JP2021197757A - Resonance type power supply device - Google Patents

Abstract

To provide a resonance type power supply device capable of obtaining a high output voltage.SOLUTION: A resonance type power supply device includes: a switching circuit that receives as an input a DC voltage and applies an AC voltage to a first winding through a resonance capacitor; a rectifier circuit that rectifies a current flowing through a second winding and outputs between both ends of a smoothing capacitor; a transformer that magnetically couples the first and second windings; and a control unit that controls switching elements in the switching circuit and the rectifier circuit. The resonance type power supply device outputs DC power to a load from between both ends of the smoothing capacitor. The control unit controls the switching element so as to include a charging period where the current of the resonance capacitor is increased in a direction of increasing a voltage absolute value of the resonance capacitor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply device that insulates and outputs the power of a DC power supply.

In recent years, due to the growing awareness of global environmental conservation, systems equipped with DC power sources such as storage batteries, solar cells, and fuel cells have been developed. In these systems, there is a demand for a DC-DC converter that supplies power from a DC power supply to a load or another DC power supply with high conversion efficiency. As a circuit method of an isolated DC-DC converter with high efficiency, a resonance type converter utilizing a resonance phenomenon of capacitance and inductance is known.

In the resonance type converter, when the switching element is turned off at the timing when the current flowing through the switching element becomes small due to resonance, the switching loss becomes small because the breaking current is small, and high efficiency can be obtained. However, in general, in a resonant converter, the output is controlled by changing the switching frequency, and the switching frequency is raised when the output power is reduced. Therefore, when the input voltage is high or the output voltage is low, switching is performed. The frequency goes up. Then, the switching element is turned off before the current flowing through the switching element becomes small due to resonance. At this time, if the output current is large, the breaking current is large and the switching frequency is also high, so that the switching loss becomes large and the efficiency decreases. do.

Therefore, Patent Document 1 discloses a resonance converter technique that can obtain high efficiency even when the output current is large and the input voltage is high or the output voltage is low. In Patent Document 1, the switching frequency is set lower than the resonance frequency of the resonance capacitor and the resonance inductor. Further, in Patent Document 1, after the resonance current by the resonance capacitor and the resonance inductor has finished flowing, the resonance capacitor is charged by the resonance current by the resonance capacitor, the resonance inductor and the transformer excitation inductance, and then the output voltage polarity of the switching circuit is switched. A high output voltage is obtained by increasing the sum of the input voltage and the resonant capacitor voltage.

Japanese Unexamined Patent Publication No. 2017-99182

In the resonance type converter of Patent Document 1, it is possible to obtain an output voltage higher than the turns ratio of the transformer.

However, in the resonance type converter, when the output current is large, the resonance current of the resonance capacitor and the resonance inductor becomes large, so that the voltage of the resonance capacitor is already high after the resonance current has finished flowing.

In particular, when the voltage of the resonance capacitor is higher than the input voltage, even if an attempt is made to charge the resonance capacitor with the resonance current due to the resonance capacitor, the resonance inductor, and the transformer excitation inductance, this charging current will decrease. With the technique described in 1, it is difficult to charge the resonant capacitor to a higher voltage.

An object of the present invention is to provide a resonance type power supply device capable of obtaining a high output voltage.

As a preferable example of the present invention, a switching circuit in which a DC voltage is input and an AC voltage is applied to the first winding via a resonance capacitor, and a current flowing in the second winding are rectified between both ends of the smoothing capacitor. It has a rectifying circuit that outputs, a transformer that magnetically couples the first winding and the second winding, and a control unit that controls the switching circuit and the switching element in the rectifying circuit, and both ends of the smoothing capacitor. It is a resonance type power supply device that outputs DC power to the load from between.
The control unit is a resonance type power supply device that controls the switching element so as to include a charging period in which the current of the resonance capacitor is increased in a direction of increasing the absolute voltage value of the resonance capacitor.

According to the present invention, it is possible to provide a resonance type power supply device capable of obtaining a high output voltage.

