PFC circuit and electronic device

Abstract

The application discloses a PFC circuit and electronic equipment, in the PFC circuit, when the voltage of the electrical signal output by the rectifier circuit suddenly changes, the voltage value of the energy storage module will also change greatly, and the output end of the detection module is connected with the control circuit and the switching circuit respectively, so that when the detection module detects that the voltage value of the energy storage module changes greatly, the voltage value of the control signal can be changed, the on-off state of the control circuit controlling the switching circuit is affected, and thus when the detection module detects that the voltage change value of the energy storage module is greater than a target voltage, the switching circuit is controlled to disconnect the output end of the rectifier circuit and the ground end, so that the control circuit cannot timely output the control signal for disconnecting the output end of the rectifier circuit and the ground end of the switching circuit when the voltage of the electrical signal output by the rectifier circuit suddenly changes, and overcurrent or even damage of the device is caused.

Description

Technical Field

[0001] This application relates to electronic control technology, including but not limited to a PFC circuit and electronic device. Background Technology

[0002] To maintain a constant bus voltage, the power factor correction (PFC) circuit operates with a low duty cycle for the power switching transistors (e.g., insulated-gate bipolar transistors, IGBTs) when the input voltage is high. Conversely, when the input voltage is low, the power switching transistors maintain a higher duty cycle. The controller acquires the input voltage value in real time and controls the PFC duty cycle based on the difference between the input voltage and the bus voltage.

[0003] When the mains voltage experiences a phase loss or other interference, the input voltage may suddenly change from a trough to a peak or experience a high-voltage disturbance at a trough. Because the PFC duty cycle is large at this time, the controller cannot recognize the sudden change in input voltage in time and cannot respond and adjust the duty cycle in a timely manner. The high duty cycle combined with a large input voltage will cause the current flowing through the power switch tube to rise rapidly. This may cause the PFC to shut down due to overcurrent or damage the power device. Utility Model Content

[0004] In view of this, the PFC circuit and electronic device provided in the embodiments of this application can respond more quickly to sudden changes in input voltage, rapidly control the PFC switching on and off, and prevent overcurrent or even damage to the device.

[0005] In a first aspect, embodiments of this application provide a PFC circuit, including:

[0006] A rectifier circuit, wherein the input terminal of the rectifier circuit is connected to an AC input terminal, and the output terminal of the rectifier circuit is connected to a load;

[0007] Control circuit, used to output control signals;

[0008] A switching circuit, wherein the control terminal of the switching circuit is connected to the output terminal of the control circuit, the input terminal of the switching circuit is connected to the output terminal of the rectifier circuit, and the output terminal of the switching circuit is connected to ground. The switching circuit is used to turn on or off the connection between the output terminal of the rectifier circuit and the ground terminal according to the control signal.

[0009] An overcurrent protection circuit is provided, wherein the input terminal of the overcurrent protection circuit is connected to the rectifier circuit, and the output terminal of the overcurrent protection circuit is connected to the control circuit and the switching circuit respectively. The overcurrent protection circuit is used to control the switching circuit to disconnect the output terminal of the rectifier circuit from the ground terminal when the voltage change value of the electrical signal output by the rectifier circuit is detected to be greater than the target voltage.

[0010] The overcurrent protection circuit includes an energy storage module and a detection module. One end of the energy storage module is connected to the output terminal of the rectifier circuit, and the other end of the energy storage module is connected to the input terminal of the detection module. The output terminal of the detection module is connected to the control circuit and the switching circuit respectively. When the detection module detects that the voltage change value of the energy storage module is greater than the target voltage, it controls the switching circuit to disconnect the output terminal of the rectifier circuit from the ground terminal.

[0011] In the aforementioned PFC circuit, a sudden voltage change in the output signal of the rectifier circuit will also cause a significant change in the voltage of the energy storage module. Since the output of the detection module is connected to both the control circuit and the switching circuit, when the detection module detects a significant change in the voltage of the energy storage module, it can change the voltage value of the control signal, affecting the on / off state of the switching circuit controlled by the control circuit. Thus, when the detection module detects that the voltage change of the energy storage module is greater than the target voltage, it controls the switching circuit to disconnect the output of the rectifier circuit from the ground. This prevents damage to the components in the switching circuit caused by the control circuit failing to output the control signal to disconnect the output of the rectifier circuit from the ground in time when the voltage of the output signal of the rectifier circuit changes suddenly.

