阅读说明：本技术 一种能量前馈型buck软开关电路及装置 (Energy feedforward type buck soft switching circuit and device ) 是由 张强 郑雪钦 张达敏 林智勇 于 2019-09-16 设计创作，主要内容包括：本发明提供了一种能量前馈型buck软开关电路及装置,包括：buck电路、辅助软开关电路；buck电路包括电源、主开关回路、负载及滤波回路,辅助软开关电路包括：变压器、谐振回路、第一辅助开关回路及第二辅助开关回路；电源通过第一辅助开关回路与变压器的原边回路电气连接,其中,变压器的原边回路包括谐振回路及原边绕组,谐振回路与原边绕组电气连接,滤波回路通过主开关回路与变压器的原边回路电气连接,变压器的副边回路通过第二辅助开关回路与负载电气连接；谐振回路的能量通过变压器传至负载。基于本发明,通过辅助软开关电路及变压器的配合,在实现软开关的同时,将谐振能量直接传至负载,提高电能的转化效率。(The invention provides an energy feedforward type buck soft switching circuit and a device, comprising: buck circuit, auxiliary soft switching circuit; buck circuit includes power, main switch return circuit, load and filtering circuit, and supplementary soft switch circuit includes: the circuit comprises a transformer, a resonant circuit, a first auxiliary switch circuit and a second auxiliary switch circuit; the power supply is electrically connected with a primary side loop of the transformer through a first auxiliary switch loop, wherein the primary side loop of the transformer comprises a resonance loop and a primary side winding, the resonance loop is electrically connected with the primary side winding, a filter loop is electrically connected with the primary side loop of the transformer through a main switch loop, and a secondary side loop of the transformer is electrically connected with a load through a second auxiliary switch loop; the energy of the resonant tank is transferred to the load through the transformer. Based on the invention, through the matching of the auxiliary soft switching circuit and the transformer, the resonant energy is directly transmitted to the load while the soft switching is realized, and the conversion efficiency of the electric energy is improved.)

1. An energy feed-forward buck soft switching circuit, comprising: buck circuit, auxiliary soft switching circuit;

the buck circuit includes power, main switch return circuit, load and filtering circuit, supplementary soft switch circuit includes: the circuit comprises a transformer, a resonant circuit, a first auxiliary switch circuit and a second auxiliary switch circuit;

the power supply is electrically connected with a primary side loop of the transformer through the first auxiliary switch loop, wherein the primary side loop of the transformer comprises a resonance loop and a primary side winding, the resonance loop is electrically connected with the primary side winding, the filter loop is electrically connected with the primary side loop of the transformer through the main switch loop, and a secondary side loop of the transformer is electrically connected with the load through the second auxiliary switch loop; the energy of the resonant tank is transferred to the load through the transformer.

2. An energy feed-forward type buck soft switching circuit as claimed in claim 1, wherein the first auxiliary switching loop comprises a first field effect transistor and a first diode;

the D pole of the first field effect transistor is electrically connected with the positive pole of the power supply, the S pole of the first field effect transistor is electrically connected with the negative pole of the first diode, and the positive pole of the first diode is electrically connected with the negative pole of the power supply.

3. An energy feed-forward buck soft switching circuit as claimed in claim 2, wherein the main switching loop includes a second fet and a second diode;

the D pole of the second field effect transistor is electrically connected with the positive pole of the power supply, the S pole of the second field effect transistor is electrically connected with the negative pole of the second diode, and the positive pole of the second diode is electrically connected with the negative pole of the power supply.

4. An energy feed forward buck soft switching circuit as claimed in claim 3, wherein the resonant tank includes: a first inductor and a first capacitor;

the first end of the first inductor is electrically connected with the negative electrode of the first diode, the second end of the first inductor is electrically connected with the first end of the primary winding, the second end of the primary winding is electrically connected with the negative electrode of the second diode, and the first capacitor is connected in parallel with two ends of the first diode.

5. An energy feed-forward buck soft switching circuit as claimed in claim 4, wherein the filter loop comprises: a second capacitor and a second inductor;

the first end of the second inductor is electrically connected with the cathode of the first diode, and the second end of the second inductor is electrically connected with the anode of the second diode through the second capacitor.

6. An energy feed-forward buck soft switching circuit as claimed in claim 1, wherein the secondary side loop of the transformer comprises: a secondary winding and a third diode;

the first end of the secondary winding is electrically connected with the positive electrode of the third diode, the negative electrode of the third diode is electrically connected with the first end of the load, and the second end of the load is electrically connected with the second end of the secondary winding.

7. An energy feedforward type buck soft switching apparatus, comprising an energy feedforward type buck soft switching circuit according to any one of claims 1 to 6.

Technical Field

The invention relates to the field of buck chopping, in particular to an energy feedforward buck soft switching circuit and device.

