JP7021568B2 - Converter device - Google Patents

Description

The present invention relates to a converter device that converts an input DC voltage into an output DC voltage and outputs the voltage.

As a converter device of this type, a converter device (current resonance type DC-DC converter) disclosed in Non-Patent Document 1 below is known. In this converter device, the converter device that normally functions as an LC resonance circuit equivalently to the input voltage (input voltage) and the load (the load that supplies the voltage converted in this converter device) are connected in series. It is configured to be in the state of being. Further, in this converter device, the impedance of this converter device that functions as an LC resonance circuit can be changed by changing the operating frequency (switching frequency). For this reason, in this converter device, the voltage (output voltage) supplied to the load is stabilized by changing the operating frequency.

However, in a configuration such as this converter device that changes the operating frequency to stabilize the output voltage, switching loss and loss in magnetic components such as transformers are required when the operating frequency must be increased depending on the operating conditions. The problem arises that the number increases.

This problem can be improved by adopting the configuration of the converter device (current resonance type DC-DC converter) disclosed in Non-Patent Document 2 below. Specifically, this converter device is configured as a two-stage converter composed of a booster circuit and a current resonance converter that operates at a fixed frequency (constant switching frequency), and controls the switching operation of the booster circuit (PWM). By controlling), the DC voltage supplied from the booster circuit to the current resonance converter can be changed. For this reason, in this converter device, it is possible to stabilize the voltage (output voltage) supplied to the load while avoiding an increase in switching loss in the current resonance converter and loss in the magnetic component.

ROBERT L. STEIGERWALD, "A Comparison of Half-Bridge Resonant Converter Topologies", IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 3, NO. 2, APRIL 1988 Jun-Ho Kim, 3 others, "Analysis and Design of Boost-LLC Converter for High Power Density AC-DC Adapter", 2013 IEEE, [online], [Search on February 15, 2018], Internet <URL: http://koasas.kaist.ac.kr/bitstream/10203/187705/1/77644.pdf>

However, the converter device disclosed in Non-Patent Document 2 described above has the following problems to be solved. That is, in this converter device, since the booster circuit has a diode, a recovery loss due to this diode occurs in this converter device, and there is a problem that this recovery loss is generally large.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a one-stage type converter device capable of controlling an output voltage without changing a switching frequency.

In order to achieve the above object, the converter device according to the present invention is described above via a transformer in which the first winding and the second winding are formed, a pair of first DC terminal portions, and a pair of first connection lines. A pair of first AC terminals connected to the first winding, a pair of second DC terminals, and a pair of second AC terminals connected to the second winding via a pair of second connection lines. It is composed of a unit and a first switch and a second switch connected to each other by the first AC terminal portion of one of the pair of first AC terminal portions, and one end portion on the first switch side is the first. The pair is connected to the first DC terminal portion of one of the pair of first DC terminal portions via one power line, and the other end portion on the second switch side is connected to the other end portion on the second switch side via the second power line. A series switch unit connected to the other first DC terminal unit of the first DC terminal unit and an inductor inserted and connected to at least one of the first power line and the second power line are connected in series. It is composed of a third switch and a first capacitor, one end of which is connected to the one end of the series switch portion, and the other end of the pair of first AC terminal portions. It is composed of a first series circuit unit connected to the other first AC terminal unit, a fourth switch and a second capacitor connected in series, and one end is connected to the other first AC terminal unit. And the other end is arranged between the second series circuit part connected to the other end of the series switch part, the pair of second AC terminal parts, and the pair of second DC terminal parts. A rectifying smoothing unit provided, an LC resonance circuit inserted and connected to at least one of the pair of first connection lines and the pair of second connection lines, and switching control from the first switch to the fourth switch. Is provided with a control unit that converts the input DC voltage input to the pair of first DC terminal units into an output DC voltage and outputs the output from between the pair of second DC terminal units. By executing the switching control, only the fourth switch among the fourth switches is turned off from the first switch, thereby storing energy in the inductor based on the input DC voltage. At the same time, in the first operation of supplying a current to the first winding by releasing the energy stored in the first capacitor, only the second switch among the fourth switches is turned off from the first switch. By making it in a state, the first A second that supplies a current to the first winding by discharging the energy stored in the capacitor and stores energy in the second capacitor based on the input DC voltage and the energy discharged from the inductor. Operation, by turning off only the third switch of the fourth switch from the first switch, energy is stored in the inductor based on the input DC voltage and is stored in the second capacitor. The third operation of supplying a current to the first winding by releasing the current energy, and turning off only the first switch among the fourth switches from the first switch causes the first switch. A current is supplied to the first winding by discharging the energy stored in the two capacitors, and the energy is stored in the first capacitor based on the input DC voltage and the energy discharged from the inductor. The four operations are repeatedly executed by the series switch unit, the first series circuit unit, and the second series circuit unit .

As a result, the booster circuit, which is indispensable for the two-stage converter described in the prior art, can be configured as a one-stage type that does not require it, so that the recovery loss generated in the diode of this booster circuit can be eliminated. can. Further, the output DC voltage can be controlled by changing the on-duty of the first switch and the second switch (that is, the output DC voltage can be controlled without changing the switching frequency of the first switch to the fourth switch. can do).

In the converter device according to the present invention, the first switch to the fourth switch are composed of FETs having a built-in body diode. As a result, when shifting each switch from the OFF state to the ON state, the switch is switched to the ON state with a current flowing through the body diode (that is, the drain-source voltage is switched to the ON state when the voltage is close to zero volt. Since the transition (zero volt switching) is possible, the turn-on loss at each switch can be reduced.

Further, the converter device according to the present invention is connected to the first winding via a transformer in which the first winding and the second winding are formed, a pair of first DC terminal portions, and a pair of first connection lines. A pair of connected first AC terminal portions, a pair of second DC terminal portions, a pair of second AC terminal portions connected to the second winding via a pair of second connection lines, and the pair. It is composed of a first switch and a second switch connected to each other by the first AC terminal portion of one of the first AC terminal portions of the above, and one end portion on the first switch side is via the first power line. The pair of first DC terminal portions is connected to one of the first DC terminal portions, and the other end portion on the second switch side is connected to the first DC terminal portion via the second power line. A first series switch unit connected to the other first DC terminal unit, an inductor inserted and connected to at least one of the first power line and the second power line, and the pair of first units. It is composed of a third switch and a fourth switch connected to each other by the other first AC terminal portion of the AC terminal portions, and one end portion on the third switch side is the first switch via the fifth switch. A second series switch unit connected to one end of the series switch unit and having the other end on the fourth switch side connected to the other end of the first series switch unit via the sixth switch. A capacitor connected in parallel to the second series switch section, a rectifying smoothing section disposed between the pair of second AC terminal sections and the pair of second DC terminal sections, and the pair of second AC terminals. The pair of first alternating currents by executing switching control from the first switch to the sixth switch with an LC resonance circuit inserted and connected to at least one of the one connection line and the pair of second connection lines. The control unit includes a control unit that converts an input DC voltage input to the terminal unit into an output DC voltage and outputs the output from between the pair of second DC terminal units. By turning off only the third switch and the sixth switch among the sixth switches from the first switch, energy is stored in the inductor and stored in the capacitor based on the input DC voltage. The first operation of supplying an electric current to the first winding by releasing the current energy, turning off only the second switch and the third switch among the sixth switches from the first switch. By A second operation of supplying a current to the first winding based on the input DC voltage and the energy emitted from the inductor while accumulating energy in the capacitor, among the first switch to the sixth switch. By turning off only the 4th switch and the 5th switch, energy is stored in the inductor based on the input DC voltage, and the energy stored in the capacitor is discharged, so that the first switch is released. While accumulating energy in the capacitor by the third operation of supplying a current to the winding and by turning off only the first switch and the fourth switch among the first switch to the sixth switch. , The first series switch section, the second series switch section, the fifth switch, and the fourth operation of supplying a current to the first winding based on the input DC voltage and the energy emitted from the inductor. The sixth switch is repeatedly executed .