[0012] In some embodiments, the detection module includes a voltage detection unit, a comparator, and a first switching transistor. The first input terminal of the comparator is connected to the energy storage module, the second input terminal of the comparator is connected to a reference power supply, the output terminal of the comparator is connected to the control terminal of the first switching transistor, the input terminal of the first switching transistor is connected to the control circuit, and the output terminal of the first switching transistor is connected to ground.

[0013] The reference power supply is used to output the target voltage;

[0014] The voltage detection unit is used to detect the voltage change value of the energy storage module and output the corresponding voltage signal;

[0015] The comparator is used to control the first switch to disconnect the control circuit and the ground terminal when the voltage value of the voltage signal is greater than the target voltage.

[0016] It is understandable that the instantaneous voltage change value of the energy storage module is detected by the voltage detection unit, and the corresponding voltage signal is output to the comparator. The comparator compares the voltage value of the voltage signal with the target voltage, and controls the on / off state of the first switching transistor based on the comparison result. The overall circuit structure is simple, does not require the calculation and control of the controller, and can respond more quickly to sudden changes in the input voltage.

[0017] In some embodiments, the voltage detection unit includes a resistor, the energy storage module includes a capacitor, and the resistor and the capacitor constitute an RC differentiating circuit.

[0018] It is understandable that by setting a resistor and forming an RC differentiating circuit with the resistor and capacitor, the input of the RC differentiating circuit is the voltage value of the capacitor, and the output of the RC differentiating circuit is the voltage value after differentiating the voltage of the capacitor. The voltage value after differentiating the voltage of the capacitor can characterize the voltage change of the capacitor. The overall circuit structure is simple and can quickly respond to the speed of voltage change.

[0019] In some embodiments, the resistor includes a first resistor and a second resistor, one end of the first resistor is connected to the other end of the capacitor, the other end of the first resistor is connected to the first input terminal of the comparator, one end of the second resistor is connected between the other end of the first resistor and the first input terminal of the comparator, and the other end of the second resistor is connected to ground.

[0020] It is understandable that when the voltage of a capacitor changes abruptly, the change will be reflected by the current of the capacitor. The first resistor can convert the current of the capacitor into voltage, which makes it convenient for the comparator to compare the voltage. The overall circuit structure is simple and the components are inexpensive.

[0021] In some embodiments, the control circuit includes a controller connected to the input terminals of the switching circuit and the first switching transistor, respectively.

[0022] It is understandable that by connecting the controller to the input terminals of the switching circuit and the first switching transistor respectively, the input terminal of the first switching transistor can be placed between the controller and the switching circuit. This allows the first switching transistor to disconnect the connection between the controller and the ground terminal when the comparator outputs a detection signal representing a sudden change in the voltage of the energy storage module, thereby pulling down the voltage at the drive terminal of the switching circuit and improving the operational stability of the circuit.

[0023] In some embodiments, the controller is also connected to the output terminal of the rectifier circuit to detect the voltage value at the output terminal of the rectifier circuit, and outputs a target control signal when the detected voltage value at the output terminal of the rectifier circuit is greater than a preset voltage threshold. The target control signal is used to control the switching circuit to be in a first duty cycle, which is different from a second duty cycle, where the second duty cycle is the duty cycle when the voltage value at the output terminal of the rectifier circuit is less than or equal to the preset voltage threshold.

[0024] Understandably, the overcurrent protection circuit affects the conduction state of the switching circuit when the voltage at the output of the rectifier circuit changes abruptly, but does not change the control signal output by the controller. Therefore, after the voltage at the output of the rectifier circuit stabilizes, the conduction state of the switching circuit is still controlled by the controller. Thus, the overcurrent protection circuit serves as an auxiliary protection measure for the PFC circuit. By connecting the controller to the output of the rectifier circuit, the controller can detect the voltage value at the output of the rectifier circuit in real time. When the voltage value at the output of the rectifier circuit exceeds a preset voltage threshold, the controller outputs a target control signal to the switching circuit. The controller can then change the control signal to protect the PFC circuit and improve its stability.

[0025] In some embodiments, the switching circuit includes a second switching transistor and a driving circuit. The input terminal of the driving circuit is connected to the control circuit and the first switching transistor, respectively. The output terminal of the driving circuit is connected to the driving terminal of the second switching transistor. The input terminal of the second switching transistor is connected to the output terminal of the rectifier circuit. The output terminal of the second switching transistor is connected to ground.

