IGBT module temperature measurement circuit, temperature measurement method and computer readable storage medium

Abstract

The present invention provides an IGBT module temperature measurement circuit, a temperature measurement method and a computer-readable storage medium, wherein the circuit part includes a comparator U1, a power port V cc , capacitor C1, first MOSFET tube Q1 and reference resistor; the power port V cc are electrically connected to the first node and the reverse input terminal of the comparator U1 respectively; the power port V cc It is also electrically connected to the power supply terminal of the comparator U1; in addition to the power supply port V cc In addition to being electrically connected, the first node is also electrically connected to the same-direction input terminal of the comparator U1, the capacitor C1, and the source of the first MOSFET tube Q1; the drain of the first MOSFET tube Q1 is electrically connected to the signal ground; the gate of the first MOSFET tube Q1 is electrically connected to the output terminal of the comparator U1; one end of the capacitor C1 is electrically connected to the first node, and the other end is electrically connected to the signal ground; the ground terminal of the comparator U1 is electrically connected to the signal ground; the reference resistor is arranged at a set position of the IGBT module temperature measurement circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of IGBT module temperature measurement, and specifically to an IGBT module temperature measurement circuit, a temperature measurement method and a computer-readable storage medium, and in particular to an IGBT module temperature measurement circuit, a temperature measurement method and a computer-readable storage medium for detecting the temperature of an NTC resistor inside an IGBT module. Background Art

[0002] In today's context of increasingly stringent requirements for power supply quality, users are also increasingly demanding the reliability of power electronic equipment. IGBT (Insulated Gate Bipolar Transistor) modules are the mainstream switching devices currently used in high-power power electronic equipment, and are also the most important components in high-power power electronic equipment. Its reliability is an important guarantee for the reliability of high-power power electronic equipment. Therefore, improving its reliability has become the primary way to improve the reliability of high-power power electronic equipment.

[0003] There are three main reasons for IGBT module failure: overvoltage; overcurrent; overtemperature. Since voltage and current are signals that must be collected by power electronic equipment, overvoltage or overcurrent can be prevented through software or hardware circuits. Therefore, overtemperature becomes the main reason for IGBT module failure.

[0004] The bottleneck of preventing IGBT modules from overheating is how to obtain the temperature of the tube core inside the IGBT module in real time and accurately. An NTC temperature measuring resistor is usually placed near the tube core inside the IGBT module. The temperature difference between this resistor and the IGBT tube core is generally within 10°C. Therefore, obtaining the resistance value of this NTC resistor in real time and accurately is the key.

[0005] There are two main ways to obtain the resistance value of NTC resistors: one is a temperature detection circuit based on AD (analog / digital) conversion. For example, the patent document CN204241124U discloses a wide-range NTC temperature measurement device, which uses a constant value resistor and an NTC resistor in series and connects them to both ends of a DC power supply to form a voltage divider circuit. The voltage signal obtained on the NTC resistor is sent to the AD converter to be converted into a digital signal, and then the temperature value is obtained by looking up the table. There are two disadvantages of this circuit. First, the stability and accuracy of the DC voltage determine the accuracy of temperature sampling; second, an AD conversion circuit is required, which is usually expensive, so the cost of implementation is high.

[0006] The other type is a temperature detection circuit based on VF (voltage / frequency) conversion. For example, patent document CN203965065U discloses a temperature measurement circuit for an IGBT die. There are two types of VF conversion circuits. One type uses LM331 as the control chip of the VF conversion circuit. Figure 3 As shown, the frequency output by this circuit is:

[0007]

[0008] It can be seen from here that the output frequency is not only related to the resistance value of the NTC resistor, but also to the power supply voltage V cc and the capacitance of capacitor Ct, so the accuracy of temperature detection also depends on the power supply voltage V cc And the accuracy of capacitor Ct. Therefore, to obtain accurate temperature values, high-precision power supply and high-precision capacitors are required, especially capacitors. For large-capacity capacitors, their accuracy is usually only 20%, which has a great impact on the accuracy of temperature detection.

[0009] Another VF conversion circuit described in the patent uses AD7740 as the control chip. This control chip is a synchronous VF conversion controller, and its output signal is synchronized with its clock signal (such as Figure 5 As shown in the figure, when the frequency of the clock signal and the frequency of the output signal are not integer multiples, the output frequency will fluctuate. For example, when the frequency to be output is 3 / 10 times the clock frequency, the output frequency fluctuates between 1 / 4 and 1 / 3 of the clock frequency. Therefore, after the processor obtains the frequency of the output signal, it still needs to pass through a low-pass filter with a very low cutoff frequency to obtain the accurate output frequency, which reduces the real-time performance of temperature detection.