Background

With the continuous development of science and technology, higher requirements are put forward on the efficiency, power density and reliability of a DC/DC converter, in the prior art, please refer to the transformer TR scheme in fig. 1(a), in the whole working process of a resonant inductor Lr, energy is fed back to an input power supply E through D4, which is equivalent to the fact that resonant energy circulates between Lr and E, in the transformer ATR scheme in fig. 1(b), in the rising process of iLr, resonant current circulates in a self-coupling transformer; however, the energy of Lr is finally fed back to the input power E through D3, referring to fig. 2, considering the influence of the parasitic capacitance and the leakage inductance of the coupling inductor of the actual device S, D, the problem of oscillation is serious, which results in excessive voltage and current stress, and meanwhile, the resonant energy is transmitted to the output side through the coupling inductor after two conversions, as mentioned above, the resonant energy in the prior art is fed back to the input power, or transmitted to the output side after two conversions, which will affect the improvement of efficiency. Meanwhile, the partial scheme also has the problems of overlarge voltage and current stress.

Disclosure of Invention

In view of this, the invention discloses an energy feedforward type buck soft switching circuit and device, which realize soft switching and directly transmit resonance energy to a load by matching an auxiliary soft switching circuit and a transformer, so that the conversion efficiency of electric energy is improved.

The first embodiment of the present invention provides an energy feedforward type buck soft switching circuit, including: buck circuit, auxiliary soft switching circuit;

the buck circuit includes power, main switch return circuit, load and filtering circuit, supplementary soft switch circuit includes: the circuit comprises a transformer, a resonant circuit, a first auxiliary switch circuit and a second auxiliary switch circuit;

the power supply is electrically connected with a primary side loop of the transformer through the first auxiliary switch loop, wherein the primary side loop of the transformer comprises a resonance loop and a primary side winding, the resonance loop is electrically connected with the primary side winding, the filter loop is electrically connected with the primary side loop of the transformer through the main switch loop, and a secondary side loop of the transformer is electrically connected with the load through the second auxiliary switch loop; the energy of the resonant tank is transferred to the load through the transformer.

Preferably, the first auxiliary switch loop comprises a first field effect transistor and a first diode;

the D pole of the first field effect transistor is electrically connected with the positive pole of the power supply, the S pole of the first field effect transistor is electrically connected with the negative pole of the first diode, and the positive pole of the first diode is electrically connected with the negative pole of the power supply.

Preferably, the main switch loop comprises a second field effect transistor and a second diode;

the D pole of the second field effect transistor is electrically connected with the positive pole of the power supply, the S pole of the second field effect transistor is electrically connected with the negative pole of the second diode, and the positive pole of the second diode is electrically connected with the negative pole of the power supply.

Preferably, the resonant tank comprises: a first inductor and a first capacitor;

the first end of the first inductor is electrically connected with the negative electrode of the first diode, the second end of the first inductor is electrically connected with the first end of the primary winding, the second end of the primary winding is electrically connected with the negative electrode of the second diode, and the first capacitor is connected in parallel with two ends of the first diode.

Preferably, the filter circuit comprises: a second capacitor and a second inductor;

the first end of the second inductor is electrically connected with the cathode of the first diode, and the second end of the second inductor is electrically connected with the anode of the second diode through the second capacitor.

Preferably, the secondary side loop of the transformer comprises: a secondary winding and a third diode;

the first end of the secondary winding is electrically connected with the positive electrode of the third diode, the negative electrode of the third diode is electrically connected with the first end of the load, and the second end of the load is electrically connected with the second end of the secondary winding.

A second embodiment of the present invention provides an energy feedforward type buck soft switching apparatus, including an energy feedforward type buck soft switching circuit as described in any one of the above.

According to the energy feedforward type buck soft switching circuit and the device provided by the embodiment of the invention, the zero voltage of the main switching loop is switched on and off, the zero current switch of the auxiliary switching loop, the transformer and the third diode form a forward working mode, the input power supply directly supplies power to the load, the energy waste caused by multiple times of conversion and transmission of electric energy when the electric energy is transmitted to the load is avoided, and the conversion efficiency of the electric energy can be effectively improved by directly transmitting the resonance energy to the load through the transformer.

