Shaft current corrosion inhibition method, device, equipment, storage medium and program product

Abstract

The invention relates to a shaft current corrosion inhibition method and device, equipment, a storage medium and a program product, and relates to the technical field of motors, and the method comprises the steps: determining the three-phase duty ratio of a three-phase reference voltage vector of a three-phase AC motor in different sectors; modulating and optimizing the initial control signal of the three-phase inverter system according to the three-phase duty ratios of the different sectors to obtain a modulated and optimized control signal; controlling a switch in the three-phase inverter system based on the modulated and optimized control signal to obtain a first axis current; the first axis current is smaller than the second axis current; the first shaft current is a shaft current generated by a three-phase alternating current motor based on the modulated and optimized control signal; the second shaft current is the shaft current generated by the three-phase alternating current motor based on the initial control signal. Therefore, the shaft current corrosion can be effectively inhibited.

Description

Technical Field

[0001] The present application relates to the field of motor technology, in particular to the field of permanent magnet motor control, and specifically to a shaft current corrosion inhibition method, device, equipment, storage medium and program product. Background Art

[0002] The parasitic capacitance between the motor stator, rotor, bearing and motor ground due to the electrostatic coupling effect constitutes the conduction path of common-mode electromagnetic interference (EMI). This path induces shaft voltage at both ends of the bearing. When the shaft voltage exceeds the threshold that the insulating oil film can withstand, it will induce a high current density shaft current. The shaft current is discharged instantaneously in the form of electric sparks, which not only causes electrochemical corrosion, but also causes the metal at the contact point to melt, causing continuous damage to the bearing components. If there is a lack of effective suppression measures, long-term operation will cause insulation breakdown, seriously shortening the service life of the motor.

[0003] Therefore, the shaft current corrosion problem has become one of the key challenges that cannot be ignored in permanent magnet synchronous motor drive systems, and is of vital importance to ensure the stability of motor drive system performance and the safety of operation. It is urgent to develop and implement effective shaft current corrosion suppression strategies to cope with this increasingly severe technical problem.

[0004] Related technology CN112926225A models the common-mode circuit of the three-phase electric drive system as an RLC series structure. The model contains both the differential-mode impedance parameters of the power main circuit and the parasitic spurious parameters of the common-mode circuit, which is not conducive to the calculation of the parasitic impedance causing the shaft current. In addition, the passive suppression strategy of adding magnetic rings and common-mode filters will increase the hardware cost and volume weight.

[0005] Related technology CN116094381A proposes a dynamic zero vector modulation strategy, which uses two effective vectors with opposite directions and adjacent to the action sector with the same action time to replace the effect of the zero vector, thereby achieving common mode suppression. However, the algorithm is complex and will reduce the quality of current output.

[0006] However, it is difficult to effectively suppress the shaft current corrosion generated by the three-phase AC motor with the related technology. Summary of the invention

[0007] The present application provides a shaft current corrosion suppression method, device, equipment, storage medium and program product to at least solve the technical problem in the related art that it is difficult to effectively suppress the shaft current corrosion generated by the three-phase AC motor. The technical solution of the present application is as follows:

[0008] According to the first aspect provided by the present application, a shaft current corrosion suppression method provides a shaft current corrosion suppression method, the method comprising: determining the three-phase duty ratio of the three-phase reference voltage vector of the three-phase AC motor in different sectors; according to the three-phase duty ratio of different sectors, modulating and optimizing the initial control signal of the three-phase inverter system to obtain a modulation-optimized control signal; based on the modulation-optimized control signal, controlling the switch in the three-phase inverter system to obtain a first shaft current; the first shaft current is less than the second shaft current; the first shaft current is the shaft current generated by the three-phase AC motor based on the modulation-optimized control signal; the second shaft current is the shaft current generated by the three-phase AC motor based on the initial control signal.

[0009] According to the above technical means, the present application can optimize the modulation of the initial control signal, reduce the proportion of the control signal zero vector, and reduce the peak value of the common mode voltage according to the common mode voltage generation mechanism of the three-phase AC motor system, thereby suppressing the shaft current corrosion caused by the common mode voltage from the perspective of suppressing the noise source. In addition, the present application is simple and flexible, and can reduce the high dv / dt problem of the common mode voltage caused by the inverter dead zone. Therefore, the present application can effectively suppress shaft current corrosion.

[0010] In one possible approach, the three-phase current generated by the three-phase AC motor during operation is subjected to Park transformation and Clark transformation to obtain the dq-axis feedback current corresponding to the three-phase current; the dq-axis feedback current is subjected to current loop and speed loop control, and the dq-axis voltage in the rotating coordinate system is obtained through a PI controller; the dq-axis voltage is subjected to an inverse Park transformation to obtain the voltage vector of the three-phase AC motor in the three-phase stationary coordinate system; the voltage vector in the three-phase stationary coordinate system is subjected to an inverse Clark transformation to obtain the three-phase reference voltage vector of the three-phase AC motor.

[0011] According to the above technical means, the present application can accurately obtain the three-phase reference voltage vector of the three-phase AC motor through coordinate transformation to support the subsequent suppression of the common mode voltage amplitude causing shaft current corrosion. Therefore, the present application can effectively suppress shaft current corrosion.

[0012] In one possible manner, determining the three-phase duty ratio of the three-phase reference voltage vector of the three-phase AC motor in different sectors includes: normalizing the three-phase reference voltage vector and performing carrier comparison to obtain the three-phase duty ratio of the three-phase reference voltage vector in different sectors.

[0013] According to the above technical means, the present application can accurately obtain the three-phase duty ratio of the three-phase reference voltage vector in different sectors by comparing the carrier of the three-phase reference voltage vector, so as to support the subsequent modulation optimization of the control signal of the inverter system, so as to further support the control of the inverter system switch tube action based on the control signal of the inverter system, and reduce the common mode voltage amplitude causing shaft current corrosion. Therefore, the present application can effectively suppress shaft current corrosion.

[0014] In one possible manner, the control signal after modulation optimization includes a first control signal and a second control signal; according to the three-phase duty cycle of different sectors, the initial control signal of the inverter system of the three-phase AC motor is modulated and optimized to obtain the control signal after modulation optimization, including: for each sector, the initial control signal corresponding to the center of the three-phase duty cycle of the sector is flipped to obtain the first control signal; the first control signal is used as the control signal for driving the upper bridge arm of the three-phase inverter, and the second control signal is used as the control signal for driving the lower bridge arm of the three-phase inverter; the second control signal is the control signal after the first control signal is inverted.

[0015] According to the above technical means, the present application can optimize the modulation of the control signal of the inverter system based on the three-phase duty ratio of different sectors, so as to further control the on and off of the switch tube of the three-phase inverter system based on the control signal of the three-phase inverter system, and reduce the common mode voltage amplitude causing shaft current corrosion. Therefore, the present application can effectively suppress shaft current corrosion.

[0016] In one possible approach, a common-mode loop of a three-phase AC motor is modeled to obtain a common-mode loop model, and a target filter is determined based on the common-mode loop model; the first axis current is filtered based on the target filter; and the filtered first axis current is less than the first axis current.

