A switching control method for motor driving and energy storage power multiplexing

Abstract

The present application relates to the technical field of digital processing, in particular to a motor driving and energy storage power reuse switching control method, comprising the following steps: collecting current and voltage and generating a threshold table, selecting a bridge arm and a diode according to the relationship between three-phase current and voltage to generate a driving sequence, controlling the inverter bridge to cut off the current, disconnecting the motor contactor after confirming the safety of the bus voltage, completing the energy storage side pre-charging and main contactor switching, outputting a running signal after confirming the conduction and pre-charging current returning to zero, in the present application, the threshold is compensated by running statistics, so that the cut-off criterion fits the actual fluctuation, the bridge arm and anti-parallel diode are selected according to the direction of three-phase current, a controlled release path is established for the residual current of the winding, the current breaking, contact arc and bus overvoltage are inhibited, and the contactor and pre-charging state are confirmed by combining the coil current, contact pressure difference, branch current and battery bus voltage difference, so as to avoid the fixed delay causing loop overlap, insufficient pre-charging and main branch impact, and improve the switching safety and accuracy.

Description

Technical Field

[0001] This invention relates to the field of digital processing technology, and in particular to a switching control method for motor drive and energy storage power reuse. Background Technology

[0002] Digital processing involves the acquisition, calculation, judgment, and control of data such as motor commands, bus voltage, phase current, rotor position, energy storage battery voltage, and state of charge. Its core aspects include operating status identification, power flow direction determination, switching device conduction sequence setting, pulse width modulation signal generation, and switching condition judgment. Typically, the conduction combination, duty cycle, and contactor action sequence of switching devices are determined by comparing sampled data, preset thresholds, and operating commands. Among them, the switching control of traditional motor drive and energy storage power reuse refers to the same power conversion circuit switching power loops and control commands between motor drive and energy storage charging and discharging states. It takes into account the connection relationship of motor windings, energy storage battery, DC bus, inverter bridge switches, and contactors. The switching time is usually determined based on start / stop commands, phase current, bus voltage, and battery terminal voltage. The pulse width modulation signal is stopped in sequence, the current threshold is judged, the current contactor is disconnected, the target contactor is turned on after a delay, and the switching device drive sequence, current setpoint, and duty cycle are reset.

[0003] Existing technologies mainly rely on stopping pulse width modulation, comparing phase current with bus voltage, disconnecting the current contactor, and delaying the connection of the target contactor to complete the switching. This results in the failure to organize the follow current path after stopping the drive, the lack of active constraint on the release of residual energy in the winding, and the existence of branch current when the contactor operates. This can easily lead to contact arcing, sudden rise in bus voltage, and increased voltage stress on the devices. At the same time, the connection time of the target contactor is mainly determined by a fixed delay. The contactor coil response, contact bounce, mechanical hysteresis, and pre-charge speed are affected by temperature, aging, and load changes. The fixed waiting time cannot accurately represent the true on / off state. For example, if the energy storage side circuit is connected before the motor side contacts are completely separated, it can easily lead to circuit overlap. If the main branch is connected before the pre-charge is sufficient, it will generate a large inrush current and shorten the contactor's life. Summary of the Invention

[0004] To address the technical problems existing in the prior art, embodiments of the present invention provide a switching control method for motor drive and energy storage power reuse, comprising the following steps: S1: Collect the three-phase winding current, contactor contact voltage, power branch current, contactor coil current and DC bus voltage, calculate the zero current threshold, turn-off current reference range, contactor terminal voltage threshold, bus voltage upper limit, pre-charge current threshold range and pre-charge voltage threshold range, and generate a threshold parameter table. S2: Collect the three-phase winding current, DC bus voltage and energy storage battery terminal voltage. Based on the threshold parameter table, compare the absolute value of the three-phase current and the relationship between the two-terminal voltages. Select the six-arm inverter bridge and the corresponding anti-parallel diode according to the current direction to generate the gate drive sequence. S3: Control the six-arm inverter bridge to turn on according to the gate drive sequence, monitor the three-phase winding current and DC bus voltage, determine that the current of each phase winding is within the turn-off current reference range and the DC bus voltage does not exceed the upper limit of the bus voltage, and generate the motor side contactor disconnect enable signal. S4: Based on the motor-side contactor disconnect enable signal and threshold parameter table, disconnect the motor-side contactor coil, monitor the contactor coil current, the voltage across the contacts and the motor-side branch current, and after finding that the motor-side contactor is in the disconnected state, connect the energy storage side pre-charge contactor, monitor the pre-charge contactor coil current, the voltage across the contacts, the pre-charge branch current, the energy storage battery terminal voltage and the DC bus voltage, determine that the pre-charge contactor is in the closed state, the pre-charge branch current is within the pre-charge current threshold range and the voltage difference across the two ends is within the pre-charge voltage threshold range, and generate the energy storage side main contactor closing enable signal; S5: Based on the main contactor closing enable signal of the energy storage side, the main contactor is turned on. After confirming that the main branch is conducting, the pre-charge contactor is turned off. After determining that the pre-charge branch current is zero, an energy storage power reuse operation signal is generated.

[0005] As a further aspect of the present invention, the specific steps of S1 are as follows: S101: Collects three-phase winding current, contactor contact voltage, power branch current, contactor coil current and DC bus voltage. Numbers and arranges the five types of signals according to the same sampling time. Converts the three-phase winding current into absolute value and the contactor contact voltage into differential voltage value. Calculates the maximum, minimum, average and maximum difference between adjacent samples for each value within a continuous sampling period. Establishes a numerical sequence according to the signal name and generates operating statistics. S102: Based on the operating statistics, select the minimum absolute value of the three-phase winding current and the maximum value of the difference between adjacent samples and sum them up to calculate the zero current threshold. Set its negative and positive values ​​as the lower and upper limits of the cut-off current reference range. Select the sum of the minimum contact voltage difference and the maximum value of the difference between adjacent samples as the contactor terminal voltage threshold. Set the sum of the maximum DC bus voltage and the maximum value of the difference between adjacent samples as the upper limit of the bus voltage to obtain the disconnection parameter group. S103: Call the disconnect parameter group and running statistics, select the minimum and maximum values ​​of the power branch current, collect the energy storage battery terminal voltage and DC bus voltage, calculate the absolute value of the difference between the energy storage battery terminal voltage and the DC bus voltage at the same sampling time, and select the minimum and maximum values ​​of the absolute values ​​of the difference, calculate the two pre-charge threshold ranges, set the minimum and maximum values ​​of the power branch current as the lower limit and upper limit of the pre-charge current threshold range, and set the minimum and maximum values ​​of the absolute values ​​of the difference as the lower limit and upper limit of the pre-charge voltage threshold range, and write them into the disconnect parameter group and the two pre-charge threshold ranges by name and value to generate a threshold parameter table.

[0006] As a further aspect of the present invention, the method for determining the maximum value of the adjacent sampling difference is as follows: according to the order of sampling time, calculate the absolute value of the difference between the current sampling value and the previous sampling value in the same signal, and select the maximum value from all the absolute differences corresponding to a continuous sampling period, and use the maximum value as the fluctuation compensation amount of the corresponding monitoring signal.

[0007] As a further aspect of the present invention, the specific steps of S2 are as follows: S201: Collect the three-phase winding current, DC bus voltage and energy storage battery terminal voltage. Arrange the winding current values ​​of phase A, phase B and phase C and the two voltage values ​​at the same sampling time. Record the current flowing from the inverter bridge to the winding as 1, the reverse current as negative 1, and the zero value as 0. Take the absolute value of each phase current, subtract the energy storage battery terminal voltage from the DC bus voltage, calculate the absolute value of the three-phase current, the current direction code and the terminal voltage difference, and generate an electrical parameter array. S202: Based on the electrical parameter array and threshold parameter table, read the absolute value of the three-phase current, the current direction code, the terminal voltage difference and the zero current threshold. Compare the absolute value of each phase current with the zero current threshold. If it is not greater than the zero current threshold, record the corresponding phase state as 0. If it is greater than the zero current threshold, retain the current direction code. Then compare the terminal voltage difference with the zero value. The positive value, negative value and zero value are recorded as 1, -1 and 0 respectively. Arrange the codes according to the sampling time to obtain the current and voltage criterion codes.

