JP2915243B2 - Series resonant converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a series resonant converter for preventing a short circuit current generated in a basic operation of a resonant converter.

[0002]

2. Description of the Related Art FIG. 5 shows, for example, the Institute of Electronics, Information and Communication Engineers, Research Report PE-88-64, "Rectifier Using a Voltage Clamp Type Series Resonant Converter" and the Institute of Electronics, Information and Communication Engineers, Research Report PE86-33, "A-SCR". Is a circuit diagram showing a conventional full-bridge type series resonance converter shown in "High-frequency resonance type inverter link DC-DC converter and characteristic evaluation", wherein 1 is a power supply, 2D1, 2D.
2, 3D1 and 3D2 are bridge-connected feedback diodes, and 4S1, 4S2, 5S1, and 5S2 are switching elements connected in parallel to the feedback diodes 2D1, 2D2, 3D1, and 3D2.

Further, reference numeral 6 denotes a resonance inductor, 7 denotes an auxiliary resonance inductor, 8 denotes a resonance capacitor, and 9 denotes a transformer, which are connected between the input side connection point and the output side connection point of the bridge. 10A and 10B are rectifying diodes, 11A and 11B are smoothing capacitors, and 12 is a load.

Next, the operation will be described. In a switching power supply, a series resonance converter uses a resonance phenomenon to reduce a voltage applied to each switching element or a current flowing through the switching element at a moment when the switching element is turned on and off in order to minimize a loss of the switching element. It is configured so that

According to this, in the bridge type resonant converter, the half cycle of the sine wave current is equal to the switching element 4S
1, 4S2, and the other half cycle is feedback diode 2D1,
In the mode flowing through the 2D2, there is a mode in which the switching elements 5S1 and 5S2 are turned on when current flows through the feedback diodes 2D1 and 2D2 depending on the load condition.

That is, two switching elements 4S
When both 1, 4S2 are closed at the same time, a current flows through the route of power supply 1 → switching element 4S1 → resonant capacitor 8 → transformer 9 → resonant inductor 6 → switching element 4S2 → power supply 1; , A sine wave due to the resonance current of the resonance capacitor 8 and the resonance inductor 6.

Next, during a period from when the switching elements 4S1 and 4S2 are opened and when the switching elements 5S1 and 5S2 are closed, the resonance current flows through the resonance capacitor 8 and is charged.

When this voltage becomes higher than the power supply voltage or the load voltage, the resonance capacitor 8 → period diode 2
D1 → power supply 1 → feedback diode 2D2 → resonant inductor 6 → transformer 9 → resonant capacitor 8 flows in a route, and the current flowing at this time also becomes a sine wave due to the resonant current of the resonant capacitor 8 and the resonant inductor 6. .

On the other hand, two switching elements 5S1, 5
If S2 is closed at the same time, power supply 1 → switching element 5S1 → resonance capacitor 8 → transformer 9 →
Resonant inductor 6 → switching element 5S2 → power supply 1
The current flows through the route.

Further, switching elements 5S1 and 5S2
Is opened and then the switching elements 4S1 and 4S2 are closed, and the discharging capacitor 8 → transformer 9 → resonating inductor 6 → feedback diode 3D2
→ power supply 1 → feedback diode 3D1 → resonance capacitor 8
The current flows through the route.

Therefore, as can be seen from the above-mentioned current route, a current flows through the transformer 9 over the entire period, and as shown in FIG.
With respect to the ON / OFF timing of the switching elements 4S1 and 4S2 and the switching elements 5S1 and 5S2 as shown in (b), a sine wave current as shown in FIG. Flows. Then, at this time, currents as shown in the A section and the B section flow through the feedback diodes 2D1 and 2D2 and the feedback diodes 3D1 and 3D2. As a result, currents as shown in FIGS. 7A and 7B flow through the switching elements 4S1 and 4S2 and the feedback diodes 3D1 and 3D2.

[0012]

Since the conventional series resonant converter is configured as described above, there is a mode in which the switching elements 5S1 and 5S2 are turned on when a current flows through the feedback diodes 2D1 and 2D2. Therefore, during a period in which the feedback diodes 2D1 and 2D2 recover, a short-circuit current flows through the route of the power supply 1 → the feedback diodes 2D1 and 2D2 → the switching elements 5S1 and 5S2. There were problems such as applying voltage and power stress.

The first aspect of the present invention has been made to solve the above-described problems, and a series resonance converter capable of reducing a stress applied to a switching element by suppressing a short-circuit current. The purpose is to:

Another object of the present invention is to provide a series resonant converter capable of suppressing a short-circuit current by using a short-circuit current limiting transformer inserted between feedback diodes.

