CN114629388A - LC resonance suppression method based on virtual admittance remodeling - Google Patents

Abstract

An LC resonance suppression method based on virtual admittance reshaping belongs to the technical field of motor control. The present invention aims at the problem that the LC resonance aggravates the voltage fluctuation of the busbar. It includes: filtering the bus voltage at both ends of the small-capacity film capacitor through a primary band-pass filter and a primary virtual admittance to obtain a primary damping current, thereby obtaining a primary damping power; passing the bus voltage at both ends of the small-capacity film capacitor through a secondary band-pass Filter filtering and secondary virtual admittance obtain secondary damping current, and then obtain secondary damping power; primary damping power and secondary damping power generate α-axis damping voltage and β-axis damping voltage through damping voltage generation module; The shaft voltage command and the β-axis voltage command are added to obtain the final voltage command; the final voltage command is input to the PWM inverter to obtain the actual three-phase current. The invention reshapes the impedance of the inherent harmonics near the resonance frequency based on the virtual admittance, so as to realize the LC resonance suppression.

Description

LC resonance suppression method based on virtual admittance remodeling

technical field

The invention relates to an LC resonance suppression method based on virtual admittance remodeling, and belongs to the technical field of motor control.

Background technique

In the field of permanent magnet motor drive control, system reliability, operating life and power density have gradually become the focus of attention.

Electrolytic capacitors are the core components of traditional motor drivers, which are used to stabilize the DC side bus voltage, but they have problems such as large size, short life and easy explosion risk. Compared with electrolytic capacitors, film capacitors have the advantage of long life. The electrolytic capacitor-free motor drive system using small-capacity film capacitors has long service life and high power density, and is suitable for electric transmission occasions such as fans, pumps and compressors. At present, the electrolytic capacitor-free motor drive control technology is in the initial stage of development, and still faces some technical difficulties in harmonic suppression and stable operation.

The non-electrolytic capacitor permanent magnet synchronous motor drive system is mainly composed of a diode uncontrolled rectifier bridge, a small-capacity film capacitor, a three-phase voltage inverter and a permanent magnet synchronous motor. Due to the significant reduction in the capacitance of the electrolytic capacitor-free motor drive system, LC resonance is prone to occur, and the harmonics at the natural frequency of the system will be amplified, which will aggravate the bus voltage fluctuation, reduce the power quality of the grid side, and even lead to unstable system operation. Therefore, LC resonance suppression is the basic problem for the stable operation of the electrolytic capacitor-free drive system.

SUMMARY OF THE INVENTION

Aiming at the problem that in the existing non-electrolytic capacitor permanent magnet synchronous motor drive system, the use of small-capacity film capacitors leads to LC resonance, the harmonics near the system resonance frequency are significantly amplified, and the bus voltage fluctuation is aggravated. A method for LC resonance suppression by virtual admittance remodeling.

An LC resonance suppression method based on virtual admittance reshaping of the present invention is aimed at a permanent magnet synchronous motor drive system without electrolytic capacitors including a diode rectifier bridge, a small-capacity film capacitor, a PWM inverter and a permanent magnet synchronous motor PMSM Perform LC resonance suppression; including,

After filtering the bus voltage u _dc at both ends of the small-capacity film capacitor through the primary band-pass filter to obtain the primary component of the bus voltage u _dc , the primary damping current i _{damp_1} is obtained through the primary virtual admittance _; The first-order damping power P _{damp_1} is obtained by multiplying the voltage u _dc ; the first-order virtual admittance is determined according to the first-order harmonic frequency;

After filtering the bus voltage u _dc at both ends of the small-capacity film capacitor through the secondary band-pass filter to obtain the secondary component of the bus voltage u _dc , the secondary damping current i _{damp_2} is obtained through the secondary virtual admittance; The current i _{damp_2} is multiplied by the bus voltage u _dc to obtain the secondary damping power P _{damp_2} ; the secondary virtual admittance is determined according to the frequency of the second harmonic;

The primary damping power P _{damp_1} and the secondary damping power P _{damp_2} are generated by the damping voltage generation module to generate the α-axis damping voltage u _{α_damp} and the β-axis damping voltage u _{β_damp} ; the α-axis damping voltage u _{α_damp} is combined with the α-axis voltage command u obtained in the vector control _α ^* is added to obtain the final voltage command of the α-axis, and the β-axis damping voltage u _{β_damp} is added to the β-axis voltage command u _β ^* obtained in vector control to obtain the final voltage command of the β-axis; the final voltage command of the α-axis and the final voltage of the β-axis are added The voltage command is input to the PWM inverter to obtain the actual A-phase current i _a , the actual _B -phase current ib , and the actual _C -phase current ic , thereby realizing the suppression of LC resonance.

