CN204095556U - A kind of drive system of electric automobile trouble diagnosing Centralized Controller - Google Patents

Abstract

The utility model discloses a centralized controller for fault diagnosis of an electric vehicle drive system, comprising (1) a left front/right front/left rear/right rear wheel drive controller, embedded with a main control module, a signal acquisition and correction module, and a Hall signal solution module, power drive module, wheel speed estimation module, power inverter switch breakdown fault diagnosis module, main and auxiliary Hall signal redundancy verification module and main and auxiliary Hall signal rule sequence verification module; (2) complete wheel speed Comparison module; based on the principle of signal characteristic analysis, the utility model proposes an on-board diagnosis method for comparing the conduction phase current and the ground current for the breakdown fault of the power inverter switch; for the hub motor Hall sensor failure fault, a main and auxiliary Hall signal redundancy check, main and auxiliary Hall signal rule sequence check and complete wheel speed comparison combined on-board diagnosis and vehicle diagnosis; using the above methods can greatly improve the reliability of the electric vehicle drive system sex.

Description

A centralized controller for fault diagnosis of electric vehicle drive system

technical field

The utility model relates to the field of diagnosis and control of electric vehicles, in particular to a centralized controller for fault diagnosis of an electric vehicle driving system.

Background technique

Electric vehicles, known as green and environment-friendly vehicles, have received extensive attention because of their advantages such as zero-emission pollution and saving oil resources. Electric vehicles have four key technologies: battery technology, drive control technology, vehicle technology and energy management technology. As the core part of drive control technology, its excellent performance directly affects the safety performance of electric vehicles. As we all know, due to the influence of factors such as frequent loading and harsh working environment in its application, the failure of electric vehicle drive system is inevitable.

At present, the fault diagnosis methods of electric vehicle drive system can be divided into two types: on-board diagnosis (On-board Diagnostic) and vehicle diagnosis (Vehicle Diagnostic). The principle of on-board diagnosis is: when the electric vehicle is running normally, the voltage values of the input and output signals of its driving system have a certain range of variation. If it does not disappear within a certain period of time, it can be judged that there is a fault in the drive system, and the fault is stored in the internal RAM in the form of code, and at the same time, the fault indicator light on the instrument panel is lit to remind the driver. The principle of vehicle diagnosis is: the driving system sends its operation information to the vehicle controller through the vehicle bus, and then judges whether the operation parameter values of the operation information are within the corresponding parameter value range. If so, it indicates that the operation information is normal; otherwise, Indicates that there is abnormal operation information that is not within the corresponding parameter value range, and the local fault diagnosis database is queried according to the abnormal operation information, and the fault information corresponding to the abnormal operation information is read from the fault diagnosis database.

The above-mentioned fault diagnosis method has the following problems:

1. Although the on-board diagnosis can quickly and accurately diagnose the faults of the electric vehicle drive system, it cannot diagnose the breakdown faults of hardware circuits such as the inverter circuit in the power drive module.

2. The vehicle diagnosis is aimed at multiple electronic control systems for fault diagnosis, and the drive system is only one of them. Its operation information is transmitted through the vehicle bus, which will inevitably occupy a large amount of bus time, indirectly prolonging the time for fault diagnosis and increasing the risk of occurrence. The probability.

Contents of the invention

The technical problem to be solved by the utility model is to overcome the problems existing in the prior art, and provide a centralized controller for fault diagnosis of the drive system of electric vehicles, which adopts a fault diagnosis method based on signal characteristic analysis, and integrates on-board diagnosis technology and vehicle diagnosis technology Combination, on the premise of ensuring good loading characteristics and braking characteristics, aims to improve the reliability of the electric vehicle drive system.

The utility model provides a centralized controller for fault diagnosis of an electric vehicle drive system, comprising: a main control module 5, a signal acquisition and correction module 6, a Hall signal calculation module 7, a power drive module 8, a wheel speed estimation module 9, a power inverter The variable switch breakdown fault diagnosis module 10, the main and auxiliary Hall signal redundancy verification module 11, the main and auxiliary Hall signal rule sequence verification module 12, and the complete wheel speed comparison module 13.

