Junction temperature detection circuit and device and power system

Abstract

The utility model relates to a junction temperature detection circuit, a junction temperature detection device and a power system. The junction temperature detection circuit comprises a voltage detection circuit and a control circuit. Two voltage detection ends of the voltage detection circuit are respectively connected with a first end and a second end of the to-be-detected power device, and the voltage detection circuit is used for detecting the conduction voltage of the to-be-detected power device; the control circuit is connected with the voltage detection circuit and is used for acquiring the conduction current of the to-be-detected power device and determining the junction temperature of the to-be-detected power device from a preset corresponding relation according to the conduction current and the conduction voltage; the preset corresponding relation is the corresponding relation between the on resistance and the junction temperature. The voltage detection circuit detects the conduction voltage of the to-be-detected power device in real time, and the control circuit calculates the real-time conduction resistance of the to-be-detected power device according to the conduction voltage obtained in real time and the conduction current of the to-be-detected power device, and obtains the junction temperature corresponding to the conduction resistance according to the preset corresponding relation. Therefore, real-time junction temperature detection of the to-be-detected power device is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of junction temperature detection, and particularly relates to a junction temperature detection circuit, a device and a power system. BACKGROUND

[0002] The junction temperature is an important parameter of a power device, and the degradation trend and failure condition of the power device during work are closely related to the junction temperature fluctuation and amplitude of the power device during operation. If the device operating temperature exceeds the maximum junction temperature, the device may be damaged and the device will fail. Therefore, it is necessary to obtain the junction temperature of the power device in real time for monitoring the junction temperature of the power device for the design and application of the power device. The junction temperature is closely related to the on-resistance of the power device, and the on-resistance can be used to indirectly obtain the junction temperature of the power device. Therefore, how to detect the on-resistance of the power device in real time is a technical problem to be solved by those skilled in the art. CONTENT OF THE INVENTION

[0003] The present application provides a junction temperature detection circuit, a device and a power system, which can detect the on-voltage of the power device to be detected in real time, and then obtain the on-resistance through the control circuit, thereby realizing real-time acquisition of the junction temperature of the power device to be detected.

[0004] In a first aspect, the present application provides a junction temperature detection circuit, comprising: a voltage detection circuit and a control circuit. Two voltage detection ends of the voltage detection circuit are connected with a first end and a second end of a power device to be detected respectively, and the voltage detection circuit is used for detecting the on-voltage of the power device to be detected; the control circuit is connected with the voltage detection circuit, and is used for acquiring the on-current of the power device to be detected, and determining the junction temperature of the power device to be detected from a preset corresponding relationship according to the on-current and the on-voltage; wherein the preset corresponding relationship is the corresponding relationship between the on-resistance and the junction temperature. The voltage detection circuit detects the on-voltage of the power device to be detected in real time, and outputs the detected on-voltage to the control circuit. The control circuit calculates the on-resistance of the power device to be detected by the on-voltage and the on-current. Since the control circuit stores the preset corresponding relationship which can reflect the corresponding relationship between the junction temperature and the on-resistance of the power device, the control circuit can obtain the junction temperature corresponding to the on-resistance by querying the preset corresponding relationship according to the on-resistance calculated in real time, thereby realizing real-time junction temperature detection of the power device to be detected.

[0005] In some embodiments, the voltage detection circuit comprises a first operational amplifier; the non-inverting input terminal of the first operational amplifier is electrically connected with the first terminal of the power device to be detected, the inverting input terminal of the first operational amplifier is electrically connected with the second terminal of the power device to be detected, the inverting input terminal of the first operational amplifier is electrically connected with the output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is electrically connected with the control circuit. The present application amplifies the received voltage by the first operational amplifier to ensure that the voltage output to the control circuit is the conduction voltage. And the voltage amplified and output by the first operational amplifier is fed back to the inverting input terminal of the first operational amplifier, so as to realize the control of the gain of the first operational amplifier, to realize the stable output of the first operational amplifier, so as to ensure that the control circuit can receive accurate conduction voltage, so that the control circuit can calculate accurate conduction resistance, and then obtain accurate power device junction temperature.

