Control circuit and power device

Abstract

The utility model provides a kind of control circuit and electric power equipment.Control circuit includes field effect tube, detection unit and control unit.Detection unit is connected with the drain of field effect tube, and detection unit is configured to can obtain the drain voltage of field effect tube, and according to drain voltage output fault signal.Control unit is connected with the grid of field effect tube, and control unit is configured to receive control signal and drive field effect tube.Detection unit and control unit are connected, and control unit is configured to receive fault signal and change the grid voltage of field effect tube according to fault signal.The embodiment of the utility model is favorable to reduce the energy consumption of field effect tube, and reduce the damage risk when short-circuit fault of field effect tube occurs, improve the stability of control circuit.

Description

Technical Field

[0001] This utility model relates to the field of field-effect transistor circuit technology, and in particular to a control circuit and power equipment. Background Technology

[0002] Field-effect transistors (FETs) are crucial components in circuit design, widely used in power equipment such as inverters, uninterruptible power supplies (UPS), and switch-mode power supplies (SMPS). In circuit design, FETs exhibit lower switching and conduction losses at higher gate voltages; therefore, to reduce energy consumption, it's necessary to appropriately increase the gate voltage of FETs. However, at the same time, higher gate voltages reduce the FET's short-circuit withstand capability, making it prone to burnout within a short time, thus compromising its stability. For example, when the gate voltage of a silicon carbide (SiC) FET is 15V, the short-circuit response time is approximately 3 microseconds; when the gate voltage is increased to 18V, the allowable short-circuit response time decreases to approximately 1 microsecond.

[0003] Therefore, in the design of field-effect transistor circuits, it is difficult to simultaneously reduce energy consumption and improve short-circuit withstand capability.

[0004] The content of the background section is merely the technology known to the inventor and does not necessarily represent the prior art in this field. Utility Model Content

[0005] To address one or more deficiencies in the prior art, this utility model provides a control circuit, comprising: Field-effect transistor; A detection unit is connected to the drain of the field-effect transistor (FET), and the detection unit is configured to acquire the drain voltage of the FET and output a fault signal based on the drain voltage. A control unit, connected to the gate of the field-effect transistor, is configured to receive a control signal and drive the field-effect transistor; The detection unit and the control unit are connected, and the control unit is configured to receive the fault signal and change the gate voltage of the field-effect transistor according to the fault signal.

[0006] According to one aspect of the present invention, the control circuit further includes: A first power supply is connected to the control unit and supplies power to the gate of the field-effect transistor through the control unit.

[0007] According to one aspect of the present invention, the detection unit includes a saturation voltage drop detection unit, which receives the drain voltage and outputs a first fault signal based on the drain voltage; the control unit responds to the first fault signal and disconnects from the field-effect transistor, or disconnects from the first power supply, or reduces the gate voltage of the field-effect transistor.

[0008] According to one aspect of the present invention, the saturation voltage drop detection unit includes a first comparator, which receives a detection voltage and compares it with a first preset voltage; when the detection voltage is greater than the first preset voltage, the first comparator outputs a first fault signal; the detection voltage is determined based on the drain voltage.

[0009] According to one aspect of the present invention, the saturation pressure drop detection unit further includes: A desaturation detection capacitor is connected to the comparator and the drain of the field-effect transistor, and is configured to receive the drain voltage of the field-effect transistor and output the detection voltage to the first comparator; A power supply is provided, which is connected to the desaturation detection capacitor and charges the desaturation detection capacitor.

[0010] According to one aspect of the present invention, the saturation pressure drop detection unit further includes: An isolation element is disposed between the desaturation detection capacitor and the drain of the field-effect transistor.

[0011] According to one aspect of the present invention, the isolation element includes a diode, the cathode of which is connected to the drain of the field-effect transistor, and the anode of which is connected to the desaturation detection capacitor; the voltage drop of the diode is preset.

[0012] According to one aspect of this utility model, the power supply is a constant current source; the charging time of the desaturation detection capacitor is preset.

