High-pass filtering active damping control method of permanent magnet motor

Abstract

The invention discloses a high-pass filtering active damping control method of a permanent magnet motor, and belongs to the field of motor control. According to a permanent magnet motor driven by an inverter, large current harmonics are contained in a stator coil, and vibration and noise of the motor are caused. An LC filter is connected in series between an inverter and a motor, so that current harmonics can be filtered, but system resonance can be caused, current waveform deterioration is caused, even stable operation of the system is influenced, and dynamic performance is seriously reduced. According to the invention, the high-pass filter is connected in series in the capacitance current feedback loop, so that the resonance suppression effect and the dynamic performance of the motor system are improved.

Description

Technical Field

[0001] The invention relates to a high-pass filtering active damping control method for a permanent magnet motor, and belongs to the field of motor control. Background Art

[0002] Permanent magnet synchronous motors have been widely used in many fields due to their simple structure and high power density. Permanent magnet synchronous motors driven by voltage source inverters will generate large current harmonics in the stator coils, aggravating the vibration and noise of the motor. A series LC filter is usually used to filter out current harmonics. However, the introduction of LC filters will produce resonance, deteriorate the current waveform, and even affect the stable operation of the system.

[0003] Many discussions have been conducted at home and abroad on the resonance problem of LC filters. Among them, passive damping has a simple structure, is easy to implement, and has reliable performance, and has achieved many results in the control of permanent magnet synchronous motors. "Analysis and Design of Passive Damping LCL Filter for Three-Phase Converter" (see "Transactions of China Electrotechnical Society", 2017) achieved resonance suppression by connecting a resistor in series with the capacitor branch of the LCL filter, but passive damping increased additional power loss.

[0004] Some scholars have also proposed the concept of virtual resistance. In "Apassivity-based stability analysis of the active damping technique in the offshore wind farm applications" (see "IEEE Transactions on Industry Applications", 2018), the capacitor series virtual resistance is equivalent to the filter capacitor current feedback to suppress resonance. Due to the influence of inverter delay, the traditional capacitor current proportional feedback seriously affects the dynamic performance of the current loop. Summary of the invention

[0005] Aiming at the resonance suppression of a permanent magnet synchronous motor with a pre-LC filter, the present invention proposes a high-pass filter active damping control method for the permanent magnet motor.

[0006] To implement the above method, the present invention adopts Figure 1 The control system shown in the figure is implemented, which includes eight parts: an inverter, an LC filter, a permanent magnet synchronous motor PMSM, an abc-dq module for three-phase static-two-phase rotating coordinate transformation, a current controller, an active damping module, a dq-αβ module for two-phase rotating-two-phase static coordinate transformation, and a PWM module.

[0007] The system is divided into a power circuit and a control circuit. In the power circuit, the inverter outputs three-phase AC power, which is filtered by an LC filter and then fed to the permanent magnet synchronous motor PMSM. In the control circuit, the inverter's current signal i invx , LC filter capacitor current signal i cx The current signal i of the permanent magnet synchronous motor sx The coordinates are transformed by the abc-dq module, and the current signals of the d-axis and q-axis of the three are output: i invd,q 、i cd,q 、i sd,q ; The filter capacitor current signal i of the d-axis and q-axis output by the abc-dq module cd,q As the input of the active damping module, the output active damping voltage u ADd,q ; Reference current i of d-axis and q-axis d,qref The inverter side current signal i of the d-axis and q-axis output by the abc-dq module invd,q (or the motor side current signal i of the d-axis and q-axis sd,q ) is used as the difference, and the calculated result is used as the input of the current controller to output the motor reference voltage u d,qref ; The motor reference voltage u output by the current controller d,qref , the active damping voltage u output by the active damping module ADd,q The difference between the two is calculated, and the result is used as the input of the dq-αβ module, and the output is the voltage reference u of the α-axis and β-axis. α,βref ; The voltage reference u of the α-axis and β-axis output by the dq-αβ module α,βref The control PWM module outputs 6 PWMs as the input of the inverter, which are used to control the on and off of the 6 switching tubes in the inverter.

