Active discharge method, device and storage medium for motor drive system

Abstract

An embodiment of the present invention provides an active discharge method, device, and storage medium for a motor drive system. The method includes: receiving an active discharge instruction; determining whether the motor drive system has a fault that does not allow active discharge; if no fault does not allow active discharge, determining whether the motor drive system is installed with a bus voltage sensor and whether there is a voltage sampling fault; if no bus voltage sensor is installed or there is a voltage sampling fault, obtaining the three-phase current of the motor winding, the magnetic pole position of the motor rotor, and the motor speed of the motor drive system; determining a first direct-axis basic voltage control variable and a first orthogonal-axis basic voltage control variable of the motor stator based on the three-phase current, the magnetic pole position, and the motor speed; determining a bus voltage value of the motor drive system based on the first direct-axis basic voltage control variable and the first orthogonal-axis basic voltage control variable; and controlling active discharge of the permanent magnet synchronous motor based on the motor speed and the bus voltage value.

Description

Technical Field

[0001] The present invention relates to the field of motor control technology, and in particular to an active discharge method, device, storage medium and motor drive system for a motor drive system. Background Art

[0002] Construction vehicles and automobiles equipped with inverter-driven high-voltage motor systems typically use large DC capacitors at the DC power input as energy storage and filtering elements. In the event of a serious collision, the energy stored in the DC capacitors must be quickly released, rapidly reducing the voltage across the capacitors to below a safe level. This allows for emergency power-off of high-voltage components, ensuring high-voltage safety in the construction vehicle or automobile.

[0003] At present, since there is no need to increase the cost of additional circuits, the capacitor voltage is often quickly reduced by actively discharging the motor windings when the high voltage is turned on. However, when a serious fault occurs in an engineering vehicle or automobile, it is very likely to cause the voltage sampling circuit (bus voltage sensor or voltage sampling circuit) of the motor drive system to fail. The motor winding discharge schemes in the prior art all rely on the voltage signal collected by the voltage sampling circuit. When the voltage sampling circuit fails, it is difficult to actively discharge the capacitor through the motor windings, making it impossible for engineering vehicles and automobiles to discharge the voltage of the high-voltage system to below the safe voltage within the specified time. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide an active discharge method, device, storage medium and motor drive system for a motor drive system, so as to solve the problem in the prior art that the motor drive system is difficult to perform active discharge when a bus voltage sensor is not installed or there is a voltage sampling fault.

[0005] In order to achieve the above-mentioned object, the first aspect of the present invention provides an active discharge method for a motor drive system, wherein the motor drive system includes a permanent magnet synchronous motor, including:

[0006] receiving an active discharge instruction;

[0007] Determine whether the motor drive system has a fault that does not allow active discharge;

[0008] In the absence of a fault that does not allow active discharge, determine whether the motor drive system is equipped with a bus voltage sensor and whether there is a voltage sampling fault;

[0009] When the bus voltage sensor is not installed or there is a voltage sampling fault, obtain the three-phase current of the motor winding, the magnetic pole position of the motor rotor and the motor speed of the motor drive system;

[0010] Determine a first direct-axis basic voltage control variable and a first orthogonal-axis basic voltage control variable of the motor stator according to the three-phase current, the magnetic pole position and the motor speed;

[0011] Determine the bus voltage value of the motor drive system according to the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity;

[0012] The active discharge of the permanent magnet synchronous motor is controlled according to the motor speed and bus voltage value.

[0013] In an embodiment of the present invention, determining the first direct-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity of the motor stator according to the three-phase current, the magnetic pole position and the motor speed includes: determining the first direct-axis two-beat average current value and the first orthogonal-axis two-beat average current value of the motor stator according to the three-phase current and the magnetic pole position; determining the first direct-axis average current given value and the first orthogonal-axis average current given value of the motor stator according to the motor speed; adjusting the first direct-axis two-beat average current value and the first orthogonal-axis two-beat average current value according to the first direct-axis average current given value, the first orthogonal-axis average current given value and the magnetic pole position; adjusting the first direct-axis two-beat average current value and the first orthogonal-axis two-beat average current value to meet the convergence condition; determining the first direct-axis basic voltage control quantity according to the adjusted first direct-axis two-beat average current value and the first direct-axis average current given value; determining the first orthogonal-axis basic voltage control quantity according to the adjusted first orthogonal-axis two-beat average current value and the first orthogonal-axis average current given value.

[0014] In an embodiment of the present invention, determining a first direct-axis average current given value and a first orthogonal-axis average current given value of a motor stator according to a motor speed includes: obtaining maximum allowable absolute values ​​of a permanent magnet flux coefficient, a direct-axis synchronous inductance, and a direct-axis demagnetization current of the permanent magnet synchronous motor when the absolute value of the motor speed is greater than or equal to a preset multiple of a safe speed of the permanent magnet synchronous motor; determining the first direct-axis average current given value according to the maximum allowable absolute values ​​of the permanent magnet flux coefficient, the direct-axis synchronous inductance, and the direct-axis demagnetization current; and determining the first orthogonal-axis average current given value to be a preset value.

[0015] In an embodiment of the present invention, determining the first direct-axis average current given value and the first orthogonal-axis average current given value of the motor stator according to the motor speed includes: when the absolute value of the motor speed is less than a preset multiple of the safe speed of the permanent magnet synchronous motor, determining that the first direct-axis average current given value and the first orthogonal-axis average current given value are both preset values.

[0016] In an embodiment of the present invention, determining the bus voltage value of the motor drive system based on the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity includes: determining a voltage judgment value based on the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity; when the voltage judgment value is greater than or equal to the second preset value and less than or equal to the first preset value, determining the direct-axis output voltage and the orthogonal-axis output voltage of the motor stator; determining the bus voltage value based on the direct-axis output voltage, the orthogonal-axis output voltage, the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity.

[0017] In an embodiment of the present invention, determining the bus voltage value of the motor drive system according to the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity includes: determining a voltage judgment value according to the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity; when the voltage judgment value is less than a second preset value, determining the direct-axis high-frequency current component and the orthogonal-axis high-frequency current component of the motor stator according to the direct-axis current corresponding to the adjusted first direct-axis two-beat average current value, the orthogonal-axis current corresponding to the adjusted first orthogonal-axis two-beat average current value, the historical direct-axis current of the motor stator in the previous beat, and the historical orthogonal-axis current. current component; determine the first direct-axis high-frequency current amplitude of the motor stator according to the direct-axis high-frequency current component, the orthogonal-axis high-frequency current component and the direct-axis high-frequency voltage reference control quantity corresponding to the basic voltage amplitude; when the first direct-axis high-frequency current amplitude is less than the preset direct-axis high-frequency current reference value, determine the bus voltage value according to the safe voltage and maximum voltage error of the permanent magnet synchronous motor; when the direct-axis high-frequency current amplitude is greater than or equal to the direct-axis high-frequency current reference value, determine the bus voltage value according to the current sampling period of the permanent magnet synchronous motor, the direct-axis high-frequency inductance, the first direct-axis high-frequency current amplitude and the basic voltage amplitude.

[0018] In an embodiment of the present invention, controlling the active discharge of the permanent magnet synchronous motor according to the motor speed and the bus voltage value includes: judging whether the discharge success condition of the permanent magnet synchronous motor is met; when the discharge success condition is not met and the execution time of the active discharge of the permanent magnet synchronous motor does not exceed the preset time, determining the direct-axis final voltage control amount and the orthogonal-axis final voltage control amount of the permanent magnet synchronous motor according to the motor speed and the bus voltage value; controlling the active discharge of the permanent magnet synchronous motor according to the direct-axis final voltage control amount and the orthogonal-axis final voltage control amount; until the discharge success condition is met or the execution time of the active discharge of the permanent magnet synchronous motor exceeds the preset time, determining that the active discharge of the permanent magnet synchronous motor is completed.

[0019] In an embodiment of the present invention, determining the direct-axis final voltage control amount and the quadrature-axis final voltage control amount of a permanent magnet synchronous motor based on the motor speed and the bus voltage value includes: obtaining the safe speed of the permanent magnet synchronous motor; determining the voltage difference between the safe voltage and the maximum voltage error of the permanent magnet synchronous motor; determining the second direct-axis basic voltage control amount and the second quadrature-axis basic voltage control amount of the motor based on the current three-phase current, pole position, safe speed and voltage difference of the motor winding; determining the amplitude of the direct-axis high-frequency voltage control amount under the motor speed and bus voltage value based on the safe speed, voltage difference and the second direct-axis basic voltage control amount and the second quadrature-axis basic voltage control amount; determining the direct-axis final voltage control amount based on the amplitude of the direct-axis high-frequency voltage control amount and the second direct-axis basic voltage control amount; and determining the quadrature-axis final voltage control amount based on the second quadrature-axis basic voltage control amount.

