JP2013055810A - Switching power supply apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching power supply apparatus having a bridgeless power factor improvement circuit, which does not need a double system control circuit for normal switching operation in order to execute protection operation, and also provide control method therefor.SOLUTION: A switching power supply apparatus 1 comprises a power factor improvement circuit 2 having: a first reactor (L1) connected between a connection point of a first rectifier element (D1) and a first switching element (Q1) and an end of an AC power supply (Vac); and a second reactor (L2) connected between a connection point of a second rectifier element (D2) and a second switching element (Q2) and the other end of the AC power supply (Vac). A switching control section 5 determines aberration occurrence out of the switching power supply apparatus 1 on the basis of either of/both of an output signal from L1 and L2 current detection circuits 6, 7 or/and an output signal from an AC voltage detection circuit 8, so as to stop the first and the second switching elements (Q1, Q2) from switching operation.

Description

  The present invention relates to a switching power supply device and a control method thereof, and more particularly to a switching power supply device having a function of detecting that an abnormality has occurred in the device and executing a protection operation and a control method thereof.

  2. Description of the Related Art Conventionally, a switching power supply device that rectifies an AC voltage of an input AC power supply, converts the AC voltage to a desired AC or DC voltage, and supplies it to a load is widely used. Such a switching power supply device is required to be provided with a power factor correction circuit in order to improve its power factor and reduce EMI noise generated from the device. Therefore, in a general configuration of a switching power supply device, a rectifier circuit composed of a diode bridge and a power factor correction circuit composed of a boost converter circuit are mounted at the input stage.

  On the other hand, in switching power supply devices, a power factor improvement circuit (hereinafter also referred to as a bridgeless power factor improvement circuit) that eliminates the need for a diode bridge in the previous stage by combining a power factor improvement function by a boost operation and a rectification function has been proposed. (For example, refer to Patent Document 1). This bridgeless power factor correction circuit consists of a rectifier circuit and a power factor correction circuit separately because the input stage of the switching power supply device is configured by a simple circuit and the conduction loss of the diode can be reduced. This is more advantageous than the provided configuration.

  In order to use such a switching power supply device safely, in addition to normal switching operation control, it is desirable to perform a protective operation such as stopping the switching operation when an abnormality occurs in the device. . In general, in a conventional switching power supply device, in order to perform this protection operation, a detection circuit that detects a voltage or current in the device and / or a detection value thereof is provided separately from a normal switching operation control circuit system. A protection circuit that operates accordingly is provided.

  For example, a control IC for a power factor correction circuit described in Patent Document 1 includes an input terminal (OVP) for overvoltage protection and an input terminal for overvoltage protection separately from an output voltage feedback terminal (VFB) for normal switching operation control. An overvoltage protection comparator connected to the switching element is disclosed. Patent Document 1 discloses that when the output voltage input from the input terminal exceeds a predetermined threshold, the gate drive of the switch element is stopped. Have been described.

Special table 2007-527687

  However, in general, in a configuration in which a detection circuit and / or protection circuit for performing a protection operation is provided separately from a control circuit for normal switching operation (hereinafter also referred to as a dual system), the control of the switching power supply device is performed. There is a problem that the circuit becomes complicated and the cost of the apparatus increases.

  Furthermore, in the bridgeless power factor correction circuit, the switching operation is shared by different switch elements for each half cycle with different polarities of the AC voltage input to the device. There is also a problem that the system configuration may not function sufficiently as a protection means.

That is, even if the bridgeless power factor correction circuit has a protection means for determining an abnormality of the device by detecting an overvoltage (or other detection target such as a voltage drop or an overcurrent), for example, for some reason When the switching operation of one of the switch elements stops and the output control in the corresponding half cycle is not performed, only the corresponding half cycle output control by the switching operation of the other switch element is performed. In such a state, there is a possibility that the operation of the apparatus may continue without causing an overvoltage or the like at a level determined to be abnormal in the output.

  When the state in which the output is controlled by only one of the switch elements continues for a long time in this way, the operation is concentrated on the switch element and the corresponding control system, and the apparatus is overheated. Serious damage such as burnout may occur. Therefore, in the bridgeless power factor correction circuit, the protection means detects a state in which the output is controlled by only one of the switch elements as an abnormality and executes a protection operation to prevent the occurrence of serious damage as described above. It is desirable that it can be prevented.

  In addition, as a method for executing this, a method of detecting an overheating state of the apparatus is conceivable. In this method, a temperature sensor and its detection signal are used separately from a control circuit for normal switching operation. Thus, a means for discriminating the overheated state is required, and there is a disadvantage that the control circuit becomes complicated due to the dual system as described above.

  Furthermore, the phenomenon that the operation concentrates only on one switch element and its control system is not only when the operation of one switch element actually stops, but also on the abnormality of the means for determining the polarity of the AC voltage or the input to the device This may occur even when an imbalance occurs in the length of the period during which output control is performed by the switching operation of each switch element due to an abnormality in the AC voltage waveform itself, etc., and bridgeless power factor improvement It is desirable that the circuit protection means can detect such a phenomenon as an abnormality and perform an appropriate protection operation.

The present invention has been made in view of the above problems, and its purpose is to provide a switching power supply device having a bridgeless power factor correction circuit without making the control circuit for normal switching operation a dual system. It is an object of the present invention to provide a switching power supply apparatus capable of performing a protection operation and a control method thereof.

  The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further, while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) A power factor correction circuit (2) having a first switch element (Q1) and a second switch element (Q2), and a first and a first detecting an input current from both ends of an AC power supply (Vac), respectively. 2 input current detection circuits (6, 7), an input voltage detection circuit (8) for detecting input voltages at both ends of the AC power supply (Vac), and an output voltage of the power factor correction circuit (2) are predetermined. And a switching control unit (5) for controlling the first and second switch elements (Q1, Q2) so that the voltage is equal to the voltage of the input voltage detection circuit (8). The first and second switch elements (Q1, Q2) are determined based on the input voltage detection signal output from the first and second input current detection circuits (6, 6). 7) Input current output from A switching power supply device configured to determine the period of the switching operation of each of the first and second switch elements (Q1, Q2) based on an output signal, wherein the switching control unit (5) includes: Based on one or both of the input current detection signal output from the first and second input current detection circuits (6, 7) and the input voltage detection signal output from the input voltage detection circuit (8). The switching power supply is characterized by determining occurrence of an abnormality in the switching power supply device and stopping the switching operation of the first and second switch elements (Q1, Q2) when it is determined that the abnormality has occurred. Apparatus (claim 1).

