Motor pre-charging completion judgment circuit and motor pre-charging completion judgment method

Abstract

The present invention belongs to the field of electronic technology, and provides a motor pre-charging completion judgment circuit and a motor pre-charging completion judgment method; the pre-charging completion judgment circuit comprises: a first voltage-dividing module configured to perform voltage-dividing sampling on the voltage of a motor bus and output a first voltage; a second voltage-dividing module configured to perform voltage-dividing sampling on the voltage of a battery bus and output a second voltage; the voltage-dividing ratio of the first voltage-dividing module and the voltage-dividing ratio of the second voltage-dividing module meet a first preset condition; a comparator module configured to generate a charging comparison signal when the first voltage and the second voltage meet a second preset condition; a single-channel digital isolation module configured to convert the charging comparison signal into a driving signal, and the driving signal is used to disconnect the motor pre-charging circuit; the pre-charging completion judgment circuit of the present invention can detect and judge the pre-charging process of the motor without software control, and solves the problem that the circuit structure of the traditional judgment circuit is complex and the manufacturing and application costs are high.

Description

Technical Field

[0001] The present invention belongs to the field of electronic technology, and in particular relates to a motor pre-charging completion judgment circuit and a motor pre-charging completion judgment method. Background Art

[0002] A motor is an electromagnetic device that uses the law of electromagnetic induction to achieve electrical energy conversion or transmission. Since motors have excellent control performance and can realize various circuit functions, they have become an indispensable power component in the field of electronics. During the operation of the motor, technicians need to frequently adjust the on and off of the power supply to control the power start and stop process, so the DC bus of the motor needs to be connected to continuous power to maintain the stable operation of the motor. However, according to the internal structure of the motor controller in traditional technology, there is a large capacitor on the DC bus of the motor. If the motor is connected to the charging power supply at the moment, the voltage between the two plates of the capacitor will not change suddenly, but the current at both ends of the capacitor will change suddenly. At this time, the DC of the motor The capacitor on the bus is equivalent to a short-circuit state, and there will be a short-circuit current of extremely high amplitude on the DC bus. This short-circuit current will seriously damage the physical safety of the capacitor, and even a serious short-circuit current will burn the capacitor, causing serious damage to the safe operation of the motor. Therefore, the technicians use the pre-charging circuit of the motor to suppress the impact of the short-circuit current on the capacitor when the charging power is connected. After the DC bus in the motor is stably connected to the charging power, the charging power is continuously connected through the DC bus of the motor. Therefore, the pre-charging circuit of the motor can prevent the impact current at the moment the charging power is connected to the capacitor from damaging it, ensure the safe and smooth start-up of the motor, and then maintain the physical safety of the motor.

[0003] Conventional technology provides pre-charging protection for the motor controller through a pre-charging circuit. When the motor controller is charged through the pre-charging circuit, it is necessary to switch to the DC bus of the motor for power supply to achieve safe startup and stable operation of the motor. Therefore, when the pre-charging circuit is used to pre-charge the motor at the moment of startup, it is immediately switched to the stable power supply mode of the motor bus after the pre-charging process of the motor is completed to achieve safe switching between the pre-charging mode and the stable power supply mode of the motor DC bus. Then the technician needs to determine when the motor has completed pre-charging. In conventional technology, the pre-charging judgment circuit of the motor mainly adopts the following three technologies: 1. By collecting the DC bus current in the motor controller, when the current of the DC bus is close to the preset saturation value, it is judged that the motor pre-charging is completed; 2. The output voltage of the battery and the voltage of the DC bus of the motor controller are collected respectively. When the voltages of the two tend to be equal, it is judged that the motor pre-charging is completed; 3. The voltage of the DC bus of the motor controller is collected. When the DC bus voltage of the motor controller reaches the preset undervoltage protection point, it is judged that the motor pre-charging is completed.

[0004] However, in the above three methods for judging whether pre-charging is completed, it is necessary to sample the voltage of the motor controller or the voltage of the battery and then perform A / D conversion, and to cooperate with corresponding software to process the current / voltage signal to finally judge whether the pre-charging of the motor is completed. Therefore, the pre-charging completion judgment circuit in the traditional technology not only requires an A / D conversion circuit but also needs to cooperate with software control, the operation is cumbersome, the manufacturing cost of the circuit structure is high, and the judgment error of whether the pre-charging of the motor is completed is large. Summary of the invention

[0005] The present invention provides a motor pre-charging completion judgment circuit and a motor pre-charging completion judgment method, aiming to solve the problems that the motor pre-charging completion judgment circuit in the traditional technology has a complex circuit structure, needs to be combined with software control to detect and judge the motor pre-charging process, has cumbersome operation, has a large error in judging whether the motor pre-charging is completed, and has a high operating cost.

[0006] A first aspect of the present invention provides a motor pre-charging completion judgment circuit, comprising:

[0007] A first voltage dividing module connected to the motor bus and configured to perform voltage division sampling on the voltage of the motor bus and output a first voltage;

[0008] A second voltage dividing module connected to the battery bus and configured to divide the battery bus voltage and sample it to output a second voltage; the voltage dividing ratio of the first voltage dividing module and the voltage dividing ratio of the second voltage dividing module meet a first preset condition, wherein the first preset condition is:

[0009] A / B ≥ C;

[0010] A is the voltage division ratio of the first voltage division module, B is the voltage division ratio of the second voltage division module, and C is between 85% and 100%;

[0011] A comparator module connected to the first voltage dividing module and the second voltage dividing module, and configured to generate a charging comparison signal when the first voltage and the second voltage meet a second preset condition;

[0012] A single-channel digital isolation module connected to the comparator module and configured to convert the charging comparison signal into a driving signal, wherein the driving signal is used to disconnect the pre-charging circuit of the motor.

[0013] A second aspect of the present invention provides a method for determining whether pre-charging of a motor is completed, comprising:

[0014] Perform voltage division sampling on the motor bus voltage to output a first voltage;

[0015] The battery bus voltage is sampled and divided to output a second voltage; wherein the voltage sampling ratio of the motor bus and the voltage sampling ratio of the battery bus meet a first preset condition, and the first preset condition is:

[0016] W / V ≥ Q;

[0017] W is the voltage division sampling ratio of the motor bus voltage, V is the voltage division sampling ratio of the battery bus voltage, and Q is between 85% and 100%;

[0018] When the first voltage and the second voltage meet a second preset condition, a charging comparison signal is generated;

[0019] The charging comparison signal is converted into a driving signal, wherein the driving signal is used to disconnect the pre-charging circuit of the motor.