[0026] It is understandable that since the second switching transistor used in the PFC circuit is usually a high-power switching device, and the voltage value of the control circuit does not match the driving voltage value of the high-power switching device, a driving circuit needs to be set between the control circuit and the second switching transistor. The driving circuit converts the control signal output by the control circuit into a driving voltage that matches the second switching transistor, thereby stabilizing the driving of the second switching transistor.

[0027] In some embodiments, the first switching transistor is a bipolar transistor.

[0028] Understandably, because the comparator output voltage is relatively low, the first switching transistor can be set as a bipolar transistor to reduce device cost.

[0029] In some embodiments, when the voltage at the output of the rectifier circuit increases abnormally, the smaller the values ​​of the capacitor and resistor, the greater the voltage change of the energy storage module.

[0030] It is understandable that the RC differentiating circuit composed of capacitors and resistors needs to respond promptly to changes in capacitor voltage. However, if the values ​​of capacitors and resistors are large, the charging and discharging speed of the capacitor is slow, and the charging current of the capacitor is large during normal operation. When the output voltage of the rectifier circuit changes abruptly, it is difficult for this step voltage to generate a voltage signal at the comparator input that is much larger than the voltage signal during normal operation. Therefore, setting smaller values ​​for capacitors and resistors can increase the amplitude of the capacitor voltage change, and the comparator can output the detection signal that controls the first switching transistor to disconnect the control circuit and ground more quickly, thereby improving the response speed of overcurrent protection.

[0031] Secondly, embodiments of this application provide an electronic device including the PFC circuit described in the first aspect. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the specification, serve to explain the technical solutions of this application.

[0033] Figure 1 A schematic diagram of the structure of a PFC circuit provided in related technologies;

[0034] Figure 2 This is a waveform diagram of the input voltage and the rectified voltage in the relevant technology;

[0035] Figure 3 This is a schematic diagram of the overcurrent protection circuit provided in the embodiments of this application;

[0036] Figure 4 This is a schematic diagram of the overcurrent protection circuit provided in the embodiments of this application;

[0037] Figure 5 This is a schematic diagram of the overcurrent protection circuit provided in the embodiments of this application;

[0038] Figure 6 This is a schematic diagram of the overcurrent protection circuit provided in the embodiments of this application;

[0039] Figure 7 This is a schematic diagram of the PFC circuit provided in an embodiment of this application;

[0040] Figure 8 This is a schematic diagram of the switching circuit provided in an embodiment of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the specific technical solutions of this application will be further described in detail below with reference to the accompanying drawings of the embodiments of this application. The following embodiments are used to illustrate this application, but are not intended to limit the scope of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0043] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0044] It should be noted that the terms "first, second, third" used in the embodiments of this application are used to distinguish similar or different objects and do not represent a specific order of objects. It can be understood that "first, second, third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0045] Figure 1 This provides a schematic diagram of a PFC circuit in the related art. For example... Figure 1 As shown, the PFC circuit may include a rectifier circuit 101, a control circuit 103, and a switch circuit 102. The input terminal of the rectifier circuit 101 is connected to the AC input terminal, the output terminal of the rectifier circuit 101 is connected to the load, the control terminal of the switch circuit 102 is connected to the output terminal of the control circuit 103, the input terminal of the switch circuit 102 is connected to the output terminal of the rectifier circuit 101, and the output terminal of the switch circuit 102 is connected to the ground terminal.

[0046] To maintain a constant bus voltage, the PFC circuit uses control circuit 103 to collect the input voltage value at the AC input terminal in real time via sampling resistor R. Based on the difference between the input voltage and the bus voltage, the duty cycle of switch circuit 102 is adjusted. That is, when the input voltage at the AC input terminal is high, the duty cycle of switch circuit 102 output by control circuit 103 is low; when the input voltage at the AC input terminal is low, the duty cycle of switch circuit 102 output by control circuit 103 is high.

[0047] However, when the mains voltage experiences a phase loss or other interference, the input voltage may suddenly change from a trough to a peak, or a high-voltage disturbance may occur during a trough. Because the duty cycle of the switching circuit 102 is large at this time, the control circuit 103 cannot detect the sudden change in input voltage in time and therefore cannot respond and adjust the duty cycle accordingly. A high duty cycle combined with a large input voltage will cause the current flowing through the switching circuit 102 to rise rapidly, potentially causing PFC overcurrent shutdown or even damaging power devices.

