Be applicable to the synchronous rectification driving circuit of centre cap structure rectifying
Technical field
The present invention relates to a kind of synchronous rectification driving circuit.More particularly, the present invention relates to a kind of current control synchronization commutation driving circuit that is applicable to centre cap structure rectifying circuit.
Background technology
In order to reduce integrated circuit (IC) power consumption, supply power voltage will further reduce, and the low-voltage, high-current power supply is more and more.Along with the progress of semiconductor technology, the conducting resistance of mesolow MOSFET is more and more littler, therefore in the Switching Power Supply of low-voltage, high-current, in order to reduce conduction loss, generally all adopts synchronous rectification.
Synchronous rectification can be divided into driven and current drives by its drive signal type.Its type of drive of topology different in the voltage driving mode is different, and the application of a lot of topologys is restricted, and drive signal is influenced by input voltage, because the no current feedback is unsuitable for working under the DCM state, can cause electric current circulation or the like when being connected in parallel.The current-driven synchronized communtating pipe is to obtain the synchronous rectifier drive signal by the electric current that detection is flow through self.Conducting when synchronous rectifier flows through forward current is turn-offed when electric current is zero, makes reverse current can not flow through synchronous rectifier.Synchronous rectifier is the same with diode can only unidirectional conducting, can be applicable in all kinds of converter topology circuit, so current driven synchronous rectifier is very promising.But existing current-driven synchronized communtating technology power loss is big, and circuit complex work frequency is low, is not easy to control etc., has influenced its application, and Current Transformer Secondary side winding has three groups, and two groups are used for the energy feedback, processed complex, cost height.
The centre cap structure is a kind of rectification circuit commonly used.In the prior art, the synchronous rectifier that uses the current drives mode to drive center-tap rectifier circuit needs two current transformers as independently sampling and driving, and cost is higher.And because current transformer is connected in series with synchronous rectifier, and there are some leakage inductances in instrument transformer itself, and the generation of the junction capacitance between the drain-source of MOSFET resonance, cause due to voltage spikes, increased loss on the line, reduced efficient.
Summary of the invention
In order to reduce the quantity of current transformer and secondary side winding, simplify circuit structure, reduce cost, the present invention proposes a kind of instrument transformer generation two-way method of driving of utilizing.By utilizing a secondary side winding of instrument transformer, produce the two-way drive signal respectively and drive two corresponding synchronous rectifiers.
For this reason, the present invention adopts following technical scheme: the synchronous rectification driving circuit that is applicable to centre cap structure rectifying circuit, comprise high frequency transformer T1, current transformer CT1, output capacitance C1, output capacitance C2, synchronous rectifier SR1, synchronous rectifier SR2 and a drive circuit that is used to drive synchronous rectifier SR1 and synchronous rectifier SR2, it is characterized in that current transformer CT1 has two first side winding N1, N2 and a secondary side winding N3, and can drive two synchronous rectifiers;
Described current transformer CT1 is used to detect the current signal of synchronous rectifier SR1 and synchronous rectifier SR2, the secondary windings in series of its first side winding N1, N2 and high frequency transformer T1, the secondary side winding N3 of current transformer CT1 is connected to the input of described synchronous rectification tube drive circuit;
The drive circuit of described synchronous rectifier has two outputs, the secondary side winding N3 of the input termination current transformer CT1 of synchronous rectification tube drive circuit, and two outputs connect the gate pole of two synchronous rectifiers respectively, and the synchronous rectification tube drive circuit comprises:
Two shapings and reset circuit form drive signal after the current signal of the synchronous rectifier that current transformer CT1 secondary side is detected is converted to voltage signal and shaping, and when this synchronous rectification tube current is zero current transformer CT1 are resetted; The input of described reset circuit connects current transformer CT1 secondary side, and output connects the input of push-pull power amplifier circuit;
Two drive self-powered circuits, the energy that current transformer CT1 gathers is stored, and produced a voltage source that changes with the mean variation of electric current in half switch periods in the synchronous rectifying tube, give whole synchronous rectifier drive circuitry; The secondary side of the input termination current transformer CT1 of described driving self-powered circuit, its output termination push-pull power amplifier circuit;
Two push-pull power amplifier circuits will carry out power amplification rear drive corresponding synchronous rectifying tube from the drive signal of shaping and reset circuit output; The input termination shaping of described push-pull power amplifier circuit and the output of reset circuit, its output connects the gate pole of controlled synchronous rectifier.
