An overcurrent protection circuit of an intelligent power module and related equipment

Abstract

The application discloses an overcurrent protection circuit of an intelligent power module and related equipment. The overcurrent protection circuit comprises a current sampling circuit, an operational amplifier circuit, a triode and a resistance voltage dividing circuit. The sampling end of the current sampling circuit is connected with the three-phase current output end of the intelligent power module, and the output end thereof is connected with the input end of the operational amplifier circuit; the output end of the operational amplifier circuit is connected with the control end of the triode; the input end of the resistance voltage dividing circuit is connected with the output end of the triode, the output end thereof is connected with the CIN pin of the IPM, and the temperature coefficient of the triode and the temperature coefficient of the resistance voltage dividing circuit form a mutual compensation relationship. By making the temperature coefficients of the triode and the resistance voltage dividing circuit mutually compensate, the voltage input to the CIN pin of the IPM is prevented from deviating from the preset overcurrent protection threshold due to temperature change, and the protection mis-triggering or protection lagging problem caused by temperature drift is reduced.

Description

Technical Field

[0001] This application relates to the field of overcurrent protection technology, and in particular to an overcurrent protection circuit and related equipment for an intelligent power module. Background Technology

[0002] With the widespread adoption of variable frequency drive technology, the Intelligent Power Module (IPM) is a core component of air conditioning and industrial compressor drive systems, responsible for compressor speed regulation and control. As a crucial component of the IPM, the overcurrent protection circuit must monitor the IPM output current in real time and trigger the IPM protection mechanism when the current exceeds the limit, preventing hardware damage and ensuring stable system operation.

[0003] Existing IPM overcurrent protection circuits typically include current sampling, signal processing, and protection triggering modules. The current sampling module acquires the three-phase current of the IPM through a shunt resistor or Hall sensor and converts it into a voltage signal; the signal processing module, with an operational amplifier as its core, compares the sampled voltage with a reference voltage and outputs a level signal to control the switching elements; the protection triggering module uses a resistor divider network to convert the output signal of the switching elements into a voltage adapted to the IPM CIN pin, triggering IPM protection.

[0004] In practical applications, the resistance of the resistor divider network is not well-matched to the temperature characteristics of the switching elements. Temperature fluctuations can cause the input voltage at the CIN pin to deviate from the protection threshold, leading to false triggering or protection hysteresis. Ground loop current in high-power systems causes ground potential drift, which, combined with the voltage drop across the conductors, further amplifies the threshold deviation, making it difficult for existing circuits to meet the high requirements of compressor drive systems in terms of accuracy and reliability. Summary of the Invention

[0005] To address the aforementioned issues, this application provides an overcurrent protection circuit and related equipment for an intelligent power module.

[0006] The embodiments of this application disclose the following technical solutions: In a first aspect, embodiments of this application provide an overcurrent protection circuit for an intelligent power module, the overcurrent protection circuit comprising a current sampling circuit, an operational amplifier circuit, a transistor, and a resistor voltage divider circuit: The sampling terminal of the current sampling circuit is connected to the three-phase current output terminal of the intelligent power module IPM, and the output terminal of the current sampling circuit is connected to the input terminal of the operational amplifier circuit. The output terminal of the operational amplifier circuit is connected to the control terminal of the transistor. The input terminal of the resistor voltage divider circuit is connected to the output terminal of the transistor, and the output terminal of the resistor voltage divider circuit is connected to the CIN pin of the IPM; wherein, the temperature coefficient of the transistor and the temperature coefficient of the resistor voltage divider circuit compensate for each other.

[0007] In one possible implementation, the transistor is a PNP transistor; The base of the PNP transistor is connected to the output terminal of the operational amplifier circuit through the first resistor R1; The collector of the PNP transistor is connected to the input terminal of the resistor divider circuit and grounded through the second resistor R2; the emitter of the PNP transistor is connected to the first power supply voltage; the emitter and base of the PNP transistor are connected in parallel with the third resistor R3; and the emitter and collector of the PNP transistor are connected in parallel with the first capacitor C1.

[0008] In one possible implementation, the resistor voltage divider circuit is a symmetrical resistor voltage divider network; the symmetrical resistor voltage divider network includes a first voltage divider resistor and a second voltage divider resistor, the resistance values ​​of the first voltage divider resistor and the second voltage divider resistor are equal; the symmetrical resistor voltage divider network is used to suppress high-frequency switching noise; The first end of the first voltage divider resistor is connected to the output terminal of the transistor; the second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor, and then connected to the CIN pin of the IPM. The second terminal of the second voltage divider resistor is grounded, and the second terminal of the first voltage divider resistor and the second terminal of the second voltage divider resistor are connected in parallel with a second capacitor.

[0009] In one possible implementation, the operational amplifier circuit includes an operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, and a fourth capacitor.

[0010] The fourth resistor is connected in parallel to the output terminal and the non-inverting input terminal of the operational amplifier; The output terminal of the operational amplifier U1B is connected to the control terminal of the transistor; the non-inverting input terminal of the operational amplifier is connected to the common terminal of the fifth resistor and the sixth resistor; the inverting input terminal of the operational amplifier is connected to the first terminal of the third capacitor and the first terminal of the seventh resistor. The second terminal of the third capacitor is grounded, and the fourth capacitor is connected in parallel across the sixth resistor; the first terminal of the fifth resistor is connected to the second power supply voltage, the second terminal of the fifth resistor is connected to the first terminal of the sixth resistor, and the second terminal of the sixth resistor is grounded; the second terminal of the seventh resistor is connected to the output terminal of the current sampling circuit.

[0011] In one possible implementation, the voltage between the base and emitter of the transistor has a negative temperature coefficient; the resistor divider circuit has a positive temperature coefficient.

[0012] In one possible implementation, the transistor is an NPN transistor; The base of the NPN transistor is connected to the output terminal of the operational amplifier circuit via an eighth resistor. The collector of the NPN transistor is grounded; the emitter of the NPN switching transistor is connected to the first power supply voltage through the ninth resistor and is connected to the input terminal of the resistor divider circuit; the collector and base of the NPN switching transistor are connected in parallel with the tenth resistor; the emitter and collector of the PNP switching transistor are connected in parallel with the fifth capacitor.

