CN108988718A - Inhibit the AC machine drive system and method for zero-sequence current and common-mode voltage - Google Patents

Abstract

The invention discloses a three-phase open-winding AC motor drive system and method for suppressing zero-sequence current and common-mode voltage, wherein the motor drive system includes a DC power supply, a DC bus capacitor, a first three-phase inverter and a second three-phase inverter. phase inverter. Aiming at the zero-sequence current and common-mode voltage problems caused by the traditional open-winding motor powered by a single DC power supply, the invention also provides a zero-sequence current control and common-mode voltage suppression method. Since this method enables the AC side current output by the inverter to have a frequency multiplication effect, the AC side current can be optimized, the torque ripple of the motor can be reduced, and the common mode voltage output from the inverter to the three-phase open-winding motor can be suppressed, reducing Electromagnetic interference generated by small motor drive systems. The invention does not need to increase any hardware cost, and can improve the motor control performance.

Description

AC motor drive system and method for suppressing zero-sequence current and common-mode voltage

technical field

The invention belongs to the field of motor control, and more specifically relates to a three-phase open-winding AC motor drive system and method for suppressing zero-sequence current and common-mode voltage.

Background technique

In three-phase AC motors, the stator open winding structure has a higher DC voltage utilization rate than the star structure. Based on the above characteristics, three-phase open-winding AC motors are widely used in occasions where the back EMF of the motor is higher than the voltage of the DC power supply. Since the neutral point of the stator winding is open, there is a zero-sequence current path for the motor when powered by a single DC power supply. The general control method will generate a large zero-sequence current in the stator winding of the motor, resulting in a large rotation speed of the motor. Torque ripple, while increasing the harmonic loss of the motor drive system. Traditional zero-sequence current suppression usually adopts two methods, one method is to use two independent DC power supplies to supply power to two sets of inverters, and realize zero-sequence current suppression by blocking the zero-sequence current path; the other method is A single DC power supply combined with active control is used to suppress zero-sequence current by eliminating zero-sequence voltage. The former method increases the size and cost of the system because of the need to add an additional power supply; the latter method has more applications, but the existing active control method sacrifices the freedom of the dual-inverter topology. While suppressing the zero-sequence voltage, the motor control effect is reduced, and the common-mode voltage problem of the inverter is not considered.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a three-phase open-winding AC motor drive system and method that suppresses zero-sequence current and common-mode voltage, thereby solving the problem caused by the traditional open-winding motor being powered by a single DC power supply. Zero-sequence current and common-mode electromagnetic interference problems.

In order to achieve the above object, according to one aspect of the present invention, a three-phase open-winding AC motor zero-sequence current drive system is provided, including: a DC power supply, a DC bus capacitor and a first three-phase inverter, and the system also includes second three-phase inverter;

The first three-phase inverter includes a first bridge arm, a second bridge arm and a third bridge arm, the first bridge arm includes a first switch tube and a second switch tube, and the second bridge arm includes a first bridge arm Three switch tubes and a fourth switch tube, the third bridge arm includes a fifth switch tube and a sixth switch tube;

The second three-phase inverter includes a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm, the fourth bridge arm includes a seventh switching tube and an eighth switching tube, and the fifth bridge arm includes a first switching tube. Nine switching tubes and a tenth switching tube, the sixth bridge arm includes an eleventh switching tube and a twelfth switching tube;

The second end of the first switch tube is connected to the first end of the second switch tube, the second end of the third switch tube is connected to the first end of the fourth switch tube, and the fifth switch tube is connected to the first end of the fourth switch tube. The second end of the switch tube is connected to the first end of the sixth switch tube;

The second end of the seventh switch tube is connected to the first end of the eighth switch tube, the second end of the ninth switch tube is connected to the first end of the tenth switch tube, and the tenth switch tube is connected to the first end of the tenth switch tube. The second end of a switch tube is connected to the first end of the twelfth switch tube;

The first end of the DC bus capacitor, the first end of the first switch tube, the first end of the third switch tube, the first end of the fifth switch tube, the first end of the seventh switch tube The first terminal, the first terminal of the ninth switch tube, and the first terminal of the eleventh switch tube are all connected to the positive terminal of the DC power supply;

The second end of the DC bus capacitor, the second end of the second switching transistor, the second end of the fourth switching transistor, the second end of the sixth switching transistor, the second end of the eighth switching transistor The second terminal, the second terminal of the tenth switching tube, and the second terminal of the twelfth switching tube are all connected to the negative terminal of the DC power supply;

When working, the midpoint of the first bridge arm is connected to the first terminal of the stator winding of the three-phase open-winding AC motor, and the midpoint of the second bridge arm is connected to the stator winding of the three-phase open-winding AC motor. The second terminal is connected, the midpoint of the third bridge arm is connected to the third terminal of the stator winding of the three-phase open-winding AC motor, and the midpoint of the fourth bridge arm is connected to the three-phase open-winding AC The fourth terminal of the stator winding of the motor is connected, the midpoint of the fifth bridge arm is connected to the fifth terminal of the stator winding of the three-phase open-winding AC motor, and the midpoint of the sixth bridge arm is connected to the third terminal of the three-phase open-winding AC motor. The sixth terminal connection of the stator winding of an open-winding AC motor.

