CN115421068A - MOSFET short-circuit fault detection system and method of three-phase bridge type inverter circuit - Google Patents
MOSFET short-circuit fault detection system and method of three-phase bridge type inverter circuit Download PDFInfo
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Abstract
The invention discloses a MOSFET short-circuit fault detection system and a method of a three-phase bridge inverter circuit, wherein the detection system comprises an input power supply, a pre-drive IC, an MCU module, an inverter, successive electric appliances, a motor, a pull-up resistor and a voltage division circuit; the inverter is used for converting an input power supply into alternating current with variable frequency for the working of the power supply machine and driving the motor to rotate; the successive electrical appliances are connected in series to the three-phase input of the motor and are used for cutting off the output voltage and current of the inverter when the inverter fails. The invention provides a MOSFET short-circuit fault detection system and a MOSFET short-circuit fault detection method for a three-phase bridge type inverter circuit, which can detect faults of the MOSFET of an inverter during power-on and initialization of the system, detect corresponding faults of MOSFETs of successive electric appliances, accurately locate the MOSFET with a single fault, avoid the fault from flowing into an automobile driving link and ensure the personal safety of a driver and passengers.
Description
Technical Field
The invention relates to a MOSFET short-circuit fault detection system and method of a three-phase bridge type inverter circuit.
Background
At present, most of direct current brushless motor control schemes adopt a three-phase bridge inverter to output alternating current with variable frequency to control the rotation of a motor. The MOSFET, which is the main component of the inverter, has a high-speed switching state, and can generally reach more than 20 KHz. The MOSFET is easy to damage due to extremely high voltage overshoot at the moment of switching on and off and large heat productivity caused by high-speed switching, and the MOSFET is easy to break down due to the reverse electromotive force generated by the high-speed rotation of the motor. After the MOSFET is broken down, a vehicle direct-current power supply can be directly loaded to a motor coil, so that the current of the motor coil is overlarge, the heat productivity is huge in a short time, even the heat is burnt, and a major traffic accident is easily caused.
Most of the existing technical schemes for MOSFET fault detection are to adopt series current detection resistors to detect the three-phase current of a motor, and the processing mode of detecting that a certain phase current is too large or too small is to cut off the output of an inverter through successive electric appliances, so as to prevent the motor from being blocked or a coil from being burnt out. However, the detection method is only suitable for the motor running process and is used as an important safety part of an electric power steering gear and an electric power braking system on an automobile, and the inverter is turned off during the running process to cause the sudden failure of power assistance, so that a driver is difficult to control the automobile, and particularly traffic accidents are easy to happen under the high-speed running condition.
In the prior art as shown in fig. 1, the whole system consists of six parts, namely, a power input, a pre-drive IC, an inverter, successive electric appliances, a motor and phase current monitoring. The inverter is a bridge circuit formed by six MOSFETs, and the successive electric appliances are respectively connected in series with the three-phase input of the motor by three MOSFETs. And the terminal voltage monitoring acquires the terminal voltage of the motor through the ADC and provides the terminal voltage to the singlechip. The inverter is mainly used for driving the direct current brushless motor to rotate, and the input direct current 12V voltage is converted into alternating current with variable frequency for the work of the motor through the MOSFET high-speed switch. The pre-drive IC controls six MOSFETs of the inverter to carry out switching work according to a certain sequential logic strategy by receiving a PWM instruction of the MCU. The sequential electric appliance is mainly used for cutting off the output voltage and current of the inverter when the inverter fails, so that the motor is prevented from misoperation and the motor coil is prevented from being burnt out. The phase current monitoring detects the three-phase current of the inverter U, V, W through the current sampling resistor, and inputs the three-phase current to the MCU for monitoring and judging whether the inverter and the motor work normally or not.
