JPS6392258A - Phase control type solid-state relay - Google Patents

Abstract

PURPOSE:To control positions in positive and negative cycles by regulating a control input level applied to a time-limit time-setting circuit by a limiter circuit when the control input level exceeds a given value. CONSTITUTION:A phase control type solid-state relay is composed of a primary side circuit A consisting of a phototransistor PT1, a timer circuit 2, a relay output circuit 3, a time-limit time-setting circuit 5 and others, and a secondary side circuit B consisting of a null voltage detection circuit 6, a relay input circuit 8 and others. In this case, a resistor R11 is connected between a gate signal input terminal 1c and a resistor R3, and a cathode and an anode of Zener diode ZD3 are connected to a junction of said both resistors R3, R11 and to a DC electrode terminal 1b, respectively. Further, the Zener diode ZD3 constitutes a limiter circuit 10. Also, a resistor R12 for stabilizing a charging voltage is connected between both ends of a capacitor C1 of the timer circuit 2 to regulate noise and the like, even if an input level exceeds a given value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a phase-controlled solid-state relay (SSR) used for controlling motor rotation speed and power control of heaters, lamps, etc. in industrial equipment and general consumer equipment.

<Prior art and its problems> A conventional phase-controlled solid-state relay will be described with reference to FIG. 2.

First, the primary side circuit A will be explained.

Between the DC power supply terminals 1a and 15 connected to the DC power supply E,
Phototransistor PT, resistor R3゜capacitor C8
series circuit is connected. Also, in this series circuit,
Current limiting resistor Rz, light emitting diode LED1. A series circuit of transistors Tr is connected in parallel. The resistor R3 and capacitor C+ in the previous series circuit form the timer circuit 2.
It consists of In addition, a resistor Rz, a light emitting diode LE
DI and transistor Tr+ constitute a relay output circuit 3.

A series circuit of a resistor R3+ and a gate-on resistor R4 is connected between the control voltage input terminal IC and the negative DC power supply terminal 1b, and a PUT (
programmable unijunction transistor)
4 gates are connected. The anode of this PUT4 is connected to the connection point between the resistor R1 and the capacitor CI in the timer circuit 2, and the cathode is connected to the negative side DC power supply terminal 1b via the resistor R3. The cathode of PUT4 is connected to the base of transistor Tr1, the gate is connected to the connection point between resistor R3 and gate-on resistor R4, and the gate and anode are connected to the noise prevention capacitor C.
Connected via 2.

Resistors Rs, Rs, Rs, PUT4, etc. constitute a time limit setting circuit 5.

Next, the secondary side circuit B will be explained.

Two light emitting diodes LEDt and LEDz connected in parallel with mutually opposite polarities constitute a zero voltage detection circuit 6 for the secondary side input voltage, and this zero voltage detection circuit 6 is connected to the phototransistor P T of the primary side circuit A. + constitutes a photocoupler PCI. AC power S terminal 7a, T
b, a current limiting resistor Rh.

Zero voltage detection circuit6. Current limiting resistor R? , R1, and a commutation resistor R9 are connected in series. The commutation resistance R is
It controls the turn-on current of the main triac TACI, which will be described later.

The anode of a Zener diode ZDt is connected to the connection point between the current limiting resistor R1 and the zero voltage detection circuit 6, and the cathode of the Zener diode ZD is connected to the cathode thereof.
Is the anode of the Zener diode ZDI the current limiting resistor R? ,
Connected to the connection point of R1+. These two Zener diodes ZDI and zDz are connected to the zero voltage detection circuit 6.
Light-emitting diode LED
! .

It protects the LEDs.

Zener diode ZDz anode and current limiting resistor Rs+
A series circuit of a current limiting resistor R11+ and a phototritic PACI is connected between the connection point of the commutation resistor R9. This phototriac PACI constitutes a phototriac coupler PTC1 together with the light emitting diode LEDI in the primary circuit A.

A capacitor C5 is connected between the connection point of the current limiting resistors Ra and Rho and the AC power supply terminal 7b in order to suppress the rate of increase in input voltage (a'V/Vt) to a constant level.

The T2 terminal of the main triac TAC, which is an example of a bidirectional semiconductor switching element, is the AC power supply terminal 7a.
The T1 terminal is connected to the AC power supply terminal 7b. Main triac TAC, gate terminal G
is connected to the connection point between the commutation resistor R1 and the phototritic PAC.

A resistor R1°, a phototritic PAC, and a commutation resistor R9 constitute a relay input circuit 8.