[0008] As a further aspect of the present invention, based on the current-voltage criterion code, a six-bit gate bit sequence is established according to the order of the upper and lower bridge arms of phase A, phase B, and phase C, and the status code and terminal voltage relationship code of each phase are read respectively. When the phase status code is 1 or -1, select the bridge arm whose forward conduction direction of the anti-parallel diode is consistent with the direction of the corresponding winding current as the selected bridge arm, and use the other bridge arm of the same phase as the complementary bridge arm. When the terminal voltage relationship code is 1, the selected bridge arm state position is 1 and the complementary bridge arm state position is 0; when the terminal voltage relationship code is -1, the selected bridge arm state position is 0 and the complementary bridge arm state position is 1. When the terminal voltage relationship code is 0, both the selected bridge arm status bit and the complementary bridge arm status bit are set to 0. When the phase status code is 0, the upper and lower bridge arm status bits of the corresponding phase are both set to 0, and the upper and lower bridge arm status bits of the same phase are not simultaneously set to 1. The six-bit status is arranged according to the sampling time to generate the gate drive sequence.

[0009] As a further aspect of the present invention, the specific steps of S3 are as follows: S301: Control the six-arm inverter bridge to turn on according to the gate drive sequence. Read the six-bit status in the order of A-phase upper arm, A-phase lower arm, B-phase upper arm, B-phase lower arm, C-phase upper arm, and C-phase lower arm. Determine whether each status value is equal to 1. If it is equal to 1, write the turn-on level to the corresponding bridge arm gate drive terminal. If it is not equal to 1, write the turn-off level. Record the six level values ​​in the order of bridge arms. Arrange the sampling time with the six level values ​​to generate the bridge arm turn-on status quantity. S302: Based on the sampling time corresponding to the bridge arm conduction state quantity, monitor the three-phase winding current and DC bus voltage, synchronously record the A-phase winding current value, B-phase winding current value, C-phase winding current value and DC bus voltage value, calculate the absolute value of the three-phase winding current, arrange the absolute value of each phase current with the corresponding sampling time, arrange the DC bus voltage value with the corresponding sampling time, and collect them in the order of A-phase, B-phase, C-phase and DC bus to obtain the winding bus quantity value group.

[0010] As a further aspect of the present invention, based on the winding bus value group and threshold parameter table, the absolute value of each phase current, the DC bus voltage value, the cut-off current reference range, and the upper limit of the bus voltage are read. It is determined whether the absolute values ​​of the three phase currents are all within the cut-off current reference range and whether the DC bus voltage does not exceed the upper limit of the bus voltage. When all four conditions are met, the enable bit is written as 1. When any condition is not met, the enable bit is written as 0. The enable bits are arranged according to the sampling time to generate the motor-side contactor disconnect enable signal.

[0011] As a further aspect of the present invention, the specific steps of S4 are as follows: S401: Based on the motor-side contactor disconnect enable signal and threshold parameter table, disconnect the motor-side contactor coil, monitor the contactor coil current, the voltage across the contact points and the motor-side branch current, read the zero current threshold and the contactor terminal voltage threshold, determine that the absolute values ​​of the coil current and the branch current are not greater than the zero current threshold and the absolute values ​​of the voltage across the contact points are not less than the contactor terminal voltage threshold. If the condition is met, record it as 1; if it is not met, record it as 0, and generate the motor-side disconnect state value. S402: Based on the motor-side disconnected state value, read the state bit. When the state bit is 1, connect the energy storage side pre-charge contactor, monitor the pre-charge contactor coil current, contact voltage, pre-charge branch current, energy storage battery terminal voltage and DC bus voltage, calculate the absolute value of coil current, contact voltage, pre-charge branch current and the absolute value of the difference between energy storage battery terminal voltage and DC bus voltage, arrange the four values ​​according to the sampling time to obtain the loop monitoring quantity group; S403: Call the loop monitoring quantity group and threshold parameter table, determine whether the absolute value of the coil current is greater than the zero current threshold, the absolute value of the voltage across the contact is not greater than the contactor terminal voltage threshold, the absolute value of the precharge branch current is within the precharge current threshold range, and the absolute value of the battery bus voltage difference is within the precharge voltage threshold range. Write 1 if all four conditions are met, and write 0 if any one condition is not met. Arrange the written values ​​according to the sampling time to generate the energy storage side main contactor closing enable signal.

[0012] As a further aspect of the present invention, the generation of the energy storage side main contactor closing enable signal further includes: continuously counting the results of the four judgment conditions, incrementing the count value when all four judgment conditions are met at adjacent sampling times, clearing the count value when any judgment condition is not met, and setting the energy storage side main contactor closing enable signal to an active state after the count value reaches a preset number of confirmations.

[0013] As a further aspect of the present invention, the specific steps of S5 are as follows: S501: Based on the main contactor closing enable signal of the energy storage side, the main contactor is turned on, the coil current and contact voltage of the main contactor are monitored, the zero current threshold and the contactor terminal voltage threshold are called in the threshold parameter table, and it is determined that the absolute value of the coil current is greater than the zero current threshold and the absolute value of the contact voltage is not greater than the contactor terminal voltage threshold. When both conditions are met, the conduction bit is recorded as 1. When either condition is not met, the conduction bit is recorded as 0. The conduction bits are arranged according to the sampling time to generate the main branch conduction status value. S502: Based on the main branch conduction status value, read the status bit. When the status bit is 1, disconnect the precharge contactor coil. Monitor the precharge contactor coil current, contact voltage and precharge branch current. Record the three values ​​at the same sampling time. Calculate the absolute value of coil current, absolute value of contact voltage and absolute value of precharge branch current. Arrange the three absolute values ​​with the corresponding sampling time to obtain the precharge disconnection value group. S503: Call the precharge disconnection value group and threshold parameter table, read the absolute value of coil current, absolute value of contact voltage, absolute value of precharge branch current, zero current threshold and contactor terminal voltage threshold, determine whether the absolute value of coil current is not greater than the zero current threshold, the absolute value of contact voltage is not less than the contactor terminal voltage threshold and the absolute value of precharge branch current is not greater than the zero current threshold. If all three conditions are met, write the operation bit as 1, otherwise write it as 0, and generate the energy storage power reuse operation signal.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In this invention, the three-phase winding current, contact voltage difference, branch current, coil current, and bus voltage are arranged correspondingly at the same sampling time. The maximum, minimum, average, and maximum difference between adjacent samples are extracted. The zero current threshold, turn-off current range, contactor terminal voltage threshold, and upper limit of bus voltage are compensated with the actual fluctuation amount, so that the switching criteria fit the current electrical state and reduce misjudgments caused by sampling fluctuations. Based on the amplitude and direction of the three-phase current and the relationship between the battery and the bus voltage, the freewheeling direction of the six bridge arms and anti-parallel diodes is selected phase by phase to establish a controlled release path for the remaining winding current. This system ensures that the three-phase current enters the shut-off range before the contactor disconnects, while limiting the rise in bus voltage. The motor-side disconnection state is jointly confirmed by the coil current, contact voltage difference, and branch current. The pre-charge state is jointly confirmed by the coil current, contact voltage difference, pre-charge current, and battery bus voltage difference. Instantaneous jitter is eliminated through continuous sampling and counting. The pre-charge contactor is disconnected only after the main contactor is turned on. The operating conditions are coil de-energization, contact separation, and pre-charge branch current returning to zero. This reduces the risk of current-carrying disconnection, contact arcing, main circuit impact, and contactor malfunction, and improves the safety, accuracy, and continuity of power circuit switching. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the steps of the present invention. Detailed Implementation