[0008] The current signal of the inverter i invx , LC filter capacitor current signal i cx , the current signal i of the permanent magnet synchronous motor sx The rotor position θ of the permanent magnet synchronous motor is given to the abc-dq module, and the d-axis and q-axis inverter side current signals i are output by calculation invd,q , d-axis and q-axis motor side current signals i sd,q , and the d-axis and q-axis filter capacitor current signals i cd,q ;

[0009] The d-axis and q-axis filter capacitor current signals i output by the abc-dq module cd,q It is given to the active damping module and the d-axis and q-axis active damping voltages u are output by calculation. ADd,q ;

[0010] The input and output relationship of the active damping module is: Where T dIs 1.5 times the system control cycle; K c is the gain of the active damping module (6); b is the inverse of the high corner frequency of the active damping module (6); s is the differential operator in the complex frequency domain;

[0011] The adjustable parameter K c and b can take the following values:

[0012]

[0013] Where: K p is the proportional coefficient of the current controller; L f , C f are the inductance and capacitance values ​​of the LC filter respectively; L s is the motor stator inductance; ω c is the desired current loop open-loop cutoff frequency;

[0014] The d-axis and q-axis reference current signals i d,qref Subtract the d-axis and q-axis inverter side current signals i output by the abc-dq module invd,q (or d-axis and q-axis motor side current signal i sd,q ), the calculation result is given to the current controller module, and after calculation, the d-axis and q-axis motor reference voltage u is output d,qref ;

[0015] The output of the current controller is the d-axis and q-axis motor reference voltage u d,qref , minus the d-axis and q-axis active damping voltages u output by the active damping module ADd,q , get the reference voltage u of the d-axis and q-axis motors after damping *d,qref ;

[0016] D-axis and Q-axis motor reference voltage u after damping *d,qref and the motor rotor position θ are given to the dq-αβ module, and after calculation, the voltage reference u of the α-axis and β-axis is output α,βref ;

[0017] The voltage reference u of the α-axis and β-axis output by the dq-αβ module α,βref It is given to the PWM module, and after calculation, 6 PWM output signals are output to control the on and off of the 6 switching tubes in the inverter.

[0018] Compared with the existing damping method, the present invention has the advantages that, unlike the existing capacitor current proportional feedback active damping method, the control method can improve the resonance suppression effect while improving the dynamic performance of the system.

[0019] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a system structure diagram of the high-pass filtering active damping control method for the permanent magnet motor described in the present invention. DETAILED DESCRIPTION

[0021] The present invention provides a high-pass filter active damping control method for a permanent magnet motor. Figure 1 This method is described in further detail.

[0022] To implement the control method, the present invention adopts Figure 1 The system shown in the figure is implemented, which includes eight parts: an inverter, an LC filter, a permanent magnet synchronous motor PMSM, an abc-dq module for three-phase static to two-phase rotating coordinate transformation, a current controller, an active damping module, a dq-αβ module for two-phase rotating to two-phase static coordinate transformation, and a PWM module.

[0023] The system is divided into a power circuit and a control circuit. In the power circuit, the inverter outputs three-phase AC power, which is filtered by an LC filter and then fed to the permanent magnet synchronous motor PMSM. In the control circuit, the inverter's current signal i invx , LC filter capacitor current signal i cx The current signal i of the permanent magnet synchronous motor sx The coordinates are transformed by the abc-dq module, and the current signals of the d-axis and q-axis of the three are output: i invd,q 、i cd,q 、i sd,q ; The filter capacitor current signal i of the d-axis and q-axis output by the abc-dq module cd,q As the input of the active damping module, the output active damping voltage u ADd,q ; Reference current i of d-axis and q-axis d,qref The inverter side current signal i of the d-axis and q-axis output by the abc-dq module invd,q (or the motor side current signal i of the d-axis and q-axis sd,q ) is used as the difference, and the calculated result is used as the input of the current controller to output the motor reference voltage u d,qref ; The motor reference voltage u output by the current controller d,qref , the active damping voltage u output by the active damping module ADd,q The difference between the two is calculated, and the result is used as the input of the dq-αβ module, and the output is the voltage reference u of the α-axis and β-axis. α,βref ; The voltage reference u of the α-axis and β-axis output by the dq-αβ module α,βref The control PWM module outputs 6 PWMs as the input of the inverter, which are used to control the on and off of the 6 switching tubes in the inverter.

[0024] The current signal of the inverter iinvx , LC filter capacitor current signal i cx , the current signal i of the permanent magnet synchronous motor sx The rotor position θ of the permanent magnet synchronous motor is given to the abc-dq module, and the d-axis and q-axis inverter side current signals i are output by calculation invd,q , d-axis and q-axis motor side current signals i sd,q , and the d-axis and q-axis filter capacitor current signals i cd,q ;

[0025] The current signal of the inverter i invx , LC filter capacitor current signal i cx , the current signal i of the permanent magnet synchronous motor sx You can also choose two of the three, and give them to the abc-dq module together with the rotor position θ of the permanent magnet synchronous motor, and calculate and output the two current signals of the corresponding d-axis and q-axis. invd,q =i sd,q +i cd,q Another current signal is calculated.

