CN209593312U - Sofe Switch High Power Factor A.C.-D.C. converter - Google Patents
Sofe Switch High Power Factor A.C.-D.C. converter Download PDFInfo
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- CN209593312U CN209593312U CN201821774471.8U CN201821774471U CN209593312U CN 209593312 U CN209593312 U CN 209593312U CN 201821774471 U CN201821774471 U CN 201821774471U CN 209593312 U CN209593312 U CN 209593312U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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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
Technical Field
The utility model belongs to the technical field of switching power supply, a soft switch high power factor exchanges-direct current converter is related to.
Background
The wide application of power electronic devices causes serious pollution to public power grids, and the problems of harmonic waves and reactive power are increasingly emphasized. In order to reduce the harm degree of the electric power pollution, corresponding standards are made by many countries, such as the harmonic standard 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 that a PFC circuit is often used in a front stage of an ac-dc Power electronic converter.
Fig. 1 shows the topology of a conventional two-stage ac-dc power electronic converter. The front stage usually adopts a Boost (Boost) circuit as power factor correction to realize alternating current-direct current energy conversion and output stable direct current voltage; and the rear stage adopts a high-efficiency half-bridge LLC resonant converter to realize the functions of isolation and voltage reduction.
The Boost circuit as a preceding stage power factor correction circuit has the advantages of simple structure and easy acquisition of higher power factor, but has certain defects, such as larger reverse recovery problem of a freewheeling diode when a current continuous mode is adopted, and the efficiency is reduced because the switching process is hard switching; if an intermittent mode is adopted, the peak value of input current is large, the switching process is hard switching, the efficiency is low, and in addition, the size of the inductor is large; by adopting the current critical conduction mode, although zero voltage switching-on of the switching tube can be realized to reduce loss, the voltage at two ends of the inductance winding is detected, the complexity of control is increased, and in addition, under the condition of high-voltage input, only the switching tube can be switched on at the bottom of the resonance valley, and complete soft switching cannot be realized.
Disclosure of Invention
The utility model provides a soft switch high power factor exchanges DC converter, soft switch high power factor exchanges DC converter includes soft switch power factor correction circuit, wherein
The soft switching power factor correction circuit includes: the filter, the rectifier tube D1, the rectifier tube D2, the follow current tube D3, the follow current tube D4, the inductor L1, the capacitor C1, the switch tube Q1, the switch tube Q2 and the capacitor CB;
one input end of the filter is connected with one end of an alternating current source Vac, the other input end of the filter is connected with the other end of the alternating current source Vac, one output end of the filter is connected with the anode of a rectifier tube D1 and the cathode of a rectifier tube D2, one output end of the filter is connected with the anode of a rectifier tube D3 and the cathode of a follow current tube D4, the cathode of a rectifier tube D1 is connected with the cathode of a rectifier tube D3, the drain of a switch tube Q1 and the positive end of a capacitor CB, the anode of a rectifier tube D2 is connected with the anode of a rectifier tube D4, the source of a switch tube Q2, the negative end of a capacitor CB and reference ground, the anode of a follow current tube D3 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C1, the other end of a capacitor C1 is connected with the source of a switch tube Q1 and the drain of a switch tube;
the soft switching power factor correction circuit realizes the correction of the alternating current input current, so that the waveform of the alternating current input current is close to a sine wave, and a direct current voltage is output at two ends of a capacitor CB;
preferably, the load is connected between the positive end (end A) and the negative end (end B) of the capacitor CB, and the load is a passive load such as a resistor, an LED, a storage battery and the like or a direct current-direct current conversion circuit;
preferably, the load is connected between a midpoint (a C end) of a switch arm formed by the switch tube Q1 and the switch tube Q2 and a negative end (a B end) of the capacitor CB, and the load can be a resistor or a dc-dc conversion circuit;
preferably, the load is connected between a midpoint (end C) of a switch arm formed by the switch tube Q1 and the switch tube Q2 and a midpoint (end D) of two series capacitors forming the capacitor CB, and the load can be a resistor or a dc-dc conversion circuit;
the direct current-direct current conversion circuit carries out direct current voltage conversion or converts direct current voltage at two ends of the capacitor CB into direct current;
preferably, the soft-switching high power factor ac-dc converter further comprises a control circuit, and the control circuit may be PFM control, PWM control or PFM + PWM control;
preferably, the control circuit comprises a PFM control error amplifying unit, a sawtooth wave generating circuit, a PWM control error amplifying unit, a comparator Com2, and a driving signal generating circuit.
