CN115421068B - A MOSFET short-circuit fault detection system and method for a three-phase bridge inverter circuit - Google Patents
A MOSFET short-circuit fault detection system and method for a three-phase bridge inverter circuit Download PDFInfo
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Abstract
The invention discloses a MOSFET short-circuit fault detection system and 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, a successive electrical apparatus, a motor, a pull-up resistor and a voltage dividing circuit; the inverter is used for converting an input power supply into alternating current with variable frequency for the motor to work and driving the motor to rotate, the relay is connected in series with the three-phase input end of the motor, and the relay is used for cutting off the output voltage and current of the inverter when the inverter breaks down. The invention provides a MOSFET short-circuit fault detection system and method of a three-phase bridge inverter circuit, which enable the system to detect faults of an inverter MOSFET during power-on and initialization, detect corresponding faults of successive electrical appliance MOSFETs, accurately position a single fault MOSFET, avoid the faults from flowing into an automobile driving link and ensure personal safety of drivers and passengers.
Description
Technical Field
The invention relates to a MOSFET short-circuit fault detection system and method of a three-phase bridge inverter circuit.
Background
At present, most of brushless DC motor control schemes adopt three-phase bridge inverter to output alternating current with variable frequency to control motor rotation. As the main component MOSFET of the inverter, the working condition is a high-speed switch state, and the operating condition can reach more than 20 KHz. The MOSFET is extremely fragile due to the large heat generation caused by the extremely high voltage overshoots at the moment of turning on and off and the high-speed switch, and in addition, 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 breaks down, a vehicle direct current power supply is directly loaded to a motor coil, so that the motor coil current is overlarge, and the motor coil generates huge heat and even burns in a short time, so that serious traffic accidents are easily caused.
Most of the prior technical schemes for detecting the faults of the MOSFETs are that three-phase current detection of the motor is carried out by adopting a series current detection resistor, and the processing mode of detecting that the current of a certain phase is too large or too small is that the output of the inverter is cut off through a successive electrical appliance, so that the motor is prevented from being blocked or a coil is prevented from being burnt out. However, the detection method is only suitable for an electric power steering gear and an electric power braking system which are important safety components on an automobile in the running process of the motor, and when the automobile runs through Cheng Nibian, the power steering gear is turned off, so that the power steering is suddenly disabled, a driver is difficult to control the automobile, and particularly, traffic accidents are very easy to occur under the high-speed running condition.
In the prior art as shown in fig. 1, the whole system consists of six parts including a power supply input, a pre-drive IC, an inverter, a relay, a motor and a phase current monitor. The inverter is a bridge circuit formed by six MOSFETs, and the relay is respectively connected in series with three phases of input of the motor by three MOSFETs. Terminal voltage monitoring is carried out by collecting motor terminal voltage through an ADC and providing the motor 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 motor to work through the MOSFET high-speed switch. The pre-drive IC receives the PWM instruction of the MCU to control six MOSFETs of the inverter to perform switching operation according to a certain sequential logic strategy. The relay 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 the normal scheme, when the system is electrified and initialized, the pre-drive IC does not work, all MOSFETs in the inverter are in an OFF state, and after the system is initialized, the pre-drive IC starts to work according to MCUPWM instructions to control the MOSFETs to switch. Therefore, when the system is powered on 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 if any one of the MOSFETs of the successive electrical appliances is in a short-circuit fault state, the fault cannot be detected through the current sampling resistor.
Therefore, how to detect the MOSFET failure of the inverter at the time of starting the vehicle, so as to avoid the occurrence of the power-assist loss during running is a problem to be solved.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the prior art, and provide a system and a method for detecting the MOSFET short-circuit fault of 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 MOSFET of a successive electrical appliance, can accurately position the MOSFET with single fault, avoid the faults from flowing into an automobile driving link, and ensure the personal safety of drivers 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 inverter circuit, which comprises an input power supply, a pre-drive IC, an MCU module, an inverter, a successive electrical appliance, 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 motor to work and driving the motor to rotate;
The relay 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 dividing circuit;
The pre-drive IC controls the inverter to switch according to a sequential logic strategy by receiving a PWM instruction of the MCU;
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 relay includes three MOSFETs respectively connected in series to three phase inputs of the motor.
