CN103312171B - Isolated soft switching double tube positive exciting resonance DC/DC circuit - Google Patents

Abstract

The invention relates to a power electronic electric energy conversion circuit, and aims to provide an isolated soft-switch double-tube forward resonance DC/DC circuit. The circuit includes a power supply, two switching tubes, two clamping diodes, a high-frequency isolation transformer, a primary winding, a secondary winding, an output rectifier diode, and an output filter capacitor; it also includes an input-side inductor, a resonant inductor, and a resonant capacitor; the resonant The capacitor Cr is connected in parallel with the power supply, and the input side inductance is located between the resonant capacitor and the power supply; the resonant inductance is connected in series with the primary winding of the transformer; the load composed of the resonant inductance, the resonant capacitor and the output voltage forms a series resonant circuit. The invention enables the power switch tube to work in the zero-voltage on and quasi-zero-current off states, reduces the overlapping time of the voltage at both ends of the power switch tube and the current passing through the power switch tube, and reduces the switching loss of the power switch tube. It can recycle the energy on the parasitic inductance or capacitance, improve the energy conversion efficiency; reduce the energy consumption of the circuit and save energy. <!--1-->

Description

Isolated Soft-Switching Dual Transistor Forward Resonant DC/DC Circuit

technical field

The invention relates to a power electronic electric energy conversion circuit, in particular to an isolated soft switch double-tube forward resonance DC/DC circuit.

Background technique

The forward topology has been widely used due to its simple circuit structure, electrical isolation of input and output, wide range of voltage rise and fall, easy multi-channel output, and suitable for small and medium power power conversion occasions. The dual-tube forward DC/DC converter circuit is a DC voltage conversion circuit in the forward topology in power electronics technology. Today's dual-tube forward DC/DC converter circuit is generally realized by the structure shown in Figure 1: it includes diodes D _p1 and D _p2 for magnetic reset, switch tubes Q ₁ and Q ₂ , isolation input and output and It consists of a transformer T ₁ for voltage lifting, a diode D ₁ for limiting current flow, a freewheeling diode D ₂ , and an inductance L and a capacitor C _o for filtering. The dual-transistor forward DC/DC conversion circuit has disadvantages: because the power electronic device is not an ideal switch, there is a turn-on delay and a turn-off delay, which causes the voltage at _both ends of the switch tubes Q1 and _Q2 and the current through them to appear. overlap time, resulting in switching losses.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide an isolated soft-switching double-transistor forward resonant DC/DC circuit. By adopting the converter circuit, the present invention can reduce the overlap time between the voltage applied to both ends of the switch tube and the current passing through the switch tube at the moment of turning on and off of the switch tube, thereby reducing the switching loss of the switch device and suppressing the voltage or current overshoot occurs.

For solving technical problem, solution of the present invention is:

Provides an isolated soft-switching dual-tube forward resonant DC/DC circuit, including a power supply (V _in ), two switching tubes (Q ₁ , Q ₂ ), two clamping diodes (D _p1 , D _p2 ), high Frequency isolation transformer (T ₁ ), primary winding (N _P ), secondary winding (N _s ), output rectifier diode (D ₁ ) and output filter capacitor (C _o ); the circuit also includes input side inductance (L _in ), the resonant inductance (L _r ) and the resonant capacitor (C _r ); the resonant capacitor C _r is connected to the power supply (V _in ) in parallel, and the input side inductance (L _in ) is located between the resonant capacitor (C _r ) and the power supply (V _in ) The resonant inductance (L _r ) is connected in series with the primary winding of the transformer; the load composed of the resonant inductance (L _r ) and the resonant capacitor (C _r ) and the output voltage V _o forms a series resonant circuit.

