JPH0739137A - Phase controller - Google Patents

Abstract

PURPOSE:To control a phase angle by calculating with software a cycle or a pulse width of a charging pulse which corresponds to a specified phase angle and changing the charging time of a capacitor for charging. CONSTITUTION:A charging pulse generating circuit 4 calculates and generates a charging pulse having a cycle which corresponds to a specified phase angle synchronously with the zero cross of an a.c. power supply AC and then transmits it through a charging pulse transmission circuit 12. In a charging and discharging circuit 5, constant voltage is cyclically applied to a capacitor for charging synchronously with the charging pulse, and when the charging voltage comes to a reference potential, stored charge is discharged. Using this discharging current as a trigger pulse, a load controlling circuit 18 causes current to flow in a load 22. When the a.c. power supply AC is at the zero cross, conduction is stopped and residual charge of the capacitor for charging 16 is discharged through a zero cross reset circuit 3. A phase is controlled by repeating the above mentioned operation cycle. By this method, a burden on hardware is lightened and only the software modifications are required for changing the phase control conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a phase control device which performs phase control in multiple stages.

[0002]

2. Description of the Related Art FIGS. 7 and 8 are circuit diagrams showing an example of a conventional phase control device. As shown in FIGS. 7 and 8, the conventional phase control device includes a diode bridge 31, a zero-cross reset circuit 32, a smoothing circuit 33, a charging / discharging circuit 34, which rectifies the current from the commercial AC power supply AC, and
It is composed of a load control circuit 35. 36 is a controlled load.

In a conventional phase control device, as shown in FIG. 7, a variable resistor or a switching unit of a plurality of resistors is used as a charging resistor 37 of a charging / discharging circuit 34 and a time constant with a charging capacitor 38 is used. DC power supply 3
Phase control is performed by keeping the voltage of 9 constant and controlling the charging time of the charging capacitor 38, or
As shown in FIG. 8, the phase control is performed by changing the voltage of the DC power supply 39 applied to the charging capacitor 38 of the charging / discharging circuit 34 to control the charging time of the charging capacitor 38.

[0004]

In the case where a microcomputer is used to continuously perform multi-step phase control as in today's day, a variable resistor is used as the charging resistor 37 shown in FIG. 7 for charging. Since the method of controlling the charging time of the capacitor 38 is generally difficult to control by a microcomputer, a method of controlling the charging / discharging time by switching a plurality of resistors is usually adopted. However, this method requires a large number of parts because a resistor and a changeover switch for the number of control steps are required in the case of continuously performing multi-step phase control, resulting in a heavy load on hardware. . Further, when the number of stages of phase control and the control angle are changed after the circuit design is completed, it is necessary to change not only the software of the microcomputer but also the circuit constants and the addition of parts.

Further, in the method of controlling the charging time of the charging capacitor 38 by varying the voltage of the DC power supply 39 shown in FIG. 8, a D / A converter (not shown) is generally used as its constituent element. However, in this case, peripheral circuits of the D / A converter such as an output buffer and an interface circuit with a microcomputer are required, and like the method of controlling the charging time using the variable resistor described above,
It places a heavy burden on the hardware.

An object of the present invention is to solve the above-mentioned problems, and in a phase control device for performing continuous multi-step control of a phase angle by using a charging time by a capacitor, a hardware load is increased as compared with a conventional system. It is an object of the present invention to provide a phase control device which is small in number and can be flexibly dealt with only by changing software when changing phase control conditions.

[0007]

SUMMARY OF THE INVENTION The present invention is a load control means for controlling an AC power source to be supplied to a load at a controlled phase angle, and charging for starting charging from a phase angle reference point of the AC power source. Phase control including a capacitor and load control instruction means for discharging the charging capacitor by reaching a predetermined charge level in a charge time corresponding to a predetermined phase angle of the AC power source and operating the load control means by the discharge In the device, a phase angle setting means for setting a predetermined phase angle,
Arithmetic means for computing the pulse period or pulse width of the charging pulse corresponding to a predetermined phase angle, and a train of charging pulses of the pulse period or pulse width computed by the computing means are generated in synchronization with the phase angle reference point. A pulse train generating means and a charging control means for performing pulse charging of the charging capacitor by the train of charging pulses are provided.

[0008]

In the present invention, the pulse period or the pulse width of the charging pulse corresponding to the predetermined phase angle is calculated by software by the calculating means, and the charging time of the charging capacitor is changed by this to control the phase angle. I'm trying to do.

[0009]

1 is a circuit diagram of a phase control device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration of a charge pulse generation circuit in FIG.

