits or battery charging, and then "high-voltage" rectifiers for powering vacuum tube circuits.
Operation of a thyristor rectifier for a capacitive load
The literature describes a large number of thyristor power controllers operating on alternating or pulsating current with active (for example, incandescent lamps) or inductive (for example, an electric motor) load. The rectifier load is usually a filter in which capacitors are used to smooth out ripples, so the rectifier load can be capacitive in nature.
Consider the operation of a rectifier with a thyristor controller for a resistive-capacitive load. A diagram of such a regulator is shown in fig. 1.
Rice. 1.
Here, for example, a full-wave rectifier with a midpoint is shown, however, it can also be made according to another scheme, for example, a bridge. Sometimes thyristors, in addition to regulating the voltage on the load U n they also perform the function of rectifying elements (valves), however, this mode is not allowed for all thyristors (KU202 thyristors with some letters allow operation as valves). For the sake of clarity, let's assume that thyristors are only used to regulate the voltage across the load. U n , and straightening is done by other devices.
The principle of operation of the thyristor voltage regulator is illustrated in Fig. 2. At the output of the rectifier (the connection point of the cathodes of the diodes in Fig. 1), voltage pulses are obtained (the lower half-wave of the sinusoid is “turned” up), indicated U rec . Pulsation frequency f p at the output of a full-wave rectifier is equal to twice the mains frequency, i.e. 100 Hz when powered by mains 50 Hz . The control circuit supplies the control electrode of the thyristor with current pulses (or light if an optothyristor is used) with a certain delay t relative to the beginning of the ripple period, i.e., the moment when the rectifier voltage U rec becomes zero.
Rice. 2.
Figure 2 is made for the case when the delay t exceeds half the period of pulsations. In this case, the circuit operates on the incident part of the sinusoid wave. The longer the thyristor turn-on delay, the lower the rectified voltage will be. U n on load. Voltage ripple on the load U n smoothed by a filter capacitor C f . Here and below, some simplifications are made when considering the operation of the circuits: the output impedance of the power transformer is assumed to be zero, the voltage drop across the rectifier diodes is not taken into account, and the thyristor turn-on time is not taken into account. It turns out that the recharging of the filter capacitance C f happens instantly. In reality, after a trigger pulse is applied to the control electrode of the thyristor, the filter capacitor takes some time to charge, which, however, is usually much less than the pulsation period T p.
Now imagine that the thyristor turn-on delay t is equal to half the pulsation period (see Fig. 3). Then the thyristor will turn on when the voltage at the rectifier output passes through the maximum.
Rice. 3.
In this case, the load voltage U n will also be the largest, approximately the same as if there were no thyristor regulator in the circuit (we neglect the voltage drop across the open thyristor).
This is where we run into a problem. Suppose we want to regulate the load voltage from almost zero to the highest value that can be obtained from the available power transformer. To do this, taking into account the assumptions made earlier, it will be necessary to apply triggering pulses to the thyristor EXACTLY at the moment when U rec passes through a maximum, i.e. t c \u003d T p /2. Taking into account the fact that the thyristor does not open instantly, but recharging the filter capacitor C f also requires some time, the triggering pulse must be applied a little BEFORE half of the pulsation period, i.e. t< T п /2. The problem is that, firstly, it is difficult to say how much earlier, because it depends on such reasons that are difficult to accurately take into account when calculating, for example, the turn-on time of a given thyristor instance or the total (including inductances) output resistance of a power transformer. Secondly, even if the calculation and adjustment of the circuit is absolutely accurate, the turn-on delay time t , the frequency of the network, and hence the frequency and period T p ripple, thyristor turn-on time and other parameters may change over time. Therefore, in order to get the highest voltage on the load U n there is a desire to turn on the thyristor much earlier than half the pulsation period.
Suppose that we did so, i.e., set the delay time t much smaller T p /2. Graphs characterizing the operation of the circuit in this case are shown in Fig. 4. Note that if the thyristor opens before half a half cycle, it will remain open until the process of charging the filter capacitor is completed. C f (see the first pulse in Fig. 4).
Rice. 4.
