WO2015196672A1

WO2015196672A1 - Auxiliary power source circuit with power factor correction circuit, and control method and device therefor

Info

Publication number: WO2015196672A1
Application number: PCT/CN2014/089410
Authority: WO
Inventors: 余世伟; 陈亮
Original assignee: 欧普照明股份有限公司
Priority date: 2014-06-26
Filing date: 2014-10-24
Publication date: 2015-12-30
Also published as: CN105450054B; CN105450054A

Abstract

An auxiliary power source circuit with a PFC circuit, comprising: a PFC circuit (501) for receiving an alternating-current input voltage from an alternating-current power source and generating a direct-current output voltage and an auxiliary power source output voltage needed by a load; a PFC load size judgement circuit (504) for receiving the output current from the PFC circuit, judging whether the load of the PFC circuit is high or low according to the output current, and outputting a shielding signal to an alternating-current instantaneous voltage detection circuit when it is judged that the load of the PFC circuit is high; the alternating-current instantaneous voltage detection circuit (502) for receiving the alternating-current input voltage from the alternating-current power source, detecting an instantaneous value of the alternating-current input voltage, generating a pulse signal synchronized with the alternating-current input voltage, and outputting the pulse signal to an enable end of a PFC control circuit (503); and the PFC control circuit which controls the PFC circuit to operate in a normal operation manner when the enable end thereof receives a high-level pulse signal, and is in a non-operating state when the enable end thereof receives a low-level pulse signal.

Description

Power factor correction circuit with auxiliary power supply circuit and control method and device thereof

Technical field

The present invention relates to the field of PFC (power factor correction) technology, and more particularly to a PFC circuit with an auxiliary power supply circuit, a control method thereof and a control device.

Background technique

Figure 1 shows a conventional PFC circuit with an auxiliary power supply circuit.

As shown in Figure 1, the PFC circuit has its own auxiliary power supply circuit including: rectifier bridges DB1-DB4, receiving AC input voltage, and rectifying the AC input voltage into DC input voltage; input capacitor CBB2, connected in parallel between rectifier bridges DB1-DB4 The filter output signal of the rectifier bridge is filtered; the PFC switching power supply including the inductor L2, the switch transistor Q1 and the diode D1 is connected in parallel with the input capacitor CBB2 for generating the DC output required for the load.

2 is a conventional PFC circuit including a PFC control circuit with an auxiliary power supply circuit.

The PFC control circuit controls the operation of the PFC switching power supply by outputting a drive signal.

The two PFC inductive windings shown in Figures 1 and 2 can be used to power the control line as an auxiliary power source. They have a characteristic that they can hardly supply energy when the PFC is very light or empty, so that the entire power supply Very light load or standby mode does not provide a stable auxiliary power supply.

Figures 3 and 4 show the current flow on the inductor L2 in the existing PFC circuit with the auxiliary power supply circuit when the PFC is lightly loaded.

In the case of light load of the PFC, the PFC control circuit within a power frequency cycle may only issue a small number of drive pulses (ie, the drive pulse is intermittent, for example, only 10ms within a power frequency cycle of 50ms, the PFC control circuit is transmitting The driving pulse, which is often the lighter the load, the shorter the working time ratio, drives the switching tube Q1. The main winding and the auxiliary winding of the inductor L2 are coupled and have current flow Both the primary winding and the auxiliary winding induce a corresponding proportional voltage.

As shown in Figure 3, if the pulse is issued when the instantaneous value of the AC input voltage is high, after the pulse is turned off, the voltage difference between the main winding of the inductor L2 is relatively small, that is, the voltage drop is small, and the current on the inductor L2 will follow. The direction output of the PFC main circuit.

As shown in Figure 4, if the pulse is issued when the instantaneous value of the AC input voltage is low, the voltage difference between the two sides of the inductor L2 is relatively large when the pulse is turned off, that is, the voltage drop is high, because the voltage at the end of the main winding 2 of the inductor L2 is also the input. The voltage is low, and the voltage at the 3 terminal is the output voltage is basically constant, so the voltage drop is relatively large, the voltage drop of the main winding of the inductor L2 is large, the auxiliary winding of the inductor L2 also induces a relatively large voltage, and the current flow on the auxiliary winding of the inductor L2 As shown in Figure 4.

