Junction temperature monitoring method of insulated gate bipolar transistor, alternating current brushless motor, controller and electric tool

Abstract

The invention provides a junction temperature monitoring method for an insulated gate bipolar transistor, and the method comprises the steps: detecting the conduction voltage between a collector electrode and an emitter electrode when the conduction current between the collector electrode and the emitter electrode of the insulated gate bipolar transistor is in a preset range through a detection circuit when the insulated gate bipolar transistor works; and determining the junction temperature of the insulated gate bipolar transistor according to the break-over current and the detected break-over voltage, so as to monitor and control the junction temperature.

Description

Technical Field

[0001] The present application relates to a power tube device, and more specifically, to a technology for detecting the temperature of an insulated gate bipolar transistor. Background Art

[0002] IGBT (Insulated Gate Bipolar Transistor) is a core device for energy conversion and transmission, and is used in rail transportation, smart grid, aerospace, electric vehicles, and many power tools.

[0003] In AC brushless power tools, NTC (Negative Temperature Coefficient) is usually used to detect the temperature of IGBT (Insulated Gate Bipolar Transistor). Since there is a difference in amplitude and time delay between NTC temperature and IGBT junction temperature, it is difficult to estimate IGBT junction temperature using NTC temperature. Summary of the invention

[0004] According to one aspect of the present application, a method for monitoring the junction temperature of an insulated gate bipolar transistor (IGBT) and a method for monitoring the junction temperature of an insulated gate bipolar transistor of a lower half bridge of a power bridge of an AC brushless motor are provided to provide a method for determining the junction temperature without using an NTC.

[0005] According to the junction temperature monitoring method of the insulated gate bipolar transistor provided in the present application, it includes: when the insulated bipolar transistor is working, when the on-current between the collector and the emitter of the insulated bipolar transistor is within a preset range, the detection circuit detects the on-voltage between the collector and the emitter; and determines the junction temperature of the insulated gate bipolar transistor according to the on-current and the detected on-voltage, thereby realizing the monitoring of the junction temperature. Wherein, the detection circuit includes a Zener diode, one end of which is connected to the collector of the insulated gate bipolar transistor via a resistor, and the other end is connected to the emitter of the insulated gate bipolar transistor via another resistor; a discharge resistor, the discharge resistor is connected in parallel with the Zener diode; a differential amplifier circuit, the input end of which is connected to the two ends of the Zener diode. By way of example, the preset range is 3 amperes to 20 amperes.

[0006] According to another aspect of the present application, a method for monitoring the junction temperature of an insulated gate bipolar transistor of the lower half bridge of the power bridge of an AC brushless motor is also provided, the method comprising: when the insulated bipolar transistor is working, when the on-current between the collector and the emitter of the insulated bipolar transistor is within a preset range, the detection circuit detects the on-voltage between the collector and the emitter; and according to the on-current and the detected on-voltage, the junction temperature of the insulated gate bipolar transistor is determined, thereby realizing the monitoring of the junction temperature. Wherein, the detection circuit comprises a Zener diode, one end of which is connected to the collector of the insulated gate bipolar transistor via a resistor, and the other end is connected to the emitter of the insulated gate bipolar transistor via another resistor; a discharge resistor, the discharge resistor is connected in parallel with the Zener diode; and a differential amplifier circuit, the input end of which is connected to the two ends of the Zener diode.

[0007] An AC brushless motor is also provided, the AC brushless motor comprising a detection circuit and a controller. The detection circuit comprises a Zener diode, one end of which is connected to the collector of the insulated gate bipolar transistor of the lower half bridge of the power bridge of the motor via a resistor, and the other end of which is connected to the emitter of the insulated gate bipolar transistor via another resistor; a discharge resistor, the discharge resistor is connected in parallel with the Zener diode; and a differential amplifier circuit, the input end of which is connected to the two ends of the Zener diode. The controller is configured to execute instructions stored in a memory, so as to realize that when the insulated bipolar transistor is working, when the conduction current between the collector and the emitter of the insulated bipolar transistor is within a preset range, the detection circuit detects the conduction voltage between the collector and the emitter; and determines the junction temperature of the insulated gate bipolar transistor according to the conduction current and the detected conduction voltage, thereby realizing the monitoring of the junction temperature.

[0008] A controller is also provided. The controller includes a device configured to execute instructions stored in a memory and implement one of the above-mentioned methods for monitoring the junction temperature of an insulated gate bipolar transistor when executing the instructions.

[0009] An electric tool is also provided, which includes the junction temperature monitoring method of the insulated gate bipolar transistor described in any of the examples above, or is configured to execute the method described above for monitoring the junction temperature of the insulated gate bipolar transistor of the lower half bridge of the power bridge of the AC brushless motor; or includes the AC brushless motor described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present application will be more fully understood by referring to the following detailed description of specific embodiments in conjunction with the accompanying drawings, in which the same reference numerals in the drawings always refer to the same elements in the drawings.

