hybrid power point combines modern engine internal combustion, technologically combined with electric motors. The whole complex is managed electronic system, and of course all components are different the highest quality. The hybrid propulsion system manages the energy consumption depending on the driving conditions of the vehicle.
3.1 (a) Getting started
To start the movement and when driving at low speeds, only an electric motor is used.
When accelerating, the battery directs its energy to the power management unit.
The control unit directs energy to electric motors located in the front and back parts car.
Front and rear electric motors allow the car to move off smoothly.
3.1. (b) Movement.
When driving a car in normal mode the wheels are driven by a gasoline engine and electric motors; engine power is distributed between the wheels and electric generator which in turn drives the electric motors.
Energy distribution is controlled to ensure maximum efficiency. If necessary, the generator also charges the battery, giving it excess energy.
3.1 (c) Overclocking.
1. Gas engine accelerates the vehicle while operating normally.
2. To improve the dynamics, additional energy is supplied from the electric motor.
3. During normal operation, the gasoline engine also powers the generator.
4. The generator can direct excess power to the power management box.
3.1. (d) Braking.
1. When braking, kinetic energy is converted into electricity.
2. Electric motors direct it to the power control unit.
3. The power management unit returns power to the high voltage battery. The car's gasoline engine is running normally.
BLDC motor (VD)
Most often in hybrid cars as traction drive valve motor is used.
The valve motor is a synchronous motor based on the principle of frequency regulation with self-synchronization, the essence of which is to control the vector magnetic field stator depending on the position of the rotor. Valve motors (BLDC or PMSM in English literature) are also called demon collector engines direct current, because the controller of such a motor is usually powered by DC voltage.
3.2.1 Description of the HP
This type of motor is designed to improve the properties of DC motors.
In a brushless motor (VD), the inductor is located on the rotor (in the form permanent magnets), the armature winding is on the stator (synchronous motor). The supply voltage of the motor windings is formed depending on the position of the rotor. If a collector was used for this purpose in DC motors, then in a brushless motor its function is performed by a semiconductor switch (rotor position sensor (RPS) with an inverter).
The main difference between a VD and a synchronous motor is its self-synchronization with the help of a DPR, as a result of which, in VD, the field rotation frequency is proportional to the rotor speed.
3.2.2 Stator
Stator[Fig. 5] has a traditional design and is similar to the stator of an induction machine. It consists of a body, a core made of electrical steel and a copper winding laid in grooves along the perimeter of the core. The number of windings determines the number of motor phases. For self-starting and rotation, two phases are sufficient - sine and cosine. Usually VD three-phase, less often - four-phase.
According to the method of laying turns in the stator windings, motors with reverse electromotive force trapezoidal (BLDC) and sinusoidal (PMSM) waveforms. According to the method of supply phase electricity also varies trapezoidal or sinusoidally in the respective motor types.
(Fig. 5 Brushless motor stator)
3.2.3 Rotor
The rotor is made using permanent magnets and usually has two to eight pairs of poles with alternating north and south poles.
At first, ferrite magnets were used to make the rotor. They are common and cheap, but they have the disadvantage of low level magnetic induction. Magnets made from rare earth alloys are now gaining popularity, as they allow you to get high level magnetic induction and reduce the size of the rotor.
3.2.4 Rotor position sensor
The rotor position sensor (RPS) provides feedback on the position of the rotor. His work may be based on different principles-- photoelectric, inductive, on the Hall effect, etc. The most popular are Hall sensors and photoelectric, as they are practically inertialess and allow you to get rid of the delay in the channel feedback according to the position of the rotor.
The photoelectric sensor, in its classic form, contains three fixed photodetectors, which are alternately closed by a shutter rotating synchronously with the rotor. This is shown in the figure. The binary code obtained from the DPR fixes six different positions of the rotor. The sensor signals are converted by the control device into a combination of control voltages that control the power switches, so that two switches are turned on in each cycle (phase) of the engine operation and two of the three armature windings are connected in series to the network. Armature windings U, V, W are located on the stator with a shift of 120 ° and their beginnings and ends are connected so that when switching the keys, a rotating magnetic field is created.
3.2.5 HP control system
The control system contains power switches, often thyristors or insulated gate power transistors. Of these, a voltage inverter or a current inverter is assembled. The key management system is usually implemented using a microcontroller. The presence of a microprocessor requires a large number of computational operations for engine control.
3.2.6 How the HP works
The principle of HP operation is based on the fact that the HP controller switches the stator windings so that the stator magnetic field vector is always orthogonal to the rotor magnetic field vector. Using PWM, the controller controls the current flowing through the HP windings, i.e. the vector of the magnetic field of the stator, and thus the moment acting on the HP rotor is regulated. The sign of the angle between the vectors determines the direction of the moment acting on the rotor.
Switching is carried out in such a way that the rotor excitation flux - F0 is maintained constant relative to the armature flux. As a result of the interaction of the armature flux and excitation, a torque M is created, which tends to turn the rotor so that the armature and excitation fluxes coincide, but when the rotor turns under the action of the DPR, the windings switch and the armature flux turns to the next step.
In this case, the resulting current vector will be shifted and stationary relative to the rotor flux, which creates a moment on the motor shaft.