The present invention has been based on the phenomena in Figures 3 and 4.

Summary of the invention

The other aspects and advantages of the invention will be set forth in part in the description which follows.

The present application is a novel PFC circuit-based auxiliary power supply circuit, which adopts a PFC control circuit that is turned on when the AC input voltage is low at a light load, that is, the PFC control circuit works normally when the absolute value of the instantaneous value of the AC voltage is low, so that The PFC control circuit operates near the AC voltage across zero, enabling stable output at light loads.

The present application discloses a PFC circuit with an auxiliary power supply circuit, comprising: a PFC circuit, receiving an AC input voltage from an AC power source, and generating a DC output voltage required for the load and an auxiliary power voltage output; a PFC load size judging circuit, receiving The output current from the PFC circuit, and judge whether the load of the PFC circuit is high or low according to the output current. When it is judged that the load of the PFC circuit is high, the shield signal is output to the alternating current instantaneous voltage detecting circuit; the alternating current instantaneous voltage detecting circuit receives the AC power source. The AC input voltage detects the instantaneous value of the AC input voltage, generates a pulse signal synchronized with the AC input voltage, and outputs the pulse signal to the PFC control circuit. The PFC control circuit controls the PFC circuit according to the normal working mode when the enable terminal receives the high-level pulse signal, and is in the non-working state when the enable terminal receives the low-level pulse signal.

The present application also discloses a control device for a PFC circuit with an auxiliary power supply circuit, the PFC circuit operating according to the control of the PFC control circuit, the control device comprising: a PFC load size determination circuit, receiving an output current from the PFC circuit, and Judging whether the load of the PFC circuit is high or low according to the output current, when determining that the load of the PFC circuit is high, outputting a shielding signal to the alternating current instantaneous voltage detecting circuit; the alternating current instantaneous voltage detecting circuit receiving the alternating current input voltage from the alternating current power source, and the alternating current input The instantaneous value of the voltage is detected, a pulse signal synchronized with the AC input voltage is generated, and the pulse signal is output to the enable end of the PFC control circuit.

The present application also discloses a PFC circuit self-contained auxiliary power supply circuit control method, the PFC circuit operates according to the control of the PFC control circuit, the control method includes: detecting whether the load of the PFC circuit is high or low; when detecting the PFC circuit When the load is low, the AC input voltage is detected; a pulse signal synchronized with the AC input voltage is generated and output to the PFC control circuit; and the pulse signal controls the PFC control circuit to be in an active state or a non-operation state.

DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the <RTIgt

FIG. 5 shows a block diagram of a PFC circuit with an auxiliary power supply circuit in accordance with an embodiment of the present invention.

FIG. 6 shows a detailed circuit diagram of an alternating current instantaneous voltage detecting circuit according to an embodiment of the present invention.

7A and 7B are diagrams showing the manner in which a PFC control circuit is controlled by a pulse signal output from an alternating current instantaneous voltage detecting circuit in accordance with an embodiment of the present invention.

FIG. 8 is a flow chart showing a control method of a PFC circuit with an auxiliary power supply circuit according to an embodiment of the present invention.

detailed description

The invention will be fully described below with reference to the drawings, which illustrate embodiments of the invention. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and the scope of the invention In the drawings, the components are exaggerated for clarity.

It will be understood that when an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or the intermediate element can be present. In contrast, when an element is referred to as being "directly connected" The same reference numbers indicate the same elements. The term "and/or" used herein includes any and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components and/or portions, these elements, components and/or portions are not limited by these terms. These terms are only used to distinguish one element, component or part. Thus, a first element, component or portion discussed below may be referred to as a second element, component or portion without departing from the teachings of the invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning meaning meaning It should also be understood that terms such as those defined in a typical dictionary should be interpreted as having meanings consistent with their meaning in the context of the related art, and not interpreted in an idealized or extremely formalized sense unless It is clearly defined as such.

