H-bridge circuit temperature monitoring system and method

Abstract

The application discloses an H-bridge circuit temperature monitoring system, comprising a temperature sensing module and a control module; the temperature sensing module comprises a test power supply, a first temperature sensing circuit and a second temperature sensing circuit; the first temperature sensing circuit and the second temperature sensing circuit are connected in parallel between the test power supply and the control module, and are used for respectively generating a first monitoring current and a second monitoring current input to the control module according to a test voltage provided by the test power supply; both the temperature sensing circuits comprise thermistors, and the two thermistors are respectively used for sensing the temperatures of two field effect tubes on both sides of the H-bridge circuit and changing resistance values when the temperatures change, so that the monitoring currents change; the control module is used for calculating the temperatures of the field effect tubes of the H-bridge circuit sensed by the thermistors according to the current changes. The application further discloses a corresponding H-bridge circuit temperature monitoring method.

Description

Technical Field

[0001] This invention belongs to the field of automotive electronics technology, and relates to a temperature monitoring system, and more particularly to a temperature monitoring system and method for field-effect transistors in an H-bridge circuit. Background Technology

[0002] In the field of automotive electronics, the H-bridge circuit is a classic circuit for driving DC motors. Traditional H-bridge circuits drive the motor's rotation by controlling the conduction and cutoff of relevant field-effect transistors (FETs), achieving forward and reverse rotation. To ensure the FETs conduct and cut off as needed, a corresponding control circuit is generally required for the H-bridge circuit. This integrated circuit has the advantages of simple circuit structure and fewer external components; however, such circuits also have certain drawbacks. They cannot withstand large currents, and when the current increases, the FETs overheat significantly, easily causing safety hazards. Existing technologies mainly focus on the functional implementation of the H-bridge circuit, such as its control methods, checking for open circuits and short circuits; or on reducing the power consumption of the H-bridge circuit, allowing it to operate at lower power; and some focus on monitoring the operating current of the H-bridge circuit. However, the problem of severe FET overheating in H-bridge circuits is rarely mentioned in existing technologies. Current technologies lack effective temperature monitoring measures for the FETs in H-bridge circuits, leading to malfunctions in practical applications due to FET overheating. Summary of the Invention

[0003] Based on the above problems, the purpose of this invention is to provide an H-bridge circuit temperature monitoring system and method, which can monitor the temperature of the H-bridge circuit in real time and avoid safety hazards caused by failure to deal with abnormal H-bridge circuit temperature in a timely manner.

[0004] This invention provides a temperature monitoring system for an H-bridge circuit, comprising a temperature sensing module and a control module. The temperature sensing module includes a test power supply, a first temperature sensing circuit, and a second temperature sensing circuit. The first and second temperature sensing circuits are connected in parallel between the test power supply and the control module, and are used to generate a first monitoring voltage and a second monitoring voltage input to the control module based on the test voltage provided by the test power supply. The first temperature sensing circuit includes a first thermistor, and the second temperature sensing circuit includes a second thermistor. The first and second thermistors are used to sense the temperature of the field-effect transistors in the H-bridge circuit and change their resistance values ​​when the temperature changes, so that the first and second monitoring voltages change respectively. The control module is used to acquire the first and second monitoring voltages and calculate the temperature of the field-effect transistors in the H-bridge circuit sensed by the first and second thermistors based on the changes in the first and second monitoring voltages.

[0005] In some embodiments, the effective temperature sensing range of both the first thermistor and the second thermistor is -55°C to 155°C.

[0006] In some embodiments, the first temperature sensing circuit of the temperature sensing module includes a first thermistor, a first fixed resistor, a first capacitor, and a first sensing terminal. The first thermistor has one end electrically connected to one end of the first fixed resistor, and the other end is grounded. The other end of the first fixed resistor is connected to the test power supply. The first sensing terminal is led out from between the first thermistor and the first fixed resistor. The first capacitor is electrically connected between the first sensing terminal and the grounded end of the first thermistor.

[0007] In some embodiments, the second temperature sensing circuit of the temperature sensing module includes a second thermistor, a second fixed resistor, a second capacitor, and a second sensing terminal. One end of the second thermistor is electrically connected to one end of the second fixed resistor, and the other end of the second thermistor is connected to the test power supply and the second H-bridge circuit temperature monitoring system. The other end of the fixed resistor is grounded. The second sensing terminal is led out from between the second thermistor and the second fixed resistor. The second capacitor is electrically connected between the second sensing terminal and the grounded end of the second fixed resistor.