Further, the PFM control error amplifying element 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 terminal to receive an output voltage or current signal fed back by the main circuit, the other end of the resistor R1 is connected to one end of the first compensation network and a negative input terminal of the operational amplifier OP1, a positive input terminal of the operational amplifier OP1 is connected to a positive terminal of the voltage reference Vref1, a negative terminal of the voltage reference Vref1 is connected to a ground, and an output terminal of the first compensation network is connected to an output terminal of the first operational amplifier OP 1; the PFM control error amplification link compares and amplifies a signal difference value between a signal received by the FB and a voltage reference Vref1 to generate an error amplification signal Vcomp 1;
the sawtooth wave generating circuit comprises a voltage reference Vref2, a voltage-controlled current source VCI, a capacitor C1, a switch S1, a voltage reference Vref4 and a comparator Com1, wherein the negative input end of the voltage-controlled current source VCI is connected with the output end of an operational amplifier OP1, the positive input end of the voltage-controlled current source VCI is connected with the positive end of the voltage reference Vref3, the negative end of the voltage reference Vref3 is connected with the reference ground, one output end of the voltage-controlled current source VCI is connected with the reference ground, the other output end of the voltage-controlled current source VCI is connected with one end of the capacitor C1, one end of the switch S1 and the negative input end of the comparator Com1, the positive input end of the comparator Com1 is connected with the control end of the comparator Com1 at one end of; the sawtooth wave generating circuit generates a sawtooth wave signal Vsaw with variable frequency according to the received error amplifying signal Vcomp 1;
the PWM control error amplification link comprises a resistor R2, a second compensation network, an operational amplifier OP2, a voltage reference Vref2 and a limiter LIMV, wherein one end of the resistor R2 is connected with the VFB end and receives an output voltage signal fed back by a main circuit, the other end of the resistor R2 is connected with 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 with the positive end of the voltage reference Vref2, the negative end of the voltage reference Vref2 is connected with the ground, the output end of the second compensation network is connected with the output end of the operational amplifier OP2, the output end of the operational amplifier OP2 is connected with the input end of the limiter LIMV2, and the output end of the limiter LIMV2 outputs an error amplification signal Vcomp 685; the PWM control error amplification link compares a signal difference value between a signal received by the VFB and a voltage reference Vref1, amplifies the signal and outputs an error amplification signal Vcomp2 after the amplitude is limited by a limiter LIMV;
the negative input end of the comparator Com2 is connected with the output end of the sawtooth wave generating circuit and receives a sawtooth wave signal Vsaw, the positive input end of the comparator Com2 is connected with the output end of the PWM control error amplifying link and receives an error amplifying signal Vcomp2 output by the comparator Com 2; the comparator Com2 compares the received sawtooth wave signal Vsaw with the error amplification signal Vcomp2, and outputs a pulse signal Vpulse;
the driving signal generating circuit comprises an inverter INV, a first delay circuit, a second delay circuit, an AND gate AND1, an AND gate AND2 AND a driving circuit; the input end of the inverter INV is connected with the input end of the second delay circuit AND one input end of the AND gate AND2 to receive the pulse signal Vpulse, the output end of the inverter INV is connected with the input end of the first delay circuit AND one input end of the AND gate AND1, the output end of the AND gate AND1 is connected with one input end of the driving circuit, AND two output ends of the driving circuit respectively output the driving signal Vg_Q1And Vg_Q2(ii) a The first delay circuit and the second delay circuit generate delay time Td1 and Td2 respectively for generating a driving signal Vg_Q1And Vg_Q2The drive circuit is used for enhancing the drive capability and the drive signal bootstrap.
Preferably, the soft-switching high-power-factor ac-dc converter comprises the soft-switching power factor correction circuit and a half-bridge LLC resonant dc-dc conversion circuit, a switching tube of the half-bridge LLC resonant dc-dc conversion circuit is multiplexed with a switching tube of the soft-switching high-power-factor correction circuit, and the half-bridge LLC resonant dc-dc conversion circuit further comprises a resonant inductor Lr, a resonant capacitor Cr, a transformer T2, an output rectification circuit, and an output capacitor Co; one end of a resonant inductor Lr is connected with the source electrode of a switch tube Q1 and the drain electrode of a switch tube Q2, the other end of the resonant inductor Lr is connected with one end of a resonant capacitor Cr, the other end of the resonant capacitor Cr is connected with one end of a primary winding of a transformer T2, the other end of the primary winding of the transformer T2 is connected with the reference ground, a secondary winding of the transformer T2 is connected with the input end of an output rectifier, and the output end of the output rectifier is connected with an output capacitor Co;
preferably, the soft-switching high-power-factor ac-dc converter comprises the soft-switching power factor correction circuit and a half-bridge flyback circuit, and a switching tube of the half-bridge flyback circuit is multiplexed with a switching tube of the soft-switching high-power-factor correction circuit. The half-bridge flyback circuit further comprises a blocking capacitor Cx, a transformer T3, an output rectifier tube Do and an output capacitor Co; one end of a blocking capacitor Cx is connected with the source electrode of a switch tube Q1 and the drain electrode of a switch tube Q2, the other end of the blocking capacitor Cx is connected with the dotted end of the primary winding of a transformer T3, the dotted end of the primary winding of the transformer T3 is connected with the reference ground, the dotted end of the secondary winding of the transformer T3 is connected with the input end of an output rectifier Do, the output end of the output rectifier Do is connected with the output end of an output capacitor Co, and the positive end of the output capacitor Co is connected with the dotted end of the secondary winding of the transformer T3;
preferably, the rectifier D1, the rectifier D2, the freewheeling tube D3 and the freewheeling tube D4 in the soft-switching high power factor AC-DC converter are diodes,
preferably, the rectifier D1, the rectifier D2, the freewheeling tube D3 and the freewheeling tube D4 in the soft-switching high power factor ac-dc converter can also be partially or completely MOSFETs.