Among them, main control module 5, signal acquisition and correction module 6, Hall signal calculation module 7, power drive module 8, wheel speed estimation module 9, power inverter switch breakdown fault diagnosis module 10, main and auxiliary Hall signal redundancy The verification module 11 and the main and auxiliary Hall signal rule sequence verification module 12 are embedded in the left front/right front/left rear/right rear wheel drive controller; the whole wheel speed comparison module receives the left front/right front/left rear /Right rear wheel speed, and compare the wheel speed in the vehicle controller.

The main control module 5 is embedded with a main control chip and its minimum circuit. The main control chip adopts a digital signal processor DSP TMS320F2812 from Texas Instruments.

The signal acquisition and correction module 6 is embedded with a bus voltage acquisition port, a current acquisition port, and a correction voltage acquisition port, and corrects the AD conversion error caused by the zero drift of the main control chip through correction processing.

Hall signal calculation module 7, calculates the Hall signal into the control register value of the main control chip comparison mode, refers to the commutation phase sequence of the in-wheel motor to make it output the corresponding PWM drive signal, and sends the collected main and auxiliary Hall signals To the main and auxiliary Hall signal redundancy verification module and the main and auxiliary Hall signal rule sequence verification module.

The power drive module 8 is embedded with a drive circuit and a power inverter circuit. A current sensor is added to the ground terminal of the power inverter circuit and the phase terminal of the hub motor, and the collected ground current signal and phase current signal are sent to the power inverter Switch breakdown fault diagnosis module.

The wheel speed estimation module 9, the main control module 5 triggers the capture interruption of the main control chip through the high and low level changes of the hub motor Hall signal, estimates the wheel speed of the hub motor by recording the interval between two adjacent interruptions, and The wheel speed value is sent to the whole wheel speed comparison module.

The power inverter switch breakdown fault diagnosis module 10, the main control module 5 diagnoses the fault of the power inverter circuit of the left front/right front/left rear/right rear wheel drive controller by comparing whether the current entering the ground and the conduction phase current of the in-wheel motor are equal Power inverter switch breakdown fault. Since the conduction phase of the motor and the ground form the same circuit, the conduction phase current and the ground circuit must be equal; on the contrary, if a power switch of the power inverter circuit is broken down, it will inevitably lead to a short circuit in the corresponding phase of the hub motor. The phase current is zero, obviously the ground current is not zero.

The main and auxiliary Hall signal redundancy verification module 11, the main control module 5 performs signal redundancy verification through the two sets of Hall sensors that come with the hub motor to diagnose whether the Hall sensor of the left front/right front/left rear/right rear hub motor invalidated.

The main and auxiliary Hall signal rule sequence verification module 12, the change rule of the Hall signal of the hub motor in adjacent commutation cycles is fixed, and the main control module 5 can diagnose left front/right front/left rear by using this fixed rule /Whether the Hall sensor of the right rear hub motor fails.

The whole wheel speed comparison module 13 receives the estimated wheel speeds of the left front/right front/left rear/right rear hub motors from the wheel speed estimation module through the vehicle-mounted bus. If the relative error of the estimated wheel speed value of a certain hub motor exceeds the threshold, It means that the corresponding wheel hub motor Hall sensor fails.

Compared with the prior art, the beneficial effects of the utility model are:

1. The AD correction method is used to solve the problem of the reduction of AD conversion accuracy caused by the zero drift of the main control chip, which makes the electric vehicle drive system more reliable and more applicable.

2. The breakdown fault of the power inverter switch of the power inverter circuit is diagnosed and located by comparing the conduction phase current and the ground current. The diagnosis method is simple in principle and easy to implement.

3. The failure diagnosis mode of the wheel hub motor Hall sensor combined with on-board diagnosis and vehicle diagnosis is adopted, which greatly improves the accuracy of its fault diagnosis.

Description of drawings:

Fig. 1 is a structural block diagram of the utility model.

Fig. 2 is a block diagram of the correction processing method of the present invention.

Fig. 3 is a schematic diagram of the Hall signal of the present invention.

Fig. 4 is a structural block diagram of the power inverter circuit of the present invention.

Fig. 5 is a flow chart of the Hall signal solving program of the present invention.