According to another aspect of the present invention, a zero-sequence current suppression method based on the above-mentioned three-phase open-winding AC motor drive system is provided, including:

Compare the d-axis current, q-axis current, and zero-axis current in the rotating coordinate system with the d-axis reference current, q-axis reference current, and zero-axis reference current to obtain the d-axis error current, q-axis error current, and zero-axis error current;

Through the d-axis error current, the q-axis error current, and the zero-axis error current, a d-axis reference voltage, a q-axis reference voltage, and a zero-axis reference voltage are obtained, and through the d-axis reference voltage, the q axis reference voltage, the zero axis reference voltage and rotor position angle to obtain a three-phase reference voltage in a stationary coordinate system;

The reference voltages of the phases of the first three-phase inverter and the reference voltages of the phases of the second three-phase inverter are obtained from the three-phase reference voltages, and the reference voltages of the phases of the first three-phase inverter are obtained by And the reference voltage of each phase of the second three-phase inverter is compared with the triangular carrier wave respectively to generate an initial symmetrical pulse width modulation signal;

According to the sector where the rotor position angle is located, phase-shift each of the initial symmetrical pulse width modulation signals, so that the output of the first three-phase inverter and the second three-phase inverter are the same The common-mode voltage with reduced amplitude can obtain the target pulse width modulation signals PWM1, PWM2, PWM3, PWM4, PWM5 and PWM6, wherein PWM1, PWM2 and PWM3 are used to control the switching tube action of the first three-phase inverter , PWM4, PWM5 and PWM6 are used to control the switching tube action of the second three-phase inverter, so as to suppress the zero-sequence current and common-mode voltage of the motor.

Preferably, the partition situation of the sector is:

Wherein, θ represents the rotor position angle.

Preferably, if the rotor position angle is in the first sector, the target pulse width modulation signal PWM1 is obtained by shifting the phase of _Ga1 by half a switching period, and the target pulse width modulation signal _PWM4 is obtained by shifting the phase of Ga2 by half a switching period, Move G _b2 to align the falling edge of G _b2 with the rising edge of PWM4 to obtain the target pulse width modulation signal PWM5, move G _c2 to align the rising edge of G _c2 with the falling edge of PWM4 to obtain the target pulse width modulation signal PWM6, and move G _b1 to make G _b1 The rising edge of PWM1 is aligned with the falling edge of PWM1 to obtain the target pulse width modulation signal PWM2, and the moving G _c1 is aligned to align the falling edge of G _c1 with the rising edge of PWM1 to obtain the target pulse width modulation signal PWM3, and the falling edge of PWM2 is automatically aligned with the falling edge of PWM6. The rising edge of PWM3 is automatically aligned with the rising edge of PWM5, wherein G _a1 , G _b1 and G _c1 are the initial pulse width modulation signals for driving the upper transistor of the first three-phase inverter, G _a2 , G _b2 and G _c2 is the initial pulse width modulation signal for driving the upper transistor of the second three-phase inverter.

Preferably, if the rotor position angle is in the second sector, shift _Gc1 by half a switching period to obtain the target pulse width modulation signal PWM3, and shift _Gc2 by half a switching period to obtain the target pulse width modulation signal PWM6, Move G _b2 to align the falling edge of G _b2 with the rising edge of PWM6 to obtain the target pulse width modulation signal PWM5, move G _a2 to align the rising edge of G _a2 with the falling edge of PWM6 to obtain the target pulse width modulation signal PWM4, and move G _b1 to make G _b1 The rising edge of G a1 is aligned with the falling edge of PWM3 to obtain the target pulse width modulation signal PWM2, and the moving G _a1 is made to align the falling edge of G _a1 with the rising edge of PWM3 to obtain the target pulse width modulation signal PWM1, and the falling edge of PWM2 is automatically aligned with the falling edge of PWM4. The rising edge of PWM1 is automatically aligned with the rising edge of PWM5, wherein G _a1 , G _b1 and G _c1 are the initial pulse width modulation signals for driving the upper transistor of the first three-phase inverter, G _a2 , G _b2 and G _c2 is the initial pulse width modulation signal for driving the upper transistor of the second three-phase inverter.

Preferably, if the rotor position angle is in the third sector, shift G _b1 by half a switching cycle to obtain the target pulse width modulation signal PWM2, and shift G _b2 by half a switching cycle to obtain the target pulse width modulation signal PWM5, Move G _c2 to align the falling edge of G _c2 with the rising edge of PWM5 to obtain the target pulse width modulation signal PWM6, move G _a2 to align the rising edge of G _a2 with the falling edge of PWM5 to obtain the target pulse width modulation signal PWM4, and move G _c1 to make G _c1 The rising edge of PWM2 is aligned with the falling edge of PWM2 to obtain the target pulse width modulation signal PWM3, and G _a1 is moved to align the falling edge of G _a1 with the rising edge of PWM2 to obtain the target pulse width modulation signal PWM1, and the falling edge of PWM3 is automatically aligned with the falling edge of PWM4. The rising edge of PWM1 is automatically aligned with the rising edge of PWM6, wherein G _a1 , G _b1 and G _c1 are initial pulse width modulation signals for driving the upper transistor of the first three-phase inverter, G _a2 , G _b2 and G _c2 is the initial pulse width modulation signal for driving the upper transistor of the second three-phase inverter.

Preferably, if the rotor position angle is in the fourth sector, the target pulse width modulation signal PWM1 is obtained by shifting the phase of _Ga1 by half a switching period, and the target pulse width modulation signal _PWM4 is obtained by shifting the phase of Ga2 by half a switching period, Move G _c2 to align the falling edge of G _c2 with the rising edge of PWM4 to obtain the target pulse width modulation signal PWM6, move G _b2 to align the rising edge of G _b2 with the falling edge of PWM4 to obtain the target pulse width modulation signal PWM5, and move G _c1 to make G _c1 The rising edge of PWM1 is aligned with the falling edge of PWM1 to obtain the target pulse width modulation signal PWM3, and G _b1 is moved to align the falling edge of G _b1 with the rising edge of PWM1 to obtain the target pulse width modulation signal PWM2, and the falling edge of PWM3 is automatically aligned with the falling edge of PWM5. The rising edge of PWM2 is automatically aligned with the rising edge of PWM6, wherein G _a1 , G _b1 and G _c1 are initial pulse width modulation signals for driving the upper transistor of the first three-phase inverter, G _a2 , G _b2 and G _c2 is the initial pulse width modulation signal for driving the upper transistor of the second three-phase inverter.