Compared with prior art, the invention has the beneficial effects as follows:
1, only need a current transformer and a secondary side winding, realize the driving of two SR, simplified circuit, reduced cost, can be to the high frequency integrated development.
2, can realize the self-powered of drive circuit, drive simple.
3, because the rectification circuit driving voltage changes adjustment automatically with synchronous rectifying tube SR electric current, and driving voltage reduces during underloading, the synchronous rectification driving power consumption is reduced, improved light-load efficiency, reduce loss, reduce cost.
As further improvement of the present invention, between the drain-source utmost point of each synchronous rectifier, also be provided with a mistake Drive Protecting Circuit.Described mistake Drive Protecting Circuit will be missed drive signal and remove, the drain-source utmost point of its input termination synchronous rectifier, output termination shaping and reset circuit when shaping and reset circuit output mistake drive signal.
Further improve as of the present invention, the magnetic core of current transformer CT1 is down " day " font structure again, and first side winding is passed two windows of magnetic core respectively, and secondary side winding is then on the magnetic post of centre.The magnetic core of current transformer CT1 can be pieced together the combined magnet core of forming two symmetrical magnetic circuits by two or more parts.Air gap can be provided with on the magnetic post, also air gap can be do not established.
One preferred embodiment, the magnetic core of current transformer CT1 is made up of two " E " type magnetic cores, the magnetic post mill air gap on " E " type magnetic core both sides, two first side winding N1 and the N2 of CT1 pass from the space of magnetic intercolumniation respectively, the sense of current is identical, and the secondary side winding N3 of CT1 is on the magnetic post of centre.
Another preferred embodiment, the magnetic core of current transformer CT1 is made up of two " E " type magnetic cores, with the center pillar of " E " type magnetic core mill air gap, both sides magnetic post does not grind air gap.Only with an air gap is set, technology is simpler for this execution mode, and mechanical structure is more stable.
Another preferred embodiment, the magnetic core of current transformer CT1 is made up of " E " type magnetic core and " I " type magnetic core, the magnetic post mill air gap on " E " type magnetic core both sides, two first side winding N1 and the N2 of CT1 pass from the space of magnetic intercolumniation respectively, the sense of current is identical, and the secondary side winding N3 of CT1 is on the magnetic post of " E " type magnetic core centre.
Another preferred embodiment, the magnetic core of current transformer CT1 is made up of " E " type magnetic core and " I " type magnetic core, with the center pillar of " E " type magnetic core mill air gap, both sides magnetic post does not grind air gap.Only with an air gap is set, technology is simpler for this execution mode, and mechanical structure is more stable.
Another preferred embodiment, the magnetic core of current transformer CT1 is made up of three " worker " font magnetic core splicings, magnetic core does not have air gap, two first side winding N1 and the N2 of CT1 pass from the space between three " worker " font magnetic cores respectively, the sense of current is identical, and the secondary side winding N3 of CT1 is on " worker " font magnetic core of centre.This execution mode need not be provided with air gap, and technology is simple, and mechanical structure is stable.
Description of drawings
The invention will be further described below in conjunction with drawings and Examples.
Fig. 1 current transformer of the present invention drives the specific implementation circuit diagram of synchronous rectifier.
A kind of structure chart of Fig. 2 current transformer of the present invention.
The another kind of structure chart of Fig. 3 current transformer of the present invention.
The third structure chart of Fig. 4 current transformer of the present invention.
The 4th kind of structure chart of Fig. 5 current transformer of the present invention.
The 5th kind of structure chart of Fig. 6 current transformer of the present invention.
Fig. 7 the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit one that drives protection with mistake.
Fig. 8 the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit two that drives protection with mistake.
Fig. 9 the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit three that drives protection with mistake.
Figure 10 the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit four that drives protection with mistake.
Figure 11 the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit five that drives protection with mistake.
Figure 12 the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit six that drives protection with mistake.
Figure 13 the present invention is applied to the circuit diagram of half-bridge LLC circuit.
Figure 14 the present invention is applied to the circuit diagram of full-bridge LLC circuit.
Embodiment
With reference to accompanying drawing 1, current transformer of the present invention drives the specific implementation circuit diagram of synchronous rectifier, comprises current transformer CT1 and drive circuit.
Described current transformer CT1 is made up of magnetic core, first side winding N1, first side winding N2 and secondary side winding N3.The secondary windings in series of first side winding N1, N2 and high frequency transformer T1, the secondary side winding N3 of current transformer CT1 is connected to the input of drive circuit.