[0013] In one possible implementation, the resistor voltage divider circuit is an asymmetric resistor voltage divider circuit; the asymmetric resistor voltage divider circuit includes at least a third voltage divider resistor and a fourth voltage divider resistor; The third voltage divider resistor and the fourth voltage divider resistor are two fixed resistors with different resistance values; or, one of the third voltage divider resistors and the fourth voltage divider resistor is a fixed resistor and the other voltage divider resistor is an adjustable resistor. When the third and fourth voltage divider resistors are two fixed resistors with different resistance values, the first end of the third voltage divider resistor is connected to the output terminal of the transistor; the second end of the third voltage divider resistor is connected to the CIN pin of the IPM after being connected to the first end of the fourth voltage divider resistor; the second end of the fourth voltage divider resistor is grounded; and a fifth capacitor is connected in parallel with the second end of the third and fourth voltage divider resistors. When one of the third and fourth voltage divider resistors is a fixed resistor and the other is an adjustable resistor, the first end of the fixed resistor is connected to the output terminal of the transistor; the second end of the fixed resistor is connected to the first end of the adjustable resistor and then connected to the CIN pin of the IPM; the second end of the adjustable resistor is grounded; and the fifth capacitor is connected in parallel with the second end of the fixed resistor and the second end of the adjustable resistor.

[0014] In one possible implementation, the current sampling circuit includes a signal summing terminal and three shunt resistors; One end of each shunt resistor is connected to the three-phase current output terminal of the IPM, and the other end is connected to the signal summing terminal; the signal summing terminal is connected to the input terminal of the operational amplifier circuit.

[0015] Secondly, embodiments of this application disclose an intelligent power module, which includes an overcurrent protection circuit as described in any one of the first aspects.

[0016] Thirdly, embodiments of this application disclose a compressor, the compressor including an overcurrent protection circuit as described in any one of the first aspects, or the compressor including an intelligent power module as described in the second aspect.

[0017] This application provides an overcurrent protection circuit and related equipment for an intelligent power module. The overcurrent protection circuit includes a current sampling circuit, an operational amplifier circuit, a transistor, and a resistor divider circuit. The sampling terminal of the current sampling circuit is connected to the three-phase current output terminal of the intelligent power module, and its output terminal is connected to the input terminal of the operational amplifier circuit. The output terminal of the operational amplifier circuit is connected to the control terminal of the transistor. The input terminal of the resistor divider circuit is connected to the output terminal of the transistor, and its output terminal is connected to the CIN pin of the IPM. The temperature coefficients of the transistor and the resistor divider circuit are mutually compensating.

[0018] This application embodiment compensates for the temperature coefficients of the transistor and the resistor voltage divider circuit. This technical solution can effectively counteract the influence of temperature fluctuations on the characteristics of both, and prevent the voltage input to the CIN pin of the IPM from deviating from the preset overcurrent protection threshold due to temperature changes. This stabilizes the overcurrent protection action point, reduces protection false triggering or protection hysteresis caused by temperature drift, significantly improves the threshold accuracy and environmental adaptability of the overcurrent protection circuit, and thus ensures the reliability of the IPM and compressor drive system. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of a first overcurrent protection circuit provided in an embodiment of this application; Figure 2 A schematic diagram of a second overcurrent protection circuit provided in an embodiment of this application; Figure 3 A schematic diagram of a third overcurrent protection circuit provided in an embodiment of this application; Figure 4 A schematic diagram of a fourth overcurrent protection circuit provided in an embodiment of this application; Figure 5 A schematic diagram of the fifth overcurrent protection circuit provided in the embodiments of this application; Figure 6 This is a schematic diagram of a sixth overcurrent protection circuit provided in an embodiment of this application. Detailed Implementation

[0021] As described earlier, with the widespread application of variable frequency drive technology, the Intelligent Power Module (IPM) has become a core component in the drive systems of air conditioning compressors and industrial variable frequency compressors. It integrates a power switching unit and drive control circuitry, enabling efficient speed regulation and operation control of the compressor. The overcurrent protection circuit is one of the key supporting circuits for the stable operation of the IPM. Because compressors are prone to load fluctuations and sudden changes in operating conditions during operation, the overcurrent protection circuit needs to monitor the IPM's output current in real time. When the current exceeds the safe threshold, it promptly triggers the IPM's protection mechanism to prevent damage to the IPM and compressor hardware, ensuring the continuous and reliable operation of the entire drive system.

[0022] In one implementation, the overcurrent protection circuit of an IPM typically consists of a current sampling module, a signal processing module, and a protection triggering module. The current sampling module often uses a shunt resistor or a Hall sensor to collect the three-phase output current of the IPM and converts the current signal into a voltage signal. The signal processing module, with an operational amplifier at its core, compares the sampled voltage signal with a preset reference voltage and outputs a corresponding level signal to control the switching elements (such as transistors) in the protection triggering module to turn on or off. The protection triggering module then uses a resistor divider network to convert the output signal of the switching elements into a voltage signal adapted to the trigger threshold of the IPM's CIN pin. When this voltage signal reaches the preset threshold of the CIN pin, the IPM initiates the overcurrent protection process.

[0023] In practical applications, this implementation method has significant shortcomings. The resistors used in resistive voltage divider networks generally have a positive temperature coefficient, while the conduction characteristics of switching elements shift with changes in ambient temperature. Existing circuits do not adapt to these temperature characteristics, causing the voltage input to the CIN pin of the IPM to deviate from the preset overcurrent protection threshold during temperature fluctuations. This leads to a deviation in the trigger point of the protection action, either causing unnecessary system shutdown due to false triggering of protection when no overcurrent occurs, or failing to trigger protection in time during actual overcurrent, resulting in device damage. Simultaneously, ground loop currents in high-power compressor drive systems cause ground potential drift, which, combined with the voltage drop due to the resistance of the conductors, further amplifies the deviation in the protection threshold. These problems make it difficult for existing overcurrent protection circuits to meet the high requirements of stable operation in modern compressor drive systems in terms of accuracy and reliability.

[0024] This application provides an overcurrent protection circuit and related equipment for an intelligent power module. The overcurrent protection circuit includes a current sampling circuit, an operational amplifier circuit, a transistor, and a resistor divider circuit. The sampling terminal of the current sampling circuit is connected to the three-phase current output terminal of the intelligent power module, and its output terminal is connected to the input terminal of the operational amplifier circuit. The output terminal of the operational amplifier circuit is connected to the control terminal of the transistor. The input terminal of the resistor divider circuit is connected to the output terminal of the transistor, and its output terminal is connected to the CIN pin of the IPM. The temperature coefficients of the transistor and the resistor divider circuit are mutually compensating.

