A control method for a permanent magnet synchronous motor back-to-back test system

Abstract

The invention discloses a control method for a counter-rotating test system of a permanent magnet synchronous motor. The counter-rotating test system is composed of a multi-phase permanent magnet synchronous motor, a grid-side rectifier and a machine-side inverter. One or more sets of three-phase stator windings of the multi-phase permanent magnet synchronous motor operate in a torque control mode, and the remaining three-phase stator windings operate in a speed control mode. The control method of the invention designs a disturbance observer, and uses the compensation voltage observed by the observer to form a feedforward term to improve the stability of the system and suppress the adverse effects of the magnetic coupling between different three-phase stator windings on the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control, and particularly relates to a control method for a permanent magnet synchronous motor counter-rotating test system. Background Art

[0002] High-power multiphase permanent magnet synchronous motors and converters, as energy conversion devices, are widely used in fields such as ship propulsion, urban light rail, locomotive traction, aerospace, etc.

[0003] For the test under load, adopting the method of directly connecting a resistive-inductive load has disadvantages such as large power consumption and inflexible test. Based on the power circulation method of the converter and the motor in counter-rotation, the power consumption can be significantly reduced and the test flexibility can be improved.

[0004] In the traditional power circulation method of the converter and the motor in counter-rotation, usually two independent converters are used to control two independent motors respectively, and the configuration method of connecting the two motors through a mechanical device increases the volume and cost of the motor counter-rotation test system, and at the same time, the control of the entire system becomes more complex. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a control method for a permanent magnet synchronous motor counter-rotating test system with low cost and convenient operation and test.

[0006] The technical solution adopted by the present invention to solve its technical problems is: a control method for a permanent magnet synchronous motor counter-rotating test system, based on a counter-rotating test system composed of a multiphase permanent magnet synchronous motor, a grid-side rectifier, and a machine-side inverter, wherein one or more sets of three-phase stator windings of the multiphase permanent magnet synchronous motor operate in torque control mode, and the remaining one or more sets of three-phase stator windings operate in speed control mode; the method includes the following steps:

[0007] Step S1, set the xth, …, yth sets of three-phase stator windings of the multiphase permanent magnet synchronous motor to operate in speed control mode, and the dq-axis voltage / current of the xth, …, yth sets of three-phase stator windings are u dqx / i dqx 、…、u dqy / i dqy respectively, and the mth, …, nth sets (x, y, m, n = 1, 2, 3, …) of three-phase stator windings operate in torque control mode, and the dq-axis voltage / current of the mth, …, nth sets of three-phase stator windings are u dqm / i dqm 、…、u dqn / i dqn respectively. Take the dq-axis voltage / current of each set of three-phase stator windings as the input quantity of the observer, and the output quantity of the observer is the dq-axis compensation voltage Δu dqx, Δu dqy , …, Δu dqm , Δu dqn and the dq-axis current observations i dqxe , i dqye , …, i dqme , i dqne ;

[0008] Step S2, use the dq-axis current observations i dqxe , i dqye , …, i dqme , i dqne output from the observer as the negative feedback signal of the corresponding current loop PI controller;

[0009] Step S3, add the dq-axis compensation voltages Δu dqx , Δu dqy , …, Δu dqm , Δu dqn output from the observer to the output voltages u dqxpi , u dqypi , …, u dqmpi , u dqnpi output from the corresponding current loop PI controller respectively. The superimposed quantity is used as the input of the PWM modulation module to output a pulse drive signal to control the corresponding three-phase stator windings.

[0010] For the control method of the permanent magnet synchronous motor back-to-back test system described above, the state space model of the observer in step S1 is:

[0011]

[0012]

[0013] where u s , y, z1, z2 are the dq-axis voltages, dq-axis currents, dq-axis current observations, and dq-axis compensation voltages of the three-phase stator windings respectively. R0 and α0 are the virtual phase resistance of the motor and the reciprocal of the dq-axis inductance of the motor respectively. β1 and β2 are the gain coefficients of the observer.

[0014] For the control method of the permanent magnet synchronous motor back-to-back test system described above, the virtual resistance term R0 of the observer is R0 = 10R s , where R s is the phase resistance of the multi-phase permanent magnet synchronous motor.

[0015] For the control method of the permanent magnet synchronous motor back-to-back test system described above, the gain coefficients β1 and β2 of the observer are respectively:

[0016] β1 = 2ω0 + R0

[0017]

[0018] Among them, ω0 is the bandwidth of the observer.

[0019] For the control method of a permanent magnet synchronous motor back-to-back test system, the bandwidth ω0 of its observer is ω0 = 5ω c ~10ω c , where ω c is the current loop bandwidth.