[0020] In an embodiment of the present invention, determining the amplitude of the direct-axis high-frequency voltage control amount under the motor speed and bus voltage value based on the safe speed, the voltage difference, the second direct-axis basic voltage control amount and the second orthogonal-axis basic voltage control amount includes: when the motor speed is less than the safe speed and the bus voltage value is greater than or equal to the voltage difference, obtaining the historical value of the bus voltage of the motor drive system in the previous beat; determining the maximum allowable discharge current of the permanent magnet synchronous motor under the bus voltage value; determining the given value of the direct-axis high-frequency current amplitude of the motor stator according to the historical value of the bus voltage, the voltage difference, the second direct-axis basic voltage control amount, the second orthogonal-axis basic voltage control amount, a preset direct-axis high-frequency current reference value and the maximum allowable discharge current; determining the amplitude of the second direct-axis high-frequency current of the motor stator according to the historical direct-axis current and the historical orthogonal-axis current of the motor stator in the previous beat, the current three-phase current of the motor winding and the pole position; determining the amplitude of the direct-axis high-frequency voltage control amount under the motor speed and bus voltage value according to the given value of the direct-axis high-frequency current amplitude and the second direct-axis high-frequency current amplitude.

[0021] In an embodiment of the present invention, determining the amplitude of the direct-axis high-frequency voltage control quantity of the motor stator at the motor speed and bus voltage value based on the safe speed and voltage difference includes: when the motor speed is greater than or equal to the safe speed, determining the bus voltage set value based on the bus voltage value; determining the second direct-axis average current set value of the motor stator at the motor speed and bus voltage value based on the bus voltage value and the bus voltage set value; determining the second orthogonal-axis average current set value of the motor stator at the motor speed and bus voltage value; determining the amplitude of the direct-axis high-frequency voltage control quantity of the motor stator at the motor speed and bus voltage value based on the second direct-axis average current set value and the second orthogonal-axis average current set value at the motor speed and bus voltage value.

[0022] In an embodiment of the present invention, determining the bus voltage set value based on the bus voltage value includes: when the bus voltage value is greater than the voltage difference, determining the bus voltage set value based on the bus voltage value, the maximum allowable duration of active discharge of the permanent magnet synchronous motor and the voltage difference; when the bus voltage value is less than or equal to the voltage difference, determining the bus voltage set value as the voltage difference.

[0023] A second aspect of the present invention provides an active discharge device for a motor drive system, comprising:

[0024] a memory configured to store instructions;

[0025] The processor is configured to call instructions from the memory and implement the above-mentioned active discharge method for the motor drive system when executing the instructions.

[0026] A third aspect of the present invention provides a motor drive system, comprising:

[0027] Permanent magnet synchronous motor;

[0028] The above-mentioned active discharge device for the motor drive system.

[0029] A fourth aspect of the present invention provides a machine-readable storage medium having instructions stored thereon. When the instructions are executed by a processor, the processor is configured to execute the above-mentioned active discharge method for a motor drive system.

[0030] Through the above technical solution, when the bus voltage sensor is not installed or there is a voltage sampling fault, the bus voltage value of the motor drive system can be determined based on the three-phase current, magnetic pole position and motor speed, thereby controlling the active discharge of the permanent magnet synchronous motor and ensuring the safety of the motor drive system under high voltage.

[0031] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:

[0033] Figure 1 A schematic diagram of a process flow of an active discharging method for a motor drive system according to an embodiment of the present invention is shown;

[0034] Figure 2 Schematically shows a flow chart of an active discharging method for a motor drive system according to another embodiment of the present invention;

[0035] Figure 3 A schematic diagram of a motor drive system according to an embodiment of the present invention is shown schematically;

[0036] Figure 4 The figure schematically shows the internal structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present invention and are not used to limit the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0039] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] Figure 1 The following schematically shows a flow chart of an active discharge method for a motor drive system according to an embodiment of the present invention. Figure 1 As shown, in one embodiment of the present invention, an active discharge method for a motor drive system is provided, comprising the following steps:

[0041] Step 101: Receive an active discharge instruction.

[0042] Step 102: Determine whether the motor drive system has a fault that does not allow active discharge.

[0043] The motor drive system includes a permanent magnet synchronous motor. A processor can receive an active discharge instruction and determine whether the motor drive system has a fault that disallows active discharge. Fault trigger flags corresponding to potential motor drive system faults can be defined in advance. Faults that disallow active discharge can be identified from all possible faults based on the characteristics of the motor drive system and actual needs. Faults that disallow active discharge are then assigned corresponding fault trigger flags.

[0044] When receiving an active discharge instruction and determining whether a fault that disallows active discharge exists, the processor may determine whether at least one of the predetermined fault trigger flags for the fault that disallows active discharge is set. For example, if the fault trigger flag is 1, it can be determined that the fault trigger flag is set; if the fault trigger flag is 0, it can be determined that the fault trigger flag is not set.

[0045] If at least one fault trigger flag for a fault that does not allow active discharge is set, it can be determined that a fault that does not allow active discharge exists in the motor drive system. If all fault trigger flags for faults that do not allow active discharge are not set, it can be determined that no fault that does not allow active discharge exists in the motor drive system.

[0046] In one embodiment, if a fault exists in the motor drive system that does not allow active discharge, active discharge is not performed, and the active discharge state of the motor drive system may be fed back as discharge failure.

[0047] Step 103: If there is no fault that does not allow active discharge, determine whether the motor drive system is equipped with a bus voltage sensor and whether there is a voltage sampling fault.

[0048] In the absence of a fault that disallows active discharge, the processor can determine whether the motor drive system is equipped with a bus voltage sensor and whether a voltage sampling fault exists. For example, when determining whether a voltage sampling fault exists, the processor can determine whether the sampled value of the bus voltage sensor exceeds a preset range. If the sampled value exceeds the preset threshold, it can be determined that the sampled value of the bus voltage sensor is stuck, and in this case, it can be determined that a voltage sampling fault exists in the motor drive system.

[0049] In one embodiment, if the motor drive system is equipped with a bus voltage sensor and there is no voltage sampling fault, the bus voltage value of the motor drive system can be collected by the bus voltage sensor, that is, the bus voltage value at this time is the sampling voltage of the bus voltage sensor.

[0050] Step 104: When a bus voltage sensor is not installed or a voltage sampling fault occurs, obtain the three-phase current of the motor winding, the magnetic pole position of the motor rotor, and the motor speed of the motor drive system.

[0051] Step 105: Determine a first direct-axis basic voltage control variable and a first orthogonal-axis basic voltage control variable of the motor stator according to the three-phase current, the magnetic pole position, and the motor speed.

[0052] If a bus voltage sensor is not installed or a voltage sampling fault occurs, the processor can obtain the three-phase current of the motor winding, the magnetic pole position of the motor rotor, and the motor speed of the motor drive system. The processor can determine the first direct-axis basic voltage control variable and the first orthogonal-axis basic voltage control variable of the motor stator based on the three-phase current of the motor winding, the magnetic pole position of the motor rotor, and the motor speed.

[0053] Specifically, in an embodiment of the present invention, determining a first direct-axis basic voltage control variable and a first quadrature-axis basic voltage control variable of a motor stator based on three-phase current, magnetic pole position, and motor speed includes: determining a first direct-axis two-beat average current value and a first quadrature-axis two-beat average current value of the motor stator based on the three-phase current and magnetic pole position; determining a first direct-axis average current given value and a first quadrature-axis average current given value of the motor stator based on the motor speed; adjusting the first direct-axis two-beat average current value and the first quadrature-axis two-beat average current value based on the first direct-axis average current given value, the first quadrature-axis average current given value, and the magnetic pole position; adjusting the first direct-axis two-beat average current value and the first quadrature-axis two-beat average current value to meet a convergence condition; determining a first direct-axis basic voltage control variable based on the adjusted first direct-axis two-beat average current value and the first direct-axis average current given value; and determining a first quadrature-axis basic voltage control variable based on the adjusted first quadrature-axis two-beat average current value and the first quadrature-axis average current given value.