[0020] In the pre-charging completion judgment circuit of the above-mentioned motor, the voltage of the motor bus and the battery bus voltage can be respectively collected through the first voltage dividing module and the second voltage dividing module to obtain the first voltage and the second voltage; wherein the change of the motor charging energy of the motor controller during the pre-charging process can be obtained through the first voltage and the second voltage; since the voltage dividing ratio of the first voltage dividing module and the voltage dividing ratio of the second voltage dividing module in the present invention meet the first preset condition, the ratio of the motor bus voltage to the battery bus voltage can accurately and quickly judge whether the motor has completed the pre-charging process; when the first voltage and the second voltage meet the second preset condition, the voltage of the motor bus and the battery bus voltage meet the charging completion condition, the motor has completed the pre-charging process, and the comparator module generates a charging comparison signal; the single-channel digital isolation module generates a driving signal according to the charging comparison signal, and the pre-charging circuit of the motor is disconnected in time through the driving signal, so that the motor automatically switches from the pre-charging mode to the stable power supply mode of the DC bus; therefore, the pre-charging completion judgment circuit in this embodiment is The first voltage divider module and the second voltage divider module can sample and divide the voltage of the motor bus and the battery bus without A / D conversion; since there is a specific proportional relationship between the voltage divider ratio of the first voltage divider module and the voltage divider ratio of the second voltage divider module, the present embodiment can directly determine whether the motor has completed the pre-charging process according to the proportional relationship between the voltage of the motor bus and the voltage of the battery bus, without software control, and only needs to detect, judge and generate a drive signal for the pre-charging process of the motor through a hardware circuit structure, which is easy to operate, has a simple circuit structure, and has a low application cost of the pre-charging completion judgment circuit, can accurately judge whether the pre-charging of the motor is completed, and has reliable operation; it effectively solves the problem that the motor pre-charging completion judgment circuit in the traditional technology needs to perform A / D conversion on the voltage / current, and needs to cooperate with software control to detect and judge the pre-charging process of the motor, the manufacturing cost and application cost of the circuit are high, the operation is cumbersome, the judgment accuracy of whether the pre-charging of the motor is completed is low, and the practical value is not high. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the 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 work.

[0022] Figure 1 1 is a schematic diagram of a circuit structure of a pre-charging circuit provided by an embodiment of the present invention;

[0023] Figure 2 It is a module structure diagram of a pre-charging completion judgment circuit provided by an embodiment of the present invention;

[0024] Figure 3 is a circuit structure diagram of a first voltage dividing module and a second voltage dividing module provided in an embodiment of the present invention;

[0025] Figure 4 is a circuit structure diagram of another first voltage dividing module and a second voltage dividing module provided in an embodiment of the present invention;

[0026] Figure 5 is a circuit structure diagram of another first voltage dividing module and a second voltage dividing module provided in an embodiment of the present invention;

[0027] Figure 6 It is a module structure diagram of another pre-charging completion judgment circuit provided by an embodiment of the present invention;

[0028] Figure 7 is a circuit structure diagram of a power isolation module provided by an embodiment of the present invention;

[0029] Figure 8 is a circuit structure diagram of a comparator module provided by an embodiment of the present invention;

[0030] Fig. 9 is a circuit structure diagram of a single-channel digital isolation module provided by an embodiment of the present invention;

[0031] Fig.10 is a module structure diagram of a battery management system provided by an embodiment of the present invention;

[0032] Fig.11 It is a flow chart of an implementation method of a motor pre-charging completion judgment method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] It should be noted first that, according to the internal circuit structure of the motor controller, when the motor controller is connected to the power supply and started, a large peak current will exist on the motor bus. Since the peak current has a large amplitude and a short duration, if the peak current is not processed, the peak current will cause great damage to the operation of the motor controller. For this reason, the traditional technology uses a pre-charging circuit to implement pre-charging protection for the motor to reduce the physical damage caused by the peak current to the motor; for example,

[0035] Figure 1 A conventional motor pre-charging circuit is shown. Figure 1As shown, the pre-charging circuit of the motor has a resistor R0, and the resistor R0 is connected in parallel with the switch K0. When the motor is connected to a three-phase power supply, the three-phase power supply can be filtered through a filter to improve the stability of the motor connected to the power supply. The pre-charging circuit of the motor includes the resistor R0. At the moment when the motor bus is connected to the power supply, the switch K0 is disconnected, the pre-charging circuit is turned on, and the power is output to the motor through the resistor R0. Since the resistor R0 can consume the electric energy in the power supply, the damage to the motor caused by the peak current at the moment when the motor is connected to the power supply is reduced. The negative impact of the peak current on the motor can be weakened by the resistor R0, thereby ensuring the safe starting of the motor. Then, after the pre-charging process of the motor is completed, the switch K0 needs to be closed. The resistor R0 is short-circuited and the pre-charging circuit is disconnected, and then the three-phase power supply can be directly transmitted to the motor controller through the switch K0 to achieve stable power supply to the motor and reduce the loss of electric energy in the transmission process; therefore, during the pre-charging process of the motor, it is necessary to timely determine whether the motor has completed pre-charging. If the motor has completed pre-charging, the motor controller needs to quickly switch to the stable power supply mode of the motor bus. Under the stable power supply mode, the three-phase power supply transmits electric energy to the motor through the switch K0 to drive the motor to a stable operating state; the pre-charging completion judgment circuit in the present invention can directly determine whether the motor has completed the pre-charging process, which is easy to operate and can ensure the safe starting and stable operation of the motor.

[0036] It should be noted that Figure 1 The pre-charging circuit shown is only an exemplary circuit structure. Since the pre-charging circuit is the application object of the pre-charging circuit in the present invention, the pre-charging completion judgment circuit in the present invention can be applied to different motor pre-charging circuits in the art, and is not limited to Figure 1 The circuit structure of the pre-charging circuit shown in the figure can be applied to different types of pre-charging circuits without violating the inventive concept of the present invention, and has a wide range of applications.