[0013] According to one aspect of the present invention, the control circuit further includes: A second power supply is connected to the gate of the field-effect transistor, and the output voltage of the second power supply is less than the output voltage of the first power supply.

[0014] According to one aspect of the present invention, the detection unit further includes a drive voltage adjustment unit, which receives a detection voltage and outputs a second fault signal based on the detection voltage; the control unit responds to the second fault signal and controls the second power supply to supply power to the gate of the field-effect transistor; the detection voltage is determined based on the drain voltage.

[0015] According to one aspect of the present invention, the drive voltage adjustment unit includes a second comparator, which receives a detected voltage and compares it with a second preset voltage; when the detected voltage is greater than the second preset voltage, the second comparator outputs a second fault signal.

[0016] According to one aspect of the present invention, the present invention also includes an electrical device, the electrical device comprising: The control circuit as described above.

[0017] Compared with existing technologies, the embodiments of this utility model provide a control circuit, including a detection unit and a control unit. The detection unit can detect the drain voltage of the field-effect transistor (FET) and output a fault signal. The control unit adjusts the gate voltage of the FET according to the fault signal. During normal operation of the FET, a higher gate voltage can be maintained, which helps reduce the FET's power consumption. When a short circuit or overcurrent occurs in the FET, the control unit lowers the gate voltage, which helps reduce the risk of damage to the FET during short-circuit faults and improves the stability of the control circuit.

[0018] Embodiments of this utility model also include an electrical device that uses the control circuit described above. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the following description of the embodiments will be introduced as examples. The drawings described below are merely embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. The drawings are used to provide a further understanding of this utility model and constitute a part of the specification. They are used together with the embodiments of this utility model to explain this utility model and do not constitute a limitation on this utility model. In the drawings: Figure 1 This is a block diagram of the control circuit in some embodiments of this utility model; Figure 2 This is a block diagram of the detection unit and control unit in some embodiments of this utility model; Figure 3 This is a circuit diagram of the control circuit in some embodiments of this utility model; Figure 4A This is a simulation diagram of a field-effect transistor with a low short-circuit impedance in the existing technology; Figure 4B These are simulation diagrams of the field-effect transistor with low short-circuit impedance in some embodiments of this utility model; Figure 5A This is a simulation diagram of a field-effect transistor with a high short-circuit impedance in the existing technology; Figure 5B These are simulation diagrams of the field-effect transistor with high short-circuit impedance in some embodiments of this utility model; Figure 6 These are simulation diagrams of the instantaneous high current response in some embodiments of this utility model; Figure 7 This is a block diagram of the power equipment in some embodiments of this utility model. Detailed Implementation

[0020] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this invention. Therefore, the drawings and description are considered exemplary in nature and not restrictive.

[0021] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "multiple" means two or more, unless otherwise explicitly specified.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "coupling" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] The following provides many different embodiments or examples for implementing various structures of this invention. To simplify the invention, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0025] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0026] Figure 1 A schematic diagram of an exemplary control circuit 100 consistent with some embodiments of the present invention is shown. See also Figure 1 The control circuit 100 includes a field-effect transistor 110, a detection unit 120, and a control unit 130.

[0027] The detection unit 120 is connected to the drain of the field-effect transistor 110. The detection unit 120 can acquire the drain voltage of the field-effect transistor 110 and output a corresponding fault signal based on the drain voltage of the field-effect transistor 110.

[0028] The control unit 130 and the gate of the field-effect transistor 110 are connected. In some embodiments, the control unit 130 is connected to a power supply, or the control unit 130 has a built-in power supply that supplies power to the gate of the field-effect transistor 110. In some embodiments, the control unit 130 can drive the field-effect transistor 110 at a higher voltage, which helps to reduce the power consumption of the field-effect transistor 110.

[0029] In some embodiments, the control unit 130 may be connected to a signal source to receive control signals from the field-effect transistor 110, and control and drive the field-effect transistor 110 according to the control signals.

[0030] See Figure 1 The control unit 130 is connected to the detection unit 120. The control unit 130 can receive the fault signal output by the detection unit 120, and the control unit 130 can change the gate voltage of the field-effect transistor 110 according to the fault signal.

