Automatic insulation test circuit for power module

Abstract

The invention discloses an automatic insulation test circuit for a power module, which comprises an HV power supply end and an LV power supply end, and is characterized in that a voltage withstanding instrument provides test voltage for the two power supply ends; the plurality of pins comprise an LVPIN1 pin, an LVPIN2 pin, an NTCPIN1 pin, an NTCPIN2 pin and a DBC pin, a CH contact and a KEL contact are led out from each pin, the CH contact is used for applying voltage, and the KEL contact is used for testing a Kelvin loop; according to the invention, all pins of the power module are all provided with Kelvin test loops, and the upper computer is used for controlling the closing and opening of the relay, so that the independent measurement between the CH contact and the KEL contact of each pin is realized. According to the design, the problems of missing detection and poor contact can be effectively eliminated, the hidden danger of discharging is avoided, the safety and stability of the testing process are improved, and therefore the integrity and accuracy of power module pin path detection are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power module testing, in particular to a power module automatic insulation test circuit. BACKGROUND

[0002] Power semiconductor modules (such as IGBT / MOSFET modules, vehicle OBC / inverters, industrial drives, etc.) often use DBC substrates as heat dissipation and insulation integrated carriers. The typical structure is a Cu / ceramic / Cu sandwich, and the ceramic material includes Al2O3, AlN, Si3N4, etc., which not only provides an electrically insulated path between the chip and the heat sink, but also bears the heat conduction and mechanical support. With the increase of working voltage, dv / dt and power density, the insulation reliability of DBC under long-term thermal cycling, humid bias and pollution conditions has become one of the system life bottlenecks.

[0003] In the above module, NTC thermistors are often used as key sensors for junction temperature / case temperature monitoring and protection triggering, usually attached to the surface of the DBC or adjacent to the power copper layer area. In addition to meeting the R-T characteristic stability, NTC also needs to ensure the insulation strength and partial discharge resistance between it and the high-voltage conductor, and adapt to the change of electric field distribution after pouring / coating. Mainly adopt: DC or AC voltage resistance and leakage current test between DBC copper layers, copper layer and base / heat sink, and NTC signal end to high-voltage copper.

[0004] The current problems encountered by multi-pin module products are as follows:

[0005] 1. DBC low-voltage pin measurement is mostly parallel measurement, and no Kelvin open circuit detection is performed for each pin, which may cause missed detection and pin discharge problems.

[0006] 2. DBC insulation test and NTC test are independent processes, resulting in reduced detection efficiency.

[0007] 3. No NTC resistance value measurement function or complex circuit structure.

[0008] Therefore, a power module automatic insulation test circuit is proposed. SUMMARY

[0009] The purpose of the present application is to provide a power module automatic insulation test circuit to solve the problems raised in the background art.

[0010] To achieve the above purpose, the present application provides the following technical scheme: a power module automatic insulation test circuit, comprising:

[0011] HV power supply end and LV power supply end, and the voltage resistance instrument provides test voltage for the two power supply ends;

[0012] Multiple pins, including LV_PIN1, LV_PIN2, NTC_PIN1, NTC_PIN2 and DBC, each with a CH contact and a KEL contact. The CH contact is used to apply voltage and the KEL contact is used for Kelvin loop testing.

[0013] Multiple relays, by controlling the closing and opening of multiple relays, can be switched to form Kelvin test circuit, insulation test circuit, isolation test circuit and NTC resistance measurement circuit, so as to realize independent testing of multi-pin Kelvin, insulation test, isolation test, NTC resistance measurement function and combined testing of the above functions;

[0014] The resistance measurement module includes A1, A2, A3 and A4, which are connected to each test circuit respectively, and are used to measure the circuit resistance value or assist in the detection of test signals.

[0015] Preferably, one end of relay K1 is connected to the HV power supply terminal, the other end of relay K1 is connected to one end of relay K1-1, relay K1-2 and relay K1-3 respectively, and the other end of relay K1-2 is connected to one end of resistance measurement module A1.

