JPS6392259A - Phase control type solid-state relay - Google Patents

Abstract

PURPOSE:To improve operability of an apparatus by activating a time-limit time-setting circuit through a control input detection circuit when a 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 pbototransistor 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 series circuit of voltage divider resistor R11, R12 is provided between a gate input terminal 1c and a DC power terminal 1b, the base of transistor Tr2 is connected to a voltage divider junction of said series circuit and the collector of said transistor Tr2 is connected to the cathode of PUT4 and to the base of transistor Tr1 of the relay output circuit 3. A control input detection circuit 10 constituted in said manner drives always the relay output circuit 3 when a control voltage of said input terminal 1c is less than a given value, and activates the time-limit timesetting circuit 5 if said control voltage exceeds said 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 type # terminals 1a and 15 connected to the DC power supply E,
A series circuit of a phototransistor P Tl and a tK anti-R1° capacitor C1 is connected. Furthermore, a series circuit including a current limiting grinder R22, a light emitting diode LED+, and a transistor Tr is connected in parallel to this series circuit. The resistor R and capacitor C9 in the above series circuit constitute a timer circuit 2. In addition, the resistor R22 light emitting diode LED+ and the transistor Tr+ are connected to the relay output circuit 3.
It consists of

A series circuit of a resistor R1 and a gate-on resistor R# is connected between the control voltage input terminal IC and the negative DC power supply terminal 1b, and these resistors R, , R.

The gate of a PUT (programmable unijunction transistor) 4 is connected to the connection point. 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 electrode side DC power supply terminal 1b via the resistor R3. The cathode of PUT4 is connected to the base of transistor Tr+, and the gate is connected to resistor R1 and gate-on resistor R.
4, and its gate and anode are connected via a noise prevention capacitor C8.

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

Next, the secondary side circuit will be explained.

Two light emitting diodes LEDz and LEDs 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, together with the phototransistor PT+ of the primary side circuit A, It constitutes a photocoupler PCI. AC power supply terminal 7a, ? Between b, current limiting resistor R6° zero voltage detection circuit 6. Current limiting resistor R?
, Rs, and a commutation resistor R9 are connected in series. The commutation resistance R, is the main triac T described later.
This controls the turn-on current of AC+.

The anode of a Zener diode ZDt is connected to the connection point between the current limiting resistor R6 and the zero voltage detection circuit 6, and the cathode of the Zener diode ZD is connected to the cathode thereof.
The anode of the Zener diode ZDI is the current limiting resistor Ry,
It is connected to the connection point of Rs. These two Zener diodes ZDI and ZDt suppress the current flowing through the zero voltage detection circuit 6 below the rated value, and
.

It protects the LEDs.

Zener diode ZD2 anode and current limiting resistor Rs,
A series circuit of a current limiting resistor R1° and a phototritic PAC is connected between the connection point of the commutation resistor R9. This phototriac PAct is the primary side circuit A
Together with the light emitting diode L ED + , it constitutes a phototriac coupler PTC.

Current limiting resistors Rh, R+. A capacitor C1 is connected between the connection point and the AC power supply terminal 7b for suppressing the rate of increase in input voltage (dVldt) to a constant level.

The T2 terminal of the main triac TA C1 as an example of a bidirectional semiconductor switching element is the AC i source terminal 7.
a, and its T terminal is connected to the AC i source terminal 7b. The gate terminal G of the main trie 7 link TAC is connected to the connection point between the commutation resistor R9 and the phototritic PAC.

A resistor R+e+, a phototriac PACI, and a commutation resistor R 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 1c of the load drive primary side circuit A, 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 corresponds to the conduction phase angle of the main triac TACI.

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

When the power switch S is turned on, a current from the AC power supply 9 is applied to the resistor Rh, the zero voltage detection circuit 6, and the resistor Rt.
, Rs and R9. 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 Rh
, Ry, Rs, and a minute current limited by R9. Even if the power supply voltage increases further, the light emitting diode L
The current flowing through E D is the Zener diode ZD
, is limited below the rated value.