[0008] In some embodiments, the control module includes an analog-to-digital converter (ADC) having a first ADC port and a second ADC port. The first sensing terminal is electrically connected to the first ADC port, and the second sensing terminal is electrically connected to the second ADC port. The ADC is used to acquire the first monitoring voltage and the second monitoring voltage through the first ADC port and the second ADC port, and to convert the first monitoring voltage and the second monitoring voltage into a first digital voltage signal and a second digital voltage signal.

[0009] In some embodiments, the control module further includes an MCU electrically connected to the analog-to-digital converter, which is used to calculate the temperatures of the first thermistor and the second thermistor based on the first digital voltage signal and the second digital voltage signal, and to use the calculated temperatures of the first thermistor and the second thermistor as the temperatures of the field-effect transistors in the H-bridge circuit.

[0010] The present invention also provides a method for monitoring the temperature of an H-bridge circuit, applied to the H-bridge circuit temperature monitoring system described above, comprising:

[0011] S1, the temperature sensing module uses the first temperature sensing circuit and the second temperature sensing circuit to sense the temperature change of the field-effect transistor in the H-bridge circuit, and generates a first monitoring voltage and a second monitoring voltage based on the sensed temperature change of the field-effect transistor; S2, the H-bridge circuit temperature monitoring system uses the control module to obtain the first monitoring voltage and the second monitoring voltage, and calculates the temperatures of the first thermistor and the second thermistor as the temperature of the field-effect transistor in the H-bridge circuit based on the first monitoring voltage and the second monitoring voltage; S3, the H-bridge circuit temperature monitoring system automatically determines whether the temperature of the field-effect transistor in the H-bridge circuit is within a preset safe temperature range.

[0012] In some embodiments, step S2 further includes: dividing a preset test temperature range into multiple test temperature intervals according to a preset temperature change gradient, and testing the voltage values ​​of the first monitoring voltage and the second monitoring voltage in each test temperature interval; the H-bridge circuit temperature monitoring system establishes and stores a voltage-temperature relationship table based on the correspondence between the voltage values ​​of the first monitoring voltage and the second monitoring voltage in each test temperature interval and each test temperature interval; the H-bridge circuit temperature monitoring system uses the control module to obtain the real-time voltage value of at least one of the first monitoring voltage and the second monitoring voltage, and determines the test temperature interval corresponding to the real-time voltage value of at least one of the first monitoring voltage and the second monitoring voltage according to the voltage-temperature relationship table, and determines the temperature of at least one of the first thermistor and the second thermistor according to the test temperature interval, and uses it as the temperature of at least one field-effect transistor of the H-bridge circuit.

[0013] In some embodiments, determining the temperature of at least one of the first thermistor and the second thermistor based on the test temperature range includes:

[0014] According to the order of temperature from low to high, the real-time voltage value of the first monitoring voltage is compared with the voltage value corresponding to each test temperature interval in the voltage-temperature relationship table; when the voltage value corresponding to the test temperature interval that is the largest among all voltage values ​​corresponding to the test temperature interval that is less than the real-time voltage value of the first monitoring voltage is the voltage value corresponding to the nth test temperature interval, the upper limit of the nth test temperature interval is determined as the temperature of the first thermistor, and is used as the temperature of the field-effect transistor of the H-bridge circuit whose temperature is sensed by the first thermistor.

[0015] In some embodiments, determining the temperature of at least one of the first thermistor and the second thermistor based on the test temperature range further includes:

[0016] According to the order of temperature from low to high, the real-time voltage value of the second monitoring voltage is compared with the voltage value corresponding to each test temperature interval in the voltage-temperature relationship table; when the smallest voltage value corresponding to the test temperature interval that is greater than the real-time voltage value of the second monitoring voltage is the voltage value corresponding to the nth test temperature interval, the upper limit of the nth test temperature interval is determined as the temperature of the second thermistor, and is used as the temperature of the field-effect transistor of the H-bridge circuit whose temperature is sensed by the second thermistor.