According to the LC resonance suppression method based on virtual admittance remodeling of the present invention, the primary virtual admittance is designed as:

In the formula, Y _{d_1} is the first-order virtual admittance amplitude, θ _{d_1} is the first-order virtual admittance angle, ω _{d_1} is the first harmonic frequency, and s is the frequency domain operator.

According to the LC resonance suppression method based on virtual admittance reshaping of the present invention, the secondary virtual admittance is designed as:

In the formula, Y _{d_2} is the second virtual admittance amplitude, θ _{d_2} is the second virtual admittance angle, and ω _{d_2} is the second harmonic frequency.

According to the LC resonance suppression method based on virtual admittance reshaping of the present invention, the method for generating the α-axis damping voltage u _{α_damp} and the β-axis damping voltage u _{β_damp} by the damping voltage generating module includes:

为矢量控制中转子观测位置。where |i _s | is the stator current amplitude,

Observe the position of the rotor in vector control.

采用速度/位置观测器对α轴电压指令u_α ^*、β轴电压指令u_β ^*、实际α轴电流i_α和实际β轴电流i_β进行处理后得到。According to the LC resonance suppression method based on virtual admittance reshaping of the present invention, the rotor observes the position

The velocity/position observer is used to process the α-axis voltage command u _α ^* , the β-axis voltage command u _β ^* , the actual α-axis current i _α and the actual β-axis current i _β to obtain.

According to the LC resonance suppression method based on virtual admittance reshaping of the present invention, the actual α-axis current i _α and the actual β-axis current i _β use a Clarke transform unit to convert the actual A-phase current i _a , the actual _B -phase current ib and The actual _C -phase current ic is obtained by transforming it.

Beneficial effects of the present invention: The method of the present invention is used for suppressing the LC resonance phenomenon in the grid-side three-phase input non-electrolytic capacitor permanent magnet synchronous motor drive system due to the significant reduction in the capacitance value of the busbar. It reshapes the impedance of the inherent harmonics near the resonance frequency based on the virtual admittance, which can effectively suppress the bus voltage and grid-side current harmonics, thereby suppressing the LC resonance and significantly improving the grid-side power quality and stability. .

Description of drawings

Fig. 1 is the principle block diagram of the LC resonance suppression method based on virtual admittance reshaping according to the present invention;

2 is an experimental waveform diagram of voltage and current harmonics at the first harmonic frequency obtained when the virtual admittance is not applied in the specific embodiment;

Fig. 3 is the schematic diagram after the voltage obtained in Fig. 2 is transformed by FFT;

Fig. 4 is the schematic diagram after the electric current obtained in Fig. 2 is transformed by FFT;

5 is an experimental waveform diagram of voltage and current harmonics at the first harmonic frequency obtained when the virtual admittance set in the method of the present invention is applied in a specific embodiment; the virtual admittance value is set as |Y _{d_1} |=0.60pu and θ _{d_1} = -0.51pu;

Fig. 6 is the schematic diagram after the voltage obtained in Fig. 5 is transformed by FFT;

Fig. 7 is the schematic diagram after the electric current obtained in Fig. 5 is transformed by FFT;

8 is an experimental waveform diagram of voltage and current harmonics at the second harmonic frequency obtained when the virtual admittance is not applied in the specific embodiment;

Fig. 9 is the schematic diagram after the voltage obtained in Fig. 8 is transformed by FFT;

10 is a schematic diagram of the current obtained in FIG. 8 after FFT transformation;

11 is an experimental waveform diagram of voltage and current harmonics at the second harmonic frequency obtained when the virtual admittance set in the method of the present invention is applied in a specific embodiment; the virtual admittance value is set as |Y _{d_2} |=0.45pu and θ _{d_2} =-1.08pu;

FIG. 12 is a schematic diagram of the voltage obtained in FIG. 11 after FFT transformation;

FIG. 13 is a schematic diagram of the current obtained in FIG. 11 after FFT transformation.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

1, the present invention provides an LC resonance suppression method based on virtual admittance reshaping. The electrolytic capacitor-free permanent magnet synchronous motor drive system of the magnetic synchronous motor PMSM111 performs LC resonance suppression; including,