[0011] Figure 1It is a structural schematic diagram of a detection circuit for detecting the on-voltage of an insulated gate bipolar transistor IGBT according to an example of the present application;

[0012] Figure 2 is a flow chart of a method for monitoring junction temperature of an insulated gate bipolar transistor IGBT according to an example of the present application;

[0013] Figure 3 The relationship between the on-current, on-voltage and junction temperature of the IGBT is shown;

[0014] Figure 4 is a flow chart of a method for monitoring the junction temperature of an insulated gate bipolar transistor of a lower half bridge of a power bridge of an AC brushless motor according to an example of the present application;

[0015] Figure 5 It is a structural schematic diagram of an IGBT applied in an AC brushless motor according to an example of the present application. DETAILED DESCRIPTION

[0016] In order to help those skilled in the art to accurately understand the subject matter for which protection is sought in the present application, the specific implementation of the present application will be described in detail below in conjunction with the accompanying drawings.

[0017] Figure 1 Schematic diagram of the structure of a detection circuit for detecting the on-voltage of an insulated gate bipolar transistor (IGBT) according to an example of the present application, wherein the on-voltage refers to the on-voltage between the collector and the emitter of the insulated bipolar transistor. Figure 1 As shown, the detection circuit includes a Zener diode 10, a discharge resistor 12, a differential amplifier circuit module 14, and an IGBT 15. One end of the Zener diode 10 is connected to the collector of the IGBT through a first resistor R1, and the other end is connected to the emitter of the IGBT through a fifth resistor R5. The discharge resistor 12 and the Zener diode 10 are connected in parallel. The input end of the differential amplifier circuit module 14 is connected to the two ends of the Zener diode 10, and the output is the conduction voltage between the collector and the emitter of the IGBT 15 to be detected. Specifically, one input end 140 of the differential amplifier circuit module 14 is connected to the cathode of the Zener diode 10 through a third resistor R3, and the other input end 140 is connected to the anode of the Zener diode 10 through a fourth resistor R4. The output of the differential amplifier circuit 14 is the conduction voltage between the collector 15-C and the emitter 15-E of the IGBT to be detected.

[0018] The Zener diode 10 is configured to be non-conductive when the collector 15-C and the emitter 15-E of the IGBT 15 are conductive. As a voltage stabilizing element, the Zener diode 10 can provide overvoltage protection to the subsequent circuit as a load, thereby preventing the subsequent circuit of the Zener diode 10 from being damaged due to overvoltage, and the subsequent circuit includes, for example, a discharge resistor 12 and a differential amplifier circuit module 14. The first resistor R1 is provided to limit the current of the Zener diode 10 at the breakdown voltage. The discharge resistor 12 provides a discharge path for the Zener diode 10, so that during the change process of the Zener diode 10 from high voltage to low voltage (i.e., the process of returning from breakdown to normal), the resistor 12 can receive the discharge current of the Zener diode 10, and realize the rapid discharge of the Zener diode 10. In this way, the real-time sampling of the voltage at the resistor 12 can be basically achieved. When the IGBT 15 is turned off, the voltage across the Zener diode 10 exceeds its breakdown voltage, the Zener diode breaks down, and the output voltage is limited, thereby protecting the subsequent circuit.

[0019] Figure 2 It is a flow chart of a method for monitoring junction temperature of an insulated gate bipolar transistor IGBT according to examples of the present application. According to these examples, in step S200, when the insulated bipolar transistor is operating, the detection circuit detects the on-voltage between the collector and the emitter of the insulated bipolar transistor when the on-current between the collector and the emitter of the insulated bipolar transistor is within a preset range. In the example of the present application, the detection circuit detects the on-voltage between the collector and the emitter when the on-current between the collector and the emitter of the insulated bipolar transistor is between 3 amperes and 20 amperes. The detection circuit may be used in combination with Figure 1 In step S202, the junction temperature of the insulated gate bipolar transistor is determined according to the on-current and the detected on-voltage, so as to monitor the junction temperature.

[0020] Detection circuit such as Figure 1 As shown, it will be combined with Figure 1 and Figure 2 Describe various examples according to the present application. Figure 2 The on-state voltage and current of the IGBT 15 are related to its temperature, especially when the on-state voltage changes within the preset current range, i.e., within the range of 3 amperes to 20 amperes, the temperature changes accordingly. Specifically, when the on-state current of the IGBT 15 is within the preset current range of 3A to 20A, the temperature increases when the on-state voltage decreases. According to some examples, the on-state voltage decreases by about 1mV and the temperature increases by about 1 degree.

