A silicon carbide device based overcurrent and overvoltage protection circuit

Abstract

The application discloses a kind of overcurrent overvoltage protection circuit based on silicon carbide device, overcurrent protection circuit includes IPM module, three sampling resistors are respectively connected with the three-phase circuit of IGBT lower bridge in IPM module one to one for collecting three-phase current signal;IPM module is equipped with the overcurrent protection pin connected with the output end of operational amplifier for receiving amplified voltage signal, and compared with threshold voltage of overcurrent protection pin, when the voltage signal received by overcurrent protection pin is greater than threshold voltage, the built-in protection circuit in IPM module is turned off driving signal;The input end of voltage dividing network in overvoltage protection circuit is connected with the bus voltage input end P+ of IPM module, and the output end is respectively connected with clamping protection unit and filter unit;Clamping protection unit is connected with 3.3V power supply and ground for limiting the upper limit of sampling voltage;Filter unit includes first filter circuit and second filter circuit, and differential signal conditioning is realized for two signal output nodes.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to an overcurrent and overvoltage protection circuit based on silicon carbide devices. Background Technology

[0002] The description in this section provides only background information related to the disclosure of this invention and does not constitute prior art.

[0003] In electronic circuit systems, such as inverters and converters, overcurrent in power semiconductors is one of the important causes of system failure. Traditional silicon-based power devices are prone to overcurrent damage in high-temperature, high-frequency, and high-voltage applications due to the limitations of their material properties.

[0004] Silicon carbide (SiC) devices possess high voltage withstand capability, low on-resistance, high switching frequency, and excellent high-temperature resistance, making them promising for widespread applications in the electronics and power fields. However, SiC devices have relatively weak overcurrent withstand capability, thus requiring reliable overcurrent protection circuits to ensure their safe operation.

[0005] Intelligent power modules (IPMs) are widely used in frequency converters, motor drives, and other fields. Because IPMs integrate power devices and drive circuits, overcurrent is one of the main causes of IPM damage. Traditional overcurrent protection schemes typically use software detection, which has a slow response speed and is difficult to handle rapid overcurrent situations. Hardware overcurrent protection circuits can respond quickly and effectively protect IPMs from overcurrent damage.

[0006] Existing overvoltage protection schemes for IPM modules mostly rely on software detection, which suffers from large response delays and significant susceptibility to system interference. Some hardware protection schemes have defects such as low voltage division accuracy, inability to balance filtering effect and response speed, and unreasonable design of withstand voltage and power consumption, making it difficult to meet the protection requirements of IPM modules in extreme circuit environments.

[0007] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide an overcurrent and overvoltage protection circuit based on silicon carbide devices, which addresses the shortcomings of the prior art.

[0009] This application discloses an overcurrent and overvoltage protection circuit based on silicon carbide devices, including an overcurrent protection circuit and an overvoltage protection circuit; The overcurrent protection circuit includes an IPM module, a sampling resistor unit, and an operational amplifier unit. The sampling resistor unit includes three sampling resistors, each connected to one of the three phase circuits of the IGBT lower bridge in the IPM module, for acquiring three-phase current signals. The operational amplifier unit includes an operational amplifier and three signal transmission resistors. One end of each of the three signal transmission resistors is connected to one end of the three sampling resistors, and the other ends converge and are connected to the non-inverting input of the operational amplifier, transmitting the voltage signal on the sampling resistors to the operational amplifier for processing. The IPM module has an overcurrent protection pin connected to the output of the operational amplifier, for receiving the amplified voltage signal and comparing it with the threshold voltage of the overcurrent protection pin. When the voltage signal received by the overcurrent protection pin is greater than the threshold voltage, the built-in protection circuit of the IPM module shuts off the drive signal and stops outputting. The overvoltage protection circuit includes a voltage divider network, a clamping protection unit, a filtering unit, and a signal output node. The input terminal of the voltage divider network is connected to the bus voltage input terminal P+ of the IPM module, and the output terminal is connected to the clamping protection unit and the filtering unit respectively. The clamping protection unit is connected to a 3.3V power supply and ground to limit the upper limit of the sampling voltage. The filtering unit includes a first filtering circuit and a second filtering circuit, which correspond to the two signal output nodes respectively to achieve differentiated signal conditioning.

