JPH0773199B2 - Load control circuit device - Google Patents

Description

The present invention relates to a load control circuit device that uses a tripod transformer to control a load without contact.

(B) Conventional Technology The inventor of this application has developed a non-contact control circuit using a tripod transformer to control the load of a motor or the like on / off, and has already filed various applications. The basic configuration of this contactless control circuit includes an AC power supply, a load driven by this AC power supply, a primary coil, a secondary coil and a tertiary coil, and
From a tripod transformer in which an AC power source is connected to the secondary coil, and a bidirectional three-terminal thyristor such as a triac that is connected to the tertiary coil and turns on / off a load in response to a short circuit / open of the secondary coil. It will be. In this contactless control circuit, the secondary coil is short-circuited by the ON operation of the switching element of the control circuit connected to the secondary coil.
A voltage is induced in the next coil to turn on the bidirectional three-terminal thyristor and turn on the load.

(C) Problems to be solved by the invention In the contactless control circuit using the tripod transformer, when an operation input is input and the secondary coil is short-circuited to turn on the load, the operation input is applied to the secondary coil. Since it is short-circuited for the entire period, it cannot be used as an electronic control power source due to the secondary voltage drop, and there is a problem that wasteful power is consumed.

In view of the above, the present invention makes the short-circuit period of the secondary coil of the tripod transformer as short as possible, even if an operation input is applied,
An object of the present invention is to provide a load control circuit device that consumes relatively little power.

(D) Means for Solving the Problems In the load control circuit device of the present invention, one leg of the three-legged iron core is an open leg with a gap, and the first non-aperture leg is connected to an AC power source. A leaky three-leg transformer in which the primary coil (2) is wound, the secondary coil (3) is wound around the second non-open leg, and the tertiary coil (4) is wound around the open leg. (1) is connected to both ends of the primary coil (2),
A series circuit of a load (6) and a bidirectional three-terminal thyristor (7); and a control circuit connected to the secondary coil (3) and generating an induced voltage in the tertiary coil (4) by an ON operation.
From a trigger circuit (d ₁ , d ₂ ) connected to the tertiary coil (4) and triggering the bidirectional three-terminal thyristor (7) in response to an induced voltage in the tertiary coil (4) In the above, the control circuit is connected to a full-wave rectification circuit (9) connected to both ends of the secondary coil (3) and an output side of the full-wave rectification circuit (9), and at the time of ON operation, A smoothing circuit (10) for receiving the outputs of a switching circuit (R ₂ , Tr) that short-circuits the secondary coil (3) with a predetermined resistance value and the full-wave rectification circuit (9) and smoothing the same.
And a comparison voltage generation circuit (R ₃ , R ₄ ) that outputs a comparison voltage (Vc) according to the change in the waveform of the output of the full-wave rectification circuit (9)
And a reference voltage generation circuit (R ₅ , R ₆ ) that generates a reference voltage (Vs) corresponding to the DC output voltage of the smoothing circuit (10), and the comparison voltage (Vc) and reference voltage (Vs) In the case where an operation input is applied, a comparator (11) that outputs in a predetermined short time near the zero crossing point where the reference voltage (Vs) becomes larger than the comparison voltage (Vc) is received. , The output of this comparator (11) is the switching circuit (R ₂ ,
And a gate circuit (12) for turning on the switching circuit (R ₂ , Tr) for a predetermined short time.

(E) Action In this load control circuit device, when an AC signal is applied from the AC current to the primary coil of the tripod transformer, the signal is changed to 2
Derived to the next coil side, full-wave rectified by a full-wave rectifier circuit,
Further, the full-wave rectified output is smoothed by the smoothing circuit. Then, the voltage (comparison voltage) corresponding to the full-wave rectified output is output from the comparator
And the voltage (reference voltage) corresponding to the DC output of the smoothing circuit are compared, and the comparator outputs the output only for a predetermined short time near the zero crossing point where the reference voltage becomes larger. That is, the pulse signal is output in synchronization with the zero-point crossing point.

If the operation input is not applied, the switching circuit will not turn on. However, if the operation input is applied, the switching circuit will be turned on every half cycle of the AC power supply, and a current of a predetermined value or more will flow to the secondary coil. In response, the trigger circuit operates to turn on the bidirectional three-terminal thyristor and drive the load.

(F) Examples Hereinafter, the present invention will be described in more detail with reference to Examples.

