JPH0283605A - Electrification angle control circuit - Google Patents

Abstract

PURPOSE:To obtain stable operations for all the electrification angles by performing the electrification angle control of the inductive load of a fluorescent lamp, etc., by using a noise isolation transformer, an insulating transformer, a solid-state relay, and an integrated circuit for power control in addition to a switching device such as a triac, etc. CONSTITUTION:The noise isolation transformer 17 cuts off both an input noise from an AC power source 1 and a noise generated from the electrification angle control system of the triac 4. The insulating transformer 18 suppresses the noise transmitted from the trigger circuit of the triac 4 to the AC power source 1. The solid-state relay 19 consists of an input circuit 191 to receive a trigger signal inputted from the integrated circuit 20 for power control, an optical information part 192 to perform the optical information transmission of a received trigger signal, and the triac 194 to perform the electrification angle control of a load current by the trigger signal outputted from a zero cross circuit 193, etc. In such a way, an AC power added on the dimmer line of a stabilizer 2 for dimming can be controlled, then, the dimming of a fluorescent tube 3 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a conduction angle control circuit, and particularly to a conduction angle control circuit for controlling power consumption of an inductive load.

[Conventional technology]

Conventionally, in this type of device, for example, a power control device for a fluorescent lamp, a thyristor connected between a power source and a fluorescent lamp,
A synchronous power supply is generated in a circuit that controls the phase angle of gate 1 in a switching element such as a bidirectional thyristor (TRIAC), and this charges a capacitor connected to a unijunction transistor or bidirectional switching element. A method has been widely used in which the phase angle is controlled by controlling the amount of current and changing the time until the voltage of the capacitor reaches the switching voltage.

A third example of a conventional conduction angle control circuit using the above method is shown below.
To explain the diagram, 1 is a single-phase AC power supply, 2 is a dimming ballast, 3 is a fluorescent tube, 4 is a bidirectional thyristor (triac) for controlling the primary voltage conduction angle of the dimming ballast 2, and 5
is a stabilized power supply for conduction angle command, 6 is a variable resistor for setting conduction angle, 7 to 9 are fixed resistors, 10 is a transistor for current control, 11 is a capacitor for constant current charging, and 12 is a unijunction transistor for oscillation. , 13 is a pulse transformer, 14 is a constant voltage diode for synchronous power supply, 15 is a current limiting resistor, and 16 is a full-wave rectifier diode bridge. According to the above circuit, the current full-wave rectified by the diode bridge 16 connected to the AC power supply 1 is passed through the resistor 15.
The voltage flows from the voltage to the constant voltage diode 14. Here, the voltage generated between the anode and cathode of the voltage regulator diode 14 is defined as a synchronous power source. On the other hand, the conduction angle command signal obtained by dividing the voltage of the stabilized power supply 5 by the variable resistor 6 is transmitted to the resistor 7.
The current flows through the resistor 9 between the base and emitter of the transistor 10 and becomes the base current of the transistor 10. Note that the resistor 8 is a fixed bias resistor for the transistor 10. Due to the base current flowing through the transistor 10,
A collector current flows from the synchronous power supply between the collector and emitter of the transistor 10 through the resistor 9, and the capacitor 1
1 is charged with constant current. When the voltage across the constant current charged capacitor 11 reaches the switching voltage of the unijunction transistor 12, the charged charge passes from the emitter of the unijunction transistor 12 through the primary winding of the pulse transformer 13 at the same pace. ,
Discharged. As a result, the current induced in the secondary winding of the pulse transformer 13 becomes the gate current of the bidirectional thyristor 4 connected between the AC power supply 1 and the dimming ballast 2, and the bidirectional thyristor 4 The light is ignited and a voltage is applied to the dimming ballast 2 at the set conduction angle.

