Pre-charging circuit based on working characteristics of power device

Abstract

The utility model discloses a pre-charging circuit based on working characteristics of a power device, relating to the technical field of pre-charging circuits, the pre-charging circuit is connected with a capacitor module in a power supply circuit, the pre-charging circuit comprises a pre-charging module, a sampling module and a control module, the sampling module and the control module are both connected with the pre-charging module, the pre-charging module at least comprises an MOSFET tube Q2, and the sampling module is used for collecting source current of the MOSFET tube Q2 and generating sampling voltage; and the control module is used for controlling the MOSFET Q2 to work in a variable resistance region according to the sampling voltage. Based on the variable resistance characteristic shown when the MOSFET works in the variable resistance area, the MOSFET Q2 is controlled to work in the variable resistance area through the control module, the MOSFET Q2 is used for replacing a pre-charging resistor in a traditional pre-charging circuit to complete pre-charging work, and the problems that the traditional pre-charging circuit is large in size and high in device cost are solved.

Description

Technical Field

[0001] This utility model relates to the field of pre-charging circuit technology, and in particular to a pre-charging circuit based on the operating characteristics of power devices. Background Technology

[0002] A pre-charge circuit is a circuit used in circuit design to ensure that the circuit reaches a stable state before startup or operation. It is mainly used in the start-up process of capacitor / battery charging and is widely used in new energy battery charging and on-board charging. It is an indispensable circuit component in the charging system.

[0003] Traditional pre-charging circuits, such as Figure 1 As shown, this circuit utilizes a pre-charging resistor (cement casing resistor R1) connected in parallel with a MOSFET device (Q2) or relay that acts as a switch to achieve the pre-charging function. Specifically, before supplying power to the load, the pre-charging resistor R1 pre-charges capacitors C4 and C5 to avoid excessive inrush current at power-on. However, due to the large size and high cost of the pre-charging resistor, this traditional pre-charging circuit suffers from problems of large circuit size and high device cost. Utility Model Content

[0004] In response to the above-mentioned problems and technical requirements, the inventors have proposed a pre-charging circuit based on the operating characteristics of power devices.

[0005] The technical solution of this utility model is as follows:

[0006] A pre-charging circuit based on the operating characteristics of power devices, connected to a capacitor module in a power supply circuit, includes a pre-charging module, a sampling module, and a control module. The sampling module and the control module are both connected to the pre-charging module.

[0007] The precharge module includes at least a MOSFET Q2, the sampling module is used to acquire the source current of the MOSFET Q2 and generate a sampling voltage, and the control module is used to control the MOSFET Q2 to operate in the variable resistance region according to the sampling voltage.

[0008] A further technical solution is that the capacitor module includes capacitor C4 and capacitor C5, and the sampling module includes resistor R2;

[0009] The MOSFET Q2 is an NMOS transistor. One end of the capacitor C4 is connected to the drain of the MOSFET Q2. The source of the MOSFET Q2 is grounded through the resistor R2. The other end of the capacitor C4 is connected to the load. The capacitor C5 is connected in parallel with the capacitor C4.

[0010] Further, the control module comprises a voltage comparator U1, a controller, a switch tube Q3, a resistor R4, a resistor R5, a resistor R6 and a capacitor C6, wherein,

[0011] The first output end of the controller is connected with the second electrode of the switch tube Q3, the second electrode of the switch tube Q3 is connected with the power supply voltage VCC, the first electrode of the switch tube Q3 is connected with one end of the resistor R6 and the non-inverting input end of the voltage comparator U1 through the resistor R5, the other end of the resistor R6 is grounded, and the capacitor C6 is connected with the resistor R6 in parallel.

[0012] The inverting input end of the voltage comparator U1 is connected with one end of the resistor R2 and the source electrode of the MOSFET tube Q2, the output end of the voltage comparator U1 is connected with the gate electrode of the MOSFET tube Q2 through the resistor R4, the power supply end of the voltage comparator U1 is connected with the power supply voltage VCC, and the grounding end of the voltage comparator U1 is grounded.

[0013] Further, the power supply circuit comprises a switch tube Q1, a diode D1 and a resistor R3, the first electrode of the switch tube Q1 is grounded, the second electrode of the switch tube Q1 is connected with the second output end of the controller through the resistor R3, the third electrode of the switch tube Q1 is connected with the anode of the diode D1, and one end of the capacitor C4 and the capacitor C5 is connected with the cathode of the diode D1.

[0014] Further, the switch tube Q1 is a MOSFET tube, and the switch tube Q3 is a triode.

[0015] Further, the controller comprises a PFC controller, and the second output end of the controller is used for outputting a PWM signal.

[0016] Further, the power supply circuit further comprises an inductor L1 and a capacitor C3, one end of the capacitor C3 is connected with the third electrode of the switch tube Q1 through the inductor L1, and the other end of the capacitor C3 is grounded.