(2) In the switching power supply device according to item (1), the power factor correction circuit (2) includes a smoothing capacitor (C1) connected in parallel to the load circuit (3), and a first rectifier element (D1). ) And a first switch element (Q1), and a second series circuit composed of a second rectifier element (D2) and a second switch element (Q2), One series circuit and the second series circuit include one end on the first rectifier element (D1) side, one end on the second rectifier element (D2) side, and the first switch element (Q1). And one end on the second switch element (Q2) side are connected in parallel with each other, and the first and second rectifier elements (D1, D2) are connected to the smoothing capacitor (C1). The smoothing capacitor (C1) so as to be charged A first reactor connected to the column and connected between a connection portion of the first rectifier element (D1) and the first switch element (Q1) and one end of an AC power supply (Vac); (L1), a second reactor (L2) connected between the second rectifier element (D2), the connection portion of the second switch element (Q2), and the other end of the AC power supply (Vac). ), And the first switch element (Q1) and the connection part of the second switch element (Q2) and one end of the AC power supply (Vac) on the first reactor (L1) side. The third rectifier element (D3), the connection portion of the first switch element (Q1) and the second switch element (Q2), and the second reactor (L2) side of the AC power supply (Vac) A fourth rectifying element (D4) connected between the first end and the fourth rectifying element (D4). Switching power supply device according to claim bets (claim 2).

(3) In the switching power supply device according to (1) or (2), the switching control unit (5) is configured so that the input current detection signal output from the first input current detection circuit (6) From the state in which the first timing information that determines the cycle of the switching operation of the first switch element (Q1) is not detected and the input current detection signal output from the second input current detection circuit (6), the first If at least one of the states in which the first timing information that determines the cycle of the switching operation of the two switching elements (Q2) is not detected exceeds the predetermined first period, the switching power supply device is abnormal. It is determined that the occurrence of the switching power supply device (claim 3).

(4) In the switching power supply according to (3), the first period is a period longer than one cycle of the AC power supply (Vac) (Claim 4). .

(5) In the switching power supply device according to any one of (1) to (4), the switching control unit (5) receives an input voltage detection signal output from the input voltage detection circuit (8), The state in which the second timing information corresponding to the switching time point between the driving period of the first switch element (Q1) and the driving period of the second switch element (Q1) is not detected exceeds the predetermined second period. When the switching power supply device continues, it is determined that an abnormality has occurred in the switching power supply device (claim 5).

(6) In the switching power supply device described in (5), the second period is a period longer than a half cycle of the AC power supply (Vac) (Claim 6). .

(7) A power factor correction circuit (2) having a first switch element (Q1) and a second switch element (Q2), and a first and a second detecting an input current from both ends of the AC power supply (Vac), respectively. 2 input current detection circuits (6, 7), an input voltage detection circuit (8) for detecting input voltages at both ends of the AC power supply (Vac), and an output voltage of the power factor correction circuit (2) are predetermined. And a switching control unit (5) for controlling the first and second switch elements (Q1, Q2) so that the voltage is equal to the voltage of the input voltage detection circuit (8). The first and second switch elements (Q1, Q2) are determined based on the input voltage detection signal output from the first and second input current detection circuits (6, 6). 7) Input current output from A switching power supply control method configured to determine a period of a switching operation of each of the first and second switch elements (Q1, Q2) based on an output signal, wherein the first and second switching power supply devices are controlled. Based on either or both of the input current detection signal output from the input current detection circuit (6, 7) and the input voltage detection signal output from the input voltage detection circuit (8). Switching including: a step of determining occurrence of an abnormality, and a step of stopping the switching operation of the first and second switch elements (Q1, Q2) when it is determined that the abnormality has occurred. A method for controlling a power supply device (claim 7).

(8) In the method for controlling a switching power supply according to (7), the step of determining the occurrence of an abnormality in the switching power supply includes an input output from the first input current detection circuit (6). A state in which the first timing information for determining the cycle of the switching operation of the first switch element (Q1) is not detected from the current detection signal, and is output from the second input current detection circuit (7). At least one of the states in which the first timing information for determining the cycle of the switching operation of the second switch element (Q2) is not detected from the input current detection signal continues beyond the predetermined first period. And a method for controlling the switching power supply device, comprising the step of determining that an abnormality has occurred in the switching power supply device.

(9) In the method for controlling a switching power supply according to (7) or (8), the step of determining the occurrence of an abnormality in the switching power supply is output from the input voltage detection circuit (8). A state in which the second timing information corresponding to the switching time point between the driving period of the first switch element (Q1) and the driving period of the second switch element (Q2) is not detected from the input voltage detection signal is a predetermined state. A control method for a switching power supply apparatus, comprising: a step of determining that an abnormality has occurred in the switching power supply apparatus when continuing beyond a second period (claim 9).

According to the switching power supply device and the control method thereof according to the present invention, in the switching power supply device provided with the bridgeless power factor correction circuit, a simple circuit configuration without making the control circuit for normal switching operation a dual system This makes it possible to execute a protection operation when an abnormality occurs.
In particular, in the switching power supply device and the control method thereof according to the present invention, in the bridgeless power factor correction circuit, the state where the output control concentrates on the switching operation of one of the two switch elements is reliably determined as an abnormality. By detecting and executing the protection operation, it is possible to prevent serious damage such as burning of the circuit element, which may occur when such a state continues.

It is a circuit block diagram which shows an example of the switching power supply device in one Embodiment of this invention. FIG. 2 is a functional block diagram illustrating a configuration example of a switching control unit in the switching power supply device illustrated in FIG. 1. FIG. 2 is a waveform diagram showing a driving period of a first switch element and a driving period of a second switch element together with an AC power supply waveform during normal operation of the switching power supply device shown in FIG. 1. 3 is a timing chart showing control of switching periods of the first and second switch elements by a switching control unit during normal operation of the switching power supply device shown in FIG. 1. 2 is a flowchart illustrating an example of an abnormality determination procedure in the control method for the switching power supply device illustrated in FIG. 1. 6 is a flowchart showing another example of an abnormality determination procedure in the switching power supply device control method shown in FIG. 1.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a circuit configuration diagram showing a switching power supply device 1 according to an embodiment of the present invention. The switching power supply device 1 includes a power factor correction circuit 2, and a load circuit 3 is connected to the power factor correction circuit 2. The power factor correction circuit 2 includes a first series circuit composed of a first rectifier element D1 and a first switch element Q1, and a second series circuit composed of a second rectifier element D2 and a second switch element Q2. have. In the power factor correction circuit 2, diodes are used as the first and second rectifier elements D1 and D2, and MOS-FETs are used as the first and second switch elements Q1 and Q2. Is formed by connecting the anode terminal of the first rectifier element D1 and the drain terminal of the first switch element Q1, and the second series circuit includes the anode terminal of the second rectifier element D2 and the second switch element. Connected to the drain terminal of Q2.