[Problem to be solved by the invention]

In the conventional conduction angle control circuit described above, capacitor 1
After the voltage of the capacitor 11 reaches the switching voltage of the unijunction transistor 12 and is not discharged, the capacitor 11 starts to be charged again, so that two or more gate pulses are generated within one cycle. Even if a bidirectional switching element whose switching voltage does not depend on the synchronous power supply voltage is used instead of the unijunction transistor 12, if the conduction angle becomes 90' or less, two or more gate pulses will similarly occur. When dimming fluorescent lamps, sudden fluctuations and distortions in the power supply voltage become a problem, and the phase of the alternating current for this inductive load is the phase of the voltage of the alternating current power supply 1 applied to the bidirectional thyristor 4 for controlling the conduction angle. Since the second and subsequent pulses cause the bidirectional thyristor 4 to fire at an unexpected conduction angle in the next half cycle, there is a drawback.

FIG. 4 is a waveform diagram showing the voltage waveforms of various parts of the conventional example shown in FIG. capacitor 1
1, (d) is the gate pulse waveform, (e
The voltage waveform applied to the bidirectional thyristor 4, (f
> indicates the input voltage waveform of the dimming ballast 2.

FIG. 4(d) shows the gate pulse waveform when the gate pulse signal of one period of the synchronous power supply voltage is generated two or more times. When voltage fluctuation is corrected by controlling the conduction angle of the triac 4 using this gate pulse signal, as shown in FIG. α may occur continuously, and the normal dimming effect of the fluorescent tube 3 may not be expected.

[Means to solve the problem]

The conduction angle control circuit of the present invention is connected between a noise isolation transformer having a primary winding connected to an AC power supply, the secondary winding of this noise isolation transformer, and an inductive load, and controls the load current to 1. - a switching element that controls the flow angle according to a signal input to a terminal, and a power control circuit that is operated by the AC power source and generates a variable delay pulse that can set a delay time from a zero-crossing point of the voltage waveform of the AC power source; A solid-state relay circuit that conducts when the variable delay pulse is input from the power control circuit and shuts off when the load current approaches zero, and a solid-state relay circuit that connects the primary winding to the AC power source and and an isolation transformer in which the gate terminal of the switching element is connected to a secondary winding.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

The AC power supply 1 is a source that supplies AC power after controlling the current conduction angle of the commercial frequency when the LAC 4 supplies AC power to the dimming ballast 2, which is an inductive load. The variable resistor 6 changes the delay time constant of the variable delay pulse generation system of the power control integrated circuit 20. The noise isolation transformer 17 blocks both input noise from the AC power supply 1 and noise generated from the current conduction angle control system of the triac 4. The isolation transformer 18 is 1
- Suppressing the noise transmitted from the trigger circuit of the reactor 4 to the AC power supply 1.

The solid state relay 19 is connected to the power control integrated circuit 2
An input circuit 191 that receives a trigger signal input from 0, and an optical information section 192 that transmits optical information of the received trigger signal.
, a zero cross circuit 193 that receives a trigger signal from the optical information section 192, and a triac 19 that controls the conduction angle of the load current using the trigger signal output from the zero cross circuit 193.
4, when controlling an inductive load with a triac, due to the phase delay of the load current, d v / d at the time of commutation is
In order to prevent the triac from shifting to the on state without a gate signal due to a change in the i/dt amount, the dv at the time of commutation is
A CR series circuit 195 suppresses the amount of /d;
6□ 197, 198, and 199 connection terminals.

