A three-phase bridge MOSFET fault detection device and method

Abstract

The present invention relates to the field of electronic circuit technology, and in particular to a fault detection device and method for a three-phase bridge MOSFET, wherein a pre-driver IC is connected to an MCU module, the three-phase bridge inverter is connected to the pre-driver IC, and the MCU module is connected to a terminal voltage detection circuit through a voltage divider circuit; the three-phase bridge inverter is used to convert an input power supply into a variable frequency alternating current for a load to operate, and drive the load to operate; the pre-driver IC controls the MOSFET in the three-phase bridge inverter to switch according to a timing logic strategy by receiving a PWM instruction from the MCU module; the MCU module is used to monitor and analyze a terminal voltage signal during an initialization phase. Compared with the prior art, the fault detection device and method for a three-phase bridge MOSFET of the present invention can quickly and accurately detect MOSFET faults during the power-on initialization phase of a three-phase bridge circuit, so as to improve the reliability and safety of the three-phase bridge circuit and reduce the impact of faults on the system.

Description

Technical field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a fault detection device and method for a three-phase bridge MOSFET. [Background Technology]

[0002] Brushless motors are typically driven using a three-phase bridge circuit. MOSFETs are key power devices, and their operating state directly impacts the motor's proper operation. Because MOSFETs operate at high switching speeds and are subject to high voltage and current stresses, they are prone to failures such as short circuits and open circuits. Therefore, MOSFET fault detection during the power-up initialization phase is crucial to promptly detect faults and prevent further damage to the motor and the entire system.

[0003] The existing technology for MOSFET fault detection has the following defects:

[0004] 1. The detection circuit is complex and difficult to implement in the product;

[0005] 2. There is no static initialization detection, which poses a security risk;

[0006] 3. It is not possible to fully detect various MOSFET faults during power-on and initialization. [Summary of the invention]

[0007] In order to overcome the above problems, the present invention proposes a three-phase bridge MOSFET fault detection device and method that can effectively solve the above problems.

[0008] The present invention provides a technical solution to solve the above-mentioned technical problems: providing a three-phase bridge MOSFET fault detection device and method, including an MCU module, a pre-driver IC, a three-phase bridge inverter, a voltage divider circuit and a terminal voltage detection circuit, wherein the pre-driver IC is connected to the MCU module, the three-phase bridge inverter is connected to the pre-driver IC, and the MCU module is connected to the terminal voltage detection circuit via the voltage divider circuit; the three-phase bridge inverter is used to convert input power into variable-frequency AC power for load operation, thereby driving the load to operate; the pre-driver IC controls the MOSFET in the three-phase bridge inverter to perform switching operations according to a timing logic strategy by receiving PWM instructions from the MCU module; and the MCU module is used to monitor and analyze the terminal voltage signal during the initialization phase.

[0009] Preferably, the three-phase bridge MOSFET fault detection device further includes an input power supply, wherein the input power supply is connected to a three-phase bridge inverter, and the three-phase bridge inverter is connected to a load, and the load is a brushless DC motor.

[0010] Preferably, the MCU module adopts an STM32 microprocessor as the main control chip, utilizes the DMA function of the STM32 microprocessor, continuously performs ADC sampling of the terminal voltage of the brushless motor, and simultaneously adopts a mean filtering algorithm to process the sampled terminal voltage signal, processes the zero-crossing signal in the main control chip, and utilizes the zero-crossing signal to realize the operation of the brushless motor.

[0011] Preferably, the fault detection device for the three-phase bridge MOSFET further includes a current detection circuit, and the current detection circuit is connected to the load and the MCU module respectively.

[0012] Preferably, the three-phase bridge inverter includes a MOSFET tube Q1, a MOSFET tube Q2, a MOSFET tube Q3, a MOSFET tube Q4, a MOSFET tube Q5 and a MOSFET tube Q6, the MOSFET tube Q1 is connected to the MOSFET tube Q4, the MOSFET tube Q2 is connected to the MOSFET tube Q5, and the MOSFET tube Q3 is connected to the MOSFET tube Q6.

[0013] Preferably, the MOSFET tube Q1 and the MOSFET tube Q4 are connected to the U phase, the MOSFET tube Q3 and the MOSFET tube Q6 are connected to the V phase, and the MOSFET tube Q2 and the MOSFET tube Q5 are connected to the W phase.

