CN107276386A

CN107276386A - The effective value-acquiring method of alternating voltage and device of PFC power supplys

Info

Publication number: CN107276386A
Application number: CN201710483384.0A
Authority: CN
Inventors: 黄招彬
Original assignee: Guangdong Midea Refrigeration Equipment Co Ltd
Current assignee: GD Midea Air Conditioning Equipment Co Ltd
Priority date: 2017-06-21
Filing date: 2017-06-21
Publication date: 2017-10-20
Anticipated expiration: 2037-06-21
Also published as: CN107276386B; WO2018232818A1

Abstract

The present invention discloses the effective value-acquiring method of alternating voltage and device of a kind of PFC power supplys, wherein, the effective value-acquiring method of alternating voltage of PFC power supplys comprises the following steps：Obtain the current operating parameters of PFC power supplys；During the condition that the circuit of power factor correction for meeting PFC power supplys in the current operating parameters of PFC power supplys is closed, the circuit of power factor correction of control PFC power supplys is closed, and the input ac voltage peak value of PFC power supplys is obtained according to the voltage at electrochemical capacitor two ends；During the condition that the circuit of power factor correction for meeting PFC power supplys in the current operating parameters of PFC power supplys is opened, control circuit of power factor correction is opened, and the input ac voltage instantaneous value of PFC power supplys is obtained according to the mode of operation of circuit of power factor correction；The alternating voltage virtual value of PFC power supplys is calculated according to input ac voltage peak value or input ac voltage instantaneous value.Technical solution of the present invention has the characteristics of accuracy is high.

Description

Method and device for acquiring effective value of alternating voltage of PFC (power factor correction) power supply

Technical Field

The invention relates to the technical field of power electronics, in particular to a method and a device for acquiring an effective value of alternating voltage of a PFC power supply.

Background

In household appliances and the like: the single-phase alternating current power supply of the self-power grid is rectified by an uncontrollable full bridge, then passes through a power factor correction circuit and finally outputs a direct current power supply to supply power for a large-capacity electrolytic capacitor and a load. The power factor correction circuit generally adopts a BOOST architecture. The BOOST type power factor correction circuit can not only enable a power circuit to achieve a high power factor, but also BOOST and output a stable direct current bus voltage so as to provide a stable direct current power supply for a load.

There are various control methods for BOOST type power factor correction, such as voltage/current double closed loop control algorithm, single cycle control algorithm, etc. From the viewpoint of power factor correction, the alternating voltage is not needed to be used as an input quantity by adopting the single-period control algorithm, and the alternating voltage sampling circuit is eliminated, however, the alternating voltage is needed to be used as a protection threshold value or other control input parameters in most electric appliance systems, so that the estimation of the effective value of the alternating voltage is needed to be carried out on the basis of the elimination of the alternating voltage sampling circuit.

The prior art adopts the following method to obtain the effective value of the alternating voltage of the PFC power supply: and when the current is small, calculating an effective value by adopting the estimated voltage peak value, and when the current is large, calculating the effective value by adopting the estimated voltage instantaneous value. In any switching period of a power switching tube in the power factor correction circuit, the voltage instantaneous value is related to the inductance current change quantity, the inductance current rising time and the inductance current falling time.

Because the time of the current drop of the inductor cannot be known when the power factor correction circuit works in the inductor current interrupted mode, the prior art cannot avoid the problem that the estimated alternating voltage effective value is larger due to the estimation error of the alternating voltage of the power factor correction circuit in the current interrupted working state.

Disclosure of Invention

The invention mainly aims to provide a method for acquiring an effective value of alternating voltage of a PFC power supply, aiming at improving the accuracy of an acquisition result of the effective value of the alternating voltage of the PFC power supply.

In order to achieve the above object, the method for obtaining the effective value of the alternating voltage of the PFC power supply according to the present invention comprises the following steps:

s100, obtaining current working parameters of the PFC power supply;

s200, when the current working parameters of the PFC power supply meet the condition that a power factor correction circuit of the PFC power supply is closed, controlling the power factor correction circuit of the PFC power supply to be closed, acquiring the voltage at two ends of an electrolytic capacitor of the PFC power supply, and then acquiring the input alternating current voltage peak value of the PFC power supply according to the voltage at two ends of the electrolytic capacitor;

s300, when the current working parameters of the PFC power supply meet the condition that a power factor correction circuit of the PFC power supply is started, controlling the power factor correction circuit to be started, determining the working mode of the power factor correction circuit, and then acquiring the input alternating current voltage instantaneous value of the PFC power supply according to the working mode of the power factor correction circuit;

and S400, calculating the effective value of the alternating voltage of the PFC power supply according to the input alternating voltage peak value or the input alternating voltage instantaneous value.

Preferably, the obtaining the voltage across the electrolytic capacitor of the PFC power supply, and then obtaining the input ac voltage peak value of the PFC power supply according to the voltage across the electrolytic capacitor specifically includes:

s210, collecting voltages at two ends of the electrolytic capacitor in one voltage period of an input alternating current power supply of the PFC power supply, and storing the voltages as a plurality of voltage sampling samples;

s220, obtaining a voltage sampling sample with the maximum voltage value in the plurality of voltage sampling samples;

and S230, calculating the input alternating current voltage peak value of the PFC power supply according to the voltage value of the voltage sampling sample with the maximum voltage value and a first preset calculation formula.

Preferably, the power factor correction circuit is a BOOST architecture, and the first preset calculation formula is:

Vac_peak＝Vdc_peak+Vfrd+Vbd；

wherein, Vac _ peak is the input alternating voltage peak value of the PFC power supply, Vdc _ peak is the maximum value of the voltage added at two ends of the electrolytic capacitor, Vfrd is the conduction voltage drop of a fast recovery diode in the power factor correction circuit, and Vbd is the conduction voltage drop of a rectifier bridge in the PFC power supply.

Preferably, the power factor correction circuit includes a power switching tube and an inductor, and the determining the operating mode of the power factor correction circuit specifically includes:

s310, detecting the voltage at two ends of the electrolytic capacitor, and acquiring the switching period of the power switching tube and the duty ratio of the conduction time;

s320, calculating the current peak value of the inductor when the power factor correction circuit works in a current critical mode according to the voltage at the two ends of the electrolytic capacitor, the switching period of the power switching tube, the duty ratio of the conduction time of the power switching tube and a second preset calculation formula;

s330, detecting the current peak value of the inductor;

s341, if the current peak value of the inductor is larger than the current peak value of the inductor when the power factor correction circuit works in a current critical mode, determining that the power factor correction circuit works in a current continuous mode;

s342, if the current peak value of the inductor is equal to the current peak value of the inductor when the power factor correction circuit works in a current critical mode, determining that the power factor correction circuit works in the current critical mode;

and S343, if the current peak value of the inductor is smaller than the current peak value of the inductor when the power factor correction circuit works in the current critical mode, determining that the power factor correction circuit works in the current discontinuous mode.

Preferably, the power factor correction circuit further includes a fast recovery diode, and the second preset calculation formula is:

Ipeak＝(Vdc+Vfrd-Vigbt)/L×D(1-D)×Ts；

wherein Ipeak is the current peak value of the inductor, Vdc is the voltage at two ends of the electrolytic capacitor, Vfrd is the conduction voltage drop of the fast recovery diode, Vigbt is the conduction voltage drop of the power switch tube, L is the inductance value of the inductor, D is the duty ratio of the conduction time of the power switch tube, and Ts is the switching period of the power switch tube.

Preferably, the acquiring the input ac voltage instantaneous value of the PFC power supply according to the operating mode of the power factor correction circuit specifically includes:

s351, when the power factor correction circuit works in a current continuous mode or a current critical mode, acquiring the current variation of the inductor in one switching period of the power switching tube, and calculating the input alternating current voltage instantaneous value of the PFC power supply according to the current variation and a third preset calculation formula;

and S352, when the power factor correction circuit works in a current interruption mode, acquiring the starting time of the power switch tube in one switching period, and calculating the input alternating current voltage instantaneous value of the PFC power supply according to the starting time of the power switch tube in one period and a fourth preset calculation formula.

