CN209593312U - Soft Switching High Power Factor AC-DC Converter - Google Patents

Abstract

The utility model discloses a kind of Sofe Switch High Power Factor A.C.-D.C. converters, the utility model proposes Sofe Switch High Power Factor A.C.-D.C. converter can realize that the no-voltage of switching tube of circuit of power factor correction opens (Sofe Switch) in full voltage input range, and obtain higher power factor；Only have an input rectifying pipe conducting in every half power frequency period, reduces the loss of input rectification circuit；The quasi-single-stage soft switch power factor correcting circuit that a kind of connection type of the utility model is constituted is compared with traditional Boost type quasi-single-stage circuit, busbar voltage can substantially reduce, therefore the voltage stress of switching tube can be reduced, is applied to full voltage input range (90V-265Vac).

Description

Soft Switching High Power Factor AC-DC Converter

technical field

The utility model belongs to the technical field of switching power supplies and relates to a soft-switching high power factor AC-DC converter.

Background technique

The wide application of power electronic devices has caused serious pollution to the public grid, and the problems of harmonics and reactive power have been paid more and more attention. In order to reduce the harm of electric power pollution, many countries have formulated corresponding standards, such as the harmonic standards IEEE555-2 and IEC1000-3-2 of the International Electrotechnical Commission. Power Factor Correction (PFC) technology, such as Active Power Factor Correction (APFC) technology can effectively suppress harmonics, so power factor correction circuits (PFC) are often used in AC- The front stage of the DC power electronic conversion device.

Figure 1 shows the topology of a traditional two-stage AC-DC power electronic conversion device. The front stage usually uses a boost (Boost) circuit as power factor correction to achieve AC-DC energy conversion and output a stable DC voltage; the latter stage uses a high-efficiency half-bridge LLC resonant converter to achieve isolation and step-down functions.

The advantage of the Boost circuit as a pre-stage power factor correction circuit is that it has a simple structure and is easy to obtain a higher power factor. However, it also has certain disadvantages. If the current continuous mode is used, the freewheeling diode has a large reverse recovery problem. The switching process is a hard switch, resulting in a decrease in efficiency; and if the discontinuous mode is used, the peak value of the input current is large, the switching process is a hard switch, and the efficiency is low. In addition, the inductance is large; the current critical conduction mode is used, although it can be realized The switch tube is turned on at zero voltage to reduce loss, but the detection of the voltage across the inductor winding increases the complexity of the control. In addition, in the case of high voltage input, the switch tube can only be turned on at the bottom of the resonance valley, and it cannot achieve complete softness. switch.

Contents of the invention

The utility model proposes a soft-switching high power factor AC-DC converter, the soft-switching high power factor AC-DC converter includes a soft-switching power factor correction circuit, wherein

The soft switching power factor correction circuit includes: a filter, a rectifier tube D1, a rectifier tube D2, a freewheel tube D3, a freewheel tube D4, an inductor L1, a capacitor C1, a switch tube Q1, a switch tube Q2, and a capacitor CB;

Among them, one input terminal of the filter is connected to one end of the AC source Vac, and the other input terminal of the filter is connected to the other end of the AC source Vac, and one output terminal of the filter is connected to the anode of the rectifier tube D1 and the cathode of the rectifier tube D2, and the filter's One output terminal is connected to the anode of the freewheeling tube D3 and the cathode of the freewheeling tube D4, the cathode of the rectifier tube D1 is connected to the cathode of the freewheeling tube D3, the drain of the switching tube Q1 and the positive terminal of the capacitor CB, and the anode of the rectifier tube D2 is connected to the freewheeling tube The anode of the tube D4, the source of the switching tube Q2, the negative terminal of the capacitor CB and the reference ground, the anode of the freewheeling tube D3 are connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to The source of the switching tube Q1 and the drain of the switching tube Q2, and the gates of the switching tube Q1 and the switching tube Q2 respectively receive the drive signal output by the control circuit;

The soft switching power factor correction circuit realizes the correction of the AC input current, makes the AC input current waveform close to a sine wave, and outputs a DC voltage at both ends of the capacitor CB;

Preferably, it also includes a load, the load is connected between the positive terminal (A terminal) and the negative terminal (B terminal) of the capacitor CB, and the load is a passive load such as a resistor, an LED, a storage battery, or a DC-DC conversion circuit;

Preferably, a load is also included, and the load is connected between the midpoint (terminal C) of the switch bridge arm formed by the switch tube Q1 and the switch tube Q2 and the negative terminal (terminal B) of the capacitor CB, and the load can be resistance or DC-DC conversion circuit;

Preferably, a load is also included, and the load is connected between the midpoint (C terminal) of the switch bridge arm formed by the switch tube Q1 and the switch tube Q2 and the midpoint (D terminal) of the two series capacitors forming the capacitor CB, and the load can be is a resistor or a DC-DC conversion circuit;

The DC-DC conversion circuit converts the DC voltage across the capacitor CB into a DC voltage or converts it into a DC current;

Preferably, the soft-switching high power factor AC-DC converter also includes a control circuit, and the control circuit can be PFM control, PWM control or PFM+PWM control;

Preferably, the control circuit includes a PFM control error amplification link, a sawtooth wave generation circuit, a PWM control error amplification link, a comparator Com2, and a drive signal generation circuit.

