CN100373756C - Single stage PFC and power converter circuit - Google Patents

Abstract

A power converter provides constant load power while achieving a high power factor in a single stage configuration with reduced component count and ratings. The power converter takes a rectified line input to a switching half-bridge that supplies current to a load. A series combination of shunt switch and capacitor is connected across the load to store energy from the input and supply energy to the load. The switches are operated with conduction angles that achieve constant power supplied to the load while drawing a sinusoidal current in phase with the input voltage to achieve high power factor. The circuit provides a simplified configuration over prior power converters that may be used with a resonant load as part of an electronic ballast or an AC-to-DC converter. The power converter configuration and operation also achieves a low total harmonic distortion on the input line power.

Description

Power converter circuit and operation method thereof with single-level power factor correction (PFC)

The cross reference of related application (cross reference)

The provisional application No.60/450 that the application has been based on and has required the U.S. to propose on February 27th, 2003,572 priority, it is called new single-stage PFC and ballast control circuit/general purpose converter, thus its application priority is also here incorporated into its disclosure as a reference.

Technical field

The present invention relates generally to the have power factor correction power converter of (PFC) and ballast control, relates in particular to the single stage power converter or the ballast control that comprise a pfc circuit.

Background technology

The electric ballast that comprises power factor correction (PFC) is well-known with power converter in relevant industry.Typically, the power converter of any kind comprises electric ballast, and connecting a pfc circuit at their input is 1 preferably to adjust input power factor.Worthwhile and be to be that the load that is connected to power circuit shows as fully without any the pure resistive load that connects impedance according to the frequent needs of adjusting of requirement.That is, alternating voltage and alternating current that the circuit input provides are kept homophase, thereby the load that connects shows as pure resistive.When input voltage and the same phase time of electric current, power factor is near 1, therefore provide and on incoming line, shown as pure resistive load, and less than any tangible influence from capacitor or inductance coil, if voltage and current is an out-phase each other, then can produce influence from capacitor or inductance coil.

In order to obtain to be 1 electrical source power factor, the power factor change-over circuit is typically connected to the power circuit input.Pfc circuit also produces the DC bus-bar voltage of rectification usually, and this voltage offers transducer so that use in power-conversion application.It is the electric ballast that is used for fluorescent lamp that a typical power converter circuit is used.Normally, electric ballast comprises that this transducer Be Controlled provides the supply power of standard under fluorescent lamp preheating, igniting and the normal running (operation) conditions simultaneously by the power converter of DC bus-bar voltage power supply.The simple block diagram of this application as shown in Figure 1.The illustrative electric ballast of Fig. 1 comprises the half-bridge resonance output stage that is used for exciter.The pfc circuit that is connected to the power circuit input is considered to boosting type converter usually, and this transducer uses a high-voltage switch, an inductance coil, a diode, a high-voltage direct-current bus capacitor and a PFC control circuit.The electric ballast output stage is realized by the half-bridge driven resonant load that typically two high-voltage switches, a resonant inductance coil, a resonant capacitor, a DC-isolation capacitor and a ballast control circuit are adopted in this load.The simplified electrical circuit diagram of conventional circuit of electronic ballast as shown in Figure 2.

Conventional half-bridge electronic ballast output stage disposes as shown in Figure 2, and it comprises that connects a dc-link capacitance device Cbus who switches half-bridge circuit.High side half-bridge switch M1 and dc-link capacitance device Cbus are connected on the same node jointly as can be seen in circuit diagram 2.In the time of conventional electrical ballast in opening Fig. 2, the input power supply is first to dc-link capacitance device Cbus charging, thereby provides power supply to the half-bridge resonance output stage when electric ballast moves.The pfc circuit that comprises inductance coil Lpfc, switch Mpfc and diode Dpfc moves between the starting period and bus capacitor Cbus is charged.In this conventional circuit types, the common folk prescription of power is to flowing through load, and bus capacitor Cbus provides power to load in the cycle of Power Conversion.Therefore, bus capacitor Cbus must set the rated value that bears the peak power conversion, and switch Mpfc, M1 and M2 also must set and bear the rated value of peak value busbar voltage.