Preferably, the PFC power supply further includes a rectifier bridge, the power factor correction circuit further includes a fast recovery diode, and the third preset calculation formula is:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts；

wherein Vac is an input alternating current voltage instantaneous value of the PFC power supply, Vdc is a voltage at two ends of the electrolytic capacitor, D is a duty ratio of conduction time of the power switch tube, Vigbt is conduction voltage drop of the power switch tube, Vfrd is conduction voltage drop of the fast recovery diode, Vbd is conduction voltage drop of the rectifier bridge, L is an inductance value of the inductor, Delta Iin is a current variation of the inductor in a switching period of the power switch tube, and Ts is a switching period of the power switch tube.

Preferably, the PFC power supply further includes a rectifier bridge, and the fourth preset calculation formula is:

Vac＝L×Ipeak/Ton+Vigbt+Vbd；

wherein Vac is an instantaneous value of input alternating voltage of the PFC power supply, L is an inductance value of the inductor, Ipeak is a current peak value of the inductor, Ton is an on time of the power switch tube in a switching period, Vigbt is a conduction voltage drop of the power switch tube, and Vbd is a conduction voltage drop of the rectifier bridge.

s510, detecting the voltage at two ends of the electrolytic capacitor, and acquiring the switching period of the power switching tube and the duty ratio of the conduction time;

s520, calculating a current midpoint value of the inductor when the power factor correction circuit works in a current critical mode according to the voltage at two ends of the electrolytic capacitor, the switching period of the power switching tube, the duty ratio of the conduction time of the power switching tube and a fifth preset calculation formula;

s530, detecting the current midpoint value of the inductor;

s541, if the current midpoint value of the inductor is larger than the current midpoint value of the inductor when the power factor correction circuit works in the current critical mode, determining that the power factor correction circuit works in the current continuous mode;

s542, if the current midpoint value of the inductor is equal to the current midpoint value of the inductor when the power factor correction circuit works in the current critical mode, determining that the power factor correction circuit works in the current critical mode;

s543, if the current midpoint value of the inductor is smaller than the current midpoint value of the inductor when the power factor correction circuit works in the current critical mode, it is determined that the power factor correction circuit works in the current discontinuous mode.

Preferably, the power factor correction circuit further includes a fast recovery diode, and the fifth preset calculation formula is:

Imid＝(Vdc+Vfrd–Vigbt)/L×D(1-D)×Ts/2；

the current neutral point value of the inductor is Imid, Vdc is the voltage at two ends of the electrolytic capacitor, Vfrd is the conduction voltage drop of the fast recovery diode, Vigbt is the conduction voltage drop of the power switch tube, L is the inductance value of the inductor, D is the duty ratio of the conduction time of the power switch tube, and Ts is the switching period of the power switch tube.

s551, when the power factor correction circuit works in a current continuous mode or a current critical mode, obtaining the current variation of the inductor in one switching period of the power switching tube, and calculating the input alternating current voltage instantaneous value of the PFC power supply according to the current variation and a sixth preset calculation formula;

s552, when the power factor correction circuit works in a current interruption mode, acquiring the starting time of the power switch tube in a switching period, and calculating the input alternating current voltage instantaneous value of the PFC power supply according to the starting time of the power switch tube in the switching period and a seventh preset calculation formula.

Preferably, the PFC power supply further includes a rectifier bridge, the power factor correction circuit further includes a fast recovery diode, and the sixth preset calculation formula is:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts；

Preferably, the PFC power supply further includes a rectifier bridge, and the seventh preset calculation formula is:

Vac＝L×(Imid×2)/Ton+Vigbt+Vbd；

wherein Vac is an input alternating voltage instantaneous value of the PFC power supply, L is an inductance value of the inductor, Imid is a current midpoint value of the inductor, Ton is an opening time of the power switch tube in a switching period, Vigbt is a conduction voltage drop of the power switch tube, and Vbd is a conduction voltage drop of the rectifier bridge.

Preferably, the calculating the effective value of the ac voltage of the PFC power supply according to the input ac voltage peak value or the input ac voltage instantaneous value specifically includes:

calculating the effective value of the alternating voltage of the PFC power supply according to the input alternating voltage peak value and an eighth preset formula; or,

calculating the effective value of the alternating voltage of the PFC power supply according to the input alternating voltage instantaneous value and a ninth preset formula;

the eighth preset formula is: vac _ rms ═ Vac _ peak/sqrt (2);

the ninth preset formula is as follows: vac _ rms ═ sqrt (LPF (Vac × Vac));

where Vac _ rms is an effective value of the ac voltage of the PFC power supply, Vac _ peak is a peak value of the ac voltage of the power supply, sqrt (2) is an open square operation on the number "2", Vac is an instantaneous value of the ac voltage of the power supply, LPF (Vac × Vac) is a low pass filter operation on (Vac × Vac), and sqrt (LPF (Vac × Vac)) is an open square operation on (LPF (Vac × Vac)).

Preferably, the current operating parameters of the PFC power supply include:

at least one of a current power value of a load connected with the PFC power supply, a current input current value of the PFC power supply and a current input current peak value of the PFC power supply.

Preferably, the condition that the current operating parameter of the PFC power supply satisfies the condition that the power factor correction circuit of the PFC power supply is turned off includes:

the current power value of a load connected with the PFC power supply is smaller than a preset power value, or the current input current value of the PFC power supply is smaller than a preset input current value, or the current input current peak value of the PFC power supply is smaller than a preset input current peak value;

the condition that the current working parameters of the PFC power supply meet the starting condition of a power factor correction circuit of the PFC power supply comprises the following steps:

the current power value of a load connected with the PFC power supply is larger than or equal to a preset power value, or the current input current value of the PFC power supply is larger than or equal to a preset input current value, or the current input current peak value of the PFC power supply is larger than or equal to a preset input current peak value.

Correspondingly, the invention also provides an apparatus for obtaining the effective value of the alternating voltage of the PFC power supply, comprising:

the working parameter acquisition module is used for acquiring the current working parameters of the PFC power supply;

the peak voltage acquisition module is used for controlling the power factor correction circuit of the PFC power supply to be closed when the current working parameters of the PFC power supply meet the condition that the power factor correction circuit of the PFC power supply is closed, acquiring the voltage at two ends of an electrolytic capacitor of the PFC power supply, and then acquiring the input alternating current voltage peak value of the PFC power supply according to the voltage at two ends of the electrolytic capacitor;

the instantaneous voltage acquisition module is used for controlling the power factor correction circuit to be started when the current working parameters of the PFC power supply meet the condition that the power factor correction circuit of the PFC power supply is started, determining the working mode of the power factor correction circuit and then acquiring the input alternating current voltage instantaneous value of the PFC power supply according to the working mode of the power factor correction circuit;

and the effective value calculating module is used for calculating the effective value of the alternating voltage of the PFC power supply according to the input alternating voltage peak value or the input alternating voltage instantaneous value.

Preferably, the peak voltage obtaining module includes:

the voltage acquisition unit is used for acquiring the voltages at two ends of the electrolytic capacitor in one voltage period of an input alternating current power supply of the PFC power supply and storing the voltages as a plurality of voltage sampling samples;

the maximum voltage acquisition unit is used for acquiring a voltage sampling sample with the maximum voltage value in a plurality of voltage sampling samples;

and the peak voltage calculating unit is used for calculating the input alternating voltage peak value of the PFC power supply according to the voltage value of the voltage sampling sample with the maximum voltage value and a first preset calculating formula.