In another aspect, the present invention provides a method for detecting a MOSFET short-circuit fault in a three-phase bridge inverter circuit, including:
Step S1, when a three-phase bridge inverter is electrified and a MOSFET does not have a fault, monitoring the normal state voltage of a motor terminal through an MCU module;
step S2, after the three-phase bridge inverter is electrified, 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 normal state voltage;
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.
Further, the short-circuit faults of the MOSFETs of the three-phase bridge inverter circuit in the step S3 include an inverter upper bridge MOSFET and a relay short-circuit fault and an inverter lower bridge MOSFET short-circuit fault.
Further, the method for detecting the short-circuit fault of the relay specifically comprises the following steps:
When the MOSFETs do not fail after power-on, each MOSFET of the inverter is in an OFF state, the successive electrical appliance is in an OFF state, 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:
Wherein delta ADC is ADC reading error, vmcu is MCU supply voltage, m is ADC sampling bit number, R1 is upper side voltage dividing resistor, R2 is lower side voltage dividing resistor, R3 is pull-up resistor;
When the U-shaped relay is short-circuited, current flows through the voltage dividing circuit to the ground through the pull-up resistor, at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal is a relay short-circuit fault alarm value, and the relay short-circuit fault alarm value Y1 is as follows:
Wherein Δadc is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, R3 is a pull-up resistor, vin is an input power supply voltage, and Δ Vmcu is an MCU supply voltage error;
When the V-phase relay or the W-phase relay is short-circuited, the current passes through the pull-up resistor to the motor coil and then passes through the voltage dividing circuit to the ground, and at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal is equal to the short-circuit fault alarm value Y1 of the phase relay.
Further, the method for detecting the short-circuit fault of the upper bridge MOSFET of the inverter specifically comprises the following steps:
when the bridge MOSFET of the inverter is short-circuited, current passes through the voltage dividing circuit to the ground through the short-circuited MOSFET, at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the bridge MOSFET short-circuit fault alarm value of the inverter, and the bridge MOSFET short-circuit fault alarm value Y2 of the inverter is as follows:
Y2>Y1;
Wherein Δadc is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, vin is an input supply voltage, and Δ Vmcu is an MCU supply voltage error.
Further, the detection conditions of the bridge MOSFET short-circuit fault of the inverter and the short-circuit fault of the relay 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< X1, the system judges that the system is normal;
when X1 is less than or equal to V0< Y1, the system judges that a short circuit fault of the relay occurs;
When Y1 is less than or equal to V0 and less than or equal to Y2, the system judges that the short circuit fault of the bridge MOSFET on the inverter occurs.
Further, the method for detecting the 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 failure, each MOSFET of the inverter is in an OFF state, the successive electrical appliance is in an OFF state, the pre-drive IC is in an open state, but does not send a drive command, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the normal system initialization voltage, and the normal system initialization voltage X2 is:
Wherein Ir is a pre-drive IC leakage current, deltaADC is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, vin is an input power supply voltage, delta Vmcu is an MCU supply voltage error,
When the short-circuit fault of the lower bridge MOSFET of the inverter occurs, the electric leakage current of the pre-drive IC flows into the ground through the short-circuit MOSFET, and at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal 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, delta ADC is ADC reading error, vmcu is MCU supply voltage, n is AD conversion digit, R1 is upper side bleeder resistor, R2 is downside bleeder resistor.
Further, under the condition that the pre-drive IC is opened, short-circuit fault detection of a lower bridge MOSFET of the inverter is carried out, and the real-time monitoring voltage value of the motor terminal monitored by the MCU module is set to be V0;
when Y3 is less than or equal to V0< X2, the system judges that the 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 DC brushless motor control inverter:
1. the inverter upper bridge MOSFET and the successive electrical appliance short circuit fault.
2. The inverter lower bridge MOSFET shorts out.
The phase voltages of three-phase input terminals of the motor U, V, W are input to the MCU through the voltage dividing circuit to monitor the voltages and judge whether the inverter and the motor work normally or not. The pull resistor is added to the motor single phase to be connected with a power supply, so that the monitoring voltage is different from the monitoring voltage in a normal state when a fault occurs, and the fault is detected. And detecting the occurrence of faults through the difference between the monitoring voltage in a normal state and the monitoring voltage in a fault state caused by leakage current when the pre-drive IC is opened. The MOSFET fault of the inverter is detected when the vehicle is started, so that the power-assisted loss during running is avoided, and the personal safety of a driver and passengers is ensured.