[0017] Compared to existing technologies, the H-bridge circuit temperature monitoring system provided by this invention connects a fixed resistor and a thermistor in a specific manner and arranges the thermistor close to the field-effect transistor (FET) of the H-bridge circuit. This arrangement equates the temperature of the thermistor to the temperature of the FET. Since the resistance of the thermistor is highly sensitive to temperature changes, this method allows for precise monitoring of the FET temperature, achieving real-time and accurate monitoring of the FET temperature in the H-bridge circuit. Furthermore, by establishing a voltage-temperature relationship table within a preset temperature range and comparing the real-time monitoring voltage with this table to derive the real-time FET temperature, accurate temperature calculation ensures that the H-bridge circuit operates within a safe temperature range. In addition, the first and second temperature sensing circuits in the H-bridge circuit temperature monitoring system provided by this invention form a dual-channel complementary temperature sensing circuit. The advantage of using a dual-channel complementary temperature sensing circuit is that, at the same temperature, the sum of the first and second monitoring voltages generated by the first and second temperature sensing circuits should be constantly equal to the voltage of the test power supply. This characteristic can be used to conveniently determine whether a fault has occurred in the H-bridge circuit. For example, when the sum of the first monitoring voltage and the second monitoring voltage is not equal to the voltage of the test power supply, and the deviation is greater than the preset allowable deviation range, it can be directly determined that the H-bridge circuit has failed and reported as soon as possible. The advantage of using a dual-channel complementary sampling circuit is that when one temperature sensing circuit fails, the other temperature sensing circuit can still work normally and can still maintain the monitoring of the temperature of the H-bridge circuit. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1A functional block diagram of an H-bridge circuit temperature monitoring system according to a preferred embodiment of one aspect of the present invention;

[0020] Figure 2 for Figure 1 The circuit diagrams of the first and second temperature sensing circuits of the H-bridge circuit temperature monitoring system are shown.

[0021] Figure 3 for Figure 1 The diagram shows the relationship between the first and second monitoring voltages and the temperature generated by the H-bridge circuit temperature monitoring system during operation.

[0022] Figure 4 This is a flowchart of a preferred embodiment of an H-bridge circuit temperature monitoring method according to another aspect of the present invention. Detailed Implementation

[0023] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of preferred embodiments with reference to the accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the present invention; some well-known parts may not be shown. In the various drawings, the same elements are represented by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0025] An embodiment of the present invention provides a functional block diagram of an H-bridge circuit temperature monitoring system, such as... Figure 1 As shown.

[0026] Specifically, the functional module diagram includes a temperature sensing module 1 and a control module 2. The temperature sensing module includes a first temperature sensing circuit 11 and a second temperature sensing circuit 12. The control module 2 includes a first analog-to-digital conversion port 21 and a second analog-to-digital conversion port 22, as well as an MCU 23. The first temperature sensing circuit 11 has a first sensing terminal A, the second temperature sensing circuit 12 has a second sensing terminal B, and the control module 2 has two analog-to-digital conversion ports 2a and 2b. The first sensing terminal A of the first temperature sensing circuit 11 and the second sensing terminal B of the second temperature sensing circuit 12 are electrically connected to the two analog-to-digital conversion ports 2a and 2b of the control module, respectively, for converting the voltage across the first thermistor and the second thermistor sensed by the first temperature sensing terminal A and the second temperature sensing terminal B into digital voltages and transmitting them to the MCU 23, and finally converting the digital voltage values ​​into corresponding temperature values.

[0027] Specifically, the first temperature sensing terminal A is connected to the MCU 23 through the first analog-to-digital converter port 2a, and the second temperature sensing terminal B is connected to the MCU 23 through the second analog-to-digital converter port 2b. The MCU 23 reads the monitoring voltage values ​​of the first temperature sensing terminal A and the second temperature sensing terminal B in real time through the first analog-to-digital converter port 2a and the second analog-to-digital converter port 2b. The voltage values ​​of the first temperature sensing terminal A and the second temperature sensing terminal B are converted into the temperature values ​​corresponding to the voltage values.

[0028] It should be noted that, during the use of the H-bridge temperature sensing circuit in this embodiment, the first and second thermistors should be arranged close to each other, preferably in contact, with the field-effect transistor in the H-bridge circuit. The purpose is to make the temperature of the field-effect transistor monitored by the first and second thermistors infinitely close to the temperatures of the first and second thermistors. Therefore, the temperatures of the first and second thermistors can be considered equivalent to the temperature of the field-effect transistor, that is, the temperatures of the first and second thermistors can be considered equivalent to the temperature of the H-bridge circuit.

[0029] Please see Figure 2 , Figure 2 for Figure 1 The circuit diagrams shown are of the first and second temperature sensing circuits in the H-bridge circuit temperature monitoring system.