Vac_peak＝Vdc_peak+Vfrd+Vbd；

Preferably, the instantaneous voltage acquisition module includes:

the first voltage detection subunit is used for detecting the voltage at two ends of the electrolytic capacitor;

the first state obtaining subunit is used for obtaining the switching period and the duty ratio of the conduction time of the power switching tube;

the current peak value calculating unit is used for calculating the current peak value of the inductor when the power factor correction circuit works in a current critical mode according to the voltage at two ends of the electrolytic capacitor, the switching period of the power switching tube, the duty ratio of the conduction time of the power switching tube and a second preset calculating formula;

the current peak value detection unit is used for detecting the current peak value of the inductor;

the first working mode determining unit is used for determining that the power factor correction circuit works in a current continuous mode when the current peak value of the inductor is larger than the current peak value of the inductor when the power factor correction circuit works in a current critical mode;

when the current peak value of the inductor is equal to the current peak value of the inductor when the power factor correction circuit works in the current critical mode, determining that the power factor correction circuit works in the current critical mode;

and when the current peak value of the inductor is smaller than the current peak value of the inductor when the power factor correction circuit works in the current critical mode, determining that the power factor correction circuit works in the current discontinuous mode.

Ipeak＝(Vdc+Vfrd-Vigbt)/L×D(1-D)×Ts；

Preferably, the instantaneous voltage acquisition module further includes:

the first instantaneous voltage acquisition unit is used for acquiring the current variation of the inductor in one switching period of the power switching tube when the power factor correction circuit works in a current continuous mode or a current critical mode, and acquiring an input alternating voltage instantaneous value of the PFC power supply according to the current variation and a third preset calculation formula;

and the second instantaneous voltage acquisition unit is used for acquiring the starting time of the power switching tube in one switching period when the power factor correction circuit works in a current interruption mode, and acquiring the input alternating current voltage instantaneous value of the PFC power supply according to the starting of the power switching tube in one period and a fourth preset calculation formula.

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts；

Vac＝L×Ipeak/Ton+Vigbt+Vbd；

Preferably, the instantaneous voltage acquisition module includes:

the second voltage detection subunit is used for detecting the voltage at two ends of the electrolytic capacitor;

the second state obtaining subunit is used for obtaining the switching period and the duty ratio of the conduction time of the power switching tube;

the current midpoint value calculating unit is used for calculating the current midpoint value of the inductor when the power factor correction circuit works in a current critical mode according to the voltage at two ends of the electrolytic capacitor, the switching period of the power switching tube, the duty ratio of the conduction time of the power switching tube and a fifth preset calculation formula;

the current midpoint value detection unit is used for detecting the current midpoint value of the inductor;

the second working mode determining unit is used for determining that the power factor correction circuit works in a current continuous mode when the current midpoint value of the inductor is larger than the current midpoint value of the inductor when the power factor correction circuit works in a current critical mode;

the current midpoint value of the inductor is equal to the current midpoint value of the inductor when the power factor correction circuit works in a current critical mode, and the power factor correction circuit is determined to work in the current critical mode;

and when the current midpoint value of the inductor is smaller than the current midpoint value of the inductor when the power factor correction circuit works in the current critical mode, determining that the power factor correction circuit works in the current discontinuous mode.

Imid＝(Vdc+Vfrd–Vigbt)/L×D(1-D)×Ts/2；

Preferably, the instantaneous voltage acquisition module further includes:

the third instantaneous voltage obtaining unit is used for obtaining the current variation of the inductor in one switching period of the power switching tube when the power factor correction circuit works in a current continuous mode or a current critical mode, and obtaining the input alternating voltage instantaneous value of the PFC power supply according to the current variation and a sixth preset calculation formula;

and the fourth instantaneous voltage acquisition unit is used for acquiring the starting time of the power switching tube in one switching period when the power factor correction circuit works in a current interruption mode, and acquiring the input alternating voltage instantaneous value of the PFC power supply according to the starting time of the power switching tube in one period and a seventh preset calculation formula.

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts；

Vac＝L×(Imid×2)/Ton+Vigbt+Vbd；

Preferably, the effective value calculation module is specifically configured to:

calculating the effective value of the alternating voltage of the PFC power supply according to the input alternating voltage peak value and an eighth preset formula; or calculating the effective value of the alternating voltage of the PFC power supply according to the input alternating voltage instantaneous value and a ninth preset formula;

the eighth preset formula is Vac _ rms ═ Vac _ peak/sqrt (2);

the ninth preset formula is as follows: vac _ rms ═ sqrt (LPF (Vac × Vac));

Preferably, the current operating parameters of the PFC power supply include:

The method for acquiring the effective value of the alternating voltage of the PFC power supply comprises the following steps: first, the current operating parameters of the PFC power supply are obtained. Then, if the current working parameters of the PFC power supply meet the condition that a power factor correction circuit of the PFC power supply is closed, the power factor correction circuit of the PFC power supply is controlled to be closed, and the input alternating-current voltage peak value of the PFC power supply is obtained according to the voltages at the two ends of the electrolytic capacitor; and if the current working parameters of the PFC power supply meet the condition of starting a power factor correction circuit of the PFC power supply, controlling the PFC power supply to be started, and acquiring the input alternating current voltage instantaneous value of the PFC power supply according to the working mode of the power factor correction circuit. And finally, calculating the effective value of the alternating voltage of the PFC power supply according to the peak value of the input alternating voltage or the instantaneous value of the input alternating voltage. According to the technical scheme, the input alternating current voltage instantaneous value of the PFC power supply is obtained according to the working mode of the power factor correction circuit. Therefore, the technical scheme can avoid the interference of the current interruption mode on the result of obtaining the effective value of the alternating voltage of the PFC power supply, and has the characteristic of high accuracy compared with the prior art.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic circuit diagram of a PFC power supply according to an embodiment of the present invention;

fig. 2 is a schematic flowchart of an embodiment of a method for obtaining an effective ac voltage value of a PFC power supply according to the present invention;

FIG. 3 is a detailed flowchart of one embodiment of step S200 in FIG. 2;

FIG. 4 is a schematic view of a detailed process of step S300 in FIG. 2;

FIG. 5 is a schematic view of a detailed flow chart of another embodiment of step S300 in FIG. 2;

fig. 6 is a schematic diagram of functional modules of an embodiment of an ac voltage effective value obtaining apparatus of a PFC power supply according to the present invention;

FIG. 7 is a functional block diagram of an embodiment of the peak voltage obtaining module shown in FIG. 6;

FIG. 8 is a functional block diagram of an embodiment of the transient voltage acquisition module of FIG. 6;

FIG. 9 is a functional block diagram of another embodiment of the transient voltage acquisition module of FIG. 6.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the descriptions relating to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The invention provides a method for acquiring an effective value of alternating voltage of a PFC power supply. The topology of the PFC power factor correction circuit has various options, such as BOOST, BUCK, etc.

In order to better understand the technical solution of the present invention, the working principle of the PFC power supply is described herein by taking a BOOST type power factor correction circuit as an example in this embodiment.

As shown in fig. 1, the PFC power supply includes a rectifier bridge BD, an electrolytic capacitor C, and a BOOST-type power factor correction circuit 10, where the BOOST-type power factor correction circuit 10 includes an inductor L, a power switch IGBT, a fast recovery diode FRD, and a controller. The input end of the rectifier bridge BD is used for being connected with an input alternating current power supply AC, the positive end of the rectifier bridge BD is connected with the first end of the inductor L, the second end of the inductor L, the input end of the power switch tube IGBT and the anode of the fast recovery diode FRD are interconnected, the cathode of the fast recovery diode FRD is connected with the anode of the electrolytic capacitor C, and the connection node of the fast recovery diode FRD is used for being connected with the anode of a load. The negative end of the rectifier bridge BD, the output end of the power switch tube IGBT and the negative electrode of the electrolytic capacitor C are interconnected, the connection node of the rectifier bridge BD and the output end of the power switch tube IGBT is used for being connected with the negative electrode of a load, and the controlled end of the power switch tube IGBT is connected with the control end of the controller.