In the present invention, the positive pole of the power supply (V _in ) is connected to the input end of the input side inductance (L _in ), the output end of the input side inductance (L _in ) is connected to the input end of the resonant capacitor (C _r ), and the resonant capacitor (C r ) _r ) The output end is connected to the negative pole of the power supply (V _in ) to form a loop; the output end of the input inductor (L _in ) is also connected to one end of the switch tube (Q ₂ ), and the other end of the switch tube (Q ₂ ) is connected to the high frequency isolation transformer (T ₁ ) The resonant inductor (L _r ) connected to the end of the primary winding (N _p ) with the same name, and the high frequency isolation transformer (T ₁ ) primary winding (N _p ) with the opposite end connected to the end of the switching tube (Q ₁ ), The other end of the switch tube (Q ₁ ) is connected to the negative pole of the power supply (V _in ) to form a loop; the input end of the resonant inductor (L _r ) is connected to the cathode of the clamping diode (D _p2 ), and the anode of the clamping diode (D _p2 ) is connected to the power supply (V _in ) negative pole; high-frequency isolation transformer (T ₁ ) primary winding (N _p ) opposite end connected to clamp diode (D _p1 ) anode, clamp diode (D _p1 ) cathode connected to input side inductance (L _in ) The output terminal forms a dual-tube forward converter; the terminal with the same name of the secondary winding (N _s ) of the high-frequency isolation transformer (T ₁ ) is connected to the anode of the output rectifier diode (D ₁ ), and the cathode of the output rectifier diode (D ₁ ) is connected to The positive pole of the output filter capacitor (C _o ), and the negative pole of the filter capacitor (C _o ) are connected to the opposite end of the secondary winding (N _s ) of the high-frequency isolation transformer to form a loop; the input terminal of the load (R _L ) is connected to the filter capacitor (C _o ) the positive pole, and the input terminal of the load (R _L ) is connected to the negative pole of the filter capacitor (C _o ), forming an output filter circuit.

In the present invention, the resonant inductance is the transformer leakage inductance, or an additional independent inductance.

In the present invention, the two-phase dual-transistor forward resonant DC/DC circuit shares a resonant capacitor (Cr), and the duty ratios of the driving signals of the switch tubes in the two-phase circuits are the same and the phases differ by 180 degrees.

The present invention also provides another isolated soft-switching dual-tube forward resonant DC/DC circuit, including a power supply (V _in ) and an output filter capacitor (C _o ); including two parallel DC/DC converter circuit structures; The two DC/DC circuits share a resonant capacitor (Cr), and the duty ratios of the driving signals of the switch tubes in the two-phase circuits are the same and the phases differ by 180 degrees; wherein, the first DC/DC converter includes: two Switch tube (Q ₁ , Q ₂ ), two clamping diodes (D _p1 , D _p2 ), high frequency isolation transformer (T ₁ ), primary winding ( _NP ), secondary winding (N _s ), output rectifier Diode (D ₁ ) and resonant inductance (L _r ); resonant inductance (L _r ) is connected in series with the primary winding of the transformer; one end of the switching tube (Q ₂ ) is connected to the cathode of the clamping diode (D _p1 ), and the switching tube (Q ₂ ) The other end is connected to the cathode of the clamping diode (D _p2 ), and the input end of the resonant inductor (L _r ) connected to the same name end of the primary winding (N _p ) of the high frequency isolation transformer (T ₁ ); the high frequency isolation transformer ( T ₁ ) The opposite end of the primary winding (N _p ) is connected to one end of the switching tube (Q ₁ ) and the anode of the clamping diode (D _p1 ), and the other end of the switching tube (Q ₁ ) is connected to the clamping diode (D _p2 ) The anode of the high-frequency isolation transformer (T ₁ ) secondary winding (N _s ) with the same name is connected to the anode of the output rectifier diode (D ₁ ), and the cathode of the output rectifier diode (D ₁ ) is connected to the positive pole of the output filter capacitor (C _o ) , the negative pole of the filter capacitor (C _o ) is connected to the opposite end of the secondary winding (N _s ) of the high-frequency isolation transformer to form a loop; the input terminal of the load (R _L ) is connected to the positive pole of the filter capacitor (C _o ), and the load (R _L ) input terminal is connected to the negative pole of the filter capacitor (C _o ) to form an output filter circuit; the second DC/DC converter has the same structure as the first DC/DC converter, and: the positive pole of the power supply (V _in ) is connected to The input end of the input side inductance (L _in ), and the output end of the input side inductance (L _in ) are connected to the cathode of the clamping diode (D _p1 ) in the first DC/DC converter and the input end of the resonant capacitor (C _r ); The output terminal of the resonant capacitor (C _r ) is connected to the anode of the clamp diode (D _p4 ) in the second DC/DC converter; the anode of the clamp diode (D _p2 ) in the first DC/DC converter is connected to the power supply (V _in ) negative pole.