As a result, the booster circuit, which is indispensable for the two-stage converter described in the prior art, can be configured as a one-stage type that does not require it, so that the recovery loss generated in the diode of this booster circuit can be eliminated. can. Further, the output DC voltage can be controlled by changing the on-duty of the first switch and the second switch (that is, the output DC voltage can be controlled without changing the switching frequency of the first switch to the sixth switch. can do).

In the converter device according to the present invention, the first switch to the sixth switch are composed of FETs having a built-in body diode. As a result, when shifting each switch from the OFF state to the ON state, the switch is switched to the ON state with a current flowing through the body diode (that is, the drain-source voltage is switched to the ON state when the voltage is close to zero volt. Since the transition (zero volt switching) is possible, the turn-on loss at each switch can be reduced.

According to the present invention, the output DC voltage can be controlled by changing the on-duty of each switch arranged on the first winding side (that is, the output without changing the switching frequency of these switches). Since the voltage can be controlled) and the 1-stage type that does not require the booster circuit that is indispensable for the 2-stage converter described in the prior art, the recovery loss that occurs in the diode of this booster circuit can be eliminated. ..

It is a block diagram of the converter device 1A. It is a waveform diagram for demonstrating the operation of the converter apparatus 1A. It is a block diagram for demonstrating the operation in the period T1 in FIG. 2 of a converter apparatus 1A. It is a block diagram for demonstrating the operation in the period T2 in FIG. 2 of a converter apparatus 1A. It is a block diagram for demonstrating the operation in the period T3 in FIG. 2 of a converter apparatus 1A. It is a block diagram for demonstrating the operation in the period T4 in FIG. 2 of a converter apparatus 1A. It is a block diagram of the converter device 1B. It is a waveform diagram for demonstrating the operation of the converter apparatus 1B. It is a block diagram of the 1st winding 2a side for demonstrating the operation in the period T1 in FIG. 8 of a converter apparatus 1B. It is a block diagram of the 1st winding 2a side for demonstrating the operation in the period T2 in FIG. 8 of a converter apparatus 1B. It is a block diagram of the 1st winding 2a side for demonstrating the operation in the period T3 in FIG. 8 of a converter apparatus 1B. It is a block diagram of the 1st winding 2a side for demonstrating the operation in the period T4 in FIG. 8 of a converter apparatus 1B.

Hereinafter, embodiments of the converter device will be described with reference to the drawings.

First, the configuration of the converter device 1A as an example of the converter device will be described with reference to FIG. The converter device 1A includes a transformer 2, a pair of first DC terminal portions 3a and 3b, a pair of first AC terminal portions 4a and 4b, a pair of second DC terminal portions 5a and 5b, and a pair of second AC terminal portions 6a. , 6b, series switch section 7, inductor 8, first series circuit section 9, second series circuit section 10, rectifying smoothing section 11, LC resonance circuit 12, and control section 13, and a pair of first DC terminal sections 3a. , 3b The input DC voltage Vin (in this example, as an example, it is assumed to be the voltage output from the DC power supply PS as shown in FIG. 1) is converted into the output DC voltage Vout to form a pair of firsts. 2 It is configured to be able to supply to the load LD connected to the DC terminal portions 5a and 5b.

Specifically, the transformer 2 is, as an example in this example, two windings (first winding 2a and second winding 2b) formed on a common magnetic core (not shown) and magnetically coupled to each other. ) Is provided. The pair of first AC terminal portions 4a and 4b are connected to the first winding 2a via the pair of first connection lines L1a and L1b. Further, in this example, the LC resonance circuit 12 is inserted and connected to the first connection lines L1a and L1b. Specifically, in this example, the LC resonance circuit 12 is configured to include a resonance capacitor 12a inserted and connected to the first connection line L1a and a resonance inductor 12b inserted and connected to the first connection line L1b. There is. Therefore, in this example, the first AC terminal portion 4a is connected to one end of the first winding 2a via the first connection line L1a to which the resonance capacitor 12a is inserted and connected, and the first AC terminal portion 4b is , The resonance inductor 12b is connected to the other end of the first winding 2a via the first connection line L1b to which the resonance inductor 12b is inserted and connected. Regarding the resonance capacitor 12a and the resonance inductor 12b, instead of this configuration, although not shown, the resonance capacitor 12a is inserted and connected to the first connection line L1b, and the resonance inductor 12b is inserted and connected to the first connection line L1a. It can also be configured.

The pair of second AC terminal portions 6a and 6b are connected to the second winding 2b via the pair of second connection lines L2a and L2b. In this example, the LC resonance circuit 12 is inserted and connected to the first connection lines L1a and L1b as described above, but the present invention is not limited to this configuration, and the first connection lines L1a and L1b and the second connection line L1a and L1b are not limited to this. It suffices if it is inserted and connected to at least one of the connection lines L2a and L2b.

The series switch section 7 is a first switch 7a and a second switch 7b connected to each other by the first AC terminal section (in this example, the first AC terminal section 4a) of the first AC terminal sections 4a and 4b. It is composed of a series circuit of. In this example, as an example, the first switch 7a and the second switch 7b are both composed of an n-channel type FET (field effect transistor having a built-in body diode), and the source terminal of the first switch 7a and the second switch 7b. The drain terminal of is connected by the first AC terminal portion 4a. Further, one end of this series circuit (the end on the side of the first switch 7a; the drain terminal of the first switch 7a in this example) is a pair of first DC terminal portions 3a, via the first power line Lp1. It is connected to one of the first DC terminal portions (in this example, the first DC terminal portion 3a) of 3b. Further, the other end of this series circuit (the end on the side of the second switch 7b; the source terminal of the second switch 7b in this example) is a pair of first DC terminal portions 3a, via the second power line Lp2. It is connected to the other first DC terminal portion of 3b (in this example, the first DC terminal portion 3b).

The inductor 8 is inserted and connected to at least one of the first power line Lp1 and the second power line Lp2. In this example, as an example, the inductor 8 is inserted and connected to the first power line Lp1, but although not shown, it may be configured to be inserted and connected to the second power line Lp2, or the first power line. The configuration may be such that both Lp1 and the second power line Lp2 are separately inserted and connected.

The first series circuit unit 9 is composed of a third switch 9a and a first capacitor 9b connected in series. In this example, as an example, the third switch 9a is composed of an n-channel type FET (field effect transistor having a built-in body diode), and the drain terminal of the third switch 9a and one terminal of the first capacitor 9b are connected to each other. It is connected. Further, in the first series circuit unit 9, one end (source terminal of the third switch 9a in this example) is connected to one end of the series switch 7 (drain terminal of the first switch 7a in this example). At the same time, the other end (the other terminal of the first capacitor 9b in this example) is the other first AC terminal part (in this example, the first AC) of the pair of first AC terminal parts 4a and 4b. It is connected to the terminal portion 4b). Instead of this configuration, the first series circuit unit 9 has a first capacitor 9b arranged on one end side of the series switch unit 7, and a third switch 9a on the first AC terminal unit 4b side. The configuration may be arranged in the same direction.

The second series circuit unit 10 is composed of a fourth switch 10a and a second capacitor 10b connected in series. In this example, as an example, the fourth switch 10a is composed of an n-channel type FET (field effect transistor having a built-in body diode), and the source terminal of the fourth switch 10a and one terminal of the second capacitor 10b are connected to each other. It is connected. Further, in the second series circuit unit 10, one end portion (the other terminal of the second capacitor 10b in this example) is connected to the other first AC terminal portion (in this example, the first AC terminal portion 4b). At the same time, the other end (drain terminal of the fourth switch 10a in this example) is connected to the other end of the series switch portion 7 (source terminal of the second switch 7b in this example). Instead of this configuration, the second series circuit unit 10 has a fourth switch 10a arranged in the same direction on the first AC terminal unit 4b side and a second switch 10a on the other end side of the series switch unit 7. The configuration may be such that the capacitor 10b is arranged.