[0006] In some embodiments, the voltage detection circuit further comprises a first resistor, a second resistor and a third resistor; the non-inverting input terminal of the first operational amplifier is electrically connected with the first terminal of the power device to be detected through the first resistor, the inverting input terminal of the first operational amplifier is electrically connected with the second terminal of the power device to be detected through the second resistor; and the inverting input terminal of the first operational amplifier is electrically connected with the output terminal of the first operational amplifier through the third resistor. The present application divides the large voltage existing when the power device to be detected is disconnected by the first resistor and the second resistor, so as to play a protective role for the first operational amplifier and the control circuit. The voltage output by the first operational amplifier is also output to the inverting input terminal of the first operational amplifier through the third resistor. By adjusting the resistance value of the third resistor, the feedback gain of the first operational amplifier can be adjusted, and then the gain control of the first operational amplifier can be realized to ensure the stable output of the first operational amplifier.

[0007] In some embodiments, the voltage detection circuit further comprises a fourth resistor; the non-inverting input terminal of the first operational amplifier is electrically connected with the bias voltage output terminal of the power supply through the fourth resistor. The present application connects the non-inverting input terminal of the first operational amplifier with the bias voltage output terminal of the power supply. When the conduction voltage between the terminals of the power device to be detected is negative, the negative voltage output to the non-inverting input terminal of the first operational amplifier is adjusted to positive voltage by the bias voltage output by the power supply, and the gain of the bias voltage output by the power supply can be adjusted by the fourth resistor, so as to ensure that the voltage output to the non-inverting input terminal of the first operational amplifier can meet the voltage output requirements of the first operational amplifier.

[0008] In some embodiments, the voltage detection circuit further comprises a first diode and a second diode; a negative terminal of the first diode is electrically connected to the positive power supply terminal of the power supply, and a positive terminal of the first diode is electrically connected to the non-inverting input terminal of the first operational amplifier; a negative terminal of the second diode is electrically connected to the positive terminal of the first diode, and a positive terminal of the second diode is electrically connected to the negative power supply terminal of the power supply. The first diode and the second diode are configured to clamp the voltage output to the non-inverting input terminal of the first operational amplifier, so that the voltage output to the non-inverting input terminal of the first operational amplifier is clamped within a certain voltage range, thereby preventing the first operational amplifier and the control circuit from being damaged due to an excessively large received voltage.

[0009] In some embodiments, the voltage detection circuit further comprises a third diode and a fourth diode; a negative terminal of the third diode is electrically connected to the positive power supply terminal of the power supply, and a positive terminal of the third diode is electrically connected to the inverting input terminal of the first operational amplifier; a negative terminal of the fourth diode is electrically connected to the positive terminal of the third diode, and a positive terminal of the fourth diode is electrically connected to the negative power supply terminal of the power supply. The third diode and the fourth diode are configured to clamp the voltage output to the inverting input terminal of the first operational amplifier, so that the voltage output to the inverting input terminal of the first operational amplifier is clamped within a certain voltage range, thereby preventing the first operational amplifier and the control circuit from being damaged due to an excessively large received voltage.

[0010] In some embodiments, the voltage detection circuit further comprises a filter resistor and a filter capacitor; an output terminal of the first operational amplifier is electrically connected to a first terminal of the filter resistor, a second terminal of the filter resistor is electrically connected to the controller, and the second terminal of the filter resistor is grounded through the filter capacitor. The filter resistor and the filter capacitor are configured to filter out the interference signals in the output signal of the first operational amplifier, so that an accurate conduction voltage is output to the control circuit, thereby enabling the control circuit to calculate a more accurate conduction resistance and obtain an accurate junction temperature of the power device under test.

[0011] In some embodiments, the voltage detection circuit further comprises a second operational amplifier; the first operational amplifier is electrically connected to the control circuit through the second operational amplifier. The first operational amplifier and the second operational amplifier form a two-stage amplification circuit, which can maintain the accuracy and precision of the input signal, so that the control circuit receives a more accurate conduction voltage to calculate a more accurate conduction resistance, thereby obtaining an accurate junction temperature of the power device under test.