The beneficial effects of the utility model reside in that: the utility model provides a soft switch high power factor AC-DC converter which can realize the zero voltage switching-on (soft switch) of the switch tube of the power factor correction circuit in the full input voltage range and obtain higher power factor; only one input rectifying tube is conducted in each half power frequency period, so that the loss of the input rectifying tube is reduced; the utility model discloses a quasi-single-stage soft switch power factor correction circuit that connected mode constitutes compares with traditional Boost type quasi-single-stage circuit, and bus voltage can greatly reduced, consequently can reduce the voltage stress of switch tube, is applied to full voltage input scope (90V-265 Vac).
Drawings
FIG. 1 is a prior art two-stage AC-DC power electronic converter;
fig. 2 shows a first circuit structure diagram of the soft switching high power factor ac-dc converter of the present invention;
fig. 3 shows a second circuit structure diagram of the soft switching high power factor ac-dc converter of the present invention;
fig. 4 shows a third circuit structure diagram of the soft switching high power factor ac-dc converter of the present invention;
fig. 5 shows a portion of the key waveforms of the soft-switching high power factor ac-dc converter of the present invention;
fig. 6 shows an equivalent circuit schematic diagram of the soft-switching high power factor circuit in the first operating mode of the present invention;
fig. 7 shows an equivalent circuit schematic diagram of the soft-switching high power factor circuit in the second operating mode of the present invention;
fig. 8 shows an equivalent circuit schematic diagram of the soft-switching high power factor circuit in the third operating mode of the present invention;
fig. 9 shows an equivalent circuit schematic diagram of the soft-switching high power factor circuit in the fourth operating mode of the present invention;
fig. 10 shows an equivalent circuit schematic diagram of the soft-switching high power factor circuit in the fifth operating mode of the present invention;
fig. 11 shows an equivalent circuit schematic diagram of the soft-switching high power factor circuit according to the sixth operating mode of the present invention;
fig. 12 is a schematic diagram of an equivalent circuit of the soft-switching high power factor circuit in the seventh operating mode of the present invention;
fig. 13 shows an equivalent circuit schematic diagram of the soft-switching high power factor circuit in the eighth operating mode of the present invention;
fig. 14 shows a half power frequency cycle ac input current calculation curve of the soft switching high power factor ac-dc converter of the present invention;
fig. 15 shows a relationship curve of the operating frequency of the soft-switching high power factor ac-dc converter with a constant dc bus voltage and ac input voltage;
figure 16 shows an embodiment of a PFM + PWM control circuit suitable for use in a soft-switching high power factor ac-dc converter of the present invention;
FIG. 17 illustrates some of the key waveforms of the control circuit shown in FIG. 16;
fig. 18 shows a first embodiment of a soft-switched high power factor ac-dc converter of the present invention;
fig. 19 shows a second embodiment of the soft-switched high power factor ac-dc converter of the present invention;
fig. 20 illustrates a third embodiment of the soft-switched high power factor ac-dc converter of the present invention;
fig. 21 illustrates a fourth embodiment of the soft-switched high power factor ac-dc converter of the present invention;
fig. 22 shows a schematic diagram of the soft-switched high power factor circuit of the present invention after MOSFETs are used for rectifiers D1, D2 and freewheeling transistors D3, D4;
Detailed Description
The present invention will be described in detail below with reference to the circuit diagram of the present invention.