Fig. 6 is a flow chart of the power inverter switch breakdown fault diagnosis program of the present invention.

Fig. 7 is a flow chart of the main and auxiliary Hall signal rule sequence verification program of the present invention.

Fig. 8 is a flow chart of the wheel speed estimation program of the present invention.

Detailed ways:

The specific embodiment of the utility model is described below in conjunction with accompanying drawing.

Fig. 1 shows a structural block diagram of the utility model, including: main control module 5, signal acquisition and correction module 6, Hall signal calculation module 7, power drive module 8, wheel speed estimation module 9, power inverter switch breakdown fault diagnosis Module 10, main and auxiliary Hall signal redundancy verification module 11, main and auxiliary Hall signal rule sequence verification module 12, complete wheel speed comparison module 13.

Among them, main control module 5, signal acquisition and correction module 6, Hall signal calculation module 7, power drive module 8, wheel speed estimation module 9, power inverter switch breakdown fault diagnosis module 10, main and auxiliary Hall signal redundancy The verification module 11 and the main and auxiliary Hall signal rule sequence verification module 12 are embedded in the left front/right front/left rear/right rear wheel drive controller; the whole wheel speed comparison module receives the left front/right front/left rear /Right rear wheel speed, and compare the wheel speed in the vehicle controller.

The main control module 5 adopts a digital signal processor TMS320F2812 produced by Texas Instruments as the main control chip. This processor has a single-cycle 32×32-bit multiplication and accumulation function, can complete 64-bit data processing, and can easily realize software upgrades. In addition, it also includes a wealth of peripheral units: 12-bit high-precision AD converter, event manager for motor control, enhanced bus controller and other functional modules. Due to flexible control and strong anti-interference ability, it is very suitable for hub motor control system.

The signal acquisition and correction module 6 is embedded with a bus voltage acquisition port, a current acquisition port, and a reference voltage acquisition port, wherein the bus voltage signal is input to the isolation amplifier ACPL-782T through an external resistor and then converted into a single-ended signal proportional to the bus voltage; The sensor uses ACS755LCB-050; all external acquisition signals are input through the above interfaces, connected to the ADINA1~ADINA7 pins of the main control chip, and then the AD conversion is corrected by the analog and digital quantities of the reference voltage (1.8V and 2.5V) The offset error and gain error caused by the zero drift of the main control chip in the process.

The Hall signal calculation module 7 is embedded with main and auxiliary Hall signal acquisition ports. The main and auxiliary Hall signals are connected to the CAP1-CAP6 pins of the main control chip after being RC filtered and reversed twice. The main control chip resolves the main and auxiliary Hall signals into the control register value of the comparison mode of the main control chip, refers to the commutation phase sequence of the in-wheel motor, and outputs a PWM signal corresponding to the Hall signal to drive the power drive module.

The power drive module 8 is embedded with a drive circuit and a power inverter circuit. The PWM drive signal output by the main control chip first passes through the bus transceiver 74HC245 to convert the level of the drive signal, improve the load capacity of the drive signal, and isolate the drive module from the main function of the control module. Then, the three high-side switching signals PWM1, PWM3, and PWM5 are respectively connected to the HIN1, HIN2, and HIN3 pins of the driver chip IR2130, and the three low-side switching signals PWM2, PWM4, and PWM6 are respectively connected to the HIN4, HIN5, and pins of the driver chip IR2130. HIN6 pin. After the PWM driving signal passes through the driving chip, its high-side switching signal needs to be boosted through the bootstrap circuit to reach the driving voltage of the power switch of the power inverter module. The PWM modulation method adopts unipolar modulation in which the upper tube is modulated and the lower tube is normally closed. This method has the advantage of small modulation current fluctuations. At the same time, the RC filter circuit can avoid voltage and current surges and suppress interference.

The wheel speed estimation module 9 and the main control module 5 trigger the capture interruption of the main control chip through the high and low level changes of the hub motor Hall signal, and record the interval between two adjacent interruptions, that is, the rotor passes through 1/120 circle (number of pole pairs) For the time of 20), the wheel speed of the in-wheel motor is estimated by the above method, and the estimated wheel speed is sent to the whole wheel speed comparison module.