The controller is configured to output a PWM wave to a controlled terminal of the power switching tube IGBT, so as to turn on the power factor correction circuit 10, thereby implementing a power factor correction function.

Specifically, when the power switch tube IGBT is turned on, a current is output from the positive terminal of the rectifier bridge BD, sequentially passes through the inductor L and the power switch tube IGBT, and returns to the negative terminal of the rectifier bridge BD. In the process, the current of the inductor L rises linearly, and the voltage relation of the inductor L meets the following conditions:

Vac＝L×p·Iin+Vigbt+Vbd； (1)

when the power switch tube IGBT is turned off, the current is output from the positive end of the rectifier bridge BD, and returns to the negative end of the rectifier bridge BD through the inductor L, the fast recovery diode FRD and the electrolytic capacitor C (and the load) in sequence. In the process: when the output voltage of the rectifier bridge BD is higher than the voltage of the electrolytic capacitor C, the current of the inductor L continuously rises; when the output voltage of the rectifier bridge BD is lower than the voltage of the electrolytic capacitor C, the current of the inductor L decreases. The voltage relation satisfies:

Vac＝Vdc+L×p·Iin+Vfrd+Vbd； (2)

wherein Vac is an instantaneous value (absolute value) of input alternating voltage of the PFC power supply, Vdc is voltage of an electrolytic capacitor C, Iin is an instantaneous value of current of an inductor L, p is a differential operator, L is an inductance value of the inductor L, Vbd is conduction voltage drop of a rectifier bridge BD, Vigbt is conduction voltage drop of a power switch tube IGBT, and Vfrd is conduction voltage drop of a fast recovery diode FRD.

And setting the period of the PWM wave as Ts, setting the on time of the power switch tube IGBT as Ton, the off time of the power switch tube IGBT as Toff, and recording the duty ratio as D as Ton/Ts, wherein the Ts is Ton + Toff. In each PWM period, the rise time of the inductor L current is referred to as Tup, and the fall time of the inductor L current is referred to as Tfall. The sum of the rise and fall of the inductor L current in each PWM cycle is the final current change Δ Iin, i.e.

(Vac-Vigbt–Vbd)×Tup+(Vac-Vdc-Vfrd–Vbd)×Tfall＝L×ΔIin； (3)

When the power factor correction circuit 10 operates in the current continuous mode or the current critical mode, and Ton ═ Tup and Toff ═ Tfall are satisfied, then:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts； (4)

when the power factor correction circuit 10 operates in the current discontinuous mode, the inductor L current rises from zero and finally falls to zero in the current PWM period, and the final current change Δ Iin is 0, which satisfies Ton Tup and Toff Tfall, then:

Vac＝Vdc×Tfall/(Ton+Tfall)+Vigbt×Ton/(Ton+Tfall)+Vfrd×Tfall/(Ton+Tfall)+Vbd；(5)

since Tfall cannot be directly known when the power factor correction circuit 10 operates in the current interruption mode, the effective value of the ac voltage of the PFC power supply cannot be directly obtained by the above equation (5). Since Toff > Tfall when the power factor correction circuit 10 operates in the current chopping mode, substituting Toff for Tfall into equation (5) above will result in an effective value of the ac voltage that is greater than the actual value. This is the reason why the ac voltage of the PFC power supply obtained by the prior art has a large effective value.

However, when the power factor circuit 10 operates in the current chopping mode, the current peak value Ipeak of the inductor L satisfies:

L×Ipeak＝(Vac-Vigbt–Vbd)×Ton； (6)

therefore, the instantaneous value of the input ac voltage of the PFC power supply can be calculated according to the above equation (6). Namely:

Vac＝L×Ipeak/Ton+Vigbt+Vbd； (7)

in addition, when the power factor correction circuit 10 operates in the current critical mode, the current peak value Ipeak of the inductor L satisfies:

Ipeak＝(Vdc+Vfrd–Vigbt)/L×D(1-D)×Ts； (8)

in a PWM period, the current peak value Ipeak of the inductor L is the current of the power switch tube IGBT at the moment of switching from on to off; and the current midpoint value Imid of the inductor L is the current of the power switch tube IGBT at the turn-on midpoint moment.

When the power factor correction circuit 10 operates in the current interruption mode or the current critical mode, the current peak value of the inductor L and the current midpoint value of the inductor L satisfy:

Ipeak＝Imid×2； (9)

when the power factor correction circuit 10 operates in the current continuous mode, the current peak value of the inductor L and the current midpoint value of the inductor L satisfy:

Ipeak<(Imid×2)； (10)

based on the above description, referring to fig. 2, in an embodiment, the method for obtaining the effective value of the ac voltage of the PFC power supply includes the following steps:

s100, obtaining current working parameters of the PFC power supply;

here, the current operating parameter of the PFC power supply may be a power value of a load connected to the PFC power supply; the input current value of the PFC power supply or the input current peak value of the PFC power supply can also be obtained; the input current peak value of the PFC power supply may be equal to or greater than a peak value of the input current of the PFC power supply.

When the PFC power supply outputs the power supply to supply power to the load, if the power factor correction circuit 10 is started, the PFC power supply outputs the power supply with corrected power to the load; if the PFC circuit 10 is turned off, the PFC power source outputs power without power correction to the load.

The load may be an actual electrical device, such as a motor, or an analog device for testing, such as a resistor.

In this embodiment, how to obtain the current operating parameter of the PFC power supply is described by taking the operating parameter as the input current value of the PFC power supply as an example.

Specifically, a detection resistor (not shown) may be connected in series to the current trunk of the PFC power supply, and one end of the detection resistor is grounded, and the other end of the detection resistor is connected to the negative terminal of the rectifier bridge BD or the negative terminal of the load. In this way, the input current of the PFC power supply can be obtained by detecting the voltage falling on the other end of the detection resistor by a voltage detection device (not shown) under the condition of neglecting the influence of temperature, current, etc. on the resistance value of the detection resistor. When the other end of the detection resistor is connected with the negative end of the rectifier bridge BD, the detected voltage is negative voltage; when the other end of the detection resistor is connected to the negative electrode of the load, the detected voltage is a positive voltage. Preferably, the other end of the detection circuit is connected to the negative pole of the load. To widen the selection range of the voltage detection device.

It should be noted that, by adopting the above manner, the peak value of the input current of the PFC power supply may also be obtained.

S200, when the current working parameters of the PFC power supply meet the condition that the power factor correction circuit 10 of the PFC power supply is closed, controlling the power factor correction circuit 10 of the PFC power supply to be closed, acquiring the voltages at two ends of an electrolytic capacitor C of the PFC power supply, and then acquiring the input alternating-current voltage peak value of the PFC power supply according to the voltages at two ends of the electrolytic capacitor C;

here, the condition that the current operating parameter of the PFC power supply satisfies the condition that the power factor correction circuit 10 of the PFC power supply is turned off may be selected as follows: the current working parameter of the PFC power supply is smaller than the preset working parameter. For example, the current power value of the load connected to the PFC power supply is smaller than a preset power value, the current input current value of the PFC power supply is smaller than a preset input current value, the current input current peak value of the PFC power supply is smaller than a preset input current peak value, and so on, which are not listed here.

It should be noted that, in the PFC power supply, the power factor correction circuit 10 is provided to reduce the transmission loss of the power supply. When the current operating parameters of the PFC power supply (including the power value of the load connected to the PFC power supply, the input current value of the PFC power supply, the input current peak value of the PFC power supply, and the like) are small, the transmission loss base number of the power supply is small, the effect of the power factor correction circuit 10 is relatively weak, and even the power consumption of the power factor correction circuit 10 itself is larger than the power transmission loss reduced by the power factor correction circuit 10. Therefore, the technical scheme can select whether the power factor correction circuit 10 needs to be started or not according to the actual working state of the PFC power supply, so that the effective value of the alternating voltage of the PFC power supply can be conveniently obtained, and the reactive power loss of the PFC power supply can be kept in a relatively low state.