[0025] This application embodiment compensates for the temperature coefficients of the transistor and the resistor voltage divider circuit. This technical solution can effectively counteract the influence of temperature fluctuations on the characteristics of both, and prevent the voltage input to the CIN pin of the IPM from deviating from the preset overcurrent protection threshold due to temperature changes. This stabilizes the overcurrent protection action point, reduces protection false triggering or protection hysteresis caused by temperature drift, significantly improves the threshold accuracy and environmental adaptability of the overcurrent protection circuit, and thus ensures the reliability of the IPM and compressor drive system.

[0026] The overcurrent protection circuit provided in this application is applied to various compressor drive systems with an IPM as the core driving device. It is particularly suitable for hardware devices with high requirements for overcurrent protection accuracy and environmental adaptability, including household air conditioner compressors, commercial refrigeration unit compressors, industrial variable frequency air compressors, and new energy vehicle air conditioner compressors. In these hardware devices, the IPM, as the power core, is responsible for outputting three-phase current to drive the compressor. The overcurrent protection circuit provided in this application directly connects to the three-phase current output terminal of the IPM through the sampling terminal, capturing the current signal of the compressor in real time under conditions such as startup, load change, and long-term continuous operation. After processing by the operational amplifier circuit, the transistor is controlled to switch on and off, and then the trigger signal is accurately transmitted to the CIN pin of the IPM through the resistor voltage divider circuit. Whether in extreme temperature environments such as high temperatures in summer or low temperatures in winter, or in the complex electromagnetic environment generated by the high-frequency operation of the compressor, the circuit can stabilize the overcurrent protection threshold by utilizing the complementary temperature coefficient characteristics of the transistor and the resistor voltage divider circuit. This reduces the risk of false triggering or failure of the protection due to temperature drift, ensures the reliable operation of the IPM and other core hardware such as the compressor, and extends the service life of the entire drive system.

[0027] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0028] See Figure 1 , Figure 1 This is a schematic diagram of an overcurrent protection circuit provided in an embodiment of this application. The overcurrent protection circuit includes a current sampling circuit, an operational amplifier circuit, a transistor, and a resistor voltage divider circuit.

[0029] The sampling terminal of the current sampling circuit is connected to the three-phase current output terminal of the IPM, and the output terminal of the current sampling circuit is connected to the input terminal of the operational amplifier circuit. The output terminal of the operational amplifier circuit is connected to the control terminal of the transistor.

[0030] The input terminal of the resistor voltage divider circuit is connected to the output terminal of the transistor, and the output terminal of the resistor voltage divider circuit is connected to the CIN pin of the IPM; the temperature coefficient of the transistor and the temperature coefficient of the resistor voltage divider circuit compensate for each other.

[0031] As the core power device of the compressor drive system, the IPM's three-phase current output terminal is used to output drive current to the compressor, providing power for its operation. The IPM's CIN pin is the overcurrent protection trigger terminal. When the voltage signal received at the CIN pin exceeds a preset threshold, the IPM will immediately activate its internal protection mechanism, cutting off the output current to prevent itself and the compressor from being damaged by overcurrent.

[0032] The current sampling circuit monitors the three-phase current signal output by the IPM in real time and converts it into a voltage signal that can be recognized and processed by the operational amplifier circuit. The sampling terminal of the current sampling circuit is directly connected to the three-phase current output terminal of the IPM to ensure accurate capture of current changes during compressor operation. The output terminal of the current sampling circuit is connected to the input terminal of the operational amplifier circuit, transmitting the converted voltage sampling signal to the operational amplifier circuit for further processing.

[0033] In one possible implementation, the current sampling circuit includes a signal aggregation terminal and three shunt resistors. One end of each shunt resistor is connected to one of the three-phase current output terminals of the IPM, enabling real-time capture of the three-phase drive current signals output by the IPM. The other ends of all three resistors converge to the same signal aggregation terminal, achieving centralized integration of the three-phase current signals. The signal aggregation terminal is directly connected to the input terminal of the operational amplifier circuit, transmitting the integrated current sampling signal to the operational amplifier circuit for subsequent processing. During operation, the shunt resistors utilize their electrical characteristics to convert the current signal into a voltage signal recognizable by the operational amplifier circuit. The signal aggregation terminal ensures that the sampling data of the three-phase current can be transmitted synchronously, avoiding sampling omissions or delays caused by signal dispersion. This ensures that the circuit can accurately monitor changes in the three-phase output current of the IPM, providing a reliable signal basis for triggering subsequent overcurrent protection actions.

[0034] The operational amplifier (op-amp) circuit, as the core of signal comparison and processing, amplifies and performs threshold comparison on the voltage sampling signal transmitted by the current sampling circuit. The op-amp circuit's input receives the voltage signal output from the current sampling circuit, compares this signal with a preset reference voltage through internal comparison logic, and outputs a corresponding level signal based on the comparison result. The op-amp circuit's output is connected to the control terminal of a transistor, controlling the transistor's on or off state through the output level signal.

[0035] Transistors, acting as switching control elements, are used to switch their operating states based on the output signal of the operational amplifier circuit, thereby controlling the signal transmission of the resistor divider circuit. The control terminal of the transistor is connected to the output terminal of the operational amplifier circuit, receiving the level control signal output by the operational amplifier. The output terminal of the transistor is connected to the input terminal of the resistor divider circuit; when the transistor is turned on, it transmits a signal to the resistor divider circuit; when it is turned off, it cuts off signal transmission. Furthermore, the transistor has a specific temperature coefficient, which can complement the temperature coefficient of the resistor divider circuit.

[0036] A resistor divider circuit converts the signal transmitted by the transistor into a voltage signal adapted to the CIN pin threshold of the IPM. The input of the resistor divider circuit is connected to the output of the transistor, receiving the signal transmitted from the transistor. The output of the resistor divider circuit is connected to the CIN pin of the IPM, transmitting the divided voltage signal to the CIN pin to provide a precise signal for triggering the IPM's overcurrent protection. The resistors in the resistor divider circuit have an opposite temperature coefficient to those of the transistor, forming a complementary temperature coefficient relationship that counteracts characteristic shifts caused by temperature changes.