Further, the PFM control error amplification link includes a resistor R1, a first compensation network, a first operational amplifier OP1 and a voltage reference Vref1, one end of the resistor R1 is connected to the FB end, and receives the output voltage or current signal fed back by the main circuit, and the resistor R1 The other end of the first compensation network is connected to one end of the first compensation network and the negative input end of the operational amplifier OP1, the positive input end of the operational amplifier OP1 is connected to the positive end of the voltage reference Vref1, the negative end of the voltage reference Vref1 is connected to the reference ground, and the output of the first compensation network The terminal is connected to the output terminal of the first operational amplifier OP1; the PFM control error amplification link compares and amplifies the signal difference between the signal received by FB and the voltage reference Vref1, and generates an error amplification signal Vcomp1;

The sawtooth wave generation circuit includes a voltage reference Vref2, a voltage-controlled current source VCI, a capacitor C1, a switch S1, a voltage reference Vref4, and a comparator Com1. The positive input terminal of the current source VCI is connected to the positive terminal of the voltage reference Vref3, the negative terminal of the voltage reference Vref3 is connected to the reference ground, one output terminal of the voltage-controlled current source VCI is connected to the reference ground, the other output terminal is connected to one end of the capacitor C1, and the switch S1 One end of the comparator Com1 and the negative input end of the comparator Com1, the positive input end of the comparator Com1 is connected to one end of the voltage reference Vref4, the output end of the comparator Com1 is connected to the control end of the switch S1, and the other end of the switch S1 is grounded; the sawtooth wave generating circuit receives The error amplification signal Vcomp1 generates a frequency-variable sawtooth signal Vsaw;

The PWM control error amplification link includes a resistor R2, a second compensation network, an operational amplifier OP2, a voltage reference Vref2, and a limiter LIMV. One end of the resistor R2 is connected to the VFB end to receive the output voltage signal fed back by the main circuit. The other end is connected to one end of the second compensation network and the negative input end of the operational amplifier OP2, the positive input end of the operational amplifier OP2 is connected to the positive end of the voltage reference Vref2, the negative end of the voltage reference Vref2 is connected to the reference ground, and the output end of the second compensation network Connect the output terminal of the operational amplifier OP2, the output terminal of the operational amplifier OP2 is connected to the input terminal of the limiter LIMV2, and the output terminal of the limiter LIMV2 outputs the error amplification signal Vcomp2; the PWM control error amplification link compares the signal received by VFB with the voltage reference Vref1 Compare the signal difference between them, amplify and output the error amplification signal Vcomp2 after limiting the amplitude by the limiter LIMV;

The negative input terminal of the comparator Com2 is connected to the output terminal of the sawtooth wave generating circuit to receive the sawtooth signal Vsaw, and the positive input terminal of the comparator Com2 is connected to the output terminal of the PWM control error amplification link to receive the output error amplification signal Vcomp2; the comparator Com2 compares the received sawtooth signal Vsaw with the error amplifier signal Vcomp2, and outputs the pulse signal Vpulse;

The driving signal generation circuit includes an inverter INV, a first delay circuit, a second delay circuit, an AND gate AND1, an AND gate AND2 and a drive circuit; the input terminal of the inverter INV is connected to the second delay circuit The input terminal of the AND gate AND2 receives the pulse signal Vpulse, the output terminal of the inverter INV is connected to the input terminal of the first delay circuit and an input terminal of the AND gate AND1, and the output terminal of the AND gate AND1 is connected to the drive One input terminal of the circuit, two output terminals of the drive circuit output drive signals V _{g_Q1} and V _{g_Q2 respectively} ; the first delay circuit and the second delay circuit generate delay Td1 and Td2 respectively for generating the drive signal V The dead time between _{g_Q1} and V _{g_Q2} , the driving circuit is used to enhance the driving capability and drive signal bootstrapping.

Preferably, a soft-switching high power factor AC-DC converter includes the soft-switching power factor correction circuit and the half-bridge LLC resonant DC-DC conversion circuit, and the switching tube of the half-bridge LLC resonant DC-DC conversion circuit Multiplexed with the switching tube of the soft-switching high power factor correction circuit, the half-bridge LLC resonant DC-DC conversion circuit also includes a resonant inductor Lr, a resonant capacitor Cr, a transformer T2, an output rectifier circuit, and an output capacitor Co; the resonant inductor Lr One end is connected to the source of the switching tube Q1 and the drain of the switching tube Q2, the other end of the resonant inductor Lr is connected to one end of the resonant capacitor Cr, the other end of the resonant capacitor Cr is connected to one end of the primary winding of the transformer T2, and the primary winding of the transformer T2 The other end is connected to the reference ground, the secondary winding of the transformer T2 is connected to the input end of the output rectifier, and the output end of the output rectifier is connected to the output capacitor Co;

Preferably, a soft-switching high power factor AC-DC converter includes the soft-switching power factor correction circuit and a half-bridge flyback circuit, the switching tube of the half-bridge flyback circuit and the soft-switching high power factor correction circuit The switching tube is multiplexed. The half-bridge flyback circuit also includes a DC blocking capacitor Cx, a transformer T3, an output rectifier Do, and an output capacitor Co; one end of the DC blocking capacitor Cx is connected to the source of the switching tube Q1 and the drain of the switching tube Q2, and the DC blocking capacitor The other end of Cx is connected to the same-name end of the primary winding of the transformer T3, the opposite-name end of the primary winding of the transformer T3 is connected to the reference ground, the opposite-name end of the secondary winding of the transformer T3 is connected to the input end of the output rectifier Do, and the output end of the output rectifier Do Connect to the positive end of the output capacitor Co, and the negative end of the output capacitor Co to the same-named end of the secondary winding of the transformer T3;