[0014] A method for detecting a fault in a three-phase bridge MOSFET comprises the following steps:

[0015] Step S1: After the system is powered on, in the initialization phase, the pre-driver IC is in the off state, and all MOSFETs in the three-phase bridge inverter are in the off state;

[0016] Step S2: Input the detected terminal voltage signal to the ADC port of the MCU module through the terminal voltage detection circuit and the voltage divider circuit, and the MCU module records the terminal voltage value at this time as the initial reference voltage;

[0017] Step S3: Turn on the MOSFETs of the three-phase bridge inverter and detect their terminal voltages in sequence, and compare the terminal voltages with the values ​​in the normal state to determine whether a fault exists.

[0018] Preferably, in step S2, when power is turned on, each MOSFET is in the off state, and the terminal voltage value is detected at this time. If the MOSFET is not short-circuited, the detected terminal voltage is within a specific voltage range U ref ±Δ;

[0019] In step S2, if the reference voltage is VCC±Δ at this time, it means that the upper bridge of this bridge arm is short-circuited, and if the reference voltage is 0V~Δ, it means that the lower bridge of this bridge arm is open-circuited.

[0020] Preferably, in step S3, the MOSFETs are turned on in sequence respectively. When Q1 is turned on alone, the terminal voltage of the U phase is VCC±Δ; when Q3 is turned on alone, the terminal voltage of the V phase is VCC±Δ; when Q5 is turned on alone, the terminal voltage of the W phase is VCC±Δ; when Q4 is turned on alone, the terminal voltage of the U phase is 0V~Δ; when Q6 is turned on alone, the terminal voltage of the V phase is 0V~Δ; when Q2 is turned on alone, the terminal voltage of the W phase is 0V~Δ; if the actual detection result does not match the above normal state, it is judged that the corresponding MOSFET is in a fault state.

[0021] Preferably, in step S3, if a fault is determined to have occurred, the MCU module may record the fault information and take corresponding measures.

[0022] Compared with the prior art, the three-phase bridge MOSFET fault detection device and method of the present invention can quickly and accurately detect MOSFET faults during the power-on initialization stage of the three-phase bridge circuit, thereby improving the reliability and safety of the three-phase bridge circuit and reducing the impact of the fault on the system.

Brief Description of the Drawings

[0023] Figure 1 This is a structural block diagram of a fault detection device for a three-phase bridge MOSFET according to the present invention;

[0024] Figure 2 A schematic diagram of a three-phase bridge inverter circuit of a three-phase bridge MOSFET fault detection device according to the present invention;

[0025] Figure 3 This is a schematic diagram of a terminal voltage detection circuit of a three-phase bridge MOSFET fault detection device according to the present invention;

[0026] Figure 4 Flowchart of the fault detection method of the three-phase bridge MOSFET of the present invention. [Specific implementation method]

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] It should be noted that in the embodiment of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0029] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0030] See also Figures 1 to 4 The fault detection device of the three-phase bridge MOSFET of the present invention includes an MCU module, a pre-driver IC, a three-phase bridge inverter, a voltage divider circuit and a terminal voltage detection circuit. The pre-driver IC is connected to the MCU module, the three-phase bridge inverter is connected to the pre-driver IC, and the MCU module is connected to the terminal voltage detection circuit through the voltage divider circuit.

[0031] The three-phase bridge inverter includes a bridge circuit composed of six MOSFETs, which is used to convert input power into frequency-variable alternating current for load operation, thereby driving the load to operate.

[0032] The pre-driver IC controls the MOSFETs in the three-phase bridge inverter to perform switching operations according to a certain timing logic strategy by receiving PWM instructions from the MCU module.

[0033] The MCU module is used for non-inductive back electromotive force voltage detection of the brushless motor and is used to monitor and analyze terminal voltage signals during the initialization phase to detect MOSFET faults.

[0034] The MCU module adopts an STM32 microprocessor as the main control chip, utilizes the DMA function of the STM32 microprocessor, continuously performs ADC sampling on the terminal voltage of the brushless motor, and simultaneously adopts a mean filtering algorithm to process the sampled terminal voltage signal, processes the zero-crossing signal in the main control chip, and utilizes the zero-crossing signal to realize the operation of the brushless motor.

[0035] The MCU module includes two A / D sampling modules, and the two A / D sampling modules are respectively connected to the terminal voltage detection circuit and the current detection module.

[0036] The A / D sampling module connected to the terminal voltage detection circuit is connected to a signal processing module, the signal processing module is connected to a zero-crossing signal detection module of the phase-changing module, and the zero-crossing signal detection module is connected to the phase-changing module.

[0037] The MCU module includes a speed PID module and a PWM output module. The speed PID module and the phase-changing module are respectively connected to the PWM output module, and the PWM output module is connected to the pre-driver IC.

[0038] The three-phase bridge MOSFET fault detection device of the present invention further includes an input power supply connected to a three-phase bridge inverter, and the three-phase bridge inverter is connected to a load, wherein the load is a brushless DC motor.