[0016] Preferably, the other end of the resistance measurement module A1 is connected to one end of relays K1-7 and K1-8 respectively. The other end of relay K1-7 is connected to the NTC_KEL1 contact of the NTC_PIN1 pin. The NTC_CH1 contact of the NTC_PIN1 pin is connected to the other end of relay K1-1. The other end of relay K1-8 is connected to the NTC_KEL2 contact of the NTC_PIN2 pin. The NTC_CH2 contact of the NTC_PIN2 pin is connected to the other end of relay K1-3.

[0017] Preferably, one end of relay K2 is connected to the LV power supply terminal, the other end of relay K2 is connected to one end of relay K2-1, relay K2-2 and relay K2-3 respectively, and the other end of relay K2-2 is connected to one end of resistance measurement module A2.

[0018] Preferably, the other end of the resistance measurement module A2 is connected to one end of relays K2-7 and K2-8 respectively. The other end of relay K2-7 is connected to the NTC_KEL1 contact of the NTC_PIN1 pin. The NTC_CH1 contact of the NTC_PIN1 pin is connected to the other end of relay K2-1. The other end of relay K2-8 is connected to the NTC_KEL2 contact of the NTC_PIN2 pin. The NTC_CH2 contact of the NTC_PIN2 pin is connected to the other end of relay K2-3.

[0019] Preferably, one end of relays K1-4, K1-5, and K1-6 are connected to the HV power supply terminal respectively. The other end of relay K1-5 is connected to one end of resistance measurement module A3. The other end of resistance measurement module A3 is connected to one end of relays K1-9 and K1-10 respectively. The other end of relay K1-9 is connected to the HV_KEL3 contact of the HV_PIN pin. The HV_CH3 contact of the HV_PIN pin is connected to the other end of relay K1-4. The other end of relay K1-10 is connected to the HV_KEL4 contact of the DBC pin. The HV_CH4 contact of the DBC pin is connected to the other end of relay K1-6.

[0020] Preferably, one end of relays K2-4, K2-5, and K2-6 are respectively connected to the LV power supply terminal. The other end of relay K2-5 is connected to one end of the resistance measurement module A4. The other end of the resistance measurement module A4 is respectively connected to one end of relays K2-9 and K2-10. The other end of relay K2-9 is connected to the LV_KEL3 contact of the LV_PIN1 pin. The LV_CH3 contact of the LV_PIN1 pin is connected to the other end of relay K2-4. The other end of relay K2-10 is connected to the LV_KEL4 contact of the LV_PIN2 pin. The LV_CH4 contact of the LV_PIN2 pin is connected to the other end of relay K2-6.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. Achieve full pin Kelvin testing with high detection integrity: This invention sets up Kelvin test circuits on all pins of the power module and controls the closing and opening of relays through the host computer to realize independent measurement between the CH contacts and KEL contacts of each pin. This design can effectively eliminate the problems of missed detection and poor contact, avoid the hidden danger of discharge, and improve the safety and stability of the testing process, thereby ensuring the integrity and accuracy of the pin path detection of the power module.

[0023] 2. Multifunctional test modes can be freely combined, resulting in high testing efficiency: Under the same fixture conditions, this invention can realize arbitrary combination tests of multiple functions such as Kelvin test, insulation test, isolation test and NTC resistance measurement through upper computer program control. The test functions can be flexibly configured as needed. This solution can complete multiple tests under one clamping condition without changing the fixture or rewiring, which greatly improves the testing efficiency and automation level and reduces production costs.

[0024] 3. Simple circuit structure and high system integration: This invention achieves the NTC resistance measurement function and other test functions sharing the same circuit structure by rationally designing the relay switching network. The test mode can be switched by controlling the closing state of different relays through the host computer. This design avoids repeated wiring and the addition of extra hardware modules, simplifies the circuit topology, reduces system complexity, and improves the stability and reliability of the device.