[0037] Figure 2 The module structure of the motor pre-charging completion judgment circuit 10 provided in the embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0038] like Figure 2As shown, the pre-charging completion judgment circuit 10 includes: a first voltage dividing module 101, a second voltage dividing module 102, a comparator module 103 and a single-channel digital isolation module 104, wherein the first voltage dividing module 101 is connected to the motor bus 20, wherein the motor bus 20 has the running power of the motor, and the voltage of the motor bus 20 can be divided and sampled by the first voltage dividing module 101 to output a first voltage, and the voltage of the motor bus 20 is the voltage inside the motor. Only when the voltage of the motor bus 20 is within the error range of the rated voltage of the motor bus 20 The motor can maintain a normal operating state only when the voltage of the motor bus 20 exceeds the error range of the rated voltage of the motor bus. If the voltage of the motor bus 20 exceeds the error range of the rated voltage of the motor bus, it means that the input power amplitude of the motor is too large. This abnormal input power will cause great damage to the operation safety of the motor. Therefore, in this embodiment, the first voltage divider module 101 samples the voltage of the motor bus 20 to obtain a first voltage. The actual input power situation of the motor can be obtained through the first voltage. The first voltage divider module 101 can monitor the actual input power change of the motor to ensure the operation safety of the motor.

[0039] The second voltage divider module 102 is connected to the battery bus 30, wherein the battery bus 30 is used as a power supply function device, and high-power electric energy can be provided to the motor through the battery bus 30. The battery bus voltage is collected by the second voltage divider module 102, and the battery bus voltage is divided and sampled and then outputted as a second voltage. The magnitude of the electric energy output by the battery bus 30 can be obtained through the second voltage. Thus, the embodiment can monitor the change of the output power of the battery bus 30 in real time through the second voltage divider module 102; wherein the voltage divider ratio of the first voltage divider module 101 and the voltage divider ratio of the second voltage divider module 102 meet the first preset condition, wherein the first preset condition is:

[0040] A / B≥C (1)

[0041] In the above formula (1), A is the voltage division ratio of the first voltage division module 101, B is the voltage division ratio of the second voltage division module 102, and C is between 85% and 100%; as a preferred embodiment, C is 90%. Therefore, in this embodiment, the voltage division ratio in the first voltage division module 101 and the voltage division ratio in the second voltage division module 102 meet the conditions of the above formula (1). After the pre-charging process of the motor is completed, the voltage of the motor bus 20 sampled by the first voltage division module 101 and the battery bus voltage sampled by the second voltage division module 102 will meet the charging completion condition; and then when the operating parameters of the first voltage division module 101 and the operating parameters of the second voltage division module 102 both meet the above-mentioned specific proportional relationship, the pre-charging completion judgment circuit 10 in this embodiment can judge whether the motor has completed the pre-charging operation according to the ratio of the voltage of the motor bus 20 to the battery bus voltage. The operation is simple and the detection accuracy is extremely high.

[0042] As a preferred embodiment, when C is equal to 90% and the voltage dividing ratio in the first voltage dividing module 101 reaches 90% of the voltage dividing ratio of the second voltage dividing module 102, the ratio between the voltage of the motor bus 20 and the battery bus voltage can be used to determine whether the motor has completed the pre-charging process, thereby improving the detection and judgment accuracy of the pre-charging completion judgment circuit 10 for the motor pre-charging process.

[0043] The comparator module 103 is connected to the first voltage divider module 101 and the second voltage divider module 102. The first voltage divider module 101 transmits the first voltage to the comparator module 103, and the second voltage divider module 102 transmits the second voltage to the comparator module 103. The comparator module 103 has voltage analysis and judgment functions. When the first voltage and the second voltage meet the second preset condition, the motor has completed the pre-charging operation, and the comparator module 103 generates a charging comparison signal; on the contrary, if the first voltage and the second voltage do not meet the second preset condition, the pre-charging completion judgment circuit 10 cannot judge whether the motor has completed the pre-charging process, and the comparator module 103 will not generate a charging comparison signal. There is a one-to-one correspondence between the presence or absence of this charging comparison signal and whether the pre-charging process of the motor is completed; specifically, if the first voltage sampled by the first voltage divider module 101 and the second voltage sampled by the second voltage divider module 102 meet the second preset condition, the pre-charging completion judgment circuit 10 can judge the pre-charging process of the motor, combined with the voltage divider ratio relationship between the first voltage divider module 101 and the second voltage divider module 102 in the above formula (1), when the pre-charging process of the motor is completed, the voltage of the motor bus 20 is within the rated voltage error range of the motor bus 20, and the voltage of the motor bus 20 and the battery bus voltage meet the charging completion condition, wherein the charging completion condition is:

[0044] O / P≥C (2)

[0045] In the above formula (2), O is the voltage of the motor bus 20, and P is the battery bus voltage; therefore, when the first voltage and the second voltage meet the second preset condition, the voltage of the battery bus 20 and the battery bus voltage meet the charging completion condition shown in the above formula (2), and the comparator module 103 generates a charging comparison signal, which can be judged by the pre-charging completion judgment circuit 10: the motor has completed the pre-charging operation.

[0046] The single-channel digital isolation module 104 is connected to the comparator module 103. When the comparator module 103 transmits the charging comparison signal to the single-channel digital isolation module 104, it means that the motor has completed the pre-charging process. The single-channel digital isolation module 104 converts the charging comparison signal into a drive signal, and disconnects the pre-charging circuit of the motor through the drive signal, so that the motor is directly connected to the electric energy through the DC bus to protect the stable working state and avoid the loss of electric energy. The structure of the pre-charging circuit can be referred to by those skilled in the art. Figure 1 In the circuit structure shown, the single-channel digital isolation module 104 has the function of signal function conversion. The driving signal can drive the motor to perform working mode switching operation, so that the motor is converted from the pre-charging mode to the stable power supply mode. The motor can achieve safe startup, and the motor can be directly connected to the power supply in the stable power supply mode, reducing the loss of electric energy, ensuring that the motor can continuously access stable electric energy in the stable power supply mode and maintain a stable and safe operating state.