[0020] The present invention has the following technical effects: The present invention uses the compensated voltage observed by the observer to form a feedforward term to improve the stability of the system, suppresses the adverse effects of the magnetic coupling between different three-phase stator windings on the system performance, and while reducing the system cost and structural complexity, the back-to-back test operation is convenient to implement and has practical engineering application value. Description of the Drawings

[0021] Figure 1 is a schematic diagram of the topology structure of the back-to-back test system of the present invention;

[0022] Figure 2 is the overall block diagram of the control method of the back-to-back test system of the present invention;

[0023] Figure 3 is a schematic diagram of the topology structure of the back-to-back test system of a dual three-phase Y-shifted 30° permanent magnet synchronous motor;

[0024] Figure 4 is the overall block diagram of the control method of the back-to-back test system of a dual three-phase Y-shifted 30° permanent magnet synchronous motor. Detailed Embodiments

[0025] To further illustrate the purpose and technical solution of the present invention, the following will be described in further detail with reference to specific embodiments of the drawings.

[0026] As Figure 1 shown, the permanent magnet synchronous motor back-to-back test system disclosed by the present invention includes a multi-phase permanent magnet synchronous motor, a grid-side rectifier, and a machine-side inverter. One or more sets of three-phase stator windings of the multi-phase permanent magnet synchronous motor operate in the torque control mode, and the other one or more sets of three-phase stator windings operate in the speed control mode. As Figure 2 shown, a control method for a permanent magnet synchronous motor back-to-back test system disclosed by the present invention includes the following steps:

[0027] Step S1, set the xth to yth sets of three-phase stator windings of the multi-phase permanent magnet synchronous motor to operate in the speed control mode, and the dq-axis voltage / current of the xth to yth sets of three-phase stator windings are u dqx / i dqx 、…、u dqy / i dqy, the m-th, …, n-th sets (x, y, m, n = 1, 2, 3, …) of three-phase stator windings operate in the torque control mode, and the dq-axis voltages / currents of the m-th, …, n-th sets of three-phase stator windings are u dqm / i dqm , …, u dqn / i dqn . Taking the dq-axis voltages / currents of each set of three-phase stator windings as the input quantities of the observer, the output quantities of the observer are the dq-axis compensation voltages Δu dqx , Δu dqy , …, Δu dqm , Δu dqn and the observed values of the dq-axis currents i dqxe , i dqye , …, i dqme , i dqne ;

[0028] Step S2, taking the observed values of the dq-axis currents i dqxe , i dqye , …, i dqme , i dqne output by the observer as the negative feedback signals of the corresponding current loop PI controllers;

[0029] Step S3, adding the dq-axis compensation voltages Δu dqx , Δu dqy , …, Δu dqm , Δu dqn output by the observer to the output voltages u dqxpi , u dqypi , …, u dqmpi , u dqnpi of the corresponding current loop PI controllers respectively. The superimposed quantity is used as the input of the PWM modulation module, and the output pulse drive signal controls the corresponding three-phase stator windings.

[0030] The state space model of the observer is:

[0031]

[0032]

[0033] where u s , y, z1, z2 are the dq-axis voltage, dq-axis current, observed value of the dq-axis current, and dq-axis compensation voltage of the three-phase stator winding respectively, R0, α0 are the virtual phase resistance of the motor and the reciprocal of the dq-axis inductance of the motor respectively, and β1, β2 are the gain coefficients of the observer.

[0034] The virtual resistance term R0 of the observer = 10R s , where R sis the phase resistance of the multi-phase permanent magnet synchronous motor.

[0035] The gain coefficients β1 and β2 of the observer are respectively:

[0036] β1 = 2ω0 + R0

[0037]

[0038] where ω0 is the bandwidth of the observer. The bandwidth ω0 of the observer = 5ω c ~10ω c where ω c is the current loop bandwidth.

[0039] The present invention will be further described in detail below by taking the double three-phase Y-shifted 30° permanent magnet synchronous motor back-to-back test system as an example in conjunction with the accompanying drawings.

[0040] As Figure 3 shown, a double three-phase Y-shifted 30° permanent magnet synchronous motor back-to-back test system includes a double three-phase Y-shifted 30° permanent magnet synchronous motor, a grid-side rectifier, a machine-side inverter, and a control system. The double three-phase Y-shifted 30° permanent magnet synchronous motor is a double three-phase permanent magnet synchronous motor with separated centers. The first set of three-phase stator windings is A1B1C1, and the center point is O1. The second set of three-phase stator windings is A2B2C2, and the center point is O2. The three-phase stator windings A1B1C1 operate in the speed control mode, and the three-phase stator windings A2B2C2 operate in the torque control mode. The grid-side rectifier is a general three-phase two-level topology, and the three-phase AC input currents are i ai 、i bi 、i ci , and the DC bus voltage controlled by the rectifier is U dc , and it can also be any AC / DC converter topology. The machine-side inverter is a general three-phase two-level topology, and the three-phase AC output currents are i ao 、 i bo 、i co , and the DC bus voltage controlled by the inverter is U dc , and it can also be any DC / AC converter topology.

