Active discharging method and device for motor driving system and storage medium

Abstract

The embodiment of the invention provides an active discharging method and device for a motor driving system and a storage medium. The method comprises the steps of receiving an active discharging instruction; judging whether the motor driving system has a fault that active discharge is not allowed or not; under the condition that the fault that active discharging is not allowed does not exist, whether a bus voltage sensor is installed on the motor driving system or not and whether a voltage sampling fault exists or not are judged; under the condition that a bus voltage sensor is not installed or a voltage sampling fault exists, obtaining a three-phase current of a motor winding of the motor driving system, a magnetic pole position of a motor rotor and a motor rotating speed; determining a first straight-axis basic voltage control quantity and a first orthogonal-axis basic voltage control quantity of a motor stator according to the three-phase current, the magnetic pole position and the rotating speed of the motor; determining a bus voltage value of the motor driving system according to the first direct-axis basic voltage control quantity and the first orthogonal-axis basic voltage control quantity; and controlling the permanent magnet synchronous motor to actively discharge according to the motor speed and the bus voltage value.

Description

Technical Field

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

[0002] Engineering vehicles and automobiles are equipped with high-voltage motor systems driven by inverters, and usually large DC capacitors are set at the DC power input end as energy storage and filtering elements. When a serious collision occurs in engineering vehicles and automobiles, it is usually necessary to quickly release the energy stored in the DC capacitors, so that the voltage across the capacitors quickly drops below the safe voltage, thereby achieving emergency power-off of high-voltage components to ensure the high-voltage safety of engineering vehicles and automobiles.

[0003] At present, since there is no need to increase the cost of additional circuits, the capacitor voltage is often rapidly reduced by actively discharging the motor winding when the high voltage is turned on. However, when a serious fault occurs in an engineering vehicle or a car, it is very likely to cause a fault in the voltage sampling circuit (bus voltage sensor or voltage sampling circuit) of the motor drive system. 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 through the motor winding, making it impossible for engineering vehicles and cars to discharge the voltage of the high-voltage system 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 object, the first aspect of the present invention provides an active discharge method for a motor drive system, the motor drive system comprising 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 amount and a first orthogonal-axis basic voltage control amount 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 amount and the first orthogonal-axis basic voltage control amount;

[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 amount and the first orthogonal-axis basic voltage control amount 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 amount 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 amount 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 linkage coefficient, a direct-axis synchronous inductance and a direct-axis demagnetizing 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 linkage coefficient, the direct-axis synchronous inductance and the direct-axis demagnetizing 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 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: when the absolute value of the motor speed is less than a preset multiple of a 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 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 greater than or equal to a 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 according to 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 amount and the first orthogonal-axis basic voltage control amount includes: determining a voltage judgment value according to the first straight-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount; 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 two-beat average current value of the first direct-axis, the orthogonal-axis current corresponding to the adjusted two-beat average current value of the first orthogonal-axis, 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 a permanent magnet synchronous motor according to a motor speed and a bus voltage value includes: 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 a preset time, determining a direct-axis final voltage control amount and a quadrature-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 quadrature-axis final voltage control amount; and determining that the active discharge of the permanent magnet synchronous motor is completed until the discharge success condition is met or the execution time of the active discharge of the permanent magnet synchronous motor exceeds a preset time.

[0019] In an embodiment of the present invention, determining the final direct-axis voltage control amount and the final orthogonal-axis 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 of the permanent magnet synchronous motor and the maximum voltage error; determining the second direct-axis basic voltage control amount and the second orthogonal-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 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; determining the orthogonal-axis final voltage control amount according to the second orthogonal-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 at the motor speed and bus voltage value according to the safe speed, the voltage difference, and 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 at 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 second direct-axis high-frequency current amplitude 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 at 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 amount of the motor stator at the motor speed and 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 the bus voltage set value according to 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 according to 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 amount of the motor stator at the motor speed and bus voltage value according to 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 a bus voltage set value based on a 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, which, when executed by a processor, configure the processor 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 according to 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 specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on 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 A schematic diagram of a process flow of an active discharging method for a motor drive system according to another embodiment of the present invention is shown;

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

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

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described 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 components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication 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 used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to 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 flowchart of the active discharge method for a motor drive system according to an embodiment of the present invention is schematically shown. 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: receiving an active discharge instruction.