[0012] In a second aspect, the application provides a junction temperature detection device comprising at least one junction temperature detection circuit as described in the above embodiments.

[0013] In a third aspect, the present application provides a power system comprising the junction temperature detection device as in the above embodiments.

[0014] The above description is only a summary of the technical solutions of the present application. In order to enable one skilled in the art to better understand the technical means of the present application, the contents of the specification can be implemented, and in order to enable the above and other purposes, features and advantages of the present application to be more apparent and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0016] Figure 1 The structural schematic diagram of a junction temperature detection circuit according to an embodiment of the present application.

[0017] Figure 2 The structural schematic diagram of a preferred junction temperature detection circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0018] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0020] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0021] Reference to“an embodiment” herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in an embodiment” in various places in the specification are not necessarily referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments in accordance with the application.

[0022] In the description of the embodiments of the application, the term“and / or” only means an association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character“ / ” herein generally means that the front and rear associated objects have an“or” relationship.

[0023] In the description of the embodiments of the application, the term“a plurality of” means more than two (including two), and similarly, “a plurality of groups” means more than two groups (including two groups), and “a plurality of pieces” means more than two pieces (including two pieces).

[0024] In the description of the embodiments of the application, the technical terms“center”,“longitudinal”,“transverse”,“length”,“width”,“thickness”,“upper”,“lower”,“front”,“rear”,“left”,“right”,“vertical”,“horizontal”,“top”,“bottom”,“inner”,“outer”,“clockwise”,“counterclockwise”,“axial”,“radial”,“circumferential” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the application.

[0025] In the description of the embodiments of the application, unless otherwise explicitly specified and limited, the technical terms“mounting”,“connection”,“connection”,“fixing” and the like should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the application can be understood according to the specific circumstances.

[0026] Power devices such as MOS tubes are at the core of modern power electronic converters, which play a very important role in the reliability, cost and performance of the device. However, the working capacity of the power device will degenerate in the continuous working process, and if the degeneration trend of the power device cannot be accurately obtained, the failure prediction of the power device will be affected, so a reliable method is needed to detect the degeneration trend of the power device in real time. The junction temperature is an important parameter of the power device, and the degeneration trend and failure of the power device during operation are closely related to the junction temperature fluctuation and amplitude of the power device during operation. The junction temperature is closely related to the on-resistance of the power device, and the junction temperature of the power device can be indirectly obtained by obtaining the on-resistance of the power device. Therefore, in order to obtain the junction temperature in real time, how to detect the on-resistance of the power device in real time has become a technical problem that needs to be solved by the technical personnel in the field.

[0027] In order to realize real-time detection of the on-resistance of the power device, and then obtain the junction temperature of the power device, the application provides a junction temperature detection circuit, device and power system. The voltage detection circuit is used to obtain the on-resistance of the power device in real time and send it to the control circuit. The control circuit will calculate the on-resistance of the power device according to the obtained on-resistance and the real-time detected on-current of the power device, so as to realize real-time detection of the on-resistance of the power device. The control module matches the junction temperature of the power device corresponding to the on-resistance according to the preset corresponding relationship, so as to realize real-time junction temperature detection of the power device.

[0028] According to some embodiments of the application, Figure 1 The structure diagram of a junction temperature detection circuit according to an embodiment of the application is shown in Figure 1 The junction temperature detection circuit includes a voltage detection circuit 100 and a control circuit 200. The two voltage detection ends of the voltage detection circuit 100 are respectively connected with the first end and the second end of the power device 310 to be detected, and the voltage detection circuit 100 is used to detect the on-voltage of the power device 310 to be detected. The control circuit 200 is connected with the voltage detection circuit 100, and is used to obtain the on-current of the power device 310 to be detected, and determine the junction temperature of the power device 310 to be detected from the preset corresponding relationship according to the on-current and the on-voltage. The preset corresponding relationship is the corresponding relationship between the on-resistance and the junction temperature.