The circuit block diagram of the resonance type power supply device in Example 1. FIG. An operation diagram illustrating the operation of a resonance type power supply device. The waveform diagram explaining the operation of mode a0. The waveform diagram explaining the operation of mode a1. The waveform diagram explaining the operation of mode a2. The waveform diagram explaining the operation of mode a3. The waveform diagram explaining the operation of mode a4. The waveform diagram explaining the operation of mode a5. The waveform diagram explaining the operation of mode a6. The waveform diagram explaining the operation of mode a7. The waveform diagram explaining the operation of mode a8. A graph illustrating the operation of a resonant power supply. The circuit block diagram of the resonance type power supply device in Example 2.

Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit configuration diagram of the resonance type power supply device 10 in the first embodiment. The resonance type power supply device 10 is connected between the DC power supply 3 and the load 4, and supplies power from the DC power supply 3 to the load 4.

The resonance type power supply device 10 has a switching circuit 1 that inputs a DC voltage and applies an AC voltage to the first winding N1 via the resonance capacitor Cr, and a smoothing capacitor that rectifies the current flowing through the second winding N2. A rectifying circuit 2 that outputs between both ends, a control unit 5 that controls the on / off state of the switching element provided in these circuits, a smoothing capacitor C1 connected in parallel to the DC power supply 3, and smoothing connected in parallel to the load 4. It includes a capacitor C2 and a transformer that magnetically couples the first winding and the second winding.

The switching circuit 1 includes a switching element Q1 and a switching element Q2 connected in series between both ends of the smoothing capacitor C1, and the series connection point is a node Nd1. Further, a switching element Q3 and a switching element Q4 connected in series between both ends of the smoothing capacitor C1 are provided, and the series connection point is a node Nd2. This switching circuit 1 inputs a voltage from the smoothing capacitor C1 and outputs it between the nodes Nd1 and Nd2. Further, a resonance capacitor Cr, a resonance inductor Lr, and a first winding N1 of the transformer T are connected in series between the nodes Nd1 and Nd2. The exciting inductance Lm of the transformer T is defined in parallel with the first winding N1.

Diodes D1 to D4 are connected in antiparallel to the switching elements Q1 to Q4, respectively. Here, when MOSFETs are used as these switching elements Q1 to Q4, the parasitic diodes of MOSFETs can be used, so the diodes D1 to D4 can be omitted.

The rectifier circuit 2 includes a diode D5 and a diode D6 connected in series between both ends of the smoothing capacitor C2, and the series connection point is a node Nd3. Further, a diode D7 and a diode D8 connected in series between both ends of the smoothing capacitor C2 are provided, and the series connection point is referred to as a node Nd4. This rectifier circuit 2 inputs the current of the second winding N2 magnetically coupled to the first winding N1 between the nodes Nd3-Nd4, rectifies it, and outputs it between both ends of the smoothing capacitor C2.

The switching elements Q5 to Q8 are connected in antiparallel to the diodes D5 to D8, respectively. The switching element Q5 and the switching element Q6 are connected in series by a first node (node Nd3) between both ends of the smoothing capacitor C2. The switching element Q7 and the switching element Q8 are connected in series by a second node (node Nd4) between both ends of the smoothing capacitor C2. One end of the second winding N2 is connected to the first node (node Nd3), and the other end of the second winding N2 is connected to the second node (node Nd4).

The control unit 5 reads out the program recorded in the recording device by a CPU such as a microcomputer, and as shown in FIGS. 2 or 3A to 3I, the ON state of the switching element constituting the switching circuit 1 and the rectifier circuit 2 is set. Control the off state.

Here, when MOSFETs are used as these switching elements Q5 to Q8, the parasitic diodes of MOSFETs can be used, so the diodes D5 to D8 can be omitted.

Here, in the resonance type power supply device 10, the resonance capacitor Cr and the resonance inductor Lr are connected in series with the first winding N1, but the resonance capacitor Cr and the resonance inductor Lr are connected to the second winding N2. It may be connected in series, or may be connected in series to both the first winding N1 and the second winding N2. Further, the leakage inductance of the transformer T may be used as the resonance inductor Lr.

A voltage sensor 6 is connected to the smoothing capacitor C1 to detect the input voltage of the switching circuit 1. A voltage sensor 7 is connected to the smoothing capacitor C2 to detect the output voltage of the rectifier circuit 2. Further, a current sensor 8 is connected between the rectifier circuit 2 and the smoothing capacitor C2 to detect the output current of the rectifier circuit 2. The voltage sensor 6, the voltage sensor 7, and the current sensor 8 are connected to the control unit 5.

