A junction temperature detection circuit, method and system for a power device

Abstract

The application provides a junction temperature detection circuit, a junction temperature detection method and a system of a power device, wherein the junction temperature detection circuit comprises: a driving unit comprising a first output port connected with a drain electrode of the power device and capable of outputting a current; a capacitor unit connected between the first output port and a ground; a current sampling module connected with a source electrode of the power device and used for detecting a drain current of the power device; a main control unit having a sampling port for collecting a second voltage across the capacitor unit; and the main control unit being connected with the current sampling module, acquiring the drain current of the power device, determining an on-resistance of the power device according to the drain current and the second voltage, and further determining a junction temperature of the power device. The application builds the junction temperature detection circuit of the power device, acquires the on-resistance of the power device, and realizes the detection of the junction temperature of the power device according to the relationship between the on-resistance of the power device and the junction temperature.

Description

Technical Field

[0001] This invention relates to the field of power device testing technology, and more specifically, to a junction temperature detection circuit, junction temperature detection method, and system for power devices. Background Technology

[0002] Datasheets, also known as specification sheets, for power devices such as silicon carbide, insulated-gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and intelligent power modules (IPMs) clearly specify the range of junction temperatures (TJ). Exceeding this range can lead to damage or reduced reliability of the power devices. Since thermocouples cannot be directly placed on the wafer of a power device, it is difficult to measure the junction temperature. Therefore, inverter circuits built using power devices require thermocouples to be placed on the module or inside the power module to collect the device temperature, inferring the device temperature based on the thermocouple readings, and adjusting the device's operating mode accordingly. For circuit topologies composed of discrete power devices, thermocouples need to be fixed at the power devices, increasing the complexity of the printed circuit board assembly (PCBA) manufacturing process. In addition, it is difficult to guarantee the consistency of the thermocouple's fixed position, resulting in poor consistency in temperature sampling.

[0003] Therefore, how to propose a scheme to determine the junction temperature based solely on the on-resistance of discrete power devices without using thermocouples has become an urgent problem to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, the first aspect of this invention provides a junction temperature detection circuit for power devices.

[0005] A second aspect of the present invention also proposes a method for detecting junction temperature.

[0006] A third aspect of the present invention also proposes a junction temperature detection system.

[0007] A fourth aspect of the present invention also proposes a junction temperature detection system.

[0008] A fifth aspect of the invention also proposes a readable storage medium.

[0009] In view of this, the first aspect of the present invention provides a junction temperature detection circuit for a power device, comprising: a driving unit, the driving unit including a first output port connected to the drain of the power device, the first output port being capable of outputting current; a capacitor unit connected between the first output port and ground; a current sampling module connected to the source of the power device for detecting the drain current of the power device; a main control unit having a sampling port for acquiring a second voltage across the capacitor unit; the main control unit being connected to the current sampling module for acquiring the drain current of the power device, determining the on-resistance of the power device based on the drain current and the second voltage, and determining the junction temperature of the power device based on the on-resistance.

[0010] The junction temperature detection circuit for power devices provided by the present invention is used to detect the junction temperature of power devices. By constructing a junction temperature detection circuit for power devices, the on-resistance of the power device is obtained through a capacitor unit and a current sampling module. Then, based on the relationship between the on-resistance and the junction temperature of the power device, the junction temperature of the power device is detected. This eliminates the need for fixing thermocouples near the power device to detect the junction temperature, reducing the complexity of the printed circuit board assembly (PCBA) manufacturing process, avoiding the problem of inconsistent thermocouple positioning, and improving the consistency of temperature sampling.

[0011] In the above technical solution, the current sampling module is a Hall sensor.

[0012] In this technical solution, the current sampling module is a Hall sensor. Specifically, the Hall sensor can obtain either the current signal or the voltage signal of the power device. If it is a current signal, it is directly used as the drain current. Since the voltage across the power device is equal to the second voltage across the capacitor unit, the on-resistance of the power device can be calculated using Ohm's law. If the Hall sensor obtains a voltage signal, the main control unit converts the voltage signal into a drain current, and then the on-resistance of the power device can be calculated using Ohm's law. Of course, the current sampling module can be more than just a Hall sensor; it can also be an operational amplifier circuit, etc.

[0013] In the above technical solution, the junction temperature detection circuit further includes: a sampling resistor unit, one end of which is connected to the source of the power device and the other end is grounded; the current sampling module is used to detect the first voltage across the sampling resistor unit; and the main control unit obtains the drain current based on the first voltage and the sampling resistor unit.