In addition, in the embodiment, how to determine that the current operating parameter of the PFC power supply is smaller than the preset operating parameter may be implemented in various ways.

For example, obtaining current working parameters of the PFC power supply; calculating the difference value between the current working parameter of the PFC power supply and a preset working parameter; and if the difference is smaller than zero, determining that the current working parameter of the PFC power supply is smaller than the preset working parameter. Therefore, whether the current working parameter of the PFC power supply is smaller than the preset working parameter or not can be quickly determined.

Or, acquiring the current working parameters of the PFC power supply; calculating the difference value between the current working parameter of the PFC power supply and a preset working parameter; circularly executing the actions to obtain the difference value between the current working parameters of the PFC power supply and the preset working parameters; calculating an average value of the plurality of difference values; and if the average value of the difference values is smaller than zero, determining that the current working parameter of the PFC power supply is smaller than the preset working parameter. Therefore, the influence of detection errors on the data acquisition result can be avoided, and the reliability is further improved.

It should be noted that, if the operating parameter is the input current of the PFC power supply, the preset input current value of the PFC power supply may be selected from 1 ampere to 2 amperes.

Optionally, referring to fig. 3, the following method is adopted to obtain the voltages at two ends of the electrolytic capacitor C of the PFC power supply, and obtain the peak value of the input ac voltage of the PFC power supply according to the voltages at two ends of the electrolytic capacitor C:

s210, collecting voltages at two ends of an electrolytic capacitor C in one voltage period of an input Alternating Current (AC) power supply of a Power Factor Correction (PFC) power supply, and storing the voltages as a plurality of voltage sampling samples;

It can be understood that, in one voltage cycle of the input AC power AC of the PFC power supply, the more the stored voltage sample is, the closer the voltage value of the voltage sample with the largest voltage value is to the peak value of the input AC voltage of the PFC power supply. Preferably, in the present embodiment, the number of stored voltage sample samples is between 50 and 100.

In addition, according to the operating principle of the PFC power supply, when the power factor correction circuit 10 is turned off, the power switching tube IGBT is turned off, and the rectifier bridge BD, the inductor L, the fast recovery diode FRD, and the electrolytic capacitor C form a current loop, so that there are:

Vac_peak＝Vdc_peak+Vfrd+Vbd； (11)

where Vac _ peak is the peak value of the input ac voltage of the PFC power supply, and Vdc _ peak is the maximum value of the voltage across the electrolytic capacitor C. The above equation (11) is the first predetermined calculation equation.

When the power factor correction circuit 10 is in the off state, the above equation (11) is always satisfied, and when the stored voltage sample is sufficiently large, the sum of the voltage value of the voltage sample with the largest voltage value, the conduction voltage drop of the fast recovery diode FRD, and the conduction voltage drop of the rectifier bridge BD is almost equal to the input ac voltage peak value of the PFC power supply. Therefore, the present embodiment can obtain an accurate input ac voltage peak value.

S300, when the current working parameters of the PFC power supply meet the starting condition of the power factor correction circuit 10 of the PFC power supply, controlling the power factor correction circuit 10 to be started, determining the working mode of the power factor correction circuit 10, and then acquiring the input alternating current voltage instantaneous value of the PFC power supply according to the working mode of the power factor correction circuit 10;

here, the condition that the current operating parameter of the PFC power supply satisfies the condition that the power factor correction circuit 10 of the PFC power supply is turned on may be selected as: the current working parameter of the PFC power supply is larger than or equal to the preset working parameter. For example, the current power value of the load connected to the PFC power supply is greater than or equal to a preset power value, the current input current value of the PFC power supply is greater than or equal to a preset input current value, the current input current peak value of the PFC power supply is greater than or equal to a preset input current peak value, and so on, which are not listed here.

It should be noted that, in the PFC power supply, the power factor correction circuit 10 is provided to reduce the transmission loss of the power supply. When the current operating parameters of the PFC power supply (including the power value of the load connected to the PFC power supply, the input current value of the PFC power supply, the input current peak value of the PFC power supply, and the like) are large, the transmission loss base number of the power supply is large, and the effect of the power factor correction circuit 10 is relatively obvious. Therefore, the technical scheme can select whether the power factor correction circuit 10 needs to be started or not according to the actual working state of the PFC power supply, so that the effective value of the alternating voltage of the PFC power supply can be conveniently obtained, and the reactive power loss of the PFC power supply can be kept in a relatively low state.

In addition, in the embodiment, various means may be adopted for determining how to determine that the current operating parameter of the PFC power supply is greater than or equal to the preset operating parameter.

For example, obtaining current working parameters of the PFC power supply; calculating the difference value between the current working parameter of the PFC power supply and a preset working parameter; and if the difference is greater than or equal to zero, determining that the current working parameter of the PFC power supply is greater than or equal to a preset working parameter. In this way, whether the current operating parameter of the PFC power supply is greater than or equal to the preset operating parameter can be quickly determined.

Or, acquiring the current working parameters of the PFC power supply; calculating the difference value between the current working parameter of the PFC power supply and a preset working parameter; circularly executing the actions to obtain the difference value between the current working parameters of the PFC power supply and the preset working parameters; calculating an average value of the plurality of difference values; and if the average value of the difference values is larger than or equal to zero, determining that the current working parameter of the PFC power supply is larger than or equal to a preset working parameter. Therefore, the influence of detection errors on the data acquisition result can be avoided, and the reliability is further improved.

Optionally, referring to fig. 4, the following method is adopted to determine the operating mode of the power factor correction circuit, and then the input ac voltage instantaneous value of the PFC power supply is obtained according to the operating mode of the power factor correction circuit:

s310, detecting the voltage at two ends of the electrolytic capacitor C, and acquiring the switching period and the duty ratio of the conduction time of the IGBT of the power switching tube;

the duty ratio of the on-time of the power switch tube IGBT refers to the duty ratio of the on-time of the power switch tube IGBT in the current switching period of the power switch tube IGBT.

It should be noted that, in one voltage cycle of the input power AC of the PFC power supply, at different times, the duty ratios of the obtained on-times of the power switching tubes IGBT may be different.

S320, calculating the current peak value of the inductor when the power factor correction circuit 10 works in the current critical mode according to the voltage at the two ends of the electrolytic capacitor C, the switching period of the power switching tube IGBT, the duty ratio of the conduction time of the power switching tube IGBT and a second preset calculation formula;

according to the working principle of the PFC power supply, the second predetermined calculation formula may be selected as:

Ipeak＝(Vdc+Vfrd-Vigbt)/L×D(1-D)×Ts； (12)

s330, detecting the current peak value of the inductor L;

the current peak value of the inductor L means a current value flowing through the inductor L when the power switching tube IGBT is switched from on to off in a current switching period of the power switching tube IGBT.

Preferably, a sampling resistor (not shown) may be added to assist in detecting the current of the load. For example, the first end of the sampling resistor is connected with the negative end of the rectifier bridge BD, and the second end of the sampling resistor, the output end of the power switch tube IGBT, and the negative electrode of the electrolytic capacitor C are interconnected. Therefore, under the condition of knowing the resistance value of the sampling resistor, the voltage falling on the second end of the sampling resistor is detected, and the main circuit current of the PFC power supply, namely the current flowing through the inductor L, can be obtained.

S341, if the current peak value of the inductor L is greater than the current peak value of the inductor L when the power factor correction circuit 10 operates in the current critical mode, determining that the power factor correction circuit 10 operates in the current continuous mode;

it can be understood that, in one switching cycle of the power switch IGBT: if the power factor correction circuit 10 operates in the current continuous mode, the current flowing through the inductor L is greater than zero at the time when the power switch tube IGBT is turned on, and the current flowing through the inductor L linearly increases when the power switch tube IGBT is in the on state. If the power factor correction circuit 10 operates in the current critical mode, the current flowing through the inductor L is equal to zero at the time when the power switch tube IGBT is turned on, and the current flowing through the inductor L linearly increases when the power switch tube IGBT is in the on state.