The main technical feature of the present invention is that, when the PFC circuit is under no-load or very light load, the intermittent driving pulses from the PFC control circuit are all sent out when the input AC power is low, and the PFC is controlled. The control circuit does not work when the input AC power is high, so that a large voltage difference between the two ends of the inductor can be ensured, thereby ensuring the auxiliary winding voltage output of the inductor as the auxiliary power source.

As shown in FIG. 5, the PFC circuit has its own auxiliary power supply circuit including a PFC circuit 501, a PFC control circuit 503, and a control device. The control device includes an alternating current instantaneous voltage detecting circuit 502 and a PFC load size determining circuit 504.

The PFC circuit 501 receives an AC input voltage from an AC power source and generates a DC output required for the load and an auxiliary power voltage output.

The PFC load size judging circuit 504 receives the DC output from the PFC circuit 501, and judges whether the load of the PFC circuit 501 is high or low based on the DC output. When the PFC load size judging circuit 504 judges that the PFC circuit 501 is high (full load), the AC instantaneous voltage detecting circuit 502 is shielded. At this time, the PFC circuit 501 and the conventional PFC external auxiliary power supply work in exactly the same state. The PFC load size judging circuit 504 is for shielding the AC instantaneous voltage detecting circuit 502 when the PFC circuit 501 is heavily loaded, and does not output the mask signal to the AC instantaneous voltage detecting circuit 502 when the PFC circuit 501 is under a low load.

Although the PFC load size determination circuit 504 is shown in FIG. 5 to determine the level of the load of the PFC circuit 501 based on the DC output from the PFC circuit 501, those skilled in the art will appreciate that the PFC load size determination circuit 504 can also be based on other signals. The level of the load of the PFC circuit 501 is judged. For example, a DC-DC converter is usually connected to the PFC circuit, and the PFC load size determining circuit 504 can also receive an enable signal or output power of the DC-DC converter, and determine the load of the PFC circuit 501 based thereon. High and low.

The AC instantaneous voltage detecting circuit 502 does not operate when receiving the mask signal from the PFC load size determining circuit 504 (the mask signal is, for example, a long high level). When the mask signal from the PFC load size judging circuit 504 is not received, that is, when the PFC circuit 501 is lightly loaded or idling, the AC instantaneous voltage detecting circuit 502 operates.

The AC instantaneous voltage detecting circuit 502 receives the AC input voltage from the AC power source, detects the instantaneous value of the AC input voltage, and obtains a pulse signal synchronized with the AC input voltage (for example, the instantaneous absolute value of the AC input voltage is lower than a predetermined threshold) The pulse signal is at a high level, and when the instantaneous absolute value of the AC input voltage is higher than a predetermined threshold, the pulse signal is at a low level, and the pulse signal is output to the enable end of the PFC control circuit 503.

The enable terminal of the PFC control circuit 503 receives the pulse signal. When the pulse signal is high level, the PFC control circuit 503 is enabled to control the operation of the PFC circuit 502 in accordance with the normal operation mode, that is, the switching transistor Q1 is turned on or off according to the driving voltage from the PFC control circuit 503, and allows the input current. The waveform tracks the voltage waveform while the auxiliary winding of the inductor L2 of the PFC circuit 502 induces a voltage as an auxiliary power supply output voltage. When the pulse signal is low, the PFC control circuit 503 is disabled.

With the present invention, it is possible to make the AC instantaneous voltage detecting circuit 502 emit a high level signal only when the AC input signal is low to force the PFC control circuit 503 to be in operation, thereby ensuring that the PFC inductor auxiliary winding output voltage is high.

Those skilled in the art should understand that the PFC circuit 501 and the PFC control circuit 503 can employ the existing PFC circuit and its control circuit as described in FIGS. 1 and 2, and other suitable PFC circuits and their control circuits can also be used.

FIG. 6 shows a detailed circuit diagram of an alternating current transient voltage detecting circuit 502 in accordance with an embodiment of the present invention.