[0031] Specifically, when the field-effect transistor 110 is operating normally, the detection unit 120 acquires the drain voltage of the field-effect transistor 110 and uses a fault signal to enable the control unit 130 to control the field-effect transistor 110 normally, maintaining a high gate voltage for the field-effect transistor 110. When the field-effect transistor 110 experiences a short circuit or overcurrent, the drain voltage of the field-effect transistor 110 will abnormally increase. The detection unit 120 acquires the drain voltage of the field-effect transistor 110 and, in response to the increase in the drain voltage of the field-effect transistor 110, outputs a corresponding fault signal. The control unit 130 receives the fault signal and, according to the control, changes the gate voltage of the field-effect transistor 110, for example, by disconnecting or reducing the gate voltage of the field-effect transistor 110, to protect the field-effect transistor 110 and reduce the risk of the field-effect transistor 110 and the control circuit 100 being burned out in the event of a short circuit or overcurrent.

[0032] In this embodiment, the control circuit 100 can maintain a high gate voltage for the field-effect transistor 110 during normal operation, thereby reducing the power consumption of the field-effect transistor 110. Furthermore, in the event of a short circuit or overcurrent in the field-effect transistor 110, the control unit 130 can detect the drain voltage and change the gate voltage of the field-effect transistor 110 to reduce the risk to the field-effect transistor 110 and improve the safety and stability of the control circuit 100.

[0033] Figure 2 A block diagram showing the interaction between an exemplary detection unit 120 and a control unit 130, consistent with some embodiments of the present invention.

[0034] See Figure 2 According to some preferred embodiments of the present invention, the control circuit 100 further includes a first power supply 140. The first power supply 140 is connected to the control unit 130, and the first power supply 140 supplies power to the gate of the field-effect transistor 110 through the control unit 130. In some embodiments, the first power supply 140 can provide a higher gate voltage to the field-effect transistor 110, which is beneficial to reducing the power consumption of the field-effect transistor 110.

[0035] join Figure 2In some embodiments, the detection unit 120 includes a saturation voltage drop detection unit 121. The saturation voltage drop detection unit 121 can receive the drain voltage of the field-effect transistor 110 and output a first fault signal based on the drain voltage. The control unit 130 receives and responds to the first fault signal by disconnecting from the field-effect transistor 110 or disconnecting from the first power supply 140. Alternatively, in some embodiments, the control unit 130, in response to the first fault signal, reduces the gate voltage of the field-effect transistor 110. For example, in some embodiments, the control unit 130, in response to the first fault signal, blocks the connection between the control unit 130 and the signal source, isolating the control signal.

[0036] Figure 3 A circuit diagram of an exemplary control circuit 100 consistent with some embodiments of the present invention is shown.

[0037] See Figure 3 In some embodiments, the voltage drop detection unit 121 includes a first comparator 122. The first comparator 122 can receive a detected voltage and compare the detected voltage with a first preset voltage. When the detected voltage is greater than the first preset voltage, the first comparator 122 outputs a first fault signal. The control unit 130 is connected to the first comparator 122 and, in response to the first fault signal, disconnects from the field-effect transistor 110 or disconnects from the first power supply 140. Alternatively, in some embodiments, the control unit 130, in response to the first fault signal, reduces the gate voltage 111 of the field-effect transistor 110.

[0038] The detection voltage can be obtained by processing the drain voltage 112 of the field-effect transistor 110 obtained through direct detection, which helps to reduce misjudgments by the detection unit 120 caused by unstable current changes in the field-effect transistor 110. In some embodiments, the detection voltage can be implemented through circuit design, which will be described in detail in subsequent embodiments.

[0039] In some embodiments, the first comparator 122 may be connected to a power supply that provides a fixed voltage output, which supplies a first preset voltage to the first comparator 122. The first comparator 122 compares the detected voltage and the first preset voltage, and outputs a first fault signal based on the magnitude relationship between the detected voltage and the first preset voltage. When the detected voltage is greater than the first preset voltage, the first comparator 122 outputs the first fault signal. The control unit 130 receives and responds to the first fault signal by disconnecting the connection with the field-effect transistor 110 or the first power supply 140, or by reducing the voltage of the gate 111 of the field-effect transistor 110.