In the motor mode of operation, the stator MMF is ahead of the rotor MMF by an angle of 90°, which is maintained with the help of the DPR. In the braking mode, the stator MMF lags behind the rotor MMF, the angle of 90° is also maintained using the DPR.
3.2.7 Motor control
The HP controller regulates the torque acting on the rotor by changing the PWM value.
Unlike a brushed DC motor, switching in the HP is carried out and controlled electronically.
Control systems that implement algorithms for pulse-width regulation and pulse-width modulation in the control of the HP are widespread.
The system that provides the widest range of speed control is for motors with vector control. With the help of a frequency converter, the motor speed is controlled and the flux linkage in the machine is maintained at a given level.
A feature of the regulation of an electric drive with vector control is that controlled coordinates measured in a fixed coordinate system are converted to a rotating system, a constant value is allocated from them, proportional to the components of the vectors of controlled parameters, according to which control actions are formed, then the reverse transition.
The disadvantage of these systems is the complexity of the control and functional devices for a wide range of speed control.
Valve motors are powered by direct current. VD can be considered as a DC motor (inverted !!), in which the brush-collector assembly is replaced by electronics, which is emphasized by the word “valve”, that is, “controlled by power keys” (valves). The phase currents of a brushless motor have a sinusoidal shape. As a rule, an autonomous voltage inverter with pulse-width modulation is used as a power amplifier.
The valve motor should be distinguished from the brushless DC motor (BLDC), which has a trapezoidal magnetic field distribution in the gap and is characterized by rectangular shape phase voltages. The BLDT structure is simpler than the VD structure (there is no coordinate converter, instead of PWM, 120- or 180-degree switching is used, the implementation of which is simpler than PWM).
In the Russian-language literature, a motor is called a valve motor if the back-EMF of the controlled synchronous machine is sinusoidal, and contactless motor DC if the back-EMF is trapezoidal.
In the English literature, such motors are usually considered as part of an electric drive and are referred to under the abbreviations PMSM (Permanent Magnet Synchronous Motor) or BLDC (Brushless Direct Current Motor). It is worth noting that the abbreviation PMSM in English literature is more often used to refer to the synchronous machines themselves with permanent magnets and with a sinusoidal form of phase back-EMF, while the abbreviation BLDC is similar to the Russian abbreviation BDPT and refers to motors with a trapezoidal form of back-EMF (if other form is not specified).
Generally speaking, a brushless motor is not an electric machine in the traditional sense, since its problems affect a number of issues related to the theory of electric drive and automatic control systems: structural organization, the use of sensors and electronic components, as well as software.
BLDC motors that combine the reliability of machines alternating current with good controllability of DC machines, they are an alternative to DC motors (DC motors), which are characterized by a number of flaws associated with the brush-collector assembly (BCU), such as sparking, interference, brush wear, poor armature heat dissipation, etc. The absence of a control panel makes it possible to use the VD in those applications where the use of a DPT is difficult or impossible.
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Working principle of brushless DC motor
Subtitles
Description and principle of operation
The inputs of the coordinate converter (PC) receive DC voltages, the action of which is similar to the armature voltage of the DC motor, and u d (\displaystyle u_(d)), similar to the excitation voltage of the DC motor (the analogy is valid when considering the independent excitation circuit of the DC motor).
The signals , are projections of the control voltage vector U y → = ( u d , u q ) (\displaystyle (\vec (U_(y)))=\(u_(d),u_(q)\)) on the axis of the rotating coordinate system ( d , q ) (\displaystyle \(d,q\)) associated with the HP rotor (more precisely, with the rotor flux vector). Coordinate converter performs projection transformation u d , u q (\displaystyle u_(d),u_(q)) in the projection of a fixed coordinate system ( α , β ) (\displaystyle \(\alpha ,\beta \)) associated with the stator.
As a rule, in the control systems of the electric drive is set u d = 0 (\displaystyle u_(d)=0), while the coordinate transformation equations take the form:
U α = − u q ⋅ sin θ , (\displaystyle u_(\alpha )=-u_(q)\cdot \sin (\theta ),)
U β = (\displaystyle u_(\beta )=) u q ⋅ cos θ , (\displaystyle u_(q)\cdot \cos (\theta ),)
where is the angle of rotation of the rotor (and the system of rotating coordinates) relative to the axis α (\displaystyle \alpha ) fixed coordinate system. To measure the instantaneous value of an angle θ (\displaystyle \theta ) a rotor position sensor (RPS) is installed on the HP shaft.
In fact, u q (\displaystyle u_(q)) is in this case the assignment of the value of the amplitude of the phase voltages. A PC, carrying out position modulation of the signal u q (\displaystyle u_(q)), generates harmonic signals u α , u β (\displaystyle u_(\alpha ),u_(\beta )), which the power amplifier (PA) converts into phase voltages u A , u B (\displaystyle u_(A),u_(B)). Synchronous motor as part of a brushless motor, it is often called a synchronous electromechanical converter (SEMC).
As a rule, the electronic part of the HP switches the stator phases of the synchronous machine so that the stator magnetic flux vector is orthogonal to the rotor magnetic flux vector (the so-called vector control). If the orthogonality of the stator and rotor flows is observed, the maximum torque of the HP is maintained under conditions of a change in the rotational speed, which prevents the rotor from falling out of synchronism and ensures the operation of the synchronous machine with the highest possible efficiency for it. To determine the current position of the rotor flux, current sensors can be used instead of the rotor position sensor (indirect position measurement).