The invention belongs to a new isolated soft-switching double-tube forward resonant DC/DC circuit. The circuit includes a double-tube forward conversion circuit and an output filter circuit to convert the input DC voltage. The overlap time between the voltage at both ends of the power switch tube and the current passing through the power switch tube is reduced, thereby achieving the purpose of reducing switching loss.

The soft-switching single-channel dual-transistor forward DC/DC converter circuit of the present invention can reduce the overlapping time of the voltage at both ends of the power switch tube and the current passing through the power switch tube, and reduce the power loss of the switch device. The invention can reduce the energy consumption of the circuit, save energy, improve the energy conversion efficiency, reduce the heat generation of the power switching device, improve the working stability of the circuit, and increase the service life of the device and the circuit. The invention is suitable for DC/DC DC voltage conversion power supply circuit.

Using soft switching technology, using resonant inductance L _r and resonant capacitor C _r in the input stage to generate parallel resonance, so that the power switch tube works in the zero-voltage on and quasi-zero current off state, reducing the voltage and passing power at both ends of the power switch tube The overlapping time of the current of the switching tube reduces the switching loss of the power switching tube.

The beneficial effects produced by the present invention include:

1. Due to the use of soft switching parallel resonance technology at the input end, the power switch tube works in the zero-voltage on and quasi-zero current off states, reducing the overlapping time of the voltage at both ends of the power switch tube and the current passing through the power switch tube, reducing The switching loss of the power switch tube is reduced.

2. Recover the energy on the parasitic inductance or capacitance to improve the energy conversion efficiency.

3. Reduce the energy consumption of the circuit and save energy.

3. Realize high frequency and increase power density.

4. Reduce the heat generation of power switching devices, improve the working stability of the circuit, and improve the service life of devices and circuits.

Description of drawings

Figure 1 is a schematic diagram of the structure of a forward DC/DC converter circuit using an ordinary two-transistor;

Fig. 2 is the structure schematic diagram that the present invention adopts soft-switching single-way dual-transistor forward DC/DC converter circuit;

The equivalent circuit of the soft-switching single-way double-tube forward circuit that Fig. 3 the present invention adopts when ton;

The equivalent circuit of the soft-switching single-channel double-tube forward circuit that Fig. 4 the present invention adopts when tooff;

Fig. 5 schematic diagram of the voltage and current at both ends of the switching tube when the present invention is turned on at zero voltage and turned off at quasi-zero current;

Fig. 6 is a schematic diagram of the voltage and current at both ends of the switch tube when the zero voltage is turned on in the present invention;

Fig. 7 is a schematic diagram of the voltage and current at both ends of the switching tube when the present invention is turned off at zero current;

Figure 8 Two-phase interleaved parallel isolation type soft switch double-tube forward resonant DC/DC circuit;

Figure 9. Isolated soft-switching double-transistor forward resonant DC/DC full-bridge rectifier circuit.

detailed description

The specific implementation manners of the present invention will be described in further detail below in conjunction with the accompanying drawings.

Example 1:

A single-phase isolated soft-switching double-transistor forward resonant DC/DC circuit, the circuit structure of which is shown in Figure 2.

See attached drawing 2. A single-phase isolated soft-switching double-tube forward resonant DC/DC circuit, the power supply V _in and the input inductance L _in form a constant current output; the switch tubes Q ₁ and Q ₂ , the clamping diodes D _p1 and D _p2 , high The primary winding N _P of the frequency isolation transformer T ₁ forms a dual-tube forward converter; the resonant inductor L _r and the resonant capacitor C _r form a parallel resonant circuit; the output rectifier diode D ₁ and the output filter capacitor C _o form an output rectifier filter circuit.

