JP2014230312A - Dc power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power supply device that implements a compact circuit and a low loss by reducing a surge voltage.SOLUTION: A series circuit of a primary side of a transformer 4 and a first switching element 5 is connected to a DC input power supply 3. A series circuit of a secondary side of the transformer 4 and a first diode 7 is connected to a junction of the primary side of the transformer 4 and the first switching element 5 via a capacitor 6. A second diode 8 is connected in parallel with the series circuit. A load 2 is connected to a junction of the capacitor 6 and the secondary side of the transformer 4 via a reactor 9. A control circuit 11 is provided for controlling the first switching element 5 to step up/down a voltage of the DC input power supply 3.

Description

  The present invention relates to a step-up / step-down type DC power supply device capable of boosting or stepping down a DC voltage and supplying a DC current to a load, and more particularly, to reducing the loss, size, and cost of the device.

  In an in-vehicle power supply in which both the input voltage and the load voltage change, a switching power supply having a converter capable of step-up / step-down is used. One of the buck-boost converters is a Cuk converter (see, for example, Patent Document 1). In the Cuk converter, the voltage applied to each element is the sum of the input voltage and the output voltage. It was difficult to avoid an increase in loss and an increase in cost.

  In order to solve this problem, a DC / DC conversion circuit and a load circuit that adjusts a direct current output of the DC / DC conversion circuit and supplies the load to a load are provided. The DC / DC conversion circuit includes a switching element and a switching element. A transformer in which the power supply voltage of the DC power supply is applied to the primary winding, a series circuit of the secondary winding of the transformer and the rectifier element, the DC power supply, the primary winding of the transformer, and the switching A power supply device is disclosed in which a secondary circuit of a transformer and a series circuit of rectifying elements are connected to a closed circuit composed of elements via a capacitor (see, for example, Patent Document 2).

US Pat. No. 4,184,197 (column 4 to column 6, FIG. 5) Japanese Patent No. 3687528 (paragraphs [0026] to [0031], FIG. 1)

  The invention disclosed in Patent Document 2 has a problem that a surge voltage due to transformer leakage inductance is not taken into consideration, so that an excessive voltage is applied to both ends of the switching element, the circuit loss increases, and the circuit becomes large. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a DC power supply device that can reduce a surge voltage and reduce the size and loss of a circuit. To do.

  In a first DC power supply device according to the present invention, a series circuit of a primary side of a transformer and a first switching element is connected to a DC input power source, and the primary side of the transformer and the first switching element are connected. A series circuit of the secondary side of the transformer and the first diode is connected to the point via a capacitor, and a second diode is connected in parallel to the series circuit of the secondary side of the transformer and the first diode. A control circuit for connecting a load to a connection point between the capacitor and the secondary side of the transformer via a reactor, controlling the first switching element to step up / down the voltage of the DC input power supply, and supplying the load to the load Is.

  In a second DC power supply device according to the present invention, a series circuit of a primary side of a transformer and a first switching element is connected to a DC input power source, and the primary side of the transformer and the first switching element are connected. A series circuit of the secondary side of the transformer and the second switching element is connected to the point via a capacitor, and a second diode is connected in parallel to the series circuit of the secondary side of the transformer and the second switching element. Connect the load to the connection point between the capacitor and the secondary side of the transformer via the reactor, and control the first and second switching elements to step up / down the voltage of the DC input power supply and supply it to the load A control circuit is provided.

  Since the first DC power supply device according to the present invention is configured as described above, it is possible to reduce the surge voltage and to reduce the size and loss of the circuit.

  Since the second DC power supply device according to the present invention is configured as described above, the surge voltage can be reduced, and the circuit can be reduced in size and loss.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which concerns on the DC power supply device of Embodiment 1 of this invention. It is operation | movement explanatory drawing which concerns on the DC power supply device of Embodiment 1 of this invention. It is operation | movement explanatory drawing of the switching element which concerns on the DC power supply device of Embodiment 1 of this invention. It is an example of a block diagram of the control circuit which concerns on the DC power supply device of Embodiment 1 of this invention. It is a block diagram which concerns on the DC power supply device of Embodiment 2 of this invention. It is a block diagram of the multi-output transformer which concerns on the DC power supply device of Embodiment 2 of this invention. It is a block diagram which concerns on the DC power supply device of Embodiment 3 of this invention. It is explanatory drawing of the gate signal which concerns on the DC power supply device of Embodiment 3 of this invention. It is a block diagram which concerns on the DC power supply device of Embodiment 4 of this invention. It is operation | movement explanatory drawing which concerns on the DC power supply device of Embodiment 4 of this invention. It is operation | movement explanatory drawing which concerns on the DC power supply device of Embodiment 4 of this invention.

Embodiment 1 FIG.
The first embodiment includes a series circuit of a primary side of a transformer connected to a DC input power source and a first switching element, a series circuit of a secondary side of the transformer and a first diode, A capacitor for connecting a series circuit of the secondary side of the transformer and the first diode to a connection point between the primary side and the first switching element, and a series circuit of the secondary side of the transformer and the first diode A second diode connected in parallel to the capacitor, a reactor connecting the load to the connection point between the capacitor and the secondary side of the transformer, and the first switching element to control the voltage of the DC input power source, The present invention relates to a DC power supply device that includes a control circuit that supplies power to a power source.