[0017] Further, the power supply circuit further comprises a rectifier module, and the rectifier module comprises a diode D2, a diode D3, a diode D4 and a diode D5, wherein,

[0018] The cathode of the diode D2 is connected with the cathode of the diode D3 and one end of the inductor L1, the anode of the diode D3 is connected with the cathode of the diode D5, the anode of the diode D5 is connected with the anode of the diode D4 and the first electrode of the switch tube Q1, and the cathode of the diode D4 is connected with the anode of the diode D2.

[0019] Further, the power supply circuit further comprises an input module, the input module comprises a capacitor C1, a capacitor C2 and a common mode choke T1, wherein,

[0020] The first output end of the common mode choke T1 is connected with the anode of a diode D2 and the cathode of a diode D4, and the second output end of the common mode choke T1 is connected with the anode of a diode D3 and the cathode of a diode D5.

[0021] The first input end of the common mode choke T1 is connected with the second input end through the capacitor C1, and the first output end of the common mode choke T1 is connected with the second output end through the capacitor C2.

[0022] Further, the input module further comprises a fuse F1, one end of the fuse F1 is connected with one end of the capacitor C1 and the first input end of the common mode choke T1.

[0023] The beneficial technical effects of the utility model are:

[0024] The utility model discloses based on the variable resistance characteristic that MOSFET pipe works in variable resistance area, and through control module control MOSFET pipe Q2 works in variable resistance area, to utilize MOSFET pipe Q2 to replace the precharge resistance in traditional precharge circuit and complete precharge work, and the problem of large size, high cost of device of traditional precharge circuit is solved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is the schematic diagram of traditional precharge circuit provided by the utility model.

[0026] Figure 2 It is the transfer characteristic curve of MOSFET pipe provided by the utility model.

[0027] Figure 3 It is the schematic diagram of one embodiment of precharge circuit based on the working characteristic of power device provided by the utility model. DETAILED DESCRIPTION

[0028] The specific embodiment of the utility model is further explained below in combination with the drawings.

[0029] The utility model provides a kind of precharge circuit based on the working characteristic of power device, the precharge circuit is connected with the capacitor module in power supply circuit, including precharge module, sampling module and control module, the sampling module and control module are connected with precharge module, wherein,

[0030] The precharge module includes at least a MOSFET Q2, the sampling module is used to acquire the source current of the MOSFET Q2 and generate a sampling voltage, and the control module is used to control the MOSFET Q2 to operate in the variable resistance region according to the sampling voltage.

[0031] Specifically, the operating characteristics based on power devices refer to the variable resistance characteristics exhibited by a MOSFET when operating in the variable resistance region. Those skilled in the art will understand that when the gate-source voltage Vgs of a MOSFET is greater than the turn-on voltage Vth, a conductive channel begins to form between the drain and source of the MOSFET, i.e., the MOSFET turns on. When the gate-source voltage Vgs is greater than the turn-on voltage Vth, and the drain-source voltage Vds < Vgs - Vth, the MOSFET operates in the variable resistance region, exhibiting variable resistance characteristics. In this case, the MOSFET is not fully turned on, and the channel resistance is controlled by Vgs. Figure 2 As shown, when the MOSFET operates in the variable resistance region, Vgs is constant, and the drain current ID is linearly related to Vds. The MOSFET can be used as an equivalent resistor.

[0032] In this embodiment, the MOSFET Q2 is an NMOS transistor. When pre-charging the capacitor module in the power supply circuit, the control module controls the MOSFET Q2 to operate in the variable resistance region according to the sampled voltage Vs, thereby replacing the pre-charging resistor in the traditional pre-charging circuit to complete the pre-charging work. This eliminates the need for the costly and bulky pre-charging resistor in the traditional pre-charging circuit, solving the problems of large size and high device cost in traditional pre-charging circuits. The specific forms of the power supply circuit, pre-charging module, sampling module, and control module are described below.

[0033] like Figure 3 As shown, the capacitor module includes capacitors C4 and C5, and the sampling module includes resistor R2. One end of capacitor C4 is connected to the drain of MOSFET Q2, and the source of MOSFET Q2 is grounded through resistor R2. The other end of capacitor C4 is connected to the load, and capacitor C5 is connected in parallel with capacitor C4. Resistor R2 serves as the sampling resistor, used to acquire the source current of MOSFET Q2, i.e., the current flowing through MOSFET Q2. The voltage drop across resistor R2 caused by the source current is the sampling voltage Vs. During pre-charging, MOSFET Q2, which operates in the variable resistance region, is equivalent to a resistor charging capacitors C4 and C5.

[0034] Furthermore, the control module includes a voltage comparator U1, a controller, a switching transistor Q3, resistors R4, R5, and R6, and a capacitor C6, wherein...