Drawings

FIG. 1 is a schematic circuit diagram of a technical solution of TR and ATR in the prior art;

FIG. 2 is a schematic circuit diagram of a prior art solution in which a coupling inductor is transformed to be transmitted to an output side;

FIG. 3 is a schematic diagram of an energy feed-forward buck soft switching circuit according to an embodiment of the present invention;

FIG. 4 is a schematic waveform of an energy feedforward type buck soft switching circuit according to an embodiment of the present invention during steady-state operation;

fig. 5 is an equivalent circuit before TO time of the energy feedforward type buck soft switching circuit provided by the embodiment of the invention;

FIG. 6 is an equivalent circuit of the energy feedforward type buck soft switch circuit at time T0-T1;

FIG. 7 is an equivalent circuit of the energy feedforward type buck soft switching circuit at time T1-T2;

FIG. 8 is an equivalent circuit of the energy feedforward type buck soft switching circuit provided by the embodiment of the invention at the time T2-T3;

FIG. 9 is an equivalent circuit of the energy feedforward type buck soft switch circuit at time T3-T4;

FIG. 10 is an equivalent circuit of the energy feed-forward type buck soft switching circuit provided by the embodiment of the invention at the time T4-T5;

FIG. 11 is an equivalent circuit of the energy feedforward type buck soft switching circuit at time T5-T6;

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.

The following detailed description of specific embodiments of the invention refers to the accompanying drawings.

The invention discloses an energy feedforward type buck soft switching circuit and device.

Referring to fig. 3, a first embodiment of the invention provides an energy feed-forward buck soft switching circuit, which includes: buck circuit, auxiliary soft switching circuit;

the buck circuit comprises a power supply, a main switch loop, a load RL and a filtering loop, and the auxiliary soft switch circuit comprises: the circuit comprises a transformer, a resonant circuit, a first auxiliary switch circuit and a second auxiliary switch circuit;

the power supply is electrically connected with a primary side loop of the transformer through the first auxiliary switch loop, wherein the primary side loop of the transformer comprises a resonance loop and a primary side winding N1, the resonance loop is electrically connected with the primary side winding, the filter loop is electrically connected with the primary side loop of the transformer through the main switch loop, and a secondary side loop of the transformer is electrically connected with the load RL through the second auxiliary switch loop; the energy of the resonant tank is transferred to the load RL through the transformer.

It should be noted that, the conduction time periods of the main switch loop and the first control switch loop are controlled by inputting control signals from the outside, so that different switches of the loops perform soft switching operation at different time periods, and the resonant energy is directly transmitted to the load RL by the cooperation of the transformer and the second auxiliary switch loop.

In the embodiment, the first auxiliary switch loop comprises a first field effect transistor Q1 and a first diode D1;

wherein the D pole of the first FET Q1 is electrically connected to the positive pole of the power source, the S pole of the first FET Q1 is electrically connected to the negative pole of the first diode D1, and the positive pole of the first diode D1 is electrically connected to the negative pole of the power source.

It should be noted that the G pole of the first fet Q1 is configured to receive an external control signal, so that the first fet Q1 is periodically turned on, and the first diode D1 is configured to freewheel in a loop, where here, the first fet Q1 is preferably an N-channel fet, and in other embodiments, it may also be a P-channel fet, and it may also be other types of fully-controlled devices such as an IGBT, a GTR, and the like, which are not specifically limited herein, and these schemes may be correspondingly configured according to actual situations, but all of these schemes are within the protection scope of the present invention.

In this embodiment, the main switch circuit includes a second fet Q2 and a second diode D2;

the D pole of the second field effect transistor Q2 is electrically connected with the positive pole of the power supply, the S pole of the second field effect transistor Q2 is electrically connected with the negative pole of the second diode D2, and the positive pole of the second diode D2 is electrically connected with the negative pole of the power supply.

It should be noted that the G pole of the second fet Q2 is configured to receive an external control signal, so that the second fet Q2 is periodically turned on, and the second diode D2 is configured to avoid a current from directly flowing back to a power supply, where here, the second fet Q2 is preferably an N-channel fet, and in other embodiments, may also be a P-channel fet, and may also be other types of fully-controlled devices such as an IGBT and a GTR, which are not specifically limited herein, and these schemes may be correspondingly configured according to actual situations, but all of these schemes are within the protection scope of the present invention.

In this embodiment, the resonant tank includes: a first inductor L1 and a first capacitor C1;

the first end of the first inductor L1 is electrically connected to the negative electrode of the first diode D1, the second end of the first inductor L1 is electrically connected to the first end of the primary winding N1, the second end of the primary winding N1 is electrically connected to the negative electrode of the second diode D2, the first capacitor C1 is connected in parallel to two ends of the first diode D1, and the first inductor L1 is used for storing energy, resonating, and supplying power from an input power source to a load RL while storing energy.

It should be noted that the essence of resonance is that the electric field in the first capacitor C1 and the magnetic field in the first inductor L1 can be switched, and this increase and decrease are completely compensated. The sum of the electric field energy and the magnetic field energy is kept unchanged all the time, and the power supply does not need to convert energy back and forth with a capacitor or an inductor and only needs to supply electric energy consumed by a resistor in the circuit.