[0029] The power device to be tested 310 is a power switch tube of the three-phase inverter 300, the three-phase inverter 300 includes three bridge arms, two power devices to be tested 310 are arranged in series on each bridge arm, and the voltage detection circuit 100 is arranged correspondingly on each power device to be tested 310, and the voltage detection circuit 100 is used for detecting the on-voltage of the power device to be tested 310 in real time. The first voltage detection end of the voltage detection circuit 100 is electrically connected with the first end of the power device to be tested 310, the second voltage detection end of the voltage detection circuit 100 is electrically connected with the second end of the power device to be tested 310, and the output end of the voltage detection circuit 100 is electrically connected with the control circuit 200. When the power device to be tested 310 is turned on, the voltage detection circuit 100 detects the on-voltage of the power device to be tested 310 in real time, and sends the detected on-voltage to the control circuit 200.

[0030] The junction temperature detection circuit further includes a current detection circuit 400, which can include a device capable of detecting current, such as a Hall current detector or a shunt. The bridge arm midpoint of each bridge arm of the three-phase inverter 300 is electrically connected with the current detection circuit 400, and the current detection circuit 400 is used for detecting the on-current of the power device to be tested 310 in real time. The control circuit 200 obtains the on-current of the power device to be tested 310 in real time through the current detection circuit 400, and obtains the on-voltage of the power device to be tested 310 in real time through the voltage detection circuit 100, and calculates the on-resistance of the power device to be tested 310 through the obtained on-voltage and on-current. Since the junction temperature of the power device corresponds to the on-resistance of the power device, a preset corresponding relationship between the on-resistance and the junction temperature can be established through experiments before the junction temperature is detected, and the obtained preset corresponding relationship is stored in the control circuit 200. When the control circuit 200 calculates the on-resistance according to the obtained on-current and on-voltage in real time, the junction temperature corresponding to the on-resistance can be obtained directly through the preset corresponding relationship, thereby realizing real-time junction temperature detection of the power device to be tested 310.

[0031] It should be noted that the power device to be tested 310 is a power switch tube of the three-phase inverter 300, and the power device to be tested 310 can also be a power switch tube of other motor controllers except the three-phase inverter, which is not limited here.

[0032] In some embodiments, the voltage detection circuit includes a first operational amplifier; the non-inverting input end of the first operational amplifier is electrically connected with the first end of the power device to be tested, the inverting input end of the first operational amplifier is electrically connected with the second end of the power device to be tested, the inverting input end of the first operational amplifier is electrically connected with the output end of the first operational amplifier, and the output end of the first operational amplifier is also electrically connected with the control circuit.

[0033] Specifically, when the to-be-tested power device in the motor controller is not turned on, the voltage across the to-be-tested power device is the power supply voltage of the motor controller, and the voltage value of the power supply voltage can usually reach several hundred volts. If the control circuit is directly connected with the to-be-tested power device, the control circuit can be damaged due to the excessively large voltage received, and even a safety accident can be caused. Therefore, a voltage dividing circuit needs to be arranged in front of the control circuit to realize protection of the control circuit. However, the arrangement of the voltage dividing circuit can cause the voltage received by the control circuit to be excessively small. Therefore, a first operational amplifier needs to be arranged to amplify the voltage after voltage division. In the detection process of the turn-on voltage of the to-be-tested power device, the output voltage of the to-be-tested power device is output to the non-inverting input terminal of the first operational amplifier after voltage division by the voltage dividing circuit, and is amplified by the first operational amplifier. The turn-on voltage finally output by the first operational amplifier is obtained by adjusting the amplification gain of the first operational amplifier. The inverting input terminal of the first operational amplifier is also electrically connected with the output terminal of the first operational amplifier, so that the voltage after amplification output by the first operational amplifier can be fed back to the inverting input terminal of the first operational amplifier. Therefore, the gain of the first operational amplifier can be controlled, so that the output of the first operational amplifier is stable, so that the control circuit can receive the accurate turn-on voltage, the control circuit can calculate the accurate turn-on resistance, and then the accurate junction temperature of the power device can be obtained.