[0048] The input voltage is rectified by the rectifier circuit 101 to form the following... Figure 2As shown in the waveform, the PFC circuit adjusts the duty cycle of the switching circuit 102 according to the input voltage. When the input voltage is at its peak, a lower duty cycle is sufficient to maintain the required bus voltage. When the input voltage is at its trough, the duty cycle needs to be increased to maintain the bus voltage with a higher boost ratio.

[0049] If a phase loss occurs in the input voltage, causing a direct jump from the trough to the peak, or if a high-voltage surge occurs at the trough, the control circuit 103 detects the anomaly by measuring the input voltage through the sampling resistor and reduces the duty cycle of the switching circuit 102 to prevent high voltage from directly affecting the high-duty-cycle PFC circuit. Simultaneously, during the input voltage acquisition process by the control circuit 103 through the sampling resistor, a filter capacitor needs to be added to avoid noise in the input voltage acquired by the control circuit 103, which could lead to malfunctions. The depth of the filter capacitor not only affects the frequency of malfunctions in the control circuit 103 but may also affect loop stability. A deeper filter depth results in a slower response speed of the control circuit 103 to the rectified voltage change, causing a rapid increase in the rectified current within a short period, potentially leading to protection shutdown, impacting user experience, and even posing a risk of device damage.

[0050] In view of the above problems, embodiments of this application provide a PFC circuit, in Figure 1 An overcurrent protection circuit 104 is added to the PFC circuit shown. The overcurrent protection circuit 104 can detect rapid changes in the rectified voltage and directly act on the control signal output by the control circuit 103 to shut down the switching circuit 102 and protect the PFC circuit.

[0051] In some embodiments, such as Figure 3 As shown, the PFC circuit described above may include a rectifier circuit 101, a control circuit 103, a switching circuit 102, and an overcurrent protection circuit 104. The input terminal of the rectifier circuit 101 is connected to the AC input terminal, and the output terminal of the rectifier circuit 101 is connected to the load. The control terminal of the switching circuit 102 is connected to the output terminal of the control circuit 103, the input terminal of the switching circuit 102 is connected to the output terminal of the rectifier circuit 101, and the output terminal of the switching circuit 102 is connected to ground. The input terminal of the overcurrent protection circuit 104 is connected to the rectifier circuit 101, and the output terminal of the overcurrent protection circuit 104 is connected to both the control circuit 103 and the switching circuit 102.

[0052] Among them, the control circuit 103 is used to output control signals;

[0053] Switching circuit 102 is used to turn on or off the connection between the output terminal and ground terminal of rectifier circuit 101 according to control signal;

[0054] The overcurrent protection circuit 104 is used to control the switching circuit 102 to disconnect the output terminal and ground terminal of the rectifier circuit 101 when the voltage change value of the electrical signal output by the rectifier circuit 101 is detected to be greater than the target voltage.

[0055] The overcurrent protection circuit 104 includes an energy storage module 1041 and a detection module 1042. One end of the energy storage module 1041 is connected to the output terminal of the rectifier circuit 101, and the other end of the energy storage module 1041 is connected to the input terminal of the detection module 1042. The output terminal of the detection module 1042 is connected to the control circuit 103 and the switching circuit 102 respectively. When the detection module 1042 detects that the voltage change value of the energy storage module 1041 is greater than the target voltage, the control switching circuit 102 disconnects the output terminal of the rectifier circuit 101 from the ground terminal.

[0056] In this embodiment, when the voltage of the electrical signal output by the rectifier circuit 101 changes abruptly, it also causes a significant change in the voltage value of the energy storage module 1041. Since the output terminal of the detection module 1042 is connected to the control circuit 103 and the switching circuit 102 respectively, when the detection module 1042 detects a significant change in the voltage value of the energy storage module 1041, it can change the voltage value of the control signal received by the switching circuit 102, affecting the on / off state of the switching circuit 102. Thus, when the detection module 1042 detects that the voltage change value of the energy storage module 1041 is greater than the target voltage, it controls the switching circuit 102 to disconnect the output terminal and ground terminal of the rectifier circuit 101. This prevents overcurrent or even damage to the devices in the switching circuit 102 caused by the control circuit 103 failing to output the control signal to disconnect the output terminal and ground terminal of the rectifier circuit 101 in time when the voltage of the electrical signal output by the rectifier circuit 101 changes abruptly.