[0017] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0018] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0019] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0020] Please see Figure 1 This invention provides a switching control method for motor drive and energy storage power reuse, comprising the following steps: S1: Collect the three-phase winding current, contactor contact voltage, power branch current, contactor coil current and DC bus voltage, calculate the zero current threshold, turn-off current reference range, contactor terminal voltage threshold, bus voltage upper limit, pre-charge current threshold range and pre-charge voltage threshold range, and generate a threshold parameter table. The specific steps of S1 are as follows: S101: Collects three-phase winding current, contactor contact voltage, power branch current, contactor coil current and DC bus voltage. Numbers and arranges the five types of signals according to the same sampling time. Converts the three-phase winding current into absolute value and the contactor contact voltage into differential voltage value. Calculates the maximum, minimum, average and maximum difference between adjacent samples for each value within a continuous sampling period. Establishes a numerical sequence according to the signal name and generates operating statistics. Based on the monitoring signals obtained by the motor drive and energy storage power multiplexing device within a continuous sampling period, the three-phase winding current, contactor contact voltage, power branch current, contactor coil current, and DC bus voltage are assigned corresponding numbers according to the same sampling time. The five types of signals obtained at the same sampling time are written under the same time number. Signals obtained at different sampling times are arranged in chronological order. The positive and negative signs of the A-phase winding current, B-phase winding current, and C-phase winding current are removed, while the current amplitude is retained. The voltage at the first and second terminals of the contactor contacts is subtracted, and the absolute value of the subtraction result is recorded as the contact voltage difference at the corresponding sampling time. The processed absolute values ​​of the three-phase winding current, contact voltage difference, power branch current, contactor coil current, and DC bus voltage are established as numerical sequences according to their signal names. Each numerical sequence is compared item by item, and the largest value is retained as the maximum value. The smallest value is taken as the minimum value. All sampled values ​​in the same numerical sequence are summed and divided by the number of samples in the sequence to obtain the mean. Following the sampling order, the second sampled value is subtracted from the first, and the absolute value is taken; the third sampled value is subtracted from the second, and the absolute value is taken. This process continues until the last sampled value. Then, all adjacent absolute differences are compared, and the largest is retained as the maximum adjacent sampling difference. For example, if the absolute value sequence of a winding current is 2.6A, 2.1A, 1.7A, 1.4A, and 1.2A, then its maximum value is 2.6A, minimum value is 1.2A, and mean is 1.8A. The adjacent absolute differences are 0.5A, 0.4A, 0.3A, and 0.2A, respectively, and the maximum adjacent sampling difference is 0.5A. The signal names and their corresponding maximum, minimum, mean, and maximum adjacent sampling difference are associated and recorded to generate operational statistics.

[0021] S102: Based on the operating statistics, select the minimum absolute value of the three-phase winding current and the maximum value of the difference between adjacent samples and sum them up to calculate the zero current threshold. Set its negative and positive values ​​as the lower and upper limits of the cut-off current reference range. Select the sum of the minimum contact voltage difference and the maximum value of the difference between adjacent samples as the contactor terminal voltage threshold. Set the sum of the maximum DC bus voltage and the maximum value of the difference between adjacent samples as the upper limit of the bus voltage to obtain the disconnection parameter group. Based on the aforementioned operational statistics, the minimum value of the absolute value of the three-phase winding current and the maximum value of the adjacent sampling difference are read. The minimum absolute value of the current and the maximum value of the adjacent sampling difference are added together, and the sum is recorded as the zero current threshold. The zero current threshold directly corresponds to the statistical result of the absolute value of the three-phase winding current within the current continuous sampling period, without introducing any fixed proportion, weight, or correction coefficient. A negative sign is added to the zero current threshold to obtain the lower limit of the turn-off current reference range, and a positive sign is maintained to obtain the upper limit of the turn-off current reference range, so that the lower and upper limits correspond to the negative and positive values ​​of the same zero current threshold, respectively. Then, the minimum value of the contactor contact voltage difference and the maximum value of the adjacent sampling difference are read from the operational statistics. The minimum contact voltage difference and the corresponding maximum value of the adjacent sampling difference are added together, and the sum is recorded as the contactor terminal voltage threshold. Finally, the maximum value of the DC bus voltage and the maximum value of the adjacent sampling difference are read from the operational statistics. The maximum DC bus voltage is added to the maximum difference between adjacent samples, and the sum is recorded as the upper limit of the bus voltage. For example, when the minimum absolute value of the three-phase winding current is 0.3A and the maximum difference between adjacent samples is 0.5A, the zero current threshold is 0.3A plus 0.5A equals 0.8A. The lower limit of the turn-off current reference range is -0.8A, and the upper limit is +0.8A. When the minimum contact voltage difference is 0.04V and the maximum difference between adjacent samples is 0.01V, the contactor terminal voltage threshold is 0.05V. When the maximum DC bus voltage is 352V and the maximum difference between adjacent samples is 1V, the upper limit of the bus voltage is 353V. Each set of values ​​corresponds only to calculation examples of its respective parameters. The zero current threshold, the lower limit of the turn-off current reference range, the upper limit of the turn-off current reference range, the contactor terminal voltage threshold, and the upper limit of the bus voltage are associated and recorded according to their names and values ​​to obtain the disconnection parameter group.

[0022] S103: Call the disconnect parameter group and running statistics, select the minimum and maximum values ​​of the power branch current, collect the energy storage battery terminal voltage and DC bus voltage, calculate the absolute value of the difference between the energy storage battery terminal voltage and the DC bus voltage at the same sampling time, and select the minimum and maximum values ​​of the absolute values ​​of the difference, calculate the two pre-charge threshold ranges, set the minimum and maximum values ​​of the power branch current as the lower limit and upper limit of the pre-charge current threshold range, set the minimum and maximum values ​​of the absolute values ​​of the difference as the lower limit and upper limit of the pre-charge voltage threshold range, write them into the disconnect parameter group and the two pre-charge threshold ranges by name and value, and generate a threshold parameter table; The aforementioned disconnect parameter group and operating statistics are invoked. The minimum and maximum values ​​of the power branch current are read from the operating statistics. The minimum power branch current is recorded as the lower limit of the pre-charge current threshold range, and the maximum power branch current is recorded as the upper limit of the pre-charge current threshold range. The minimum power branch current is obtained by comparing all power branch current samples in a continuous sampling period. In each comparison, the smaller value is retained and compared with the next sample value until all sample values ​​are compared. The maximum power branch current is obtained by comparing the same numerical sequence. In each comparison, the larger value is retained and compared with the next sample value until all sample values ​​are compared. The battery terminal voltage and DC bus voltage are collected in the same continuous sampling period. The battery terminal voltage and DC bus voltage are subtracted at the same sampling time, and the absolute value of the subtraction result is taken to obtain the absolute value of the battery bus voltage difference at each sampling time. A sequence of absolute values ​​of battery bus voltage difference is established according to the order of sampling time. The minimum and maximum values ​​of the absolute values ​​of the battery bus voltage differences are compared item by item in the sequence. The minimum value is recorded as the lower limit of the pre-charge voltage threshold range, and the maximum value is recorded as the upper limit of the pre-charge voltage threshold range. No additional fixed proportions, weights, coefficients, or compensation values ​​are introduced. As an example of actual values, if the current sequence of a certain power branch is 4.8A, 3.5A, 2.2A, and 1.1A, the minimum value of 1.1A and the maximum value of 4.8A are obtained after comparing each value. The corresponding pre-charge current threshold range is 1.1A to 4A. 0.8A; The absolute value sequence of the voltage difference of a certain battery bus is 210V, 145V, 72V, 28V. After comparing each value, the minimum value of 28V and the maximum value of 210V are obtained. The corresponding pre-charge voltage threshold range is 28V to 210V. The two sets of values ​​are used to explain the process of obtaining the boundary of their respective ranges. Cross-group continuous calculation is not performed. The parameters in the disconnected parameter group, the pre-charge current threshold range, and the pre-charge voltage threshold range are written into the same parameter record according to the parameter name and the corresponding value to generate a threshold parameter table.

