CN203233307U

CN203233307U - Bridgeless forward power factor correcting device

Info

Publication number: CN203233307U
Application number: CN2013202461268U
Authority: CN
Inventors: 谢小高; 蓝舟; 董汉菁
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2013-05-07
Filing date: 2013-05-07
Publication date: 2013-10-09
Anticipated expiration: 2023-05-07

Abstract

The utility model relates to a bridgeless forward power factor correcting device. When a traditional power factor correcting circuit works, the number of semiconductor power devices which are conducted at the same time is large, and the power consumption is large. The bridgeless forward power factor correcting device comprises two parts, a power main circuit and a control circuit. The main circuit comprises an input circuit, a transformer T and an output circuit. The control circuit comprises a feedback circuit outputting voltage or current, a phase detecting circuit where an alternating voltage is input, a magnetic reset detecting circuit of the transformer T, and a PFC controller and a driving circuit. Compared with a traditional Boost PFC circuit, just a single-stage circuit can satisfy a low-voltage application occasion and satisfy the requirement that a front stage and a rear stage of the circuit are isolated.

Description

A kind of no bridge normal shock power factor correcting device

Technical field

The utility model belongs to the switch power technology field, and being specifically related to a kind of isolated form does not have bridge positive activation type power factor correcting device.

Background technology

Because the non-linear element in present most of power consumption equipments and the existence of energy-storage travelling wave tube, can make the input AC current waveform that serious distortion takes place, net side input power factor is very low, in order to satisfy the harmonic requirement of international standard IEC61000-3-2, must in these power consumption equipments, add power factor correcting device (PFC).Traditional passive power factor corrective circuit adds the Boost topological structure after generally adopting rectifier bridge.Wherein, the Boost topology has control easily, drives simple and can carry out switch work in whole power frequency period, and the power factor of input current can be close to characteristics such as 1.But the Boost circuit has the high shortcoming of output voltage, and for the low voltage application occasion, the back level needs extra DC-DC reduction voltage circuit.In addition, this traditional power factor correction circuit is when work, and the semiconductor power device number of conducting simultaneously is more, and power loss is bigger.In order to reduce circuit loss, improve the conversion efficiency of circuit, non-bridge PFC circuits is studied widely and is used.

Summary of the invention

At above-mentioned deficiency, the utility model proposes a kind of novel no bridge normal shock power factor correcting device.Can realize the PFC function by the control to different switching tubes, and can make input current satisfy international standard IEC61000-3-2 C class standard.This device mainly comprises power main circuit and control circuit two parts.

The main circuit of the no bridge normal shock power factor correcting device that the utility model proposes mainly comprises the input side circuit, transformer T and outlet side circuit.

The input side circuit mainly comprises input voltage source Vac, capacitor C in, switching tube Q1 and switching tube Q2, diode D1 and diode D2; Wherein, diode D1, the first winding N1 and switching tube Q1 have constituted former limit major loop one; Diode D2, the second winding N2 and switching tube Q2 have constituted former limit major loop two; Specifically be the negative electrode of the terminating diode D1 of the same name of the first winding N1, the drain electrode of another termination switching tube Q1 of the first winding N1; The anode of diode D1 connects the end of input voltage source Vac, and the source electrode of switching tube Q1 connects the other end of input voltage source Vac, just former border district; The negative electrode of the terminating diode D2 of the same name of the second winding N2, the drain electrode of another termination switching tube of second winding N2 Q2; The anode of diode D2 connects the former border district of input, and the source electrode of switching tube Q2 connects the anode of diode D2.

Transformer is three winding constructions, comprises the first winding N1, the second winding N2 and tertiary winding N3.

The outlet side circuit is by diode D3 and diode D4, outputting inductance Lo and output capacitance Co, and load Rload forms; The anode of the terminating diode D3 of the same name of tertiary winding N3, the anode of another terminating diode D4 of tertiary winding N3 and the negative electrode of output capacitance Co and the end of load Rload; The terminating diode D3 of outputting inductance Lo and the negative electrode of diode D4, the anode of another termination output capacitance Co of inductance L o and the other end of load Rload.