Hereinafter, the operation of the resonance type power supply device 10 will be described with reference to the drawings. In this specification, the voltage between both ends of the switching element in the ON state and the voltage equal to or less than the forward voltage drop of the diode are referred to as zero voltage, and the voltage between both ends of the switching element is the zero voltage. At this time, turning on this switching element is called zero voltage switching. Zero voltage switching has the effect of suppressing switching loss.

The circuit operation of the resonance type power supply device 10 will be described with reference to FIG. 2 and FIGS. 3A to 3I. FIG. 2 is a waveform diagram, and Vg1 to Vg8 represent gate signals of switching elements Q1 to Q8, that is, on / off states, respectively. V1 represents the voltage between the nodes Nd1 and Nd2 of the switching circuit 1, and the voltage of the node Nd1 with respect to the node Nd2 is positive. V2 represents the voltage between the nodes Nd3-Nd4 of the rectifier circuit 2, and the voltage of the node Nd3 with respect to the node Nd4 is positive.

The VCr represents the voltage of the resonance capacitor Cr, and the direction in which the current flows from the node Nd1 toward the resonance capacitor Cr is positive.

ILr represents the current of the resonant inductor, and the direction of flow from the node Nd1 to the resonant inductor Lr is positive.

ILm represents the exciting current of the transformer T flowing through the exciting inductance Lm, and the direction in which the voltage V1 is positively maintained and the direction in which the voltage V2 is positively maintained are positive. IN2 represents the current flowing through the second winding N2, and the direction of flow from the second winding N2 to the node Nd3 is positive.

t0 to t16 represent the time. Further, Tp represents the charging period from t4 to t6 and from t12 to t14.

3A to 3I show circuit operations in modes a0 to a8, respectively. The circuit operation at each time and mode will be described below.
(Mode a0: Time t0 to t1)
As shown in FIG. 3A, in the mode a0, in the switching circuit 1, the switching elements Q1 and Q4 are in the on state, and the switching elements Q2 and Q3 are in the off state. The voltage of the smoothing capacitor C1 is output from the switching circuit 1, a positive voltage V1 is applied to the resonance capacitor Cr, the resonance inductor Lr and the first winding N1, and the current is applied to the resonance capacitor Cr, the resonance inductor Lr and the first winding N1. Is flowing.

In the rectifier circuit 2, the switching elements Q5 and Q8 are in the on state and the switching elements Q6 and Q7 are in the off state, and the current induced in the second winding N2 passes through the switching elements Q5 and Q8 to both ends of the smoothing capacitor C2. Flowing. When MOSFETs are used as the switching elements Q5 and Q8, by turning on the switching elements Q5 and Q8 in this way, the conduction loss can be reduced as compared with the case where the current flows through the diodes D5 and D8. .. This is called synchronous rectification.

The voltage of the smoothing capacitor C2 is applied to the second winding N2, and the voltage V2 is positive. In this mode, the resonance current due to the resonance capacitor Cr and the resonance inductor Lr flows through the resonance capacitor Cr, the resonance inductor Lr, the first winding N1 and the second winding N2.
(Mode a1: Time t1 to t2)
As shown in FIG. 3B, in the mode a1, the switching element Q5 is turned off at the time t1 before the time t2 when the resonance current by the resonance capacitor Cr and the resonance inductor Lr ends. The current flowing through the switching element Q5 flows through the diode D5.
(Mode a2: Time t2 to t3)
As shown in FIG. 3C, when the electric charge is accumulated in the resonant capacitor Cr, the resonant inductor current ILr decreases to the exciting inductance current ILm, and the current IN2 flowing through the second winding N2 decreases to zero, the mode a2 is entered. .. A reverse recovery current flows through the diode D5, a positive voltage V2 is continuously applied to the second winding N2, and the current IN2 flowing through the second winding N2 increases in the negative direction. Further, the resonant inductor current ILr falls below the exciting inductance current ILm and decreases.
(Mode a3: Times t3 to t4)
As shown in FIG. 3D, in the mode a3, when the diode D5 reversely recovers, the mode a3 is reached. The switching element Q8 is continuously on, and the current IN2 flowing through the second winding N2 becomes a circulating current passing through the switching element Q8 and the diode D6.