[0054] The processor can determine the first direct-axis two-beat average current value and the first orthogonal-axis two-beat average current value of the motor stator based on the three-phase current and the magnetic pole position. Among them, the first direct-axis two-beat average current value refers to the direct-axis two-beat average current value determined when the bus voltage is estimated. The first orthogonal-axis two-beat average current value refers to the orthogonal-axis two-beat average current value determined when the bus voltage is estimated. When determining the first direct-axis two-beat average current value and the first orthogonal-axis two-beat average current value of the motor stator, the processor can determine the current direct-axis current value and the current orthogonal-axis current value of the motor stator of the permanent magnet synchronous motor in the current beat through clack transformation and park transformation based on the three-phase current and the magnetic pole position.

[0055] The processor may obtain the historical direct-axis current value and the historical orthogonal-axis current value of the motor stator in the previous beat. The processor may determine the first direct-axis two-beat average current value of the motor stator based on the current direct-axis current value and the historical direct-axis current value. Specifically, the processor may determine the average value between the current direct-axis current value and the historical direct-axis current value as the first direct-axis two-beat average current value of the motor stator. The processor may determine the first orthogonal-axis two-beat average current value of the motor stator based on the current orthogonal-axis current value and the historical orthogonal-axis current value. Specifically, the processor may determine the average value between the current orthogonal-axis current value and the historical orthogonal-axis current value as the first orthogonal-axis two-beat average current value of the motor stator.

[0056] In one embodiment, the two-beat average current value of the direct axis and the two-beat average current value of the orthogonal axis of the motor stator can be determined by the following formula (1):

[0057]

[0058] Among them, i df Refers to the average current value of the motor stator's direct axis in two beats, i qf Refers to the average current value of the two-beat orthogonal axis of the motor stator, i d Refers to the current direct axis current value of the motor stator at the current beat, i q Refers to the current orthogonal axis current value of the motor stator at the current beat, i d_last Refers to the historical direct axis current value of the motor stator in the previous beat, i q_last It refers to the historical quadrature axis current value of the motor stator in the previous beat.

[0059] The processor can determine a first direct-axis average current set value and a first quadrature-axis average current set value for the motor stator based on the motor speed. The first direct-axis average current set value and the first quadrature-axis average current set value can be determined in different ways depending on the motor speed range. The first direct-axis average current set value and the first quadrature-axis average current set value both refer to average current set values ​​used to estimate the bus voltage.

[0060] In an embodiment of the present invention, determining a first direct-axis average current given value and a first orthogonal-axis average current given value of the motor stator according to the motor speed includes: obtaining the maximum allowable absolute values ​​of the permanent magnet flux coefficient, direct-axis synchronous inductance and direct-axis demagnetization current of the permanent magnet synchronous motor when the absolute value of the motor speed is greater than or equal to a preset multiple of the safe speed of the permanent magnet synchronous motor; determining the first direct-axis average current given value according to the maximum allowable absolute values ​​of the permanent magnet flux coefficient, direct-axis synchronous inductance and direct-axis demagnetization current; and determining the first orthogonal-axis average current given value of the motor stator to be a preset value.

[0061] When the absolute value of the motor speed is greater than or equal to a preset multiple of the safe speed of the permanent magnet synchronous motor, the processor may obtain the maximum allowable absolute values ​​of the permanent magnet flux linkage coefficient, direct-axis synchronous inductance, and direct-axis demagnetization current of the permanent magnet synchronous motor. The preset multiple may be set based on actual conditions, for example, 0.5.

[0062] The processor can determine the first direct-axis average current given value based on the permanent magnet flux coefficient, the direct-axis synchronous inductance, and the maximum allowable absolute value of the direct-axis demagnetization current. Specifically, the inverse of the ratio between the permanent magnet flux coefficient and the direct-axis synchronous inductance can be determined, and the inverse of the maximum allowable absolute value of the direct-axis demagnetization current can be determined. The maximum value between the two can be selected as the first direct-axis average current given value of the motor stator in this case. The processor can determine the first orthogonal axis average current given value of the motor stator to be a preset value. The preset value can be set according to actual needs. For example, the preset value can be set to 0.

[0063] In one embodiment, when the absolute value of the motor speed is greater than or equal to a preset multiple of the safe speed of the permanent magnet synchronous motor, the first direct axis average current set value and the first orthogonal axis average current set value of the motor stator can be determined by the following formula (2):

[0064]

[0065] Among them, i df_ref It refers to the first direct axis average current given value when the absolute value of the motor speed is greater than or equal to the preset multiple of the safe speed of the permanent magnet synchronous motor, i qf_ref It refers to the first orthogonal axis average current given value when the absolute value of the motor speed is greater than or equal to the preset multiple of the safe speed of the permanent magnet synchronous motor, ψ f Refers to the permanent magnet flux coefficient of the permanent magnet synchronous motor, L d Refers to the direct-axis synchronous inductance of the permanent magnet synchronous motor, i d_abs_max It refers to the maximum allowable absolute value of the direct-axis demagnetization current of the permanent magnet synchronous motor.

[0066] In an embodiment of the present invention, determining the first direct-axis average current given value and the first orthogonal-axis average current given value of the motor stator according to the motor speed includes: when the absolute value of the motor speed is less than a preset multiple of the safe speed of the permanent magnet synchronous motor, determining that the first direct-axis average current given value and the first orthogonal-axis average current given value are both preset values.

[0067] When the absolute value of the motor speed is less than a preset multiple of the safe speed of the permanent magnet synchronous motor, the processor may determine that the first straight-axis average current set value and the first orthogonal-axis average current set value are both preset values. The preset values ​​may be set according to actual needs, for example, the preset values ​​may be set to 0.

[0068] The processor can adjust the first straight-axis average current and the first orthogonal-axis average current according to the first straight-axis average current given value, the first orthogonal-axis average current given value, and the magnetic pole position. Specifically, the processor can determine the current direct-axis voltage control amount according to the first straight-axis average current given value and the first straight-axis two-beat average current value, and can determine the current orthogonal-axis voltage control amount according to the first orthogonal-axis average current given value and the first orthogonal-axis two-beat average current value, and determine the α-axis voltage control amount and the β-axis voltage control amount in the two-phase stationary coordinate system according to the current direct-axis voltage control amount, the current orthogonal-axis voltage control amount, and the magnetic pole position of the motor rotor through inverse park transformation. The processor can generate the on-off control pulses of the three-phase switch tube according to the α-axis voltage control amount and the β-axis voltage control amount, thereby adjusting the first straight-axis two-beat average current value and the first orthogonal-axis two-beat average current value.

[0069] The processor may determine, in real time, a first difference between the first straight-axis average current and a given first straight-axis average current value, and may determine, in real time, a second difference between the first orthogonal-axis average current and the given first orthogonal-axis average current value. If both the first difference and the second difference converge to a preset allowable error range, and the duration of convergence to the preset operating error range exceeds a first preset time duration and is within a second preset time duration, it may be determined that the first straight-axis average current and the first orthogonal-axis average current are adjusted to meet a convergence condition. The second time duration is greater than the first time duration.

[0070] If the direct-axis average current and the orthogonal-axis average current are not adjusted to meet the convergence conditions, it can be determined that the bus voltage value of the motor drive system cannot be determined when the bus voltage sensor is not installed or there is a voltage sampling fault, that is, the bus voltage value estimation fails at this time. For safety reasons, it can be determined that the active discharge of the motor drive system has failed and the active discharge is ended.

[0071] When the direct-axis average current and the quadrature-axis average current are adjusted to meet the convergence condition, the processor may determine the first direct-axis basic voltage control variable based on the adjusted first direct-axis average current and the first direct-axis average current given value. The first direct-axis basic voltage control variable refers to the direct-axis basic voltage control variable when estimating the bus voltage. The processor may determine the first quadrature-axis basic voltage control variable based on the adjusted first quadrature-axis average current and the first quadrature-axis average current given value. The first quadrature-axis basic voltage control variable refers to the quadrature-axis basic voltage control variable when estimating the bus voltage.

[0072] Step 106: Determine the bus voltage value of the motor drive system according to the first straight-axis basic voltage control variable and the first orthogonal-axis basic voltage control variable.

[0073] Specifically, in an embodiment of the present invention, determining the bus voltage value of the motor drive system based on the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity includes: determining a voltage judgment value based on the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity; when the voltage judgment value is greater than or equal to the second preset value and less than or equal to the first preset value, determining the direct-axis output voltage and the orthogonal-axis output voltage of the motor stator; determining the bus voltage value based on the direct-axis output voltage, the orthogonal-axis output voltage, the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity.