[0010] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the IPM module adopts Silan Microelectronics SQM50A65JA.

[0011] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the operational amplifier has a gain of 13.3.

[0012] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the threshold voltage of the overcurrent protection pin is 0.5V. When the output voltage of the operational amplifier is greater than 0.5V, the built-in circuit of the IPM module shuts off the drive signal and stops outputting.

[0013] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the maximum input voltage at the non-inverting input terminal of the operational amplifier is 0.035V.

[0014] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the maximum withstand voltage of a single sampling resistor is 0.11V, and the current flowing through a single sampling resistor is 55A. When the current in any phase of the three-phase circuit exceeds 55A, the IPM module triggers overcurrent protection.

[0015] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the voltage divider network consists of six series resistors, including one 200kΩ resistor, five and one 180kΩ resistors, and one 5.6kΩ resistor, with a voltage division ratio of 5.6kΩ / 1105.6kΩ. All resistors in the voltage divider network are 0805 packaged surface mount resistors, with a maximum withstand voltage of 300V per resistor and a maximum power consumption of no more than 0.07W per resistor.

[0016] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the clamping protection unit uses a bidirectional diode. When the sampling voltage output by the voltage divider network is greater than 3.3V, the diode conducts and clamps the voltage to 3.3V.

[0017] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the first filter circuit is a π-type filter circuit, consisting of a first resistor, a first capacitor, and a second capacitor. The corresponding signal output node is BUS_V_AD, and the time constant of this branch is 48μs. The output signal is used for bus voltage detection of the IPM module.

[0018] Furthermore, in the aforementioned overcurrent and overvoltage protection circuit based on silicon carbide devices, the second filter circuit is an RC filter circuit, consisting of a second resistor and a third capacitor. The corresponding signal output node is BUS_V_CMP, and the filtering time constant of this branch is 0.01μs. The output signal is used for overvoltage protection of the IPM module.

[0019] In summary, the structure adopted in the embodiments of the present invention has the following advantages: 1. The overcurrent and overvoltage protection circuit based on silicon carbide devices described in this invention features a fast overcurrent protection response. It directly detects the current signal using hardware circuitry, eliminating the need for software calculations. When the current exceeds the threshold, the IPM immediately shuts off the output, resulting in a short response time. It also boasts high detection accuracy, precisely amplifying the sampling voltage through an operational amplifier. Combined with the IPM module's built-in protection threshold, a precise 55A overcurrent protection threshold setting can be achieved, meeting the requirements of high-precision equipment. Furthermore, the circuit structure is stable, with a simple and reliable combination of sampling resistor and operational amplifier. The IPM incorporates multiple protection functions, further enhancing the circuit's safety and stability. 2. The overcurrent and overvoltage protection circuit based on silicon carbide devices described in this invention features overvoltage protection circuits where the clamping protection unit and the second filter circuit have response times calculated in microseconds, avoiding delays in software detection and promptly suppressing overvoltage surges. The voltage divider network has a precise voltage division ratio, and combined with the low ripple characteristics of the π-type filter, the detection error of the BUS_V_AD signal is small, ensuring the accuracy of bus voltage sampling. The resistor selection meets the withstand voltage and power consumption derating specifications, and the clamping diodes provide hardware-level overvoltage protection, reducing the risk of device damage. The two filter branches are adapted to detection and protection requirements respectively, improving circuit adaptability.

