CN204707027U

CN204707027U - A kind of isolation MOSFET drive circuit

Info

Publication number: CN204707027U
Application number: CN201520350492.7U
Authority: CN
Inventors: 舒文彬; 李思奇
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2015-05-27
Filing date: 2015-05-27
Publication date: 2015-10-14
Anticipated expiration: 2025-05-27

Abstract

The utility model relates to a kind of isolation MOSFET drive circuit, belongs to power electronics and drives applied technical field.The utility model comprises high-frequency isolation transformer T, capacitance C1, capacitance C2, electric capacity C3, diode D1, D2, D3, triode V1, V2, MOSFET pipe Q.The utility model can solve the problem of the drive current deficiency caused because isolating transformer there is leakage inductance, and driving force is strong, and structure is simple.Utilize electric capacity that big current can be provided instantaneously to make up the defect that immediate current deficiency opened by isolating transformer in the circuit cleverly, thus realize open-minded fast, form loop at shutdown moment by PNP triode and MOSFET input capacitance simultaneously, the electric charge of input capacitance is released rapidly, realizes turning off fast.

Description

A kind of isolation MOSFET drive circuit

Technical field

The utility model relates to a kind of isolation MOSFET drive circuit, belongs to power electronics and drives applied technical field.

Background technology

At present, in power conversion circuit, MOSFET (metal oxide semiconductor field effect tube) drive circuit has dissimilar and respective corresponding technical scheme, respectively has pluses and minuses.The utility model proposes a kind of high-speed isolated MOSFET drive circuit, utilize totem mode circuit structure, use the device composition drive circuits such as high-frequency isolation transformer, diode, electric capacity.This drive circuit can solve the inadequate problem of the driving voltage that causes because isolating transformer there is leakage inductance, driving force is strong, utilize electric capacity that big current can be provided instantaneously to make up the defect that immediate current deficiency opened by isolating transformer in the circuit cleverly, thus realize open-minded fast, form loop at shutdown moment by PNP triode and MOSFET input capacitance simultaneously, the electric charge of input capacitance is released rapidly, realizes turning off fast.

Summary of the invention

The technical problems to be solved in the utility model is: the utility model provides a kind of isolation MOSFET drive circuit, the drive current deficiency caused because isolating transformer there is leakage inductance, slow-footed problem can be solved, driving force is strong, structure is simple, utilize electric capacity that big current can be provided instantaneously to make up the defect that immediate current deficiency opened by isolating transformer in the circuit cleverly, thus realize open-minded fast, form loop at shutdown moment by PNP triode and MOSFET input capacitance simultaneously, the electric charge of input capacitance is released rapidly, realizes turning off fast.

Technical solutions of the utility model are: a kind of isolation MOSFET drive circuit, comprises high-frequency isolation transformer T, capacitance C1, capacitance C2, electric capacity C3, diode D1, D2, D3, triode V1, V2, MOSFET pipe Q;

Described capacitance C1 is connected with the primary coil of high-frequency isolation transformer T, the secondary coil of described high-frequency isolation transformer T through capacitance C2 more respectively with the negative pole of diode D1, the positive pole of diode D2, triode V1 base stage, triode V2 base stage is connected, the positive pole of diode D1 respectively with the collector electrode of triode V2, the positive pole of diode D3, the source electrode of MOSFET pipe Q is connected, the negative pole of diode D2 respectively with the collector electrode of triode V1, one end of electric capacity C3 is connected, the other end of electric capacity C3 is connected with the source electrode of MOSFET pipe Q, triode V1 emitter and triode V2 emitter respectively with the negative pole of diode D3, the grid of MOSFET pipe Q is connected.

Circuit working principle of the present utility model is:

When drive singal is by high-frequency isolation transformer T, respectively according to drive singal positive and negative come conducting NPN transistor and PNP transistor, thus driven MOS FET.Element in Fig. 1, when high-frequency isolation transformer T secondary coil Same Name of Ends is timing, D2 conducting, C3 charges rapidly, the turning-on voltage of MOSFET is now provided by coil and electric capacity C3, triode V1 due to high potential open-minded, voltage through diode to electric capacity C3 charging open MOSFET through triode simultaneously, as shown in Figure 2.In the process, electric capacity C3 utilizes the characteristic of electric capacity moment discharge and recharge provide big current to make up the problem that immediate current deficiency opened by isolating transformer instantaneously opening, because open high-frequency isolation transformer instantaneously to there is leakage inductance, cause opening undercurrent, and electric capacity C3 open moment rapidly electric discharge just can make up.And open stable after, voltage charges to C3.When high frequency transformer secondary coil Same Name of Ends is for time negative, PNP triode is open-minded, forms loop with the input capacitance of MOSFET, and now input capacitance is discharged rapidly by this loop, turns off fast, as shown in Figure 3.

In addition, the turn ratio of described high-frequency isolation transformer T is 1:1 (in varied situations can designed, designed turn ratio).

Totem-pote circuit comprises NPN triode, PNP triode, i.e. corresponding triode V1, triode V2, and described electric capacity C3 can open at MOSFET the problem making up the drive current deficiency that isolating transformer causes because of leakage inductance instantaneously.

Belonging to when diode D2 can prevent electric capacity C3 repid discharge in circuit electric current flow back to secondary coil.

Described isolating transformer turn ratio can designed, designed as required, and winding also can carry out suitable increase in addition.

