TWI748768B - Motor driving system - Google Patents

Abstract

A motor driving system is provided, which has a pre-charging circuit with an intelligent charging and discharging mechanism. In terms of charging, a delay circuit can be used to delay a turn-on timing of a low impedance path. A detection circuit is also provided to detect system status and battery voltage, and perform a discharge process in a non-driving mode and when a voltage of battery continues to decrease. In the discharge process, a driving mechanism of the motor drive system can also be used to achieve a variety of applications.

Description

Motor drive system

The invention relates to a motor drive system, in particular to a motor drive system with a pre-charging circuit with an intelligent charging and discharging mechanism.

In the existing motor electric drive system, in order to avoid instantaneous large currents in the process of power-on drive, causing system damage and reduced service life. Therefore, a pre-charge circuit is usually configured between the power supply (for example, a battery) and the controller. The purpose is to use a lower current to fully charge the internal capacitor, and then turn on the switch on the main loop to avoid Generate instantaneous high current and cause system damage.

Generally speaking, the pre-charging circuit can work normally during the start-up process, but problems often occur during the power-off process. For example, when the system is about to shut down, its controller will not drive the motor, so the current consumption of the system is very low at this time, so that it takes a lot of time for the internal capacitor to discharge below the rated safe voltage (10 seconds to minutes). During this discharging process, if the power supply is restarted immediately, or the battery cells that have not been powered on are started in stages, because the capacitor voltage has not reached the threshold voltage for starting the precharge, an instantaneous large current will be generated, causing system damage or system failure. can.

The technical problem to be solved by the present invention is to provide a motor drive system with a pre-charging circuit with an intelligent charging and discharging mechanism in view of the shortcomings of the prior art.

In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a motor drive system for driving a motor. The motor drive system includes a battery pack, a power control circuit, a capacitor, an inverter circuit, and a motor control. Circuit, state detection circuit, pre-charge circuit, delay circuit and discharge control circuit. The battery pack includes a first battery unit and a second battery unit connected in series between a first input terminal and a second input terminal. The power control circuit is configured to control the turn-on and turn-off of the battery pack. The capacitor is connected between the first input terminal and the second input terminal. The inverter circuit is connected to the first input terminal and the second input terminal to be powered by the battery pack, and has a plurality of switching elements that are bridged to form a plurality of output terminals, wherein the output terminals are respectively connected to the motor. A phase winding. The motor control circuit is configured to generate a motor control signal group to control the switching actions of the switching elements, so that each phase winding of the motor is energized to drive the motor. The state detection circuit is configured to detect the operating state of the motor drive system. The pre-charge circuit includes a high-impedance path, a low-impedance path, a pre-charge switch, and a detection circuit. The high impedance path is connected between the second input terminal and the battery pack. The low impedance path is connected between the second input terminal and the battery pack, wherein the resistance value of the high impedance path is greater than the resistance value of the low impedance path. The precharge switch is provided on this low impedance path. The detection circuit is configured to: compare a first voltage of the first input terminal with a pre-charge start voltage, and correspondingly generate a detection result signal, wherein, in response to the first voltage being higher than the pre-charge start voltage The detection result signal is used to control the pre-charge switch to turn on, and in response to the first voltage being less than or equal to the pre-charge start voltage, the detection result signal is used to control the pre-charge switch to turn off. The detection circuit is further configured to detect whether the operating state is a non-driving mode and whether the first voltage drops over time, wherein, in response to detecting that the operating state is the non-driving mode and the first voltage drops over time , Output a discharge indication signal for performing a discharge procedure on the capacitor, and stop outputting the discharge indication signal until it is detected that the first voltage no longer drops over time. The delay circuit is arranged between the detection circuit and the precharge switch, and is configured to delay the detection result signal by a predetermined delay time. The discharge control circuit is configured to execute the discharge procedure according to the discharge instruction signal, including: Obtain a current operating angle of the motor through the motor control circuit; and according to the current operating angle, correct the motor control signal group with a correction angle to drive the motor to stop and enter a discharge mode.