[0057] In some embodiments, the detection module 1042 may include a differential amplifier and a comparator. The first input terminal of the differential amplifier is connected to the energy storage module 1041 through a resistor. The second input terminal of the differential amplifier is connected to a reference power supply. The output terminal of the differential amplifier is connected to the first input terminal of the comparator. The voltage of the reference power supply is the voltage threshold after rectification under normal conditions. The second input terminal of the comparator is connected to a reference power supply. The output terminal of the comparator is connected to the control circuit 103 and the switching circuit 102, respectively.

[0058] When the rectified voltage undergoes a sudden change, the charge stored in the energy storage module increases, and the output current of the energy storage module increases. After the current is converted into voltage by a resistor, the differential amplifier compares this voltage with a reference voltage. If the voltage is greater than the reference power supply voltage, a first electrical signal is output to the comparator to indicate that a sudden change has occurred in the rectified voltage, meaning the voltage change in the output signal of the rectifier circuit is greater than the target voltage. If the voltage is less than or equal to the reference power supply voltage, a second electrical signal is output to the comparator to indicate that no sudden change has occurred in the rectified voltage, meaning the voltage change in the output signal of the rectifier circuit is less than or equal to the target voltage. Upon receiving the electrical signal from the differential amplifier, the comparator compares it with a reference voltage, which is a voltage between the first and second electrical signals, and then outputs a corresponding control signal.

[0059] In some embodiments, such as Figure 4 As shown, the detection module 1042 may include a voltage detection unit 10421, a comparator 10422, and a first switching transistor 10423. The first input terminal of the comparator 10422 is connected to the energy storage module 1041, the second input terminal of the comparator 10422 is connected to the reference power supply, the output terminal of the comparator 10422 is connected to the control terminal of the first switching transistor 10423, the input terminal of the first switching transistor 10423 is connected to the control circuit 103, and the output terminal of the first switching transistor 10423 is connected to ground.

[0060] Reference power supply, used to output target voltage;

[0061] The voltage detection unit 10421 is used to detect the voltage change value of the energy storage module 1041 and output the corresponding voltage signal.

[0062] Comparator 10422 is used to control the first switch transistor 10423 to disconnect the control circuit 103 from the ground terminal when the voltage value of the voltage signal is greater than the target voltage.

[0063] In this embodiment, the voltage detection unit 10421 detects the voltage change value of the energy storage module 1041 and outputs a corresponding voltage signal to the first input terminal of the comparator 10422. The comparator 10422 then compares the voltage signal at the first input terminal with the voltage of the reference power supply at the second input terminal. If the voltage value of the voltage signal is greater than the target voltage, it outputs an electrical signal with a first voltage. After the electrical signal with the first voltage is mixed with the control signal, the first switch 10423 receives the mixed electrical signal. At this time, the first switch 10423 disconnects the control circuit 103 from the ground terminal. If the voltage value of the voltage signal is less than or equal to the target voltage, it outputs an electrical signal with a second voltage. After the electrical signal with the second voltage is mixed with the control signal, the first switch 10423 receives the mixed electrical signal. At this time, the first switch 10423 turns on the control circuit 103 and connects it to the ground terminal.

[0064] It is understandable that the voltage detection unit 10421 detects the instantaneous voltage change value of the energy storage module 1041 and outputs the corresponding voltage signal to the comparator 10422. The comparator 10422 compares the voltage value of the voltage signal with the target voltage and controls the on / off state of the first switch 10423 according to the comparison result. The overall circuit structure is simple, does not require the calculation and control of the controller, and can respond more quickly to sudden changes in the input voltage.

[0065] In some embodiments, the first switching transistor 10423 described above can be a triode.

[0066] Understandably, because the voltage output of comparator 10422 is relatively low, the first switching transistor 10423 can be set as a transistor to reduce device cost.

[0067] In some embodiments, the voltage detection unit 10421 may include a controller. The controller acquires the voltage of the energy storage module 1041 through an internal analog-to-digital converter (ADC), converts it into a digital signal, and then uses a software algorithm to calculate the difference between the current sampled value and historical sampled values ​​in real time to obtain the instantaneous voltage increment. After converting the instantaneous voltage increment into an analog voltage signal, it is output to the comparator 10422. The controller is, for example, a microcontroller (MCU) or a digital signal processor (DSP).

