JPH0361204B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to phase control of AC power.

Conventionally, phase control circuits for AC power sources using bidirectional three-terminal thyristors, etc., were all directly connected to the AC power source, and there was a risk of electric shock when controlling the phase. In view of the drawbacks of the conventional circuit, the present invention provides a low-voltage firing angle control section that is completely insulated from the AC power source on the secondary (low voltage) side of a leaky three-legged transformer, and
Since the phase of the AC power supply is controlled by opening and closing a bidirectional three-terminal thyristor using the output signal of the second secondary coil that is electromagnetically coupled to the control unit, there is no risk of electric shock when operating the control unit. It is an object of the present invention to provide a completely novel and useful AC power phase control circuit.

The present invention will be described below based on drawings showing embodiments thereof. That is, in FIG. 1, 1 is a leaky three-legged transformer, and the primary coil 4 of the leaky three-legged transformer 1 is connected to the AC power supply 1.
Connected to 3. The first secondary coil 6 of the leaky three-legged transformer 1 is connected to a control unit as described below, and the output terminal of the second secondary coil 8 is
It is connected between the gate and cathode of a bidirectional three-terminal thyristor 14 such as a triac or thyristor via a full-wave rectifier circuit 16 consisting of a bridge diode and a resistor 15. Both ends of the AC power supply 13 are connected to the cathode of the bidirectional three-terminal thyristor 14 and the other end of a load 19 connected to the anode of the bidirectional three-terminal thyristor 14.

The control section includes a bidirectional three-terminal thyristor 9 inserted at both ends of the first secondary coil 6, and a trigger element 10 such as an SBS or a diagonal, a variable resistor 11, and a It is formed by connecting a trigger circuit consisting of a capacitor 12. In the figure, 7 is a switch for short-circuiting the first secondary coil 6, and 17 and 18 are resistors and capacitors for absorbing transient current.

To explain the operation of the circuit of the present invention, a low voltage (for example, 12V) induced in the first secondary coil 6 is charged to the capacitor 12 through the variable resistor 11, and the terminal voltage of the capacitor 12 exceeds the break-out point of the trigger element 10. When the voltage exceeds the voltage, the trigger element 10 exhibits negative resistance, so that the voltage stored in the capacitor 12 is released to the gate of the bidirectional three-terminal thyristor 9, triggering the bidirectional three-terminal thyristor 9. The trigger element 10, such as an SBS or a diak, generates pulses that are substantially symmetrical in both directions, and thus triggers the bidirectional three-terminal thyristor 9 in both directions to control its firing angle. Therefore, the first secondary coil 6 is repeatedly short-circuited with a constant phase with respect to the input voltage.

Here, the operation of the leaky three-legged transformer 1 will be explained using FIGS. 2 and 3, and the operation and operation of the present invention will be explained later.

In Fig. 2, when the primary coil 4 is connected to the power source 13 and energized, and the switches 7 at both ends of the secondary coil 6 are open, the primary magnetic flux Φ ₁ generated by the primary coil 4 is expressed by the solid line. Most of the magnetic flux Φ ₁ ' flows into the central leg 5 as shown in FIG. Induces low voltages that are 180° out of phase.

Since the open leg 2 with the gap G has a high magnetic resistance, only an extremely small amount of leakage magnetic flux Φ ₁ '' can pass through, and therefore the magnetic flux that interlinks with the second secondary coil 8 is also very small. induces only a very small voltage.

On the other hand, the switches 7 at both ends of the secondary coil 6
When the circuit is closed, a short-circuit current flows through the secondary coil 6, and a secondary magnetic flux Φ ₂ having an approximately opposite phase to the primary magnetic flux Φ ₁ ' is generated in the central leg 5, as shown by the dotted line in FIG. The magnetic flux Φ ₂ ' is divided into the first leg 3 around which the secondary coil 4 is wound, and the magnetic flux Φ ₂ ' is divided into the open leg 2.

When the short-circuit magnetic flux Φ ₂ ' of the secondary coil 6 flows through the first leg 3, the input to the primary coil 4 connected to the power supply 13 naturally increases, the primary magnetic flux Φ ₁ increases, and therefore the open leg 2 The magnetic flux Φ ₁ ″ flowing in also increases.

The open leg 2 has the short-circuit magnetic flux Φ ₂ ″ of the secondary coil 6 and 1
Since a large amount of the composite magnetic flux of the secondary magnetic flux Φ ₁ '' flows and interlinks with the second secondary coil 8, a voltage is induced in the second secondary coil 8, and from the power supply voltage waveform (Fig. 3 A, A).
An output as shown in FIG. 3B, which is delayed in phase by a little less than 360 degrees (in other words, slightly advanced in phase) is generated.

Since the leaky three-legged transformer has the above-mentioned characteristics, the operation of the present invention utilizing these characteristics will be explained with reference to FIGS. 1 and 3.

When the switch 7 is closed in FIG. 1, the second secondary coil 8
A voltage (Fig. 3B) is generated, and the full-wave rectifier circuit 16
and is applied to the gate of the main bidirectional three-terminal thyristor 14 connected in series with the load 19 to the power source 13 through the resistor 15 to ignite and conduct the bidirectional three-terminal thyristor 14 to the load 19. Supply electricity.

In addition, when the switch 7 is opened in FIG.
12V) charges the capacitor 12 through the variable resistor 11, and when the terminal voltage of the capacitor 12 becomes equal to or higher than the breakover voltage of the trigger element 10, the trigger element 10 becomes conductive and transfers the charge stored in the capacitor 12 to the first two terminals. The gate of the tropic three-terminal thyristor 9 is released and triggered.