Therefore, the peak current value of the inductor L when the power factor correction circuit 10 operates in the current continuous mode is larger than the peak current value of the inductor L when the power factor correction circuit 10 operates in the current critical mode. The technical scheme has the characteristic of high accuracy.

S342, if the current peak value of the current of the inductor L is equal to the current peak value of the inductor L when the power factor correction circuit 10 operates in the current critical mode, determining that the power factor correction circuit 10 operates in the current critical mode;

s343, if the current peak value of the inductor L is smaller than the current peak value of the inductor L when the power factor correction circuit 10 operates in the current critical mode, it is determined that the power factor correction circuit 10 operates in the current discontinuous mode.

It can be understood that, in one switching cycle of the power switch IGBT: if the power factor correction circuit 10 operates in the discontinuous current mode, the current flowing through the inductor L is equal to zero before the power switching tube IGBT finishes the turn-off state, and the current flowing through the inductor L is linearly reduced when the power switching tube IGBT is in the turn-off state. If the power factor correction circuit 10 operates in the current critical mode, the current flowing through the inductor L is greater than zero before the power switching tube IGBT finishes the turn-off state, and the current flowing through the inductor L is linearly reduced when the power switching tube IGBT is in the turn-off state.

Therefore, the peak current value of the inductor L when the power factor correction circuit 10 operates in the current critical mode is larger than the peak current value of the inductor L when the power factor correction circuit 10 operates in the current discontinuous mode. The technical scheme has the characteristic of high accuracy.

S351, when the power factor correction circuit 10 works in a current continuous mode or a current critical mode, acquiring the current variation of the inductor L in one switching period of the power switching tube IGBT, and calculating the input alternating current voltage instantaneous value of the PFC power supply according to the current variation and a third preset calculation formula;

here, the third predetermined formula may be selected as:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts； (13)

and S352, when the power factor correction circuit 10 works in the current interruption mode, acquiring the turn-on time of the power switch tube IGBT in one switching period, and calculating the input alternating current voltage instantaneous value of the PFC power supply according to the turn-on time of the power switch tube IGBT in one period and a fourth preset calculation formula.

Here, the fourth preset formula may be selected as:

Vac＝L×Ipeak/Ton+Vigbt+Vbd； (14)

according to the technical scheme, the working mode of the power factor correction circuit 10 is determined according to the current peak value of the inductor L, and different calculation formulas are selected according to different working modes of the power factor correction circuit 10 to calculate the input alternating current voltage instantaneous value of the PFC power supply. The present embodiment determines the operation mode of the PFC circuit 10 reliably, and calculates the instantaneous value of the input ac voltage of the PFC power supply accurately.

Optionally, referring to fig. 5, the following method is adopted to determine the operating mode of the power factor correction circuit, and then the input ac voltage instantaneous value of the PFC power supply is obtained according to the operating mode of the power factor correction circuit:

s510, detecting the voltage at two ends of the electrolytic capacitor C, and acquiring the switching period and the duty ratio of the conduction time of the IGBT of the power switching tube;

S520, calculating a current midpoint value of the inductor L when the power factor correction circuit 10 works in a current critical mode according to the voltage of the two ends C of the electrolytic capacitor, the switching period of the power switching tube IGBT, the duty ratio of the conduction time of the power switching tube IGBT and a fifth preset calculation formula;

according to the working principle of the PFC power supply, the fifth predetermined calculation formula may be selected as:

Imid＝(Vdc+Vfrd–Vigbt)/L×D(1-D)×Ts/2； (15)

where Imid is the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current critical mode.

S530, detecting the current midpoint value of the inductor L;

the current midpoint value of the inductor L refers to a current value flowing through the inductor L at a moment when the power switching tube IGBT turns on a midpoint in a current switching period of the power switching tube IGBT.

S541, if the current midpoint value of the inductor L is greater than the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current critical mode, determining that the power factor correction circuit 10 operates in the current continuous mode;

Therefore, the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current continuous mode is greater than the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current critical mode. The technical scheme has the characteristic of high accuracy.

Therefore, the peak current value of the inductor L when the power factor correction circuit 10 operates in the current critical mode is larger than the peak current value of the inductor L when the power factor correction circuit 10 operates in the current discontinuous mode.

When the power factor correction circuit 10 operates in the current critical mode or the current discontinuous mode, the peak current value of the inductor L is twice the midpoint current value of the inductor L. Therefore, the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current critical mode is greater than the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current discontinuous mode. The technical scheme has the characteristic of high accuracy.

S551, when the power factor correction circuit 10 works in a current continuous mode or a current critical mode, obtaining a current variation of the inductor L in a switching period of the power switching tube IGBT, and calculating an input alternating current voltage instantaneous value of the PFC power supply according to the current variation and a sixth preset calculation formula;

here, the sixth preset formula may be selected as:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts； (16)

s552, when the power factor correction circuit 10 works in the current interruption mode, obtaining the turn-on time of the power switch tube IGBT in one switching period, and calculating the input ac voltage instantaneous value of the PFC power supply according to the turn-on time of the power switch tube IGBT in one switching period and a seventh preset calculation formula.

Here, the seventh preset formula may be selected as:

Vac＝L×(Imid×2)/Ton+Vigbt+Vbd； (17)

according to the technical scheme, the working mode of the power factor correction circuit 10 is determined according to the current midpoint value of the inductor L, and different calculation formulas are selected according to different working modes of the power factor correction circuit 10 to calculate the input alternating current voltage instantaneous value of the PFC power supply. The present embodiment determines the operation mode of the PFC circuit 10 reliably, and calculates the instantaneous value of the input ac voltage of the PFC power supply accurately.

And S400, calculating the effective value of the alternating voltage of the PFC power supply according to the peak value of the input alternating voltage or the instantaneous value of the input alternating voltage.

Specifically, the effective value of the alternating voltage of the PFC power supply is calculated according to the input alternating voltage peak value and an eighth preset formula; or calculating the effective value of the alternating voltage of the PFC power supply according to the input alternating voltage instantaneous value and a ninth preset formula.

Here, the eighth preset formula is: vac _ rms ═ Vac _ peak/sqrt (2); (18)

the ninth preset formula is: vac _ rms ═ sqrt (LPF (Vac × Vac)); (19)

The method for acquiring the effective value of the alternating voltage of the PFC power supply comprises the following steps: first, the current operating parameters of the PFC power supply are obtained. Then, if the current working parameters of the PFC power supply meet the condition that the power factor correction circuit 10 of the PFC power supply is closed, controlling the power factor correction circuit 10 of the PFC power supply to be closed, and acquiring the input alternating-current voltage peak value of the PFC power supply according to the voltage at the two ends of the electrolytic capacitor C; and if the current working parameters of the PFC power supply meet the condition that the power factor correction circuit 10 of the PFC power supply is started, controlling the PFC power supply to be started, and acquiring the input alternating-current voltage instantaneous value of the PFC power supply according to the working mode of the power factor correction circuit 10. And finally, calculating the effective value of the alternating voltage of the PFC power supply according to the peak value of the input alternating voltage or the instantaneous value of the input alternating voltage. According to the technical scheme, the input alternating current voltage instantaneous value of the PFC power supply is obtained according to the working mode of the power factor correction circuit. Therefore, the technical scheme can avoid the interference of the current interruption mode on the result of obtaining the effective value of the alternating voltage of the PFC power supply, and has the characteristic of high accuracy compared with the prior art.

