JPH01234056A - Voltage resonance type converter - Google Patents

Abstract

PURPOSE:To lower the noise of an apparatus and to raise the efficiency thereof, by turning OFF switching elements via a transistor by the sensed output of a resonance current. CONSTITUTION:A voltage resonance type converter is composed of a DC power supply V1, a smoothing capacitor C1 on the power supply side, a transformer T1 having primary - tertiary windings n11-n13, a rectifying diode D, a smoothing capacitor C on the output side, a resonance capacitor C2, diodes D1-D3, an ON-OFF transistor (Tr) Q1, a turn-OFF Tr Q2, and a base circuit capacitor C3. Then, the resonance current of said resonance capacitor C2 is sensed by said diodes D2-D3 to turn ON the Tr Q2 and to turn OFF the Tr Q1 rapidly. Thus, while the voltage of the both ends of the Tr Q1 does not rise, the electric current of said Tr Q1 is cut OFF, so that the loss of Tr Q1 is controlled.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a general-purpose DC-DC converter that is characterized by low noise, high efficiency, high power, and low cost, and more particularly relates to a voltage resonant converter. .

(Prior Art and Problems to be Solved by the Invention) Conventionally, various DC-DC converters have been proposed. Examples of these DC-DC converters include those shown in FIGS. 5 to 7.

Figure 5 shows an on-off type converter, where the power supply voltage
, is turned on and off by transistor Q0, and 1 of transformer T0
The current in the secondary winding no+ is interrupted, the voltage induced in the secondary winding net of the transformer To is rectified by diode D, and smoothed by capacitor C, resulting in an output voltage ■. Convert to The base circuit of the transistor Q0 is driven by the voltage induced in the tertiary winding n03 of the transformer T0, and oscillates according to the constants of each part.

Since this circuit cannot operate in quasi-E class operation, it has large losses and has problems in achieving high efficiency and miniaturization.

Also, what is shown in Fig. 6 is a voltage resonance type on-off converter, and this converter also uses a transistor Q.

The current in the primary winding net of the transformer T0 is intermittent, and the DC power supply ■1 outputs the voltage ■. Convert to In this circuit, the inductance of the primary winding not of the transformer T0 and the Koni/dancer C0 resonate to regulate the oscillation frequency. In this converter, transistor Q0 has poor turn-off characteristics and large losses. Therefore, there is a problem in achieving high efficiency.

Furthermore, FIG. 7 shows a separately excited voltage resonant converter, which converts a DC power source V into a DC voltage V0 by turning on and off a transistor Q. This converter has an output voltage control function. That is, the output voltage v0 is input to the error amplifier 1, and the primary side of the photocoupler H() and the
Furthermore, the current of the flywheel diode is detected by a current transformer CT to drive the synchronous oscillator 4, and its output is input to the amplifier 3, and the current of the flywheel diode is This is a passive voltage resonant converter that drives Q0. This converter has a problem of complicated circuit configuration and high cost.

In view of the above problems, the present invention has low noise and high efficiency.

The purpose of the present invention is to provide a voltage resonant converter that features high power and low cost.

(Means for Solving the Problems) The present invention has been proposed to achieve the above objects,
A voltage obtained by connecting an on/off switching element in series with the primary winding of the transformer, driving the switching element with the induced voltage of the tertiary winding of the transformer, and rectifying and smoothing the output of the secondary winding of the transformer. The gist of the present invention is a voltage resonant converter, characterized in that the converter includes a detection circuit that detects a resonant current, and the switching element is turned off via a transistor by the output of the detection circuit.

(Example) Embodiments of the present invention will be described below along with the drawings.

It should be noted that the embodiments are merely illustrative, and it goes without saying that various changes and improvements may be made without departing from the spirit of the present invention.

Fig. 1 is a circuit diagram showing the first embodiment of the present invention. .Tertiary winding n
13 is a wound conversion transformer, D is a rectifying diode, C is a smoothing capacitor on the output side, C2 is a resonant capacitor, D is a diode, Di and Ds are detection diodes, and Ql is an on/off switch. Transistor, Qt is transistor Q.

Turn-off transistor, C3-dranister Q
, is the base circuit capacitor of .

Next, the operation of this circuit will be explained with reference to the waveform diagram in FIG.

The present invention is an on-off voltage resonant converter that operates as a quasi-class E converter. In this circuit configuration, the resonant current r of the resonant capacitor is connected to the detection diode D2.
Voltage of diode D1 at D3. Detects and turns on transistor Q2, which turns on/off transistor Q, which is a switching element.

By rapidly turning off the on-off transistor Q, the current rc of the on-off transistor Q is cut off while the voltage (2) across the on-off transistor Q does not rise, thereby suppressing the loss of the transistor Q. VIIE is the base-emitter voltage of transistor Q.

Next, FIG. 3 is a circuit diagram showing a second embodiment of the present invention, in which the detection diodes Dz and Di of the first embodiment shown in FIG. 1 are replaced with a resistor R. It is.

Further, FIG. 4 is a circuit diagram showing a third embodiment of the present invention, in which a current transformer CT is used instead of the detection diodes D t, , D s of the first embodiment shown in FIG. , has been replaced with .

The circuits shown in FIGS. 3 and 4 operate similarly to the circuit shown in FIG. 1, except that the detection circuit is changed.

(Effects of the Invention) As explained above, according to the present invention, an on/off switching element is connected in series with the primary winding of a transformer, and the switching element is driven by the induced voltage of the tertiary winding of the transformer, A voltage resonant converter configured by rectifying and smoothing the output of the secondary winding of the transformer, comprising a detection circuit for detecting a resonant current, and turning off the switching element via a transistor by the output of the detection circuit, A low-noise, high-efficiency, high-power, low-cost voltage resonant converter can be provided.

[Brief explanation of the drawing]

1, 3, and 4 respectively show the first embodiment of the present invention. Second. and a circuit diagram showing the third embodiment, FIG. 2 is a waveform diagram explaining the operation of the first circuit, and FIGS. 5 to 7 are circuit diagrams showing various conventional converters. T1...Transformer, D, D,...Diode, D,, D3...Detection diode, C,C,. C,,C,...Capacitor, Ql...On/off transistor, Q! ...transistor patent applicant
Takayama, Patent Attorney, Tamura Seisakusho Co., Ltd.
Michio (1 other person) ゛ ) Figure 2

Claims (1)

[Claims] A voltage obtained by connecting an on/off switching element in series with the primary winding of the transformer, driving the switching element with the induced voltage of the tertiary winding of the transformer, and rectifying and smoothing the output of the secondary winding of the transformer. 1. A voltage resonant converter, comprising: a detection circuit that detects a resonant current; and an output of the detection circuit turns off the switching element via a transistor.