Described control circuit comprises the feedback circuit of output voltage or output current, the phase detecting circuit of AC-input voltage, the magnetic reset testing circuit of transformer T and pfc controller and drive circuit; The pwm pulse of pfc controller and drive circuit output is used for controlling switching tube Q1 and the switching tube Q2 in the main circuit.

For reducing the odd harmonic content of input current, the utility model has been used the control method of a kind of variable ON time (VOT), injects the first-harmonic of outputting inductance electric current at the output signal Comp of traditional error amplifier signal.

The novel power factor correcting device that employing the utility model proposes can reach following beneficial effect at least:

(1) have the advantage of forward converter, compare with traditional Boost pfc circuit, single-level circuit just can satisfy the application scenario of low-voltage, and can satisfy the requirement that level is isolated before and after the circuit.

(2) main power circuit has been removed rectifier bridge, compares the quantity of the semiconductor power device of conducting simultaneously in the time of can reducing circuit working, the efficient of raising circuit with traditional pfc circuit.

(3) by suitable control, transformer can winding N1 and N2 by the former limit of transformer just can be realized mutual degaussing, need not that extra winding resets or other reset circuits.

(4) Harmonics of Input is little, satisfies IEC61000-3-2 C class standard.

Description of drawings

Fig. 1 does not have bridge normal shock power factor correcting device structure chart;

The no bridge forward converter of Fig. 2 (a) operation mode I;

The no bridge forward converter of Fig. 2 (b) operation mode II;

Fig. 3 control circuit module map;

The circuit waveform figure that Fig. 4 the utility model is realized;

Fig. 5 is a specific embodiment of the present utility model.

Embodiment

Also by reference to the accompanying drawings the utility model is done further detailed description below by concrete example.

As shown in Figure 1, the novel no bridge normal shock power factor correcting device that the utility model proposes mainly comprises power main circuit and control circuit, and wherein the power main circuit comprises the input side circuit, transformer T and outlet side circuit.

The input side circuit mainly comprises input voltage source Vac, capacitor C in, switching tube Q1 and switching tube Q2, diode D1 and diode D2.Wherein, diode D1, Transformer Winding N1 and switching tube Q1 have constituted former limit major loop one; Diode D2, Transformer Winding N2 and switching tube Q2 have constituted former limit major loop two.In more detail, the negative electrode of the terminating diode D1 of the same name of winding N1, the drain electrode of another termination switching tube Q1 of winding N1.The anode of diode D1 connects an end of input AC, and the source electrode of switching tube Q1 connects the other end of input voltage source, just former border district.The negative electrode of the terminating diode D2 of the same name of winding N2, the drain electrode of another termination switching tube of winding N2 Q2.The anode of diode D2 connects the former border district of input, and the source electrode of switching tube Q2 connects the anode of diode D2.

Transformer is three winding constructions, comprises the first winding N1, the second winding N2 and tertiary winding N3.In some application scenario, when auxiliary power supply being provided or being used for magnetic core resetting current zero passage detection as the need winding, Transformer Winding can suitably increase.

The outlet side circuit is mainly by diode D3 and diode D4, outputting inductance Lo and output capacitance Co, and load Rload forms.Particularly, the anode of the terminating diode D3 of the same name of winding N3, the anode of another terminating diode of winding N3 D4 and the negative electrode of output capacitance Co and the end of load Rload.The terminating diode D3 of outputting inductance Lo and the negative electrode of diode D4, the anode of another termination output capacitance of inductance L o Co and the other end of load Rload.

Wherein, voltage source V ac is the AC sine input voltage.Cin is the less polarity free capacitor of appearance value, mainly plays the filter harmonic contributions of higher order.Generally, the transformer first winding N1 is identical with the number of turn of the second winding N2.

Wherein, switching tube Q1 can be dissimilar switching devices such as MOSFET, GTR, IGBT etc.

Wherein, switching tube Q2 can be dissimilar switching devices such as MOSFET, GTR, IGBT etc.

Wherein, load Rload can be ohmic load, LED load or late-class circuit.