[0014] In this technical solution, current flows through the power device to the sampling resistor unit and then to ground, and also flows through the capacitor unit and then to ground. Therefore, the second voltage across the capacitor unit is equal to the sum of the on-state voltage of the power device and the first voltage across the sampling resistor unit. Knowing both the first and second voltages, the on-state voltage of the power device can be determined. Simultaneously, by acquiring the first voltage across the sampling resistor unit and the resistance value of the sampling resistor unit through the current sampling module, the current flowing through the sampling resistor unit and the power device can be determined. Thus, according to Ohm's law, given the on-state voltage and current of the power device, the on-resistance of the power device can be determined. By obtaining the on-resistance of the power device through the sampling resistor unit and the current sampling module, and then based on the relationship between the on-resistance and junction temperature, the junction temperature of the power device can be detected. This eliminates the need for junction temperature detection using thermocouples fixed near the power device, reducing the complexity of the printed circuit board assembly (PCBA) manufacturing process.

[0015] In the above technical solution, the junction temperature detection circuit of the power device further includes: a voltage conversion module, connected between the first output port and the main control unit, for converting the voltage collected by the sampling port into a second voltage, wherein the second voltage meets the voltage sampling range of the main control unit.

[0016] In this technical solution, considering the voltage sampling range of the main control unit's acquisition port, a voltage conversion module is incorporated to prevent the voltage across the capacitor unit from exceeding the acceptable sampling range of the main control unit's acquisition port. This voltage conversion module converts the voltage across the capacitor unit to conform to the sampling range of the main control unit, thereby protecting the main control unit. The junction temperature detection circuit with the voltage conversion module not only achieves the aforementioned technical effects but also protects the main control unit.

[0017] In the above technical solution, the main control unit determines the junction temperature of the power device based on the on-resistance and the on-resistance-junction temperature correlation table of the power device.

[0018] The datasheet of a power device contains a curve showing the relationship between on-resistance and junction temperature. By converting this curve, an on-resistance-junction temperature correlation table can be obtained and pre-stored in the main control unit. The main control unit can then determine the junction temperature corresponding to the on-resistance by looking up the table in the on-resistance-junction temperature correlation table.

[0019] In the above technical solution, the sampling resistor can be a non-inductive resistor.

[0020] In this technical solution, the non-inductive resistor has the characteristic of low resistance. Therefore, the resistance of the non-inductive resistor is much smaller than the on-resistance of the power device. Thus, when calculating the on-state voltage of the power device, the voltage across the non-inductive resistor can be ignored, which speeds up the calculation of the on-state voltage, makes the main control unit process faster, and thus improves the working efficiency.

[0021] In the above technical solution, the main control unit can determine the current of the power device based on the first voltage and the resistance value of the sampling resistor unit; and determine the on-resistance based on the current and the second voltage.

[0022] In the above technical solution, the current can be a constant current, and the junction temperature detection circuit further includes: a first resistor unit connected between the first output port and the drain of the power device; and the main control unit is also used to: determine the third voltage across the first resistor unit based on the constant current and the resistance value of the first resistor unit; and determine the on-resistance based on the first voltage, the second voltage, the third voltage and the resistance value of the sampling resistor unit.

[0023] In this technical solution, a port of the driving unit with a constant current output is used as a constant current source. By connecting a first resistor unit in series at this port, the port can also be made into a desaturation protection port. The first resistor unit can pull up the voltage of the first output port, so that the first output port can also serve as the desaturation protection port of the driving unit.

[0024] In the above technical solution, the junction temperature detection circuit may further include: a first diode unit connected between the first output port and the drain of the power device; and the main control unit is further configured to: determine the on-resistance based on the first voltage, the second voltage, the on-state voltage of the first diode unit and the resistance value of the sampling resistor unit.

[0025] In this technical solution, the driving unit can be protected by adding a first diode unit to the circuit. Because the first diode unit has unidirectional conduction characteristics, it can protect the driving unit and prevent damage caused by excessively high drain voltage of the power devices.

[0026] In the above technical solution, the junction temperature detection circuit further includes: a first diode unit connected in series with the first resistor unit between the first output port and the drain of the power device; and the main control unit is also used to: determine the on-resistance based on the first voltage, the second voltage, the third voltage, the on-state voltage of the first diode unit and the resistance value of the sampling resistor unit.