[0017] According to the above technical means, the present application can accurately select parameters for the target filter to filter the first axis current, and cooperate with the above-mentioned axis current corrosion suppression method based on software control optimization to reduce the axis current in the common mode loop. Therefore, the present application can effectively suppress axis current corrosion.

[0018] In one possible manner, a target filter is determined based on a common mode loop model, including: determining a shaft current corresponding to the common mode loop model; and selecting parameters for multiple filters based on the shaft current to obtain a target filter.

[0019] According to the above technical means, the present application can accurately select the optimal filter to support the subsequent blocking of the shaft current conduction loop. Therefore, the present application can effectively suppress shaft current corrosion.

[0020] In one possible method, determining the shaft current corresponding to the common-mode loop model includes: determining the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor based on the common-mode loop model; determining the shaft current corresponding to the filter based on the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor.

[0021] According to the above-mentioned technical means, the present application can accurately calculate the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings and the shaft voltage of the three-phase AC motor, avoiding the problem that the shaft voltage of the three-phase AC motor cannot be calculated in the related technology, thereby supporting the subsequent effective suppression of shaft current corrosion.

[0022] In one possible method, stray parameters corresponding to a common-mode loop of a three-phase AC motor, stray parameters corresponding to a motor bearing, and a shaft voltage of the three-phase AC motor are determined, including: performing common-mode loop modeling on the three-phase AC motor to obtain stray parameters corresponding to the three-phase AC motor; the stray parameters corresponding to the three-phase AC motor include stray parameters between a stator core and a stator winding, stray parameters between a stator core and a rotor core, and stray parameters between a stator winding and a stator core; performing common-mode loop modeling on the motor bearing to obtain stray parameters corresponding to the motor bearing; performing common-mode loop modeling on the three-phase AC motor system to obtain the shaft voltage of the three-phase AC motor.

[0023] According to the above technical means, the present application can accurately calculate the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings and the shaft voltage of the three-phase AC motor by modeling the common mode loop, thereby supporting the subsequent effective suppression of shaft current corrosion.

[0024] According to the second aspect provided by the present application, a circuit control device is provided, including: a determination unit, an adjustment unit and a control unit; the determination unit is used to determine the three-phase duty cycle of the three-phase reference voltage vector of the three-phase AC motor in different sectors; the adjustment unit is used to modulate and optimize the initial control signal of the three-phase inverter system according to the three-phase duty cycle of different sectors to obtain the modulated optimized control signal; the modulated optimized control signal is used to control the conduction and shutdown of the switch tube in the three-phase inverter system; the control unit is used to control the switch in the three-phase inverter system based on the modulated optimized control signal to obtain a first axis current; the first axis current is less than the second axis current; the first axis current is the axis current generated by the three-phase AC motor based on the modulated optimized control signal; the second axis current is the axis current generated by the three-phase AC motor based on the initial control signal.

[0025] In one possible manner, the device also includes: a processing unit; the processing unit is specifically used to: perform Park transform and Clark transform on the three-phase current generated when the three-phase AC motor is running, to obtain the dq-axis feedback current corresponding to the three-phase current; perform current loop and speed loop control on the dq-axis feedback current, and obtain the dq-axis voltage in the rotating coordinate system through a PI controller; perform inverse Park transform on the dq-axis voltage to obtain the voltage vector of the three-phase AC motor in the three-phase stationary coordinate system; perform inverse Clark transform on the voltage vector in the three-phase stationary coordinate system to obtain the three-phase reference voltage vector of the three-phase AC motor.

[0026] In one possible manner, the determination unit is used to normalize the three-phase reference voltage vector and perform carrier comparison to obtain the three-phase duty ratios of the three-phase reference voltage vector in different sectors.

[0027] In one possible manner, the adjustment unit is specifically used to: for each sector, flip the initial control signal corresponding to the center of the three-phase duty cycle of the sector to obtain a first control signal; use the first control signal as a control signal for driving the upper bridge arm of the three-phase inverter, and use the second control signal as a control signal for driving the lower bridge arm of the three-phase inverter; the second control signal is a control signal after the first control signal is inverted.

[0028] In one possible manner, the determination unit is also used to model the common-mode loop of the three-phase AC motor to obtain a common-mode loop model, and determine a target filter based on the common-mode loop model; the processing unit is also used to filter the first axis current based on the target filter; the filtered first axis current is less than the first axis current.

[0029] In one possible manner, the determination unit is specifically used to: determine the shaft current corresponding to the common mode loop model; and select parameters for multiple filters based on the shaft current to obtain a target filter.

[0030] In one possible manner, the determination unit is specifically used to: determine the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor based on the common mode loop model; determine the shaft current corresponding to the filter based on the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor.

[0031] In one possible manner, a determination unit is specifically used to: perform common-mode loop modeling on a three-phase AC motor to obtain stray parameters corresponding to the three-phase AC motor; the stray parameters corresponding to the three-phase AC motor include stray parameters between a stator core and a stator winding, stray parameters between a stator core and a rotor core, and stray parameters between a stator winding and a stator core; perform common-mode loop modeling on a motor bearing to obtain stray parameters corresponding to the motor bearing; perform common-mode loop modeling on a three-phase AC motor system to obtain a shaft voltage of the three-phase AC motor.

[0032] According to the third aspect provided by the present application, a circuit is provided, including: a three-phase inverter system and a target filter; the output end of the three-phase inverter system is connected to the input end of the target filter; the three-phase inverter system is used to generate a first axis current based on a control signal after modulation optimization; the target filter is used to filter the first axis current.

[0033] According to the fourth aspect provided by the present application, an electronic device is provided, comprising: a processor; a memory for storing processor executable instructions; wherein the processor is configured to execute instructions to implement the method of the above-mentioned first aspect and any possible implementation manner thereof.

[0034] According to the fifth aspect provided by the present application, a computer-readable storage medium is provided. When the instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute the method in the above-mentioned first aspect and any possible implementation method thereof.

[0035] According to the sixth aspect provided by the present application, a computer program product is provided, the computer program product comprising computer instructions, and when the computer instructions are executed on an electronic device, the electronic device executes the method of the above-mentioned first aspect and any possible implementation manner thereof.

[0036] Therefore, the above technical features of the present application have the following beneficial effects:

[0037] (1) Based on the modulation optimization of the initial control signal, the proportion of the control signal zero vector can be reduced. According to the common-mode voltage generation mechanism of the three-phase AC motor system, the peak value of the common-mode voltage can be reduced, and the shaft current corrosion caused by the common-mode voltage can be suppressed from the perspective of suppressing the noise source. In addition, the present application is simple and flexible, and can reduce the high dv / dt problem of the common-mode voltage caused by the inverter dead zone. Therefore, the present application can effectively suppress the shaft current corrosion.

[0038] (2) The three-phase reference voltage vector of the three-phase AC motor can be accurately obtained through coordinate transformation to support the subsequent suppression of the common mode voltage amplitude causing shaft current corrosion. Therefore, the present application can effectively suppress shaft current corrosion.

[0039] (3) By comparing the three-phase reference voltage vector with a carrier, the three-phase duty ratio of the three-phase reference voltage vector in different sectors can be accurately obtained to support the subsequent modulation optimization of the control signal of the inverter system, so as to further support the control of the inverter system switch tube action based on the control signal of the inverter system, and reduce the common mode voltage amplitude causing shaft current corrosion. Therefore, the present application can effectively suppress shaft current corrosion.