An AC power supply 9 is connected between the AC power supply terminals 7a and 7b via a power switch S and loads such as motors, lamps, and heaters.
It is connected to the.

Next, the operation of this conventional example will be explained.

■ A control voltage at a certain level is applied in advance to the control voltage input terminal IC to the load drive primary circuit, and the gate-on resistor R
A constant voltage is generated across PUT4, and a gate voltage appears at the gate of PUT4. The voltage level of the control voltage is the main triac TAC.

This corresponds to the conduction phase angle of .

Turn on the power switch S in the secondary circuit B. At this point in time, the phototriac PAct and the main triac TAC are non-conductive.

When the power switch S is turned on, a current from the AC power supply 9 is applied to the resistor R6, the zero voltage detection circuit 6, the resistor Rq,
It flows through the paths Ra and Rq. As the voltage increases during the positive half cycle period of the power supply voltage, the current also increases, and the light emitting diode LEDz starts emitting light when the power supply voltage is around zero voltage. The current at the start of this light emission is the resistance R1+R
? +Rs, a minute current limited by R9. Even if the power supply voltage increases further, the light emitting diode LED
The current flowing through z is limited to below the rated value by the Zener diode ZDI.

On the other hand, when the power switch S is turned on, a current flows through the load, and this load current is passed through the current limiting resistor Ra.

Since Ry and Rs suppress the current to a minute current, only a minute current flows through the commutation resistor R9, and the commutation resistor R
Since the voltage drop at 9 is small, the gate current flowing to the gate terminal G of the main triac TAC is less than the turn-on current. Therefore, the main triac T A
C+ remains non-conducting.

As long as the main triac TAC+ maintains a non-conducting state, the current flowing to the load is limited by the current limiting resistor Rh,
Since it is a minute current limited by R7, Rm and the commutation resistor R9, it does not reach a current (drive current) sufficient to drive the load.

When light from the light emitting diode LEDt enters the phototransistor P T + of the primary side circuit A, this phototransistor P T r becomes conductive, and charging of the capacitor C1 in the timer circuit 2 is started. Capacitor C
The charging time constant for 1 is determined by the resistance value of the resistor R and the capacitance of the capacitor CI.

With the start of charging the capacitor C1, the anode voltage of PUT4 in the time limit setting circuit 5 gradually increases.

When this anode voltage becomes higher than the gate voltage appearing across the gate-on resistor R#, PUT4 becomes conductive. When PUT4 becomes conductive, a voltage is generated across the resistor R3, and a current due to this voltage flows to the base of the transistor Tri in the relay output circuit 3, making the transistor TrI conductive.

When transistor Tr+ conducts, relay output circuit 3 (
The light-emitting diode LED in the photo-trial coupler (PTC+) starts emitting light.

The light enters the phototriac PACI in the relay input circuit 8, and the phototriac PACI
C+ becomes conductive.

When the phototritic P A CI conducts, the resistance R
? , R1 are connected in parallel, and their combined resistance value decreases, so that the current flowing through the commutation resistor R9 increases. Therefore, the voltage across the commutation resistor R9 increases, the current flowing to the gate terminal G of the main triac TACI reaches the turn-on current, and the main triac TACI becomes conductive.

When the main triac T A CI conducts, the zero voltage detection circuit 6. Resistance R? + Zener diode ZD,
, ZDt, the circuit consisting of the resistor RIl is substantially shorted by the main triac T A C+ and the resistor Rj
, R@ is supplied to the load via the main triac TACI. At this time, the capacitor C1 suppresses inrush current from flowing into the main triac TAC+ and the load.

On the other hand, due to the aforementioned substantial short circuit, the photocoupler PC
The light emission of the light emitting diode LEDt in , is also substantially stopped, and the phototransistor PT in the primary side circuit A becomes non-conductive. Along with this, rapid discharge of the charge in the capacitor CI in the timer circuit 2 is started via the PUT4 and the resistor R3. Then, when the voltage between the anode and the cathode of PUT4 becomes equal to or lower than the ON voltage of PUT4 due to the voltage drop of the capacitor CI, PUT4 returns to the non-conductive state. Note that the return of PUT4 to the non-conductive state is performed until the end of the positive half cycle period, and the discharge of the charge in capacitor C3 is completed until this return.

As described above, a drive current is supplied to the load by the conduction of the main triac TAC, but when the power supply voltage reaches near zero voltage and becomes less than the holding voltage of the main triac TAC, the main triac TAC is turned off. This stops the supply of drive current to the load. That is, the power supply to the load is always stopped near zero voltage.