A third object of the present invention is to provide a series resonant converter capable of suppressing a short-circuit current by a short-circuit current limiting transformer inserted between a power supply and each feedback diode in a forward series.

[0016]

According to a first aspect of the present invention, there is provided a series resonant converter comprising: at least four feedback diodes bridge-connected between a DC power supply and a load via a transformer; The connected switching element is connected between the input side connection point and the output side connection point of the bridge composed of the respective feedback diodes, and includes the switching element when the switching elements on the opposite sides of the bridge are simultaneously turned on. A resonance capacitor that allows a current having a resonance frequency to flow through the circuit, and a resonance inductor that forms a resonance circuit together with the resonance capacitor, wherein the resonance inductor is provided between the power supply and the bridge including the feedback diode. This is a connected short-circuit current limiting transformer.

In a series resonance converter according to a second aspect of the present invention, the resonance inductor is connected in the forward direction to the adjacent two inductors.
This is a short-circuit current limiting transformer connected between two feedback diodes.

According to a third aspect of the present invention, there is provided a series resonant converter, wherein the resonant inductor is a short-circuit current limiting transformer connected between a power supply and two adjacent feedback diodes connected in the forward direction. .

[0019]

According to the first aspect of the present invention, the short-circuit current flowing through the switching element via the feedback diode is suppressed by the short-circuit current limiting transformer inserted between the power supply and the bridge of the feedback diode.

In the series resonance converter according to the second aspect of the present invention, the short-circuit current flowing through the switching element via the feedback diode is suppressed by the short-circuit current limiting transformer inserted between the feedback diodes.

According to the third aspect of the present invention, the short-circuit current flowing through the switching element via the feedback diode is suppressed by the short-circuit current limiting transformer inserted between the power supply and the feedback diode connected in series in the forward direction. To do.

[0022]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a power source, 2D1 and 2,
D2, 3D1, and 3D2 are bridge-connected feedback diodes, and 4S1, 4S2, 5S1, and 5S2 are switching elements connected in parallel to the feedback diodes 2D1, 2D2, 3D1, and 3D2.

Reference numeral 7 denotes an auxiliary resonance inductor, 8 denotes a resonance capacitor, and 9 denotes a transformer, which are connected between the input side connection point and the output side connection point of the bridge. 10A and 10B are rectifying diodes, 11A and 11
B is a smoothing capacitor, and 12 is a load.

Further, reference numeral 13 denotes a power source 1 and a feedback diode 2.
D1, D2, 3D1, and 3D2, a short-circuit current limiting transformer connected to a bridge between the power supply 1 and the bridge, and connected between the power supply 1 and the bridge to store energy stored in the transformer 9 Is fed back to the power supply 1.

Next, the operation will be described. Also in this embodiment, in order to suppress the loss of each switching element, an operation is performed such that the applied voltage or current becomes zero by a resonance phenomenon at the moment when these elements are turned on and off. In this case, the short-circuit current limiting transformer 13 inserted between the power supply 1 and the bridge
When both S1 and 4S2 and switching elements 5S1 and 5S2 are on, they function as resonance inductors.

The short-circuit current limiting transformer 13
In the mode in which the switching elements 5S1 and 5S2 are turned on when a current flows through the feedback diodes 2D1 and 2D2, that is, in a short-circuit mode, it functions as a current-limiting inductor that suppresses the short-circuit current. That is, the current flowing through the switching elements 4S1 and 4S2 at this time becomes as shown in FIG.
The current flowing through D1 and 3D2 is stabilized as shown in FIG. 2B, and is significantly improved as compared with that shown in FIG. At this time, the short-circuit current controlling transformer 1
The energy stored in 3 is fed back to the power supply 1 via the feedback diode 14.

Embodiment 2 FIG. In the above embodiment, the short-circuit current limiting transformer 13 is inserted between the power supply 1 and the bridge as the main switching circuit. However, as shown in FIG. Between feedback diodes 2D1 and 3D1 and feedback diode 2D
A short-circuit current limiting transformer 16 may be inserted between 2 and 3D2.

According to this, since an inductance component enters between the switching elements 4S1 and 5S1 and between the switching elements 4S2 and 5S2 connected in series, the short-circuit current can be suppressed, the stress applied to the switching elements can be reduced, and the life of the switching elements can be reduced. And reliability is significantly improved. Further, since each switching circuit section including the switching elements 4S1 and 5S1 and 4S2 and 5S2 is connected in parallel to the power supply 1, the voltage applied to them does not exceed the power supply voltage.