The first series circuit and the second series circuit connect the cathode terminals of the first and second rectifier elements D1 and D2, and connect the source terminals of the first and second switch elements Q1 and Q2, They are connected in parallel to each other, and a smoothing capacitor C1 is connected in parallel with the first series circuit (and the second series circuit).
The power factor correction circuit 2 includes a first reactor L1 and a second reactor L2, and one end of the first reactor L1 is a connection between the first rectifier element D1 and the first switch element Q1. The other end is connected to one end of the AC power supply Vac. One end of the second reactor L2 is connected to a connection portion between the second rectifying element D2 and the second switch element Q2, and the other end is connected to the other end of the AC power supply Vac.

That is, in the parallel circuit of the first series circuit and the second series circuit, the first rectifier element D1 charges the smoothing capacitor C1 from the AC power supply Vac via the first reactor L1, the second rectification. The element D2 is connected in the direction in which the smoothing capacitor C1 is charged from the AC power source Vac via the second reactor L2.

Furthermore, the power factor correction circuit 2 includes third to sixth rectifying elements D3, D4, D5, and D6 each formed of a diode. Here, the connection mode of the third to sixth rectifying elements D3, D4, D5, and D6 in the power factor correction circuit 2 will be described in detail.

The cathode terminal of the third rectifying element D3 is connected to one end of the AC power supply Vac on the first reactor L1 side, and the cathode terminal of the fourth rectifying element D4 is one end of the AC power supply Vac on the second reactor L2 side. And the anode terminals of the third and fourth rectifying elements D3 and D4 are connected to the connecting portion of the first switch element Q1 and the second switch element Q2 (that is, one end of the smoothing capacitor C1). The

The anode terminal of the fifth rectifying element D5 is connected to one end of the AC power supply Vac on the first reactor L1 side, and the anode terminal of the sixth rectifying element D6 is connected to the second reactor L2 side of the AC power supply Vac. The cathode terminals of the fifth and sixth rectifying elements D5 and D6 are connected to the connecting portion between the first rectifying element D1 and the second rectifying element D2 (that is, the other end of the smoothing capacitor C1). ).

The switching power supply device 1 further includes a switching control unit 5 that controls the switching operation of the first and second switch elements Q1 and Q2, and according to a drive pulse (gate drive signal) output from the switching control unit 5. The first and second switch elements Q1 and Q2 are switched. As a result, the power factor correction circuit 2 rectifies and boosts the input AC voltage from the AC power supply Vac while improving the power factor without providing a diode bridge, and with respect to the load circuit 3 connected in parallel to the smoothing capacitor C1. The DC voltage across the smoothing capacitor C1 (hereinafter referred to as PFC voltage) is output.

  The switching power supply device 1 includes a detection unit 4. The detection unit 4 detects a PFC voltage and outputs an output signal corresponding to the detected value to the switching control unit 5. And an L1 current detection circuit (a first current detection circuit) that detects an input current flowing from one end of the AC power supply Vac through the first reactor L1 and outputs an output signal (input current detection signal) corresponding to the detected value to the switching control unit 5. The input current flowing through the second reactor L2 from the other end of the AC power supply Vac and the output signal (input current detection signal) corresponding to the detected value is output to the switching controller 5. The L2 current detection circuit (second input current detection circuit) 7 and the input voltage across the AC power supply Vac are detected, and an output signal (input voltage detection signal) corresponding to the detected value And AC voltage detection circuit (input voltage detection circuit) 8 to be output to the switching control unit 5 are included.

The switching control unit 5, as will be described later, on the basis of these output signals output from the detection unit 4, the period (frequency) of drive pulses for the switch elements Q 1 and Q 2 so that the PFC voltage becomes a predetermined voltage. ) And on-duty, and the switching operation of the first and second switch elements Q1 and Q2 is controlled.

  In the switching power supply device 1, the load circuit 3 typically converts the input PFC voltage and outputs a predetermined DC or AC voltage, or a DC-DC converter or a DC-AC converter (inverter). For example, a current resonance (LLC) converter circuit is included. However, the switching power supply device 1 according to the present invention is not limited by the configuration of the load circuit 3, and any appropriate load circuit using a PFC voltage as an input voltage can be applied.

As shown in FIG. 2, the switching control unit 5 includes a drive circuit 1 (29) that outputs a drive pulse for the first switch element Q1, and a drive circuit 2 (30 that outputs a drive pulse for the second switch element Q2. ) And a switch element control circuit 10 for outputting a command signal for outputting a predetermined drive pulse to the drive circuits 1 and 2 (29, 30).

  The switch element control circuit 10 includes, as functional blocks, an AC voltage AD conversion unit 24, an AC polarity determination unit 25, a PFC voltage AD conversion unit 21, a duty calculation unit 22, a duty limiter unit 23, a comparator 1 (26), a comparison 2 (27) and a PWM output control unit 28 for PFC. Although not shown, the switch element control circuit 10 further includes a time measuring unit that functions as a PWM timer and abnormality determination timers 1 to 3 described later.

  Here, the switch element control circuit 10 is preferably configured as a digital control device using a programmable device such as a microcomputer, DSP, or FPGA. However, each functional block constituting such a switch element control circuit 10 can be implemented by any appropriate hardware or software, or a combination thereof, as long as the control procedure described below is executed. The hardware may include an analog circuit.

Here, in the following explanation, regarding the polarity of the AC power supply Vac, the polarity at which one end on the first reactor L1 side is higher than the one end on the second reactor L2 side is “positive”, and the second reactor L2 side The polarity at which one end of the AC power supply Vac is higher than that at one end on the first reactor L1 side is defined as “negative”, and in one cycle of voltage fluctuation of the AC power supply Vac, the positive polarity period is the positive half cycle period, The negative period is called the negative half cycle period.

However, in the method for controlling the switching power supply device 1 according to the present invention, as described later, when an abnormality occurs in the waveform of the AC power supply Vac due to some factor, the abnormality is detected and an appropriate protection operation is executed. Therefore, in this specification, the term “half cycle” refers to a half of one cycle in a normal waveform of the AC power supply Vac.
Therefore, in the switching power supply device 1, when an abnormality occurs in the waveform of the AC power supply Vac, the lengths of the positive half cycle period and the negative half cycle period are not necessarily the same as each other. The length of either or both of the half cycle periods is not necessarily the same as the half period of the AC power supply Vac.

Next, the normal operation of the power factor correction circuit 2 will be described with reference to FIGS. 3 and 4 together with FIG.
In the switch element control circuit 10, the output signal from the AC voltage detection circuit 8 is input to the AC voltage AD conversion unit 24 and A / D converted, and the digital data corresponding to the input voltage of the AC power supply Vac obtained thereby. Is output to the AC polarity determination unit 25. The AC polarity determination unit 25 determines the current polarity of the AC power supply Vac based on the data input from the AC voltage AD conversion unit 24, and as a result, a signal designating either positive or negative polarity is displayed as PFC. Is output to the PWM output control unit 28.