Worthwhile is to reduce the power converter circuit that the rated value that needs realizes having the input pfc circuit, and simplifies this circuit simultaneously.

Summary of the invention

The invention provides a kind of power converter circuit that is used in rectifying circuit input, comprising: a kind of half-bridge switches, its be connected to rectification circuit input in case from the circuit input of the rectification of input voltage homophase receive a sinusoidal current; A kind of branch switch, it is connected to described half-bridge electric current is diverted to the half-bridge switching or switches shunt current from half-bridge; And energy storing device, it is connected to branch switch with storage or discharge and the energy of the electric current shunted by branch switch.

The present invention also provides a kind of method of operate power converter circuit, this circuit comprises that the half-bridge that connects the power converter input switches and the branch switch that is connected half-bridge and energy storage device, comprising: switch the firm power that half-bridge and branch switch obtain to pass to load; Thereby and switch half-bridge and branch switch and from power converter, receives sinusoidal current acquisition High Power Factor with the input voltage homophase.

In addition, the invention provides a kind of single-stage PFC and power converter circuit of supplying with the resonant load multiple power source.By revising the circuit topology of conventional half-bridge power converter circuit, the present invention is implemented in and improves usefulness on the traditional design basis and reduce component number.Thereby circuit structure of the present invention also reduces size and power consumption that the requirement of component ratings has reduced circuit.Single stage power converter and pfc circuit have the ability to use soft handover in all switches, thereby reduce switching losses and further reduce power consumption.

According to the present invention, the boosting type converter of conventional power factor correction is removed, because this function is incorporated into load is provided in the operation of firm power.Circuit obtains one and approaches 1 power factor, and the bidirectional power current control is provided simultaneously.Half-bridge switches the circuit input voltage that is connected to rectification, and it allows to omit conventional input inductance coil, reduces the requirement of the rated value of dc-link capacitance device simultaneously.By control switch suitably in power converter, from the circuit input, receive sinusoidal current and obtain High Power Factor.In the power converter of routine, the capacitor in the boosting type converter is used to keep the load of variation and the normal pressure under the initial conditions, so capacitor is very big.In the present invention, boosting type converter is removed and bus capacitor does not need to keep normal pressure, but the energy storing device of the transfer power of conduct between input and load.Therefore, bus capacitor can reduce 2-4 doubly.

When keeping High Power Factor, can derive the conduction angle of different switches and obtain constant bearing power.In addition, reduce whole input harmonics distortion widely, thus the electromagnetic interference (EMI) of restriction radiation and conduction.

Other feature and advantage of the present invention will become clear in the following description by means of accompanying drawing.

Description of drawings

The present invention describes hereinafter in more detail by means of accompanying drawing, and accompanying drawing is as follows:

The calcspar of the power converter of the prior art that Fig. 1 separates for PFC and output stage.

Fig. 2 is the simplified electrical circuit diagram of the conventional power converter of driving fluorescent lamp.

Fig. 3 is the calcspar according to the power converter of PFC of the present invention and output stage merging.

Fig. 4 is the simplified electrical circuit diagram according to the circuit topology for driving fluorescent lamp of the present invention.

The circuit input voltage of Fig. 5 illustration rectification and the curve chart of electric current.

Fig. 6 illustration the curve chart of input power, bearing power and capacitor power.

Fig. 7 illustration according to the curve chart at the switches conductive angle in the power converter of the present invention.

Fig. 8 illustration the curve chart of input current and voltage and bus capacitor voltage and current.

Fig. 9 illustration according to the simplified electrical circuit diagram of bi-directional power flow of the present invention.

Figure 10 illustration conduction angle switches in circuit according to the present invention curve chart and sequential chart.

Figure 11 represents curve chart and the sequential chart according to the conduction angle switching of power converter of the present invention.

Embodiment

Refer now to Fig. 3, the calcspar with single stage power converter of power factor correction (PFC) is illustrated as square 30.Single stage power converter is illustrated as and drives a load, for example resonance (resonant) load of the electronic lamp ballast of excitation (powers) velocitron 32.