  Hereinafter, regarding the configuration, function, and operation of the first embodiment of the present invention, FIG. 1 is a configuration diagram of a DC power supply device, FIG. 2 is an operation explanatory diagram, FIG. 3 is an operation explanatory diagram of a switching element, and control. A description will be given based on FIG. 4 which is an example of a circuit configuration diagram.

  In the following description, after describing the configuration, function, and operation of the DC power supply device, a configuration example of the control circuit will be described.

First, the configuration of a system including a DC power supply device will be described with reference to FIG.
In FIG. 1, the entire system includes a DC power supply device 1 and a load 2 for supplying a desired DC voltage. The DC power supply device 1 includes a DC input power supply unit, a power supply main circuit unit, and a control unit as main units.

The DC input power supply unit corresponds to the DC input power supply 3.
Next, the power supply main circuit unit will be described. The power supply main circuit unit includes a transformer 4, a first switching element 5, a capacitor 6, a first diode 7, a second diode 8, a reactor 9, and an output capacitor 10.
A series circuit of a primary side winding 4 a of the transformer 4 and the first switching element 5 is connected to the DC input power source 3. The first end of the primary winding 4 a of the transformer 4 is connected to the positive electrode of the DC input power supply 3. The second end of the primary winding 4a of the transformer 4 is connected to the drain of the first switching element 5, and this connection point is referred to as point A.
A series circuit of the secondary winding 4 b of the transformer 4 and the first diode 7 is connected to the first switching element 5 in parallel via the capacitor 6. That is, the first end of the capacitor 6 is connected to the point A. The second end of the capacitor 6 is connected to the first end of the secondary winding 4b of the transformer 4, and this connection point is referred to as point B. The second end of the secondary winding 4b of the transformer 4 and the anode of the first diode 7 are connected.

A second diode 8 is connected in parallel to the series circuit of the secondary winding 4 b of the transformer 4 and the first diode 7. The anode of the second diode 8 is connected to the first end of the secondary winding 4 b of the transformer 4, that is, the point B.
An output capacitor 10 is connected in parallel to the series circuit of the secondary winding 4 b of the transformer 4 and the first diode 7, that is, the second diode 8, via the reactor 9. The first end of the reactor 9 is connected to point B. A connection point between the second end of the reactor 9 and the first end of the output capacitor 10 is referred to as a C point.
An output end of the power supply main circuit unit, that is, a first end and a second end of the output capacitor 10 are connected to the load 2.
The source of the first switching element 5, the cathode of the first diode 7, the cathode of the second diode 8, and the second end of the output capacitor 10 are connected to the negative electrode of the DC input power supply 3.
The DC power supply device 1 according to the first embodiment supplies the voltage (−Vout) to the load 2 by inverting the polarity with respect to the voltage (Vin) of the DC input power supply 3.

  Next, the control unit will be described. The control unit includes a control circuit 11 that generates a pulse signal for switching control of the first switching element 5, a first gate circuit 12, and an output detection circuit 13.

The control unit controls the first switching element to step up / down the voltage of the DC input power supply and supply it to the load. The operation of this control unit will be described in detail later, but the function of each circuit will be briefly described.
The control circuit 11 generates a pulse signal that controls the switching of the first switching element 5. The first gate circuit 12 receives a pulse signal from the control circuit 11 and outputs a gate signal to the gate of the first switching element 5. The output detection circuit 13 detects the output voltage and current to the load 2 necessary for controlling the first switching element 5 and outputs the detected output voltage and current to the control circuit 11.

Next, main components will be described.
The load 2 is assumed to be a multi-series connected LED or the like for a vehicle headlight.
The DC input power source 3 is a stable power source such as a constant voltage power source or a DC power source having a large voltage fluctuation such as an in-vehicle battery power source.

The first switching element 5 is a voltage-controlled self-extinguishing high-speed semiconductor element. Since the point A in FIG. 1 is a positive potential, an N-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or It is desirable to select an IGBT (Insulated Gate Bipolar Transistor).
In FIG. 1, the first switching element 5 is assumed to be an N-type MOSFET. If an IGBT is used, the drain is read as a collector and the source is read as an emitter.

The transformer 4 is obtained by winding two windings around a common iron core, adjusting the number of primary turns so as to obtain a necessary exciting inductance, and obtaining a desired boost ratio. The turn ratio n with the winding is determined.
The first end of the primary winding 4a of the transformer 4 and the first end of the secondary winding 4b of the transformer 4 connected in series to the first diode 7 are connected to the transformer 4 in FIG. The black circles shown are connected so as to have the same polarity.
In FIG. 1, the second end of the secondary winding 4 b of the transformer 4 is connected in series to the anode of the first diode 7. However, the connection order is changed to change the cathode of the first diode 7. And the first end of the secondary winding 4b of the transformer 4 may be connected in series.

The capacitor 6 sets the capacitor capacity so that the resonance frequency with the inductance value of the reactor 9 is sufficiently lower than the switching frequency of the first switching element 5. The resonance frequency due to the inductance of the capacitor 6 and the reactor 9 is preferably set to 1/5 or less of the switching frequency of the first switching element 5.
With such a setting, the resonance vibration generated in the output voltage Vout can be suppressed, and the circuit operation can be stabilized.
Since charging / discharging current flows through the capacitor 6 every time the first switching element 5 is switched, it is desirable to use an electrolytic capacitor having a low internal impedance, or a ceramic capacitor or a film capacitor. When such a capacitor is used, the loss is reduced and the circuit can be further downsized.