[0034] In some embodiments, the voltage detection circuit further comprises a first resistor, a second resistor and a third resistor; the non-inverting input terminal of the first operational amplifier is electrically connected with the first terminal of the to-be-tested power device through the first resistor, and the inverting input terminal of the first operational amplifier is electrically connected with the second terminal of the to-be-tested power device through the second resistor; and the inverting input terminal of the first operational amplifier is electrically connected with the output terminal of the first operational amplifier through the third resistor.

[0035] Specifically, the first resistor and the second resistor are both high-value resistors, and the resistance values of the first resistor and the second resistor can be several hundred kilo-ohms or even several mega-ohms, so that the high voltage across the to-be-tested power device in the motor controller is divided when the to-be-tested power device is not conducting. When the motor controller has a large voltage operating requirement, the first resistor and the second resistor are arranged to divide the large voltage, thereby protecting the first operational amplifier and the control circuit. The voltage after being divided by the first resistor and the second resistor is output to the first operational amplifier, the first operational amplifier amplifies the received voltage, and the amplified voltage is the real-time detected conduction voltage, which is output to the control circuit through the output end of the first operational amplifier. The voltage output by the first operational amplifier is also output to the inverting input end of the first operational amplifier through the third resistor, and the feedback gain of the first operational amplifier can be adjusted by adjusting the resistance value of the third resistor, thereby controlling the gain of the first operational amplifier to ensure the stability of the output of the first operational amplifier.

[0036] In some embodiments, the voltage detection circuit further comprises a fourth resistor; the non-inverting input end of the first operational amplifier is electrically connected to the bias voltage output end of the power supply through the fourth resistor.

[0037] Specifically, during the operation of the motor controller, the output current direction of the to-be-tested power device can be different. When the output current direction of the to-be-tested power device is from the to-be-tested power device to the bridge arm midpoint of the motor controller, the voltage across the to-be-tested power device is positive. When the output current direction of the to-be-tested power device is from the bridge arm midpoint of the motor controller to the to-be-tested power device, the voltage across the to-be-tested power device is negative. During the detection of the conduction voltage of the to-be-tested power device by the voltage detection circuit, the voltage finally output by the voltage detection circuit needs to be positive to facilitate the processing of the control circuit. Therefore, the non-inverting input end of the first operational amplifier is connected to the bias voltage output end of the power supply, so that when the conduction voltage across the to-be-tested power device is negative, the negative voltage output to the non-inverting input end of the first operational amplifier is adjusted to a positive voltage by the bias voltage output by the power supply, and the gain of the bias voltage output by the power supply can be adjusted by the fourth resistor, so that the voltage output to the non-inverting input end of the first operational amplifier can meet the voltage output requirements of the first operational amplifier.

[0038] In some embodiments, the voltage detection circuit further comprises a first diode and a second diode; the negative electrode of the first diode is electrically connected to the positive power supply end of the power supply, and the positive electrode of the first diode is electrically connected to the non-inverting input end of the first operational amplifier; the negative electrode of the second diode is electrically connected to the positive electrode of the first diode, and the positive electrode of the second diode is electrically connected to the negative power supply end of the power supply.

[0039] For example, the voltage drop of the first diode and the second diode is U0, the voltage output by the positive power supply terminal of the power supply is U1, and the voltage output by the negative power supply terminal of the power supply is U2, where U1 is greater than U2. Both the first diode and the second diode function as a clamp. When the voltage output from the first end of the power device under test to the non-inverting input terminal of the first operational amplifier is greater than the voltage U1 output by the positive power supply terminal of the power supply, the first diode is turned on, and the second diode is kept off. At this time, the voltage received by the non-inverting input terminal of the first operational amplifier is U1+U0. When the voltage output from the first end of the power device under test to the non-inverting input terminal of the first operational amplifier is less than the voltage U2 output by the negative power supply terminal of the power supply, the first diode is kept off, and the second diode is turned on. At this time, the voltage received by the non-inverting input terminal of the first operational amplifier is U2-U0. Therefore, the voltage received by the non-inverting input terminal of the first operational amplifier is clamped in the voltage range of less than or equal to U1+U0 and greater than or equal to U2-U0, so that the large voltage generated when the power device under test is turned off is clamped in a certain voltage range, thereby ensuring that the first operational amplifier and the control circuit will not be damaged due to the excessively large voltage received.