Correspondingly, the invention also provides a device for acquiring the effective value of the input alternating voltage of the PFC power supply. Referring to fig. 6, in one embodiment, the apparatus includes:

a working parameter obtaining module 100, configured to obtain current working parameters of the PFC power supply;

The peak voltage obtaining module 200 is configured to control the power factor correction circuit 10 of the PFC power supply to be turned off when the current working parameter of the PFC power supply meets a condition that the power factor correction circuit 10 of the PFC power supply is turned off, obtain voltages at two ends of an electrolytic capacitor C of the PFC power supply, and then obtain an input ac voltage peak value of the PFC power supply according to the voltages at the two ends of the electrolytic capacitor C;

Optionally, referring to fig. 7, in an embodiment, the peak voltage obtaining module 200 includes:

the voltage acquisition unit 210 is configured to acquire voltages at two ends of the electrolytic capacitor within one voltage period of the input ac power of the PFC power supply, and store the voltages as a plurality of voltage sampling samples;

a maximum voltage obtaining unit 220, configured to obtain a voltage sample with a maximum voltage value among the multiple voltage samples;

the peak voltage calculating unit 230 calculates an input ac voltage peak value of the PFC power according to the voltage value of the voltage sample with the largest voltage value and a first preset calculation formula.

Vac_peak＝Vdc_peak+Vfrd+Vbd； (20)

where Vac _ peak is the peak value of the input ac voltage of the PFC power supply, and Vdc _ peak is the maximum value of the voltage across the electrolytic capacitor C. The above equation (20) is the first predetermined calculation equation.

When the power factor correction circuit 10 is in the off state, the above equation (20) is always satisfied, and when the stored voltage sample is sufficiently large, the sum of the voltage value of the voltage sample with the largest voltage value, the conduction voltage drop of the fast recovery diode FRD, and the conduction voltage drop of the rectifier bridge BD is almost equal to the input ac voltage peak value of the PFC power supply. Therefore, the present embodiment can obtain an accurate input ac voltage peak value.

The instantaneous voltage obtaining module 300 is configured to control the power factor correction circuit 10 to start when the current working parameter of the PFC power meets a start condition of the power factor correction circuit 10 of the PFC power, determine a working mode of the power factor correction circuit 10, and then obtain an input alternating voltage instantaneous value of the PFC power according to the working mode of the power factor correction circuit 10;

Optionally, referring to fig. 8, in another embodiment, the instantaneous voltage obtaining module 300 includes:

a first voltage detecting subunit 311 for detecting the voltage across the electrolytic capacitor;

a first state obtaining subunit 312, configured to obtain a switching period and a duty ratio of a conduction time of the power switching tube;

The current peak value calculating unit 320 is configured to calculate a current peak value of the inductor when the power factor correction circuit operates in the current critical mode according to the voltage across the electrolytic capacitor, the switching period of the power switching tube, the duty ratio of the on-time of the power switching tube, and a second preset calculation formula;

Ipeak＝(Vdc+Vfrd-Vigbt)/L×D(1-D)×Ts； (21)

a current peak value detection unit 330, configured to detect a current peak value of the inductor;

The first operation mode determining unit 340 is configured to determine that the power factor correction circuit operates in the current continuous mode when a current peak value of the inductor is greater than a current peak value of the inductor when the power factor correction circuit operates in the current critical mode;

Therefore, the peak current value of the inductor L when the power factor correction circuit 10 operates in the current continuous mode is larger than the peak current value of the inductor L when the power factor correction circuit 10 operates in the current critical mode.

In one switching cycle of the power switch tube IGBT: if the power factor correction circuit 10 operates in the discontinuous current mode, the current flowing through the inductor L is equal to zero before the power switching tube IGBT finishes the turn-off state, and the current flowing through the inductor L is linearly reduced when the power switching tube IGBT is in the turn-off state. If the power factor correction circuit 10 operates in the current critical mode, the current flowing through the inductor L is greater than zero before the power switching tube IGBT finishes the turn-off state, and the current flowing through the inductor L is linearly reduced when the power switching tube IGBT is in the turn-off state.

The technical scheme has the characteristic of high accuracy.

The first instantaneous voltage acquisition unit 351 is used for acquiring the current variation of the inductor in one switching period of the power switching tube when the power factor correction circuit works in a current continuous mode or a current critical mode, and acquiring the input alternating voltage instantaneous value of the PFC power supply according to the current variation and a third preset calculation formula;

here, the third predetermined formula may be selected as:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts； (22)

the second instantaneous voltage obtaining unit 352 is configured to obtain, when the power factor correction circuit operates in the current interruption mode, a turn-on time of the power switching tube in one switching period, and obtain an input ac voltage instantaneous value of the PFC power supply according to the turn-on time of the power switching tube in one switching period and a fourth preset calculation formula.

Here, the fourth preset formula may be selected as:

Vac＝L×Ipeak/Ton+Vigbt+Vbd； (23)

Optionally, referring to fig. 9, in another embodiment, the instantaneous voltage obtaining module 300 includes:

a second voltage detecting subunit 511, configured to detect a voltage across the electrolytic capacitor;

a second state obtaining subunit 512, configured to obtain a switching period and a duty ratio of a conduction time of the power switching tube;

The current midpoint value calculating unit 520 is configured to calculate a current midpoint value of the inductor when the power factor correction circuit operates in the current critical mode according to the voltage across the electrolytic capacitor, the switching period of the power switching tube, the duty cycle of the on-time of the power switching tube, and a fifth preset calculation formula;

Imid＝(Vdc+Vfrd–Vigbt)/L×D(1-D)×Ts/2； (24)

A current midpoint value detecting unit 530, configured to detect a current midpoint value of the inductor;

A second operation mode determining unit 540, configured to determine that the power factor correction circuit operates in the current continuous mode when the current midpoint value of the inductor is greater than the current midpoint value of the inductor when the power factor correction circuit operates in the current critical mode;

the current midpoint value of the inductor is equal to the current midpoint value of the inductor when the power factor correction circuit works in the current critical mode, and the power factor correction circuit is determined to work in the current critical mode;

Therefore, the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current continuous mode is greater than the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current critical mode.

When the power factor correction circuit 10 operates in the current critical mode or the current discontinuous mode, the peak current value of the inductor L is twice the midpoint current value of the inductor L. Therefore, the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current critical mode is greater than the current midpoint value of the inductor L when the power factor correction circuit 10 operates in the current discontinuous mode.

The technical scheme has the characteristic of high accuracy.

The third instantaneous voltage obtaining unit 551 is configured to obtain a current variation of the inductor in a switching period of the power switching tube when the power factor correction circuit operates in the current continuous mode or the current critical mode, and obtain an input ac voltage instantaneous value of the PFC power supply according to the current variation and a sixth preset calculation formula;

here, the sixth preset formula may be selected as:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts； (25)

the fourth instantaneous voltage obtaining unit 552 is configured to obtain the on-time of the power switching tube in one switching period when the power factor correction circuit operates in the current interruption mode, and obtain the input ac voltage instantaneous value of the PFC power supply according to the on-time of the power switching tube in one switching period and a seventh preset calculation formula.

Here, the seventh preset formula may be selected as:

Vac＝L×(Imid×2)/Ton+Vigbt+Vbd； (26)

And the effective value calculating module 400 is configured to calculate an effective value of the ac voltage of the PFC power supply according to the input ac voltage peak value or the input ac voltage instantaneous value.

