JPS585587B2 - Inverter - Google Patents

Description

[Detailed description of the invention] There is an inperter as shown in FIG.

That is, the input AC voltage from the AC power supply 1 is supplied to the rectifier circuit 2, and the rectified output is supplied to the series circuit of the capacitor 11.12, and the transistor 21.22.
A series circuit between the collector and emitter of the capacitor 11
, 12 series circuits are connected in parallel.

The coils 31 and 32 of the oscillation transformer 30 are connected between the base and emitter of the transistors 21 and 22, respectively, and the emitter of the transistor 21 and the collector of the transistor 22 are connected through the current feedback coil 33 of the transformer 30, and further connected to the power transformer. 40 input coils 4
1 to the connection point between capacitors 11 and 12.

Further, the feedback coil 43 of the transformer 40 is connected to the voltage feedback coil 34 of the transformer 30 through the resistor 3, and the rectifier circuit 4 and the smoothing circuit 5 are connected to the output coil 42 of the transformer 40.

Note that 6 is an output terminal. Therefore, transistor 21.
22 is alternately turned on and off, an alternating voltage is supplied to the input coil 41 of the transformer 40, so that a desired DC voltage is taken out to the terminal 6.

At this time, current feedback is performed by the AC current flowing through the input coil 41 flowing through the coil 33 of the transformer 30, and voltage feedback is performed by supplying the AC voltage generated in the coil 43 to the coil 34. The above-mentioned transistors 21 and 22 are repeatedly turned on and off.

According to such an inverter, by keeping its oscillation frequency high, for example, 20 kHz, the power transformer 40 can be made smaller and lighter, and the whole can also be made smaller and lighter.

Furthermore, power transformers such as audio main amplifiers are extremely large, which limits the size, design, and component arrangement of the main amplifier.
Since its shape can be freely designed, there are no restrictions on the size, design, or component arrangement of the main amplifier in which this inverter is used.

By the way, the AC equivalent circuit of such an inverter is
It is shown as in Figure A.

That is, the transistors 21 and 22 and the oscillation transformer 3
Since oscillation is performed by 0, these are represented as an oscillator 7, and the distributed capacitance between the collector of the transistor 22 and the chassis is represented as a capacitance 8.

Note that point A indicates the collector of the transistor 22.

However, in such a circuit, unnecessary radiation is emitted through the input power supply 1.

In particular, since the oscillation of the oscillator 7 is a square wave oscillation and its oscillation frequency is high, unnecessary radiation occurs over a wide frequency range.

Therefore, when used as a power source for audio equipment, for example,
This causes problems such as a decrease in S/N.

In view of these points, the present invention aims to eliminate unnecessary radiation generated in this type of inverter.

Therefore, in the present invention, the heat sink for heat dissipation of the transistor 22 is connected to the AC zero potential point on the input side.

That is, the transistors 21 and 22 are generally attached to a heat sink for heat dissipation, but as shown in FIG. As shown, the transistor 22 is insulated and attached to a heat sink 52 via an insulating thin plate 51 such as Mylar, and the heat sink 52 is insulated from the chassis 56 by screws 55 via insulating washers 53 and 54. Attach.

Then, as shown in FIG. 3, the heat sink 52 is connected to the connection point between the capacitors 11 and 12.

According to this configuration, as shown in FIG. 2B, the capacitor 9 is configured by the case (collector) of the transistor 22 and the heat sink 52, and the capacitor 10 is configured by the heat sink 52 and the chassis 56. The midpoint between the capacitors 9 and 10 will be connected to the input power supply 1 through capacitors 11 and 12.

Therefore, since the oscillator T is short-circuited through the capacitors 12 and 9, even if the oscillator 7 generates an unnecessary radiation component, this does not go out to the input power supply 1 as unnecessary radiation.

Note that in this case, the collector of the transistor 21 is connected to the capacitor 11, so there is no problem.

Thus, according to the present invention, unnecessary radiation of the inverter can be eliminated, and the S/N ratio of electronic equipment in which the inverter is used will not be lowered or interference will be caused.

Moreover, the configuration is such that the heat sink 52 is replaced by the capacitor 11.
．． It is extremely simple and inexpensive since it only needs to be connected to 12 connection midpoints.

The heat dissipation of the transistor 22 is not hindered yet.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram of a conventional example, FIG. 2 is an equivalent circuit diagram thereof, FIG. 3 is a connection diagram of an example of the present invention, and FIG. 4 is a sectional view of a part thereof. 1 is an input AC power supply, 6 is an output terminal, and 52 is a heat sink.

Claims (1)

[Claims] 1: a first rectifier circuit that forms a first DC voltage from a human-powered AC voltage; a transformer; a transformer that switches the first DC voltage and intermittently supplies it to the input coil of the transformer; In an inverter having a switching element that obtains an alternating current voltage, and a second rectifier circuit that forms a desired second direct current voltage from the alternating current voltage, the switching element is installed insulated from a heat sink for heat dissipation, and an inverter in which the heat sink is provided insulated from the chassis, and the heat sink is connected to the first rectifier circuit through a capacitor.