JP2012151964A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device which can be used as a step-up PFC circuit and a booster circuit.SOLUTION: The power supply device comprises: a rectification circuit 11; a booster circuit 12; an error comparator 21; an oscillator 28; a first comparison signal generation circuit 26; a saw-tooth wave generation circuit 24; a second comparison signal generation circuit 27; and a PWM drive circuit 20 which outputs either a first drive signal for PFC step-up control or a second drive signal for step-up control based on an external input. The first drive signal for PFC step-up control drives a switching element M1 based on the output of the first comparison signal generation circuit 26 and the output of the oscillator 28, and the second drive signal for step-up control drives the switching element M1 based on the output of the second comparison signal generation circuit 27 and the output of the oscillator 28.

Description

  The present invention relates to a power supply apparatus that can be applied to both a case where power factor improvement by PFC (Power Factor Control) is required and a case where only boosting is performed in a booster circuit.

  In a conventional power supply device including a booster circuit, a device that performs PFC and a device that simply boosts exist as separate devices. For example, a power supply device that performs step-up PFC control has the configuration shown in FIG.

  Specifically, as shown in FIG. 8, the power supply device is a device in which a booster circuit 12 is connected to the output of a rectifier circuit 11 formed of a diode bridge that rectifies the AC power supply 10.

  A smoothing capacitor C1 is connected between the two output terminals of the power supply device, and the switching element M1 is connected to the control circuit 13. The control circuit 13 operates by receiving power supply from the step-down circuit 14 that steps down the output of the step-up circuit 12.

  On the other hand, a power supply device that performs boost control is specifically shown in FIG. This is a device in which a booster circuit 12 is connected to the output of a rectifier circuit 11 composed of a diode bridge that rectifies the AC power supply 10.

  A smoothing capacitor C1 is connected between the two output terminals of the power supply device, and the switching element M1 is connected to the control circuit 15. The control circuit 15 operates by receiving power supply from the step-down circuit 14 that steps down the output of the step-up circuit 12.

  The power supply device that performs the boost PFC control is described in, for example, Patent Document 1, and the power supply device that performs only the boost control and does not perform the PFC control is described in Patent Document 2. As described above, there is a conventional device that does not use the same power supply device for different control. In addition, whether to use the boosting PFC circuit or the boosting circuit depends on whether the power used is over 25 W or 25 W or less, and the same power supply device is used depending on the amount of power used. It is desirable that it can be used by switching.

JP 2009-177777 A JP 2010-3631 A

  The present invention has been made in view of the current state of the power supply apparatus as described above, and its purpose is to be used as a booster PFC circuit and a booster circuit in a single apparatus, such as the amount of power used. It is an object of the present invention to provide a power supply apparatus that can be used by switching as necessary.

  A power supply apparatus according to the present invention includes a rectifier circuit that is connected to an AC power source and rectifies AC, and a series circuit of an inductor and a switching element. The series circuit is connected to an output side of the rectifier circuit, and A booster circuit that outputs a boosted voltage to a load side by switching, an error comparator that compares a voltage supplied to the load with a reference voltage, an oscillator that generates a pulse used for PWM driving the switching element, and the error A breakdown prevention current for the switching element is created based on the output of the comparator and the output of the rectifier circuit, and a comparison signal is generated by comparing the breakdown prevention current with the current flowing through the switching element of the booster circuit. The comparison signal generation circuit, the output of the error comparator and the output of the oscillator are used to prevent oscillation of the output voltage supplied to the load. And a sawtooth wave generating circuit for generating a sawtooth wave with a limit for preventing destruction of the switching element, and comparing the sawtooth wave with a current flowing through the switching element of the booster circuit to obtain a comparison signal. A second comparison signal generation circuit to be generated; a first drive signal for PFC / step-up control that drives the switching element based on an output of the first comparison signal generation circuit and an output of the oscillator; And a PWM drive circuit that outputs one of the second drive signals for boost control that drives the switching element based on the output of the comparison signal generation circuit and the output of the oscillator based on the external input. It is characterized by that.