[0040] (4) The control signal modulation of the inverter system can be optimized based on the three-phase duty ratio of different sectors, so as to further control the on and off of the switch tube of the three-phase inverter system based on the control signal of the three-phase inverter system, thereby reducing the common mode voltage amplitude causing shaft current corrosion. Therefore, the present application can effectively suppress shaft current corrosion.

[0041] (5) The parameters of the target filter can be accurately selected to filter the first axis current, and the axis current corrosion suppression method based on software control optimization can be used to reduce the axis current in the common mode loop. Therefore, the present application can effectively suppress the axis current corrosion.

[0042] (6) The optimal filter can be accurately selected to support the subsequent blocking of the shaft current conduction loop. Therefore, the present application can effectively suppress shaft current corrosion.

[0043] (7) The stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor can be accurately calculated, thereby avoiding the problem that the shaft voltage of the three-phase AC motor cannot be calculated in the related technology, thereby supporting the subsequent effective suppression of shaft current corrosion.

[0044] (8) By modeling the common mode loop, the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor can be accurately calculated, thereby supporting the subsequent effective suppression of shaft current corrosion.

[0045] It should be noted that the technical effects brought about by any implementation method in the third to sixth aspects can refer to the technical effects brought about by the corresponding implementation methods in the first and second aspects, and will not be repeated here.

[0046] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application, and do not constitute an improper limitation on the present application.

[0048] Figure 1is a flow chart showing a method for inhibiting shaft current corrosion according to an exemplary embodiment;

[0049] Figure 2 is a schematic diagram of a three-phase AC motor circuit according to an exemplary embodiment;

[0050] Figure 3 is a schematic diagram showing a comparison of common-mode voltage peak values ​​of a sector according to an exemplary embodiment;

[0051] Figure 4 is a flow chart showing another method for inhibiting shaft current corrosion according to an exemplary embodiment;

[0052] Figure 5 is a schematic diagram of modeling a three-phase AC motor according to an exemplary embodiment;

[0053] Figure 6 is a schematic diagram of an equivalent circuit of a motor bearing according to an exemplary embodiment;

[0054] Figure 7 is a schematic diagram of a leakage current conduction circuit caused by a common mode voltage / shaft voltage according to an exemplary embodiment;

[0055] Figure 8 is a schematic diagram showing a connection method of an impedance analyzer according to an exemplary embodiment;

[0056] Fig. 9 is a schematic diagram of an equivalent circuit model of a common-mode loop of a three-phase motor drive system according to an exemplary embodiment;

[0057] Fig.10 is an equivalent circuit diagram of a common mode loop of a three-phase motor drive system according to an exemplary embodiment;

[0058] Fig.11 is a schematic diagram showing a topological structure of a two-level three-phase winding AC motor drive system and a traditional RLC common mode loop model according to an exemplary embodiment;

[0059] Fig.12 is a flowchart of common-mode loop modeling of a three-phase motor system according to an exemplary embodiment;

[0060] Fig.13 is a flow chart of a software method for inhibiting shaft current corrosion according to an exemplary embodiment;

[0061] Fig.14 is a block diagram of a shaft current corrosion suppression device according to an exemplary embodiment;

[0062] Fig.15 It is a block diagram of an electronic device according to an exemplary embodiment. DETAILED DESCRIPTION

[0063] In order to enable ordinary persons in the art to better understand the technical solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings.

[0064] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0065] As described in the background technology, in order to solve the problem that related technologies are difficult to effectively suppress the shaft current corrosion generated by the three-phase AC motor, the present application provides a shaft current corrosion suppression method, which can determine the three-phase duty cycle of the three-phase reference voltage vector of the three-phase AC motor in different sectors, and according to the three-phase duty cycle of different sectors, modulate and optimize the initial control signal of the three-phase inverter system to obtain the modulated optimized control signal, and further control the switches in the three-phase inverter system based on the modulated optimized control signal to obtain a first shaft current, wherein the first shaft current is less than the second shaft current, the first shaft current is the shaft current generated by the three-phase AC motor based on the modulation optimized control signal, and the second shaft current is the shaft current generated by the three-phase AC motor based on the initial control signal.

[0066] For ease of understanding, the shaft current corrosion inhibition method provided in the present application is specifically introduced below with reference to the accompanying drawings.

[0067] Figure 1 is a flow chart of a method for inhibiting shaft current corrosion according to an exemplary embodiment. Figure 1 As shown, the shaft current corrosion inhibition method includes the following steps: S101-S103.

[0068] S101. The shaft current corrosion suppression device determines the three-phase duty ratio of the three-phase reference voltage vector of the three-phase AC motor in different sectors.

[0069] Among them, the three-phase reference voltage vector can be used to characterize the synthetic vector of the three-phase voltage achieved in the three-phase AC motor control. The three-phase voltage space can be divided into six sectors according to the relative positions of the three-phase voltage vectors, and each sector corresponds to an angle range of 60 degrees. The three-phase duty cycle can be the duty cycle of the phase pulse width modulation (PWM) signal.

[0070] In one possible manner, the shaft current corrosion suppression device can perform Park transformation and Clark transformation on the three-phase current generated when the three-phase AC motor is running, and obtain the dq axis feedback current corresponding to the three-phase current. The shaft current corrosion suppression device can perform current loop and speed loop control on the dq axis feedback current, and obtain the dq axis voltage in the rotating coordinate system through the PI controller. The shaft current corrosion suppression device can perform an inverse Park transformation on the dq axis voltage to obtain the voltage vector of the three-phase AC motor in the three-phase stationary coordinate system. The shaft current corrosion suppression device can perform an inverse Clark transformation on the voltage vector in the three-phase stationary coordinate system to obtain the three-phase reference voltage vector of the three-phase AC motor.

[0071] In one example, Figure 2 As shown, it is a schematic diagram of a three-phase AC motor circuit provided by the present application. The circuit may include a permanent magnet synchronous motor (PMSM), that is, a three-phase AC motor, a current sensor, a Park transformation, an inverse Park transformation, a Clark transformation, a common mode voltage suppression modulation, a two-level inverter system, a speed loop PI controller (proportional integral (PI) controller), and a current loop PI controller.

[0072] in addition, Figure 2 In, N ref Can be used to characterize the reference speed of the speed loop. err It can be used to characterize the difference between the reference speed and the feedback speed of the speed loop. e Can be used to characterize the motor electrical angle. m Can be used to characterize the motor mechanical angle.

[0073] The shaft current corrosion suppression device can obtain the current of the three-phase AC motor in the rotating coordinate system, that is, the three-phase current i generated on the abc axis when the three-phase AC motor is running. a 、i b 、i c The shaft current corrosion suppression device can perform Park transformation, Clark transformation, and T1 transformation on the three-phase current generated by the three-phase AC motor during operation to obtain the dq-axis feedback current I corresponding to the three-phase current.q_fed ,I d_fed . dq axis feedback current I q_fed ,I d_fed Satisfies the following formula 1:

[0074]

[0075] Among them, i a It can be used to characterize the motor A phase current. b It can be used to characterize the motor B phase current. c It can be used to characterize the motor C phase current. θ can be used to characterize the rotor position angle of a three-phase AC motor. d_fed Can be used to characterize the d-axis feedback current. I q_fed It can be used to characterize the q-axis feedback current. I0 can be used to characterize the zero-axis current.

