TWI435521B - A novel half-bridge power factor corrector with soft-switching - Google Patents

Description

New half-bridge power factor corrector with flexible switching

The present application proposes a novel half-bridge power factor corrector with flexible switching, wherein the auxiliary circuit of pulse width modulation realizes zero current switching function, resulting in The active switch switches between the zero current state and the passive switch at zero voltage, and the current path in the circuit only flows through the characteristics of the auxiliary switch circuit to reduce the conduction loss, thereby improving the efficiency of the half bridge power factor corrector.

The issue of supply and demand for energy and food is now one of the important issues of concern to all countries in the world, especially energy, an indispensable element in the development of human science and technology. There are many forms of energy, such as oil, natural gas, nuclear energy and solar energy. The storage of energy is currently the best way to generate electricity in the form of electricity. In daily life, the AC-DC rectification method occupies a considerable proportion, such as: computers, electric lights, industrial equipment, and home appliances, etc., and the required power supply is still dominated by DC power. Generally, the utility power is obtained from the power system, and then the conventional passive AC-DC rectifier is used to obtain the DC power supply. The structure is composed of a passive component diode bridge rectifier and a filter capacitor. Since the rectifier is naturally rectified, the input current is included. The nonlinear distortion waveform of the low-frequency harmonics, in addition to the power factor reduction of the nonlinear distortion current waveform, the harmonic components contained in it also affect other electronic devices, and even cause virtual power imbalance, affecting the power quality of the entire power system.

In recent years, countries around the world have advocated improving energy efficiency, which has made the development and development of power factor correctors increasingly valued. In particular, the active power factor corrector is widely used to control the active switch so that the input current can follow the reference current sinusoidal waveform without generating a high surge current form, thereby improving the power factor and reducing the harmonics to comply with the correlation. specification. The half-bridge power factor modifier architecture of the prior art is shown in FIG. 1(a), and has the advantage that the number of switches on the conduction path is the least, so that the circuit loss is small compared to other types of power factor correctors, and Excellent power factor correction and high conversion efficiency point. Moreover, compared to the single-switch power factor corrector, the power that can be processed is large, which is popular. However, as described above, the conventional half-bridge power factor corrector adopts a hard switch (Hard Switching) method, and the efficiency cannot be further improved.

Not only the above-mentioned conventional half-bridge power factor corrector, but also the active power factor corrector generally uses a hard switching mode, and the higher the switching frequency, the larger the size of the inductor and the capacitor, and the lower the cost. The power factor is similar to one. However, the power switch is not an ideal component. As the switching frequency increases, the number of switching times per unit time increases, causing serious switching loss and electromagnetic interference. In order to further improve and improve converter efficiency, in recent years, Soft Switching pulse wave modulation technology has been proposed one after another, and future electronic products are bound to be combined with power factor correction and flexible switching technology.

Furthermore, with the rapid advancement of process technology, semiconductor components have made electronic products increasingly thin and light, making traditional linear power converters that are bulky and inefficient, unable to meet the needs of the market, so they are replaced by switched power conversion. The power converter uses Pulse Width Modulation (PWM) technology to switch the power switching components on or off in a high-frequency manner to achieve output buck, boost, and efficiency. . In addition, the switching frequency is increased, so that the power converter can select a smaller energy storage component to achieve the goal of reducing cost, thinness and shortness. However, the power switch is not an ideal component, and there are parasitic capacitances and stray inductances, so that when the power switch is switched, a high voltage surge or current surge is instantaneously generated, resulting in overheating of the power switch and reducing the life of the switching element. Voltage and current waveforms on the switch as shown in 1(b) The overlapping part is Switching Loss. Therefore, the problems derived from high frequency switching:

1. The switching loss of the power switching element becomes larger as the switching frequency increases, affecting the efficiency of the power converter. And the higher the switching loss, the more serious the Thermal Problem of the converter.

2. It will cause serious electromagnetic interference (EMI) problems, affecting the normal operation of itself and other devices.