[0027] In this technical solution, by simultaneously adding a first resistor unit and a first diode unit to the circuit, the first output port has a desaturation protection function while avoiding damage to the drive unit caused by excessively high drain voltage of the power device.

[0028] A second aspect of the present invention provides a junction temperature detection method for a junction temperature detection circuit of a power device according to any of the above technical solutions. The junction temperature detection method includes: determining the on-resistance of the power device based on the drain current of the power device and the second voltage across the capacitor unit; and determining the junction temperature of the power device based on the on-resistance.

[0029] A third aspect of the present invention provides a junction temperature detection system, comprising: an acquisition module for determining the on-resistance of a power device based on a first voltage across a sampling resistor unit, a second voltage across a capacitor unit, and the resistance value of the sampling resistor unit; and a determination module for determining the junction temperature of the power device based on the on-resistance.

[0030] A fourth aspect of the present invention provides a junction temperature detection system, including a memory and a processor, wherein the memory stores a program or instructions that can run on the processor, and when the program or instructions are executed by the processor, the steps of the junction temperature detection method of any of the above-described technical solutions are implemented.

[0031] A fifth aspect of the present invention provides a readable storage medium having a program and / or instructions stored thereon, wherein the program and / or instructions, when executed by a processor, implement the steps of the junction temperature detection method in any of the above-described technical solutions.

[0032] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0033] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0034] Figure 1 This is a schematic diagram of the junction temperature detection circuit structure of a power device according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the junction temperature detection circuit structure of a power device according to another embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the junction temperature detection circuit structure of a power device according to an embodiment of the present invention;

[0037] Figure 4 This is a graph showing the relationship between the on-resistance and junction temperature of a power device according to an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of the junction temperature detection circuit structure of a power device according to another embodiment of the present invention;

[0039] Figure 6This is a schematic diagram of the junction temperature detection circuit structure of a power device according to another embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of the junction temperature detection circuit structure of a power device according to another embodiment of the present invention;

[0041] Figure 8 This is a schematic flowchart of a junction temperature detection method according to another embodiment of the present invention;

[0042] Figure 9 This is a block diagram of a junction temperature detection system according to another embodiment of the present invention;

[0043] Figure 10 This is a block diagram of a junction temperature detection system according to another embodiment of the present invention.

[0044] in, Figures 1 to 10 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0045] 11 Power device, 12 Drive unit, 121 First output port, 13 Capacitor unit, 14 Sampling resistor unit, 15 Current sampling module, 152 Drain of power device, 153 Source of power device, 16 Main control unit, 17 Voltage conversion module, 18 First resistor unit, 19 First diode unit, 20 Hall sensor, 700 Junction temperature detection system, 702 Acquisition module, 704 Determination module, 800 Junction temperature detection system, 802 Memory, 804 Processor. Detailed Implementation

[0046] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0047] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0048] The following reference Figures 1 to 10 This invention describes junction temperature detection circuits, methods, and systems for power devices in some embodiments.

[0049] Example 1

[0050] This embodiment proposes a junction temperature detection circuit for power device 11, such as... Figure 1As shown, the system includes a drive unit 12, a capacitor unit 13, a current sampling module 15, and a main control unit 16. The drive unit 12 has a first output port 121 capable of outputting current. The first output port 121 is connected to the drain 152 of the power device 11. One end of the capacitor unit 13 is connected to the first output port 121, and the other end is grounded. It should be understood that the capacitor unit 13 can consist of one or more capacitors, which can be connected in parallel and / or in series. Of course, the capacitor unit 13 can also contain other components that function as capacitors. Furthermore, the current sampling module 15 is connected to the source 153 of the power device 11 to detect the drain current 152 of the power device 11. Furthermore, the main control unit 16 can collect the voltage across the capacitor unit 13, and the collected voltage is used as a second voltage. Furthermore, the main control unit 16 is connected to the current sampling module 15 and can acquire the drain current 152 of the power device 11 collected by the current sampling module 15. In this way, the current flows to ground through the power device 11 on one hand, and to ground after passing through the capacitor unit 13 on the other. In this scheme, the second voltage across the capacitor unit 13 is equal to the on-state voltage of the power device 11. At the same time, in this embodiment, the current sampling module 15 collects the drain current 152 of the power device 11. Thus, when both the on-state voltage and the current of the power device 11 are known, the on-state voltage of the power device 11 can be determined.

