JP2003324963A - Power-converting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the switching loss of switching elements, and to reduce the heat generation of the switching elements so as to improve the conversion efficiency of a power-converting device, by regenerating energy accumulated in dv/dt controlling capacitors. <P>SOLUTION: A switching element series circuit comprising first and second switching elements is connected parallel to DC power sources connected in series. The primary winding of a transformer is connected between the series connection point of the DC power sources and that of the switching elements, and the secondary winding of the transformer to a load. The first and the second switching elements are each connected parallel to a first capacitor- auxiliary winding series circuit comprising a first capacitor and a first auxiliary winding of the transformer, and to a second capacitor-auxiliary winding series circuit comprising a second capacitor and a second auxiliary winding of the transformer respectively. A dt/dv value at the time when the switching elements are turned on is controlled and simultaneously the energy accumulated in the first and the second capacitors is regenerated to the power sources or the load. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter that obtains another arbitrary output from a DC power supply via a switch circuit and a transformer when performing power conversion by turning on / off a switch element. The present invention relates to a power conversion device having a function of reducing switching loss that occurs when a switch element is turned off and regenerating energy stored in a snubber capacitor.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional example of a half-bridge type power converter. As shown, DC power supply 41 and DC power supply 42
A DC power supply series circuit composed of a switch element 11 and a switch element 12 is connected in parallel to the switch element series circuit, the switch element 11 and the switch element 12 series connection point, a DC power supply 41 and a DC power supply 42. The primary winding 31 of the transformer 3 is connected between the series connection points of, and the load 5 is connected in parallel to the secondary winding 32 of the transformer 3.

The operation in the configuration of FIG. 7 is shown in FIG. When the voltage of the DC power supply 41 is E / 2 and the voltage of the DC power supply 42 is E / 2, the transformer primary winding 31 is positively excited by the voltage of E / 2 during the period a in which the switch element 11 is turned on. Transformer secondary winding 3
Power is supplied to the load 5 via 2 and the transformer primary winding 31 is excited by the voltage of E / 2 in the negative polarity during the period f in which the switch element 12 is turned on, and the transformer secondary winding 32 is turned on. Power to the load 5 via. By repeating such an operation, electric power is supplied from the DC power supply 41 and the DC power supply 42 to the load 5.

[0004]

In the case of the conventional embodiment shown in FIG. 7, in the switching process of the periods b to c and the periods g to h, an overlapping period occurs between the voltage waveform and the current waveform of the switch element, This becomes switching loss. This loss causes heat generation in the switch element, which in turn reduces the conversion efficiency of the power conversion device.

A capacitor can be connected in parallel with the switch element to reduce switching loss.
If the stored energy of the capacitor is consumed by a resistor,
The switch element does not generate heat, but the resistor generates heat, and the power conversion efficiency cannot be improved.

An object of the present invention is to reduce the switching loss of the switch element and at the same time regenerate the stored energy of the capacitor, thereby reducing the heat generation of the switch element and improving the conversion efficiency of the power conversion device.

[0007]

In order to solve such a problem, according to the invention of claim 1, in a power converter which obtains another arbitrary output from a DC power source through at least a switch element and a transformer, A first switch element and a second switch element are connected in series to the DC power supply, and one terminal of the primary winding of the transformer is connected to the first switch element and the second switch element. Connected to the series connection point of
A first capacitor / auxiliary winding series circuit including a first capacitor and a first auxiliary winding of the transformer is connected in parallel with the first switch element, and a second capacitor and a transformer are connected in parallel. A second capacitor consisting of a second auxiliary winding,
An auxiliary winding series circuit is connected in parallel with the second switch element.

According to a second aspect of the present invention, the first switch element, the second switch element, the first capacitor, the second capacitor, the first auxiliary winding of the transformer, and the transformer. 2nd auxiliary winding of this is combined and comprised.

[0009]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. It should be noted that this embodiment is defined by claim 1.
Corresponds to the invention of.