[0020] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a circuit diagram of an overcurrent protection circuit based on silicon carbide devices in an embodiment of the present invention; Figure 2 This is a hardware overcurrent circuit diagram of the IGBT in an embodiment of the present invention. Figure 3 This is a circuit diagram of an overvoltage protection circuit based on silicon carbide devices in an embodiment of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0024] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. Furthermore, the accompanying drawings of the present invention are for simple illustrative purposes only and are not depictions of actual dimensions; this is stated in advance. The following embodiments will further describe the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of protection of the present invention.

[0025] It should be understood that while terms such as "first," "second," and "third" may be used in this document to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another. Furthermore, the term "or" as used herein should, as appropriate, include any combination of one or more of the related listed items.

[0026] Reference Figure 1 As shown in the figure, this application discloses an overcurrent protection circuit based on silicon carbide devices, including: an IPM module, a sampling resistor unit, and an operational amplifier unit; The IPM module has 6 built-in IGBT transistors and 3 high-speed half-bridge high-voltage gate drive circuits. The sampling resistor unit includes three sampling resistors, which are respectively connected to the three-phase circuit of the IGBT lower bridge in the IPM module to collect three-phase current signals. The operational amplifier unit includes an operational amplifier and three signal transmission resistors. One end of each of the three signal transmission resistors is connected to one end of the three sampling resistors, and the other ends are connected together to the non-inverting input of the operational amplifier to transmit the voltage signal on the sampling resistor to the operational amplifier for processing. The IPM module is provided with an overcurrent protection pin connected to the output terminal of the operational amplifier. It is used to receive the amplified voltage signal and compare it with the threshold voltage of the overcurrent protection pin. When the voltage signal received by the overcurrent protection pin is greater than the threshold voltage, the built-in protection circuit of the IPM module shuts off the drive signal and stops the output.

[0027] Specifically, in this embodiment, the IPM module adopts Silan Microelectronics SQM50A65JA, which has 6 low-loss IGBTs and 3 high-speed half-bridge high-voltage gate drive circuits to realize the conversion and output of electrical energy. It also integrates undervoltage and short-circuit protection functions and temperature output function. After receiving the overcurrent detection signal, it can quickly turn off the drive signal and stop the output to protect the module and the back-end circuit. Each phase of the IPM is provided with an independent negative DC terminal. Three sampling resistors, RS1, RS2, and RS3, each with a resistance of 2mΩ and a power of 3W, are connected one-to-one with the three-phase circuit of the IGBT lower bridge of the IPM module to acquire the voltage signals corresponding to the three-phase currents in real time. The current-to-voltage conversion element is based on Ohm's law. When the three-phase currents flow through the three resistors respectively, a voltage signal proportional to the current is generated across the resistors, thus realizing the real-time acquisition of the three-phase currents.

[0028] Among them, reference Figure 2 In the IGBT hardware overcurrent scheme, current sampling is performed by sampling the U, V, and W phases of the IGBT lower bridge through three 2mΩ 3W resistors respectively. The current is then input to the operational amplifier via differential wiring, and the output is sent to the microcontroller for current sampling and overcurrent protection. A single trigger overcurrent protection value is applied, the MCU responds, the six-channel microcontroller outputs PWM to shut down, the IGBTs are turned off, and the compressor stops. The three-phase two-level half-bridge inverter uses the DC bus HV+ / HV- to synthesize three-phase AC through three half-bridges (U / V / W) to drive the motor, and a shunt resistor is connected in series on the lower bridge arm (lower side) for three-phase current sampling. Among them, ① DC bus and bus capacitor: HV+ / HV- serves as the high-voltage DC input (e.g., 200-450V). The capacitor on the left, the DC link capacitor (commonly thin-film / electrolytic in parallel), provides a switching transient current loop, reducing bus ripple and spikes. The larger the parasitic inductance of the bus loop, the more severe the switching spikes (V = L•di / dt); ② Three half-bridge power devices (Q1~Q6): In each phase, there is a pair of upper and lower transistors. U phase: Q1 (upper transistor) + Q4 (lower transistor); V phase: Q2 + Q5; W phase: Q3 + Q6; The diode symbol represents an anti-parallel diode (both IGBT and MOSFET are used for freewheeling). ③ Three-phase output to the motor: The midpoints of each half-bridge are U / V / W, which are directly connected to the three-phase windings of the motor. ④ Three-phase current sampling (RS1 / RS2 / RS3): The three low-side sampling resistors (2 mΩ / 3W) in the red box are located in the emitter circuit of each lower tube (Q4 / Q5 / Q6), and their lower ends are connected to HV- (bus negative terminal).

[0029] In this embodiment, the operational amplifier unit includes an operational amplifier U3A, signal transmission resistors R8, R9, and R10, and amplification resistors R17 and R18. The operational amplifier amplifies the voltage signal transmitted by the sampling resistors by a fixed factor, converting the small signal into an overcurrent detection signal that can be recognized by the IPM module. One end of the signal transmission resistors R8, R9, and R10 is connected to the three sampling resistors RS1, RS2, and RS3, respectively, and the other end is connected to the non-inverting input of the operational amplifier U3A. The amplification factor of the operational amplifier U3A is determined by the amplification resistor R17 and R18. R7 and R18 are determined. Signal transmission resistors R8, R9, and R10 transmit the voltage signal collected by the sampling resistor to the non-inverting input of the operational amplifier without distortion, avoiding signal attenuation or interference. Amplification resistors R17 and R18 are key components for determining the amplification factor of the operational amplifier. By precisely matching the resistance ratio of 20Ω and 1.5Ω, the amplification factor of the operational amplifier is stabilized at approximately 13.3 times, ensuring the accuracy of overcurrent detection. Specifically, in this embodiment, the amplification factor AV of the operational amplifier is AV = R17 / R18 ≈ 13.3.

[0030] Specifically, in this embodiment, the threshold voltage of the overcurrent protection pin is 0.5V. When the output voltage of the operational amplifier is greater than 0.5V, the built-in circuit of the IPM module shuts off the drive signal and stops outputting.

[0031] Specifically, in this embodiment, the maximum input voltage of the non-inverting input terminal of the operational amplifier is 0.035V. This value is calculated by the formula: maximum voltage of the non-inverting input terminal = maximum threshold voltage of the operational amplifier output / (amplification factor + 1) = 0.5V / (13.3 + 1) ≈ 0.035V.

[0032] Specifically, in this embodiment, the maximum withstand voltage of a single sampling resistor is 0.11V, and the current flowing through a single sampling resistor is 55A. When the current in any phase of the three-phase circuit exceeds 55A, the IPM module triggers overcurrent protection. When a phase short-circuit fault occurs in the three-phase circuit, the current of the faulty phase and the current of the non-faulty phase have a ratio of approximately 2:1, and the current of the non-faulty phase approaches 0. At this time, the maximum withstand voltage of a single sampling resistor is 0.035V*3≈0.11V, and the current flowing through a single sampling resistor is the voltage divided by the resistance value, i.e., 0.11V / 2mΩ=55A. When the circuit current exceeds 55A, the IPM module triggers the overcurrent protection mechanism.

[0033] Specifically, in this embodiment, the sampling resistor has a resistance of 2mΩ and a power of 3W.

[0034] In this embodiment, the normal operating signal flow of the overcurrent protection circuit is as follows: the three-phase current (U phase, V phase, W phase) output from the IGBT lower bridge of the IPM module flows through sampling resistors RS1, RS2, and RS3 respectively, generating a weak voltage signal (proportional to the current) across the resistors. This voltage signal is transmitted through R8, R9, and R10 to the non-inverting input pin 3 of the operational amplifier U3A. The operational amplifier amplifies the input signal by a factor of 13.3 through the feedback loop formed by R17 and R18. The amplified signal is output from the output pin 1 of the operational amplifier and transmitted to the overcurrent protection pin 8 of the IPM module. At this time, the signal voltage is lower than the 0.5V threshold, and the IPM module determines that there is no overcurrent fault in the circuit and maintains normal drive output.