It can be seen that the switching loss and the electromagnetic interference problem are the main factors that affect the overall efficiency and function of the switching power converter. In order to improve these problems, a flexible switching technique has been developed to reduce switching loss, conduction loss, and component stress of power switching elements. The present invention proposes a half-bridge power factor corrector with flexible switching to improve the shortcomings of the prior art.

The present application proposes a novel half-bridge power factor corrector with flexible switching, wherein the auxiliary circuit of the pulse width modulation realizes the function of zero current switching, so that the active switch is switched between the zero current state and the passive switch at zero. The voltage state is switched, and the current path in the circuit flows only through the characteristics of the auxiliary switching circuit to reduce the conduction loss, thereby improving the efficiency of the half-bridge power factor corrector. The half-bridge power factor corrector is the most commonly used one. The advantage is that the number of switches on the conduction path is the smallest, so the circuit loss is minimal, and the power factor correction effect is good and the conversion efficiency is high. Moreover, compared to the single-switch power factor corrector, the power that can be processed is large, welcome. However, as described above, the general half-bridge power factor corrector adopts a hard switching mode, and the efficiency cannot be further improved. To this end, the present invention applies a flexible switching technique to a half-bridge power factor corrector to improve efficiency. The novel flexible switching half-bridge power factor corrector proposed by the present invention has a main circuit including power factor correction and flexible switching such as zero current. Power factor correction mainly reduces harmonic components and improves power factor, while zero current switching allows the power switch to switch to zero current, reducing switching losses, electromagnetic interference, and improving overall circuit efficiency.

The novel half-bridge power factor modifier circuit disclosed in the present invention is shown in FIG. 2, and includes a conventional half-bridge power factor corrector, an auxiliary switch circuit of an upper arm switch S1, and an auxiliary switch circuit of a lower arm switch S2. The half bridge power factor corrector comprises an input AC power source V _S , an inductor L _S , an upper arm switch S1 , a lower arm switch S2 , a first flywheel diode D1 and a second flywheel diode D2 . a first output capacitor C1 and a second output capacitor C2 and an output equivalent load RL; wherein the auxiliary switching circuit of the lower arm switch S2 includes a first resonant inductor Lr1, a first resonant capacitor Cr1, and a first The diode passive switch D3 and a first auxiliary switch S4; wherein the auxiliary switching circuit of the upper arm switch S1 includes a second resonant inductor Lr2, a second resonant capacitor Cr2, a second diode passive switch D4, and a The second auxiliary switch S3.

In order to simplify the description of the preferred embodiment in the description, only the operation principle of the average current control mode is explained. It is well known to those skilled in the art that the new power factor corrector is not limited thereto, and can be operated in a continuous current conduction mode or even In the boundary current conduction mode, and It is not limited to the control law of power factor correction, such as hysteresis control method, average current control method, peak current control method and other control laws that can achieve power factor correction function.

2 is a novel half-bridge power factor corrector with flexible switching according to a preferred embodiment of the present invention, comprising a conventional half-bridge power factor corrector, an auxiliary switch circuit of an upper arm switch S1, and a lower arm switch S2. Auxiliary switch circuit. The half bridge power factor corrector comprises an input AC power source V _S , an inductor L _S , an upper arm switch S1 , a lower arm switch S2 , a first flywheel diode D1 and a second flywheel diode D2 . a first output capacitor C1 and a second output capacitor C2 and an output equivalent load RL, the diodes including a fast diode, an ultra-fast diode, and a Schottky diode suitable for switching The auxiliary switching circuit of the lower arm switch S2 includes a first resonant inductor Lr1, a first resonant capacitor Cr1, a first diode passive switch D3, and a first auxiliary switch S4; The auxiliary switching circuit of the upper arm switch S1 includes a second resonant inductor Lr2, a second resonant capacitor Cr2, a second diode passive switch D4, and a second auxiliary switch S3. The upper arm switch S1 and the lower arm switch S2 The first auxiliary switch S4 and the second auxiliary switch S3 include, for example, a gold oxide half field effect transistor (MOSFET), a bipolar transistor (BJT), an insulated gate bipolar transistor (IGBT), and the like, which are suitable for switching operations. Transistor.