  In the power supply device according to the present invention, the PWM drive circuit includes a driver for driving the switching element by first and second drive signals.

  The power supply device according to the present invention includes a series circuit of a resistor and a third switching element, the adjustment load circuit connected to the output terminal of the rectifier circuit, and the third switching element based on the output of the rectifier circuit And a load adjustment circuit for adjusting the load of the rectifier circuit by controlling the rectifier circuit.

  The power supply device according to the present invention is characterized in that a triac is used in the rectifier circuit and operates by outputting a second drive signal.

  A power supply apparatus according to the present invention includes a fourth switching element for controlling power supplied to a load, and a load power control circuit that drives the fourth switching element in accordance with a load control signal to control power It is characterized by comprising.

  In the power supply device according to the present invention, the booster circuit includes a first booster circuit including a series circuit of a first inductor and a first switching element, and a series circuit of a second inductor and a second switching element. The two booster circuits are constituted by circuits connected in parallel, and the first comparison signal generation circuit and the second comparison signal generation circuit have two channels corresponding to the first switching element and the second switching element. The PWM drive circuit outputs a first drive signal and a second drive signal corresponding to the first switching element and the second switching element, respectively.

  According to the present invention, either the first drive signal for PFC / boost control for driving the switching element or the second drive signal for boost control for driving the switching element is output based on the external input. Therefore, a single power supply device can be used as a booster type PFC circuit or a booster circuit, and can be used by appropriately switching according to the necessity of power consumption.

  Further, according to the present invention, since the error comparator and the oscillator are shared by the boosting PFC circuit and the boosting circuit, the parts used are smaller than when the boosting PFC circuit and the boosting circuit are separately prepared. Reduced devices can be realized.

The circuit block diagram which shows the structure of the power supply device which concerns on the 1st Embodiment of this invention. The wave form diagram for demonstrating operation | movement of the principal part in the power supply device which concerns on the 1st Embodiment of this invention. The wave form diagram for demonstrating operation | movement of the principal part in the power supply device which concerns on the 1st Embodiment of this invention. The circuit block diagram which shows the structure of the power supply device which concerns on the 2nd Embodiment of this invention. The circuit block diagram which shows the structure of the control circuit in the power supply device which concerns on the 2nd Embodiment of this invention. The circuit block diagram which shows the structure of the power supply device which concerns on the 3rd Embodiment of this invention. The circuit block diagram which shows the structure of the control circuit in the power supply device which concerns on the 3rd Embodiment of this invention. The circuit block diagram which shows the structure of the power supply device which performs the conventional pressure | voltage rise PFC control. The circuit block diagram which shows the structure of the power supply device which performs the conventional pressure | voltage rise control.

  Hereinafter, a power supply device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In each figure, the same components are denoted by the same reference numerals and redundant description is omitted. FIG. 1 shows the configuration of the power supply device according to the first embodiment. The power supply apparatus according to the embodiment is an apparatus in which a booster circuit 12 is connected to an output of a rectifier circuit 11 formed of a diode bridge that rectifies an AC power supply 10. The booster circuit 12 is connected to the output of the rectifier circuit 11 by a series circuit of a switching element M1 composed of an inductor L1 and, for example, a MOSFET, and a diode connected in series to the inductor L1 along a path from the inductor L1 to one output terminal. D1 is a connected circuit.

  A smoothing capacitor C1 is connected between the two output terminals of the power supply device, and the switching element M1 is connected to the control circuit 2. The control circuit 2 operates by receiving power supply from the step-down circuit 14 that steps down the output of the step-up circuit 12.

  The control circuit 2 includes an error comparator 21, a first limiter 22, a second limiter 23, a sawtooth wave generation circuit 24, an amplifier 25, a first comparator 26, a second comparator 27, an oscillator 28, and a PWM drive circuit 20. A driver 29 is provided.