Embodiment 3 FIG. FIG. 4 shows a power supply 1 and two adjacent feedback diodes 2D1 connected in a forward direction.
This shows a short-circuit current limiting transformer 18 connected between 3D1 and feedback diodes 2D2 and 3D2.

According to this, the short-circuit current can be suppressed for each of the switching elements 4S1 and 5S1 and the switching elements 4S2 and 5S2 connected in series, the stress on these can be individually and optimally suppressed, and the life and reliability can be improved.

[0031]

As described above, according to the first aspect of the present invention, at least four feedback diodes bridge-connected between a DC power supply and a load via a transformer, and each of the feedback diodes is connected in parallel. Switching element, connected between the input side connection point and the output side connection point of the bridge consisting of each feedback diode, when the switching element on the opposite side of the bridge is simultaneously turned on, the circuit including the switching element A resonance capacitor for flowing a current having a resonance frequency, and a resonance inductor forming a resonance circuit together with the resonance capacitor, wherein the resonance inductor is connected between the power supply and the bridge including the feedback diode. Since it is configured as a short-circuit current limiting transformer, each switch There is an effect that it can reduce the stress applied to the device can be obtained.

According to the second aspect of the present invention, the resonance inductor is configured as a short-circuit current limiting transformer connected between two adjacent feedback diodes connected in the forward direction. By introducing an inductance component between the diodes, that is, between the switching elements connected in series, the short-circuit current can be suppressed, and the stress applied to the switching elements can be suppressed.
There is an effect that a product that can improve the life and reliability can be obtained. Further, it is possible to prevent a voltage higher than the power supply voltage from being applied to each switching element.

According to the third aspect of the present invention, the resonant inductor is configured as a short-circuit current limiting transformer connected between the power supply and two adjacent feedback diodes connected in the forward direction. There is an effect that a short-circuit current can be individually and optimally suppressed for each switching element connected in series.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a series resonance converter according to an embodiment of the present invention.

FIG. 2 is a current waveform diagram showing a current flowing through a switching element and a feedback diode in FIG.

FIG. 3 is a circuit diagram showing a series resonance converter according to an embodiment of the present invention.

FIG. 4 is a circuit diagram showing a series resonant converter according to an embodiment of the present invention.

FIG. 5 is a circuit diagram showing a conventional series resonance converter.

6 is a timing chart showing the operation timing of the switching element in FIG. 5 and the waveform of a current flowing through a transformer.

FIG. 7 is a current waveform diagram showing a current flowing through a switching element and a feedback diode in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply (DC power supply) 2D1, 2D2, 3D1, 3D2 Feedback diode 4S1, 4S2, 5S1, 5S2 Switching element 8 Resonant capacitor 9 Transformer 13, 16, 18 Transformer for short-circuit current limiting

Claims (3)

(57) [Claims] At least four feedback diodes bridge-connected between a DC power supply and a load via a transformer, switching elements connected in parallel for each of the feedback diodes, and an input of a bridge composed of the feedback diodes. A resonance capacitor, which is connected between the side connection point and the output side connection point and causes a current having a resonance frequency to flow through a circuit including the switching element when the switching element on the opposite side of the bridge is simultaneously turned on; A series resonance converter including a resonance inductor that forms a resonance circuit together with a capacitor;
A series resonance converter comprising a short-circuit current limiting transformer connected between the power supply and the bridge including the feedback diode. 2. A feedback bridge connected between a DC power supply and a load via a transformer, at least four feedback diodes, a switching element connected in parallel for each feedback diode, and an input of a bridge comprising the feedback diodes. A resonance capacitor, which is connected between the side connection point and the output side connection point and causes a current having a resonance frequency to flow through a circuit including the switching element when the switching element on the opposite side of the bridge is simultaneously turned on; A series resonance converter including a resonance inductor that forms a resonance circuit together with a capacitor;
A series resonant converter, comprising a short-circuit current limiting transformer connected between two adjacent feedback diodes connected in the forward direction. 3. A feedback bridge connected between a DC power supply and a load via a transformer, at least four feedback diodes, a switching element connected in parallel for each feedback diode, and an input of a bridge comprising the feedback diodes. A resonance capacitor, which is connected between the side connection point and the output side connection point and causes a current having a resonance frequency to flow through a circuit including the switching element when the switching element on the opposite side of the bridge is simultaneously turned on; A series resonance converter comprising a resonance inductor and a resonance circuit together with a capacitor, wherein the resonance inductor is connected between the power supply and two adjacent feedback diodes connected in a forward direction to each other. A series resonant converter characterized by using a transformer for the device.