[0025] 4. High degree of automation and wide applicability: This invention achieves automatic switching and execution of multiple testing functions through software control, and the testing process can be completed without manual intervention. The device can adapt to power modules of different models and pin counts, realize multi-channel parallel testing, and has good scalability and versatility. This solution is particularly suitable for batch testing scenarios in automated power module production lines, and can significantly improve product testing efficiency and consistency. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the principle of the present invention;

[0027] Figure 2 This is the circuit diagram of the present invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0029] Please see Figures 1-2 The present invention provides a technical solution: an automated insulation test circuit for power modules, which can realize independent testing of multi-pin Kelvin, insulation testing, isolation testing, NTC resistance measurement, and combined testing of the above four functions.

[0030] The following explanation uses a four-pin and one-DBC pin as an example, where the four pins include two NTC pins and two general-purpose pins.

[0031] like Figure 1 As shown, during the test, each pin (including the DBC pin) has two contacts: the CH contact and the KEL contact. The CH contact is used to apply voltage, and the KEL contact is used for Kelvin circuit testing.

[0032] Figure 2 This shows the detailed circuit connections. The withstand voltage tester provides test voltages to the HV and LV power supply terminals. HV reaches the HV branch point through K1, and LV reaches the LV branch point through K2. A1, A2, A3, and A4 in the device are resistance measurement modules.

[0033] The following five pin Kelvin test circuits can be implemented by switching different relays:

[0034] 1. The NTC_PIN1_Kelvin test circuit is divided into a high-voltage channel and a low-voltage channel.

[0035] High-voltage channel section: By closing relays K1-1, K1-2, and K1-7, a test circuit is formed consisting of HV_CH1 channel, NTC_PIN1, HV_KEL1 channel, K1-7, A1, K1-2, and K1-1.

[0036] Low-voltage channel section: By closing relays K2-1, K2-2, and K2-7, a test circuit is formed consisting of the LV_CH1 channel, NTC_PIN1, LV_KEL1 channel, K2-7, A2, K2-2, and K2-1.

[0037] 2. The NTC_PIN2_Kelvin test circuit is divided into a high-voltage channel and a low-voltage channel.

[0038] High-voltage channel section: By closing relays K1-2, K1-3, and K1-8, a test circuit is formed consisting of HV_CH2 channel, NTC_PIN2, HV_KEL2 channel, K1-8, A1, K1-3, and K1-2.

[0039] Low-voltage channel section: By closing relays K2-2, K2-3, and K2-8, a test circuit is formed consisting of the LV_CH2 channel, NTC_PIN2, LV_KEL2 channel, K2-8, A2, K2-3, and K2-2.

[0040] 3. The DBC_Kelvin test circuit is formed by closing relays K1-5, K1-6, and K1-10, which consists of the HV_CH4 channel, DBC, HV_KEL4 channel, A3, K1-6, and K1-5.

[0041] 4. The LV_PIN1_Kelvin test circuit is formed by closing relays K2-4, K2-9, and K2-5, which consist of the LV_CH3 channel, K2-4, K2-5, A4, the LV_KEL3 channel, K2-9, and LV_PIN1.

[0042] 5. The LV_PIN2_Kelvin test circuit is formed by closing relays K2-5, K2-6, and K2-10, which consist of the LV_CH4 channel, K2-6, K2-5, A4, the LV_KEL4 channel, K2-10, and LV_PIN2.

[0043] Kelvin Test: The Kelvin test measures the contact resistance between the CH and KEL contacts of each pin to verify the integrity and reliability of the pin path. During the test, the resistance between the CH and KEL contacts of each pin must be accurately measured. If the measured resistance is below a set threshold, the channel is considered to have passed the test; if the resistance exceeds the threshold, the test is considered to have failed. To perform the Kelvin test, simply disconnect relays K1 and K2 and close the Kelvin test circuit corresponding to each pin to complete the automated Kelvin detection for all channels.

[0044] Insulation Test: The insulation test is mainly used to detect the insulation performance between the pins of the power module and between the pins and the DBC. In this mode, a high-voltage signal is applied to the CH contact of the DBC pin, while a low-voltage signal is applied to the CH contacts of the other four pins to measure the leakage current or insulation resistance between different nodes, thereby determining whether the insulation condition meets the standard requirements. During the test, relays K1, K1-6, K2, K2-1, K2-3, K2-4, and K2-6 should be closed. This configuration enables the automatic establishment of electrical isolation and insulation test paths between the high and low voltage terminals.