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 Rh.

R? , R1 suppresses the current to a minute current, so 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 CI remains non-conducting.

As long as the main triac TACI maintains a non-conducting state, the current flowing to the load will flow through the current limiting resistors Rh and R.
7. Since Rs is a minute current limited by the commutation resistor R9, it does not reach a current (drive current) sufficient to drive the load.

When light from the light emitting diode LED□ enters the phototransistor P T + to the primary circuit, this phototransistor P T + becomes conductive, and charging of the capacitor C2 in the timer circuit 2 is started. Capacitor C1
The charging time constant for the voltage is determined by the resistance value of the resistor RI and the capacitance of the capacitor CI.

As charging of capacitor C+ starts, the anode voltage of PUT 4 in time limit setting circuit 5 gradually increases.

When this anode voltage becomes higher than the gate voltage appearing across the gate-on resistor R4, PUT4 becomes conductive. When PUT4 becomes conductive, a voltage is generated between both ends of resistor R2, a current due to this voltage flows to the base of transistor 7r in relay output circuit 3, and transistor Tr+ becomes conductive.

When transistor Tr+ becomes conductive, relay output circuit 3
The light emitting diode LED in the (phototriac coupler PTC+) starts emitting light.

The light enters the phototriac P A C+ in the relay input circuit 8, and this phototriac P
AC, conducts.

When the phototriac PACI conducts, the resistance R? ,
Since the resistor R2° is connected in parallel to R1 and their combined resistance value decreases, the current flowing through the commutation resistor R1 increases. Therefore, the voltage across the commutation resistor R7 increases, and the current flowing to the gate terminal G of the main triac TACI reaches the turn-on current, causing the main triac TAC.

conducts.

When the main triac TAC becomes conductive, the zero voltage detection circuit 6. Resistor Rff+ Zener diode ZD,,
ZD2, a circuit consisting of resistor R6 is effectively shorted by the main triac TACI, and resistor R? , R1 is the main triac TAC.

is supplied to the load via. 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 7 is also substantially stopped, and the phototransistor PT in the primary side circuit A
I becomes non-conductive. Along with this, rapid discharge of the charge in the capacitor C1 in the timer circuit 2 is started via the PUT4 and the resistor R1. Then, when the voltage between the anode and cathode of PUT4 becomes lower than the ON voltage of PUT4 due to the voltage drop of capacitor C1, PUT
4 returns to the non-conducting 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 the capacitor C1 is completed until this return.

As described above, a drive current is supplied to the load by the conduction of the main triac TACI, but when the mz voltage reaches near zero voltage and becomes lower than the holding voltage of the main triac 77 TACl, 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 L E D 3 replaces the light emitting diode LED O.
The operation is similar to that in the positive half cycle period, except that the LED emits light and the Zener diode ZD limits the current flowing to the light emitting diode LED3.

■ 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 C1 to rise to the voltage that makes PUT4 conductive from the start of charging. Therefore, the conduction timing of PUT4 is delayed, the conduction angle of the main triac TAC 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 C+ 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 TAC+ increases, and the power supplied to the load increases.

According to the conventional phase-controlled solid-state relay described above, (11) in order to detect zero voltage, the light emitting diodes LED, , LED constituting the photocoupler PC1
(2) A photocoupler Pct is used to transmit zero voltage from the secondary circuit B to the primary circuit A, and (2) the photocoupler Pct is used as a bidirectional semiconductor switching element. Since the timer circuit 2 and the time limit setting circuit 5 consisting of PUT 4, etc. are used to define the conduction angle of the main triac TAC+, costs can be reduced, the circuit configuration simplified, the weight reduced, and This has the advantage of saving space.

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

(a) In a general operation mode, the power supplied to the load as the control voltage shifts follows the control voltage shift smoothly.

However, in contrast to this, in the case of the conventional example, when the control voltage is shifted from a low state to a high state, a large amount of power is suddenly applied to the load from a state where the power supply is zero, and the work is interrupted. People are confused, in short,
It's not easy to use.

