WO2017012328A1

WO2017012328A1 - Phase-shift full-bridge topology circuit for single-stage power factor correction

Info

Publication number: WO2017012328A1
Application number: PCT/CN2016/072691
Authority: WO
Inventors: 孙伟峰; 张太之; 苏畅; 俞居正; 钱钦送; 陆生礼; 时龙兴
Original assignee: 东南大学
Priority date: 2015-07-17
Filing date: 2016-01-29
Publication date: 2017-01-26
Also published as: CN104917412A

Abstract

A phase-shift full-bridge topology circuit for single-stage power factor correction comprises an input energy storage capacitor (1), an input rectification circuit (2), a full-bridge arm circuit (6), a direct current blocking capacitor (7), a transformer (8) and an output rectification filter circuit (9). The phase-shift full-bridge topology circuit is additionally provided with an input inductor (3) and a free-wheeling circuit (4) composed of a free-wheeling switching tube (Q_f) and a free-wheeling diode (D_f), the free-wheeling circuit is connected in parallel with the input inductor, after the parallel connection, one end is connected to an output end of the input rectification circuit, the other end is connected to the full-bridge arm circuit, and a lower switching tube (Q₂) of a lead leg in the full-bridge arm circuit is multiplexed as a switch in a booster circuit to implement rectification, so as to implement single-stage power factor correction together with the input inductor. The phase-shift full-bridge topology circuit implements a two-stage circuit with a power factor correction function and a phase-shift full-bridge topology structure by a single-stage circuit, thereby improving the power density of a full-bridge circuit having a power factor correction function, and the circuit has a simple structure, low costs and high reliability.

Description

Single-stage power factor correction phase-shifted full-bridge topology circuit

Technical field

The present invention relates to a full-bridge topology circuit for charging, and more particularly to a single-stage power factor correction (PFC) phase-shifted full-bridge topology circuit.

Background technique

In recent years, the motor drive and energy storage technologies of hybrid vehicles have developed rapidly, and at the same time, battery chargers have become a key requirement for the development of hybrid vehicles.

The well-known charger topology is a two-stage structure. The first stage is usually a boost converter that is used to implement power factor correction (PFC). The second stage is typically a high efficiency isolated dc-dc converter that is used to electrically isolate and control the charging current. In general, full-bridge converters are the most common topology when the output power is in the range of 1-5 kW. However, in the two-stage architecture, the cost and complexity of the overall circuit is greatly improved by the addition of an additional switching converter to the first stage. In addition to this, the efficiency of the entire circuit is also affected.

In some existing single-stage structures, the resonant full-bridge converter can achieve high power factor and constant output voltage by using series-parallel resonance changes. However, such switching tubes require greater voltage stress and variable switching frequency. Control, which brings about problems such as magnetic components and complex filter design, limits its scope of application. There are also some current feedback filters that rectify the input current by turning on the switching tubes on one or both of the bridge arms. To solve the voltage overshoot and ringing problems of this type of topology, a buffer is generally added to the circuit. Such as input storage capacitors to eliminate overshoot and ringing, which in turn will reduce the conversion efficiency of the entire circuit.

Summary of the invention

In order to realize PFC, electrical isolation and charging current control by using a single-stage topology, the present invention proposes a single-stage power factor correction (PFC) phase-shifted full-bridge topology circuit, which reduces cost and circuit complexity, and simultaneously The function of the two-level topology is realized.

To achieve the above object, the present invention adopts the following technical solution: a single-stage power factor correction phase-shifted full-bridge topology circuit, including an input storage capacitor, an input rectifier circuit, a full bridge arm circuit, a DC blocking capacitor, a transformer, and an output rectification filter. The circuit, the input storage capacitor is connected in parallel with the full bridge arm circuit, the DC blocking capacitor, the transformer, the output rectification filter circuit and the charged battery are connected in series, connected to the output end of the full bridge arm circuit, input to the storage circuit, the input rectifier circuit, The common ground terminal of the full bridge arm circuit and the DC blocking circuit is connected to the input end ground, and the ground end of the output rectifying and filtering circuit is connected to the output end ground, and is characterized in that: an input inductor L and a freewheeling circuit are added, and the freewheeling circuit and the input inductor L are connected in parallel. One end of the parallel connection, one end is connected to the output end of the input rectifier circuit, the other end is connected to the full bridge arm circuit, and the lower switch tube of the lead bridge arm in the full bridge arm circuit is reused as a switch tube in the boost circuit to achieve rectification, Single stage with input inductor L Power factor correction; where:

One end of the input inductor L is connected to the output end of the input rectifier circuit, and the other end of the input inductor L is connected to the connection point of the upper and lower switch tubes of the front bridge arm in the full bridge arm circuit;

Freewheeling circuit comprising the freewheeling switch Q _f and the freewheeling diode D _f, the freewheeling switch L has one end connected to the drain of Q _f input inductor, freewheeling switch tube connecting the source level Q _f the freewheeling diode D _f of the negative electrode The anode of the freewheeling diode D _f is connected to the other end of the input inductor L.