A switch element series circuit including a switch element 11 and a switch element 12 is connected in parallel to a DC power source series circuit including a DC power source 41 and a DC power source 42 to form a switch element.
The primary winding 31 of the transformer 3 is connected between the series connection point of the switch 11 and the switch element 12 and the series connection point of the DC power supply 41 and the DC power supply 42.
And a first capacitor / auxiliary winding series circuit consisting of the capacitor 21 and the auxiliary winding 33 of the transformer 3 is connected to the switching element 1
1 in parallel with the capacitor 22 and the auxiliary winding 34 of the transformer 3
The second capacitor / auxiliary winding series circuit consisting of is connected in parallel with the switch element 12, and the load 5 is connected in parallel with the secondary winding 32 of the transformer 3.

The circuit operation in the configuration of FIG. 1 is shown in FIG. DC power supply 41 voltage is E / 2, DC power supply 42 voltage is E / 2,
If the number of turns of the transformer primary winding 31 is N1, and the number of turns of the transformer auxiliary winding 33 and the transformer auxiliary winding 34 is N3, the switching element 11
During the period a when the power is turned on, the transformer primary winding 31 is moved in the positive direction E /
It is excited by the voltage of 2 and supplies power to the load 5 through the transformer secondary winding 32, and the transformer primary winding 31 is moved in the negative direction to E / 2 during the period f in which the switch element 12 is turned on. It is excited by a voltage and supplies power to the load 5 via the transformer secondary winding 32.

By repeating such operations, electric power is supplied from the DC power supply 41 and the DC power supply 42 to the load 5. These operations are similar to those of the conventional embodiment.

The operation in each period of a to j in FIG. 2 will be described below. In the period a, the voltage of (E / 2) × (N3 / N1) is applied to the transformer auxiliary winding 33 and the transformer auxiliary winding 34, and the voltage of − (E / 2) · (N3 / N1) is applied to the capacitor 21. Voltage is E + across capacitor 22
The voltages of (E / 2) and (N3 / N1) are applied respectively.

During the period b, when the switch element 11 is turned off, the DC power source 41 → switch element 11 → transformer primary winding 31
The current flowing in the path of DC power supply 41 → capacitor 21
→ Transformer auxiliary winding 33 → Transmuted gradually to the path of the transformer primary winding 31. By this operation, the voltage increase rate of the switch element 11 is suppressed, the overlapping period of the voltage waveform and the current waveform of the switch element 11 is shortened, and the switching loss is reduced.
At the same time, current flows in the path of capacitor 22 → transformer auxiliary winding 34 → transformer primary winding 31 → DC power supply 42
The electric charge accumulated in 22 is regenerated by the DC power supply 42.

In the period c, the current flowing through the switch element 11 becomes zero, but the DC power supply 41 → capacitor 21 → transformer auxiliary winding 33 → transformer primary winding 31 path and capacitor 22 → transformer auxiliary The current continues to flow in the path of the winding 34 → the transformer primary winding 31 → the DC power supply 42, and the voltage of the switch element 11, the switch element 12, the capacitor 21, and the capacitor 22 becomes E /
2. When the transformer auxiliary winding 33 and the transformer auxiliary winding 34 reach zero voltage, the period c is completed, and the switch element 11 and the switch element 12 are both turned off to the period d.

During the period e, when the switch element 12 is turned on, the DC power source 42 → the transformer primary winding 31 → the switch element 12
Current flows through the path of the
While supplying electric power to the capacitor 22, the current flows through the path of the capacitor 22 → transformer auxiliary winding 34 → switch element 12, and the charge accumulated in the capacitor 22 is transferred to the transformer auxiliary winding 34 and the transformer secondary winding 32. It is discharged to the load 5 via and the voltage of the capacitor 22 is reversely charged to − (E / 2) · (N3 / N1). At this time, a voltage of-(E / 2) ・ (N3 / N1) is applied to the transformer auxiliary winding 33, so that the DC power supply 41 → the capacitor 21 → the transformer auxiliary winding 33 → the primary winding of the transformer. A current flows in the path of the line 31 and charges the capacitor 21 to E + (E / 2) · (N3 / N1).