One of the beneficial effects of the present invention is that the motor drive system provided by the present invention has a pre-charging circuit with an intelligent charging and discharging mechanism. In terms of charging, the delay circuit can be used to delay the turn-on timing of the low-impedance path, and the internal capacitor after charging can avoid the instantaneous large current that may cause system damage when the system restarts quickly.

On the other hand, the detection circuit of the pre-charge circuit can simultaneously detect the system status and the battery voltage, and perform the discharge process in the non-driving mode and when the battery voltage continues to decrease, so that the voltage can be lower than the rated safe voltage and the pre-charge starting voltage, and In the discharging process, the drive mechanism of the motor drive system can also be used to achieve a variety of applications.

In order to further understand the features and technical content of the present invention, please refer to the following detailed description and drawings about the present invention. However, the provided drawings are only for reference and description, and are not used to limit the present invention.

1: Motor drive system

10: battery pack

11: Power control circuit

12: Inverter circuit

13: Motor control circuit

14: Status detection circuit

15: Precharge circuit

16: discharge control circuit

130: first processing circuit

131: drive control circuit

132: The first voltage detection circuit

133: Phase current detection circuit

150: detection circuit

151: Delay circuit

152: second processing circuit

153: The second voltage detection circuit

154: storage unit

14': Controller area network

B1: The first battery unit

B2: The second battery unit

C1: Capacitance

H1, H2, H3, L1, L2, L3: Motor control signal

Ic1, Ic2: Capacitor discharge current

In1: the first input

In2: second input

Iu, Iv, Iw: phase current

M: Motor

O1, O2, O3: output terminal

P1: Low impedance path

P2: High impedance path

R1, R2: resistance

S1: Detection result signal

S2: Discharge indicator signal

S3: Power status signal

SW1~SW6: switching element

SWp: pre-charge switch

t0, t1, t2: time

T1: Delay time

V1: first voltage

Vc: Capacitor voltage

Vgs: pre-charge switch signal

Vpc: pre-charge starting voltage

Fig. 1 is a functional block diagram of a motor drive system according to an embodiment of the present invention.

Fig. 2 is a functional block diagram of a motor control circuit according to an embodiment of the present invention.

3 is a detailed functional block diagram of the detection circuit and a block diagram of its peripheral circuits according to an embodiment of the present invention.

FIG. 4 is a graph of voltage and current versus time of a pre-charging circuit applying a smart discharge mechanism according to an embodiment of the present invention.

FIG. 5 is a graph of voltage and current versus time of a precharge circuit applying a delayed turn-on mechanism according to an embodiment of the present invention.

FIG. 6 is a diagram of a detection circuit used to execute a state detection procedure according to an embodiment of the present invention flow chart.

The following is a specific embodiment to illustrate the implementation of the "motor drive system" disclosed in the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be based on different viewpoints and applications, and various modifications and changes can be made without departing from the concept of the present invention. In addition, the drawings of the present invention are merely schematic illustrations, and are not drawn according to actual size, and are stated in advance. The following embodiments will further describe the related technical content of the present invention in detail, but the disclosed content is not intended to limit the protection scope of the present invention. In addition, the term "or" used in this document may include any one or a combination of more of the associated listed items depending on the actual situation.

Referring to FIG. 1, an embodiment of the present invention provides a motor drive system 1 for driving a motor M. The motor drive system 1 includes a battery pack 10, a power control circuit 11, a capacitor C1, an inverter circuit 12, and a motor control Circuit 13, state detection circuit 14, pre-charge circuit 15, and discharge control circuit 16.

The battery pack 10 may basically include a first battery cell B1 and a second battery cell B2 connected in series between the first input terminal In1 and the second input terminal In2, but the present invention is not limited to this, and the battery pack 10 may include two The battery unit above. The first battery cell B1 and the second battery cell B2 can be, for example, lithium-ion batteries, lithium-ion polymer batteries, lead-acid batteries (full-cell lead-acid batteries, deep-cycle lead-acid batteries, and valve-regulated lead-acid batteries), nickel-cadmium Batteries, nickel-metal hydride batteries, zinc-air batteries, sodium nickel chloride batteries (zebra), etc., and each includes a built-in overcurrent protection circuit.