[0010] like Figure 4 As shown, the output frequency of the circuit is:

[0011]

[0012] It can be seen from this formula that its output frequency and clock signal frequency f CLKIN Since the clock signal is generated from a crystal, its accuracy is very high. However, its output frequency is still related to the power supply voltage V cc Therefore, its temperature sampling accuracy depends on the accuracy of its power supply voltage.

[0013] In summary, providing a novel IGBT module temperature measurement circuit, temperature measurement method and computer-readable storage medium has high necessity and application value. Summary of the invention

[0014] In view of the defects in the prior art, an object of the present invention is to provide an IGBT module temperature measurement circuit, a temperature measurement method and a computer-readable storage medium.

[0015] According to the present invention, an IGBT module temperature measurement circuit includes a comparator U1, a power port V cc , capacitor C1, first MOSFET tube Q1 and reference resistor;

[0016] The power port V cc are electrically connected to the first node and the reverse input terminal of the comparator U1 respectively; the power port V cc It is also electrically connected to the power supply terminal of the comparator U1;

[0017] In addition to the power supply port V cc In addition to being electrically connected, the first node is also electrically connected to the non-inverting input terminal of the comparator U1, the capacitor C1, and the source of the first MOSFET tube Q1;

[0018] The drain of the first MOSFET tube Q1 is electrically connected to the signal ground; the gate of the first MOSFET tube Q1 is electrically connected to the output end of the comparator U1;

[0019] One end of the capacitor C1 is electrically connected to the first node, and the other end is electrically connected to the signal ground;

[0020] The ground terminal of the comparator U1 is electrically connected to the signal ground;

[0021] The reference resistor is arranged at a setting position of the IGBT module temperature measurement circuit.

[0022] Preferably, the IGBT module temperature measurement circuit further includes an IGBT module temperature measurement element; the IGBT module temperature measurement element is arranged at the power port V cc and the first node, including the thermistor.

[0023] Preferably, a second node is further provided between the first node and the non-inverting input terminal of the comparator U1; the reference resistor includes a standard resistor R ref ;

[0024] The standard resistance R ref is disposed between the first node and the second node;

[0025] One end of the capacitor C1 passes through the second node, the standard resistor R ref One end is electrically connected to the first node, and the other end is electrically connected to the signal ground.

[0026] Preferably, the reference resistor further includes a fourth resistor R4; the output end of the comparator U1 is also connected to the power port V via the fourth resistor R4. cc Electrical connection.

[0027] Preferably, the reference resistor further comprises a first resistor R1; the power port V cc A third node is also provided between the inverting input terminal of the comparator U1; the first resistor R1 is provided at the power supply port V cc Between the third node.

[0028] Preferably, the reference resistor further includes a second resistor R2; the third node is electrically connected to the first resistor R1 and the inverting input terminal of the comparator U1 respectively, and is also electrically connected to the signal ground through the second resistor R2.

[0029] Preferably, the IGBT module temperature measurement circuit also includes a second MOSFET tube Q2; the source of the second MOSFET tube Q2 is electrically connected to the third node; the drain of the second MOSFET tube Q2 is electrically connected to the signal ground; and the gate of the second MOSFET tube Q2 is electrically connected to the output end of the comparator U1.

[0030] Preferably, the reference resistor further includes a third resistor R3; the third resistor R3 is arranged between the third node and the source of the second MOSFET tube Q2.

[0031] According to the present invention, a method for measuring temperature of an IGBT module comprises the following steps:

[0032] Step 1: Measure the charging time T of capacitor C1 H ;

[0033] Step 2: Measure the discharge time T of capacitor C1 L ;

[0034] Step 3: Calculate T H / T L , and according to T H / T L , check the settings - Temperature table to obtain the corresponding temperature value.