It turns out that for a short delay t possible fluctuations in the output voltage of the regulator. They occur if, at the moment the triggering pulse is applied to the thyristor, the voltage on the load U n there is more voltage at the output of the rectifier U rec . In this case, the thyristor is under reverse voltage and cannot open under the action of a triggering pulse. One or more trigger pulses may be missed (see second pulse in Figure 4). The next turn on of the thyristor will occur when the filter capacitor is discharged and at the moment the control pulse is applied, the thyristor will be under direct voltage.
Probably the most dangerous is the case when every second impulse is missed. In this case, a direct current will pass through the winding of the power transformer, under the influence of which the transformer may fail.
In order to avoid the appearance of an oscillatory process in the thyristor controller circuit, it is probably possible to abandon the pulse control of the thyristor, but in this case the control circuit becomes more complicated or becomes uneconomical. Therefore, the author has developed a thyristor regulator circuit in which the thyristor is normally triggered by control pulses and no oscillatory process occurs. Such a scheme is shown in Fig. 5.
Rice. 5.
Here the thyristor is loaded on the starting resistance R p , and the filter capacitor C R n connected via start diode VD n . In such a circuit, the thyristor starts up regardless of the voltage across the filter capacitor C f .After a trigger pulse is applied to the thyristor, its anode current first begins to pass through the starting resistance R p and, then, when the voltage is on R p exceed the load voltage U n , the starting diode opens VD n and the anode current of the thyristor recharges the filter capacitor C f . Resistance R p such a value is chosen to ensure a stable start of the thyristor with a minimum delay time of the triggering pulse t . It is clear that some power is wasted on the starting resistance. Therefore, in the above circuit, it is preferable to use thyristors with a low holding current, then it will be possible to apply a large starting resistance and reduce power losses.
The scheme in fig. 5 has the disadvantage that the load current passes through an additional diode VD n , on which part of the rectified voltage is uselessly lost. This drawback can be eliminated by connecting a starting resistance R p to a separate rectifier. A circuit with a separate control rectifier from which the start circuit and starting resistance are powered R p shown in fig. 6. In this circuit, the control rectifier diodes can be low-power, since the load current flows only through the power rectifier.
Rice. 6.
Low voltage power supplies with thyristor regulator
Below is a description of several designs of low voltage rectifiers with a thyristor regulator. In their manufacture, I took as a basis the circuit of a thyristor regulator used in devices for charging car batteries (see Fig. 7). This scheme was successfully used by my late comrade A. G. Spiridonov.
Rice. 7.
The elements circled in the diagram (Fig. 7) were installed on a small printed circuit board. Several similar schemes are described in the literature, the differences between them are minimal, mainly in the types and ratings of parts. The main differences are:
1. Time-setting capacitors of different capacities are used, i.e. instead of 0.5m F put 1 m F , and, accordingly, a variable resistance of another value. For the reliability of starting the thyristor in my circuits, I used a capacitor for 1m F.
2. Parallel to the time-setting capacitor, you can not put resistance (3 k Win fig. 7). It is clear that this may require a variable resistance not 15 k W, but a different value. I have not yet found out the influence of the resistance parallel to the time-setting capacitor on the stability of the circuit.
3. In most circuits described in the literature, transistors of the KT315 and KT361 types are used. Sometimes they fail, so in my circuits I used more powerful transistors of the KT816 and KT817 types.
4. To base connection point pnp and npn collector transistors, a divider can be connected from resistances of a different value (10 k W and 12k W in fig. 7).
5. A diode can be installed in the control electrode circuit of the thyristor (see the diagrams below). This diode eliminates the effect of the thyristor on the control circuit.
The diagram (Fig. 7) is given as an example, several similar diagrams with descriptions can be found in the book “Chargers and start-chargers: An information review for motorists / Comp. A. G. Khodasevich, T. I. Khodasevich - M.: NT Press, 2005”. The book consists of three parts, it contains almost all the chargers in the history of mankind.
The simplest rectifier circuit with a thyristor voltage regulator is shown in fig. 8.
Rice. 8.
This circuit uses a full-wave mid-point rectifier because it contains fewer diodes, so fewer heatsinks are needed and higher efficiency. The power transformer has two secondary windings for alternating voltage 15 V . The thyristor control circuit here consists of a capacitor C1, resistances R 1- R 6, transistors VT 1 and VT 2, diode VD 3.