[0076] The shaft current corrosion suppression device can obtain the dq axis current deviation by subtracting the dq axis feedback current from the dq axis reference current. The dq axis current deviation is passed through the PI controller to obtain the rotating coordinate system voltage vector, that is, the dq axis voltage U d , U q The shaft current corrosion suppression device can obtain the voltage vector of the three-phase AC motor in the three-phase stationary coordinate system by inverse Park transformation (i.e. T2 transformation) of the dq axis voltage, i.e. U α , U β .U α , U β Satisfies the following formula 2:

[0077]

[0078] Among them, U α , U β It can be used to characterize the voltage vector of a three-phase AC motor in a three-phase stationary coordinate system. d , U q It can be used to characterize the voltage vector of the rotating coordinate system, that is, the dq axis voltage. θ can be used to characterize the rotor position angle of a three-phase AC motor.

[0079] The shaft current corrosion suppression device can perform an inverse Clark transformation (i.e., T3 transformation) on the voltage vector in the three-phase stationary coordinate system to obtain the three-phase reference voltage vector of the three-phase AC motor, i.e., U a , U b , U c .U a , U b , U c Satisfies the following formula three:

[0080]

[0081] Among them, U a , U b , U c It can be used to ensure the three-phase reference voltage vector. α is π / 2. U α , U β It can be used to characterize the voltage vector of a three-phase AC motor in a three-phase stationary coordinate system. U0 can be used to characterize the zero axis voltage.

[0082] In one possible manner, the shaft current corrosion suppression device may normalize the three-phase reference voltage vector and compare it with the reverse carrier to obtain the three-phase duty ratio of the three-phase reference voltage vector in different sectors.

[0083] In one example, the shaft current corrosion suppression device can perform carrier comparison on the three-phase reference voltage vector to obtain the three-phase duty ratios PWM_A, PWM_B, and PWM_C of the three-phase reference voltage vector in different sectors.

[0084] For example, as shown in Table 1, Table 1 shows the relationship between the three-phase duty ratios PWM_A, PWM_B, and PWM_C of different sectors.

[0085] Table 1

[0086] Sector Sector Range Three-phase duty cycle relationship Median 1 -30 degrees<θ≤30 degrees PWM_B≤PWM_C≤PWM_A PWM_C 2 30 degrees<θ≤90 degrees PWM_A≤PWM_B≤PWM_C PWM_B 3 120 degrees<θ≤180 degrees PWM_C≤PWM_A≤PWM_B PWM_A 4 180 degrees<θ≤240 degrees PWM_B≤PWM_C≤PWM_A PWM_C 5 240 degrees<θ≤300 degrees PWM_A≤PWM_B≤PWM_C PWM_B 6 300 degrees<θ≤360 degrees PWM_C≤PWM_A≤PWM_B PWM_A

[0087] S102. The shaft current corrosion suppression device modulates and optimizes the initial control signal of the three-phase inverter system according to the three-phase duty ratio of different sectors to obtain a control signal after modulation optimization.

[0088] The control signal can be used to control the switch tube of the inverter system to turn on or off.

[0089] In one possible manner, for each sector, the initial control signal corresponding to the middle of the three-phase duty cycle of the sector is flipped to obtain a first control signal; the first control signal is used as a control signal for driving the upper bridge arm of the three-phase inverter, and the second control signal is used as a control signal for driving the lower bridge arm of the three-phase inverter. The second control signal is a control signal obtained by inverting the first control signal.

[0090] S103. The shaft current corrosion suppression device controls switches in the three-phase inverter system based on the control signal after modulation optimization to obtain a first shaft current.

[0091] The first shaft current may be smaller than the second shaft current. The first shaft current may be a shaft current generated by the three-phase AC motor based on the adjusted control signal. The second shaft current may be a shaft current generated by the three-phase AC motor based on the initial control signal.

[0092] In one possible approach, the shaft current may be positively correlated with the common mode voltage. That is, the smaller the common mode voltage, the smaller the shaft current. The common mode voltage satisfies the following formula 4:

[0093]

[0094] Among them, V cm is the common mode voltage amplitude. V a 、V b 、V c It can be used to characterize the common mode voltage of each phase of a three-phase AC motor. a 、V b 、V c Satisfies the following formula 5:

[0095]

[0096] Among them, V x It can be used to characterize the common mode voltage of the xth phase. dc S is the DC bus voltage of the motor. x Can be used to characterize the xth control signal.

[0097] In one example, as shown in Table 2, Table 2 shows the initial control signal and the adjusted control signal.

[0098] Table 2

[0099]

[0100] In another example, Figure 3 FIG. 1 is a schematic diagram showing a comparison of common-mode voltage peak values ​​of a sector.

[0101] Among them, before optimization is the common mode voltage peak value ±U dc / 2, the optimized common mode voltage peak is ±U dc / 6, the amplitude is reduced to 1 / 3 of the original.

[0102] based on Figure 1 According to the technical solution in the invention, the present application can optimize the modulation of the initial control signal, reduce the proportion of the zero vector of the control signal, and reduce the peak value of the common-mode voltage according to the common-mode voltage generation mechanism of the three-phase AC motor system, thereby suppressing the shaft current corrosion caused by the common-mode voltage from the perspective of suppressing the noise source. In addition, the present application is simple and flexible, and can reduce the high dv / dt problem of the common-mode voltage caused by the inverter dead zone. Therefore, the present application can effectively suppress the shaft current corrosion.

[0103] In some embodiments, Figure 4 is a flow chart of another method for inhibiting shaft current corrosion according to an exemplary embodiment. Figure 4As shown, the shaft current corrosion inhibition method includes the following steps: S201-S202.

[0104] S201. The shaft current corrosion suppression device models the common mode loop of the three-phase AC motor to obtain a common mode loop model, and determines a target filter based on the common mode loop model.

[0105] Among them, the target filter can be the optimal filter selection based on the electric drive shaft current threshold requirement and power density requirement and based on the stray capacitance parameters and shaft voltage.

[0106] In one possible manner, the shaft current corrosion suppression device can determine the shaft current corresponding to the common mode loop model. The shaft current corrosion suppression device can select parameters for multiple filters based on the shaft current to obtain a target filter.

[0107] In one example, the multiple filters may include passive filters and active filters. The passive filters may increase the impedance of the common mode loop to suppress the shaft current. The active filters may be external semiconductor devices and electronic circuits to suppress the shaft current.

[0108] In one possible manner, the shaft current corrosion suppression device can determine the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor based on the common mode loop model. In one possible manner, the shaft current corrosion suppression device can determine the shaft current corresponding to the filter based on the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor.

[0109] In another possible manner, the shaft current corrosion suppression device can perform common mode loop modeling on the three-phase AC motor to obtain the corresponding stray parameters of the three-phase AC motor.

[0110] Among them, the corresponding stray parameters of the three-phase AC motor include stray parameters between the stator core and the stator winding, stray parameters between the stator core and the rotor core, and stray parameters between the stator winding and the stator core.

[0111] In one example, the shaft current corrosion suppression device can be based on the partial capacitance theory of multi-conductor systems, that is, when there is a dielectric material between two conductors, stray capacitance may appear. Figure 5As shown, it is a schematic diagram of modeling a three-phase AC motor. The shaft current corrosion suppression device can model the three-phase AC motor to obtain a three-conductor electrostatic independent system of the motor stator core (including the housing), the motor stator winding, and the motor rotor core (including the permanent magnet). Among them, the stray parameters between the stator core and the stator winding, the stray parameters between the stator core and the rotor core, and the stray parameters between the stator winding and the stator core mainly appear in the form of parasitic capacitance. The shaft current corrosion suppression device can use an analytical method to calculate the stray parameters between the stator core and the stator winding, the stray parameters between the stator core and the rotor core, and the stray parameters between the stator winding and the stator core.

[0112] Optionally, the stray parameter between the stator winding and the stator core can be equivalent to a flat plate capacitor model, and the stray parameter C between the stator winding and the stator core is sf Satisfies the following formula six:

[0113]

[0114] Among them, N S It can be used to characterize the number of slots in the motor. ε0 can be used to characterize the dielectric constant. r It can be used to characterize the relative dielectric constant. g0 can be used to characterize the thickness of the insulation slot. L can be used to characterize the effective length of the stator core. C sf It can be used to characterize the stray parameters between the stator winding and the stator core.

[0115] Optionally, the stray parameter between the stator winding and the rotor core can be equivalent to a plate capacitor containing multilayer dielectrics, and the stray parameter C between the stator winding and the rotor core is sr Satisfy the following formula seven:

[0116]

[0117] Among them, ε r1 , ε r2 They are used to characterize the relative dielectric constants of the slot cover insulation and the slot wedge. S can be used to characterize the effective area of ​​the capacitor. C sr It can be used to characterize the stray parameters between the stator winding and the rotor core. ε0 can be used to characterize the dielectric constant. d1 can be used to characterize the distance from the stator winding to the slot wedge, and d2 can be used to characterize the distance from the rotor core to the slot wedge.

[0118] Optionally, the distance between the rotor core and the stator core is relatively far, and the slotting has an effect on the inside of the motor to increase the effective air gap, so it can be approximated that there is no slot between the rotor core and the stator core. In this case, the stray parameter C between the rotor core and the stator core is rf Satisfies the following formula eight:

[0119] Crf =2πε0·L r ·ln(R f +k c δ) / R r Formula 8

[0120] Among them, δ can be used to characterize the equivalent air gap of the motor. c Can be used to characterize the Karlsruhe coefficient. f It can be used to characterize the equivalent resistance of the stator core. r It can be used to characterize the equivalent inductance of the rotor core. rf It can be used to characterize the stray parameters between the rotor core and the stator core.

[0121] In one possible way, in view of the complexity of the motor structure and the interaction between the three conductors, the shaft current corrosion suppression device can use the finite element method to perform numerical calculations of the electromagnetic field to solve the capacitive coupling parameters. The shaft current corrosion suppression device can set the stator core and the housing as the reference potential (zero potential) and apply excitation voltages to the stator winding and the rotor core respectively. In this electric field, the potential φ at each point follows Formula 9, that is, the Laplace equation:

[0122]

[0123] In one possible way, when solving the capacitance matrix (i.e., inductance matrix) of the three-conductor electrostatic independent system, the shaft current corrosion inhibition device can set the solution items of the capacitance matrix, finely divide the solution grid, and perform numerical calculations. Through this process, the inductance matrix reflecting the electrostatic interaction between conductors can be accurately obtained. The inductance matrix satisfies the following formula 10:

[0124]

[0125] Among them, s, r, and f can be used to characterize the stator winding, rotor core, and stator core, respectively. s , β r Can be used to characterize the self-inductance coefficient. sr , β rs Can be used to characterize mutual inductance.

[0126] In one possible way, the relationship between inductance and potential is The potentials of the stator winding and the rotor core can satisfy the following formula 11 and formula 12:

[0127]

[0128] Among them, q s Can be used to characterize the potential of the stator winding. r Can be used to characterize the potential of the rotor core.s , β r Can be used to characterize the self-inductance coefficient. sr , β rs Can be used to characterize mutual inductance. C rf It can be used to characterize the stray parameters between the rotor core and the stator core. sr It can be used to characterize the stray parameters between the stator winding and the rotor core. sf It can be used to characterize the stray parameters between the stator winding and the stator core.

[0129] According to Formula 11 and Formula 12, the internal stray capacitance of the motor can be determined, that is, Formula 13:

[0130]

[0131] Among them, β s , β r Can be used to characterize the self-inductance coefficient. sr , β rs Can be used to characterize mutual inductance. C rf It can be used to characterize the stray parameters between the rotor core and the stator core. sr It can be used to characterize the stray parameters between the stator winding and the rotor core. sf It can be used to characterize the stray parameters between the stator winding and the stator core.

[0132] It should be noted that the capacitance value obtained above is a value per unit axial length. The shaft current corrosion suppression device can determine the effective axial length of the motor and obtain the actual stray parameters.

[0133] In one possible approach, the shaft current corrosion suppression device can perform common mode loop modeling on the motor bearing to obtain the corresponding stray parameters of the motor bearing.

[0134] In one example, Figure 6 As shown, Figure 6 This is a schematic diagram of an equivalent circuit of a motor bearing. The motor bearing structure can include balls, inner and outer rings, and insulating oil film. During normal operation, the oil film can be used as a dielectric capacitor to isolate the balls from the inner and outer rings. At this time, the bearing can be equivalent to an oil film as a dielectric capacitor element. When the shaft voltage of the motor exceeds the maximum voltage that the oil film can withstand, a high current density current will be formed. At this time, the impedance of the bearing is mainly determined by the bearing resistance. Therefore, the bearing can be equivalent to the stray parameter (bearing capacitance) C corresponding to the motor bearing b With random switch S b After being connected in parallel, it is connected with the bearing resistance R b Series circuit model.

[0135] Among them, the stray parameter C corresponding to the motor bearingb It can be equivalent to a flat plate capacitor with equal area and a flat plate capacitor with oil film as the medium. The stray parameter C corresponding to the motor bearing b The following formula 14 and formula 15 are satisfied:

[0136]

[0137] S b =π·ab Formula 15

[0138] Among them, C b It can be used to characterize the stray parameters corresponding to the motor bearings. b Can be used to characterize random switching. b It can be used to characterize the plate capacitance of the oil film. a is the major axis of the ellipse formed by the contact deformation at the contact point, and b is the minor axis of the ellipse formed by the contact deformation at the contact point.

[0139] In one possible approach, the shaft current corrosion suppression device can perform common mode loop modeling on the three-phase AC motor system to obtain the shaft voltage of the three-phase AC motor.

[0140] In another possible manner, the shaft current corrosion suppression device can model the common mode loop of the three-phase AC motor system. The staff or the shaft current corrosion suppression device can derive a simplified equivalent circuit of the common mode loop based on the shaft current conduction path and the Thevenin equivalent circuit principle, and derive the shaft voltage calculation formula and the casing voltage calculation formula of the three-phase AC motor based on the equivalent circuit. The staff or the shaft current corrosion suppression device can calculate the shaft voltage and the casing voltage based on the shaft voltage calculation formula and the casing voltage calculation formula.