[0023] S2: Collect the three-phase winding current, DC bus voltage and energy storage battery terminal voltage. Based on the threshold parameter table, compare the absolute value of the three-phase current and the relationship between the two-terminal voltages. Select the six-arm inverter bridge and the corresponding anti-parallel diode according to the current direction to generate the gate drive sequence. The specific steps of S2 are as follows: S201: Collect the three-phase winding current, DC bus voltage and energy storage battery terminal voltage. Arrange the winding current values ​​of phase A, phase B and phase C and the two voltage values ​​at the same sampling time. Record the current flowing from the inverter bridge to the winding as 1, the reverse current as negative 1, and the zero value as 0. Take the absolute value of each phase current, subtract the energy storage battery terminal voltage from the DC bus voltage, calculate the absolute value of the three-phase current, the current direction code and the terminal voltage difference, and generate an electrical parameter array. Based on the three-phase winding current, DC bus voltage, and energy storage battery terminal voltage obtained at each sampling time from the motor drive and energy storage power multiplexing device, a sampling time sequence number k is assigned to each group of data according to the sampling time sequence. Under the same sampling time sequence number, the A-phase winding current, B-phase winding current, C-phase winding current, DC bus voltage, and energy storage battery terminal voltage are arranged sequentially, so that the five data items correspond to the same sampling time. The current value and current direction of each phase winding current are read separately. When the current flows from the inverter bridge to the corresponding phase winding, The phase current direction code is recorded as 1. When the current flows from the corresponding phase winding to the inverter bridge, the phase current direction code is recorded as negative 1. When the current value of the corresponding phase winding is zero, the phase current direction code is recorded as 0. Then, the absolute values ​​of the currents of phase A, phase B, and phase C are taken respectively. The positive current values ​​are directly retained, the negative current values ​​are removed from their negative signs and their amplitudes are retained, and the zero current is retained as zero. The DC bus voltage and the energy storage battery terminal voltage are subtracted at the k-th sampling time, and the terminal voltage difference is calculated according to Equation 1: , Formula 1; In formula 1, Indicates the first The terminal voltage difference at each sampling time, in volts. Indicates the first The DC bus voltage at each sampling time, in volts. Indicates the first The terminal voltage of the energy storage battery at each sampling time, in volts. This represents the sampling time sequence number determined according to the sampling order. Taking actual values ​​as an example, if the A-phase current is 2.7A, the B-phase current is -1.6A, and the C-phase current is 0A at a certain sampling time, then the absolute values ​​of the three-phase currents are 2.7A, 1.6A, and 0A respectively, and the three-phase current direction codes are 1, -1, and 0 respectively. If the DC bus voltage at this time is 336V and the energy storage battery terminal voltage is 330V, then the terminal voltage difference is 336V minus 330V, which equals 6V. Arrange the sampling time sequence number, the absolute values ​​of the three-phase currents, the three-phase current direction codes, and the terminal voltage difference according to their corresponding positions to generate an electrical parameter array.

[0024] S202: Based on the electrical parameter array and threshold parameter table, read the absolute value of the three-phase current, the current direction code, the terminal voltage difference and the zero current threshold, compare the absolute value of each phase current with the zero current threshold, record the corresponding phase state as 0 when it is not greater than the zero current threshold, and retain the current direction code when it is greater than the zero current threshold. Then compare the terminal voltage difference with the zero value, and record the positive value, negative value and zero value as 1, -1 and 0 respectively. Arrange the codes according to the sampling time to obtain the current voltage criterion code. Based on the aforementioned electrical parameter array and threshold parameter table, the absolute values ​​of the currents and current direction codes of phases A, B, and C are read group by group according to the sampling time sequence number. At the same time, the terminal voltage difference at the corresponding sampling time is read, and the zero current threshold is read from the threshold parameter table. For each phase, the absolute value of the current is compared numerically with the zero current threshold. Each sampling time is different The phase status code is determined according to Formula 2. Formula 2; In Equation 2, Indicates the first Each sampling time is different The phase state codes are dimensionless codes. Choose A, B, or C. This indicates the sampling time sequence number determined according to the order of sampling. Indicates the first Each sampling time is different The winding current, in amperes. This represents the absolute value of the corresponding winding current. This indicates the zero current threshold read from the threshold parameter table, in amperes. Indicates the first Each sampling time is different The current direction code is a dimensionless code, with values ​​of 1, -1, or 0. After comparing phases A, B, and C sequentially, the phase status codes for each of the three phases are obtained. Then, the terminal voltage difference at the same sampling time is compared with the zero value. When the terminal voltage difference is greater than zero, the terminal voltage relationship code is recorded as 1; when the terminal voltage difference is less than zero, the terminal voltage relationship code is recorded as -1; and when the terminal voltage difference is equal to zero, the terminal voltage relationship code is recorded as 0. As an example of actual values, if the zero current threshold is 0.7A, the absolute values ​​of the currents in the three phases are 0.5A, 1.3A, and 1.8A, and the original current direction codes are 1, -1, and 1, respectively, then the phase status codes for the three phases are 0, -1, and 1, respectively. If the corresponding terminal voltage difference is -4V, then the terminal voltage relationship code is -1. The phase status codes of phases A, B, and C, as well as the terminal voltage relationship codes, are arranged according to the same sampling time to obtain the current-voltage criterion code.

[0025] Based on the current-voltage criterion code, a six-bit gate bit sequence is established according to the upper and lower bridge arms of phase A, phase B, and phase C, and the status code and terminal voltage relationship code of each phase are read respectively. When the phase status code is 1 or -1, select the bridge arm whose forward conduction direction of the anti-parallel diode is consistent with the direction of the corresponding winding current as the selected bridge arm, and use the other bridge arm of the same phase as the complementary bridge arm. When the terminal voltage relationship code is 1, the selected bridge arm state position is 1 and the complementary bridge arm state position is 0; when the terminal voltage relationship code is -1, the selected bridge arm state position is 0 and the complementary bridge arm state position is 1. When the terminal voltage relationship code is 0, both the selected bridge arm status bit and the complementary bridge arm status bit are set to 0. When the phase status code is 0, the upper and lower bridge arm status bits of the corresponding phase are both set to 0, and the upper and lower bridge arm status bits of the same phase are not simultaneously set to 1. The six-bit status is arranged according to the sampling time to generate the gate drive sequence. Based on the aforementioned current-voltage criterion code, a six-bit gate bit sequence is established according to the order of the upper bridge arm of phase A, the lower bridge arm of phase A, the upper bridge arm of phase B, the lower bridge arm of phase B, the upper bridge arm of phase C, and the lower bridge arm of phase C. Each phase corresponds to one upper bridge arm status bit and one lower bridge arm status bit. Then, the phase status codes of phases A, B, and C, as well as the terminal voltage relationship code at the same sampling time, are read according to the sampling time sequence number. When the phase status code of a certain phase is 1, the forward conduction direction of the anti-parallel diodes corresponding to the upper and lower bridge arms of that phase is read. The forward conduction direction of each anti-parallel diode is compared item by item with the current direction flowing from the inverter bridge to the winding. The bridge arm whose forward conduction direction of the anti-parallel diode is consistent with the current direction of the winding is selected as the bridge arm. The selected bridge arm is designated as the complementary bridge arm, and the other bridge arm in the same phase is designated as the complementary bridge arm. When the phase status code of a certain phase is -1, the forward conduction direction of the anti-parallel diodes corresponding to the upper and lower bridge arms of that phase is compared with the current direction flowing from the winding to the inverter bridge item by item. The bridge arm whose forward conduction direction of the anti-parallel diodes is consistent with the current direction of the winding is selected as the selected bridge arm, and the other bridge arm in the same phase is designated as the complementary bridge arm. When the terminal voltage relationship code is 1, the status bit of the selected bridge arm is set to 1, and the status bit of the complementary bridge arm is set to 0. When the terminal voltage relationship code is -1, the status bit of the selected bridge arm is set to 0, and the status bit of the complementary bridge arm is set to 1. When the terminal voltage relationship code is 0, both the status bits of the selected bridge arm and the complementary bridge arm are set to 0. When the phase status code of a certain phase is 0, both the status bits of the upper and lower bridge arms of that phase are set to 0. During the writing process of each status bit, the upper and lower bridge arm status bits of the same phase are not simultaneously set to 1. As an example of actual values, at a certain sampling moment, the phase status codes of phases A, B, and C are 1, -1, and 0 respectively. Then, phase A selects the bridge arm with the same forward conduction direction as the anti-parallel diode according to the direction of the inverter bridge flow to the winding. Phase B selects the bridge arm with the same forward conduction direction as the anti-parallel diode according to the direction of the winding flow to the inverter bridge. The upper and lower bridge arm status bits of phase C are both set to 0. When the terminal voltage relationship code at the same sampling moment is 1, the selected bridge arm status bits of phases A and B are set to 1, and the complementary bridge arm status bits are set to 0. When the terminal voltage relationship code is -1, the selected bridge arm status bits of phases A and B are set to 0, and the complementary bridge arm status bits are set to 1. When the terminal voltage relationship code is 0, the selected bridge arm status bits and the complementary bridge arm status bits of phases A and B are both set to 0. The states formed by the three phases are connected according to the six-bit gate bit sequence, and the six-bit states of each group are arranged according to the sampling time to generate the gate drive sequence.