[0051] Example 2

[0052] This embodiment proposes a junction temperature detection circuit for power device 11, such as... Figure 2As shown, the system includes a drive unit 12, a capacitor unit 13, a Hall sensor 20, and a main control unit 16. The drive unit 12 has a first output port 121 capable of outputting current. The first output port 121 is connected to the drain 152 of the power device 11. One end of the capacitor unit 13 is connected to the first output port 121, and the other end is grounded. The Hall sensor 20 is connected to the source 153 of the power device 11 and is used to detect the drain current 152 of the power device 11. Furthermore, the main control unit 16 can acquire the voltage across the capacitor unit 13, and the acquired voltage is used as a second voltage. Furthermore, the main control unit 16 is connected to the Hall sensor 20 and can acquire the drain current 152 of the power device 11 acquired by the Hall sensor 20. Thus, the current flows to ground through the power device 11 on one hand, and to ground after passing through the capacitor unit 13 on the other. In this scheme, the second voltage across capacitor unit 13 is equal to the on-state voltage of power device 11. Simultaneously, in this embodiment, Hall sensor 20 collects the drain current 152 of power device 11. Thus, given that both the on-state voltage and current of power device 11 are known, the on-state voltage of power device 11 can be determined. Of course, in this embodiment, Hall sensor 20 can also obtain the voltage signal of power device 11. If a voltage signal is obtained, the main control unit 16 will convert the voltage signal into drain current 152, and then calculate the on-resistance of power device 11 using Ohm's law.

[0053] Example 3

[0054] This embodiment proposes a junction temperature detection circuit for power device 11, such as... Figure 3 As shown, it includes a drive unit 12, a capacitor unit 13, a sampling resistor unit 14, a current sampling module 15, and a main control unit 16.

[0055] The driving unit 12 has a first output port 121 capable of outputting current. The first output port 121 is connected to the drain 152 of the power device 11. One end of the capacitor unit 13 is connected to the first output port 121, and the other end is grounded. It should be understood that the capacitor unit 13 can be composed of one or more capacitors, and when the capacitor unit 13 is composed of multiple capacitors, the multiple capacitors can be connected in parallel and / or in series. Of course, the capacitor unit 13 can also contain other components that function as capacitors. Further, the sampling resistor unit 14 is connected between the source 153 of the power device 11 and ground. The sampling resistor unit 14 can be composed of one or more resistors connected in series and parallel. The current sampling module 15 is connected to both ends of the sampling resistor unit 14 to obtain the voltage across the sampling resistor unit 14. Further, the main control unit 16 can collect the voltage across the capacitor unit 13, and the collected voltage is used as a second voltage. Further, the main control unit 16 is connected to the current sampling module 15 and can obtain the first voltage across the sampling resistor unit 14 collected by the current sampling module 15.

[0056] The first output port 121 of the drive unit 12 can output current. This current flows through the power device 11 to the sampling resistor unit 14 and then to ground, and also flows through the capacitor unit 13 and then to ground. Therefore, the second voltage across the capacitor unit 13 is equal to the sum of the on-state voltage of the power device 11 and the first voltage across the sampling resistor unit 14. Knowing both the first and second voltages, the on-state voltage of the power device 11 can be determined. Simultaneously, by acquiring the first voltage across the sampling resistor unit 14 and the resistance value of the sampling resistor unit 14 through the current sampling module 15, the current flowing through the sampling resistor unit 14 and the power device 11 can be determined. Because this current flows through the power device 11, its on-resistance can be determined according to Ohm's law, given that the on-state voltage and current of the power device 11 are known.

[0057] The datasheet for power device 11 specifies the relationship between junction temperature and on-resistance. Therefore, once the on-resistance is known, the junction temperature can be determined based on the on-resistance.

[0058] According to an embodiment of this application, a junction temperature detection circuit for a power device 11 is constructed. This circuit can calculate the on-resistance of the power device 11, and based on the relationship between the junction temperature and on-resistance, the junction temperature of the power device 11 is detected. This eliminates the need to detect the junction temperature of the power device by fixing a thermocouple near it, reducing the complexity of the PCBA manufacturing process and avoiding the problem of inconsistent thermocouple placement, thus improving the consistency of temperature sampling. Furthermore, since this application can detect the junction temperature of the power device 11 without fixing a thermocouple, it simplifies the number of components in the device, reduces production costs, and solves the problem of difficult thermocouple assembly.

[0059] Those skilled in the art should understand that the first output port 121 of the drive unit 12 can be any pin of the drive unit capable of outputting current, and for a drive unit with a desaturation (DESAT) pin, it can also be a DESAT pin.