As shown in FIG. 6, the alternating current instantaneous voltage detecting circuit 502 includes first and second diodes D8 and D9, a Zener diode ZD3, and a transistor Q4. Positive electrode of the first diode D8 and second diode The positive terminal of D9 serves as an input terminal of the alternating current instantaneous voltage detecting circuit 502, and receives an input from an alternating current power source. The anode of the first diode D8 is coupled to the L terminal of the AC power source, the anode of the second diode D9 is coupled to the N terminal of the neutral line of the AC power source, the cathode of the first diode D8 and the second diode D9. The negative pole is coupled to the negative pole of the Zener diode ZD3, the anode of the Zener diode ZD3 is coupled to the base of the transistor Q4, the collector of the transistor Q4 is the output of the AC instantaneous voltage detecting circuit 502, and the emitter of the transistor Q4 is grounded.

The alternating current transient voltage detecting circuit 502 further includes first to fourth resistors R37, R38, R39, and R14. The first to third resistors R37-R39 are connected between the connection point of the negative electrode of the first diode D8 and the negative electrode of the second diode D9 and the negative electrode of the Zener diode ZD3, and the collector of the transistor Q4 passes the fourth The resistor R14 is connected to the power supply Vcc.

The alternating current instantaneous voltage detecting circuit 502 detects an alternating current input voltage from the alternating current power source received at the input end thereof, and when the instantaneous absolute value of the input voltage is detected to be lower than a predetermined threshold, the alternating current instantaneous voltage detecting circuit 502 outputs a high level through the output end thereof. The pulse signal is sent to the PFC control circuit 503 to enable the PFC control circuit 503 to operate normally. When it is detected that the instantaneous absolute value of the input voltage is higher than a predetermined threshold, the alternating current instantaneous voltage detecting circuit 502 outputs a low level pulse signal through its output terminal, and the PFC control circuit 503 is prohibited from operating.

Those skilled in the art should understand that the alternating current instantaneous voltage detecting circuit 502 is not limited to the circuit shown in FIG. 6, and FIG. 6 is only one of the implementations of the alternating current instantaneous voltage detecting circuit 502. Any circuit capable of realizing the function of the alternating current instantaneous voltage detecting circuit 502 of the present invention is within the scope of the present invention.

7A and 7B are diagrams for controlling the PFC control circuit 503 by a pulse signal output from the alternating current instantaneous voltage detecting circuit 502 according to an embodiment of the present invention.

The PFC control circuit 503 shown in Figures 7A and 7B is an existing L6562 PFC controller.

As shown in FIG. 7A, the pulse signal output from the alternating current instantaneous voltage detecting circuit 502 can be directly output to the zero current detector in the PFC control circuit 503 to enable the L6562 PFC controller. Current zero crossing detection section. Alternatively, as shown in Fig. 7B, the pulse signal output from the alternating current instantaneous voltage detecting circuit 502 can be directly output to the driver in the PFC control circuit 503 to directly enable the PFC pulse output portion. Applying the enable signal in both ways can force the PFC control circuit 503 to not operate when the AC input voltage is high, and to operate normally when the instantaneous absolute value of the AC input voltage is below a predetermined threshold.

That is, when the AC input voltage is high, the PFC control circuit 503 does not supply the driving voltage to the switching transistor Q1 inside the PFC circuit 501; and when the instantaneous absolute value of the AC input voltage is lower than the predetermined threshold, the PFC control circuit 503 goes to the PFC circuit. The switching transistor Q1 inside the 501 provides a driving voltage.

It should be understood by those skilled in the art that the PFC control circuit 503 is not limited to the L6562 PFC controller shown in FIG. 7, and therefore, the manner of adding an enable signal to the PFC control circuit 503 is not limited to the mode shown in FIG. Any of the circuits capable of implementing the functions of the PFC control circuit 503 of the present invention and the various ways of applying an enable signal to the PFC control circuit 503 are within the scope of the present invention.

At step 801, it is detected whether the load of the PFC circuit is high or low.

At step 802, the AC input voltage is detected when the load of the PFC circuit is low.

At step 803, a pulse signal synchronized with the AC input voltage is generated and output to the PFC control circuit, wherein when the instantaneous absolute value of the AC input voltage is below a predetermined threshold, the pulse signal is at a high level; when the AC input voltage is The pulse signal is at a low level when the instantaneous absolute value is above a predetermined threshold.