  The PFC PWM output control unit 28 performs a boost operation by the switching operation of the first switch element Q1 based on the signal input from the AC polarity determination unit 25 (drive period of the first switch element Q1). And a period for executing the step-up operation by the switching operation of the second switch element Q2 (drive period of the second switch element Q2), and a command signal for outputting the corresponding drive pulse is sent to the drive circuit 1 And 2 (29, 30).

  In the power factor correction circuit 2, as shown in FIG. 3, the positive half cycle period is the driving period of the first switch element Q1, and the negative half cycle period is the driving period of the second switch element Q2. That is, in the positive half cycle period, a drive pulse corresponding to a predetermined on-time and cycle described later is output from the drive circuit 1 (29) to the first switch element Q1, and the power factor improvement circuit 2 It functions as a booster circuit having the first reactor L1, the first switch element Q1, and the first rectifier element D1 as operation units. During this time, the output of the drive pulse from the drive circuit 2 (30) is stopped (fixed to High level), and the second switch element Q2 is fixed to the ON state. As a result, a current return path is formed between the source and drain of the second switch element Q2.

In the negative half cycle period, a drive pulse corresponding to a predetermined on-time and cycle described later is output from the drive circuit 2 (30) to the second switch element Q2, and the power factor improvement circuit 2 The second reactor L2, the second switching element Q2, and the second rectifying element D2 function as a booster circuit having an operation unit (hereinafter referred to as a second operation unit). During this time, the output of the drive pulse from the drive circuit 1 (29) is stopped (fixed to the High level), and the first switch element Q1 is fixed to the ON state. As a result, a current return path is formed between the source and drain of the first switch element Q1.

  Here, the switch element control circuit 10 has an ON time and a period of the switching operation corresponding to the drive pulses output from the drive circuits 1 and 2 (29, 30) to the first and second switch elements Q1 and Q2. (ON time + OFF time) is controlled as follows.

In the switch element control circuit 10, the output signal from the PFC voltage detection circuit 9 is input to the PFC voltage AD conversion unit 21 and A / D converted, and the digital data corresponding to the PFC voltage obtained thereby is the duty calculation unit. 22 is output. The duty calculator 22 derives the on-time in one switching operation from the error between the data input from the PFC voltage AD converter 21 and the data corresponding to the preset target voltage by using the PID calculation. Then, the data specifying the derived on-time is output to the duty limiter unit 23.

The duty limiter 23 determines whether or not the on-time derived by the duty calculator 22 is within a predetermined range. If the on-time is within the range, the on-time input from the duty calculator 22 is determined. Is directly output to the PFC PWM output control unit 28. Further, when the on time derived by the duty calculator 22 is larger than the upper limit value of the above range and when the on time is smaller than the lower limit value of the above range, the data specifying the on time are respectively The replaced data is replaced with the upper limit value and the lower limit value, and the replaced data is output to the PFC PWM output control unit 28.

  Further, in the switching element control circuit 10, the output signal from the L1 current detection circuit 6 is input to the comparator 1 (26), and in the comparator 1 (26), the value corresponds to zero current. It is determined whether or not. When the output signal from the L1 current detection circuit 6 corresponds to zero current, the comparator 1 (26) uses a signal indicating that zero current has been detected (hereinafter also referred to as an ON signal) for PFC. Output to the PWM output control unit 28. That is, the comparator 1 (26) detects information (first timing information) that the value corresponds to zero current from the output signal of the L1 current detection circuit 6, and this information will be described later. And used to determine the period of the first switch element Q1.

Similarly, the output signal from the L2 current detection circuit 7 is input to the comparator 2 (27), and the comparator 2 (27) determines whether or not the value corresponds to zero current. . When the output signal from the L2 current detection circuit 7 corresponds to zero current, the comparator 2 (27) outputs the ON signal to the PFC PWM output control unit 28. That is, the comparator 2 (27) detects the first timing information that the value corresponds to zero current from the output signal from the L2 current detection circuit 7.

The control of the switching operation during the drive period of the first switch element Q1 by the PFC PWM output control unit 28 is as follows.
The PFC PWM output control unit 28 uses the on-time input from the duty limiter unit 23 to generate a command signal designating a drive pulse corresponding to the on-time, and outputs the command signal to the drive circuit 1 (29). When a corresponding drive pulse is output from the drive circuit 1 (29) and the first switch element Q1 is turned on, a current starts to flow from the AC power supply Vac to the first switch element Q1 via the first reactor L1. As shown in FIG. 4, the current value detected by the L1 current detection circuit 6 increases.

Thereafter, after the on-time Rdon determined as described above has elapsed, when the first switch element Q1 is turned off according to the drive pulse output from the drive circuit 1 (29), the first reactor L1 and the first reactor L1 and the second As the current flows so as to charge the smoothing capacitor C1 through one rectifying element D1, and the energy stored in the first reactor L1 is discharged when the first switch element Q1 is turned on, the L1 current detection circuit 6 The current value detected by the value decreases and becomes zero when the discharge is completed.

When the ON signal corresponding to the zero current is input from the comparator 1 (26), the PFC PWM output control unit 28 uses the latest on-time input from the duty limiter unit 23 at that time. Then, a command signal corresponding to the next drive pulse is output to the drive circuit 1 (29), and the first switch element Q1 is turned on according to the drive pulse output from the drive circuit 1 (29). As a result, the off time (and hence the period t of the switching operation) in the switching operation immediately before the first switch element Q1 is determined, and thereafter this control is repeated in the drive period of the first switch element Q1.

  Note that, during the drive period of the first switch element Q1, for the drive circuit 2 (30), the output of the drive pulse is stopped from the PFC PWM output control unit 28 and the second switch element Q2 is turned on. The command signal for fixing to is output.

Here, the control of the switching operation in the drive period of the second switch element Q2 of the PFC PWM output control unit 28 is the same as the control of the switching operation in the drive period of the first switch element Q1 described above. In the above description, the first switch element Q1, the first reactor L1, the first rectifier element D1, the L1 current detection circuit 6, the comparator 1 (26), the drive circuit 1 (29), and the drive circuit 2 are provided. (30), the second switch element Q2, the second reactor L2, the second rectifier element D2, the L2 current detection circuit 7, the comparator 2 (27), the drive circuit 2 (30), and the drive circuit 1 respectively. By replacing with (29), the description is omitted.