The electronic part of a modern VD contains a microcontroller and a transistor bridge, and the principle of pulse-width modulation (PWM) is used to form phase currents. The microcontroller monitors compliance with the specified control laws, and also performs system diagnostics and its software protection against emergency situations.
Sometimes there is no rotor position sensor, and the position is estimated by the control system from measurements of current sensors with the help of observers (the so-called "sensorless" control of the HP). In such cases, due to the removal of an expensive and often cumbersome position sensor, the price and weight and dimensions of an electric drive with HP are reduced, but control becomes more complicated, and the accuracy of position and speed determination decreases.
In applications of medium and high power electrical filters can be additionally included in the system to mitigate the negative effects of PWM: overvoltages on the windings, bearing currents and reduced efficiency. However, this is true for all types of engines.
Application
Due to their high reliability and good controllability, brushless motors are used in a wide range of applications, from computer fans and CD/DVD drives to robots and space rockets. VDs are widely used in industry, especially in speed control systems with a large range and a high rate of starts, stops and reverse; aviation technology, automotive engineering, biomedical equipment, household appliances and so on.
Advantages and disadvantages
Valve motors are designed to combine best qualities AC motors and DC motors. This determines their dignity.
Advantages:
- Wide speed range
- Non-contact and absence of knots requiring frequent maintenance(collector)
- Can be used in explosive and aggressive environments
- Large torque capacity
- High energy performance (efficiency above 90%)
- Long service life and high reliability due to the absence of sliding electrical contacts.
Valve motors are also characterized by some disadvantages, the main of which is high cost. However, speaking of high cost, one should also take into account the fact that brushless motors are usually used in expensive systems with increased requirements for accuracy and reliability.
Flaws:
- The high cost of the motor, due to the frequent use of expensive permanent magnets in the design of the rotor. The cost of an electric drive with HP, however, is comparable to the cost of a similar drive based on a DCT with independent excitation (the control characteristics of such a motor and HP are comparable). Generally speaking, a rotor with electromagnetic excitation However, this is associated with a set of practical inconveniences. In some cases, it is preferable to use an asynchronous motor with a frequency converter.
- Relatively complex engine structure and control.
Design
Structurally, modern valve drives consist of an electromechanical part (synchronous machine and rotor position sensor) and a control part (microcontroller and power bridge).
According to the location of the rotor, brushless motors are divided into intra-rotor (eng. inrunner) and external-rotor (eng. outrunner).
When referring to the design of the VD, it is useful to keep in mind a non-constructive element of the system - the control program (logic).
The synchronous machine used in the HP consists of a laminated (assembled from separate electrically insulated sheets of electrical steel - to reduce eddy currents) stator, in which a multi-phase (usually two- or three-phase) winding and a rotor (usually on permanent magnets) are located.
Hall sensors are used as rotor position sensors in BDPT, and rotating transformers and accumulating sensors are used in VD. In so-called. In "sensorless" systems, information about the position is determined by the control system based on the instantaneous values of the phase currents.
Information about the position of the rotor is processed by the microprocessor, which, according to the control program, generates control PWM signals. The low-voltage PWM signals from the microcontroller are then converted by a power amplifier (usually a transistor bridge) into power voltages applied to the motor.
The combination of the rotor position sensor and the electronic assembly in the HP and BDPT can be compared with a certain degree of reliability with the brush-collector unit of the DT. However, remember that motors are rarely used outside the drive. Thus, electronic equipment is characteristic of VD almost to the same extent as for DPT.
stator
The stator has a traditional design. It consists of a housing, a core made of electrical steel and a copper winding laid in grooves along the perimeter of the core. The winding is divided into phases, which are laid in grooves in such a way that they are spatially shifted relative to each other by an angle determined by the number of phases. It is known that two phases are sufficient for uniform rotation of the motor shaft of an AC machine. Usually synchronous machines, used in HP, are three-phase, however, there are also HP with four- and six-phase windings.
Because they allow you to get a higher level of magnetic induction and reduce the size of the rotor.
Rotor position sensor
The rotor position sensor (RPS) provides feedback on the position of the rotor. Its work can be based on different principles - photoelectric, inductive, transformer, on the Hall effect, and so on. The most popular are Hall sensors and photoelectric sensors, which have low inertia and provide small delays in the rotor position feedback channel.
Typically, a photoelectric sensor contains three fixed photodetectors, between which there is a rotating mask with risks, rigidly fixed on the HP rotor shaft. A simplified sensor is shown in Fig. 1 where the mask is shown in gray and the LEDs are yellow. Thus, the DPR provides information about the current position of the HP rotor for the control system.
25.3. BLDC motors
25.3.1. VD series brushless motors with a capacity of 30-132 kW
Valve motors of the VD series with a power of 30 - 132 kW with a height of the axis of rotation of 225 - 315 mm are designed for drives of the main movement of machine tools with CNC. The package includes an electromechanical converter (EMC), a controlled semiconductor switch - a frequency converter (FC), a rotor position sensor (RPS) and a tacho generator (TG).
The electromechanical converter (Fig. 25.4) is made in an inverted version (inductor on the stator, and armature on the rotor) and is structurally unified with 2P series DC collector motors. EMF excitation system - mixed. It consists of an independent excitation winding OB and a longitudinal compensating winding KO, included in the DC link of the inverter. Coils of windings of independent excitation and compensation are spaced apart on opposite poles of each pair. All EMF sizes are made with a four-pole inductor. In the tips of the poles there is a copper short-circuited damper winding. The rotor has 36 grooves beveled by one tooth division. The armature winding is three-phase, connected in a star with a neutral wire. The ends of the phases and the zero point are displayed on four slip rings. Sliding current collection from the rings is provided by metal-containing brushes installed in double brush holders.
Rice. 25.5. Connection diagram of the power circuits of the VD motor inverter
The frequency converter includes a power section and a control system. The power part of the inverter is a rectifier-inverter unit with a DC link. The power supply unit of the EMF excitation winding is structurally integrated with the inverter. The connection diagram of the inverter and EMF is shown in fig. 25.5.
The switching of the inverter valves at EMF speeds from 0 to 0.1 and nom is forced, and at speeds above 0.1 "nom it is natural.
The rotor position sensor is located in the same unit as the TG. It is a light-photodiode unit. In addition to the main functions of the DPR, it provides information about
Rice. 25.4. Structural scheme VD series engine:
1 - armature winding; 2 - independent excitation winding; 3 - longitudinal compensatory threshing; 4 - damper winding rods; 5 - short-circuit arcs; 6 - tachogenerator and DPR; 7 - fan; 8 - slip rings
angle of rotation or about the path (i.e., performs the function of a resolver).
The tachogenerator is production car type TMS-1.
structure symbol valve motor:
VD225GUHL4,
where B - valve; D - engine; 225 - height of the axis of rotation, mm; G - the presence of TG; UHL4 - climatic design and placement category in accordance with GOST 15150-69.
FC symbol structure:
ETU7YI-39, where E - electric drive; T - thyristor;
U - unified; 7 - from brushless motor; 8 - with engine low voltage with static converter; 39 - rated current at the output of the inverter, equal to 80 A.
EMF designs according to the mounting method - IM1001, IM2001, IM20011 according to GOST 2479-79, cooling method - IC06 according to GOST 20459-75, degree of protection - IP44 according to GOST 17494-72. Motor insulation - according to heat resistance class F (GOST 8865-70). The EMP version with filters on the suction branch pipe of the fan type "rider" is provided.
The working position of the FC blocks is vertical. They can be built into the
Table 25.22. Technical data brushless motors VD series
|
<ратность |
|||||||
|
EMP size |
Inverter frame size |
nominal power, kW |
Rotation frequency, rpm |
permanent link |
Phase current, A |
maximum frequency |
|
|
rotation |
|||||||
|
VD225 GUHL4 |
|||||||
|
WD250 GUHL4 |
|||||||
|
WD280 GUHL4 |
|||||||
|
VD315 GUHL4 |
|||||||
|
VD225 GUHL4 |
|||||||
|
WD250 GUHL4 |
|||||||
|
WD280 GUHL4 |
|||||||
|
VD315 GUHL4 |
|||||||
|
VD225 GUHL4 |
|||||||
|
WD250 GUHL4 |
|||||||
|
WD280 GUHL4 |
|||||||
|
VD315 GUHL4 |
|||||||
|
VD225 GUHL4 |
|||||||
|
WD250 GUHL4 |
|||||||
|
WD280 GUHL4 |
|||||||
|
VD315 GUHL4 |
Table 25.23. Overall, installation and connection dimensions, mm, and weight of VD series motors, version IM1001 (Fig. 25.6)
|
Size |
|||||||||||||||||||
|
engine |
TO |
h |
|||||||||||||||||
|
VD225 GUHL4 |
|||||||||||||||||||
|
WD250 GUHL4 |
|||||||||||||||||||
|
WD280 GUHL4 |
|||||||||||||||||||
|
VD315 GUHL4 |
Table 25.24. Dimensional and installation
dimensions, mm, frequency converters for
VD series engines
|
EMP size |
s |
|||||
|
ETU7801-39 ETU7801-41 ETU7801-44 |
475 475 605 1215 |
500 500 650 1260 |
Note. All types of EMF, except ETU7801-39, are equipped with fans.
Malized cabinets of one- or two-sided maintenance, used in large-block electric drives control devices. Degree of protection - IP00 in accordance with GOST 14254-80. The cooling of the inverter for a current of 80 A is natural air, and for yuks 125, 250, 500 A - forced air. Nominal values of climatic factors for EMF and IF - according to GOST 15150-69 and GOST 15543-70:
Height above sea level, m. . 1u(Yu
Ambient temperature, °С......... 1-40
Relative humidity, %.
at 20X........65
at 25 °С........SO
Technical data of engines of the VD series with a power of 30-132 kW of the main version with a speed of 1000 rpm, as well as modifications with a speed of 500, 750, 1500 rpm, while maintaining the torque of the main version b each laoapii-te are given in Table. 25.22.
The power supply of the VD series inverter is carried out from a three-phase industrial circuit with a voltage of 380 V and a frequency of 50 Hz. Rated voltage at the output of the inverter, i.e., on the armature winding of the EMF. 300 V. Independent excitation voltage 220 V.
EMF and IF operation mode - S1. Valve electric motors of the VD series are capable of double current overload for 10 s at the rated rotation frequency and an overload of 1.3/nom at the maximum rotation frequency while maintaining the same power. The power factor: and all standard versions of the VD series is 0 82.