After filtering the bus voltage u _dc at both ends of the small capacitance film capacitor through the primary bandpass filter 206 to obtain the primary component of the bus voltage u _dc , the primary damping current i _{damp_1} is obtained through the primary virtual admittance 204 _; The first-order damping power P _{damp_1} is obtained by multiplying the bus voltage u _dc by the No. 1 multiplication unit 203; the first-order virtual admittance 204 is determined according to the first-order harmonic frequency;

After filtering the bus voltage u _dc at both ends of the small-capacity film capacitor through the secondary band-pass filter 207 to obtain the secondary component of the bus voltage u _dc , the secondary damping current i _{damp_2} is obtained through the secondary virtual admittance 205; The secondary damping current i _{damp_2} and the bus voltage u _dc are multiplied by the second multiplication unit 202 to obtain the secondary damping power P _{damp_2} ; the secondary virtual admittance 205 is determined according to the second harmonic frequency;

The primary damping power P _{damp_1} and the secondary damping power P _{damp_2} are generated by the damping voltage generation module 201 to generate the α-axis damping voltage u _{α_damp} and the β-axis damping voltage u _{β_damp} ; the α-axis damping voltage u _{α_damp} is combined with the α-axis voltage command obtained in the vector control u _α ^* is added to obtain the final voltage command of the α axis, and the β axis damping voltage u _{β_damp} is added to the β axis voltage command u _β ^* obtained in the vector control to obtain the final voltage command of the β axis; the final voltage command of the α axis and the β axis are added together. The final voltage command is input to the PWM inverter to obtain the actual A-phase current i _a , the actual _B -phase current ib , and the actual _C -phase current ic , thereby realizing the suppression of LC resonance.

The band-pass filter is designed to effectively extract the first and second harmonics. When the grid side frequency is 50Hz, the first harmonic of the bus voltage is 300Hz, and the second harmonic is 600Hz. When the switching frequency is 8kHz, the primary bandpass filter 206 is set to:

where BPF1(z) represents a first-order bandpass filter, and z is a discrete domain operator;

The secondary bandpass filter 207 is set to:

where BPF2(z) represents a secondary bandpass filter.

1, the vector control in this embodiment includes: the vector control part includes a speed regulator 101, a No. 1 subtraction unit 102, a No. 2 subtraction unit 103, a current regulator 104, two-phase rotation to two-phase static Coordinate system transformation unit 105, first addition unit 106, second addition unit 107, Clarke transformation unit 112, two-phase stationary to two-phase rotation coordinate system transformation unit 113 and velocity/position observer 114;

对实际α轴电流i_α和实际β轴电流i_β进行变换获得的实际q轴电流i_q和实际d轴电流i_d；d轴电流差Δi_d和q轴电流差Δi_q经过电流调节器104得到d轴电压指令u_d ^*和q轴电压指令u_q ^*，d轴电压指令u_d ^*和q轴电压指令u_q ^*结合速度/位置观测器114获得的转子观测位置

经过两相旋转到两相静止坐标系变换单元105得到α轴电压指令u_α ^*和β轴电压指令u_β ^*；α轴电压指令u_α ^*与α轴阻尼电压u_{α_damp}经一号加法运算单元106获得α轴最终电压指令，β轴电压指令u_β ^*与β轴阻尼电压u_{β_damp}经二号加法运算单元107获得β轴最终电压指令；α轴最终电压指令和β轴最终电压指令经过PWM逆变器108得到实际A相电流i_a、实际B相电流i_b、实际C相电流i_c，实际A相电流i_a、实际B相电流i_b、实际C相电流i_c通过Clarke变换单元112变换得到实际α轴电流i_α和实际β轴电流i_β；图1中二极管整流桥109与三相交流电网110连接，二极管整流桥109经小容值薄膜电容与PWM逆变器108连接，PWM逆变器108连接永磁同步电机PMSM111。The rotational speed command ω _e ^* obtained by the speed/position observer 114 and the actual rotational speed ω _e pass through the rotational speed regulator 101 to obtain the q-axis current command i _q ^* , the q-axis current command i _q ^* and the two-phase stationary to the two-phase rotating coordinate system The actual q-axis current i _q obtained by transforming the actual α-axis current i _α and the actual β-axis current i _β by the transforming unit 113 passes through the No. 1 subtraction unit 102 to obtain the q-axis current difference Δi _q , the _d -axis current command id ^* and the The actual d-axis current id obtained by the transformation of the two-phase stationary to two-phase rotating coordinate system transformation unit 113 passes through the second subtraction unit 103 to obtain the _d -axis current difference _Δid , and the two-phase stationary to two-phase rotating coordinate system transformation unit 113 combines the speed /The observed position of the rotor obtained by the position observer 114