  A forward current flows through the first diode 7 when the first switching element 5 is off, and a reverse voltage is applied between the cathode and the anode when the first switching element 5 is on. Such a switching operation causes so-called diode recovery in the first diode 7 and increases loss. Therefore, it is desirable to use a diode having a low forward ON voltage and low diode recovery, such as a Schottky barrier diode or a fast recovery diode, as the first diode 7. When such a diode is used, the loss generated in the first diode 7 is reduced, and the circuit can be further downsized.

The second diode 8 is attached to suppress a surge voltage that is generated when the first switching element 5 is turned off. By configuring the capacitor 6 and the second diode 8 constituting the power supply main circuit section to be connected between the drain and source of the first switching element 5, a circuit having an effect equivalent to a kind of Zener diode is configured. doing.
With this configuration, the surge voltage generated at both ends of the first switching element 5 is clamped by the charging voltage of the capacitor 6, and the surge voltage is suppressed.
Note that a small diode can be used for the second diode 8 because a current flows only in a short time of several tens of nanoseconds to several hundred nanoseconds of the turn-off period of the first switching element 5.

The output capacitor 10 absorbs a ripple voltage generated by the switching of the first switching element 5. However, when the presence of a ripple voltage is allowed in the DC voltage output to the load 2, the output capacitor 10 is not necessarily required.
Further, when a constant current is supplied to a load whose impedance changes rapidly, the load change cannot be followed if the capacity of the output capacitor 10 is large. For this reason, the value of the reactor 9 can be set large and the output capacitor 10 can be made small or not attached. With such a configuration, it is possible to configure a DC power supply device that can stably supply a constant current to the load even when the load fluctuates.

Next, the operation of DC power supply device 1 according to the first embodiment will be described with reference to FIGS.
FIG. 2A shows a current path when the first switching element 5 is on, and shows a current path a of the current Ia and a current path b of the current Ib. FIG. 2B shows a current path when the first switching element 5 is off, and shows a current path c of the current Ic, a current path d of the current Id, and a current path e of the current Ie. Yes.

First, a case where the first switching element 5 is on will be described with reference to FIG.
When the first switching element 5 is on, the current Ia flows through the current path a of the DC input power supply 3 → the primary winding of the transformer 4 → the first switching element 5 → DC input power supply 3. The current Ib flows through the current path b of the load 2 → the reactor 9 → the capacitor 6 → the first switching element 5 → the load 2. Since the secondary side winding 4b of the transformer 4 is prevented from being energized by the first diode 7, no current flows.

  In FIG. 2A, the input voltage Vin, the output voltage -Vout, the voltage V1a of the primary side winding 4a of the transformer 4, the voltage V2a of the secondary side winding 4b of the transformer 4, and the voltage V3a across the capacitor 6 are shown. , The voltage V4a across the reactor 9, the switching frequency f of the first switching element 5, the on-duty D of the first switching element 5, the exciting inductance L1 of the transformer 4, the inductance L2 of the reactor 9, the step-up of the transformer 4 When the ratio n is set and the on-voltage at the time of energization of the first switching element 5 is ignored, Equations (1) to (6) are established.

V1a = Vin (1)
V2a = nV1a (2)
V3a = Vin + Vout (3)
V4a = −Vout + V3a (4)
Ia = V1a / L1 × D / f (5)
Ib = V4a / L2 × D / f (6)

  Next, a case where the first switching element 5 is OFF will be described with reference to FIG.

  During the turn-off transition period ts of the first switching element 5, due to the influence of the leakage inductance of the transformer 4 and the stray inductance included in the circuit wiring, the primary side winding 4 a of the transformer 4 → the capacitor 6 → the second diode 8. A pulsed current Ic flows in the current path c passing through.

Here, the effect of the second diode 8 will be described with reference to FIG.
FIG. 3A shows the drain-source voltage of the first switching element 5 due to the leakage inductance of the transformer 4 and the stray inductance included in the circuit wiring.
FIG. 3B shows the drain-source voltage of the first switching element 5 when the second diode 8 is present. FIG. 3C shows the current flowing through the second diode 8.

  In the absence of the second diode 8, a surge voltage determined by the product of the sum of the leakage inductance and wiring inductance and the time change rate of the current is generated at both ends of the first switching element 5. For this reason, it is necessary to select an expensive element with a high withstand voltage as the first switching element 5. Furthermore, since the switching loss generated at the time of switching increases, the circuit efficiency is lowered.

  In addition, assuming that a low withstand voltage product is used for the first switching element 5, when a general surge suppression snubber circuit is attached to the first switching element 5, all of the surge energy is absorbed by the snubber circuit. Since it needs to be consumed, the loss in the snubber circuit increases and the circuit efficiency is significantly reduced.

However, as shown in FIG. 3B, when there is the second diode 8, the capacitor 6 and the second diode 8 constituting the power supply main circuit section are connected between the drain and the source of the first switching element 5. Therefore, when viewed from the first switching element 5, a circuit having an effect equivalent to that of a kind of Zener diode is connected to both ends. For this reason, the surge voltage generated at both ends of the first switching element 5 is clamped by the charging voltage (= Vin + Vout) of the capacitor 6 to suppress the surge voltage.
Therefore, an inexpensive element with a low withstand voltage can be selected as the first switching element 5. Further, since the surge energy is stored in the capacitor 6, no loss occurs, and there is an effect that the circuit can be reduced in size and efficiency.