The power control integrated circuit 20 includes an overcurrent detection circuit 228 that has an output impedance component when determining a time constant that determines a period in which an inhibit signal is not generated in combination with a capacitor 24, and an overcurrent detection circuit 228 that has an output impedance component when the power supply voltage is half-wave rectified. A crossover detection/reset signal generator 227 that periodically detects the upper voltage from
DC stabilized power supply 226 taken out from the overcurrent detector 2
A buffer amplifier 225 that moderately amplifies the inhibit prevention signal generated by combining the output impedance component of 28 and the capacitor 24, and a servo amplifier 224 that uses the ground signal of the return line of the half-wave rectified voltage source as a servo error signal.
Voltage controlled current source 223 for generating variable delay pulses
and a level sensitive trigger signal generator 222 for generating variable delay pulses.
Trigger pulse output amplifier 221 for outputting the trigger signal output from 2 to the switching element, and connection terminal 2
01,202,203,204゜211.212,21
3,214. It is made up of spikes. 21 and 22 are fixed resistors that are used in combination with the variable resistor 6 to variably set the delay time constant when generating variable delay pulses within the power control integrated circuit 20; 24 is a diode, and 24 is a capacitor that determines each time constant of the DC stabilization/output voltage and inhibit hit prevention signal.

The output of the AC power supply 1 passes through a noise isolation transformer 17 and is supplied to a fluorescent lamp consisting of a dimming ballast 2 and a fluorescent tube 3 and a triac 4, and current conduction of the triac 4 is performed to preheat the fluorescent tube 3. The power supply system is branched into a power supply system that is not subjected to angle control and a power supply system for dimming that passes through a triac 4 that controls the current conduction angle of the power supply in order to perform dimming control of the fluorescent tube 3.

The AC power supply 1 is half-wave rectified by a diode 23, and the variable resistor 6. Capacitor 11. Fixed resistor 25.
Isolation transformer 18. Solid state relay19. Integrated circuit for power control ¥820. The AC power applied to the dimming line of the dimming ballast 2 is controlled by the gate signal generation function of the triac 4, which is composed of fixed resistors 21 and 22, and the conduction angle control of the inductive load performed by the triac 4. Light control of the tube 3 is performed.

FIG. 2 is a waveform diagram showing the waveforms of each part of the embodiment shown in FIG.
Output voltage waveform of, (b) solid state relay 19
(c) is the voltage waveform of the triac 4; (d) is the current waveform of the triac 4.

〔Effect of the invention〕

As explained above, the present invention applies not only to switching elements such as triacs, but also to noise isolation transformers,
By controlling the conduction angle of an inductive load such as a fluorescent lamp using an isolation transformer, a solid state relay, and an integrated circuit for power control, stable operation can be obtained for all conduction angles.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2(a)
-(d) are waveform diagrams showing voltage waveforms at various parts of the embodiment shown in Fig. 1, Fig. 3 is a block diagram of an example of a conventional conduction angle control circuit, and Figs. FIG. 3 is a waveform diagram showing voltage waveforms at various parts of the conventional example, and FIG. 5 is a waveform diagram for explaining problems in the embodiment shown in FIG. 1... AC power supply, 2... Dimming ballast, 3... Fluorescent tube, 4... Bidirectional thyristor, 17... Noise isolation transformer, 18... Isolation transformer,
19... Solid state relay, 20... Integrated circuit for power control, 191... Input circuit, 192... Optical information section, 193... Zero cross circuit, 194... Triac, 195... CR series circuit, 221...
Trigger pulse output amplifier, 222... Level sensing trigger generator, 223... Voltage controlled current source, 224...
Servo amplifier, 225... Loose amplifier, 226...
DC stabilized power supply, 227...Crossover detection/reset signal generator, 228...Overcurrent detector.

Claims (1)

[Claims] A noise isolation transformer has a primary winding connected to an AC power source, and is connected between the secondary winding of this noise isolation transformer and an inductive load. a switching element to be controlled; a power control circuit that is operated by the AC power source and generates a variable delay pulse that can set a delay time from a zero-crossing point of the voltage waveform of the AC power source; and the variable delay pulse is input from the power control circuit. Then, a solid-state relay circuit conducts and becomes cut-off when the load current approaches zero, and a primary winding is connected to the AC power source, and the gate terminal of the switching element is connected to the secondary winding through the solid-state relay circuit. A conduction angle control circuit characterized by comprising an isolation transformer connected to a line.