[0074] The processor may determine a voltage determination value based on the first direct-axis basic voltage control amount and the orthogonal-axis basic voltage control amount. Specifically, the processor may determine the sum of the squares of the direct-axis basic voltage control amount and the square of the orthogonal-axis basic voltage control amount, and perform square root of the sum to obtain the voltage determination value.

[0075] The processor may determine a bus voltage value of the motor drive system based on the voltage determination value. If the voltage determination value is greater than a first preset value, it may be determined that the bus voltage value cannot be estimated, and the active discharge of the motor drive system has failed. If the voltage determination value is not greater than the first preset value, the bus voltage value of the motor drive system may be estimated.

[0076] When the voltage determination value is greater than or equal to the second preset value and less than or equal to the first preset value, the processor may determine the direct-axis output voltage and the quadrature-axis output voltage of the motor stator. The first preset value and the second preset value may be set according to actual conditions. For example, the first preset value may be set to 1, and the second preset value may be set to 0.5.

[0077] In one embodiment, the processor may determine the direct-axis output voltage of the motor stator based on the resistance value of the motor stator, the current direct-axis current corresponding to the adjusted direct-axis average current, the current quadrature-axis current corresponding to the adjusted quadrature-axis average current, the angular velocity of the permanent magnet synchronous motor, and the quadrature-axis synchronous inductance. The processor may determine the quadrature-axis output voltage of the motor stator based on the resistance value, the current direct-axis current, the current quadrature-axis current, the angular velocity, the direct-axis synchronous inductance of the permanent magnet synchronous motor, and the permanent magnet flux linkage coefficient.

[0078] Specifically, the direct axis output voltage and the quadrature axis output voltage of the motor stator can be determined according to the following formula (3):

[0079] u d_out =R s i d -ω r L q i q

[0080] u q_out =R si q +ω r (L d i d +ψ f ) Formula (3)

[0081] Among them, u d_out Refers to the direct axis output voltage of the motor stator, u q_out Refers to the orthogonal axis output voltage of the motor stator, R s Refers to the resistance value of the motor stator, i d Refers to the current direct axis current of the motor stator at the current beat, i q Refers to the current quadrature axis current of the motor stator at the current beat, ω r Refers to the angular velocity of the permanent magnet synchronous motor, L q Refers to the orthogonal axis synchronous inductance of the motor stator, L d It refers to the direct-axis synchronous inductance of the permanent magnet synchronous motor, and ψf refers to the permanent magnet flux linkage coefficient of the permanent magnet synchronous motor.

[0082] In one embodiment, when calibrating the permanent magnet synchronous motor, the reference angular velocity ω can be recorded. r_base All dq axis current combinations below, and the d axis output voltage component u corresponding to each dq axis current combination out_q and the q-axis output voltage component u out_q , so according to the speed ω r_base The relationship between each dq axis current combination and the d and q axis output voltage components is mapped to a two-dimensional table. When determining the direct axis output voltage and the orthogonal axis output voltage of the motor stator, the two-dimensional table can be searched based on the converged direct axis two-beat average current value and the converged orthogonal axis two-beat average current value, and interpolated, and then multiplied by the speed ratio ω. r / ω r_base The direct-axis output voltage and the orthogonal-axis output voltage of the motor stator are obtained.

[0083] The processor may determine a bus voltage value based on the direct-axis output voltage, the quadrature-axis output voltage, the first direct-axis basic voltage control variable, and the first quadrature-axis basic voltage control variable. Specifically, if the absolute value of the first quadrature-axis basic voltage control variable is greater than the absolute value of the first direct-axis basic voltage control variable, the bus voltage value may be determined based on the quadrature-axis output voltage and the first quadrature-axis basic voltage control variable. If the absolute value of the first quadrature-axis basic voltage control variable is less than or equal to the absolute value of the first direct-axis basic voltage control variable, the bus voltage value may be determined based on the direct-axis output voltage and the first direct-axis basic voltage control variable.

[0084] Specifically, the bus voltage value can be determined according to the following formula:

[0085]

[0086] Among them, u dc_est Refers to the bus voltage value, u q_out Refers to the orthogonal axis output voltage, u d_out Refers to the direct axis output voltage, u qf0 Refers to the first orthogonal axis basic voltage control quantity, u df0 Refers to the first straight axis basic voltage control quantity.

[0087] In an embodiment of the present invention, determining the bus voltage value of the motor drive system according to the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity includes: determining a voltage judgment value according to the first straight-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity; when the voltage judgment value is less than a second preset value, determining the direct-axis high-frequency current component and the orthogonal-axis high-frequency current component of the motor stator according to the direct-axis current corresponding to the adjusted first direct-axis two-beat average current value, the orthogonal-axis current corresponding to the adjusted first orthogonal-axis two-beat average current value, the historical direct-axis current of the motor stator in the previous beat, and the historical orthogonal-axis current. current component; determine the first direct-axis high-frequency current amplitude of the motor stator according to the direct-axis high-frequency current component, the orthogonal-axis high-frequency current component and the direct-axis high-frequency voltage reference control quantity corresponding to the basic voltage amplitude; when the first direct-axis high-frequency current amplitude is less than the preset direct-axis high-frequency current reference value, determine the bus voltage value according to the safe voltage and maximum voltage error of the permanent magnet synchronous motor; when the direct-axis high-frequency current amplitude is greater than or equal to the direct-axis high-frequency current reference value, determine the bus voltage value according to the current sampling period of the permanent magnet synchronous motor, the direct-axis high-frequency inductance, the first direct-axis high-frequency current amplitude and the basic voltage amplitude.

[0088] When the voltage judgment value is less than the second preset value, the processor can determine the direct-axis high-frequency current component and the quadrature-axis high-frequency current component of the motor stator based on the direct-axis current corresponding to the adjusted first direct-axis two-beat average current value, the quadrature-axis current corresponding to the adjusted first quadrature-axis average current, and the historical direct-axis current and historical quadrature-axis current of the motor stator in the previous beat.

[0089] Specifically, the processor may determine the direct-axis high-frequency current component and the orthogonal-axis high-frequency current component of the motor stator according to the following formula (4):

[0090]

[0091] Among them, i d Refers to the direct-axis high-frequency current component of the motor stator, i d Refers to the current direct axis current of the motor stator at the current beat, i d_last Refers to the historical direct axis current of the motor stator in the previous beat, i q Refers to the high-frequency current component of the orthogonal axis of the motor stator, i qRefers to the current quadrature axis current of the motor stator at the current beat, i q_last It refers to the historical quadrature axis current of the motor stator in the previous beat.

[0092] When the voltage judgment value is less than the second preset value, the processor can add a positive and negative symmetrical periodic high-frequency square wave control amount u to the direct axis voltage control amount. d , whose amplitude is u d_amp , its frequency f is set to the switching frequency f sw Among them, u d_amp The range is 0 to 1, and its basic value can be set to 0.5. The switching frequency can be set to 20kHz and above, which can achieve low-speed discharge without electromagnetic noise.

[0093] The processor can determine the first direct-axis high-frequency current amplitude of the motor stator based on the direct-axis high-frequency current component, the orthogonal-axis high-frequency current component, and the direct-axis high-frequency voltage reference control variable corresponding to the basic voltage amplitude. The basic voltage amplitude can be set to 0.5, and the corresponding direct-axis high-frequency voltage reference control variable can be determined based on the basic voltage amplitude. The first direct-axis high-frequency current amplitude refers to the direct-axis high-frequency current amplitude when estimating the bus voltage. The sign of the direct-axis high-frequency voltage reference control variable is initially positive, and its sign is reversed in each subsequent control cycle.

[0094] When determining the amplitude of the first direct-axis high-frequency current of the motor stator, if the direct-axis high-frequency voltage reference control variable is less than zero, that is, the direct-axis high-frequency voltage reference control variable is a negative value, then the amplitude of the first direct-axis high-frequency current can be determined to be the direct-axis high-frequency current component of the motor stator. If the direct-axis high-frequency voltage reference control variable is greater than zero, that is, the direct-axis high-frequency voltage reference control variable is a positive value, then the amplitude of the first direct-axis high-frequency current can be determined to be the inverse of the direct-axis high-frequency current component of the motor stator.

[0095] Specifically, the amplitude of the direct-axis high-frequency current of the motor stator can be determined by the following formula (5):

[0096]

[0097] Among them, i d_amp Refers to the direct axis high frequency current amplitude of the motor stator, i d Refers to the direct-axis high-frequency current component of the motor stator, u d Refers to the direct-axis high-frequency voltage reference control quantity.