[0040] See Figure 2 and Figure 3In some embodiments, the control circuit 100 further includes a second power supply 150. The second power supply 150 is connected to the gate 111 of the field-effect transistor 110, and the output voltage of the second power supply 150 is less than the output voltage of the first power supply 140. Specifically, in some embodiments, the output voltage of the first power supply 140 is, for example, 18V, and the output voltage of the second power supply 150 is, for example, 15V.

[0041] In some embodiments, the control unit 130 can control the first power supply 140 and the second power supply 150 to supply power to the gate 111 of the field-effect transistor 110. Preferably, when the second power supply 150 supplies power to the gate 111 of the field-effect transistor 110, the field-effect transistor 110 has no risk of overheating or a low risk of overheating. When a short circuit or overcurrent occurs, the control unit 130 can respond to the fault signal output by the detection unit 120 and control the second power supply 150 to supply power to the gate 111 of the field-effect transistor 110 to ensure the safety of the field-effect transistor 110.

[0042] See Figure 3 In some embodiments, the saturation voltage drop detection unit 121 further includes a desaturation detection capacitor 123 and a power supply 124.

[0043] The desaturation detection capacitor 123 is connected to the first comparator 122 and the drain 112 of the field-effect transistor 110. The desaturation detection capacitor 123 can receive the drain voltage of the field-effect transistor 110 and output a detection voltage to the first comparator 122.

[0044] The power supply 124 is connected to the desaturation detection capacitor 123 and charges the desaturation detection capacitor 123. In a preferred embodiment of this invention, the power supply 124 is a constant current source, such as using a Zener diode or a reference voltage source. The power supply 124 charges the desaturation detection capacitor 123 with a constant current, and the desaturation detection capacitor 123 charges at a fixed rate within a certain time range. The voltage of the desaturation detection capacitor 123 (which can be used as the detection voltage) increases linearly, which helps to maintain the stability of the detection voltage. In some embodiments, the charging time of the desaturation detection capacitor 123 (i.e., the time parameter of the capacitor) is preset.

[0045] In a preferred embodiment of this invention, the desaturation detection capacitor 123 and the power supply 124 cooperate to output a detection voltage to the first comparator 122, which can reduce the risk of false triggering of the first comparator 122. For example, when the field-effect transistor 110 experiences a momentary excessive current, the voltage of the drain 112 of the field-effect transistor 110 will not be directly received by the first comparator 122, and a first fault signal will be output, thus avoiding false triggering. In some embodiments, the detection voltage can be the voltage of the desaturation detection capacitor 123. When the voltage of the drain 112 of the field-effect transistor 110 increases, the desaturation detection capacitor 123 continues to be charged by the power supply 124, and the voltage of the desaturation detection capacitor 123 increases approximately linearly. When the voltage of the desaturation detection capacitor 123 is greater than a first preset voltage, the first comparator 122 outputs a first fault signal. In response to the first fault signal, the control unit 130 disconnects the connection with the field-effect transistor 110 or the first power supply 140, or the control unit 130 reduces the voltage of the gate 111 of the field-effect transistor 110.

[0046] See Figure 3 According to a preferred embodiment of the present invention, the saturation voltage drop detection unit 121 further includes an isolation element 125. The isolation element 125 is disposed between the desaturation detection capacitor 123 and the drain 112 of the field-effect transistor 110. The isolation element 125 can prevent the voltage at the drain 112 of the field-effect transistor 110 from being directly transmitted to the first comparator 122, which could cause the first comparator 122 to erroneously trigger, issuing a first fault signal and affecting the normal operation of the control circuit 100. The isolation element 125 can isolate high voltage when the field-effect transistor 110 is working normally, and allow high voltage signals to pass through when the field-effect transistor 110 malfunctions.

[0047] Specifically, in a preferred embodiment of this invention, the isolation element 125 includes a diode. See also Figure 3 The cathode of the diode is connected to the drain 112 of the field-effect transistor 110, and the anode of the diode is connected to the desaturation detection capacitor 123. Furthermore, the diode's voltage drop is preset.