  The error comparator 21 compares the output voltage divided by the series circuit of the resistors R2 and R3 with a predetermined threshold voltage REF and outputs an error voltage. In addition, the input voltage of the booster circuit 12 is divided by a series circuit of resistors R 4 and R 5 and is supplied to the first limiter 22. The first limiter 22 is supplied with the divided potential by the resistors R4 and R5 and the error voltage by the error comparator 21, and the first limiter 22 is supplied by the divided voltage potential by the resistors R4 and R5 and the error comparator 21. The error voltage is combined and applied to the first comparator 26 as a breakdown prevention reference potential for the switching element M1. The reference potential for preventing destruction of the switching element M1 applied to the first comparator 26 is a sine wave half-wave waveform as indicated by Va in FIG.

  The other input terminal of the first comparator 26 is supplied with the current flowing in the switching element M1 from the connection point of the switching element M1 and the resistor R1 after being amplified by the amplifier 25. Comparison is made as shown in FIG. 2B, and the comparison result is sent to the PWM drive circuit 20 and controlled in the continuous current type (CCM) mode. As described above, the first limiter 22, the amplifier 25, and the first comparator 26 create the breakdown prevention current of the switching element M 1 based on the output of the error comparator 21 and the output of the rectifier circuit 11, and It functions as a first comparison signal generation circuit that compares the current flowing through the switching element M1 of the circuit 12 to generate a comparison signal.

  The error voltage output from the error comparator 21 is combined with the output of the second limiter 23, which is a breakdown preventing voltage of the switching element M1, and sent to the sawtooth wave generation circuit 24. The sawtooth wave generation circuit 24 In order to prevent oscillation of the output OUT of the device, a sawtooth voltage is applied to the second comparator 27 as a reference voltage. The sawtooth wave voltage is a voltage Vb shown in FIG. 3A, which rises at the pulse timing given from the oscillator 28 and thereafter has a gentle slope.

  The other input terminal of the second comparator 27 is supplied with the current flowing through the switching element M1 from the connection point of the switching element M1 and the resistor R1 after being amplified by the amplifier 25. The comparison is made as shown in FIG. 3B and the comparison result is sent to the PWM drive circuit 20. As described above, the second comparator 27 is a second comparison signal generation circuit that generates a comparison signal by comparing the sawtooth wave generated by the sawtooth wave generation circuit 24 and the current flowing through the switching element M1 of the booster circuit 12. Function.

  The PWM drive circuit 20 has a mode terminal MODE, and a signal for switching between an operation as a PFC / boost circuit or an operation as a boost circuit is given to the mode terminal MODE from the outside. This signal can be output from a switch that can be switched manually, or can be output from, for example, a circuit that determines the input power and sends a signal corresponding to the magnitude of the power.

  The PWM drive circuit 20 switches the output based on the signal from the mode terminal MODE. When a signal indicating the operation as a PFC / boost circuit is given to the mode terminal MODE, the PWM drive circuit 20 outputs the output of the first comparator 26 and the output of the oscillator 28 as the first comparison signal generation circuit. The first drive signal for PFC / step-up control for driving the switching element M1 is output via the driver 29 based on the above.

  Further, when a signal indicating the operation as a booster circuit is given to the mode terminal MODE, the PWM drive circuit 20 outputs the output of the second comparator 27 and the output of the oscillator 28 as the second comparison signal generation circuit. And a second drive signal for boost control for driving the switching element M1 is output via the driver 29.

  When the output of the amplifier 25 exceeds the reference value Va shown in FIG. 2A, a signal for turning off the switching element M1 is output from the first comparator 26. When the output is below the reference value Va, Outputs a signal for turning on the switching element M1. Further, when the output of the amplifier 25 exceeds the reference value Vb shown in FIG. 3A, a signal for turning off the switching element M1 is output from the second comparator 27, and is below the reference value Vb. In this case, a signal for turning on the switching element M1 is output.