[0026] S3: Control the six-arm inverter bridge to turn on according to the gate drive sequence, monitor the three-phase winding current and DC bus voltage, determine that the current of each phase winding is within the turn-off current reference range and the DC bus voltage does not exceed the upper limit of the bus voltage, and generate the motor side contactor disconnect enable signal. The specific steps of S3 are as follows: S301: Control the six-arm inverter bridge to turn on according to the gate drive sequence. Read the six-bit status in the order of A-phase upper arm, A-phase lower arm, B-phase upper arm, B-phase lower arm, C-phase upper arm, and C-phase lower arm. Determine whether each status value is equal to 1. If it is equal to 1, write the turn-on level to the corresponding bridge arm gate drive terminal. If it is not equal to 1, write the turn-off level. Record the six level values ​​in the order of bridge arms. Arrange the sampling time with the six level values ​​to generate the bridge arm turn-on status quantity. Based on the aforementioned gate drive sequence, the corresponding six-bit states are read sequentially according to the sampling time. The six state positions are then mapped to the upper and lower arms of phase A, the upper and lower arms of phase B, the upper and lower arms of phase B, the upper and lower arms of phase C, and the lower arm of phase C. For each state position, a numerical judgment is performed. If the current state value is 1, a conduction level is written to the gate drive terminal of the corresponding arm; if the current state value is not 1, a deactivation level is written to the gate drive terminal of the arm. The reading, judgment, and level writing of the same group of six states are completed sequentially according to the predetermined arm order, without changing the correspondence between the six states and the six arms. This process is repeated after the six gate level writes for the current sampling time are completed. After input, six level values ​​are recorded in the order from the upper bridge arm of phase A to the lower bridge arm of phase C. Then, the current sampling time is established in correspondence with the recorded six level values. Subsequently, the six-bit state of the next sampling time is read and the same process is repeated. As an example of actual values, if the six-bit state of a certain sampling time is 1, 0, 0, 1, 0, 0 in sequence, then the on level is written to the gate drive terminal of the upper bridge arm of phase A and the lower bridge arm of phase B, and the off level is written to the gate drive terminal of the lower bridge arm of phase A, the upper bridge arm of phase B, the upper bridge arm of phase C and the lower bridge arm of phase C. This example only shows the writing relationship between the state value and the gate level. Each sampling time and its corresponding six level values ​​are recorded in sequence to generate the bridge arm conduction state quantity.

[0027] S302: Based on the sampling time corresponding to the conduction state of the bridge arm, monitor the three-phase winding current and DC bus voltage, and synchronously record the A-phase winding current value, B-phase winding current value, C-phase winding current value and DC bus voltage value. Calculate the absolute value of the three-phase winding current, arrange the absolute value of each phase current with the corresponding sampling time, arrange the DC bus voltage value with the corresponding sampling time, and collect them in the order of A-phase, B-phase, C-phase and DC bus to obtain the winding bus value group; Based on the sampling times corresponding to the aforementioned bridge arm conduction status quantities, the three-phase winding currents and DC bus voltages are synchronously monitored. At each sampling time, the A-phase winding current, B-phase winding current, C-phase winding current, and DC bus voltage values ​​are read and written to the data location corresponding to the same sampling time. Absolute value processing is performed on the three-phase winding currents: when the winding current value is positive, the original value is retained; when the winding current value is negative, the negative sign is removed and the current amplitude is retained; when the winding current value is zero, the zero value is retained. This yields the absolute values ​​of the A-phase, B-phase, and C-phase currents. The absolute values ​​of each phase current are then arranged according to their corresponding sampling times, and the DC bus voltage value is compared with the data from the same sampling time. The data at each sampling time is collected in a fixed order: the absolute values ​​of the A-phase current, B-phase current, C-phase current, and DC bus voltage. For example, if the A-phase winding current is -0.6A, the B-phase winding current is 0.4A, and the C-phase winding current is 0A at a certain sampling time, the corresponding absolute values ​​of the three-phase currents are 0.6A, 0.4A, and 0A, respectively. If the DC bus voltage at that sampling time is 350V, then 0.6A, 0.4A, 0A, and 350V are written into the corresponding position at that sampling time in a predetermined order. This set of values ​​only represents the processing of the absolute current values ​​and the arrangement of the four values. By collecting the records in order of sampling time, the winding bus voltage value set is obtained.

[0028] According to the winding bus value group and threshold parameter table, read the absolute value of each phase current, DC bus voltage value, turn-off current reference range and upper limit of bus voltage, determine whether the absolute value of the three phase current is within the turn-off current reference range and whether the DC bus voltage does not exceed the upper limit of bus voltage. When all four conditions are met, write the enable bit as 1. When any condition is not met, write the enable bit as 0. Arrange the enable bits according to the sampling time to generate the motor side contactor disconnect enable signal. Based on the aforementioned winding bus current value group and threshold parameter table, the absolute values ​​of phase A current, phase B current, phase C current, and DC bus voltage are read group by group according to the sampling time. The cut-off current reference range and bus voltage upper limit are read from the threshold parameter table. Since the lower limit of the cut-off current reference range is the negative value of the zero current threshold and the upper limit is the positive value of the zero current threshold, and the current of each phase winding has been converted to a non-negative absolute value, the absolute values ​​of phase A current, phase B current, and phase C current are compared with the upper limit of the cut-off current reference range. When the absolute value of the current in the corresponding phase is not greater than the upper limit of the cut-off current reference range, the current of that phase is determined to be within the cut-off current reference range; otherwise, the current of that phase is determined to be outside the cut-off current reference range. Then, the DC bus voltage value is compared with the upper limit of the bus voltage. When the DC bus voltage value is not greater than the upper limit of the bus voltage, the bus voltage condition is recorded as met. When the DC bus voltage is greater than the upper limit of the bus voltage, the bus voltage condition is marked as invalid. Then, the A-phase current condition, B-phase current condition, C-phase current condition, and bus voltage condition are collected. When the absolute values ​​of the three-phase currents are all within the cutoff current reference range and the bus voltage condition is valid, the enable bit corresponding to the current sampling time is written as 1. When any condition is invalid, the enable bit corresponding to the current sampling time is written as 0. As an example of actual values, a certain cutoff current reference range is from -0.8A to +0.8A, and the absolute values ​​of the three-phase currents are 0.5A, 0.6A, and 0.4A, respectively. The absolute values ​​of the three currents are all not greater than the upper limit of the range of 0.8A. If the DC bus voltage does not exceed the corresponding upper limit of the bus voltage, the enable bit of the sampling time is written as 1. This example only shows the process of judging each of the four conditions and writing the enable bit. The sampling times and the corresponding enable bits are arranged in sequence to generate the motor side contactor disconnect enable signal.

[0029] S4: Based on the motor-side contactor disconnect enable signal and threshold parameter table, disconnect the motor-side contactor coil, monitor the contactor coil current, the voltage across the contacts and the motor-side branch current, and after finding that the motor-side contactor is in the disconnected state, connect the energy storage side pre-charge contactor, monitor the pre-charge contactor coil current, the voltage across the contacts, the pre-charge branch current, the energy storage battery terminal voltage and the DC bus voltage, determine that the pre-charge contactor is in the closed state, the pre-charge branch current is within the pre-charge current threshold range and the voltage difference across the two ends is within the pre-charge voltage threshold range, and generate the energy storage side main contactor closing enable signal; The specific steps of S4 are as follows: S401: Based on the motor-side contactor disconnect enable signal and threshold parameter table, disconnect the motor-side contactor coil, monitor the contactor coil current, the voltage across the contact points and the motor-side branch current, read the zero current threshold and the contactor terminal voltage threshold, determine that the absolute values ​​of the coil current and the branch current are not greater than the zero current threshold and the absolute values ​​of the voltage across the contact points are not less than the contactor terminal voltage threshold. If the condition is met, record it as 1; if it is not met, record it as 0, and generate the motor-side disconnect state value. Based on the aforementioned table of motor-side contactor disconnect enable signal and threshold parameters, the enable bit in the motor-side contactor disconnect enable signal is read. When the enable bit is 1, the power supply to the motor-side contactor coil is cut off. Subsequently, the motor-side contactor coil current, the voltage at the first terminal of the contactor contact, the voltage at the second terminal of the contactor contact, and the motor-side branch current are monitored. The absolute value of the coil current and the absolute value of the motor-side branch current are obtained by taking the absolute value of the branch current. The voltage at the first terminal of the contactor contact is subtracted from the voltage at the second terminal of the contactor contact, and the absolute value of the subtraction result is taken to obtain the absolute value of the voltage across the contact. The zero current threshold and the contactor terminal voltage threshold are read from the threshold parameter table. The absolute value of the coil current is compared with the zero current threshold. If the absolute value of the coil current is not greater than the zero current threshold, the first judgment result is recorded as true; otherwise, it is recorded as false. The motor-side contactor is then disconnected. The absolute value of the branch current is compared with the zero current threshold. If the absolute value of the branch current is not greater than the zero current threshold, the second judgment result is recorded as true; otherwise, it is recorded as false. The absolute value of the voltage across the contact is compared with the contactor terminal voltage threshold. If the absolute value of the voltage across the contact is not less than the contactor terminal voltage threshold, the third judgment result is recorded as true; otherwise, it is recorded as false. When all three judgment results are true, the motor-side disconnected state value is written as 1. When any one judgment result is false, the motor-side disconnected state value is written as 0. As an example of actual values, when the zero current threshold is 0.8A, the contactor terminal voltage threshold is 0.05V, the absolute value of the coil current is 0.2A, the absolute value of the branch current is 0.4A, and the absolute value of the voltage across the contact is 12V, all three judgment results are true, the motor-side disconnected state value is written as 1, and the motor-side disconnected state value is generated.