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

[0043] The motor drive system includes a permanent magnet synchronous motor. The processor can receive an active discharge instruction and can determine whether the motor drive system has a fault that does not allow active discharge. Among them, the corresponding fault trigger flag can be defined in advance for the possible faults of the motor drive system, and the fault that does not allow active discharge can be determined in advance from all possible faults according to the characteristics of the motor drive system and actual needs. The fault that does not allow active discharge corresponds to a fault trigger flag.

[0044] When receiving an active discharge instruction and determining whether there is a fault that does not allow active discharge, the processor may determine whether at least one of the predetermined fault trigger flags of the fault that does not allow active discharge is set. For example, when the fault trigger flag is 1, it can be determined that the fault trigger flag is set, and when 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 of a fault that does not allow active discharge is set, it can be determined that the motor drive system has a fault that does not allow active discharge. If all fault trigger flags of faults that do not allow active discharge are not set, it can be determined that the motor drive system does not have a fault that does not allow active discharge.

[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: In the absence of a fault that does not allow active discharge, determine whether a bus voltage sensor is installed in the motor drive system and whether there is a voltage sampling fault.

[0048] In the absence of a fault that does not allow active discharge, the processor can determine whether the motor drive system is equipped with a bus voltage sensor and whether there is a voltage sampling fault. For example, when determining whether there is a voltage sampling fault, it can be determined whether the sampling value of the bus voltage sensor exceeds a preset range. If the sampling value exceeds the preset threshold, it can be determined that the sampling value of the bus voltage sensor is stuck, and at this time, it can be determined that there is a voltage sampling fault 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 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.

[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] When the bus voltage sensor is not installed or there is a voltage sampling fault, the processor can obtain the three-phase current of the motor winding of the motor drive system, the magnetic pole position of the motor rotor, and the motor speed. The processor can determine the first direct axis basic voltage control amount and the first orthogonal axis basic voltage control amount of the motor stator according to 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 the first direct axis basic voltage control amount and the first orthogonal axis basic voltage control amount 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 amount 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 amount according to the adjusted first orthogonal axis two-beat average current value and the first orthogonal 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 according to 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 estimating the bus voltage. The first orthogonal-axis two-beat average current value refers to the orthogonal-axis two-beat average current value determined when estimating the bus voltage. 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 according to 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 direct axis of the motor stator in two beats, i qf Refers to the average current value of the two-beat orthogonal axis of the motor stator, i d It refers to the current direct axis current value of the motor stator at the current beat, i q It 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 orthogonal axis current value of the motor stator in the previous beat.

[0059] The processor can determine 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. The first direct axis average current given value and the first orthogonal axis average current given value of the motor stator can be determined in different ways when the motor speed is in different intervals. The first direct axis average current given value and the first orthogonal axis average current given value both refer to the average current given value when estimating 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 a motor stator according to a motor speed includes: obtaining maximum allowable absolute values ​​of a permanent magnet flux linkage coefficient, a direct-axis synchronous inductance and a direct-axis demagnetizing 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 linkage coefficient, the direct-axis synchronous inductance and the direct-axis demagnetizing 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 can obtain the maximum allowable absolute value of the permanent magnet flux linkage coefficient, the direct axis synchronous inductance, and the direct axis demagnetization current of the permanent magnet synchronous motor. The preset multiple can be set according to actual conditions, for example, the preset multiple can be set to 0.5.

[0062] The processor can determine the first direct-axis average current given value according to 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, and the maximum value between the two is selected as the first direct-axis average current given value of the motor stator in this case. The processor can determine that the first orthogonal axis average current given value of the motor stator is a preset value. Among them, 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 given value and the first orthogonal axis average current given 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 a permanent magnet synchronous motor.