The rectifying smoothing portion 11 is arranged between the pair of second AC terminal portions 6a and 6b and the pair of second DC terminal portions 5a and 5b. With this configuration, the rectifying smoothing section 11 converts the voltage induced in the second winding 2b (induced voltage V2 which is an AC voltage) into the output DC voltage Vout between the pair of second DC terminal sections 5a and 5b. Output. In this example, as an example, the rectifying smoothing unit 11 includes a rectifying circuit (bridge type full-wave rectifying circuit) composed of four diodes 11a, 11b, 11c, and 11d and a capacitor 11e, as shown in FIG. There is. Specifically, the anode terminal of the diode 11a and the cathode terminal of the diode 11b are connected by the second AC terminal portion 6a, the anode terminal of the diode 11c and the cathode terminal of the diode 11d are connected by the second AC terminal portion 6b, and the diode. Each cathode terminal of the diode 11a and the diode 11c is connected to the second DC terminal portion 5a, and each anode terminal of the diode 11b and the diode 11d is connected to the second DC terminal portion 5b. Further, the capacitor 11e is connected between the cathode terminal of the diode 11c and the anode terminal of the diode 11d (that is, between the second DC terminal portions 5a and 5b).

The control unit 13 executes switching control for these four switches 7a to 10a by outputting drive signals S1, S2, S3, and S4 to each of the four switches from the first switch 7a to the fourth switch 10a. Then, the operation of converting the input DC voltage Vin into the AC voltage V1 and outputting it between the first AC terminal units 4a and 4b is performed by the circuit on the first winding 2a side (series switch unit 7, inductor 8, first series circuit). It is executed by a power conversion circuit (a power conversion circuit composed of a unit 9 and a second series circuit unit 10). In this example, since each switch from the first switch 7a to the fourth switch 10a is composed of FETs as described above, the control unit 13 is an appropriate drive circuit (not shown) for each of the switches 7a to 10a. The corresponding drive signal among the drive signals S1 to S4 is output as a positive voltage signal based on the potential of the source terminal between the gate and the source of each switch 7a to 10a.

Next, the operation of the converter device 1A will be described with reference to FIGS. 1 to 6.

The control unit 13 repeatedly outputs the drive signals S1 to S4 from the first switch 7a to the fourth switch 10a, with the output state from the period T1 to the period T4 shown in FIG. 2 as one cycle. Note that "ON" and "OFF" in FIG. 2 indicate ON / OFF states of the switches 7a to 10a corresponding to the drive signals S1 to S4. Hereinafter, the operation will be described separately for each period T1, T2, T3, and T4.

First, in the period T1, as shown in FIG. 2, the drive signal S1 is switched from zero volt (an example of a voltage lower than the gate threshold voltage) to a positive voltage (a voltage equal to or higher than the gate threshold voltage), thereby showing in FIGS. As described above, the first switch 7a shifts from the OFF state to the ON state. Further, as shown in FIG. 2, the drive signal S4 is switched from the positive voltage to zero volt, so that the fourth switch 10a shifts from the ON state to the OFF state as shown in FIGS. 2 and 3. Further, since the other drive signals S2 and S3 are maintained at a positive voltage as shown in FIG. 2, the second switch 7b and the third switch 9a continue to be in the ON state as shown in FIGS. 2 and 3. That is, only the fourth switch 10a is turned off.

In this case, in the circuit on the first winding 2a side (first DC terminal portions 3a, 3b side), the fourth switch 10a first shifts to the OFF state, and then the first switch 7a shifts to the ON state. Therefore, immediately before the first switch 7a shifts to the ON state, the current Ie flowing in the first winding 2a in the period T4 is the resonance capacitor 12a and the body die of the first switch 7a in the OFF state as described later. , In the current path returning to the first winding 2a via the third switch 9a, the first capacitor 9b, and the resonant inductor 12b in the ON state, as shown in FIG. 3, the direction opposite to the direction shown in the figure as the current Ib. Flow to. Therefore, the first switch 7a shifts to the ON state (zero-volt switching) in a state where the current Ib is flowing through the body diode, that is, in a state where the drain-source voltage is close to zero volt. Therefore, the turn-on loss in the first switch 7a is significantly reduced.

Further, when the fourth switch 10a shifts to the OFF state, the charging of the first capacitor 9b (accumulation of energy in the first capacitor 9b) executed as described later in the period T4 is completed, and then the first capacitor 9b is charged. When the switch 7a shifts to the ON state, the current can flow in the direction opposite to this direction (direction shown in FIG. 3) in the above current path in which the current Ib is flowing in the above direction. .. Therefore, by releasing the energy stored in the first capacitor 9b, the current Ib is connected to the current path from the first capacitor 9b to the third switch 9a, the first switch 7a in the ON state, and the resonance capacitor 12a. The current flows in the direction of returning to the first capacitor 9b (direction shown in FIG. 3) via the first winding 2a and the resonant inductor 12b. Since the LC resonance circuit 12 (resonance capacitor 12a and resonance inductor 12b) is included in this current path, the waveform of the current Ib (current of the third switch 9a) is a resonance waveform (sine wave shape) as shown in FIG. Waveform). Further, since the current Ib flows through the first winding 2a in the direction shown in FIG. 3, the diodes 11a and 11b are connected to the connection points (second AC terminal portion 6b) of the diodes 11c and 11d in the second winding 2b. A voltage (induced voltage V2) at which the connection point (second AC terminal portion 6a) of the above becomes a high potential is induced.

Further, when the first switch 7a shifts to the ON state together with the second switch 7b in the ON state, the DC power supply PS (input DC voltage Vin) is short-circuited via the inductor 8. As a result, as shown in FIG. 3, another current path is formed from the DC power supply PS to the DC power supply PS via the inductor 8, the first switch 7a, and the second switch 7b, and the current Ia is formed in this current path. Flows in the direction indicated by the arrow in FIG. Therefore, when this current Ia flows through the inductor 8, energy is stored in the inductor 8. Further, since the currents Ia and Ib flow in the same direction in the first switch 7a where these two current paths overlap, the combined current (Ia + Ib) of the currents Ia and Ib flows.

As described above, in the period T1, the circuit on the first winding 2a side (that is, the series switch section 7, the first series circuit section 9 and the second series circuit section 10) is connected to the inductor 8 based on the input DC voltage Vin. The first operation of supplying the current Ib to the first winding 2a is executed by accumulating the energy and releasing the energy stored in the first capacitor 9b.

On the other hand, in the circuit on the second winding 2b side (second DC terminal portions 5a, 5b side), the inflow of the current Ib into the first winding 2a described above (inflow in the direction shown in FIG. 3) is caused. Since the induced voltage V2 at which the second AC terminal portion 6a has a high potential with respect to the second AC terminal portion 6b is induced in the second winding 2b, as shown in FIG. 3, based on this induced voltage V2, the second A current Ic flows from the 2 windings 2b to the current path returning to the 2nd winding 2b via the diode 11a, the load LD, and the diode 11d (the output DC voltage Vout is output to the load LD).

Then, in the period T2, as shown in FIG. 2, the drive signal S2 is switched from the positive voltage to the zero voltage, and the drive signal S4 is switched from the zero voltage to the positive voltage, so that the second switch 7b is switched as shown in FIGS. Shifts from the ON state to the OFF state, and the fourth switch 10a shifts from the OFF state to the ON state. Since the corresponding drive signal is the same as that in the period T1, each of the other switches continues the ON / OFF state in the period T1. That is, only the second switch 7b is turned off.

In this case, in the circuit on the first winding 2a side, the second switch 7b first shifts to the OFF state, and then the fourth switch 10a shifts to the ON state. Therefore, immediately before the fourth switch 10a shifts to the ON state, the voltage across the inductor 8 (the voltage applied to the inductor 8 in the period T1) is added to the voltage of the DC power supply PS (input DC voltage Vin), that is, the voltage applied to the inductor 8. The application of the voltage to which the input DC voltage (voltage equivalent to Vin) is added to the first series circuit unit 9 and the second series circuit unit 10 is started. As a result, in addition to the energy from the DC power supply PS, the energy emitted from the inductor 8 causes the inductor 8 from the DC power supply PS, the third switch 9a in the ON state, the first capacitor 9b, and the first capacitor 9b, as shown in FIG. The current Id flows in the direction shown in FIG. 4 in the current path returning to the DC power supply PS via the body diode of the 2nd capacitor 10b and the 4th switch 10a in the OFF state. Therefore, the fourth switch 10a shifts to the ON state (zero-volt switching) in a state where the current Id is flowing through the body diode, that is, in a state where the drain-source voltage is close to zero volt. Therefore, the turn-on loss in the fourth switch 10a is significantly reduced.