The power inverter switch breakdown fault diagnosis module 10, the main control module 5 diagnoses the fault of the power inverter circuit of the left front/right front/left rear/right rear wheel drive controller by comparing whether the current entering the ground and the conduction phase current of the in-wheel motor are equal Power inverter switch breakdown fault. Since the conduction phase of the motor and the ground form the same circuit, the conduction phase current and the ground circuit must be equal; on the contrary, if a power switch of the power inverter circuit is broken down, it will inevitably lead to a short circuit in the corresponding phase of the hub motor. The phase current is zero, obviously the ground current is not zero.

The main and auxiliary Hall signal redundancy verification module 11, the main control module 5 performs signal redundancy verification through the two sets of Hall sensors that come with the hub motor to diagnose whether the Hall sensor of the left front/right front/left rear/right rear hub motor invalidated.

The main and auxiliary Hall signal rule sequence verification module 12, the change rule of the Hall signal of the hub motor in adjacent commutation cycles is fixed, and the main control module 5 can diagnose left front/right front/left rear by using this fixed rule /Whether the Hall sensor of the right rear hub motor fails.

The whole wheel speed comparison module 13 receives the estimated wheel speeds of the left front/right front/left rear/right rear hub motors from the wheel speed estimation module through the vehicle-mounted bus. If the relative error of the estimated wheel speed value of a certain hub motor exceeds the threshold, It means that the corresponding wheel hub motor Hall sensor fails.

Fig. 2 shows the flow chart of the correction processing program of the present invention. The following describes the flow chart of the correction processing program in combination with the correction method. The relationship between the input analog voltage of AD conversion and the converted digital quantity is as follows:

V＝(D×3)/4095 (1)

In the above formula, V is the input analog voltage, and D is the converted digital quantity.

The analog voltage converted by formula (1) should be equal to the actual voltage theoretically. However, if the main control chip has zero drift, the analog voltage converted by formula (1) will have a certain error with the actual voltage value, that is, the AD conversion error. The analog voltage (X) converted by formula (1) and the actual voltage (Y) correspondence (i.e. correction equation) is expressed as:

Y＝KX+B (2)

In the formula, K is the gain error coefficient, and B is the offset error coefficient.

Take two correction voltages (1.8V and 2.5V) and convert them into V ₁ and V ₂ through formula (1) after AD conversion, and finally substitute (V ₁ 1.8) and (V ₂ 2.5) into formula (2) to find Get the gain error coefficient (K) and offset error coefficient (B).

K＝(2.5-1.8)/(V ₂ -V ₁ ) (3)

B=(2.5×V ₁ −1.8×V ₂ )/(V ₂ −V ₁ ) (4)

Then, the gain error coefficient and offset error coefficient are substituted into formula (2), so that the bus voltage signal, phase current and ground current signal collected by the signal acquisition module are converted into the analog voltage converted by AD conversion into formula (2), After correction processing, the accurate actual voltage of the above signal can be obtained.

Step S201 inputs two correction voltages, a bus voltage signal, a phase current and a ground current signal.

Step S202 calculates the gain error coefficient, and the calculation formula is shown in formula (3).

Step S203 calculates the offset error coefficient, and the calculation formula is shown in formula (4).

In step S204, the gain error coefficient and the offset error coefficient are substituted to obtain a correction equation, and the calculation formula is shown in formula (2).

In step S205, the bus voltage signal, the phase current and the ground current signal are substituted into the correction equation to obtain an accurate actual voltage after correction.

Fig. 3 shows a schematic diagram of the Hall signal of the present invention. The in-wheel motor has three Hall sensors installed at 60°. The Hall signal is a PWM waveform with a pulse width of 180° electrical angle, a sequential lag of 60°, and a duty cycle of 50%. 1 commutation is performed, and 6 commutations are a commutation cycle. In the in-wheel motor drive mode, the three Hall signals are 001, 000, 100, 110, 111, and 011 in one commutation cycle, and the corresponding in-wheel motor conduction phases are UW, UV, WV, WU, VU, and VW. In the hub motor braking mode, the three Hall signals are 011, 111, 110, 100, 000, and 001 in one commutation cycle, and the corresponding hub motor conduction phases are WU, VU, VW, UW, UV, and WV.