Referring to fig. 2, a first block diagram of a soft-switching high power factor ac-dc converter of the present invention includes a soft-switching power factor correction circuit and a load;
the soft switching power factor correction circuit includes: the filter, the rectifier tube D1, the rectifier tube D2, the follow current tube D3, the follow current tube D4, the inductor L1, the capacitor C1, the switch tube Q1, the switch tube Q2 and the capacitor CB; one input end of the filter is connected with one end of an alternating current source Vac, the other input end of the filter is connected with the other end of the alternating current source Vac, one output end of the filter is connected with the anode of a rectifier tube D1 and the cathode of a rectifier tube D2, one output end of the filter is connected with the anode of a rectifier tube D3 and the cathode of a follow current tube D4, the cathode of a rectifier tube D1 is connected with the cathode of a rectifier tube D3, the drain of a switch tube Q1 and the positive end of a capacitor CB, the anode of a rectifier tube D2 is connected with the anode of a rectifier tube D4, the source of a switch tube Q2, the negative end of a capacitor CB and reference ground, the anode of a follow current tube D3 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C1, the other end of a capacitor C1 is connected with the source of a switch tube Q1 and the drain of a switch tube;
the load is connected between the positive end (A end) and the negative end (B end) of the capacitor CB, and the load is a passive load such as a resistor, an LED, a storage battery and the like or a direct current-direct current conversion circuit;
referring to fig. 3, a second block diagram of a soft-switching high power factor ac-dc converter of the present invention includes a soft-switching power factor correction circuit and a load;
the soft switching power factor correction circuit includes: the filter, the rectifier tube D1, the rectifier tube D2, the follow current tube D3, the follow current tube D4, the inductor L1, the capacitor C1, the switch tube Q1, the switch tube Q2 and the capacitor CB; one input end of the filter is connected with one end of an alternating current source Vac, the other input end of the filter is connected with the other end of the alternating current source Vac, one output end of the filter is connected with the anode of a rectifier tube D1 and the cathode of a rectifier tube D2, one output end of the filter is connected with the anode of a rectifier tube D3 and the cathode of a follow current tube D4, the cathode of a rectifier tube D1 is connected with the cathode of a rectifier tube D3, the drain of a switch tube Q1 and the positive end of a capacitor CB, the anode of a rectifier tube D2 is connected with the anode of a rectifier tube D4, the source of a switch tube Q2, the negative end of a capacitor CB and reference ground, the anode of a follow current tube D3 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C1, the other end of a capacitor C1 is connected with the source of a switch tube Q1 and the drain of a switch tube;
the load is connected between the midpoint (C end) of a switch bridge arm formed by the switch tube Q1 and the switch tube Q2 and the negative end (B end) of the capacitor CB, and the load can be a resistor or a direct current-direct current conversion circuit;
referring to fig. 4, a third block diagram of a soft-switching high power factor ac-dc converter of the present invention includes a soft-switching power factor correction circuit and a load;
the soft switching power factor correction circuit includes: the filter, the rectifier tube D1, the rectifier tube D2, the follow current tube D3, the follow current tube D4, the inductor L1, the capacitor C1, the switch tube Q1, the switch tube Q2 and the capacitor CB; one input end of the filter is connected with one end of an alternating current source Vac, the other input end of the filter is connected with the other end of the alternating current source Vac, one output end of the filter is connected with the anode of a rectifier tube D1 and the cathode of a rectifier tube D2, one output end of the filter is connected with the anode of a rectifier tube D3 and the cathode of a follow current tube D4, the cathode of a rectifier tube D1 is connected with the cathode of a rectifier tube D3, the drain of a switch tube Q1 and the positive end of a capacitor CB, the anode of a rectifier tube D2 is connected with the anode of a rectifier tube D4, the source of a switch tube Q2, the negative end of a capacitor CB and the reference ground, the anode of a follow current tube D3 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C1, the other end of a capacitor C1 is connected with the source of a switch tube Q1 and the drain of a switch tube;
the capacitor CB is formed by serially connecting a capacitor CB1 and a capacitor CB2, the load is connected between the midpoint (C end) of a switch arm formed by the switch tube Q1 and the switch tube Q2 and the midpoint (D end) of the capacitor CB1 and the capacitor CB2, and the load can be a resistor or a direct current-direct current conversion circuit;
referring to fig. 5, a part of the key waveforms of the soft switching high power factor ac-dc converter of the present invention is shown, where VacRepresenting the AC input voltage, V, supplied by the networkc1_avgWaveform i after filtering high frequency components for capacitor C1 voltageLRepresenting the current, i, through the inductor L1acRepresenting the AC bus current, i, flowing into the grid via a filterinRepresenting the ac bus current before the filter, Vg_Q1And Vg_Q2Respectively showing the gate voltages i of the switching tube Q1 and the switching tube Q2Q1And iQ2Respectively represent the current flowing through the switch tube Q1 and the switch tube Q2; wherein, for the sake of simplicity, Vg_Q1And Vg_Q2Respectively only the AC input voltage VacThe waveforms, one switching cycle for each of the positive and negative half cycles, are used to describe the operation of the circuit and do not take into account dead time.
When the ac input voltage Vac is in a positive half cycle, the operation of the circuit can be simply divided into four stages:
first stage [ t0-t1]: at time t0, switch Q2 is turned off due to iLIs negative, corresponding to iQ1Is also negative, therefore iQ1First, the current flows through the body diode of the switching tube Q1, so that the switching tube Q1 is turned on at zero voltage, the freewheeling tube D3 remains turned on, and the equivalent circuit is as shown in fig. 6. During this time, the inductor L1 and the capacitor C1 resonate, iLRising from the negative maximum value resonance, the loop equation is;
wherein, VCBThe voltage at the two ends of the capacitor CB, i.e. the dc bus voltage.