[0030] S402: Based on the motor-side disconnected state value, read the state bit. When the state bit is 1, connect the energy storage side pre-charge contactor, monitor the pre-charge contactor coil current, contact voltage, pre-charge branch current, energy storage battery terminal voltage and DC bus voltage, calculate the absolute value of coil current, contact voltage, pre-charge branch current and the absolute value of the difference between energy storage battery terminal voltage and DC bus voltage, arrange the four values ​​according to the sampling time to obtain the loop monitoring quantity group; Based on the aforementioned motor-side disconnected state value, the state bit is read. When the state bit is 1, the energy storage side pre-charge contactor is connected. The pre-charge contactor coil current, the voltage at the first and second terminals of the pre-charge contactor contacts, the pre-charge branch current, the energy storage battery terminal voltage, and the DC bus voltage are monitored according to the sampling time. The absolute value of the pre-charge contactor coil current is obtained by taking the absolute value of the coil current. The voltage at the first and second terminals of the pre-charge contactor contacts is subtracted, and the absolute value of the subtraction result is taken to obtain the absolute value of the voltage across the contacts. The absolute value of the pre-charge branch current is also obtained by taking the absolute value of the pre-charge branch current. The energy storage battery terminal voltage is subtracted from the DC bus voltage, and the absolute value of the subtraction result is taken. The absolute value of the battery bus voltage difference is calculated according to Equation 3. Formula 3; In Formula 3, Indicates the first The absolute value of the battery bus voltage difference at each sampling time, in volts, with subscripts... Indicates the precharge circuit. Indicates the first The terminal voltage of the energy storage battery at each sampling time, in volts, with subscript... Indicates the energy storage battery end, Indicates the first DC bus voltage at each sampling time, in volts, subscript Indicates DC bus, The sampling time number is used as an example of actual values. At a certain sampling time, the coil current is -0.9A, the difference between the voltage at the first and second terminals of the contact is -0.03V, the pre-charge branch current is 4.2A, the energy storage battery terminal voltage is 360V, and the DC bus voltage is 342V. The four values ​​are 0.9A, 0.03V, 4.2A, and 18V, respectively. The four values ​​are arranged in the order of the absolute value of the coil current, the absolute value of the voltage at both ends of the contact, the absolute value of the pre-charge branch current, and the absolute value of the difference in the battery bus voltage, and the corresponding sampling time to obtain the loop monitoring quantity group.

[0031] S403: Call the circuit monitoring quantity group and threshold parameter table, determine whether the absolute value of the coil current is greater than the zero current threshold, the absolute value of the voltage across the contact is not greater than the contactor terminal voltage threshold, the absolute value of the precharge branch current is within the precharge current threshold range, and the absolute value of the battery bus voltage difference is within the precharge voltage threshold range. Write 1 if all four conditions are met, and write 0 if any condition is not met. Arrange the written values ​​according to the sampling time to generate the energy storage side main contactor closing enable signal. Calling the aforementioned circuit monitoring quantity group and threshold parameter table, read the absolute values ​​of the precharge contactor coil current, the voltage across the contact points, the precharge branch current, and the battery bus voltage difference at the sampling time. From the threshold parameter table, read the zero current threshold, contactor terminal voltage threshold, lower limit of the precharge current threshold range, upper limit of the precharge current threshold range, lower limit of the precharge voltage threshold range, and upper limit of the precharge voltage threshold range. Compare the absolute value of the coil current with the zero current threshold. If the absolute value of the coil current is greater than the zero current threshold, the first judgment result is recorded as true; otherwise, it is recorded as false. Compare the absolute value of the voltage across the contact points with the contactor terminal voltage threshold. If the absolute value of the voltage across the contact points is not greater than the contactor terminal voltage threshold, the second judgment result is recorded as true; otherwise, it is recorded as false. Compare the absolute value of the precharge branch current with the lower and upper limits of the precharge current threshold range respectively. When the absolute value of the precharge branch current is not less than the lower limit of the range and not greater than the upper limit of the range, the third judgment result is recorded as true; otherwise, it is recorded as false. The absolute value of the battery bus voltage difference is compared with the lower limit and upper limit of the precharge voltage threshold range, respectively. When the absolute value of the battery bus voltage difference is not less than the lower limit of the range and not greater than the upper limit of the range, the fourth judgment result is recorded as true; otherwise, it is recorded as false. When all four judgment results are true, the write value at the current sampling time is recorded as 1. When any judgment result is false, the write value is recorded as 0. As an example of actual values, when the absolute value of the coil current is greater than the zero current threshold, the absolute value of the voltage at both ends of the contact is not greater than the contactor terminal voltage threshold, and the absolute value of the precharge branch current and the absolute value of the battery bus voltage difference are respectively within the corresponding threshold range, the write value is recorded as 1. The sampling times and the corresponding write values ​​are arranged sequentially to generate the energy storage side main contactor closing enable signal.

[0032] S5: Based on the main contactor closing enable signal of the energy storage side, the main contactor is turned on. After confirming that the main branch is conducting, the pre-charge contactor is turned off. After determining that the pre-charge branch current is zero, an energy storage power reuse operation signal is generated. The specific steps of S5 are as follows: S501: Based on the main contactor closing enable signal of the energy storage side, the main contactor is turned on, the coil current and contact voltage of the main contactor are monitored, the zero current threshold and the contactor terminal voltage threshold are called in the threshold parameter table, and it is determined that the absolute value of the coil current is greater than the zero current threshold and the absolute value of the contact voltage is not greater than the contactor terminal voltage threshold. When both conditions are met, the conduction bit is recorded as 1. When either condition is not met, the conduction bit is recorded as 0. The conduction bits are arranged according to the sampling time to generate the main branch conduction status value. Based on the aforementioned energy storage side main contactor closing enable signal, the corresponding enable bit is read according to the sampling time. When the enable bit is 1, the energy storage side main contactor is turned on. Subsequently, the main contactor coil current and main contactor contact voltage are monitored and recorded according to the corresponding sampling time. The absolute value of the main contactor coil current is taken. When the coil current is positive, the original value is retained. When the coil current is negative, the negative sign is removed and its amplitude is retained. When the coil current is zero, the zero value is retained. The absolute value of the main contactor contact voltage is taken and its non-negative amplitude is retained. Then, the zero current threshold and contactor terminal voltage threshold are read from the threshold parameter table. The absolute value of the coil current is compared with the zero current threshold. When the absolute value of the coil current is greater than the zero current threshold, the coil current judgment result is recorded as true. When the absolute value of the coil current is not greater than the zero current threshold, the coil current is recorded as true. The judgment result is recorded as invalid. The absolute value of the contact voltage is compared with the contactor terminal voltage threshold. When the absolute value of the contact voltage is not greater than the contactor terminal voltage threshold, the contact voltage judgment result is recorded as valid. When the absolute value of the contact voltage is greater than the contactor terminal voltage threshold, the contact voltage judgment result is recorded as invalid. When both judgment results are valid, the conduction bit at the corresponding sampling time is recorded as 1. When either judgment result is invalid, the conduction bit is recorded as 0. As an example of actual values, the zero current threshold is 0.7A, the contactor terminal voltage threshold is 0.05V, the absolute value of the main contactor coil current at a certain sampling time is 0.9A, and the absolute value of the contact voltage is 0.03V. Then both judgment results are valid, and the corresponding conduction bit is recorded as 1. This set of values ​​only represents the comparison process of two conditions. The conduction bits are arranged in sequence according to the sampling time to generate the main branch conduction state value.