Further, the second capacitor 10b is charged with the energy emitted from both the DC power supply PS and the inductor 8 by the current Id flowing in this way (energy is stored in the second capacitor 10b).

Further, since the ON state of the first switch 7a and the third switch 9a is continued, as shown in FIG. 4, the same current path as in the period T1 (from the first capacitor 9b to the third switch 9a, the first switch). The current Ib continuously flows through 7a, the resonance capacitor 12a, the first winding 2a, and the current path returning to the first capacitor 9b via the resonance inductor 12b), and the discharge of the first capacitor 9b (from the first capacitor 9b). The release of energy) is continued.

Further, since the currents Ib and Id flow in the opposite directions to the first series circuit unit 9 (third switch 9a and the first capacitor 9b) where these two current paths overlap, the combined currents (Ib-) of the currents Ib and Id flow. Id) flows to the third switch 9a. Further, the current Ia that was flowing in the period T1 does not flow in the first switch 7a, and only the current Ib flows (that is, a current that is smaller by this current Ia than in the period T1 flows).

As described above, in the period T2, the circuit on the first winding 2a side (that is, the series switch unit 7, the first series circuit unit 9 and the second series circuit unit 10) has the energy stored in the first capacitor 9b. (While supplying the current Ib to the first winding 2a), the second operation of accumulating the energy in the second capacitor 10b based on the input DC voltage Vin and the energy emitted from the inductor 8 is executed.

On the other hand, in the circuit on the second winding 2b side, the current Ib continuously flows into the first winding 2a in the same direction as described above, and therefore, between the second AC terminal portions 6a and 6b. Since the induced voltage V2 is continuously induced with the same polarity, as shown in FIG. 4, the current Ic continuously flows in the same current path as in the period T1 (output DC voltage Vout to the load LD). Output continues).

Subsequently, in the period T3, the drive signal S2 is switched from zero volt to a positive voltage as shown in FIG. 2, and as shown in FIGS. 2 and 5, the second switch 7b shifts from the OFF state to the ON state. .. Further, as shown in FIG. 2, when the drive signal S3 is switched from the positive voltage to zero volt, the third switch 9a shifts from the ON state to the OFF state as shown in FIGS. 2 and 5. Since the corresponding drive signal is the same as that in the period T2, each of the other switches continues the ON / OFF state in the period T2. That is, only the third switch 9a is turned off.

In this case, in the circuit on the first winding 2a side, the third switch 9a first shifts to the OFF state, and then the second switch 7b shifts to the ON state. Therefore, immediately before the second switch 7b shifts to the ON state, the current Ib flowing in the first winding 2a in the period T2 is the resonant inductor 12b, the second capacitor 10b, the fourth switch 10a in the ON state, and the OFF state. As shown in FIG. 5, the current Ie flows in the direction opposite to the direction shown in the figure in the body die of the second switch 7b and the current path returning to the first winding 2a via the resonance capacitor 12a. Therefore, the second switch 7b shifts to the ON state (zero-volt switching) in a state where the current Ie is flowing through the body diode, that is, in a state where the drain-source voltage is close to zero volt. Therefore, the turn-on loss in the second switch 7b is significantly reduced.

Further, when the third switch 9a shifts to the OFF state, the charging of the first capacitor 9b (accumulation of energy in the first capacitor 9b) executed in the period T2 is completed, and then the second switch 7b By shifting to the ON state, the current can flow in the direction opposite to this direction (direction shown in FIG. 5) in the above current path in which the current Ie is flowing in the above direction. Therefore, by releasing the energy stored in the second capacitor 10b, the current Ie is in the ON state from the second capacitor 10b to the resonance inductor 12b, the first winding 2a, and the resonance capacitor 12a in this current path. The current flows in the direction of returning to the second capacitor 10b (direction shown in FIG. 5) via the second switch 7b and the fourth switch 10a. Since the LC resonance circuit 12 is included in this current path, the waveform of the current Ie (current of the fourth switch 10a) becomes a resonance waveform (sinusoidal waveform) as shown in FIG. Further, since Ie in the direction opposite to the current Ib in the periods T1 and T2 flows in the first winding 2a, the second AC terminal portion 6b is provided in the second winding 2b with respect to the second AC terminal portion 6a. A high potential voltage (induced voltage V2) is induced.

Further, when the second switch 7b shifts to the ON state together with the first switch 7a in the ON state, the DC power supply PS is short-circuited via the inductor 8. As a result, as shown in FIG. 5, another current path is formed from the DC power supply PS to the DC power supply PS via the inductor 8, the first switch 7a, and the second switch 7b, and the current Ia is formed in this current path. Flows in the direction indicated by the arrow in FIG. Therefore, when this current Ia flows through the inductor 8, energy is stored in the inductor 8. Further, since the currents Ia and Ie flow in the same direction in the second switch 7b where these two current paths overlap, the combined current (Ia + Ie) of the currents Ia and Ie flows.

As described above, in the period T3, the circuit on the first winding 2a side (that is, the series switch section 7, the first series circuit section 9 and the second series circuit section 10) is connected to the inductor 8 based on the input DC voltage Vin. The third operation of supplying the current Ie to the first winding 2a is executed by accumulating the energy and releasing the energy stored in the second capacitor 10b.

On the other hand, in the circuit on the second winding 2b side, the second AC terminal portion 6b has a high potential with respect to the second AC terminal portion 6a due to the inflow of the current Ie into the first winding 2a described above. Since the induced voltage V2 is induced in the second winding 2b, based on this induced voltage V2, the second winding 2b is passed through the diode 11c, the load LD and the diode 11b from the second winding 2b as shown in FIG. The current If flows in the current path returning to 2b (the output DC voltage Vout is output to the load LD).

Then, in the period T4, as shown in FIG. 2, the drive signal S1 switches from the positive voltage to the positive voltage, and the drive signal S3 switches from the zero voltage to the positive voltage, so that the first switch 7a is shown in FIGS. Shifts from the ON state to the OFF state, and the third switch 9a shifts from the OFF state to the ON state. Since the corresponding drive signal is the same as that in the period T3, each of the other switches continues the ON / OFF state in the period T3. That is, only the first switch 7a is turned off.

In this case, in the circuit on the first winding 2a side, the first switch 7a first shifts to the OFF state, and then the third switch 9a shifts to the ON state. Therefore, immediately before the third switch 9a shifts to the ON state, the voltage between both ends of the inductor 8 (the voltage applied to the inductor 8 in the period T3, that is, that is, the voltage applied to the inductor 8 in the voltage of the DC power supply PS (input DC voltage Vin). The application of the voltage to which the input DC voltage (voltage equivalent to Vin) is added to the first series circuit unit 9 and the second series circuit unit 10 is started. As a result, in addition to the energy from the DC power supply PS, the energy released from the inductor 8 causes the inductor 8 from the DC power supply PS, the body diode of the third switch 9a in the OFF state, and the first capacitor, as shown in FIG. The current Diode flows in the direction shown in FIG. 6 in the current path returning to the DC power supply PS via 9b, the second capacitor 10b, and the fourth switch 10a in the ON state. Therefore, the third switch 9a shifts to the ON state (zero-volt switching) in a state where the current Id is flowing through the body diode, that is, in a state where the drain-source voltage is close to zero volt. Therefore, the turn-on loss in the third switch 9a is significantly reduced.

Further, the first capacitor 9b is charged with the energy emitted from both the DC power supply PS and the inductor 8 by the current Id flowing in this way (energy is stored in the first capacitor 9b).

Further, since the second switch 7b and the fourth switch 10a continue to be ON, as shown in FIG. 6, the same current path as in the period T3 (from the second capacitor 10b to the resonance inductor 12b, the first winding). 2a, the current Ie continuously flows through the resonance capacitor 12a, the current path returning to the second capacitor 10b via the second switch 7b and the fourth switch 10a in the ON state, and the second capacitor 10b is discharged (second). The release of energy from the capacitor 10b) is continued.