The invention has the following advantages:

1) The present invention realizes a two-stage circuit with a power factor correction function and a phase-shifted full-bridge topology structure by using a primary circuit, which greatly improves the power density of a full-bridge circuit with PFC function, and has a simple structure, low cost, and reliability. High sex.

2) While implementing power factor correction, the output of the system with higher power (>500W) can be guaranteed.

3) Multiple switching of one of the full-bridge converter arms is used to achieve power factor correction, which makes the circuit topology simple, low cost, and good in effect and reliability.

4) The circuit operates at a constant switching frequency, the control mode is simple and easy, and the input current offset is small.

5) The working mode and process are similar to the standard phase-shifted full-bridge converter. The zero-voltage turn-on of the switch can be realized, which reduces the loss of the circuit and improves the achievability of the circuit.

6) Since the input inductor is added, the circuit operates in the "pseudo-continuous current mode", and the output voltage is controllable.

DRAWINGS

Figure 1 is a schematic diagram of the operation of the circuit of the present invention;

Figure 2 is an operational waveform of the circuit of the present invention;

3 is a measured waveform of an input current and a voltage of the circuit of the present invention;

Figure 4 is a graph showing the measured PF value and efficiency of the circuit of the present invention.

detailed description

1, a single-stage power factor correction (PFC) phase-shifted full-bridge topology circuit of the present invention includes an input storage capacitor (C _F ), an input rectifier circuit 2, a full bridge arm circuit 6, and a DC blocking capacitor (C _{b ).} 7, transformer 8 and output rectification filter circuit 9, the above circuit is a known structure of single-stage power factor correction. The input storage capacitor C _F is connected in parallel with the full bridge arm circuit 6. The DC blocking capacitor C _b , the transformer 8 , the output rectifying and filtering circuit 9 and the charged battery Battery _are sequentially connected in series, and are connected to the output end of the full bridge arm circuit 6 and input. The common ground terminal of the storage capacitor C _F , the input rectifier circuit 2 , the full bridge arm circuit 6 and the DC blocking capacitor C _b is connected to the input terminal, and the ground terminal of the output rectifier filter circuit 9 is connected to the output terminal ground.

On the basis of the above circuit, the present invention adds an input inductor (L) 3 and a freewheeling circuit 4, and the freewheeling circuit 4 and the input inductor L are connected in parallel. The two ends of the parallel connection are respectively connected to the output end of the input rectifier circuit 2 and the bridge arm. Circuit 6, and complex The lower switching transistor circuit 5 of the leading arm of the full bridge arm circuit 6 is used as a switching tube in the boost circuit to realize rectification, and the input inductor L is used together to realize single-stage power factor correction.

The positive terminal of the input storage capacitor C _F is connected to the common end of the two upper tubes of the full bridge arm circuit 6 , and the negative end of the C _F is connected to the input terminal common ground. C _F is applied to the input bus and is used in the circuit to reduce voltage overshoot and ringing on the input bus.

The input rectifier circuit 2 performs full-wave rectification of the AC input, including an AC input V _I and a rectifier bridge composed of four diodes. The AC input V _I is connected between the two bridge arms of the rectifier bridge at both ends, and the output end of the rectifier bridge is connected to the input. One end of the inductor L and the other end are connected to the input common ground.

The full bridge arm circuit 6 includes four switching tubes Q ₁ , Q ₂ , Q ₃ , Q ₄ , Q ₁ and Q ₂ constitute a leading bridge arm, and Q ₃ and Q ₄ constitute a lag bridge arm. At the same time, the lower switching tube Q _{2 of the} leading bridge arm is multiplexed to form a multiplexing circuit 5, which is rectified as a switching tube in the boost circuit, so that there is no need to add a boost circuit to implement the PFC in the circuit. The multiplexing circuit 5, the full bridge arm circuit 6, the DC blocking capacitor 7, the transformer 8 and the output rectifying and filtering circuit 9 together constitute a standard full bridge converter.

The DC blocking capacitor (C _b ) 7 is an electrolytic capacitor C _b , the positive terminal is connected to the output of the full bridge arm 6 , and the negative terminal is connected to the input terminal of the transformer 8 , which isolates the DC output of the full bridge arm from the rear transformer to avoid The transformer is biased to cause the core to saturate.

The transformer 8 is composed of a power transformer T _r and a transformer excitation inductance L _m equivalently, L _m and T _r primary windings are connected in parallel, the primary side is connected to the output of the full bridge arm, the secondary winding leads three taps, and the output rectifier filter circuit is connected. 9, to achieve energy transfer and voltage conversion.