Let's consider how the circuit works. Capacitor C1 is charged through a variable resistance R 2 and constant R 1. When the voltage across the capacitor C 1 will exceed the voltage at the connection point of the resistances R4 and R 5, open the transistor VT 1. Collector current of the transistor VT 1 opens VT 2. In turn, the collector current VT 2 opens VT 1. Thus, the transistors open like an avalanche and the capacitor is discharged C 1 to thyristor control electrode VS 1. This is how the triggering impulse is obtained. By changing the variable resistance R 2 trigger pulse delay time, the output voltage of the circuit can be adjusted. The greater this resistance, the slower the capacitor charges. C 1, the trigger pulse delay time is longer and the output voltage at the load is lower.
Constant resistance R 1, connected in series with a variable R 2 limits the minimum pulse delay time. If it is greatly reduced, then at the minimum position of the variable resistance R 2, the output voltage will abruptly disappear. That's why R 1 is selected in such a way that the circuit works stably at R 2 in the position of minimum resistance (corresponding to the highest output voltage).
The circuit uses resistance R 5 power 1 W only because it came to hand. It will probably suffice to install R 5 with a power of 0.5 W.
resistance R 3 is set to eliminate the influence of interference on the operation of the control circuit. Without it, the circuit works, but is sensitive, for example, to touching the terminals of transistors.
Diode VD 3 eliminates the influence of the thyristor on the control circuit. In experience, I checked and made sure that the circuit works more stable with a diode. In short, you don’t need to skimp, it’s easier to put the D226, whose reserves are inexhaustible and make a reliable device.
resistance R 6 in thyristor control electrode circuit VS 1 increases the reliability of its operation. Sometimes this resistance is set to a larger value or not set at all. The circuit without it usually works, but the thyristor can spontaneously open due to interference and leakage in the control electrode circuit. I have installed R 6 value 51 Was recommended in the reference data of thyristors KU202.
Resistance R 7 and diode VD 4 provide a reliable start of the thyristor with a short delay time of the triggering pulse (see Fig. 5 and explanations to it).
Capacitor C 2 smoothes the voltage ripple at the output of the circuit.
As a load during the experiments, the regulator used a lamp from a car headlight.
A diagram with a separate rectifier for powering the control circuits and starting the thyristor is shown in fig. 9.
Rice. 9.
The advantage of this circuit is a smaller number of power diodes that require installation on radiators. Note that the diodes D242 of the power rectifier are connected by cathodes and can be installed on a common radiator. The anode of the thyristor connected to its case is connected to the “minus” of the load.
The wiring diagram of this version of the controlled rectifier is shown in fig. 10.
Rice. 10.
To smooth the ripple of the output voltage can be applied LC -filter. A diagram of a controlled rectifier with such a filter is shown in fig. eleven.
Rice. eleven.
I applied exactly LC -filter for the following reasons:
1. It is more resistant to overloads. I was designing a circuit for a laboratory power supply, so overloading it is quite possible. I note that even if you make any protection scheme, it will have some response time. During this time, the power supply should not fail.
2. If you make a transistor filter, then some voltage will definitely drop across the transistor, so the efficiency will be low, and the transistor may need a radiator.
The filter uses a serial inductor D255V.
Consider possible modifications of the thyristor control circuit. The first of them is shown in Fig. 12.
Rice. 12.
Usually, the time-setting circuit of a thyristor regulator is made from a time-setting capacitor and a variable resistance connected in series. Sometimes it is convenient to build a circuit so that one of the outputs of the variable resistance is connected to the "minus" of the rectifier. Then you can turn on the variable resistance in parallel with the capacitor, as done in Figure 12. When the engine is in the lower position according to the circuit, the main part of the current passing through the resistance 1.1 k Wenters the time-setting capacitor 1mF and charges it quickly. In this case, the thyristor starts at the “tops” of the rectified voltage ripples or a little earlier, and the output voltage of the regulator is the highest. If the engine is in the upper position according to the diagram, then the timing capacitor is shorted and the voltage on it will never open the transistors. In this case, the output voltage will be zero. By changing the position of the variable resistance slider, it is possible to change the strength of the current charging the timing capacitor and, thus, the delay time of the triggering pulses.
