A double-inverter temperature balance control method of an open-winding motor driving system

Abstract

The application discloses a kind of double inverter temperature balance control methods of open-winding motor drive system, first according to sensor in open-winding motor and coordinate transformation module, the three-phase voltage of motor control output is detected;The temperature difference of two parallel inverters is detected, and the sum after being given with temperature difference reference value is input to temperature controller, and the output amplitude distribution deviation value is controlled after temperature controller;Then the reference voltage amplitude of motor controller output is distributed based on the strategy of PS-SPWM, forms new output three-phase reference voltage, finally again selects triangle carrier and new three-phase reference voltage instruction to compare amplitude, generates the pulse width modulation signal required for controlling the switch tube action of inverter.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, and more specifically, relates to a dual-inverter temperature balance control method for an open-winding motor drive system. Background Technology

[0002] In recent years, researchers have proposed various novel motor drive schemes. Among them, the three-phase open-winding motor drive system with a common DC bus has attracted increasing attention because it does not require an additional DC power supply, thus reducing the system cost.

[0003] Inverters generate heat during energy conversion due to switching and conduction losses in semiconductor devices. During operation, in an open-winding motor drive system with dual inverters, inconsistencies in thermal resistance and heat dissipation environment lead to temperature differences between the two inverters. This can limit the inverter's capacity, potentially causing failure and reducing system reliability and lifespan. Therefore, implementing appropriate technical solutions to balance the temperature of dual inverters is crucial for open-winding motor drive systems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dual inverter temperature balance control method for an open-winding motor drive system. This method is used to suppress the temperature difference between the two inverters caused by environmental factors and inconsistent inverter thermal resistance, and can also suppress the zero-sequence current in the zero-sequence circuit, thereby improving the stability and lifespan of the system.

[0005] To achieve the above-mentioned objective, the present invention provides a dual-inverter temperature balance control method for an open-winding motor drive system, characterized by comprising the following steps:

[0006] (1) The position sensor obtains the rotation angle θ of the motor based on the rotation position of the open winding motor, and then the motor speed v is obtained by differentiating the rotation angle θ.

[0007] (2) The current i of the three-phase open-winding motor in the stationary coordinate system abc is detected by a current sensor. a i b and i c Then use the abc~dq0 module to process i a i b i c Perform a coordinate transformation to obtain i in the rotated coordinate system dq0. d i q and i0;

[0008] (3) Output the voltage V in the rotating coordinate system dq0 through the current controller. d V q and pulse width Δt;

[0009] (3.1) The motor speed v and the given reference speed v ref The input is sent to the speed controller, which then outputs the reference current i for the q-axis. qref Then the current i qref and q-axis current i q The summation is used as the q-axis reference input for the current controller, and the output q-axis voltage V is controlled by the current. q ;

[0010] (3.2) The reference current i given on the d-axis dref With d-axis current i d The summation is used as the d-axis reference input for the current controller, and the output d-axis voltage V is controlled by the current. d ;

[0011] (3.3) The reference current i given on the 0 axis 0ref The summation with the 0-axis current i0 is used as the 0-axis reference input of the current controller, and the required pulse width Δt is output after current control.

[0012] (4) Based on the rotation angle θ, the voltage V in the rotating coordinate system dq0 is... d V q The inverse coordinate transformation is performed using the dq~αβ module, and the target reference vector V is obtained. ref ;

[0013] (5) The temperatures of inverter 1 and inverter 2 are detected by temperature sensors, and the difference is calculated to obtain ΔT. ΔT is used as the feedback quantity of the temperature controller and the given temperature difference reference value ΔT. ref The summation is then input to the temperature controller, which controls the output amplitude distribution deviation value ΔV. When ΔV>0, it indicates that the temperature of inverter 1 is lower than that of inverter 2; when ΔV<0, it indicates that the temperature of inverter 1 is higher than that of inverter 2; when ΔV=0, it indicates that the temperature of inverter 1 is equal to that of inverter 2.