Fig. 4 is a structural block diagram of the power inverter circuit of the present invention. The power inverter circuit is composed of six power inverter switches, the upper bridge arm is composed of power inverter switch 1, power inverter switch 3 and power inverter switch 5, and the lower bridge arm is composed of power inverter switch 2, power inverter switch 4 and power inverter switch 6.

Fig. 5 is a flow chart of the Hall signal solving program of the present invention. The lower 12-bit data of the comparison mode control register of the main control chip represents the output mode of PWM1~PWM6, the binary number 10 represents high effective (modulates the power inverter switch 1/3/5 of the upper bridge arm), and 11 represents forced high (normal Open the power inverter switch 2/4/6 of the lower bridge arm, that is, the PWM modulation mode in which the upper tube modulates the lower tube and normally closes. First, judge the working mode of the controller according to the mode flag bit.

If the mode flag is 1, then enter step S501 driving mode, and execute the calculation of the driving phase sequence:

When the Hall signal is 001, enter step S503, the comparison mode control register value is 0C02 (0000110000000010), and the output control signal PWM1/PWM6 drives the power inverter switch 1/power inverter switch 6.

When the Hall signal is 000, enter step S504, the comparison mode control register value is 00C2 (0000000011000010), and the output control signal PWM1/PWM4 drives the power inverter switch 1/power inverter switch 4.

When the Hall signal is 100, enter step S505, the comparison mode control register value is 02C0 (0000001011000000), and the output control signal PWM5/PWM4 drives the power inverter switch 5/power inverter switch 4.

When the Hall signal is 110, enter step S506, the comparison mode control register value is 020C (0000001000001100), and the output control signal PWM5/PWM2 drives the power inverter switch 5/power inverter switch 2.

When the Hall signal is 111, enter step S507, the comparison mode control register value is 002C (0000000000101100), and the output control signal PWM3/PWM2 drives the power inverter switch 3/power inverter switch 2.

When the Hall signal is 011, enter step S508, the comparison mode control register value is 0C20 (0000110000100000), and the output control signal PWM3/PWM6 drives the power inverter switch 3/power inverter switch 6.

If the mode flag is 0, then enter step S502 braking mode, and perform braking phase sequence calculation:

When the Hall signal is 001, enter step S509, the comparison mode control register value is 020C (0000001000001100), and the output control signal PWM5/PWM2 drives the power inverter switch 5/power inverter switch 2.

When the Hall signal is 000, enter step S510, the comparison mode control register value is 002C (0000000000101100), and the output control signal PWM3/PWM2 drives the power inverter switch 3/power inverter switch 2.

When the Hall signal is 100, enter step S511, the comparison mode control register value is 0C20 (0000110000100000), output control signal PWM3/PWM6 to drive power inverter switch 3/power inverter switch 6.

When the Hall signal is 110, enter step S512, the comparison mode control register value is 0C02 (0000110000000010), and the output control signal PWM1/PWM6 drives the power inverter switch 1/power inverter switch 6.

When the Hall signal is 111, enter step S513, the comparison mode control register value is 00C2 (0000000011000010), and the output control signal PWM1/PWM4 drives the power inverter switch 1/power inverter switch 4.

When the Hall signal is 011, enter step S514, the comparison mode control register value is 02C0 (0000001011000000), and the output control signal PWM3/PWM6 drives the power inverter switch 3/power inverter switch 6.

Fig. 6 is a flow chart of the power inverter switch breakdown fault diagnosis program of the present invention.

When the Hall signal is 001, enter step S601, the in-wheel motor conduction phase is UW, under normal circumstances U-phase current = W-phase current = ground current; if U-phase current ≠ ground current, it means that the power inverter switch 1 breaks down The U-phase current=0; if the W-phase current≠ground current, it means that the power inverter switch 6 breaks down and the W-phase current=0.

When the Hall signal is 000, go to step S602, the hub motor conduction phase is UV, under normal circumstances U-phase current = V-phase current = ground current; if U-phase current ≠ ground current, it means that the power inverter switch 1 breaks down The U-phase current=0; if the V-phase current≠ground current, it means that the power inverter switch 4 breaks down and the V-phase current=0.