Preferably, the rectifier D1, rectifier D2, freewheel D3 and freewheel D4 in the soft-switching high power factor AC-DC converter are diodes,

Preferably, the rectifier D1, the rectifier D2, the freewheel D3 and the freewheel D4 in the soft-switching high power factor AC-DC converter may also be part or all of MOSFETs.

The beneficial effect of the utility model is that: the soft switch high power factor AC-DC converter proposed by the utility model can realize the zero-voltage turn-on (soft switch) of the switch tube of the power factor correction circuit in the full input voltage range, and obtain relatively High power factor; only one input rectifier is turned on in each half power frequency cycle, which reduces the loss of the input rectifier circuit; the quasi-single-stage soft switching power factor correction circuit composed of a connection method of the utility model is different from the traditional Compared with the Boost type quasi-single-stage circuit, the bus voltage can be greatly reduced, so the voltage stress of the switch tube can be reduced, and it can be applied to the full voltage input range (90V-265Vac).

Description of drawings

Fig. 1 is a kind of prior art two-stage AC-DC power electronic converter;

Fig. 2 shows the first circuit structure diagram of the soft-switching high power factor AC-DC converter of the present invention;

Fig. 3 shows the second circuit structure diagram of the soft-switching high power factor AC-DC converter of the present invention;

Fig. 4 shows the third circuit structure diagram of the soft-switching high power factor AC-DC converter of the present invention;

Fig. 5 shows some key waveforms of the soft-switching high power factor AC-DC converter of the present invention;

Fig. 6 shows a schematic diagram of an equivalent circuit in the first working mode of the soft-switching high power factor circuit of the present invention;

Fig. 7 shows a schematic diagram of an equivalent circuit in the second working mode of the soft-switching high power factor circuit of the present invention;

Fig. 8 shows a schematic diagram of an equivalent circuit in the third working mode of the soft-switching high power factor circuit of the present invention;

Fig. 9 shows a schematic diagram of an equivalent circuit in the fourth working mode of the soft-switching high power factor circuit of the present invention;

Fig. 10 shows a schematic diagram of an equivalent circuit in the fifth working mode of the soft-switching high power factor circuit of the present invention;

Fig. 11 shows a schematic diagram of an equivalent circuit in the sixth working mode of the soft-switching high power factor circuit of the present invention;

Fig. 12 shows a schematic diagram of an equivalent circuit in the seventh working mode of the soft-switching high power factor circuit of the present invention;

Fig. 13 shows a schematic diagram of an equivalent circuit in the eighth working mode of the soft-switching high power factor circuit of the present invention;

Fig. 14 shows the calculation curve of the AC input current of the soft-switching high power factor AC-DC converter of the utility model at half power frequency period;

Fig. 15 shows the relationship curve between the operating frequency and the AC input voltage of the soft-switching high power factor AC-DC converter of the present invention under the condition of a certain DC bus voltage;

Fig. 16 shows an embodiment of a PFM+PWM control circuit suitable for a soft-switching high power factor AC-DC converter of the present invention;

Fig. 17 shows some key waveforms of the control circuit shown in Fig. 16;

Fig. 18 shows the first specific embodiment of the soft-switching high power factor AC-DC converter of the present invention;

Fig. 19 shows the second specific embodiment of the soft-switching high power factor AC-DC converter of the present invention;

Fig. 20 shows the third specific embodiment of the soft-switching high power factor AC-DC converter of the present invention;

Fig. 21 shows the fourth specific embodiment of the soft-switching high power factor AC-DC converter of the present invention;

Fig. 22 shows a schematic diagram of rectifier tubes D1, D2 and freewheeling tubes D3, D4 in the soft-switching high power factor circuit of the present invention after MOSFETs are used;

Detailed ways

The content of the utility model will be described in detail below in conjunction with the circuit structure diagram of the utility model.

Referring to the first structural diagram of the soft-switching high power factor AC-DC converter of the present invention shown in Figure 2, the soft-switching high power factor AC-DC converter includes a soft-switching power factor correction circuit and a load;

The soft switching power factor correction circuit includes: a filter, a rectifier tube D1, a rectifier tube D2, a freewheeling tube D3, a freewheeling tube D4, an inductor L1, a capacitor C1, a switch tube Q1, a switch tube Q2, and a capacitor CB; wherein, One input terminal of the filter is connected to one end of the AC source Vac, the other input terminal is connected to the other end of the AC source Vac, one output terminal of the filter is connected to the anode of the rectifier tube D1 and the cathode of the rectifier tube D2, one output of the filter The terminal is connected to the anode of the freewheeling tube D3 and the cathode of the freewheeling tube D4, the cathode of the rectifier tube D1 is connected to the cathode of the freewheeling tube D3, the drain of the switching tube Q1 and the positive end of the capacitor CB, and the anode of the rectifier tube D2 is connected to the freewheeling tube D4 The anode of the switch tube Q2, the source of the switch tube Q2, the negative terminal of the capacitor CB and the reference ground, the anode of the freewheeling tube D3 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the switch tube The source of Q1 and the drain of the switching tube Q2, and the gates of the switching tube Q1 and the switching tube Q2 respectively receive the drive signal output by the control circuit;