The regulation range is often iu rotation of permanent magnet motors 1: 1000, including 1:4 up from the nominal.
Weight and size indicators of EMF and FC of valve electric drives are given in Table 1, respectively. 25.23, in fig. 25 6 and in table. 25.24.
Rice. 25.6. Overall and mounting dimensions EMP VD series
25.3.2. 200-3150 kW VD series brushless motors
VD series 200 - 3150 kW low-speed brushless motors are designed to operate in controlled electric drives of chemical and mill equipment, mine hoists, drilling rigs, pumps, fans, etc.
Table 25.25. Power scale for low-speed motors of the VD series
IN The set of a low-speed brushless motor of the VD series includes an electromechanical converter (EMC), a frequency converter (FC), a rotor position sensor (RPS), a tachogenerator (TG) and a power supply system for the excitation winding (Fig. 25.7).
Engines are classified by dimensions, useful power and maximum speed in accordance with Table. 25.25. The selection of the appropriate size of the inverter is carried out according to the useful power of the EMF.
The electromechanical converter of the low-speed VD series is structurally unified with serial synchronous motors. The three-phase armature winding is located on the stator, the excitation winding is on the rotor. A damper winding is placed in the tips of the poles of the inductor. The field winding can be powered in two ways. According to the first method (shown in Fig. 25.7), the system
Table 25.26. Overall, installation and connection dimensions, mm, and weight of electromechanical converters of VD series brushless motors (dimensions
WD800 - WD1600)
|
Size |
Maximum speed, rpm |
||||||
|
engine |
|||||||
|
WD8005 WD800M WD800b BfllOOOS VDOOM Bfll250S WD1250M WD1250L WD16008 WD1600M WD1600L |
|||||||
|
EMP size |
Weight, kg |
||||||||||
Rice. 25.7. Structural diagram of a low-speed motor of the VD series
is completely contactless. The supply voltage is supplied to the thyristor block of the excitation system bsv, which allows you to get an adjustable three-phase AC voltage at the output. It is fed to the stator winding of an asynchronous transformer AT, then straightened by a rotary rectifier BB and fed to the excitation winding EMP. According to the second method, the excitation power supply system is based on the traditional use of sliding current collection, carried out using two slip rings and brushes. In this case, the output BSV form an adjustable rectified voltage.
Electromechanical converters of standard sizes VD800, VD1000 and VD1250 are made with shielded rolling bearings, EMP of standard size VD1600 - with pedestal rolling bearings. Degree of protection EMP-1R44 according to GOST 17494-72. Cooling method - IC0541 according to GOST 20459-75.
Dimensional and installation-attach-
The actual dimensions of the EMF are given in Table. 25.26.
Low-speed VD series frequency converter includes a power section and a control system SU. In its structure, the power part of the inverter is a direct frequency converter. The inverter is powered from a three-phase industrial network with a voltage of 660 V and a frequency of 50 Hz. The inverter is connected to the network through a six-winding reactor.
Synchronization of the operation of the FC thyristors is carried out using the DPR. The value of the control angle is chosen in such a way as to provide maximum torque on the shaft.
Switching current in the thyristors of each group occurs due to the mains voltage. Switching current when switching groups is of a twofold nature: during start-up and acceleration - network, i.e. due to mains voltage, and at higher speeds - mixed, using the motor EMF.
Table 25.28. Power scale and overall dimensions of frequency converters
engines WD800- VD1600
|
dimensions |
|||
|
Inverter frame size |
Power, kW |
(length x height x |
Weight, kg |
|
x width), m |
|||
|
TNTRV-630-690UHL4 |
|||
|
TNTRV-1,2k-690UHL4 |
|||
|
TNTRV-2,0k-690UHL4 |
5.4 x 2.4 x 0.8 |
||
|
TNSHRV-2,5k-690U X L4 |
8.2 x 2.4 x 0.8 |
||
|
TNShRV-3,1k-690UHL4 |
The regulation of the frequency of rotation of valve motors is carried out within 0.1 - \n max. The change in efficiency and power factor during speed control is shown in Table. 25.27. If necessary, the control system is equipped with devices that provide electrical braking of the engine.
The power part of the inverter, as well as the power supply circuit of the excitation winding, are structurally placed in standard double-sided service cabinets. The degree of protection of the inverter - IP20 according to GOST 14254-80. Cooling-forced air. The overall dimensions of the inverter are given in Table. 25.28.
Nominal values of climatic factors for low-speed brushless motors of the VD series according to GOST 15150-69 and GOST 15543-70:
Height above sea level, m. 1000 Ambient temperature, °C.......... 1-40
Relative humidity at
25 ° С, %......... 80
25.3.3. PChVS series brushless motors
Thyristor electric drives according to the circuit of a brushless motor of the PCHVS series are designed to provide start-up and speed control of powerful high-voltage synchronous motors. The block diagram of the electric drive is shown in fig. 25.8, types of electric drives, overall
Rice. 25.8. Structural diagram of the electric drive according to the scheme of the brushless motor of the series
IN - rectifier; AND- inverter; SU V - rectifier control system; SUM - inverter control system; VR - input reactor; SR - smoothing reactor; DT- current sensor; DPR- rotor position sensor; DFN - EMF phase sensor; RV- excitation regulator; TG- tachogenerator; O V - excitation winding
the dimensions of the power boards and the control cabinet are given in Table. 25.29.