Here, the description returns to FIG.
When the first switching element 5 is turned off, the DC input power source 3 → the primary winding 4a of the transformer 4 → the capacitor 6 → the secondary winding 4b of the transformer 4 → the first diode 7 → DC input. Id flows through the current path d of the power source 3. Ie flows through the current path e of the load 2 → the reactor 9 → the secondary winding 4 b of the transformer → the first diode 7.

  As shown in FIG. 2 (b), the input voltage Vin, the output voltage -Vout, the primary side voltage V1b of the transformer 4, the secondary side voltage V2b of the transformer 4, the both-ends voltage V3b of the capacitor 6, and the both ends of the reactor 9 When the voltage V4b is assumed and the forward voltage drop of the first diode 7 is ignored, the equations (7) to (12) are established.

V1b = Vin−V3b−V2b (7)
V2b = nV1b (8)
V3b = Vin + Vout (9)
V4b = −Vout−V2b (10)
Id = V1b / L1 × (1-D) / f (11)
Ie = V4b / L2 × (1-D) / f (12)

When the relationship is obtained from Equations (7) to (10), Equation (13) is obtained.
V1b = V4b = −Vout / (1 + n) (13)
Therefore, when the voltage across the first switching element 5 is Vq, the equation (14) is obtained.
Vq = Vin−V1b = Vin + Vout / (1 + n) (14)

  From the expressions (13) and (14), the voltage applied to the transformer 4 and the voltage applied to both ends of the first switching element 5 when the first switching element 5 in the first embodiment is turned off are: In either case, the voltage is reduced by the amount obtained by dividing the output voltage Vout portion by (1 + n), compared to the applied voltage in the Cuk converter.

  Reduction of the voltage applied to the transformer 4 suppresses the change ΔB in the magnetic flux of the transformer core proportional to the voltage. As a result, it is possible to reduce the core iron loss that increases in proportion to the power of the change ΔB of the magnetic flux ΔB, and to reduce the size and increase the efficiency of the transformer.

Reduction of the voltage between both ends of the first switching element 5 makes it possible to select a low withstand voltage element. In general, there is a trade-off determined by the element material between the on-resistance and the withstand voltage of a MOSFET, and it is known that the on-resistance increases in proportion to the withstand voltage about 2.5. For this reason, the conduction loss of the 1st switching element 5 can be reduced significantly by selection of a low withstand voltage element.
Moreover, since the low withstand voltage element has a high switching speed, the switching loss can be greatly reduced. Furthermore, the low withstand voltage element has advantages such as a small package and low cost compared to the high withstand voltage element. Due to the downsizing, loss reduction, and cost reduction of these individual circuit components, a compact, high-efficiency, inexpensive DC power supply device can be configured.

Next, a method for controlling DC power supply device 1 according to the first embodiment will be described.
Since the current flowing through the reactor 9 is continuous, Ib in the equation (6) is equal to Ie in the equation (12). Furthermore, the expression (15) is obtained by applying the expression (13) to the expressions (3) and (4).
Vout = (1 + n) Vin × D / (D−1) (15)

  Therefore, when the step-up ratio n of the transformer is determined, the on-duty of the first switching element 5 is controlled by PWM (Pulse Width Modulation), so that the negative output voltage Vout is changed from the positive input voltage Vin. Can be obtained.

Next, functions and operations of the control unit will be described.
As shown in FIG. 1, the output detection circuit 13 detects either the voltage or current of the load 2 or both the voltage and current. The control circuit 11 outputs a pulse signal VP based on the deviation between the detection signal Vsen of the output detection circuit 13 and the output command value Vt. The first gate circuit 12 outputs a gate signal VG for driving the first switching element 5 by the pulse signal VP, and PWM-controls the first switching element 5.

  When a constant voltage is supplied to the load 2, the output detection circuit 13 detects the voltage across the load and outputs the detection signal Vsen to the control circuit 11. When a constant current is supplied to the load 2, the output detection circuit 13 detects a current flowing through the load and outputs this detection signal Vsen to the control circuit 11.

A circuit configuration example and function of the control circuit 11 will be described with reference to FIG.
The control circuit 11 includes a subtraction circuit 111, a PI control circuit 112, a triangular wave generation circuit 113, and a comparison circuit 114.

The subtraction circuit 111 calculates a deviation ΔVsen1 between the detection signal Vsen detected by the output detection circuit 13 and the output command value Vt. The PI control circuit 112 outputs a signal ΔVsen2 for performing proportional integration (PI) control using the output signal ΔVsen1 calculated by the subtraction circuit 111. The triangular wave generation circuit 113 generates a triangular wave signal Vtr having a predetermined frequency. The comparison circuit 114 compares the output signal ΔVsen2 of the PI control circuit 112 with the triangular wave signal Vtr of the triangular wave generation circuit 113.
In the comparison circuit 114, when the output signal ΔVsen2 of the PI control circuit 112 and the triangular wave signal Vtr of the triangular wave generation circuit 113 are compared, if the output signal ΔVsen2 is larger than the triangular wave signal Vtr, the first switching element 5 Is set to output a pulse signal VP = Vp. When the triangular wave signal Vtr is larger, the pulse signal VP = 0V for turning off the first switching element 5 is set to be output.

  The control circuit 11 may be configured using an analog control IC such as a logic IC or an operational amplifier, but may be configured using a digital control IC such as a microcomputer or FPGA.