[0047] exist Figure 2 In the motor pre-charging completion judgment circuit 10 shown in the figure, the pre-charging completion judgment circuit 10 includes 4 circuit modules (a first voltage dividing module 101, a second voltage dividing module 102, a comparator module 103 and a single-channel digital isolation module 104). The pre-charging process of the motor can be detected and judged through these 4 circuit modules. The circuit structure is simple, and in the process of sampling and analyzing the voltage of the motor bus 20 and the battery bus voltage through the pre-charging completion judgment circuit 10, there is no need to perform A / D conversion on the voltage. Since the voltage dividing ratio of the first voltage dividing module 101 and the voltage dividing ratio of the second voltage dividing module 102 meet the conditions in the above formula (1), then the magnitude relationship between the voltage of the motor bus 20 and the battery bus voltage can be used to directly judge whether the motor has completed the pre-charging process. No software control is required, and the internal voltage of each circuit module in the pre-charging completion judgment circuit 10 is used. The circuit structure can accurately judge the pre-charging process of the motor, the operation is simple, the judgment error is small, and the pre-charging completion judgment circuit 10 has a relatively simplified manufacturing cost and application cost, and has a high practical value; when the pre-charging completion judgment circuit 10 detects that the motor has completed the pre-charging process, the single-channel digital isolation module 104 generates a driving signal, and the driving signal can drive the motor to realize the conversion of the working mode. The motor automatically switches from the pre-charging mode to the stable power supply mode to ensure the safe starting and stable operation of the motor, avoid the physical damage to the motor caused by the peak current on the motor bus at the moment of starting the motor, and improve the safety of the motor; thereby effectively solving the problems of complex circuit structure of the pre-charging completion judgment circuit in the traditional technology, high manufacturing cost and application cost, cumbersome operation process, and large errors in the detection and judgment of the pre-charging process of the motor.

[0048] As an optional implementation manner, the second preset condition is:

[0049] S=T (3)

[0050] S is the first voltage, and T is the second voltage; in the comparator module 103, when the first voltage and the second voltage are equal, the proportional relationship between the voltage of the motor bus 20 and the battery bus voltage can be used to determine whether the motor has completed the pre-charging process. The operation is simple, and the pre-charging completion judgment circuit 10 can accurately monitor and judge the pre-charging process of the motor.

[0051] As an optional implementation, Figure 3 The specific circuit structure of the first voltage dividing module 101 and the second voltage dividing module 102 provided in this embodiment is shown. Figure 3 The first voltage-dividing module 101 includes a first voltage-dividing branch 1011, wherein the first voltage-dividing branch 1011 includes at least two resistors connected in series in sequence; wherein each resistor has a resistance voltage-dividing function in the first voltage-dividing branch 1011, and the voltage of the motor bus 20 is sampled by the voltage-dividing sampling resistor in the first voltage-dividing branch 1011 to obtain a first voltage, so as to realize the voltage sampling and monitoring of the motor bus 20; the second voltage-dividing module 102 includes a second voltage-dividing branch 1021, wherein the second voltage-dividing branch 1021 includes at least two resistors connected in series in sequence, and when the second voltage-dividing branch 1021 is connected to the battery bus voltage, the battery bus voltage can be sampled by the voltage-dividing sampling resistor in the second voltage-dividing branch 1021 to obtain a second voltage, thereby realizing the sampling and monitoring of the battery bus voltage.

[0052] like Figure 3 The first end of the first voltage-dividing branch 1011 is connected to the motor bus 20 for accessing the voltage of the motor bus 20; the first end of the second voltage-dividing branch 1021 is connected to the battery bus 30 for accessing the battery bus voltage; and the second end of the first voltage-dividing branch 1011 and the second end of the second voltage-dividing branch 1021 are connected to the first end of the current-limiting resistor RS, and the second end of the current-limiting resistor RS is grounded GND; the current-limiting resistor RS can prevent the current in the branch from being too large, and thus the current-limiting resistor RS can be used in this embodiment to prevent the operating current in the first voltage-dividing branch 1011 and the operating current in the second voltage-dividing branch 1021 from being in an overcurrent state, thereby ensuring the operating safety of the electronic components in the first voltage-dividing branch 1011 and the second voltage-dividing branch 1021, so that the first voltage-dividing module 101 and the second voltage-dividing module 102 can both achieve normal current sampling functions; wherein the first voltage-dividing branch 1011 and the second voltage-dividing branch 1021 meet the following conditions:

[0053] E = D * C (4);

[0054] In the above formula (4), E is the resistance value of the voltage-dividing sampling resistor in the second voltage-dividing branch 1021, and D is the resistance value of the voltage-dividing sampling resistor in the first voltage-dividing branch 1011; when the voltage-dividing sampling resistor in the second voltage-dividing module 102 and the voltage-dividing sampling resistor in the first voltage-dividing module 101 meet the conditions shown in the above formula (4), combined with the above formula Figure 2 In the embodiment, if the first voltage output by the first voltage dividing module 101 and the second voltage output by the second voltage dividing module 102 meet the second preset condition, the comparator module 103 can determine that the motor has completed the pre-charging process.

[0055] Therefore, the first voltage divider module 101 and the second voltage divider module 102 in the present embodiment have an extremely simplified circuit and are easy to implement. A plurality of resistors connected in series can be used to realize voltage division conversion for the motor bus 20 voltage and the battery bus voltage, respectively, so as to realize accurate collection and monitoring of the input power of the motor and the output power of the battery, which is beneficial to reduce the judgment error of the pre-charging completion judgment circuit 10 in the present embodiment for the pre-charging process of the motor and ensure the starting safety of the motor; at the same time, the number of resistors in the first voltage divider module 101 and the number of resistors in the second voltage divider module 102 in the present embodiment can be adjusted arbitrarily according to actual needs, and the compatibility is extremely strong, which effectively simplifies the circuit structure of the pre-charging judgment circuit 10 in the present embodiment, greatly improves the scope of application of the pre-charging completion judgment circuit 10 in the present embodiment, and has higher practical value.

[0056] As a preferred embodiment, Figure 4 Another specific circuit structure of the first voltage dividing module 101 and the second voltage dividing module 102 provided in this embodiment is shown. Figure 4In the above-mentioned first voltage-dividing branch 1011, N resistors are included, and the second voltage-dividing branch 1021 includes N resistors, wherein N is a positive integer greater than or equal to 2; in the first voltage-dividing branch 1011, the first end of the first resistor R21 is the first end of the first voltage-dividing branch 1011, wherein the first end of the first voltage-dividing branch 1011 is used to access the voltage of the motor bus 20, and the second end of the Nth resistor R2N is the second end of the first voltage-dividing branch 1011, then the second end of the Nth resistor R2N is connected to the first end of the current-limiting resistor RS, and the first end of the Nth resistor R2N and the Nth resistor R2N are connected to each other. -1 The second ends of the resistors R2N-1 are connected together to form the signal output terminal OUT1 of the first voltage divider module 101, and the signal output terminal OUT1 of the first voltage divider module 101 is connected to the comparator module 103, then the Nth resistor R2N is the voltage dividing sampling resistor of the first voltage dividing branch 1011; after the first voltage dividing branch 1011 performs voltage dividing sampling on the voltage of the motor bus 20, the first voltage can be output to the comparator module 103 through the signal output terminal OUT1 of the first voltage dividing module 101, and the comparator module 103 can obtain the voltage fluctuation in the motor bus 20 according to the first voltage.