[0045] Isolation Test: The isolation test verifies the electrical isolation performance between NTC pins and general-purpose pins and DBC pins. In this mode, a high-voltage signal is applied to the CH contacts of the two NTC pins, while a low-voltage signal is applied to the CH contacts of the two general-purpose pins; the DBC pins remain un-voltaged. During the test, relays K1, K1-1, K1-3, K2, K2-4, and K2-6 should be closed. This path configuration allows for separate testing of the electrical isolation performance between the NTC signal terminals and power terminals.

[0046] NTC Resistance Measurement: The NTC resistance measurement mode is used to detect the resistance characteristics of thermistors (NTCs) in power modules to evaluate the effectiveness of the module's temperature monitoring function. During testing, relays K1-2, K1-3, and K1-7 must be closed to form a complete test loop consisting of K1-2, A1, K1-7, HV_KEL1 channel, NTC_PIN1, the NTC resistor, NTC_PIN2, HV_CH2, and K1-3. This loop allows for accurate measurement of the resistance between the two NTC pins.

[0047] Working Principle: This invention's multi-pin automated insulation measurement circuit for power modules, featuring Kelvin and thermistor value measurement, automatically switches and executes multiple functions such as Kelvin testing, NTC resistance measurement, insulation testing, and isolation testing by controlling the closing and opening states of each relay via a host computer. Its specific usage process is as follows:

[0048] 1. Kelvin Test: During Kelvin testing, first disconnect relays K1 and K2 to disconnect the high-voltage and low-voltage main channels. Then, following the aforementioned Kelvin test circuit for each pin, close the corresponding relays, ensuring that the CH contact and KEL contact of each pin (including the DBC pin) form an independent test path. Measure the contact resistance of each channel using resistance measurement modules A1 to A4 to determine the integrity and contact reliability of the pin path.

[0049] 2. NTC Resistance Measurement: When measuring the NTC resistance, relays K1-2, K1-3, and K1-7 must be closed to form an NTC test circuit. This circuit consists of K1-2, A1, K1-7, HV_KEL1 channel, NTC_PIN1, the internal NTC resistor of the module, NTC_PIN2, HV_CH2, and K1-3 connected in sequence. This closed circuit allows for accurate measurement of the thermistor value between the two NTC pins.

[0050] 3. Insulation Test: In insulation test mode, an insulation test path is formed by closing relays K1, K1-6, K2, K2-1, K2-3, K2-4, and K2-6. At this time, the HV terminal of the withstand voltage tester outputs high voltage to the CH contact of the DBC pin, and the LV terminal is connected to the CH contacts of the remaining pins. By detecting the leakage current or insulation resistance value, it can be determined whether the insulation performance between the power module pins and between the pins and the DBC meets the requirements.

[0051] 4. Isolation Test: In isolation test mode, an isolation test path is constructed by closing relays K1, K1-1, K1-3, K2, K2-4, and K2-6. During the test, a high-voltage signal is applied to the CH contacts of the two NTC pins, and a low-voltage signal is applied to the CH contacts of the two ordinary pins. The DBC pin remains un-voltageed. By monitoring the electrical isolation performance, the electrical isolation status between the NTC pins and the ordinary power pins and DBC pins can be verified, ensuring the independence and safety of the signal and power terminals within the module.

[0052] The following requirements apply when testing automated batch production lines:

[0053] 1. Under the premise of the same fixture, different test modes require the CH and KEL contacts of the NTC pin to switch between high-voltage and low-voltage channels.

[0054] 2. When performing Kelvin testing, both high-voltage and low-voltage Kelvin tests need to be performed on the NTC pins simultaneously.

[0055] 3. Under the premise of the same fixture, each test item can be flexibly configured, and each test function can be tested independently or in combination.

[0056] 4. All pins need to be tested by Kelvin to ensure high test integrity.