In this embodiment, the filter circuit includes: a second capacitor C2 and a second inductor L2;

a first terminal of the second inductor L2 is electrically connected to the cathode of the first diode D1, and a second terminal of the second inductor L2 is electrically connected to the anode of the second diode D2 through the second capacitor C2.

The second capacitor C2 and the second inductor L2 are provided to form a passive filter circuit, and the filter circuit functions to reduce the ac component in the pulsating dc voltage as much as possible, retain the dc component thereof, reduce the ripple factor of the output voltage, and make the waveform smoother

In this embodiment, the secondary side loop of the transformer includes: a secondary winding N2 and a third diode D3;

a first end of the secondary winding N2 is electrically connected to an anode of the third diode D3, a cathode of the third diode D3 is electrically connected to a first end of the load RL, and a second end of the load RL is electrically connected to a second end of the secondary winding N2.

It should be noted that the third diode D3 is used to cooperate with the first diode D1 to form a forward working mode, so as to directly supply the energy stored in the first inductor L1 to the load RL.

Referring to fig. 4 and 5, fig. 4 is a schematic waveform diagram of the circuit in steady-state operation, assuming that the second capacitor C2 and the second inductor L2 of the resonant circuit are large enough to ignore high-frequency ripples, iL2 and Uo are constant values, fig. 5 is an equivalent circuit diagram of the circuit before time t0, and the first diode D1 freewheels when iL2 passes through, and operates like a hard switch buck.

Referring to fig. 6, fig. 6 is an equivalent circuit when the voltage enters a time period [ t0, t1], at a time t0, the second fet Q2 turns on the first fet Q1 in advance, iL1 starts to rise linearly from 0, but iL1< iL2, D1 is still turned on, the first inductor L1 forms a forward working mode with the third diode D3 through the transformer while storing energy, and an input power directly supplies power to a load RL.

Referring to fig. 7, fig. 7 is an equivalent circuit when the current enters a time period [ t1, t2], at a time t1, where iL1 is iL2, iD1 is 0, the first diode D1 is turned off softly, the first inductor L1 and the first capacitor C1 start a resonance process (the resonance frequency is far greater than the frequency of the fet), the voltage of the first capacitor C1 gradually rises, the voltage of the corresponding first fet Q1 gradually falls, and after a resonance period of 1/4, the current of the first inductor L1 reaches a maximum value.

Referring to fig. 8, fig. 8 is an equivalent circuit when the time period of [ t2, t3] is entered, at time t2, the voltage of the first fet Q1 drops to zero, the parasitic diode of the first fet Q1 is turned on, and to provide a condition for achieving zero-voltage turn-on of the first fet Q1, the current of the first inductor L1 linearly drops under the action of the output emission voltage until the current of the first inductor L1 is equal to the current of the second inductor L2, so long as a turn-on signal is given at this stage, the first fet Q1 can achieve zero-voltage turn-on.

Referring to fig. 9, fig. 9 is an equivalent circuit when the current enters a time period [ t3, t4], after a time point t3, the current of the first inductor L1 is smaller than the current of the second inductor L2, the current flows through the first fet Q1 until the current of the first inductor L1 is zero, and then the second fet Q2 is turned off, so that zero current turn-off between the second fet Q2 and the third diode D3 can be realized.

Referring to fig. 10, fig. 10 shows the equivalent circuit when the current enters the time period [ t4, t5], after the time point t4, the current of the auxiliary soft switching loop is zero, and the normal conduction process of S1 is entered, where the current of the first fet Q1 is equal to the current of the second inductor L2.

Referring to fig. 11, fig. 11 is an equivalent circuit when the equivalent circuit enters a time period [ t5, t6], at a time point t5, the first fet Q1 is turned off, and the voltage of the first fet Q1 rises linearly due to the action of the first capacitor C1, and falls linearly corresponding to the voltage of the first diode D1. The first fet Q1 achieves approximately zero voltage turn off. Until time t6, the voltage of the first capacitor C1 drops to zero, the first diode D1 is turned on, and a free-wheeling path is provided for the current of the second inductor L2, and the current returns to a free-wheeling state before t0, and waits for the next switching cycle.

A second embodiment of the present invention provides an energy feedforward type buck soft switching apparatus, including an energy feedforward type buck soft switching circuit as described in any one of the above.

According to the energy feedforward type buck soft switching circuit and the device provided by the embodiment of the invention, the zero voltage of the main switching loop is switched on and off, the zero current switch of the auxiliary switching loop, the transformer and the third diode form a forward working mode, the input power supply directly supplies power to the load, the energy waste caused by multiple times of conversion and transmission of electric energy when the electric energy is transmitted to the load is avoided, and the conversion efficiency of the electric energy can be effectively improved by directly transmitting the resonance energy to the load through the transformer.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention.