RU2821420C1 - Device for direct torque control of asynchronous motor based on three-phase three-level independent inverter npc - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electrical engineering and can be used to control a three-phase three-level voltage inverter, the control system of which uses a method of direct control of the motor torque. Device for direct torque control of an asynchronous motor based on a three-phase three-level self-contained inverter NPC by installing a stator flux linkage setting unit, a seven-position relay torque controller and a three-command vector selection unit allows to increase accuracy and speed of reaction of the asynchronous motor torque control system.

EFFECT: increased accuracy and speed of reaction of the asynchronous motor torque control system.

1 cl, 1 dwg

Description

The invention relates to the field of electrical engineering and can be used to control a three-phase three-level voltage inverter, the control system of which uses the method of direct motor torque control.

A device for direct self-control of an asynchronous motor is known (patent RU No. 34286, published on November 27, 2003), which includes a torque generator, a flux linkage controller, a voltage generator block with a voltage sensor, a current generator block with two current sensors, a torque generator block and flux linkage block, coordinate converter, two adders, three relay controllers, pulse selector block. The pulse selector block is connected to a voltage inverter, which is connected to a power source. A current sensor is included in one of the winding phases. A pair of outputs of the current generator block is connected to the torque and flux generator block. Two other flux linkage generator blocks are connected to a voltage generator block, which is connected to a torque generator and coordinate converter block. Three outputs of the coordinate converter are connected to the inputs of the first relay controller, the other two inputs of which are connected to the flux linkage controller.

The disadvantage of the device is the presence of three relay regulators, which leads to low engine speed.

A device for direct control of the speed of an AC motor is known (patent RU No. 2336624, published on October 20, 2008), which is a complex system that includes a frequency and voltage converter with two inputs and an AC motor. A speed sensor and a mechanical torque sensor are installed on the motor output shaft. The main difference of this device is the presence of a feedback vector generating unit, which is the sum of the DC motor speed signals and its mechanical torque with coefficients configured so that the feedback vector transfer function does not contain oscillatory links at all supply voltage frequencies and motor speeds. This feedback vector is fed to the high gain inverting input of the speed controller.

The disadvantage is the presence of a vector selection block, which is designed without taking into account minimizing the number of switches of the inverter switches, which leads to a decrease in the efficiency of a three-phase three-level voltage inverter.

A DC motor control device is known (patent RU No. 2375811, published on December 10, 2009), which is an electrical power supply system that includes a power source, a filter, an inverter and the presence of the first and second windings of a pulse transformer, each of which consists of two identical parts . The device includes four power switches, two capacitive storage devices and a load control unit. The first and second terminals of the transformer windings are connected to the first power terminals of the first, second, third and fourth switches. The second load terminal is connected to the first power terminals of the fifth and sixth switches. The second terminals of the last keys are connected to the middle terminals of the first and second windings of the transformer, which are also connected to the first power terminals of the first and second double-sided keys. The control pins of the first, second, third, fourth, fifth and sixth keys are connected to the corresponding outputs of the first driver.

The disadvantage of the device is that the presence of the first and second windings of the pulse transformer leads to a decrease in the efficiency of the motor.

A control device for a three-phase active voltage rectifier is known (patent RU No. 161102, published 07/03/2015), which includes current and voltage sensors of the power source, as well as a rectified voltage sensor. A pulse-width modulator, a rectified voltage adjuster, and a power supply reactive current adjuster are also present. The control system includes a unit for separating the symmetrical components of positive and negative sequence voltages in the power source voltage curve. Also present is a phase-locked loop block, a block for converting power supply currents from a stationary coordinate system (ABC) to a rotating coordinate system (d-q), a block of proportional-integral regulators of the active and reactive components of the power source current, a block for converting positive sequence control voltages from a rotating coordinate system (d-q) into a fixed coordinate system (α-β).

The disadvantage of the device is the presence of a pulse-width modulator, a rectified voltage and reactive current setter of the power supply, which leads to an increase in harmonic distortion of individual phase currents of active rectifiers and a significant fluctuation in the DC link voltage.

A control device for a high-voltage frequency converter is known (patent RU No. 157682, published on December 10, 2015), which includes a power supply voltage sensor, a three-phase power supply, a voltage asymmetry calculation unit, a high-voltage converter and its control system, a DC link voltage adjuster and synchronous machine. The first fiber-optic output of the high-voltage converter is connected through the power supply current sensor to the third input of the frequency converter control system. The fourth input of the control system is connected to the output of the power supply voltage sensor, and the fifth input is connected to the output of the DC link voltage sensor. Three inputs of the latter are connected to the second, third and fourth information outputs of the high-voltage frequency converter. The sixth input of the frequency converter control system with a symmetrical power supply voltage is connected to the reactive current set point.

The disadvantage of the known device is the presence of a high-voltage converter, which leads to an increase in the harmonic distortion of phase currents and a significant fluctuation in the DC link voltage.

A device for direct torque control of a synchronous motor is known (patent RU No. 2662151, published on July 24, 2018), adopted as a prototype, which includes a rotation speed setting unit, a unit for generating a given flux linkage and electromagnetic torque, relay regulators of the flux linkage and electromagnetic torque, a base preselection unit voltage vector, voltage inverter control signal generation unit, three-phase three-level inverter, current and voltage sensors, rotor angular position sensor, speed sensor. A matching block for two groups of basic voltage vectors, a block for selecting basic voltage vectors and a relay voltage balancing regulator provide control of the power part of the system, guaranteeing stability and control accuracy.

The disadvantage of the known device is the presence of a block for preliminary selection of the base voltage vector and a block for generating a given flux linkage and electromagnetic torque, which leads to a decrease in the efficiency of a three-phase three-level autonomous voltage inverter when choosing the base voltage vectors.

The technical result is to increase the accuracy and speed of response of the torque control system of an asynchronous motor.

The technical result is achieved by additionally installing a block for setting the stator flux linkage, the output of which is connected to the first input of the stator flux linkage control block, and the second input is connected to the first output of the block for calculating the current values of the stator flux linkage, torque and rotor position angle, the voltage vector selection block is connected to the output a two-position relay regulator of the stator flux linkage, the input of which is connected to the output of the stator flux linkage control block, the second input of the voltage vector selection block is connected to the output of a seven-position relay torque regulator, the input of which is connected to the output of the torque control block, the third input of the voltage vector selection block is connected to the third output of the block calculation of current values of stator flux linkage, torque and rotor position angle.

The device is illustrated by the following figure:

fig. 1 - functional diagram of the device, where:

1 - block for setting the stator flux linkage;

2 - rotation speed setting block;

3 - stator flux linkage control unit;

4 - rotation speed control unit;

5 - torque control unit;

6 - two-position relay regulator of stator flux linkage;

7 - seven-position relay torque controller;

8 - voltage vector selection block;

9 - block for generating control signals for inverter keys;

10 - three-phase three-level autonomous inverter NPC;

11 - current sensor;

12 - inverter output phase voltage sensor;

13 - asynchronous motor;

14 - engine speed sensor;

15 - block for calculating the current values of stator flux linkage, torque and rotor position angle;

16 - direct current source.

The device for direct torque control of an asynchronous motor based on a three-phase three-level autonomous inverter NPC contains a unit for setting the stator flux linkage 1 (Fig. 1), the output of which is connected through a fiber optic cable with the first input of the stator flux linkage control unit 3, and the second input through a fiber-optic cable with the first output of the unit for calculating the current values of the stator flux linkage, torque and rotor position angle 15. The output of the rotation speed setting unit 2 is connected through a fiber-optic cable with the first input of the rotation speed control unit 4, and the second input is connected via a fiber-optic cable to the engine speed sensor 14. The output of the rotation speed control unit 4 is connected via a fiber-optic cable to the first input of the torque control unit 5, the second input of which is connected through a fiber-optic cable with the second output of the unit for calculating the current values of the stator flux linkage, torque and rotor position angle 15. The first input of the voltage vector selection unit 8 is connected via a fiber-optic cable to the output of a two-position relay regulator of the stator flux linkage 6, the input of which is connected through an optical fiber. fiber cable with the output of the stator flux linkage control unit 3. The second input of the voltage vector selection unit 8 is connected via a fiber-optic cable to the output of the seven-position relay torque controller 7, the input of which is connected via a fiber-optic cable to the output of the torque control unit 5. The third input of the selection unit voltage vector 8 is connected via a fiber-optic cable to the third output of the unit for calculating the current values of stator flux linkage, torque and rotor position angle 15. The output of the voltage vector selection unit 8 is connected via a fiber-optic cable to the input of the inverter key control signal generation unit 9, the output of which connected via a fiber-optic cable to the information input of the three-phase three-level autonomous inverter NPC 10, the electrical input of which is connected via an electrical cable to a direct current source 16. The electrical output of the three-phase three-level autonomous inverter NPC 10 is connected via an electrical cable to the electrical input of the current sensor 14, electrical output which is connected through an electric cable to an asynchronous motor 13. The information output of the current sensor 11 is connected through a fiber-optic cable to the first input of the unit for calculating the current values of stator flux linkage, torque and rotor position angle 15, the second output of which is connected through a fiber-optic cable to the information output inverter output phase voltage sensor 12.