Further, the switching power supply device 1 is preset with a maximum cycle allowed in the switching operation of the first and second switch elements Q1 and Q2, and the switch element control circuit 10 measures the maximum cycle. The PWM timer is provided. Then, the PFC PWM output control unit 28, when an ON signal corresponding to zero current is not input from the comparator 1 (26) until the maximum period elapses from the time point when one drive pulse is output. When the maximum period is reached, the command signal corresponding to the next drive pulse is output to the drive circuit 1 (29) using the latest on-time input from the duty limiter unit 23.

For example, the PWM timer is configured by a so-called free-run counter whose count value is counted up in accordance with a clock signal (not shown) input to the switch element control circuit 10, and a preset count value The maximum period may be set according to the time required to count up from the minimum value Cmin to the maximum value Cmax.

In this case, during the drive period of the first switch element Q1, the PFC PWM output controller 28 receives an ON signal corresponding to zero current from the comparator 1 (26) as shown in FIG. Then, the count value of the PWM timer is reset to the minimum value Cmin (timer clear), and the count-up is started from that point (timer set). In the switching operation of any of the first switch elements Q1, when the count value of the PWM timer reaches the maximum value Cmax without receiving the ON signal from the comparator 1 (26), the PFC The PWM output control unit 28 clears and sets the PWM timer, and at that time, outputs a command signal corresponding to the next drive pulse to the drive circuit 1 (29). Thereby, the cycle of the immediately preceding switching operation is forcibly set to the maximum cycle tmax. The PWM timer operates in the same manner even during the drive period of the second switch element Q2.

  The switch element control circuit 10 performs a control procedure executed by the PFC PWM output control unit 28 by generating an ON signal in the comparator 1 (26) and generating an ON signal in the comparator 2 (27). It is configured to interrupt, and the procedures for clearing and setting the PWM timer and shifting to the next drive pulse output (if necessary) are handled by the respective interrupt handlers. Also good.

  As described above, the switching control unit 5 determines the ON time in the switching operation of the first and second switch elements Q1 and Q2 according to the error between the target voltage of the PFC voltage and the detection voltage. The power factor correction circuit 2 is subjected to PWM control so that is a predetermined target voltage. Further, the switching control unit 5 turns on the switching operation of the first and second switching elements Q1 and Q2 after the input current flowing through the first and second reactors L1 and L2 becomes zero after the turn-off. Since the control is performed in a so-called critical mode, the off time of each switching operation is the target voltage of the PFC voltage, the instantaneous value of the input AC power supply Vac voltage, and the first and second reactors L1 and L2. It is determined according to the inductance, power supplied to the load circuit 3, and the like, and the cycle of the switching operation (switching frequency) also changes according to these conditions.

  Here, functions of the third to sixth rectifying elements D3, D4, D5, and D6 in the power factor correction circuit 2 will be described as follows. In the power factor correction circuit 2, the third and fourth rectifier elements D3 and D4 are connected to the output ground of the power factor correction circuit (one end of the smoothing capacitor C1 on the side connected to the first and second switch elements Q1 and Q2). ) And the both ends of the AC power supply Vac are connected, and both ends of the AC power supply Vac are not floated from the output ground. Therefore, the AC voltage detection circuit 8 can be configured by a simple circuit that does not require an insulating means or the like. The fifth and sixth rectifying elements D5 and D6 are smoothed from the AC power supply Vac immediately after the power factor correction circuit 2 is started (before the switching operations of the first and second switch elements Q1 and Q2 are started). A path for charging the capacitor C1 is formed. In addition, the power factor correction circuit 2 includes the third to sixth rectifying elements D3, D4, D5, and D6, thereby suppressing ringing generated in the first and second reactors L1 and L2, thereby EMI noise can be reduced.

  In the switching power supply 1, the PFC PWM output control unit 28 of the switching control unit 5 is the first switch element in the off state in the critical mode control of the switching operation of the first and second switch elements Q1 and Q2. Q1 (or second switch element Q2) may be turned on immediately after an ON signal corresponding to zero current is input from comparator 1 (26) (or comparator 2 (27)). Alternatively, after the ON signal corresponding to zero current is input from the comparator 1 (26) (or the comparator 2 (27)), the parasitic capacitance (or the first capacitor L1 and the first switching element Q1) (or , By the voltage resonance between the second reactor L2 and the parasitic capacitance of the second switch element Q2, the first switch element Q1 (or the second switch element Q2) Rain - Wait for the source voltage drops to a minimum value, thereby turning on the first switching element Q1 at the time (the second switch element Q2), it may be configured to perform so-called quasi-resonant control.

  Furthermore, the switching power supply device 1 is not limited by the configurations of the L1 current detection circuit 6 and the L2 current detection circuit 7, and the input current flowing from the AC power supply Vac through the first reactor L1 and the second reactor L2 is zero current. In such a case, any appropriate circuit can be used as long as the corresponding signal can be output. For example, the L1 current detection circuit 6 and the L2 current detection circuit 7 may be configured using a current transformer, or may share two magnetic cores with each of the first reactor L1 and the second reactor L2. You may comprise using a next winding.

Next, an example of an abnormality determination procedure in the switching power supply device 1 that is a feature of the switching power supply device and the control method thereof according to the present invention will be described with reference to FIG.
In this example, the switch element control circuit 10 includes an abnormality determination timer 1 and an abnormality determination timer 2 in addition to the PWM timer described above. In addition, it is determined that an abnormality has occurred in the switching power supply device 1 by measuring a first period for determining an abnormality related to the cycle of the switching operation of the second switch elements Q1 and Q2.

  Here, the abnormality determination timer 1 and the abnormality determination timer 2 are so-called free registers whose count values are counted up in accordance with a clock signal (not shown) input to the switch element control circuit 10 as in the PWM timer. It may be constituted by a run counter, and the first period may be set according to a time required for counting up from a preset minimum value to a maximum value.

  In the abnormality determination procedure shown in FIG. 5, first, whether or not an ON signal is generated in the comparator 1 (26) (that is, whether or not a value corresponding to zero current is detected from the output signal of the L1 current detection circuit 6). Is determined (step S1). If it is determined that the error has occurred (Yes), the PFC PWM output control unit 28 resets the count value of the abnormality determination timer 1 to the minimum value (timer clear), and starts counting up from that point. Next, it is determined whether or not the abnormality determination timer 1 has expired (whether or not the count value has reached the maximum value) (step S4). On the other hand, when it is determined in step S1 that no ON signal is generated in the comparator 1 (26) (No), the control directly proceeds to step S4.