[0030] Specifically, the first temperature sensing circuit 11 includes a first test power supply U1, a first fixed resistor R1, a first thermistor NTC1, a first filter capacitor C1, and a first sensing terminal A; one end of the first thermistor is electrically connected to one end of the first fixed resistor, and the other end of the first thermistor is grounded; the other end of the first fixed resistor is connected to the test power supply; the first sensing terminal is led out from between the first thermistor and the first fixed resistor; the first capacitor is electrically connected between the first sensing terminal and the grounded end of the first thermistor.

[0031] Specifically, the second temperature sensing circuit 12 includes a second test power supply U2, a second fixed resistor R2, a second thermistor NTC2, a second filter capacitor C2, and a second sensing terminal B. In the second temperature sensing circuit, one end of the second thermistor is electrically connected to one end of the second fixed resistor, the other end of the second thermistor is connected to the test power supply, and the other end of the fixed resistor is grounded. The second sensing terminal is led out from between the second thermistor and the second fixed resistor. The second capacitor is electrically connected between the second sensing terminal and the grounded end of the second fixed resistor.

[0032] It should be noted that the voltage of the two test power supplies of the first temperature sensing circuit 11 and the second temperature sensing circuit 12 is the same, the first and second thermistors are of the same type, and the resistance values ​​of the first and second fixed resistors are also the same.

[0033] Specifically, the changes in the relationship between the first and second monitoring voltages and temperature are as follows: Figure 3 As shown.

[0034] Overall, based on the inherent characteristics of thermistors, the resistance values ​​of both the first and second thermistors decrease as the temperature increases.

[0035] Specifically, since the effective temperature range of both the first and second thermistors is -55℃ to 155℃, the preset effective operating temperature range of the H-bridge circuit temperature monitoring system is -55℃ to 155℃. In this embodiment, the temperature value can be -55℃ to 155℃; when the temperature is -55℃, the resistance of the thermistor is at its maximum, the voltage drop across the thermistor is at its maximum, and therefore the voltage at the first sensing terminal is at its maximum value. As the temperature gradually increases, the resistance of the thermistor gradually decreases, the voltage drop across the thermistor decreases, and the voltage at the first sensing terminal decreases.

[0036] Specifically, as the temperature rises, the voltage value of the second sensing terminal changes in the opposite direction to that of the first sensing terminal; when the temperature is -55℃, the resistance of the thermistor is at its maximum, the voltage drop of the fixed resistor is small, and therefore the voltage value of the second sensing terminal is at its minimum. As the temperature gradually rises, the resistance of the second thermistor decreases, the voltage drop of the fixed resistor increases, and therefore the voltage value of the second sensing terminal increases.

[0037] It should be noted that, since the first and second temperature sensing circuits are arranged complementaryly, the sum of the voltage values ​​at the first and second sensing terminals should be constant at the same temperature, equal to the voltage value of the test power supply. Since the MCU's range is 4595, therefore... Figure 3 The sum of the digital voltage values ​​of the first and second sensing terminals shown in the figure is always 4595.

[0038] Specifically, converting the voltage obtained by the temperature sensing circuit into the temperature of the H-bridge circuit includes the following steps:

[0039] Based on the effective temperature range of the thermistor, a normal operating effective temperature range for the H-bridge circuit monitoring system is preset, and this effective temperature range is used as the preset test temperature range. Within the preset temperature range, the system is divided into multiple test temperature intervals according to a preset temperature change gradient, and the voltage values ​​of the first monitoring voltage and the second monitoring voltage are measured in each test temperature interval. A voltage-temperature relationship table is established and stored based on the correspondence between the voltage values ​​of the first monitoring voltage and the second monitoring voltage in each test temperature interval and each test temperature interval. The control module is used to obtain the real-time voltage value of at least one of the first monitoring voltage and the second monitoring voltage, and the test temperature interval corresponding to the real-time voltage value of at least one of the first monitoring voltage and the second monitoring voltage is determined according to the voltage-temperature relationship table. The temperature of at least one of the first thermistor and the second thermistor is determined according to the test temperature interval and used as the temperature of at least one field-effect transistor in the H-bridge circuit.

[0040] It should be noted that in the voltage-temperature relationship table, one temperature value can correspond to multiple voltage values.

[0041] Please see Figure 4 Another embodiment of the present invention also provides a method for monitoring the temperature of an H-bridge circuit, which is applied to the H-bridge circuit temperature monitoring system described above;

[0042] The method includes:

[0043] S1, the H-bridge circuit temperature monitoring system uses the first temperature sensing circuit and the second temperature sensing circuit to sense the temperature change of the field-effect transistor of the H-bridge circuit respectively, and generates a first monitoring voltage and a second monitoring voltage according to the sensed temperature change of the field-effect transistor respectively.