[0040] In some embodiments, the voltage detection circuit further comprises a third diode and a fourth diode; the negative terminal of the third diode is electrically connected to the power supply terminal of the power supply, and the positive terminal of the third diode is electrically connected to the inverting input terminal of the first operational amplifier; the negative terminal of the fourth diode is electrically connected to the positive terminal of the third diode, and the positive terminal of the fourth diode is electrically connected to the negative power supply terminal of the power supply.

[0041] For example, the voltage drop of the third diode and the fourth diode is U0, the voltage output by the positive power supply terminal of the power supply is U1, and the voltage output by the negative power supply terminal of the power supply is U2, where U1 is greater than U2. Both the third diode and the fourth diode function as a clamp. When the voltage output from the second end of the power device under test to the inverting input terminal of the first operational amplifier is greater than the voltage U1 output by the positive power supply terminal of the power supply, the third diode is turned on, and the fourth diode is kept off. At this time, the voltage received by the inverting input terminal of the first operational amplifier is U1+U0. When the voltage output from the second end of the power device under test to the inverting input terminal of the first operational amplifier is less than the voltage U2 output by the negative power supply terminal of the power supply, the third diode is kept off, and the fourth diode is turned on. At this time, the voltage received by the inverting input terminal of the first operational amplifier is U2-U0. Therefore, the voltage received by the inverting input terminal of the first operational amplifier is clamped in the voltage range of less than or equal to U1+U0 and greater than or equal to U2-U0, so that the large voltage generated when the power device under test is turned off is clamped in a certain voltage range, thereby ensuring that the first operational amplifier and the control circuit will not be damaged due to the excessively large voltage received.

[0042] In some embodiments, the voltage detection circuit further comprises a filter resistor and a filter capacitor; an output end of the first operational amplifier is electrically connected with a first end of the filter resistor, a second end of the filter resistor is electrically connected with the control circuit, and the second end of the filter resistor is grounded through the filter capacitor.

[0043] Specifically, the filter resistor and the filter capacitor jointly act on filtering the signal output by the first operational amplifier, filter out the interference signal existing in the output signal, so as to output the accurate conduction voltage to the control circuit, thereby making the control circuit can calculate more accurate conduction resistance, and then realize obtaining accurate junction temperature of the power device under test.

[0044] In some embodiments, the voltage detection circuit further comprises a second operational amplifier; the first operational amplifier is electrically connected with the control circuit through the second operational amplifier.

[0045] Specifically, the first operational amplifier collects and amplifies the voltage across the power device under test, and then outputs the amplified voltage to the second operational amplifier, which is amplified again and output to the control circuit. The present application adopts the first operational amplifier and the second operational amplifier for two-stage amplification, which can realize higher amplification gain than and amplification, so as to amplify the weak voltage signal to a larger amplitude to meet the voltage collection demand of the control circuit. And the two-stage amplification circuit also has the characteristics of low distortion, so as to maintain the accuracy and precision of the input signal, so that the control circuit receives more accurate conduction voltage to calculate more accurate conduction resistance, and then realizes obtaining accurate junction temperature of the power device under test.

[0046] Figure 2 A preferred structure diagram of a junction temperature detection circuit for an embodiment of the present application is shown in FIG. 1. Figure 2 As shown in FIG. 1, the voltage detection circuit 100 comprises a first operational amplifier 110, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a filter resistor R5, a filter capacitor C1, a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4.