If it is determined in step S4 that the abnormality determination timer 1 has not expired (No), the count value of the abnormality determination timer 1 is held (that is, in a state in which the time measurement from the immediately preceding timer set is continued). (Step S5), the control proceeds to Step S6.
In step S6, it is determined whether or not an ON signal is generated in the comparator 2 (27) (that is, whether or not a value corresponding to zero current is detected from the output signal from the L2 current detection circuit 7). . If it occurs (Yes), the PFC PWM output control unit 28 resets the count value of the abnormality determination timer 2 to the minimum value (timer clear), and starts counting up from that point (timer set) Then, it is determined whether or not the abnormality determination timer 2 has expired (whether or not the count value has reached the maximum value) (step S9). On the other hand, if it is determined in step S6 that no ON signal is generated in the comparator 2 (27) (No), the control directly proceeds to step S9.

  If it is determined in step S9 that the abnormality determination timer 2 has not expired (No), the count value of the abnormality determination timer 2 is held (that is, in a state in which the time measurement from the immediately preceding timer set is continued). (Step S10), the control returns to Step S1.

  Further, when it is determined in step S4 that the abnormality determination timer 1 has expired (Yes) and in step S10, it is determined that the abnormality determination timer 2 has expired (Yes), an abnormality has occurred. The PFC PWM output control unit 28 performs the switching operation of the first and second switch elements Q1 and Q2 on the drive circuit 1 (29) and the drive circuit 2 (30) (preferably in an off state). In response to the command signal, the drive circuit 1 (29) and the drive circuit 2 (30) stop outputting the drive pulse (in other words, the first and second switch elements Q1). , Q2 is preferably stopped in the off state) (step S11).

  According to the abnormality determination procedure shown in FIG. 5, during the repetition of steps S1 to S10, the abnormality determination timer 1 is set last, and then the abnormality determination is performed without generating the ON signal of the comparator 1 (26). When either the event that the timer 1 expires or the event that the abnormality determination timer 2 expires without the ON signal of the comparator 2 (27) occurring after the abnormality determination timer 2 is set last Therefore, it is determined that an abnormality has occurred, and the protection operation of stopping the switching operation of the first and second switch elements Q1 and Q2 is executed.

The abnormality determination procedure shown in FIG. 5 uses the abnormality determination timer 1 and the abnormality determination timer 2 as described above, and information indicating that the value corresponds to zero current from the output signal of the L1 current detection circuit 6. That either one of the undetected state and the state in which the information that the value corresponds to zero current is not detected from the output signal of the L2 current detection circuit 7 has continued beyond the first period. It is to detect.

The state in which the information that the value corresponds to zero current is not detected from the output signal of the L1 current detection circuit 6 continues for a long period of time indicates that the first reactor L1, the first switch element Q1, And there is a high possibility that some abnormality (for example, operation stop of the first switch element Q1) has occurred in the operation unit (and other circuit system for operating this operation unit) composed of the first rectifier element D1. In addition, the fact that the information that the value corresponds to zero current is not detected from the output signal of the L2 current detection circuit 7 continues for a long period of time indicates that the second reactor L1 and the second switch element Q2 , And the second rectifying element D2 (and other circuit system for operating the operation unit), there is some abnormality (for example, the second switch element). This means that there is a high possibility that the operation of the child Q2 has stopped.

Therefore, in the switching power supply device 1, the first period for determining the abnormality is necessary to distinguish the occurrence of such an abnormality from the normal operation, and the abnormality of the device is detected as quickly as possible. It is preferable that the period length is as long as possible. However, in the power factor correction circuit 2, even when both operation units are operating normally, the L2 current detection circuit 7 normally performs zero during the drive period (positive half cycle period) of the first switch element Q1. No current is detected, and since the zero current is not detected by the L1 current detection circuit 6 during the driving period (negative half cycle period) of the second switch element Q2, the first period for abnormality determination is It is necessary to set the length to be longer than at least a half cycle of normal operation of the AC power supply Vac.
For example, when the first period is regarded as “half cycle of normal operation of AC power supply Vac” + “substantial abnormality determination period”, “substantial abnormality determination period” is defined as half cycle of AC power supply Vac. The first period may be longer than one cycle of the AC power supply Vac.

According to the switching power supply device 1 in which the abnormality determination procedure shown in FIG. 5 is implemented and its control method, only one of the two operation units (and other circuit systems for operating the operation unit) described above is used. When an abnormality occurs, the operation is stopped, while the other operation is detected, and the protection operation can be executed at this stage. As a result, the state where the output control is concentrated only on one of the operation units of the power factor correction circuit 2 continues for a long period of time, so that the apparatus suffers serious damage such as overheating of the apparatus, and consequently burning of the circuit elements. And the device can be safely stopped.

  The abnormality determination procedure described above protects a normal circuit system for critical mode PWM control of the power factor correction circuit 2 such as the switching control unit 5 including the detection unit 4 and the switch element control circuit 10. Since it can be executed by extending the control procedure of the normal operation executed by the switch element control circuit 10 without separately providing a detection circuit and / or a protection circuit for operation, the complexity and cost of the device are increased. It is possible to detect the occurrence of an abnormality in the switching power supply device 1 and execute an appropriate protection operation to ensure the safety of the device.

  Further, in the abnormality determination procedure shown in FIG. 5, after the abnormality determination timer 1 is finally set, the abnormality determination timer 1 expires without the ON signal of the comparator 1 (26) being generated, and finally the abnormality is detected. After the determination timer 2 is set, it is determined that an abnormality has occurred when any one of the events that cause the abnormality determination timer 2 to expire without generating the ON signal of the comparator 2 (27) occurs. However, the abnormality determination procedure shown in FIG. 5 is determined so as to determine that an abnormality has occurred when both of these events occur (for example, in the AND condition of the determination of Yes in step S4 and the determination of Yes in step S9). It is easy to change (to perform step S11).

Even in this case, the switching power supply device 1 and its control method can at least generate an abnormality in the switching power supply device 1 without making the normal circuit system for performing the critical mode PWM control of the power factor correction circuit 2 double. This is advantageous in that it can detect and execute an appropriate protective action to ensure the safety of the device.

The abnormality determination procedure shown in FIG. 5 is described by extracting only the part related to abnormality determination from the entire control procedure executed by the switch element control circuit 10, and the abnormality determination procedure is the control procedure. It is executed at any appropriate point in time. Further, at this time, any two steps necessary for normal operation are executed between any two steps described as a continuous procedure (including the return from step S10 to S1). There may be.

  Furthermore, in the flowchart shown in FIG. 5, the abnormality determination procedure is shown as a series of steps executed in order from step S <b> 1. However, in the abnormality determination procedure executed by the switch element control circuit 10, the comparator 1 (26) The generation of the ON signal and the generation of the ON signal of the comparator 2 (27) are detected by the PFC PWM output control unit 28 by interruption, and then the abnormality determination timer 1 is cleared and set, and the abnormality determination timer 2 The procedure for clearing and setting may be processed by each interrupt handler in the same manner as for clearing and setting the PWM timer.