The actual q-axis current i _q and the actual d-axis current id obtained by transforming the actual α-axis current i _α and the actual β-axis current i _β ; the _d -axis current difference _Δid and the q-axis current difference Δi _q pass through the current regulator 104 The d-axis voltage command u _d ^* and the q-axis voltage command u _q ^* are obtained, the d-axis voltage command _ud ^* and the q-axis voltage command u _q ^* are obtained in combination with the observed position of the rotor obtained by the speed/position observer 114

After two-phase rotation to two-phase static coordinate system transformation unit 105, the α-axis voltage command u _α ^* and the β-axis voltage command u _β ^* are obtained; the α-axis voltage command u _α ^* and the α-axis damping voltage u _{α_damp} are processed by the first addition unit 106 obtains the final α-axis voltage command, the β-axis voltage command u _β ^* and the β-axis damping voltage u _{β_damp} obtain the β-axis final voltage command through the second addition unit 107; the α-axis final voltage command and the β-axis final voltage command undergo PWM inversion. The inverter 108 obtains the actual A-phase current i _a , the actual _B -phase current ib , the actual _C -phase current ic , the actual A-phase current i _a , the actual _B -phase current ib , and the actual _C -phase current ic through the Clarke transformation unit 112 The actual α-axis current i _α and the actual β-axis current i _β are obtained by transformation; the diode rectifier bridge 109 is connected to the three-phase AC power grid 110 in FIG. The inverter 108 is connected to the permanent magnet synchronous motor PMSM111.

Further, the primary virtual admittance 204 is designed as:

In the formula, Y _{d_1} is the first-order virtual admittance amplitude, θ _{d_1} is the first-order virtual admittance angle, ω _{d_1} is the first harmonic frequency, and s is the frequency domain operator.

The secondary virtual admittance 205 is designed as:

In the formula, Y _{d_2} is the second virtual admittance amplitude, θ _{d_2} is the second virtual admittance angle, and ω _{d_2} is the second harmonic frequency.

In the process of virtual admittance design, the amplitude of virtual admittance should be reduced as much as possible, and the harmonic suppression effect should be achieved by adjusting the angle of virtual admittance. Because the excessive virtual admittance amplitude will increase the power disturbance on the machine side and reduce the control effect of the machine side torque and speed.

The traditional active damping control method can effectively increase the system damping by constructing the grid-side current or bus voltage feedback loop, and according to the power balance principle of the grid-side and the machine-side, to effectively increase the system damping, so as to achieve the purpose of resonance suppression. The characteristic of the invention is that only the first and second harmonics which are significantly amplified by the resonance frequency are processed, and the advantage is that the precise regulation of the harmonics can be realized. side power disturbance.

Still further, the method for generating the α-axis damping voltage u _{α_damp} and the β-axis damping voltage u _{β_damp} by the damping voltage generating module 201 includes:

为矢量控制中转子观测位置。where |i _s | is the stator current amplitude,

Observe the position of the rotor in vector control.

采用速度/位置观测器114对α轴电压指令u_α ^*、β轴电压指令u_β ^*、实际α轴电流i_α和实际β轴电流i_β进行处理后得到。Going a step further, the rotor observes the position

The speed/position observer 114 is used to process the α-axis voltage command u _α ^* , the β-axis voltage command u _β ^* , the actual α-axis current i _α and the actual β-axis current i _β , and obtained after processing.

The actual α-axis current i _α and the actual β-axis current i _β are obtained by transforming the actual A-phase current i _a , the actual _B -phase current ib and the actual _C -phase current ic by using the Clarke transform unit 112 .

Specific examples:

The effectiveness of the LC resonance suppression strategy proposed by the present invention is verified on the non-electrolytic capacitor permanent magnet synchronous motor drive system platform. The parameters of the experimental platform are set as: grid voltage 380V, grid frequency 50Hz (the corresponding first harmonic is 300Hz, and the second harmonic is 600Hz), the DC bus capacitor is a film capacitor, the capacitance value is 30μF, and the grid-side inductance is 2.5mH , The d-axis inductance of the motor is 7.5mH, the q-axis inductance is 17.5mH, the number of rotor pole pairs is 3, the rated speed is 1500r/min, and the stator resistance is 0.265Ω. All control algorithms in the experiment are completed in ARM STM32F103. The switching frequency and the update frequency of the current and voltage sampling values are both set to 8kHz. The experiment is expressed in per-unit form, the base voltage is 310V, the base current is 21A, the base power is 11kW, the base frequency is 314rad/s, the base angle is πrad, and the base impedance is 15Ω.