[0035] In this embodiment, the overcurrent fault status signal flow and protection logic are as follows: When a phase short circuit (UV, UW, VW phase short circuit) fault occurs in the circuit, the fault phase current increases sharply, while the non-fault phase current approaches 0 (the ratio of fault phase current to non-fault phase current is approximately 2:1), causing a significant increase in the voltage across the corresponding sampling resistor (such as RS1). The increased voltage signal is transmitted to the non-inverting input of the operational amplifier U3A via the signal transmission resistor R8. After being amplified by 13.3 times, the output voltage of the operational amplifier exceeds the 0.5V threshold. After the overcurrent protection pin (pin 8) of the IPM module detects the voltage signal exceeding the threshold, the built-in protection circuit immediately starts, shutting off the IGBT drive signal and stopping the three-phase output to prevent the IPM module and the back-end circuit from burning out due to overcurrent. When the circuit fault is cleared, the voltage across the sampling resistor returns to normal, the output voltage of the operational amplifier drops below the 0.5V threshold, the IPM module releases the protection state, and resumes normal output.

[0036] The circuit in this embodiment is also equipped with a +15V power supply and a +5V reference voltage source. The +15V power supply powers the IPM module, and the +5V reference voltage source provides a stable reference voltage for the operational amplifier unit, ensuring the accuracy of current detection.

[0037] In this embodiment, diode D2 prevents the reverse voltage of the IPM module from flowing back into the operational amplifier, thus protecting the operational amplifier from damage.

[0038] Additionally, refer to Figure 3 This application discloses an overvoltage protection circuit based on silicon carbide devices, including: a voltage divider network, a clamping protection unit, a filtering unit, and a signal output node; The input terminal of the voltage divider network is connected to the bus voltage input terminal P+ of the IPM module, and the output terminal is connected to the clamping protection unit and the filtering unit respectively. The clamping protection unit is connected to a 3.3V power supply and ground to limit the upper limit of the sampling voltage; The filtering unit includes a first filtering circuit and a second filtering circuit, which correspond to the two signal output nodes respectively, to achieve differentiated signal conditioning.

[0039] Specifically, in this embodiment, the voltage divider network consists of six series resistors, including one 200kΩ resistor R505, five and one 180kΩ resistors (R506, R507, R508, R509, R512), and one 5.6kΩ resistor R515, with a total resistance of 1105.6kΩ and a voltage division ratio of 5.6kΩ / 1105.6kΩ. This can reduce the bus voltage P+ to the range that the ADC can measure, with a maximum detection voltage of 652V. It can be adapted to the upper limit of the 3.3V microcontroller I / O port input. The 5.6kΩ resistor R515 is the sampling resistor.

[0040] Specifically, in this embodiment, the resistors in the voltage divider network are all 0805 packaged surface mount resistors, with a maximum withstand voltage of 300V for a single resistor. The total withstand voltage of six resistors connected in series is not less than 1800V. When used according to the derating specification, the actual withstand voltage meets the maximum detection voltage requirement of 652V, and the maximum power consumption of a single resistor does not exceed 0.07W, which is lower than the rated power consumption of 0.25W. In the voltage divider network, each 0805 resistor has a withstand voltage of 300V, and the total withstand voltage of six resistors connected in series is 1800V. When used with a 50% derating, the actual withstand voltage is 900V, far exceeding the maximum detection voltage of 652V, eliminating the risk of withstand voltage breakdown. When the bus voltage is 652V, the current flowing through the voltage divider network is I = 652V / 1105.6kΩ ≈ 0.59mA, and the power consumption of a single 200kΩ resistor is P = I... 2 ×R = (0.59 × 10) -3 ) 2 ×200×10 3 With a power consumption of approximately 0.07W, lower than the rated power consumption of 0.25W, there will be no overheating damage.