  Here, the abnormality determination procedure shown in FIG. 5 effectively prevents the output control from being concentrated on the other operation unit by stopping one of the two operation units constituting the power factor correction circuit 2. It was something to detect. However, in the power factor correction circuit 2, when the output control is concentrated only on one of the operation units, the waveform of the input AC power supply Vac itself and the AC power supply Vac are detected in the switching power supply device 1, and the polarity is determined. A control system for determining and setting the first drive period and the second drive period (for example, AC voltage detection circuit 8, AC voltage conversion unit 24, AC polarity determination unit 25, PFC PWM output control unit 28) One or both of the first drive period (actual positive half-cycle period or a period set as a positive half-cycle period by the control system) and the second drive period (actual negative half-cycle period). This can also occur if the ratio of the lengths of the half-cycle period or the period set as the negative half-cycle period by the control system) deviates significantly from 50%.

  Next, with reference to FIG. 6, an example of an abnormality determination procedure for dealing with such an abnormality in the switching power supply device 1 will be described. In this case, the switch element control circuit 10 includes an abnormality determination timer 3, and by measuring the second period for abnormality determination related to polarity reversal of the AC power supply Vac by the abnormality determination timer 3, It is determined that an abnormality has occurred in the switching power supply device 1.

As with the PWM timer, the abnormality determination timer 1 and the abnormality determination timer 2, the abnormality determination timer 3 counts up its count value according to a clock signal (not shown) input to the switch element control circuit 10. The so-called free-run counter may be used, and the second period may be set according to the time required to count up from a preset minimum value to a maximum value.

  In the abnormality determination procedure shown in FIG. 6, the PFC PWM output control unit 28 first determines whether or not the polarity inversion of the AC power supply Vac has occurred (step S101). This determination is made, for example, by comparing the current polarity of the AC power supply Vac with the previous polarity based on a signal input from the AC polarity determination unit 25 and changing from positive to negative or from negative to positive. It is executed by determining whether or not there has been. In this case, the switching element control circuit 10 passes through the AC voltage conversion unit 24 and the AC polarity determination unit 25, and by this determination by the PFC PWM output control unit 28, from the output signal of the AC voltage detection circuit 8, the AC power supply Vac Information (second timing information) corresponding to the switching time between the drive period of the first switch element Q1 and the drive period of the second switch element Q2 that the polarity is inverted is detected.

  If it is determined in step S101 that polarity reversal has occurred (Yes), the PFC PWM output control unit 28 resets the count value of the abnormality determination timer 3 to the minimum value (timer clear), and from that time point Counting up is started (timer set), and then it is determined whether or not the abnormality determination timer 3 has expired (whether or not the count value has reached the maximum value) (step S104). On the other hand, if it is determined in step S101 that polarity reversal has not occurred (No), the control directly proceeds to step S104.

  If it is determined in step S104 that the abnormality determination timer 3 has not expired (No), the count value of the abnormality determination timer 3 is held (that is, in a state in which the time measurement from the immediately preceding timer set is continued). (Step S105), the control returns to Step S101.

  If it is determined in step S104 that the abnormality determination timer 3 has expired (Yes), it is determined that an abnormality has occurred, and the PFC PWM output control unit 28 determines that the drive circuit 1 (29) and the drive circuit 2 (30), a command signal for stopping the switching operation of the first and second switch elements Q1 and Q2 (preferably in an off state) is output, and the drive circuit 1 (29) and the drive circuit 2 ( 30) stops the output of the drive pulse according to this command signal (in other words, the switching operation of the first and second switch elements Q1 and Q2 is preferably stopped in the off state) (step S106).

  According to the abnormality determination procedure shown in FIG. 6, during the repetition of the steps S101 to S105, after the abnormality determination timer 3 is set lastly, the abnormality determination timer 3 does not generate the polarity determination of the AC power supply Vac. When an event that expires occurs, it is determined that an abnormality has occurred, and a protection operation is performed in which the switching operation of the first and second switch elements Q1 and Q2 is stopped.

  In the abnormality determination procedure shown in FIG. 6, the abnormality determination timer 3 is used in the second state in which information indicating that the polarity inversion of the AC power supply Vac has occurred is not detected from the output signal of the AC voltage detection circuit 8. It detects that it continued beyond this period.

  In this abnormality determination procedure, the second period for abnormality determination is the half cycle of normal operation of the AC power supply Vac (that is, the polarity inversion of the AC power supply Vac in the normal operation of the AC power supply Vac and the switching power supply device 1). And a period longer than the time interval at which the occurrence is detected), the waveform of the input AC power supply Vac itself as described above and the AC power supply Vac in the switching power supply 1 Control system (for example, AC voltage detection circuit 8, AC voltage conversion unit 24, AC polarity determination unit 25, PFC) for determining the polarity and setting the first drive period and the second drive period When an abnormality occurs in one or both of the PWM output control unit 28), the abnormality can be detected.

Therefore, according to the switching power supply 1 in which the abnormality determination procedure shown in FIG. 6 is implemented and the control method thereof, one of the drive period of the first switch element Q1 and the drive period of the second switch element Q2 Is set to have a longer period than the other drive period, thereby including a switch element (first switch element Q1 or second switch element Q2) having a longer drive period. The state where the output control is concentrated on the operation unit continues for a long period of time, and as a result, the device is subject to serious damage such as overheating of the device and consequently burnout of the circuit element, and the power factor correction circuit 2 is subjected to critical mode PWM control. Therefore, it is possible to prevent the normal circuit system from being doubled and to stop the apparatus safely.

Note that the abnormality determination procedure shown in FIG. 6 is also described by extracting only the part related to abnormality determination from the entire control procedure executed by the switch element control circuit 10, similarly to the abnormality determination procedure shown in FIG. 5. The abnormality determination procedure is executed at any appropriate time in the entire control procedure. Further, at this time, any two steps necessary for normal operation are executed between any two steps described as a continuous procedure (including the return from step S105 to S101). There may be.

  Here, only the abnormality determination procedure shown in FIG. 5 may be implemented in the switching power supply device 1 and its control method, or only the abnormality determination procedure shown in FIG. 6 is implemented. Alternatively, both the abnormality determination procedure shown in FIG. 5 and the abnormality determination procedure shown in FIG. 6 may be implemented.

  The representative embodiment of the present invention has been described above, but the present invention is not limited to the circuit configuration of the above embodiment, and various modifications can be made without departing from the spirit of the present invention. . For example, in the embodiment described above, the PWM timer and the abnormality determination timers 1 to 3 are provided in the switch element control circuit 10, but these timers are provided outside the switch element control circuit 10. Alternatively, a timer provided in the switch element control circuit 10 and a timer provided outside the switch element control circuit 10 may be mixed.