[0037] When the compressor starts running, the three-phase current output terminal of the IPM outputs drive current to the compressor. The current sampling circuit collects this three-phase current signal in real time and converts it into a corresponding voltage sampling signal, which is continuously transmitted to the input terminal of the operational amplifier circuit. The operational amplifier circuit compares the received voltage sampling signal with a preset reference voltage in real time. The preset reference voltage can be set according to the maximum current threshold for safe operation of the compressor. When the compressor is running normally and the current does not exceed the limit, the voltage sampling signal is less than the preset reference voltage. The operational amplifier circuit outputs a high-level signal, the transistor remains in the cutoff state, the resistor divider circuit has no signal input, the voltage at the CIN pin of the IPM is lower than the protection threshold, the IPM continues to output current normally, and the compressor operates stably.

[0038] When the compressor experiences a sudden load change or malfunction leading to an abnormal increase in current, the current signal collected by the current sampling circuit increases synchronously. The converted voltage sampling signal then exceeds the preset reference voltage, causing the operational amplifier circuit's output signal to switch from high to low. This low-level signal is transmitted to the control terminal of the transistor, triggering it to conduct. The transistor's output then transmits a signal to the resistor divider circuit. The resistor divider circuit divides this signal, generating a voltage signal that meets the protection threshold of the IPM's CIN pin, and transmits this voltage signal to the IPM's CIN pin. When the CIN pin detects that this voltage signal has reached the preset threshold, the IPM immediately activates its overcurrent protection mechanism, cutting off the three-phase current output to prevent hardware damage to the compressor and IPM due to prolonged overcurrent.

[0039] Temperature drift, also known as temperature displacement, refers to the phenomenon where the core electrical parameters (such as resistance, voltage, and current amplification factors) of electronic components deviate from their designed standard parameters when the ambient temperature changes. Drift is caused by the physical characteristics of the component itself and is a non-ideal characteristic. It shifts systematically with temperature changes, thus affecting the operating accuracy and stability of the entire circuit. For overcurrent protection circuits, temperature drift is one of the key factors leading to performance degradation.

[0040] The voltage between the base and emitter of the transistor has a negative temperature coefficient; the resistor voltage divider circuit has a positive temperature coefficient.

[0041] The electrical parameters of a transistor, especially the base-emitter voltage V. BE The current amplification factor β is extremely sensitive to temperature, and the electrical parameters of a transistor exhibit a negative temperature coefficient characteristic.

[0042] When the ambient temperature rises, the current amplification factor β increases, and the base-emitter voltage V of the transistor also increases. BE The base-emitter voltage V decreases. BE The decrease in I will cause the base current of the transistor to drop. B It is easier to increase, thus increasing the collector current I. C This increases, eventually causing the output potential V at the collector of the transistor (NPN or PNP type) to rise. C This potential shift directly alters the signal amplitude transmitted from the transistor to the resistor divider circuit. If not compensated, it will cause the output voltage of the subsequent divider circuit to deviate from the preset value, affecting the trigger threshold judgment of the IPM's CIN pin.

[0043] The core component of a resistive voltage divider circuit is a resistor. Ordinary resistors (such as carbon film resistors and metal film resistors) typically exhibit a positive temperature coefficient characteristic. When the ambient temperature rises, the resistance value in the voltage divider circuit increases with the temperature; when the temperature decreases, the resistance value decreases accordingly.

[0044] The output voltage of a resistor voltage divider circuit is determined by the voltage division ratio (e.g., R2 / (R1+R2)). When the resistance value changes due to temperature drift, the voltage division ratio will shift synchronously. For example, if the resistor voltage divider circuit is symmetrical, an increase in temperature will cause both R1 and R2 to increase in value, and the change in their resistance ratios will be consistent, resulting in a small shift in the voltage division ratio. If the resistor voltage divider circuit is asymmetrical, the change in resistance value will directly cause the output voltage to increase or decrease. This shift will cause the voltage signal transmitted to the CIN pin of the IPM to deviate from the overcurrent protection threshold, ultimately leading to the protection circuit triggering protection even when there is no overcurrent or failing to trigger protection even when there is an overcurrent.

[0045] Throughout the operation, the temperature coefficients of the transistor and the resistor divider circuit compensate for each other. When the ambient temperature rises or falls, the electrical characteristics of the transistor will shift due to its own temperature coefficient, and the resistance value in the resistor divider circuit will also drift accordingly with temperature changes. The two shifts are opposite in direction and matched in magnitude. Therefore, the temperature drift of the resistor divider circuit and the transistor can cancel each other out the effects of temperature changes, ensuring that the voltage signal output from the resistor divider circuit to the CIN pin remains stable near the preset protection threshold, avoiding false triggering or failure of protection actions due to temperature fluctuations.

[0046] The overcurrent protection circuit provided in this application, through reasonable component selection and connection design, effectively counteracts the interference of temperature changes on circuit characteristics by leveraging the complementary temperature coefficients of transistors and resistor voltage dividers. This avoids the overcurrent protection threshold inaccuracy problem caused by temperature drift in traditional circuits, significantly improving the operational stability and protection accuracy of the overcurrent protection circuit under different temperature environments. Simultaneously, the overcurrent protection circuit achieves rapid detection and protection triggering of overcurrent signals through a coherent logic of current sampling, operational amplifier comparison, transistor switching, and voltage divider triggering. It can cut off the IPM output at the first moment of compressor current abnormality, providing reliable overcurrent protection for both the IPM and the compressor. The overcurrent protection circuit has a simple structure and conventional component selection, making it easy to integrate into existing compressor drive systems. While ensuring protection performance, it reduces system upgrade and adaptation costs, demonstrating strong practicality and application value.

[0047] In overcurrent protection circuits, transistors serve as crucial switching control elements. The complementary temperature coefficients of transistors and resistor voltage dividers are key to stabilizing the overcurrent protection threshold. To adapt to the circuit design requirements, power supply logic, and installation layout of different compressor drive systems, the following sections will detail the specific implementation methods for NPN and PNP transistors, clarifying the component connection relationships corresponding to different types of transistors.