The electric drive provides: starting the motor, operation at any given speed in the range of 0.06-1 and ohm, reversing the motor, regenerative braking, optimization of transient processes by automatically limiting the current at the level of 1.5-2/nom, automatic synchronization of the motor with the network .
The electric drive includes an EMF, an inverter with a DC link, a thyristor exciter, and a control system. As an EMF in the PCVS series, we used
Table 25.29. Technical and weight and size data of brushless motors of the series
PCVS
commercially available synchronous motors. The use of a serial engine in terms of power is determined by its design features and electrical parameters. At the rated speed, the utilization factor lies within 0.8-0.9 due to some deterioration of cos f (as a rule, when operating from a current inverter with switching due to the motor EMF cos<р„ ом « 0,85-г 0,88 вместо 0,9), а также за счет дополнительных потерь от высших гармонических тока. Меньшее значение коэффициента использования относится к турбодвигателям.
The thyristor FC consists of two similar power modules: a rectifier and an inverter, made according to a three-phase bridge circuit. Each arm is made up of a series of connected thyristors in series with devices that provide uniform voltage division between thyristors, with devices for indicating the integrity of thyristors and protection in case of failure of an unacceptable number of semiconductor devices. The power module also includes current and voltage control devices and KS circuits that limit overvoltages when switching current between thyristors.
All types of PCVS in terms of power are provided with two basic designs of power modules for voltages of 6 and 10 kV. Depending on the rated current (630, 320, 200 A), there are three versions of modules for cooling devices: group forced, individual forced and natural. For currents above 630 A, parallel connection of frequency converters for a current of 630 A is performed.
Three modes are distinguished in the operation of the drive: the mode of forced current switching in the inverter phases (low-frequency mode), the current switching mode in the inverter phases under the action of the EMF of the EMF armature, the motor-network synchronization mode. The main operating mode is the current switching mode in the inverter phases under the action of the EMF of the EMF armature. In this mode, the control pulses applied to the inverter are synchronized according to the EMF EMF phase.
The amplitude of the armature current is determined by the output signal module of the speed controller and is worked out by a closed system of automatic current control by acting on the controlled rectifier. The excitation current is automatically adjusted as a function of the stator current in such a way that the amplitude of the switching
The EMF does not depend on the armature current and changes in proportion to the rotational speed.
In the low frequency rotation mode, the synchronization of the inverter control impulses is carried out by the logical signals of the rotor angular position sensor (RPS) relative to the stator. In case of oscillating LPR, the hour inerure in the process of starting, braking and reversing to low exposure hours 1 from can be determined by a smooth change in the frequency reference signal, in this variant the electric drive operates according to the scheme of a synchronous motor with frequency control.
In the mode of synchronization of the engine with the network, the frequency, phase and amplitude of the voltage of the EMF armature winding powered by the inverter are set equal to the corresponding network parameters, after which the armature winding is connected to the network, and the inverter is turned off.
Synchronous and asynchronous brushless DC motors are widely used in various fields of industrial production. In this article, we will consider in detail their device and principle of operation.
Principle of operation
The valveless brushless motor VMED, DVU is one of the types of electric motor that induces non-permanent magnetic poles on a ferromagnetic rotor. Torque is generated by magnetic resistance.
Photo - Brushless brushless motorThere are three types of brushless motors:
- Synchronous;
- Asynchronous;
- Inductor.
The design of a switched reluctance engine (VRD) includes two phase windings installed around diametrically opposite stator poles. When power is applied, the rotor moves in accordance with the stator poles, due to which the resistance of the magnetic field is minimized. The same principle is used at the heart of the operation of the switched reluctance motor.
Photo - AC motor In a highly efficient variable speed drive, the magnetism of the motor is optimized for reverse operation. Information about the position of the rotor is used to control the phase of the voltage supply. This ensures continuous torque and high efficiency. The signals are superimposed on the angular unsaturated phase of the inductance, with its maximum value corresponding to the minimum pole resistance. A positive moment is only produced at angles where the gradient inductance is also positive.
To protect the electronics from high volt-seconds, the phase current at low speeds must be limited. As a rule, this is achieved due to the hysteresis of the current. Special sensors are used to control the process.
Photo - Scheme of a brushless motor At higher speeds the current is limited. To optimize performance, the single pulse control voltage is used with a pre-aligned angle.
The trajectory of reactive energy clearly illustrates the mechanism of its transformation. The power domain represents the power that is converted into mechanical energy (or it has already been converted by the generator). In the event of a sudden power failure, residual or excess energy returns to the stator. The minimum influence of the magnetic field on the operation of the engine is its main difference from similar devices.
Advantages valve motor:
- Due to the small magnetic resistance, energy losses are minimized;
- High safety performance (ability to work at peak loads);
- Wide range of speeds;
- Soft shifting.
The disadvantages of automated brushless motors include:
- High noise level;
- Difficult to manage;
- Relatively high cost compared to similar devices.
Video: what brushless motors consist of
Design
The traction valve motor (Interskol catalog, Lenze, Fighter for ESP, ESP) consists of sensors that indicate the position of the rotor of a synchronous type machine. The combination of these mechanisms is called the electromechanical part of the engine. The control part of the device includes a microcontroller and a power bridge. The engine control unit belongs to the logistical non-constructive section of the system.