[0047] The non-inverting input terminal of the first operational amplifier 110 is electrically connected with the first end of the power device under test 310 through a first resistor R1, the inverting input terminal of the first operational amplifier 110 is electrically connected with the second end of the power device under test 310 through a second resistor R2, the inverting input terminal of the first operational amplifier 110 is electrically connected with the output terminal of the first operational amplifier 110 through a third resistor R3, the non-inverting input terminal of the first operational amplifier 110 is electrically connected with the bias voltage output terminal 501 of the power supply 500 through a fourth resistor R4, the output terminal of the first operational amplifier 110 is electrically connected with the first end of a filter resistor R5, the second end of the filter resistor R5 is electrically connected with the control circuit 200, and the second end of the filter resistor R5 is also grounded through a filter capacitor C1.

[0048] The negative terminal of the first diode D1 is electrically connected with the positive power supply terminal 502 of the power supply 500, the positive terminal of the first diode D1 is electrically connected with the non-inverting input terminal of the first operational amplifier 110, the negative terminal of the second diode D2 is electrically connected with the positive terminal of the first diode D1, the positive terminal of the second diode D2 is electrically connected with the negative power supply terminal 503 of the power supply 500. The negative terminal of the third diode D3 is electrically connected with the positive power supply terminal 502 of the power supply 500, the positive terminal of the third diode D3 is electrically connected with the inverting input terminal of the first operational amplifier 110, the negative terminal of the fourth diode D4 is electrically connected with the positive terminal of the third diode D3, and the positive terminal of the fourth diode D4 is electrically connected with the negative power supply terminal 503 of the power supply 500.

[0049] Specifically, when the power device under test 310 is turned on, the voltage detection circuit 100 detects the on-voltage of the power device under test 310 in real time, the on-voltage is output to the first operational amplifier 110 after being divided by the first resistor R1 and the second resistor R2, and the first operational amplifier 110 amplifies and outputs the divided voltage to the control circuit 200. The control circuit 200 obtains the on-resistance of the power device under test 310 by calculating the on-voltage and the on-current obtained, and obtains the junction temperature corresponding to the on-resistance according to the preset corresponding relationship, thereby realizing real-time junction temperature detection of the power device under test 310. The voltage output by the first operational amplifier 110 is also output to the inverting input terminal of the first operational amplifier 110 through the third resistor R3. By adjusting the resistance value of the third resistor R3, the feedback gain of the first operational amplifier 110 can be adjusted, and the gain of the first operational amplifier 110 can be controlled to ensure the stability of the output of the first operational amplifier 110.

[0050] The noninverting input terminal of the first operational amplifier 110 is connected with the bias voltage output terminal 501 of the power supply 500, when the on voltage between the to-be-tested power device 310 is negative, the negative voltage output to the noninverting input terminal of the first operational amplifier 110 is adjusted by the bias voltage output by the power supply 500 to become a positive voltage, and the bias voltage output by the power supply 500 can also be gain-adjusted by the fourth resistor R4, so as to ensure that the voltage output to the noninverting input terminal of the first operational amplifier 110 can meet the voltage output requirement of the first operational amplifier 110.

[0051] The first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 play a role of voltage clamping, can clamp the voltage output to the noninverting input terminal and the inverting input terminal of the first operational amplifier 110 in a certain voltage range, so as to ensure that the first operational amplifier 110 and the control circuit 200 will not be damaged due to the voltage received being too large. The filter resistor R5 and the filter capacitor C1 jointly act on the signal output by the first operational amplifier 110 to filter the interference signal existing in the output signal, so as to output an accurate on voltage to the control circuit 200, so that the control circuit 200 can calculate a more accurate on resistance, and then realize obtaining an accurate to-be-tested power device junction temperature.

[0052] The application also provides a junction temperature detection device, comprising at least one junction temperature detection circuit as described in the above embodiments.

[0053] It can be understood that the junction temperature detection device provided by the embodiments of the application can realize the corresponding beneficial effects of any one of the junction temperature detection circuits provided by the above embodiments, which will not be repeated here.

[0054] The application also provides a power system, comprising a junction temperature detection device as described in the above embodiments.