[0057] In the second voltage-dividing branch 1021, the first end of the first resistor R31 is the first end of the second voltage-dividing branch 1021, and the battery bus voltage can be connected through the first end of the first resistor R31; the second end of the Nth resistor R3N is the second end of the second voltage-dividing branch 1021, then the second end of the Nth resistor R3N is connected to the first end of the current-limiting resistor RS, the first end of the Nth resistor R3N and the second end of the N-1th resistor R3N-1 are connected together to form the signal output end OUT2 of the second voltage-dividing module 102, then the Nth resistor R3N is the voltage-dividing sampling resistor of the second voltage-dividing branch 1021, and the signal output end OUT2 of the second voltage-dividing module 102 is connected to the comparator module 103; when the second branch 1021 obtains the second voltage after voltage-dividing sampling of the battery bus voltage, the signal output end OUT2 of the second voltage-dividing module 102 outputs the second voltage to the comparator module 103, and the comparator module 103 can obtain the actual power supply fluctuation of the battery according to the second voltage.

[0058] The first voltage dividing branch 1011 and the second voltage dividing branch 1021 meet the following conditions:

[0059] F=G*C (5)

[0060] H(i)=K(i) (6)

[0061] In the above formula (5) and the above formula (6), F is the resistance value of the Nth resistor R3N in the second voltage-dividing branch 1021, and G is the resistance value of the Nth resistor R2N in the first voltage-dividing branch 1011; i is any positive integer between 1 and N-1, H(i) is the resistance value of the i-th resistor R3i in the second voltage-dividing branch 1021, and K(i) is the resistance value of the i-th resistor R2i in the first voltage-dividing branch 1011; when the above-mentioned first voltage-dividing branch 1011 and the second voltage-dividing branch 1021 meet the conditions of the above-mentioned formula (5) and the formula (6), the ratio of the voltage of the motor bus 20 to the battery bus voltage can accurately detect whether the motor has completed the pre-charging process.

[0062] As a preferred embodiment, Figure 4 As shown, the first voltage-dividing branch 1011 further includes: an ESD diode RE1 and a capacitor RC1, wherein the ESD diode RE1 is connected in parallel with the Nth resistor R2N in the first voltage-dividing branch 1011, and the capacitor RC1 is connected in parallel with the Nth resistor R2N in the first voltage-dividing branch 1011, wherein the ESD diode RE1 has the functions of preventing overvoltage and anti-static. In the embodiment, the combination of the ESD diode RE1 and the capacitor RC1 can prevent the first voltage-dividing branch 1011 from being in an overcurrent state, and avoid the electronic components in the first voltage-dividing branch 1011 from being interfered by the electrostatic discharge in the circuit, thereby ensuring the stable and safe operation of the first voltage-dividing branch 1011; the second voltage-dividing branch 1021 further includes: an ESD diode R E2 and capacitor RC2, wherein the ESD diode RE2 is connected in parallel with the Nth resistor R3N in the second voltage-dividing branch 1021, and the capacitor RC2 is connected in parallel with the Nth resistor R3N in the second voltage-dividing branch 1021. By combining the ESD diode RE2 and the capacitor RC2, the second voltage-dividing branch 1021 can play an anti-overvoltage and anti-static role to prevent the second voltage-dividing branch 1021 from being in an overvoltage / overcurrent operating state, and then the battery bus voltage can be continuously sampled and monitored through the second voltage-dividing branch 1021; when the signal output terminal OUT2 of the second voltage-dividing module 102 outputs the second voltage, the change of the battery output power supply can be obtained through the second voltage to ensure the power supply safety of the motor.

[0063] In order to better illustrate the working principle of the pre-charging completion judgment circuit 10 in this embodiment, the detection and judgment principle of the pre-charging completion judgment circuit 10 for the motor pre-charging process is described below through a specific embodiment. In this example, it is set that the first voltage dividing branch 1011 includes 7 resistors connected in series, and the second voltage dividing branch 1021 includes 7 resistors connected in series. Figure 5The specific circuit structure of the first voltage-dividing branch 1011 and the second voltage-dividing branch 1021 in this example is shown, and C=90% is set. According to the above formulas (1) and (2), if the pre-charging completion judgment circuit 10 has satisfied the pre-charging completion judgment condition, when the amplitude of the voltage of the motor bus 20 reaches 90% of the amplitude of the battery bus voltage, the comparator module 103 can judge that the motor has completed the pre-charging process; and in order to simplify the circuit analysis process, the voltage-dividing effect of the current-limiting resistor RS is ignored in this example. In the circuit calculation process in this example, the resistance value of the current-limiting resistor RS is approximately 0Ω, and the first voltage-dividing branch 1011 and the second voltage-dividing branch 1021 are not in an overcurrent state. The first voltage-dividing branch 1011 and the second voltage-dividing branch 1021 can respectively realize a normal voltage-dividing conversion effect on the voltage; the details are as follows:

[0064] As mentioned above, according to Figure 5 Specific circuits of the first voltage-dividing branch 1011 and the second voltage-dividing branch 1021 shown in ; if in the first voltage-dividing branch 1011, the resistance value of each resistor in the first to sixth resistors is 127KΩ, and the resistance value of the seventh resistor R27 (voltage-dividing sampling resistor) is 5.6KΩ; in the second voltage-dividing branch 1012, the resistance value of each resistor in the first to sixth resistors is also 127KΩ, and the resistance value of the seventh resistor R37 (voltage-dividing sampling resistor) is: 5.6*90%=5.04KΩ, thereby satisfying: the first voltage-dividing branch 1011 The resistance value of the seventh resistor R27 in the second voltage-dividing branch 1021 is 10% greater than the resistance value of the seventh resistor R37 in the second voltage-dividing branch 1021; if the battery bus voltage is sampled through the second voltage-dividing branch 1012 to obtain: the battery bus voltage V1 = 1000, according to Ohm's law, in the second voltage-dividing branch 1012, the voltage obtained by the seventh resistor is: V2 = (1000*5.04) / (127*6+5.04) = 6.57V, then after the battery bus voltage is sampled through the second voltage-dividing branch 1021, the second voltage is 6.57V; refer to the above Figure 2In the embodiment, if the pre-charging process of the motor is to be determined by formula (1) to formula (3), the first voltage and the second voltage must be equal. Then, after the first voltage-dividing branch 1011 divides the voltage of the motor bus 20, the first voltage V3 obtained must also be equal to 6.57V. Then, according to the series connection form of the 7 resistors in the first voltage-dividing branch 1011, the voltage V4 of the motor bus 20 is 6.57 / (5.6 / (127*6+5.6))=900.56V. Therefore, the voltage V4 of the motor bus 20 sampled by the first voltage-dividing branch 1011 is 900.56V. Then, the voltage V4 of the motor bus 20 and the voltage V3 of the motor bus 20 are equal. The ratio of the bus voltage V1 is: V4 / V1=900.56 / 1000=90.056%>90%; therefore, in this embodiment, the amplitudes of the voltage V4 of the motor bus 20 and the motor bus voltage V1 have satisfied the condition of the above formula (2), and the motor has been pre-charged; the comparator module 103 generates a charging comparison signal, which can indirectly drive the motor to take the working mode switching operation through the charging comparison signal, the pre-charging circuit is disconnected, and the motor automatically switches from the pre-charging starting mode to the stable working mode to achieve safe and stable operation of the motor and avoid physical damage to the motor caused by the peak current during the starting process.