Since the voltage V2 is a zero voltage and the second winding N2 and the first winding N1 are also zero voltages, the voltage V1 output by the switching circuit 1 is applied to the resonance capacitor Cr and the resonance inductor Lr. At this time, since the voltage VCr of the resonance capacitor Cr is higher than the voltage V1, the current ILr of the resonance inductor Lr decreases, and the current IN2 flowing through the second winding N2 increases in the negative direction.
(Mode a4: Times t4 to t5)
As shown in FIG. 2, the switching element Q8 in which the rectifier circuit 2 is in the ON state during the period when the current of the resonant inductor is larger than the exciting current of the transformer T is turned off after the current of the resonant inductor falls below the exciting current of the transformer. Will be. Alternatively, the switching element Q8, which is in the ON state of the rectifier circuit 2, is turned off after the polarity of the current of the second winding changes.

As shown in FIG. 3E, when the switching element Q8 is turned off, the mode a4 is set.

IN2 flowing in the second winding N2 current flowing through the switching element Q8 is commutated to the diode D7 and flows to the smoothing capacitor C2. At this time, the switching elements Q6 and Q7 are turned on (zero voltage switching). The switching element Q6 is zero voltage switching even if it is turned on in the mode a3.

The voltage V2 becomes negative, and the voltage of the smoothing capacitor C2 is applied to the second winding N2 in the opposite direction. On the other hand, the voltage of the smoothing capacitor C1 is still positively output to the voltage V1, and the voltage V2 is converted to the first winding N1 by the turns ratio of the first winding N1 and the second winding N2. , The total voltage with the voltage V1 is applied to the resonance capacitor Cr and the resonance inductor Lr. This total voltage is higher than the resonant capacitor voltage VCr. Therefore, the resonant inductor current ILr, which had decreased in the mode a3, has turned to increase in the mode a4. Along with this, the change in the current IN2 flowing in the second winding N2 also turns positive and approaches zero from negative. The resonance inductor current ILr is a current for charging the resonance capacitor Cr, and the resonance capacitor voltage VCr further increases.

In this way, voltages of opposite polarities are applied from the switching circuit 1 and the rectifying circuit 2 to the first winding N1 and the second winding N2 of the transformer T to resonate in the direction of increasing the absolute voltage value of the resonance capacitor Cr. The period for increasing the current of the capacitor Cr is called the charging period.
(Mode a5: Time t5 to t6)
As shown in FIG. 3F, when the resonant inductor current ILr increases to the exciting inductance current ILm and the current IN2 flowing through the second winding N2 reaches zero, the mode a5 is entered. Subsequently, a voltage of opposite polarity is applied to the first winding N1 and the second winding N2 of the transformer T from the switching circuit 1 and the rectifying circuit 2, and the current of the resonance capacitor Cr, that is, the resonance inductor current ILr resonates. The charging period increases in the direction of increasing the absolute voltage value of the capacitor Cr.

The resonance inductor current ILr increases beyond the exciting inductance current ILm, the current IN2 flowing in the second winding N2 also increases in the positive direction, and the energy of the smoothing capacitor C2 is transferred from the rectifying circuit 2 to the second winding N2. It is being supplied.

In the mode a5, the control unit 5 controls so as to further include a period for supplying energy from the rectifier circuit 2 to the second winding N2 during the charging period. Thereby, the output voltage can be increased.
(Mode a6: Times t6 to t7)
As shown in FIG. 3G, when the switching elements Q1 and Q4 are turned off, the current flowing through the switching elements Q1 and Q4 is commutated to the diodes D2 and D3, respectively, and the mode a6 is set. At this time, the switching elements Q2 and Q3 are turned on (zero voltage switching). The switching elements Q2 and Q3 need only be turned on by the positive period, that is, time t8, for the resonant inductor current ILr, resulting in zero voltage switching.

The polarity of the voltage V1 output by the switching circuit 1 is switched, and the voltage V1 becomes negative. The resonance inductor current ILr and the current IN2 flowing through the second winding N2 turn to decrease.
(Mode a7: Times t7 to t8)
As shown in FIG. 3H, when the current IN2 flowing through the second winding N2 reaches zero, the mode a7 is entered. The resonance inductor current ILr is smaller than the exciting inductance current ILm. The current IN2 flowing through the second winding N2 increases in the negative direction, and energy supply to the smoothing capacitor C2 is started.
(Mode a8: Times t8 to t9)
As shown in FIG. 3I, when the resonant inductor current ILr reaches zero, the mode a8 is entered. The resonant inductor current ILr increases in the negative direction. This mode a8 is a symmetrical operation of the mode a0. After that, after the symmetrical operation of the modes a1 to a7, the mode returns to the mode a0.