The power control circuit 11 can be used to control the battery pack 10 to turn on and off. For example, the power control circuit 11 can be, for example, a power management circuit including a power converter, but the present invention is not limited to this. The capacitor C1 is connected between the first input terminal In1 and the second input terminal In2. The inverter circuit 12 is connected to the first input terminal In1 and the second input terminal In2 to be powered by the battery pack 10, and has multiple switching elements that are bridged to form multiple output terminals. For example, as shown in FIG. The converter circuit 12 includes switching elements SW1 to SW6, and respectively form output terminals O1, O2, and O3. The output terminals O1, O2, and O3 are respectively connected to multiple phase windings of the motor M. Taking a three-phase motor as an example, the output terminals O1, O2, and O3 can be respectively connected to the U-phase winding, V-phase winding and W-phase winding of the motor M.

The motor control circuit 13 can be configured to generate a motor control signal group to control the switching actions of the above-mentioned switching elements, so that each phase winding of the motor M is energized to drive the motor M. The motor control signal group may include motor control signals H1, H2, H3, L1, L2, and L3. Further reference may be made to FIG. 2, which is a functional block diagram of a motor control circuit according to an embodiment of the present invention. As shown in FIG. 2, the motor control circuit 13 may include a first processing circuit 130, a driving control circuit 131, a first voltage detection circuit 132 and a phase current detection circuit 133.

The first processing circuit 130 may be, for example, a microprocessor or a digital signal processor. The first processing circuit 130 may be configured to execute a motor control algorithm to obtain independent torque from the instantaneous phase currents Iu, Iv, Iw Current and field current. Simple AC motor control can be achieved by using a microprocessor-based control system, and high-end AC inverters will be implemented with a digital signal processor (DSP). The phase current detection circuit 133 can be configured to detect the phase currents Iu, Iv, Iw of the U-phase winding, V-phase winding, and W-phase winding of the motor M to generate angle information indicating the current operating angle of the motor M , The first voltage detection circuit 132 can be used to detect the first voltage V1 on the first input terminal In1.

The state detection circuit 14 is configured to detect the operating state of the motor drive system 1. The state detection circuit 14 may be, for example, a Controller Area Network (CAN), which is used to exchange information between various electronic control devices in a mobile vehicle such as a car or a locomotive to form an electronic control network. .

The precharge circuit 15 may include a low impedance path P1, a high impedance path P2, and a precharge switch. Turn off SWp, detection circuit 150, and delay circuit 151. The low impedance path P1 and the high impedance path P2 are respectively connected between the second input terminal In2 and the battery pack 10, and the resistance value of the high impedance path P2 is greater than the resistance value of the low impedance path P1, and the precharge switch SWp is set at low impedance On path P1.

For example, the low impedance path P1 includes a resistor R1 and the precharge switch SWp, and the high impedance path P2 includes a resistor R2. Among them, the resistance value of the resistor R2 is higher than the resistance value of the resistor R1. Therefore, when the motor drive circuit 1 is started, since there is no charge or only a very low residual voltage on the capacitor C1, the high impedance path P2 can be used to prevent the battery pack 10 from being directly exposed. Instantaneous short circuit caused by conduction with capacitor C1.

In the embodiment of the present invention, the detection circuit 150 needs to play two roles, namely judging whether the battery voltage reaches the pre-charge starting voltage, and judging whether to start the discharge mechanism according to the system state and the battery voltage.

In terms of pre-charging, the detection circuit 150 can be configured to compare the first voltage V1 of the first input terminal Inp with a pre-charge starting voltage, and correspondingly generate a detection result signal S1. Wherein, in response to the first voltage V1 being higher than the pre-charge starting voltage, the detection result signal S1 is used to control the pre-charge switch SWp to be turned on. In response to the first voltage V1 being less than or equal to the pre-charge start voltage, the detection result signal S1 is used to control the pre-charge switch to turn off SWp.