[0066] 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: when the absolute value of the motor speed is less than a preset multiple of a 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 can determine that the first straight axis average current given value and the first orthogonal axis average current given value are both preset values. The preset values ​​can be set according to actual needs, for example, the preset values ​​can 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 voltage control amount of the α-axis and the voltage control amount of the β-axis 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 the inverse park transformation. The processor can generate the on-off control pulse of the three-phase switch tube according to the voltage control amount of the α-axis and the voltage control amount of the β-axis, thereby adjusting the first straight-axis two-beat average current value and the first orthogonal-axis two-beat average current value.

[0069] The processor can determine in real time a first difference between the first straight-axis average current and the first straight-axis average current given value, and can determine in real time a second difference between the first orthogonal-axis average current and the first orthogonal-axis average current given value. When 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 the first preset duration, and is within the second preset duration, it can be determined that the first straight-axis average current and the first orthogonal-axis average current are adjusted to meet the convergence condition. The second duration is greater than the first 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 orthogonal-axis average current are adjusted to meet the convergence condition, the processor can determine the first direct-axis basic voltage control amount according to the adjusted first direct-axis average current and the first direct-axis average current given value. The first direct-axis basic voltage control amount refers to the direct-axis basic voltage control amount when estimating the bus voltage. The processor can determine the first orthogonal-axis basic voltage control amount according to the adjusted first orthogonal-axis average current and the first orthogonal-axis average current given value. The first orthogonal-axis basic voltage control amount refers to the orthogonal-axis basic voltage control amount 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 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 greater than or equal to a 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 according to 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 the voltage determination value according to 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 square of the direct axis basic voltage control amount and the square of the orthogonal axis basic voltage control amount, and perform square root on the sum to obtain the voltage determination value.

[0075] The processor can determine the bus voltage value of the motor drive system according to the voltage judgment value. If the voltage judgment value is greater than the first preset value, it can be determined that the bus voltage value cannot be estimated, and it is determined that the active discharge of the motor drive system has failed. If the voltage judgment value is not greater than the first preset value, the bus voltage value of the motor drive system can 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 can determine the direct axis output voltage and the orthogonal axis output voltage of the motor stator. The first preset value and the second preset value can be set according to actual conditions. For example, the first preset value can be set to 1 and the second preset value can be set to 0.5.

[0077] In one embodiment, the processor can determine the direct-axis output voltage of the motor stator according to the resistance value of the motor stator, the current direct-axis current corresponding to the adjusted direct-axis average current, the current orthogonal-axis current corresponding to the adjusted orthogonal-axis average current, the angular velocity of the permanent magnet synchronous motor, and the orthogonal-axis synchronous inductance. The processor can determine the orthogonal-axis output voltage of the motor stator according to the resistance value, the current direct-axis current, the current orthogonal-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 orthogonal 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 It refers to the current direct axis current of the motor stator at the current beat, i q It 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 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 obtain 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 according to 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 the bus voltage value according to the direct axis output voltage, the quadrature axis output voltage, the first direct axis basic voltage control amount, and the first quadrature axis basic voltage control amount. Specifically, if the absolute value of the first quadrature axis basic voltage control amount is greater than the absolute value of the first quadrature axis basic voltage control amount, the bus voltage value may be determined according to the quadrature axis output voltage and the first quadrature axis basic voltage control amount. If the absolute value of the first quadrature axis basic voltage control amount is less than or equal to the absolute value of the first quadrature axis basic voltage control amount, the bus voltage value may be determined according to the direct axis output voltage and the first quadrature axis basic voltage control amount.

[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 basic voltage control quantity of the first orthogonal axis, 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 amount and the first orthogonal-axis basic voltage control amount includes: determining a voltage judgment value according to the first straight-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount; 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 two-beat average current value of the first direct-axis, the orthogonal-axis current corresponding to the adjusted two-beat average current value of the first orthogonal-axis, 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 orthogonal-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 orthogonal-axis current corresponding to the adjusted first orthogonal-axis average current, and the historical direct-axis current and historical orthogonal-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 It 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 qIt refers to the current orthogonal 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 , whose 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 no electromagnetic noise during low-speed discharge.

[0093] The processor can 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 amount corresponding to the basic voltage amplitude. Among them, the basic voltage amplitude can be set to 0.5, and the corresponding direct-axis high-frequency voltage reference control amount can be determined according to 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. Among them, the initial value of the positive and negative signs of the direct-axis high-frequency voltage reference control amount is positive, and its sign is reversed in each subsequent control cycle.