[0035] According to a computer-readable storage medium storing a computer program provided by the present invention, when the computer program is executed by a processor, the steps of the above-mentioned IGBT module temperature measurement method are implemented.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The IGBT module temperature measurement circuit provided by the present invention has the advantages of simple structure, high reliability and good versatility;

[0038] 2. The IGBT module temperature measurement circuit provided by the present invention has extremely low material cost. According to statistics, excluding the NTC resistor, the material cost after mass production is only RMB 0.28 (based on the material price in 2016);

[0039] 3. The IGBT module temperature measurement circuit provided by the present invention can maintain a temperature measurement accuracy of 1°C within a temperature measurement range of 0-150°C at an extremely low material cost, which is sufficient for the temperature measurement of the IGBT module;

[0040] 4. The IGBT module temperature measurement circuit, temperature measurement method and computer-readable storage medium provided by the present invention have no requirements on the accuracy of the power supply and capacitor, and do not require calibration or adjustment during the production process, so they are easy to achieve mass production and reduce labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0042] Figure 1 A circuit diagram of a preferred example of an IGBT module temperature measurement circuit provided by the present invention;

[0043] Figure 2 A schematic diagram of waveforms of the comparator's in-phase input terminal, inverting input terminal, and output terminal in a preferred example of the IGBT module temperature measurement circuit provided by the present invention;

[0044] Figure 3 It is a circuit diagram of a temperature detection circuit using LM331 in the prior art;

[0045] Figure 4 It is a circuit diagram of a temperature detection circuit using AD7740 in the prior art;

[0046] Figure 5 It is the output waveform of the temperature detection circuit using AD7740 in the prior art. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0048] According to the present invention, an IGBT module temperature measurement circuit includes a comparator U1, a power port V cc , capacitor C1, first MOSFET tube Q1 and reference resistor; the power port V ccare electrically connected to the first node and the reverse input terminal of the comparator U1 respectively; the power port V cc It is also electrically connected to the power supply terminal of the comparator U1; in addition to the power supply port V cc In addition to being electrically connected, the first node is also electrically connected to the same-direction input terminal of the comparator U1, the capacitor C1, and the source of the first MOSFET tube Q1; the drain of the first MOSFET tube Q1 is electrically connected to the signal ground; the gate of the first MOSFET tube Q1 is electrically connected to the output terminal of the comparator U1; one end of the capacitor C1 is electrically connected to the first node, and the other end is electrically connected to the signal ground; the ground terminal of the comparator U1 is electrically connected to the signal ground; the reference resistor is arranged at a set position of the IGBT module temperature measurement circuit.

[0049] Specifically, the IGBT module temperature measurement circuit also includes an IGBT module temperature measurement element; the IGBT module temperature measurement element is arranged at the power port V cc and the first node, including a thermistor. A second node is also provided between the first node and the same-direction input terminal of the comparator U1; the reference resistor includes a standard resistor R ref ; The standard resistance R ref Set between the first node and the second node; one end of the capacitor C1 passes through the second node, the standard resistor R ref The reference resistor also includes a fourth resistor R4; the output end of the comparator U1 is also connected to the power port V via the fourth resistor R4. cc The reference resistor also includes a first resistor R1; the power port V cc A third node is also provided between the inverting input terminal of the comparator U1; the first resistor R1 is provided at the power supply port V cc Between the third node.

[0050] More specifically, the reference resistor also includes a second resistor R2; the third node is electrically connected to the first resistor R1 and the reverse input terminal of the comparator U1 respectively, and is also electrically connected to the signal ground through the second resistor R2. The IGBT module temperature measurement circuit also includes a second MOSFET tube Q2; the source of the second MOSFET tube Q2 is electrically connected to the third node; the drain of the second MOSFET tube Q2 is electrically connected to the signal ground; the gate of the second MOSFET tube Q2 is electrically connected to the output terminal of the comparator U1. The reference resistor also includes a third resistor R3; the third resistor R3 is arranged between the third node and the source of the second MOSFET tube Q2.

[0051] According to the present invention, a method for measuring temperature of an IGBT module comprises the following steps:

[0052] Step 1: Measure the charging time T of capacitor C1 H ;

[0053] Step 2: Measure the discharge time T of capacitor C1 L ;

[0054] Step 3: Calculate T H / T L , and according to T H / T L , check the settings - Temperature table to obtain the corresponding temperature value.

[0055] According to a computer-readable storage medium storing a computer program provided by the present invention, when the computer program is executed by a processor, the steps of the above-mentioned IGBT module temperature measurement method are implemented.

[0056] Furthermore, the key technical points of the preferred embodiment of the present invention are:

[0057] 1. Measure the resistance of the thermistor by detecting the pulse width ratio;

[0058] 2. The detection accuracy is not affected by the power supply voltage and capacitance accuracy, but only depends on the accuracy of the resistor.