[0098] The preset direct-axis high-frequency current reference value is based on the direct-axis high-frequency current corresponding to the bus voltage being the difference between the safe voltage and the maximum voltage error and the basic voltage amplitude being 0.5. If the direct-axis high-frequency current amplitude is less than the preset direct-axis high-frequency current reference value, it indicates that the bus voltage is less than the difference between the safe voltage and the maximum voltage error. The processor may determine the bus voltage value as the difference between the difference between the safe voltage and the maximum voltage error and a preset value, wherein the preset value may be set to 0.1.

[0099] When the direct-axis high-frequency current amplitude is greater than or equal to the direct-axis high-frequency current reference value, it can be said that the bus voltage is greater than or equal to the difference between the safe voltage and the maximum voltage error. The processor can determine the bus voltage value based on the current sampling period of the permanent magnet synchronous motor, the direct-axis high-frequency inductance, the first direct-axis high-frequency current amplitude, and the basic voltage amplitude. Specifically, the bus voltage value in this case can be determined by the following formula (6):

[0100]

[0101] Among them, u dc_est Refers to the bus voltage value, i d_amp Refers to the amplitude of the first direct-axis high-frequency current of the motor stator, L d Refers to the direct-axis high-frequency inductance of the permanent magnet synchronous motor, T samp Refers to the current sampling period of the permanent magnet synchronous motor, u d_amp Refers to the basic voltage amplitude.

[0102] Step 107: Control the permanent magnet synchronous motor to actively discharge according to the motor speed and the bus voltage value.

[0103] The processor can control the active discharge of the permanent magnet synchronous motor based on the motor speed and bus voltage. Specifically, the processor can determine the speed range of the motor speed and the voltage range of the bus voltage, and control the active discharge of the permanent magnet synchronous motor based on the speed range and voltage range. If the speed range or voltage range is not within the predefined range, the permanent magnet synchronous motor can be controlled to actively discharge until the active discharge of the permanent magnet synchronous motor stops.

[0104] In an embodiment of the present invention, controlling the active discharge of the permanent magnet synchronous motor according to the motor speed and the bus voltage value includes: judging whether the discharge success condition of the permanent magnet synchronous motor is met; if the discharge success condition is not met, determining the direct-axis final voltage control amount and the orthogonal-axis final voltage control amount of the permanent magnet synchronous motor according to the motor speed and the bus voltage value; controlling the active discharge of the permanent magnet synchronous motor according to the direct-axis final voltage control amount and the orthogonal-axis final voltage control amount; until the discharge success condition is met and the execution time of the active discharge of the permanent magnet synchronous motor does not exceed the preset time, determining that the active discharge of the permanent magnet synchronous motor is completed.

[0105] The processor may determine whether a successful discharge condition for the permanent magnet synchronous motor is satisfied. Specifically, the successful discharge condition for the permanent magnet synchronous motor is determined to be satisfied when all of the following conditions are satisfied: the absolute value of the motor speed is less than a safe speed for the permanent magnet synchronous motor; and the bus voltage value is less than a difference between the safe voltage and the maximum voltage error.

[0106] If the discharge success conditions are not met, the processor may determine whether the active discharge execution duration of the permanent magnet synchronous motor exceeds a preset duration. If the discharge success conditions are not met and the execution duration does not exceed the preset duration, the processor may determine the final voltage control value of the direct axis and the final voltage control value of the quadrature axis of the permanent magnet synchronous motor based on the motor speed and bus voltage value. At this time, the permanent magnet synchronous motor's discharge status may be returned to discharging.

[0107] In an embodiment of the present invention, determining the direct-axis final voltage control amount and the quadrature-axis final voltage control amount of a permanent magnet synchronous motor according to the motor speed and the bus voltage value includes: obtaining the safe speed of the permanent magnet synchronous motor; determining the voltage difference between the safe voltage and the maximum voltage error of the permanent magnet synchronous motor; determining the second direct-axis basic voltage control amount and the second quadrature-axis basic voltage control amount of the motor according to the current three-phase current, pole position, safe speed and voltage difference of the motor winding; determining the amplitude of the direct-axis high-frequency voltage control amount under the motor speed and bus voltage value according to the safe speed, voltage difference and the second direct-axis basic voltage control amount and the second quadrature-axis basic voltage control amount; determining the direct-axis final voltage control amount according to the amplitude of the direct-axis high-frequency voltage control amount and the second direct-axis basic voltage control amount; and determining the quadrature-axis final voltage control amount according to the second quadrature-axis basic voltage control amount.

[0108] The processor can obtain the safe speed of the permanent magnet synchronous motor and determine the voltage difference between the safe voltage of the permanent magnet synchronous motor and the maximum voltage error. The processor can determine the second direct-axis basic voltage control variable and the second quadrature-axis basic voltage control variable of the motor based on the current three-phase current and magnetic pole position of the motor winding. The second direct-axis basic voltage control variable and the second quadrature-axis basic voltage control variable are recalculated after estimating the bus voltage value.

[0109] Specifically, the second direct-axis two-beat average current value and the second quadrature-axis two-beat average current value of the motor stator can be determined based on the current three-phase current and magnetic pole position of the motor winding. When the motor speed is less than the safe speed and the bus voltage is greater than or equal to the voltage difference, the corresponding second direct-axis average current set value and the second quadrature-axis average current set value are both 0. In this case, the second direct-axis basic voltage control variable can be determined based on the second direct-axis two-beat average current value and the second direct-axis average current set value.

[0110] When the motor speed is greater than or equal to the safe speed, the second direct-axis average current given value can be determined according to the bus voltage value and the bus voltage given value, and the second orthogonal-axis average current given value can be determined according to the following formula (10), and then the second direct-axis basic voltage control quantity can be determined according to the second direct-axis two-beat average current value and the second direct-axis average current given value.

[0111] The processor can determine the amplitude of the direct-axis high-frequency voltage control amount of the motor stator under the motor speed and bus voltage value according to the safe speed, voltage difference, second direct-axis basic voltage control amount and second orthogonal-axis basic voltage control amount.

[0112] In an embodiment of the present invention, determining the amplitude of the direct-axis high-frequency voltage control amount under the motor speed and bus voltage value based on the safe speed, the voltage difference, the second direct-axis basic voltage control amount and the second orthogonal-axis basic voltage control amount includes: when the motor speed is less than the safe speed and the bus voltage value is greater than or equal to the voltage difference, obtaining the historical value of the bus voltage of the motor drive system in the previous beat; determining the maximum allowable discharge current of the permanent magnet synchronous motor under the bus voltage value; determining the given value of the direct-axis high-frequency current amplitude of the motor stator according to the historical value of the bus voltage, the voltage difference, the second direct-axis basic voltage control amount, the second orthogonal-axis basic voltage control amount, a preset direct-axis high-frequency current reference value and the maximum allowable discharge current; determining the amplitude of the direct-axis high-frequency current of the second motor stator according to the historical direct-axis current and historical orthogonal-axis current of the motor stator in the previous beat, the current three-phase current of the motor winding and the pole position; and determining the amplitude of the direct-axis high-frequency voltage control amount of the motor stator under the motor speed and bus voltage value according to the given value of the direct-axis high-frequency current amplitude and the second direct-axis high-frequency current amplitude.

[0113] When the motor speed is less than the safe speed and the bus voltage value is greater than or equal to the voltage difference, the processor can obtain the bus voltage history value of the motor drive system in the previous cycle. The processor can determine the maximum allowable discharge current of the permanent magnet synchronous motor under the bus voltage value. The maximum allowable discharge current can be obtained by calibrating the fastest discharge time for the bus voltage to drop from the highest voltage to below the safe voltage, or it can be determined according to the following formula (7):

[0114]

[0115] Among them, i d_Max Refers to the maximum allowable discharge current of the permanent magnet synchronous motor under the bus voltage value, u dc_normal Refers to the bus voltage rating, u safe Refers to the safety voltage of permanent magnet synchronous motor, u err_Max Refers to the maximum voltage error of the permanent magnet synchronous motor, i d_base Refers to the preset direct-axis high-frequency current reference value.

[0116] The processor can determine the given value of the direct-axis high-frequency current amplitude of the motor stator based on the bus voltage history value, the voltage difference, the second direct-axis basic voltage control value, the second orthogonal-axis basic voltage control value, the preset direct-axis high-frequency current reference value, and the maximum allowable discharge current. Specifically, it can be determined according to the following formula (8):

[0117]

[0118] Among them, i d_amp_ref Refers to the given value of the direct-axis high-frequency current amplitude of the motor stator, u dc_last It refers to the historical value of the bus voltage of the motor drive system in the previous beat, u qf Refers to the second orthogonal axis basic voltage control quantity, u df Refers to the second direct axis basic voltage control quantity, u safe Refers to the safety voltage of permanent magnet synchronous motor, u err_Max Refers to the maximum voltage error of the permanent magnet synchronous motor, i d_base Refers to the preset direct-axis high-frequency current reference value, i d_Max It refers to the maximum allowable discharge current of the permanent magnet synchronous motor at the bus voltage value.

[0119] The processor may determine the amplitude of the second direct-axis high-frequency current of the motor stator based on the historical direct-axis current and the historical quadrature-axis current of the motor stator in the previous beat, the current three-phase current of the motor winding, and the magnetic pole position. Specifically, the processor may determine the amplitude of the second direct-axis high-frequency current of the motor stator based on the current three-phase current of the motor winding and according to the above formula (5). The processor may determine the amplitude of the direct-axis high-frequency voltage control amount of the motor stator under the motor speed and bus voltage value based on the given direct-axis high-frequency current amplitude and the second direct-axis high-frequency current amplitude.

[0120] In an embodiment of the present invention, determining the amplitude of the direct-axis high-frequency voltage control quantity of the motor stator at the motor speed and bus voltage value based on the safe speed and voltage difference includes: when the motor speed is greater than or equal to the safe speed, determining the bus voltage set value based on the bus voltage value; determining the second direct-axis average current set value of the motor stator at the motor speed and bus voltage value based on the bus voltage value and the bus voltage set value; determining the second orthogonal-axis average current set value of the motor stator at the motor speed and bus voltage value; determining the amplitude of the direct-axis high-frequency voltage control quantity of the motor stator at the motor speed and bus voltage value based on the second direct-axis average current set value and the second orthogonal-axis average current set value at the motor speed and bus voltage value.

[0121] When the motor speed is greater than or equal to the safe speed, the processor may determine a bus voltage set value based on the bus voltage value. Specifically, in an embodiment of the present invention, determining the bus voltage set value based on the bus voltage value includes: when the bus voltage value is greater than the voltage difference value, determining the bus voltage set value based on the bus voltage value, the maximum allowable active discharge time of the permanent magnet synchronous motor, and the voltage difference value; when the bus voltage value is less than or equal to the voltage difference value, determining the bus voltage set value as the voltage difference value.

[0122] When the bus voltage value is greater than the voltage difference, in order to reduce the speed as quickly as possible and reduce the bus voltage to below the safe voltage within a specified time, the processor may determine a bus voltage set value based on the bus voltage value, the maximum allowable active discharge time of the permanent magnet synchronous motor, and the voltage difference. Specifically, the processor may determine the difference between the bus voltage value and the voltage difference, determine the ratio between the difference and the maximum allowable active discharge time of the permanent magnet synchronous motor, and determine the difference between the bus voltage value and the ratio as the bus voltage set value in this case.

[0123] Specifically, when the motor speed is greater than or equal to the safe speed and the bus voltage value is greater than the voltage difference, the bus voltage set value is determined by the following formula (9):

[0124]

[0125] Among them, u dc_ref Refers to the bus voltage given value, u dc_init Refers to the bus voltage value, specifically the bus voltage when the bus voltage value is greater than the voltage difference value, u safe Refers to the safety voltage of permanent magnet synchronous motor, u err_Max Refers to the maximum voltage error of the permanent magnet synchronous motor, T dsg_max It refers to the maximum allowable duration of active discharge of permanent magnet synchronous motor.

[0126] When the bus voltage value is less than or equal to the voltage difference, the processor may determine the bus voltage set value to be the voltage difference, that is, the difference between the safe voltage of the permanent magnet synchronous motor and the maximum voltage error.

[0127] When the motor speed is greater than or equal to the safe speed, the processor can determine the reference command i of the given value of the direct-axis current basic component according to the bus voltage value and the bus voltage given value. df_cmd and the reference command i of the given value of the direct-axis current fundamental component df_cmd Set to the second direct-axis average current given value of the motor stator at the motor speed and bus voltage value.

[0128] The processor can determine a second orthogonal axis average current given value of the motor stator under the motor speed and bus voltage value. Specifically, when the motor speed is greater than or equal to the safe speed, the second orthogonal axis average current given value is determined by the following formula (10):

[0129]

[0130] Among them, i qf_ref Refers to the second orthogonal axis average current given value, i s_max Refers to the maximum allowable discharge current preset by the motor drive system, i df_ref Refers to the second direct axis average current given value, i q_Lmt Refers to the current maximum allowable orthogonal axis current amplitude, u qf_last Refers to the orthogonal axis voltage control amount of the previous beat, u dc_last Refers to the bus voltage history value of the motor drive system in the previous beat, T samp Refers to the current sampling period, which is the same as the control period.

[0131] The processor may determine the amplitude of the direct-axis high-frequency voltage control variable of the motor stator at the motor speed and bus voltage value based on the second direct-axis average current given value and the second orthogonal-axis average current given value at the motor speed and bus voltage value. Specifically, the processor may control the second direct-axis two-beat average current value and the second orthogonal-axis two-beat average current value to follow the second direct-axis average current given value and the second orthogonal-axis average current given value at the motor speed and bus voltage value, respectively, to obtain the second direct-axis basic voltage control variable and the second orthogonal-axis basic voltage control variable.

[0132] When the motor speed is greater than or equal to the safe speed, the amplitude of the direct-axis high-frequency voltage control value of the motor stator can be determined according to the following formula (11):

[0133]

[0134] Among them, u d_amp Refers to the amplitude of the direct-axis high-frequency voltage control quantity, u df Refers to the second direct axis basic voltage control quantity, u qf Refers to the second orthogonal axis basic voltage control quantity.

[0135] The processor may determine a final direct-axis voltage control value based on the amplitude of the direct-axis high-frequency voltage control value and the second direct-axis basic voltage control value. Specifically, the direct-axis high-frequency voltage control value may be determined based on the amplitude of the direct-axis high-frequency voltage control value, and the sum of the direct-axis high-frequency voltage control value and the second direct-axis basic voltage control value may be determined as the final direct-axis voltage control value. The processor may also determine a final orthogonal-axis voltage control value based on the second orthogonal-axis basic voltage control value, where the second orthogonal-axis final voltage control value is the orthogonal-axis basic voltage control value.

[0136] The processor can control the active discharge of the permanent magnet synchronous motor based on the final direct-axis voltage control value and the final quadrature-axis voltage control value. Specifically, the final direct-axis voltage control value and the final quadrature-axis voltage control value can be transformed through an inverse Park transform to generate on / off control pulses for the three-phase switching transistors to control the active discharge of the permanent magnet synchronous motor.

[0137] When the discharge success condition is met, the active discharge can be stopped and the active discharge of the permanent magnet synchronous motor is completed. At this time, the discharge state of the permanent magnet synchronous motor can be returned to successful.

[0138] If the active discharge of the permanent magnet synchronous motor exceeds a preset duration, the active discharge can be stopped, completing the active discharge. At this point, the permanent magnet synchronous motor's discharge status can be returned to failure. The preset duration can be set based on actual needs. For example, the preset duration can be set to 2 seconds.

[0139] like Figure 2 As shown, a flow chart of another active discharge method for a motor drive system is provided.

[0140] After receiving an active discharge command requesting discharge initiation, the system can determine whether a fault exists that disallows active discharge. If so, the system returns the discharge status to failure and stops active discharge. If not, the system can determine whether a bus voltage sensor is installed and whether there is a voltage sampling fault.

[0141] If a bus voltage sensor is installed and there is no voltage sampling fault, the bus voltage sampling value can be obtained, that is, the bus voltage collected by the bus voltage sensor. If a bus voltage sensor is not installed or there is a voltage sampling fault, the bus voltage value can be obtained by estimating the bus voltage.

[0142] If the bus voltage is less than the difference between the safe voltage and the maximum voltage error, and the motor speed is less than the safe speed, the system returns to the discharge state successfully and stops active discharge. If the bus voltage is greater than or equal to the difference between the safe voltage and the maximum voltage error, or the motor speed is greater than or equal to the safe speed, the system determines whether the discharge execution time exceeds the maximum allowable time.

[0143] If the discharge execution time exceeds the maximum allowable time, the discharge status returns to failure and active discharge can be stopped. If the discharge execution time does not exceed the maximum allowable time, the discharge status returns to discharging and the control strategy can be selected based on the speed and bus voltage to perform active discharge.

[0144] In one embodiment, the basic voltage control variable can be determined as follows: the direct-axis two-beat average current set value and the direct-axis two-beat average current feedback value are respectively used as inputs of a first proportional-integral controller, the difference between them is calculated and recorded as a first difference, a first proportional component value and a first integral component value are calculated based on the first difference, and the sum of the first proportional component value and the first integral component value is used as the direct-axis basic voltage control variable for the current control cycle. The first proportional component value is equal to the first difference multiplied by a preset proportional coefficient, and the first integral component value is equal to the sum of the first difference multiplied by the preset integral coefficient and the first integral component value of the previous control cycle. The initial value of the first integral component value is 0. Specifically, the quadrature-axis two-beat average current set value and the quadrature-axis two-beat average current feedback value are respectively used as inputs of a second proportional-integral controller, the difference between them is calculated and recorded as a second difference, a second proportional component value and a second integral component value are calculated based on the difference, and the sum of the second proportional component value and the second integral component value is used as the direct-axis basic voltage control variable for the current control cycle. The second proportional sub-item value is equal to the second difference multiplied by a preset proportional coefficient, and the second integral sub-item value is equal to the sum of the second difference multiplied by a preset integral coefficient and the second integral sub-item value of the previous control cycle. The initial value of the second integral sub-item value is 0.

[0145] Through the above technical solution, when the bus voltage sensor is not installed or there is a voltage sampling fault, the bus voltage value of the motor drive system can be determined based on the three-phase current, magnetic pole position and motor speed, thereby controlling the active discharge of the permanent magnet synchronous motor and ensuring the safety of the motor drive system under high voltage.

[0146] Figure 1 and 2 FIG. 1 is a flow chart of an active discharge method for a motor drive system in one embodiment. It should be understood that although Figure 1 and 2 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. In addition, Figure 1 and 2 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily performed at the same time, but can be performed at different times. The order of execution of these sub-steps or stages is not necessarily one by one, but can be performed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0147] In one embodiment, a storage medium is provided, on which a program is stored. When the program is executed by a processor, the method for active discharge of the motor drive system is implemented.

[0148] In one embodiment, a processor is provided, which is used to run a program, wherein the program executes the above-mentioned method for active discharge of the motor drive system when running.

[0149] In one embodiment, an active discharge device for a motor drive system is provided, comprising:

[0150] a memory configured to store instructions;

[0151] The processor is configured to call instructions from the memory and implement the above-mentioned active discharge method for the motor drive system when executing the instructions.

[0152] In one embodiment, a motor drive system is provided, comprising:

[0153] Permanent magnet synchronous motor;

[0154] The above-mentioned active discharge is used for the motor drive system.

[0155] like Figure 3 As shown, a schematic diagram of a motor drive system is provided. The motor drive system includes a permanent magnet synchronous motor (PMSM in the figure) and a device for active discharge of the motor drive system. The device for active discharge of the motor drive system includes the high-frequency voltage amplitude calculation module, high-frequency voltage calculation module, average current control module, inverse Park transformation module, voltage modulation module, average current setting calculation module, bus voltage closed-loop control module, voltage selection module, voltage sampling and diagnosis module, voltage estimation module, voltage setting calculation module, high-frequency current amplitude closed-loop control module, high-frequency current amplitude setting calculation module, high-frequency current calculation module, Park transformation module, Clark transformation module, current collector, position and speed acquisition module, and average current calculation module.

[0156] Among them, spd refers to the motor speed of the permanent magnet synchronous motor, i u 、i v 、i w refers to the three-phase current of the motor winding of the permanent magnet synchronous motor, θ refers to the position of the motor rotor magnetic pole, i α It refers to the current of the α axis in the two-phase stationary coordinate system, i β It refers to the current of the β axis in the two-phase stationary coordinate system. The above module can be used to implement the above active discharge method for the motor drive system.

[0157] The high-frequency voltage amplitude calculation module is used to calculate the high-frequency voltage amplitude. The average current control module is used to close the loop to control the average value of the d and q axis components of the stator current. df and i qfThe inverse Park transformation module is used to control the d and q axis voltage u df 、u qf , combined with the current rotor magnetic field position θ to obtain u α_c 、u β_c ,u α_c : Voltage control quantity of α axis in two-phase stationary coordinate system, u β_c : The voltage control quantity of the β axis in the two-phase stationary coordinate system. The voltage modulation module is used to generate the on-off control pulses of the three-phase switch tube. The average current given calculation module is used to calculate the given value of the average current i according to the input information such as the current speed. df_ref and i qf_ref The voltage selection module is used to select different voltages according to different situations. The voltage sampling and diagnosis module is used to collect bus voltage. The voltage estimation module is used to estimate bus voltage. The voltage setting calculation module determines the bus voltage setting value. The high-frequency current amplitude closed-loop control module is used to control the high-frequency d-axis current amplitude i d_amp The high-frequency current amplitude given calculation module is used to determine the high-frequency current amplitude given value. The Park transformation module and the Clark transformation module are used to obtain the i according to the collected motor winding phase current and the position of the motor rotor pole. d and i q The current collector is used to collect the phase current of the motor winding. The position and speed acquisition module is used to collect the position of the motor rotor pole and the motor speed. The average current calculation module is used to calculate the average current of the direct axis and the average current of the quadrature axis.

[0158] In one embodiment, a new energy vehicle is provided, comprising the above-mentioned motor drive system.

[0159] The energy used by the new energy vehicle of this embodiment may include fuel cells, hybrid power and hydrogen energy; in addition, the new energy vehicle of this embodiment is also an intelligent connected vehicle, which may include a sensing / perception system, a communication system, etc., and collects vehicle operation data and vehicle surrounding environment information through the sensing / perception system in the vehicle, and realizes network connection with other vehicles and the cloud through the communication system, and shares the collected vehicle operation data, vehicle surrounding environment information, etc. to the cloud and other authorized vehicles to realize data sharing, remote analysis, intelligent driving and other operations.

[0160] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 4As shown. The computer device includes a processor A01, a network interface A02, a memory (not shown in the figure) and a database (not shown in the figure) connected via a system bus. Among them, the processor A01 of the computer device is used to provide computing and control capabilities. The memory of the computer device includes an internal memory A03 and a non-volatile storage medium A04. The non-volatile storage medium A04 stores an operating system B01, a computer program B02 and a database (not shown in the figure). The internal memory A03 provides an environment for the operation of the operating system B01 and the computer program B02 in the non-volatile storage medium A04. The database of the computer device is used to store data such as bus voltage values. The network interface A02 of the computer device is used to communicate with an external terminal through a network connection. When the computer program B02 is executed by the processor A01, it realizes an active discharge method for a motor drive system.

[0161] Those skilled in the art will understand that Figure 4 The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present invention and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0162] An embodiment of the present invention provides a device, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, the steps of the active discharge method for a motor drive system are implemented.

[0163] The present invention also provides a computer program product, which, when executed on a data processing device, is adapted to execute a program that initiates the following steps of an active discharge method for a motor drive system.

[0164] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0165] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0166] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0167] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0168] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0169] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0170] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0171] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0172] The above are merely embodiments of the present invention and are not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. An active discharge method for a motor drive system, characterized in that: The motor drive system includes a permanent magnet synchronous motor, and the method includes: receiving an active discharge instruction; Determining whether the motor drive system has a fault that does not allow active discharge; In the absence of a fault that does not allow active discharge, determining whether the motor drive system is equipped with a bus voltage sensor and whether there is a voltage sampling fault; In the case where a bus voltage sensor is not installed or there is a voltage sampling fault, obtaining the three-phase current of the motor winding, the magnetic pole position of the motor rotor and the motor speed of the motor drive system; Determine a first direct-axis basic voltage control variable and a first orthogonal-axis basic voltage control variable of the motor stator according to the three-phase current, the magnetic pole position, and the motor speed; determining a bus voltage value of the motor drive system according to the first direct-axis basic voltage control variable and the first orthogonal-axis basic voltage control variable; Active discharge of the permanent magnet synchronous motor is controlled according to the motor speed and the bus voltage value.