  Thus, the pulse signal VP is generated based on the deviation between the detection signal Vsen and the output command value Vt, and when the pulse signal VP = Vp is input to the first gate circuit 12, the first switching element 5 is turned on. A signal of VG = Vg is output from the gate circuit. When the pulse signal VP = 0V is input to the first gate circuit 12, a signal of VG = 0V that turns off the first switching element 5 is output from the first gate circuit 12. In this way, it is possible to configure a circuit in which the DC input power source is stepped up / down according to the duty cycle of the ON / OFF signal supplied to the switching element, the polarity is inverted, and a stable DC voltage is supplied to the load. .

  Note that the voltage Vg output from the first gate circuit 12 is set to a voltage value equal to or higher than a threshold voltage at which the switching element is turned on. In addition, the voltage for turning off the first switching element 5 may not be 0 V and may be a negative voltage as long as it is equal to or lower than the threshold voltage for turning on the switching element.

  As described above, the DC power supply according to Embodiment 1 includes the series circuit of the primary side of the transformer and the first switching element connected to the DC input power source, the secondary side of the transformer, and the first side. A series circuit of diodes, a capacitor for connecting a series circuit of the secondary side of the transformer and the first diode to a connection point between the primary side of the transformer and the first switching element, and 2 of the transformer A second diode connected in parallel to the series circuit of the secondary side and the first diode, a reactor connecting the load to the connection point between the capacitor and the secondary side of the transformer, and the first switching element are controlled. And a control circuit for stepping up and down the voltage of the DC input power source and supplying it to the load. For this reason, there is an effect that the surge voltage can be reduced, and the circuit can be reduced in size and loss.

Embodiment 2. FIG.
In the first embodiment, the transformer and the reactor are separately mounted. However, in the second embodiment, a multi-output transformer having one transformer and one reactor is used.

Hereinafter, with respect to the configuration and operation of the second embodiment of the present invention, differences from the first embodiment will be described based on FIG. 5 which is a configuration diagram of the DC power supply device 100 and FIG. 6 which is a configuration diagram of the multi-output transformer. The explanation is centered.
In FIG. 5, the same reference numerals are given to the same or corresponding parts as those in FIG. 1, which is a configuration diagram of the DC power supply device 1 of the first embodiment.
5, in addition to the points A to C in FIG. 1, a connection point between the second end of the secondary winding of the multi-output transformer and the anode of the first diode is a D point.

  In the configuration diagram of FIG. 5, the difference from FIG. 1 is only the multi-output transformer 41. The method of controlling the first switching element 5 by the control circuit 11 is the same as that of the first embodiment, and the effect by the operation is the same as the effect obtained in the first embodiment.

  In the first embodiment, the transformer 4 and the reactor 9 are separately mounted. However, since the transformer 4 and the reactor 9 use a core and a bobbin for holding the core, the circuit is enlarged. This is one of the causes of high costs. Therefore, in the second embodiment, three windings (primary winding 41a, secondary winding 41b, and tertiary winding 41c) are wound around a common core as shown in FIG. It is set as the structure using the multi-output transformer 41 which made the transformer 4 and the reactor 9 which are shown by 1 into one.

In the circuit shown in the first embodiment of the present invention, the voltage ratio between the primary side winding 4a and the secondary side winding 4b of the transformer 4 having a turns ratio n and both ends of the reactor 9 is either when switching is on or off. I found that the ratio was 1: n: 1.
Therefore, as shown in FIG. 6, the turn ratio is set so that Vin-A, B-D, and B-C are 1: n: 1, and the multi-output transformer 41 is set as shown in FIG. The circuit operation similar to that of the first embodiment can be obtained by connecting the black circles shown in FIG.
The resonance frequency is adjusted mainly by the capacitor 6 by the inductance of the capacitor 6 and the third winding of the multi-output transformer 41.

  If the multi-output transformer 41 is configured as described above, the same effects as those of the first embodiment can be obtained, and the cores and bobbins constituting the reactor 9 can be reduced. In addition, the circuit can be reduced in size and cost.

  As described above, the DC power supply according to Embodiment 2 has a configuration using a multi-output transformer in which a transformer and a reactor are combined into one. For this reason, it has the effect that a surge voltage can be reduced similarly to the DC power supply device according to the first embodiment, and the circuit can be reduced in size and loss. Further, the circuit can be reduced in size and cost.

Embodiment 3 FIG.
Embodiment 3 includes a series circuit of a primary side of a transformer connected to a DC input power source and a first switching element, a series circuit of a secondary side of the transformer and a second switching element, and a transformer A capacitor for connecting a series circuit of the secondary side of the transformer and the second switching element to a connection point between the primary side of the transformer and the first switching element, a secondary side of the transformer and the second switching element, A second diode connected in parallel to the series circuit, a reactor connecting a load to the connection point between the capacitor and the secondary side of the transformer, and controlling the first switching element and the second switching element to direct current The present invention relates to a DC power supply device including a control circuit that raises and lowers the voltage of an input power supply and supplies it to a load.

  Specifically, the direct-current power supply device according to the third embodiment has a configuration in which a second switching element is connected instead of the first diode connected in series to the secondary side of the transformer in the first embodiment. It is a thing.

Hereinafter, with respect to the configuration and operation of the third embodiment of the present invention, based on FIG. 7 which is a configuration diagram of the DC power supply device 200 and FIG. 8 which is an explanatory diagram of a gate signal, the difference from the first embodiment will be mainly described. explain.
In FIG. 7, the same reference numerals are given to the same or corresponding parts as those in FIG. 1, which is a configuration diagram of the DC power supply device 1 of the first embodiment.