Control circuit mainly comprises the feedback circuit of output voltage or output current, the phase detecting circuit of AC-input voltage, the magnetic reset testing circuit of transformer T and pfc controller and drive circuit.Wherein the magnetic reset testing circuit of transformer T can omit in some occasion, as increasing active clamping circuir.The pwm pulse of pfc controller and drive circuit output is used for controlling the switching tube in the main power circuit.

Concrete operation principle and the operation mode of no bridge forward converter of the present utility model are described below in conjunction with accompanying drawing 2.

The voltage of converting transformer secondary N3 when AC-input voltage is during less than output voltage, and diode D3 turn-offs, input current I _InOnly comprise very little exciting current and claim to be during this period of time Dead Time.

When AC-input voltage is positive half cycle, and the voltage of conversion to the winding N3 is during greater than output voltage V o, and switching tube Q1 is in the nonstop switch state, and switching tube Q2 keeps conducting state always, and circuit comprises operation mode I and operation mode II:

1. operation mode I:

Shown in Fig. 2 (a), at input side, switching tube Q1 conducting, exchange input and form the conducting loop through the transformer first winding N1, switching tube Q1 and diode D1, voltage on the winding N3 is greater than output voltage, diode D3 conducting, the electric current among the outputting inductance Lo is linear to rise, and electric energy is sent to load end from input.

2. operation mode II:

Shown in Fig. 2 (b), switching tube Q1 turn-offs, and by diode D2, the major loop two that winding N2 and switching tube Q2 form resets transformer T by another.Diode D3 turn-offs simultaneously, the D4 conducting, and the energy that is stored in the energy among the outputting inductance Lo discharges to output loading through diode D4.

When AC-input voltage was in negative half period, switching tube Q1 kept conducting state always, and Q2 is in the nonstop switch state.Operating state with exchange that to be input as positive half cycle similar, no longer describe in detail.

In order to realize above operation principle, the control scheme of employing as shown in Figure 3, the waveform of each module output is as shown in Figure 4 among Fig. 3.

Wherein, pfc controller is the PFC(power factor correction) control circuit (concrete execution mode is showed in Fig. 5); The reset signal of output variable (output voltage V o or electric current I o), AC-input voltage signal and transformer T respectively after testing circuit send into the PFC controller, produce PWM pulse signal V _GThe input ac voltage phase detecting circuit is used for detecting the positive-negative half-cycle of input ac voltage and produces phase signal Vph1, Vph1 is low level when the positive half cycle of input ac voltage (Vac〉0), and Vph1 is high level when input ac voltage negative half period (Vac＜0); The input ac voltage phase detecting circuit comprises resistance R 3, resistance R 4 and comparator U2, wherein the termination of R3 exchanges an end of input, the other end of R3 and the negative input end of receiving comparator U1 after the end of R4 links to each other, another termination of R4 exchanges the other end of input, and receives the positive input terminal of former border district and comparator.Logic and driver element are according to the pwm pulse signal V of the pfc controller output of output signal Vph1 of input ac voltage phase detecting circuit _GControl, make the driving pulse (GD1) of when the positive half cycle of input ac voltage (Vac〉0) Q2 conducting always, Q1 be the PWM pulse signal of pfc controller output, the pwm pulse signal that the driving pulse (GD2) of Q1 conducting always, Q2 is exported for the PFC controller when input ac voltage negative half period (V ac＜0); Logic and driver element comprise inverter U5, with the door U9 and with door U10, or the door U11 and or the door U12, drive unit 1 and drive unit 2.The input of inverter U5, link to each other with input of input of door U10 or door U11 and the output of input ac voltage phase detecting circuit, the input of the output termination of inverter U5 and door U9, or the input of door U12.With door U9 with link to each other with another input of door U10 and the output of PFC controller; With the output termination of door U9 or another input of door U11, with the output termination of door U10 or another input of door U12.Or the output of door U11 be the signal GD1 of control switch pipe Q1 break-make by drive unit 1, or the output of door U12 to pass through drive unit 2 be the signal GD2 of control switch pipe Q2 break-make.

Further, the control of some control mode such as permanent ON time need not the AC-input voltage signal deteching circuit.