In addition, the new half-bridge power factor corrector with flexible switching performs active power switch switching by a PWM controller (not shown), and the PWM controller includes continuous and discontinuous current conduction mode control of the input inductor. . Power factor correction function The control mode includes modes such as an average current control mode, a peak current control mode, and a hysteresis current control mode to achieve a power factor correction function.

The operation of the half-bridge power factor corrector with flexible switching proposed by the present invention will be described below, and FIGS. 3(a) and (b) respectively illustrate the waveform of the positive half-negative period of the input power source V _S , and FIG. 4( a ) And (b) respectively explain the equivalent circuit of the positive and negative half cycles of the input power supply V _S . Furthermore, since the switching frequency is much larger than the input power supply 60 Hz frequency, it can be assumed that the input power supply voltage is a constant voltage in one switching period, and the positive and negative half cycles can be respectively divided into seven state intervals in one switching period. Furthermore, since the positive and negative half-cycle circuit operations are symmetrical, the circuit operates under a steady state condition of a switching cycle, and only the circuit of the positive half cycle is analyzed. The following is a description of the positive half-cycle operation. In order to facilitate the analysis, the following assumptions are made before the steady-state operation analysis:

(a) All component devices are considered ideal.

(b) The input current i _L =I _in is a fixed value. Since the input inductance L _{S is} much larger than the resonant inductors Lr1 and Lr2, it can be regarded as a current source.

(c) The output voltage V _O is constant. Because the output capacitor C _O is very large, it can be regarded as a voltage source.

(d) The input voltage V _S is a fixed value.

(e) Before the main conduction is turned on, the voltages of the resonant capacitors Cr1 and Cr2 are zero (V _Cr1 = V _Cr2 =0) and the currents of the resonant inductors Lr1 and Lr2 are input currents (I _Lr1 = I _Lr2 = I _in ).

The operation of the positive half cycle is divided into seven state intervals, the waveform is shown in Figure 3(a), and the equivalent circuit is shown in Figure 4(a).

(1) First state [t ₀ ~ t ₁ ]: The lower arm switch S2 is turned on, and the first auxiliary switch S4 is turned off.

The equivalent circuit of this state is shown in Figure 5. Before t=t ₀ , the lower arm switch S2 maintains an off state, and the input current I _in flows through the first flywheel diode D1 and the first resonant inductor Lr1 and the output voltage V _O . When t=t ₀ , the lower arm switch S2 is turned on in a zero current switching manner, and the first resonant inductor current is linearly discharged by the output voltage V _O . When t=t ₁ , the first resonant inductor current reaches zero, so that A flywheel diode D1 is turned off in a zero current switching manner.

(2) Second state [t ₁ to t ₂ ]: The lower arm switch S2 is turned on, and the first auxiliary switch S4 is turned off.

The equivalent circuit of this state is shown in Figure 6. When the second state starts, the lower arm to maintain the switch S2 is turned on, the rest of the semiconductor element are in the OFF state, a current flows through the lower arm switch S2 is maintained constant value I _in, this state of the conventional boost converter similar to conduction mode.

(3) Third state [t ₂ ~ t ₃ ]: The lower arm switch S2 is turned on, and the first auxiliary switch S4 is turned on.

The equivalent circuit of this state is shown in FIG. When the third state starts, the first auxiliary switch S4 is turned on in a zero current switching manner, and starts to resonate. The path of the resonant circuit is as shown in FIG. 7, flowing through the output voltage V _O , the first resonant inductor Lr1 , and the first resonant capacitor Cr1 . And a first auxiliary switch S4.

(4) Fourth state [t ₃ ~ t ₄ ]: The main switch S2 is turned on, and the first auxiliary switch S4 is turned off.

The equivalent circuit of this state is shown in FIG. When t=t ₃ , the resonant capacitor voltage is the largest, and the discharge is made through the resonance path, as shown in FIG. 8, flowing through the output voltage V _O , the resonant inductor Lr1, the resonant capacitor Cr1, the diode D3, and the main switch S2.

() Fifth state [t ₄ ~ t ₅ ]: The lower arm switch S2 is turned off, and the first auxiliary switch S4 is turned off.