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

[0095] Specifically, the direct-axis high-frequency current amplitude 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 It 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 a value based on the direct-axis high-frequency current corresponding to the difference between the safe voltage and the maximum voltage error and the basic voltage amplitude of 0.5. When the direct-axis high-frequency current amplitude is less than the preset direct-axis high-frequency current reference value, it means that the bus voltage is less than the difference between the safe voltage and the maximum voltage error. The processor can determine that the bus voltage value is the difference between the difference between the safe voltage and the maximum voltage error and the preset value, wherein the preset value can 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, and the processor can 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. 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 active discharge of the permanent magnet synchronous motor according to the motor speed and the bus voltage value.

[0103] The processor can control the active discharge of the permanent magnet synchronous motor according to the motor speed and the bus voltage value. Specifically, the speed interval in which the motor speed is located and the voltage interval in which the bus voltage value is located can be determined, and the active discharge of the permanent magnet synchronous motor can be controlled according to the speed interval and the voltage interval. If the speed interval or the voltage interval is not in the predefined interval, 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 a 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, 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; and determining that the active discharge of the permanent magnet synchronous motor is completed 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.

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

[0106] If the discharge success condition is not met, the processor can determine whether the execution time of the active discharge of the permanent magnet synchronous motor exceeds the preset time. If the discharge success condition is not met and the execution time does not exceed the preset time, the processor can determine the final voltage control amount of the direct axis and the final voltage control amount of the orthogonal axis of the permanent magnet synchronous motor according to the motor speed and the bus voltage value. At this time, the discharge state of the permanent magnet synchronous motor can also be returned to discharging.

[0107] In an embodiment of the present invention, determining the final direct-axis voltage control amount and the final orthogonal-axis 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 of the permanent magnet synchronous motor and the maximum voltage error; determining the second direct-axis basic voltage control amount and the second orthogonal-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 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; and determining the orthogonal-axis final voltage control amount according to the second orthogonal-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 amount and the second orthogonal axis basic voltage control amount of the motor according to the current three-phase current and magnetic pole position of the motor winding. The second direct axis basic voltage control amount and the second orthogonal axis basic voltage control amount are recalculated after the bus voltage value is estimated.

[0109] Specifically, the second direct-axis two-beat average current value and the second orthogonal-axis two-beat average current value of the motor stator can be determined according to 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 value is greater than or equal to the voltage difference, the corresponding second direct-axis average current given value and the second orthogonal-axis average current given value are both 0. At this time, the second direct-axis basic voltage control amount can be determined according to the second direct-axis two-beat average current value and the second direct-axis average current given 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, the voltage difference, the second direct-axis basic voltage control amount and the 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 at the motor speed and 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 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 at 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 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 of the motor stator at 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 beat. 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 It refers to the maximum allowable discharge current of the permanent magnet synchronous motor under the bus voltage value, u dc_normal Refers to the rated value of bus voltage, 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 according to the bus voltage history value, the voltage difference, the second direct-axis basic voltage control amount, the second orthogonal-axis basic voltage control amount, 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 It 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 basic voltage control quantity of the second orthogonal axis, 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 under the bus voltage value.

[0119] The processor can determine the second direct-axis high-frequency current amplitude 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 magnetic pole position. Specifically, the processor can determine the second direct-axis high-frequency current amplitude of the motor stator based on the current three-phase current of the motor winding and according to the above formula (5). 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 given value of the 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 amount of the motor stator at the motor speed and 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 the bus voltage set value according to 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 according to 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 amount of the motor stator at the motor speed and bus voltage value according to 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 the bus voltage set value according to the bus voltage value. Specifically, in an embodiment of the present invention, determining the bus voltage set value according to the bus voltage value includes: when the bus voltage value is greater than the voltage difference value, determining the bus voltage set value according to the bus voltage value, the maximum allowable duration of active discharge 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] In the case where 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 the specified time, at this time, the processor can determine the bus voltage set value according to the bus voltage value, the maximum allowable duration of active discharge of the permanent magnet synchronous motor, and the voltage difference. Specifically, the processor can determine the difference between the bus voltage value and the voltage difference, and determine the ratio between the difference and the maximum allowable duration of active discharge 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 that the bus voltage set value is 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 the 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 average current given value of the second orthogonal axis, 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 It refers to the orthogonal axis voltage control amount of the previous beat, u dc_last It refers to the historical value of the bus voltage 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 can determine the amplitude of the direct-axis high-frequency voltage control amount of the motor stator at the motor speed and bus voltage value according to 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 can 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 amount and the second orthogonal-axis basic voltage control amount.