Among Fig. 4, Vac is the AC-input voltage waveform, and Vph1 is the AC-input voltage phase signal of AC-input voltage phase detecting circuit output, and Vph2 is the logical inverse signal of Vph1.GD1 is the driving signal of the switching tube Q1 of logic and driver element output, and GD2 is the driving signal of the switching tube Q2 of logic and driver element output.

Fig. 5 is the specific embodiment of a variable ON time of the present utility model (VOT), comprises main circuit of the present utility model and control circuit.Wherein main circuit comprises the input side circuit, transformer T and outlet side circuit.Increased the 4th winding N4 that is used for transformer T reset detection in the main circuit of the present utility model shown in Fig. 5.The former border district of termination of the same name of N4 winding, the different name end is signal ZCD1, takes over the end of zero detection module R1.Outputting inductance Lo goes up increases by an auxiliary winding for detection of the current zero-crossing point of diode D4, also is used for the first-harmonic injection module simultaneously.The former border district of auxiliary winding termination of the same name on the Lo, the different name end is signal ZCD2, takes over the end of zero detection module R1 and the end of first-harmonic injection module R5.

Transformer is four winding constructions, comprises the first winding N1, the second winding N2, tertiary winding N3 and the 4th winding N4.In some application scenario, when providing auxiliary power supply or other purposes as the need winding, Transformer Winding can suitably increase.

The outlet side circuit is mainly by diode D3 and diode D4, outputting inductance Lo and output capacitance Co, and load Rload forms.Particularly, the anode of the terminating diode D3 of the same name of winding N3, the end of the anode of another terminating diode D4 and the negative electrode of output capacitance Co and load Rload.The terminating diode D3 of outputting inductance Lo and the negative electrode of diode D4, the anode of another termination output capacitance Co of inductance L o and the other end of load Rload.

Control circuit comprises phase-angle detection comparator U2, input voltage sample circuit K1, and first-harmonic injects network 101, ON time control module 102, logic and drive circuit 103 and zero cross detection circuit 104.

Further, first-harmonic injection network 101 comprises resistance R 5 and R6, diode D5 and a low pass filter LPF.

Logic and drive circuit 103 comprise reverser U5, with a door U9, with door U10 or door U11 or door U12, drive unit 1 and drive unit 2.

Zero cross detection circuit 104 comprises resistance R 1, resistance R 2, comparator U3 and comparator U4, and with door U6.

Wherein, the control circuit annexation is as follows: an end in input voltage sample circuit K1 one termination AC-input voltage source and the anode of diode D1, the negative input end of another termination phase-angle detection comparator U2 of K1.The former border district of positive input termination of phase-angle detection comparator.The output signal Vph1 of phase-angle detection comparator U2 is as the input signal of logic and drive circuit 103.Resistance R _ f b is as the input signal of error amplifier U1 in the output voltage feedback signal access ON time control module 102.The end of another termination capacitor C f of resistance R _ f b and the negative input end of error amplifier U1.The positive input termination reference signal Vref of error amplifier U1, the other end of capacitor C f is connected with the output of error amplifier U1, produces error amplification signal Vcomp and inserts the end of adder U13.

The ZCD1 signal is taken over an end of resistance R 1 in zero detection module 104, and ZCD2 takes over an end of resistance R 2 in zero detection module 104 and the end of first-harmonic injection module R5.The negative input end of another termination comparator U3 of R1, the former border district of positive input termination of comparator U3.The other end of R2 is taken over the negative input end of zero detection comparator U4, the former border district of positive input termination of zero passage detection comparator U4.The output signal of zero passage detection comparator U3 and U4 inserts respectively and door U6.Insert the S end of the rest-set flip-flop U7 in the ON time control module 102 with the output signal of door U6.