The load is connected between the positive terminal (A terminal) and the negative terminal (B terminal) of the capacitor CB, and the load is a passive load such as a resistor, an LED, a storage battery or a DC-DC conversion circuit;

Referring to the second structural diagram of the soft-switching high power factor AC-DC converter of the present invention shown in Figure 3, the soft-switching high power factor AC-DC converter includes a soft-switching power factor correction circuit and a load;

The soft switching power factor correction circuit includes: a filter, a rectifier tube D1, a rectifier tube D2, a freewheeling tube D3, a freewheeling tube D4, an inductor L1, a capacitor C1, a switch tube Q1, a switch tube Q2, and a capacitor CB; wherein, One input terminal of the filter is connected to one end of the AC source Vac, the other input terminal is connected to the other end of the AC source Vac, one output terminal of the filter is connected to the anode of the rectifier tube D1 and the cathode of the rectifier tube D2, one output of the filter The terminal is connected to the anode of the freewheeling tube D3 and the cathode of the freewheeling tube D4, the cathode of the rectifier tube D1 is connected to the cathode of the freewheeling tube D3, the drain of the switching tube Q1 and the positive end of the capacitor CB, and the anode of the rectifier tube D2 is connected to the freewheeling tube D4 The anode of the switch tube Q2, the source of the switch tube Q2, the negative terminal of the capacitor CB and the reference ground, the anode of the freewheeling tube D3 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the switch tube The source of Q1 and the drain of the switching tube Q2, and the gates of the switching tube Q1 and the switching tube Q2 respectively receive the drive signal output by the control circuit;

The load is connected between the middle point (C terminal) of the switching bridge arm formed by the switching tube Q1 and the switching tube Q2 and the negative terminal (B terminal) of the capacitor CB, and the load can be a resistance or a DC-DC conversion circuit;

Referring to the third structural diagram of the soft-switching high power factor AC-DC converter of the present invention shown in Figure 4, the AC-DC converter includes a soft-switching power factor correction circuit and a load;

The soft switching power factor correction circuit includes: a filter, a rectifier tube D1, a rectifier tube D2, a freewheeling tube D3, a freewheeling tube D4, an inductor L1, a capacitor C1, a switch tube Q1, a switch tube Q2, and a capacitor CB; wherein, One input terminal of the filter is connected to one end of the AC source Vac, the other input terminal is connected to the other end of the AC source Vac, one output terminal of the filter is connected to the anode of the rectifier tube D1 and the cathode of the rectifier tube D2, one output of the filter The terminal is connected to the anode of the rectifier D3 and the cathode of the rectifier D4, the cathode of the rectifier D1 is connected to the cathode of the rectifier D3, the drain of the switching tube Q1 and the positive end of the capacitor CB, and the anode of the rectifier D2 is connected to the rectifier D4 The anode of the switch tube Q2, the source of the switch tube Q2, the negative terminal of the capacitor CB and the reference ground, the anode of the freewheeling tube D3 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the switch tube The source of Q1 and the drain of the switching tube Q2, and the gates of the switching tube Q1 and the switching tube Q2 respectively receive the drive signal output by the control circuit;

The capacitor CB is composed of a capacitor CB1 and a capacitor CB2 connected in series, and the load is connected between the midpoint (terminal C) of the switching bridge arm formed by the switching tube Q1 and the switching tube Q2 and the midpoint (terminal D) of the capacitor CB1 and the capacitor CB2 , the load can be a resistor or a DC-DC conversion circuit;

Referring to some key waveforms of the soft-switching high power factor AC-DC converter of the present invention shown in Fig. 5, wherein V _ac represents the AC input voltage provided by the power grid, and V _{c1_avg} is the waveform after the high-frequency component is filtered out by the capacitor C1 voltage , i _L represents the current flowing through the inductor L1, i _ac represents the AC bus current flowing into the power grid through the filter, i _in represents the AC bus current before the filter, V _{g_Q1} and V _{g_Q2} represent the switching tube Q1 and switching tube Q2 respectively The gate voltage, i _Q1 and i _Q2 represent the current flowing through the switch tube Q1 and the switch tube Q2 respectively; among them, for the sake of simplicity, V _{g_Q1} and V _{g_Q2} respectively only draw a switch in the positive and negative half cycles of the AC input voltage V _ac The periodic waveform is used to describe the working process of the circuit, and the dead time is not considered.

When the AC input voltage Vac is in the positive half cycle, the working process of the circuit can be simply divided into four stages:

The first stage [t0-t1]: At time t0, the switch tube Q2 is turned off, and since i _L is negative, the corresponding i _Q1 is also negative, so i _Q1 first flows through the body diode of the switch tube Q1, making the switch tube Q1 Zero-voltage conduction, the freewheeling tube D3 remains on, and the equivalent circuit is shown in Figure 6. During this period, the inductor L1 and the capacitor C1 resonate, and i _L rises from the negative maximum resonance, and the loop equation is;

Wherein, V _CB is the voltage across the capacitor CB, that is, the DC bus voltage.