The equivalent circuit of this state is shown in FIG. In this state, the resonant current flows through the reverse parallel diode of the first auxiliary switch S4, causing the first auxiliary switch S4 to be turned off in a zero current switching and a zero voltage switching manner.

(6) Sixth state [t ₅ ~ t ₆ ]: The lower arm switch S2 is turned off, and the first auxiliary switch S4 is turned off.

The equivalent circuit of this state is shown in FIG. The input current I _in flows through the first auxiliary diode D3, the first resonant capacitor Cr1, the first resonant inductor Lr1, and the output voltage V _O . When t=t ₆ , the voltage v _Cr1 on the first resonant capacitor Cr1 is discharged to zero.

(7) Seventh state [t ₆ to t ₇ ]: The lower arm switch S2 is turned off, and the first auxiliary switch S4 is turned off.

The equivalent circuit of this state is shown in FIG. The input current I _in flows through the first flywheel diode D1, the first resonant inductor Lr1, and the output voltage V _O , which is similar to the conventional boost converter cutoff mode.

The technical content and technical features of the present invention have been disclosed as above, but those skilled in the art can still make various substitutions and modifications without departing from the spirit and scope of the invention. . Here, it is emphasized that the above embodiment only illustrates the operation of the positive half cycle of the input power source, and the operation of the negative half cycle is symmetric to the positive half cycle, and the equivalent circuit and associated waveforms are illustrated in the drawings. Therefore, the scope of the present invention should be construed as being limited by the scope of the appended claims

C1‧‧‧First Output Capacitor

C2‧‧‧Second output capacitor

Cr1‧‧‧First Resonance Capacitor

Cr2‧‧‧ second resonance capacitor

D1‧‧‧First flywheel diode

D2‧‧‧Second flywheel diode

D3‧‧‧First diode passive switch (first passive auxiliary switch)

D4‧‧‧Second diode passive switch (second passive auxiliary switch)

Lr1‧‧‧First Resonant Inductor

Lr2‧‧‧Second resonant inductor

L _S ‧‧‧Inductors

RL‧‧‧ output equivalent load

S1‧‧‧Upper arm switch

S2‧‧‧Bottom arm switch

S3‧‧‧Second auxiliary switch

S4‧‧‧First auxiliary switch

V _O ‧‧‧Output voltage

v _S ‧‧‧Input AC power

1(a) is a circuit diagram of a conventional half bridge power factor corrector of the prior art; FIG. 1(b) is a schematic diagram of switching loss of a conventional power switching element of the prior art; FIG. 2 illustrates one of the preferred embodiments of the present invention. A circuit diagram of a half-bridge power factor corrector with flexible switching in an embodiment; FIGS. 3(a) and (b) respectively illustrate waveform diagrams of the positive half negative period of the input power source V _{S of the} embodiment of the present invention of FIG. 2; a) and (b) respectively illustrate the present invention in the embodiment of FIG. 2 v _S input power of the equivalent circuit of the positive and negative half-cycle; FIG. 5 illustrates an embodiment of the present invention, FIG 2 is input to a first state of the positive half cycle power of the equivalent FIG. 6 illustrates a second state equivalent circuit of the embodiment of the present invention of FIG. 2 in the positive half cycle of the input power source; FIG. 7 illustrates a third state equivalent circuit of the embodiment of the present invention of FIG. 2 in the positive half cycle of the input power source; FIG. 8 illustrates a fourth state equivalent circuit of the embodiment of the present invention of FIG. 2 in the positive half cycle of the input power source; FIG. 9 illustrates a fifth state equivalent circuit of the embodiment of the present invention of FIG. 2 in the positive half cycle of the input power source; FIG. Illustrating the sixth state equivalent circuit of the embodiment of the present invention of FIG. 2 in the positive half cycle of the input power source; Example input power of the positive half cycle of the seventh state of FIG. 11 illustrates an equivalent circuit of FIG. 2 embodiment of the present invention.