During the period g, when the switch element 12 is turned off, the DC power source 42 → the transformer primary winding 31 → the switch element 12
The current flowing in the path of is gradually commutated to the path of the DC power supply 42, the transformer primary winding 31, the transformer auxiliary winding 34, and the capacitor 22. By this operation, the voltage increase rate of the switch element 12 is suppressed, the overlapping period of the voltage waveform and the current waveform of the switch element 12 is shortened, and the switching loss is reduced.
At the same time, the capacitor 21 → DC power supply 41 → transformer primary winding
31 → Transformer Auxiliary winding 33
The electric charge accumulated in 21 is regenerated to the DC power supply 41.

During the period h, the current flowing through the switch element 12 becomes zero, but the DC power source 42 → transformer primary winding 31
→ Transformer auxiliary winding 34 → Capacitor 22 path and capacitor 21 → DC power supply 41 → Transformer primary winding 31 → Transformer auxiliary winding 33 path, current continues to flow, and switch element 11, switch element 12, capacitor 21 and capacitor 22 voltage is E /
2. When the voltage of the transformer auxiliary winding 33 and the transformer auxiliary winding 34 becomes zero voltage, the period h is completed, and the period i in which both the switch element 11 and the switch element 12 are in the off state is entered.

During the period j, when the switch element 11 is turned on, the DC power source 41 → switch element 11 → transformer primary winding 31
Current flows through the path of the
While supplying power to the capacitor 21, the current flows through the path of the capacitor 21 → the switch element 11 → the transformer auxiliary winding 33, and the charge accumulated in the capacitor 21 is transferred to the transformer auxiliary winding 33 and the transformer secondary winding 32. It is discharged to the load 5 via and further reversely charges the voltage of the capacitor 21 to − (E / 2) · (N3 / N1). At this time, the voltage (E / 2) / (N3 / N1) is applied to the transformer auxiliary winding 34, so that the DC power supply 42 → the transformer primary winding 31 → the transformer auxiliary winding 34 → the capacitor A current flows through the path of 22 and charges the capacitor 22 to E + (E / 2) · (N3 / N1).

By repeating the above operation, the energy stored in the capacitors 21 and 22 is not wasted, and the DC power supply 41 and the DC power supply 42 are not consumed.
Or it is regenerated to load 5.

FIG. 3 is a circuit diagram showing a modification of the second embodiment of the present invention. It should be noted that this embodiment is defined by claim 1.
Corresponds to the invention of. The difference from FIG. 1 is that the polarities of the primary winding 31, the auxiliary winding 33, and the auxiliary winding 34 of the transformer 3 are reversed, and the other points are the same. The principle of operation is also the same as in FIG.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention. This embodiment corresponds to the invention of claim 2.

For the DC power source 4, a first switch element series circuit including a switch element 11a and a switch element 12a,
A second switch element series circuit including a switch element 11b and a switch element 12b is connected in parallel, and a series connection point between the switch element 11a and the switch element 12a and a series connection point between the switch element 11b and the switch element 12b. During the transformer
3 is connected to the primary winding 31, and the first capacitor-auxiliary winding series circuit consisting of the capacitor 21a and the auxiliary winding 33a of the transformer 3 is connected to the switch element 11a, the capacitor 22a and the auxiliary winding of the transformer 3. The second capacitor / auxiliary winding series circuit including the switch 34a and the switch element 12a, the capacitor 21b and the transformer 3
The third capacitor-auxiliary winding series circuit including the auxiliary winding 33b of the switch element 11b, the capacitor 22b and the transformer.
A fourth capacitor / auxiliary winding series circuit composed of three auxiliary windings 34b is connected in parallel with each switch element 12b,
The load 5 is connected in parallel with the secondary winding 32 of the transformer 3.

The circuit operation in the configuration of FIG. 4 is shown in FIG. The voltage of the DC power supply 4 is E, the number of turns of the transformer primary winding 31 is N
1, the number of turns of the transformer auxiliary windings 33a, 33b, 34a, 34b is N3, and its operation will be described.

During the period a, the switch elements 11a and 12b are turned on, the transformer primary winding 31 is excited in the positive direction by the DC power supply voltage E, and the load 5 is supplied with power via the transformer secondary winding 32. To supply. At this time, the transformer auxiliary windings 33a, 33b, 34
The voltage of E ・ N3 / N1 is applied to a and 34b, and -E ・ N3 is applied to capacitors 21a and 22b.
The voltage of / N1 and the voltage of E + E · N3 / N1 are applied to the capacitors 21b and 22a, respectively.