In a general scheme, when a system is electrified and initialized, a pre-drive IC does not work, all MOSFETs in an inverter are in an OFF state, and after the system is initialized, the pre-drive IC starts to work according to an MCUPWM instruction to control the MOSFETs to switch. Therefore, when the system is electrified and initialized, if a single MOSFET of an upper bridge or a lower bridge in the inverter is in a short-circuit fault state or a MOSFET of any one successive electric appliance is in a short-circuit fault state, the fault cannot be detected through the current sampling resistor.
Therefore, how to detect the MOSFET fault of the inverter when the vehicle is started so as to avoid the loss of the assist force during the driving is an urgent problem to be solved.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of the prior art and provides a MOSFET short-circuit fault detection system and a MOSFET short-circuit fault detection method for a three-phase bridge inverter circuit, so that the system can detect the faults of the MOSFET of the inverter during power-on and initialization, can detect the corresponding faults of the MOSFETs of successive electrical appliances, can accurately position the MOSFET with a single fault, avoid the fault from flowing into an automobile driving link, and ensure the personal safety of a driver and passengers.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the invention provides a MOSFET short-circuit fault detection system of a three-phase bridge type inverter circuit, which comprises an input power supply, a pre-drive IC, an MCU module, an inverter, successive electric appliances, a motor, a pull-up resistor and a voltage division circuit, wherein the input power supply is connected with the pre-drive IC;
the inverter is used for converting an input power supply into alternating current with variable frequency for the working of the power supply machine and driving the motor to rotate;
the sequential electric appliance is connected in series with the three-phase input end of the motor and is used for cutting off the output voltage and current of the inverter when the inverter breaks down;
the MCU module monitors the voltage of a motor terminal through a voltage division circuit;
the pre-drive IC controls the inverter to carry out switching work according to a sequential logic strategy by receiving a PWM (pulse width modulation) instruction of the MCU;
and the single phase of the motor is connected with an input power supply through a pull-up resistor.
Further, the inverter is a bridge circuit formed by six MOSFETs,
further, the successive electrical devices comprise three MOSFETs connected in series to the three-phase input of the motor, respectively.
Another aspect of the present invention provides a method for detecting a short-circuit fault of a MOSFET of a three-phase bridge inverter circuit, including:
step S1, when a three-phase bridge inverter is powered on and a MOSFET (metal oxide semiconductor field effect transistor) does not have a fault, monitoring the normal state voltage of a motor terminal through an MCU (microprogrammed control unit) module;
s2, after the three-phase bridge inverter is powered on, the MCU module monitors the voltage of a motor terminal in real time and compares the real-time monitoring voltage monitored by the MCU module with the voltage in a normal state;
and S3, if the real-time monitoring voltage monitored by the MCU module is different from the normal state voltage, judging that the MOSFET of the three-phase bridge type inverter circuit has a short-circuit fault.
Further, the short-circuit faults of the MOSFETs of the three-phase bridge inverter circuit in step S3 include an inverter upper bridge MOSFET and a successive electrical short-circuit fault and an inverter lower bridge MOSFET short-circuit fault.
Further, the method for detecting the short-circuit fault of the successive electrical appliances specifically comprises the following steps:
when the MOSFETs are not in fault after power-on, at the moment, each MOSFET of the inverter is in an OFF state, successive electrical appliances are in OFF states, the pre-drive IC is in an OFF state, the voltage of the motor terminal monitored by the MCU module is equal to the ground, the real-time monitoring voltage of the motor terminal monitored by the MCU module is the normal power-on voltage of the system, and the normal power-on voltage X1 of the system is as follows:
the delta ADC is an ADC reading error, vmcu is an MCU power supply voltage, m is an ADC sampling digit, R1 is an upper side divider resistor, R2 is a lower side divider resistor, and R3 is a pull-up resistor;
when the U successive electrical appliance is in short circuit, the current flows to the ground through the voltage division circuit through the pull-up current blocking, the real-time monitoring voltage of the motor terminal monitored by the MCU module is the successive electrical appliance short circuit fault alarm value, and the successive electrical appliance short circuit fault alarm value Y1 is as follows:
wherein, Δ ADC is the ADC reading error, vmcu is the MCU supply voltage, m is the ADC sampling number, R1 is the upper side divider resistor, R2 is the lower side divider resistor, R3 is the pull-up resistor, vin is the input supply voltage, and Δ Vmcu is the MCU supply voltage error;
when the V successive electrical appliance or the W successive electrical appliance is in short circuit, the current flows to the motor coil through the pull-up resistor and then flows to the ground through the voltage division circuit, and the real-time monitoring voltage of the motor terminal monitored by the MCU module is equal to the short-circuit fault alarm value Y1 of the successive electrical appliance.