A direct torque control device for an asynchronous motor based on a three-phase three-level autonomous NPC inverter operates as follows. The block for calculating the current values of the stator flux linkage, torque and position angle of the rotor 15 based on signals from the current sensor 11 and the output phase voltage sensor of the inverter 12 generates three output signals.

At the first output of the block for calculating the current values of the stator flux linkage, torque and position angle of the rotor 15, a signal of the current value of the stator flux linkage Y _s is generated, which is fed to the second input of the stator flux linkage control unit 3, and the first input of which is supplied with a signal from the stator flux linkage setting unit 1. The output signal of the stator flux linkage control unit is supplied to the input of the on-off relay stator flux linkage regulator 6, where the command dY _s is generated to increase or decrease the current value of the stator flux linkage Y _s . The specified command is supplied to the first input of the voltage vector selection block 8.

At the second output of the block for calculating the current values of the stator flux linkage, torque and rotor position angle 15, a signal of the current value of torque M is generated, which is supplied to the second input of the torque control block 5. At the output of the rotation speed control block 4, after comparing the current one, which is received from the rotation speed sensor 14, and the set value of the rotation speed, which is received from the rotation speed setting unit 2, a torque command is formed, which is supplied to the first input of the torque control unit 5. The output signal of the torque control unit, after comparing the values from the first and second inputs, is fed to the input of the seven-position relay controller torque 7, where a command dM is generated to increase or decrease the current torque M. The specified command is supplied to the second input of the voltage vector selection block 8. The seven-position relay torque controller 7 allows you to increase the accuracy of torque control of an asynchronous motor.

At the third output of the block for calculating the current values of the stator flux linkage, torque and rotor position angle 15, a signal of the current rotor position angle is generated. The specified command is supplied to the third input of the voltage vector selection block 8.

The voltage vector selection block 8 uses the three above commands to determine the voltage vector, the signal of which is supplied to the input of the inverter key control signal generation block 9, where a command is generated to control the three-phase three-level autonomous inverter NPC 10. Three-phase three-level autonomous inverter NPC 10, which is powered from a source DC 16, according to the specified command, an output voltage is generated to control the asynchronous motor 13 in accordance with the rotation speed setting. The voltage vector selection block 8 allows you to increase the response speed of the torque control system of an asynchronous motor.

A device for direct torque control of an asynchronous motor based on a three-phase three-level autonomous NPC inverter by installing a stator flux linkage setting unit, a seven-position relay torque controller and a vector selection unit for three commands allows increasing the accuracy and speed of response of the torque control system of an asynchronous motor.

Claims (1)

A device for direct torque control of an asynchronous motor based on a three-phase three-level autonomous inverter NPC, containing a rotation speed setting unit, the output of which is connected to the first input of the rotation speed control unit, an inverter key control signal generation unit, the output of which is connected to the control input of a three-phase three-level voltage inverter, electrical the input of which is connected to a constant voltage source, and the electrical output of the voltage inverter is connected to an asynchronous motor through a current sensor, and the information output of the three-phase three-level voltage inverter is connected to the output phase voltage sensor of the inverter, and the outputs of the above two sensors are connected, respectively, to the first and second inputs of the calculation unit current values of the stator flux linkage, torque and rotor position angle, the engine is equipped with a speed sensor, the output of which is connected to the second input of the rotation speed control unit, characterized in that a stator flux linkage setting unit is additionally installed, the output of which is connected to the first input of the stator flux linkage control unit, and the second input with the first output of the block for calculating the current values of the stator flux linkage, torque and rotor position angle, the voltage vector selection block is connected to the output of the two-position relay regulator of the stator flux linkage, the input of which is connected to the output of the stator flux linkage control block, the second input of the voltage vector selection block is connected to the output a seven-position relay torque controller, the input of which is connected to the output of the torque control unit, the third input of the voltage vector selection unit is connected to the third output of the unit for calculating the current values of the stator flux linkage, torque and rotor position angle.

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