[0039] The fault detection device for a three-phase bridge MOSFET of the present invention further comprises a current detection circuit, which is connected to the load and the MCU module respectively.

[0040] The three-phase bridge inverter includes a MOSFET tube Q1, a MOSFET tube Q2, a MOSFET tube Q3, a MOSFET tube Q4, a MOSFET tube Q5 and a MOSFET tube Q6. The MOSFET tube Q1 is connected to the MOSFET tube Q4, the MOSFET tube Q2 is connected to the MOSFET tube Q5, and the MOSFET tube Q3 is connected to the MOSFET tube Q6.

[0041] The MOSFET tube Q1 and the MOSFET tube Q4 are connected to the U phase, the MOSFET tube Q3 and the MOSFET tube Q6 are connected to the V phase, and the MOSFET tube Q2 and the MOSFET tube Q5 are connected to the W phase.

[0042] The terminal voltage detection circuit includes three groups of resistors R1 and R2 connected in series, and two ends of the three resistors R2 are connected to capacitors C1 respectively.

[0043] The voltage dividing circuit includes a voltage dividing resistor.

[0044] The fault detection method of the three-phase bridge MOSFET of the present invention comprises the following steps:

[0045] Step S1: After the system is powered on, in the initialization stage, the pre-driver IC is in the off state, and all MOSFETs in the three-phase bridge inverter are in the off state.

[0046] Step S2: The detected terminal voltage signal is input to the ADC port of the MCU module through the terminal voltage detection circuit and the voltage divider circuit. The MCU module records the terminal voltage value at this time as the initial reference voltage U ref ±Δ.

[0047] In step S2, when power is turned on, each MOSFET is in the off state. At this time, the terminal voltage value is detected. If the MOSFET is not short-circuited, the detected terminal voltage is within a specific voltage range U ref ±Δ.

[0048] In step S2, if the reference voltage is VCC±Δ at this time, it means that the upper bridge of this bridge arm is short-circuited, and if the reference voltage is 0V~Δ, it means that the lower bridge of this bridge arm is open-circuited.

[0049] Step S3: Turn on the MOSFETs of the three-phase bridge inverter and detect their terminal voltages in sequence, and compare the terminal voltages with the values ​​in the normal state to determine whether a fault exists.

[0050] In step S3, Q1 is turned on first. At this time, the MCU module detects the terminal voltage of the U phase through the ADC. If the detected voltage value is VCC±Δ, Q1 is normal; then Q3 is turned on to detect the terminal voltage of the V phase. If it is VCC±Δ, Q3 is normal; similarly, Q5, Q4, Q6, and Q2 are turned on separately and the terminal voltage is detected in turn. If they all meet the voltage values ​​under the above normal state, it is preliminarily determined that the three-phase bridge MOSFET is not faulty.

[0051] In step S3, if the terminal voltage of a MOSFET, when it is individually turned on, is not consistent with the normal state, the MOSFET is determined to be faulty. For example, if the U-phase terminal voltage is not VCC ± Δ when Q1 is individually turned on, Q1 is determined to be faulty. At this point, the MCU module can record the fault information and take appropriate measures, such as issuing an alarm signal or commanding the system to stop operation, to prevent the fault from escalating.

[0052] In step S3, the MOSFETs are turned on sequentially. When Q1 is turned on alone, the voltage at the U phase is VCC±Δ; when Q3 is turned on alone, the voltage at the V phase is VCC±Δ; when Q5 is turned on alone, the voltage at the W phase is VCC±Δ; when Q4 is turned on alone, the voltage at the U phase is 0V~Δ; when Q6 is turned on alone, the voltage at the V phase is 0V~Δ; and when Q2 is turned on alone, the voltage at the W phase is 0V~Δ. If the actual detection result does not match the normal state, the corresponding MOSFET is determined to be in a faulty state.

[0053] Compared with the prior art, the three-phase bridge MOSFET fault detection device and method of the present invention can timely detect MOSFET faults during the system power-on initialization stage, avoiding more serious impacts caused by the faults during system operation, thereby improving the reliability and safety of the system; through the precise measurement and analysis of the terminal voltages of each MOSFET when it is turned on individually, a single faulty MOSFET can be accurately located, which is conducive to rapid repair and maintenance of the circuit; the detection method is based on simple terminal voltage detection and comparison, does not require complex current detection and complex algorithms, is easy to implement and has a fast detection speed, which is conducive to rapid startup of the system.

[0054] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications, equivalent replacements and improvements made within the concept of the present invention should be included in the patent protection scope of the present invention.