As described above, of the two switching elements Q5 and Q8 provided in the rectifier circuit 2 that was turned on in the mode a0, one of the switching elements is set before the time t2 when the resonant inductor current ILr reaches the exciting inductance current ILm. That is, the current IN2 flowing in the second winding N2 is turned off before it decreases to zero, and the other switching element is turned off after the time t2. As a result, the switching element provided in the rectifier circuit 2 can be switched to zero voltage while preventing an excessive backflow of energy from the smoothing capacitor C2 and a decrease in the charging current of the resonance capacitor Cr.

As shown in FIGS. 2 and 3A to 3I, the control unit 5 applies a voltage of opposite polarity from the switching circuit 1 and the rectifying circuit 2 to the first winding N1 and the second winding N2 of the transformer. The switching element is controlled so as to include a charging period Tp that increases the current of the resonance capacitor Cr in the direction of increasing the absolute voltage value of the resonance capacitor Cr.

The control of the control unit 5 further has the following configuration.
The control unit 5 controls the charging period Tp to further include a period for supplying energy from the rectifier circuit 2 to the second winding N2.

Further, the control unit 5 turns off the switching element in which the rectifier circuit 2 is on during the period when the current of the resonant inductor is larger than the exciting current of the transformer, after the current of the resonant inductor falls below the exciting current of the transformer.

Further, the control unit 5 turns off the switching element in the ON state of the rectifier circuit 2 after the polarity of the current of the second winding changes.

Further, the control unit 5 turns on two of the switching elements Q5, Q6, Q7, and Q8 while the current of the second winding is flowing, and the polarity of the current of the second winding N2 changes. One of the two switching elements is turned off before the time t2, and the other of the two switching elements is controlled to be turned off after the polarity of the current of the second winding N2 is changed.

As described above, in the resonance type power supply device 10 of the present embodiment, the control unit 5 applies a voltage of opposite polarity from the switching circuit 1 and the rectifying circuit 2 to the first winding N1 and the second winding N2 of the transformer T. By providing a charging period Tp that increases the current of the resonance capacitor Cr in the direction of increasing the absolute voltage value of the resonance capacitor Cr, the resonance capacitor Cr can be charged to a higher voltage even when the output current is large, and the voltage is higher. The output voltage can be obtained.

Further, during this charging period Tp, the energy of the smoothing capacitor C2 is supplied from the rectifier circuit 2 to the second winding N2 so that a higher output voltage can be obtained.

Depending on the input / output voltage / current conditions and the length of the charging period Tp, the polarity of the current IN2 flowing through the second winding N2 may not be reversed during the charging period Tp. In this case, the switching elements Q1 and Q4 are turned off in the middle of the mode a4, and the modes a5 and the mode a6 do not exist. However, the mode a4 is a period constituting the charging period Tp, and the effect of the present invention is effective. can get.

FIG. 4 is a graph illustrating the operation of the resonance type power supply device, and shows how to determine the charging period Tp. When the output voltage is high or the output current is large, the charging period Tp is lengthened. Even when the input voltage drops, it is necessary to increase the boost ratio obtained by dividing the output voltage by the input voltage. Therefore, the charging period Tp may be lengthened as in the case where the output voltage is high.

The control unit 5 controls to increase the charging period Tp as the voltage supplied to the load or the current supplied to the load increases. Alternatively, the control unit 5 controls so that the charging period Tp is increased as the voltage input to the switching circuit 1 decreases.

More specifically, when the desired output voltage is high, the output current is large, or the input voltage is low, the control unit 5 controls to lower the switching frequency and raise the output voltage. When the desired output voltage cannot be obtained even if the switching frequency is lowered, the control unit 5 increases the charging period Tp. Specifically, as shown in FIG. 2, the control unit 5 controls the switching element so as to lengthen the period from turning off the switching element Q8 to turning off the switching elements Q1 and Q4.