[0065] It can be known from the above examples that the pre-charging completion judgment circuit 10 in this embodiment can respectively perform voltage division sampling on the voltage of the motor bus 20 and the battery bus voltage through the first voltage division module 101 and the second voltage division module 102. Since the resistance values ​​between the voltage division sampling resistor of the first voltage division module 101 and the voltage division sampling resistor of the second voltage division module 102 satisfy a specific proportional relationship, then whether the motor has completed the pre-charging process is judged according to the amplitude ratio of the voltage of the motor bus 20 and the battery bus voltage. The operation is simple and the circuit structure is simple. During the sampling and conversion process of the voltage, no software operation is required, and no A / D conversion of the voltage is required. Furthermore, the present embodiment can accurately monitor and judge the pre-charging process of the motor by virtue of the circuit structure of the pre-charging completion judgment circuit 10 itself. The monitoring accuracy is extremely high, which ensures the safe starting and stable operation of the motor, greatly reduces the manufacturing cost and application cost of the pre-charging completion judgment circuit 10, and is extremely practical.

[0066] As a specific implementation method, Figure 6 is another module structure of the pre-charge completion judgment circuit 10 provided in this embodiment. Figure 2 The module structure of the pre-charge completion judgment circuit 10 shown in FIG. Figure 6The pre-charge completion judgment circuit 10 further includes: a first power supply TES, a second power supply VAUX and a power isolation module 601, wherein the first power supply TES is connected to the comparator module 103 and the single-channel digital isolation module 104, and the electric energy can be transmitted to the comparator module 103 and the single-channel digital isolation module 104 through the first power supply TES, so that the comparator module 103 and the single-channel digital isolation module 104 can maintain a normal working state; the second power supply VAUX is connected to the single-channel digital isolation module 104, and the electric energy is output to the single-channel digital isolation module 104 through the second power supply VAUX; in this embodiment, the first power supply TES and the second power supply VAUX can both provide electric energy to drive the electronic components in the pre-charge completion judgment circuit 10 to be in a state of Normal working state; however, since the operating parameters of the first power supply TES and the operating parameters of the second power supply VAUX are different, and the electric energy output by the two is incompatible, the first power supply TES and the second power supply VAUX cannot power the electronic components at the same time; the power isolation module 601 is connected between the first power supply TES and the second power supply VAUX, and the power isolation module 601 has the function of power conversion. Therefore, the power isolation module 601 can convert the electric energy in the first power supply TES and the electric energy in the second power supply VAUX, so that the first power supply TES and the second power supply VAUX can be compatible and coexist in the pre-charging completion judgment circuit, so as to ensure the safe power supply of each circuit module and realize accurate pre-charging judgment operation for the motor.

[0067] As an optional implementation, Figure 7 The circuit structure of the power isolation module 601 provided in this embodiment is as follows: Figure 7 As shown, the power isolation module 601 includes: a DC converter P1, a first capacitor C1, a first inductor L1, a second capacitor C2 and a first diode D1; wherein, the first end of the first capacitor C1 and the positive power output electrode VOUT+ of the DC converter P1 are connected to the first power supply TES, the second end of the first capacitor C1 and the negative power output electrode VOUT- of the DC converter P1 are connected to the ground GND, the first end of the first inductor L1 is connected to the positive power input electrode VIN+ of the DC converter P1, the second end of the first inductor L1, the first end of the second capacitor C2 and the cathode of the first diode D1 are connected to the second power supply VAUX, and the anode of the first diode D1, the second end of the second capacitor C2 and the negative power input electrode VIN- of the DC converter P1 are connected to the ground GND.

[0068] As an optional implementation, the model of the DC converter P1 is: ROE0505S; in this embodiment, the first power supply TES is connected to the second power supply VAUX through the DC converter P1, and then the DC converter P1 can realize the conversion of the two power supplies; thus, the first power supply TES and the second power supply VAUX can simultaneously provide stable power to the electronic components in the pre-charging completion judgment circuit 10 to ensure that the pre-charging completion judgment circuit 10 can be in a normal working state.

[0069] As an optional implementation, Figure 8 is the circuit structure of the comparator module 103 provided in this embodiment, such as Figure 8 As shown, the comparator module 103 includes: a comparator chip U1 and a first resistor R1; the positive signal input pin IN+ of the comparator chip U1 is connected to the second voltage divider module 102, the reverse signal input pin IN- of the comparator chip U1 is connected to the first voltage divider module 101, the ground pin of the comparator chip U1 is grounded GND, the power pin of the comparator chip U1 and the first end of the first resistor R1 are connected to the first power supply TES, and stable power can be provided to the comparator chip U1 through the first power supply TES; the second end of the first resistor R1 and the signal output end OUT of the comparator chip U1 are connected to the single-channel digital isolation module 104.