[0059] In view of the problems of the prior art, the preferred example of the present invention proposes an NTC temperature measurement circuit based on pulse width ratio detection, which can avoid the use of high-precision power supplies and high-precision capacitors, and the components used are low-cost, the circuit is stable and reliable, and is suitable for mass production. The main principle of the circuit is to use NTC resistors to participate in circuit oscillation to form pulses. The positive pulse width is proportional to the resistance value of the NTC resistor, and the negative pulse width is proportional to the resistance value of the standard resistor. By calculating the ratio of the positive and negative pulse widths, the temperature value can be calculated. The temperature measurement accuracy of the present invention only depends on the accuracy of the resistor, and the accuracy of the resistor is usually easy to make relatively high, so the circuit of the present invention has a higher temperature measurement accuracy.

[0060] The circuit of the preferred embodiment of the present invention includes a thermistor NTC, a resistor R ref , resistor R1, resistor R2, resistor R3, resistor R4, capacitor C1, MOSFET tube Q1, MOSFET tube Q2, comparator U1, one end of the thermistor NTC is connected to the power supply, and the other end is connected to the source of the MOSFET tube Q1, the drain of the MOSFET tube Q1 is connected to the signal ground, and the gate is connected to the output end of the comparator U1, the resistor R refOne end of the resistor R1 is connected to the source of the MOSFET tube Q1, and the other end is connected to the non-inverting input terminal of the comparator U1. One end of the capacitor C1 is connected to the non-inverting input terminal of the comparator U1, and the other end is connected to the signal ground. One end of the resistor R1 is connected to the power supply, and the other end is connected to the inverting input terminal of the comparator U1. One end of the resistor R2 is connected to the inverting input terminal of the comparator U1, and the other end is connected to the signal ground. One end of the resistor R3 is connected to the inverting input terminal of the comparator U1, and the other end is connected to the source of the MOSFET tube Q2. The drain of the MOSFET tube Q2 is connected to the signal ground, and the gate is connected to the output terminal of the comparator U1. One end of the resistor R4 is connected to the power supply, and the other end is connected to the output terminal of the comparator U1. The power supply terminal of the comparator U1 is connected to the power supply, and the ground terminal is connected to the signal ground.

[0061] Furthermore, the temperature measuring circuit of the preferred embodiment of the present invention is as follows Figure 1 As shown, the comparator U1 and the resistors R1, R2, R3, R4, and MOSFET tube Q2 form a Schmitt trigger. When the comparator output is 0, the MOSFET tube Q2 is turned off. It is easy to know that the voltage at the inverting terminal of the comparator is:

[0062]

[0063] At this time, MOSFET tube Q1 is turned off, V cc Through the NTC resistor and resistor R ref Charge capacitor C1 until the voltage on capacitor C1 just exceeds V - , the comparator U1 output is high impedance, and resistor R4 pulls Vo up to V cc , MOSFET tube Q2 is turned on, and it is easy to know that the voltage at the inverting terminal of the comparator is:

[0064]

[0065] At the same time, MOSFET tube Q1 is turned on, and capacitor C1 is connected through resistor R ref And the switch tube Q1 discharges. When the voltage on capacitor C1 is just lower than V-, the comparator output flips to 0, and the cycle repeats to form oscillation.

[0066] like Figure 2 As shown, the preferred circuit working waveform of the present invention, Vp is the waveform of the non-inverting input terminal of the comparator U1, Vn is the waveform of the inverting input terminal of the comparator, which is also the waveform at both ends of the capacitor C1, and Vo is the waveform of the output terminal of the comparator U1.

[0067] When the circuit enters a stable state, the voltage waveform across capacitor C1 is a triangle wave between V- and V+. When the output of comparator U1 is 0, MOSFET Q1 is turned off, and V cc Through the NTC resistor and resistor R refCharge capacitor C1 from V- to V+. The charging time is:

[0068]

[0069] When the comparator output is in high impedance state, resistor R4 pulls Vo up to V cc MOSFET tube Q1 is turned on, capacitor C1 is connected through resistor R ref And the switch tube Q1 discharges, and the voltage of capacitor C1 is reduced from V+ to V-. The discharge time is:

[0070]

[0071] Calculate the ratio of charging time to discharging time:

[0072]

[0073] in:

[0074]

[0075] It is obvious that the ratio D of the charging time to the discharging time is only proportional to the NTC resistance and the resistance R ref , resistor R1, resistor R2, resistor R3, and the power supply voltage V cc And capacitor C1 have nothing to do with it, so there is no need for precise power supply voltage and capacitance, and precise resistance is easy to obtain. Therefore, it is only necessary to accurately calculate the ratio D of charging time and discharging time to obtain the accurate NTC resistance value, and thus the accurate temperature value.