[0068] In some embodiments, such as Figure 5 As shown, the voltage detection unit 10421 may include a resistor, and the energy storage module 1041 includes a capacitor. The resistor and capacitor constitute an RC differentiating circuit.

[0069] In this embodiment, during normal operation, the rectified voltage is a complete sinusoidal half-wave signal. The sinusoidal half-wave signal will regularly charge and discharge the capacitor. When the input voltage changes abruptly, the charging current of the capacitor by the rectified voltage increases, raising the voltage at the first input terminal of comparator 10422. When the voltage at the first input terminal is higher than the reference voltage, comparator 10422 outputs a high level, the first switch 10423 is turned on, pulling the control signal output by the controller low, and PFC is turned off. After the rectified voltage stabilizes, the charging current of the capacitor by the rectified voltage decreases or reverses, comparator 10422 outputs a low level again, the first switch 10423 is turned off, and the control signal received by the switching circuit 102 is restored.

[0070] It is understandable that by setting a resistor and forming an RC differentiating circuit with the resistor and capacitor, the input of the RC differentiating circuit is the voltage value of the capacitor, and the output of the RC differentiating circuit is the voltage value after differentiating the voltage of the capacitor. The voltage value after differentiating the voltage of the capacitor can characterize the voltage change of the capacitor. The overall circuit structure is simple and can quickly respond to the speed of voltage change.

[0071] In some embodiments, when the values ​​of capacitors and resistors are large, the charging and discharging speed is slow, and the charging current of the capacitor is large during normal operation. When the rectified voltage suddenly changes, this step voltage is difficult to generate a voltage signal at the input of comparator 10422 that is much larger than the voltage signal during normal operation, meaning the voltage change amplitude of energy storage module 1041 is small. When the values ​​of capacitors and resistors are small, if the rectified voltage increases abnormally, the signal at the input of comparator 10422 is significantly higher than the voltage signal during normal operation, meaning the voltage change amplitude of energy storage module 1041 is large. Therefore, the values ​​of capacitors and resistors need to be as small as possible to achieve a faster charging and discharging speed and a smaller charging current.

[0072] Preferably, the values ​​of the capacitor and resistor can satisfy the following condition: when the abnormal switching voltage after rectification is sufficient to cause the current of the first switching transistor 10423 to rise to 80% of its shutdown protection current, the switching circuit 102 is triggered to disconnect.

[0073] It is understandable that the RC differentiating circuit composed of capacitors and resistors needs to respond promptly to changes in capacitor voltage. However, if the values ​​of capacitors and resistors are large, the charging and discharging speed of the capacitor is slow, and the charging current of the capacitor is large during normal operation. When the output voltage of the rectifier circuit 101 changes abruptly, this step voltage is difficult to generate a voltage signal at the input of comparator 10422 that is much larger than the voltage signal during normal operation. Therefore, setting smaller values ​​for capacitors and resistors can increase the amplitude of capacitor voltage changes, and comparator 10422 can output the detection signal that controls the first switching transistor 10423 to disconnect the control circuit 103 from the ground terminal more quickly, thereby improving the response speed of overcurrent protection.

[0074] In some embodiments, such as Figure 6 As shown, the resistor may include a first resistor R1 and a second resistor R2. One end of the first resistor R1 is connected to the other end of the capacitor, and the other end of the first resistor R1 is connected to the first input terminal of the comparator 10422. One end of the second resistor R2 is connected between the other end of the first resistor and the first input terminal of the comparator 10422, and the other end of the second resistor R2 is connected to ground.

[0075] In this embodiment, the first resistor R1 can convert the current of the capacitor into voltage, so that the comparator 10422 can compare the voltage. The second resistor R2 can divide the converted voltage to match the receiving range of the comparator 10422.

[0076] The specific values ​​of the first resistor R1 and the second resistor R2 can be set by those skilled in the art according to the actual situation, and this application embodiment does not impose any restrictions.

[0077] It is understandable that when the voltage of the capacitor changes abruptly, the change will be reflected by the current of the capacitor. The first resistor can convert the current of the capacitor into voltage, which makes it convenient for the comparator 10422 to compare the voltage. The overall circuit structure is simple and the component cost is low.

[0078] In some embodiments, the control circuit 103 may include a controller, which is connected to the input terminals of the switching circuit 102 and the first switching transistor 10423, respectively.

