JPH0361205B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an AC power phase control circuit having a low voltage control section completely isolated from a power source.

Conventionally, phase control circuits for AC power sources using triaxes and the like were all directly connected to the AC power source, and there was a risk of electric shock when performing phase control operations. 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 supply on the secondary (low voltage) side of a composite tripod transformer, and also provides a Since the bidirectional three-terminal thyristor is controlled by the output signal of the tertiary coil that is electromagnetically coupled to the AC power source, the phase of the AC power source is controlled, so there is absolutely no risk of electric shock when operating the control unit, and this is an extremely new and innovative product. The purpose of this invention is to provide a useful AC power phase control circuit.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

In FIG. 1, reference numeral 1 denotes a composite tripod transformer, the structure of which is as shown in FIG. A primary coil 8 is wound around one of the outer legs 5 and 7 of the composite tripod core and connected to an AC power source 11, and a low voltage secondary coil is connected to the central leg 6. A coil 9 is wound around the other outer leg 7, and a tertiary coil 10 is wound around the other outer leg 7, respectively. An operating switch 12, a series circuit of a bidirectional three-terminal thyristor 13 and a current limiting resistor 14, and a series circuit of a variable resistor 15 and a capacitor 16 are connected to both ends of the secondary coil 9, and a combination of the variable resistor 15 and the capacitor 16 is connected to both ends of the secondary coil 9. A variable firing angle control section A is provided between the point and the gate of the bidirectional three-terminal thyristor 13, in which a trigger element 17 such as an SBS or a diagonal is connected, and one end of the tertiary coil 10 is connected to the power source 11, and the other end is It is connected to the gate of a bidirectional three-terminal thyristor 19 connected in series with the load 18 to the power supply 11 via a pair of anti-parallel connected diodes 20 . In the figure, 12 is an operation switch that short-circuits and opens the secondary coil 9.
Reference numerals 21 and 22 designate thyristor protection circuits that absorb induced voltages caused by firing and extinguishing of the bidirectional three-terminal thyristor 19 and peak voltages from the power supply.

Next, the operation of the present invention will be explained. The low voltage (e.g. 12V) induced in the secondary coil 9 is applied to the variable resistor 15.
When the terminal voltage of the capacitor 16 becomes equal to or higher than the breakover voltage of the trigger element 17, the trigger element 17 exhibits negative resistance, so that the amount of electricity stored in the capacitor 16 becomes bidirectional three-terminal. is released to the gate of thyristor 13 and triggers the bidirectional three-terminal thyristor 13. Changes in the variable resistor 15 cause a delay in the time it takes for the electrical voltage charged in the capacitor 16 to reach the breakover voltage, and the trigger element 17, such as an SBS or diac, generates pulses that are substantially symmetrical in both directions. A directional three-terminal thyristor is triggered in both directions to control its firing angle. Therefore, the secondary coil 9 is repeatedly short-circuited with a constant phase depending on the position of the variable resistor 15 with respect to the input voltage.

Here, to explain the function of the composite tripod transformer 1, as shown in FIG. 2, when the secondary coil 9 is open, the primary magnetic flux φ ₁ generated by the primary coil 8 is A magnetic circuit is formed within the iron core 2, and magnetic flux does not pass through the inner core 3 since it is isolated by a non-magnetic material. Therefore, no electromotive force is generated in the tertiary coil 110 wound around the inner iron core 3. On the other hand, when the secondary coil 9 is short-circuited by turning on the operation switch 12 as described above or by controlling the phase with the variable firing angle control section A shown in FIG. Most of the secondary magnetic flux φ ₂ generated in the opposite direction to the magnetic flux φ ₁ passes through the core 3 having low magnetic resistance, forming a magnetic circuit as shown by the dotted line. As a result, the tertiary coil 10
A voltage is induced which lags behind the voltage applied to the primary coil 8 by about 360 degrees or more, that is, is approximately in phase and slightly ahead of the voltage applied to the primary coil 8. Since the composite tripod transformer 1 has such characteristics, when the secondary coil 9 is short-circuited and opened, a voltage appears in the tertiary coil 10 corresponding to the short-circuit current when the secondary coil 9 is short-circuited.
If this voltage is applied to the gate of the bidirectional three-terminal thyristor 19 through the anti-parallel connected diode 20, the firing angle of the bidirectional three-terminal thyristor 19 can be changed in the same way. Controlled alternating current power is supplied.