Sometimes it is required to control the thyristor regulator not with the help of a variable resistance, but from some other circuit (remote control, control from a computer). It happens that the parts of the thyristor regulator are under high voltage and direct connection to them is dangerous. In these cases, an optocoupler can be used instead of a variable resistance.
Rice. 13.
An example of including an optocoupler in a thyristor controller circuit is shown in fig. 13. Type 4 transistor optocoupler is used here N 35. The base of its phototransistor (pin 6) is connected through a resistance to the emitter (pin 4). This resistance determines the gain of the optocoupler, its speed and resistance to temperature changes. The author tested the regulator with a resistance of 100 indicated in the diagram k W, while the dependence of the output voltage on temperature turned out to be NEGATIVE, i.e., with a very strong heating of the optocoupler (the PVC insulation of the wires melted), the output voltage decreased. This is probably due to a decrease in the output of the LED when heated. The author thanks S. Balashov for advice on the use of transistor optocouplers.
Rice. 14.
When adjusting the thyristor control circuit, it is sometimes useful to adjust the transistor threshold. An example of such adjustment is shown in Fig. 14.
Consider also an example of a circuit with a thyristor regulator for a higher voltage (see Fig. 15). The circuit is powered by the secondary winding of the TCA-270-1 power transformer, which provides an alternating voltage of 32 V . The ratings of the parts indicated in the diagram are selected for this voltage.
Rice. 15.
The scheme in fig. 15 allows you to smoothly adjust the output voltage from 5 V to 40 V , which is sufficient for most semiconductor devices, so this circuit can be taken as the basis for the manufacture of a laboratory power supply.
The disadvantage of this circuit is the need to dissipate a sufficiently large power on the starting resistance R 7. It is clear that the smaller the holding current of the thyristor, the greater the value can be and the lower the power of the starting resistance R 7. Therefore, it is preferable to use thyristors with low holding current.
In addition to conventional thyristors, an optothyristor can be used in the thyristor regulator circuit. On fig. 16. shows a circuit with a TO125-10 optothyristor.
Rice. 16.
Here, the optothyristor is simply turned on instead of the usual one, but since its photothyristor and LED are isolated from each other, the schemes for its use in thyristor regulators may be different. Note that due to the low holding current of thyristors TO125, the starting resistance R 7 requires less power than in the circuit in fig. 15. Since the author was afraid to damage the optothyristor LED with high pulsed currents, resistance R6 was included in the circuit. As it turned out, the circuit works without this resistance, and without it, the circuit works better at low output voltages.
High voltage power supplies with thyristor regulator
When developing high-voltage power supplies with a thyristor regulator, the optothyristor control circuit developed by V.P. Burenkov (PRZ) for welding machines was taken as a basis. Printed circuit boards have been developed and are being produced for this circuit. The author is grateful to V.P. Burenkov for a sample of such a board. A diagram of one of the layouts of an adjustable rectifier using a board designed by Burenkov is shown in fig. 17.
Rice. 17.
The parts installed on the printed circuit board are circled in the diagram with a dotted line. As can be seen from fig. 16, quenching resistances are installed on the board R1 and R 2, rectifier bridge VD 1 and zener diodes VD 2 and VD 3. These parts are for 220V mains power V . To test the thyristor regulator circuit without alterations in the printed circuit board, a TBS3-0.25U3 power transformer was used, the secondary winding of which is connected in such a way that an alternating voltage of 200 is removed from it. V , i.e. close to the normal supply voltage of the board. The control circuit works in the same way as described above, i.e., the capacitor C1 is charged through a trimmer R 5 and a variable resistance (installed off-board) until the voltage across it exceeds the voltage at the base of the transistor VT 2, after which the transistors VT 1 and VT2 open and the capacitor C1 is discharged through the opened transistors and the optocoupler thyristor LED.
The advantage of this circuit is the ability to adjust the voltage at which the transistors open (using R 4), as well as the minimum resistance in the timing circuit (using R 5). As practice shows, having the possibility of such adjustment is very useful, especially if the circuit is assembled in amateur conditions from random parts. With the help of tuning resistors R4 and R5, it is possible to achieve voltage regulation over a wide range and stable operation of the regulator.