The second stage [t1-t2]: At time t1, since i _L rises to zero, the freewheeling tube D3 is turned off, the rectifier tube D1 is turned on, and the freewheeling tube D3 is turned off. The equivalent circuit is shown in Figure 7. During this period, the inductor current i _L1 rises resonantly, and the loop equation is:

The third stage [t2-t3]: At the time t2, the switching tube Q1 is turned off, and the inductor current i _L first flows through the body diode of the switching tube Q2, so that the switching tube Q2 is turned on with zero voltage, and the rectifier tube D1 remains on, which is equivalent to The circuit is shown in Figure 8. During this period, the inductor current i _L resonantly drops, and the loop equation is:

The fourth stage [t3-t4]: At time t3, the inductor current i _L drops to zero, the rectifier tube D1 is turned off, and the freewheeling tube D4 is turned on. The equivalent circuit is shown in Figure 9. During this period, the inductor current i _L1 continues to resonate down, and the loop equation is:

When the AC input voltage is a negative half cycle, according to the symmetry of the circuit, the working process of the circuit is similar. The rectifier tube D2 and the freewheeling tube D3 are turned on. Referring to the waveform at time t5-t9, the working process of the circuit can also be divided into four stage, and the equivalent circuits of each stage are shown in Figure 10-Figure 13 respectively, and will not be analyzed in detail here.

From the above circuit analysis, it can be known that only one rectifier is turned on in each half of the power frequency cycle, so the loss of the rectifier circuit is lower than that of the traditional rectifier circuit; in addition, both the switch tube Q1 and the switch tube Q2 can achieve zero-voltage conduction, That is, soft switching is realized.

According to the above analysis, the expression of AC input current in half power frequency cycle can be calculated as follows:

in, The expression of the switching period Ts is:

According to the formulas (5) and (6), the waveform of the AC input current iac can be obtained as shown in Figure 14. It can be seen that the AC input current waveform is very close to sinusoidal, so that the soft switching high power factor of the utility model under certain working conditions can be calculated The relationship curve between the switching frequency of the circuit and the effective value of the AC input voltage is shown in Figure 15. It can be seen from Figure 15 that the gain of the DC bus voltage relative to the AC input voltage can be adjusted by adjusting the frequency, which means that the soft-switching high power factor circuit of the present invention can adopt frequency conversion control (PFM). As those skilled in the art can also know, at a certain switching frequency, the PWM method of adjusting the duty cycle controls the voltage gain of the soft-switching high power factor circuit of the present invention, and can also achieve the purpose of adjusting the output voltage/current. Therefore, the soft-switching high power factor circuit of the present invention can adopt PFM control, PWM control, or a mixed control mode of PFM+PWM control. The above control methods do not exhaustively list all feasible control methods applicable to the soft-switching high power factor circuit of the present invention, and those skilled in the art should not be difficult to find other applicable control methods according to the spirit of the present invention.

According to the circuit relationship, it can be further deduced that the voltage value V _{c1_avg} after the high-frequency component is filtered out by the capacitor C1 is equal to 1/2 of the AC input voltage V _ac , so the capacitor C1 also functions as a voltage divider for the AC input voltage, so that The voltage gain of the soft switch high power factor circuit of the utility model is lower than that of the traditional Boost circuit.

Figure 16 shows a schematic diagram of a specific embodiment of a PFM+PWM control circuit suitable for an AC-DC converter of the present invention; the control circuit includes a PFM control error amplification link 101, a sawtooth wave generation circuit 102, and a PWM control error an amplification link 103 , a comparator Com2 , and a driving signal generating circuit 104 .

Further, the PFM control error amplification link 101 includes a resistor R1, a compensation network 1, an operational amplifier OP1 and a voltage reference Vref1, one end of the resistor R1 is connected to the FB end, and receives the output voltage or current signal fed back by the main circuit, and the other end of the resistor R1 One end is connected to one end of the compensation network 1 and the negative input end of the op amp OP1, the positive input end of the op amp OP1 is connected to the positive end of the voltage reference Vref1, the negative end of the voltage reference Vref1 is connected to the reference ground, and the output end of the compensation network 1 is connected to the op amp The output terminal of OP1; the PFM control error amplification link 101 compares and amplifies the signal difference between the signal received by FB and the voltage reference Vref1, and generates an error amplification signal Vcomp1;

The sawtooth wave generating circuit 102 includes a voltage reference Vref2, a voltage-controlled current source VCI, a capacitor C1, a switch S1, a voltage reference Vref4, and a comparator Com1. The negative input terminal of the voltage-controlled current source VCI is connected to the output terminal of the op amp OP1. The positive input terminal of the current control source VCI is connected to the positive terminal of the voltage reference Vref3, the negative terminal of the voltage reference Vref3 is connected to the reference ground, one output terminal of the voltage control current source VCI is connected to the reference ground, and the other output terminal is connected to one end of the capacitor C1, the switch One end of S1 and the negative input end of the comparator Com1, the positive input end of the comparator Com1 is connected to one end of the voltage reference Vref4, the output end of the comparator Com1 is connected to the control end of the switch S1, and the other end of the switch S1 is grounded; the sawtooth wave generating circuit 102 Generate a frequency-variable sawtooth wave signal Vsaw according to the received error amplification signal Vcomp1;