A configuration according to DC power supply device 200 of Embodiment 3 of the present invention will be described with reference to FIG.
In FIG. 7, the entire system includes a DC power supply device 200 and a load 2 that supplies a desired DC voltage. The DC power supply apparatus 200 includes a DC input power supply unit, a power supply main circuit unit, and a control unit as main units.

The DC input power supply unit corresponds to the DC input power supply 3.
Next, the power supply main circuit unit will be described. The power supply main circuit section includes a transformer 4, a first switching element 5, a capacitor 6, a second switching element 51, a second diode 8, a reactor 9, and an output capacitor 10.
A series circuit of a primary side winding 4 a of the transformer 4 and the first switching element 5 is connected to the DC input power source 3. The first end of the primary winding 4 a of the transformer 4 is connected to the positive electrode of the DC input power supply 3. The second end of the primary winding 4a of the transformer 4 is connected to the drain of the first switching element 5, and this connection point is referred to as point A.
A series circuit of the secondary winding 4 b of the transformer 4 and the second switching element 51 is connected in parallel to the first switching element 5 via the capacitor 6. That is, the first end of the capacitor 6 is connected to the point A. The second end of the capacitor 6 is connected to the first end of the secondary winding 4b of the transformer 4, and this connection point is referred to as point B. The second end of the secondary winding 4b of the transformer 4 and the drain of the second switching element 51 are connected, and the connection point is referred to as point D.

A second diode 8 is connected in parallel to the series circuit of the secondary winding 4 b of the transformer 4 and the second switching element 51. The anode of the second diode 8 is connected to the first end of the secondary winding 4 b of the transformer 4, that is, the point B.
An output capacitor 10 is connected in parallel to the series circuit of the secondary winding 4 b of the transformer 4 and the second switching element 51, that is, the second diode 8, via the reactor 9. The first end of the reactor 9 is connected to point B. A connection point between the second end of the reactor 9 and the first end of the output capacitor 10 is referred to as a C point.
The load 2 is connected to the output end of the power supply main circuit section, that is, the first end and the second end of the output capacitor 10.
The source of the first switching element 5, the source of the second switching element 51, the cathode of the second diode 8, and the second end of the output capacitor 10 are connected to the negative electrode of the DC input power supply 3.

  Next, the control unit will be described. The control unit includes a control circuit 11 that generates a pulse signal for switching control of the first switching element 5 and the second switching element 51, a first gate circuit 12, a second gate circuit 22, and output detection. A circuit 13.

The control unit controls the first and second switching elements to step up and down the voltage of the DC input power supply and supply it to the load.
The control circuit 11 generates a pulse signal that controls the switching of the first switching element 5 and the second switching element 51. The first gate circuit 12 receives a pulse signal from the control circuit 11 and outputs a gate signal to the gate of the first switching element 5. The second gate circuit 22 receives a pulse signal from the control circuit 11 and outputs a gate signal to the gate of the second switching element 51. The output detection circuit 13 detects the output voltage and current to the load 2 necessary for controlling the first switching element 5 and the second switching element 51, and outputs them to the control circuit 11.

  The third embodiment is the same as the first embodiment except for the second switching element 51 and the second gate circuit 22 that drives the second switching element 51. Further, the control method is the same as that of the first embodiment, and the effect by the operation is the same as the effect obtained in the first embodiment. Therefore, the second switching element 51 and the second switching element 51 are hereinafter described. The second gate circuit 22 to be driven will be described.

The second switching element 51 is a voltage-controlled self-extinguishing type high-speed semiconductor element, and either an N-type or a P-type element may be used. However, since the point D in FIG. It is desirable to use the MOSFET.
When an N-type MOSFET is used, it is necessary to connect a source to point D in FIG. 7 and provide a positive gate signal VG ′ with reference to this source. However, since the point D is a floating potential, the second gate circuit 22 needs to be insulated. For this reason, there is a problem that the circuit configuration becomes complicated and the circuit becomes expensive.
If a P-type MOSFET is used, the source potential of the second switching element 51 can be set to 0 V side, and the second switching element 51 is switched by giving a negative gate signal Vg ′ to the source. Can be made. Therefore, the second gate circuit 22 does not need to be insulated, and the circuit can be stably operated. Furthermore, the gate circuit can be configured at low cost.

Below, the case where P-type MOSFET is used for the 2nd switching element 51 is demonstrated. 8A shows a signal waveform of the pulse signal Vp, FIG. 8B shows a signal waveform of the gate signal Vg, and FIG. 8C shows a signal waveform of the gate signal Vg ′. Yes.
The control circuit 11 outputs the pulse signal VP according to the deviation between the detection signal Vsen and the output command value Vt, as in the first embodiment. For example, the pulse signal is branched into two, one is input to the first gate circuit 12 and the other is input to the second gate circuit 22. In the first gate circuit 12, as shown in FIGS. 8A and 8B, a positive voltage signal VG = Vg for turning on the first switching element 5 when the pulse signal VP = Vp. Is output. When the pulse signal VP = 0V, a signal of VG = 0V for turning off the first switching element 5 is output. Thereby, the first switching element 5 is turned on / off according to the signal of the pulse signal VP. On the other hand, in the second gate circuit 22, as shown in FIGS. 8A and 8C, when the pulse signal VP = Vp, a signal of VG ′ = 0 V for turning off the second switching element. When the pulse signal VP = 0V, a negative voltage signal VG ′ = Vg ′ for turning on the second switching element 51 is output. As a result, the second switching element 51 is turned off / on according to the signal of the pulse signal VP.