Drive circuit comprises two shapings and reset circuit, two driving self-powered circuits and two push-pull power amplifier circuits.Described shaping and reset circuit are made up of diode D1, resistance R 1 and resistance R 2, the negative electrode of diode D1 connects the end of the same name of current transformer CT1 secondary side winding N3 and an end of resistance R 1, the end of the other end connecting resistance R2 of resistance R 1, the anode of another terminating diode D1 of resistance R 2 and the source electrode of synchronous rectifier SR1; Described driving self-powered circuit is made up of diode D2 and energy storage capacitor C3, the anode of diode D2 connects the end of the same name of current transformer CT1 secondary side winding N3, the negative electrode of diode D2 connects the positive pole of energy storage capacitor C3, and the negative pole of energy storage capacitor C3 connects the source electrode of synchronous rectifier SR1; Described push-pull power amplifier circuit is made up of NPN type triode Q1, positive-negative-positive triode Q2 and diode D7 forms, the base stage of triode Q1 connects the base stage of triode Q2, the anode of diode D7 and the other end of resistance R 1, the negative electrode of diode D7 connects the end of the same name of current transformer CT1 secondary side winding N3, the emitter of triode Q1 connects the emitter of triode Q2 and the gate pole of synchronous rectifier SR1, the collector electrode of triode Q1 connects the negative electrode of diode D2, and the collector electrode of triode Q2 connects the source electrode of synchronous rectifier SR1.
With reference to accompanying drawing 2, adopt a kind of structure chart of current transformer of the present invention.The magnetic core of current transformer CT1 is made up of two " E " type magnetic cores, the magnetic post mill air gap on " E " type magnetic core both sides, two first side winding N1 and the N2 of CT1 pass from the space of magnetic intercolumniation respectively, and the sense of current is identical, and the secondary side winding N3 of CT1 is on the magnetic post of centre.
With reference to accompanying drawing 3, adopt the another kind of structure chart of current transformer of the present invention.The center pillar of comparing " E " type magnetic core with Fig. 2 grinds air gap, and both sides magnetic post does not grind air gap, and all the other structures are constant.Only with an air gap is set, technology is simpler for this execution mode, and mechanical structure is more stable.
With reference to accompanying drawing 4, adopt the third structure chart of current transformer of the present invention.The magnetic core of current transformer CT1 is made up of " E " type magnetic core and " I " type magnetic core, the magnetic post mill air gap on " E " type magnetic core both sides, two first side winding N1 and the N2 of CT1 pass from the space of magnetic intercolumniation respectively, the sense of current is identical, and the secondary side winding N3 of CT1 is on the magnetic post of " E " type magnetic core centre.
With reference to accompanying drawing 5, adopt the 4th kind of structure chart of current transformer of the present invention.The center pillar of comparing " E " type magnetic core with Fig. 4 grinds air gap, and both sides magnetic post does not grind air gap, and all the other structures are constant.Only with an air gap is set, technology is simpler for this execution mode, and mechanical structure is more stable.
With reference to accompanying drawing 6, adopt the 5th kind of structure chart of current transformer of the present invention.The magnetic core of current transformer CT1 is made up of three " worker " font magnetic core splicings, magnetic core does not have air gap, two first side winding N1 and the N2 of CT1 pass from the space between three " worker " font magnetic cores respectively, the sense of current is identical, and the secondary side winding N3 of CT1 is on " worker " font magnetic core of centre.This execution mode need not be provided with air gap, and technology is simple, and mechanical structure is stable.
With reference to accompanying drawing 7, the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit one with mistake driving protection, comprises main circuit, drive circuit, current transformer CT1 and two mistake Drive Protecting Circuit.
Described main circuit is made up of first side winding, output capacitance C1, output capacitance C2, synchronous rectifier SR1, the synchronous rectifier SR2 of high frequency transformer T1, current transformer CT1.The termination of the same name of high frequency transformer T1 connects the non-same polarity of current transformer CT1 first side winding N1, the non-same polarity of high frequency transformer T1 connects the end of the same name of current transformer CT1 first side winding N2, and the centre cap of high frequency transformer T1 connects the positive pole of output capacitance C1 and output capacitance C2; The drain electrode of the termination synchronous rectifier SR1 of the same name of current transformer CT1 first side winding N1, the non-same polarity of current transformer CT1 first side winding N2 connects the drain electrode of synchronous rectifier SR2; The source electrode of synchronous rectifier SR1 connects the source electrode of synchronous rectifier SR2, the negative pole of output capacitance C1 and the negative pole of output capacitance C2, and gate pole links to each other with the output of drive circuit; The gate pole of synchronous rectifier SR2 links to each other with the output of drive circuit.