Here, the charging period Tp is a period from the output of the voltage having the opposite polarity to that of the switching circuit 1 from the rectifier circuit 2 until the polarity of the output voltage of the switching circuit 1 is switched. The period up to time t6 and from time t12 to t14. Practically, the voltage having the opposite polarity to that of the switching circuit 1 may be output from the rectifier circuit 2 at a time earlier than the time when the polarity of the output voltage of the switching circuit 1 is switched by the charging period Tp.

In the above description of the circuit operation, the switching element Q5 is turned off before the switching element Q8, but the operations of these two switching elements may be interchanged. Similarly, in FIG. 2, the switching element Q7 is turned off before the switching element Q6, but the operations of these two switching elements may also be interchanged.

Further, in this embodiment, the operation of feeding power from the smoothing capacitor C1 side to the smoothing capacitor C2 side has been described, but if the operations of the switching circuit 1 and the rectifier circuit 2 are exchanged, power is supplied from the smoothing capacitor C2 side to the smoothing capacitor C1 side. In that case, the effect of the present invention can be obtained.

FIG. 5 is a circuit configuration diagram of the resonance type power supply device 20 in the second embodiment. The resonance type power supply device 20 is connected between the DC power supply 13 and the load 14, and supplies power from the DC power supply 13 to the load 14. The control unit 5, the voltage sensor 6, the voltage sensor 7, and the current sensor 8 connected to the control unit 5 and the control unit 5 shown in FIG. 1 are omitted in FIG. In the second embodiment, the control unit 5, the voltage sensor 6, the voltage sensor 7, and the current sensor 8 perform the same functions as those in the first embodiment.

The resonance type power supply device 20 includes a switching circuit 11, a rectifier circuit 12, a smoothing capacitor C11 connected in parallel to the DC power supply 13, a smoothing capacitor C12 connected in parallel to the load 14, and resonance capacitors Cr1 and Cr2. It is provided with a resonance inductor Lr1.

The switching circuit 11 includes a switching element Q11 and a switching element Q12 connected in series between both ends of the smoothing capacitor C11. As described above, the resonance type power supply device 20 is different from the resonance type power supply device 10 of the first embodiment in that the circuit method is a half bridge.

Further, the rectifier circuit 12 is different from the rectifier circuit 2 of the first embodiment in that the number of switching elements is reduced from 4 to 2. In Example 1, it has been described that the polarity of the current IN2 flowing through the second winding N2 may not be reversed during the charging period Tp depending on the input / output voltage / current conditions and the length of the charging period Tp.

In this case, in the state where the switching elements Q5 and Q7 are on, there is no period in which the current flows in the forward direction through the switching elements Q5 and Q7, so that the switching elements Q5 and Q7 can be omitted. The rectifier circuit 12 of the second embodiment has a circuit configuration in which the switching elements corresponding to the switching elements Q5 and Q7 in the rectifier circuit 2 of the first embodiment are omitted.

In the second embodiment as shown in FIG. 5, the rectifier circuit 12 has a first diode D15 and a first switching element Q13 connected in series by a first node between both ends of the smoothing capacitor C12, and between both ends of the smoothing capacitor C12. The second diode D16 and the second switching element Q14 connected in series at the second node, and the first antiparallel diode D13 and the second antiparallel diode D13 and the second switching element Q13 connected in antiparallel to the first switching element Q13 and the second switching element Q14, respectively. The antiparallel diode D14 is provided, one end of the second winding N12 is connected to the first node, and the other end of the second winding N12 is connected to the second node.

Then, the control unit turns on one of the first switching element Q13 and the second switching element Q14 while the current of the second winding N12 is flowing, and the polarity of the current of the second winding N12 changes. Turn off the one that was turned on later.

Other configurations and circuit operations are the same as those of the resonant power supply device 10 of the first embodiment. The resonance type power supply device 20 of the present embodiment has an effect of cost reduction by reducing the number of switching elements as compared with the resonance type power supply device 10 of the first embodiment.

As described above, in the resonant power supply device of the present embodiment, the input voltage and the output voltage are connected in series via a transformer, and the total voltage is applied to the resonant circuit to increase the voltage of the resonant capacitor. It is charged to a high output voltage. According to the present invention, it is possible to suppress an increase in the secondary winding ratio of the transformer, and it is possible to improve the efficiency when the output voltage is not high.