[0014] (6) Without changing the target reference vector V ref Given the amplitude, the target reference vector V for the two inverters ref The amplitude is allocated accordingly;

[0015] When ΔV = 0, V ref The amplitude is evenly distributed, that is, the reference vector V of inverter 1 and inverter 2 is... ref1 V ref2 The amplitudes are equal, but the directions are opposite;

[0016] When ΔV>0, based on ΔV=0, the reference vector V of inverter 1 is...ref1 The amplitude increases by |ΔV|, and the reference vector V of inverter 2... ref2 The amplitude decreases by |ΔV|;

[0017] When ΔV < 0, based on ΔV = 0, the reference vector V of inverter 1 is... ref1 The amplitude decreases by |ΔV|, and the reference vector V of inverter 2... ref2 The amplitude increases by |ΔV|;

[0018] (7) In V ref After the amplitude distribution is completed, the reference vectors V of the two inverters, whose amplitudes are equally distributed to the target reference vector, are respectively... ref1 V ref2 Performing an αβ~abc inverse coordinate transformation, we obtain new reference voltages for the two inverters. Let V be the reference voltage for inverter 1. a1 V b1 and V c1 The reference voltage for inverter 2 is V. a2 V b2 and V c2 ;

[0019] (8) Calculate the change in pulse width ΔD of the PWM waves of the two inverters after amplitude distribution relative to the average amplitude distribution:

[0020]

[0021] Among them, T s The pulse width period of the PWM wave;

[0022] (9) Adjust the pulse width of the PWM waves of the two inverters;

[0023] (9.1) When ΔV < 0, the pulse width of the A-phase bridge arm of the two inverters is symmetrical on both sides and increases by ΔD, while the sum of the pulse widths of the B and C phase inverters decreases by ΔD respectively.

[0024] (9.2) When ΔV>0, the pulse widths of the A-phase bridge arms of the two inverters are symmetrical on both sides and decrease by ΔD, while the sum of the pulse widths of the B and C phase inverters increases by ΔD respectively.

[0025] (9.3) When ΔV=0, the pulse widths of phases A, B, and C will not be increased or decreased.

[0026] (10) Based on the sector where the rotor position angle is located, the initial symmetrical pulse width modulation signals are phase-shifted respectively so that the first and third phases of inverter 1 and the second and third phases of inverter 2 output common mode voltages with the same amplitude, and the modulation signals PWM1, PWM2, PWM3, PWM4, PWM5 and PWM6 with target pulse width are obtained. Among them, PWM1, PWM2 and PWM3 are used to control the operation of the first and third phase switching transistors of inverter 1, and PWM4, PWM5 and PWM6 are used to control the operation of the second and third phase switching transistors of inverter 2, so as to suppress the zero-sequence current in the zero-sequence circuit and balance the temperature of the two inverters.

[0027] The objective of this invention is achieved as follows:

[0028] This invention discloses a dual-inverter temperature balance control method for an open-winding motor drive system. First, the three-phase voltage output of the motor control is detected by sensors and a coordinate transformation module in the open-winding motor. Then, the temperature difference between the two parallel inverters is detected and summed with a given temperature difference reference value before being input to the temperature controller. The temperature controller then controls the output amplitude distribution deviation value. Next, based on a PS-SPWM strategy, the amplitude of the reference voltage output by the motor controller is distributed to form a new three-phase output reference voltage. Finally, a triangular carrier wave is selected and compared with the new three-phase reference voltage command to generate the required pulse width modulation signal for controlling the switching action of the inverter transistors.

[0029] Meanwhile, the dual-inverter temperature balance control method for an open-winding motor drive system of the present invention also has the following beneficial effects:

[0030] (1) Regarding the temperature balance control of parallel inverters, this invention utilizes the fact that the conduction losses of IGBT and anti-parallel diodes differ under the same voltage drop and current. Based on this, the amplitude of the reference voltage of the dual inverters can be adjusted while ensuring that the total amplitude of the AC current remains unchanged, thereby adjusting the conduction time of IGBT and anti-parallel diodes to achieve temperature balance of the parallel dual inverters.