[0048] In one possible implementation, the transistor can be a PNP type transistor. For example... Figure 2As shown, the base (B) of the PNP transistor serves as the control terminal, connected to the output of the operational amplifier circuit via a first resistor (R1). Resistor R1 limits current, preventing excessively high output voltage from damaging the transistor's base and ensuring stable control signal transmission. The collector (C) of the PNP transistor serves as the output terminal, connected to the input of the resistor divider circuit, and grounded via a second resistor (R2), forming a loop to ensure signal transmission integrity. The emitter (E) of the PNP transistor is connected to the first power supply voltage (VCC1), providing the necessary power for the transistor to conduct.

[0049] To further optimize circuit stability, a third resistor R3 is connected in parallel between the emitter (E) and base (B) of the PNP transistor. R3 acts as a bias resistor, stabilizing the base potential and preventing external interference from causing the transistor to mis-turn on or off. A first capacitor C1 is connected in parallel between the emitter (E) and collector (C) of the PNP transistor. C1 filters out high-frequency interference signals in the circuit, suppresses voltage spikes, protects the transistor from damage caused by instantaneous high voltage, and improves the smoothness of signal transmission.

[0050] The current sampling circuit captures the current signal from the three-phase current output terminal of the IPM in real time, converts it into a voltage signal, and transmits it to the operational amplifier circuit. The operational amplifier circuit compares this voltage signal with a preset reference voltage and outputs a corresponding level based on the comparison result. When the compressor current is normal, the operational amplifier circuit outputs a high level, the base potential and emitter potential difference of the PNP transistor are small, the transistor remains in the off state, the resistor divider circuit has no effective signal input, the voltage at the CIN pin of the IPM is lower than the protection threshold, and the system operates normally. When the current abnormally increases, the operational amplifier circuit outputs a low level, the base potential of the PNP transistor decreases, the emitter and base form a forward bias, the PNP transistor conducts, and the first power supply voltage VCC1 outputs a signal through the collector of the PNP transistor to the resistor divider circuit. After voltage division processing, a voltage signal adapted to the CIN pin threshold of the IPM is generated, triggering the IPM overcurrent protection mechanism.

[0051] The base-emitter voltage V of a PNP transistor BE It has a negative temperature coefficient, V increases with temperature. BE A drop in temperature will cause a shift in the collector output potential; however, the resistors in the resistor divider circuit have a positive temperature coefficient, meaning their resistance increases with temperature, causing a reverse shift in the voltage division ratio. The temperature drift characteristics of both cancel each other out, effectively mitigating false triggering or protection failure caused by temperature drift. Simultaneously, the synergistic effect of the first capacitor C1 and the resistor divider circuit further enhances the circuit's resistance to high-frequency noise, ensuring stable and reliable overcurrent protection performance even in complex electromagnetic environments.

[0052] In another possible implementation, the transistor can be an NPN transistor. For example... Figure 3 As shown, the transistor can be an NPN transistor. The base (B) of the NPN transistor serves as the control terminal, connected to the output of the operational amplifier circuit via the eighth resistor (R8). The eighth resistor (R8) acts as a current limiter, preventing the output signal from being too high and damaging the transistor base, thus ensuring stable transmission of the control signal to the base. The collector (C) of the NPN transistor is directly grounded, forming the reference ground potential of the signal loop. The emitter (E) is connected to the first power supply voltage (VCC1) via the ninth resistor (R9). The ninth resistor (R9) provides the necessary power supply path for the transistor to conduct and also limits the current, preventing excessive emitter current from damaging the device. Simultaneously, the emitter (E) is also connected to the input of the resistor divider circuit, enabling effective signal transmission.

[0053] To further improve the stability of the circuit, a tenth resistor R10 is connected in parallel between the collector (C) and base (B) of the NPN transistor. R10 acts as a bias resistor, stabilizing the static potential of the transistor's base and preventing false turn-on or false cut-off caused by external electromagnetic interference or signal fluctuations. This ensures the transistor responds accurately to control signals under preset conditions. A fifth capacitor C5 is connected in parallel between the emitter (E) and collector (C) of the NPN transistor. C5 has a high-frequency filtering function, filtering out high-frequency interference signals generated by PWM driving, suppressing instantaneous voltage spikes, protecting the transistor from high-voltage damage, and smoothing the signal transmission waveform to reduce the impact of noise on subsequent voltage divider circuits.

[0054] The current sampling circuit captures the current signal from the three-phase current output terminal of the IPM in real time, converts it into a corresponding voltage signal, and transmits it to the operational amplifier circuit. The operational amplifier circuit compares the sampled voltage signal with a preset reference voltage and outputs a corresponding level signal based on the comparison result. When the compressor operating current is within the normal range, the operational amplifier circuit outputs a low level. At this time, the base potential of the NPN transistor is lower than the emitter potential, and the emitter and base cannot form a forward bias. The transistor remains in the off state, and the resistor divider circuit has no effective drive signal input. The voltage at the CIN pin of the IPM remains below the protection threshold, and the system operates normally. When the compressor current increases abnormally, the operational amplifier circuit outputs a high level, the base potential of the NPN transistor rises, the emitter and base form a forward bias, and the transistor quickly turns on. The first power supply voltage VCC1 is current-limited by the ninth resistor R9 and output to the resistor divider circuit through the emitter of the NPN transistor. After being processed by the voltage divider network, a voltage signal adapted to the protection threshold of the CIN pin of the IPM is generated. After the IPM detects this threshold voltage, it immediately triggers the overcurrent protection mechanism to avoid module damage.

[0055] The base-emitter voltage V of an NPN transistor BEBoth components have a negative temperature coefficient; as the ambient temperature rises, VBE decreases, causing a shift in the emitter output potential. Conversely, the resistors in the voltage divider circuit have a positive temperature coefficient; their resistance increases with temperature, causing a reverse shift in the voltage division ratio. The temperature drift characteristics of these two components compensate and cancel each other out, effectively mitigating the impact of temperature drift on the overcurrent protection threshold and preventing false triggering or failure of the protection due to temperature changes. Simultaneously, the fifth capacitor C5 and the resistor divider network form a collaborative filtering structure, further enhancing the circuit's ability to suppress high-frequency switching noise. Even in the complex electromagnetic environment of high-frequency compressor operation, the overcurrent protection circuit maintains stable and reliable performance, ensuring the safe operation of the IPM module and the compressor drive system.