[0041] Specifically, in this embodiment, the clamping protection unit uses a bidirectional diode. When the sampling voltage output by the voltage divider network is greater than 3.3V, the diode conducts and clamps the voltage to 3.3V. This prevents damage to the IPM module's microcontroller I / O port due to overvoltage, eliminates the need for software intervention, and provides a fast response. One end of diode D502 is connected to the sampling voltage node, and the other end is connected to the 3.3V power supply (A3V3) and ground (AGND) respectively, forming a bidirectional clamping loop.

[0042] The bus voltage P+ is input to a voltage divider network. After being divided by R505~R509, R512, and R515, the output is a sampled voltage. According to the voltage division ratio, the sampled voltage and the bus voltage satisfy the following relationship: Vsampled = P+ × 5.6 / 1105.6. To ensure that when P+ is 652V, Vsampled does not exceed 3.3V, and given that the maximum input voltage of the microcontroller's I / O port is 3.3V, the maximum input voltage P+ = 3.3 * 1105.6 / 5.6 ≈ 652V.

[0043] Specifically, in this embodiment, the first filtering circuit is a π-type filtering circuit, consisting of a 1 kΩ first resistor R513, a 1 nF first capacitor C507, and a 47 nF second capacitor C506. The corresponding signal output node is BUS_V_AD, and the time constant of this branch is 48 μs. The output signal is used for bus voltage detection in the IPM module. After passing through the first resistor R513, the sampling voltage node is connected to AGND via the first capacitor C507 and the second capacitor C506, forming a π-type filter. The output terminal BUS_V_AD is connected to the ADC module.

[0044] Specifically, in this embodiment, the second filtering circuit is an RC filtering circuit, consisting of a 100Ω second resistor R514 and a 100pF third capacitor C505. The corresponding signal output node is BUS_V_CMP. The filtering time constant of this branch is 0.01μs. The output signal is used for overvoltage protection of the IPM module, resulting in a faster response speed and timely feedback of voltage fluctuations, thus providing overvoltage protection. The sampling voltage node, after passing through the second resistor R514, is connected to AGND along with the third capacitor C505 to form an RC filter. The output terminal BUS_V_CMP is connected to the overvoltage protection trigger module.

[0045] In this embodiment, the IPM module also includes an inverter circuit, a PFC circuit, and a drive circuit. The signal output node BUS_V_AD node of the IPM module overvoltage protection circuit is connected to the ADC module, and the BUS_V_CMP node is connected to the overvoltage protection trigger module to realize the coordinated control of bus voltage detection and overvoltage protection.

[0046] The overvoltage protection circuit in this embodiment operates as follows: ① Voltage sampling stage: The bus voltage P+ is input to the voltage divider network. After being divided by R505~R509, R512, and R515, the sampled voltage is output. According to the voltage division ratio, the sampled voltage and the bus voltage satisfy the following relationship: Vsample = P+ × 5.6 / 1105.6, ensuring that when P+ is 652V, Vsample does not exceed 3.3V. ② Overvoltage clamping stage: When the bus voltage rises abnormally, causing Vsample to exceed 3.3V, D502 conducts, clamping Vsample to 3.3V to prevent excessively high voltage from being input to the microcontroller's I / O port, thus achieving hardware-level overvoltage protection. ③ Signal conditioning and protection triggering stage: The BUS_V_AD signal, after π-type filtering, has low ripple and high stability. It is transmitted to the ADC module for accurate detection of the bus voltage, providing a basis for judging the system's operating status. The BUS_V_CMP signal, after RC filtering, has a fast response speed and can track bus voltage fluctuations in real time. When overvoltage is detected, it quickly triggers the overvoltage protection module, shutting down relevant power devices to prevent damage to the IPM module. The RC filtering time constant of the BUS_V_CMP branch is 0.01μS, and the overvoltage detection and protection trigger time is less than 15μS, effectively preventing the MOSFET from being damaged by overvoltage.