The specific connection method is: the positive pole of the power supply V _in is connected to the input end of the input side inductor L _in , the output end of the input side inductor _Lin is connected to the input end of the resonant capacitor C _r , and the output end of the resonant capacitor C _r is connected to the negative pole of the power supply V _in to form loop; the output end of the input side inductance L _in is also connected to one end of the switch tube _Q2 , and the other end of the switch tube _Q2 is connected to the resonant inductor _Lr connected to the same name end _of the primary winding _Np of the high frequency isolation transformer T1, high frequency isolation Transformer T ₁ primary winding N _p different end is connected to one end of switch tube Q ₁ , and the other end of switch tube Q ₁ is connected to the negative pole of power supply V _in to form a loop; the input end of resonant inductor L _r is connected to the cathode of clamping diode D _p2 to clamp The anode of the diode D _p2 is connected to the negative pole of the power supply V _in ; the opposite end of the primary winding N _p of the high _- frequency isolation transformer T1 is connected to the anode of the clamping diode D _p1 , and the cathode of the clamping diode D _p1 is connected to the output end of the input inductor L _in , It forms a double-tube forward converter _{; the terminal with the same name of the secondary winding N s of} the high-frequency isolation transformer T1 is connected to the anode _of the output rectifier diode D1, and the cathode _of the output rectifier diode D1 is connected to the positive pole of the output filter capacitor C _o , and the filter capacitor C _o The negative pole is connected to the opposite end of the secondary winding N _s of the high-frequency isolation transformer to form a loop; the input terminal of the load R _L is connected to the positive pole of the filter capacitor C _o , and the input terminal of the load R _L is connected to the negative pole of the filter capacitor C _o to form an output filter circuit .

The power supply V _in and the large inductance L _in at the input side can be equivalent to a current source I. The equivalent circuit of the soft-switching single-channel dual-transistor forward DC/DC converter circuit adopted in the present invention at t _off is shown in Fig. 4 . At this time, the switching tube Q1 and the switching tube _Q2 are disconnected, because the switching frequency _of the switching tubes Q1 and _Q2 is _{higher than} the resonance frequency, the circuit load presents an _inductive characteristic, and the voltage phase is ahead of the current phase. Before the current of the upper six strands rises, because the diodes connected in parallel _on the switch tubes Q1 and _Q2 have already conducted current, the voltage at _both ends of the switch tubes Q1 and _Q2 has dropped to the conduction voltage. At this time, the conduction voltage generated by the current rise The conduction loss is not large, and the switch is turned on at zero voltage. The voltage V _ds at both ends of the switch tube and the change of the current flowing through the switch tube are shown in Figure 6, and zero-voltage turn-on occurs. The equivalent circuit of the soft-switching single-channel dual-tube forward DC/DC converter circuit in the present invention at ton is shown in Fig. 3 . At this time, the switching tube Q1 and the switching tube _Q2 are turned _on . When Q1 and _Q2 are turned off, the resonant inductance L _r and the resonant capacitor C _r resonate, and the voltage V _ds at _both ends of the switching tube and the current flowing through the switching tube Changes as shown in Figure 7, a quasi-zero current shutdown occurs.

Example 2:

A two-phase isolated soft-switching dual-transistor forward resonant DC/DC circuit, the circuit structure of which is shown in Figure 8.

The circuit structure of the dual-transistor forward resonant DC/DC circuit can be extended to a DC/DC converter circuit structure in which multiple units are connected in parallel. It is illustrated by a two-phase interleaved parallel dual-tube forward resonant DC/DC circuit: the positive pole of the power supply V _in is connected to the input end of the input side inductance L _in , the output end of the input side inductance L _in is connected to the input end of the parallel resonant capacitor C _r , and connected in parallel The output end of the resonant capacitor C _r is connected to the negative pole of the power supply V _in to form a loop;

The output end of the input side inductance L _in is connected to one end of the switching tube _Q2 , and the other end of the switching tube _Q2 is connected to the resonant inductor L _r1 connected to the same name end of the primary winding _{Np1 of} the high frequency isolation transformer _T1 , and the high frequency isolation transformer T1 The opposite end of the primary winding N _p1 is connected to one end of the switching tube Q ₁ , and the other end of the switching tube Q ₁ is connected to the negative pole of the power supply V _in to form a loop; the input end of the resonant inductor L _r1 is connected to the cathode of the clamping diode D _p2 , and the clamping diode D _p2 The anode is connected to the negative pole of the power supply V _in ; the opposite end of the primary winding N _p1 of the high _- frequency isolation transformer T1 is connected to the anode of the clamping diode D _p1 , and the cathode of the clamping diode D _p1 is connected to the output end of the input inductor L _in , forming the first One-way dual-tube forward converter;