The voltage VG = Vg output from the first gate circuit 12 is set to a voltage value equal to or higher than a threshold voltage at which the switching element is turned on. Further, the voltage VG = 0 V for turning off the first switching element 5 may not be 0 V and may be a negative voltage as long as it is equal to or lower than the threshold voltage for turning on the switching element. The voltage VG = Vg ′ output from the second gate circuit 22 is set to a voltage value equal to or lower than a threshold voltage at which the second switching element 51 that is a P-type MOSFET is turned on. Further, the voltage VG = 0 V for turning off the second switching element 51 may not be 0 V and may be a positive voltage as long as it is equal to or higher than the threshold voltage for turning off the second switching element 51.
When an N-type MOSFET is used for the second switching element 51, the operation of the circuit is the same as described above if the output from the second gate circuit 22 is a positive voltage.

Thus, by turning on / off the first switching element 5 in accordance with the pulse signal VP and turning off / on the second switching element 51 contrary to on / off of the first switching element 5, It becomes possible to replace the first diode 7 in the first embodiment with the second switching element 51 in the third embodiment. As a result, it is possible to obtain the same circuit operation as in the first embodiment, and the same effect as in the first embodiment can be obtained.
Furthermore, the on-voltage generated when a current flows through a switching element having an on-resistance is one order of magnitude smaller than the energized voltage generated when a current flows through a diode, so that circuit loss can be greatly reduced. It becomes.
With this configuration, it is possible to reduce the size, loss, and cost of the circuit components to be used, and thus it is possible to configure a DC power supply that is small, highly efficient, and inexpensive.

  In the third embodiment, as in the second embodiment, the transformer and the reactor can be a single multi-output transformer.

  As described above, the DC power supply according to Embodiment 3 includes the series circuit of the primary side of the transformer and the first switching element connected to the DC input power source, the secondary side of the transformer, and the second side. A series circuit with a switching element, a capacitor for connecting a series circuit of the secondary side of the transformer and the second switching element to a connection point between the primary side of the transformer and the first switching element, and a transformer A second diode connected in parallel to a series circuit of the secondary side of the second switching element and the second switching element, a reactor connecting a load to a connection point between the capacitor and the secondary side of the transformer, and the first switching element And a control circuit that controls the second switching element to step up and down the voltage of the DC input power supply and supplies the voltage to the load. For this reason, there is an effect that the surge voltage can be reduced, and the circuit can be reduced in size and loss. Furthermore, since the circuit components to be used can be reduced in size, reduced in loss, and reduced in cost, a DC power supply device that is small, highly efficient, and inexpensive can be configured.

Embodiment 4 FIG.
The DC power supply device according to the fourth embodiment is configured to use a polarity inversion capacitor, a lead-in diode, and a current limiting resistor instead of the second gate circuit in the third embodiment.

Hereinafter, with respect to the configuration and operation of the fourth embodiment of the present invention, based on FIG. 9 which is a configuration diagram of the DC power supply device 300 and FIGS. 10 and 11 which are operation explanatory diagrams, mainly differences from the third embodiment will be described. explain.
In FIG. 9, the same reference numerals are given to the same or corresponding parts as in FIG. 7, which is a configuration diagram of the DC power supply device 200 of the third embodiment.
Note that FIGS. 10 and 11 show only a circuit portion necessary for explaining the gate signal of the second switching element.

  In the third embodiment, the second gate circuit 22 is used and the second switching element 51 is turned off / on according to the pulse signal VP. However, this configuration requires a negative output gate power supply to generate the gate signal VG ', and the circuit configuration of the second gate circuit 22 is slightly complicated.

In the fourth embodiment, the first end (point E in FIG. 9) of the polarity inversion capacitor 61 is connected to the output of the first gate circuit 12, and the second end (point F in FIG. 9) is the second switching. The gate of the element 51 is connected. A series circuit of a lead-in diode 62 and a current limiting resistor 63 is connected between the point F and the source of the second switching element 51.
The polarity inversion capacitor 61 is a capacitor having a sufficiently large capacity with respect to the gate input capacitance of the second switching element 51, and the lead-in diode 62 is a diode having a withstand voltage higher than the output voltage of the first gate circuit 12. It is desirable to select. The current limiting resistor 63 is a resistor that limits the forward current of the drawing diode 62 to a rated value or less, and the value is determined from the current characteristics of the drawing diode 62.

Operations of the first gate circuit 12 and the polarity reversal capacitor 61 will be described with reference to FIGS. 10 illustrates the operation when the pulse signal VP = Vp, and FIG. 11 illustrates the operation when VP = 0V. As shown in FIG. 10, the first gate circuit is used when the pulse signal VP = Vp. 12 outputs a positive gate signal VG = Vg, and the polarity inversion capacitor 61 is charged to Vg−Vf via the pull-in diode 62 and the current limiting resistor 63. Here, Vf is the ON voltage of the drawing diode 62. At this time, the gate signal voltage VG is a signal for turning on the first switching element 5, and the gate signal VG ′ is a positive voltage signal corresponding to the diode on-voltage Vf, so that the first switching element 5 is turned on. Then, the second switching element 51 is turned off.