Described drive circuit summation current transformer CT1 is identical with Fig. 1 structure.
Described mistake Drive Protecting Circuit is made of the negative electrode of a terminating diode D3 of resistance R 3 and the drain electrode of synchronous rectifier SR1, the anode of another terminating diode D3 and the base stage of triode Q3 resistance R 3, diode D3 and triode Q3; The collector electrode connecting resistance R1 of triode Q3 and the tie point of resistance R 2, emitter connects the source electrode of synchronous rectifier SR1.
With reference to accompanying drawing 8; the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit two that drives protection with mistake; comparing with the circuit of Fig. 7 has increased a diode D9; receive the anode of diode D9 after the positive pole of capacitor C 3 and capacitor C 4 linked to each other; the negative electrode of diode D9 connects the output of main circuit, and all the other structures are constant.Adopt this structure can reduce the number of turn of current transformer CT1 secondary winding N3, reduce cost, and can realize that portion of energy directly to load output feed, raises the efficiency, can be applied to the not high situation of output voltage (greater than 10V less than 20V).
With reference to accompanying drawing 9; the present invention is applied to a kind ofly drive the centre cap structure rectifying embodiment of circuit three of protection with mistake, and comparing with Fig. 7 has increased a voltage-stabiliser tube Z1, receives the negative electrode of voltage-stabiliser tube Z1 after the positive pole of capacitor C 3 and capacitor C 4 is linked to each other; the plus earth of voltage-stabiliser tube Z1, all the other structures are constant.Adopt this structure can reduce the number of turn of current transformer CT1 secondary winding N3, reduce cost.
With reference to accompanying drawing 10; the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit four with mistake driving protection, and comparing with Fig. 9 has increased a diode D9, and the anode of diode D9 connects the negative electrode of voltage-stabiliser tube Z1; the negative electrode of diode D9 connects main circuit output, and all the other structures are constant.Adopt this result can reduce the number of turn of current transformer CT1 secondary winding, reduce cost, and can realize that portion of energy directly to load output feed, raises the efficiency, can be applied to the not high situation of output voltage (greater than 10V less than 20V).
With reference to accompanying drawing 11; the present invention is applied to a kind of centre cap structure rectifying embodiment of circuit five that drives protection with mistake; compare with Fig. 7 and to have lacked two energy storage capacitor C3 and C4; a voltage stabilizing didoe Z2 and a capacitor C 5 have been increased; connect the negative electrode of voltage-stabiliser tube Z2 and the positive pole of capacitor C 5 after the collector electrode of triode Q1 and Q4 linked to each other, the anode of voltage-stabiliser tube Z2 connects the output of the negative pole and the main circuit of capacitor C 5.Adopt this result can reduce the number of turn of current transformer CT1 secondary winding, reduce cost, and can realize that portion of energy directly to load output feed, raises the efficiency, can be applied to the lower situation of output voltage (less than 10V).
With reference to Figure 12, the present invention is applied to a kind ofly drive the centre cap structure rectifying embodiment of circuit six of protection with mistake, compares the output that connects main circuit after positive pole with capacitor C 3 and capacitor C 4 links to each other with the circuit of Fig. 7, and all the other structures are constant.Adopt this structure can reduce the number of turn of current transformer CT1 secondary winding N3, reduce cost, and can realize that portion of energy directly to load output feed, raises the efficiency, can be applied to the not high situation of output voltage (greater than 10V less than 20V).
With reference to Figure 13, the present invention is applied to the circuit diagram of half-bridge LLC circuit, comprises the centre cap structure rectifying circuit of half-bridge circuit and band drive circuit of the present invention.
With reference to Figure 14, the present invention is applied to the circuit diagram of full-bridge LLC circuit, comprises full-bridge circuit and band drive circuit centre cap structure rectifying circuit of the present invention.
At last, it is also to be noted that what more than enumerate only is specific embodiments of the invention.Obviously, the invention is not restricted to above embodiment, many distortion can also be arranged.All distortion that those of ordinary skill in the art can directly derive or associate from content disclosed by the invention all should be thought the protection range of inventing.
What should be understood that is: the foregoing description is just to explanation of the present invention, rather than limitation of the present invention, and any innovation and creation that do not exceed in the connotation scope of the present invention all fall within protection scope of the present invention.