The PWM control error amplification link 103 includes a resistor R2, a compensation network 2, an operational amplifier OP2, a voltage reference Vref2, and a limiter LIMV. One end of the resistor R2 is connected to the VFB end to receive the output voltage signal fed back by the main circuit. The other end is connected to one end of the compensation network 2 and the negative input end of the op amp OP2, the positive input end of the op amp OP2 is connected to the positive end of the voltage reference Vref2, the negative end of the voltage reference Vref2 is connected to the reference ground, and the output end of the compensation network 2 is connected to the op amp. Put the output terminal of OP2, the output terminal of the operational amplifier OP2 is connected to the input terminal of the limiter LIMV2, and the output terminal of the limiter LIMV2 outputs the error amplification signal Vcomp2; Compare the signal difference between them, amplify and output the error amplification signal Vcomp2 after limiting the amplitude by the limiter LIMV;

The negative input terminal of the comparator Com2 is connected to the output terminal of the sawtooth wave generating circuit 102 to receive the sawtooth signal Vsaw, and the positive input terminal of the comparator Com2 is connected to the output terminal of the PWM control error amplification link 103 to receive the output error amplification signal Vcomp2; The comparator Com2 compares the received sawtooth signal Vsaw with the error amplification signal Vcomp2, and outputs the pulse signal Vpulse;

The driving signal generating circuit 104 includes an inverter INV, a delay circuit 1, a delay circuit 2, an AND gate AND1, an AND gate AND2 and a drive circuit 1041; the input terminal of the inverter INV is connected to the delay circuit 2 The input terminal and an input terminal of the AND gate AND2 receive the pulse signal Vpulse, the output terminal of the inverter INV is connected to the input terminal of the delay circuit 1 and an input terminal of the AND gate AND1, and the output terminal of the AND gate AND1 is connected to the drive circuit. One input terminal, two output terminals of driving circuit 1041 respectively output driving signals V _{g_Q1} and V _{g_Q2} ; said delay circuit 1 and delay circuit 2 generate delay time Td1 and Td2 respectively, for generating driving signals V _{g_Q1} and V The dead time between _{g_Q2} , the driving circuit 1041 is used to enhance the driving capability and drive signal bootstrapping.

Fig. 17 shows the key waveforms of the control circuit in Fig. 16, including schematic diagrams of two cases of PFM control and PWM control;

The first case: when the output voltage is low so that the output voltage feedback signal VFB is always lower than the voltage reference Vref2, Vcomp2 is in a constant high state, and due to the effect of the limiter LIMV, Vcomp2 is clamped at Vref4/2; PFM control error The amplifying link 101 plays a role of circuit regulation, outputting the Vcomp1 signal affected by the working condition of the circuit, the difference between the Vcomp1 signal and Vref3 changes the output current of the voltage-controlled current source VCI, thereby adjusting the frequency of the sawtooth wave Vsaw, and the sawtooth wave Vsaw The peak value of Vsaw is equal to Vref4; after Vcomp2 is compared with Vsaw, the output duty ratio is equal to 50%, and the pulse signal Vpulse whose frequency is consistent with the frequency of the sawtooth wave Vsaw is further output by the driving signal generating circuit 104. The frequency is variable and the duty ratio is close to 50%. drive signals V _{g_Q1} and V _{g_Q2} ; the adjustment process of the circuit is illustrated as follows: when the main circuit is affected by the outside world, the output voltage increases, so that the FB signal increases, and the PFM control error amplification link 101 makes Vcomp1 decrease, and the Vcomp1 signal and Vref3 The larger the difference, the higher the output current of the voltage-controlled current source VCI, the higher the frequency of Vsaw, and the higher frequency of the driving signal. It can be seen from Figure 15 that the operating frequency of the circuit reduces the gain of the circuit and reduces the output voltage. Therefore, it can be seen that through The negative feedback effect of the control circuit can make the circuit return to the steady state.

The second situation: when the output voltage is high, the main circuit feedback signal FB is always higher than the voltage reference Vref1, so Vcomp1 is in a constant low state, the output voltage feedback signal VFB reaches the voltage reference Vref2, and the PWM control error amplification link 102 functions as a circuit regulator. Function, output the error amplification signal Vcomp2 with adjustable amplitude. The difference between the voltage reference Vref3 and Vcomp1 is a constant value, so the frequency of the sawtooth wave Vsaw is a constant value and the peak value is equal to Vref2; Vcomp2 is compared with Vsaw to output a pulse signal Vpulse with an adjustable duty cycle and a frequency consistent with the sawtooth wave Vsaw. The driving signals V _{g_Q1} and V _{g_Q2} with adjustable duty ratio are further outputted through the driving signal generating circuit 104 . An example to illustrate the adjustment process of the circuit is as follows: when the main circuit is affected by the outside world, the output voltage increases, so that the VFB signal increases, and the PWM control error amplification link 102 causes Vcomp2 to decrease, thereby reducing the duty cycle of the pulse signal Vpulse, and further making the drive signal Vg_Q1 occupy The duty ratio of Vg_Q2 decreases and the duty ratio of Vg_Q2 increases; therefore, the on-time of the switch tube S1 decreases, so that the energy transferred by the inductor L1 in each switching cycle decreases, thereby reducing the output voltage. Therefore, it can be seen that the negative feedback of the control circuit can make the circuit return to a steady state.