On the other hand, the detection circuit 150 is further configured to detect whether the operating state of the motor driving system 1 is in the non-driving mode, and whether the first voltage V1 decreases with time. In response to detecting that the operating state is in the non-driving mode and the first voltage V1 decreases with time, output the discharge instruction signal S2 for performing the discharge process on the capacitor C1, and stop until it is detected that the first voltage no longer decreases with time Output discharge indicator signal S2.

The delay circuit 151 is disposed between the detection circuit 150 and the precharge switch SWp, and is configured to delay the detection result signal S1 by a predetermined delay time T1. The delay circuit 151 can be, for example, an RC circuit, and since the detection result signal S1 can be used to control the conduction of the precharge switch SWp when the first voltage V1 is higher than the precharge start voltage, the delay circuit 151 can delay the low impedance path P1 When on The computer thinks that the capacitor C1 will gain time for charging, and the charged capacitor C1 can avoid the instantaneous large current when the system restarts quickly and cause the system to be damaged.

It should be noted that when the pre-charge switch SWp is turned off, the battery pack 10 will charge the capacitor C1 with a pre-charge current Ipc through the high impedance path P2, and the above-mentioned predetermined delay time T1 needs to be at least greater than the pre-charge current The charging time T2 related to the capacitance value of Ipc and the capacitor C1, where the delay time T1 needs to satisfy: T1>T2=C1*Vbat/Ipc, where Vbat is the voltage provided by the battery pack 10. Therefore, the parameters of each element in the precharge circuit 15 can be designed according to this conditional formula.

Here, further reference may be made to FIG. 3, which is a detailed functional block diagram of the detection circuit and a block diagram of its peripheral circuits according to an embodiment of the present invention. As shown in FIG. 3, the detection circuit 150 may further include a second processing circuit 152, a second voltage detection circuit 153 and a storage unit 154.

Wherein, the second processing circuit 152 can be, for example, a microprocessor or a digital signal processor, and the second voltage detection circuit 153 can be used to obtain the first voltage V1 of the first input terminal In1 and the precharge start voltage Vpc (for example, receiving A reference voltage), and compare the first voltage V1 with the precharge start-up voltage Vpc to correspondingly output the detection result signal S1.

On the other hand, the power control circuit 11 further generates a power state signal S3 according to the turn-on and turn-off of the battery pack 10, and in response to detecting that the operating state is in the non-driving mode, the detection circuit 150, for example, the second processing The circuit 152 is further configured to determine whether the battery pack is on or off according to the power state signal S3. In response to detecting that the battery pack 10 is turned off, the detection circuit 150 (or the second processing circuit 152 therein) outputs a discharge instruction signal S2 to the discharge control circuit 16.

In the embodiment of FIG. 3, the controller area network 14' described above is used as the state detection circuit 14 for obtaining the operating state of the motor drive system 1 and notifying the second processing circuit 152. For example, the controller area network 14' can detect whether the operating state is in a driving mode or a non-driving mode.

Furthermore, the storage unit 154 may be, for example, an electronically-erasable programmable read-only memory (Electrically-Erasable Programmable Read-Only Memory, EEPROM), which stores There are program codes or firmware for implementing various functions of the detection circuit 150, and can be executed by the second processing circuit 152.

Under the above-mentioned structure, the detection circuit 150 can determine whether the battery pack 10 is offline or a part of the batteries by detecting whether the operating state of the motor drive system 1 is in the non-driving mode and whether the first voltage V1 decreases with time. The unit is offline. If it is offline, perform a discharge procedure for the capacitor C1 to make the first voltage V1 lower than the pre-charge start voltage Vpc, or further adjust its discharge time so that the first voltage V1 is lower than the rated value within a rated time Safe voltage.