[0070] As an optional implementation, the comparator chip U1 is of model TL331; according to Figure 8 The circuit structure of the comparator module 103 shown is that when the first voltage-dividing module 101 performs voltage-dividing sampling on the voltage of the motor bus 20 to obtain a first voltage, and the second voltage-dividing module 102 performs voltage-dividing sampling on the battery bus voltage to obtain a second voltage, the comparator chip U1 is connected to the first voltage through the reverse signal input pin IN-, and the comparator chip U1 is connected to the second voltage through the forward signal input pin IN+; and the comparator chip U1 can obtain, based on the first voltage and the second voltage: the change of the power supply connected to the motor bus 20 and the power supply output by the battery bus 30; when the motor completes the pre-charging operation, the signal output terminal OUT of the comparator chip U1 outputs the charging comparison signal to the single-channel digital isolation module 104 to drive the motor to achieve the switching of the working mode; and thus the comparator chip U1 in this embodiment has a relatively simplified circuit structure, which can accurately judge the motor pre-charging process.

[0071] As an optional implementation, Fig. 9 The circuit structure of the single-channel digital isolation module 104 provided in this embodiment is as follows: Fig. 9As shown, the single-channel digital isolation module 104 includes: a digital isolation chip U2, a third capacitor C3 and a fourth capacitor C4; wherein, the first end of the third capacitor C3 and the first power pin VS of the digital isolation chip U2 are connected to the first power supply TES, the second end of the third capacitor C3 and the first ground pin VS of the digital isolation chip U2 are connected to the ground GND, the first end of the fourth capacitor C4 and the second power pin VDD1 of the digital isolation chip U2 are connected to the second power supply VAUX, the second end of the fourth capacitor C4 and the second ground pin GND1 of the digital isolation chip U2 are connected to the ground GND, the signal input pin SDA2 of the digital isolation chip U2 is connected to the comparator module 103, the signal output pin SDA1 of the digital isolation chip U2 is the signal output end of the single-channel digital isolation module 104, and the signal output end of the single-channel digital isolation module 104 is used to output a driving signal; wherein in this embodiment, the first power supply TES and the second power supply VAUX can simultaneously output stable electric energy to the digital isolation chip U2, thereby enabling the digital isolation chip U2 to realize the corresponding circuit function.

[0072] As an optional implementation, the model of the above-mentioned digital isolation chip U2 is: ADUM1250; the digital isolation chip U2 can realize digital isolation between the pre-charging completion judgment circuit 10 and the motor to ensure the working safety of the pre-charging completion judgment circuit 10; if the pre-charging completion judgment circuit 10 detects that the motor has completed the pre-charging process, the comparator module 103 outputs the charging comparison signal to the signal input pin SDA2 of the digital isolation chip U2, wherein the digital isolation chip U2 can realize the signal function conversion operation for the charging comparison signal, and the driving signal output by the signal output pin SDA1 of the digital isolation chip U2 can drive the motor to adopt the working mode switching operation, so that the motor enters the stable working mode, and the motor is continuously connected to stable power to maintain normal operation.

[0073] As an optional implementation, the single-channel digital isolation module 104 is a photoelectric coupler; the charging comparison signal can be converted through the photoelectric coupler to realize the signal conversion and transmission function of the pre-charging completion judgment circuit 10. When the pre-charging completion judgment circuit 10 detects that the motor has been pre-charged, the photoelectric coupler can quickly output a drive signal to disconnect the pre-charging circuit of the motor to ensure the safe operation of the motor; therefore, the single-channel digital isolation module 104 in this embodiment has an extremely simplified circuit structure, which is beneficial to reducing the manufacturing cost and application cost of the pre-charging completion judgment circuit 10 in this embodiment.

[0074] Fig.10 The module structure of the battery management system (BMS) 100 provided in this embodiment is as follows: Fig.10As shown, the battery management system 100 includes the motor pre-charging completion judgment circuit 10 as described above; Figures 1 to 9 The embodiment of the present invention is that the pre-charging completion judgment circuit 10 in the present embodiment has a simplified telephone structure, and can detect and judge the pre-charging process of the motor without software operation and A / D conversion of the voltage. It is easy to operate and has strong practicality, and overcomes the shortcomings of the cumbersome operation steps of the motor pre-charging completion judgment method in the traditional technology; thus, the battery management system 100 in the present embodiment can monitor the pre-charging process of the motor in real time, and estimate the state of the power supply of the battery, so as to ensure the safe start-up and stable operation of the motor; through the battery management system 100, the damage to the physical safety of the motor caused by the peak current at the moment of connecting to the power supply can be prevented, which greatly maintains the stable operation of the motor in the present embodiment; at the same time, the above-mentioned battery management system 100 has a low application cost and high practical value, and can be applied to various industrial fields, greatly improving the safety of the motor.

[0075] Fig.11 This is the implementation process of the method for determining the completion of pre-charging of the motor provided in this embodiment, such as Fig.11 As shown, the pre-charging completion judgment method includes the following steps:

[0076] Step S1101: divide and sample the voltage of the motor bus to output a first voltage.

[0077] Step S1102: perform voltage division sampling on the battery bus voltage to output a second voltage; wherein the voltage division sampling ratio of the motor bus and the voltage division sampling ratio of the battery bus meet a first preset condition, wherein the first preset condition is:

[0078] W / V≥Q (7)

[0079] In the above formula (7), W is the voltage division sampling ratio of the motor bus 20 voltage, V is the voltage division sampling ratio of the battery bus voltage, and Q is between 85% and 100%.

[0080] Step S1103: generating a charging comparison signal when the first voltage and the second voltage meet a second preset condition;

[0081] Step S1104: converting the charging comparison signal into a driving signal, wherein the driving signal is used to disconnect the pre-charging circuit of the motor.

[0082] It should be noted that the pre-charging completion judgment method in this embodiment is the same as Figure 2 Therefore, for the embodiments of each step of the pre-charge completion judgment method in this embodiment, please refer to the above Figure 2 The embodiments of the present invention will not be described in detail here.

[0083] Therefore, in this embodiment, the pre-charging process of the motor can be detected and judged through the pre-charging completion judgment method to avoid damage to the physical safety of the motor caused by the peak current at the moment the power is turned on; and after the motor completes the pre-charging operation, the motor can automatically switch the working mode through the driving signal, and the motor is directly connected to the power supply in the stable working mode to maintain a normal working state, which greatly improves the safety of the starting and stable operation of the motor in this embodiment and ensures the physical safety of the motor; it overcomes the shortcomings of the traditional pre-charging completion judgment method in the traditional technology, which is complicated to operate and needs to be combined with software control to determine whether the motor has completed the pre-charging process, thereby resulting in a high application cost of the traditional pre-charging completion judgment method.