Refer now to Fig. 4, be illustrated as circuit 40 usually according to the circuit diagram of single stage power converter of the present invention.Circuit 40 comprises that the half-bridge that comprises switch M1 and M2 switches, and it is connected to the output stage of single RCL ballast resonant, and this output stage comprises inductance coil L, capacitor C, direct current capacitor CDC and lamp 32.Switch M1 and M2 are with work in complementary fashion.That is, two switches are not opened simultaneously.In addition, when opening and closing M1 and M2 successively, in transfer sequence, introduce a situation of avoiding short circuit idle time.Approximately be 2 microseconds typical idle time.Switch M3 connects the Centroid of dc-link capacitance device Cbus to the half-bridge conversion.Circuit 40 is different from conventional circuit of electronic ballast shown in Figure 2 20, the condenser capacity requirement that it adopts single-inductor L and reduces capacitor Cbus, and non-polarized capacitor can be used in the reliability that reduces cost in the circuit and improve electric ballast.

Resonant network can be replaced by piezoelectricity conversion equivalence, and under the situation of AC-to DC conversion, lamp also can be replaced by the transducer that connects impedance load.Therefore, circuit of the present invention also is applicable to as having the general purpose converter of power factor correction and reducing cost and number of elements.

When connecting as shown in the figure, the bidirectional power flow that circuit of electronic ballast 40 obtains by load.Load is received power from the input of the circuit of rectification, for example,, receive by switching half-bridge switch when the circuit of rectification is input as when high, and at the circuit input voltage of rectification when low, also provide power by bus capacitor Cbus.In this configuration, capacitor Cbus provides the power of the incoming line voltage cycle of part, rather than spreads all over the power in whole input cycle, the situation of custom circuit 20 as shown in Figure 2.Switch M1, M2 and M3 Be Controlled receive sinusoidal current and obtain High Power Factor from the circuit input.Circuit arrangement obtains favourable total harmonic distortion (THD) in input.Half-bridge does not adopt booster circuit and the advantage that obtains importing, and it reduces THD to the acceptable standard otherwise want careful control.In addition, control switch M1, M2 and M3 continue charging to bus capacitor Cbus, and provide firm power to load.In this configuration, the resonance output stage comprises inductance coil L, capacitor C, lamp 32 and dc-link capacitance device Cbus.

Thereby the topology of circuit 40 is configured to each switch of work has a special function.For example, load provides electric current to switch M1 to resonant lamp from the input of the circuit of rectification, and switch M1 is opened and closed and receive sinusoidal current and obtain High Power Factor from the circuit input.Switch M2 is opened and closed and obtains the distribution channel again in the circuit 40 and keep bi-directional current flow in resonant circuit.Switch M3 is in the be high time work of circuit input voltage, and to dc-link capacitance device Cbus charging, and provides load current at the circuit input voltage when low, and keeps the firm power (constant power) that offers load.Thereby operation that can deploy switch M1-M3 realizes soft handover in each switch.In the present example, switch opens/shutoff operation is to be configured according to special curve to avoid each switch direct-cut operation or non-zero voltage to switch.

Because the incoming line voltage and current is controlled as sine and homophase each other, circuit 40 obtains one and approaches 1 High Power Factor.Because this High Power Factor, circuit 40 shows as the resistive load of circuit input voltage, thereby reduces line input impedance and meet the requirement of adjustment standard.Refer now to Fig. 5, the circuit input of rectification can be assumed to the output of full-bridge converters and realize full-wave rectification.Fig. 5 illustration the voltage and current of the full-wave rectification of homophase each other, as typical standard or approach the situation of desirable full-wave rectifier.In the present example, input power is by input voltage and the decision of input current product.Equation (1) has provided the expression formula of input power.

If the purpose of transducer is to provide firm power to load, the power that is provided by bus capacitor Cbus is subtracted each other by input power and bearing power and decides, and equation (2) and (3) expression are arranged.

P _capacilor=P _load-P _input (2)

Refer now to Fig. 6, its illustration the input power, bearing power and the capacitor power that provide by all-wave circuit input voltage.Thereby showing how capacitor power changes with input power one keeps constant load power.