Preferably, if the rotor position angle is in the fifth sector, shift G _c1 by half a switching cycle to obtain the target pulse width modulation signal PWM3, and shift G _c2 by half a switching cycle to obtain the target pulse width modulation signal PWM6, Move G _a2 to align the falling edge of G _a2 with the rising edge of PWM6 to obtain the target pulse width modulation signal PWM4, move G _b2 to align the rising edge of G _b2 with the falling edge of PWM6 to obtain the target pulse width modulation signal PWM5, and move G _a1 to make G _a1 The rising edge of PWM3 is aligned with the falling edge of PWM3 to obtain the target pulse width modulation signal PWM1, and G _b1 is moved to align the falling edge of G _b1 with the rising edge of PWM3 to obtain the target pulse width modulation signal PWM2. The falling edge of PWM1 is automatically aligned with the falling edge of PWM5, The rising edge of PWM2 is automatically aligned with the rising edge of PWM4, wherein G _a1 , G _b1 and G _c1 are initial pulse width modulation signals for driving the upper transistor of the first three-phase inverter, G _a2 , G _b2 and G _c2 is the initial pulse width modulation signal for driving the upper transistor of the second three-phase inverter.

Preferably, if the rotor position angle is in the sixth sector, shift _Gb1 by half a switching period to obtain the target pulse width modulation signal PWM2, and shift _Gb2 by half a switching period to obtain the target pulse width modulation signal PWM5, Move G _a2 to align the falling edge of G _a2 with the rising edge of PWM5 to obtain the target pulse width modulation signal PWM4, move G _c2 to align the rising edge of G _c2 with the falling edge of PWM5 to obtain the target pulse width modulation signal PWM6, and move G _a1 to make G _a1 The rising edge of G c1 is aligned with the falling edge of PWM2 to obtain the target pulse width modulation signal PWM1, and the moving G _c1 is aligned to align the falling edge of G _c1 with the rising edge of PWM2 to obtain the target pulse width modulation signal PWM3, and the falling edge of PWM1 is automatically aligned with the falling edge of PWM6. The rising edge of PWM3 is automatically aligned with the rising edge of PWM4, G _a1 , G _b1 and G _c1 are the initial pulse width modulation signals for driving the upper tube of the first three-phase inverter, and G _a2 , G _b2 and G _c2 are the driving The initial pulse width modulation signal of the upper transistor of the second three-phase inverter.

Generally speaking, compared with the prior art, the above technical scheme conceived by the present invention is based on the traditional unipolar frequency doubling SPWM modulation method, and carries out appropriate carrier phase shifting in each sector of vector synthesis , so that the two sets of three-phase inverters output the same common-mode voltage with reduced amplitude in real time, thereby eliminating the zero-sequence voltage input from the inverter to the three-phase open-winding AC motor, realizing the suppression of zero-sequence current, and reducing the motor voltage at the same time. common-mode voltage at the terminal. The control method of the invention does not need to add hardware, has strong versatility, and can reduce the current harmonics on the AC side while suppressing zero-sequence current and common-mode voltage.

Description of drawings

1 is a topological structure diagram of a three-phase open-winding AC motor powered by a single DC power supply provided by an embodiment of the present invention;

2 is a control block diagram of a three-phase open-winding AC motor provided by an embodiment of the present invention;

Fig. 3 is a flow chart of a zero-sequence current control method for a three-phase open-winding AC motor provided by an embodiment of the present invention;

Fig. 4 is a pulse width modulation signal waveform diagram for driving two sets of three-phase inverters provided by an embodiment of the present invention;

Fig. 5 is a comparison diagram of zero-sequence current control and zero-sequence current control provided by an embodiment of the present invention;

Fig. 6 is a phase current comparison diagram between a phase current provided by an embodiment of the present invention and a general zero-sequence current active control method;

Fig. 7 is a comparison diagram of common-mode voltage of a motor provided by an embodiment of the present invention and a common-mode voltage of a general zero-sequence current active control method;

Throughout the drawings, the same reference numerals are used to designate the same elements or structures, wherein:

1-DC power supply, 2-DC bus capacitor, 3-first three-phase inverter, 4-second three-phase inverter, 5-three-phase open-winding AC motor, 6-three-phase AC motor grounding.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

The invention provides a three-phase open-winding AC motor drive system and method for suppressing zero-sequence current. control effect.

As shown in Figure 1, it is a schematic structural diagram of a three-phase open-winding AC motor zero-sequence current drive system provided by an embodiment of the present invention, including: a DC power supply 1, a DC bus capacitor 2, a first three-phase inverter 3 and a first three-phase inverter 3. Two or three phase inverter 4;

The first three-phase inverter 3 includes a first bridge arm, a second bridge arm and a third bridge arm, the first bridge arm includes a first switching tube and a second switching tube, and the second bridge arm includes a third switching tube and a third switching tube. Four switch tubes, the third bridge arm includes a fifth switch tube and a sixth switch tube;

The second three-phase inverter 4 includes a fourth bridge arm, a fifth bridge arm and a sixth bridge arm, the fourth bridge arm includes a seventh switching tube and an eighth switching tube, and the fifth bridge arm includes a ninth switching tube and a sixth switching tube. Ten switch tubes, the sixth bridge arm includes the eleventh switch tube and the twelfth switch tube;

The second end of the first switch tube is connected to the first end of the second switch tube, the second end of the third switch tube is connected to the first end of the fourth switch tube, and the second end of the fifth switch tube is connected to the sixth switch tube. the first end of the tube is connected;

The second end of the seventh switch tube is connected to the first end of the eighth switch tube, the second end of the ninth switch tube is connected to the first end of the tenth switch tube, and the second end of the eleventh switch tube is connected to the tenth switch tube. The first ends of the two switch tubes are connected;

The first end of the DC bus capacitor 2, the first end of the first switch tube, the first end of the third switch tube, the first end of the fifth switch tube, the first end of the seventh switch tube, the first end of the ninth switch tube Both the first terminal and the first terminal of the eleventh switching tube are connected to the positive terminal of the DC power supply 1;

The second end of the DC bus capacitor 2, the second end of the second switching tube, the second end of the fourth switching tube, the second end of the sixth switching tube, the second end of the eighth switching tube, the second end of the tenth switching tube Both the second end and the second end of the twelfth switching tube are connected to the negative end of the DC power supply 1;

When working, the midpoint of the first bridge arm is connected to the first terminal of the stator winding of the three-phase open-winding AC motor, and the midpoint of the second bridge arm is connected to the second terminal of the stator winding of the three-phase open-winding AC motor. The midpoint of the third bridge arm is connected to the third terminal of the stator winding of the three-phase open-winding AC motor, the midpoint of the fourth bridge arm is connected to the fourth terminal of the stator winding of the three-phase open-winding AC motor, and the fifth bridge arm The midpoint of the bridge arm is connected to the fifth terminal of the stator winding of the three-phase open-winding AC motor, and the midpoint of the sixth bridge arm is connected to the sixth terminal of the stator winding of the three-phase open-winding AC motor.

