JPS6033744Y2 - DC-DC converter with start-up compensation function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC-DC converter with a start-up compensation function, and more particularly to a DC-DC converter with a start-up compensation function that compensates for start-up performance in the case of a capacitive load.

To obtain high voltage DC from a low voltage DC source such as a battery, use DC-
A DC:7 inverter is used.

Figures 1 and 2 show general C-DC converters using transistor oscillation circuits. are shown respectively.

In FIG. 1, the collector of the transistor Q□ of the collector-grounded oscillator circuit 1 is connected to the low voltage source B via the switch S, and the base of the transistor Q1 is provided with a base bias via the resistor R□. It has become.

Further, a capacitor C□ is connected between the base and emitter of the transistor Q1, and the first winding of the transformer T1 is connected via a resistor R2.

A diode D□ is connected in parallel to this first winding L1, and a bypass is configured to prevent damage to the transistor Q□ due to reverse bias between the base and emitter of the transistor Q1. are doing.

The emitter side of the second winding is further grounded via the second winding L2 of the transformer T1.

The oscillation output of such a collector-grounded oscillator circuit 1 is transmitted through a rectifying diode D connected to the third winding of the transformer T□.
2 and supplied to the load LD.

By the way, if the load is capacitive in the above case, the inrush current when the switch S is closed will be very large, which will cause the ambient temperature to rise and the characteristics of the circuit elements of the oscillation circuit 1, especially the characteristics of the transformer T1 to deteriorate. If the impedance changes and impedance mismatch occurs, there is a risk that startup will not be possible.

On the other hand, in FIG. 2, the collector of the transistor Q2 of the common emitter oscillation circuit 2 is connected to the first winding L4 of the transformer T2.
and a low voltage source B via a switch S, a resistor R3 is connected to the base of the transistor Q2, and a second voltage source of the transformer T2 is connected to the base of the transistor Q2.
Base bias is provided through the winding and resistor R4.

Further, a diode D3 forming a bypass is connected between the base and emitter of the transistor Q2 to prevent damage to the transistor Q2 due to a reverse bias between them.

The second winding L5 is grounded at one end by a resistor R6 and a capacitor C2.

The oscillation output of the emitter grounded oscillator circuit 2 is as follows:
It is rectified by a rectifying diode D2 connected to the third winding L6 of the transformer T2, and is supplied to the load LD.

Even in this case, if the load LD is capacitive, the first
This causes the same inconvenience as the circuit shown in the figure.

In view of the above points, the present invention aims to provide a DC-DC converter with a start-up compensation function, which improves start-up performance by ensuring start-up even in the case of a capacitive load. .

Embodiments of the DC-DC converter with start-up compensation function according to the present invention will be described below with reference to the drawings.

FIG. 3 shows a case where the present invention is applied to a DC-DC converter including a collector-grounded oscillator circuit.

In this figure, the low voltage source B side and the load LD are connected by a series circuit of a resistor R6 and a diode D4, and the load LD is charged at the same time as the switch S is closed.

The other configurations are the same as in FIG. 1. According to the above configuration, since the load LD is charged by the low voltage source B via the resistor R6 and the diode D4 from the moment the switch S is closed, the impedance of the load LD as seen from the common collector oscillator circuit 1 becomes high. At the beginning of the startup of oscillation circuit 1, the load LD
No inrush current flows.

As a result, the oscillation circuit 1 is in a state where it is easy to oscillate, and the start-up performance is greatly improved, and even if the characteristics of the circuit elements change due to a large change in the ambient temperature, the oscillation circuit 1 can be started up reliably.

After the oscillation circuit 1 is started, a normal boosted voltage obtained by rectifying the oscillation output with the diode D2 is applied to the load LD.

In this case, since the diode D is cut off, the boosted voltage will not flow back to the low voltage source B side.

FIG. 4 shows another embodiment in which the present invention is applied to a DC-DC converter including a grounded emitter oscillation circuit 2.

In this figure as well, the low voltage source B side and the load LD are connected by a series circuit of a resistor R6 and a diode D, so that the load LD is filled at the same time as the switch S is closed.

This embodiment also provides the same effect as the case of FIG. 3.

As described above, according to the present invention, there is obtained a DC-DC:1 inverter with a start-up compensation function, which is capable of reliably starting even in the case of a capacitive load and improves start-up performance.

[Brief explanation of the drawing]

Fig. 1 Conventional DC-D with collector grounded oscillator circuit
2 is a circuit diagram showing a conventional DC-DC converter having an emitter-connected topographical oscillation circuit, and FIG. 3 is a circuit diagram showing a DC-DC converter with a start-up compensation function according to the present invention.
Embodiment of Converter and Circuit Diagram FIG. 4 is a circuit diagram showing another embodiment of the present invention. 1... Collector grounded oscillation circuit, 2...
Emitter grounded oscillator circuit, B...Low pressure source, C□
, C2... Capacitor, R1 to R6...
...Resistor, Dl to D4...Diode, Q
l, Q2...Transistor, LD...
load.

Claims (1)

[Scope of utility model registration request] a low-voltage DC source, a collector-grounded or emitter-grounded transistor oscillation circuit having a transistor and a transformer, and a switch for connecting the low-voltage DC source and the transistor oscillation circuit, the rectified output of the output winding of the transformer; In a DC-DC:y inverter that supplies a capacitive load, a resistor and a diode are connected between the switching oscillation circuit side end and the load side in a forward direction from the low voltage DC source side toward the load side. A DC-DC:l inverter with a start-up compensation function, characterized in that the DC-DC:1 inverter is connected in a series circuit.