CN217741563U

CN217741563U - Passive drive lossless soft switch clamping circuit

Info

Publication number: CN217741563U
Application number: CN202221567963.6U
Authority: CN
Inventors: 田前程; 祝春霞
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-12-03
Filing date: 2022-06-22
Publication date: 2022-11-04
Anticipated expiration: 2032-06-22

Abstract

The utility model discloses a harmless soft switch clamp circuit of passive drive, including first transformer, first unit, the soft switch clamp unit of passive drive and second unit, first unit is equipped with rectification filter circuit, rectification filter circuit is used for alternating voltage to carry out rectification filtering in order to obtain generating line DC voltage, the soft switch clamp unit of passive drive, including first diode, second diode, third diode, second electric capacity, third electric capacity and second switch tube, the second unit includes QR mode controller, first resistance, second resistance, third resistance, first switch and first electric capacity, through first switch break-make transmission energy to secondary; the first resistor is a current sampling resistor, and a current signal is sampled to the QR mode controller; the second resistor and the third resistor form a resistor voltage divider and provide a demagnetization signal to the QR mode controller. The utility model provides a soft switch clamp circuit of passive drive not only realizes traditional RCD clamp circuit's function, can also provide the zero voltage for the main switch and open and turn-off the condition to self has also realized the soft switch break-make, and does not need extra drive and supply circuit.

Description

Passive drive lossless soft switch clamping circuit

Technical Field

The utility model belongs to the technical field of the circuit, concretely relates to harmless soft switch clamp circuit of passive drive.

Background

The flyback topology of the QR mode is widely applied to switching power supplies below 150W, such as the fast charging field, or LED illumination and the like. In a conventional QR flyback, a primary side comprises a main switch mosfet and an RCD clamping circuit, wherein capacitive discharge of C1 exists when a main switch tube Q1 is switched on, and hard switch switching-off exists when the main switch tube Q1 is switched off, and particularly under the high-frequency condition (over 100K), loss is increased obviously along with further improvement of frequency, so that the further improvement of working frequency is limited, and the realization of high power density in unit volume is not facilitated; meanwhile, the RCD clamping circuit discharges through the resistor R all the time, and the RCD clamping circuit is used as fixed loss, so that the improvement of the efficiency of the whole machine is further limited.

With the accelerated commercialization of third-generation semiconductors, it is becoming an urgent subject to develop a driving topology suitable for third-generation semiconductors, since new semiconductor devices such as gallium nitride and silicon carbide can sufficiently exhibit their excellent performance only when they are operated in a high-frequency operating region. The utility model is based on this and provides an alternative solution.

SUMMERY OF THE UTILITY MODEL

The utility model provides a problem: a soft switching topology circuit suitable for high frequency and high power density, suitable for driving third generation semiconductor power devices and not limited thereto is provided. Therefore, on the basis of the original flyback QR topology, the original RCD clamping part is improved, and the effect of forming a soft switch is achieved.

In order to achieve the above purpose, the utility model provides a technical scheme: a passive driving lossless soft switch clamping circuit comprises a first transformer, a first unit, a passive driving soft switch clamping unit and a second unit,

the first unit is provided with a rectifying and filtering circuit which is used for rectifying and filtering alternating current voltage to obtain bus direct current voltage, the first transformer is coupled with the primary and secondary stages and transmits energy to the secondary stage,

the passive driving soft switch clamping unit comprises a first diode, a second diode, a third diode, a second capacitor, a third capacitor and a second switch tube,

the second unit comprises a QR mode controller, a first resistor, a second resistor, a third resistor, a first switch and a first capacitor, energy is transmitted to a secondary through the on-off of the first switch, the first resistor is a current sampling resistor, a sampling current signal is transmitted to the QR mode controller, a resistor voltage divider is formed by the second resistor and the third resistor, a demagnetization signal is provided to the QR mode controller, and the first switch is connected with the first capacitor in parallel.

The utility model discloses a technological effect and advantage: the utility model provides a soft switch clamp circuit of passive drive, make full use of Ciss2 and the second electric capacity series connection of second switch tube itself carry out the partial pressure to original clamp voltage, realize right the passive drive of second switch tube returns the flat wave electric capacity of generating line to realize harmlessly through the energy return of resonance in with clamp electric capacity at later stage, not only realizes traditional RCD clamp circuit's function, can also carry out zero voltage simultaneously and open and turn-off manufacturing conditions for the main switch to soft switch break-make has also been realized to self, and does not need extra drive and supply circuit, has superior performance and cost advantage. The utility model discloses a first switch and second switch tube can be the mosfet (including plane and coolmos) of second generation semiconductor, also can be the GaN pipe of third generation semiconductor, and cis 2 and C1 can be the input/output electric capacity of switch tube itself, and the electric capacity that also can be extra to incorporate adds the sum of the input/output electric capacity of itself, specifically confirms according to practical application.

Drawings

Fig. 1 is the overall schematic diagram of the passive-driven lossless soft switching clamp circuit of the present invention.

Fig. 2 is a schematic diagram of the passive driving soft switching clamping unit of the present invention.

Fig. 3 is a schematic diagram of the second unit and the third unit according to the present invention.