[0060] Furthermore, the junction temperature detection circuit of the above embodiment may also include a voltage conversion module 17.

[0061] A voltage conversion module 17 can be positioned between the main control unit 16 and the first output port 121 of the drive unit 12. Because the second voltage across the capacitor unit 13 sampled by the main control unit 16 may exceed the voltage sampling range that the main control unit 16's sampling port can withstand, a voltage conversion module 17 can be provided to protect the main control unit 16. The voltage conversion module 17 can convert the second voltage across the capacitor unit 13 to conform to the sampling range of the main control unit 16 before inputting it into the main control unit 16. Using a junction temperature detection circuit with a voltage conversion module 17 not only achieves the aforementioned technical effects but also protects the main control unit 16. In actual testing, the voltage conversion ratio of the voltage conversion module 17 can be adjusted according to the actual situation. For example, when the maximum voltage value that the acquisition port of the main control unit 16 can withstand is large, the voltage conversion ratio of the voltage conversion module 17 can be set relatively small, such as 1 to 10 times. When the maximum voltage value that the acquisition port of the main control unit 16 can withstand is small, the voltage conversion ratio of the voltage conversion module 17 can be set relatively large, such as 10 to 100 times. This not only ensures the safety of the main control unit 16 but also guarantees calculation efficiency. Furthermore, the voltage conversion module 17 can select any type of transformer, such as a transformer or transformer coil.

[0062] In the above embodiment, the main control unit 16 can determine the junction temperature of the power device 11 based on the on-resistance and the on-resistance-junction temperature correlation table of the power device 11.

[0063] The datasheet for power device 11 will include a graph showing the relationship between junction temperature and on-resistance, such as... Figure 4 As shown, Figure 4 This shows the drain-source current I in the power device. ds 20A, gate-source voltage V gs This diagram illustrates the relationship between junction temperature and on-resistance of a power device under conditions of 15V and a time frame within 200 microseconds. The vertical axis represents the on-resistance of the power device, and the horizontal axis represents its junction temperature. In this embodiment, the on-resistance-junction temperature relationship curve can be transformed to obtain an on-resistance-junction temperature correlation table, as shown in Table 1 below. This table can be pre-stored in the main control unit 16. After determining the on-resistance, the main control unit 16 can determine the corresponding junction temperature by looking up the table.

[0064] Table 1

[0065] Junction temperature YY1 YY2 YY3 YY4 ...... YYY

[0066] In the above embodiments, the sampling resistor can also be a non-inductive resistor.

[0067] Because non-inductive resistors have low resistance, their resistance is much smaller than the on-resistance of power device 11. Therefore, when calculating the on-state voltage of power device 11, the voltage across the non-inductive resistor can be ignored, accelerating the calculation of the on-state voltage and allowing the main control unit 16 to process the data faster, thus improving work efficiency. Furthermore, compared to ordinary resistors, non-inductive resistors used in this application have the following advantages: 1. The inductance of the resistor itself is very small (only a few microhenries), with excellent frequency response characteristics. Besides being widely used in AC and DC circuits, it is more suitable for medium and high frequency circuits. 2. The volt-ampere characteristic is linear, with stable electrical performance, high voltage resistance, and good insulation performance, avoiding leakage during detection. 3. Strong overload capacity, particularly suitable for intermittent power supply and pulsed high-current circuits, with a wide range of applications. 4. Good temperature characteristics, a wide applicable temperature range, high mechanical strength, and resistance to cold and thermal shock, ensuring detection efficiency in any environment. Furthermore, a high-precision non-inductive resistor (with an accuracy of 0.01%, or one ten-thousandth of an accuracy) can be selected, which makes the sampled voltage very reliable.

[0068] Example 4

[0069] In Example 2, as Figure 5As shown, the junction temperature detection circuit includes: a driving unit 12, a capacitor unit 13, a sampling resistor unit 14, a current sampling module 15, a main control unit 16, and a first resistor unit 18. Compared with the junction temperature detection circuit of the power device 11 in Embodiment 1, the current in this embodiment is a constant current, and a first resistor unit 18 is added.

[0070] One end of the first resistor unit 18 is connected to the drain 152 of the power device 11, and the other end is connected to the first output port 121 of the drive unit 12. The first resistor unit 18 can be composed of one or more resistors connected in series and parallel.