The commercial AC power supply AC is full-wave rectified by the diode bridge 1 and supplied to the smoothing circuit 2, the zero-cross reset circuit 3 and the charging pulse generation circuit 4. The smoothing circuit 2 smoothes the full-wave rectified direct current and outputs it to the charging / discharging circuit 5.

As shown in FIG. 2, the charging pulse generation circuit 4
Is a zero-cross detector 6 for detecting a zero-cross of the commercial AC current AC, a phase angle setter 7 for setting a required phase angle, and a pulse cycle or pulse width data of a charging pulse corresponding to a phase control angle. First memory unit 8
And the required phase control angle set by the phase angle setting unit 7, and the pulse width or pulse cycle data of the charging pulse stored in the first memory unit 8 is selected. In synchronization with the detection signal,
An arithmetic unit 10 for controlling the pulse train generation unit 9 and an arithmetic unit 1
A second memory unit 11 for storing the pulse cycle or pulse width data of the charging pulse selected by 0;
The pulse train generator 9 generates a charging pulse according to the control from 0.

FIG. 3 is a flow chart showing the operation of the charge pulse generating circuit 4 in the phase control device according to one embodiment of the present invention, and FIG. 4 is the first memory section in the charge pulse generating circuit 4 in the phase control device. 8 shows a data configuration example of FIG. 8, FIG. 5 is a flow chart showing a control flow for one cycle of the phase control device, and FIG. 6 is a charge pulse of the phase control device and a charging voltage of the charging capacitor. It is a figure which shows change. In the following description,
The operation of performing the phase angle control by changing the pulse cycle of the charging pulse will be described.

First, referring to FIG. 3, the charging pulse generating circuit 4
The operation of will be described. The arithmetic unit 10 receives the required value of the phase angle from the phase angle setting unit 7 in step 1, and in step 2
Then, the first memory unit 8 refers to the pulse period data corresponding to the required phase angle, and the pulse period data corresponding to the required phase angle referred to in step 3 is stored in the second memory unit 11. Here, the data in the first memory unit 8 is configured in a table shape as shown in FIG. 4, and for example, when the required phase angle is B, the data of the pulse period f _B is the second memory unit 1.
It is stored in 1.

The operation unit 10 repeats the above operation until the zero-cross detection signal is output from the zero-cross detection unit 6, and when the zero-cross is detected in step 4, the operation unit 1
When 0, the charge pulse generation of the pulse train generation unit 9 is stopped in Step 5, and the pulse cycle data is read from the second memory unit 11 and output to the pulse train generation unit 9 in Step 6. After that, in step 7, the pulse train generator 9 starts to generate the charging pulse.

Next, the phase control process for one cycle in the phase control device according to one embodiment of the present invention will be described with reference to FIGS. 5 and 6.

By constantly repeating the operation shown in the flowchart of FIG. 3, the charge pulse generation circuit 4 always generates a charge pulse in step 11 in synchronization with the zero cross of the commercial AC power supply AC.

The charge pulse transmission circuit 12 transmits the charge pulse output from the charge pulse generation circuit 4 to the charge / discharge circuit 5 via the pulse transformer 13. Since the charging control transistor 14 of the charging / discharging circuit 5 is turned on / off in synchronization with the charging pulse, as shown in FIG. 6, when in the on state, a constant voltage determined by the Zener voltage of the Zener diode 15 is cycled. By being applied to the charging capacitor 16 in a stepwise manner, the charging capacitor 16 is pulse-charged at every arrival of the charging pulse in step 12, and the charging voltage of the charging capacitor 16 gradually rises as shown in FIG. . When this voltage reaches the reference potential V _TH at the point P in FIG. 1 in step 13, the programmable unijunction transistor (PUT) 17 in step 14 is reached.
Is turned on, and the electric charge charged in the charging capacitor 16 is discharged.

This discharge current becomes a trigger pulse, the light emitting diode 20 of the photo bidirectional thyristor 19 of the load control circuit 18 emits light, and the bidirectional thyristor 21 in the photo bidirectional thyristor 19 is turned on in step 15 to turn on. A current flows through the control load 22. Then, in step 16, the current stops flowing in the bidirectional thyristor 21 in the photo bidirectional thyristor 19 at the time of the zero cross of the commercial AC power supply AC, so that the bidirectional thyristor 21 is turned off in step 17.

The charging pulse generation circuit 4 stops the generation of the charging pulse in step 18, and at the same time, in step 19, the total remaining charge of the charging capacitor 16 is discharged through the zero-cross reset circuit 3. The above operation is defined as one cycle, and the phase control is performed by repeating this operation.