When the Hall signal is 100, enter step S603, the in-wheel motor conduction phase is WV, under normal circumstances W-phase current = V-phase current = ground current; if W-phase current ≠ ground current, it means that the power inverter switch 5 breaks down The W-phase current=0; if the V-phase current≠ground current, it means that the power inverter switch 4 breaks down and the V-phase current=0.

When the Hall signal is 110, enter step S604, the in-wheel motor conduction phase is WU, under normal circumstances W-phase current = U-phase current = ground current; if W-phase current ≠ ground current, it means that the power inverter switch 5 breaks down The W-phase current = 0; if the U-phase current ≠ ground current, it means that the power inverter switch 2 breaks down and the U-phase current = 0.

When the Hall signal is 111, go to step S605, the in-wheel motor conduction phase is VW, under normal circumstances V-phase current = W-phase current = ground current; if V-phase current ≠ ground current, it means that the power inverter switch 3 breaks down The V-phase current=0; if the W-phase current≠ground current, it means that the breakdown of the power inverter switch 2 causes the W-phase current=0.

When the Hall signal is 011, go to step S606, the in-wheel motor conduction phase is VU, under normal circumstances V-phase current = U-phase current = ground current; if V-phase current ≠ ground current, it means that the power inverter switch 3 breaks down As a result, the V-phase current=0; if the U-phase current≠ground current, it means that the breakdown of the power inverter switch 6 causes the U-phase current=0.

Through the above method, it is possible to accurately diagnose which power inverter switch in the power inverter circuit is broken down.

Fig. 7 is a flow chart of the main and auxiliary Hall signal rule sequence verification program of the present invention. The three hall signals are 001, 000, 100, 110, 111, 011 in one commutation cycle when the hub motor is driven, which is the regular sequence of hall signals.

Step S701 reads the Hall signal at the last moment.

Step S702 judges whether the Hall signal read in step S701 conforms to the Hall signal rule sequence, if not conforming to or exceeds the Hall signal rule sequence, it means that at least one of the three Hall signals is faulty, based on which it is determined that the hub motor Hall Sensor failed.

Steps S703-S708 are a regular sequence for setting the Hall signal.

Step S703 is to set the Hall signal at the previous moment of Hall signal 001 to 011.

Step S704 is to set the Hall signal at the previous moment of the Hall signal 000 to 001.

Step S705 is to set the Hall signal 100 at the previous moment to 000.

Step S706 is to set the Hall signal 110 at the previous moment to 100.

Step S707 is to set the Hall signal 111 at the previous moment to be 110 .

Step S708 is to set the Hall signal 011 at the previous moment to 111.

Fig. 8 is a flow chart of the wheel speed estimation program of the present invention. The number of pole pairs of the in-wheel motor is 20, so 120 interruptions are triggered every time the rotor passes through one revolution (that is, the rotor passes through 1/120 revolution each time). The motor speed is estimated by calculating the interval between two adjacent interruptions.

Step S801 reads the count value of the counter when the last capture interrupt occurred.

Step S802 records the count value of the counter when the current capture interrupt occurs.

Next, determine whether the counter overflows when the current capture interrupt occurs, that is, the timer count value exceeds 65535. You can check whether the overflow occurs by querying the timer cycle interrupt flag bit.

If overflow occurs, go to step S803 and record the number of overflow occurrences.

Step S804 calculates the time interval between two adjacent interruptions in the case of an overflow, and the calculation formula is: count difference between two adjacent interruptions=the count value when the capture interrupt occurs at the current moment-the count value of the counter at the time when the capture interrupt occurred last time+ The number of overflows × 65535, and then multiplied by the counting cycle can get the interval between two adjacent interruptions.

If there is no overflow, enter step S805 to calculate the interval between two adjacent interruptions without overflow. The calculation formula is: the count difference between two adjacent interruptions = the count value when the capture interruption occurs at the current moment - the last time Capture the count value of the counter when the interrupt occurs, and then multiply it by the count cycle to get the interval between two adjacent interrupts.