Among them, the DC power supply 1 is used to provide DC power to the system, and the first three-phase inverter 3 and the second three-phase inverter 4 are used to invert the DC power into a three-phase AC current and input it into the stator winding of the motor to drive the motor to work , the three-phase open-winding AC motor 5 is used to convert electrical energy into mechanical energy output, the DC bus capacitor 2 is used to stabilize the DC side voltage, and the motor grounding 6 is used to prevent the electric leakage of the motor due to fault or insulation damage from causing electric shock hazards to equipment lines or personal .

Wherein, the three-phase open-winding AC motor 5 may include an induction motor, a permanent magnet synchronous motor, and the like.

The embodiment of the present invention also provides a zero-sequence current and common-mode voltage suppression method based on the above-mentioned three-phase open-winding AC motor drive system. The synthesized sector performs appropriate carrier phase shift, so that the two sets of three-phase inverters output the same common-mode voltage with reduced amplitude in real time, thereby eliminating the zero-sequence voltage input from the inverter to the three-phase open-winding AC motor, Realize the suppression of zero-sequence current, and reduce the common-mode voltage at the motor terminal at the same time.

In terms of motor control, the vector control method is adopted, the basic idea is to generate the reference voltage vector in the rotating coordinate system through the d-axis, q-axis and zero-axis current controllers designed in the pulse width modulation circuit, and then calculate the static coordinates through coordinate transformation The three-phase reference voltage under the system, and then select the triangular carrier wave to compare the amplitude with the three-phase reference voltage command, and generate the required pulse width modulation signal to control the switching tube action of the inverter.

FIG. 2 is a schematic diagram of a vector control method for a three-phase AC motor provided by an embodiment of the present invention. The control system consists of an inner loop (current loop) and an outer loop (speed loop). The speed loop adjusts the difference between the reference speed and the feedback speed through the speed controller to obtain the command value i _qref of the torque current component. Similarly, the command values _idref and i _0ref of the d-axis and zero-axis current are also adjusted according to actual needs. The reference current is compared with the feedback current at the dq0 coordinate, where the feedback current at the dq0 coordinate is the measured three-phase current obtained through coordinate transformation, and finally adjusted by the d-axis, q-axis and zero-axis current controllers to generate a reference voltage V _d , V _q and V ₀ . V _d , V _q and V ₀ undergo coordinate transformation to generate three-phase reference voltages V _a , V _b and V _c in the static coordinate system, and finally V _a , V _b and V _c are input to the zero-sequence current control algorithm module to generate The PWM signals of the two sets of inverters are used to drive the corresponding switching tubes to control the current and speed of the motor. The rotor position of the motor is used for coordinate transformation, and the rotational speed of the motor is used for speed loop feedback, wherein the rotor position and rotational speed can be obtained by a position sensor. Specifically, the following steps are included:

(1) Compare the d-axis current, q-axis current, and zero-axis current in the rotating coordinate system with the d-axis reference current, q-axis reference current, and zero-axis reference current to obtain the d-axis error current, q-axis error current, and Zero axis error current;

Among them, by The _d -axis current id , q-axis current i _q and zero-axis current i ₀ in the rotating coordinate system are obtained, i _a , i _b and _ic are the three-phase currents in the stationary coordinate system, and θ is the rotor position angle.

Among them, i _a , i _b and i _c are obtained by the current sensor in the sampling feedback circuit, θ is obtained by the position sensor, the input terminal of the sampling feedback circuit is connected to the output terminal of the current sensor of the three-phase open-winding AC motor 5 and the rotor position sensor, and the output and The drive control circuit is connected to collect the stator winding current and rotor position information of the three-phase open-winding AC motor and send them to the drive control circuit. The drive control circuit generates PWM signals for controlling the first three-phase inverter 3 and the second three-phase inverter 3. Each switching tube of the phase inverter 4 operates to output a command voltage to control the current in the stator winding of the motor.

(2) Obtain d-axis reference voltage, q-axis reference voltage, and zero-axis reference voltage through the d-axis error current, q-axis error current, and zero-axis error current, and obtain the d-axis reference voltage, q-axis reference voltage, and zero-axis reference voltage The voltage and the rotor position angle are used to obtain the three-phase reference voltage in the stationary coordinate system;

Among them, by The d-axis error current i _{d_err} , the q-axis error current i _{q_err} and the zero-axis error current i _{0_err are obtained} , and _idref , i _qref and i _0ref are the reference currents of the d-axis, q-axis and zero-axis respectively.

Wherein, V _d , V _q and V ₀ are the reference voltage commands output by the d-axis, q-axis and zero-axis current controllers respectively.

Among them, by The three-phase reference voltages V _a , V _b and V _c in the static coordinate system are obtained.

(3) Obtain the reference voltages of each phase of the first three-phase inverter 3 and the reference voltages of each phase of the second three-phase inverter 4 by the three-phase reference voltage, by applying the phases of the first three-phase inverter 3 The reference voltage and the reference voltage of each phase of the second three-phase inverter 4 are respectively compared with the triangular carrier wave to generate an initial symmetrical pulse width modulation signal;

(4) According to the sector where the rotor position angle is located, phase-shift each initial symmetrical pulse width modulation signal, so that the first three-phase inverter 3 and the second three-phase inverter 4 output the same reduction amplitude Value common-mode voltage, obtain target pulse width modulation signal PWM1, PWM2, PWM3, PWM4, PWM5 and PWM6, wherein, PWM1, PWM2 and PWM3 are used for controlling the switching tube action of first three-phase inverter 3, PWM4, PWM5 And PWM6 is used to control the switching tube action of the second three-phase inverter 4 to suppress zero-sequence current and common-mode voltage.