The output end of the input side inductance L _in is connected to one end of the switching tube _Q4 , and the other end of the switching tube _Q4 is connected to the resonant inductor _{Lr2 connected to the same name end of the primary winding Np2 of} the high frequency isolation transformer _T2 , and the high frequency isolation transformer _T2 The opposite end of the primary winding N _p2 is connected to one end of the switch tube _Q3 , and the other end of the switch tube _Q3 is connected to the negative pole of the power supply V _in to form a loop; the input end of the resonant inductor L _r2 is connected to the cathode of the clamp diode D _p4 , and the clamp diode D _p4 The anode is connected to the negative pole of the power supply V _in ; the _{opposite end of the primary winding N p2 of} the high-frequency isolation transformer T2 is connected to the anode of the clamping diode D _p3 , and the cathode of the clamping diode D _p3 is connected to the output end of the input inductor L _in to form the second One-way dual-tube forward converter;

The terminal with the same name of the secondary winding N _s1 of the high-frequency isolation transformer T ₁ is connected to the anode of the output rectifier diode D ₁ , the cathode of the output rectifier diode D ₁ is connected to the positive pole of the output filter capacitor C _o , and the secondary winding N _s2 of the high-frequency isolation transformer T _{2 The} end with the same name is connected to the anode of the output rectifier diode _D2 , the cathode of the output rectifier diode D2 is connected to the positive pole of the output filter capacitor C _o , and the negative pole of the filter capacitor C _o is connected to the opposite end of the secondary winding _Ns1 of the high-frequency isolation transformer to form a loop; The negative pole of the filter capacitor C _o is connected to the opposite end of the secondary winding N _s2 of the high-frequency isolation transformer to form a loop; the input terminal of the load R _L is connected to the positive pole of the filter capacitor C _o , and the input terminal of the load R _L is connected to the negative pole of the filter capacitor C _o . Form the output filter circuit.

Referring to accompanying drawing 9, the control strategy of this two-phase isolated soft-switching double-tube forward resonant DC/DC circuit is _: the driving signals of the switching tubes Q1 and _Q2 are in the same phase and have the same duty cycle; the switching tubes _Q3 and Q The driving signals of ₄ have the same phase and duty ratio; the phase difference between the driving signals of the switching tubes Q1 and Q2 and the driving signals of the switching tubes _Q3 and _Q4 is 180 degrees.

Finally, it should be noted that the above examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and many variations are possible. All deformations that can be directly derived or associated by those skilled in the art from the content disclosed in the present invention should be considered as the protection scope of the present invention.

Claims (4)