[0071] Since the resistance of the first resistor unit 18 is known, and the first output port outputs a constant current, the main control unit 16 can determine the voltage across the first resistor unit 18 based on the known resistance and the constant current.

[0072] In this embodiment, the second voltage across capacitor unit 13 is equal to the sum of the third voltage across first resistor unit 18, the on-state voltage of power device 11, and the first voltage across sampling resistor unit 14. Given that the first, second, and third voltages are all known, the on-state voltage of power device 11 can be calculated. With the on-state voltage and current of power device 11 known, the on-resistance can be further determined.

[0073] In this embodiment, by setting the first resistor unit 18, the voltage of the first output port can be made high enough to achieve the desaturation protection function of the drive unit 12.

[0074] Example 5

[0075] In Example 3, as Figure 6 As shown, the junction temperature detection circuit of this embodiment includes: a driving unit 12, a capacitor unit 13, a sampling resistor unit 14, a current sampling module 15, a main control unit 16, and a first diode unit 19. Compared with the junction temperature detection circuit of the power device 11 in Embodiment 1, a first diode unit 19 is added. The first diode unit 19 is disposed between the drain 152 of the power device 11 and the first output port 121 of the driving unit 12.

[0076] In this embodiment, the voltage across capacitor unit 13 is equal to the sum of the forward voltage of first diode unit 19, the on-state voltage of power device 11, and the first voltage across sampling resistor unit 14. Given the forward voltage of the first diode unit and the first voltage, the on-state voltage of power device 11 can be obtained. Furthermore, according to Ohm's law, given the on-state voltage and current of power device 11, the on-resistance can be determined.

[0077] By setting the first diode unit 19, the unidirectional conduction characteristic of the first diode unit 19 is used to protect the drive unit 12 and prevent damage to the drive unit 12 caused by excessive voltage at the drain 152 of the power device 11.

[0078] Example 6

[0079] In Example 4, as Figure 7 As shown, the junction temperature detection circuit includes: a driving unit 12, a capacitor unit 13, a sampling resistor unit 14, a current sampling module 15, a main control unit 16, a first resistor unit 18, and a first diode unit 19. Compared with the junction temperature detection circuit of the power device 11 in Embodiment 1, the current in this embodiment is a constant current, and the first resistor unit 18 and the first diode unit 19 are added.

[0080] In this embodiment, the main control unit 16 is the main control chip IC1, the drive unit 12 is the drive unit IC2, and the power device 11 is the power device Q1. R1, D1, and C1 constitute the peripheral circuit of the DESAT pin of the drive unit IC2. The main control chip IC1 obtains the voltage value of the DESAT pin through the AD sampling pin. The voltage of the DESAT pin is often higher than the power supply voltage of the main control chip IC1, so a voltage conversion module 17 is added between the DESAT pin and the voltage sampling pin of the main control chip IC1. RS is a non-inductive resistor used to detect the current flowing through it. The current sampling module 15 inputs the collected voltage value to the main control chip IC1, and the current value flowing through the sampling resistor RS is obtained after internal logic conversion.

[0081] The working principle of the DESAT pin of drive unit 12 is as follows: When power device Q1 is turned on, the current source in the DESAT pin of drive unit IC2 flows into ground (GND) through R1, D1 and Q1. When power device Q1 is turned off, the current source in the DESAT pin of drive unit IC2 stops working.

[0082] The main control chip IC1 calculates the voltage value of the DESAT pin using the voltage conversion module 17 according to the following formula: VDSON = VDESAT - VR1 - VD1 - VRS, where VDSON represents the on-state voltage of power device Q1, VDESAT represents the voltage value of the DESAT pin, VR1 represents the voltage value across resistor R1, VD1 represents the voltage value across diode D1, and VRS represents the voltage value across resistor RS. Since the value of RDSON is much larger than the value of RS, the voltage of VRS can be ignored, and VDSON = VDESAT - VR1 - VD1 is used. The main control chip IC1 can calculate the current flowing through RS using the current sampling module 15. From this, the power device RDSON = VDSON / IRS can be calculated. Then, by looking up the correspondence table between RDSON and TJ, the TJ value can be obtained through RDSON.

[0083] The voltage input to the voltage conversion module 17 must meet the voltage sampling range of the main control chip IC1, and the voltage input to the voltage conversion module 17 must still meet the sampling range of the main control chip IC1 when the drive unit DESAT pin generates desaturation protection.