C1‧‧‧First Output Capacitor

C2‧‧‧Second output capacitor

Cr1‧‧‧First Resonance Capacitor

Cr2‧‧‧ second resonance capacitor

D1‧‧‧First flywheel diode

D2‧‧‧Second flywheel diode

D3‧‧‧First diode passive switch (first passive auxiliary switch)

D4‧‧‧Second diode passive switch (second passive auxiliary switch)

Lr1‧‧‧First Resonant Inductor

Lr2‧‧‧Second resonant inductor

L _S ‧‧‧Inductors

RL‧‧‧ output equivalent load

S1‧‧‧Upper arm switch

S2‧‧‧Bottom arm switch

S3‧‧‧Second auxiliary switch

S4‧‧‧First auxiliary switch

V _O ‧‧‧Output voltage

v _S ‧‧‧Input AC power

Claims (8)

A novel half-bridge power factor corrector with flexible switching, comprising: an inductor; an upper arm switch; a lower arm switch; a first flywheel diode; a second flywheel diode; and a first output capacitor a second output capacitor; wherein the one end of the upper arm switch, one end of the lower arm switch, the anode of the first flywheel diode and the cathode of the second flywheel diode are coupled to the other end of the inductor, One end of the first output capacitor and one end of the second output capacitor are coupled to the other end of the input AC power source; an auxiliary switch circuit of the upper arm switch has a second resonant inductor, a second resonant capacitor, and a a second diode passive switch and a second auxiliary switch, wherein one end of the second resonant inductor is coupled to the anode of the second flywheel diode; and the auxiliary switch circuit of the lower arm switch has a first resonance An inductor, a first resonant capacitor, a first diode passive switch, and a first auxiliary switch, wherein one end of the first resonant inductor is coupled to the first flywheel diode a cathode; wherein one end of the first resonant inductor is connected to one end of the first resonant capacitor, the other end is connected to a positive output end of the integrated circuit, and the other end of the first resonant capacitor is connected to the first two pole a passive connection switch cathode and a connection point of the first auxiliary switch, and the anode of the first diode passive switch is connected to a connection point of the half bridge power factor corrector input inductor and the upper and lower arm switches, the first The other end of the auxiliary switch is connected to the negative output end of the overall circuit; wherein, when the lower arm switch is switched in the zero current state, after the lower arm switch is turned on, and the first auxiliary switch is switched at the zero voltage state, After the first auxiliary switch is turned on, the current is caused to flow through the auxiliary switch circuit of the lower arm switch to reduce the conduction loss. A novel half-bridge power factor corrector with flexible switching according to claim 1, wherein one end of the second resonant inductor is connected to one end of the second resonant capacitor, and the other end is connected to a negative output end of the overall circuit, and The other end of the two resonant capacitor is connected to the connection point of the second diode passive switch anode and the second auxiliary switch, and the cathode of the second diode passive switch is connected to the half bridge power factor corrector input The junction of the inductor and the upper and lower arm switches, and the other end of the second auxiliary switch is connected to the positive output of the overall circuit. A novel half-bridge power factor corrector having flexible switching according to claim 1, wherein the upper arm and the lower arm, and the auxiliary switch comprise a MOSFET, a bipolar transistor (BJT), an insulating gate, such as a gold oxide half field effect transistor (MOSFET) Bipolar transistors (IGBTs), and other transistors suitable for switching operations. A novel half-bridge power factor corrector having flexible switching according to claim 1, wherein the diode includes a diode such as a fast diode, an ultra-fast diode, and a Schottky diode for switching body. A novel half-bridge power factor corrector with flexible switching according to claim 1, wherein the active power switch is switched by a PWM controller. A novel half-bridge power factor corrector with flexible switching according to claim 2, wherein the PWM control comprises continuous and discontinuous current conduction mode control of the input inductor. A novel half-bridge power factor corrector with flexible switching according to claim 1, wherein the control mode of the power factor correction function includes a power factor correction function such as an average current control mode, a peak current control mode, and a hysteresis current control mode The way. A novel half-bridge power factor corrector having flexible switching according to claim 1, wherein the upper arm switch is switched in a zero current state, and the second auxiliary switch is switched in a zero voltage state to cause a current to flow through the upper arm switch Auxiliary switch circuit.