[0033] S502: Based on the main branch conduction status value, read the status bit. When the status bit is 1, disconnect the precharge contactor coil. Monitor the precharge contactor coil current, contact voltage and precharge branch current. Record the three values ​​at the same sampling time. Calculate the absolute value of coil current, absolute value of contact voltage and absolute value of precharge branch current. Arrange the three absolute values ​​with the corresponding sampling time to obtain the precharge disconnection value group. Based on the aforementioned main branch conduction status value, read the status bit corresponding to the current sampling time. When the status bit is 1, the pre-charge contactor coil is disconnected. Subsequently, monitor the pre-charge contactor coil current, pre-charge contactor contact voltage, and pre-charge branch current at the same sampling time. Record the three monitored values ​​at the position corresponding to the same sampling time. Take the absolute value of the pre-charge contactor coil current. When the coil current is positive, retain the original value; when the coil current is negative, remove the negative sign and retain its amplitude; when the coil current is zero, retain the zero value. Take the absolute value of the pre-charge contactor contact voltage and retain its non-negative amplitude. Take the absolute value of the pre-charge branch current. When the pre-charge branch current is positive, retain the original value; when the pre-charge branch current is negative, remove the negative sign and retain its amplitude. The amplitude is retained, and when the pre-charge branch current is zero, the zero value is retained. Then, the three values ​​are arranged in a fixed order according to the absolute value of the pre-charge contactor coil current, the absolute value of the pre-charge contactor contact voltage, and the absolute value of the pre-charge branch current, so that each group of three absolute values ​​is associated with the corresponding sampling time. As an example of actual values, at a certain sampling time, the pre-charge contactor coil current is -0.3A, the contact voltage is 8V, and the pre-charge branch current is -0.5A. After taking the absolute values, we get 0.3A, 8V, and 0.5A respectively. This group of values ​​only represents the absolute value conversion and arrangement process of the three monitored values ​​and is not used as a fixed judgment parameter. The three absolute values ​​obtained at different sampling times are recorded in the order of sampling to obtain the pre-charge disconnection value group.

[0034] S503: Call the precharge disconnection value group and threshold parameter table, read the absolute value of coil current, absolute value of contact voltage, absolute value of precharge branch current, zero current threshold and contactor terminal voltage threshold, determine that the absolute value of coil current is not greater than the zero current threshold, the absolute value of contact voltage is not less than the contactor terminal voltage threshold and the absolute value of precharge branch current is not greater than the zero current threshold. If all three conditions are met, write the operation bit as 1, and write 0 otherwise, and generate the energy storage power reuse operation signal. Calling the aforementioned pre-charge disconnection value group and threshold parameter table, read the absolute values ​​of the pre-charge contactor coil current, pre-charge contactor contact voltage, and pre-charge branch current at the sampling time. Then, read the zero-current threshold and contactor terminal voltage threshold from the threshold parameter table. Compare the absolute value of the pre-charge contactor coil current with the zero-current threshold. If the absolute value of the coil current is not greater than the zero-current threshold, the coil current judgment result is recorded as true; if the absolute value of the coil current is greater than the zero-current threshold, the coil current judgment result is recorded as false. Similarly, compare the absolute value of the pre-charge contactor contact voltage with the contactor terminal voltage threshold. If the absolute value of the contact voltage is not less than the contactor terminal voltage threshold, the contact voltage judgment result is recorded as true; if the absolute value of the contact voltage is less than the contactor terminal voltage threshold, the contact voltage judgment result is recorded as false. The system compares the absolute value of the pre-charge branch current with the zero current threshold. If the absolute value of the pre-charge branch current is not greater than the zero current threshold, the pre-charge branch current judgment result is recorded as true. If the absolute value of the pre-charge branch current is greater than the zero current threshold, the pre-charge branch current judgment result is recorded as false. When all three judgment results are true, the operation bit is written as 1. When any one judgment result is false, the operation bit is written as 0. For example, the zero current threshold is 0.6A, the contactor terminal voltage threshold is 0.05V, the absolute value of the coil current at a certain sampling moment is 0.2A, the absolute value of the contact voltage is 10V, and the absolute value of the pre-charge branch current is 0.3A. In this case, all three judgment results are true, and the operation bit is written as 1. This set of values ​​only represents the threshold comparison and operation bit writing process, generating the energy storage power reuse operation signal.

[0035] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A switching control method for motor drive and energy storage power reuse, characterized in that, Includes the following steps: S1: Collect the three-phase winding current, contactor contact voltage, power branch current, contactor coil current and DC bus voltage, calculate the zero current threshold, turn-off current reference range, contactor terminal voltage threshold, bus voltage upper limit, pre-charge current threshold range and pre-charge voltage threshold range, and generate a threshold parameter table. S2: Collect the three-phase winding current, DC bus voltage and energy storage battery terminal voltage. Based on the threshold parameter table, compare the absolute value of the three-phase current and the relationship between the two-terminal voltages. Select the six-arm inverter bridge and the corresponding anti-parallel diode according to the current direction to generate the gate drive sequence. S3: Control the six-arm inverter bridge to turn on according to the gate drive sequence, monitor the three-phase winding current and DC bus voltage, determine that the current of each phase winding is within the turn-off current reference range and the DC bus voltage does not exceed the upper limit of the bus voltage, and generate the motor side contactor disconnect enable signal. S4: Based on the motor-side contactor disconnect enable signal and threshold parameter table, disconnect the motor-side contactor coil, monitor the contactor coil current, the voltage across the contacts and the motor-side branch current, and after finding that the motor-side contactor is in the disconnected state, connect the energy storage side pre-charge contactor, monitor the pre-charge contactor coil current, the voltage across the contacts, the pre-charge branch current, the energy storage battery terminal voltage and the DC bus voltage, determine that the pre-charge contactor is in the closed state, the pre-charge branch current is within the pre-charge current threshold range and the voltage difference across the two ends is within the pre-charge voltage threshold range, and generate the energy storage side main contactor closing enable signal; S5: Based on the main contactor closing enable signal of the energy storage side, the main contactor is turned on. After confirming that the main branch is conducting, the pre-charge contactor is turned off. After determining that the pre-charge branch current is zero, an energy storage power reuse operation signal is generated.

2. The switching control method for motor drive and energy storage power reuse according to claim 1, characterized in that, The specific steps of S1 are as follows: S101: Collects three-phase winding current, contactor contact voltage, power branch current, contactor coil current and DC bus voltage. Numbers and arranges the five types of signals according to the same sampling time. Converts the three-phase winding current into absolute value and the contactor contact voltage into differential voltage value. Calculates the maximum, minimum, average and maximum difference between adjacent samples for each value within a continuous sampling period. Establishes a numerical sequence according to the signal name and generates operating statistics. S102: Based on the operating statistics, select the minimum absolute value of the three-phase winding current and the maximum value of the difference between adjacent samples and sum them up to calculate the zero current threshold. Set its negative and positive values ​​as the lower and upper limits of the cut-off current reference range. Select the sum of the minimum contact voltage difference and the maximum value of the difference between adjacent samples as the contactor terminal voltage threshold. Set the sum of the maximum DC bus voltage and the maximum value of the difference between adjacent samples as the upper limit of the bus voltage to obtain the disconnection parameter group. S103: Call the disconnect parameter group and running statistics, select the minimum and maximum values ​​of the power branch current, collect the energy storage battery terminal voltage and DC bus voltage, calculate the absolute value of the difference between the energy storage battery terminal voltage and the DC bus voltage at the same sampling time, and select the minimum and maximum values ​​of the absolute values ​​of the difference, calculate the two pre-charge threshold ranges, set the minimum and maximum values ​​of the power branch current as the lower limit and upper limit of the pre-charge current threshold range, and set the minimum and maximum values ​​of the absolute values ​​of the difference as the lower limit and upper limit of the pre-charge voltage threshold range, and write them into the disconnect parameter group and the two pre-charge threshold ranges by name and value to generate a threshold parameter table.