When the switch elements 11a and 12b are turned off in the period b, the current flowing in the path of the DC power source 4 → switch element 11a → transformer primary winding 31 → switch element 12b becomes
The DC power source 4 → the capacitor 21a → the transformer auxiliary winding 33a → the transformer primary winding 31 → the transformer auxiliary winding 34b → the capacitor 22b is gradually commutated.

By this operation, the voltage rising rate of the switch elements 11a, 12b is suppressed, the overlapping period of the voltage waveform and the current waveform of the switch elements 11a, 12b is shortened, and the switching loss is reduced. At the same time, current flows in the path of capacitor 22a → transformer auxiliary winding 34a → transformer primary winding 31 → transformer auxiliary winding 33b → capacitor 21b → DC power supply 4
The charges accumulated in 22a and 21b are regenerated by the DC power supply 4.

In the period c, the current flowing through the switch elements 11a and 12b becomes zero, but the DC power source 4 → the capacitor 2
1a → transformer auxiliary winding 33a → transformer primary winding 31 → transformer auxiliary winding 34b → capacitor 22b path and capacitor 22a
→ transformer auxiliary winding 34a → transformer primary winding 31 → transformer auxiliary winding 33b → capacitor 21b → current continues to flow in the path of the DC power supply 4 and switch elements 11a, 12a, 11b, 12b and capacitors
21a, 22a, 21b, 22b voltage is E / 2, transformer auxiliary winding 33a,
When the voltages of 34a, 33b, and 34b become zero voltage, the period c is completed, and the period shifts to the period d in which all the switch elements are in the off state.

During the period e, when the switching elements 11b and 22a are turned on, a current flows through the path of the DC power supply 4 → the switching element 11b → the transformer primary winding 31 → the switching element 22a and passes through the transformer secondary winding 32. Powers the load 5 and
Capacitor 21b → Switch element 11b → Transformer auxiliary winding 33b
And a path of the capacitor 22a → the transformer auxiliary winding 34a → the switching element 12a, current is stored in the capacitors 21b and 22a, and the charge is accumulated in the capacitors 21b and 22a. It is discharged to the load 5 through the line 32, and the voltages of the capacitors 21b and 22a are further reverse-charged to −E · N3 / N1.

At this time, -E is added to the transformer auxiliary windings 33a and 34b.
・ When the voltage of N3 / N1 is applied, current flows in the route of DC power supply 4 → capacitor 21a → transformer auxiliary winding 33a → transformer primary winding 31 → transformer auxiliary winding 34b → capacitor 22b,
The capacitors 21a and 22b are charged to the voltage E + E · N3 / N1.

When the switching elements 11b and 12a are turned off in the period g, the current flowing in the path of the DC power source 4 → the switching element 11b → the primary winding 31 of the transformer → the switching element 12a becomes
The DC power source 4 → capacitor 21b → transformer auxiliary winding 33b → transformer primary winding 31 → transformer auxiliary winding 34a → capacitor 22a is gradually commutated in the route.

By this operation, the voltage rising rate of the switch elements 11b and 12a is suppressed, the overlapping period of the voltage waveform and the current waveform of the switch elements 11b and 12a is shortened, and the switching loss is reduced. At the same time, current flows in the path of capacitor 22b → transformer auxiliary winding 34b → transformer primary winding 31 → transformer auxiliary winding 33a → capacitor 21a → DC power supply 4
The electric charges accumulated in 22b and 21a are regenerated to the DC power supply 4.

In the period h, the current flowing through the switch elements 11b and 12a becomes zero, but the DC power supply 4 → the capacitor 2
1b → transformer auxiliary winding 33b → transformer primary winding 31 → transformer auxiliary winding 34a → capacitor 22a path and capacitor 22b
→ transformer auxiliary winding 34b → transformer primary winding 31 → transformer auxiliary winding 33a → capacitor 21a → current continues to flow in the path of the DC power supply 4 and switch elements 11a, 12a, 11b, 12b and capacitors 21a, 22a , 21b, 22b voltage is E / 2, transformer auxiliary winding 3
When the voltages of 3a, 34a, 33b, and 34b become zero voltage, the period h is completed, and the period is shifted to the period i in which all the switch elements are in the off state.