[0056] In overcurrent protection circuits, resistor dividers convert the transistor output signal into a voltage signal that matches the trigger threshold of the CIN pin of the IPM. The temperature coefficient of the resistor divider compensates for the temperature coefficient of the transistor. To accommodate the anti-interference requirements, protection threshold adjustment requirements, and hardware layout conditions of different compressor drive systems, the following sections will detail the specific connection relationships of overcurrent protection circuits under two topologies: symmetrical and asymmetrical resistor dividers.

[0057] In one possible implementation, the resistor voltage divider circuit can be a symmetrical resistor voltage divider circuit. By using voltage divider resistors with equal resistance values ​​and a filter capacitor, the overcurrent protection circuit's ability to resist high-frequency interference is enhanced, making it suitable for applications with high-frequency switching noise in compressor drive systems. For example... Figure 4 As shown, the symmetrical resistor voltage divider network includes a first voltage divider resistor Rx and a second voltage divider resistor Ry, and the resistance values ​​of the first voltage divider resistor Rx and the second voltage divider resistor Ry are the same.

[0058] The first terminal of the first voltage divider resistor Rx serves as the input terminal of the entire voltage divider circuit, connected to the output terminal of the transistor, receiving the electrical signal transmitted after the transistor is turned on. The second terminal of the first voltage divider resistor Rx is connected to the first terminal of the second voltage divider resistor Ry, and their connection point serves as the output terminal of the symmetrical resistor voltage divider circuit, connected to the CIN pin of the IPM, responsible for transmitting the divided voltage signal to the protection trigger terminal of the IPM. The second terminal of the second voltage divider resistor Ry is directly grounded, forming a complete voltage divider loop. In addition, a second capacitor C2 is connected in parallel between the second terminals of the first voltage divider resistor Rx and the second voltage divider resistor Ry. The second capacitor C2 and the voltage divider resistors work together to form a filter structure to suppress high-frequency switching noise in the circuit.

[0059] When the transistor is turned on and inputs an electrical signal to the symmetrical resistor voltage divider circuit, the current flows through the first voltage divider resistor Rx and the second voltage divider resistor Ry in sequence. Since the resistance values ​​of the first voltage divider resistor Rx and the second voltage divider resistor Ry are equal, according to the voltage divider principle, the output voltage of the voltage divider node is 1 / 2 of the input voltage, which can match the protection threshold requirement of the CIN pin of the IPM.

[0060] Regarding temperature drift compensation, the first voltage divider resistor Rx and the second voltage divider resistor Ry can be made of the same material and have the same specifications. The positive temperature coefficient characteristics of the first voltage divider resistor Rx and the second voltage divider resistor Ry are the same. When the ambient temperature changes, the resistance values ​​of the first voltage divider resistor Rx and the second voltage divider resistor Ry will increase or decrease synchronously, and the voltage division ratio will always remain stable and will not shift due to temperature fluctuations.

[0061] Meanwhile, the overall temperature drift characteristics of this symmetrical resistor divider circuit complement the negative temperature coefficient of the transistor. When the temperature rises, the offset of the transistor's output potential is offset by the reverse voltage offset generated by the increased resistance of the voltage divider network, ultimately ensuring that the voltage signal transmitted to the CIN pin of the IPM remains stable near the preset threshold, avoiding protection false triggering or hysteresis problems caused by temperature drift.

[0062] The second capacitor C2, connected in parallel in the voltage divider circuit, further enhances the circuit's reliability. During the operation of the compressor drive system, a large amount of high-frequency pulse-width modulation (PWM) switching noise is generated. This noise easily couples to the voltage divider circuit, interfering with the output signal. The second capacitor short-circuits the high-frequency noise signal to ground, preventing it from transmitting to the CIN pin of the IPM, thus ensuring the purity of the protection trigger signal. Simultaneously, the second capacitor C2 also suppresses instantaneous voltage spikes, preventing false triggering of the IPM's protection mechanism by voltage spikes. In summary, the symmetrical resistive voltage divider circuit, while achieving temperature drift compensation, also addresses the need for high-frequency noise immunity, making it suitable for variable frequency compressor drive systems with high requirements for protection accuracy and anti-interference capabilities.

[0063] In another possible implementation, the resistor divider circuit can adopt an asymmetric topology. By flexibly configuring the resistor specifications, it can adapt to the CIN pin trigger threshold requirements of different IPM models, greatly improving the circuit's versatility and scenario adaptability.

[0064] like Figure 5 As shown, an asymmetric resistor voltage divider circuit includes at least a third voltage divider resistor Rm and a fourth voltage divider resistor Rn. Specifically, it can be configured in two ways: the third voltage divider resistor Rm and the fourth voltage divider resistor Rn are fixed resistors with different resistance values; or, one of the third voltage divider resistor Rm and the fourth voltage divider resistor Rn is a fixed resistor, and the other is an adjustable resistor.

[0065] When two fixed resistors with different resistance values ​​are used, the first terminal of the third voltage divider resistor Rm serves as the input terminal of the voltage divider circuit, directly connected to the output terminal of the transistor, receiving the electrical signal transmitted after the transistor is turned on. The second terminal of the third voltage divider resistor Rm is connected to the first terminal of the fourth voltage divider resistor Rn, and their connection point serves as the output terminal of the voltage divider circuit, connected to the CIN pin of the IPM, transmitting the divided voltage signal to the protection trigger terminal of the IPM. The second terminal of the fourth voltage divider resistor Rn is directly grounded, forming a complete voltage divider circuit. Because the resistance values ​​of the third and fourth voltage divider resistors Rm and Rn differ, the voltage division ratio is determined by the ratio of their resistance values. The resistor values ​​can be flexibly selected according to the CIN pin threshold requirements of different IPMs, adapting to diverse hardware needs without changing the circuit topology.

[0066] When using a configuration of fixed and adjustable resistors, taking the third voltage divider resistor Rm as a fixed resistor and the fourth voltage divider resistor Rn as an adjustable resistor as an example.

[0067] The first terminal of the third voltage divider resistor Rm serves as the input terminal of the asymmetric resistor voltage divider circuit, directly connected to the output terminal of the transistor, receiving the electrical signal transmitted after the transistor is turned on. The second terminal of the third voltage divider resistor Rm is connected to the first terminal of the fourth voltage divider resistor Rn, and their connection point serves as the output terminal of the voltage divider circuit, connected to the CIN pin of the IPM, responsible for transmitting the divided voltage signal to the overcurrent protection trigger terminal. The second terminal of the fourth voltage divider resistor Rn is directly grounded, forming a complete voltage divider circuit. The resistance value of the third voltage divider resistor Rm can be pre-selected based on the voltage threshold of the IPM's CIN pin and the transistor's output voltage range to ensure the voltage division range is within a reasonable range. The fourth voltage divider resistor Rn is a linearly adjustable precision potentiometer, whose resistance adjustment range covers the discrete range of the IPM threshold, meeting the calibration requirements of different batches of devices.