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

[0133]

[0134] Among them, u d_amp It 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 basic voltage control quantity of the second orthogonal axis.

[0135] The processor may determine 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. Specifically, the direct-axis high-frequency voltage control amount may be determined according to the amplitude of the direct-axis high-frequency voltage control amount, and the sum of the direct-axis high-frequency voltage control amount and the second direct-axis basic voltage control amount may be determined as the direct-axis final voltage control amount. The processor may determine the orthogonal-axis final voltage control amount according to the second orthogonal-axis basic voltage control amount, and the second orthogonal-axis final voltage control amount is the orthogonal-axis basic voltage control amount.

[0136] The processor can control the active discharge of the permanent magnet synchronous motor according to the final voltage control amount of the direct axis and the final voltage control amount of the orthogonal axis. Specifically, the final voltage control amount of the direct axis and the final voltage control amount of the orthogonal axis can be transformed by inverse Park to generate the on-off control pulse of the three-phase switch tube 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 also be returned to success.

[0138] When the execution time of active discharge of the permanent magnet synchronous motor exceeds the preset time, 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 also be returned to failure. Among them, the preset time can be set according to actual needs, for example, the preset time can be set to 2s.

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

[0140] After receiving the active discharge command request to start discharging, it can be determined whether there is a fault that does not allow active discharge. If there is a fault that does not allow active discharge, the discharge state is returned to failure and active discharge is stopped. If there is no fault that does not allow active discharge, it can be determined whether the bus voltage sensor is installed and there is no voltage sampling fault.

[0141] When the 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. When the bus voltage sensor is not installed or there is a voltage sampling fault, the bus voltage can be estimated to obtain the bus voltage value.

[0142] Afterwards, if the bus voltage value 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 discharge state is returned successfully and the active discharge is stopped. If the bus voltage value 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, it is determined whether the discharge execution time exceeds the maximum allowable time.

[0143] If the discharge execution time exceeds the maximum allowed time, the discharge state returns to failure and active discharge can be stopped. If the discharge execution time does not exceed the maximum allowed time, the discharge state can be returned to discharging, and the control strategy can be selected according to the speed and bus voltage to perform active discharge.

[0144] In one embodiment, the above-mentioned determination of the basic voltage control amount can be determined in the following manner: the direct-axis two-beat average current given value and the direct-axis two-beat average current feedback value are respectively used as the input of the first proportional-integral controller, the difference between them is calculated and recorded as the first difference, the first proportional sub-item value and the first integral sub-item value are calculated according to the first difference, and the sum of the first proportional sub-item value and the first integral sub-item value is used as the direct-axis basic voltage control amount of the current control cycle. The first proportional sub-item value is equal to the first difference multiplied by the preset proportional coefficient, and the first integral sub-item value is equal to the sum of the first difference multiplied by the preset integral coefficient and the first integral sub-item value of the previous control cycle. The initial value of the first integral sub-item value is 0. Specifically, the cross-axis two-beat average current given value and the cross-axis two-beat average current feedback value are respectively used as the input of the second proportional-integral controller, the difference between them is calculated and recorded as the second difference, the second proportional sub-item value and the second integral sub-item value are calculated according to the difference, and the sum of the second proportional sub-item value and the second integral sub-item value is used as the direct-axis basic voltage control amount of 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 according to 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. Moreover, 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 executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed 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, and 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, and the processor 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 in 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. Among them, the device for active discharge of the motor drive system includes a high-frequency voltage amplitude calculation module, a high-frequency voltage calculation module, an average current control module, an inverse Park transformation module, a voltage modulation module, an average current given calculation module, a bus voltage closed-loop control module, a voltage selection module, a voltage sampling and diagnosis module, a voltage estimation module, a voltage given calculation module, a high-frequency current amplitude closed-loop control module, a high-frequency current amplitude given calculation module, a high-frequency current calculation module, a Park transformation module, a Clark transformation module, a current collector, a position and speed acquisition module and an 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 previous and current beats 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, we can get u α_c 、u β_c ,u α_c : Voltage control quantity of the α axis in the 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 current speed and other input information. 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 the 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 magnetic 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 orthogonal 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 also belongs to an intelligent networked vehicle, which may include a sensor / perception system, a communication system, etc., and collects vehicle operation data and vehicle surrounding environment information through the sensor / 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, an active discharge method for a motor drive system is implemented.

[0161] Those skilled in the art will understand that Figure 4 The structure shown in the figure is only a block diagram of a part 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 those shown in the figure, or combine certain components, or have a different arrangement of components.

[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 suitable for executing a program that initiates the following steps of an active discharge method for a motor drive system.

[0164] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, 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 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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 flowchart and / or block diagram. 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 capable of directing a computer or other programmable data processing device to operate 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 A 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 operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0168] In a typical configuration, a computing device includes one or more processors (CPU), 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 include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. 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 disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape 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 temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0171] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0172] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in 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 amount and a first orthogonal-axis basic voltage control amount of the motor stator according to the three-phase current, the magnetic pole position and the motor speed; Determine the bus voltage value of the motor drive system according to the first direct-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount; The permanent magnet synchronous motor is controlled to actively discharge 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 step of determining the first direct-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount of the motor stator according to the three-phase current, the magnetic pole position and the motor speed comprises: 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; Determine 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 average current value of the first direct axis over two beats and the average current value of the first orthogonal axis over two beats to meet a convergence condition; Determine the first direct-axis basic voltage control amount 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 two-beat average current value of the first orthogonal axis 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 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 greater than or equal to a preset multiple of the safe speed of the permanent magnet synchronous motor, obtaining the maximum allowable absolute value 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 the 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 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, 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: The determining of the bus voltage value of the motor drive system according to the first direct-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount comprises: 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 orthogonal axis output voltage of the motor stator; The bus voltage value is determined according to the direct-axis output voltage, the orthogonal-axis output voltage, the first direct-axis basic voltage control amount, and the first orthogonal-axis basic voltage control amount.

6. The active discharge method for a motor drive system according to claim 1, characterized in that: The determining of the bus voltage value of the motor drive system according to the first direct-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount comprises: determining a voltage determination value according to the first direct-axis basic voltage control amount and the first orthogonal-axis basic voltage control amount; In the case where the voltage judgment value is less than the second preset value, the direct-axis high-frequency current component and the orthogonal-axis high-frequency current component of the motor stator are determined 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, and the historical direct-axis current and historical orthogonal-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 amount corresponding to a basic voltage amplitude; When the first direct-axis high-frequency current amplitude 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 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 voltage control amount of the direct axis and the final voltage control amount of the orthogonal axis of the permanent magnet synchronous motor according to the motor speed and the bus voltage value includes: Obtaining a safe rotation 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; Determine a second direct-axis basic voltage control amount and a second orthogonal-axis basic voltage control amount 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; Determine 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: The step of 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 comprises: When the motor speed is less than the safe speed and the bus voltage value is greater than or equal to the voltage difference value, obtaining a bus voltage history value of the motor drive system in the previous cycle; Determining the maximum allowable discharge current of the permanent magnet synchronous motor at the bus voltage value; Determine a given value of the direct-axis high-frequency current amplitude of the motor stator according to the bus voltage historical value, 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; Determine 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 magnetic pole position; The amplitude of the direct-axis high-frequency voltage control amount at 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: The step of 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 comprises: 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; Determine 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; Determine 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 given value according to the bus voltage value comprises: When the bus voltage value is greater than the voltage difference value, determining the bus voltage given value according to the bus voltage value, the maximum allowable duration of active discharge 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, 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.

Images