  In the switching power supply device 1, the power factor correction circuit 2 is not limited to that shown in FIG. 1, and includes two switch elements, a first switch element Q1 and a second switch element Q2, and an input voltage detection circuit. The drive periods of the first and second switch elements Q1 and Q2 are determined based on the input voltage detection signal output from 8, and output from the first and second input current detection circuits 6 and 7, respectively. Based on the input current detection signal, the switching operation cycles of the first and second switch elements Q1 and Q2 are determined, respectively, so that the switching control is performed so that the output voltage becomes a predetermined voltage. The present invention can be applied to a rate improvement circuit.

Further, in the switching power supply device 1, when the load circuit 3 includes a switching type DC-DC converter or DC-AC converter, the switching control unit 5 controls the switching operation of the switch elements included in these converters. It may have a function.

1: switching power supply device, 2: power factor correction circuit, 3: load circuit, 4: detection unit, 5: switching control unit, 6: L1 current detection circuit (first input current detection circuit), 7: L2 current detection Circuit (second input current detection circuit), 8: AC voltage detection circuit (input voltage detection circuit), 9: PFC voltage detection circuit, C1: smoothing capacitor, D1 to D6: first to sixth rectifier elements, L1 : First reactor, L2: second reactor, Q1: first switch element, Q2: second switch element, Vac: AC power supply

Claims (9)

A power factor correction circuit (2) having a first switch element (Q1) and a second switch element (Q2), and first and second inputs for detecting input currents from both ends of an AC power supply (Vac), respectively. The output voltage of the current detection circuit (6, 7), the input voltage detection circuit (8) for detecting the input voltage across the AC power supply (Vac), and the power factor correction circuit (2) is a predetermined voltage. And a switching control unit (5) for controlling the first and second switch elements (Q1, Q2). The switching control unit (5) is output from the input voltage detection circuit (8). The drive periods of the first and second switch elements (Q1, Q2) are determined based on the input voltage detection signal, and from the first and second input current detection circuits (6, 7). Output input current detection signal Based on, a switching power supply configured so as to determine the period of the switching operation of each of the first and second switching elements (Q1, Q2),
The switching control unit (5) includes an input current detection signal output from the first and second input current detection circuits (6, 7) and an input voltage detection signal output from the input voltage detection circuit (8). Based on one or both of the above, the occurrence of an abnormality in the switching power supply device is determined, and when it is determined that the abnormality has occurred, the switching operation of the first and second switch elements (Q1, Q2) is performed. A switching power supply device that is stopped. The power factor correction circuit (2) includes a smoothing capacitor (C1) connected in parallel to the load circuit (3), a first rectifier element (D1), and a first switch element (Q1). A second series circuit comprising a series circuit and a second rectifying element (D2) and a second switch element (Q2), wherein the first series circuit and the second series circuit are One end of the first rectifier element (D1) and one end of the second rectifier element (D2) side, and one end of the first switch element (Q1) side and the second switch element (Q2) side The smoothing capacitor (C1) is connected in parallel with each other at one end, and the first and second rectifying elements (D1, D2) are in a direction to charge the smoothing capacitor (C1). And the first rectifier element (D1). , The first reactor (L1) connected between the connection portion of the first switch element (Q1) and one end of the AC power source (Vac), the second rectifier element (D2), and the second A second reactor (L2) connected between the connecting portion of the switching element (Q2) and the other end of the AC power supply (Vac), the first switching element (Q1), and the second switch A third rectifier element (D3) connected between a connection portion of the element (Q2) and one end of the AC power supply (Vac) on the first reactor (L1) side; and the first switch element (Q1) ) And a second rectifying element (D4) connected between the connection part of the second switching element (Q2) and one end of the AC power supply (Vac) on the second reactor (L2) side, The switching power supply device according to claim 1, comprising: The switching control unit (5) determines a cycle of the switching operation of the first switch element (Q1) from an input current detection signal output from the first input current detection circuit (6). In order to determine the period of the switching operation of the second switch element (Q2) from the state where the first timing information is not detected and the input current detection signal output from the second input current detection circuit (7) The at least one of the states in which the first timing information is not detected continues to exceed a predetermined first period, and it is determined that an abnormality has occurred in the switching power supply device. 3. The switching power supply device according to 2. The switching power supply according to claim 3, wherein the first period is a period longer than one cycle of the AC power supply (Vac). The switching control unit (5) determines the driving period of the first switch element (Q1) and the second switch element (Q1) from the input voltage detection signal output from the input voltage detection circuit (8). It is determined that an abnormality has occurred in the switching power supply device when the state in which the second timing information corresponding to the switching point with the driving period is not detected continues beyond a predetermined second period. The switching power supply device according to any one of claims 1 to 4. 6. The switching power supply device according to claim 5, wherein the second period is a period longer than a half cycle of the AC power supply (Vac). A power factor correction circuit (2) having a first switch element (Q1) and a second switch element (Q2), and first and second inputs for detecting input currents from both ends of an AC power supply (Vac), respectively. The output voltage of the current detection circuit (6, 7), the input voltage detection circuit (8) for detecting the input voltage across the AC power supply (Vac), and the power factor correction circuit (2) is a predetermined voltage. And a switching control unit (5) for controlling the first and second switch elements (Q1, Q2). The switching control unit (5) is output from the input voltage detection circuit (8). The drive periods of the first and second switch elements (Q1, Q2) are determined based on the input voltage detection signal, and from the first and second input current detection circuits (6, 7). Output input current detection signal Based on, a respective control method for the switching power supply configured so as to determine the period of the switching operation of the first and second switching elements (Q1, Q2),
Based on one or both of the input current detection signal output from the first and second input current detection circuits (6, 7) and the input voltage detection signal output from the input voltage detection circuit (8). The step of determining the occurrence of an abnormality of the switching power supply device and the step of stopping the switching operation of the first and second switch elements (Q1, Q2) when it is determined that the abnormality has occurred. A control method for a switching power supply device. The step of determining the occurrence of an abnormality in the switching power supply device includes a period of a switching operation of the first switch element (Q1) from an input current detection signal output from the first input current detection circuit (6). The period of the switching operation of the second switch element (Q2) from the state where the first timing information for determination is not detected and the input current detection signal output from the second input current detection circuit (7) Determining that an abnormality of the switching power supply device has occurred when at least one of the states in which the first timing information for determining the first timing information is not detected is continued beyond a predetermined first period. The method of controlling a switching power supply device according to claim 7. The step of determining the occurrence of an abnormality in the switching power supply device includes the driving period of the first switch element (Q1) and the second switch from the input voltage detection signal output from the input voltage detection circuit (8). When the state in which the second timing information corresponding to the switching time with the driving period of the element (Q2) is not detected continues beyond the predetermined second period, it is determined that an abnormality has occurred in the switching power supply device. The method according to claim 7 or 8, further comprising a step.

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