With this circuit, I began my R&D work on the development of a thyristor regulator. In it, the skipping of triggering pulses was also detected when the thyristor operated on a capacitive load (see Fig. 4). The desire to improve the stability of the regulator led to the appearance of the circuit in Fig. 18. In it, the author tested the operation of a thyristor with starting resistance (see Fig. 5.
Rice. 18.
In the scheme of Fig. 18. used the same board as in the diagram of fig. 17, only the diode bridge was removed from it, because here, one common rectifier is used for the load and the control circuit. Note that in the diagram in Fig. 17, the starting resistance is selected from several connected in parallel to determine the maximum possible value of this resistance, at which the circuit begins to work stably. A wire resistance 10 is connected between the optothyristor cathode and the filter capacitor.W. It is needed to limit the current surges through the optoristor. Until this resistance was set, after turning the variable resistance knob, the optothyristor passed one or more whole half-waves of the rectified voltage into the load.
Based on the experiments carried out, a rectifier circuit with a thyristor regulator was developed, suitable for practical use. It is shown in fig. 19.
Rice. 19.
Rice. 20.
PCB SCR 1M 0 (Fig. 20) is designed for installation on it of modern small-sized electrolytic capacitors and wire resistances in a ceramic case of the type SQP . The author expresses his gratitude to R. Peplov for his help with the fabrication and testing of this printed circuit board.
Since the author was developing a rectifier with the highest output voltage of 500 V , it was necessary to have some reserve for the output voltage in case of a decrease in the mains voltage. It was possible to increase the output voltage if the windings of the power transformer were reconnected, as shown in fig. 21.
Rice. 21.
Note also that the diagram in Fig. 19 and board fig. 20 are designed with the possibility of their further development. For this on board SCR 1M 0 there are additional conclusions from the common wire GND 1 and GND 2, from the rectifier DC 1
Development and adjustment of a rectifier with a thyristor regulator SCR 1M 0 were carried out jointly with student R. Pelov at PSU. C with his help, photographs of the module were taken SCR 1M 0 and waveforms.
Rice. 22. View of the SCR 1 M module 0 part side
Rice. 23. View of the module SCR 1M 0 solder side
Rice. 24. View of the module SCR 1 M 0 on the side
Table 1. Oscillograms at low voltage
|
No. p / p |
Minimum voltage regulator position |
According to the scheme |
Notes |
|
On the cathode VD5 |
5 V/div 2 ms/div |
||
|
|
On capacitor C1 |
2 V/div 2 ms/div |
|
|
|
ie connections R2 and R3 |
2 V/div 2 ms/div |
|
|
|
At the anode of the thyristor |
100 V/div 2 ms/div |
|
|
|
At the thyristor cathode |
50 V/div 2 ms/de |
Table 2. Oscillograms at medium voltage
|
No. p / p |
Middle position of the voltage regulator |
According to the scheme |
Notes |
|
|
On the cathode VD5 |
5 V/div 2 ms/div |
|
|
|
On capacitor C1 |
2 V/div 2 ms/div |
|
|
|
ie connections R2 and R3 |
2 V/div 2 ms/div |
|
|
|
At the anode of the thyristor |
100 V/div 2 ms/div |
|
|
|
At the thyristor cathode |
100 V/div 2 ms/div |
Table 3. Oscillograms at maximum voltage
|
No. p / p |
Maximum voltage regulator position |
According to the scheme |
Notes |
|
|
On the cathode VD5 |
5 V/div 2 ms/div |
|
|
|
On capacitor C1 |
1 V/div 2 ms/div |
|
|
|
ie connections R2 and R3 |
2 V/div 2 ms/div |
|
|
|
At the anode of the thyristor |
100 V/div 2 ms/div |
|
|
|
At the thyristor cathode |
100 V/div 2 ms/div |
To get rid of this shortcoming, the regulator circuit was changed. Two thyristors were installed - each for its own half-cycle. With these changes, the circuit was tested for several hours and no “outliers” were noticed.
Rice. 25. SCR 1 M 0 scheme with modifications
(Option 1)
In triac power controllers operating on the principle of passing a certain number of current half-periods through the load per unit time, the parity condition for their number must be met. In many well-known amateur radio (and not only) designs, it is violated. Readers are offered a regulator that is free from this shortcoming. Its diagram is shown in rice. 1.