Please refer to FIG. 1 again, the discharge control circuit 16 may be configured to perform the discharge process according to the discharge instruction signal S2. Specifically, this discharge procedure is suitable for the existing motor drive circuit, which uses the motor M as a load. At the time point when the system is judged to be in the non-driving mode, it is driven in a similar manner to the general drive mode, but with different phases. Angle to drive each phase winding of the motor M so that the rotor of the motor M is stationary without shaking.

In detail, the discharge control circuit 16 can obtain the current operating angle of the motor M through the motor control circuit 13 (for example, the phase current detection circuit 133 and the first processing circuit 130), and then according to the obtained current operating angle, Correct the angle to correct the motor control signal group to drive the motor M to stop and enter the discharge mode.

For example, for a three-phase motor, you can refer to a commonly used six-step square wave drive signal table to determine the current operating angle based on the detected phase currents Iu, Iv, and Iw. The discharge control circuit 16 can modify the motor control signal group with +90 degrees or -90 degrees as the correction angle according to the current operating angle to generate new motor control signals H1, H2, H3, L1, L2, and L3 to drive the motor. M. At this time, since the electromagnetic force of the stator of the motor M is parallel to the direction of the magnetic field of the rotor, the rotor of the motor M can be made to stand still without shaking.

The following will further describe the judgment criterion of the detection circuit 150. In detail, when the detection circuit 150 detects whether the first voltage V1 decreases with time, it can substantially determine the first voltage V1 Whether the decrease rate of the voltage V1 is greater than the first predetermined decrease rate, if so, the first voltage V1 is judged to decrease with time. For example, the first predetermined drop rate may be, for example, -7V/s, but it is only an example, and the present invention is not limited thereto. On the other hand, the detection circuit 150 can also determine whether the rate of decrease of the first voltage V1 is less than the second predetermined rate of decrease, and if so, the first voltage V1 is determined to no longer decrease with time. For example, the second predetermined drop rate may be, for example, -3V/s, but it is only an example, and the present invention is not limited thereto.

Further reference may be made to FIG. 4, which is a graph of the voltage and current versus time of the pre-charge circuit applying the intelligent discharge mechanism according to the embodiment of the present invention, in which the capacitor voltage Vc (that is, the first voltage V1) and the capacitor discharge are shown respectively Current Ic1. As shown in FIG. 4, between time t0 and t1, the capacitor voltage Vc continues to decrease, the detection circuit 150 detects that the operating state of the motor drive system 1 is in the non-driving mode, and the capacitor voltage Vc decreases with time. Therefore, at time t1 starts the discharge mechanism, so that the capacitor discharge current Ic1 rises and the capacitor voltage Vc drops rapidly, in other words, the precharge circuit 15 is forced to initialize.

Further reference may be made to FIG. 5, which is a graph of voltage and current versus time for a pre-charge circuit according to an embodiment of the present invention using a delayed turn-on mechanism, respectively showing the capacitor voltage Vc (that is, the first voltage V1) and the pre-charge switch signal Vgs, detection result signal S1 and capacitor charging current Ic2. As shown in FIG. 4, at time t0, only the first battery cell B1 of the battery pack 10 is turned on. However, the voltage provided by the first battery cell B1 is still higher than the pre-charge start voltage Vpc. At time t1, the second battery unit B1 is powered on. At this time, since the capacitor voltage Vc is higher than the pre-charge start voltage Vpc, the detection result signal S1 can be used to control the pre-charge switch SWp to turn on. However, due to the existence of the delay circuit 151, This makes the turn-on timing of the low-impedance path P1 delay the delay time T1, and therefore obtains the charging time for the capacitor C1, so that before the precharge switch signal Vgs reaches the turn-on point P1, the capacitor C1 has sufficient power, and the charged capacitor C1 can Avoid instantaneous high current when the system restarts quickly and cause system damage.

Further reference may be made to FIG. 6, which is a flow chart of the detection circuit according to an embodiment of the present invention for executing a state detection procedure. In detail, the detection circuit 150 can start the discharge process according to various states of the system. An example is provided below, but the present invention is not limited to this. As shown in Figure 6, the status detection The program includes:

Step S100: Detect whether the motor driving system is in a non-driving mode or a driving mode.