  In any mode, the control circuit 2 operates so that the voltage obtained by dividing the output voltage of the booster circuit 12 by the resistors R2 and R3 is equal to the predetermined threshold voltage REF given to the error comparator 21, The output setting voltage can be set by the ratio of the resistors R2 and R3 and the predetermined threshold voltage REF. For example, when the predetermined threshold voltage REF is 1V, the output setting voltage can be 400V by setting R2: R3 = 399: 1.

  As described above, according to this embodiment, it is possible to select either the PFC / boost control mode or the boost control mode, and the PFC / boost control power supply device and the boost control power supply device are simply combined. Compared to the case, it is possible to reduce the number of parts and circuits used, and it can be used flexibly regardless of the power used.

  FIG. 4 shows a power supply device according to the second embodiment. In the booster circuit 12A of this power supply device, a diode D2 is connected to the series circuit of the inductor L1 and the diode D1 in the booster circuit 12 of FIG. Further, a triac 16 is connected between the AC power supply 10 and the rectifier circuit 11 so that the switched AC is supplied to the rectifier circuit 11.

  An adjustment load circuit 17 is connected to the output side of the rectifier circuit 11. The adjustment load circuit 17 is constituted by a series circuit of a resistor R6 and a third switching element M2 constituted by a MOSFET.

  A series circuit of one or more LEDs 18 as a load, an inductor L2, a fourth switching element M3 constituted by a MOSFET, and a resistor R7 is connected to the output terminal of the apparatus. The step-down circuit 14 includes a MOSFET-M4, a resistor R8, a capacitor C2, and a Zener diode D5. Power is supplied from the step-down circuit 14 to the VIN terminal of the control circuit 2A.

  As shown in FIG. 5, the control circuit 2A has a configuration according to the control circuit 2 of the first embodiment, and operates as a PFC / boost circuit or operates as a boost circuit according to a signal applied to the mode terminal MODE. Can be controlled. In addition to the configuration of the control circuit 2, the control circuit 2A includes a driver 31 for the third switching element M2, a driver 32 for the fourth switching element M3, a PWM driver 33, and an AND gate 34.

  The PWM drive circuit 20A performs an operation according to the PWM drive circuit 20 of the first embodiment, and further uses the triac 16, so that the driver 31 corresponds to a case where the load on the booster circuit 12A or the control circuit 2A is light. The control signal is sent from the third switching element M2, the third switching element M2 is turned on, and the load is adjusted so that the triac 16 does not malfunction.

  Further, the voltage detected by the resistor is taken from FB_I, compared with the output value of the comparison value holding unit 39 by the comparator 38 via the amplifier 37, and the comparison result is supplied to the PWM drive circuit 20A, thereby flowing to the LED 18. Current detection is performed. The PWM drive circuit 20A detects the voltage by the resistor R7, obtains the current flowing through the LED 18, provides a PWM signal for controlling the operation period to the PWM driver 33 based on this, and controls the AND gate 34 to control the AND gate 34 by PWM. The drive signal of the fourth switching element M3 can be sent to control the dimming. A DC voltage can be applied to the comparison value holding unit 39 from the I_CON terminal, and a current flowing from the outside to the LED 18 can be set.

  In the PWM drive circuit 20A, the duty of the PWM signal output to the PWM driver 33 can be adjusted by applying a DC voltage to the PWM_REF terminal. The DC voltage is supplied from the comparison value holding unit 35 to the comparator 36, and the comparator 36 compares the output value of the comparison value holding unit 35 with the output of the oscillator 28 and supplies the comparison result to the PWM drive circuit 20A. The PWM drive circuit 20A controls the duty of the PWM signal output to the PWM driver 33 based on the comparison result.

  In addition, by directly inputting a PWM signal from the PWM_IN terminal to the PWM drive circuit 20A, the PWM drive circuit 20A outputs this PWM signal to the PWM driver 33 to perform PWM control of the fourth switching element M3.

  The control circuit 2A includes Vref that holds a predetermined threshold voltage REF supplied to the error comparator 21, and further includes a linear regulator LDO (Low Drop Out). The PWM drive circuit 20A includes an overvoltage protection circuit OVP and a low voltage malfunction prevention circuit UVLO.

  In the second embodiment shown in FIG. 4 in which the triac 16 is used for AC input, a mode for boosting control of the booster circuit 12A instead of PFC / boost control is selected by a signal at the MODE terminal. When the input voltage is controlled to be small by the triac 16, by using the boost control mode instead of the boost PFC control, the restriction due to the current limit becomes smaller than that in the PFC control. For this reason, in the power supply device of the second embodiment, the boosting capability is increased, and a larger output voltage can be obtained using a small input voltage.

  Thereby, when the triac 16 is used, the operable range of the voltage applied to the LED 18 with a small input voltage can be expanded. Further, when dimming is performed by a power supply device using the triac 16, the input voltage average value and the input voltage width are detected, and the output current value passed through the LED 18 and the operation period of the fourth switching element M3 (ON (Period) is generated to control the fourth switching element M3. These input voltage average values and input voltage widths can be used individually for dimming, or can be used in combination for dimming control. Even with the power supply device of this embodiment, it is possible to reduce the number of parts and circuits used compared to the case where the power supply device for PFC / boost control and the power supply device for boost control are simply combined. Can be used.

  FIG. 6 shows a power supply device according to the third embodiment. The booster circuit 12B of the power supply circuit includes a first booster circuit including a series circuit of a first inductor L1-1 and a first switching element M1-1, a second inductor L1-2, and a second switching element. The second booster circuit including the M1-2 series circuit is constituted by a circuit connected in parallel.

  A resistor R1-1 is connected between the switching element M1-1 and the ground, and a resistor R1-1 is connected between the switching element M1-2 and the ground. Furthermore, a diode D1-1 is connected between the inductor L1-1 and the output terminal, and a diode D1-2 is connected between the inductor L1-2 and the output terminal.

  The control circuit 2B used in the power supply device according to the third embodiment is configured as shown in FIG. That is, amplifiers 25-1 and 25-2 are provided to amplify a current flowing through the switching element M1 from a connection point between the switching element M1 and the resistor R1. The outputs of the amplifiers 25-1 and 25-2 are sent to the first comparators 26-1 and 26-2, respectively. The functions of the first comparators 26-1 and 26-2 are the same as those of the first comparator, and their outputs are given to the PWM drive circuit 20B.

  The PWM drive circuit 20B receives a signal indicating that the operation as a PFC / boost circuit is applied to the mode terminal MODE, and operates as a first comparison signal generation circuit to drive the switching elements M1-1 and M1-2. A first drive signal for boost control is output via the drivers 29-1 and 29-2. Further, the PWM drive circuit 20B, when a signal indicating the operation as a booster circuit is given to the mode terminal MODE, boost control for driving the switching elements M1-1 and M1-2 as a second comparison signal generation circuit. The second driving signal is output via the drivers 29-1 and 29-2.

  The PWM drive circuit 20B interleaves a signal output to the first switching element M1-1 via the driver 29-1 and a signal output to the second switching element M1-2 via the driver 29-2. Output alternately. Other configurations are the same as those of the power supply device according to the second embodiment.

  According to the power supply device according to the third embodiment having such a configuration, the number of components and circuits used can be reduced compared to the case where the power supply device for PFC / boost control and the power supply device for boost control are simply combined. It can be used flexibly regardless of the power used. In addition, since the booster circuit has a two-channel configuration with the first booster circuit and the second booster circuit, the ability to send power to the output side can be improved, compared to the power supply device according to the second embodiment. Therefore, it is suitable when large power is required. In addition, since the two-channel booster circuit is interleaved, current ripple can be reduced.