Further, the method for detecting the short-circuit fault of the upper bridge MOSFET of the inverter specifically comprises the following steps:
when the upper bridge MOSFET of the inverter is in short circuit, the current passes through the short-circuited MOSFET and goes to the ground through the voltage division circuit, the real-time monitoring voltage of the motor terminal monitored by the MCU module at the moment is the short-circuit fault alarm value of the upper bridge MOSFET of the inverter, and the short-circuit fault alarm value Y2 of the upper bridge MOSFET of the inverter is as follows:
Y2＞Y1；
wherein, Δ ADC is ADC reading error, vmcu is MCU supply voltage, m is ADC sampling digit, R1 is upper side divider resistance, R2 is lower side divider resistance, vin is input power voltage, and Δ Vmcu is MCU supply voltage error.
Further, the detection conditions of the short-circuit fault of the MOSFET on the upper bridge of the inverter and the short-circuit fault of the successive electric appliance are the same, and the real-time monitoring voltage value of the motor terminal monitored by the MCU module is set as V0;
when V0 is less than X1, the system judges that the system is normal;
when X1 is more than or equal to V0 and less than Y1, the system judges that the short circuit fault of successive electric appliances occurs;
when the voltage Y1 is larger than or equal to the voltage V0 and smaller than or equal to the voltage Y2, the system judges that short-circuit fault of the upper bridge MOSFET of the inverter occurs.
Further, the method for detecting short-circuit fault of the lower bridge MOSFET of the inverter in the step S3 specifically includes the following steps:
when the system is initialized after power-on and the MOSFETs are not in fault, at the moment, each MOSFET of the inverter is in an OFF state, successive electric appliances are in OFF states, the pre-driver IC is in an open state, but a driving instruction is not sent out, at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the system initialization normal voltage, and the system initialization normal voltage X2 is as follows:
wherein Ir is the pre-driver IC leakage current, Δ ADC is the ADC reading error, vmcu is the MCU supply voltage, m is the ADC sampling digit, R1 is the upper side divider resistor, R2 is the lower side divider resistor, vin is the input power voltage, Δ Vmcu is the MCU supply voltage error,
when the short-circuit fault of the lower bridge MOSFET of the inverter occurs, the leakage current of the pre-drive IC flows into the ground through the short-circuit MOSFET, the real-time monitoring voltage of the motor terminal monitored by the MCU module is the short-circuit fault alarm value of the lower bridge MOSFET of the inverter, and the short-circuit fault alarm value Y3 of the lower bridge MOSFET of the inverter is as follows:
wherein, Δ ADC is ADC reading error, vmcu is MCU supply voltage, n is AD conversion digit, R1 is upper side divider resistance, and R2 is lower side divider resistance.
Further, short-circuit fault detection is carried out on the MOSFET of the lower bridge of the inverter under the condition that the pre-drive IC is opened, and the real-time monitoring voltage value of the motor terminal monitored by the MCU module is set as V0;
and when the Y3 is more than or equal to V0 and less than X2, the system judges that short-circuit fault of the lower bridge MOSFET of the inverter occurs.
By adopting the technical scheme, the invention provides a detection method aiming at the following two fault conditions of the direct current brushless motor control inverter:
1. short circuit fault of bridge MOSFET and successive electric appliance on the inverter.