[0079] It is understandable that by connecting the controller to the input terminals of the switching circuit 102 and the first switching transistor 10423 respectively, the input terminal of the first switching transistor 10423 can be set between the controller and the switching circuit 102. This allows the first switching transistor 10423 to disconnect the connection between the controller and the ground terminal when the comparator 10422 outputs a detection signal representing a sudden change in the voltage of the energy storage module 1041, thereby pulling down the voltage at the drive terminal of the switching circuit 102 and improving the operational stability of the circuit.

[0080] In some embodiments, such as Figure 7 As shown, the controller is also connected to the output terminal of the rectifier circuit 101 to detect the voltage value at the output terminal of the rectifier circuit 101. When the voltage value at the output terminal of the rectifier circuit 101 is detected to be greater than a preset voltage threshold, the controller outputs a target control signal. The target control signal is used to control the switching circuit 102 to be in a first duty cycle. The first duty cycle is different from the second duty cycle. The second duty cycle is the duty cycle when the voltage value at the output terminal of the rectifier circuit 101 is less than or equal to the preset voltage threshold.

[0081] In this embodiment, the overcurrent protection circuit 104 affects the conduction state of the switching circuit 102 when the voltage at the output of the rectifier circuit 101 changes abruptly, but does not change the control signal output by the controller. Therefore, after the voltage at the output of the rectifier circuit 101 stabilizes, the conduction state of the switching circuit 102 is still controlled by the controller. Thus, the overcurrent protection circuit 104 serves as an auxiliary protection measure for the PFC circuit. By connecting the controller to the output of the rectifier circuit 101, the controller can detect the voltage value at the output of the rectifier circuit 101 in real time. When the voltage value at the output of the rectifier circuit 101 is greater than a preset voltage threshold, the controller outputs a target control signal to the switching circuit 102. The controller can change the control signal, thereby adjusting the duty cycle of the switching circuit 102 when the output voltage of the rectifier circuit 101 is stable but greater than the preset voltage threshold, further protecting the PFC circuit and improving its stability.

[0082] The second duty cycle is the duty cycle of the switching circuit 102 when the AC input voltage is within the normal range. The AC input voltage is within the normal range, meaning that the voltage value at the output terminal of the rectifier circuit 101 is less than or equal to a preset voltage threshold.

[0083] It is understandable that the controller is also connected to the output terminal of the rectifier circuit 101. When the controller detects that the voltage value at the output terminal of the rectifier circuit 101 is greater than the preset voltage threshold, the controller can change the control signal to protect the PFC circuit and improve stability.

[0084] In some embodiments, such as Figure 8 As shown, the switching circuit 102 may include a second switching transistor and a driving circuit. The input terminal of the driving circuit is connected to the control circuit 103 and the first switching transistor 10423, respectively. The output terminal of the driving circuit is connected to the driving terminal of the second switching transistor. The input terminal of the second switching transistor is connected to the output terminal of the rectifier circuit 101. The output terminal of the second switching transistor is connected to ground.

[0085] It is understandable that since the second switching transistor used in the PFC circuit is usually a high-power switching device, and the voltage value of the control circuit 103 does not match the driving voltage value of the high-power switching device, a driving circuit needs to be set between the controller and the second switching transistor. The driving circuit converts the control signal output by the control circuit 103 into a driving voltage that matches the second switching transistor, thereby stabilizing the driving of the second switching transistor.

[0086] This application also provides an electronic device including a PFC circuit as described in any of the above embodiments.

[0087] It should be understood that the phrases "one embodiment," "an embodiment," or "some embodiments" mentioned throughout the specification mean that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment," "in one embodiment," or "in some embodiments" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above-described embodiments are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments. The descriptions of the various embodiments above tend to emphasize the differences between the various embodiments; their similarities or commonalities can be referred to mutually, and for the sake of brevity, they will not be repeated here.

[0088] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0089] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0090] The modules described above as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules. They may be located in one place or distributed across multiple network terminals. Some or all of the modules may be selected to achieve the purpose of this embodiment according to actual needs.

[0091] In addition, each functional module in the various embodiments of this application can be fully integrated into one processing terminal, or each module can be a separate terminal, or two or more modules can be integrated into one terminal; the integrated modules can be implemented in hardware or in the form of hardware plus software functional terminals.