[0021] Figure 3The relationship between the on-current, on-voltage and junction temperature of the IGBT 15 is shown in the figure, where the horizontal axis represents the temperature T in degrees Celsius and the vertical axis represents the on-voltage in volts. Figure 3 As shown, curve 30 and curve 32 represent the case where the on-current is relatively small, while curve 34 represents the case where the on-current is relatively large. As shown by curve 30 and curve 32, when the on-current is relatively small, the on-voltage decreases as the temperature increases; as shown by curve 34, when the on-current is relatively large, the relationship between the on-voltage and the temperature presents a different trend from that shown by curve 32 and curve 30, and the on-voltage increases as the temperature increases. In the example of this figure, the on-current shown by curve 30 is, for example, 5A, the on-current shown by curve 32 is 40A, and the on-current shown by curve 34 is 60A. According to Figure 3 In the example shown, for a relatively small on-current, the junction temperature rises by about 1 degree for every 1 mV decrease in on-voltage. However, when the on-current is 60 A, the on-voltage increases as the junction temperature rises. In addition, for IGBTs, the relationship between on-current, on-voltage, and temperature can be predetermined.

[0022] Figure 4 The present invention is a flow chart of a method for monitoring the junction temperature of an insulated gate bipolar transistor of a lower half bridge of a power bridge of an AC brushless motor according to an example of the present application. In step S400, when the insulated bipolar transistor is working, the detection circuit detects the on-state voltage between the collector and the emitter when the on-state current between the collector and the emitter of the insulated bipolar transistor is within a preset range. The preset range is, for example, 3A to 20A. The detection circuit may adopt Figure 1 The detection circuit shown.

[0023] According to each example of the present application, a data table can be constructed in advance based on a data set of the determined on-current, on-voltage and corresponding junction temperature of the IGBT, so that the corresponding junction temperature can be found from the data set based on the on-current and / or on-voltage. Thus, determining the junction temperature of the insulated gate bipolar transistor based on the detected on-voltage can be implemented as follows: based on the on-current and the detected on-voltage, the junction temperature corresponding to the on-current and the on-voltage is found from a preset data table to determine the junction temperature of the insulated gate bipolar transistor. As an example, the functional relationship between the on-current, on-voltage and junction temperature can also be preset, so as to calculate the junction temperature based on the determined on-voltage or on-current.

[0024] Figure 5 It is a structural schematic diagram of an IGBT applied in an AC brushless motor according to an example of the present application. Figure 1The DC bus terminal 100 of the detection circuit shown is electrically connected to the DC bus voltage 1114, and the output terminal 110 of the detection circuit is connected to the controller MCU (not shown), which can be a controller of an electric tool or a controller of the AC brushless motor, etc. During the operation of the motor, if the IGBT 15 in the lower half bridge of the power half bridge is in the on state, the voltage across its collector 15-C and emitter 15-E is low, about 2V. When the IGBT 15 is in the off state, the voltage across its collector 15-C and emitter 15-E can be as high as about 300V. According to the example of the present application, the Zener diode 10 (see Figure 1 ) is set to a breakdown voltage of 3 V. Therefore, when the IGBT 15 is turned on, the Zener diode 10 does not break down. Figure 1 The detection circuit shown can detect the on-current of the IGBT 15 and the on-voltage between the collector 15-C and the emitter 15-E of the IGBT 15, thereby obtaining the on-voltage when the on-current is in the range of 3 A to 20 A. Accordingly, the junction temperature of the IGBT 15 can be determined based on the known relationship between the on-voltage and the junction temperature.

[0025] According to the present application, each example may also compare the determined junction temperature of the IGBT with a preset threshold value for the junction temperature. If the determined junction temperature is greater than the preset threshold value, a method such as reducing the on-current and / or on-voltage may be implemented to reduce the temperature of the IGBT, which is to ensure that the on-current is within the range of 3A to 20A.

[0026] The present application also provides an AC brushless motor, which includes a detection circuit and a controller. The detection circuit can be used Figure 1 The detection circuit shown, the controller is configured to execute instructions in the memory to implement any one of the methods described in the above examples. The memory can be a memory included in the motor, or an external memory that can be read by the controller of the motor.

[0027] The present application also provides an electric tool, which includes an AC brushless motor according to the present application, or can execute any method described in the above examples. As an example, the electric tool is an angle grinder.

[0028] Although specific embodiments of the present application have been shown and described in detail to illustrate the principles of the present application, it should be understood that the present application can be implemented in other ways without departing from such principles.