Inject control module 101, a termination ZCD2 of resistance R 5, the end of the other end connecting resistance R6 of resistance R 5 and the negative electrode of diode D5 and the input of low pass filter at first-harmonic.The anode of the other end of R6 and diode D5 links to each other and connects former border district.The output of low pass filter inserts the other end of adder U13, output signal Vcomp addition with error amplifier U1, produce the ON time that signal Vcomp2 changes each switch periods in half power frequency period, form variable ON time control (VOT).The output of adder U13 is the negative input end that signal Vcomp2 meets comparator U8, and the output of the positive input termination sawtooth wave generating circuit of comparator U8, the output of comparator U8 connect the R end of rest-set flip-flop; Sawtooth wave generating circuit comprises current source Idc, capacitor C s and switching tube Sc, the termination DC power supply Vcc of current source Idc, the end of another termination capacitor C s of current source Idc and the end of switching tube Sc, the other end of the other end of capacitor C s and switch S c all connects former border district, the reversed-phase output of the control termination RS trigger of switching tube Sc

The output signal Vph1 of the output drive signal of ON time control module 102 and phase-detection comparator U2 inserts logic and drive control module 103 respectively.Wherein, the output signal Vph1 of phase-detection comparator U2 connect the input of reverser U5 or door U11 an end and with the end of door U10.The output drive signal of permanent ON time control module 102 connect with the end of door U9 and with the other end of door U10.The output signal Vph2 of reverser U5 connects and the other end of door U9 and or the end of door U12.Connect with the output signal of door U9 or the other end of door U11, connect with the output signal of door U10 or the other end of door U12.Or the door U11 output signal connect drive unit 1, or the door U12 output signal connect drive unit 2.The output of drive unit 1 connects the gate pole of metal-oxide-semiconductor Q1, and the output of drive unit 2 connects the gate pole of metal-oxide-semiconductor Q2.

The course of work of no bridge power factor correcting device shown in Figure 5 is briefly described as follows: AC-input voltage Vac sends into phase-detection comparator U2 through sample circuit K1, produces phase signal Vph1.Logic and drive circuit 103 are according to control signal Vph1 and drive signal V _GProduce driving signal GD1 and the GD2 of metal-oxide-semiconductor Q1 and Q2.When input voltage Vac is timing, Vph1 is low level, and Vph2 is high level, and at this moment, driving signal GD2 is high level, switching tube Q2 normal open.Drive signal GD1 and signal V _GIdentical, control switch pipe Q1 does not stop break-make.At this moment, input voltage Vac, diode D1, Transformer Winding N1, the winding N3 of switching tube Q1 and transformer T and secondary circuit constitute forward converter.When switching tube turn-offed, exciting current was by winding N2, and switching tube Q2 and diode D2 feed back to input voltage source Vac, finish the magnetic reset of transformer T.When input voltage Vac when negative, Vph1 is high level, Vph2 is low level, at this moment, driving signal GD1 is high level, switching tube Q1 normal open.Drive signal GD2 and signal V _GIdentical, control switch pipe Q2 does not stop break-make.At this moment, input voltage Vac, diode D2, Transformer Winding N2, the winding N2 of switching tube Q2 and transformer T and secondary circuit constitute forward converter, when switching tube turn-offs, exciting current is by winding N1, and switching tube Q1 and diode D1 feed back to input voltage source Vac, finish the magnetic reset of transformer T.

Error amplifier compares the benchmark Vref of output voltage feedback signal and setting in the module 102, and the error of the two is exported a direct current level Vcomp after compensating network and error amplifier U1 amplification.If the Vcomp signal directly inserts the negative input end of comparator U8, so, traditional permanent ON time control (COT) that Here it is.Work as V _GWhen being output as high level, switch S c turn-offs, and constant-current source Idc gives capacitor C s charging, and when the voltage on the capacitor C s rose gradually and surpass the negative input end of comparator U8, U8 exported high level, V _GSignal resets.Switching tube Sc conducting, the electric capacity on the capacitor C s reduce to zero rapidly, and capacitor C s goes up and forms triangular wave.When output voltage feedback signal was lower than benchmark Vref, error amplifier U1 output voltage rose, and made output signal V through ON time control module 102 _GDuty ratio increase.Otherwise when output voltage feedback signal was higher than benchmark Vref, error amplifier U1 output voltage descended, and made output signal V through ON time control module 102 _GDuty ratio reduce, thereby realize voltage stabilizing to output voltage.Owing to less than output voltage, so there is one section corresponding Dead Time in input current, and influence each harmonic content of input current when existing sinusoidal input voltage of a period of time to convert secondary winding N3 to go up, cause to pass through IEEC C class standard.The utility model has been introduced the first-harmonic injection module on the basis of permanent ON time control, before the Vcomp signal inserts comparator U8, and Vcomp and the fundamental signal addition that from ZCD2, extracts, the negative input end of input comparator U8 then.The ON time of the switching tube of change in whole power frequency period forms variable ON time control (VOT), makes to import more sinusoidalization of average current Iac.Thereby input current waveform has clear improvement, and reduces the odd harmonic of input current, meets IEC61000-3-2 C class standard.