The triggering element 10, such as an SBS or diak, generates symmetrical pulses in both directions, so that the first bidirectional three-terminal thyristor 9 fires in both directions. Third
FIG. C shows the waveform of the pulse of the trigger element applied to the gate of the first bidirectional three-terminal thyristor 9.

By adjusting the value of the variable resistor 11, this pulse can be selected from 1 to 10 times per half cycle of the secondary voltage of the secondary coil 6 (Fig. 3 A, B). The pulse generation timing can also be set arbitrarily within a half cycle, and is generated in synchronization with the power supply frequency.

In Fig. 1, the first bidirectional three-terminal thyristor 9 is triggered and conducts, and both ends of the secondary coil 6 are momentarily shorted, and the voltage waveform of the secondary coil 6 takes the form shown in Fig. 3D. show.

When both ends of the secondary coil 6 are short-circuited, leakage type 3
The output voltage of the second secondary coil 8 is generated by the function of the leg transformer, and the voltage waveform is changed by the variable resistor 1.
The phase of the pulse applied to the gate of the first bidirectional three-terminal thyristor 9, generated by the adjustment in step 1, coincides with the phase as shown in FIG. 3E.

The pulsed output voltage (FIG. 3E) of the second secondary coil 8 is applied to the gate of the second (main) bidirectional three-terminal thyristor 14 via the full-wave rectifier circuit 16 and the resistor 15. However, the voltage across the bidirectional three-terminal thyristor 14 triggered by the first pulse is as shown in FIG. 3F, and the voltage across the load 19 connected in series with the power source 13 is as shown in FIG. The result of phase control of the power supplied to the load 19 is obtained by supplying such a voltage.

Furthermore, as mentioned above, the output voltage waveform of the second secondary coil 8 (FIG. 3B) is slightly ahead in phase with the voltage waveform of the power supply 13 (FIG. 3A, A).
By adjusting the variable resistor 11, it is possible to output a pulse even at the zero-crossing point of the voltage waveform No. 3 (FIGS. 3A and 3A). Therefore, by adjusting the variable resistor 11, the phase of the power supplied to the load 19 can be controlled from the zero cross point and full ignition to any desired power.

In the above embodiment, the switch 7 always closes the first secondary coil 6.
is short-circuited, and the bidirectional three-terminal thyristor 14
This is to force the full ignition. Although it is possible to fully fire the bidirectional three-terminal thyristor 14 by adjusting the variable resistor 11 to make its resistance value zero, this can be instantaneously achieved by providing the switch 7. There is an advantage.

According to the present invention, by simply operating a variable resistor in a low-voltage control section that is completely isolated from the power supply,
Since the firing angle of the bidirectional three-terminal thyristor on the power supply side can be controlled, there is no risk of electric shock as in conventional circuits.

In addition, since the phase control circuit uses a leaky tripod transformer with a gap in the third leg, the signal voltage applied to the gate of the bidirectional three-terminal thyristor is ≈0 when the switch (or variable resistor) is opened. There is no risk of false firing.

In addition, since a leaky tripod transformer is used instead of using input and output transformers separately as in the past, the transformer can be provided in a small, lightweight, and low-cost manner, which naturally results in applications such as AC motors in application circuits, etc. The phase control circuit unit for the load can also be manufactured in a small size, light weight, and low cost.

In addition, the price of the transformer is lower than that of the conventional one.
3/4, and the required space is 70%, which means that for Japan's home appliance industry, the production scale will be 3/4 / 2020.
Considering the number of units produced in the millions, it is extremely valuable.

Furthermore, the variable resistor of the control section can be installed at a location separate from the main body of the transformer, so that it can be used as a so-called remote control switch, which is very convenient.

There are various advantages such as.

[Brief explanation of drawings]

The drawings are all for explaining embodiments of the present invention, and FIG. 1 is a circuit diagram of a phase control circuit according to the present invention, and FIG. 2 is a circuit diagram of a leaky type 3 used in the present invention.
Schematic front view of leg transformer, Figure 3 A, B, C,
D, E, F, and G are the power supply voltage, the induced voltage of the secondary coil 6, the induced voltage of the second secondary coil 8, the output pulse of the trigger element 10, the voltage of the secondary coil 6, and the second The output voltage of the secondary coil 8, the voltage across the second bidirectional three-terminal thyristor 14,
These are the voltage waveforms of the voltage across the load. 1...Leaky type 3 leg transformer, 2...Open leg, 3,5
...Non-open leg, 4...Primary coil, 6...First secondary coil, 8...Second secondary coil, 9...Bidirectional three-terminal thyristor, 11...Variable resistor, 13...AC power supply, 14... Bidirectional three-terminal thyristor, 19...Load.

Claims (1)

[Claims] 1. Wound a primary coil connected to an AC power source around one non-open leg of a leaky three-legged transformer in which one leg of the three-legged core is an open leg with a gap,
A first secondary coil is wound around the other non-open leg, and a second secondary coil is wound around the open leg, and
A first bidirectional three-terminal thyristor whose firing angle is made variable by a variable resistor in a trigger circuit is connected to both ends of the first secondary coil, and the load is connected to the output signal of the second secondary coil. 1. A phase control circuit for AC power using a leaky three-legged transformer, characterized in that the circuit is connected between AC power sources via a second bidirectional three-terminal thyristor that is opened and closed by a leakage type three-legged transformer.