As shown in Figure 3, the three-phase reference voltage is equally divided into two sets of three-phase inverters, and the reference voltage obtained by each phase of the two sets of inverters is: V _a1 , V _b1 and V _c1 are the three-phase reference voltages of the first three-phase inverter 3 , and V _a2 , V _b2 and V _c2 are the three-phase reference voltages of the second three-phase inverter 4 . A symmetrical initial SPWM pulse width modulation signal is generated by comparing the amplitude of the two sets of three-phase voltage commands with the triangular carrier; in addition, the rotor position angle is added to judge the sector, and the sector grouping is as follows:

Select the corresponding phase-shifting scheme in each sector according to the situation of the sector, and finally generate the target SPWM pulse width modulation signal to drive the switching tube action and reference voltage output of two sets of three-phase inverters.

As shown in Figure 4, the legend on the left is the initial symmetrical pulse width modulation signal generated by the general SPWM modulation method in sectors 1 to 6, where G _a1 , G _b1 , G _c1 , G _a2 , G _b2 and G _c2 are drive The initial pulse width modulation signal waveforms of the upper tubes of the two sets of three-phase inverters, V _cm1 and V _cm2 are the common-mode voltages output by the two sets of inverters. It can be seen that the common-mode voltage output by the two sets of inverters is different, which will generate zero-sequence current in the three-phase open-winding motor; the illustration on the right is the target PWM signal generated by the improved SPWM modulation method, by adjusting the initial pulse width Appropriate phase-shifting of the modulation signal can ensure that the common-mode voltage output by the two sets of inverters remains the same within one switching cycle, and the amplitude of the common-mode voltage generated by each set of inverters after phase-shifting is compared with that before phase-shifting. Reduction is also achieved, thereby suppressing the motor's zero-sequence current and common-mode voltage. Among them, the principle of phase shifting to achieve zero-sequence current and common-mode voltage suppression effect is as follows:

In the first sector, of the two initial PWM signals of phase A, G _a1 has the largest duty cycle of the six PWM signals, and G _a2 has the smallest duty cycle of the six PWM signals. The two initial PWM signals of Phase A are phase-shifted by half a switching cycle to obtain the target PWM signal PWM1 and the target PWM signal PWM4, and the initial PWM signals of Phase B and Phase C are also subjected to real-time phase shift control, G Move _b2 to the right so that its falling edge is aligned with the rising edge of PWM4 to obtain the target pulse width modulation signal PWM5, and G _c2 is moved to the left to align its rising edge with the falling edge of PWM4 to obtain the target pulse width modulation signal PWM6, and G _b1 is moved to the right Align its rising edge with the falling edge of PWM1 to obtain the target pulse width modulation signal PWM2, and move G _c1 to the left to align its falling edge with the rising edge of PWM1 to obtain the target pulse width modulation signal PWM3, and the falling edge of the remaining edge position PWM2 It will be automatically aligned with the falling edge of PWM6, and the rising edge of PWM3 will be automatically aligned with the rising edge of PWM5. After adopting the above phase-shifting method, it can ensure that the common-mode voltage of the two sets of inverters in this sector remains consistent, thereby eliminating the zero-sequence voltage, and at the same time reducing the amplitude of the common-mode voltage of each set of inverters and suppressing the zero-sequence current and common-mode voltage;

In the second sector, of the two initial PWM signals of phase C, G _c1 has the smallest duty cycle of the six PWM signals, and G _c2 has the largest duty cycle of the six PWM signals. The two initial PWM signals of Phase C are phase-shifted by half a switching cycle to obtain the target PWM signal PWM3 and the target PWM signal PWM6, and the initial PWM signals of Phase A and Phase B are also subjected to real-time phase-shift control, G Move _b2 to the left to align its falling edge with the rising edge of PWM6 to obtain the target pulse width modulation signal PWM5, and move G _a2 to the right to align its rising edge with the falling edge of PWM6 to obtain the target pulse width modulation signal PWM4, and G _b1 moves to the left Align its rising edge with the falling edge of PWM3 to obtain the target pulse width modulation signal PWM2, and move G _a1 to the right to align its falling edge with the rising edge of PWM3 to obtain the target pulse width modulation signal PWM1, and the falling edge of the remaining edge position PWM2 It will be automatically aligned with the falling edge of PWM4, and the rising edge of PWM1 will be automatically aligned with the rising edge of PWM5. After adopting the above phase-shifting method, it can ensure that the common-mode voltage of the two sets of inverters in this sector remains consistent, thereby eliminating the zero-sequence voltage, and at the same time reducing the amplitude of the common-mode voltage of each set of inverters and suppressing the zero-sequence current and common-mode voltage;

In the third sector, of the two initial PWM signals of phase B, G _b1 has the largest duty cycle of the six PWM signals, and G _b2 has the smallest duty cycle of the six PWM signals. The two initial PWM signals of Phase B are phase-shifted by half a switching cycle to obtain the target PWM signal PWM2 and the target PWM signal PWM5, and the initial PWM signals of Phase A and Phase C are also subjected to real-time phase shift control. Move _c2 to the right to align its falling edge with the rising edge of PWM5 to obtain the target pulse width modulation signal PWM6, and move G _a2 to the left to align its rising edge with the falling edge of PWM5 to obtain the target pulse width modulation signal PWM4, and move G _c1 to the right Align its rising edge with the falling edge of PWM2 to obtain the target pulse width modulation signal PWM3, and move G _a1 to the left so that its falling edge is aligned with the rising edge of PWM2 to obtain the target pulse width modulation signal PWM1, and the falling edge of the remaining edge position PWM3 It will be automatically aligned with the falling edge of PWM4, and the rising edge of PWM1 will be automatically aligned with the rising edge of PWM6. After adopting the above phase-shifting method, it can ensure that the common-mode voltage of the two sets of inverters in this sector remains consistent, thereby eliminating the zero-sequence voltage, and at the same time reducing the amplitude of the common-mode voltage of each set of inverters and suppressing the zero-sequence current and common-mode voltage;