The output rectification filter circuit 9 includes two diodes D _R1 and D _R2 and a filter inductor L _o and a capacitor C _o . The anodes of the two diodes D _R1 and D _R2 are respectively connected to the first and third taps of the transformer secondary winding. , and a cathode sequentially together with the filter inductor L _o, the filter capacitor C _o, B _attery batteries to be charged in series, the last access intermediate tap of the secondary winding of the transformer. And two diodes D _R1 D _R2, the filter inductor and the capacitance C _o L _o together form a full-wave rectifier circuit, the DC positive and negative non-rectified voltage output from the transformer 8 becomes a DC voltage supplied from the battery B _attery charge.

The input inductor (L) 3 is connected to the switch transistor Q ₂ , and the input inductor L is used as a freewheeling inductor in the boost circuit for realizing the PFC, and the single-stage PFC function is realized together with the switch transistor Q ₂ . One end of the L is connected to the output end of the input rectifying circuit 2, and the other end is connected to the connection point A of the upper and lower switching tubes of the front arm of the bridge arm circuit, that is, one end of the full bridge arm 6 is output.

Freewheeling circuit comprising the freewheeling 4 Q _f power switch and freewheeling diode D _f, L the inductance of the input end connected to the drain-wheeling power switch Q _f freewheeling power MOSFET switch connected to the source level Q _f the freewheeling diode D _f of the negative electrode, a positive freewheeling diode D _f is connected to the other end of the inductor L is input. The freewheeling power switch Q _f and the diode D _f are connected in parallel on both sides of the input inductor L. The addition of a freewheeling MOSFET (Q _f ) and a freewheeling diode (D _f ) separates the boost and full bridge conversion power conversion processes, eliminating the mutual limitation between the two stages.

To simplify the analysis, assume that all components are ideal and ignore the leakage inductance of the transformer. Assuming that the duty cycle of the drive signal of the switch Q ₂ is d _a , the inductor current I _L rises within the time interval d _a T . Under the control of the pseudo current continuous mode, d _{a is} constant (typical switching frequency 100 Hz), and the operating state of the circuit is similar to that of the phase-shifted full-bridge converter. V _CF is a constant value in the pseudo current continuous mode, the duty ratios of the switching tubes Q ₄ and Q ₂ are equal, and the gate driving signals of the switching tubes Q ₁ and Q ₃ are complementary to Q ₂ and Q ₄ respectively, that is, when converting The upper tube on the bridge arm is opened and the lower tube is closed, and vice versa. The charging current is controlled by the phase shift of the gate drive signal on the two bridge arms, and the phase shift difference between the two bridge arms is

Although the positive and negative voltages of the primary side of the transformer are asymmetrical, the volt-second balance can still be achieved. When da is less than 0.5, the bridge arms of the switch tubes Q ₁ and Q ₂ are super forearms, and vice versa. The input inductor current I _{L is} decreased, and the capacitor C _{F is} charged for a time interval of d _b T. During this time interval, the switching transistors Q ₂ and Q _f are both turned off. Let Q ₂ turn off and Q _f turn on for d _c T. During this time, the input inductor current is in freewheel mode and remains unchanged.

In conjunction with Figure 2, the analysis circuit operates in the following modes.

Modal 1 (t ₀ <t<t ₁ ): At t=t ₀ , the switching transistor Q _{2 is} turned on. During the entire modality 1, the switching tubes Q ₂ and Q ₄ are kept in an open state. The primary voltage V _{AB of the} transformer is zero and the leakage current of the transformer is reduced. No energy is transferred to the storage capacitor C _F . The primary current of the transformer is given by

Where n is the turns ratio of the transformer, V _o is the output voltage of the converter, L _o is the output inductance, and L _r is the series resonant inductor value of the transformer.

At the same time, since the switching transistor Q _{2 is} in the on state, the input voltage is applied across the input inductor L, and the current flowing through the inductor L increases, and the current in the inductor is given by

Where V _m is the leakage inductance voltage, I _REF (t _p ) represents the average value of the input current of the previous period, and L is the input inductance value.

When the switch Q _{4 is} turned off and Q _{3 is} turned on, the mode 1 ends. The discussion here ignores the dead time, and the zero voltage turn-on of switch Q ₃ is done during the dead time.

Modal 2 (t ₁ <t<t ₂ ): At t=t ₁ , the switching transistor Q _{3 is} turned on. During this modality, energy is transferred from the dc bus to the output via the transformer. The forward voltage V _CF is applied to the series inductance of the resonant inductor and the refractive inductance of the output inductor on the primary side. Therefore, in this mode, the current flowing through the primary side of the transformer and the output inductor rises. The primary current of the transformer is given by

Where V _CF is the voltage value on the storage capacitor, and the positive voltage direction is as shown in Figure 1.