[0141] In one example, the stray capacitance obtained above can form a common mode loop, providing a path for the generation of common mode leakage current and shaft current. The total common mode current on the AC side of the motor satisfies the following formula 16:

[0142] i cm =(i sa +i sb +i sc )+i rcm +i bcm =i scm +i rcm +i bcm Formula 16

[0143] Among them, i cm is the total mode current. sa 、i sb 、i sc is the common mode leakage current flowing from the three-phase stator winding to the stator core. scm is the common mode leakage current of the stator winding coupled to the stator core. rcmis the common mode leakage current from the rotor core to the stator core. bcm Leakage current of the bearing.

[0144] In one example, Figure 7 FIG. 1 is a schematic diagram of a leakage current conduction circuit caused by a common mode voltage / axis voltage.

[0145] Figure 7 The rotor core, shaft, bearings, stator winding and stator core (casing) are included. dg It can be used to characterize the equivalent impedance of the inverter to the midpoint of the DC bus. cable It can be used to characterize the equivalent impedance of the cables used to connect the motor windings in each bridge arm of the inverter. sa 、i sb 、i sc is the common mode leakage current flowing from the three-phase stator winding to the stator core. scm is the common mode leakage current of the stator winding coupled to the stator core. rcm is the common mode leakage current from the rotor core to the stator core. bcm is the leakage current of the bearing part. C sr1 , C sr2 , C sr3 It can be used to characterize the stray parameters between the stator winding and the rotor core. sf1 , C sf2 , C sf3 It can be used to characterize the stray parameters between the stator winding and the stator core. rf It can be used to characterize the stray parameters between the stator core and the rotor core. VA, VB

[0146] In another example, Figure 8 The figure shows a schematic diagram of a connection method of an impedance analyzer.

[0147] The shaft current corrosion suppression device can use an impedance analyzer to measure the motor common mode impedance Z under three connection modes: three-phase winding connection, single-phase winding disconnection, and three-phase winding disconnection. cm The winding connection method on the AC side motor differential mode power circuit affects the impedance Z on the AC side common mode circuit. cm There is no influence, and the common mode impedance is not affected by the winding connection method in the power loop.

[0148] The shaft current corrosion suppression device can construct a common-mode loop model of the three-phase motor drive system based on the common-mode leakage current path and common-mode impedance characteristics inside the motor.

[0149] like Fig. 9, which is a schematic diagram of an equivalent circuit model of a common-mode circuit of a three-phase motor drive system, wherein the common-mode equivalent circuit (common-mode stray circuit) on the AC side exists independently and is not directly electrically connected to the differential-mode power circuit.

[0150] Among them, Z dg It can be used to characterize the equivalent impedance of the inverter to the midpoint of the DC bus. cable It can be used to characterize the equivalent impedance of the cables used to connect the motor windings in each bridge arm of the inverter. sa 、i sb 、i sc is the common mode leakage current flowing from the three-phase stator winding to the stator core. scm is the common mode leakage current of the stator winding coupled to the stator core. rcm is the common mode leakage current from the rotor core to the stator core. bcm is the leakage current of the bearing. sr It can be used to characterize the stray parameters between the stator winding and the rotor core. sf It can be used to characterize the stray parameters between the stator winding and the stator core. rf It can be used to characterize the stray parameters between the stator core and the rotor core. Rs can be used to characterize the resistance. Ls can be used to characterize the inductance. A, B, and C can be used to characterize the three-phase bridge arm circuit. V A 、V B 、V C It can be used to characterize the three bridge arm voltages. Vma, Vmb, and Vmc can be used to characterize the back electromotive force.

[0151] like Fig.10 As shown in FIG. 1 , it is an equivalent circuit diagram of a common-mode loop of a three-phase motor drive system. The shaft current corrosion suppression device can be based on the impedance symmetry of the stray parameter branch of the permanent magnet synchronous motor, and the common-mode loop model of the three-phase motor drive system can be further simplified to obtain an equivalent circuit model of the common-mode loop of the three-phase motor drive system. Among them, the motor system common-mode loop impedance Z cm Satisfies the following formula seventeen:

[0152]

[0153] Among them, Z dg It can be used to characterize the equivalent impedance of the inverter to the midpoint of the DC bus. cable It can be used to characterize the equivalent impedance of the cables used to connect the motor windings in each bridge arm of the inverter. sf It can be used to characterize the stray equivalent impedance of each phase winding of the motor to the stator housing. sr It can be used to characterize the stray equivalent impedance of each phase winding of the motor to the rotor core. rfIt can be used to characterize the stray equivalent impedance of the motor rotor core to the stator housing. b It can be used to characterize the stray equivalent impedance of the bearing part.

[0154] In one possible approach, the shaft current corrosion suppression device can calculate the shaft voltage V based on the common mode loop equivalent circuit model of the three-phase motor drive system. b . Shaft voltage V b Satisfy formula 18:

[0155]

[0156] Among them, V b Can be used to characterize shaft voltage. dg It can be used to characterize the equivalent impedance of the inverter to the midpoint of the DC bus. cable It can be used to characterize the equivalent impedance of the cables used to connect the motor windings in each bridge arm of the inverter. sf It can be used to characterize the stray equivalent impedance of each phase winding of the motor to the stator housing. sr It can be used to characterize the stray equivalent impedance of each phase winding of the motor to the rotor core. rf It can be used to characterize the stray equivalent impedance of the motor rotor core to the stator housing. b It can be used to characterize the stray equivalent impedance of the bearing part.

[0157] Case voltage V frame Satisfies the following formula 19:

[0158]

[0159] Among them, V frame Can be used to characterize the chassis voltage. dg It can be used to characterize the equivalent impedance of the inverter to the midpoint of the DC bus. cable It can be used to characterize the equivalent impedance of the cables used to connect the motor windings in each bridge arm of the inverter. sf It can be used to characterize the stray equivalent impedance of each phase winding of the motor to the stator housing. sr It can be used to characterize the stray equivalent impedance of each phase winding of the motor to the rotor core. rf It can be used to characterize the stray equivalent impedance of the motor rotor core to the stator housing. b It can be used to characterize the stray equivalent impedance of the bearing part.

[0160] In one possible manner, the shaft current corrosion suppression device can determine the shaft current corresponding to the filter based on the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings and the shaft voltage of the three-phase AC motor, so as to further determine the target filter based on the shaft currents of multiple filters.

[0161] S202. The shaft current corrosion suppression device filters the first shaft current based on a target filter.

[0162] The filtered first axis current is smaller than the first axis current.

[0163] In one possible manner, in a circuit of a three-phase AC motor, an output end of a three-phase inverter system is connected to an input end of a target filter. The three-phase inverter system can be used to generate a first shaft current based on a control signal after modulation optimization, and the shaft current corrosion suppression device can control a switch in the three-phase inverter system based on the control signal after modulation optimization to obtain the first shaft current.