Step S806 updates the count value of the capture interrupt counter.

Step S807 calculates the wheel speed, the calculation formula is: wheel speed = 60.0/(1.7×10 ^-6 ×120×interval time between two adjacent interruptions), where 1.7×10 ^-6 is the counting period, and the constant 120 is the number of times the rotor passes 120 interrupts occur in one revolution, and then multiplied by a constant of 60 to convert the unit revolution/second to revolution/minute.

Claims (6)

1. A centralized fault diagnosis controller for an electric vehicle drive system, comprising: Main control module, embedded main control chip and its minimum circuit; The signal acquisition and correction module is embedded with the bus voltage acquisition port, current acquisition port, and correction voltage acquisition port. At the same time, the AD conversion error caused by the zero drift of the main control chip is corrected through correction processing; The Hall signal calculation module collects the main and auxiliary Hall signals and calculates them into the control register value of the comparison mode of the main control chip, and outputs the corresponding PWM signal according to the commutation phase sequence of the in-wheel motor; The power drive module is embedded with a drive circuit and a power inverter circuit, and a current sensor is added to the ground terminal and the hub motor phase terminal to collect the ground current and phase current; The wheel speed estimation module estimates the wheel speed of the hub motor through the Hall signal of the hub motor; Aiming at the power switch breakdown fault of the power inverter circuit, a power inverter switch breakdown fault diagnosis module is designed; Aiming at the failure of the Hall sensor of the hub motor, the main and auxiliary Hall signal redundancy verification module, the main and auxiliary Hall signal rule sequence verification module and the whole wheel speed comparison module are designed; Among them, the main control module, signal acquisition and correction module, Hall signal calculation module, power drive module, wheel speed estimation module, power inverter switch breakdown fault diagnosis module, main and auxiliary Hall signal redundancy verification module and main and auxiliary The Hall signal rule sequence verification module is embedded in the left front/right front/left rear/right rear wheel drive controller; the whole wheel speed comparison module receives the left front/right front/left rear/right rear wheel speed through the vehicle bus, and Carry out wheel speed comparison in the vehicle controller. 2. The centralized controller for fault diagnosis of the electric vehicle drive system according to claim 1, characterized in that, the signal correction process: solve the gain error coefficient existing in the AD conversion process by the analog quantity of the reference voltage and its digital quantity And the offset error coefficient, and use it to correct the AD conversion error caused by the zero drift of the main control chip. 3. The centralized controller for fault diagnosis of the electric vehicle drive system according to claim 1, characterized in that, the power inverter switch breakdown fault diagnosis module: since the motor conduction phase and the ground constitute the same loop, the conduction The phase current and the grounding circuit must be equal; on the contrary, if a power switch of the power inverter circuit is broken down, it will inevitably cause a short circuit in the corresponding phase of the hub motor, and the short-circuit phase current is zero, obviously the grounding current is not zero; through Compare whether the current into the ground is equal to the conduction phase current of the hub motor to diagnose the breakdown fault of the power inverter switch of the left front/right front/left rear/right rear wheel drive controller. 4. The centralized controller for fault diagnosis of the electric vehicle drive system according to claim 1, characterized in that, said main and auxiliary Hall signal redundancy check module: performs redundancy by two sets of Hall sensors carried by the in-wheel motor. Use the diagnostics to determine whether the Hall sensor of the front left/front right/rear left/rear right hub motor fails. 5. The centralized controller for fault diagnosis of the electric vehicle drive system according to claim 1, characterized in that, the main and auxiliary Hall signal rule sequence verification module: the Hall signal of the hub motor is within the adjacent commutation period The change law is fixed, and it can be used to diagnose whether the Hall sensor of the left front/right front/left rear/right rear hub motor is invalid. 6. The centralized controller for fault diagnosis of the drive system of an electric vehicle according to claim 1, wherein the complete wheel speed comparison module: receives the wheel speed estimation module through the vehicle-mounted bus for left front/right front/left rear/right The estimated wheel speed of the rear hub motor. If the relative error of the estimated wheel speed value of a certain hub motor exceeds the threshold, it means that the Hall sensor of the corresponding hub motor is invalid.