At step 804, the pulse signal controls the PFC control circuit to be in an active or inactive state, ie, when the PFC control circuit receives a high level pulse signal, it operates normally, and does not operate when a low level pulse signal is received.

The improved control device of the PFC circuit with the auxiliary power supply circuit according to the embodiment of the present invention has an AC input voltage instantaneous value detecting circuit, and the output signal of the AC voltage instantaneous value detecting circuit is Output to the PFC control circuit, and under light load, when the AC input voltage is low, the AC voltage instantaneous value detecting circuit outputs a high level pulse, and under heavy load, shields the AC voltage instantaneous value detecting circuit from the function .

The improved control method according to an embodiment of the present invention is suitable for using an auxiliary winding of a PFC circuit as an auxiliary power source, and requires that the auxiliary power source of the PFC circuit is also lightly loaded or under no load (the control circuit operates in a standby state). For example, the drive circuit of the luminaire has a control receiver module that receives the remote control signal when the luminaire is off (the main output is off).

The above is a description of the invention and should not be construed as limiting thereof. While the invention has been described with respect to the preferred embodiments of the embodiments of the present invention Therefore, all such modifications are intended to be included within the scope of the invention as defined by the appended claims. It is to be understood that the foregoing is a description of the invention, and is not intended to be limited to the specific embodiments disclosed, and modifications of the disclosed embodiments and other embodiments are intended to be included within the scope of the appended claims. The invention is defined by the claims and their equivalents.

Claims

A PFC circuit with an auxiliary power supply circuit, comprising:

a PFC circuit that receives an AC input voltage from an AC power source and generates a DC output voltage required for the load and an auxiliary power supply voltage output;

The PFC load size judging circuit receives the DC output from the PFC circuit, and determines whether the load of the PFC circuit is high or low according to the DC output, and outputs a shielding signal to the AC instantaneous voltage detecting circuit when determining that the PFC circuit load is high;

The alternating current instantaneous voltage detecting circuit receives the alternating current input voltage from the alternating current power source, detects the instantaneous value of the alternating current input voltage, generates a pulse signal synchronized with the alternating current input voltage, and outputs the pulse signal to the enable end of the PFC control circuit;

The PFC control circuit, when its enable terminal receives a high-level pulse signal, controls the PFC circuit to operate according to the normal working mode, and is in a non-operating state when its enable terminal receives a low-level pulse signal.
The PFC circuit of claim 1 having an auxiliary power supply circuit, wherein when the alternating current instantaneous voltage detecting circuit detects that the instantaneous absolute value of the alternating current input voltage is lower than a predetermined threshold, generating a high level pulse signal, and when the alternating current is instantaneous When the voltage detecting circuit detects that the instantaneous absolute value of the AC input voltage is higher than a predetermined threshold, a pulse signal of a low level is generated.
The PFC circuit of claim 2 has an auxiliary power supply circuit, and the alternating current instantaneous voltage detecting circuit comprises:

a first diode and a second diode, a positive pole of the first diode and an anode of the second diode serving as an input of an alternating current instantaneous voltage detecting circuit, receiving an input from an alternating current power source; the anode of the first diode is coupled to The L terminal of the live line of the AC power source, the anode of the second diode is coupled to the N terminal of the neutral line of the AC power source;

a Zener diode, a cathode of the Zener diode coupled to a connection point of a cathode of the first diode and a cathode of the second diode;

The triode, the base of the triode is coupled to the anode of the Zener diode, the collector of the triode acts as the output of the AC instantaneous voltage detection circuit, and the emitter of the transistor is grounded.
The PFC circuit of claim 3 has an auxiliary power supply circuit, and the alternating current instantaneous voltage detecting circuit further comprises:

First to third resistors connected between a cathode of the first diode and a cathode of the second diode and a cathode of the Zener diode;