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 invention in the event of a U-phase relay short circuit fault;
FIG. 5 is an equivalent circuit of the V, W relay of the present invention at the time of a short circuit failure;
FIG. 6 is an equivalent circuit of the inverter upper bridge MOSFET of the present invention in the event of a short circuit fault;
FIG. 7 is an equivalent circuit of the system of the present invention in a normal state upon initialization;
fig. 8 is an equivalent circuit of the inverter lower bridge MOSFET of the present invention at the time of a short circuit failure.
Detailed Description
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments that are illustrated in the appended drawings.
Example 1
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-drive IC, an MCU module, an inverter, a relay, a motor, a pull-up resistor, and a voltage dividing circuit.
Specifically, the inverter is used for converting direct current 12V voltage of an input power supply into alternating current with variable frequency for the motor to work through the MOSFET high-speed switch, the motor is driven to rotate, and the inverter is a bridge circuit formed by six MOSFETs.
The relay comprises three MOSFETs respectively connected in series with the three-phase input ends of the motor, and the three MOSFETs are respectively connected in series with the U, V, W input ends of the three-phase motor. The relay 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, 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 a motor terminal through a voltage dividing circuit, the ADC in the MCU module performs AD sampling, and the voltage dividing circuit is formed by connecting an upper voltage dividing resistor R1 and a lower voltage dividing resistor R2 in series.
The pre-drive IC receives the PWM instruction of the MCU to control six MOSFETs of the inverter to perform switching operation according to a certain sequential logic strategy.
When the MOSFETs in the successive electrical appliances have short-circuit faults, the power supply current flows through the motor coil through the pull-up resistor and then flows through the short-circuit MOSFETs, and voltage is generated on the voltage dividing circuit, so that the short-circuit state can be detected.
As shown in FIG. 2, in this embodiment, a pull-up resistor R3 is added to the single-phase input end of the motor and connected to a power supply, and the voltage of the motor terminal is sampled and collected by an MCU module ADC, when a short-circuit fault of the successive electrical appliance occurs, the power supply current flows through the motor coil through the pull-up resistor and then flows through the short-circuited successive electrical appliance MOSFET, and when the bridge MOSFET of the inverter is short-circuited, the current flows to the ground through the voltage dividing circuit through the short-circuited bridge MOSFET of the inverter, 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 supplies power but does not output, the output pin of the pre-drive IC generates tiny leakage current, and according to the characteristic, the invention supplies power to the pre-drive IC when the system is electrified and initialized, but the MCU does not send PWM instructions to enable the pre-drive IC to work, and whether the MOSFET of the lower bridge of the inverter is short-circuited is judged according to the voltage generated by the leakage current on the sampling resistor.
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:
Step S1, when a three-phase bridge inverter is electrified and a MOSFET does not have a fault, monitoring the normal state voltage of a motor terminal through an MCU module;
step S2, after the three-phase bridge inverter is electrified, 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 normal state voltage;
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, a relay short-circuit fault, and an inverter lower bridge MOSFET short-circuit fault.
Specifically, the method for detecting the short-circuit fault of the relay specifically comprises the following steps:
Fig. 3 is an equivalent circuit when the MOSFET fails after power-up, at this time, each MOSFET of the inverter is in an OFF state, the successive electrical appliance is in an OFF state, the pre-drive IC is in an OFF state, the motor terminal voltage monitored by the MCU module is equal to ground, and the error caused by ADC reading error and LSB conversion is considered, at this time, the real-time monitoring voltage of the motor terminal monitored by the MCU module is the normal power-up voltage of the system, and the normal power-up voltage X1 of the system is:
Wherein delta ADC is ADC reading error, vmcu is MCU supply voltage, m is ADC sampling bit number, R1 is upper side voltage dividing resistor, R2 is lower side voltage dividing resistor, R3 is pull-up resistor;
fig. 4 is an equivalent circuit of a U-phase relay in a short-circuit fault, when the U-phase relay is short-circuited, a current flows through the voltage dividing circuit to the ground through the pull-up resistor, and at this time, the MCU module monitors that the real-time monitoring voltage of the motor terminal is a short-circuit fault alarm value of the U-phase relay, and the short-circuit fault alarm value Y1 of the U-phase relay is:
Wherein Δadc is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, R3 is a pull-up resistor, vin is an input power supply voltage, and Δ Vmcu is an MCU supply voltage error;
Fig. 5 is an equivalent circuit of the V-phase and W-phase relay in case of short-circuit fault, when the V-phase and W-phase relay are short-circuited, the current flows to the motor coil through the pull-up resistor and then flows to the ground through the voltage dividing circuit, because the internal resistance of the motor coil is negligible compared with that of the pull-up resistor, 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 relay.