Photo - Valve reluctance motor The mechanical part of the device is a synchronous drive assembled from insulated steel sheets. This design contributes to the reduction of eddy currents generated in the winding and rotor.
Hall sensors are used for normal operation of the device. If there are no indicator devices in the brushless motor, the signals go directly to the magnetic installation. The same devices control the reverse mode. This is necessary so that the engine does not stop when diving, and also makes it possible to remotely control its operation and change settings. This function is necessary for oil, coal, gas and drilling operations.
Photo - The principle of operation of a submersible motor The stepper microprocessor processes all data on the position of the rotor, according to the settings of which the PWM signals are controlled. It should be noted that at a low level of these signals, their amplification will be required. For this purpose, special devices are used that work on the principle of microtransformers.
Technical specifications:
| Brand, type | Torque, Nm | Length, mm | The maximum allowable frequency, min -1 | Weight, kg |
| DMV 55 | 0,05; 1 | 61 | 420; 1800 | 0,4 |
| 5 DVM 55 | 0,23; 0,47; 0,7; 1,3 | 218 | 2000; 3000; 4000; 6000 | 4,5 |
| 5 DVM 155 | 2,3; 3,5; 4,7; 7 | 342 | 2000; 3000; 4000; 6000 | 13 |
| 5 DVM 165 | 10; 13; 17; 23 | 536 | 1000; 2000; 3000; 4000 | 67 |
| 5 DVM 215 | 23; 35; 47; 70 | 637 | 1000; 2000; 3000; 4000 | 28 |
Photo - Parameters of brushless motors Engines are calculated according to the following formulas:
Phase balance formula: IRΣ+ EΣ= U
EMF sum – E1= Emsin(∂+∂0), EMF amplitude – Em= ko1pФw1Ω = (ko1pФN1Ω) / 2
Designation of the motor commutation angle:
Device types
Valve motors can operate on AC or DC. In addition, they are usually divided into the following types:
- single phase device. These are the simplest brushless motors with the fewest connections between the machine and the electronics. The disadvantages of single-phase devices include: ripple, high torque, as well as the impossibility of starting at all angular positions. Single-phase motors are widely used in machines where high speed is required.
- two-phase engine. This motor, during operation, activates the air gap or, with additional adjustment, creates an asymmetry in the rotor poles. This device is installed in machines where the connection between the stator and the winding is critical. Disadvantages include high torque and ripple, which can be detrimental.
- three-phase engine. This disc motor is used to start and generate torque without using a lot of phases. This type of engine is used in various industries, and sometimes in domestic conditions. This is the most popular design of all presented. Alternative 3-phase machines with an even number of poles are the best solution for applications where a combination of high power and low speed is needed, such as in pumps. Disadvantages of three-phase motors: high torque and increased noise level.
- Devices with four phases. These motors have significantly reduced torque and pulsations, but the scope of the devices is limited by high cost and high power.
Unfortunately, it is almost impossible to develop and create a working submersible or multi-phase valve motor with your own hands, it is much easier to buy the right model. In different cities of Russia and Ukraine, the price of brushless motors can vary significantly. The lower step will be about 8,000 thousand rubles, the upper one can reach 20,000, depending on the scope and manufacturer
In many areas of production, brushless motors are used, in particular, in oil wells, drilling rigs, drive mechanisms, air cooling systems in chemical plants.
Piston aircraft engine VD-4K (M-253K).
Developer: OKB-36 (Rybinsk)
Country: USSR
Start of development: 1949
Built: 1950
M-253K (VD-4K) is a Soviet aircraft engine of a combined type (turbocompound), made according to the block star scheme. The engine is a 24-cylinder block star (six blocks of 4 cylinders each).
The history of the combined VD-4K engine is not quite common and has its roots in the pre-war period. The fact is that they began to create it not in a specialized aircraft engine design bureau, but at one of the departments of the Moscow Aviation Institute. At the end of 1938, the then People's Commissar of Aviation Industry, M.M. Usually, the parameters of a new development in the field of engine building are selected on the basis of a long-term analysis of trends and future needs of our own aircraft industry, as well as the state of similar branches of technology abroad. M.M. Kaganovich, in general, not a bad person, but who got to the position for his devotion to ideas and leaders, a nomenklatura soul (today the director of the bathhouse, tomorrow the head of the Aviation Industry), being not very knowledgeable in all the intricacies of the “Preliminary selection of the main parameters for design", simply multiplied by two the data of the M-105 engine. Hence it turned out that the new engine had to develop a power of 2100-2300 hp. at an altitude of 8000 m.
G.S. Skubachevsky with a group of students and graduate students worked out three layout options for a 24-cylinder engine: X-shaped, H-shaped and a kind of four-row star with six cylinders in each row. The last option turned out to be the most successful: its diameter was only 1065 mm, like the M-11 motor. It was assumed that a three-speed centrifugal supercharger would be used to increase the altitude, and the efficiency of the power plant would be raised by the counter-rotation screws.