[0035] The first output end of the controller is connected with the second electrode of the switch tube Q3, the second electrode of the switch tube Q3 is connected with the power supply voltage VCC, the first electrode of the switch tube Q3 is connected with one end of the resistor R6 and the non-inverting input end of the voltage comparator U1 through the resistor R5, the other end of the resistor R6 is grounded, and the capacitor C6 is connected with the resistor R6 in parallel;

[0036] The non-inverting input end of the voltage comparator U1 is connected with one end of the resistor R2 and the first electrode of the MOSFET tube Q2, and the output end of the voltage comparator U1 is connected with the second electrode of the MOSFET tube Q2 through the resistor R4. The power supply end of the voltage comparator U1 is connected with the power supply voltage VCC, and the grounding end of the voltage comparator U1 is grounded.

[0037] In the embodiment, the controller is a PFC (Power Factor Correction) controller, and the switch tube Q3 is an NPN type triode. For the triode, the first electrode is the emitter, the second electrode is the base, and the third electrode is the collector. In the specific implementation, the switch tube Q3 can also be other power devices with switching function.

[0038] The controller outputs the first control voltage through the first output end to control the conduction state of the switch tube Q3. When the switch tube Q3 is turned on, the power supply voltage VCC is divided by the resistor R5 and the resistor R6 to form the reference voltage Vcoms. The reference voltage Vcoms is slowly loaded to the non-inverting input end of the voltage comparator U1 under the action of the RC delay circuit composed of the resistor R5 and the capacitor C6, and is compared with the sampling voltage Vs loaded to the inverting input end of the voltage comparator U1, so as to control the gate voltage of the MOSFET tube Q2.

[0039] Specifically, when Vcoms>Vs, the voltage comparator U1 outputs the high level voltage (VCC) to load to the gate of the MOSFET tube Q2, so as to increase the Vgs of the MOSFET tube Q2, enhance the conduction ability, increase the source current, and increase Vs. When Vcoms<Vs, the voltage comparator U1 outputs the low level voltage (0V) to load to the gate of the MOSFET tube Q2, so as to reduce the Vgs of the MOSFET tube Q2, reduce the source current, and reduce Vs. Through the control module, the MOSFET tube Q2 can work in the variable resistance region, and the current flowing through the MOSFET tube Q2 is limited, so that the current meets the specification requirements of the safe operating area (SOA).

[0040] Further, the power supply circuit comprises a switch tube Q1, a diode D1, an inductor L1, a capacitor C3 and a resistor R3, a first electrode of the switch tube Q1 is grounded, a second electrode of the switch tube Q1 is connected with a second output terminal of the controller through the resistor R3, a third electrode of the switch tube Q1 is connected with an anode of the diode D1, a cathode of the diode D1 is connected with one end of a capacitor C4 and a capacitor C5. One end of the capacitor C3 is connected with the third electrode of the switch tube Q1 through the inductor L1, the other end of the capacitor C3 is grounded.

[0041] In the embodiment, the switch tube Q1 is an NMOS tube, for the NMOS tube, the first electrode of the switch tube Q1 is a source, the second electrode of the switch tube Q1 is a gate, and the third electrode of the switch tube Q1 is a drain. The capacitor C3, the switch tube Q1, the inductor L1, the capacitor C4, the capacitor C5 and the diode D1 form a boost circuit, the controller outputs a PWM (Pulse Width Modulation) signal to the gate of the switch tube Q1 to control the switch tube Q1 to alternately and repeatedly turn on and turn off, so that the boost circuit realizes the boost function.

[0042] Further, the power supply circuit further comprises a rectifier module and an input module, the rectifier module comprises a diode D2, a diode D3, a diode D4 and a diode D5, wherein,

[0043] The cathode of the diode D2 is connected with the cathode of the diode D3 and one end of the inductor L1, the anode of the diode D3 is connected with the cathode of the diode D5, the anode of the diode D5 is connected with the anode of the diode D4 and the first electrode of the switch tube Q1, and the cathode of the diode D4 is connected with the anode of the diode D2.

[0044] The input module comprises a capacitor C1, a capacitor C2, a fuse F1 and a common mode choke T1, wherein a first output terminal of the common mode choke T1 is connected with the anode of the diode D2 and the cathode of the diode D4, a second output terminal of the common mode choke T1 is connected with the anode of the diode D3 and the cathode of the diode D5, a first input terminal of the common mode choke T1 is connected with a second input terminal through the capacitor C1, and a first output terminal of the common mode choke T1 is connected with a second output terminal through the capacitor C2. One end of the fuse F1 is connected with one end of the capacitor C1 and the first input terminal of the common mode choke T1.