On the other hand, as shown in FIG. 11, when the pulse signal VP = 0V, the first gate circuit 12 outputs a gate signal of VG = 0V. At this time, since the voltage across the polarity reversing capacitor 61 is kept at Vg−Vf, the point F in FIG. 11 becomes a negative voltage of − (Vg−Vf), and the second switching element 51 is turned on. A gate signal VG ′ = − (Vg−Vf) is applied. Accordingly, the first switching element 5 is turned off and the second switching element 51 is turned on.
In FIGS. 9 to 11, the gate resistance is not described for each gate of the first switching element 5 and the second switching element 51, but each switching is performed at a high speed and a surge is generated between the drain and the source. When voltage is generated, it is desirable to attach a gate resistor.

  As described above, the DC power supply device 300 according to the fourth embodiment operates in the same manner as the DC power supply device 200 according to the third embodiment, and can form a small and low-loss circuit as in the third embodiment. Further, a negative output gate power source for switching the second switching element 51 is not required, and the circuit can be operated only by the signal of the first gate circuit 12, thereby simplifying the circuit. Thus, a compact and low-cost DC power supply device can be configured.

  In the fourth embodiment, as in the second embodiment, the transformer and the reactor can be a single multi-output transformer.

  As described above, the direct-current power supply according to the fourth embodiment is configured to use a polarity inversion capacitor, a pull-in diode, and a current limiting resistor instead of the second gate circuit in the third embodiment. For this reason, there is an effect that the surge voltage can be reduced, and the circuit can be reduced in size and loss. Furthermore, the circuit can be simplified, and a small-sized and low-cost DC power supply device can be configured.

  In the above embodiment, the switching element and the diode element are formed of silicon. However, the switching element and the diode element may be formed of a wide band gap semiconductor having a larger band gap than silicon. Examples of the wide band gap semiconductor include silicon carbide, a gallium nitride-based material, and diamond.

  Switching elements and diode elements formed by such wide band gap semiconductors have high voltage resistance and high allowable current density, so that switching elements and diode elements can be miniaturized. By using elements and diode elements, it is possible to reduce the size of a DC power supply apparatus incorporating these elements.

  In addition, since the heat resistance is high, the heat radiation fins of the heat sink can be downsized and the water cooling section can be air cooled, so that the DC power supply can be further downsized.

  Furthermore, since the power loss is low, it is possible to increase the efficiency of the switching element and the diode element, and further increase the efficiency of the DC power supply device.

  Although both the switching element and the diode element are preferably formed of a wide band gap semiconductor, either one of the elements may be formed of a wide band gap semiconductor, and the effects described in this embodiment are achieved. Can be obtained.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

1,100,200,300 DC power supply, 2 loads, 3 DC input power supply,
4 transformer, 5 first switching element, 6 capacitor, 7 first diode,
8 Second diode, 9 reactor, 10 output capacitor, 11 control circuit,
12 first gate circuit, 13 output detection circuit, 22 second gate circuit,
41 multi-output transformer, 51 second switching element, 61 polarity inversion capacitor,
62 drawing diode, 63 current limiting resistor, 111 subtracting circuit,
112 PI control circuit, 113 triangular wave generation circuit, 114 comparison circuit.

Claims (8)

A series circuit of a primary side of the transformer and a first switching element is connected to a DC input power source, and a secondary side of the transformer is connected to a connection point of the primary side of the transformer and the first switching element. A series circuit with a first diode is connected via a capacitor, and a second diode is connected in parallel with a series circuit of a secondary side of the transformer and the first diode, and the capacitor and the transformer A DC power supply comprising a control circuit for connecting a load to a connection point with the secondary side of the DC via a reactor, controlling the first switching element to step up / down the voltage of the DC input power supply, and supplying the voltage to the load apparatus. A series circuit of a primary side of the transformer and a first switching element is connected to a DC input power source, and a secondary side of the transformer is connected to a connection point of the primary side of the transformer and the first switching element. A series circuit with a second switching element is connected via a capacitor, and a second diode is connected in parallel with a series circuit of the secondary side of the transformer and the second switching element, and the capacitor and the A control circuit that connects a load to a connection point with the secondary side of the transformer via a reactor, controls the first and second switching elements to step up and down the voltage of the DC input power supply, and supplies the voltage to the load DC power supply with The DC power supply device according to claim 2, wherein the second switching element is a P-type voltage-controlled self-extinguishing semiconductor. 3. The control circuit includes a first gate circuit that outputs a gate signal to the first switching element, and a second gate circuit that outputs a gate signal to the second switching element. Or the direct-current power supply device of Claim 3. The control circuit includes a first gate circuit that outputs a gate signal to the first switching element, and a polarity reversal capacitor is provided between the output of the first gate circuit and the source of the second switching element. 4. The DC power supply device according to claim 3, wherein a lead-in diode and a current limiting resistor are connected in series, and a gate of the second switching element is connected to a connection point between the polarity inversion capacitor and the lead-in diode. 6. The DC power supply device according to claim 1, comprising a multi-output transformer having a single core in which the transformer and the reactor are added as a tertiary side of the transformer. 7. The DC power supply device according to claim 6, wherein the multi-output transformer has a primary side: secondary side: tertiary side winding ratio of 1: n: 1. 8. The DC power supply device according to claim 1, wherein at least one of the switching element and the diode is formed of a wide band gap semiconductor having a band gap larger than that of silicon. 9.

Images