2. Short circuit fault of the lower bridge MOSFET of the inverter.
The phase voltage of the three-phase input terminal of the motor U, V, W is input to the MCU through the voltage division circuit to monitor the voltage and judge whether the inverter and the motor work normally. The power supply is connected by adding a pull resistor to a single phase of the motor, so that the monitoring voltage is different from the monitoring voltage in a normal state when a fault occurs, and the fault is detected. The occurrence of a fault is detected by the difference between the monitoring voltage in the normal state and the fault state caused by the leakage current when the pre-driver IC is turned on. When the vehicle is started, the MOSFET fault of the inverter is detected, so that the loss of the power assistance in the driving process is avoided, and the personal safety of a driver and passengers is guaranteed.
Drawings
FIG. 1 is a schematic diagram of a prior art motor controller system of the present invention;
FIG. 2 is a schematic block diagram of a MOSFET short circuit fault detection system of the three-phase bridge inverter circuit of the present invention;
FIG. 3 is an equivalent circuit of the system of the present invention in a normal state after power-up;
FIG. 4 is an equivalent circuit of the present invention when the U successive electrical appliance has a short circuit fault;
FIG. 5 is an equivalent circuit of V, W of the present invention when there is a short circuit fault in successive appliances;
FIG. 6 is an equivalent circuit for short circuit fault of the upper bridge MOSFET of the inverter of the present invention;
FIG. 7 is an equivalent circuit of the system of the present invention in a normal state during initialization;
fig. 8 is an equivalent circuit at the time of short-circuit failure of the inverter lower bridge MOSFET of the present invention.
Detailed Description
In order that the present invention may be more readily and clearly understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings.
Example one
As shown in fig. 2, the present embodiment provides a MOSFET short-circuit fault detection system of a three-phase bridge inverter circuit, which includes an input power source, a pre-driver IC, an MCU module, an inverter, a sequential electrical device, a motor, a pull-up resistor, and a voltage divider circuit.
Specifically, the inverter is used for converting a direct current 12V voltage input into a power supply through the MOSFET high-speed switch into an alternating current with variable frequency for the work of the motor, and driving the motor to rotate, and the inverter is a bridge circuit formed by six MOSFETs.
The successive electric appliance comprises three MOSFETs which are respectively connected in series with the three-phase input end of the motor, and the three MOSFETs are respectively connected in series with the U, V, W input end of the three-phase motor. The successive electric appliances are connected in series at the three-phase input end of the motor and used for cutting off the output voltage and current of the inverter when the inverter fails, so that the motor is prevented from misoperation and the motor coil is prevented from being burnt out.
The MCU module monitors the voltage of the motor terminal through a voltage division circuit, the ADC inside the MCU module carries out AD sampling, and the voltage division circuit is formed by connecting an upper side voltage division resistor R1 and a lower side voltage division resistor R2 in series.
The pre-drive IC controls six MOSFETs of the inverter to carry out switching work according to a certain sequential logic strategy by receiving a PWM instruction of the MCU.
When the MOSFET in successive electric appliances has short-circuit fault, the power current flows through the coil of the motor through the pull-up resistor and then flows through the short-circuit MOSFET to generate voltage on the voltage division circuit, so that the short-circuit state can be detected.
As shown in fig. 2, in this embodiment, a pull resistor R3 is added to a single-phase input end of a motor to connect a power supply, and a voltage of a motor terminal is sampled and collected by an MCU module ADC, and when a short-circuit fault of successive electric appliances occurs, a power supply current flows through a motor coil by a pull-up choke and then flows through MOSFETs of the successive electric appliances which are short-circuited; when the inverter upper bridge MOSFET is short-circuited, the current passes through the short-circuited inverter upper bridge MOSFET to the ground through the voltage dividing circuit, and a voltage is generated on the voltage dividing circuit, so that the short-circuited state can be detected.