In the fourth sector, of the two initial PWM signals of phase A, G _a1 has the smallest duty cycle of the six PWM signals, and G _a2 has the largest duty cycle of the six PWM signals, and at this time The two initial PWM signals of Phase A are phase-shifted by half a switching cycle to obtain the target PWM signal PWM1 and the target PWM signal PWM4, and the initial PWM signals of Phase B and Phase C are also subjected to real-time phase shift control, G _c2 is moved to the left so that its falling edge is aligned with the rising edge of PWM4 to obtain the target pulse width modulation signal PWM6, and G _{b2 is} moved to the right so that its rising edge is aligned with the falling edge of PWM4 to obtain the target pulse width modulation signal PWM5, and G _c1 is moved to the left Align its rising edge with the falling edge of PWM1 to obtain the target pulse width modulation signal PWM3, and move G _b1 to the right so that its falling edge is aligned with the rising edge of PWM1 to obtain the target pulse width modulation signal PWM2, and the remaining edge position is the falling edge of PWM3 It will be automatically aligned with the falling edge of PWM5, and the rising edge of PWM2 will be automatically aligned with the rising edge of PWM6. After adopting the above phase-shifting method, it can ensure that the common-mode voltage of the two sets of inverters in this sector remains consistent, thereby eliminating the zero-sequence voltage, and at the same time reducing the amplitude of the common-mode voltage of each set of inverters and suppressing the zero-sequence current and common-mode voltage;

In the fifth sector, for the two initial PWM signals of phase C, G _c1 has the largest duty cycle of the six PWM signals, and G _c2 has the smallest duty cycle of the six PWM signals. The two initial PWM signals of Phase C are phase-shifted by half a switching cycle to obtain the target PWM signal PWM3 and the target PWM signal PWM6, and the initial PWM signals of Phase A and Phase B are also subjected to real-time phase-shift control, G _a2 moves to the right so that its falling edge is aligned with the rising edge of PWM6 to obtain the target pulse width modulation signal PWM4, and G _b2 moves to the left so that its rising edge is aligned with the falling edge of PWM6 to obtain the target pulse width modulation signal PWM5, and G _a1 moves to the right Align its rising edge with the falling edge of PWM3 to obtain the target pulse width modulation signal PWM1, and move G _b1 to the left to align its falling edge with the rising edge of PWM3 to obtain the target pulse width modulation signal PWM2, and the falling edge of the remaining edge position PWM1 It will be automatically aligned with the falling edge of PWM5, and the rising edge of PWM2 will be automatically aligned with the rising edge of PWM4. After adopting the above phase-shifting method, it can ensure that the common-mode voltage of the two sets of inverters in this sector remains consistent, thereby eliminating the zero-sequence voltage, and at the same time reducing the amplitude of the common-mode voltage of each set of inverters and suppressing the zero-sequence current and common-mode voltage;

In the sixth sector, of the two initial PWM signals of phase B, G _b1 has the smallest duty cycle of the six PWM signals, and G _b2 has the largest duty cycle of the six PWM signals. The two initial PWM signals of Phase B are phase-shifted by half a switching cycle to obtain the target PWM signal PWM2 and the target PWM signal PWM5, and the initial PWM signals of Phase A and Phase C are also subjected to real-time phase shift control. Move _a2 to the left to align its falling edge with the rising edge of PWM5 to obtain the target pulse width modulation signal PWM4, and move G _c2 to the right to align its rising edge with the falling edge of PWM5 to obtain the target pulse width modulation signal PWM6, and G _a1 moves to the left Align its rising edge with the falling edge of PWM2 to obtain the target pulse width modulation signal PWM1, and move G _c1 to the right to align its falling edge with the rising edge of PWM2 to obtain the target pulse width modulation signal PWM3, and the falling edge of the remaining edge position PWM1 It will be automatically aligned with the falling edge of PWM6, and the rising edge of PWM3 will be automatically aligned with the rising edge of PWM4. After adopting the above phase-shifting method, it can ensure that the common-mode voltage of the two sets of inverters in this sector remains consistent, thereby eliminating the zero-sequence voltage, and at the same time reducing the amplitude of the common-mode voltage of each set of inverters and suppressing the zero-sequence current and common-mode voltage.

As shown in FIG. 5 , the zero-sequence current comparison between the general modulation algorithm and the zero-sequence current and common-mode voltage suppression algorithm proposed by the present invention is carried out under the same working conditions. It can be seen that compared with the general modulation algorithm, the zero-sequence current and common-mode voltage suppression algorithm proposed by the present invention can greatly reduce the zero-sequence current and improve the motor control effect.

As shown in FIG. 6 , the phase current comparison between the existing zero-sequence current suppression algorithm and the zero-sequence current and common-mode voltage suppression algorithm proposed by the present invention is carried out under the same working conditions. It can be seen that compared with the existing zero-sequence current suppression algorithm, the zero-sequence current and common-mode voltage suppression algorithm proposed by the present invention has a frequency doubling effect on the phase current, and the high-frequency harmonic content is smaller, and better motor control can be obtained Effect.

As shown in FIG. 7 , the common-mode voltage comparison between the existing zero-sequence current suppression algorithm and the zero-sequence current and common-mode voltage suppression algorithm proposed by the present invention is carried out under the same working conditions. It can be seen that the zero-sequence current and common-mode voltage suppression algorithm proposed by the present invention has a smaller peak value of the common-mode voltage than the existing zero-sequence current suppression algorithm, which can reduce the common-mode electromagnetic interference of the system.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (9)

1. A three-phase open-winding AC motor drive system that suppresses zero-sequence current and common-mode voltage, comprising: a DC power supply (1), a DC bus capacitor (2) and a first three-phase inverter (3), its characteristics In that, the system further includes a second three-phase inverter (4); The first three-phase inverter (3) includes a first bridge arm, a second bridge arm and a third bridge arm, the first bridge arm includes a first switch tube and a second switch tube, and the second bridge arm The arm includes a third switch tube and a fourth switch tube, and the third bridge arm includes a fifth switch tube and a sixth switch tube; The second three-phase inverter (4) includes a fourth bridge arm, a fifth bridge arm, and a sixth bridge arm, the fourth bridge arm includes a seventh switching tube and an eighth switching tube, and the fifth bridge arm The arm includes a ninth switch tube and a tenth switch tube, and the sixth bridge arm includes an eleventh switch tube and a twelfth switch tube; The second end of the first switch tube is connected to the first end of the second switch tube, the second end of the third switch tube is connected to the first end of the fourth switch tube, and the fifth switch tube is connected to the first end of the fourth switch tube. The second end of the switch tube is connected to the first end of the sixth switch tube; The second end of the seventh switch tube is connected to the first end of the eighth switch tube, the second end of the ninth switch tube is connected to the first end of the tenth switch tube, and the tenth switch tube is connected to the first end of the tenth switch tube. The second end of a switch tube is connected to the first end of the twelfth switch tube; The first end of the DC bus capacitor (2), the first end of the first switch tube, the first end of the third switch tube, the first end of the fifth switch tube, the seventh switch tube The first end of the switch tube, the first end of the ninth switch tube, and the first end of the eleventh switch tube are all connected to the positive terminal of the DC power supply (1); The second end of the DC bus capacitor (2), the second end of the second switch tube, the second end of the fourth switch tube, the second end of the sixth switch tube, the eighth switch tube The second end of the switch tube, the second end of the tenth switch tube, and the second end of the twelfth switch tube are all connected to the negative terminal of the DC power supply (1); When working, the midpoint of the first bridge arm is connected to the first terminal of the stator winding of the three-phase open-winding AC motor, and the midpoint of the second bridge arm is connected to the stator winding of the three-phase open-winding AC motor. The second terminal is connected, the midpoint of the third bridge arm is connected to the third terminal of the stator winding of the three-phase open-winding AC motor, and the midpoint of the fourth bridge arm is connected to the three-phase open-winding AC The fourth terminal of the stator winding of the motor is connected, the midpoint of the fifth bridge arm is connected to the fifth terminal of the stator winding of the three-phase open-winding AC motor, and the midpoint of the sixth bridge arm is connected to the third terminal of the three-phase open-winding AC motor. The sixth terminal connection of the stator winding of an open-winding AC motor. 2. A zero-sequence current and common-mode voltage suppression method based on the three-phase open-winding AC motor drive system claimed in claim 1, characterized in that, comprising: Compare the d-axis current, q-axis current, and zero-axis current in the rotating coordinate system with the d-axis reference current, q-axis reference current, and zero-axis reference current to obtain the d-axis error current, q-axis error current, and zero-axis error current; Through the d-axis error current, the q-axis error current, and the zero-axis error current, a d-axis reference voltage, a q-axis reference voltage, and a zero-axis reference voltage are obtained, and through the d-axis reference voltage, the q axis reference voltage, the zero axis reference voltage and rotor position angle to obtain a three-phase reference voltage in a stationary coordinate system; Obtain the reference voltage of each phase of the first three-phase inverter (3) and the reference voltage of each phase of the second three-phase inverter (4) from the three-phase reference voltage, by inverting the first three-phase The reference voltage of each phase of the inverter (3) and the reference voltage of each phase of the second three-phase inverter (4) are respectively compared with the triangular carrier wave to generate an initial symmetrical pulse width modulation signal; According to the sector where the rotor position angle is located, phase-shift each of the initial symmetrical pulse width modulation signals, so that the first three-phase inverter (3) and the second three-phase inverter The device (4) outputs the same common-mode voltage with reduced amplitude to obtain target pulse width modulation signals PWM1, PWM2, PWM3, PWM4, PWM5 and PWM6, wherein PWM1, PWM2 and PWM3 are used to control the first three-phase inverter The switching tube action of the inverter (3), PWM4, PWM5 and PWM6 are used to control the switching tube action of the second three-phase inverter (4), so as to suppress the zero-sequence current and common-mode voltage of the motor. 3. The method according to claim 2, wherein the partition conditions of the sectors are: Wherein, θ represents the rotor position angle. 4. The method according to claim 3, wherein if the rotor position angle is in the first sector, shifting the phase of _Ga1 for half a switching period to obtain the target pulse width modulation signal PWM1, and shifting the phase of _Ga2 The target pulse width modulation signal PWM4 is obtained by half a switching cycle, and the target pulse width modulation signal PWM5 is obtained by moving G _b2 so that the falling edge of G _b2 is aligned with the rising edge of PWM4, and the target pulse width modulation signal PWM5 is obtained by moving G _c2 so that the rising edge of G _c2 is aligned with the falling edge of PWM4 to obtain the target Pulse width modulation signal PWM6, move G _b1 to align the rising edge of G _b1 with the falling edge of PWM1 to obtain the target pulse width modulation signal PWM2, move G _c1 to align the falling edge of G _c1 with the rising edge of PWM1 to obtain the target pulse width modulation signal PWM3, The falling edge of PWM2 is automatically aligned with the falling edge of PWM6, and the rising edge of PWM3 is automatically aligned with the rising edge of PWM5, wherein G _a1 , G _b1 and G _c1 are used to drive the upper transistor of the first three-phase inverter (3). G _a2 , G _b2 and G _c2 are the initial pulse width modulation signals for driving the upper transistor of the second three-phase inverter (4). 5. The method according to claim 3, wherein if the rotor position angle is in the second sector, shifting the phase of G _c1 for half a switching period to obtain the target pulse width modulation signal PWM3, and shifting the phase of G _c2 The target pulse width modulation signal PWM6 is obtained by half a switching cycle, and the target pulse width modulation signal PWM5 is obtained by moving G _b2 so that the falling edge of G _b2 is aligned with the rising edge of PWM6, and the target pulse width modulation signal PWM5 is obtained by moving G _a2 so that the rising edge of G _a2 is aligned with the falling edge of PWM6 to obtain the target Pulse width modulation signal PWM4, move G _b1 to align the rising edge of G _b1 with the falling edge of PWM3 to obtain the target pulse width modulation signal PWM2, move G _a1 to align the falling edge of G _a1 with the rising edge of PWM3 to obtain the target pulse width modulation signal PWM1, The falling edge of PWM2 is automatically aligned with the falling edge of PWM4, and the rising edge of PWM1 is automatically aligned with the rising edge of PWM5, wherein G _a1 , G _b1 and G _c1 are used to drive the upper transistor of the first three-phase inverter (3). G _a2 , G _b2 and G _c2 are the initial pulse width modulation signals for driving the upper transistor of the second three-phase inverter (4). 6. The method according to claim 3, wherein if the rotor position angle is in the third sector, shifting the phase of G _b1 for half a switching period to obtain the target pulse width modulation signal PWM2, and shifting the phase of G _b2 The target pulse width modulation signal PWM5 is obtained by half a switching cycle, and the target pulse width modulation signal PWM6 is obtained by moving G _c2 so that the falling edge of G _c2 is aligned with the rising edge of PWM5, and the target pulse width modulation signal PWM6 is obtained by moving G _a2 so that the rising edge of G _a2 is aligned with the falling edge of PWM5 to obtain the target Pulse width modulation signal PWM4, move G _c1 to align the rising edge of G _c1 with the falling edge of PWM2 to obtain the target pulse width modulation signal PWM3, move G _a1 to align the falling edge of G _a1 with the rising edge of PWM2 to obtain the target pulse width modulation signal PWM1, The falling edge of PWM3 is automatically aligned with the falling edge of PWM4, and the rising edge of PWM1 is automatically aligned with the rising edge of PWM6, wherein G _a1 , G _b1 and G _c1 are used to drive the upper transistor of the first three-phase inverter (3). G _a2 , G _b2 and G _c2 are the initial pulse width modulation signals for driving the upper transistor of the second three-phase inverter (4). 7. The method according to claim 3, wherein if the rotor position angle is in the fourth sector, shifting the phase of _Ga1 for half a switching period to obtain the target pulse width modulation signal PWM1, and shifting the phase of _Ga2 The target pulse width modulation signal PWM4 is obtained by half a switching cycle, and the target pulse width modulation signal PWM6 is obtained by moving G _c2 so that the falling edge of G _c2 is aligned with the rising edge of PWM4, and the target pulse width modulation signal PWM6 is obtained by moving G _b2 so that the rising edge of G _b2 is aligned with the falling edge of PWM4 to obtain the target Pulse width modulation signal PWM5, move G _c1 to align the rising edge of G _c1 with the falling edge of PWM1 to obtain the target pulse width modulation signal PWM3, move G _b1 to align the falling edge of G _b1 with the rising edge of PWM1 to obtain the target pulse width modulation signal PWM2, The falling edge of PWM3 is automatically aligned with the falling edge of PWM5, and the rising edge of PWM2 is automatically aligned with the rising edge of PWM6, wherein G _a1 , G _b1 and G _c1 are used to drive the upper transistor of the first three-phase inverter (3). G _a2 , G _b2 and G _c2 are the initial pulse width modulation signals for driving the upper transistor of the second three-phase inverter (4). 8. The method according to claim 3, wherein if the rotor position angle is in the fifth sector, shifting the phase of G _c1 for half a switching period to obtain the target pulse width modulation signal PWM3, and shifting the phase of G _c2 The target pulse width modulation signal PWM6 is obtained by half a switching cycle, the target pulse width modulation signal PWM4 is obtained by moving G _a2 so that the falling edge of G _a2 is aligned with the rising edge of PWM6, and the target pulse width modulation signal PWM4 is obtained by moving G _b2 so that the rising edge of G _b2 is aligned with the falling edge of PWM6 to obtain the target Pulse width modulation signal PWM5, move G _a1 to align the rising edge of G _a1 with the falling edge of PWM3 to obtain the target pulse width modulation signal PWM1, move G _b1 to align the falling edge of G _b1 with the rising edge of PWM3 to obtain the target pulse width modulation signal PWM2, The falling edge of PWM1 is automatically aligned with the falling edge of PWM5, and the rising edge of PWM2 is automatically aligned with the rising edge of PWM4, wherein G _a1 , G _b1 and G _c1 are used to drive the upper transistor of the first three-phase inverter (3). G _a2 , G _b2 and G _c2 are the initial pulse width modulation signals for driving the upper transistor of the second three-phase inverter (4). 9. The method according to claim 3, wherein, if the rotor position angle is in the sixth sector, shifting the phase of G _b1 for half a switching period to obtain the target pulse width modulation signal PWM2, and shifting the phase of G _b2 The target pulse width modulation signal PWM5 is obtained by half a switching cycle, and the target pulse width modulation signal PWM4 is obtained by moving G _a2 so that the falling edge of G _a2 is aligned with the rising edge of PWM5, and the target pulse width modulation signal PWM4 is obtained by moving G _c2 so that the rising edge of G _c2 is aligned with the falling edge of PWM5 to obtain the target Pulse width modulation signal PWM6, move G _a1 to align the rising edge of G _a1 with the falling edge of PWM2 to obtain the target pulse width modulation signal PWM1, move G _c1 to align the falling edge of G _c1 with the rising edge of PWM2 to obtain the target pulse width modulation signal PWM3, The falling edge of PWM1 is automatically aligned with the falling edge of PWM6, the rising edge of PWM3 is automatically aligned with the rising edge of PWM4, G _a1 , G _b1 and G _c1 are the initial stages for driving the upper tube of the first three-phase inverter (3) The pulse width modulation signals, G _a2 , G _b2 and G _c2 are initial pulse width modulation signals for driving the upper transistor of the second three-phase inverter (4).