[0041] As Figure 4 shown, a control method for a double three-phase Y-shifted 30° permanent magnet synchronous motor back-to-back test system includes the following steps:

[0042] Step 1, set the first set of three-phase stator windings A1B1C1 of the double three-phase Y-shifted 30° permanent magnet synchronous motor to operate in the speed control mode, and its dq-axis voltage / current is u dqm / i dqm, the second set of three-phase stator windings A2B2C2 operates in torque control mode, and its dq-axis voltage / current is u dqn / i dqn , taking the dq-axis voltage / current of each set of three-phase stator windings as the input of the observer, and the output of the observer is the compensation voltage Δu dqm 、Δu dqn and the observed values of dq-axis current i dqme 、i dqne ; the state space model of the constructed observer is:

[0043]

[0044]

[0045] where u s 、y、z1、z2 are the dq-axis voltage, dq-axis current, observed value of dq-axis current, and compensation voltage of dq-axis of the three-phase stator windings of the motor respectively; R0, α0 are the virtual phase resistance of the motor and the reciprocal of the dq-axis inductance of the motor respectively; β1, β2 are the gain coefficients of the observer. Among them, the virtual resistance term R0 of the observer = 10R s , R s is the phase resistance of the motor; the gain coefficients β1, β2 of the observer are respectively:

[0046] β1 = 2ω0 + R0

[0047]

[0048] ω0 is the bandwidth of the observer. The bandwidth of the observer is designed as ω0 = (5 - 10)ω c , ω c is the current loop bandwidth.

[0049] Step 2, taking the observed values of dq-axis current i dqme 、i dqne output by the observer as the negative feedback signals of the corresponding current loop PI controllers.

[0050] Step 3, adding the compensation voltages Δu dqm 、Δu dqn output by the observer to the reference voltages u dqmpi 、u dqnpi output by the corresponding current loop PI controllers respectively, and using the superimposed quantity as the input of the PWM modulation module to output pulse drive signals to drive the converter.

[0051] For a dual three-phase permanent magnet synchronous motor with a separated center point, rotor magnetic field orientation control is performed on its two sets of stator windings with orientation angles of θ and θ - 30° respectively. Assume that the reference voltage output by the current loop of the first set of stator windings is u dqmpi , and the components of the three-phase stator current in the dq coordinate system are i dqm , and the reference voltage output by the current loop of the second set of stator windings is u dqnpi , and the components of the three-phase stator current in the dq coordinate system are i dqn .

[0052] The dq-axis voltage formula of the three-phase stator winding is expressed as:

[0053] U dqmn = U dqmnpi + ΔU dqmn .

[0054] The above embodiments only exemplarily illustrate the principles and effects of the present invention, as well as some applied embodiments. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A control method for a permanent magnet synchronous motor back-to-back test system, characterized in that: A back-to-back test system composed of a multiphase permanent magnet synchronous motor, a grid-side rectifier and a machine-side inverter, wherein one or more sets of three-phase stator windings of the multiphase permanent magnet synchronous motor operate in torque control mode, and the remaining three-phase stator windings operate in speed control mode; including the following steps Step S1, set the x-th to y-th sets of three-phase stator windings of the polyphase permanent magnet synchronous motor to operate in the speed control mode. The dq-axis voltages / currents of the x-th to y-th sets of three-phase stator windings are u dqx / i dqx ,..., u dqy / i dqy . The m-th to n-th sets of three-phase stator windings operate in the torque control mode. The dq-axis voltages / currents of the m-th to n-th sets of three-phase stator windings are u dqm / i dqm ,..., u dqn / i dqn . Take the dq-axis voltages / currents of each set of three-phase stator windings as the input quantities of the observer. The output quantities of the observer are the dq-axis compensation voltages Δu dqx , Δu dqy ,..., Δu dqm , Δu dqn and the dq-axis current observation values i dqxe , i dqye ,..., i dqme , i dqne ; Step S2, using the observed dq-axis current values i dqxe , i dqye , …, i dqme , i dqne as the negative feedback signals of the corresponding current loop PI controllers; Step S3: Add the dq-axis compensation voltages Δu dqx , Δu dqy , …, Δu dqm , and Δu dqn to the output voltages u dqxpi , u dqypi , …, u dqmpi , and u dqnpi of the corresponding current-loop PI controllers respectively. The superimposed quantity is used as the input of the PWM modulation module to output a pulse drive signal to control the corresponding three-phase stator windings.

2. The control method for a permanent magnet synchronous motor back-to-back test system according to claim 1, characterized in that, The state space model of the observer is as follows: where u s , y, z1, z2 are the dq-axis voltages, dq-axis currents, observed values of the dq-axis currents, and dq-axis compensation voltages of the three-phase stator windings respectively, R0 and α0 are the virtual phase resistance of the multi-phase permanent magnet synchronous motor and the reciprocals of the dq-axis inductances respectively, and β1 and β2 are the gain coefficients of the observer.

3. The control method for a permanent magnet synchronous motor back-to-back test system according to claim 2, characterized in that, The virtual resistance term R0 of the observer is 10R s , where R s is the phase resistance of the multiphase permanent magnet synchronous motor.

4. The control method for a permanent magnet synchronous motor back-to-back test system according to claim 2, characterized in that, The gain coefficients β1 and β2 of the observer are respectively: β1 = 2ω0 + R0 where ω0 is the bandwidth of the observer.

5. The control method for a permanent magnet synchronous motor back-to-back test system according to claim 2, characterized in that, The bandwidth ω0 of the observer is ω0 = 5ω c ~10ω c , where ω c is the bandwidth of the current loop.

Images