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 of the inverter upper bridge MOSFET in the case of a short circuit, when the inverter upper bridge MOSFET is short-circuited, a current flows to the ground through the voltage dividing circuit via the short-circuited MOSFET, and at this time, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the alarm value of the inverter upper bridge MOSFET short circuit fault, and the alarm value Y2 of the inverter upper bridge MOSFET short circuit fault is:
Y2>Y1;
Compared with the real-time monitoring voltage Y1 monitored when the relay is short-circuited, the real-time monitoring voltage Y2 of the upper bridge MOSFET is much higher when the upper bridge MOSFET is short-circuited;
Wherein Δadc is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, vin is an input supply voltage, and Δ Vmcu is an MCU supply voltage error.
In summary, the detection conditions of the short-circuit fault of the upper bridge MOSFET of the inverter and the short-circuit fault of the relay 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< X1, the system judges that the system is normal;
when X1 is less than or equal to V0< Y1, the system judges that a short circuit fault of the relay occurs;
When Y1 is less than or equal to V0 and less than or equal to Y2, the system judges that the short circuit fault of the bridge MOSFET on the inverter occurs.
Specifically, the method for detecting the short-circuit fault of the lower bridge MOSFET of the inverter in the step S3 specifically comprises the following steps:
Fig. 7 is an equivalent loop of the inverter and the motor in a normal state when the system is initialized after the power-on, when the MOSFETs are not failed, each MOSFET of the inverter is in an OFF state, the successive electrical appliance is in an OFF state, the pre-driving IC is in an on state, but does not send a driving instruction, at this time, 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:
Wherein Ir is a pre-drive IC leakage current, deltaADC is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, vin is an input power supply voltage, delta Vmcu is an MCU supply voltage error,
Fig. 8 is an equivalent circuit of the inverter under-bridge MOSFET short-circuit fault, when the inverter under-bridge MOSFET short-circuit fault occurs, the leakage current of the pre-drive IC flows into the ground through the short-circuited MOSFET, and at this time, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the inverter under-bridge MOSFET short-circuit fault alarm value, and the inverter under-bridge MOSFET short-circuit fault alarm value Y3 is:
Wherein, delta ADC is ADC reading error, vmcu is MCU supply voltage, n is AD conversion digit, R1 is upper side bleeder resistor, R2 is downside bleeder resistor.
In summary, under the condition that the pre-drive IC is opened, short-circuit fault detection of the lower bridge MOSFET of the inverter is carried out, and the real-time monitoring voltage value of the motor terminal monitored by the MCU module is set as V0;
when Y3 is less than or equal to V0< X2, the system judges that the short circuit fault of the lower bridge MOSFET of the inverter occurs.
The technical problems, technical solutions and advantageous effects solved by the present invention have been further described in detail in the above-described embodiments, and it should be understood that the above-described embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the scope of protection of the present invention.