[0068] In both implementation methods described above, whether it's a combination of fixed resistors or a combination of a fixed resistor and an adjustable resistor, a fifth capacitor C5 is connected in parallel between the second terminal of the third voltage divider resistor Rm (the fixed resistor) and the second terminal of the fourth voltage divider resistor Rn (the fixed resistor or the adjustable resistor). One end of the fifth capacitor C5 is connected to the connection point of the third voltage divider resistor Rm and the fourth voltage divider resistor Rn, and the other end of the fifth capacitor C5 is grounded, forming a composite circuit combining voltage division and filtering.

[0069] The fifth capacitor, C5, together with the resistor in the asymmetrical resistor divider circuit, forms a low-pass filter structure. High-frequency PWM switching noise and electromagnetic coupling interference signals generated during the operation of the compressor drive system are quickly short-circuited to ground by the fifth capacitor, C5, preventing interference signals from being superimposed on the divided output voltage. This ensures the purity of the signal transmitted to the CIN pin of the IPM and prevents high-frequency noise from falsely triggering the protection mechanism. Simultaneously, the fifth capacitor, C5, effectively suppresses instantaneous voltage spikes at the voltage divider node, buffering voltage fluctuations caused by transistor switching and sudden load changes in the circuit, protecting the CIN pin of the IPM from instantaneous high-voltage impacts, and extending the device's lifespan. It should be noted that the fifth capacitor, C5, has no effect on DC voltage division; it only affects high-frequency AC signals.

[0070] Furthermore, in both embodiments described above, the third and fourth voltage-dividing resistors Rm and Rn in the asymmetric resistor divider circuit both possess positive temperature coefficients. When the ambient temperature changes, the resistance values ​​shift synchronously, and their overall temperature drift characteristics complement the negative temperature coefficient of the transistor. When a temperature increase causes a shift in the transistor's output potential, the change in resistance value leads to a reverse adjustment of the voltage division ratio, ultimately offsetting the threshold deviation caused by temperature drift and ensuring that the input voltage at the CIN pin of the IPM remains stable within the preset range. Simultaneously, this topology is simple and inexpensive, making it suitable for scenarios requiring high flexibility in protection thresholds, such as compressor drive systems compatible with multiple IPM models and small-batch customized industrial frequency converters.

[0071] In overcurrent protection circuits, the operational amplifier (op-amp) circuit, as the core of signal processing, is used to convert the current sampling signal into a control signal for the transistor. The connection stability and signal processing accuracy of the op-amp circuit directly affect the response efficiency of the entire protection circuit. To further clarify the specific implementation of the op-amp circuit, the topology of the op-amp circuit will be introduced below with reference to the accompanying drawings, detailing the connection relationships, functional divisions, and collaborative logic with other circuit modules.

[0072] In one possible implementation, such as Figure 6 As shown, the operational amplifier circuit includes operational amplifier U1B, fourth resistor R4, fifth resistor R5, sixth resistor R6, seventh resistor R7, third capacitor C3, and fourth capacitor C4.

[0073] The fourth resistor R4 is connected in parallel between the output terminal 3 and the non-inverting input terminal 1 of operational amplifier U1B, forming a feedback link. The output terminal 3 of operational amplifier U1B is connected to the control terminal of the transistor, transmitting the processed level signal to the transistor to control its on / off state. The non-inverting input terminal 1 of operational amplifier U1B is connected to the common node of the fifth resistor R5 and the sixth resistor R6, and the inverting input terminal 2 of operational amplifier U1B is connected to the first terminal of the third capacitor C3 and the first terminal of the seventh resistor R7.

[0074] The first terminal of the fifth resistor R5 is connected to the second power supply voltage VCC2. The second terminal of the fifth resistor R5 is connected to the first terminal of the sixth resistor R6, and the second terminal of the sixth resistor R6 is grounded. Together, they form a reference voltage divider network, providing a stable reference potential for the non-inverting input terminal 1 of operational amplifier U1B. The fourth capacitor C4 is connected in parallel across the sixth resistor R6 to filter out high-frequency noise in the reference voltage and improve the stability of the reference potential. The second terminal of the third capacitor C3 is grounded, forming a filter structure with the seventh resistor R7. The second terminal of the seventh resistor R7 is connected to the output terminal of the current sampling circuit to receive the voltage signal after sampling and conversion.

[0075] The voltage divider network formed by the fifth resistor R5 and the sixth resistor R6 generates a stable reference voltage powered by the second power supply voltage VCC2, providing an accurate comparison reference for operational amplifier U1B and preventing signal misinterpretation due to reference fluctuations. The fourth resistor R4 acts as a feedback resistor, forming a hysteresis comparator structure with operational amplifier U1B. This amplifies the difference between the sampled signal and the reference voltage, improves the circuit's anti-interference capability, and prevents minor fluctuations in the sampled signal from triggering transistor malfunctions. The third capacitor C3 and the seventh resistor R7 form a low-pass filter circuit, filtering high-frequency interference in the current sampling signal and ensuring the purity of the signal input to the inverting input terminal 2 of operational amplifier U1B. The fourth capacitor C4 specifically suppresses high-frequency noise in the reference voltage, further improving comparison accuracy.

[0076] Under normal operating conditions, the voltage signal output by the current sampling circuit is transmitted to the inverting input terminal 2 of operational amplifier U1B via the seventh resistor R7. At this time, the signal voltage is lower than the reference voltage at the non-inverting input terminal 1, the operational amplifier U1B outputs a high level, the transistor remains in the off state, the resistor divider circuit has no signal input, and the IPM operates normally. When the compressor current increases abnormally, the sampling signal voltage rises synchronously and exceeds the reference voltage. The output signal of operational amplifier U1B switches to a low level, triggering the transistor to conduct, thereby initiating the subsequent resistor divider and IPM protection triggering process.

