JPH0557606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an AC power phase control circuit that utilizes the characteristics of a leaky tripod transformer.

Conventionally, all AC power phase control circuits using triaxes and the like were directly connected to an AC power source, and there was a risk of electric shock when performing phase control operations. To solve this problem, when performing remote control from the low voltage operation circuit side, when using a photocoupler non-contact relay as shown in Figure 1, a power supply (DC or AC) is required for operation input, making it difficult to control on and off. Even if it were possible to do so, it would not be possible to control the phase, so a separate control circuit would be required to control the phase. Further, even if a transformer is used as shown in FIG. 2, it is necessary to insulate the pulse generating circuit from the triac gate circuit. All of the above conventional examples have a large number of parts, and when remote control is performed using non-contact low voltage operation, a step-down transformer, pulse transformer, and
It is necessary to use photocouplers, reed relays, etc., and the wiring of the power supply and operation circuits is complicated and expensive.

In order to eliminate such drawbacks of the conventional circuit, the present invention provides a low-voltage firing angle control section that is completely insulated from the AC power supply on the secondary side of the leaky tripod transformer, and also An object of the present invention is to provide a circuit that controls alternating current power by controlling the firing angle of a bidirectional three-terminal thyristor using the output signal of a tertiary coil that is electrically coupled to a bidirectional three-terminal thyristor.

Before explaining the configuration of the present invention, the configuration of the leaky tripod transformer will first be described. As shown in FIG. 4, the tripod transformer 1 has a tripod iron core having outer legs 2, 4 and a center leg 3, and the outer leg 4 is provided with a gap 5. A primary coil 6 is wound around the outer leg 2.
A secondary coil 7 is wound around the central leg 3, and a tertiary coil 8 is wound around the other outer legs 4 so as to induce a low voltage.

FIG. 3 shows an AC power phase control circuit which is an embodiment of the present invention. In this example circuit, the tripod transformer 1 is used, both sides of the primary coil 6 are connected to the power source 12, and the tertiary coil 8 is connected to the power source 12.
One end is connected to the gate of a bidirectional three-terminal thyristor 14 connected in series with a load 13 connected in parallel to the power supply 12 via a pair of antiparallel-connected diodes 15, and the other end is connected to the bidirectional It is connected to the cathode of the three-terminal thyristor 14. The secondary coil 7 of the center leg 3 is connected to a full-wave rectifier 16, and on both sides of the DC side there is a series circuit of a resistor 18, a switch 17, a variable resistor 19, and a capacitor 20, and an NPN transistor 21 (with the collector on the + side and the emitter on the + side). (connected to the - side) and two resistors 2 connected in series
2 and 23, and the connection point of the resistors 22 and 23 is connected to the base of the PNP type transistor 24, and the PNP
The collector of the PNP type transistor 24 is connected to the base of the NPN type transistor 21 via a voltage divider circuit including resistors 25 and 26, and the emitter of the PNP type transistor 24 is connected to the connection point of the variable resistor 19 and the capacitor 20. ing.

First, the operation of the tripod transformer 1 will be explained, and then the operation and operation of the circuit of the above embodiment will be explained. In addition, FIG. 5 is a waveform diagram for explaining the operation, A is a power supply voltage waveform (thick line), a tertiary voltage waveform diagram when the secondary coil is shorted (thin line), and B is a diagram of the pulse signal applied to the base of the transistor 21. Waveform (during phase control), C is the voltage waveform between the connector and emitter of transistor 21 (during phase control), D is the voltage waveform at 2 o'clock during phase control, E is the tertiary voltage waveform during phase control, F is the phase Each shows the load voltage waveform during control.

In FIG. 4, when the primary coil 6 is connected to the power supply 12 and energized, if the secondary coil 7 is open, most of the primary magnetic flux φ ₁ is as shown by the solid line, and most of the magnetic flux φ ₁ ' flows through the central leg 3. However, only a small amount of leakage magnetic flux φ ₁ ″ passes through the outer leg 4 where the gap 5 is located, so only a very small voltage is generated in the tertiary coil 8. .But 2
When the secondary coil 7 is short-circuited with the switch 17', a short-circuit current flows and a secondary magnetic flux φ ₂ in the opposite direction to the magnetic flux φ ₁ ' is generated, and the magnetic flux φ 2 '' on the outer leg ₄ side and the magnetic flux φ ₂ on the outer leg 2 side are generated. ' As shown by the dotted line, the combined magnetic flux of the magnetic flux φ ₁ '' increased by the short circuit and the magnetic flux φ ₂ '' passes through the outer leg 4 where the gap 5 is located, so that the tertiary coil 8 receives a voltage of 360° from the power supply voltage. In other words, this tertiary voltage is considered to be a voltage that is slightly ahead of the power supply voltage (bold line A in Fig. 5) (thin line A in Fig. 5).In this leakage type tripod transformer, Corresponding to the short circuit of the secondary coil 7, the voltage of the tertiary coil 8 is delayed by a little less than 360 degrees, that is, it is considered to be approximately in phase with the power supply (A in Figure 5).
Moreover, it has the characteristic of being induced by a slightly advancing voltage. This feature of the invention is exploited.

Next, the operation of the embodiment circuit shown in FIG. 3 will be explained.

When the switch 17 is open, no voltage is applied to the emitter of the PNP transistor 24, so it does not turn on, and therefore the NPN transistor 21
Since no voltage is applied to the base of the secondary coil 7 in the off state and the secondary coil 7 is not short-circuited, no voltage is generated in the tertiary coil 8. Therefore, no signal is applied to the gate of the bidirectional three-terminal thyristor 14 and it does not fire, so no power supply voltage is applied to the load.

