JPH04271267A - Power supply - Google Patents

Abstract

PURPOSE:To provide a low loss, high efficient power supply in which a difference is set between rising times of positive and negative output voltages. CONSTITUTION:A transformer 4 is connected through an input filter 3 and a switching element 2 to the input terminal 1 of a power supply. A negative voltage output terminal 11 is connected through a negative system rectifying circuit 9 to the secondary of the transformer 4 to which a rectifying transistor 5, a free wheel transistor 6, a control transistor 7 and a control circuit 8 are further connected, and a positive voltage output terminal 10 is connected thereto through an inductor 12 and a capacitor 13.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for supplying power to electronic circuits, equipment, etc.

0002

2. Description of the Related Art FIG. 3 is a diagram showing a conventional power supply device. In the figure, 1 is an input terminal, 2 is a switching element,
3 is an input filter, 4 is a transformer, 9 is a negative system rectifier circuit, 10 is a positive voltage output terminal, 11 is a negative voltage output terminal, 17
18 is a transistor, and 19 is a control circuit.

For example, consider a high-output amplification device using an FET as an amplification element as a load of a power supply device. This FE
Two output systems are required as a power supply device to operate the T. That is, a positive voltage is supplied to the drain of the FET, and a negative voltage is supplied to the gate. In addition, in order to prevent the FET from being thermally destroyed when starting up the amplifier,
As a bias for T, a negative voltage must first be applied to the gate, and then a positive voltage must be applied to the drain. Therefore, a power supply device used to supply power to such a high-output amplifier device needs to satisfy the above-mentioned performance.

In FIG. 2, a voltage input from an input terminal 1 is converted by a switching element 2 into a rectangular waveform having an appropriate on time. This rectangular wave voltage is applied between the windings on the primary side of the transformer 4. As a result, positive and negative voltages are excited on the secondary side of the transformer 4, and these are rectified by the negative system rectifier circuit 9 and the positive system rectifier circuit 17. The voltage is output. The control circuit 19 that receives the positive and negative voltages applies a voltage to the base of the transistor 18 so as to turn the transistor 18 on after a certain period of time has elapsed. As a result, after a certain period of time has passed since the negative voltage was generated at the negative voltage output terminal 11 of the power supply device,
A positive voltage is generated at the positive voltage output terminal 10.

[0005]

Since the conventional power supply device is constructed as described above, it is necessary to insert a transistor for an output switch in series with the output line. Therefore, power loss occurs due to the conduction resistance of the transistor. In addition, there were other problems such as a complicated control circuit. Particularly when a power supply device with a large output capacity has a large amount of output current, the voltage loss in the transistor cannot be ignored, which greatly affects the deterioration of the efficiency of the entire power supply device.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a power supply device that can provide a time difference in the rise of the output voltage and has less loss.

[0007]

[Means for Solving the Problems] A power supply device according to the present invention uses a rectification switching element and a control switching element in a rectification circuit.

[0008]

[Operation] By using the rectifying switching element and the controlling switching element in the rectifying circuit, the power supply device according to the present invention can provide a time difference in the rise of the output voltage and has low loss.

[0009]

[Example] Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, numerals 1 to 4 and 9 to 11 are exactly the same as the conventional device described above. 5 is a rectifying Yang transistor, 6 is a freewheel transistor, 7 is a control transistor, 8 is a control circuit, 12 is an inductor, and 13 is a capacitor.

In FIG. 1, a voltage input from an input terminal 1 is converted by a switching element 2 into a rectangular wave having an appropriate on-duty. This rectangular wave voltage excites the primary side of the transformer 4. Along with this, transformer 4
Positive and negative voltages are excited in the form of a rectangular wave on the secondary side of the circuit, which is rectified by the negative system rectifier circuit 9, which outputs a negative voltage with only a DC component.

This negative voltage is applied by the control circuit 8 to the base of the transistor 7 so as to turn on the control transistor 7 after a certain period of time has elapsed. As a result, the control transistor maintains its conductive state after a certain period of time has elapsed since the negative voltage was generated at the negative voltage output terminal 11 of the power supply device.

When the switching element 2 is turned on in this state, the voltage input from the input terminal 1 is applied to the primary winding of the transformer 4. Along with this, transformer 4
A voltage is excited in the secondary winding of. At this time, since the control transistor 7 is in a conductive state, a voltage is applied to the base of the rectifying transistor 5, and the rectifying transistor 5 becomes conductive, but the base of the freewheeling transistor 6 is in a reverse direction. is applied, and the freewheel transistor 6 becomes open. As a result, power on the primary side is supplied to the positive voltage output terminal 10 through the transformer 4. Further, the current on the secondary side at this time flows along the path indicated by the arrow in FIG.

Next, when the control transistor 7 is in a conductive state and the switching element 2 is in an off state, a reverse voltage is applied to the base of the rectifying transistor 5, and the rectifying transistor 5 is in an open state, and the freewheeling transistor is turned off. A forward voltage is applied to the base of transistor 6, and freewheeling transistor 6 becomes conductive. As a result, when the switching element 2 is in the off state, the transistor 4
The power supply from the primary side to the output end through the is cut off. However, since the freewheel transistor 6 becomes conductive, the back electromotive force generated in the inductor 12 causes
Current flows through the path of the middle dotted line. Therefore inductor 1
A current always flows through the positive voltage output terminal 1 regardless of whether the switching element 2 is on or off.
Voltage is supplied to the load from 0.

Example 2. FIG. 2 shows another embodiment of the present invention, in which 1 to 4 and 8 to 13 are the same as in FIG. 1, 14 is a rectifying FET, 15 is a freewheel FET, and 16 is a control FET. In the first embodiment, the rectifying transistor 5, the freewheel transistor 6, and the control transistor 7 are used, but in this embodiment, the rectifying FET 1
4. Similar operation can be expected when using the freewheel FET 15 and the control FET 16.

[0015]

[Effects of the Invention] As described above, according to the present invention, a rectifying switching element, a freewheel switching element, and a control switching element are used in the rectifying circuit on the secondary side. It is possible to provide a time difference in the rise time, and there is an effect that a low loss can be obtained.

[Brief explanation of the drawing]

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

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a power supply device of the present invention.

[Explanation of symbols]

1 Input terminal 2 Switching element 3 Input filter 4 Transformer 5 Rectifier transistor 6 Freewheel transistor 7 Transistor for control 9 8 Control circuit 9 Negative system rectifier circuit 10 Negative and positive voltage output terminal 11 Positive voltage output terminal 12 Inductor 13 Capacitor 14 Rectifier FET 15 Freewheel FET 16 FET for control circuit 17 Positive system rectifier circuit 18 Transistor 19 Control circuit

Claims (1)

[Claims] Claim 1: An input terminal for applying a primary side voltage, an input filter connected to this input terminal, a switching element connected to this input filter and converting the input voltage into a rectangular waveform, and this switching element. A transformer connected to the above input filter to ensure DC component insulation between the primary and secondary sides of the power supply, and a rectifier switching element and a freewheel switching element connected to the secondary side of this transformer. , an inductor and a capacitor located on the output side of this freewheel switching element for rectifying a rectangular wave, an output terminal connected to the output side of this inductor and capacitor for outputting a voltage, and the above transformer. a rectifying circuit connected to the secondary side of the rectifying circuit; a control circuit and a control switching element for receiving the output of the rectifying circuit and controlling the operation of the rectifying switching element; and a control switching element connected to the output side of the rectifying circuit; A power supply device comprising an output terminal for outputting voltage.