It can be seen from Figure 2 to Figure 7 that the first harmonic of the bus voltage can be reduced from 0.17p.u. to 0.11p.u. after the virtual admittance is applied.

It can be seen from Figure 8 to Figure 13 that the second harmonic of the bus voltage can be reduced from 0.05p.u. to 0.03p.u. after the virtual admittance is applied.

Therefore, it is verified that the method of the present invention effectively suppresses the harmonics of the natural frequency of the system in the process of suppressing the LC resonance of the permanent magnet synchronous motor drive system without electrolytic capacitors.

The LC resonance suppression strategy of the non-electrolytic capacitor permanent magnet synchronous motor drive system provided by the present invention has been described in detail above. In this paper, specific examples are used to illustrate the principles and implementations of the present invention. The descriptions of the above embodiments are only It is used to help understand the method of the present invention and its core idea; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific embodiments and application scope. The contents of the description should not be construed as limiting the present invention.

Claims (6)

1. An LC resonance suppression method based on virtual admittance reshaping, which is aimed at a non-electrolytic capacitor permanent magnet synchronous motor drive system including a diode rectifier bridge, a small-capacity film capacitor, a PWM inverter and a permanent magnet synchronous motor PMSM. LC resonance suppression; characterized by comprising, After filtering the bus voltage u _dc at both ends of the small-capacity film capacitor through a primary bandpass filter (206) to obtain the primary component of the bus voltage u _dc , the primary damping current i _{damp_1} is obtained through the primary virtual admittance (204); The damping current i _{damp_1} is multiplied by the bus voltage u _dc to obtain the primary damping power P _{damp_1} ; the primary virtual admittance (204) is determined according to the frequency of the primary harmonic; After filtering the bus voltage u _dc at both ends of the small-capacity film capacitor through the secondary band-pass filter (207) to obtain the secondary component of the bus voltage u _dc , the secondary damping current i is obtained through the secondary virtual admittance (205). _{damp_2} ; the secondary damping power P _{damp_2} is obtained by multiplying the secondary damping current i _{damp_2} by the bus voltage u _dc ; the secondary virtual admittance (205) is determined according to the second harmonic frequency; The primary damping power P _{damp_1} and the secondary damping power P _{damp_2} are generated by the damping voltage generation module (201) to generate the α-axis damping voltage u _{α_damp} and the β-axis damping voltage u _{β_damp} ; the α-axis damping voltage u _{α_damp} and the α-axis obtained in the vector control The voltage command u _α ^* is added to obtain the final voltage command of the α axis, and the β axis damping voltage u _{β_damp} and the β axis voltage command u _β ^* obtained in the vector control are added to obtain the final voltage command of the β axis; the final voltage command of the α axis and The final voltage command of the β-axis is input to the PWM inverter to obtain the actual A-phase current i _a , the actual _B -phase current ib , and the actual _C -phase current ic , thereby realizing the suppression of LC resonance. 2. The LC resonance suppression method based on virtual admittance reshaping according to claim 1, wherein, The primary virtual admittance (204) is designed as:

In the formula, Y _{d_1} is the first-order virtual admittance amplitude, θ _{d_1} is the first-order virtual admittance angle, ω _{d_1} is the first harmonic frequency, and s is the frequency domain operator. 3. The LC resonance suppression method based on virtual admittance remodeling according to claim 2, wherein, The secondary virtual admittance (205) is designed as:

In the formula, Y _{d_2} is the second virtual admittance amplitude, θ _{d_2} is the second virtual admittance angle, and ω _{d_2} is the second harmonic frequency. 4. The LC resonance suppression method based on virtual admittance remodeling according to claim 3, wherein, The method for generating the α-axis damping voltage u _{α_damp} and the β-axis damping voltage u _{β_damp} by the damping voltage generating module (201) includes:

where |i _s | is the stator current amplitude,

Observe the position of the rotor in vector control. 5. The LC resonance suppression method based on virtual admittance remodeling according to claim 4, wherein, Rotor observation position

The velocity/position observer ( 114 ) is used to process the α-axis voltage command u _α ^* , the β-axis voltage command u _β ^* , the actual α-axis current i _α and the actual β-axis current i _β . 6. The LC resonance suppression method based on virtual admittance reshaping according to claim 5, wherein, The actual α-axis current i _α and the actual β-axis current i _β are obtained by transforming the actual A-phase current i _a , the actual _B -phase current ib and the actual _C -phase current ic by the Clarke transform unit ( 112 ).

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