In order to realize the purpose of constant load power designs, the conduction angle of switch M1 and congee is determined.The conduction angle of switch Ml is lived and the conduction angle p of switch M3 is determined by load current cycle, and it is high more a lot of than circuit incoming frequency that this load current cycle frequency is tending towards.Conduction angle cut down be adopt moment the circuit input current and average high-frequency load current between relation decide, and represent by equation (4)-(6).

α=α ₁When β＜0, or, α=α ₂When β 〉=0 (4)

${\mathrm{\α}}_1=\frac{360}{2\mathrm{\π}}\left\{\arccos (\frac{-2\·{\mathrm{\π}\·P}_{\mathrm{in}}}{V_{\mathrm{in}}\·i_{\mathrm{load}}}+1)\right\}---\left(5\right)$

${\mathrm{\α}}_2=\frac{360}{2\mathrm{\π}}\left\{\arccos \right(-2\·\mathrm{\π}\·\left|\frac{P_{\mathrm{in}}}{V_{\mathrm{in}}\·i_{\mathrm{load}}}\right|+\cos (\mathrm{\β}\·(\frac{2\·\mathrm{\π}}{360}\left)\right)\left)\right\}---\left(6\right)$

Conduction angle β be adopt relation decision between capacitor power and the average high-frequency load current and by 7 expressions of following equation.

$\mathrm{\β}=\frac{360}{2\mathrm{\π}}\left\{\arccos (-2\·\mathrm{\π}\·|\frac{P_{\mathrm{Cbus}}}{V_{\mathrm{Cbus}}\·i_{\mathrm{load}}}|+1)\right\}\·\mathrm{sign}\left(\frac{P_{\mathrm{Cbus}}}{V_{\mathrm{Cbus}}\·i_{\mathrm{load}}}\right)---\left(7\right)$

Refer now to Fig. 7, show the representative graph of conduction angle α and β.Chart illustration among Fig. 7 how dynamic change of conduction angle α and β in cycle of all-wave circuit input voltage of typical circuit input voltage, bearing power, condenser voltage and capacitor value.

Refer now to Fig. 8, input voltage and map of current are attached on the electric current and voltage pattern of bus capacitor Cbus.Illustrative voltage and current is to be defined as typical input voltage and bearing power.

Based on the value of α in the low frequency cycle of each incoming line voltage and β, conduction angle α and β are used in special period and open and close switch M1, M2 and M3 during each high-frequency load current cycle.The conduction angle of each switch carries out summary description below.

When β 〉=0, conduction angle excursion≤α of β≤switch M1 ₂, when β＜0, conduction angle excursion≤α of 0＜switch M1 ₁

When β 〉=0, conduction angle excursion≤β of 180≤switch M2, when β＜0, α ₁Conduction angle excursion≤180 of＜switch M2;

When β 〉=0, α ₂Conduction angle excursion≤180 of≤switch M3, when β＜0, the conduction angle excursion of 180＜switch M3≤360 degree;

Conduction angle and switching manipulation are with reference to following Fig. 9-11 more detailed description.

Refer now to Fig. 9, loop current figure illustration at different switchings and the current path in conducting period.With reference to Figure 10 and 11, the generation in each current path or loop and lasting cycle are described explanation with reference to current loading and switching cycle.For example, Figure 10 represents the corresponding cycle that opens and closes M1, M2 and M3 in o'clock typical resonant load electric current length of β 〉=0.Switch M1 is that β is to α at the angle ₂In time, open.Current i shown in Fig. 9 _AFrom V _InFlow out by switch M1, by resonant load, get back to zero potential (ground wire) then, get back to V _InThen switch M1 be closed and switch M3 in angle from α ₂When 180 spend, be opened.Current i _cFlow out from capacitor Cbus, by M3, by resonant load and get back to zero potential and get back to capacitor Cbus.Switch M3 is closed and M2 is opened when spending from 180 to 360.Current i _DFlow out from resonant load, by switch M2 and get back to zero potential and get back to resonant load.Switch M2 keeps from 0 to β and current i _BThe zero potential of returning from resonant load flows out, by switch M2 and get back to resonant load.Cycle is opened once more along with M1 and self repeats.