3. The switching control method for motor drive and energy storage power reuse according to claim 2, characterized in that, The method for determining the maximum value of the adjacent sampling difference is as follows: according to the order of sampling time, calculate the absolute value of the difference between the current sampling value and the previous sampling value in the same signal, and select the maximum value from all the absolute differences corresponding to a continuous sampling period, and use the maximum value as the fluctuation compensation amount of the corresponding monitoring signal.

4. The switching control method for motor drive and energy storage power reuse according to claim 1, characterized in that, The specific steps of S2 are as follows: S201: Collect the three-phase winding current, DC bus voltage and energy storage battery terminal voltage. Arrange the winding current values ​​of phase A, phase B and phase C and the two voltage values ​​at the same sampling time. Record the current flowing from the inverter bridge to the winding as 1, the reverse current as negative 1, and the zero value as 0. Take the absolute value of each phase current, subtract the energy storage battery terminal voltage from the DC bus voltage, calculate the absolute value of the three-phase current, the current direction code and the terminal voltage difference, and generate an electrical parameter array. S202: Based on the electrical parameter array and threshold parameter table, read the absolute value of the three-phase current, the current direction code, the terminal voltage difference and the zero current threshold. Compare the absolute value of each phase current with the zero current threshold. If it is not greater than the zero current threshold, record the corresponding phase state as 0. If it is greater than the zero current threshold, retain the current direction code. Then compare the terminal voltage difference with the zero value. The positive value, negative value and zero value are recorded as 1, -1 and 0 respectively. Arrange the codes according to the sampling time to obtain the current and voltage criterion codes.

5. The switching control method for motor drive and energy storage power reuse according to claim 4, characterized in that, Based on the current-voltage criterion code, a six-bit gate bit sequence is established according to the upper and lower bridge arms of phase A, phase B, and phase C, and the status code and terminal voltage relationship code of each phase are read respectively. When the phase status code is 1 or -1, select the bridge arm whose forward conduction direction of the anti-parallel diode is consistent with the direction of the corresponding winding current as the selected bridge arm, and use the other bridge arm of the same phase as the complementary bridge arm. When the terminal voltage relationship code is 1, the selected bridge arm state position is 1 and the complementary bridge arm state position is 0; when the terminal voltage relationship code is -1, the selected bridge arm state position is 0 and the complementary bridge arm state position is 1. When the terminal voltage relationship code is 0, both the selected bridge arm status bit and the complementary bridge arm status bit are set to 0. When the phase status code is 0, the upper and lower bridge arm status bits of the corresponding phase are both set to 0, and the upper and lower bridge arm status bits of the same phase are not simultaneously set to 1. The six-bit status is arranged according to the sampling time to generate the gate drive sequence.

6. The switching control method for motor drive and energy storage power reuse according to claim 1, characterized in that, The specific steps of S3 are as follows: S301: Control the six-arm inverter bridge to turn on according to the gate drive sequence. Read the six-bit status in the order of A-phase upper arm, A-phase lower arm, B-phase upper arm, B-phase lower arm, C-phase upper arm, and C-phase lower arm. Determine whether each status value is equal to 1. If it is equal to 1, write the turn-on level to the corresponding bridge arm gate drive terminal. If it is not equal to 1, write the turn-off level. Record the six level values ​​in the order of bridge arms. Arrange the sampling time with the six level values ​​to generate the bridge arm turn-on status quantity. S302: Based on the sampling time corresponding to the bridge arm conduction state quantity, monitor the three-phase winding current and DC bus voltage, synchronously record the A-phase winding current value, B-phase winding current value, C-phase winding current value and DC bus voltage value, calculate the absolute value of the three-phase winding current, arrange the absolute value of each phase current with the corresponding sampling time, arrange the DC bus voltage value with the corresponding sampling time, and collect them in the order of A-phase, B-phase, C-phase and DC bus to obtain the winding bus quantity value group.

7. The switching control method for motor drive and energy storage power reuse according to claim 6, characterized in that, Based on the winding bus value group and threshold parameter table, read the absolute value of each phase current, DC bus voltage value, turn-off current reference range and upper limit of bus voltage, determine whether the absolute values ​​of the three phase currents are all within the turn-off current reference range and whether the DC bus voltage does not exceed the upper limit of bus voltage. If all four conditions are met, write the enable bit as 1. If any condition is not met, write the enable bit as 0. Arrange the enable bits according to the sampling time to generate the motor side contactor disconnect enable signal.

8. The switching control method for motor drive and energy storage power reuse according to claim 1, characterized in that, The specific steps of S4 are as follows: S401: Based on the motor-side contactor disconnect enable signal and threshold parameter table, disconnect the motor-side contactor coil, monitor the contactor coil current, the voltage across the contact points and the motor-side branch current, read the zero current threshold and the contactor terminal voltage threshold, determine that the absolute values ​​of the coil current and the branch current are not greater than the zero current threshold and the absolute values ​​of the voltage across the contact points are not less than the contactor terminal voltage threshold. If the condition is met, record it as 1; if it is not met, record it as 0, and generate the motor-side disconnect state value. S402: Based on the motor-side disconnected state value, read the state bit. When the state bit is 1, connect the energy storage side pre-charge contactor, monitor the pre-charge contactor coil current, contact voltage, pre-charge branch current, energy storage battery terminal voltage and DC bus voltage, calculate the absolute value of coil current, contact voltage, pre-charge branch current and the absolute value of the difference between energy storage battery terminal voltage and DC bus voltage, arrange the four values ​​according to the sampling time to obtain the loop monitoring quantity group; S403: Call the loop monitoring quantity group and threshold parameter table, determine whether the absolute value of the coil current is greater than the zero current threshold, the absolute value of the voltage across the contact is not greater than the contactor terminal voltage threshold, the absolute value of the precharge branch current is within the precharge current threshold range, and the absolute value of the battery bus voltage difference is within the precharge voltage threshold range. Write 1 if all four conditions are met, and write 0 if any one condition is not met. Arrange the written values ​​according to the sampling time to generate the energy storage side main contactor closing enable signal.

9. The switching control method for motor drive and energy storage power reuse according to claim 8, characterized in that, The generation of the energy storage side main contactor closing enable signal also includes: continuously counting the results of the four judgment conditions, incrementing the count value when all four judgment conditions are met at adjacent sampling times, clearing the count value when any judgment condition is not met, and setting the energy storage side main contactor closing enable signal to an active state after the count value reaches a preset number of confirmations.

10. The switching control method for motor drive and energy storage power reuse according to claim 1, characterized in that, The specific steps of S5 are as follows: S501: Based on the main contactor closing enable signal of the energy storage side, the main contactor is turned on, the coil current and contact voltage of the main contactor are monitored, the zero current threshold and the contactor terminal voltage threshold are called in the threshold parameter table, and it is determined that the absolute value of the coil current is greater than the zero current threshold and the absolute value of the contact voltage is not greater than the contactor terminal voltage threshold. When both conditions are met, the conduction bit is recorded as 1. When either condition is not met, the conduction bit is recorded as 0. The conduction bits are arranged according to the sampling time to generate the main branch conduction status value. S502: Based on the main branch conduction status value, read the status bit. When the status bit is 1, disconnect the precharge contactor coil. Monitor the precharge contactor coil current, contact voltage and precharge branch current. Record the three values ​​at the same sampling time. Calculate the absolute value of coil current, absolute value of contact voltage and absolute value of precharge branch current. Arrange the three absolute values ​​with the corresponding sampling time to obtain the precharge disconnection value group. S503: Call the precharge disconnection value group and threshold parameter table, read the absolute value of coil current, absolute value of contact voltage, absolute value of precharge branch current, zero current threshold and contactor terminal voltage threshold, determine whether the absolute value of coil current is not greater than the zero current threshold, the absolute value of contact voltage is not less than the contactor terminal voltage threshold and the absolute value of precharge branch current is not greater than the zero current threshold. If all three conditions are met, write the operation bit as 1, otherwise write it as 0, and generate the energy storage power reuse operation signal.

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