The utility model not only can be used for constant voltage circuit, also can be used for constant-current circuit, as led driver etc.

No matter above how detailed explanation is, and those skilled in the art can have many modes to implement the utility model under the prerequisite of its spirit, and described in the specification is some specific embodiment of the present utility model.All equivalent transformation or modifications of doing according to the utility model spirit essence, or the different compound mode of the various embodiments by each module form different specific embodiment etc., all should be encompassed within the protection range of the present utility model.The above-mentioned detailed description of the utility model embodiment be not exhaustive or be used for the utility model be limited in above-mentioned clear and definite in form.Above-mentioned with schematic purpose specific embodiment of the present utility model and example are described in, those skilled in the art will recognize that and can in scope of the present utility model, carry out various equivalent modifications.

The utility model enlightenment provided here is not must be applied in the said system, can also be applied in other system.Can combine to provide more embodiment with element and the effect of above-mentioned various embodiment.Can make amendment to the utility model according to above-mentioned detailed description, at above-mentioned declarative description specific embodiment of the present utility model and having described in the anticipated optimal set pattern, no matter occur how detailed explanation hereinbefore, also can be implemented in numerous ways the utility model.The details of foregoing circuit structure and control mode thereof is carried out in the details at it can carry out considerable variation, yet it still is included in the utility model disclosed herein.

Should be noted that as above-mentioned employed specific term should not redefine this term here with restriction of the present utility model some certain features, feature or the scheme relevant with this term for being illustrated in when explanation some feature of the present utility model or scheme.In a word, should be with the terminological interpretation in the claims of enclosing, used for the utility model not being limited to disclosed specific embodiment in the specification, unless above-mentioned detailed description part defines these terms clearly.Therefore, actual range of the present utility model not only comprises the disclosed embodiments, also is included among claims.

Claims

1. a no bridge normal shock power factor correcting device comprises main circuit and control circuit, and described main circuit comprises the input side circuit, and transformer T and outlet side circuit is characterized in that:

The input side circuit mainly comprises input voltage source Vac, capacitor C in, switching tube Q1 and switching tube Q2, diode D1 and diode D2; Wherein, diode D1, the first winding N1 and switching tube Q1 have constituted former limit major loop one; Diode D2, the second winding N2 and switching tube Q2 have constituted former limit major loop two; Specifically be the negative electrode of the terminating diode D1 of the same name of the first winding N1, the drain electrode of another termination switching tube Q1 of the first winding N1; The anode of diode D1 connects the end of input voltage source Vac, and the source electrode of switching tube Q1 connects the other end of input voltage source Vac, just former border district; The negative electrode of the terminating diode D2 of the same name of the second winding N2, the drain electrode of another termination switching tube of second winding N2 Q2; The anode of diode D2 connects the former border district of input, and the source electrode of switching tube Q2 connects the anode of diode D2;

Transformer is three winding constructions, comprises the first winding N1, the second winding N2 and tertiary winding N3;

The outlet side circuit is by diode D3 and diode D4, outputting inductance Lo and output capacitance Co, and load Rload forms; The anode of the terminating diode D3 of the same name of tertiary winding N3, the anode of another terminating diode D4 of tertiary winding N3 and the negative electrode of output capacitance Co and the end of load Rload; The terminating diode D3 of outputting inductance Lo and the negative electrode of diode D4, the anode of another termination output capacitance Co of inductance L o and the other end of load Rload;