Here, the eighth preset formula is: vac _ rms ═ Vac _ peak/sqrt (2); (27)

the ninth preset formula is: vac _ rms ═ sqrt (LPF (Vac × Vac)); (28)

In the ac voltage effective value acquisition device of the PFC power supply: first, the operating parameter acquiring module 100 acquires the current operating parameters of the PFC power supply. Then, the peak voltage obtaining module 200 controls the power factor correction circuit 10 of the PFC power supply to be turned off when the current working parameter of the PFC power supply meets the condition that the power factor correction circuit 10 of the PFC power supply is turned off, and obtains the input ac voltage peak value of the PFC power supply according to the voltage at the two ends of the electrolytic capacitor C; the instantaneous voltage obtaining module 300 controls the PFC power supply to be turned on when the current operating parameter of the PFC power supply meets the condition that the power factor correction circuit 10 of the PFC power supply is turned on, and obtains the input ac voltage instantaneous value of the PFC power supply according to the operating mode of the power factor correction circuit 10. Finally, the effective value calculating module 400 calculates the ac voltage effective value of the PFC power according to the input ac voltage peak value or the input ac voltage instantaneous value. According to the technical scheme, the input alternating current voltage instantaneous value of the PFC power supply is obtained according to the working mode of the power factor correction circuit. Therefore, the technical scheme can avoid the interference of the current interruption mode on the result of obtaining the effective value of the alternating voltage of the PFC power supply, and has the characteristic of high accuracy compared with the prior art.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A method for obtaining an effective value of an alternating voltage of a PFC power supply is characterized by comprising the following steps:

s100, obtaining current working parameters of the PFC power supply;

2. The method according to claim 1, wherein the step of obtaining the voltage across the electrolytic capacitor of the PFC power supply and then obtaining the peak value of the input ac voltage of the PFC power supply according to the voltage across the electrolytic capacitor comprises:

3. The method according to claim 2, wherein the power factor correction circuit is a BOOST architecture, and the first predetermined calculation formula is:

Vac_peak＝Vdc_peak+Vfrd+Vbd；

4. The method according to claim 1, wherein the power factor correction circuit includes a power switching tube and an inductor, and the determining the operation mode of the power factor correction circuit specifically includes:

s330, detecting the current peak value of the inductor;

5. The method according to claim 4, wherein the power factor correction circuit further comprises a fast recovery diode, and the second predetermined calculation formula is:

Ipeak＝(Vdc+Vfrd-Vigbt)/L×D(1-D)×Ts；

6. The method according to claim 4, wherein the obtaining the instantaneous value of the input ac voltage of the PFC power supply according to the operation mode of the power factor correction circuit specifically comprises:

7. The method according to claim 6, wherein the PFC power supply further comprises a rectifier bridge, the power factor correction circuit further comprises a fast recovery diode, and the third predetermined calculation formula is:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts；

8. The method according to claim 6, wherein the PFC power supply further comprises a rectifier bridge, and the fourth predetermined calculation formula is:

Vac＝L×Ipeak/Ton+Vigbt+Vbd；

9. The method according to claim 1, wherein the power factor correction circuit includes a power switching tube and an inductor, and the determining the operation mode of the power factor correction circuit specifically includes:

s530, detecting the current midpoint value of the inductor;

10. The method for obtaining the effective value of the alternating voltage of the PFC power supply of claim 9, wherein the power factor correction circuit further comprises a fast recovery diode, and the fifth predetermined calculation formula is:

Imid＝(Vdc+Vfrd–Vigbt)/L×D(1-D)×Ts/2；

11. The method according to claim 9, wherein the obtaining an input ac voltage instantaneous value of the PFC power according to the operation mode of the power factor correction circuit specifically comprises:

12. The method for obtaining the effective value of the alternating voltage of the PFC power supply of claim 11, wherein the PFC power supply further comprises a rectifier bridge, the power factor correction circuit further comprises a fast recovery diode, and the sixth preset calculation formula is:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts；

13. The method for obtaining the effective value of the alternating voltage of the PFC power supply of claim 11, wherein the PFC power supply further comprises a rectifier bridge, and the seventh preset calculation formula is:

Vac＝L×(Imid×2)/Ton+Vigbt+Vbd；

14. The method according to claim 1, wherein the calculating the ac voltage effective value of the PFC power according to the input ac voltage peak value or the input ac voltage instantaneous value specifically includes:

the eighth preset formula is: vac _ rms ═ Vac _ peak/sqrt (2);

the ninth preset formula is as follows: vac _ rms ═ sqrt (LPF (Vac × Vac));

15. The ac voltage effective value obtaining method of the PFC power supply according to claim 1, wherein the current operating parameters of the PFC power supply include:

16. The method for obtaining the effective value of alternating voltage of a PFC power supply of claim 15,

the condition that the current working parameters of the PFC power supply meet the condition that a power factor correction circuit of the PFC power supply is closed comprises the following steps:

17. An apparatus for obtaining an effective value of an alternating voltage of a PFC power supply, comprising:

the instantaneous voltage acquisition module is used for controlling the power factor correction circuit to be started when the current working parameters of the PFC power supply meet the condition that the power factor correction circuit of the PFC power supply is started, determining the working mode of the power factor correction circuit, and then acquiring the input alternating voltage instantaneous value of the PFC power supply according to the working mode of the power factor correction circuit;

18. The apparatus for acquiring an effective value of an alternating voltage of a PFC power supply of claim 17, wherein the peak voltage acquiring module comprises:

19. The apparatus for obtaining effective value of ac voltage of claim 18, wherein the power factor correction circuit is a BOOST architecture, and the first predetermined calculation formula is:

Vac_peak＝Vdc_peak+Vfrd+Vbd；

20. The apparatus for acquiring effective value of ac voltage of PFC power supply of claim 17, wherein the instantaneous voltage acquiring module comprises:

21. The apparatus for obtaining effective value of ac voltage of claim 20, wherein the power factor correction circuit further comprises a fast recovery diode, and the second predetermined calculation formula is:

Ipeak＝(Vdc+Vfrd-Vigbt)/L×D(1-D)×Ts；

22. The ac voltage effective value obtaining apparatus of the PFC power supply of claim 20, wherein the instantaneous voltage obtaining module further comprises:

23. The apparatus for obtaining the effective value of ac voltage of the PFC power supply of claim 22, wherein the PFC power supply further comprises a rectifier bridge, the power factor correction circuit further comprises a fast recovery diode, and the third predetermined calculation formula is:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts；

24. The apparatus for obtaining the effective value of ac voltage of the PFC power supply of claim 22, wherein the PFC power supply further comprises a rectifier bridge, and the fourth predetermined calculation formula is:

Vac＝L×Ipeak/Ton+Vigbt+Vbd；

25. The apparatus for acquiring effective value of ac voltage of PFC power supply of claim 17, wherein the instantaneous voltage acquiring module comprises:

26. The apparatus for obtaining effective value of ac voltage of claim 25, wherein the power factor correction circuit further comprises a fast recovery diode, and the fifth predetermined calculation formula is:

Imid＝(Vdc+Vfrd–Vigbt)/L×D(1-D)×Ts/2；

27. The apparatus for acquiring effective ac voltage value of a PFC power supply of claim 25, wherein the instantaneous voltage acquiring module further comprises:

28. The apparatus for obtaining effective value of ac voltage of a PFC power supply of claim 27, wherein the PFC power supply further comprises a rectifier bridge, the power factor correction circuit further comprises a fast recovery diode, and the sixth predetermined calculation formula is:

Vac＝Vdc×(1-D)+Vigbt×D+Vfrd×(1-D)+Vbd+L×ΔIin/Ts；

29. The apparatus for obtaining effective value of ac voltage of PFC power supply of claim 27, wherein the PFC power supply further comprises a rectifier bridge, and the seventh predetermined calculation formula is:

Vac＝L×(Imid×2)/Ton+Vigbt+Vbd；

30. The apparatus according to claim 17, wherein the effective value obtaining module is specifically configured to:

the eighth preset formula is Vac _ rms ═ Vac _ peak/sqrt (2);

the ninth preset formula is as follows: vac _ rms ═ sqrt (LPF (Vac × Vac));

31. The apparatus for obtaining the effective value of ac voltage of the PFC power supply of claim 17, wherein the current operating parameters of the PFC power supply include:

32. The apparatus for obtaining the effective value of alternating voltage of a PFC power supply of claim 31,