During the period j, when the switch elements 11a and 12b are turned on, a current flows through the path of the DC power source 4 → switch element 11a → transformer primary winding 31 → switch element 12b, and the secondary winding 32 passes through the transformer secondary winding 32. Power is supplied to the load 5 and the current flows through the path of the capacitor 21a → switch element 11a → transformer auxiliary winding 33a and the path of the capacitor 22b → transformer auxiliary winding 34b → switch element 12b. The charge stored in the capacitor is discharged to the load 5 through the transformer auxiliary windings 33a and 34b and the transformer secondary winding 32, and the voltage of the capacitors 21a and 22b is reversely charged to -E · N3 / N1. .

At this time, -E is added to the transformer auxiliary windings 33b and 34a.
・ By applying the voltage of N3 / N1, DC power supply 4 → Capacitor 21b → Transformer auxiliary winding 33b → Transformer primary winding 31 →
A current flows in the path from the transformer auxiliary winding 34a to the capacitor 22a to charge the capacitors 21b and 22a to the voltage of E + E · N3 / N1.

By repeating the above operation, the energy stored in the capacitors 21a, 22a, 21b and 22b is regenerated by the DC power source 4 or the load 5 without being wasted.

FIG. 6 is a circuit diagram showing a modification of the third embodiment of the present invention. In addition, this embodiment is claimed in claim 2.
Corresponds to the invention of. The difference from FIG. 4 is that the polarities of the primary winding 31 and the auxiliary windings 33a, 33b, 34a, 34b of the transformer 3 are opposite, and the other points are the same. The operation principle is the same as that of FIG. 5 except that the operation of the switch elements 11a, 12a, 11b and 12b and the polarity of the power supply to the load 5 are reversed.

[0038]

According to the present invention, the switching loss of the switch element is reduced, and the energy stored in the capacitor can be regenerated to the power supply or the load. Therefore, heat generation of the switch element can be reduced, and the conversion efficiency of the power conversion device can be improved.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention.

FIG. 2 is an operation waveform of a circuit configuration showing the first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a third embodiment of the present invention.

FIG. 5 is an operation waveform of the circuit configuration showing the third embodiment of the present invention.

FIG. 6 is a circuit configuration diagram showing a fourth embodiment of the present invention.

FIG. 7 is a circuit configuration diagram showing a conventional technique.

FIG. 8 is an operation waveform of a circuit configuration showing a conventional technique.

[Explanation of symbols]

11, 11a, 11b, 12, 12a, 12b ・ ・ ・ ・ ・ Switch element 21, 21a, 21b, 22, 22a, 22b ・ ・ ・ ・ ・ Capacitor 3 ・ ・ ・ ・ ・ Transformer 31 ・ ・ ・ ・ ・ Transformer Transformer primary winding, 32 ・ ・ ・ ・ ・ Transformer secondary winding 33, 33a, 33b, 34, 34a, 34b ・ ・ ・ ・ ・ Transformer auxiliary winding 4, 41, 42 ・ ・ ・ ・ ・ DC power supply , 5 ・ ・ ・ ・ ・ Load

Claims (2)

[Claims] 1. A power conversion device for obtaining another arbitrary output from a DC power supply via at least a switch circuit and a transformer, wherein a first switch element and a second switch are provided for the DC power supply.
Connecting in parallel a switch element series circuit consisting of a switch element, and connecting one terminal of the primary winding of the transformer to a series connection point of the first switch element and the second switch element, A first capacitor / auxiliary winding series circuit including a first capacitor and a first auxiliary winding of the transformer is connected in parallel with the first switch element, and a second capacitor and a transformer are connected in parallel. Second consisting of a second auxiliary winding
A power conversion device, wherein the capacitor / auxiliary winding series circuit is connected in parallel with the second switch element. 2. The power conversion device according to claim 1, wherein:
A plurality of the first switch element, the second switch element, the first capacitor, the second capacitor, the first auxiliary winding of the transformer and the second auxiliary winding of the transformer, A power converter characterized by being configured by combining them.