FIG. 1 is a circuit connection diagram of a well pump control device showing an embodiment of the present invention. In the figure, a tripod transformer 1
Is composed of a primary coil 2, a secondary coil 3 and a tertiary coil 4, and an AC voltage of 100V is applied from an AC power source 5 to both ends of the primary coil 2.

A well pump motor 6 as a load and a triac (bidirectional three-terminal thyristor) 7 are connected in series, and this series circuit is connected in parallel to an AC power supply 5 and a primary coil 2. Further, one end of the tertiary coil 4 is connected to the terminal T _{1 of the} triac 7, and the other end of the tertiary coil 4 is connected through the diodes (trigger circuits) d ₁ and d ₂ of antiparallel connection,
It is connected to the gate terminal G of the triac 7.

Also, a parallel circuit of the surge absorber 8 and the capacitor C ₁ is connected in parallel to the primary coil 2 for absorbing overvoltage,
Similarly, a resistor R ₁ and a capacitor are used to absorb the overvoltage.
A series circuit of C ₂ is connected in parallel to the triac 7.

A capacitor C ₃ is connected to the secondary coil 3, and
A point A and a point B of a bridge circuit (full-wave rectification circuit) 9 composed of diodes d ₃ , d ₄ , d ₅ , and d ₆ are connected. The point C of the bridge circuit 9 is connected to the stabilizing and smoothing circuit 10, and the point D is connected to the ground GND. Further, a series circuit of a resistor R ₂ and a switching transistor Tr is connected in parallel at points C and D of the bridge circuit 9.

Also, C point of the bridge circuit 9, the D point, the series circuit of the resistors R _3, R ₄ are connected, from the connection point of the resistors R ₃ and R _4, depending on the rectified signal level outputted from the fridge circuit 9 Voltage (comparative voltage) Vc is obtained. The resistor R ₄ is a variable resistor so that the level of the voltage Vc (and the rate of change near 0 volt) can be adjusted.

The series circuit of the resistors R ₃ and R ₄ is connected to the stabilization smoothing circuit 10, and the voltage smoothed by this circuit 10 is obtained across the smoothing capacitor C ₄ . This smoothing capacitor C ₄
A series circuit of resistors R ₅ and R ₆ is connected to both ends of
The connecting point of R _5, R _6, a reference voltage Vs for zero crossing point detection
Is obtained. The reference voltage Vs is a value obtained by dividing the voltage across the smoothing capacitor C ₄ by the resistors R ₅ and R _6, and is set to a predetermined value near zero volt. This reference voltage Vs is
The voltage Vc is applied to the + input terminal of the comparator 11 and to the − input terminal thereof.
The high signal is output only when the reference voltage Vs is higher than the comparison voltage Vc. These resistors R ₃ , R ₄ ,
R ₅ , R ₆ and the comparator 11 constitute a zero crossing point detection circuit and a pulse signal generation circuit.

The output terminal of the comparator 11 is connected to one input terminal of the AND circuit 12, and the signal from the pressure switch (operation switch) 13 is applied to the other input terminal of the AND circuit 12. Therefore, when the pressure switch 13 is off, the output of the AND circuit 12 is at low level.

The output terminal of the AND circuit 12 is connected to the base of the transistor Tr. If the output of the AND circuit 12 is a roll bell, the transistor Tr is in the off state. Conversely, if the output of the AND circuit 12 is at the high level, it is in the on state. is there.

By the way, in this well pump control device, the tripod transformer 1 is a leaky tripod transformer, so the operation of the leaky tripod transformer will be described with reference to the principle of operation of FIG.
However, the leaky tripod transformer itself is already known.

In FIG. 3, when the primary coil 22 is connected to the AC power supply 25 and energized, the primary magnetic flux φ ₁ generated by the primary coil 22 is generated when the switches SW at both ends of the secondary coil 23 are opened. , As shown by the solid line, most of it flows as a magnetic flux φ ₁ ′ into the central leg 32 and interlinks with the secondary coil 23, and a voltage deviated from the phase of the AC power supply 25 by about 180 ° is induced in the secondary coil 23. .
At this time, since the opening leg 33 having the gap G has high magnetic resistance, only a very small amount of leakage magnetic flux φ ₁ ″ can pass therethrough, and therefore,
The magnetic flux interlinking with the tertiary coil 24 is also small, and the tertiary coil
Very little voltage is induced in 24.