Further, by turning off the main triac TAC, the short circuit state of the zero voltage detection circuit 6 and the like is released.

During the negative half cycle period of the power supply voltage, the light emitting diode LED3 replaces the light emitting diode L E D z.
emits light, and the light emitting diode LED
Zener diode ZD limits the current flowing through s.
The operation is similar to that in the positive half-cycle period except that it is 2.

■ When the level of the control voltage applied to the phase control control voltage input terminal IC is increased, the gate voltage of PUT4 also increases, and the timer circuit 2
It takes a long time for the charging voltage of the capacitor C8 to rise from the start of charging to the voltage that makes PUT4 conductive. Therefore, the conduction timing of PUT4 is delayed, the conduction angle of the main triac T A C+ becomes small, and the power supplied to the load is reduced.

Conversely, when the control voltage applied to the control voltage input terminal IC is lowered, the gate voltage of PUT4 is also lowered, and the charging voltage of capacitor C2 in timer circuit 2 is lower than P from the start of charging.
The time required for the voltage to rise to the point where the UT4 becomes conductive is shortened. Therefore, the conduction timing of PUT4 becomes earlier,
The conduction angle of the main triac T A Cl increases, and the power supplied to the load increases.

According to the conventional phase-controlled solid-state relay described above, in order to detect +11 zero voltage, the light emitting diodes LEDz, LE constituting the photocoupler Pct are
D3 is used, (2) zero voltage is connected to secondary circuit B
In order to transmit the data from
(2) A timer circuit 2 and a time limit setting circuit 5 consisting of a PUT 4 and the like are used to define the conduction angle of the main triac TAc as a bidirectional semiconductor switching element. Therefore, there are advantages in that cost reduction, simplification of circuit configuration, weight reduction, and space saving can be achieved.

However, the conventional example having such a configuration has the following problems.

The higher the level of the control voltage applied to the control voltage input terminal 1c, the smaller the conduction angle of the main triac TAC. That is, this is because the timing at which PUT4 becomes conductive is delayed.

Therefore, if the level of the control voltage exceeds a certain value due to noise or the like, there is a possibility that the conduction timing of PUT 4 will be delayed to the next half cycle.

For example, when considering the positive half cycle in which the light emitting diode LEDt emits light, the conduction timing of PUT4 and thus the main triac TACI falls into the next negative half cycle.

When the main triac TAC+ becomes conductive, the light emitting diode LED3 is prohibited from emitting light, while the rapid discharge of the capacitor C1 of the timer circuit 2 is completed immediately after the main triac TAC+ becomes conductive. C1 is not charged. Therefore, in the next positive half cycle, conduction of PtJT4 and thus the main triac TACI does not occur. the result,
Power is supplied to the load only during the negative half cycle.

Conversely, if charging of the capacitor C3, which causes the phototriac PAC to conduct, is started in the negative half cycle, power supply to the load is limited to the positive half cycle.

In any case, if the control voltage is too high, power will only be supplied for half a cycle.

In such a case, if the load is on the motor, the rotation of the motor will be unregulated and a decrease in torque will be unavoidable.

<Object of the Invention> The present invention has been made in view of the above circumstances, and even if an abnormally high control voltage is unexpectedly applied,
The purpose is to enable phase control in both positive and negative cycles.

<Structure and Effects of the Invention> [Structure] In order to achieve the above object, the present invention has the following structure.

That is, the phase control type solid state relay of the present invention has the following characteristics: AC2i! A bidirectional semiconductor switching element connected between power supply terminals, a relay input circuit that conducts the semiconductor switching element, and a light emitting element that starts emitting light near zero voltage of an AC power supply voltage connected to the AC power supply terminal. a secondary side circuit having a secondary side circuit, a light-receiving element that forms a photocoupler together with the light-emitting element, a timer circuit that is operated by conduction of the light-receiving element, and a timer circuit that sets the time limit of the timer circuit by adjusting a control input. A phase control type comprising a primary side circuit having a time limit setting circuit that outputs an output when the time limit is completed, and a relay output circuit that operates based on the output of the time limit setting circuit and drives a relay input circuit of the secondary circuit. The solid state relay includes a limiter circuit that regulates the level of the control input to a predetermined value or less so that the time limit of the timer circuit corresponding to the level of the control input is limited to less than half a cycle of the AC power supply. It is.

[Effect]

The effects of this configuration are as follows.

