JPH07123707A - Partial resonance type constant-frequency pwm controlled dc-dc converter - Google Patents

Abstract

PURPOSE:To make a main switch to make voltage and current zero operations when the switch is turned on and zero-voltage operations when the switch is turned off by constituting a resonance circuit by connecting an inductor for resonance and a capacitor for resonance between the dividing point of a transformer and the minus section of a power source. CONSTITUTION:A transformer resonance circuit is constituted by connecting an inductor Lr for resonance and a capacitor Cr for resonance to the minus section of a power source E from the dividing point of a transformer. Then a main switching section 1 is controlled to make partial resonance by connecting the transformer, a reverse flow preventing diode D1, and auxiliary switching element Sa in series with the power source E. When the section 1 makes partial resonance, the main switch So of the section 1 makes voltage zero and current zero operations when the switch So is turned on and zero-voltage operations when the switch is turned off. Therefore, the switching loss in the main switch element So or an auxiliary switch element Sa can be reduced and the switching frequency can be made higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an invention characterized by adding a partial resonance circuit unit for minimizing the switching loss of a DC / DC converter and reducing snubber circuit loss to zero. .

[0002]

2. Description of the Related Art DC / DC by a conventional PWM chopper
The main switch of the converter is ON / OFF controlled by, for example, a hard (forced) switching mode, and switching loss is large, and it is difficult to increase the frequency of the DC / DC converter. Moreover, the electromagnetic noise level was high and the application range was limited.

[0003]

As described in the prior art, DC / DC in the hard (forced) switching mode is used.
The DC converter has large voltage stress (dv / dt value) current stress (di / dt value) and switching loss that occur when the switch element is turned on and off, and the switching loss increases as the switching frequency becomes higher. Surge and current surge are liable to occur, and there is a limit to downsizing, weight reduction and loss reduction of the DC / DC converter, and further reduction of electromagnetic noise level.

However, according to the present invention, by reducing the switching loss of the switching element of the DC / DC converter, the switching frequency can be increased, and at the same time, the power supply equipment can be reduced in size, weight, loss, and electromagnetic noise. It is intended to be realized.

[0005]

To explain the main components of the present invention, a PWM chopper provided with a smoothing circuit composed of a choke coil L, a capacitor C and a flywheel diode D from a power source E via a main switching section. In the DC / DC converter, an auxiliary switch element S for controlling the partial resonance timing of the main switching part
In a, a high-frequency transformer T for supplying a commutation voltage and a backflow prevention diode D1 are connected in series to a power source E.

By connecting the resonance inductor Lr and the resonance capacitor Cr to the minus portion of the power source E from the division point P of the transformer T to form a transformer resonance circuit, the main switch operates at zero voltage and current at turn-on and turn-on at O.
The present invention relates to a partial resonance type constant frequency PWM control DC / DC converter which is characterized by zero voltage operation during FF.

Since the resonance inductor Lr can be used as a parasitic leakage inductor of the high frequency transformer T, it can be included in the transformer T.

[0008]

[Operation] The operation mode of the DC / DC converter of the present invention will be described below with reference to FIGS.

First, the auxiliary switch element Sa ON and the main switch element So OFF The current ilr flowing from the dividing point P through the inductor Lr is fixed to the capacitor Cr until it exceeds the current Io of the choke input filter flowing in the smoothing inductor.
The voltage Vcr between both ends is clamped to the forward voltage of the flywheel diode D.

Next, in mode 2, when ilr exceeds Io, the charging current icr = ilr-Io in the resonance capacitor Cr.
Flows and Vcr draws an arc of resonance and rises.

Next, in mode 3, when Vcr reaches the voltage of the power source E, the diode Do is rendered conductive, and the energy of Lr is regenerated to E and supplied to the load.

Within the section of Mode 3, the main switching element So is
To conduct.

At this time, both the voltage and the current are 0 V immediately before the main switch element So is turned on.

Next, in mode 4, the main switching element S
The current of o gradually rises from 0 A and supplies the load.

Next, in the section of mode 5, the secondary current of the transformer T first becomes 0, and it is provided to prevent ringing on the primary side due to the parasitic leakage inductance of the transformer T.

The diode Dr is for resetting the leakage inductor.

Next, in mode 6, turn-on of the partial resonance main switching element So up to mode 5 is completed, the auxiliary switching element Sa is turned off, and current is supplied to the load side through the main switching element So.

Next, in mode 7, since the main switching element So has the capacitor Cr, it is turned off in the zero volt switching mode.

Next, the mode 8 is the OF of the switching element So.
During period F, regenerative current of L is flywheel diode D
Is a section that is supplied to the load through.

As described above, when the main switch element So is turned on, the voltage is zero, when the current is zero and when it is turned off, the voltage is zero, and when the auxiliary switch element Sa is turned on and off, the current mode is zero. Not applied to the switch element.

As a result, the switching loss is minimized and the stress on the switch element is reduced.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings for an embodiment, in FIG. 4, Vr is a reference voltage, A is an error amplifier, F is an oscillation circuit, P is a pulse width modulation circuit, and B is a delay sequence circuit, which is suitable for a transformer T. A resonant inductor is formed by providing such parasitic leakage inductance.

The output voltage is compared with the reference voltage Vr, the error amplifier A feeds it back to the pulse width modulation circuit P, and the delay sequence circuit B feeds the main switching element Q ₂ ,
By driving the auxiliary switching element Q ₁ , a low-noise, high-performance partial resonance constant frequency P with a constant output voltage
It constitutes a WM-controlled DC / DC converter.

[0024]

Since the present invention is constructed as described above, it has the following effects.

Constant frequency PWM control can be easily realized, and stable constant current control and constant current control can be freely performed by a feedback signal of an output voltage or an output current, and a conventional control IC can be introduced.

The present invention is intended for step-down conversion, but can be expanded to step-up type and forward type.

A large capacity high frequency link DC / DC converter, high power factor converter, switching regulator, UPS, active filter, battery charger,
High-frequency electronic ballasts for high-pressure discharge lamps can be manufactured in a small size, with high efficiency and low noise.
It is a useful invention for aerospace applications.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention.

FIG. 2 is a diagram of each auxiliary mode of the circuit of the present invention.

FIG. 3 is a waveform diagram of steady-state circuit operation of the present invention.

FIG. 4 is a diagram illustrating an example of an implementation circuit of the present invention.

[Explanation of symbols] Main switching unit Smoothing circuit E Power source So Main switching device Sa Auxiliary switching device T Transformer D Flywheel diode C Capacitor Cr Resonance capacitor D1 Backflow prevention tire diode Dr diode Lr Resonance inductor R Load Vr Reference voltage A Error amplifier F Oscillation circuit P Pulse width modulation circuit B Delay sequence circuit

Claims (1)

[Claims] 1. A partial resonance PWM control DC / DC converter provided with a smoothing circuit composed of a choke coil L, a smoothing capacitor C and a flywheel diode D from a DC power source E via a main switching part. Switching element Sa for controlling partial resonance of
Has a transformer T and a backflow prevention diode D1 connected in series to a power source E. By connecting the resonance inductor Lr and the resonance capacitor Cr to the negative portion of the power source E from the division point P of the transformer T to form a resonance circuit, the main switch operates at zero voltage and current when turned on, and turns off.
The present invention relates to a partial resonance type constant frequency PWM DC / DC converter which is characterized by operating at zero voltage.