There is a power supply unit, an adjustable duty cycle pulse generator and a pulse shaper that controls the triac. The power node is made according to the classical scheme: current-limiting resistor R2 and capacitor C1, rectifier on diodes VD3, VD4, zener diode VD5, smoothing capacitor C3. The pulse frequency of the generator, collected on the elements DD1.1, DD1.2 and DD1.4, depends on the capacitance of the capacitor C2 and the resistance between the extreme terminals of the variable resistor R1. The same resistor regulates the duty cycle of the pulses. Element DD1.3 serves as a pulse shaper with the frequency of the mains voltage supplied to its output 1 through a divider of resistors R3 and R4, with each pulse starting near the transition of the instantaneous value of the mains voltage through zero. From the output of the DD1.3 element, these pulses are fed through the limiting resistors R5 and R6 to the bases of the transistors VT1, VT2. The control pulses amplified by the transistors through the decoupling capacitor C4 come to the control electrode of the triac VS1. Here, their polarity corresponds to the sign of the mains voltage applied at that moment to the pin. 2 triacs. Due to the fact that the elements DD1.1 and DD1.2, DD1.3 and DD1.4 form two triggers, the level at the output of the DD1.4 element, connected to pin 2 of the DD1.3 element, changes to the opposite only in the negative half-cycle of the mains voltage . Suppose the trigger on the elements DD1.3, DD1.4 is in a state with a low level at the output of the element DD1.3 and a high level at the output of the element DD1.4. To change this state, it is necessary that the high level at the output of the DD1.2 element, connected to pin 6 of the DD1.4 element, becomes low. And this can only happen in the negative half-cycle of the mains voltage supplied to pin 13 of the DD1.1 element, regardless of the moment the high level is set at pin 8 of the DD1.2 element. The formation of the control pulse begins with the arrival of a positive half-cycle of the mains voltage at pin 1 of the element DD1.3. At some point, as a result of recharging the capacitor C2, the high level at pin 8 of the DD1.2 element will change to low, which will set a high voltage level at the output of the element. Now the high level at the output of the DD1.4 element can also change to a low one, but only in the negative half-cycle of the voltage supplied to pin 1 of the DD1.3 element. Therefore, the operating cycle of the control pulse shaper will end at the end of the negative half-cycle of the mains voltage, and the total number of half-cycles of the voltage applied to the load will be even. The main part of the device parts is mounted on a single-sided printed circuit board, the drawing of which is shown in rice. 2.
Diodes VD1 and VD2 are soldered directly to the terminals of the variable resistor R1, and the resistor R7 is soldered to the terminals of the triac VS1. The triac is equipped with a factory-made ribbed heat sink with a heat-removing surface area of about 400 cm2. Used fixed resistors MLT, variable resistor R1 - SPZ-4aM. It can be replaced by another of the same or greater resistance. The values of resistors R3 and R4 must be the same. Capacitors C1, C2 - K73-17. If increased reliability is required, then the oxide capacitor C4 can be replaced with a film one, for example, K73-17 2.2 ... 4.7 uF at 63 V, but the dimensions of the printed circuit board will have to be increased.
Instead of KD521A diodes, other low-power silicon ones are also suitable, and the D814V zener diode will replace any more modern one with a stabilization voltage of 9 V. Replacing KT3102V, KT3107G transistors - other low-power silicon ones of the corresponding structure. If the amplitude of the current pulses opening the triac VS1 is insufficient, the resistance of resistors R5 and R6 cannot be reduced. It is better to choose transistors with the highest possible current transfer coefficient at a voltage between the collector and emitter of 1 V. For VT1 it should be 150 ... 250, for VT2 - 250 ... 270. Upon completion of the installation, you can connect a load with a resistance of 50 ... 100 Ohm to the regulator and turn it on to the network. In parallel with the load, connect a DC voltmeter for 300 ... 600 V. If the triac steadily opens in both half-cycles of the mains voltage, the voltmeter needle does not deviate from zero at all or fluctuates slightly around it. If the voltmeter needle deviates only in one direction, then the triac opens only in half-cycles of one sign. The direction of the deflection of the arrow corresponds to the polarity of the voltage applied to the triac, at which it remains closed. Usually, the correct operation of the triac can be achieved by installing a transistor VT2 with a large value of the current transfer coefficient.