Fig. 4 is a schematic diagram of the waveform of Vds on the first switch in a switching cycle according to the present invention.

Detailed Description

As shown in fig. 1 to 4, a passive driving lossless soft switching clamp circuit includes a first transformer 10, a first unit 100, a second unit 200, a third unit 300, and a passive driving soft switching clamp unit 400, where the first unit 100 has a rectifying and filtering circuit 110, the rectifying and filtering circuit 110 is used for rectifying and filtering an ac voltage to obtain a bus dc voltage, and the first transformer 10 is coupled to a primary side and performs energy transmission to a secondary side.

The second unit 200 includes a QR mode controller 210, a first switch Q1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth diode D4, a first capacitor C1, and a fifth capacitor C5, and energy is transmitted to a secondary side through on/off of the first switch Q1, the first resistor R1 samples a current, samples a current signal and provides the QR mode controller 210 with the sampled current signal, the second resistor R2 and the third resistor R3 are resistor voltage dividers and provide a demagnetization signal to the QR mode controller 210, and the fourth diode D4 and the fifth capacitor C5 provide an auxiliary power supply to the QR mode controller 210.

The third unit 300 includes a fifth diode D5, a fourth capacitor C4 and a feedback unit 310, the third unit 300 provides a control signal to the QR mode controller 210 through the sub-sampling feedback unit 310, the QR mode controller 210 of the second unit 200 is configured to receive the control signal and drive the first switch Q1, and the fifth diode D5 and the fourth capacitor C4 are configured to perform a sub-rectifying filtering.

The passive driving soft switch clamping unit 400 comprises a first diode D1, a second diode D2, a third diode D3, a second capacitor C2, a third capacitor C3, a second switch tube Q2 and a first voltage-regulator tube ZD1, wherein the second capacitor C2 is connected in series with an input capacitor Ciss2 of the second switch tube Q2 and then connected in parallel with the third capacitor C3, the first voltage-regulator tube ZD1 is connected in parallel between GS poles of the second switch tube Q2 to provide clamping protection, the second switch tube Q2 of the passive driving soft switch clamping unit 400 clamps the first switch Q1 when the first switch Q1 is turned off and creates a soft switch on condition, and the first switch Q1 is connected in parallel with the first capacitor C1.

The first diode D1 provides a path for the input capacitor Ciss2 of the second switch tube Q2, the second diode D2 can block the input capacitor Ciss2 of the second switch tube Q2, the third diode D3 provides a path for reverse recovery for the second capacitor C2, and the first capacitor C1 includes the sum of the output capacitor of the first switch tube Q1 and an additional capacitor connected in parallel with the output capacitor.

The input capacitor Ciss2 is not limited to the input capacitor of the second switch Q2 itself, and may further include a sum of an additional capacitor additionally connected in parallel between GS and its own input capacitor.

The patent mainly uses the second capacitor C2 and Ciss2 connected in series to divide the clamping voltage to drive the second switch tube Q2, which is one of the core protection items of the patent, and any method related to this principle to drive the second switch tube Q2 is within the protection of the patent. And Ciss2 is not limited to the input capacitance of the second switching tube Q2 itself, but may also include the sum of an additional capacitance connected in parallel between GS and its own input capacitance.

The utility model provides a soft switch clamp circuit of passive drive not only realizes traditional RCD clamp circuit's function, can also provide the zero voltage for the main switch and open and turn-off the condition to self has also realized the soft switch break-make, and does not need extra drive and supply circuit.

Claims

1. A kind of passive drive can't damage the soft switch clamp circuit, characterized by that: comprises a first transformer, a first unit, a passive driving soft switch clamping unit and a second unit,

2. The passively driven lossless soft switch clamp circuit of claim 1, wherein: the second unit further includes a fourth diode and a fifth capacitor, and the fourth diode and the fifth capacitor provide an auxiliary power supply to the QR mode controller.

3. The passively driven lossless soft switch clamp circuit of claim 1, wherein: the third unit comprises a fifth diode, a fourth capacitor and a feedback unit, the third unit samples secondary through the feedback unit and provides an isolation control signal to the QR mode controller of the second unit, the QR mode controller of the second unit is used for receiving the control signal and driving the first switch, and the fifth diode and the fourth capacitor are used for secondary rectification filtering.

4. The passively driven lossless soft switch clamp circuit of claim 1, wherein: the passive driving soft switch clamping unit is provided with a first voltage-stabilizing tube, the second capacitor is connected with an input capacitor Ciss2 of the second switch tube in series and then connected with the third capacitor in parallel, the first voltage-stabilizing tube is connected between GS poles of the second switch tube in parallel to provide clamping protection, the second switch tube of the passive driving soft switch clamping unit utilizes the input capacitor Ciss2 of the second switch tube to participate in resonance after being connected with the second capacitor in series, passive driving of the second switch tube is achieved, clamping is carried out when the first switch is turned off, and a soft switch turning-on condition is created for the first switch to be turned on in the next period.

5. The passively driven lossless soft switch clamp circuit of claim 1, wherein: the first diode provides a path for an input capacitor Ciss2 of the second switch tube, the second diode can block the input capacitor Ciss2 of the second switch tube, and the third diode provides a reverse recovery path for the second capacitor.