Second stage [ t1-t2]: at time t1, due to iLWhen the voltage rises to zero, the freewheeling tube D3 is turned off, the rectifying tube D1 is turned on, the freewheeling tube D3 is turned off, and the equivalent circuit is shown in FIG. 7. During this time, the inductor current iL1The resonance rises, and the loop equation is:
third stage [ t2-t3]: at time t2, switching tube Q1 is turned off, and inductor current iLFirst, the current flows through the body diode of the switching tube Q2, so that the switching tube Q2 is turned on at zero voltage, the rectifying tube D1 is kept conducting, and the equivalent circuit is as shown in fig. 8. During this time, the inductor current iLThe resonance drops, and the loop equation is:
fourth stage [ t3-t4]: at time t3, inductor current iLWhen the voltage drops to zero, the rectifier D1 is turned off, the freewheeling diode D4 is turned on, and the equivalent circuit is as shown in fig. 9. During this time, the inductor current iL1Continuing to decrease the resonance, the loop equation is:
when the ac input voltage is negative half cycle, the operation process of the circuit is similar according to the symmetry of the circuit, the rectifier tube D2 and the freewheeling tube D3 are turned on, and referring to the waveforms at times t5-t9, the operation process of the circuit can be divided into four stages, and the equivalent circuits of each stage are shown in fig. 10-13, which are not analyzed in detail here.
The circuit analysis shows that only one rectifier tube is conducted in each half power frequency period, so that the loss of the rectifier circuit is lower than that of the traditional rectifier circuit; in addition, the switching tube Q1 and the switching tube Q2 can both realize zero voltage conduction, i.e. soft switching is realized.
The expression of the alternating current input current in a half power frequency period can be calculated according to the analysis approximation as follows:
wherein,the expression for the switching period Ts is:
the waveform of the ac input current iac obtained according to equations (5) and (6) is shown in fig. 14, and it can be seen that the ac input current waveform is very close to sinusoidal, so that the relationship between the switching frequency and the effective value of the ac input voltage of the soft-switching high power factor circuit under certain operating conditions can be calculated as shown in fig. 15. As can be seen from fig. 15, the gain of the dc bus voltage with respect 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 one skilled in the art can also know, the PWM method for adjusting duty ratio controls the voltage gain of the soft switching high power factor circuit of the present invention at a certain switching frequency, and the purpose of adjusting output voltage/current can be achieved as well. Therefore, the utility model discloses a soft switch high power factor circuit can adopt PFM control, PWM control, or the hybrid control mode of PFM + PWM control. The above control methods are not limited to all possible control methods applicable to the soft switching high power factor circuit of the present invention, and those skilled in the art should find out other suitable control methods without difficulty for the spirit of the present invention.
According to the circuit relationship, the voltage value V of the capacitor C1 after the high-frequency component is filtered can be further deducedc1_avgEqual to the AC input voltage Vac1/2, therefore, the capacitor C1 also functions to divide the ac input voltage, so that the voltage gain of the soft-switching high power factor circuit of the present invention is lower than that of the conventional Boost circuit.
Fig. 16 is a schematic diagram of an embodiment of a PFM + PWM control circuit suitable for an ac-dc converter according to the present invention; the control circuit comprises a PFM control error amplification link 101, a sawtooth wave generation circuit 102, a PWM control error amplification link 103, a comparator Com2 and a driving signal generation circuit 104.
Further, the PFM control error amplifying 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 terminal to receive an output voltage or current signal fed back by the main circuit, the other end of the resistor R1 is connected to one end of the compensation network 1 and a negative input terminal of the operational amplifier OP1, a positive input terminal of the operational amplifier OP1 is connected to a positive terminal of the voltage reference Vref1, a negative terminal of the voltage reference Vref1 is connected to a ground, and an output terminal of the compensation network 1 is connected to an output terminal of the operational amplifier OP 1; the PFM control error amplification link 101 compares and amplifies a signal difference between a signal received by the FB and a voltage reference Vref1 to generate an error amplification signal Vcomp 1;
the sawtooth wave generation circuit 102 comprises a voltage reference Vref2, a voltage-controlled current source VCI, a capacitor C1, a switch S1, a voltage reference Vref4 and a comparator Com1, wherein the negative input end of the voltage-controlled current source VCI is connected with the output end of an operational amplifier OP1, the positive input end of the voltage-controlled current source VCI is connected with the positive end of the voltage reference Vref3, the negative end of the voltage reference Vref3 is connected with the reference ground, one output end of the voltage-controlled current source VCI is connected with the reference ground, the other output end of the voltage-controlled current source VCI is connected with one end of the capacitor C1, one end of the switch S1 and the negative input end of the comparator Com1, the positive input end of the comparator Com1 is connected with the control end of the switch S1, and the other end; the sawtooth wave generating circuit 102 generates a sawtooth wave signal Vsaw with variable frequency according to the received error amplifying signal Vcomp 1;