[0084] Meanwhile, by adding the first resistor unit 18 and the first diode unit 19 to the circuit, the circuit can have desaturation protection function and also avoid damage to the drive unit 12 caused by excessive voltage at the drain 152 of the power device 11.

[0085] Example 7

[0086] This embodiment provides a junction temperature detection method for detecting the junction temperature of power devices, such as... Figure 8 As shown, the junction temperature detection methods include:

[0087] S602, determine the on-resistance of the power device based on the first voltage across the sampling resistor unit, the second voltage across the capacitor unit, and the resistance value of the sampling resistor unit;

[0088] S604 determines the junction temperature of power devices based on their on-resistance.

[0089] According to the junction temperature detection method provided in this embodiment, the voltage across the sampling resistor unit is collected, and the current flowing through the sampling resistor unit is calculated by combining the known resistance value of the sampling resistor unit. Since the current flows through the power device and then through the sampling resistor unit before grounding, the current flowing through the power device is the same as the current flowing through the sampling resistor unit. Therefore, the current flowing through the sampling resistor and the power device can be determined by using the voltage across the sampling resistor and the resistance value collected by the current sampling module. Furthermore, since the current at the first output port of the drive unit flows through the power device to the sampling resistor unit and then to ground, and also flows through the capacitor unit and then to ground, the voltage across the capacitor unit is equal to the sum of the voltage across the power device and the voltage across the sampling resistor unit. That is, the sum of the first voltage and the on-state voltage of the power device is the second voltage, thus allowing the determination of the on-state voltage of the power device. Therefore, according to Ohm's law, the on-resistance of the power device can be determined when the on-state voltage and current of the power device are known. This application establishes a junction temperature detection circuit for a power device to obtain the on-resistance of the power device. Based on the relationship between the on-resistance and junction temperature of the power device, the junction temperature of the power device is detected. This eliminates the need to perform junction temperature detection by fixing thermocouples near the power device, reducing the complexity of the PCBA manufacturing process, avoiding the problem of inconsistent thermocouple fixing positions, and improving the consistency of temperature sampling.

[0090] Furthermore, the junction temperature of the power device is determined based on the on-resistance and the on-resistance-junction temperature correlation table of the power device.

[0091] Since the datasheets for power devices specify a curve relating on-resistance to junction temperature, this curve can be transformed to obtain an on-resistance-junction temperature correlation table, which is then pre-stored in the main control unit. The main control unit can then determine the corresponding junction temperature based on the given on-resistance by looking up the table. This eliminates the need for fixing thermocouples near the power device for junction temperature detection, reducing the complexity of the PCBA manufacturing process, avoiding the inconsistency in thermocouple placement, and improving the consistency of temperature sampling.

[0092] The present invention also provides a junction temperature detection system 700, such as Figure 9 As shown, it includes an acquisition module 702 and a determination module 704. The acquisition module 702 is used to determine the on-resistance of the power device based on a first voltage across the sampling resistor unit, a second voltage across the capacitor unit, and the resistance value of the sampling resistor unit. The determination module 704 is used to determine the junction temperature of the power device based on the on-resistance.

[0093] An embodiment of the present invention also provides a junction temperature detection system 800, such as... Figure 10 As shown, the system includes a memory 802 and a processor 804, as well as a program stored in the memory 802 and executable on the processor 804. When the program is executed by the processor 804, it implements the steps defined by any of the aforementioned junction temperature detection methods. Furthermore, since the junction temperature detection system 800 of this application can implement the steps defined by any of the aforementioned junction temperature detection methods, the junction temperature detection system 800 provided in this embodiment has all the beneficial effects of the junction temperature detection methods provided in any of the aforementioned embodiments.

[0094] According to embodiments of the present invention, a readable storage medium is also provided, on which a program and / or instructions are stored, which, when executed by a processor, implement the steps of the junction temperature detection method in any of the above embodiments.

[0095] The readable storage medium provided according to the embodiments of the present invention has all the beneficial technical effects of the junction temperature detection method described above, since the program and / or instructions stored thereon can implement the steps of the junction temperature detection method in any of the above embodiments when executed by a processor, and will not be repeated here.