Claims (1)
1. The MOSFET short-circuit fault detection method of the three-phase bridge inverter circuit is characterized by comprising the following steps of:
Step S1, when a three-phase bridge inverter is electrified and a MOSFET does not have a fault, monitoring the normal state voltage of a motor terminal through an MCU module;
step S2, after the three-phase bridge inverter is electrified, 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 normal state voltage;
Step 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 the step S3 comprise an inverter upper bridge MOSFET, a relay short-circuit fault and an inverter lower bridge MOSFET short-circuit fault;
the method for detecting the short-circuit fault of the relay specifically comprises the following steps:
When the MOSFETs do not fail after power-on, each MOSFET of the inverter is in an OFF state, the successive electrical appliance is in an OFF state, 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:
Wherein delta ADC is ADC reading error, vmcu is MCU supply voltage, m is ADC sampling bit number, R1 is upper side voltage dividing resistor, R2 is lower side voltage dividing resistor, R3 is pull-up resistor;
When the U-shaped relay is short-circuited, current flows through the voltage dividing circuit to the ground through the pull-up resistor, at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal is a relay short-circuit fault alarm value, and the relay short-circuit fault alarm value Y1 is as follows:
Wherein Δadc is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, R3 is a pull-up resistor, vin is an input power supply voltage, and Δ Vmcu is an MCU supply voltage error;
When the V-relay or the W-relay is short-circuited, the current passes through the pull-up resistor to the motor coil and then passes through the voltage dividing circuit to the ground, and at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal is equal to the short-circuit fault alarm value Y1 of the relay;
the method for detecting the short-circuit fault of the bridge MOSFET of the inverter specifically comprises the following steps:
when the bridge MOSFET of the inverter is short-circuited, current passes through the voltage dividing circuit to the ground through the short-circuited MOSFET, at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the bridge MOSFET short-circuit fault alarm value of the inverter, and the bridge MOSFET short-circuit fault alarm value Y2 of the inverter is as follows:
Y2>Y1;
Wherein Δadc is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, vin is an input power supply voltage, and Δ Vmcu is an MCU supply voltage error;
The detection conditions of the bridge MOSFET short-circuit fault of the inverter and the short-circuit fault of the relay 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< X1, the system judges that the system is normal;
when X1 is less than or equal to V0< Y1, the system judges that a short circuit fault of the relay occurs;
when Y1 is less than or equal to V0 and less than or equal to Y2, the system judges that the short circuit fault of the upper bridge MOSFET of the inverter occurs;
The method for detecting the short-circuit fault of the lower bridge MOSFET 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 failure, each MOSFET of the inverter is in an OFF state, the successive electrical appliance is in an OFF state, the pre-drive IC is in an open state, but does not send a drive command, the MCU module monitors that the real-time monitoring voltage of the motor terminal is the normal system initialization voltage, and the normal system initialization voltage X2 is:
Wherein Ir is a pre-drive IC leakage current, deltaADC is an ADC reading error, vmcu is an MCU supply voltage, m is an ADC sampling bit number, R1 is an upper side voltage dividing resistor, R2 is a lower side voltage dividing resistor, vin is an input power supply voltage, delta Vmcu is an MCU supply voltage error,
When the short-circuit fault of the lower bridge MOSFET of the inverter occurs, the electric leakage current of the pre-drive IC flows into the ground through the short-circuit MOSFET, and at the moment, the MCU module monitors that the real-time monitoring voltage of the motor terminal 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, delta ADC is ADC reading error, vmcu is MCU supply voltage, n is AD conversion digit, R1 is upper voltage dividing resistor, R2 is lower voltage dividing resistor;
detecting short-circuit faults of a lower bridge MOSFET of the inverter under the condition that the pre-drive IC is opened, and setting the real-time monitoring voltage value of the motor terminal monitored by the MCU module as V0;
when Y3 is less than or equal to V0< X2, the system judges that the short circuit fault of the lower bridge MOSFET of the inverter occurs.
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| CN202211202994.6A CN115421068B (en) | 2022-09-29 | 2022-09-29 | A MOSFET short-circuit fault detection system and method for a three-phase bridge inverter circuit |
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| CN202211202994.6A CN115421068B (en) | 2022-09-29 | 2022-09-29 | A MOSFET short-circuit fault detection system and method for a three-phase bridge inverter circuit |
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| 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 |
| CN118566725B (en) * | 2024-07-31 | 2024-10-29 | 深圳市全芯科技集团有限公司 | Motor detection circuit of breathing machine |
| CN118920409A (en) * | 2024-10-09 | 2024-11-08 | 天津德星智能科技有限公司 | Protection method and system for EPS system phase breaker |
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| JP5813167B2 (en) * | 2014-04-01 | 2015-11-17 | 三菱電機株式会社 | Inverter fail-safe device |
| JP6274365B2 (en) * | 2015-08-19 | 2018-02-07 | 日本精工株式会社 | Electronic control device and electric power steering device equipped with the same |
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| JP2019187187A (en) * | 2018-04-17 | 2019-10-24 | 日本電産エレシス株式会社 | Failure diagnosis method for inverter circuit |
| CN114614688A (en) * | 2020-12-03 | 2022-06-10 | 日立安斯泰莫汽车系统(苏州)有限公司 | Protection devices for inverters, inverter systems and electric vehicles |
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| CN103744013A (en) * | 2014-01-21 | 2014-04-23 | 上海新世纪机器人有限公司 | Full control bridge circuit fault diagnosis method |
| CN103825505A (en) * | 2014-02-21 | 2014-05-28 | 太仓航创自动化科技有限公司 | Topology reconstruction method of brushless direct-current motor fault-tolerant inverter |
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