On the other hand, when the switches SW at both ends of the secondary coil 23 are closed, a short-circuit current flows through the secondary coil 23, and the secondary magnetic flux φ _{2 having a} phase almost opposite to that of the primary magnetic flux φ ₁ ′. Is generated in the center push 32, and the magnetic flux φ ₂ ′ is on the first leg 31 around which the primary coil 22 is wound and the magnetic flux φ is on the opening leg 33 as shown by the dotted line in FIG.
Divide as ₂ ″.

When the short circuit magnetic flux φ ₂ ′ of the secondary coil 23 flows through the first leg 31,
The input to the primary coil 22 connected to the power supply 25 is increased to 1
The secondary magnetic flux φ ₁ increases, and therefore the magnetic flux φ ₁ ″ flowing through the opening leg 33 also increases. In this way, the shorting magnetic flux φ ₂ ″ of the secondary coil 23 and the primary magnetic flux φ ₁ ″ are included in the opening leg 33. Since a large amount of synthetic magnetic flux flows and interlinks with the tertiary coil 24, an output delayed by a slight phase of 360 ° (in other words, slightly advanced in phase) from the waveform of the AC power supply 25 is induced in the tertiary coil 24. To be done.

Since the leaky three-leg transformer has the above-mentioned characteristics, if both ends of the secondary coil 23 are ON / OFF controlled by the switch SW, the phase of the tertiary coil 24 will be slightly in phase with the AC power supply 25 in synchronization with this. The advanced AC voltage will be induced.

Next, the operation of the embodiment apparatus using the leaky tripod transformer 1 will be described.

When an AC voltage e [see waveform e in FIG. 2 (c)] is applied to the primary coil 2 of the tripod transformer 1 from the AC power supply 5,
Accordingly, an AC voltage is also obtained on the secondary coil 3 side. This AC voltage is rectified by the bridge circuit 9 and further smoothed by the stabilizing and smoothing circuit 10, and the voltage across the smoothing capacitor C ₄ is supplied as a power supply voltage for each part of another electronic circuit (not shown).

Since the signal derived between the CDs of the bridge circuit 9 is full-wave rectified, the comparison voltage Vc at the connection point of the resistors R ₃ and R ₄ is
Also has the same waveform [see Vc in FIG. 2 (a)].

On the other hand, the output of the stabilization smoothing circuit 10 is compared by the comparator 11 with the reference voltage Vs divided by the resistors R ₅ and R ₆ and the full-wave rectified voltage Vc, and the comparator 11 outputs the high level signal only during the period of Vs> Vc. [See V _{0 in} FIG. 2 (b)] is output. Vs> Vc is near the zero crossing point of the AC signal e, and the comparator
The output of 11 means the zero crossing point detection output, and
It corresponds to a pulse signal synchronized with the zero crossing point. The pulse signal synchronized with the zero crossing point of the comparator 11 is input to the AND circuit 12, but when there is no operation input, that is, when the pressure switch 13 is not turned on, the AND circuit 12
Since the other input end of the transistor 11 is low level, the output pulse signal of the comparator 11 is not input to the transistor Tr, and the transistor Tr remains off.

However, when the pressure switch 13 is turned on, the AND circuit 12
Since the other input terminal of becomes high level, the comparator
The output pulse signal of 11 is input to the base of the transistor Tr via the AND circuit 12, and the transistor Tr is turned on. Then, both ends of the secondary coil 3 are short-circuited by the resistor R ₂ , and a short-circuit current flows. Even in this state, the value of the reference voltage Vs is maintained at a predetermined value by the action of the smoothing capacitor C ₄ .

At both ends of the resistor R ₃ resistor R _4, since the applied voltage across the resistor R ₂ is, increase the supply voltage from zero volts, or with decreasing to, rectified comparison voltage Vc also given increased After the period T, the state returns to the state of Vc> Vs. Then, the outputs of the comparator 11 and the AND circuit 12 become low level, and the transistor Tr returns to the off state. That is, in this circuit, the transistor Tr is turned on only during the period T in which the condition of Vc <Vs is satisfied, and the both ends of the secondary coil 3 are short-circuited by the resistor R ₂ . If the value of the variable resistor R ₄ is changed,
Since the change of the comparison voltage Vc near 0 volt can be made steep, the period T can be set to an appropriate short time.