the PWM control error amplifying link 103 comprises a resistor R2, a compensation network 2, an operational amplifier OP2, a voltage reference Vref2 and a limiter LIMV, wherein one end of the resistor R2 is connected with the VFB terminal to receive an output voltage signal fed back by the main circuit, the other end of the resistor R2 is connected with one end of the compensation network 2 and the negative input end of the operational amplifier OP2, the positive input end of the operational amplifier OP2 is connected with the positive end of the voltage reference Vref2, the negative end of the voltage reference Vref2 is connected with the ground, the output end of the compensation network 2 is connected with the output end of the operational amplifier OP2, the output end of the operational amplifier OP2 is connected with the input end of the limiter LIMV2, and the output end of the limiter LIMV2 outputs an error amplification signal Vcomp 2; the PWM control error amplification link 103 compares a signal difference value between a signal received by the VFB and a voltage reference Vref1, amplifies the signal, and outputs an error amplification signal Vcomp2 after the amplitude is limited by a limiter LIMV;
the negative input end of the comparator Com2 is connected with the output end of the sawtooth wave generating circuit 102 and receives the sawtooth wave signal Vsaw, the positive input end of the comparator Com2 is connected with the output end of the PWM control error amplifying link 103 and receives the error amplifying signal Vcomp2 output by the comparator Com 2; the comparator Com2 compares the received sawtooth wave signal Vsaw with the error amplification signal Vcomp2, and outputs a pulse signal Vpulse;
the driving signal generating circuit 104 comprises an inverter INV, a delay circuit 1, a delay circuit 2, an AND gate AND1, an AND gate AND2 AND a driving circuit 1041; the input end of the inverter INV is connected to the input end of the delay circuit 2 AND one input end of the AND gate AND2 for receiving the pulse signal Vpulse, the output end of the inverter INV is connected to the input end of the delay circuit 1 AND one input end of the AND gate AND1, the output end of the AND gate AND1 is connected to one input end of the driving circuit, AND two output ends of the driving circuit 1041 respectively output the driving signal Vg_Q1And Vg_Q2(ii) a The delay circuitThe circuit 1 and the delay circuit 2 generate delay times Td1 and Td2, respectively, for generating the driving signal Vg_Q1And Vg_Q2The driving circuit 1041 is used for enhancing the driving capability and the driving signal bootstrap.
FIG. 17 shows key waveforms for the control circuit of FIG. 16, including schematic diagrams for both PFM control and PWM control;
in the first case: when the output voltage is low so that the output voltage feedback signal VFB is constantly lower than the voltage reference Vref2, the Vcomp2 is in a constant high state, so that the Vcomp2 is clamped at Vref4/2 due to the action of the limiter LIMV; the PFM control error amplification link 101 plays a role in circuit adjustment, outputs a Vcomp1 signal influenced by circuit conditions, and the difference between the Vcomp1 signal and Vref3 changes the output current of the voltage-controlled current source VCI, so that the frequency of the sawtooth wave Vsaw is adjusted, and the peak value of the sawtooth wave Vsaw is constantly equal to Vref 4; vcomp2 is compared with Vsaw to output a pulse signal Vpulse with a duty ratio equal to 50% and a frequency consistent with the frequency of the sawtooth wave Vsaw, and a driving signal V with a variable frequency and a duty ratio close to 50% is output by a driving signal generating circuit 104g_Q1And Vg_Q2(ii) a The regulation process of the circuit is illustrated as follows: when the main circuit is affected by the external environment to increase the output voltage, so that the FB signal increases, the PFM control error amplification link 101 decreases Vcomp1, the difference between the Vcomp1 signal and Vref3 increases, so that the output current of the voltage-controlled current source VCI increases, the Vsaw frequency increases, and further the frequency of the driving signal increases, as can be seen from fig. 15, the operating frequency of the circuit decreases the gain of the circuit to decrease the output voltage, and therefore, the circuit can return to the steady state again by the negative feedback effect of the control circuit.
In the second case: when the output voltage is high, the feedback signal FB of the main circuit is constantly higher than the voltage reference Vref1, so that the Vcomp1 is in a constant low state, the feedback signal VFB of the output voltage reaches the voltage reference Vref2, the PWM control error amplification link 102 plays a role in circuit adjustment, and the error amplification signal Vcomp2 with adjustable amplitude is output. The difference between the voltage references Vref3 and Vcomp1 is constant, so the frequency of the sawtooth Vsaw is constant and the peak value is equal to Vref 2; vcomp2 with VsawAfter comparison, the pulse signal Vpulse with adjustable duty ratio and the frequency consistent with the sawtooth wave Vsaw is output, and further the drive signal V with adjustable duty ratio is output by the drive signal generating circuit 104g_Q1And Vg_Q2. The regulation process of the circuit is illustrated as follows: when the output voltage of the main circuit is increased due to external influence, so that the VFB signal is increased, the Vcomp2 is lowered through the PWM control error amplification link 102, so that the duty ratio of the pulse signal Vpulse is lowered, and further the duty ratio of the driving signal Vg _ Q1 is lowered and the duty ratio of Vg _ Q2 is raised; therefore, the conduction time of the switch tube S1 is reduced, so that the energy transferred by the inductor L1 in each switching period is reduced, and the output voltage is reduced. It can therefore be seen that the circuit can be brought back to steady state by the negative feedback action of the control circuit.
Fig. 18 shows a first embodiment of the soft-switched high power factor ac-dc converter of the present invention, wherein the load is a half-bridge LLC resonant dc-dc converter circuit; it will be appreciated by those skilled in the art that the load may be other types of dc-dc conversion circuits.