Claims

1. A method for monitoring junction temperature of an insulated gate bipolar transistor, characterized in that: The method comprises: When the insulated bipolar transistor is working, the detection circuit detects the on-state voltage between the collector and the emitter when the on-state current between the collector and the emitter of the insulated bipolar transistor is within a preset range; and Determining the junction temperature of the insulated gate bipolar transistor according to the on-current and the detected on-voltage, thereby realizing monitoring of the junction temperature; Wherein, the detection circuit comprises: a Zener diode, one end of which is connected to the collector of the insulated gate bipolar transistor via a resistor, and the other end of which is connected to the emitter of the insulated gate bipolar transistor via another resistor; a discharge resistor, the discharge resistor being connected in parallel with the Zener diode; The differential amplifier circuit module has an input end connected to the two ends of the Zener diode.

2. The method for monitoring junction temperature of an insulated gate bipolar transistor according to claim 1, characterized in that: Determining the junction temperature of the insulated gate bipolar transistor according to the on-current and the detected on-voltage includes: According to the on-current and the detected on-voltage, searching a preset data table for a junction temperature corresponding to the on-current and the on-voltage to determine the junction temperature of the insulated gate bipolar transistor; The preset data table includes a predetermined data set of on-current, on-voltage and corresponding junction temperature of the insulated gate bipolar transistor.

3. The method for monitoring junction temperature of an insulated gate bipolar transistor according to claim 1 or 2 further comprises: The determined junction temperature is compared with a preset threshold and when the junction temperature is greater than the preset threshold, the junction temperature is controlled by adjusting an on-current and / or an on-voltage of the insulated gate bipolar transistor. 4 . The junction temperature monitoring method of an insulated gate bipolar transistor according to claim 1 , wherein the preset range is 3 amperes to 20 amperes.

5. A method for monitoring the junction temperature of an insulated gate bipolar transistor of a lower half bridge of a power bridge of an AC brushless motor, characterized in that: The method comprises: When the insulated bipolar transistor is working, the detection circuit detects the on-state voltage between the collector and the emitter when the on-state current between the collector and the emitter of the insulated bipolar transistor is within a preset range; and Determining the junction temperature of the insulated gate bipolar transistor according to the on-current and the detected on-voltage, thereby realizing monitoring of the junction temperature; Wherein, the detection circuit comprises: a Zener diode, one end of which is connected to the collector of the insulated gate bipolar transistor via a resistor, and the other end of which is connected to the emitter of the insulated gate bipolar transistor via another resistor; a discharge resistor, the discharge resistor being connected in parallel with the Zener diode; The differential amplifier circuit module has an input end connected to the two ends of the Zener diode.

6. The method according to claim 5, characterized in that Determining the junction temperature of the insulated gate bipolar transistor according to the on-current and the detected on-voltage, comprising: According to the on-current and the detected on-voltage, searching a preset data table for a junction temperature corresponding to the on-current and the on-voltage to determine the junction temperature of the insulated gate bipolar transistor; The preset data table includes a predetermined data set of on-current, on-voltage and corresponding junction temperature of the insulated gate bipolar transistor.

7. The method according to claim 5 or 6, characterized in that: The method further includes comparing the determined junction temperature with a preset threshold and controlling the junction temperature by adjusting an on-current and / or an on-voltage of the insulated gate bipolar transistor when the junction temperature is greater than the preset threshold.

8. The method according to claim 5 or 6, characterized in that: The preset range is 3 amps to 20 amps.

9. An AC brushless motor, characterized in that: The AC brushless motor comprises: A detection circuit comprising: A Zener diode, one end of which is connected to the collector of the insulated gate bipolar transistor of the lower half bridge of the power bridge of the motor via a resistor, and the other end of which is connected to the emitter of the insulated gate bipolar transistor via another resistor; a discharge resistor, the discharge resistor being connected in parallel with the Zener diode; a differential amplifier circuit, whose input terminal is connected to both ends of the Zener diode; and A controller configured to execute instructions stored in the memory to: When the insulated bipolar transistor is working, the detection circuit detects the on-state voltage between the collector and the emitter when the on-state current between the collector and the emitter of the insulated bipolar transistor is within a preset range; and The junction temperature of the insulated gate bipolar transistor is determined according to the on-current and the detected on-voltage, thereby realizing the monitoring of the junction temperature.

10. A controller, characterized in that: The controller includes a device configured to execute instructions stored in a memory, and implement the junction temperature monitoring method of an insulated gate bipolar transistor according to any one of claims 1 to 4 when executing the instructions.

11. An electric tool, comprising a method configured to execute the junction temperature monitoring method of the insulated gate bipolar transistor according to any one of claims 1 to 4, or a method configured to execute the junction temperature of the insulated gate bipolar transistor of the lower half bridge of the power bridge of the AC brushless motor according to any one of claims 5 to 8; or an AC brushless motor according to claim 9.

Images