In addition, under the condition that the pre-drive IC is powered but not output, an output pin of the pre-drive IC generates tiny leakage current, according to the characteristic, when the system is powered on and initialized, the pre-drive IC is powered, but the MCU does not send a PWM instruction to enable the pre-drive IC to work, and whether the lower bridge MOSFET of the inverter is short-circuited or not is judged according to the voltage generated on the sampling resistor by the leakage current.
Example two
The embodiment provides a detection method of a MOSFET short-circuit fault detection system of a three-phase bridge inverter circuit, which comprises the following steps:
s1, monitoring the normal state voltage of a motor terminal through an MCU module when a three-phase bridge inverter is powered on and the MOSFET does not have a fault;
s2, after the three-phase bridge inverter is powered on, the MCU module monitors the voltage of a motor terminal in real time, and the real-time monitoring voltage monitored by the MCU module is compared with the voltage in a normal state;
and S3, if the real-time monitoring voltage monitored by the MCU module is different from the normal state voltage, judging that the MOSFET of the three-phase bridge inverter circuit has a short-circuit fault.
The short-circuit faults of the MOSFETs of the three-phase bridge inverter circuit in step S3 of the present embodiment include an inverter upper bridge MOSFET and a consecutive appliance short-circuit fault and an inverter lower bridge MOSFET short-circuit fault.
Specifically, the method for detecting the short-circuit fault of the successive electrical appliances specifically comprises the following steps:
fig. 3 is an equivalent circuit when the MOSFETs have no fault after power-on, the MOSFETs of the inverter are in an OFF state, the successive electrical devices are in an OFF state, the pre-driver IC is in an OFF state, the voltage of the motor terminal monitored by the MCU module is equal to ground, and considering the error caused by the ADC reading error and the LSB conversion, the real-time monitoring voltage of the motor terminal monitored by the MCU module is the system power-on normal voltage, and the system power-on normal voltage X1 is:
the ADC is an ADC reading error, vmcu is an MCU power supply voltage, m is an ADC sampling digit, R1 is an upper side divider resistor, R2 is a lower side divider resistor, and R3 is a pull-up resistor;
fig. 4 is an equivalent circuit when the U successive electrical appliance has a short circuit fault, when the U successive electrical appliance has a short circuit, the current flows to the ground through the pull-up current blocking circuit and the voltage dividing circuit, at this time, the real-time monitoring voltage of the motor terminal monitored by the MCU module is a successive electrical appliance short circuit fault alarm value, and the successive electrical appliance short circuit fault alarm value Y1 is:
wherein, Δ ADC is the ADC reading error, vmcu is the MCU supply voltage, m is the ADC sampling number, R1 is the upper side divider resistor, R2 is the lower side divider resistor, R3 is the pull-up resistor, vin is the input supply voltage, and Δ Vmcu is the MCU supply voltage error;
fig. 5 is an equivalent circuit when the V-phase and W-phase successive electrical appliances have short-circuit faults, and when the V-phase and W-phase successive electrical appliances are short-circuited, the current passes through the pull-up resistor to the motor coil and then to the ground through the voltage dividing circuit, because the internal resistance of the motor coil is negligible compared with the pull-up resistor, the real-time monitoring voltage of the motor terminal monitored by the MCU module is equal to the successive electrical appliance short-circuit fault alarm value Y1.
Specifically, the method for detecting the short-circuit fault of the upper bridge MOSFET of the inverter specifically comprises the following steps:
fig. 6 is an equivalent circuit when short-circuit fault occurs to the upper bridge MOSFET of the inverter, when the upper bridge MOSFET of the inverter is short-circuited, the current passes through the short-circuited MOSFET and goes to the ground through the voltage dividing circuit, the real-time monitoring voltage of the motor terminal monitored by the MCU module at this time is an alarm value of short-circuit fault of the upper bridge MOSFET of the inverter, and the alarm value Y2 of short-circuit fault of the upper bridge MOSFET of the inverter is:
Y2＞Y1；
compared with the real-time monitoring voltage Y1 monitored when the successive electrical appliance is short-circuited, the real-time monitoring voltage Y2 when the upper bridge MOSFET is short-circuited is much higher;
wherein, Δ ADC is ADC reading error, vmcu is MCU supply voltage, m is ADC sampling digit, R1 is upper side divider resistance, R2 is lower side divider resistance, vin is input power voltage, and Δ Vmcu is MCU supply voltage error.