Fig. 19 shows a second 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 converter circuit, and the switching tube of the half-bridge LLC resonant dc-dc converter circuit is multiplexed with the switching tube of the soft-switching high power factor correction circuit. The half-bridge LLC resonant DC-DC conversion circuit further comprises a resonant inductor Lr, a resonant capacitor Cr, a transformer T2, an output rectifying circuit 201 and an output capacitor Co; one end of a resonant inductor Lr is connected with the source electrode of a switch tube Q1 and the drain electrode of a switch tube Q2, the other end of the resonant inductor Lr is connected with one end of a resonant capacitor Cr, the other end of the resonant capacitor Cr is connected with one end of a primary winding of a transformer T2, the other end of the primary winding of the transformer T2 is connected with the reference ground, a secondary winding of the transformer T2 is connected with the input end of an output rectifier 201, and the output end of the output rectifier 201 is connected with an output capacitor Co;
the embodiment of the present invention shown in fig. 19 is a quasi-single stage ac-dc converter in nature because the soft switching pfc circuit and the dc-dc converter circuit share a switching legCompared with the conventional two-stage AC-DC converter, the number of components of the converter is reduced, and a PFM + PWM control circuit or a PFM control circuit shown in FIG. 16 can be directly adopted without adding an additional control circuit. Further, compared with the quasi-single-stage ac-dc converter composed of the conventional boost circuit and LLC dc-dc circuit, the voltage gain of the soft-switching high power factor correction circuit is reduced due to the voltage dividing effect of the capacitor C1, as shown in fig. 19, the embodiment of the present invention can obtain a lower dc bus voltage (V bus voltage)CB) The voltage stress of the switching tube is reduced, so that the quasi-single-stage AC-DC converter formed by the traditional boost circuit and the LLC DC-DC circuit can be used in the AC input range of 90V-265V, and can only be applied to the occasions with low input voltage generally.
Fig. 20 shows a third embodiment of the soft-switched high power factor ac-dc converter of the present invention, wherein the load is a half-bridge flyback circuit. And the switching tube of the half-bridge flyback circuit is multiplexed with the switching tube of the soft switch high power factor correction circuit. The half-bridge flyback circuit further comprises a blocking capacitor Cx, a transformer T3, an output rectifier tube Do and an output capacitor Co; one end of a blocking capacitor Cx is connected with the source electrode of a switch tube Q1 and the drain electrode of a switch tube Q2, the other end of the blocking capacitor Cx is connected with the dotted end of the primary winding of a transformer T3, the dotted end of the primary winding of the transformer T3 is connected with the reference ground, the dotted end of the secondary winding of the transformer T3 is connected with the input end of an output rectifier tube Do, the output end of the output rectifier tube Do is connected with the positive end of an output capacitor Co, and the negative end of the output capacitor Co is connected with the dotted end of the secondary winding of the transformer T3;
similarly, fig. 20 shows that the 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 a fourth 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 converter circuit, and the switching tube of the soft-switching high power factor ac-dc converter circuit is multiplexed with the switching tube of the soft-switching high power factor correction circuit. The embodiment of the present invention shown in fig. 21 is different from the embodiment of fig. 19 only in the connection manner, and is substantially equivalent in function, so that detailed description thereof is omitted.
Similarly, the load of the embodiment shown in fig. 21 may also be a half-bridge flyback circuit, and form a circuit structure substantially equivalent to that of the embodiment shown in fig. 20.
The utility model discloses a rectifier tube D1, rectifier tube D2 and afterflow tube D3 among the soft switch high power factor AC-DC converter, afterflow tube D4 can be the diode, also can partly or wholly substitute MOSFET to reduce the on-state loss. Fig. 22 shows an embodiment of the present invention in which all of the rectifying tubes D1, D2, D3 and D4 of the soft-switching high power factor ac-dc converter employ MOSFETs.
The present invention includes various embodiments, or different combinations, which will not be described in detail herein, for those skilled in the art without departing from the spirit of the present invention.
No matter how detailed the above appears, there are many ways of implementing the invention, and what is described in the specification is merely some specific examples of the invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.
The above detailed description of embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed. 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 foregoing specification describes certain embodiments of the invention and describes the best mode contemplated, no matter how detailed the foregoing appears in text, the invention can be practiced in many ways. The details of the above-described circuit configuration and manner of controlling the same may vary considerably in its implementation details, while still being encompassed by the invention disclosed herein.
As noted above, it should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to certain specific characteristics, features or aspects of the invention with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification, unless the above detailed description section explicitly defines such terms. Accordingly, the actual scope of the invention encompasses not only the disclosed embodiments, but also all equivalent aspects that implement or perform the invention under the claims.