The discharge timing of the charging capacitor 16 is determined by the pulse period of the charging pulse when the pulse width P _W is constant. For example, as shown in FIG. 6, when the cycle of the charge pulse is T ₁ > T ₂ , the discharge timing is T _C1
> T _C2 . This means that if the cycle of the charging pulse is shortened as shown in FIG. 6B, the charging time becomes shorter.
It is shown that the charging time becomes longer if the cycle of the charging pulse is lengthened as shown in (a). Therefore, the phase angle can be controlled by adjusting the pulse cycle of the charging pulse.

Even when the pulse width P _W in FIG. 6 is variable instead of the pulse period of the charging pulse, the same control operation as described above is performed.

In the phase controller of the present embodiment described above, the phase angle control is realized by adjusting the pulse period or pulse width of the charging pulse generated from the charging pulse generating circuit 4. When the charge pulse generating circuit 4 which is the center of the phase control is realized by using a microcomputer, the control of an arbitrary phase angle is performed by the software of the microcomputer, and the phase control in multiple stages is performed only by the software. Is possible.

In FIG. 1, a photo coupler or a relay may be used instead of the pulse transformer 13 in the charging pulse transmission circuit 12. In addition, although the zero cross point is used as the phase angle reference point, 90 ° or 180 °
Can also be used.

Further, the hardware constituting the present phase control device can be easily realized because it has only the charge pulse transmission circuit 12 other than the charge pulse generation circuit 4.

[0025]

As described above, according to the present invention,
Corresponding to load control means for controlling the AC power to be supplied to the load at a controlled phase angle, a charging capacitor for starting charging from a phase angle reference point of the AC power supply, and a predetermined phase angle of the AC power supply. A phase angle setting device for setting a predetermined phase angle in a phase control device, comprising: a load control instruction unit that discharges a charging capacitor when a predetermined charge level is reached during a charging time and operates the load control unit by the discharge. Means, a calculating means for calculating the pulse cycle or pulse width of the charging pulse corresponding to a predetermined phase angle, and a train of charging pulses of the pulse cycle or pulse width calculated by the calculating means are synchronized with the phase angle reference point. Pulse train generating means and charge control means for performing pulse charging of the charging capacitor by the train of charging pulses are provided. Since the pulse period or pulse width of the pulse is calculated by software by the calculating means, and the charging time of the charging capacitor is changed by this to control the phase angle, the burden on the hardware can be reduced. In addition, it is possible to flexibly deal with the change of the phase control condition only by changing the software.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a phase control device that is an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a charging pulse generation circuit in FIG.

FIG. 3 is a flow chart showing the operation of the charging pulse generation circuit in the phase control device.

FIG. 4 is a diagram showing a data configuration example of a first memory unit in the charging pulse generation circuit of the phase control device.

FIG. 5 is a flow chart showing a control flow for one cycle of the phase control device.

FIG. 6 is a diagram showing changes in the charging pulse of the phase control device and the charging voltage of the charging capacitor.

FIG. 7 is a circuit diagram showing an example of a conventional phase control device.

FIG. 8 is a circuit diagram showing another example of a conventional phase control device.

[Explanation of symbols]

1 diode bridge 2 smoothing circuit 3 zero cross reset circuit 4 charge pulse generation circuit 5 charge / discharge circuit 6 zero cross detection unit 7 phase angle setting unit 8 first memory unit 9 pulse train generation unit 10 arithmetic unit 11 second memory unit 12 charge pulse Transmission circuit 13 Pulse transformer 14 Charge control transistor (charge control means) 15 Zener diode 16 Charging capacitor 17 Programmable unijunction transistor (load control instruction means) 18 Load control circuit 19 Photo bidirectional thyristor (load control means) 20 Light emitting diode 21 bidirectional thyristor 22 controlled load AC commercial AC power supply

Claims (1)

[Claims] 1. A load control means for controlling an AC power supply to a load at a controlled phase angle, a charging capacitor for starting charging from a phase angle reference point of the AC power supply, and an AC power supply of the AC power supply. A phase control device comprising: a load control instruction unit that discharges the charging capacitor when a predetermined charge level is reached in a charge time corresponding to a predetermined phase angle and operates the load control unit by the discharge. Angle setting means for setting a phase angle of the charging pulse, a calculating means for calculating a pulse cycle or a pulse width of the charging pulse corresponding to the predetermined phase angle, and a charging pulse having a pulse cycle or a pulse width calculated by the calculating means. A pulse train generating means for generating a train of pulses in synchronization with the phase angle reference point,
A phase control device comprising: a charging control unit that performs pulse charging of the charging capacitor by the train of the charging pulses.