In conclusion, the detection conditions of the short-circuit fault of the MOSFET on the upper bridge of the inverter and the short-circuit fault of the successive electric appliances are the same, and the real-time monitoring voltage value of the motor terminal monitored by the MCU module is set to be V0;
when V0 is less than X1, the system judges that the system is normal;
when X1 is more than or equal to V0 and less than Y1, the system judges that the short circuit fault of successive electric appliances occurs;
when Y1 is more than or equal to V0 and less than or equal to Y2, the system judges that short-circuit fault of the upper bridge MOSFET of the inverter occurs.
Specifically, the method for detecting the short-circuit fault of the lower bridge MOSFET of the inverter in step S3 specifically includes the following steps:
fig. 7 is an equivalent circuit of the inverter and the motor in a normal state during system initialization, when the system is initialized after power is turned on and the MOSFETs are not in failure, the MOSFETs of the inverter are in an OFF state at this time, the electrical appliance is in an OFF state successively, the pre-driver IC is in an on state, but does not send a driving instruction, the real-time monitoring voltage of the MCU module monitoring the motor terminal is a system initialization normal voltage, and the system initialization normal voltage X2 is:
wherein Ir is the pre-driver IC leakage current, Δ ADC is the ADC reading error, vmcu is the MCU supply voltage, m is the ADC sampling digit, R1 is the upper side divider resistor, R2 is the lower side divider resistor, vin is the input power voltage, Δ Vmcu is the MCU supply voltage error,
fig. 8 is an equivalent circuit when the short-circuit fault occurs in the lower bridge of the inverter, when the short-circuit fault occurs in the MOSFET in the lower bridge of the inverter, the leakage current of the pre-driver IC flows into the ground through the short-circuited MOSFET, the real-time monitoring voltage of the motor terminal monitored by the MCU module at this time is the short-circuit fault alarm value of the MOSFET in the lower bridge of the inverter, and the short-circuit fault alarm value Y3 of the MOSFET in the lower bridge of the inverter is:
wherein, Δ ADC is ADC reading error, vmcu is MCU supply voltage, n is AD conversion digit, R1 is upper side divider resistance, and R2 is lower side divider resistance.
In summary, short-circuit fault detection of the lower bridge MOSFET of the inverter is carried out under the condition that the pre-drive IC is opened, and the real-time monitoring voltage value of the motor terminal monitored by the MCU module is set as V0;
and when the Y3 is more than or equal to V0 and less than X2, the system judges that short-circuit fault of the lower bridge MOSFET of the inverter occurs.
The technical problems, technical solutions and advantages of the present invention will be further described in detail with reference to the above embodiments, it should be understood that the above embodiments are only examples of the present invention and should not be construed as limiting the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The utility model provides a MOSFET short-circuit fault detecting system of three-phase bridge type inverter circuit which characterized in that: the device comprises an input power supply, a pre-drive IC, an MCU module, an inverter, successive electric appliances, a motor, a pull-up resistor and a voltage division circuit;
the inverter is used for converting an input power supply into alternating current with variable frequency for the working of the power supply machine and driving the motor to rotate;
the sequential electric appliance is connected in series with the three-phase input end of the motor and is used for cutting off the output voltage and current of the inverter when the inverter fails;
the MCU module monitors the voltage of a motor terminal through a voltage division circuit;
the pre-drive IC controls the inverter to carry out switching work according to a sequential logic strategy by receiving a PWM (pulse width modulation) instruction of the MCU;
and the single phase of the motor is connected with an input power supply through a pull-up resistor.