[0044] S2, after the control module obtains the first monitoring voltage and the second monitoring voltage, it calculates the temperature of the first thermistor and the second thermistor based on the first monitoring voltage and the second monitoring voltage as the temperature of the field-effect transistor of the H-bridge circuit.

[0045] S3, determine whether the temperature of the field-effect transistor in the H-bridge circuit is within the preset safe temperature range.

[0046] Specifically, the step of determining the temperature of one of the first thermistor and the second thermistor based on the test temperature range includes:

[0047] After the MCU obtains the real-time voltage values ​​of the first monitoring voltage and the second monitoring voltage, it compares the real-time voltage value of the first monitoring voltage with the voltage value corresponding to each test temperature interval in the voltage-temperature relationship table, in order of temperature from low to high. When the largest voltage value among all voltage values ​​corresponding to the test temperature interval that is less than the real-time voltage value of the first monitoring voltage corresponds to the voltage value of the nth test temperature interval, the upper limit of the nth test temperature interval is determined as the temperature of the first thermistor, and is used as the temperature of the field-effect transistor of the H-bridge circuit whose temperature is sensed by the first thermistor.

[0048] Specifically, the step of determining the temperature of one of the first thermistors and the second thermistors based on the test temperature range includes:

[0049] After the MCU obtains the real-time voltage values ​​of the first monitoring voltage and the second monitoring voltage, it compares the real-time voltage value of the second monitoring voltage with the voltage value corresponding to each test temperature interval in the voltage-temperature relationship table, in order of temperature from low to high. When the smallest voltage value corresponding to the test temperature interval that is greater than the real-time voltage value of the second monitoring voltage is the voltage value corresponding to the nth test temperature interval, the upper limit of the nth test temperature interval is determined as the temperature of the second thermistor, and is used as the temperature of the field-effect transistor of the H-bridge circuit whose temperature is sensed by the second thermistor.

[0050] According to the method described above, the first and second thermistors are arranged close to, preferably in contact with, the field-effect transistor of the H-bridge circuit. Therefore, the temperatures of the first and second thermistors can be equivalent to the temperatures of the field-effect transistor, which is the temperature of the H-bridge circuit. The advantage of using a first and second temperature sensing circuit to monitor the voltages across the first and second thermistors and then converting the monitored voltages into corresponding temperatures is that the voltages across the first and second thermistors are highly sensitive to temperature changes. Therefore, the first and second temperature sensing circuits can sensitively capture the temperature changes of the first and second thermistors, thereby achieving real-time and accurate monitoring of the H-bridge circuit temperature and preventing malfunctions caused by abnormal temperatures.

[0051] In the description of this invention, unless otherwise expressly specified and limited, the terms "first," "second," etc., are used merely to distinguish elements with similar properties and not to indicate or imply relative importance or a particular order. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the listed elements but also other elements not expressly listed.

[0052] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An H-bridge circuit temperature monitoring system, characterized by, The temperature sensing module and the control module are included; The temperature sensing module includes a test power supply, a first temperature sensing circuit and a second temperature sensing circuit; the first temperature sensing circuit and the second temperature sensing circuit are connected in parallel between the test power supply and the control module, and are used for generating a first monitoring voltage and a second monitoring voltage input to the control module respectively according to a test voltage provided by the test power supply; the first temperature sensing circuit includes a first thermistor, and the second temperature sensing circuit includes a second thermistor; the first thermistor and the second thermistor are arranged close to or in contact with field effect tubes of an H-bridge circuit respectively, and are used for sensing temperatures of the field effect tubes of the H-bridge circuit and changing resistance values when the temperatures change so as to make the first monitoring voltage and the second monitoring voltage change respectively; The control module is used for acquiring the first monitoring voltage and the second monitoring voltage, and calculating the temperatures of the field effect tubes of the H-bridge circuit sensed by the first thermistor and the second thermistor according to changes of the first monitoring voltage and the second monitoring voltage. The first temperature sensing circuit further includes a first fixed resistor, a first capacitor and a first sensing terminal; one end of the first thermistor is electrically connected to one end of the first fixed resistor, and the other end of the first thermistor is grounded; the other end of the first fixed resistor is connected to the test power supply; the first sensing terminal is led out from between the first thermistor and the first fixed resistor; and the first capacitor is electrically connected between the first sensing terminal and the grounded end of the first thermistor. The second temperature sensing circuit further includes a second fixed resistor, a second capacitor and a second sensing terminal; one end of the second thermistor is electrically connected to one end of the second fixed resistor, and the other end of the second thermistor is connected to the test power supply; the other end of the fixed resistor is grounded; the second sensing terminal is led out from between the second thermistor and the second fixed resistor; and the second capacitor is electrically connected between the second sensing terminal and the grounded end of the second fixed resistor. The first temperature sensing circuit and the second temperature sensing circuit constitute a double-path complementary temperature sensing circuit; and the sum of the first monitoring voltage and the second monitoring voltage is equal to the voltage of the test power supply at the same temperature.