Further, in the embodiment, a full bridge circuit and a half bridge circuit have been described as switching circuits, but the same effect can be obtained by changing to another circuit method such as a single-ended push-pull circuit or a push-pull circuit. be able to.

The present invention requires an isolated DC-DC conversion function, and can be applied to an application in which the range of change of the input voltage or the output voltage is relatively wide to obtain an effect. For example, converters that convert the power of solar cells and fuel cells, power supplies for information devices such as servers, DC-DC converters for chargers and auxiliary equipment of electric vehicles, contactless power supply devices, power supplies for X-ray tubes and processing machines. It can be widely applied to resonance type power supply devices such as bidirectional converters for power supplies, battery charging / discharging and solid state transformers.

10, 20 ... Resonant power supply,
1, 11 ... Switching circuit,
2, 12 ... Rectifier circuit,
3, 13 ... DC power supply,
4, 14 ... load,
5 ... Control unit,
6, 7 ... Voltage sensor,
8 ... Current sensor

Claims (10)

A switching circuit that inputs a DC voltage and applies an AC voltage to the first winding via a resonant capacitor.
A rectifier circuit that rectifies the current flowing in the second winding and outputs it between both ends of the smoothing capacitor,
A transformer that magnetically couples the first winding and the second winding,
It has a control unit that controls the switching element in the switching circuit and the rectifier circuit.
A resonance type power supply device that outputs DC power to a load from between both ends of the smoothing capacitor.
The control unit
A resonance type power supply device that controls the switching element so as to include a charging period in which the current of the resonance capacitor is increased in a direction of increasing the absolute voltage value of the resonance capacitor. In the resonance type power supply device according to claim 1,
The control unit
A resonance type power supply device that controls so that the charging period further includes a period for supplying energy from the rectifier circuit to the second winding. In the resonance type power supply device according to claim 1,
The control unit
A resonance type power supply device that controls to increase the charging period as the voltage supplied to the load or the current supplied to the load increases. In the resonance type power supply device according to claim 1,
The control unit
A resonance type power supply device that controls to increase the charging period as the voltage input to the switching circuit decreases. In the resonance type power supply device according to claim 1,
A resonance type power supply device including a leakage inductance component of the transformer in series with the first winding, or a resonance inductor composed of an inductor in series with the first winding. In the resonance type power supply device according to claim 5.
The control unit
A resonance type power supply device that turns off the switching element in which the rectifying circuit is on during a period in which the current of the resonant inductor is larger than the exciting current of the transformer after the current of the resonant inductor falls below the exciting current of the transformer. In the resonance type power supply device according to claim 1,
The control unit
A resonance type power supply device that turns off the switching element, which is in the ON state of the rectifier circuit, after the polarity of the current of the second winding changes. In the resonance type power supply device according to claim 1,
The rectifier circuit
The first switching element and the second switching element connected in series by the first node between both ends of the smoothing capacitor,
A third switching element and a fourth switching element connected in series by a second node between both ends of the smoothing capacitor,
A first antiparallel diode, a second antiparallel diode, a third antiparallel diode, and a fourth antiparallel diode connected in antiparallel to each of the first switching element and the fourth switching element are provided. ,
One end of the second winding is connected to the first node and the other end of the second winding is connected to the second node.
The control unit
During the period in which the current of the second winding is flowing, two switching elements from the first switching element to the fourth switching element are turned on.
One of the two switching elements is turned off before the polarity of the current of the second winding changes.
A resonant power supply that turns off the other of the two switching elements after the polarity of the current in the second winding changes. In the resonance type power supply device according to claim 1,
The rectifier circuit
A first diode and a first switching element connected in series by a first node between both ends of the smoothing capacitor,
A second diode and a second switching element connected in series by a second node between both ends of the smoothing capacitor,
A first antiparallel diode and a second antiparallel diode connected in antiparallel to the first switching element and the second switching element, respectively, are provided.
One end of the second winding is connected to the first node and the other end of the second winding is connected to the second node.
The control unit
While the current of the second winding is flowing, one of the first switching element and the second switching element is turned on.
A resonance type power supply device that turns off one of the turned-on states after the polarity of the current of the second winding changes. In the resonance type power supply device according to claim 8,
The rectifier circuit
DC power is input from between both ends of the smoothing capacitor,
A resonance type power supply device that outputs DC power from the switching circuit.

Images