Now, if the waveform of the pulse applied to the gate of the bidirectional three-terminal thyristor 13 by the trigger element 17 of the variable firing angle control section A is shown in FIG. As shown in D, no voltage appears in the lit part. Since the lit part short-circuits the secondary coil 9, a voltage as shown in Fig. 3E appears in the tertiary coil, and this is applied to the gate of the bidirectional three-terminal thyristor 19, resulting in the voltage shown in Fig. 3. A phase-controlled current such as
is supplied to Therefore, since the firing angle of the bidirectional three-terminal thyristor 13 can be varied from 0 to 180 degrees by changing the resistance value of the variable resistor 15 in the trigger circuit, the firing angle of the bidirectional three-terminal thyristor 19 can be changed by changing the resistance value of the variable resistor 15 in the trigger circuit. can also be changed in the same way.

The voltage of the tertiary coil is set slightly higher than the firing voltage of the bidirectional three-terminal thyristor 19 to limit the gate current and protect the element from damage. This prevents malfunctions by suppressing minute voltages.

In addition, in the above embodiment, the operation switch 12
By closing this, the secondary coil 9 is always kept in a short-circuited state, and the bidirectional three-terminal thyristor 19 is forced to be fully fired. variable resistance 1
Although it is possible to fully fire the bidirectional three-terminal thyristor 19 by adjusting the resistance value of thyristor 5 to zero, the advantage of providing the operating switch 12 is that this can be achieved instantly. There is.

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, instead of using separate input and output transformers as in the past, a composite tripod transformer is used, so the transformer is small, lightweight, and
It can be provided at low cost, and as a result, phase control circuit units for loads such as AC motors in applied circuits can also be manufactured in a small size, light weight, and low cost.

In addition, by using a composite tripod transformer, the price of the transformer is reduced to 3/4 compared to one that uses a conventional input transformer and output transformer.
The fact that the space required is only 70% is of great value to Japan's home appliance industry, considering the production scale of several million units per year.

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

In addition, the output of the tertiary coil is input to the gate of a bidirectional three-terminal thyristor for load control via a pair of anti-parallel connected diodes, so compared to the case of using a diode bridge circuit, the diode It is economical because the number of parts is small.

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 phase control circuit diagram according to the present invention, FIG. 2 is a schematic front view of a composite tripod transformer used in the present invention, FIG. 3 is a waveform diagram of each part for explaining the operation of the above embodiment circuit. 1: Composite tripod transformer, 2, 3: Iron core, 4: Non-magnetic material, 8: Primary coil, 9: Secondary coil, 10: Tertiary coil, 13: Bidirectional three-terminal thyristor, 15: Variable Resistor, 16: Capacitor, 17: Trigger element, 18: Load, 19: Bidirectional three-terminal thyristor.

Claims (1)

[Claims] 1 A composite tripod core is formed by separately joining one leg of each of two inner iron cores with a non-magnetic material using a non-magnetic material, and a primary coil is wound around one of the outer legs of the composite tripod core. Wind the low-voltage secondary coil around the center leg and the tertiary coil around the other outer legs.
A first bidirectional three-terminal thyristor, an operating switch, and a series circuit of a variable resistor and a capacitor are connected, and a connection point between the variable resistor and the capacitor is connected to the first bidirectional three-terminal thyristor through a trigger element. the gate of a second bidirectional three-terminal thyristor, one end of the tertiary coil being connected to the power supply and the other end connected in series with the load to the power supply through a pair of anti-parallel connected diodes; An alternating current power phase control circuit using a composite tripod transformer, characterized in that it is connected to a composite tripod transformer.