Further, since the currents Id and Ie flow in the opposite directions to the second series circuit unit 10 (fourth switch 10a and second capacitor 10b) where these two current paths overlap, the combined currents (Ie-) of the currents Id and Ie flow. Id) flows to the fourth switch 10a. Further, the current Ia that was flowing in the period T3 does not flow in the second switch 7b, and only the current Ie flows (that is, a current that is smaller by this current Ia than in the period T3 flows).

As described above, in the period T4, the circuit on the first winding 2a side (that is, the series switch unit 7, the first series circuit unit 9 and the second series circuit unit 10) has the energy stored in the second capacitor 10b. (While supplying the current Ie to the first winding 2a), the fourth operation of accumulating the energy in the first capacitor 9b based on the input DC voltage Vin and the energy emitted from the inductor 8 is executed.

On the other hand, in the circuit on the second winding 2b side, the current Ie continuously flows into the first winding 2a in the same direction as described above, and therefore, between the second AC terminals 6a and 6b. Since the induced voltage V2 is continuously induced with the same polarity, as shown in FIG. 6, the current If continues to flow in the same current path as in the period T3 (output DC voltage Vout to the load LD). Output continues).

As a result, one cycle composed of the period T1 to the period T4 is completed.

The output DC voltage Vout is expressed by the following equation. In addition, n is the turn number ratio (Ns / Np) of the first winding 2a (the number of turns Np) and the second winding 2b (the number of turns Ns), and D is the on-duty of the first switch 7a and the second switch 7b. Suppose that
Vout = n × Vin / (2 × (1-D))

As is clear from this equation, in the converter device 1A, the output DC voltage Vout is higher than the input DC voltage Vin by basically setting the on-duty D to a value larger than 0.5, although it depends on the value of n. It functions as a Boost type (boost type) converter that also grows. Further, as is clear from this equation, in the converter device 1A, the output DC voltage Vout is controlled by changing the above-mentioned on-duty D without changing the switching frequency of each switch 7a, 7b, 9a, 10a. It is possible to do.

As described above, in this converter device 1A, the circuit on the first winding 2a side includes the series switch unit 7, the inductor 8, the first series circuit unit 9, and the second series circuit unit 10 together with the first winding 2a. It is connected and configured as shown in 1. Further, the LC resonance circuit 12 is inserted and connected between the first winding 2a and the first AC terminal portions 4a and 4b.

Therefore, according to this converter device 1A, the booster circuit, which is indispensable for the two-stage converter described in the prior art, is configured as a one-stage type that does not require it, so that it is generated by the diode of this booster circuit. Recovery loss can be eliminated. Further, according to this converter device 1A, the output DC voltage Vout can be controlled by changing the on-duty of the first switch 7a and the second switch 7b (that is, the first switch 7a to the fourth switch 10a). The output DC voltage Vout can be controlled without changing the switching frequency of).

Further, in this converter device 1A, all the switches from the first switch 7a to the fourth switch 10a are composed of FETs having a built-in body diode, and the control unit 13 controls the drive signals S1, S2 at the timing shown in FIG. By outputting S3 and S4 and driving all the switches 7a, 7b, 9a and 10a, the first switch 7a to the fourth switch 10a are sequentially shifted to the ON / OFF state in the period T1 to the period T4. Switching control for causing the series switch unit 7, the first series circuit unit 9, and the second series circuit unit 10 to execute the first operation to the fourth operation is executed. Specifically, when shifting from any of the periods T1 to T4 to the next new period, the control unit 13 shifts to the OFF state and the ON state in this new period. For the other switches, first, the switch to be shifted to the OFF state is shifted to the OFF state, and then the switching control to shift the other switch to be shifted to the ON state to the ON state is executed.

Therefore, according to this converter device 1A, by shifting the switch that should be switched to the OFF state in the new period to the OFF state, the current is sent to the body diodes of other switches that should be shifted to the ON state in this new period. In this state (a state in which a current is flowing through the body diode, that is, a state in which the drain-source voltage is close to zero volt), the other switch can be moved to the ON state. Therefore, the turn-on loss in other switches can be significantly reduced.

The circuit on the first winding 2a side is not limited to the above configuration adopted in the converter device 1A, and may be, for example, a circuit described later adopted in the converter device 1B shown in FIG. 7. .. Hereinafter, the converter device 1B will be described with reference to FIGS. 7 to 12. The same components as those of the converter device 1A are designated by the same reference numerals, and duplicate description will be omitted.

First, the configuration of the converter device 1B will be described with reference to FIG. 7. The converter device 1A includes a transformer 2, a pair of first DC terminal portions 3a and 3b, a pair of first AC terminal portions 4a and 4b, a pair of second DC terminal portions 5a and 5b, and a pair of second AC terminal portions 6a. , 6b, a series switch unit 7 as a first series switch unit, an inductor 8, a series switch unit 21 having a third switch 21a and a fourth switch 21b as a second series switch unit, a fifth switch 22, a sixth switch 23, A pair of capacitors 24, a rectifying smoothing unit 11, an LC resonance circuit 12, and a control unit 13 are provided, and the input DC voltage Vin input between the pair of first DC terminal units 3a and 3b is converted into the output DC voltage Vout. It is configured to be able to supply to the load LD connected to the second DC terminal portions 5a and 5b. It is assumed that the third switch 21a, the fourth switch 21b, the fifth switch 22, and the sixth switch 23 are composed of an n-channel type FET (field effect transistor) as an example of this example.

The series switch unit 21 is composed of a third switch 21a and a fourth switch 21b connected to each other by the other first AC terminal unit 4b of the pair of first AC terminal units 4a and 4b. Further, in the series switch portion 21, one end portion (end portion on the third switch 21a side; in this example, the drain terminal of the third switch 21a) is one of the first series switch portions 7 via the fifth switch 22. An end (drain terminal of the first switch 7a) is connected, and the other end (the end on the side of the fourth switch 21b; in this example, the source terminal of the fourth switch 21a) is connected to the sixth switch 23 via the sixth switch 23. 1 It is connected to the other end of the series switch unit 7 (source terminal of the second switch 7b).

Specifically, in the fifth switch 22, the source terminal is connected to one end of the series switch portion 7 (drain terminal of the first switch 7a), and the drain terminal is connected to one end of the series switch portion 21 (the first). By connecting to the drain terminal of the 3 switch 21a), one of these ends is connected to each other. In the sixth switch 23, the drain terminal is connected to the other end of the series switch portion 7 (source terminal of the first switch 7b), and the source terminal is the other end of the series switch portion 21 (source of the fourth switch 21b). By being connected to the terminal), these other ends are connected to each other.

The capacitor 24 is connected in parallel to the series switch unit 21.

The control unit 13 outputs drive signals S11, S12, S13, S14, S15, and S16 to each of the six switches from the first switch 7a to the sixth switch 23, so that the control unit 13 outputs the drive signals to the six switches 7a to 23. The operation of executing switching control, converting the input DC voltage Vin to the AC voltage V1 and outputting it between the first AC terminal units 4a and 4b is the circuit on the first winding 2a side (series switch units 7, 21, inductor). 8. Power conversion circuit composed of the 5th switch 22 and the 6th switch 23) is executed. In this example, since each switch from the first switch 7a to the sixth switch 23 is composed of FETs as described above, the control unit 13 is an appropriate drive circuit (not shown) for each of the switches 7a to 23. The corresponding drive signal among the drive signals S11 to S16 is output as a positive voltage signal based on the potential of the source terminal between the gate and the source of each switch 7a to 23.

Next, the operation of the converter device 1B will be described with reference to FIGS. 7 to 12.

The control unit 13 sets each drive signal S11, S12, S13, S14, S15, S16 as one cycle with the output state from the period T1 to the period T4 shown in FIG. 8 as one cycle, and the corresponding switches 7a, 7b, 21a, 21b. , 22, 23 are repeatedly output. Note that "ON" and "OFF" in FIG. 8 indicate ON / OFF states of the switches 7a to 23 corresponding to the drive signals S11 to S16. Hereinafter, the operation will be described separately for each period T1, T2, T3, and T4.