In response to detecting that the motor driving system is in the non-driving mode, step S101 is entered: detecting whether the battery pack is turned off. In response to detecting that the motor driving system is in the driving mode, step S102 is entered: detecting whether an electronic brake command input from the user is received. For example, the detection circuit can receive the electronic brake command input by the user from the aforementioned controller area network 14'.

In response to detecting that the battery pack is turned off in step S101, proceed to step S103: perform a discharge procedure, and then end the process.

In response to detecting that the battery pack is turned on in step S101, proceed to step S104: detecting whether the rate of decrease of the first voltage is greater than 7V/s.

In response to detecting that the rate of decrease of the first voltage is greater than 7V/s in step S104, proceed to step S105: perform a discharge procedure. Then go to step S106: detect whether the rate of decrease of the first voltage is less than 3V/s, if yes, go to step S107 to terminate the discharging process, otherwise, repeat step S105. After step S107, return to step S100.

In response to detecting in step S104 that the rate of decrease of the first voltage is not greater than 7V/s, proceed to step S108: detecting whether a motor lock command input from the user is received. For example, the detection circuit can receive the motor lock command input by the user from the aforementioned controller area network 14'.

Wherein, in response to receiving the motor lock command in step S108, it proceeds to step S109: execute the discharge program, otherwise, it returns to step S100.

After that, proceed from step S109 to step S110: detect whether the rate of decrease of the first voltage is less than 3V/s, if yes, proceed to step S111 to terminate the discharge process, otherwise, repeat step S109. After step S111, return to step S100.

On the other hand, in response to receiving the electronic brake command in step S102, the process proceeds to step S112 to execute the discharge routine, otherwise, it returns to step S100.

After step S112, proceed to step S113: detect whether the rate of decrease of the first voltage is less than 3V/s, if yes, proceed to step S114 to terminate the discharge process, otherwise, repeat step S112. After step S114, return to step S100.

In the above process, whether it is an electronic brake command or a motor lock command, it can be received through the controller area network 14' to execute the discharge process, protect the system from high current impact, and also use the motor drive system The driving mechanism achieves a variety of applications.

[Beneficial effects of the embodiment]

One of the beneficial effects of the present invention is that the motor drive system provided by the present invention has a pre-charging circuit with an intelligent charging and discharging mechanism. In terms of charging, the delay circuit can be used to delay the turn-on timing of the low-impedance path, and the internal capacitor after charging can avoid the instantaneous large current that may cause system damage when the system restarts quickly.

On the other hand, the detection circuit of the pre-charge circuit can simultaneously detect the system status and the battery voltage, and perform the discharge process in the non-driving mode and when the battery voltage continues to decrease, so that the voltage can be lower than the rated safe voltage and the pre-charge starting voltage, and In the discharging process, the drive mechanism of the motor drive system can also be used to achieve a variety of applications.

The content disclosed above is only a preferred and feasible embodiment of the present invention, and does not limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the description and schematic content of the present invention are included in the application of the present invention. Within the scope of the patent.

1: Motor drive system

10: battery pack

11: Power control circuit

12: Inverter circuit

13: Motor control circuit

14: Status detection circuit

15: Precharge circuit

16: discharge control circuit

150: detection circuit

151: Delay circuit

B1: The first battery unit

B2: The second battery unit

C1: Capacitance

H1, H2, H3, L1, L2, L3: Motor control signal

In1: the first input

In2: second input

M: Motor

O1, O2, O3: output terminal

P1: Low impedance path

P2: High impedance path

R1, R2: resistance

S1: Detection result signal

S2: Discharge indicator signal

SW1~SW6: switching element

SWp: pre-charge switch

V1: first voltage

Claims (10)