2. The MOSFET short-circuit fault detection system of a three-phase bridge inverter circuit of claim 1, wherein: the inverter is a bridge circuit formed by six MOSFETs.
3. The MOSFET short-circuit fault detection system of a three-phase bridge inverter circuit of claim 1, wherein: the successive electrical devices comprise three MOSFETs connected in series to the three-phase input of the motor.
4. A detection method of a MOSFET short-circuit fault detection system of a three-phase bridge inverter circuit according to any of claims 1 to 3, characterized in that it comprises:
step S1, when a three-phase bridge inverter is powered on and a MOSFET (metal oxide semiconductor field effect transistor) does not have a fault, monitoring the normal state voltage of a motor terminal through an MCU (microprogrammed control unit) module;
s2, after the three-phase bridge inverter is powered on, the MCU module monitors the voltage of a motor terminal in real time and compares the real-time monitoring voltage monitored by the MCU module with the voltage in a normal state;
and S3, if the real-time monitoring voltage monitored by the MCU module is different from the normal state voltage, judging that the MOSFET of the three-phase bridge type inverter circuit has a short-circuit fault.
5. The method of detecting a short-circuit fault of a MOSFET of a three-phase bridge inverter circuit according to claim 4, wherein: and the short-circuit faults of the MOSFETs of the three-phase bridge type inverter circuit in the step S3 comprise an inverter upper bridge MOSFET, a successive electrical appliance short-circuit fault and an inverter lower bridge MOSFET short-circuit fault.
6. The method for detecting the short-circuit fault of the MOSFET of the three-phase bridge inverter circuit according to claim 5, wherein the method for detecting the short-circuit fault of the successive appliances comprises the following steps:
when the MOSFETs are not in fault after power-on, at the moment, each MOSFET of the inverter is in an OFF state, successive electrical appliances are in OFF states, the pre-drive IC is in an OFF state, the voltage of the motor terminal monitored by the MCU module is equal to the ground, the real-time monitoring voltage of the motor terminal monitored by the MCU module is the normal power-on voltage of the system, and the normal power-on voltage X1 of the system is as follows:
the delta ADC is an ADC reading error, vmcu is an MCU power supply voltage, m is an ADC sampling digit, R1 is an upper side divider resistor, R2 is a lower side divider resistor, and R3 is a pull-up resistor;
when the U successive electrical appliance is in short circuit, the current flows to the ground through the pull-up current blocking circuit and the voltage division circuit, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the successive electrical appliance short circuit fault alarm value, and the successive electrical appliance short circuit fault alarm value Y1 is as follows:
wherein, Δ ADC is the ADC reading error, vmcu is the MCU supply voltage, m is the ADC sampling number, R1 is the upper side divider resistor, R2 is the lower side divider resistor, R3 is the pull-up resistor, vin is the input supply voltage, and Δ Vmcu is the MCU supply voltage error;
when the V successive electrical appliance or the W successive electrical appliance is in short circuit, the current flows to the motor coil through the pull-up resistor and then flows to the ground through the voltage division circuit, and the real-time monitoring voltage of the motor terminal monitored by the MCU module is equal to the short-circuit fault alarm value Y1 of the successive electrical appliance.
7. The method for detecting the short-circuit fault of the MOSFET of the three-phase bridge inverter circuit according to claim 5, wherein the method for detecting the short-circuit fault of the MOSFET of the inverter includes the following steps:
when the upper bridge MOSFET of the inverter is in short circuit, the current passes through the short-circuited MOSFET and goes to the ground through the voltage division circuit, the real-time monitoring voltage of the motor terminal monitored by the MCU module at the moment is the short-circuit fault alarm value of the upper bridge MOSFET of the inverter, and the short-circuit fault alarm value Y2 of the upper bridge MOSFET of the inverter is as follows:
Y2＞Y1；
wherein, Δ ADC is ADC reading error, vmcu is MCU supply voltage, m is ADC sampling digit, R1 is upper side divider resistance, R2 is lower side divider resistance, vin is input power voltage, and Δ Vmcu is MCU supply voltage error.