[0084] It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity from another entity, and do not necessarily require or imply any such actual relationship or order between these entities. Moreover, the terms "include", "comprise" or any other variants are intended to cover non-exclusive inclusion, so that the elements inherent to the product or structure including a series of elements. In the absence of further restrictions, the elements defined by the statement "include..." or "comprises..." do not exclude the existence of additional elements in the process, method, article or terminal device including the elements. In addition, in this article, "greater than", "less than", "exceed" and the like are understood to exclude the number itself; "above", "below", "within" and the like are understood to include the number itself.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A motor pre-charging completion judgment circuit, characterized in that: include: A first voltage dividing module connected to the motor bus and configured to perform voltage division sampling on the voltage of the motor bus and output a first voltage; A second voltage dividing module connected to the battery bus and configured to divide the battery bus voltage and sample it to output a second voltage; the voltage dividing ratio of the first voltage dividing module and the voltage dividing ratio of the second voltage dividing module meet a first preset condition, wherein the first preset condition is: A / B ≥ C; A is the voltage division ratio of the first voltage division module, B is the voltage division ratio of the second voltage division module, and C is between 85% and 100%; A comparator module connected to the first voltage dividing module and the second voltage dividing module, and configured to generate a charging comparison signal when the first voltage and the second voltage meet a second preset condition; A single-channel digital isolation module connected to the comparator module and configured to convert the charging comparison signal into a driving signal, wherein the driving signal is used to disconnect the pre-charging circuit of the motor; The second preset condition is: S=T; The S is the first voltage, and the T is the second voltage; The first voltage-dividing module comprises a first voltage-dividing branch, wherein the first voltage-dividing branch comprises at least two resistors connected in series in sequence; the second voltage-dividing module comprises a second voltage-dividing branch, wherein the second voltage-dividing branch comprises at least two resistors connected in series in sequence; Wherein, the first end of the first voltage-dividing branch is connected to the motor bus, the first end of the second voltage-dividing branch is connected to the battery bus, the second end of the first voltage-dividing branch and the second end of the second voltage-dividing branch are connected to the first end of the current-limiting resistor, and the second end of the current-limiting resistor is grounded; The first voltage dividing branch and the second voltage dividing branch meet the following conditions: E=D*C; The E is the resistance value of the voltage-dividing sampling resistor in the second voltage-dividing branch, and the D is the resistance value of the voltage-dividing sampling resistor in the first voltage-dividing branch; The first voltage dividing branch includes N resistors, and the second voltage dividing branch includes N resistors, where N is a positive integer greater than or equal to 2; In the first voltage-dividing branch, the first end of the first resistor is the first end of the first voltage-dividing branch, the second end of the Nth resistor is the second end of the first voltage-dividing branch, the first end of the Nth resistor and the second end of the N-1th resistor are connected together to form a signal output end of the first voltage-dividing module, and the signal output end of the first voltage-dividing module is connected to the comparator module; In the second voltage-dividing branch, the first end of the first resistor is the first end of the second voltage-dividing branch, the second end of the Nth resistor is the second end of the second voltage-dividing branch, the first end of the Nth resistor and the second end of the N-1th resistor are connected together to form a signal output end of the second voltage-dividing module, and the signal output end of the second voltage-dividing module is connected to the comparator module; The first voltage dividing branch and the second voltage dividing branch meet the following conditions: F=G*C; H(i)=K(i); F is the resistance value of the Nth resistor in the second voltage-dividing branch, G is the resistance value of the Nth resistor in the first voltage-dividing branch; i is any positive integer between 1 and N-1, H(i) is the resistance value of the i-th resistor in the second voltage-dividing branch, and K(i) is the resistance value of the i-th resistor in the first voltage-dividing branch; The single-channel digital isolation module includes: a digital isolation chip, a third capacitor and a fourth capacitor; Among them, the first end of the third capacitor and the first power pin of the digital isolation chip are connected to the first power supply, the second end of the third capacitor and the first ground pin of the digital isolation chip are connected to the ground, the first end of the fourth capacitor and the second power pin of the digital isolation chip are connected to the second power supply, the second end of the fourth capacitor and the second ground pin of the digital isolation chip are connected to the ground, the signal input pin of the digital isolation chip is connected to the comparator module, and the signal output pin of the digital isolation chip is used to output the drive signal.

2. The precharge completion judgment circuit according to claim 1, characterized in that: Also includes: a first power supply connected to the comparator module and the single-channel digital isolation module, a second power supply connected to the single-channel digital isolation module, and A power isolation module is connected between the first power supply and the second power supply and is configured to perform power conversion.

3. The precharge completion judgment circuit according to claim 2, characterized in that: The power isolation module includes: a DC converter, a first capacitor, a first inductor, a second capacitor and a first diode; The first end of the first capacitor and the positive electrode of the power output of the DC converter are connected to the first power supply, the second end of the first capacitor and the negative electrode of the power output of the DC converter are connected to the ground, the first end of the first inductor is connected to the positive electrode of the power input of the DC converter, the second end of the first inductor, the first end of the second capacitor and the cathode of the first diode are connected to the second power supply, and the anode of the first diode, the second end of the second capacitor and the negative electrode of the power input of the DC converter are connected to the ground.

4. The precharge completion judgment circuit according to claim 2, characterized in that: The comparator module includes: a comparator chip and a first resistor; The positive signal input pin of the comparator chip is connected to the first voltage divider module, the reverse signal input pin of the comparator chip is connected to the second voltage divider module, the ground pin of the comparator chip is grounded, the power pin of the comparator chip and the first end of the first resistor are connected to the first power supply, and the second end of the first resistor and the signal output end of the comparator chip are connected to the single-channel digital isolation module.

5. The precharge completion judgment circuit according to claim 2, characterized in that: The single-channel digital isolation module is a photoelectric coupler.

6. A method for determining the completion of pre-charging of a motor based on the motor pre-charging completion determination circuit according to any one of claims 1 to 5, characterized in that: include: Perform voltage division sampling on the motor bus voltage to output a first voltage; Perform voltage division sampling on the battery bus voltage to output a second voltage; The voltage division sampling ratio of the motor bus and the voltage division sampling ratio of the battery bus meet a first preset condition, and the first preset condition is: W / V ≥ Q; W is the voltage division sampling ratio of the motor bus voltage, V is the voltage division sampling ratio of the battery bus voltage, and Q is between 85% and 100%; When the first voltage and the second voltage meet a second preset condition, a charging comparison signal is generated; The charging comparison signal is converted into a driving signal, wherein the driving signal is used to disconnect the pre-charging circuit of the motor.

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