[0164] The target filter can be used to filter the first axis current, that is, the target filter filters the first axis current generated by the three-phase AC motor to obtain the filtered first axis current.

[0165] based on Figure 4 According to the technical solution in the invention, the present application can accurately select parameters for the target filter to filter the first axis current, and cooperate with the aforementioned axis current corrosion suppression method based on software control optimization to reduce the axis current in the common mode loop. Therefore, the present application can effectively suppress the axis current corrosion.

[0166] In some embodiments, Fig.11 , which is a schematic diagram of a topological structure of a two-level three-phase winding AC motor drive system and a traditional RLC common-mode loop model. Fig.11 It includes a DC power supply 1, a DC power supply 2, a DC bus capacitor 3, an inverter system 4 composed of a two-level inverter, a three-phase AC winding motor, and a traditional RLC common mode loop model.

[0167] In one possible approach, in the common-mode loop model of the RLC series structure of a traditional three-phase electric drive system, the differential-mode electrical parameters are coupled with the common-mode stray parameters, making it impossible to accurately calculate the common-mode loop impedance, shaft voltage, and casing voltage.

[0168] In some embodiments, Fig.12The figure shows a flow chart of common-mode loop modeling of a three-phase motor system. In one possible manner, the shaft current corrosion suppression device can perform common-mode loop modeling on a three-phase AC motor in a motor system including a filter, and obtain stray parameters corresponding to the three-phase AC motor. The shaft current corrosion suppression device can perform common-mode loop modeling on motor bearings in a common-mode loop including a filter, and obtain stray parameters corresponding to the motor bearings. The shaft current corrosion suppression device can perform common-mode loop modeling and equivalent loop simplification on a motor system including a filter. The shaft current corrosion suppression device can perform common-mode loop modeling and equivalent loop simplification on a motor system including a filter, and calculate the motor shaft voltage and the housing voltage.

[0169] like Fig.13 The figure shows a flow chart of a software method for suppressing shaft current corrosion. The shaft current corrosion suppression device can determine the three-phase reference voltage vector of the three-phase AC motor in a stationary coordinate system. The shaft current corrosion suppression device can determine the three-phase duty ratio of the three-phase reference voltage vector of the three-phase AC motor in different sectors. The shaft current corrosion suppression device can adjust the initial control signal of the inverter system of the three-phase AC motor according to the three-phase duty ratio of different sectors to obtain an adjusted control signal. The shaft current corrosion suppression device can control the operating state of the three-phase AC motor based on the adjusted control signal.

[0170] Based on this, the present application can distinguish the main power circuit and separately model the common-mode circuit of the motor that causes the shaft current, so as to realize the theoretical calculation of the shaft voltage and the casing voltage, solve the problem that the current shaft voltage and the casing voltage are difficult to measure, and propose a carrier comparison method to reduce the proportion of zero vector usage based on the principle of common-mode voltage generation. The control algorithm is simple and flexible, and while reducing the common-mode voltage assignment to 1 / 3 of the original, it can reduce the problem of high common-mode voltage caused by the inverter. Further, based on the calculation of the stray impedance of the common-mode circuit, the software modulation method is optimized to cooperate with the system method of hardware blocking the conduction circuit to fundamentally solve the shaft current corrosion problem of the three-phase electric drive system.

[0171] Fig.14 FIG. 1 is a block diagram of a shaft current corrosion suppression device according to an exemplary embodiment. Fig.14 The shaft current corrosion suppression device includes: a determination unit 301 , an adjustment unit 302 , a control unit 303 and a processing unit 304 .

[0172] In a possible manner, the determination unit is used to determine the three-phase duty ratio of the three-phase reference voltage vector of the three-phase AC motor in different sectors.

[0173] In one possible manner, the adjustment unit is used to modulate and optimize the initial control signal of the three-phase inverter system according to the three-phase duty ratios of different sectors to obtain a modulated and optimized control signal. The modulated and optimized control signal is used to control the on and off of the switch tube in the three-phase inverter system.

[0174] In one possible manner, the control unit is used to control the switches in the three-phase inverter system based on the control signal after modulation optimization to obtain a first shaft current. The first shaft current is less than the second shaft current. The first shaft current is the shaft current generated by the three-phase AC motor based on the control signal after modulation optimization. The second shaft current is the shaft current generated by the three-phase AC motor based on the initial control signal.

[0175] In one possible manner, the processing unit is specifically used to: perform Park transformation and Clark transformation on the three-phase current generated when the three-phase AC motor is running, and obtain the dq axis feedback current corresponding to the three-phase current. Perform current loop and speed loop control on the dq axis feedback current, and obtain the dq axis voltage in the rotating coordinate system through the PI controller. Perform an inverse Park transformation on the dq axis voltage to obtain the voltage vector of the three-phase AC motor in the three-phase stationary coordinate system. Perform an inverse Clark transformation on the voltage vector in the three-phase stationary coordinate system to obtain the three-phase reference voltage vector of the three-phase AC motor.

[0176] In one possible manner, the determination unit is used to normalize the three-phase reference voltage vector and perform carrier comparison to obtain the three-phase duty ratios of the three-phase reference voltage vector in different sectors.

[0177] In one possible manner, the adjustment unit is specifically used to: for each sector, flip the initial control signal corresponding to the three-phase duty cycle of the sector to obtain a first control signal. The first control signal is used as a control signal to drive the upper bridge arm of the three-phase inverter, and the second control signal is used as a control signal to drive the lower bridge arm of the three-phase inverter. The second control signal is a control signal obtained by inverting the first control signal.

[0178] In one possible manner, the determination unit is further used to model the common mode loop of the three-phase AC motor to obtain a common mode loop model, and determine a target filter based on the common mode loop model. The processing unit is further used to filter the first axis current based on the target filter. The filtered first axis current is less than the first axis current.

[0179] In a possible manner, the determination unit is specifically configured to: determine the shaft current corresponding to the common mode loop model, and select parameters for multiple filters based on the shaft current to obtain a target filter.

[0180] In one possible manner, the determination unit is specifically used to: determine the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor based on the common mode loop model. Determine the shaft current corresponding to the filter based on the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor.

[0181] In one possible manner, the determination unit is specifically used to: perform common mode loop modeling on the three-phase AC motor to obtain the corresponding stray parameters of the three-phase AC motor. The corresponding stray parameters of the three-phase AC motor include stray parameters between the stator core and the stator winding, stray parameters between the stator core and the rotor core, and stray parameters between the stator winding and the stator core. Perform common mode loop modeling on the motor bearing to obtain the corresponding stray parameters of the motor bearing. Perform common mode loop modeling on the three-phase AC motor system to obtain the shaft voltage of the three-phase AC motor.

[0182] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0183] Fig.15 FIG. 1 is a block diagram of an electronic device according to an exemplary embodiment. Fig.15 As shown, the electronic device includes but is not limited to: a processor 401 and a memory 402 .

[0184] The memory 402 is used to store executable instructions of the processor 401. It can be understood that the processor 401 is configured to execute instructions to implement the shaft current corrosion suppression method in the above embodiment.

[0185] It should be noted that those skilled in the art can understand that Fig.15 The electronic device structure shown in the figure does not constitute a limitation on the electronic device, and the electronic device may include Fig.15 More or fewer components may be shown, or certain components may be combined, or the components may be arranged differently.