8. The method of detecting a MOSFET short circuit fault in a three-phase bridge inverter circuit of claim 7, wherein:
the detection conditions of the short-circuit fault of the MOSFET on the upper bridge of the inverter and the short-circuit fault of the successive electric appliances are the same, and the real-time monitoring voltage value of the motor terminal monitored by the MCU module is set to be V0;
when V0 is less than X1, the system judges that the system is normal;
when X1 is more than or equal to V0 and less than Y1, the system judges that the short circuit fault of successive electric appliances occurs;
when Y1 is more than or equal to V0 and less than or equal to Y2, the system judges that short-circuit fault of the upper bridge MOSFET of the inverter occurs.
9. The method for detecting the short-circuit fault of the MOSFET of the three-phase bridge inverter circuit according to claim 5, wherein the method for detecting the short-circuit fault of the MOSFET of the lower bridge of the inverter in the step S3 specifically comprises the following steps:
when the system is initialized after power-on and the MOSFETs are not in fault, at the moment, each MOSFET of the inverter is in an OFF state, successive electric appliances are in OFF states, the pre-driver IC is in an open state, but a driving instruction is not sent out, at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the system initialization normal voltage, and the system initialization normal voltage X2 is as follows:
wherein Ir is the pre-driver IC leakage current, Δ ADC is the ADC reading error, vmcu is the MCU supply voltage, m is the ADC sampling digit, R1 is the upper side divider resistor, R2 is the lower side divider resistor, vin is the input power voltage, Δ Vmcu is the MCU supply voltage error,
when the short-circuit fault of the lower bridge MOSFET of the inverter occurs, the leakage current of the pre-drive IC flows into the ground through the short-circuit MOSFET, the real-time monitoring voltage of the motor terminal monitored by the MCU module is the short-circuit fault alarm value of the lower bridge MOSFET of the inverter, and the short-circuit fault alarm value Y3 of the lower bridge MOSFET of the inverter is as follows:
wherein, Δ ADC is ADC reading error, vmcu is MCU supply voltage, n is AD conversion digit, R1 is upper side divider resistance, and R2 is lower side divider resistance.
10. The method of detecting a MOSFET short-circuit fault in a three-phase bridge inverter circuit according to claim 9, wherein:
detecting short-circuit faults of MOSFET (metal oxide semiconductor field effect transistor) of a lower bridge of the inverter under the condition that the pre-drive IC is opened, and setting a real-time monitoring voltage value of a motor terminal monitored by the MCU module as V0;
and when the Y3 is more than or equal to V0 and less than X2, the system judges that short-circuit fault of the lower bridge MOSFET of the inverter occurs.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116736068A (en) * | 2023-08-14 | 2023-09-12 | 天津德科智控股份有限公司 | Power fault characteristic data identification and processing method |
| CN117302341A (en) * | 2023-11-28 | 2023-12-29 | 上海同驭汽车科技有限公司 | Electric power steering system and diagnosis protection method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116736068A (en) * | 2023-08-14 | 2023-09-12 | 天津德科智控股份有限公司 | Power fault characteristic data identification and processing method |
| CN116736068B (en) * | 2023-08-14 | 2023-11-14 | 天津德科智控股份有限公司 | Power fault characteristic data identification and processing method |
| CN117302341A (en) * | 2023-11-28 | 2023-12-29 | 上海同驭汽车科技有限公司 | Electric power steering system and diagnosis protection method |
| CN117302341B (en) * | 2023-11-28 | 2024-02-13 | 上海同驭汽车科技有限公司 | Electric power steering system and diagnosis protection method |
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