First, in the period T1, as shown in FIG. 8, the drive signals S11 and S14 are switched from zero volt (an example of a voltage below the gate threshold voltage) to a positive voltage (voltage above the gate threshold voltage), whereby FIGS. As shown in the above, the first switch 7a and the fourth switch 21b shift from the OFF state to the ON state. Further, as shown in FIGS. 8, the drive signals S13 and S16 are switched from the positive voltage to zero volt, so that the third switch 21a and the sixth switch 23 are changed from the ON state to the OFF state as shown in FIGS. 8 and 9. Transition. Further, since the other drive signals S12 and S15 are maintained at a positive voltage as shown in FIG. 8, the second switch 7b and the fifth switch 22 continue to be in the ON state as shown in FIGS. 8 and 9. That is, only the third switch 21a and the sixth switch 23 are turned off.

In this case, in the circuit on the first winding 2a side, first, the third switch 21a and the sixth switch 23 simultaneously shift to the OFF state, and then the first switch 7a and the fourth switch 21b simultaneously shift to the ON state. .. Therefore, immediately before the first switch 7a and the fourth switch 21b shift to the ON state, the current Ih flowing in the first winding 2a in the period T4 is the resonance capacitor 12a and the first switch in the OFF state as described later. FIG. 9 shows the current path returning to the first winding 2a via the body die of 7a, the fifth switch 22 in the ON state, the capacitor 24, the body die of the fourth switch 21b in the OFF state, and the resonant inductor 12b. As shown, the current Ib flows in the direction opposite to the direction shown in the figure. Therefore, the first switch 7a and the fourth switch 21b shift to the ON state (zero volt switching) in a state where the current Ib is flowing in each body diode, that is, in a state where the drain-source voltage is close to zero volt. .. Therefore, the turn-on loss in the first switch 7a and the fourth switch 21b is significantly reduced.

Further, when the sixth switch 23 shifts to the OFF state, charging of the capacitor 24 (accumulation of energy in the capacitor 24) executed as described later in the period T4 is completed, and then the first switch 7a and When the fourth switch 21b shifts to the ON state, a current can flow in the current path in which the current Ib is flowing in the above direction in the direction opposite to this direction (direction shown in FIG. 9). Become. Therefore, when the energy stored in the capacitor 24 is released, the current Ib is connected to the current path from the capacitor 24 to the fifth switch 22 in the ON state, the first switch 7a in the ON state, the resonance capacitor 12a, and the second switch. The current flows back to the capacitor 24 (in the direction shown in FIG. 9) via the 1 winding 2a, the resonant inductor 12b, and the fourth switch 21b in the ON state. Since the LC resonance circuit 12 is included in this current path, the waveform of the current Ib becomes a resonance waveform (sinusoidal waveform). Further, since the current Ib flows in the first winding 2a in the direction shown in FIG. 9, the induced voltage in the second winding 2b is such that the second AC terminal 6a has a higher potential than the second AC terminal 6b. V2 induces.

Further, when the first switch 7a shifts to the ON state together with the second switch 7b in the ON state, the DC power supply PS (input DC voltage Vin) is short-circuited via the inductor 8. As a result, as shown in FIG. 9, a current path is formed from the DC power supply PS to the DC power supply PS via the inductor 8, the first switch 7a, and the second switch 7b, and the current Ia is shown in this current path. In 9, it flows in the direction indicated by the arrow. Therefore, when this current Ia flows through the inductor 8, energy is stored in the inductor 8.

As described above, in the period T1, the circuit on the first winding 2a side (that is, the circuit including the series switch portions 7 and 21) stores energy in the inductor 8 based on the input DC voltage Vin and the capacitor 24. The first operation of supplying the current Ib to the first winding 2a is executed by releasing the energy stored in the first winding. That is, the circuit on the first winding 2a side of the converter device 1B executes the same operation as the circuit on the first winding 2a side of the converter device 1A during the period T1. Therefore, the circuit on the second winding 2b side executes the same operation as the converter device 1A, and the output DC voltage Vout is applied to the load LD based on the induced voltage V2 induced between the second AC terminal portions 6a and 6b. Is output.

Then, in the period T2, as shown in FIG. 8, the drive signal S12 is switched from the positive voltage to the zero voltage, and the drive signal S16 is switched from the zero voltage to the positive voltage, so that the second switch 7b is switched as shown in FIGS. Shifts from the ON state to the OFF state, and the sixth switch 23 shifts from the OFF state to the ON state. Since the corresponding drive signal is the same as that in the period T1, each of the other switches continues the ON / OFF state in the period T1. That is, only the second switch 7b and the third switch 21a are turned off.

In this case, in the circuit on the first winding 2a side, the second switch 7b first shifts to the OFF state, and then the sixth switch 23 shifts to the ON state. Therefore, immediately before the sixth switch 23 shifts to the ON state, the voltage is obtained by adding the voltage between both ends of the inductor 8 to the voltage of the DC power supply PS (in addition to the energy from the DC power supply PS, the current is discharged from the inductor 8). As shown in FIG. 10, from the DC power supply PS, the inductor 8, the first switch 7a in the ON state, the resonance capacitor 12a, the first winding 2a, the resonance inductor 12b, the fourth switch 21b in the ON state, and OFF. The current Id flows in the direction shown in FIG. 10 in the current path returning to the DC power supply PS via the body die of the sixth switch 23 in the state, and the inductor 8 is sent from the DC power supply PS, the fifth switch 22 in the ON state, and the capacitor. The current Ie flows in the direction shown in FIG. 10 in another current path returning to the DC power supply PS via the body die of the sixth switch 23 in the 24 and OFF states. Therefore, the sixth switch 23 shifts to the ON state (zero-volt switching) in a state where the currents Id and Ie are flowing in the body diode, that is, in a state where the drain-source voltage is close to zero volt. Therefore, the turn-on loss at the sixth switch 23 is significantly reduced.

Further, when the sixth switch 23 shifts to the ON state, the supply of the current Id to the first winding 2a based on the energy emitted from both the DC power supply PS and the inductor 8 is continued. Further, since the LC resonance circuit 12 is included in the current path of the current Id, the waveform of the current Id becomes a resonance waveform (a sinusoidal waveform). Further, since the current Id flows in the first winding 2a in the direction shown in FIG. 10 (the same direction as the current Ib in the period T1), the second winding 2b is the second with respect to the second AC terminal portion 6b. The induced voltage V2 at which the AC terminal portion 6a has a high potential is induced. Further, when the sixth switch 23 shifts to the ON state, the supply of the current Ie to the capacitor 24 is continued, and the capacitor 24 is charged with the energy emitted from both the DC power supply PS and the inductor 8 (). Energy is stored in the capacitor 24).

As described above, in the period T2, the circuit on the first winding 2a side sets the current Id in the first winding 2a to the first winding 2a in the same direction as the current Ib in the period T1 based on each energy from the DC power supply PS and the inductor 8. In addition to supplying the current, the second operation of charging the capacitor 24 is executed. That is, the circuit on the first winding 2a side of the converter device 1B executes the same operation as the circuit on the first winding 2a side of the converter device 1A during the period T2. Therefore, the circuit on the second winding 2b side executes the same operation as the converter device 1A, and the output DC voltage Vout is applied to the load LD based on the induced voltage V2 induced between the second AC terminal portions 6a and 6b. Is output.

Subsequently, in the period T3, as shown in FIG. 8, the drive signals S14 and S15 are switched from positive voltage to zero volt, and the drive signals S12 and S13 are switched from zero volt to positive voltage, as shown in FIGS. , The 4th switch 21b and the 5th switch 22 shift from the ON state to the OFF state, and the 2nd switch 7b and the 3rd switch 21a shift from the OFF state to the ON state. Since the corresponding drive signal is the same as that in the period T2, each of the other switches continues the ON / OFF state in the period T2. That is, only the 4th switch 21b and the 5th switch 22 are turned off.

In this case, in the circuit on the first winding 2a side, first, the fourth switch 21b and the fifth switch 22 simultaneously shift to the OFF state, and then the second switch 7b and the third switch 21a simultaneously shift to the ON state. .. Therefore, immediately before the second switch 7b and the third switch 21a shift to the ON state, the current Id flowing in the first winding 2a in the period T2 is the resonance inductor 12b, and the body dio of the third switch 21a in the OFF state. As shown in FIG. 11, a current flows through the body die of the ede, the capacitor 24, the sixth switch 23 in the ON state, the second switch 7b in the OFF state, and the current path returning to the first winding 2a via the resonance capacitor 12a. As Ig, it flows in the direction opposite to the direction shown in the figure. Therefore, the second switch 7b and the third switch 21a shift to the ON state (zero volt switching) in a state where the current Ig is flowing in each body diode, that is, in a state where the drain-source voltage is close to zero volt. .. Therefore, the turn-on loss in the second switch 7b and the third switch 21a is significantly reduced.