Claims (8)
1. The soft switch high power factor AC-DC converter is characterized in that: the soft-switching high power factor AC-DC converter comprises a soft-switching power factor correction circuit, wherein
The soft switching power factor correction circuit includes: the filter, the rectifier tube D1, the rectifier tube D2, the follow current tube D3, the follow current tube D4, the inductor L1, the capacitor C1, the switch tube Q1, the switch tube Q2 and the capacitor CB;
one input end of the filter is connected with one end of an alternating current source Vac, the other input end of the filter is connected with the other end of the alternating current source Vac, one output end of the filter is connected with the anode of a rectifier tube D1 and the cathode of a rectifier tube D2, one output end of the filter is connected with the anode of a rectifier tube D3 and the cathode of a follow current tube D4, the cathode of a rectifier tube D1 is connected with the cathode of a rectifier tube D3, the drain of a switch tube Q1 and the positive end of a capacitor CB, the anode of a rectifier tube D2 is connected with the anode of a rectifier tube D4, the source of a switch tube Q2, the negative end of a capacitor CB and reference ground, the anode of the follow current tube D3 is connected with one end of an inductor L1, the other end of the inductor L1 is connected with one end of a capacitor C1, the other end of a capacitor C1 is connected with the source of a switch tube Q1 and the drain of a switch.
2. The soft-switched high power factor ac-dc converter of claim 1, wherein:
the LED lamp also comprises a load, wherein the load is connected between the positive end and the negative end of the capacitor CB, and the load is a resistor, an LED, a storage battery or a direct current-direct current conversion circuit.
3. The soft-switched high power factor ac-dc converter of claim 1, wherein:
the load is connected between the midpoint of a switch arm formed by the switch tube Q1 and the switch tube Q2 and the negative end of the capacitor CB, and the load is a resistor or a direct current-direct current conversion circuit.
4. The soft-switched high power factor ac-dc converter of claim 1, wherein:
the load is connected between the midpoint of a switch arm formed by the switch tube Q1 and the switch tube Q2 and the midpoint of two series capacitors forming the capacitor CB, and the load is a resistor or a direct current-direct current conversion circuit.
5. The soft-switched high power factor ac-dc converter of claim 3, wherein:
the load is a half-bridge LLC resonant DC-DC conversion circuit; the switching tube of the half-bridge LLC resonant direct-current-direct-current conversion circuit is multiplexed with the switching tube of the soft-switching high-power-factor correction circuit, and the half-bridge LLC resonant direct-current-direct-current conversion circuit further comprises a resonant inductor Lr, a resonant capacitor Cr, a transformer T2, an output rectifying circuit and an output capacitor Co; one end of the resonant inductor Lr is connected with the source electrode of the switch tube Q1 and the drain electrode of the switch tube Q2, the other end of the resonant inductor Lr is connected with one end of the resonant capacitor Cr, the other end of the resonant capacitor Cr is connected with one end of the primary winding of the transformer T2, the other end of the primary winding of the transformer T2 is connected with the reference ground, the secondary winding of the transformer T2 is connected with the input end of the output rectifier, and the output end of the output rectifier is connected with the output capacitor Co.
6. The soft-switched high power factor ac-dc converter of claim 3, 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 switch high power factor correction circuit; the half-bridge flyback circuit further comprises a blocking capacitor Cx, a transformer T3, an output rectifier tube Do and an output capacitor Co; one end of the blocking capacitor Cx is connected with the source electrode of the switch tube Q1 and the drain electrode of the switch tube Q2, the other end of the blocking capacitor Cx is connected with the dotted end of the primary winding of the transformer T3, the dotted end of the primary winding of the transformer T3 is connected with the reference ground, the dotted end of the secondary winding of the transformer T3 is connected with the input end of the output rectifier Do, the output end of the output rectifier Do is connected with the output capacitor Co, and the positive end of the output capacitor Co is connected with the dotted end of the secondary winding of the transformer T3.
7. The soft-switched high power factor ac-dc converter of claim 1, wherein:
the rectifier D1, the rectifier D2, the follow current D3 and the follow current D4 in the soft-switching high power factor AC-DC converter are diodes.
8. The soft-switched high power factor ac-dc converter of claim 1, wherein:
a rectifier D1, a rectifier D2, a follow current D3 and a follow current D4 in the soft-switching high-power-factor alternating current-direct current converter are partially or completely MOSFETs.
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| CN201821774471.8U CN209593312U (en) | 2018-10-23 | 2018-10-23 | Sofe Switch High Power Factor A.C.-D.C. converter |
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| CN201821774471.8U CN209593312U (en) | 2018-10-23 | 2018-10-23 | Sofe Switch High Power Factor A.C.-D.C. converter |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109217699A (en) * | 2018-10-23 | 2019-01-15 | 杭州电子科技大学 | A kind of Sofe Switch High Power Factor A.C.-D.C. converter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109217699A (en) * | 2018-10-23 | 2019-01-15 | 杭州电子科技大学 | A kind of Sofe Switch High Power Factor A.C.-D.C. converter |
| CN109217699B (en) * | 2018-10-23 | 2024-02-02 | 杭州电子科技大学 | Soft-switching high-power-factor alternating current-direct current converter |
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