[0048] When the field-effect transistor 110 is driven by the control signal and is normally turned on, it is in the saturation region, and the voltage between the drain 112 and the source (drain voltage) is low, typically 2-5V. The cathode of the diode is connected to the drain of the field-effect transistor 110, and the anode of the diode is charged to a higher voltage, such as close to the voltage of the first power supply 140, through the power supply 124. The cathode voltage of the diode is much lower than the anode voltage; therefore, the diode is in a reverse bias state, equivalent to being disconnected, preventing voltage fluctuations at the drain 112 of the field-effect transistor 110 from being directly transmitted to the first comparator 122, thus reducing interference from fluctuating signals. Simultaneously, keeping the diode in the disconnected state also protects the desaturation detection capacitor 123 and the first comparator 122, which operate in a low-voltage environment, preventing damage from high-voltage signals. In this embodiment, when the field-effect transistor 110 is driven by the control signal and is normally turned on, the detection voltage is determined by the charging of the desaturation detection capacitor 123 by the power supply 124.

[0049] When a short circuit or overcurrent fault occurs in the field-effect transistor 110, the MOSFET exits the saturation region and enters the linear region. The drain voltage 112 of the MOSFET 110 rises rapidly. When the cathode voltage (drain voltage) of the diode exceeds the anode voltage (first power supply 140 - diode forward voltage drop), the diode switches to forward bias, and the drain 112 of the MOSFET 110 and the desaturation detection capacitor 123 conduct. The voltage of the desaturation detection capacitor 123 rises, and the detection voltage output to the first comparator 122 rises. When the detection voltage exceeds the first preset voltage, the first comparator 122 outputs a first fault signal. In response to the first fault signal, the control unit 130 disconnects the gate voltage 111 of the MOSFET 110, protecting the MOSFET 110 from overheating damage.

[0050] See Figure 2 According to a preferred embodiment of the present invention, the detection unit 120 further includes a drive voltage adjustment unit 126. The drive voltage adjustment unit 126 can receive a detection voltage and output a second fault signal based on the detection voltage. In response to the second fault signal, the control unit 130 controls the second power supply 150 to supply power to the gate of the field-effect transistor 110. The detection voltage is determined based on the drain voltage of the field-effect transistor 110. In some embodiments, the detection voltage received by the drive voltage adjustment unit 126 may be the same as the detection voltage determined by the saturation voltage drop detection unit 121 in the aforementioned embodiments. Specifically, the drive voltage adjustment unit 126 may be connected to the desaturation detection capacitor 123 in the aforementioned embodiments and receive the voltage of the desaturation detection capacitor 123.

[0051] See Figure 3In some embodiments, the control unit 130 includes a first switch 131. The first switch 131 is disposed between the second power supply 150 and the gate 111 of the field-effect transistor 110, and the first switch 131 is connected to the drive voltage adjustment unit 126. The first switch 131 can respond to a second fault signal to control the second power supply 150 to supply power to the field-effect transistor 110.

[0052] See Figure 3 In a preferred embodiment of this invention, the drive voltage adjustment unit 126 includes a second comparator 127. The second comparator 127 can receive a detected voltage and output a second fault signal accordingly. For example, in some embodiments, the second comparator 127 receives the detected voltage and compares the detected voltage with a second preset voltage. When the detected voltage is greater than the second preset voltage, the second comparator 127 outputs a second fault signal. The control unit 130 responds to the second fault signal, for example, the first switch 131 responds to the second fault signal, and controls the second power supply 150 to supply power to the gate 111 of the field-effect transistor 110. Preferably, the first switch 131 is configured to be reversible; for example, when the detected voltage is greater than the second preset voltage, the first switch 131 controls the second power supply 150 to supply power to the gate 111 of the field-effect transistor 110. When the detected voltage drops to a level not greater than the second preset voltage, the first switch 131 disconnects the second power supply 150 from the gate 111 of the field-effect transistor 110, and power can be supplied to the gate 111 of the field-effect transistor 110 through the first power supply 140.