[0026] The d-axis and q-axis filter capacitor current signals i output by the abc-dq module cd,q It is given to the active damping module and the d-axis and q-axis active damping voltages u are output by calculation. ADd,q ;

[0027] The input and output relationship of the active damping module is: Where T d Is 1.5 times the system control cycle; K c is the gain of the active damping module; b is the inverse of the high corner frequency of the active damping module; s is the differential operator in the complex frequency domain;

[0028] The active damping module K c and b can take the following values:

[0029]

[0030] Where: K p is the proportional coefficient of the current controller; L f , C f are the inductance and capacitance values ​​of the LC filter respectively; L s is the motor stator inductance; ω c is the desired current loop open-loop cutoff frequency;

[0031] The d-axis and q-axis reference current signals i d,qref Subtract the d-axis and q-axis inverter side current signals i output by the abc-dq module invd,q(or d-axis and q-axis motor side current signal i sd,q ), the calculation result is given to the current controller module, and after calculation, the d-axis and q-axis motor reference voltage u is output d,qref ;

[0032] The output of the current controller is the d-axis and q-axis motor reference voltage u d,qref , minus the d-axis and q-axis active damping voltages u output by the active damping module ADd,q , get the reference voltage u of the d-axis and q-axis motors after damping *d,qref ;

[0033] D-axis and Q-axis motor reference voltage u after damping *d,qref and the motor rotor position θ are given to the dq-αβ module, and after calculation, the voltage reference u of the α-axis and β-axis is output α,βref ;

[0034] The voltage reference u of the α-axis and β-axis output by the dq-αβ module α,βref It is given to the PWM module, and after calculation, 6 PWM output signals are output to control the on and off of the 6 switching tubes in the inverter.

Claims

1. A high-pass filter active damping control method for a permanent magnet motor, characterized in that: The control system used in the method comprises: an inverter (1), an LC filter (2), a permanent magnet synchronous motor (PMSM) (3), an abc-dq module (4) for three-phase static-two-phase rotating coordinate transformation, a current controller (5), an active damping module (6), a dq-αβ module (7) for two-phase rotating-two-phase static coordinate transformation, and a PWM module (8); The current signal i of the inverter (1) invx , the capacitor current signal i of the LC filter (2) cx , the current signal i of the permanent magnet synchronous motor (3) sx The rotor position θ of the permanent magnet synchronous motor (3) is given to the abc-dq module (4), and the d-axis and q-axis inverter side current signals i are output by calculation. invd,q , d-axis and q-axis motor side current signals i sd,q , and the d-axis and q-axis filter capacitor current signals i cd,q ; The d-axis and q-axis filter capacitor current signals i output by the abc-dq module (4) cd,q It is given to the active damping module (6), and the d-axis and q-axis active damping voltages u are output by calculation ADd,q ; The d-axis and q-axis reference current signals i d,qref Subtract the d-axis and q-axis inverter side current signals i output by the abc-dq module (4) invd,q (or d-axis and q-axis motor side current signal i sd,q ), and gives the calculation result to the current controller module (5), and outputs the d-axis and q-axis motor reference voltage u after calculation d,qref ; The output of the current controller (5) is the d-axis and q-axis motor reference voltage u d,qref , minus the d-axis and q-axis active damping voltages u output by the active damping module (6) ADd,q , get the reference voltage u of the d-axis and q-axis motors after damping *d,qref ; D-axis and Q-axis motor reference voltage u after damping *d,qref and the motor rotor position θ are given to the dq-αβ module (7), and after calculation, the voltage reference u of the α-axis and β-axis is output α,βref ; The voltage reference u of the α-axis and β-axis output by the dq-αβ module (7) α,βref The PWM module (8) outputs 6 PWM output signals after calculation to control the on and off of 6 switch tubes in the inverter (1).

2. According to the high-pass filtering active damping control method for a permanent magnet motor according to claim 1, the input and output relationship of the active damping module (6) is: Where T d Is 1.5 times the system control cycle; K c is the gain of the active damping module (6); b is the inverse of the high corner frequency of the active damping module (6); s is the differential operator in the complex frequency domain; The active damping module (6) has K c and b takes the value of: in: K p is the proportional coefficient of the current controller (5); L f , C f are the inductance and capacitance values ​​of the LC filter respectively; L s is the motor stator inductance; ω c is the desired current loop open-loop cutoff frequency; ω r 2=(L f +L s ) / L f L s C f .

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