2. The H-bridge circuit temperature monitoring system of claim 1, wherein, The effective temperature sensing range of the first thermistor and the second thermistor is-55℃ to 155℃.

3. The H-bridge circuit temperature monitoring system of claim 1, wherein, The control module includes an analog-to-digital converter; the analog-to-digital converter has a first analog-to-digital conversion port and a second analog-to-digital conversion port; the first sensing terminal is electrically connected to the first analog-to-digital conversion port, and the second sensing terminal is electrically connected to the second analog-to-digital conversion port; and the analog-to-digital converter is used for acquiring the first monitoring voltage and the second monitoring voltage through the first analog-to-digital conversion port and the second analog-to-digital conversion port, and converting the first monitoring voltage and the second monitoring voltage into a first digital voltage signal and a second digital voltage signal.

4. The H-bridge circuit temperature monitoring system of claim 3, wherein, The control module further comprises an MCU electrically connected with the analog-to-digital converter, for calculating the temperature of the first and second thermistors according to the first and second digital voltage signals, and taking the calculated temperature of the first and second thermistors as the temperature of the field effect tube of the H-bridge circuit.

5. A method for monitoring temperature of an H-bridge circuit, applied to the temperature monitoring system of the H-bridge circuit according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: S1, sensing the temperature change of the field effect tube of the H-bridge circuit by using the first and second temperature sensing circuits respectively, and generating a first and second monitoring voltage respectively according to the sensed temperature change of the field effect tube; S2, acquiring the first and second monitoring voltages by using the control module, and calculating the temperature of the first and second thermistors as the temperature of the field effect tube of the H-bridge circuit according to the first and second monitoring voltages; S3, judging whether the temperature of the field effect tube of the H-bridge circuit is within a preset safe temperature range.

6. The method of claim 5, wherein, The step S2 comprises the following sub-steps: S21, dividing a preset test temperature range into a plurality of test temperature intervals according to a preset temperature change gradient, and testing the voltage value of the first and second monitoring voltages in each test temperature interval; S22, establishing and storing a voltage-temperature relationship table according to the correspondence between the voltage value of the first and second monitoring voltages in each test temperature interval and each test temperature interval; S23, acquiring the real-time voltage value of at least one of the first and second monitoring voltages by using the control module, determining the test temperature interval corresponding to the real-time voltage value of at least one of the first and second monitoring voltages according to the voltage-temperature relationship table, and determining the temperature of at least one of the first and second thermistors according to the test temperature interval, and taking the temperature of at least one of the first and second thermistors as the temperature of at least one field effect tube of the H-bridge circuit.

7. The method of claim 6, wherein, The step of determining the temperature of at least one of the first and second thermistors according to the test temperature interval comprises: comparing the real-time voltage value of the first monitoring voltage with the voltage value corresponding to each test temperature interval in the voltage-temperature relationship table in order from low to high; when the maximum one of all the voltage values corresponding to the test temperature intervals that are less than the real-time voltage value of the first monitoring voltage is the voltage value corresponding to the nth test temperature interval, determining the upper limit value of the nth test temperature interval as the temperature of the first thermistor, and taking the temperature of the first thermistor as the temperature of the field effect tube of the H-bridge circuit sensed by the first thermistor.

8. The method of claim 7, wherein, The step of determining the temperature of at least one of the first and second thermistors according to the test temperature interval further comprises: In order from low to high temperature, compare the real-time voltage value of the second monitoring voltage with the voltage value corresponding to each test temperature interval in the voltage-temperature relationship table; when the minimum one of all the voltage values corresponding to the test temperature intervals greater than the real-time voltage value of the second monitoring voltage is the voltage value corresponding to the nth test temperature interval, determine the upper limit value of the nth test temperature interval as the temperature of the second thermistor, and as the temperature of the field effect transistor of the H-bridge circuit sensed by the second thermistor.

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