The fourth resistor, the collector of the transistor is connected to the power supply through the fourth resistor.
The PFC circuit of claim 4, comprising an auxiliary power supply circuit, wherein a DC-DC converter is further included between the PFC circuit and the PFC load size determining circuit, and the PFC load size determining circuit receives the DC-DC converter The enable signal or the output power, and determine whether the load of the PFC circuit is high or low according to the enable signal or the output power.
The PFC circuit according to claim 5 has an auxiliary power supply circuit, and the alternating current instantaneous voltage detecting circuit directly outputs the pulse signal to the driver in the PFC control circuit to directly enable the PFC pulse output portion.
A control device for a PFC circuit with an auxiliary power supply circuit, the PFC circuit is based on a PFC Control of the control circuit operates, the control device comprising:

The PFC load size judging circuit receives the DC output from the PFC circuit, and determines whether the load of the PFC circuit is high or low according to the DC output, and outputs a shielding signal to the AC instantaneous voltage detecting circuit when determining that the PFC circuit load is high;

The AC instantaneous voltage detecting circuit receives the AC input voltage from the AC power source, detects the instantaneous value of the AC input voltage, generates a pulse signal synchronized with the AC input voltage, and outputs the pulse signal to the enable end of the PFC control circuit.
The control device according to claim 7, wherein when the alternating current instantaneous voltage detecting circuit detects that the instantaneous absolute value of the alternating current input voltage is lower than a predetermined threshold, a pulse signal of a high level is generated, and when the alternating current instantaneous voltage detecting circuit detects When the instantaneous absolute value of the AC input voltage is higher than a predetermined threshold, a low-level pulse signal is generated.
The control device according to claim 8, wherein when the alternating current instantaneous voltage detecting circuit outputs a high-level pulse signal, the PFC control circuit is enabled to control the PFC circuit to operate according to a normal operation mode, and the alternating current instantaneous voltage detecting circuit outputs a low voltage. When the pulse signal is flat, the PFC control circuit is disabled.
The control device according to claim 9, wherein the alternating current instantaneous voltage detecting circuit comprises:

a first diode and a second diode, a positive pole of the first diode and an anode of the second diode serving as an input of an alternating current instantaneous voltage detecting circuit, receiving an input from an alternating current power source; the anode of the first diode is coupled to The L terminal of the live line of the AC power source, the anode of the second diode is coupled to the N terminal of the neutral line of the AC power source;

a Zener diode, a cathode of the Zener diode coupled to the cathode and the second pole of the first diode The connection point of the negative electrode of the tube;

The triode, the base of the triode is coupled to the anode of the Zener diode, the collector of the triode acts as the output of the AC instantaneous voltage detection circuit, and the emitter of the transistor is grounded.
The control device according to claim 10, wherein the alternating current instantaneous voltage detecting circuit further comprises:

First to third resistors connected between a cathode of the first diode and a cathode of the second diode and a cathode of the Zener diode;

The fourth resistor, the collector of the transistor is connected to the power supply through the fourth resistor.
The control device according to claim 11, further comprising a DC-DC converter between said PFC circuit and said PFC load size judging circuit, said PFC load size judging circuit receiving an enable signal of said DC-DC converter or Output power, and judge whether the load of the PFC circuit is high or low according to the enable signal or the output power.
The control device according to claim 11, wherein the alternating current instantaneous voltage detecting circuit directly outputs the pulse signal to the driver in the PFC control circuit to directly enable the PFC pulse output portion.
A PFC circuit has a control method for an auxiliary power supply circuit, and the PFC circuit operates according to control of a PFC control circuit, and the control method includes:

Check whether the load of the PFC circuit is high or low;

When the load of the PFC circuit is detected to be low, the AC input voltage is detected;

Generating a pulse signal synchronized with the AC input voltage and outputting to the PFC control circuit;

The pulse signal controls the PFC control circuit to be in an active or inactive state.
The control method according to claim 14, wherein when the AC input voltage is instantaneous The pulse signal is at a high level when the value is below a predetermined threshold; the pulse signal is at a low level when an instantaneous absolute value of the AC input voltage is above a predetermined threshold.
The control method according to claim 15, wherein the PFC control circuit operates normally when the high-level pulse signal is received, and the PFC control circuit is disabled when the low-level pulse signal is received.