That is, when the level of the control input exceeds a predetermined value due to noise or the like, the limiter circuit regulates the level of the control input applied to the time limit setting circuit to be below the predetermined value. The time limit of the timer circuit is shorter than half a cycle of the AC power supply. Therefore, whether the timing operation of the timer circuit that causes the semiconductor switching element to conduct is started in the positive half cycle or in the negative half cycle, in either case, the semiconductor switching element The switching element becomes conductive.

〔effect〕

From the above, according to the present invention, the following effects are achieved. In other words, even if the level of the control input exceeds a predetermined value due to noise or the like, phase control should be performed on both positive and negative cycles in order to make the time limit of the timer circuit shorter than a half cycle of the AC power supply. Can be done.

<Description of Examples> Examples of the present invention will be described in detail below based on the drawings.

FIG. 1 is a circuit diagram of a phase-controlled solid state relay according to an embodiment of the present invention.

In FIG. 1, the same reference numerals as the conventional example shown in FIG.
Regarding connection relationships, this embodiment and the conventional example have similar configurations.

The configuration of this embodiment differs from the conventional example as follows.

A resistor R11 is connected between the gate signal input terminal IC and the resistor R1.
The cathode of a Zener diode ZDff is connected to the connection point between these two resistors Ri and R, and the anode thereof is connected to the negative DC power supply terminal 1b. In the case of this embodiment, this Zener diode ZD constitutes the limiter circuit 10 referred to in the configuration of the invention.

Note that a resistor R1□ is connected between both ends of the capacitor c1 in the timer circuit 2 to stabilize the charging voltage of the capacitor C1.

Although the noise prevention capacitor C2 is not shown, it may be connected as in the conventional example or may be omitted.

The rest of the configuration is the same as the conventional example, so the explanation will be omitted.

The operation of this embodiment will be explained below.

When the limiting voltage applied to the gate signal input terminal 1c exceeds a predetermined value due to superimposition of noise or the like, the Zener diode ZD3 becomes conductive and maintains the voltage across it at the predetermined value (constant value). Therefore, resistance R1 and resistance R
1 and the gate voltage appearing across the resistor R4 is also held constant. The gate voltage at this time is
It is related to the charging time constant of the timer circuit 2, which is determined by the resistance value of the resistor R1 and the capacitance of the capacitor CI. That is,
PUT4 anode voltage (capacitor C+ charging voltage)
The relationship is such that the time required for the charging voltage of the capacitor C1 to rise until it exceeds the gate voltage is shorter than a half cycle of the AC power supply 9.

Therefore, in the positive half cycle, the light emitting diode LE
The timing at which PUT4 becomes conductive due to the light emission of D* is limited to the period of the positive half cycle that caused the light emission, and does not shift to the next negative half cycle. Furthermore, the timing at which PUT4 becomes conductive due to the light emitting diodes LEDs emitting light during a negative half cycle is limited to the period of the negative half cycle that caused this, and is delayed to the next positive half cycle. Never.

Therefore, predetermined phase control is performed satisfactorily in both the positive half cycle and the negative half cycle.

Note that the limiter circuit 10 is a Zener diode Z.
In addition to D x, any element may be used as long as it has the same function.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a phase-controlled solid state relay according to an embodiment of the present invention. Moreover, FIG. 2 is a circuit diagram of a phase control type solid state relay according to a conventional example. A...Primary side circuit B...Secondary side circuit 2...Timer circuit 3...Relay output circuit 5...Time limit setting circuits 7a, 7b...AC power supply terminal 8... Relay input circuit 10...Limiter circuit TAC,...Main try book (bidirectional semiconductor switching element) PC+...
Photo coupler

Claims (1)

[Claims] (1) A bidirectional semiconductor switching element connected between AC power terminals, a relay input circuit that conducts this semiconductor switching element, and light emission starting near zero voltage of the AC power supply voltage connected to the AC power terminal. a secondary side circuit having a light-emitting element that functions as a photocoupler; a light-receiving element that forms a photocoupler together with the light-emitting element; a timer circuit that operates by conduction of the light-receiving element; and a timer circuit that sets the time limit of the timer circuit by adjusting a control input. and a primary side circuit having a time limit setting circuit that outputs an output upon completion of the time limit of the timer circuit, and a relay output circuit that operates based on the output of the time limit setting circuit and drives a relay input circuit of the secondary circuit. In the phase-controlled solid state relay, a limiter circuit regulates the level of the control input to a predetermined value or less so that the time limit of the timer circuit corresponding to the level of the control input is limited to less than half a cycle of the AC power supply. Phase controlled solid state relay with