As described above, the induced voltage is obtained in the tertiary coil 4 by the short-circuit current flowing in the secondary coil 3 during the period T described above (see V _{T in} FIG. 2C), and this voltage is an antiparallel diode.
It is added to the gate G of the triac 7 via d ₁ and d ₂ . This voltage is higher than the trigger gate voltage of the triac 7, the triac 7 is ignited (triggered), the motor 6 is turned on, and the operation is started. As described above, after the triac 7 is ignited, the transistor Tr returns to the off state, and the induced voltage in the tertiary coil 4 becomes small, but the turn-off time of the triac is usually a very short time of about 10 μSec or less. Therefore, there is no problem, and the triac 7, which is once ignited, maintains the ON state for a half cycle of the AC signal.
After half a cycle, the triac 7 is re-ignited by the same operation as described above, so that the operation of the motor 6 is continued.

That is, according to this circuit, in the state where the pressure switch 13 is turned on, the pressure switch 13 is turned on at the zero crossing point of the power supply AC signal to maintain the on state of the triac.

Incidentally. In the above embodiment, the circuit composed of the resistor and the comparator is used for the detection of the zero crossing point and the generation of the pulse signal, but the present invention is not limited to this circuit, and other zero crossing point detection circuits and pulses are used. A signal generation circuit may be used.

Further, in the above embodiment, the well pump motor is shown as the load and the pressure switch is shown as the operation input. However, the present invention is not limited to these, and various loads can be controlled according to various control inputs. It can be widely applied as a non-contact control circuit.

(G) Effect of the Invention According to the present invention, the load is controlled by short-circuiting the secondary coil with one pulse signal in a half cycle generated in synchronization with the zero crossing point of the AC signal. Since the power consumption due to the short-circuit current on the secondary coil side is small and the AC voltage derived to the secondary coil is rectified and stabilized and used as a power supply for an electronic circuit, the short-circuit period is short, There is almost no drop due to a short circuit, and a relatively high voltage DC power supply can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit connection diagram of a well pump control device showing an embodiment of the present invention, FIG. 2 is a waveform diagram of each part of the circuit for explaining the operation of the device, and FIG. It is drawing explaining the operation principle of a leg transformer. 1: Tripod transformer, 3: Primary coil, 3: Secondary coil, 4: Tertiary coil, 5: AC power supply, 6: Pump motor, 7: Triac, 9: Bridge circuit, 10: Stabilization smoothing circuit, 11 : Comparator, Tr: Transistor.

Claims (1)

[Claims] 1. One of the three-legged iron core is an open leg with a gap, and a first non-open leg is connected to an AC power source.
A leaky tripod transformer (2) in which a secondary coil (2) is wound, a secondary coil (3) is wound around the second non-open leg, and a tertiary coil (4) is wound around the open leg. 1), a series circuit of a load (6) and a bidirectional three-terminal thyristor (7) connected to both ends of the primary coil (2), and a secondary circuit (3) connected to the secondary coil (3). A control circuit for generating an induced voltage in the tertiary coil (4), and the bidirectional three-terminal thyristor connected to the tertiary coil (4) and responsive to the induced voltage in the tertiary coil (4). In a load control circuit device comprising a trigger circuit (d ₁ , d ₂ ) for triggering (7), the control circuit includes a full-wave rectification circuit (9) connected to both ends of the secondary coil (3). Connected to the output side of this full-wave rectifier circuit (9), the secondary coil (3) is A switching circuit for short-circuiting at a constant resistance value (R _2, Tr), receiving the output of the full-wave rectifier circuit (9), a smoothing circuit for smoothing this with (10), said full-wave rectifier circuit (9) comparison voltage generating circuit for outputting a voltage comparator in accordance with the waveform change in the output (Vc) and (R _3, R _4), for generating a reference voltage (Vs) corresponding to the DC output voltage of said smoothing circuit (10) The reference voltage generator (R ₅ , R ₆ ) and the reference voltage (Vc) and the reference voltage (Vs) are received at the inputs and compared, and the reference voltage (Vs) becomes larger than the reference voltage (Vc). A comparator (11) that outputs an output in a predetermined short time near the crossing point, and when an operation input is applied, the output of this comparator (11) is transmitted to the switching circuit (R ₂ , Tr) and The switching circuit (R ₂ ,
A load control circuit device comprising: a gate circuit (12) for turning on a Tr.