[0186] The processor 401 is the control center of the electronic device. It uses various interfaces and lines to connect various parts of the entire electronic device. By running or executing software programs and / or modules stored in the memory 402, and calling data stored in the memory 402, it performs various functions of the electronic device and processes data, thereby monitoring the electronic device as a whole. The processor 401 may include one or more processing units. Optionally, the processor 401 may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface, and application programs, and the modem processor mainly processes wireless communications. It is understandable that the above-mentioned modem processor may not be integrated into the processor 401.

[0187] The memory 402 may be used to store software programs and various data. The memory 402 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required by at least one functional module (such as a determination unit, a processing unit, etc.), etc. In addition, the memory 402 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0188] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory 402 including instructions, and the above instructions can be executed by a processor 401 of an electronic device to implement the method in the above embodiment.

[0189] In actual implementation, Fig.14 The functions of the determination unit 301, the adjustment unit 302, the control unit 303, and the processing unit 304 can all be implemented by Fig.15 The processor 401 in the embodiment calls the computer program stored in the memory 402. The specific execution process can refer to the description of the method part in the above embodiment, which will not be repeated here.

[0190] Optionally, the computer-readable storage medium may be a non-temporary computer-readable storage medium, for example, the non-temporary computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0191] In an exemplary embodiment, the present application also provides a computer program product including one or more instructions, and the one or more instructions can be executed by the processor 401 of the electronic device to complete the method in the above embodiment.

[0192] It should be noted that when the instructions in the above-mentioned computer-readable storage medium or one or more instructions in the computer program product are executed by the processor of the electronic device, the various processes of the above-mentioned method embodiment are implemented, and the same technical effect as the above-mentioned method can be achieved. To avoid repetition, they will not be repeated here.

[0193] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0194] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0195] The units described as separate components may or may not be physically separated, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0196] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0197] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or the full classification part or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium, including a number of instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to execute the full classification part or part of the steps of each embodiment method of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, ROM, RAM, disk or CD and other media that can store program code.

[0198] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for inhibiting shaft current corrosion, characterized in that: include: Determine the three-phase duty ratio of the three-phase reference voltage vector of the three-phase AC motor in different sectors; According to the three-phase duty ratios of the different sectors, an initial control signal of the three-phase inverter system is modulated and optimized to obtain a control signal after modulation optimization; Based on the control signal after modulation optimization, the switches in the three-phase inverter system are controlled to obtain a first shaft current; the first shaft current is smaller than the second shaft current; the first shaft current is the shaft current generated by the three-phase AC motor based on the control signal after modulation optimization; the second shaft current is the shaft current generated by the three-phase AC motor based on the initial control signal.

2. The method according to claim 1, characterized in that: The method further comprises: Performing Park transformation and Clark transformation on the three-phase current generated when the three-phase AC motor is running to obtain dq-axis feedback current corresponding to the three-phase current; Performing current loop and speed loop control on the dq axis feedback current, and obtaining the dq axis voltage in the rotating coordinate system through a PI controller; Performing an inverse Park transformation on the dq axis voltage to obtain a voltage vector of the three-phase AC motor in a three-phase stationary coordinate system; An inverse Clark transformation is performed on the voltage vector in the three-phase stationary coordinate system to obtain a three-phase reference voltage vector of the three-phase AC motor.

3. The method according to claim 2, characterized in that The method of determining the three-phase duty ratio of the three-phase reference voltage vector of the three-phase AC motor in different sectors includes: The three-phase reference voltage vector is normalized and carrier comparison is performed to obtain the three-phase duty ratio of the three-phase reference voltage vector in different sectors.

4. The method according to claim 3, characterized in that The optimized modulation control signal includes a first control signal and a second control signal; the optimized modulation control signal is obtained by modulating and optimizing the initial control signal of the inverter system of the three-phase AC motor according to the three-phase duty ratios of the different sectors, including: For each sector, an initial control signal corresponding to the middle duty cycle of the three-phase of the sector is flipped to obtain a first control signal; The first control signal is used as a control signal for driving an upper bridge arm of a three-phase inverter, and the second control signal is used as a control signal for driving a lower bridge arm of a three-phase inverter; the second control signal is a control signal obtained by inverting the first control signal.

5. The method according to claim 1, characterized in that The method further comprises: Modeling the common mode loop of the three-phase AC motor to obtain a common mode loop model, and determining a target filter based on the common mode loop model; The first axis current is filtered based on the target filter; the filtered first axis current is less than the first axis current.

6. The method according to claim 5, characterized in that The step of determining a target filter based on the common mode loop model comprises: determining a shaft current corresponding to the common mode loop model; Based on the shaft current, parameter selection is performed on multiple filters to obtain the target filter.

7. The method according to claim 6, characterized in that The determining of the shaft current corresponding to the common mode loop model comprises: Based on the common mode loop model, determining stray parameters corresponding to the three-phase AC motor, stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor; The shaft current corresponding to the filter is determined based on the stray parameters corresponding to the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor.

8. The method according to claim 7, characterized in that The determining of the stray parameters corresponding to the common mode loop of the three-phase AC motor, the stray parameters corresponding to the motor bearings, and the shaft voltage of the three-phase AC motor includes: Performing common mode loop modeling on the three-phase AC motor to obtain stray parameters corresponding to the three-phase AC motor; the stray parameters corresponding to the three-phase AC motor include stray parameters between the stator core and the stator winding, stray parameters between the stator core and the rotor core, and stray parameters between the stator winding and the stator core; Performing common mode loop modeling on the motor bearing to obtain stray parameters corresponding to the motor bearing; A common-mode loop model is performed on the three-phase AC motor system to obtain the shaft voltage of the three-phase AC motor.

9. A shaft current corrosion suppression device, characterized in that: The device comprises: a determination unit, an adjustment unit and a control unit; The determination unit is used to determine the three-phase duty ratio of the three-phase reference voltage vector of the three-phase AC motor in different sectors; The adjustment unit is used to modulate and optimize the initial control signal of the three-phase inverter system according to the three-phase duty ratios of the different sectors to obtain a control signal after modulation optimization; the control signal after modulation optimization is used to control the on and off of the switch tube in the three-phase inverter system; The control unit is used to control the switches in the three-phase inverter system based on the modulation optimized control signal to obtain a first shaft current; the first shaft current is smaller than the second shaft current; the first shaft current is the shaft current generated by the three-phase AC motor based on the modulation optimized control signal; the second shaft current is the shaft current generated by the three-phase AC motor based on the initial control signal.

10. A circuit, characterized in that: The circuit comprises: a three-phase inverter system and a target filter; The output end of the three-phase inverter system is connected to the input end of the target filter; The three-phase inverter system is used to generate a first axis current based on a modulation optimized control signal; The target filter is used to filter the first axis current.

11. An electronic device, characterized in that: include: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the instructions to implement the method according to any one of claims 1 to 8.

12. A computer-readable storage medium, characterized in that: When the computer-executable instructions stored in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device can perform the method as claimed in any one of claims 1 to 8.

13. A computer program product comprising instructions, characterized in that When the instructions are executed by a computer, the computer is caused to perform the method according to any one of claims 1 to 8.

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