In particular, when the load is a motor, there is a problem in that it suddenly starts rotating at the maximum speed.

(b) When the control voltage applied to the control voltage input terminal IC falls below a certain value and the gate voltage of PUT4 becomes below a certain value, PUT4 falls into an inactive state even if the anode voltage rises to a predetermined value. Therefore, the transistor "l'r+" is fixed in a non-conducting state, and the main triac TACI
As a result, even though a certain level of control voltage is applied to the control voltage input terminal 1c, no drive power is supplied to the load.

To prevent this, it is necessary to add a low limiter that limits the control voltage from falling below a certain level, which increases costs.

(c) Even if phase control is not necessary, a gate signal must be applied to the gate signal input terminal 1c because the main triac TAC+ must be conductive in order to drive the load. In addition to being inconvenient to use, the main triac TAC becomes conductive when it slightly exceeds the zero phase of the AC power supply 9, making it impossible to supply power at full phase.

That is, it lacks versatility.

<Object of the Invention> The present invention has been made in view of the above circumstances, and aims to smoothly shift the power supply that follows the shift of the control input in accordance with the shift of the control human power, as in a general operation form. It is an object of the present invention to make it possible to drive a load even when the control input is sufficiently low, to omit a low limiter, and to enable power supply in full phase.

<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-controlled solid-state relay of the present invention includes: a bidirectional semiconductor switching element connected between the AC is terminals, a relay input circuit that conducts the semiconductor switching element, and a relay input circuit connected to the AC power terminal. A secondary side circuit having a light emitting element that starts emitting light near zero voltage of the AC power supply voltage, 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 control input circuit. A time limit setting circuit that sets the time limit of the timer circuit by adjustment and outputs an output when the time limit completes the time limit, and a relay output circuit that operates based on the output of the time limit setting circuit and drives the relay input circuit of the secondary side circuit. In the phase control type solid state relay, the level of the control input is detected, and when the detection level is below a predetermined value, the relay output circuit is constantly driven, and the detection level is The control input detection circuit includes a control input detection circuit that activates the time limit setting circuit when the predetermined value is exceeded.

[Effect]

The effects of this configuration are as follows.

That is, when the level of the control input exceeds a predetermined value, the control input detection circuit activates the time limit setting circuit, so that the same phase control as in the conventional example is performed. That is, when the AC power supply voltage becomes near zero voltage, the light emitting element of the secondary side circuit starts emitting light, and the light receiving element of the primary side circuit that receives the light becomes conductive. Due to this conduction, the timer circuit starts a time limit operation, and when the time limit set by the time limit setting circuit is reached, a signal is output from the time limit setting circuit, and the relay output circuit is operated by this output signal. By this operation, the relay input circuit of the secondary circuit operates, the semiconductor switching element becomes conductive, and power is supplied to the load.

The conduction angle of the semiconductor switching element is determined by the time limit set in the time limit setting circuit based on the level of the control input.

Contrary to the above, when the level of the control input is below a predetermined value, the control input detection circuit always drives the relay output circuit, so phase control is canceled and power is supplied at full phase. In other words, when there is no need to perform phase control,
What is necessary is to set the control input level to a predetermined value or less.

From this full-phase power supply state, the level of the control input is gradually increased beyond the predetermined value (as in the case of the conventional example, the conduction angle of the semiconductor switching element gradually decreases, and the load The power supply to the
By the way, as mentioned above, when the level of the control input is below a predetermined value, power is supplied at full phase.
The decrease in power supply as the level of the control input increases is a smooth decrease from the maximum power supply state at full phase, not a sharp decrease.

That is, as in a general operation mode, the shift in the power supply that accompanies the shift in the control input level smoothly follows the shift in the control input level, and sudden fluctuations in the power supply do not occur.