Further, when the fifth switch 22 shifts to the OFF state, the charging of the capacitor 24 (accumulation of energy in the capacitor 24) executed in the period T2 is completed, and then the second switch 7b and the third switch are completed. When the 21a shifts to the ON state, the current can flow in the direction opposite to this direction (direction shown in FIG. 11) in the above current path in which the current Ig is flowing in the above direction. Therefore, when the energy stored in the capacitor 24 is released, the current Ig is transferred from the capacitor 24 to the third switch 21a, the resonance inductor 12b, the first winding 2a, and the resonance capacitor 12a in the ON state in this current path. , The current flows back to the capacitor 24 (in the direction shown in FIG. 11) via the second switch 7b in the ON state and the sixth switch 23 in the ON state. Since the LC resonance circuit 12 is included in this current path, the waveform of the current Ig becomes a resonance waveform (a sinusoidal waveform). Further, since the current Ig flows in the first winding 2a in the direction shown in FIG. 11 (opposite to the current Id in the period T2), the second winding 2b has a second AC terminal portion 6a with respect to the second AC terminal portion 6a. 2 The induced voltage V2 at which the AC terminal portion 6b has a high potential is induced.

Further, when the second switch 7b shifts to the ON state together with the first switch 7a in the ON state, the DC power supply PS is short-circuited via the inductor 8. As a result, as shown in FIG. 11, a current path is formed from the DC power supply PS to the DC power supply PS via the inductor 8, the first switch 7a, and the second switch 7b, and the current Ia is shown in this current path. In 11, the current flows in the direction indicated by the arrow. Therefore, when this current Ia flows through the inductor 8, energy is stored in the inductor 8.

As described above, in the period T3, the circuit on the first winding 2a side (that is, the circuit including the series switch portions 7 and 21) stores energy in the inductor 8 based on the input DC voltage Vin and the capacitor 24. The third operation of supplying the current Ig to the first winding 2a is executed by releasing the energy stored in the first winding. That is, the circuit on the first winding 2a side of the converter device 1B executes the same operation as the circuit on the first winding 2a side of the converter device 1A during the period T3. Therefore, the circuit on the second winding 2b side executes the same operation as the converter device 1A, and the output DC voltage Vout is applied to the load LD based on the induced voltage V2 induced between the second AC terminal portions 6a and 6b. Is output.

Then, in the period T4, as shown in FIG. 8, the drive signal S11 switches from the positive voltage to the positive voltage, and the drive signal S15 switches from the zero voltage to the positive voltage, so that the first switch 7a is shown in FIGS. Shifts from the ON state to the OFF state, and the fifth switch 22 shifts from the OFF state to the ON state. Since the corresponding drive signal is the same as that in the period T3, each of the other switches continues the ON / OFF state in the period T3. That is, only the first switch 7a and the fourth switch 21b are turned off.

In this case, in the circuit on the first winding 2a side, the first switch 7a first shifts to the OFF state, and then the fifth switch 22 shifts to the ON state. Therefore, immediately before the fifth switch 22 shifts to the ON state, it is discharged from the inductor 8 by the voltage obtained by adding the voltage between both ends of the inductor 8 to the voltage of the DC power supply PS (in addition to the energy from the DC power supply PS). As shown in FIG. 12, the inductor 8 from the DC power supply PS, the body die of the fifth switch 22 in the OFF state, the third switch 21a in the ON state, the resonance inductor 12b, the first winding 2a, and the resonance. The current Ih flows in the direction shown in FIG. 12 in the current path returning to the DC power supply PS via the capacitor 12a and the second switch 7b in the ON state, and the inductor 8 and the body of the fifth switch 22 in the OFF state are connected from the DC power supply PS. The current Ie flows in the direction shown in FIG. 12 in another current path returning to the DC power supply PS via the die, the capacitor 24, and the sixth switch 23 in the ON state. Therefore, the fifth switch 22 shifts to the ON state (zero-volt switching) in a state where the currents Ie and Ih are flowing through the body diode, that is, in a state where the drain-source voltage is close to zero volt. Therefore, the turn-on loss at the fifth switch 22 is significantly reduced.

Further, when the fifth switch 22 shifts to the ON state, the supply of the current Ih to the first winding 2a based on the energy emitted from both the DC power supply PS and the inductor 8 is continued. Further, since the LC resonance circuit 12 is included in the current path of the current Ih, the waveform of the current Id becomes a resonance waveform (a sinusoidal waveform). Further, since the current Ih flows in the first winding 2a in the direction shown in FIG. 12 (the same direction as the current Ig in the period T3), the second winding 2b is the second with respect to the second AC terminal portion 6a. The induced voltage V2 at which the AC terminal portion 6b has a high potential is induced. Further, when the fifth switch 22 shifts to the ON state, the supply of the current Ie to the capacitor 24 is continued, and the capacitor 24 is charged with the energy emitted from both the DC power supply PS and the inductor 8 (). Energy is stored in the capacitor 24).

As described above, in the period T4, the circuit on the first winding 2a side sets the current Ih in the first winding 2a to the first winding 2a in the same direction as the current Ig in the period T3 based on the respective energies from the DC power supply PS and the inductor 8. In addition to supplying the current, the fourth operation of charging the capacitor 24 is executed. That is, the circuit on the first winding 2a side of the converter device 1B executes the same operation as the circuit on the first winding 2a side of the converter device 1A during the period T4. Therefore, the circuit on the second winding 2b side executes the same operation as the converter device 1A, and the output DC voltage Vout is applied to the load LD based on the induced voltage V2 induced between the second AC terminal portions 6a and 6b. Is output.

Further, the output DC voltage Vout in the converter device 1B is expressed by the same equation as the output DC voltage Vout in the converter device 1A described above. Therefore, the converter device 1B also functions as a Boost type (boost type) converter in which the output DC voltage Vout is larger than the input DC voltage Vin in the same manner as the converter device 1A, and the switches 7a, 7b, 21a, 21b, respectively. The output DC voltage Vout can be controlled by changing the on-duty D of the first switch 7a and the second switch 7b without changing the switching frequencies of 22 and 23.

As described above, in this converter device 1B, the circuit on the first winding 2a side includes the series switch portions 7, 21, the inductor 8, the fifth switch 22, the sixth switch 23, and the capacitor 24 together with the first winding 2a. As shown in FIG. 7, they are connected and configured. Further, the LC resonance circuit 12 is inserted and connected between the first winding 2a and the first AC terminal portions 4a and 4b.

Therefore, according to this converter device 1B, since the step-up circuit which is indispensable in the two-stage type converter described in the prior art is configured as a one-stage type, the boosting is performed in the same manner as the converter device 1A. It is possible to eliminate the recovery loss that occurred in the diode of the circuit. Further, according to the converter device 1B, the output DC voltage Vout can be controlled by changing the on-duty of the first switch 7a and the second switch 7b in the same manner as the converter device 1A (that is, the first switch 7a). The output DC voltage Vout can be controlled without changing the switching frequency of the 1st switch 7a to the 6th switch 23). Further, according to this converter device 1B, a capacitor for forming a circuit on the first winding 2a side (an electronic component whose outer shape is usually extremely large as compared with a switch 7a or the like composed of a semiconductor element). Since this can be done with only one capacitor 24, the circuit board on which the electronic components are mounted and the device itself can be downsized as compared with the converter device 1A which requires two capacitors 9b and 10b. ..