[0053] Preferably, the desaturation detection capacitor 123 is connected to the second comparator 127. The second comparator 127 can output a second fault signal based on the voltage of the desaturation detection capacitor 123.

[0054] In some embodiments, the detection unit 120 may include a comparator that receives a detection voltage, compares the detection voltage with a first preset voltage and a second preset voltage, and outputs a first fault signal and a second fault signal. In some embodiments, the first preset voltage and the second preset voltage may be equal or unequal. Preferably, the first preset voltage is greater than the second preset voltage. In some embodiments, the first preset voltage and the second preset voltage are equal, and the comparator may be connected to a power supply that outputs a constant voltage (i.e., the first preset voltage and the second preset voltage).

[0055] Figure 4A and Figure 4B Simulation diagrams of existing technologies and embodiments of the present invention are shown when the short-circuit impedance of a field-effect transistor is low. Figure 4A and Figure 4B In the middle, the horizontal axis represents time.

[0056] In existing technologies, when a field-effect transistor (FET) is driven with a relatively high voltage (e.g., 18V), if a low-impedance short circuit occurs in the FET, such as due to cable sheath damage or component breakdown, the current forms a loop through the low-impedance path. (See [link to relevant documentation]). Figure 4A The gate voltage, drain voltage, and short-circuit current of a field-effect transistor remain constant over a long period of time (e.g., Figure 4A If the voltage level (1.5 microseconds as shown) remains high, the MOSFET may overheat and burn out. See also Figure 4B In some embodiments of this utility model, a higher voltage is used to drive the field-effect transistor. When a low-impedance short circuit occurs in the field-effect transistor, the gate voltage of the field-effect transistor is reduced in a short time by the detection unit and the control unit. For example, at time T1, the gate voltage of the field-effect transistor is reduced from 18V to 13V. At this time, the value of the detected voltage is greater than the second preset voltage. Correspondingly, the short-circuit current is significantly reduced, which helps to reduce the risk of the field-effect transistor being damaged by overheating due to short-circuit fault.

[0057] Figure 5A and Figure 5B Simulation diagrams of existing technologies and embodiments of the present invention are shown when the short-circuit impedance of a field-effect transistor is high. Figure 5A and Figure 5B In the middle, the horizontal axis represents time.

[0058] In existing technologies, when a field-effect transistor (FET) is driven with a relatively high voltage (e.g., 18V), a high-impedance short circuit can occur, such as due to cable corrosion or oxidation, aging or damage to the insulation material, leading to increased resistance, or loose connections causing poor contact. See also... Figure 5A When the gate voltage of a field-effect transistor (FET) remains high, the short-circuit current increases approximately linearly, and the drain voltage increases after decreasing. In the event of a high-impedance short circuit, the protection circuit's response is slow, potentially increasing the safety risks associated with the FET. See also... Figure 5B In an embodiment of this invention, when the detection voltage rises and exceeds a threshold (the detection voltage is greater than a second preset voltage) at time T1, the gate voltage of the field-effect transistor is reduced (e.g., by supplying power to the field-effect transistor through a second power supply). The short-circuit current is effectively limited, which helps reduce the heat generated by the short circuit. At the same time, a lower gate voltage helps the field-effect transistor enter the saturation region quickly, which is beneficial for the safe shutdown of the field-effect transistor.

[0059] according to Figures 4A-5B As can be seen, the technical solution of this utility model can drive the field-effect transistor with a higher voltage, thereby reducing the power of the control circuit. Furthermore, it can respond quickly in the event of a short circuit, reducing the gate voltage of the field-effect transistor, lowering the safety risk of the field-effect transistor, and improving the safety performance of the control circuit.