Figure 11 illustration typical resonant load electric current corresponding M1, M2 and switch periods of M3 during β＜0.Switch M1 in angle from 0 to α ₁In time, open.Current i _AFrom V _InOutflow by switch M1, get back to zero potential by resonant load and get back to voltage V _InSwitch M1 then be closed switch M2 in angle from α ₁When 180 spend, be opened.Current i _BThe zero potential of returning from resonant load flows out, and gets back to resonant load by the main diode of switch M2.Switch M2 then closes and switch M3 opens when angle from 180 to 360 is spent.Current i _EFlow out from resonant load, by switch M3, get back to zero potential by capacitor Cbus and at resonant load.Cycle opened once more along with switch M1 and self the circulation.

When conduction angle α and β change during the low frequency cycle of circuit input voltage, for example, as shown in Figure 7, thus the conduction angle Be Controlled average line input current of switch be sinusoidal and also with the input voltage homophase.Control circuit obtains to have low total harmonic distortion High Power Factor, keeps a constant bearing power simultaneously.Under stable operating condition, high-frequency current flows out from resonant load with uniform amplitude, it is by following realization, at incoming line voltage when being high, reception is downloaded electric current and bus capacitor Cbus is charged from line, and at the circuit input voltage when low, from capacitor, receive load current or recirculation load current in case of necessity.

Provide many advantages according to single-stage ballast of the present invention control and pfc circuit, comprise the requirement of inductance coil of use and lower dc-link capacitance device capacity level.Circuit more obtains the high-frequency factor in the high efficiency mechanism at one, and this mechanism has the cost of electric ballast/power converter of number of elements, size and the minimizing of input current total harmonic distortion and minimizing.

Although the present invention is described wherein special embodiment, many other variation and modification and other uses will become clear for this area professional.Therefore first-selectedly, the invention is not restricted to wherein detailed disclosure, but only only limit to the claim of adding.

Claims (14)

1. power converter circuit comprises:

A kind of half-bridge switches, its be connected to rectification circuit input in case from the circuit input of the rectification of input voltage homophase receive a sinusoidal current;

A kind of branch switch, it is connected to described half-bridge electric current is diverted to the half-bridge switching or switches shunt current from half-bridge; And

Energy storing device, it is connected to branch switch to store or to discharge the energy of the electric current of being shunted by branch switch.

2. according to the power converter of claim 1, wherein energy storing device is a capacitor.

3. according to the power converter of claim 1, further comprise being connected to the resonance output stage that half-bridge switches.

4. according to the power converter of claim 3, wherein the resonance output stage further comprises a lamp.

5. according to the power converter of claim 1, comprise that further is connected to the piezoelectric transducer that half-bridge switches.

6. according to the power converter of claim 5, further comprise the impedance load of a connection piezoelectric transducer, thereby form an AC-to DC transducer.

7. according to the power converter of claim 1, wherein half-bridge and branch switch work realize constant bearing power.

8. according to the power converter of claim 7, wherein half-bridge and branch switch work realize constant bearing power according to following equation:

When β 〉=0, conduction angle excursion≤α of β≤switch M1 ₂, when β＜0, conduction angle excursion≤α of 0＜switch M1 ₁

When β 〉=0, conduction angle excursion≤β of 180≤switch M2, when β＜0, α ₁Conduction angle excursion≤180 of＜switch M2;

When β 〉=0, α ₂Conduction angle excursion≤180 of≤switch M3, when β＜0, the conduction angle excursion of 180＜switch M3≤360 degree;

Wherein

α=α ₁When β＜0, or, α=α ₂When β 〉=0 (4)

${\mathrm{\α}}_1=\frac{360}{2\mathrm{\π}}\left\{\arccos (\frac{-2\·\mathrm{\π}\·P_{\mathrm{in}}}{V_{\mathrm{in}}\·i_{\mathrm{load}}}+1)\right\}---\left(5\right)$