[0057] Current insulation testing systems are generally used in manual operation mode, with a low degree of automation, and only meet some of the above functions. To meet all the above functions, multiple devices with different functions need to be distributed to complete the work, resulting in low testing efficiency and making them unsuitable for automated batch production line testing.

[0058] Regarding problem 1, this solution uses a host computer to control the opening and closing of the relay to switch the NTC pin CH contact between the high-voltage and low-voltage channels, such as... Figure 2 As shown, closing K1, K1-1, and K1-3, and opening K2-1 and K2-3, switches the NTC pin CH contact to the high-voltage channel; the low-voltage channel works similarly. Opening K1 and closing K1-1, K1-2, K1-3, K1-7, and K1-8 switches the NTC pin KEL contact to the high-voltage channel; the low-voltage channel works similarly. This solution allows for automatic channel switching of the NTC pin without manual intervention, significantly improving testing efficiency and safety.

[0059] Regarding question 2, this solution adopts Figure 2 The circuit connection shown can be completed by disconnecting K1 and closing K1-1, K1-2, K1-3, K1-7, K1-8, K2-1, K2-2, K2-3, K2-7, and K2-8. To avoid signal interference between the high and low voltage channels, A1 and A2 are isolated in the circuit design to ensure that the measurements of the high voltage channel and the low voltage channel do not affect each other, thereby ensuring the correctness, validity, and safety of the test results.

[0060] To address issue 3, and to achieve NTC resistance measurement without increasing hardware complexity, this solution utilizes the same circuit connections, allowing NTC resistance measurement to be completed simply by controlling the closing and opening of relays via a host computer. This approach avoids rewiring or structural adjustments, maintaining the simplicity of the circuit topology while improving system maintainability and scalability. By controlling the relay state at the software level, a unified approach of electrical measurement functionality and structural simplification is achieved.

[0061] Regarding question 4, under the same fixture conditions, this solution achieves independent and combined testing of multiple functions, including Kelvin testing, insulation testing, isolation testing, and NTC resistance measurement, through centralized control of relays by a host computer. Each test function is automatically switched by controlling the relays to close or open. Due to the aforementioned solution to the switching issue of the CH and KEL contact channels of the NTC pins, the NTC pins can meet different testing requirements under the same fixture. Ordinary pins and DBC pins can also achieve Kelvin and insulation testing through relay control, but do not participate in the circuit in NTC resistance measurement. Isolation and insulation testing of ordinary pins can share the same electrical configuration without switching; DBC pins do not participate in isolation testing. Therefore, intelligent control of relays by a host computer enables the independent and flexible combination of various test functions. Multiple testing modes can be completed on the same fixture platform, significantly improving the automation and versatility of the testing system while reducing hardware costs and operational complexity.

[0062] This invention enables automatic switching of the CH and KEL contacts of the NTC pin between high-voltage and low-voltage channels. By controlling the closing and opening states of the relays via a host computer, the channel assignment can be flexibly adjusted in different test modes without the need for manual wiring or operation, significantly improving the automation and safety of the test system.

[0063] This invention innovatively achieves simultaneous high-voltage and low-voltage Kelvin testing of NTC pins during the Kelvin test process. This design, through independent high- and low-voltage measurement branches and an isolated resistance detection module, ensures that the measurement signals do not interfere with each other, thereby guaranteeing the accuracy and repeatability of the test results. It solves the technical problem that traditional single-channel Kelvin testing cannot fully cover NTC pins.

[0064] This invention achieves NTC resistance measurement while utilizing a relay network and measurement module shared with other test functions, eliminating the need for additional hardware circuitry. Through rational path configuration and software control logic, it simplifies the circuit topology and integrates measurement functions, significantly reducing system complexity and manufacturing costs while ensuring test accuracy.