[0047] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention specification and drawings are included in the scope of the patent application of the present invention.

[0048] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0049] Although this application has been described by way of examples, those skilled in the art will know that this application has many modifications and variations without departing from the spirit of this application, and it is intended that the appended embodiments include these modifications and variations without departing from this application.

Claims

1. An overcurrent and overvoltage protection circuit based on silicon carbide devices, characterized in that, Includes overcurrent protection circuit and overvoltage protection circuit; The overcurrent protection circuit includes an IPM module, a sampling resistor unit, and an operational amplifier unit. The sampling resistor unit includes three sampling resistors, each connected to one of the three phase circuits of the IGBT lower bridge in the IPM module, for acquiring three-phase current signals. The operational amplifier unit includes an operational amplifier and three signal transmission resistors. One end of each of the three signal transmission resistors is connected to one end of the three sampling resistors, and the other ends converge and are connected to the non-inverting input of the operational amplifier, transmitting the voltage signal on the sampling resistors to the operational amplifier for processing. The IPM module has an overcurrent protection pin connected to the output of the operational amplifier, for receiving the amplified voltage signal and comparing it with the threshold voltage of the overcurrent protection pin. When the voltage signal received by the overcurrent protection pin is greater than the threshold voltage, the built-in protection circuit of the IPM module shuts off the drive signal and stops outputting. The overvoltage protection circuit includes a voltage divider network, a clamping protection unit, a filtering unit, and a signal output node; the input terminal of the voltage divider network is connected to the bus voltage input terminal P+ of the IPM module, and the output terminal is connected to the clamping protection unit and the filtering unit respectively; the clamping protection unit is connected to the 3.3V power supply and ground to limit the upper limit of the sampling voltage. The filtering unit includes a first filtering circuit for IPM module bus voltage detection and a second filtering circuit for IPM module overvoltage protection, which correspond to the two signal output nodes respectively to achieve differentiated signal conditioning.

2. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The IPM module is Silan Microelectronics SQM50A65JA.

3. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The operational amplifier has a gain of 13.

3.

4. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The threshold voltage of the overcurrent protection pin is 0.5V. When the output voltage of the operational amplifier is greater than 0.5V, the built-in circuit of the IPM module shuts off the drive signal and stops outputting.

5. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The maximum input voltage at the non-inverting input of the operational amplifier is 0.035V.

6. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The maximum withstand voltage of a single sampling resistor is 0.11V, and the current flowing through a single sampling resistor is 55A. When the current in any phase of the three-phase circuit exceeds 55A, the IPM module triggers overcurrent protection.

7. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The voltage divider network consists of six series resistors, including one 200kΩ resistor, 5 and 180kΩ resistors, and one 5.6kΩ resistor, with a voltage division ratio of 5.6kΩ / 1105.6kΩ. All resistors in the voltage divider network are 0805 packaged surface mount resistors, with a maximum withstand voltage of 300V per resistor and a maximum power consumption of no more than 0.07W per resistor.

8. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The clamping protection unit uses a bidirectional diode. When the sampling voltage output by the voltage divider network is greater than 3.3V, the diode turns on and clamps the voltage to 3.3V.

9. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The first filtering circuit is a π-type filtering circuit, consisting of a first resistor, a first capacitor, and a second capacitor. The corresponding signal output node is BUS_V_AD, and the time constant of this branch is 48μs. The output signal is used for bus voltage detection of the IPM module.

10. The overcurrent and overvoltage protection circuit based on silicon carbide devices according to claim 1, characterized in that, The second filtering circuit is an RC filtering circuit, consisting of a second resistor and a third capacitor. The corresponding signal output node is BUS_V_CMP. The filtering time constant of this branch is 0.01μs, and the output signal is used for overvoltage protection of the IPM module.

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