Fig. 18 shows the first specific embodiment of the soft-switching high power factor AC-DC converter of the present invention, wherein the load is a half-bridge LLC resonant DC-DC conversion circuit; it is not difficult for those skilled in the art to know that the load can also be For other types of DC-DC conversion circuits.

Fig. 19 shows the second specific embodiment of the soft-switching high power factor AC-DC converter of the present invention, wherein the load is a half-bridge LLC resonant DC-DC conversion circuit, and the half-bridge LLC resonant DC-DC conversion circuit The switching tube of the soft switching high power factor correction circuit is multiplexed. The half-bridge LLC resonant DC-DC conversion circuit also includes a resonant inductor Lr, a resonant capacitor Cr, a transformer T2, an output rectifier circuit 201, and an output capacitor Co; one end of the resonant inductor Lr is connected to the source of the switch tube Q1 and the switch tube Q2. Drain, the other end of the resonant inductor Lr is connected to one end of the resonant capacitor Cr, the other end of the resonant capacitor Cr is connected to one end of the primary winding of the transformer T2, the other end of the primary winding of the transformer T2 is connected to the reference ground, and the secondary winding of the transformer T2 is connected to Output the input terminal of the rectifier 201, the output terminal of the output rectifier 201 is connected to the output capacitor Co;

The specific embodiment of the utility model shown in Figure 19 is essentially a quasi-single-stage AC-DC converter because the soft-switching high power factor correction circuit and the DC-DC conversion circuit share the switch bridge arm, which is relatively traditional The number of components of the two-stage AC-DC converter is reduced, and the PFM+PWM control circuit or PFM control circuit shown in Figure 16 can be directly used without adding additional control circuits. Furthermore, compared with the quasi-single-stage AC-DC converter composed of the traditional boost circuit + LLC DC-DC circuit, the voltage gain of the soft-switching high power factor correction circuit is reduced due to the voltage division effect of the capacitor C1, as shown in Figure 19 The specific embodiment of the utility model can obtain a lower DC bus voltage (V _CB ), which reduces the voltage stress of the switch tube, so it can be used in the 90V-265V AC input range, and the traditional boost circuit + LLC DC-DC The quasi-single-stage AC-DC converter formed by the circuit can generally only be applied to low input voltage occasions.

Fig. 20 shows the third specific embodiment of the soft-switching high power factor AC-DC converter of the present invention, wherein the load is a half-bridge flyback circuit. The switching tube of the half-bridge flyback circuit is multiplexed with the switching tube of the soft-switching high power factor correction circuit. The half-bridge flyback circuit also includes a DC blocking capacitor Cx, a transformer T3, an output rectifier Do, and an output capacitor Co; one end of the DC blocking capacitor Cx is connected to the source of the switching tube Q1 and the drain of the switching tube Q2, and the DC blocking capacitor The other end of Cx is connected to the same-named end of the primary winding of transformer T3, the opposite-named end of the primary winding of transformer T3 is connected to the reference ground, the opposite-named end of the secondary winding of transformer T3 is connected to the input end of the output rectifier Do, and the output rectifier Do The output terminal is connected to the positive terminal of the output capacitor Co, and the negative terminal of the output capacitor Co is connected to the terminal with the same name of the secondary winding of the transformer T3;

Similarly, FIG. 20 shows that the specific embodiment of the present invention is also a quasi-single-stage AC-DC converter, which can also obtain a lower DC bus voltage (V _CB ).

Fig. 21 shows the fourth specific embodiment of the soft-switching high power factor AC-DC converter of the present invention, wherein the load is a half-bridge LLC resonant DC-DC conversion circuit, the switch tube and the soft-switching high power factor correction circuit The switching tube is multiplexed. The specific embodiment of the utility model shown in FIG. 21 is only different from the specific embodiment in FIG. 19 in the connection mode, and is substantially equivalent in function, so it will not be described in detail.

Similarly, the load of the specific embodiment shown in FIG. 21 may also be a half-bridge flyback circuit, forming a circuit structure substantially equivalent to that of the specific embodiment shown in FIG. 20 .

The rectifier tube D1, the rectifier tube D2, the freewheel tube D3 and the freewheel tube D4 in the soft-switching high power factor AC-DC converter of the present utility model can be diodes, and can also be partially or completely replaced by MOSFETs to reduce the on-state loss. Fig. 22 shows a specific embodiment in which the rectifier tube D1, rectifier tube D2, freewheeling tube D3, and freewheeling tube D4 of the soft-switching high power factor AC-DC converter of the present invention all use MOSFETs.

The specific modules included in the present invention can be implemented in various ways by those skilled in the art without violating its spirit, or can be combined in various ways to form different specific embodiments, which will not be described in detail here.

No matter how detailed the above description is, there are many ways to implement the utility model, and what is described in the description is only some specific implementation examples of the utility model. All equivalent transformations or modifications made according to the spirit of the utility model shall fall within the protection scope of the utility model.

The above detailed descriptions of the embodiments of the present invention are not intended to be exhaustive or to limit the present invention to the above-mentioned specific forms. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.