[0065] This invention enables independent and arbitrary combination testing of multiple functions, including Kelvin testing, insulation testing, isolation testing, and NTC resistance measurement, all within a single fixture platform. Through intelligent control of the relays by a host computer, test modes can be flexibly configured according to requirements, allowing for multi-functional switching without altering the hardware connections. This innovative design significantly improves the versatility and adaptability of the testing system, meeting the comprehensive automated testing needs of various power modules.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An automated insulation testing circuit for power modules, characterized in that, include: The withstand voltage tester provides test voltage to both the HV and LV power terminals. Multiple pins, including LV_PIN1, LV_PIN2, NTC_PIN1, NTC_PIN2 and DBC, each with a CH contact and a KEL contact. The CH contact is used to apply voltage and the KEL contact is used for Kelvin loop testing. Multiple relays, by controlling the closing and opening of multiple relays, can be switched to form Kelvin test circuit, insulation test circuit, isolation test circuit and NTC resistance measurement circuit, so as to realize independent testing of multi-pin Kelvin, insulation test, isolation test, NTC resistance measurement function and combined testing of the above functions; The resistance measurement module includes A1, A2, A3 and A4, which are connected to each test circuit respectively, and are used to measure the circuit resistance value or assist in the detection of test signals.

2. The automated insulation test circuit for a power module according to claim 1, characterized in that: One end of relay K1 is connected to the HV power supply terminal. The other end of relay K1 is connected to one end of relays K1-1, K1-2 and K1-3 respectively. The other end of relay K1-2 is connected to one end of resistance measurement module A1.

3. The automated insulation test circuit for a power module according to claim 2, characterized in that: The other end of the resistance measurement module A1 is connected to one end of relays K1-7 and K1-8 respectively. The other end of relay K1-7 is connected to the NTC_KEL1 contact of the NTC_PIN1 pin. The NTC_CH1 contact of the NTC_PIN1 pin is connected to the other end of relay K1-1. The other end of relay K1-8 is connected to the NTC_KEL2 contact of the NTC_PIN2 pin. The NTC_CH2 contact of the NTC_PIN2 pin is connected to the other end of relay K1-3.

4. The automated insulation test circuit for a power module according to claim 1, characterized in that: One end of relay K2 is connected to the LV power supply terminal. The other end of relay K2 is connected to one end of relays K2-1, K2-2 and K2-3 respectively. The other end of relay K2-2 is connected to one end of resistance measurement module A2.

5. The automated insulation test circuit for a power module according to claim 4, characterized in that: The other end of the resistance measurement module A2 is connected to one end of relays K2-7 and K2-8 respectively. The other end of relay K2-7 is connected to the NTC_KEL1 contact of the NTC_PIN1 pin. The NTC_CH1 contact of the NTC_PIN1 pin is connected to the other end of relay K2-1. The other end of relay K2-8 is connected to the NTC_KEL2 contact of the NTC_PIN2 pin. The NTC_CH2 contact of the NTC_PIN2 pin is connected to the other end of relay K2-3.

6. The automated insulation test circuit for a power module according to claim 1, characterized in that: The HV power supply terminal is also connected to one end of relays K1-4, K1-5, and K1-6 respectively. The other end of relay K1-5 is connected to one end of resistance measurement module A3. The other end of resistance measurement module A3 is connected to one end of relays K1-9 and K1-10 respectively. The other end of relay K1-9 is connected to the HV_KEL3 contact of the HV_PIN pin. The HV_CH3 contact of the HV_PIN pin is connected to the other end of relay K1-4. The other end of relay K1-10 is connected to the HV_KEL4 contact of the DBC pin. The HV_CH4 contact of the DBC pin is connected to the other end of relay K1-6.

7. The automated insulation test circuit for a power module according to claim 1, characterized in that: The LV power supply terminal is also connected to one end of relays K2-4, K2-5, and K2-6 respectively. The other end of relay K2-5 is connected to one end of resistance measurement module A4. The other end of resistance measurement module A4 is connected to one end of relays K2-9 and K2-10 respectively. The other end of relay K2-9 is connected to the LV_KEL3 contact of the LV_PIN1 pin. The LV_CH3 contact of the LV_PIN1 pin is connected to the other end of relay K2-4. The other end of relay K2-10 is connected to the LV_KEL4 contact of the LV_PIN2 pin. The LV_CH4 contact of the LV_PIN2 pin is connected to the other end of relay K2-6.

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