Further, in this converter device 1B, all the switches from the first switch 7a to the sixth switch 23 are composed of FETs having a built-in body diode, and the control unit 13 outputs drive signals S11 to S16 at the timing shown in FIG. By outputting and driving all the switches 7a to 23 (each switch 7a to 23 is sequentially shifted to the ON / OFF state in the period T1 to the period T4, the series switch units 7, 21 and each switch 22, The switching control for causing the 23 to execute the first operation to the fourth operation is executed. Specifically, when shifting from any period of the period T1 to the period T4 to the next new period, the control unit With respect to the switch that shifts to the OFF state and the other switches that shift to the ON state in this new period, the switch 13 first shifts the switch that should shift to the OFF state to the OFF state, and then shifts to the ON state. The switching control that shifts the other switch to be turned to the ON state is executed.

Therefore, according to this converter device 1B, by shifting the switch that should be switched to the OFF state in the new period to the OFF state, the current is sent to the body diodes of other switches that should be shifted to the ON state in this new period. In this state (a state in which a current is flowing through the body diode, that is, a state in which the drain-source voltage is close to zero volt), the other switch can be moved to the ON state. Therefore, the turn-on loss in other switches can be significantly reduced.

In the converter devices 1A and 1B described above, each switch is configured by a FET having a built-in body diode, but instead of this configuration, each switch may be configured by a parallel circuit of a bipolar transistor and a discrete diode. can. Further, in the converter devices 1A and 1B described above, the rectifier circuit of the rectifying smoothing unit 11 is configured by the bridge type full-wave rectifier circuit composed of four diodes 11a, 11b, 11c and 11d, but the present invention is limited to this. is not it. For example, although not shown, the second winding 2b is configured to have a center tap, and a diode is connected to each end of the second winding 2b, and the second winding 2b is based on the potential of the center tap. A rectifying circuit that outputs an output DC voltage Vout based on the potential of the center tap by rectifying and synthesizing the voltage induced at each end of the center tap with each diode is adopted as the rectifying circuit of the rectifying smoothing unit 11. You can also do it. Further, although not shown, a known m-fold (m is an integer of 2 or more) voltage rectifier circuit configured by combining a capacitor and a diode can be adopted as the rectifier circuit of the rectification smoothing unit 11.

Further, in the converter devices 1A and 1B described above, the LC resonance circuit 12 is configured by the resonance capacitor 12a and the resonance inductor 12b as independent components, but the present invention is not limited thereto. For example, the resonance capacitor 12a can be replaced with the capacitor 24 of the first series circuit unit 9 or the second capacitor 10b of the second series circuit unit 10 instead of the configuration arranged as an independent component. Further, the resonance inductor 12b can also be replaced with the leakage inductance of the transformer 2 instead of the configuration arranged as an independent component.

1A, 1B converter device
2 Transformer 2a 1st winding 2b 2nd winding 3a, 3b 1st DC terminal 4a, 4b 1st AC terminal 5a, 5b 2nd DC terminal 6a, 6b 2nd AC terminal
7,21 Series switch 7a 1st switch 7b 2nd switch
8 Inductor
9 1st series circuit part 9a 3rd switch 9b 1st capacitor 10 2nd series circuit part 10a 4th switch 10b 2nd capacitor 12 LC resonance circuit 13 control part 21a 3rd switch 21b 4th switch 22 5th switch 23 6th switch

Claims (4)

A transformer in which the first winding and the second winding are formed,
A pair of first DC terminals and
A pair of first AC terminals connected to the first winding via a pair of first connection lines, and a pair of first AC terminals.
A pair of second DC terminals and
A pair of second AC terminals connected to the second winding via a pair of second connection lines, and a pair of second AC terminals.
It is composed of a first switch and a second switch connected to each other by the first AC terminal portion of one of the pair of first AC terminal portions, and one end portion on the first switch side is the first power line. It is connected to the first DC terminal portion of one of the pair of first DC terminal portions via the above, and the other end portion on the second switch side is the pair of first DC terminals via the second power line. A series switch section connected to the other first DC terminal section of the terminal section,
An inductor inserted and connected to at least one of the first power line and the second power line.
It is composed of a third switch and a first capacitor connected in series, one end of which is connected to the one end of the series switch portion and the other end of the pair of first AC terminals. The first series circuit section connected to the other first AC terminal section of the
It consists of a fourth switch and a second capacitor connected in series, one end of which is connected to the other first AC terminal and the other end of which is to the other end of the series switch. The connected second series circuit section and
A rectifying smoothing portion disposed between the pair of second AC terminal portions and the pair of second DC terminal portions,
An LC resonant circuit inserted and connected to at least one of the pair of first connection lines and the pair of second connection lines.
By executing switching control from the first switch to the fourth switch, the input DC voltage input to the pair of first DC terminals is converted into an output DC voltage between the pair of second DC terminals. Equipped with a control unit that outputs from
By executing the switching control, the control unit
By turning off only the fourth switch among the fourth switches from the first switch, energy is stored in the inductor based on the input DC voltage and is stored in the first capacitor. The first operation of supplying a current to the first winding by releasing energy,
By turning off only the second switch among the fourth switches from the first switch, the energy stored in the first capacitor is released to supply a current to the first winding. At the same time, the second operation of storing energy in the second capacitor based on the input DC voltage and the energy emitted from the inductor,
By turning off only the third switch among the fourth switches from the first switch, energy is stored in the inductor based on the input DC voltage and is stored in the second capacitor. The third operation of supplying a current to the first winding by releasing energy,
Further, by turning off only the first switch of the fourth switches from the first switch, the energy stored in the second capacitor is released to supply a current to the first winding. At the same time, the series switch unit, the first series circuit unit, and the second series circuit unit perform the fourth operation of storing energy in the first capacitor based on the input DC voltage and the energy emitted from the inductor. A converter device that is repeatedly executed by the capacitor. The converter device according to claim 1 , wherein the first switch to the fourth switch are composed of FETs having a built-in body diode. A transformer in which the first winding and the second winding are formed,
A pair of first DC terminals and
A pair of first AC terminals connected to the first winding via a pair of first connection lines, and a pair of first AC terminals.
A pair of second DC terminals and
A pair of second AC terminals connected to the second winding via a pair of second connection lines, and a pair of second AC terminals.
It is composed of a first switch and a second switch connected to each other by the first AC terminal portion of one of the pair of first AC terminal portions, and one end portion on the first switch side is the first power line. It is connected to the first DC terminal portion of one of the pair of first DC terminal portions via the above, and the other end portion on the second switch side is the pair of first DC terminals via the second power line. The first series switch section connected to the other first DC terminal section of the terminal section,
An inductor inserted and connected to at least one of the first power line and the second power line.
It is composed of a third switch and a fourth switch connected to each other by the other first AC terminal portion of the pair of first AC terminal portions, and one end on the third switch side serves as a fifth switch. It was connected to one end of the first series switch portion via the sixth switch, and the other end of the fourth switch side was connected to the other end of the first series switch portion via the sixth switch. The second series switch part and
A capacitor connected in parallel to the second series switch section,
A rectifying smoothing portion disposed between the pair of second AC terminal portions and the pair of second DC terminal portions,
An LC resonant circuit inserted and connected to at least one of the pair of first connection lines and the pair of second connection lines.
By executing switching control from the first switch to the sixth switch, the input DC voltage input to the pair of first DC terminals is converted into an output DC voltage between the pair of second DC terminals. Equipped with a control unit that outputs from
By executing the switching control, the control unit
By turning off only the third switch and the sixth switch among the sixth switches from the first switch, energy is stored in the inductor and stored in the capacitor based on the input DC voltage. The first operation of supplying a current to the first winding by releasing the energy being generated,
By turning off only the second switch and the third switch among the sixth switches from the first switch, the input DC voltage and the inductor are discharged while accumulating energy in the capacitor. A second operation that supplies a current to the first winding based on energy,
By turning off only the 4th switch and the 5th switch among the 6th switches from the 1st switch, energy is stored in the inductor and stored in the capacitor based on the input DC voltage. The third operation of supplying a current to the first winding by releasing the energy being generated,
Further, by turning off only the first switch and the fourth switch among the sixth switches from the first switch, the input DC voltage and the inductor are discharged while accumulating energy in the capacitor. A converter device that repeatedly causes the first series switch unit, the second series switch unit, the fifth switch, and the sixth switch to perform a fourth operation of supplying a current to the first winding based on the energy . The converter device according to claim 3 , wherein the first switch to the sixth switch are composed of FETs having a built-in body diode.

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