Claims

1. A three-phase bridge MOSFET fault detection device, characterized in that: It includes an MCU module, a pre-driver IC, a three-phase bridge inverter, a voltage divider circuit and a terminal voltage detection circuit, wherein the pre-driver IC is connected to the MCU module, the three-phase bridge inverter is connected to the pre-driver IC, and the MCU module is connected to the terminal voltage detection circuit through the voltage divider circuit; The three-phase bridge inverter is used to convert the input power into variable frequency AC power for the load to operate, and drive the load to operate; The pre-driver IC controls the MOSFET in the three-phase bridge inverter to perform switching operation according to a sequential logic strategy by receiving a PWM instruction from the MCU module; The MCU module is used to monitor and analyze the terminal voltage signal during the initialization phase.

2. The three-phase bridge MOSFET fault detection device according to claim 1, characterized in that: The fault detection device for the three-phase bridge MOSFET also includes an input power supply, which is connected to the three-phase bridge inverter, and the three-phase bridge inverter is connected to a load, which is a brushless DC motor.

3. The three-phase bridge MOSFET fault detection device according to claim 2, characterized in that: The MCU module adopts an STM32 microprocessor as a main control chip, utilizes the DMA function of the STM32 microprocessor, continuously performs ADC sampling of the terminal voltage of the brushless motor, and simultaneously uses a mean filter algorithm to process the sampled terminal voltage signal, processes the zero-crossing signal in the main control chip, and utilizes the zero-crossing signal to realize the operation of the brushless motor.

4. The three-phase bridge MOSFET fault detection device according to claim 2, characterized in that: The fault detection device for the three-phase bridge MOSFET also includes a current detection circuit, and the current detection circuit is connected to the load and the MCU module respectively.

5. The three-phase bridge MOSFET fault detection device according to claim 1, characterized in that: The three-phase bridge inverter comprises a MOSFET tube Q1, a MOSFET tube Q2, a MOSFET tube Q3, a MOSFET tube Q4, a MOSFET tube Q5 and a MOSFET tube Q6, wherein the MOSFET tube Q1 is connected to the MOSFET tube Q4, the MOSFET tube Q2 is connected to the MOSFET tube Q5, and the MOSFET tube Q3 is connected to the MOSFET tube Q6.

6. The three-phase bridge MOSFET fault detection device according to claim 5, characterized in that: The MOSFET tube Q1 and the MOSFET tube Q4 are connected to the U phase, the MOSFET tube Q3 and the MOSFET tube Q6 are connected to the V phase, and the MOSFET tube Q2 and the MOSFET tube Q5 are connected to the W phase.

7. A three-phase bridge MOSFET fault detection method, characterized in that: The steps include: Step S1, after the system is powered on, in the initialization stage, the pre-driver IC is in a closed state, and all MOSFETs in the three-phase bridge inverter are in a turned-off state; Step S2, inputting the detected terminal voltage signal to the ADC port of the MCU module through the terminal voltage detection circuit and the voltage divider circuit, and the MCU module records the terminal voltage value at this time as the initial reference voltage; Step S3, turning on the MOSFET tubes of the three-phase bridge inverter separately and detecting the terminal voltage in sequence, comparing whether the terminal voltage value is consistent with the normal state value, so as to determine whether there is a fault.

8. The three-phase bridge MOSFET fault detection method according to claim 7, characterized in that: In step S2, when the power is turned on, each MOSFET is in the off state. At this time, the value of the terminal voltage is detected. If the MOSFET is not short-circuited, the detected terminal voltage is within a specific voltage range U ref ±Δ; In step S2, if the reference voltage is VCC±Δ at this time, it means that the upper bridge of this bridge arm is short-circuited, and if the reference voltage is 0V~Δ, it means that the lower bridge of this bridge arm is open-circuited.

9. The three-phase bridge MOSFET fault detection method according to claim 7, characterized in that: In the step S3, the MOSFETs are turned on in sequence respectively. When Q1 is turned on alone, the terminal voltage of the U phase is VCC±Δ; when Q3 is turned on alone, the terminal voltage of the V phase is VCC±Δ; when Q5 is turned on alone, the terminal voltage of the W phase is VCC±Δ; when Q4 is turned on alone, the terminal voltage of the U phase is 0V~Δ; when Q6 is turned on alone, the terminal voltage of the V phase is 0V~Δ; when Q2 is turned on alone, the terminal voltage of the W phase is 0V~Δ; if the actual detection result does not match the above normal state, it is judged that the corresponding MOSFET is in a fault state.

10. The three-phase bridge MOSFET fault detection method according to claim 7, characterized in that: In step S3, it is determined that a fault occurs, and the MCU module can record the fault information and take corresponding measures.

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