However, when the switch 17 is closed, the capacitor 20 is charged through the resistor 18 and the variable resistor 19, and the emitter voltage of the PNP transistor 24 increases, and the voltage at the base of the PNP transistor 24, which is applied with a divided voltage by the resistors 22 and 23, increases. When the voltage exceeds the voltage, the base current flows and turns on, and the charges stored in the capacitor 20 are discharged through the resistors 25 and 26, causing a pulse to oscillate (FIG. 5, b). The charging and discharging of the capacitor 20 is repeated one to ten times during a half cycle depending on the adjustment of the variable resistor 19, and the first pulse in the half cycle is generated in synchronization with the power supply frequency. Therefore, the voltage drop across the resistor 26 due to the pulse is applied to the base of the NPN transistor 21, turning on the NPN transistor 21, and the secondary coil 7 is connected to the pulse signal (in FIG. 5) via the full-wave rectifier 16. ) is shorted. tripod transformer 1
Due to the characteristics of The element is ignited, and a phase-controlled voltage (f in FIG. 5) is applied to the load 13. When the variable resistor 19 is 0, the PNP transistor 24 charged through the current-limiting resistor 18 and discharged through the resistors 25 and 26 increase the number of oscillation circuits during a half cycle, and the tertiary voltage increases with respect to the power supply voltage. Bidirectional three-terminal cyclister 14 with zero cross firing due to phase shift
is in full ignition state. As the resistance of the variable resistor 19 is increased, the charging time becomes longer and pulse oscillations as shown in Fig. 5B occur.The number of pulses gradually decreases, approaching the state where the switch 17 is open, and the phase angle changes from 0 to 180. The firing angle of the bidirectional three-terminal thyristor 14 can also be changed from 0 to 180 degrees.
It is possible to control the phase of AC power.

Further, since the voltage of the tertiary coil when the secondary coil is open is small, the voltage drop across the two parallel-connected diodes 15 is sufficient to prevent malfunction of the bidirectional three-terminal thyristor 14.

A resistor 27 and a capacitor 28 are a peak voltage absorption circuit that protects the bidirectional three-terminal cyclister 14. Also, the capacitor 29 is for peak absorption.

As mentioned above, the present invention has a number of effects as described below, and is extremely effective and can be applied to consumer equipment and industrial equipment.

By using a leakage type tripod transformer, the power supply and the low voltage phase control operation circuit are completely isolated, so there is no risk of electric shock.

Since the bidirectional three-terminal thyristor can be fired at zero cross by utilizing the slight leading phase shift characteristic of the leaky tripod transformer, it has become possible not only to turn on and off but also to control the phase of AC power over a wide range.

The secondary coil of the leakage type tripod transformer uses low voltage as the operating circuit power supply, and a simplified phase control circuit is installed, and an equivalent pulse signal is sent to the tertiary coil by short-circuit opening of the secondary coil and phase-controlled short-circuit opening. Since it is induced and applied as a gate signal, no separate power supply is required.

Since this is a phase control circuit using a leaky tripod transformer with a gap in the third leg, false firing will occur if 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 fear.

Instead of using separate input and output transformers as in the past, a leaky tripod transformer is used, so the transformer can be provided in a small, lightweight, and low-cost manner, and as a result, it naturally reduces the load of AC motors in application circuits. The phase control circuit unit can also be manufactured in a small size, light weight, and low cost.

Since a leaky tripod transformer is used, the price of the transformer is reduced to 3/4 of that of conventional ones, and the space required for installation is 70%, which means that the home appliance industry in Japan can reduce production costs. Considering the scale of production, which is several million units per year, it has a very large economic value.

The switch variable resistor of the control section can be installed at a location separate from the transformer body, making it possible to use it as a so-called remote control switch, which is very convenient.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams showing a conventional AC power phase control circuit, FIG. 3 is a circuit diagram showing an AC power phase control circuit according to an embodiment of the present invention, and FIG. 4 is a circuit diagram showing a conventional AC power phase control circuit. FIG. 5 is a block diagram of a three-legged transformer having a gap in the monopod used, and a voltage waveform diagram of each part for explaining the operation of the above-mentioned embodiment circuit. 1: Tripod transformer, 5: Gap, 6: Primary coil, 7: Secondary coil, 8: Tertiary coil, 11:
Non-magnetic material, 14: Bidirectional three-terminal thyristor, 1
9: Variable resistor, 20: Capacitor, 21: NPN
type transistor, 24: PNP type transistor.

Claims (1)

[Claims] 1. In a leaky tripod transformer in which one leg of the tripod core is an open leg with a gap, a primary coil connected to an AC power source is wound around one non-open leg, and the other non-open leg is wound with a primary coil connected to an AC power supply. An alternating current power phase control circuit configured by winding a secondary coil around an open leg and a tertiary coil around the open leg, and connecting both ends of the primary coil to a load and a bidirectional three terminal. connected to a series connection circuit of thyristors, and connecting both ends of the tertiary coil to a pair of diodes connected in antiparallel to the gate of the bidirectional three-terminal thyristor and a cathode of the bidirectional three-terminal thyristor. Both ends of the secondary coil are connected to a full-wave rectifier circuit, and a series circuit of a resistor, a switch, a variable resistor, and a capacitor, an NPN transistor, and two resistors connected in series are connected between both ends of the secondary coil on the DC side. connected in parallel, the connection point of the two resistors is connected to the base of a PNP type transistor, the collector of the PNP type transistor is connected to the base of the NPN type transistor via a resistor voltage divider circuit, and the
An AC power phase control circuit using a leaky tripod transformer, characterized in that the emitter of the PNP transistor is connected to the connection point of the variable resistor and the capacitor.