The current in the inductor is given by

Mode 2 ends when switch Q _{2 is} turned off. The length of time of modal 1 and modal 2 is the time interval d _a T.

Modal 3 (t ₂ <t<t ₃ ): At t=t ₂ , the switching transistor Q _{2 is} turned off and Q _{1 is} turned on. Since the switching transistor Q _{2 is} turned off, the energy transfer ends, and the primary current continues to flow through the switching transistors Q ₁ and Q ₃ . The primary current of the transformer is given by

At the same time, the energy stored in the input inductor L charges the storage capacitor C _F and the voltage across the input inductor L

Given by

V _L =|V _m sinωt|-V _CF (6)

When V _{CF is} greater than V _m , the input inductor current begins to decrease. The current in the inductor is given by

When the switch Q _{f is} turned on, the mode 3 ends, and the current in the inductor L is equal to the average reference current of the current cycle, that is,

I _L (t ₃ )=I _REF (t ₃ ) (8)

Mode 4 (t ₃ <t<t ₄ ): At t=t ₃ , the switching transistor Q _{f is} turned on, and the primary current of the transformer continues to flow by the switching tubes Q ₁ and Q ₃ , and the value is given by

Since the switching transistor Q _{f is} turned on, the voltage across the input inductor is approximately zero, and the current flowing through the input inductor is unchanged, and the value is given by

I _L (t)=I _REF (t ₃ ) (10)

When the switch Q _{4 is} turned on and Q _{3 is} turned off, the mode 4 ends.

Mode 5 (t ₄ <t<t ₅ ): At t=t ₄ , the switching transistor Q _{4 is} turned on, and energy is again transmitted from the dc bus to the output via the transformer, and the forward voltage V _CF is applied to the resonant inductor and the output. The inductance of the inductor on the primary inductance of the series inductance, the current flowing through the primary side of the transformer and the output inductor rises, the value is given by

Since the switching transistor Q _{f is} still open, the current flowing through the input inductor remains unchanged, ie

I _L (t)=I _REF (t ₃ ) (12)

When the switch Q _{2 is} turned on, this mode ends and the next duty cycle is started (t ₅ <t<t ₁₀ ).

Analysis of these modalities shows that with the present invention, the choice of duty cycle d _a for rectifying the input current is no longer limited, and with reasonable driver and transformer turns ratio design, the input voltage is not adjusted. Can cause an imbalance in the input current. Since the duty cycle d _a can be set close to 0.5, the turns ratio of the transformer can be designed to be larger, and the current loss of the reduced current can be reduced. It can be seen from the actual measurement of Fig. 3 that the input current has good consistency with the input voltage, the PF value is high, and the power factor correction effect of the circuit is good. It can be seen from the actual measurement of Fig. 4 that the efficiency and PF value of the circuit in the full power range are relatively high. In addition, the working mode and process of the present invention are similar to a standard phase-shifted full-bridge converter, and the zero-voltage turn-on of the switch tube can be realized. Therefore, the present invention has low loss during operation, high reliability, and is easy to implement in a circuit.

The phenomenon is that the flow velocity is too obvious in the upper and lower flow velocity of the water flow, and does not conform to the characteristics of the continuity of the natural water flow. However, although the fitted data has a steep change, the flow rate data can be improved by the fitting method based on the maximum flow velocity.

Claims

A single-stage power factor correction phase-shifted full-bridge topology circuit includes input storage capacitor, input rectifier circuit, full bridge arm circuit, DC blocking capacitor, transformer and output rectification filter circuit, input storage capacitor and full bridge arm circuit Parallel connection, DC blocking capacitor, transformer, output rectification filter circuit and charged battery are connected in series, connected to the output end of the full bridge arm circuit, input storage circuit, input rectification circuit, full bridge arm circuit and common ground of DC blocking circuit The terminal is connected to the input end, and the grounding end of the output rectifying and filtering circuit is connected to the output end, and is characterized in that: the input inductor L and the freewheeling circuit are added, the freewheeling circuit and the input inductor L are connected in parallel, and the two ends of the parallel connection are connected to the input. The output end of the rectifier circuit is connected to the full bridge arm circuit, and the lower switch tube of the lead bridge arm in the full bridge arm circuit is used as a switch tube in the boost circuit to achieve rectification, and the input inductor L is used together to realize single-stage power factor correction. ;among them:

One end of the input inductor L is connected to the output end of the input rectifier circuit, and the other end of the input inductor L is connected to the connection point of the upper and lower switch tubes of the front bridge arm in the full bridge arm circuit;

Freewheeling circuit comprising the freewheeling switch Q f and the freewheeling diode D f, the freewheeling switch L has one end connected to the drain of Q f input inductor, freewheeling switch tube connecting the source level Q f the freewheeling diode D f of the negative electrode The anode of the freewheeling diode D f is connected to the other end of the input inductor L.