[0031] (2) Regarding zero-sequence current suppression, this invention performs appropriate carrier phase shifting in each sector of vector synthesis based on the PS-SPWM strategy, so that the two sets of three-phase inverters output equal sub-common-mode voltages in real time, thereby eliminating the high-frequency zero-sequence voltage input from the inverter to the three-phase open-winding AC motor, and suppressing the low-frequency zero-sequence current in the zero-sequence circuit through the 0-axis current controller. Attached Figure Description

[0032] Figure 1 This is a topology diagram of a three-phase open-winding AC motor powered by a single DC power supply.

[0033] Figure 2 This is a schematic diagram of a three-phase open-winding drive system according to the present invention;

[0034] Figure 3 This is a schematic diagram of the temperature balance control principle of a parallel inverter in a three-phase open-winding AC motor drive system according to the present invention. Detailed Implementation

[0035] The specific embodiments of the present invention will now be described with reference to the accompanying drawings to enable those skilled in the art to better understand the invention. It should be particularly noted that in the following description, detailed descriptions of known functions and designs that might obscure the main content of the invention will be omitted here.

[0036] Example

[0037] Figure 1 This is a topology diagram of a three-phase open-winding AC motor powered by a single DC power supply.

[0038] In this embodiment, as Figure 1 As shown, a three-phase open-winding AC motor drive system includes: a DC power supply 1, a DC bus capacitor 2, first and three-phase inverters 3, an open-winding motor 5, second and three-phase inverters 4, and a motor grounding terminal 6. The DC power supply 1 provides DC power to the system. The first and three-phase inverters 3 and 4 convert the DC power into three-phase AC current and input it into the motor stator windings to drive the motor. The three-phase open-winding AC motor 5 converts electrical energy into mechanical energy output. The DC bus capacitor 2 stabilizes the DC side voltage. The motor grounding terminal 6 prevents electric shock hazards to equipment lines or personnel due to leakage current caused by motor malfunctions or insulation damage. The three-phase open-winding AC motor 5 includes both induction motors and permanent magnet synchronous motors.

[0039] The following is a detailed description of the dual-inverter temperature balance control method for a three-phase open-winding motor drive system according to the present invention, which specifically includes the following steps:

[0040] S1. The position sensor obtains the rotation angle θ of the motor based on the rotation position of the open-winding motor, and then calculates the motor speed v by differentiating the rotation angle θ.

[0041] S2. Detect the three-phase open-winding motor current i in the stationary coordinate system abc using a current sensor. a i b and i c Then use the abc~dq0 module to process i a i b i c Perform a coordinate transformation to obtain i in the rotated coordinate system dq0. d iq and i0;

[0042] S3. Output the voltage V in the rotating coordinate system dq0 through the current controller. d V q and pulse width Δt;

[0043] S3.1, compare the motor speed v with the given reference speed v ref The input is sent to the speed controller, which then outputs the reference current i for the q-axis. qref Then the current i qref and q-axis current i q The summation is used as the q-axis reference input for the current controller, and the output q-axis voltage V is controlled by the current. q ;

[0044] S3.2, Set the reference current i given on the d-axis dref With d-axis current i d The summation is used as the d-axis reference input for the current controller, and the output d-axis voltage V is controlled by the current. d ;

[0045] S3.3, Set the reference current i given on the 0 axis 0ref The summation with the 0-axis current i0 is used as the 0-axis reference input of the current controller, and the required pulse width Δt is output after current control.

[0046] S4. Based on the rotation angle θ, the voltage V in the rotating coordinate system dq0 is... d V q The inverse coordinate transformation is performed using the dq~αβ module, and the target reference vector V is obtained. ref ;

[0047] S5. The temperatures of inverter 1 and inverter 2 are detected by temperature sensors, and the difference is calculated to obtain ΔT. ΔT is used as the feedback quantity of the temperature controller and the given temperature difference reference value ΔT. ref The summation is then input to the temperature controller, which controls the output amplitude distribution deviation value ΔV. When ΔV>0, it indicates that the temperature of inverter 1 is lower than that of inverter 2; when ΔV<0, it indicates that the temperature of inverter 1 is higher than that of inverter 2; when ΔV=0, it indicates that the temperature of inverter 1 is equal to that of inverter 2.

[0048] In this embodiment, the parameters of the temperature controller are determined by the conduction loss curves of the IGBTs and anti-parallel diodes inside the inverter.

[0049] S6. Without changing the target reference vector V ref Given the amplitude, the target reference vector V for the two inverters ref The amplitude is allocated accordingly;

[0050] When ΔV = 0, V ref The amplitude is evenly distributed, that is, the reference vector V of inverter 1 and inverter 2 is... ref1 V ref2 The amplitudes are equal, but the directions are opposite;

[0051] When ΔV>0, based on ΔV=0, the reference vector V of inverter 1 is... ref1 The amplitude increases by |ΔV|, and the reference vector V of inverter 2... ref2 The amplitude decreases by |ΔV|;

[0052] When ΔV < 0, based on ΔV = 0, the reference vector V of inverter 1 is... ref1 The amplitude decreases by |ΔV|, and the reference vector V of inverter 2... ref2 The amplitude increases by |ΔV|;

[0053] S7, in V ref After the amplitude distribution is completed, the reference vectors V of the two inverters, whose amplitudes are equally distributed to the target reference vector, are respectively... ref1 V ref2 Performing an αβ~abc inverse coordinate transformation, we obtain new reference voltages for the two inverters. Let V be the reference voltage for inverter 1. a1 V b1 and V c1 The reference voltage for inverter 2 is V. a2 V b2 and V c2 Based on the PS-SPWM strategy, the pulse width of one carrier cycle is calculated, and the pulse width Δt output by the 0-axis current controller is simultaneously adjusted to generate a voltage on the dual inverter side of the zero-sequence loop that cancels the zero-sequence voltage generated by the motor rotation, thereby achieving zero-sequence current suppression.

[0054] S8. Calculate the change in pulse width ΔD of the PWM waves of the two inverters after amplitude distribution relative to the average amplitude distribution:

[0055]

[0056] Among them, T s The pulse width period of the PWM wave;

[0057] S9. To ensure that there is no high-frequency zero-sequence voltage in the zero-sequence circuit, the sub-common-mode voltage U of inverter 1 needs to be... cm1 and the sub-common-mode voltage U of inverter 2 cm2 Since they are equal, the pulse width of the PWM waves of the two inverters needs to be adjusted.

[0058] S9.1 When ΔV < 0, the pulse width of the A-phase bridge arm of the two inverters is symmetrical on both sides and increases by ΔD, while the sum of the pulse widths of the B and C phase inverters decreases by ΔD respectively.

[0059] S9.2 When ΔV>0, the pulse widths of the A-phase bridge arms of the two inverters are symmetrical on both sides and decrease by ΔD, while the sum of the pulse widths of the B and C phase inverters increases by ΔD respectively.

[0060] S9.3 When ΔV=0, the pulse widths of phases A, B, and C will not be increased or decreased.

[0061] S10. Based on the sector where the rotor position angle is located, the initial symmetrical pulse width modulation signals are phase-shifted respectively to make the first and third phases of inverter 1 and the second and third phases of inverter 2 output common-mode voltages of the same amplitude, thereby obtaining the target pulse width modulation signals PWM1, PWM2, PWM3, PWM4, PWM5 and PWM6. Among them, PWM1, PWM2 and PWM3 are used to control the operation of the first and third phase switching transistors of inverter 1, and PWM4, PWM5 and PWM6 are used to control the operation of the second and third phase switching transistors of inverter 2 to suppress zero-sequence current and balance the temperature of the two inverters.

[0062] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A dual-inverter temperature balance control method for an open-winding motor drive system, characterized in that, Includes the following steps: (1) The position sensor obtains the rotation angle of the motor based on the rotation position of the open-winding motor. Then rotate the angle The motor speed is obtained by differentiation. ; (2) Detect the current of a three-phase open-winding motor in the stationary coordinate system abc using a current sensor. and Then use the abc~dq0 module to... Perform a coordinate transformation to obtain the coordinates in the rotated coordinate system dq0. and ; (3) Output the voltage in the rotating coordinate system dq0 through the current controller. and pulse width ; (3.1) Adjust the motor speed and the given reference speed The input is sent to the speed controller, which then outputs a reference current for the q-axis. Then the current and q-axis current The difference is used as the q-axis reference input for the current controller, and the q-axis voltage is output after current control. ; (3.2) The reference current given on the d-axis With d-axis current The difference is used as the d-axis reference input for the current controller, and the d-axis voltage is output after current control. ; (3.3) Set the reference current for the 0-axis. With 0-axis current The difference is used as the 0-axis reference input for the current controller, and the required pulse width is output to the 0-axis after current control. ; (4) Based on the rotation angle The voltage in the rotating coordinate system dq0 The inverse coordinate transformation is performed using the dq~αβ module, and the target reference vector Vref is obtained. (5) The temperature difference between inverter 1 and inverter 2 is obtained by detecting the temperature sensor. ,Will As feedback from the temperature controller and a given temperature difference reference value The difference is input to the temperature controller, which then outputs the amplitude distribution deviation value. ,when When >0, it indicates that the temperature of inverter 1 is lower than the temperature of inverter 2; when When <0, it indicates that the temperature of inverter 1 is higher than the temperature of inverter 2; when When =0, it means that the temperature of inverter 1 is equal to the temperature of inverter 2; (6) Allocate the magnitudes of the target reference vector Vref of the two inverters without changing the magnitude of the target reference vector Vref; when When =0, The amplitude is evenly distributed, that is, the reference vectors of inverter 1 and inverter 2 are... , The amplitudes are equal, but the directions are opposite; when When >0, Based on =0, the reference vector of inverter 1 Amplitude increase | |, the reference vector of inverter 2 Amplitude decreases | |; when When <0, Based on =0, the reference vector of inverter 1 Amplitude decreases | |, the reference vector of inverter 2 Amplitude increases | |; (7) In After the amplitude distribution is completed, the reference vectors of the two inverters are respectively evenly distributed with respect to the target reference vector amplitude. , Perform an αβ~abc inverse coordinate transformation to obtain new reference voltages for the two inverters. Let the reference voltages of inverter 1 be Va1, Vb1 and Vc1, and the reference voltages of inverter 2 be Va2, Vb2 and Vc2. (8) Calculate the change in pulse width of the PWM wave after amplitude distribution between the two inverters relative to the average amplitude distribution pulse width. : ； in, The pulse width period of the PWM wave; (9) Adjust the pulse width of the PWM waves of the two inverters; (9.1) When When this occurs, the pulse widths of the two inverter A-phase bridge arms are symmetrical on both sides and increase. The sum of the pulse widths of the two inverters in phases B and C decreases respectively. ; (9.2) When When the pulse widths of the two inverter A-phase bridge arms are symmetrical on both sides and decrease, then... The sum of the pulse widths of the two inverters in phases B and C increases respectively. ; (9.3) When When this happens, the pulse widths of phases A, B, and C will not be increased or decreased. (10) According to the sector where the rotor position angle is located, the initial symmetrical pulse width modulation signals are phase-shifted respectively so that the inverter 1 and inverter 2 output common mode voltages with the same amplitude, and the modulation signals PWM1, PWM2, PWM3, PWM4, PWM5 and PWM6 with the target pulse width are obtained. Among them, PWM1, PWM2 and PWM3 are used to control the operation of the switching transistor of inverter 1, and PWM4, PWM5 and PWM6 are used to control the operation of the switching transistor of inverter 2, so as to suppress the zero-sequence current in the zero-sequence circuit and balance the temperature of the two inverters.

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