[0045] When the power supply circuit works, the alternating current input voltage is loaded on the capacitor C1 through the fuse F1, and is loaded on the rectifier bridge formed by the rectifier module through the common mode choke T1, and the alternating current input voltage is converted into a direct current input voltage by the rectifier bridge and is input to the boost circuit for boosting. The fuse F1 is used for current limiting protection, and the common mode choke T1 is used for suppressing electromagnetic interference.

[0046] The above merely describes preferred embodiments of the present application, and the present application is not limited to the above embodiments. It can be understood that other improvements and changes directly derived or thought of by those skilled in the art without departing from the spirit and concept of the present application shall be considered to be within the protection scope of the present application.

Claims

1. A precharge circuit based on the operating characteristics of a power device, characterized by, Connect with the capacitor module in the power supply circuit, including pre-charging module, sampling module and control module, the sampling module and control module are connected with pre-charging module, wherein, The pre-charging module at least includes MOSFET tube Q2, the sampling module is used for collecting the source current of MOSFET tube Q2 and generates sampling voltage;The control module is used for controlling MOSFET tube Q2 to work in variable resistance area according to sampling voltage.

2. The pre-charge circuit based on the operating characteristics of power devices according to claim 1, characterized in that, The capacitor module includes capacitor C4 and capacitor C5, and the sampling module includes resistor R2; The MOSFET tube Q2 is NMOS tube, one end of the capacitor C4 is connected with the drain of MOSFET tube Q2, the source of MOSFET tube Q2 is grounded through resistor R2, the other end of the capacitor C4 is connected with load, and the capacitor C5 is connected with capacitor C4 in parallel.

3. The pre-charge circuit based on the operating characteristics of power devices according to claim 2, characterized in that, The control module includes voltage comparator U1, controller, switch tube Q3, resistor R4, resistor R5, resistor R6 and capacitor C6, wherein, The first output end of the controller is connected with the second electrode of switch tube Q3, the second electrode of switch tube Q3 is connected with power supply voltage VCC, the first electrode of switch tube Q3 is connected with one end of resistor R6 and the noninverting input end of voltage comparator U1 through resistor R5, the other end of resistor R6 is grounded, and the capacitor C6 is connected with resistor R6 in parallel; The noninverting input end of voltage comparator U1 is connected with one end of resistor R2 and the source of MOSFET tube Q2, and the output end of voltage comparator U1 is connected with the gate of MOSFET tube Q2 through resistor R4;The power supply end of voltage comparator U1 is connected with power supply voltage VCC, and the ground end of voltage comparator U1 is grounded.

4. The pre-charge circuit based on the operating characteristics of power devices according to claim 3, characterized in that, The power supply circuit includes switch tube Q1, diode D1 and resistor R3, the first electrode of switch tube Q1 is grounded, the second electrode of switch tube Q1 is connected with the second output end of the controller through resistor R3, the third electrode of switch tube Q1 is connected with the anode of diode D1, and one end of capacitor C4 and capacitor C5 is connected with the cathode of diode D1.

5. The pre-charge circuit based on the operating characteristics of power devices according to claim 4, characterized in that, The switch tube Q1 is MOSFET tube, and the switch tube Q3 is triode.

6. The pre-charge circuit based on the operating characteristics of power devices according to claim 3, characterized in that, The controller includes PFC controller, and the second output end of the controller is used for outputting PWM signal.

7. The pre-charge circuit based on the operating characteristics of power devices according to claim 4, characterized by, The power supply circuit further includes inductor L1 and capacitor C3, one end of the capacitor C3 is connected with the third electrode of switch tube Q1 through inductor L1, and the other end of the capacitor C3 is grounded.

8. The pre-charge circuit based on the operating characteristics of power devices according to claim 7, characterized in that, The power supply circuit further includes rectifier module, and the rectifier module includes diode D2, diode D3, diode D4 and diode D5, wherein, The cathode of diode D2 is connected with the cathode of diode D3 and one end of inductor L1, the anode of diode D3 is connected with the cathode of diode D5, the anode of diode D5 is connected with the anode of diode D4 and the first electrode of switch tube Q1, and the cathode of diode D4 is connected with the anode of diode D2.

9. The pre-charge circuit based on the operating characteristics of power devices according to claim 8, characterized in that, The power supply circuit further includes input module, and the input module includes capacitor C1, capacitor C2 and common mode choke coil T1, wherein, The first output end of the common mode choke T1 is connected with the anode of the diode D2 and the cathode of the diode D4, and the second output end of the common mode choke T1 is connected with the anode of the diode D3 and the cathode of the diode D5. The first input end of the common mode choke T1 is connected with the second input end through the capacitor C1, and the first output end of the common mode choke T1 is connected with the second output end through the capacitor C2.

10. The pre-charge circuit based on the operating characteristics of power devices according to claim 9, characterized in that, The input module further comprises a fuse F1, one end of the fuse F1 is connected with one end of the capacitor C1 and the first input end of the common mode choke T1.

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