${\mathrm{\α}}_2=\frac{360}{2\mathrm{\π}}\left\{\arccos (-2\·\mathrm{\π}\·|\frac{P_{\mathrm{in}}}{V_{\mathrm{in}}\·i_{\mathrm{load}}}|+\cos (\mathrm{\β}\·\left(\frac{2\·\mathrm{\π}}{360}\right)))\right\}---\left(6\right)$

$\mathrm{\β}=\frac{360}{2\mathrm{\π}}\left\{\arccos (-2\·\mathrm{\π}\·|\frac{P_{\mathrm{Cbus}}}{V_{\mathrm{Cbus}}\·i_{\mathrm{load}}}|+1)\right\}\·\mathrm{sign}\left(\frac{P_{\mathrm{Cbus}}}{V_{\mathrm{Cbus}}\·i_{\mathrm{load}}}\right)---\left(7\right)$

Wherein

M1 and M2 represent high half-bridge switch and low half-bridge switch respectively;

M3 represents branch switch;

α and the conduction angle of β representative during the switch opens of correspondence;

P _InRepresent input power;

V _InRepresent input voltage;

i _LoadRepresent load current;

P _CbusRepresent the power of energy storage device; And

V _CbusRepresent the voltage of energy storage device.

9. according to the power converter of claim 1, wherein switch is a field effect transistor.

10. the method for an operate power converter circuit, this circuit comprise that the half-bridge that connects the power converter input switches and the branch switch that is connected half-bridge and energy storage device, comprising:

Switch the firm power that half-bridge and branch switch obtain to pass to load; And

Half-bridge and branch switch receive from power converter and the sinusoidal current of input voltage homophase obtains High Power Factor thereby switch.

11., further comprise according to following equation and move half-bridge and branch switch according to the method for claim 10:

When β 〉=0, conduction angle excursion≤α of β≤switch M1 ₂, when β＜0, conduction angle excursion≤α of 0＜switch M1 ₁

When β 〉=0, conduction angle excursion≤β of 180≤switch M2, when β＜0, α ₁Conduction angle excursion≤180 of＜switch M2;

When β 〉=0, α ₂Conduction angle excursion≤180 of≤switch M3, when β＜0, the conduction angle excursion of 180＜switch M3≤360 degree;

Wherein

α=α ₁When β＜0, or, α=α ₂When β 〉=0 (4)

${\mathrm{\α}}_1=\frac{360}{2\mathrm{\π}}\left\{\arccos (\frac{-2\·\mathrm{\π}\·P_{\mathrm{in}}}{V_{\mathrm{in}}\·i_{\mathrm{load}}}+1)\right\}---\left(5\right)$

${\mathrm{\α}}_2=\frac{360}{2\mathrm{\π}}\left\{\arccos (-2\·\mathrm{\π}\·|\frac{P_{\mathrm{in}}}{V_{\mathrm{in}}\·i_{\mathrm{load}}}|+\cos (\mathrm{\β}\·\left(\frac{2\·\mathrm{\π}}{360}\right)))\right\}---\left(6\right)$

$\mathrm{\β}=\frac{360}{2\mathrm{\π}}\left\{\arccos (-2\·\mathrm{\π}\·|\frac{P_{\mathrm{Cbus}}}{V_{\mathrm{Cbus}}\·i_{\mathrm{load}}}|+1)\right\}\·\mathrm{sign}\left(\frac{P_{\mathrm{Cbus}}}{V_{\mathrm{Cbus}}\·i_{\mathrm{load}}}\right)---\left(7\right)$

Wherein

M1 and M2 represent high half-bridge switch and low half-bridge switch respectively;

M3 represents branch switch;

α and the conduction angle of β representative during the switch opens of correspondence;

P _InRepresent input power;

V _InRepresent input voltage;

i _LoadRepresent load current;

P _CbusRepresent the power of energy storage device; And

V _CbusRepresent the voltage of energy storage device.

12., further be included in the half-bridge diverter switch electric current to be provided to load and from input, to receive sinusoidal current and obtain High Power Factor according to the method for claim 10.

13., further be included in diverter switch in the half-bridge and obtain a re-circulation path of load current according to the method for claim 10.

14., further comprise and switch branch switch and in energy storing device, input and load, transmit energy according to the method for claim 10.

Images