〔effect〕

From the above, according to the present invention, the following effects are exhibited. That is, (A) As in the general operation form, the shift of the supplied power accompanying the shift of the control input can be made smooth to follow the shift of the control input, so that the operability can be improved.

(B) Since the load can be driven even when the control input level is sufficiently low, the low limiter can be omitted and an increase in cost can be avoided.

(C) By reducing the control input to a predetermined value or less, it is possible to supply power in full phase, thereby increasing versatility.

<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 those shown in FIG. 2 according to the conventional example refer to the same parts as those indicated by the reference numerals in this embodiment. Furthermore, unless otherwise specified, the present embodiment and the conventional example have similar configurations regarding close reading.

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

A series circuit of voltage dividing resistors R+t+R+z is connected between the gate signal input terminal IC and the negative side DC power supply terminal 1b, and the connection point thereof is the transistor Tr.

connected to the base of. The collector of the transistor Trz is connected to the positive DC power terminal 1a via the resistor R13, and the emitter is connected to the negative DC power terminal 1b. The collector of the transistor Trz is the resistor R14.
is connected to the cathode of PUT4 via. This P
The cathode of UT4 is connected to the base of transistor Tr in relay output circuit 3.

The control input detection circuit 10 is configured with the above circuit configuration. That is, this control input detection circuit 10 constantly drives the relay output circuit 3 when the control voltage applied to the gate signal input terminal 1c is below a predetermined value, and when the control voltage exceeds the predetermined value. This makes the time setting circuit 5 active.

Note that a resistor RIS for stabilizing the charging voltage of the capacitor C1 is connected between both ends of the capacitor C9 in the timer circuit 2, and a resistor R1 in the timer circuit 2 and a phototransistor PT in the photocoupler PC+ are connected. A variable resistor VR for adjusting the charging time constant to the capacitor CI is connected between them.

Although the noise prevention capacitor cg 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 control voltage applied to the gate signal input terminal 1c is below a predetermined value, the voltage dividing resistor R1! Since the voltage across the terminals of R+2. is also below a predetermined level, the transistor 7r remains non-conducting. Therefore, the output current of the DC power supply E is the same as that of the resistor R+2. Flows to R+a, Rs,
The voltage across the resistor R3 causes the transistor Tr+ in the relay output circuit 3 to become constantly conductive.

As a result, the light emission of the light emitting diode LEDI -> the conduction of the phototriac PACI - the main triac TA
C+ is made conductive and drive power is supplied to the load. This supply is done under full phase and without phase control.

When the control voltage applied to the gate signal input terminal 1c is gradually increased from this full-phase power supply state beyond the predetermined value, the voltage dividing resistor RI! Since the voltage across the transistor Tr also exceeds a predetermined level, the transistor Tr becomes conductive.

Therefore, the output current of the DC power supply E is the same as that of the resistor R+3. The current flows through the transistor Trt, but does not flow through the resistors R14 and Rs. As a result, the constant R conduction state of the transistor Tr+ is released.Then, the transistor TrI is turned ON by the operation of the timer circuit 2 and the time limit setting circuit 5.・
OF F II is controlled. The operation in this case is the same as the conventional example, so the explanation will be omitted.

As mentioned above, when the control voltage is below a predetermined value, power is being supplied at full phase, so the decrease in supplied power as the control voltage increases is a smooth transition from the maximum power supply state at full phase. It is a decrease, but not a sudden decrease. That is, as in a general operation mode, the shift in the power supply that accompanies the shift in the control voltage smoothly follows the shift in the control voltage, and sudden fluctuations in the power supply do not occur.

Note that the output timing of the timer circuit 2 can be adjusted by adjusting the variable resistor VR.

[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...Control input detection circuit TAC+...Main triac (bidirectional semiconductor switching element) PO2...Photocoupler

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, the level of the control input is detected, and when the detected level is below a predetermined value, the relay output circuit is constantly driven, and when the detected level exceeds the predetermined value, the time limit is exceeded. A phase-controlled solid-state relay equipped with a control input detection circuit that activates the setting circuit.