In July 1939, a government decree appeared on the design of the engine, called the M-250. A special KB-2 is being created at MAI, it is staffed from students, postgraduates and CIAM employees, teachers from other MAI departments were also involved. Design work began and already on April 1, 1940, the M-250 project was being passed by the Air Force Research Institute, a decision was made to build an experimental engine at plant No. 16 in Voronezh. The first launch of the M-250 at the stand was made on the fateful day of June 22, 1941. On tests, the engine showed the declared power of 2500 hp. Then sporadic work on the engine in the conditions of war and evacuation. They really returned to the topic in 1946, when a task was received for an engine with a capacity of 3500 hp for new heavy Tupolev machines. OKB-36 in Rybinsk under the leadership of V.A. Dobrynin, based on the theoretical and practical groundwork for the M-250, in a short time creates the M-251TK (VD-3TK) engine.
In January 1949, OKB-36 proposes, on the basis of the M-251TK, to create a new combined engine M-253K with a maximum power of 4300 hp. and with specific fuel consumption in cruising modes within 0.185 - 0.195 kg / hp.h. The work was carried out within the framework of the design of the aircraft "85", the topic determined at that time for the MAP as the most important.
The M-253K project was based on the following principles:
- minimal changes in the design of the M-251TK, which was justified by the high accuracy and reliability of the components and assemblies of the M-251TK, confirmed during testing, as well as the short time allotted for development;
- maximum use of exhaust gas energy in order to minimize the boost of the main piston engine in terms of boost and obtain the specified fuel consumption (boost, in comparison with the M-251TK, was made in takeoff mode by only 7%).
The M-253K was supposed to be a combined unit consisting of two power units, an engine with three impulse turbines and a turbocharger with a variable jet nozzle, which received energy from the engine exhaust gases. The use of impulse turbines made it possible to improve efficiency by 10-11%, the use of a powerful turbocharger with an altitude of 11,000 m, with high efficiency in all modes, using the reaction of exhaust gases in an adjustable jet nozzle, made it possible to increase operational efficiency by 20-25%.
In September 1949, a working draft was completed and drawings of new units were developed - impulse turbines and a TK-36 turbocharger. In the course of the design, the compression work in the monitoring station was reduced, and the injection of a water-to-alcohol mixture was used for forced modes. As a result of the work carried out, OKB-36 managed to obtain an efficient and quite reliable unit, the basis of which was a used piston engine. Its rational scheme, in the form of a four-row six-block star with liquid cooling, made it possible to create a compact and rigid design that provided a low specific weight and high performance data.
In the same September 1949, Decree No. 3929-1608 for the 85 aircraft put forward the following basic requirements for the M-253K engine:
- takeoff power - 4300 hp;
- rated power at an altitude of 8000-9000 m - 3200 hp;
- specific fuel consumption in the mode of 0.5-0.6 rated power - 0.185-0.195 kg / hp h;
- dry weight (without pressurization unit) - 1900 kg.
In December 1950, it was necessary to submit the engine to the State 100-hour bench tests. For bench and flight tests, it was necessary to build 20 copies of the M-253K in a short time.
In January 1950, the first engine was ready, then 23 more engines were built. In June-December, 100-hour factory tests are carried out on several engines. In December 1950, the M-253K, together with the TK-36, was presented for State bench tests, which it completed with positive results in early February 1951, confirming the full compliance of all parameters with the given ones, as well as the reliability of the design. At the end of the State Tests, the M-253K receives the designation VD-4K.
VD-4K engine.
In the second half of 1950, the VD-4K was installed on the Tu-4LL flying laboratory. By the end of 1950, the first stage of flight tests was completed. One experienced VD-4K was tested, the other three were full-time ASh-73TK. These works were carried out by the LII and their positive results became a good reason for installing these engines on the first 85 aircraft. Competitors from OKB-19, with their more powerful, but more "raw" ASh-2K, did not have time for the first flight. Further tests and refinements of the VD-4K were carried out during the implementation of the joint test program on the 85 aircraft, as well as the parallel test flights of the Tu-4LL with the VD-4K. The laboratory tested all measures to refine the engine. This contributed to the acceleration of the process of joint testing. In particular, an additional fan in the engine cooling system was worked out on the Tu-4LL.
The VD-4K was finally assigned to the aircraft "85" at the end of May 1951, when it was decided to raise the "85" on the first flight with the VD-4K, since the ASh-2K was still suffering from "childhood illnesses". In the course of fine-tuning the Tu-85 engine installation, a forced cooling fan was installed on the VD-4K. Power was transmitted using a single-shaft planetary gearbox with an integrated engine ventilation system to the propeller, a five-blade AB-55 or a four-blade AB-44.
With the official completion of the Tu-85 creation program, work on the VD-4K was gradually curtailed. The creation and flight tests of the VD-4K became the pinnacle of the development of piston aircraft engine building. This required solving a wide range of problems in the field of strength and dynamics of machines, heat engineering, gas dynamics, materials science and production technology.
For the creation of VD-4K, a group of workers from OKB-36 and TsIAM was awarded the Stalin Prize in 1951.
Cylinder diameter, mm: 148
Piston stroke, mm: 144 mm
Number of cylinders: 24
Dry weight, kg: 2065 (without turbocharger)
Volume, l: 59.43
Power, hp: 3250/4300
Compression ratio: 7.0
Compressor: single stage single speed ARC
Cooling system: liquid cooling.
List of sources:
V.R. Kotelnikov. Domestic aviation piston engines.
V. Rigmant. The last piston bombers.
TsAGI. Aircraft building in the USSR 1917-1945. Book II.