[0096] In this specification, the term "multiple" refers to two or more unless otherwise expressly defined. The terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0097] In the description of this specification, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0098] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A junction temperature detection circuit for a power device, characterized in that, include: The driving unit includes a first output port, which is connected to the drain of the power device and is capable of outputting current. A capacitor unit is connected between the first output port and ground; A current sampling module is connected to the source of the power device and is used to detect the drain current of the power device. The main control unit has a sampling port, through which it acquires the second voltage across the capacitor unit; The main control unit is connected to the current sampling module to acquire the drain current of the power device, determine the on-resistance of the power device based on the drain current of the power device and the second voltage, and determine the junction temperature of the power device based on the on-resistance. The sampling resistor unit has one end connected to the source of the power device and the other end grounded. The current sampling module is used to detect the first voltage across the sampling resistor unit; The main control unit obtains the drain current based on the first voltage and the sampling resistor unit; The second voltage across the capacitor unit is equal to the sum of the on-state voltage of the power device and the first voltage across the sampling resistor unit.

2. The junction temperature detection circuit for the power device according to claim 1, characterized in that, The current sampling module is a Hall sensor.

3. The junction temperature detection circuit for the power device according to claim 1 or 2, characterized in that, Also includes: A voltage conversion module is connected between the first output port and the main control unit to convert the voltage collected by the sampling port into the second voltage, wherein the second voltage meets the voltage sampling range of the main control unit.

4. The junction temperature detection circuit for the power device according to claim 1, characterized in that, The main control unit determines the junction temperature of the power device based on the on-resistance and the on-resistance-junction temperature correlation table of the power device.

5. The junction temperature detection circuit for the power device according to claim 1, characterized in that, The sampling resistor unit is a non-inductive resistor.

6. The junction temperature detection circuit for the power device according to claim 1, characterized in that, The main control unit is used for: The current of the power device is determined based on the first voltage and the resistance value of the sampling resistor unit; and The on-resistance is determined based on the current and the second voltage.

7. The junction temperature detection circuit for the power device according to claim 1, characterized in that, The current is a constant current, and the junction temperature detection circuit further includes: A first resistor unit is connected between the first output port and the drain of the power device; and The main control unit is further configured to: determine a third voltage across the first resistor unit based on the constant current and the resistance value of the first resistor unit; and The on-resistance is determined based on the first voltage, the second voltage, the third voltage, and the resistance value of the sampling resistor unit.

8. The junction temperature detection circuit for the power device according to claim 1, characterized in that, The junction temperature detection circuit also includes: A first diode unit is connected between the first output port and the drain of the power device; and The main control unit is also used for: The on-resistance is determined based on the first voltage, the second voltage, the on-state voltage of the first diode unit, and the resistance value of the sampling resistor unit.

9. The junction temperature detection circuit for the power device according to claim 7, characterized in that, The junction temperature detection circuit also includes: A first diode unit is connected in series with the first resistor unit between the first output port and the drain of the power device; and The main control unit is also used for: The on-resistance is determined based on the first voltage, the second voltage, the third voltage, the on-state voltage of the first diode unit, and the resistance value of the sampling resistor unit.

10. A method for detecting the junction temperature of a power device, characterized in that, A junction temperature detection circuit for a power device as described in any one of claims 1 to 9, the junction temperature detection method comprising: The on-resistance of the power device is determined based on the drain current of the power device and the second voltage across the capacitor unit. The junction temperature of the power device is determined based on the on-resistance.

11. The junction temperature detection method according to claim 10, characterized in that, Determining the junction temperature of the power device based on the on-resistance specifically includes: The junction temperature of the power device is determined based on the on-resistance and the on-resistance-junction temperature correlation table of the power device.

12. The junction temperature detection method according to claim 10 or 11, characterized in that, The junction temperature detection circuit further includes: a sampling resistor unit, one end of which is connected to the source of the power device, and the other end of which is grounded; the current sampling module is used to detect a first voltage across the sampling resistor unit; the junction temperature detection method further includes: The drain current is obtained based on the first voltage and the sampling resistor unit.

13. A junction temperature detection system for a power device, characterized in that, include: The acquisition module is used to determine the on-resistance of the power device based on the drain current of the power device and the second voltage across the capacitor unit. A determining module is used to determine the junction temperature of the power device based on the on-resistance; The second voltage across the capacitor unit is equal to the sum of the on-state voltage of the power device and the first voltage across the sampling resistor unit.

14. A junction temperature detection system for a power device, characterized in that, It includes a memory and a processor, the memory storing a program or instructions that can run on the processor, the program or instructions being executed by the processor to implement the steps of the junction temperature detection method as described in any one of claims 10 to 12.

15. A readable storage medium, characterized in that, It stores a program and / or instructions thereon, which, when executed by a processor, implement the steps of the junction temperature detection method as described in any one of claims 10 to 12.

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