[0077] The operational amplifier circuit's topology design ensures both the accuracy and speed of signal processing, while strengthening anti-interference capabilities through multiple filtering and feedback structures, making it suitable for the complex electromagnetic environment of compressor drive systems. Simultaneously, the operational amplifier circuit is only responsible for signal conversion and transmission, without affecting the complementary temperature coefficient mechanism of the transistor and resistor divider circuits. This ensures that the temperature drift compensation function and signal processing function work independently and collaboratively, further enhancing the reliability and stability of the entire overcurrent protection circuit.

[0078] This application also provides an intelligent power module, which includes the overcurrent protection circuit as described in any of the above embodiments.

[0079] This application also provides a compressor, which includes an overcurrent protection circuit as described in any of the above embodiments, or the compressor includes an intelligent power module as described in the above embodiments.

[0080] In the embodiments of this application, the terms "first" and "second" (if they exist) are used only as name identifiers and do not represent the order of first and second.

[0081] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0082] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An overcurrent protection circuit for an intelligent power module, characterized in that, The overcurrent protection circuit includes a current sampling circuit, an operational amplifier circuit, a transistor, and a resistor voltage divider circuit. The sampling terminal of the current sampling circuit is connected to the three-phase current output terminal of the intelligent power module IPM, and the output terminal of the current sampling circuit is connected to the input terminal of the operational amplifier circuit. The output terminal of the operational amplifier circuit is connected to the control terminal of the transistor. The input terminal of the resistor voltage divider circuit is connected to the output terminal of the transistor, and the output terminal of the resistor voltage divider circuit is connected to the CIN pin of the IPM; wherein, the temperature coefficient of the transistor and the temperature coefficient of the resistor voltage divider circuit compensate for each other.

2. The circuit according to claim 1, characterized in that, The transistor is a PNP type transistor; The base of the PNP transistor is connected to the output terminal of the operational amplifier circuit through a first resistor; The collector of the PNP transistor is connected to the input terminal of the resistor divider circuit and grounded through the second resistor; the emitter of the PNP transistor is connected to the first power supply voltage; the emitter and base of the PNP transistor are connected in parallel with a third resistor; and the emitter and collector of the PNP transistor are connected in parallel with a first capacitor C1.

3. The circuit according to claim 1, characterized in that, The resistor voltage divider circuit is a symmetrical resistor voltage divider network; the symmetrical resistor voltage divider network includes a first voltage divider resistor and a second voltage divider resistor, the resistance values ​​of the first voltage divider resistor and the second voltage divider resistor are equal; the symmetrical resistor voltage divider network is used to suppress high-frequency switching noise; The first end of the first voltage divider resistor is connected to the output terminal of the transistor; the second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor, and then connected to the CIN pin of the IPM. The second terminal of the second voltage divider resistor is grounded, and the second terminal of the first voltage divider resistor and the second terminal of the second voltage divider resistor are connected in parallel with a second capacitor.

4. The circuit according to claim 1, characterized in that, The operational amplifier circuit includes an operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, and a fourth capacitor. The fourth resistor is connected in parallel to the output terminal and the non-inverting input terminal of the operational amplifier; The output terminal of the operational amplifier is connected to the control terminal of the transistor; the non-inverting input terminal of the operational amplifier is connected to the common terminal of the fifth resistor and the sixth resistor; the inverting input terminal of the operational amplifier is connected to the first terminal of the third capacitor and the first terminal of the seventh resistor. The second terminal of the third capacitor is grounded, and the fourth capacitor is connected in parallel across the sixth resistor; the first terminal of the fifth resistor is connected to the second power supply voltage, the second terminal of the fifth resistor is connected to the first terminal of the sixth resistor, and the second terminal of the sixth resistor is grounded; the second terminal of the seventh resistor is connected to the output terminal of the current sampling circuit.

5. The circuit according to any one of claims 1-4, characterized in that, The voltage between the base and emitter of the transistor has a negative temperature coefficient; the resistor voltage divider circuit has a positive temperature coefficient.

6. The circuit according to claim 1, characterized in that, The transistor is an NPN type transistor; The base of the NPN transistor is connected to the output terminal of the operational amplifier circuit via an eighth resistor. The collector of the NPN transistor is grounded; the emitter of the NPN switching transistor is connected to the first power supply voltage through the ninth resistor and is connected to the input terminal of the resistor divider circuit; the collector and base of the NPN switching transistor are connected in parallel with the tenth resistor; the emitter and collector of the PNP switching transistor are connected in parallel with the fifth capacitor.

7. The circuit according to claim 1, characterized in that, The resistor voltage divider circuit is an asymmetric resistor voltage divider circuit; the asymmetric resistor voltage divider circuit includes at least a third voltage divider resistor and a fourth voltage divider resistor; The third voltage divider resistor and the fourth voltage divider resistor are two fixed resistors with different resistance values; or, one of the third voltage divider resistors and the fourth voltage divider resistor is a fixed resistor and the other voltage divider resistor is an adjustable resistor. When the third and fourth voltage divider resistors are two fixed resistors with different resistance values, the first end of the third voltage divider resistor is connected to the output terminal of the transistor; the second end of the third voltage divider resistor is connected to the CIN pin of the IPM after being connected to the first end of the fourth voltage divider resistor; the second end of the fourth voltage divider resistor is grounded; and a fifth capacitor is connected in parallel with the second end of the third and fourth voltage divider resistors. When one of the third and fourth voltage divider resistors is a fixed resistor and the other is an adjustable resistor, the first end of the fixed resistor is connected to the output terminal of the transistor; the second end of the fixed resistor is connected to the first end of the adjustable resistor and then connected to the CIN pin of the IPM; the second end of the adjustable resistor is grounded; and the fifth capacitor is connected in parallel with the second end of the fixed resistor and the second end of the adjustable resistor.

8. The circuit according to claim 1, characterized in that, The current sampling circuit includes a signal collection terminal and three shunt resistors; One end of each shunt resistor is connected to the three-phase current output terminal of the IPM, and the other end is connected to the signal summing terminal; the signal summing terminal is connected to the input terminal of the operational amplifier circuit.

9. A smart power module, characterized in that, The intelligent power module includes the overcurrent protection circuit as described in any one of claims 1-8.

10. A compressor, characterized in that, The compressor includes an overcurrent protection circuit as described in any one of claims 1-8, or the compressor includes an intelligent power module as described in claim 9.

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