A motor drive system for driving a motor. The motor drive system includes: a battery pack including a first battery unit and a second battery unit connected in series between a first input terminal and a second input terminal ; A power control circuit, configured to control the battery pack to turn on and off; a capacitor, connected between the first input terminal and the second input terminal; an inverter circuit, connected to the first input terminal and The second input terminal is powered by the battery pack and has a plurality of switching elements bridged to form a plurality of output terminals, wherein the output terminals are respectively connected to a plurality of phase windings of the motor; a motor control circuit is configured to A motor control signal group is generated to control the switching actions of the switching elements, so that each phase winding of the motor is energized to drive the motor; a state detection circuit is configured to detect an operating state of the motor drive system; A pre-charging circuit includes: a high impedance path connected between the second input terminal and the battery pack; a low impedance path connected between the second input terminal and the battery pack, wherein the high impedance path The resistance value of is greater than the resistance value of the low impedance path; a precharge switch is arranged on the low impedance path; a detection circuit is configured to: a first voltage of the first input terminal and a precharge start voltage Compare, and correspondingly generate a detection result signal, wherein, in response to the first voltage being higher than the pre-charge start voltage, the detection result signal is used to control the pre-charge switch to turn on, in response to the first voltage being less than or Equal to the pre-charge start voltage, the detection result signal is used to control the pre-charge switch to turn off; detect whether the operating state is a non-driving mode, and the first voltage Whether to decrease with time, wherein, in response to detecting that the operating state is the non-driving mode and the first voltage decreases with time, output a discharge indicator signal for performing a discharge procedure on the capacitor until the first voltage is detected When a voltage no longer drops with time, stop outputting the discharge indication signal; and a delay circuit is provided between the detection circuit and the precharge switch, and is configured to delay the detection result signal by a predetermined delay time; And a discharge control circuit configured to execute the discharge procedure according to the discharge instruction signal, including: obtaining a current operating angle of the motor through the motor control circuit; and correcting the motor control by a correction angle according to the current operating angle Signal group to drive the motor to stop and enter a discharge mode. The motor drive system according to claim 1, wherein the power control circuit further generates a power state signal corresponding to the turn-on and turn-off of the battery pack, and the detection circuit is further configured to: respond to detecting the operating state as In the non-driving mode, determine whether the battery pack is on or off according to the power state signal; in response to detecting that the battery pack is off, output the discharge indication signal. According to the motor drive system of claim 2, the detection circuit is further configured to detect whether the first voltage drops over time in response to detecting that the battery pack is turned on. The motor drive system according to claim 3, wherein when the detection circuit is configured to detect whether the first voltage decreases with time, it further determines whether the decrease rate of the first voltage is greater than a first predetermined decrease rate, and if so, Then the first voltage is judged to decrease with time. The motor drive system according to claim 3, wherein the detection circuit is configured to determine whether the first voltage has not fallen over time, and further detects whether the signal is received from A motor lock command input by the user, wherein, in response to receiving the motor lock command, the detection circuit is configured to output the discharge indication signal. The motor drive system according to claim 3, wherein when the detection circuit is configured to detect whether the first voltage decreases with time, it further determines whether the decrease rate of the first voltage is less than a second predetermined decrease rate, and if so, Then the first voltage is judged to no longer decrease with time. The motor drive system according to claim 1, wherein the motor control circuit is further configured to detect a plurality of phase currents of the phase windings of the motor to generate an angle indicating the current operating angle of the motor Information. The motor drive system of claim 1, wherein, in response to detecting that the operating state is not in the non-driving mode, the detection circuit is further configured to detect whether an electronic brake command input from the user is received , If yes, output the discharge indicator signal. The motor drive system according to claim 8, wherein, in response to receiving the electronic brake command input from the user and outputting the discharge indication signal, the detection circuit is further configured to detect whether the first voltage follows When the time drops, in response to detecting that the first voltage no longer drops with time, stop outputting the discharge indication signal. The motor drive system according to claim 1, wherein when the precharge switch is turned off, the battery pack charges the capacitor with a precharge current through the high impedance path, and the predetermined delay time is at least greater than that of the precharge A charging time related to the current and the capacitance value of the capacitor.

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