While the above description describes certain embodiments of the invention and describes the best mode contemplated, no matter how detailed the above description appears, the invention can be practiced in many ways. The details of the above-mentioned circuit structure and its control method can be changed quite a lot in its implementation details, but it is still included in the utility model disclosed here.

As mentioned above, it should be noted that the special terms used when describing some features or solutions of the present utility model should not be used to indicate that the term is redefined here to limit some specific features of the utility model related to the term, features or schemes. In conclusion, the terms used in the following claims should not be construed to limit the invention to the particular embodiments disclosed in the specification, unless the above detailed description expressly defines those terms. Accordingly, the actual scope of the invention includes not only the disclosed embodiments, but also all equivalents of implementing or implementing the invention under the claims.

Claims (8)

1. Soft-switching high power factor AC-DC converter, characterized in that: the soft-switching high power factor AC-DC converter includes a soft-switching power factor correction circuit, wherein The soft switching power factor correction circuit includes: a filter, a rectifier tube D1, a rectifier tube D2, a freewheel tube D3, a freewheel tube D4, an inductor L1, a capacitor C1, a switch tube Q1, a switch tube Q2, and a capacitor CB; Among them, one input terminal of the filter is connected to one end of the AC source Vac, the other input terminal of the filter is connected to the other end of the AC source Vac, one output terminal of the filter is connected to the anode of the rectifier tube D1 and the cathode of the rectifier tube D2, one of the filter The output terminal is connected to the anode of the freewheeling tube D3 and the cathode of the freewheeling tube D4, the cathode of the rectifier tube D1 is connected to the cathode of the freewheeling tube D3, the drain of the switching tube Q1 and the positive terminal of the capacitor CB, and the anode of the rectifier tube D2 is connected to the freewheeling tube The anode of D4, the source of the switching tube Q2, the negative terminal of the capacitor CB and the reference ground, the anode of the freewheeling tube D3 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the switch The source of the transistor Q1, the drain of the switching transistor Q2, and the gates of the switching transistor Q1 and the switching transistor Q2 are respectively connected to the output signal terminal of the control circuit. 2. The soft-switching high power factor AC-DC converter according to claim 1, characterized in that: A load is also included, the load is connected between the positive terminal and the negative terminal of the capacitor CB, and the load is a resistor, an LED, a storage battery or a DC-DC conversion circuit. 3. The soft-switching high power factor AC-DC converter according to claim 1, characterized in that: A load is also included, the load is connected between the midpoint of the switching bridge arm formed by the switching tube Q1 and the switching tube Q2 and the negative terminal of the capacitor CB, and the load is a resistance or a DC-DC conversion circuit. 4. The soft-switching high power factor AC-DC converter according to claim 1, characterized in that: It also includes a load, the load is connected between the midpoint of the switching bridge arm formed by the switching tube Q1 and the switching tube Q2 and the midpoint of the two series capacitors forming the capacitor CB, and the load is a resistor or a DC-DC conversion circuit. 5. The soft-switching high power factor AC-DC converter according to claim 3, characterized in that: The load is a half-bridge LLC resonant DC-DC conversion circuit; the switch tube of the half-bridge LLC resonant DC-DC conversion circuit is multiplexed with the switch tube of the soft-switching high power factor correction circuit, and the half-bridge LLC resonant DC - The DC conversion circuit also includes a resonant inductor Lr, a resonant capacitor Cr, a transformer T2, an output rectifier circuit, and an output capacitor Co; one end of the resonant inductor Lr is connected to the source of the switching tube Q1 and the drain of the switching tube Q2, and the other end of the resonant inductor Lr One end is connected to one end of the resonant capacitor Cr, the other end of the resonant capacitor Cr is connected to one end of the primary winding of the transformer T2, the other end of the primary winding of the transformer T2 is connected to the reference ground, the secondary winding of the transformer T2 is connected to the input end of the output rectifier, and the output rectifier The output terminal is connected to the output capacitor Co. 6. The soft-switching high power factor AC-DC converter according to claim 3, characterized in that: The load is a half-bridge flyback circuit; the switch tube of the half-bridge flyback circuit is multiplexed with the switch tube of the soft-switching high power factor correction circuit; the half-bridge flyback circuit also includes a DC blocking capacitor Cx, a transformer T3, output rectifier tube Do, output capacitor Co; one end of the DC blocking capacitor Cx is connected to the source of the switch tube Q1 and the drain of the switch tube Q2, and the other end of the DC blocking capacitor Cx is connected to the same name end of the primary winding of the transformer T3, the transformer The different-name terminal of the primary winding of T3 is connected to the reference ground, the different-name terminal of the secondary winding of the transformer T3 is connected to the input terminal of the output rectifier Do, the output terminal of the output rectifier Do is connected to the positive terminal of the output capacitor Co, and the negative terminal of the output capacitor Co is connected to Terminal with the same name of the secondary winding of transformer T3. 7. The soft-switching high power factor AC-DC converter according to claim 1, characterized in that: The rectifier D1, rectifier D2, freewheel D3 and freewheel D4 in the soft-switching high power factor AC-DC converter are diodes. 8. The soft-switching high power factor AC-DC converter according to claim 1, characterized in that: Part or all of the rectifier tube D1, rectifier tube D2, freewheel tube D3, and freewheel tube D4 in the soft-switching high power factor AC-DC converter are MOSFETs.