  The triac 16 used in the second embodiment and the third embodiment can control the output between 0 and 100% using a drive circuit (not shown). Here, when the output of the triac 16 is set to 100%, the function of the triac 16 is stopped. When the output of the triac 16 is set to 0%, the current from the triac 16 to the rectifier circuit 11 is reduced. Is not flowing.

  Normally, triacs are often used with low power. Therefore, when the output of the triac 16 is controlled to be less than 100%, a signal indicating that the operation as a booster circuit is given from the mode terminal MODE to boost the voltage. When operating as a circuit only and stopping the function of the triac 16 by setting the output of the triac 16 to 100%, a signal indicating the operation as a PFC / boost circuit is given from the mode terminal MODE, and the PFC / boost It can be operated as a circuit. Of course, when the output of the triac 16 is controlled to be less than 100%, a signal indicating the operation as the PFC / boost circuit may be given from the mode terminal MODE to operate as the PFC / boost circuit.

2, 2A, 2B Control circuit 10 AC power source 11 Rectifier circuit 12, 12A, 12B Booster circuit 14 Buck circuit 16 Triac 17 Adjustment load circuit 20, 20A, 20B Drive circuit 21 Error comparator 22, 23 Limiter 24 Sawtooth wave generation Circuits 26, 27, 28 Oscillator 35 Comparison value holding unit 36, 38 Comparator 39 Comparison value holding unit

Claims (6)

A rectifier circuit connected to an AC power source and rectifying the AC;
A booster circuit including a series circuit of an inductor and a switching element, the series circuit being connected to an output side of the rectifier circuit, and outputting a boosted voltage to a load side by switching of the switching element;
An error comparator that compares a voltage supplied to the load with a reference voltage;
An oscillator for generating a pulse used for PWM driving the switching element;
A breakdown prevention current for the switching element is created based on the output of the error comparator and the output of the rectifier circuit, and the comparison signal is generated by comparing the breakdown prevention current with the current flowing through the switching element of the booster circuit. A first comparison signal generation circuit;
Using the output of the error comparator and the output of the oscillator, the oscillation of the output voltage supplied to the load is prevented, and a sawtooth wave is generated that provides a limit for preventing the switching element from being destroyed. A wave generation circuit;
A second comparison signal generation circuit for generating a comparison signal by comparing the sawtooth wave and a current flowing through the switching element of the booster circuit;
A first drive signal for PFC / step-up control for driving the switching element based on an output of the first comparison signal generation circuit and an output of the oscillator, an output of the second comparison signal generation circuit, and the oscillator And a second drive signal for boost control that drives the switching element based on the output of the output, and a PWM drive circuit that outputs any of the second drive signals based on an external input.   The power supply apparatus according to claim 1, wherein the PWM drive circuit includes a driver that drives the switching element by first and second drive signals. An adjustment load circuit configured by a series circuit of a resistor and a third switching element and connected to the output terminal of the rectifier circuit;
The power supply device according to claim 1, further comprising: a load adjustment circuit configured to control a load of the rectifier circuit by controlling the third switching element based on an output of the rectifier circuit.   The power supply apparatus according to claim 3, wherein a triac is used for the rectifier circuit, and the second drive signal is output to operate. A fourth switching element for controlling the power supplied to the load;
The power supply device according to claim 3, further comprising: a load power control circuit that drives the fourth switching element in accordance with a load control signal to control power. In the booster circuit, a first booster circuit including a series circuit of a first inductor and a first switching element, and a second booster circuit including a series circuit of a second inductor and a second switching element are arranged in parallel. Consists of connected circuits,
The first comparison signal generation circuit and the second comparison signal generation circuit are provided in two channels corresponding to the first switching element and the second switching element,
6. The PWM drive circuit outputs a first drive signal and a second drive signal corresponding to the first switching element and the second switching element, respectively. The power supply device according to any one of the above.