Add isolating transformer in this drive circuit, isolating transformer is generally high frequency, high-frequency magnet ring.The former limit of high frequency transformer adds capacitance, stop DC component flow through, prevent transformer dc magnetize and saturated.The secondary of transformer adds an electric capacity, is used for reappearing the voltage (when transformer turn ratio is 1:1) of former limit capacitance.Electric capacity and secondary and a Diode series, it is capacitor charging that this diode plays when voltage reversal, and when voltage forward, electric capacity is connected with secondary and reappeared former limit capacitance voltage.And the electric capacity be connected with totem-pote circuit NPN triode plays to discharge and maintains the effect of MOSFET turning-on voltage.Diode is that when preventing electric capacity C3 from discharging, electric current flows back to secondary coil.

The beneficial effects of the utility model are:

The utility model can solve the problem of the drive current deficiency caused because isolating transformer there is leakage inductance, and driving force is strong, and structure is simple.Utilize electric capacity that big current can be provided instantaneously to make up the defect that immediate current deficiency opened by isolating transformer in the circuit cleverly, thus realize open-minded fast, form loop at shutdown moment by PNP triode and MOSFET input capacitance simultaneously, the electric charge of input capacitance is released rapidly, realizes turning off fast;

The utility model circuit cost is cheap, only by basic electronic devices and components composition, and can need to carry out multichannel expansion according to driving, has good effect to requiring that antijamming capability is strong, open at a high speed the drive circuit of shutoff.

Accompanying drawing explanation

Fig. 1 is the utility model circuit theory diagrams;

Working state schematic representation when Fig. 2 is the utility model circuit debugging;

Working state schematic representation when Fig. 3 is the utility model circuit shut-down;

Device voltage waveform when Fig. 4 is the emulation of the utility model drive circuit high frequency transformer;

Fig. 5 is the voltage oscillogram of the utility model MOSFET pipe when opening;

Voltage oscillogram when Fig. 6 is the shutoff of the utility model MOSFET pipe.

In Fig. 1-4, T is high-frequency isolation transformer, and C1, C2, C3 are capacitance, and C3 is electric capacity, and D1, D2 are fly-wheel diode, and D3 is voltage-stabiliser tube, and V1 is NPN type triode, and V2 is positive-negative-positive diode, and Q is MOSFET pipe;

In Fig. 4, V (n007) is high-frequency isolation transformer primary coil voltage waveform, V (n002) for high-frequency isolation transformer secondary coil voltage waveform, V (n005) after electric capacity C2 raises be MOSFET grid turning-on voltage waveform.

Embodiment

Below in conjunction with the drawings and specific embodiments, the utility model is described in further detail.

Embodiment 1: as shown in figures 1 to 6, a kind of isolation MOSFET drive circuit, comprises high-frequency isolation transformer T, capacitance C1, capacitance C2, electric capacity C3, diode D1, D2, D3, triode V1, V2, MOSFET pipe Q;

High-frequency isolation transformer T primary coil meets electric capacity C1, can play a part every straight, prevents high-frequency isolation transformer T saturated by direct current.Isolating transformer secondary coil is connected with electric capacity C2, except isolated DC electricity also plays the effect of reproduction former limit capacitance voltage, diode D1 is electric capacity C2 reverse charging when secondary voltage is reverse, when coil voltage is just, electric capacity and coils connected in series, thus reproduction original edge voltage.Voltage through electric capacity not only directly connects with totem-pote circuit transistor base, and be connected to NPN type triode V1 collector electrode through diode D2, charges to electric capacity C3, triode V1 emitter is connected with the emitter of V2, composition totem exports, and is used for power amplification, improves driving force.Voltage-stabiliser tube D3 maintains the turning-on voltage of MOSFET.

For more intuitive explanation, Fig. 2 and Fig. 3 is utilized to further illustrate the operating state of MOSFET when turning on and off below.

As shown in Figure 2, be timing at high frequency transformer secondary coil Same Name of Ends, the turning-on voltage of MOSFET be provided by coil and electric capacity C2, now triode V1 due to high potential open-minded, voltage through diode to electric capacity C3 charging open MOSFET through triode simultaneously.In the process, electric capacity C3 utilizes the characteristic of electric capacity moment discharge and recharge provide big current to make up the problem that immediate current deficiency opened by isolating transformer instantaneously opening, because open high-frequency isolation transformer instantaneously to there is leakage inductance, cause opening undercurrent, and electric capacity C3 open moment rapidly electric discharge just can make up.And open stable after, voltage charges to C3.

As shown in Figure 3, at high frequency transformer secondary coil Same Name of Ends for time negative, bold portion forms loop, and now PNP triode is open-minded, forms loop with the input capacitance of MOSFET, and now input capacitance is discharged rapidly by this loop, turns off fast.

The present embodiment has also carried out the test of actual effect.As shown in Figure 4, V (n007) is primary transformer coil voltage waveform, and V (n002) is the voltage waveform of secondary transformer after electric capacity C2 raises, and V (n005) is MOSFET pipe turning-on voltage waveform.As can be seen from the figure, service time and the turn-off time of MOSFET pipe are shorter, and turning-on voltage waveform is steady.

Analogous diagram as can be seen from Fig. 5, Fig. 6, service time (as shown in Figure 5) and the turn-off time (as shown in Figure 6) of MOSFET pipe are all shorter, and all at about 20ns, and driving voltage waveform is stablized.

By reference to the accompanying drawings specific embodiment of the utility model is explained in detail above, but the utility model is not limited to above-described embodiment, in the ken that those of ordinary skill in the art possess, various change can also be made under the prerequisite not departing from the utility model aim.

Claims

1. isolate a MOSFET drive circuit, it is characterized in that: comprise high-frequency isolation transformer T, capacitance C1, capacitance C2, electric capacity C3, diode D1, D2, D3, triode V1, V2, MOSFET pipe Q;