[0092] The features disclosed in the several product embodiments provided in this application can be arbitrarily combined without conflict to obtain new product embodiments.

[0093] The above description is merely an embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A PFC circuit, characterized in that, The PFC circuit includes: A rectifier circuit, wherein the input terminal of the rectifier circuit is connected to an AC input terminal, and the output terminal of the rectifier circuit is connected to a load; Control circuit, used to output control signals; A switching circuit, wherein the control terminal of the switching circuit is connected to the output terminal of the control circuit, the input terminal of the switching circuit is connected to the output terminal of the rectifier circuit, and the output terminal of the switching circuit is connected to ground. The switching circuit is used to turn on or off the connection between the output terminal of the rectifier circuit and the ground terminal according to the control signal. An overcurrent protection circuit is provided, wherein the input terminal of the overcurrent protection circuit is connected to the rectifier circuit, and the output terminal of the overcurrent protection circuit is connected to the control circuit and the switching circuit respectively. The overcurrent protection circuit is used to control the switching circuit to disconnect the output terminal of the rectifier circuit from the ground terminal when the voltage change value of the electrical signal output by the rectifier circuit is detected to be greater than the target voltage. The overcurrent protection circuit includes an energy storage module and a detection module. One end of the energy storage module is connected to the output terminal of the rectifier circuit, and the other end of the energy storage module is connected to the input terminal of the detection module. The output terminal of the detection module is connected to the control circuit and the switching circuit respectively. When the detection module detects that the voltage change value of the energy storage module is greater than the target voltage, it controls the switching circuit to disconnect the output terminal of the rectifier circuit from the ground terminal.

2. The PFC circuit as described in claim 1, characterized in that, The detection module includes a voltage detection unit, a comparator, and a first switching transistor. The first input terminal of the comparator is connected to the energy storage module, the second input terminal of the comparator is connected to a reference power supply, the output terminal of the comparator is connected to the control terminal of the first switching transistor, the input terminal of the first switching transistor is connected to the control circuit, and the output terminal of the first switching transistor is connected to ground. The reference power supply is used to output the target voltage; The voltage detection unit is used to detect the voltage change value of the energy storage module and output the corresponding voltage signal; The comparator is used to control the first switch to disconnect the control circuit and the ground terminal when the voltage value of the voltage signal is greater than the target voltage.

3. The PFC circuit as described in claim 2, characterized in that, The voltage detection unit includes a resistor, and the energy storage module includes a capacitor. The resistor and the capacitor together form an RC differentiating circuit.

4. The PFC circuit as described in claim 3, characterized in that, The resistor includes a first resistor and a second resistor. One end of the first resistor is connected to the other end of the capacitor, and the other end of the first resistor is connected to the first input terminal of the comparator. One end of the second resistor is connected between the other end of the first resistor and the first input terminal of the comparator, and the other end of the second resistor is connected to ground.

5. The PFC circuit as described in claim 2, characterized in that, The control circuit includes a controller, which is connected to the input terminals of the switching circuit and the first switching transistor, respectively.

6. The PFC circuit as described in claim 5, characterized in that, The controller is also connected to the output terminal of the rectifier circuit to detect the voltage value at the output terminal of the rectifier circuit. When the voltage value at the output terminal of the rectifier circuit is detected to be greater than a preset voltage threshold, the controller outputs a target control signal. The target control signal is used to control the switching circuit to be in a first duty cycle. The first duty cycle is different from the second duty cycle, which is the duty cycle when the voltage value at the output terminal of the rectifier circuit is less than or equal to the preset voltage threshold.

7. The PFC circuit as described in claim 2, characterized in that, The switching circuit includes a second switching transistor and a driving circuit. The input terminal of the driving circuit is connected to the control circuit and the first switching transistor, respectively. The output terminal of the driving circuit is connected to the driving terminal of the second switching transistor. The input terminal of the second switching transistor is connected to the output terminal of the rectifier circuit. The output terminal of the second switching transistor is connected to ground.

8. The PFC circuit as described in claim 2, characterized in that, The first switching transistor is a triode.

9. The PFC circuit as described in claim 3, characterized in that, When the voltage at the output terminal of the rectifier circuit increases abnormally, the smaller the values ​​of the capacitor and resistor, the greater the voltage change of the energy storage module.

10. An electronic device, characterized in that, The electronic device includes the PFC circuit as described in any one of claims 1-9.

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