1. Isolated soft-switching dual-tube forward resonant DC/DC circuit, including power supply V _in , two switching tubes Q ₁ , Q ₂ , two clamping diodes D _p1 , D _p2 , high-frequency isolation transformer T ₁ , the original Side winding N _P , secondary winding N _s , output rectifier diode D ₁ and output filter capacitor C _o ; it is characterized in that the circuit also includes input side inductance L _in , resonant inductor L _r and resonant capacitor C _r ; resonant capacitor C _r is connected in parallel with the power supply V _in , and the input side inductance L _in is located between the resonant capacitor C _r and the power supply V _in ; the output end of the input side inductance L _in is also connected to one end of the switch tube _Q2 , and the other end of the switch tube _Q2 is connected to the The resonant inductance _{L r} connected to the same-named end of the primary winding N _P of the high _- frequency isolation transformer T1 is connected to _one end _of the switching tube Q1, and the other end _of the switching tube Q1 is connected to The negative pole of the power supply V _in forms a loop; the input terminal _of the resonant inductor _{L r} is connected to the cathode of the clamping diode D _p2 , and the anode of the clamping diode D _p2 is connected to the negative pole of the power supply V _in ; The anode of the clamping diode D _p1 and the cathode of the clamping diode D _p1 are connected to the output end of the input side inductance L _in ; the load composed of the resonant inductance L _r and the resonant capacitor C _r and the output voltage V _o forms a series resonant circuit; the transformer secondary winding N The branch after _s is connected in series with the output rectifier diode D ₁ is connected in parallel with the output capacitor C _o . 2. The double-transistor forward resonant DC/DC circuit according to claim 1, wherein the positive pole of the power supply V _in is connected to the input end of the input side inductance L _in , and the output end of the input side inductance L _in is connected to The input end of the resonant capacitor C _r and the output end of the resonant capacitor C _r are connected to the negative pole of the power supply V _in to form a loop; the output end of the input side inductance L _in is also connected to one end of the switch tube _Q2 , and the other end of the switch tube _Q2 is connected to the high-frequency isolation The resonant inductance L _r connected to the same-named end _of the primary winding N _p of transformer T1, the different-named end of the primary winding N _p of the high-frequency isolation transformer T1 is connected to _one end _of the switch tube Q1, and the other end _of the switch tube Q1 is connected to the power source V _in The negative electrode forms a loop; the input terminal of the resonant inductor L _r is connected to the cathode of the clamping diode D _p2 , and the anode of the clamping diode D _p2 is connected to the negative electrode of the power supply V _in ; the high-frequency isolation transformer T ₁ primary winding N _p different terminal is connected to the clamping diode The anode of D _p1 and the cathode of the clamping diode D _p1 are connected to the output end of the input side inductance L _in to form a double-tube forward converter; the end of the high-frequency isolation transformer T ₁ secondary winding N _s with the same name is connected to the anode of the output rectifier diode D ₁ , the cathode of the output rectifier diode D ₁ is connected to the positive pole of the output filter capacitor C _o , and the negative pole of the filter capacitor C _o is connected to the opposite end of the secondary winding N _s of the high-frequency isolation transformer to form a loop; the input end of the load R _L is connected to the filter capacitor C _o Positive pole, the load R _L output terminal is connected to the filter capacitor C _o negative pole to form an output filter circuit. 3. The dual-transistor forward resonant DC/DC circuit according to claim 1 or 2, wherein the resonant inductance is a transformer leakage inductance, or an additional independent inductance. 4. An isolated soft-switching double-tube forward resonant DC/DC circuit, including a power supply V _in and an output filter capacitor C _o ; it is characterized in that it also includes two parallel DC/DC converter circuits; two DC/DC conversion The converter circuit shares a resonant capacitor Cr, and the duty cycle of the driving signal of the switching tube in the two-phase circuit is the same, and the phase difference is 180 degrees; Wherein, the first DC/DC converter includes: two switching tubes Q ₁ , Q ₂ , two clamping diodes D _p1 , D _p2 , high-frequency isolation transformer T ₁ , primary winding N _P , secondary winding N _s , output rectifier diode D ₁ and resonant inductance L _r ; resonant inductance L _r is connected in series with the primary winding of the transformer; one end of the switch tube Q ₂ is connected to the cathode of the clamping diode D _p1 , and the other end of the switch tube Q ₂ is connected to the clamping diode D The cathode of _p2 , the input end of the resonant inductance L _r connected to the same-named end of the primary _{winding Np of} the high _- frequency isolation transformer T1 _; The anode of the clamping diode D _p1 , the other end of the switching tube Q ₁ is connected to the anode of the clamping diode D _p2 ; the terminal of the same name of the secondary winding N _s of the high frequency isolation transformer T ₁ is connected to the anode of the output rectifier diode D ₁ , and the output rectifier diode The cathode of D ₁ is connected to the positive pole of the output filter capacitor C _o , and the negative pole of the filter capacitor C _o is connected to the opposite end of the secondary winding N _s of the high-frequency isolation transformer to form a loop; the input terminal of the load R _L is connected to the positive pole of the filter capacitor C _o , and the load The output terminal of R _L is connected to the negative pole of the filter capacitor C _o to form an output filter circuit; The second DC/DC converter has the same structure as the first DC/DC converter, and: the positive pole of the power supply V _in is connected to the input end of the input side inductance L _in , and the output end of the input side inductance L _in is connected to the first The negative pole of the clamping diode D _p1 in a DC/DC converter, the input terminal of the resonant capacitor C _r ; the output terminal of the resonant capacitor C _r is connected to the positive pole of the clamping diode D _p4 in the second DC/DC converter; the first DC/ The anode of the clamping diode D _p2 in the DC converter is connected to the cathode of the power source V _in .