[0055] It can be understood that the power system provided by the embodiments of the application can realize the corresponding beneficial effects of the power system provided by the above embodiments, which will not be repeated here.

[0056] It has to be noted that, in the present document, relational terms are intended only to convey a possible relationship between elements or

[0057] The foregoing detailed description has set forth various embodiments of the application via the use of specific terminology. However, embodiments thereof can be practiced without the specific details ("every" embodiment) set forth above. In general, the teachings of the present application can be applied to any suitable industrial setting and / or process of this type. The foregoing description, therefore, is not intended to be limiting, but merely illustrative. Further, the herein disclosed subject matter is intended to cover all alternatives, modifications and equivalents. Thus, the scope of the present application should be determined by the appended claims and their legal equivalents, and not by the abilities or activities that are specifically described herein.

Claims

1. A junction temperature detection circuit, characterized by comprising: include: A voltage detection circuit, wherein the two voltage detection terminals of the voltage detection circuit are respectively connected to the first terminal and the second terminal of the power device under test, and the voltage detection circuit is used to detect the on-state voltage of the power device under test; A control circuit is connected to the voltage detection circuit. The control circuit is used to acquire the on-state current of the power device under test, and determine the junction temperature of the power device under test from a preset correspondence based on the on-state current and the on-state voltage; wherein, the preset correspondence is the correspondence between on-resistance and junction temperature.

2. The junction temperature detection circuit according to claim 1, wherein The voltage detection circuit includes a first operational amplifier; The non-inverting input of the first operational amplifier is electrically connected to the first terminal of the power device under test, the inverting input of the first operational amplifier is electrically connected to the second terminal of the power device under test, the inverting input of the first operational amplifier is electrically connected to the output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is also electrically connected to the control circuit.

3. The junction temperature detection circuit of claim 2, wherein The voltage detection circuit also includes a first resistor, a second resistor, and a third resistor; The non-inverting input of the first operational amplifier is electrically connected to the first terminal of the power device under test through the first resistor, and the inverting input of the first operational amplifier is electrically connected to the second terminal of the power device under test through the second resistor; the inverting input of the first operational amplifier is electrically connected to the output terminal of the first operational amplifier through the third resistor.

4. The junction temperature detection circuit of claim 2, wherein The voltage detection circuit also includes a fourth resistor; The non-inverting input terminal of the first operational amplifier is electrically connected to the bias voltage output terminal of the power supply through the fourth resistor.

5. The junction temperature detection circuit of claim 2, wherein The voltage detection circuit also includes a first diode and a second diode; The negative terminal of the first diode is electrically connected to the positive power supply terminal of the power supply, and the positive terminal of the first diode is electrically connected to the non-inverting input terminal of the first operational amplifier; the negative terminal of the second diode is electrically connected to the positive terminal of the first diode, and the positive terminal of the second diode is electrically connected to the negative power supply terminal of the power supply.

6. The junction temperature detection circuit of claim 2, wherein The voltage detection circuit also includes a third diode and a fourth diode; The negative terminal of the third diode is electrically connected to the positive power supply terminal of the power source, and the positive terminal of the third diode is electrically connected to the inverting input terminal of the first operational amplifier; the negative terminal of the fourth diode is electrically connected to the positive terminal of the third diode, and the positive terminal of the fourth diode is electrically connected to the negative power supply terminal of the power source.

7. The junction temperature detection circuit of claim 2, wherein The voltage detection circuit also includes a filter resistor and a filter capacitor; The output terminal of the first operational amplifier is electrically connected to the first terminal of the filter resistor, the second terminal of the filter resistor is electrically connected to the control circuit, and the second terminal of the filter resistor is grounded through the filter capacitor.

8. The junction temperature detection circuit of claim 2, wherein, The voltage detection circuit further includes a second operational amplifier; the first operational amplifier is electrically connected to the control circuit through the second operational amplifier.

9. A junction temperature detection apparatus characterized by comprising: Includes the junction temperature detection circuit as described in any one of claims 1-8.

10. A power system characterized by, Includes the junction temperature detection device as described in claim 9.

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