[0060] Figure 6Simulation diagrams of the instantaneous high current response in some embodiments of this invention are shown. See also Figure 6 When the current increases instantaneously, the detection voltage rises. When the detection voltage exceeds the second preset voltage, the control unit controls the second power supply to supply power to the field-effect transistor, and the gate voltage of the field-effect transistor decreases. Figure 6 The T1 position shown in the diagram). When the instantaneous large current disappears ( Figure 6 After the T2 position shown in the diagram is reached, the detection voltage drops accordingly. The first switch in the control unit disconnects the second power supply and the field-effect transistor, and the first power supply supplies power to the field-effect transistor. The gate voltage of the field-effect transistor recovers to a higher voltage. Figure 6 (as shown in the T3 position) to allow the MOSFET to operate with lower power consumption. Figure 6 It is understood that the embodiments of this utility model can cope with instantaneous large currents, which is beneficial to improving the stability of the control circuit and reducing the risk of false triggering of the control field-effect transistor turn-off.

[0061] like Figure 7 As shown, an embodiment of this utility model also includes a power device 10. See also Figure 7 The power equipment 10 includes the control circuit 100 as shown in the foregoing embodiments. Specifically, the power equipment 10 may be, for example, an inverter, an uninterruptible power supply (UPS), or a switch-mode power supply (SMPS). In some embodiments, the power equipment 10 may include one or more control circuits as described in the foregoing embodiments.

[0062] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A control circuit, characterized in that, include: Field-effect transistor; A detection unit is connected to the drain of the field-effect transistor (FET), and the detection unit is configured to acquire the drain voltage of the FET and output a fault signal based on the drain voltage. A control unit, connected to the gate of the field-effect transistor, is configured to receive a control signal and drive the field-effect transistor; The detection unit and the control unit are connected, and the control unit is configured to receive the fault signal and change the gate voltage of the field-effect transistor according to the fault signal.

2. The control circuit according to claim 1, characterized in that, Also includes: A first power supply is connected to the control unit and supplies power to the gate of the field-effect transistor through the control unit.

3. The control circuit according to claim 2, characterized in that, The detection unit includes a saturation voltage drop detection unit, which receives the drain voltage and outputs a first fault signal based on the drain voltage. The control unit responds to the first fault signal by disconnecting the connection with the field-effect transistor, or disconnecting the connection with the first power supply, or reducing the gate voltage of the field-effect transistor.

4. The control circuit according to claim 3, characterized in that, The saturation voltage drop detection unit includes a first comparator, which receives a detection voltage and compares it with a first preset voltage; when the detection voltage is greater than the first preset voltage, the first comparator outputs a first fault signal; the detection voltage is determined based on the drain voltage.

5. The control circuit according to claim 4, characterized in that, The saturation pressure drop detection unit further includes: A desaturation detection capacitor is connected to the first comparator and the drain of the field-effect transistor, and is configured to receive the drain voltage of the field-effect transistor and output the detection voltage to the first comparator. A power supply is provided, which is connected to the desaturation detection capacitor and charges the desaturation detection capacitor.

6. The control circuit according to claim 5, characterized in that, The saturation pressure drop detection unit further includes: An isolation element is disposed between the desaturation detection capacitor and the drain of the field-effect transistor.

7. The control circuit according to claim 6, characterized in that, The isolation element includes a diode, the cathode of which is connected to the drain of the field-effect transistor, and the anode of which is connected to the desaturation detection capacitor; the voltage drop of the diode is preset.

8. The control circuit according to claim 5, characterized in that, The power supply is a constant current source; the charging time of the desaturation detection capacitor is preset.

9. The control circuit according to claim 3, characterized in that, Also includes: A second power supply is connected to the gate of the field-effect transistor, and the output voltage of the second power supply is less than the output voltage of the first power supply.

10. The control circuit according to claim 9, characterized in that, The detection unit further includes a drive voltage adjustment unit, which receives the detection voltage and outputs a second fault signal based on the detection voltage; the control unit responds to the second fault signal and controls the second power supply to supply power to the gate of the field-effect transistor; the detection voltage is determined based on the drain voltage.

11. The control circuit according to claim 10, characterized in that, The drive voltage adjustment unit includes a second comparator, which receives a detected voltage and compares it with a second preset voltage; when the detected voltage is greater than the second preset voltage, the second comparator outputs a second fault signal.

12. An electrical device, characterized in that, include: The control circuit as described in any one of claims 1-11.

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