Triac power regulator.
(Option 2)
The proposed triac power controller (see Fig.) can be used to control the active power of heating devices (soldering iron, electric stove, stove, etc.). It is not recommended to use it to change the brightness of lighting devices, because. they will flash strongly. A feature of the regulator is the switching of the triac at the moments when the mains voltage passes through zero, so it does not create network interference Power is regulated by changing the number of half-cycles of the mains voltage supplied to the load.
The clock generator is made on the basis of the logical element EXCLUSIVE OR DD1.1. Its feature is the appearance of a high level (logical "1") at the output in the case when the input signals differ from each other, and a low level ("O") when the input signals coexist. As a result of this, "G appears at the output of DD1.1 only at the moments when the mains voltage passes through zero. The generator of rectangular pulses with adjustable duty cycle is made on logical elements DD1.2 and DD1.3. Connecting one of the inputs of these elements to power turns them into inverters The result is a square wave generator with a pulse frequency of approximately 2 Hz and a variable duration with resistor R5.
On resistor R6 and diodes VD5. VD6, the 2I coincidence scheme is executed. A high level at its output appears only when two "1"s coincide (synchronization pulse and pulse from the generator). As a result, bursts of synchronization pulses appear at the output 11 DD1.4. Element DD1.4 is a pulse repeater, for which one of its inputs is connected to a common bus.
On the transistor VT1, a control pulse shaper is made. Packets of short pulses from its emitter, synchronized with the beginning of half-cycles of the mains voltage, enter the control transition of the triac VS1 and open it. Current flows through RH.
The triac power controller is powered through the R1-C1-VD2 chain. The zener diode VD1 limits the supply voltage at 15 V. Positive pulses from the zener diode VD1 through the diode VD2 charge the capacitor C3.
With a large adjustable power, the triac VS1 must be installed on a radiator. Then the triac type KU208G allows you to switch power up to 1 kW. The dimensions of the radiator can be roughly estimated based on the fact that for 1 W of dissipated power, about 10 cm2 of the effective surface of the radiator is needed (the triac case itself dissipates 10 W of power). For more power, a more powerful triac is needed, for example, TS2-25-6. It allows you to switch a current of 25 A. The triac is selected with a permissible reverse voltage of at least 600 V. It is desirable to protect the triac with a varistor connected in parallel, for example, CH-1-1-560. Diodes VD2.. .VD6 can be used in any circuit, for example. KD522B or KD510A Zener diode - any low-power voltage 14.. .15 V. D814D will do.
The triac power controller is placed on a printed circuit board made of one-sided fiberglass with dimensions of 68x38 mm.
Simple power regulator.
Power regulator up to 1 kW (0%-100%).
The circuit was assembled more than once, it works without adjustment and other problems. Naturally, diodes and a thyristor on a radiator with a power of more than 300 watts. If less, then the housings of the parts themselves are enough for cooling.
Initially, transistors of the MP38 and MP41 types were used in the circuit.
The scheme proposed below will reduce the power of any heating appliance. The circuit is quite simple and accessible even to a novice radio amateur. To control a more powerful load, thyristors must be placed on a radiator (150 cm2 or more). To eliminate the interference created by the regulator, it is desirable to put a choke at the input.
On the parent circuit, a KU208G triac was installed, and it did not suit me because of the low switching power. After digging, I found imported triacs BTA16-600. The maximum switching voltage of which is 600 volts with a current of 16A !!!
All resistors MLT 0.125;
R4 - SP3-4aM;
The capacitor is composed of two (connected in parallel) 1 microfarad 250 volts each, type - K73-17.
With the data indicated in the diagram, the following results were achieved: Voltage regulation from 40 to the mains voltage.
The regulator can be inserted into the regular heater housing.
Schematic drawn from the controller board of the vacuum cleaner.
on the condenser marking: 1j100
I tried to control a 2 kW heating element - I didn’t notice any blinking of light in the same phase,
the voltage on the heating element is regulated smoothly and, it seems, evenly (in proportion to the angle of rotation of the resistor).
It is regulated from 0 to 218 volts at a network voltage of 224-228 volts.