2. The active discharge method for a motor drive system according to claim 1, characterized in that: The determining of the first direct-axis basic voltage control value and the first orthogonal-axis basic voltage control value of the motor stator according to the three-phase current, the magnetic pole position, and the motor speed includes: Determine a first direct-axis two-beat average current value and a first orthogonal-axis two-beat average current value of the motor stator according to the three-phase current and the magnetic pole position; Determining a first direct-axis average current given value and a first orthogonal-axis average current given value of the motor stator according to the motor speed; Adjust the first direct-axis two-beat average current value and the first orthogonal-axis two-beat average current value according to the first direct-axis average current given value, the first orthogonal-axis average current given value, and the magnetic pole position; Adjusting the two-beat average current value of the first direct axis and the two-beat average current value of the first orthogonal axis to meet the convergence condition; determining the first direct-axis basic voltage control variable according to the adjusted first direct-axis two-beat average current value and the first direct-axis average current given value; The first orthogonal axis basic voltage control amount is determined according to the adjusted first orthogonal axis two-beat average current value and the first orthogonal axis average current given value.

3. The active discharge method for a motor drive system according to claim 2, characterized in that: Determining a first direct-axis average current given value and a first orthogonal-axis average current given value of the motor stator according to the motor speed includes: When the absolute value of the motor speed is greater than or equal to a preset multiple of the safe speed of the permanent magnet synchronous motor, obtaining maximum allowable absolute values ​​of the permanent magnet flux linkage coefficient, the direct-axis synchronous inductance, and the direct-axis demagnetization current of the permanent magnet synchronous motor; determining the first direct-axis average current given value according to the permanent magnet flux linkage coefficient, the direct-axis synchronous inductance, and a maximum allowable absolute value of the direct-axis demagnetization current; The first orthogonal axis average current given value is determined to be a preset value.

4. The active discharge method for a motor drive system according to claim 2, characterized in that: Determining a first direct-axis average current given value and a first orthogonal-axis average current given value of the motor stator according to the motor speed includes: When the absolute value of the motor speed is less than a preset multiple of the safe speed of the permanent magnet synchronous motor, it is determined that the first direct-axis average current given value and the first orthogonal-axis average current given value are both preset values.

5. The active discharge method for a motor drive system according to claim 1, characterized in that: Determining the bus voltage value of the motor drive system according to the first direct-axis basic voltage control variable and the first orthogonal-axis basic voltage control variable includes: determining a voltage determination value according to the first direct-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount; When the voltage determination value is greater than or equal to the second preset value and less than or equal to the first preset value, determining the direct-axis output voltage and the quadrature-axis output voltage of the motor stator; The bus voltage value is determined according to the direct-axis output voltage, the quadrature-axis output voltage, the first direct-axis basic voltage control variable, and the first quadrature-axis basic voltage control variable.

6. The active discharge method for a motor drive system according to claim 1, characterized in that: Determining the bus voltage value of the motor drive system according to the first direct-axis basic voltage control variable and the first orthogonal-axis basic voltage control variable includes: determining a voltage determination value according to the first direct-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount; When the voltage judgment value is less than the second preset value, determining the direct-axis high-frequency current component and the quadrature-axis high-frequency current component of the motor stator according to the direct-axis current corresponding to the adjusted first direct-axis two-beat average current value, the quadrature-axis current corresponding to the adjusted first quadrature-axis two-beat average current value, and the historical direct-axis current and historical quadrature-axis current of the motor stator in the previous beat; Determining a first direct-axis high-frequency current amplitude of the motor stator according to the direct-axis high-frequency current component, the orthogonal-axis high-frequency current component, and a direct-axis high-frequency voltage reference control variable corresponding to a basic voltage amplitude; When the amplitude of the first direct-axis high-frequency current is less than a preset direct-axis high-frequency current reference value, determining the bus voltage value according to the safety voltage and the maximum voltage error of the permanent magnet synchronous motor; When the direct-axis high-frequency current amplitude is greater than or equal to the direct-axis high-frequency current reference value, the bus voltage value is determined according to the current sampling period of the permanent magnet synchronous motor, the direct-axis high-frequency inductance, the first direct-axis high-frequency current amplitude and the basic voltage amplitude.

7. The active discharge method for a motor drive system according to claim 1, characterized in that: The controlling of the active discharge of the permanent magnet synchronous motor according to the motor speed and the bus voltage value comprises: Determining whether a discharge success condition of the permanent magnet synchronous motor is met; When the discharge success condition is not met and the execution time of the active discharge of the permanent magnet synchronous motor does not exceed the preset time, determining the direct axis final voltage control amount and the orthogonal axis final voltage control amount of the permanent magnet synchronous motor according to the motor speed and the bus voltage value; Controlling active discharge of the permanent magnet synchronous motor according to the direct axis final voltage control amount and the orthogonal axis final voltage control amount; When the discharge success condition is met or the execution time of the active discharge of the permanent magnet synchronous motor exceeds a preset time, it is determined that the active discharge of the permanent magnet synchronous motor is completed.

8. The active discharge method for a motor drive system according to claim 7, characterized in that: Determining the final direct-axis voltage control amount and the final quadrature-axis voltage control amount of the permanent magnet synchronous motor according to the motor speed and the bus voltage value includes: Obtaining a safe rotational speed of the permanent magnet synchronous motor; Determining a voltage difference between a safe voltage and a maximum voltage error of the permanent magnet synchronous motor; determining a second direct-axis basic voltage control value and a second orthogonal-axis basic voltage control value of the motor according to the current three-phase current of the motor winding, the magnetic pole position, the safe speed, and the voltage difference; Determining the amplitude of the direct-axis high-frequency voltage control amount at the motor speed and the bus voltage value according to the safe speed, the voltage difference, the second direct-axis basic voltage control amount, and the second orthogonal-axis basic voltage control amount; determining the direct-axis final voltage control amount according to the amplitude of the direct-axis high-frequency voltage control amount and the second direct-axis basic voltage control amount; The orthogonal-axis final voltage control amount is determined according to the second orthogonal-axis basic voltage control amount.

9. The active discharge method for a motor drive system according to claim 8, characterized in that: Determining the amplitude of the direct-axis high-frequency voltage control amount at the motor speed and the bus voltage value according to the safe speed, the voltage difference, the second direct-axis basic voltage control amount, and the second orthogonal-axis basic voltage control amount includes: When the motor speed is less than the safe speed and the bus voltage value is greater than or equal to the voltage difference, obtaining a bus voltage history value of the motor drive system in a previous cycle; Determining a maximum allowable discharge current of the permanent magnet synchronous motor at the bus voltage value; Determining a given value of the direct-axis high-frequency current amplitude of the motor stator according to the bus voltage history value, the voltage difference, the second direct-axis basic voltage control variable, the second orthogonal-axis basic voltage control variable, a preset direct-axis high-frequency current reference value, and the maximum allowable discharge current; determining a second direct-axis high-frequency current amplitude of the motor stator according to a historical direct-axis current and a historical quadrature-axis current of the motor stator in a previous beat, a current three-phase current of the motor winding, and the magnetic pole position; The amplitude of the direct-axis high-frequency voltage control amount under the motor speed and the bus voltage value is determined according to the direct-axis high-frequency current amplitude given value and the second direct-axis high-frequency current amplitude.

10. The active discharge method for a motor drive system according to claim 8, characterized in that: Determining the amplitude of the direct-axis high-frequency voltage control amount of the motor stator at the motor speed and the bus voltage value according to the safe speed and the voltage difference includes: When the motor speed is greater than or equal to the safe speed, determining a bus voltage set value according to the bus voltage value; Determining a second direct-axis average current given value of the motor stator at the motor speed and the bus voltage value according to the bus voltage value and the bus voltage given value; Determining a second orthogonal axis average current given value of the motor stator at the motor speed and the bus voltage value; The amplitude of the direct-axis high-frequency voltage control amount of the motor stator at the motor speed and the bus voltage value is determined according to the second direct-axis average current given value and the second orthogonal-axis average current given value at the motor speed and the bus voltage value.

11. The active discharge method for a motor drive system according to claim 10, characterized in that: Determining the bus voltage set value according to the bus voltage value includes: When the bus voltage value is greater than the voltage difference, determining the bus voltage given value according to the bus voltage value, the maximum allowable active discharge time of the permanent magnet synchronous motor, and the voltage difference; When the bus voltage value is less than or equal to the voltage difference value, the bus voltage set value is determined to be the voltage difference value.

12. An active discharge device for a motor drive system, characterized in that: The device comprises: a memory configured to store instructions; A processor is configured to call the instructions from the memory and implement the active discharge method for a motor drive system according to any one of claims 1 to 11 when executing the instructions.

13. A motor drive system, characterized in that: include: Permanent magnet synchronous motor; The active discharge device for a motor drive system according to claim 12.

14. A machine-readable storage medium having instructions stored thereon, characterized in that: When the instruction is executed by a processor, the processor is configured to execute the active discharge method for a motor drive system according to any one of claims 1 to 11.

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