[0076] To obtain an accurate ratio D of the charging time to the discharging time, it is only necessary to provide a counting clock with a sufficiently high frequency and a counter with a sufficient number of bits. Therefore, a sufficiently accurate temperature value can be obtained by the circuit of the present invention.

[0077] Economic benefits:

[0078] In summary, the circuit of the present invention has a high temperature measurement accuracy. After experimental testing, the circuit of the present invention has a temperature measurement accuracy of 1°C within the temperature measurement range of 0-150°C, which is sufficient for the temperature measurement of the IGBT module. At the same time, the circuit of the present invention has no requirements on the accuracy of the power supply and the capacitor, and does not require calibration or setting during the production process, so it is easy to achieve mass production. Finally, the circuit of the present invention has an extremely low material cost. According to statistics, excluding the NTC resistor, the material cost of the circuit of the present invention after mass production is only RMB 0.28 (based on the material price in 2016). If other inventions use high-precision power supplies and / or high-precision capacitors, the cost will be more advantageous.

[0079] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0080] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An IGBT module temperature measurement circuit, characterized in that: Including comparator U1, power port V cc , capacitor C1, first MOSFET tube Q1 and reference resistor; The power port V cc are electrically connected to the first node and the reverse input terminal of the comparator U1 respectively; the power port V cc It is also electrically connected to the power supply terminal of the comparator U1; In addition to the power supply port V cc In addition to being electrically connected, the first node is also electrically connected to the non-inverting input terminal of the comparator U1, the capacitor C1, and the source of the first MOSFET tube Q1; The drain of the first MOSFET tube Q1 is electrically connected to the signal ground; the gate of the first MOSFET tube Q1 is electrically connected to the output end of the comparator U1; One end of the capacitor C1 is electrically connected to the first node, and the other end is electrically connected to the signal ground; The ground terminal of the comparator U1 is electrically connected to the signal ground; The reference resistor is arranged at a setting position of the IGBT module temperature measurement circuit; The power port V cc A third node is also provided between the inverting input terminal of the comparator U1; The IGBT module temperature measurement circuit also includes a second MOSFET tube Q2; the source of the second MOSFET tube Q2 is electrically connected to the third node; the drain of the second MOSFET tube Q2 is electrically connected to the signal ground; the gate of the second MOSFET tube Q2 is electrically connected to the output end of the comparator U1; The IGBT module temperature measurement circuit also includes an IGBT module temperature measurement element; the IGBT module temperature measurement element is arranged at the power port V cc and the first node, including a thermistor; A second node is also provided between the first node and the same-direction input terminal of the comparator U1; the reference resistor includes a standard resistor R ref ; The standard resistance R ref is disposed between the first node and the second node; One end of the capacitor C1 passes through the second node, the standard resistor R ref One end is electrically connected to the first node, and the other end is electrically connected to the signal ground; The reference resistor further includes a third resistor R3; the third resistor R3 is arranged between the third node and the source of the second MOSFET tube Q2.

2. The IGBT module temperature measurement circuit according to claim 1, characterized in that: The reference resistor also includes a fourth resistor R4; the output end of the comparator U1 is also connected to the power port V through the fourth resistor R4. cc Electrical connection.

3. The IGBT module temperature measurement circuit according to claim 2, characterized in that: The reference resistor also includes a first resistor R1; the first resistor R1 is set at the power port V cc Between the third node.

4. The IGBT module temperature measurement circuit according to claim 3, characterized in that: The reference resistor further includes a second resistor R2; the third node is electrically connected to the first resistor R1 and the inverting input terminal of the comparator U1 respectively, and is also electrically connected to the signal ground through the second resistor R2.

5. A method for measuring temperature of an IGBT module, characterized in that: The IGBT module temperature measurement circuit according to any one of claims 1 to 4 comprises the following steps: Step 1: Measure the charging time T of capacitor C1 H ; Step 2: Measure the discharge time T of capacitor C1 L ; Step 3: Calculate T H / T L , and according to T H / T L , check the settings - Temperature table to obtain the corresponding temperature value.

6. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the IGBT module temperature measurement method according to claim 5 are implemented.

Images