JPH06309043A - Ac electric power controller - Google Patents

Abstract

PURPOSE:To highly accurately control a time division by the AC electric power controller which performs AC electric power control over a controlled system according to a manipulated variable. CONSTITUTION:An integral arithmetic part 23 inputs the manipulated variable MV in the form of a load rate X, and subtracts a feedback signal G and also performs integration. A comparison part 27 outputs a timing signal B for a specific period when the integral output value is larger than a reference value. An AC detection part 33 when detecting a nearly-OV part of the voltage waveform of a load power source 31 outputs a detection signal to a zero-cross trigger circuit 29. The zero-trigger circuit 29 outputs a driving signal D to a thyristor 35 with the timing signal B and detection signal C and supplies AC load electric power to a load 37 through the thyristor 35. A feedback signal supply part 43 which is connected to the thyristor 35 outputs a feedback signal G which has a constant value to the integral arithmetic part 23 in the supply period of the AC load electric power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC power control device, and more particularly to improvement of an AC power control device for controlling the AC power of a heater or the like used as a load on the output side of a controller.

[0002]

2. Description of the Related Art As a system for controlling the temperature of a controlled object with a controller, as shown in FIG. 5, for example, a measured value from a temperature measuring sensor 3 arranged on a controlled object 1 such as a mold of an injection molding machine. From PV and a preset set value SV, a controller 5 for temperature control calculates a manipulated variable MV for PID, outputs it to the AC power controller 7, and supplies it to a load 9 such as a heater arranged in the controlled object 1 as a heater current. A configuration is known in which AC power control is performed by the AC power control device 7 according to the operation amount MV. Figure 5
Reference numeral 11 is a load power source. Then, as a control method of the AC power control device 7 in such a control system, there are generally phase control and time proportional on / off control.

In the former phase control method, as shown in FIG. 6, AC power is controlled by switching and energizing an AC load power source at an arbitrary phase angle, and since it can be adjusted at an arbitrary phase angle, fine control is possible. It is possible and the control is highly stable. However, since this phase control method switches the AC load power supply at an arbitrary phase angle, high-frequency noise is easily generated and is not suitable for a control system that is vulnerable to noise.

The latter time proportional ON / OFF control system is shown in FIG.
As shown in, AC power control is performed by changing the ratio of ON time and OFF time during a fixed period (2 seconds in FIG. 7), and noise is generated because switching is performed near 0 V of the AC load power supply voltage. It is also suitable for control systems that are difficult and susceptible to noise. On the other hand, in this control method, since the time interval between the on time and the off time is long, the ripple based on the control is apt to be long, and the fine control cannot be expected, and the control stability is difficult. A time-division control method is an improvement of both control methods. This is, for example, as shown in FIG. 8, when the AC load power supply voltage is zero as in the time proportional on / off control system.
Although it switches in the vicinity of V, unlike the time proportional ON / OFF control method, it has no cycle and is a method in which the ON time and the OFF time are repeated alternately and frequently, which makes it difficult to generate noise and is closer to the phase control described above. There is an advantage that controllability can be expected.

FIG. 9 shows a conventional A using a time division control system.
It is a block diagram showing a C power control device. That is, the charging / discharging circuit 13 including resistors and capacitors, and the voltage level Vm obtained by converting the operation amount MV from the controller 5 in FIG. 5 into a voltage.
And a charging / discharging voltage of the charging / discharging circuit 13 are compared with each other, and when the charging / discharging voltage exceeds the voltage level Vm, a comparison circuit 15 which outputs an ON / OFF standby instruction signal for power supply to the load
And an AC detection unit 17 that monitors the AC load voltage waveform of the load power supply 11 and outputs a detection signal when the voltage is near 0V, and from the AC detection unit 17 under the condition that the ON / OFF standby instruction signal is input. The zero-cross trigger circuit 19 turns on / off the power supply by the input of the detection signal and the thyristor 21 such as a triac (trademark) that switches the AC power to the load 9 by the zero-cross trigger circuit 19.

The charging / discharging circuit 13 supplies AC to the load 9.
The charging / discharging is alternately switched by the zero-cross trigger circuit 19 in accordance with the on / off switching timing of the power supply, and discharge is performed during the period when the AC power is being supplied to the load 9, and the supply of the AC power is stopped. It is configured to charge during a certain period. In such a conventional AC power control device of the time division control system, when the charging / discharging circuit 13 repeats charging / discharging in sections t1, t2, t3 ... (C in the same figure) as shown by the solid line in FIG. 10A, At first A to load 9
Since the C power supply is stopped, the charging / discharging circuit 13 performs a charging operation, and when the charging voltage rises and exceeds the voltage level Vm of the manipulated variable MV, the comparison circuit 15 zero-crosses the on / off standby instruction signals P and Q. Output to the trigger circuit 19.

That is, at the time when the voltage level Vm of the manipulated variable MV exceeds the charging voltage in the section t1, the ON standby instruction signal P
Is output, the zero-cross trigger circuit 19 enters an ON standby state for supplying AC power to the load 9 side. To the zero-cross trigger circuit 19 to which the ON standby instruction signal P is input,
When a detection signal as shown in FIG. 10B is input from the AC detection unit 17 that monitors the AC load power supply waveform, the zero-cross trigger circuit 19 turns on the thyristor 21 in the section t2 to supply AC power to the load 9. To be done.

In the section t2, the thyristor 21 is supplying the AC power to the load 9, so that the charging / discharging circuit 13 performs the discharging operation and this continues until the section t3. Section t
In No. 3, as the discharge voltage from the charge / discharge circuit 13 decreases,
When the discharge voltage drops below the voltage level Vm of the manipulated variable MV, the comparison unit 15 outputs the off standby instruction signal Q, and the zero-cross trigger circuit 19 enters the AC power supply off standby state, while the AC detection unit 17 is in progress. When the detection signal is input from, the zero-cross trigger circuit 19 turns off the thyristor 21 in the section t4 to cut off the supply of the AC power to the load 9.

In the section t4, the thyristor 21 moves to the load 9
Since the C power is not supplied, the charging / discharging circuit 13 switches to the charging operation. After that, such an operation is repeated. Therefore, the AC power is supplied to the load 9 in the periods t2, t3, t5 ... As shown in FIG. 10C, and if the operation amount MV applied to the comparison unit 15 is changed, the voltage level Vm of FIG. 10A is obtained. It is possible to change the AC power supply period that fluctuates and is supplied to the load 9.

[0010]

However, in the AC power control apparatus shown in FIG. 9 described above, the charging / discharging voltage of the charging / discharging circuit 13 is compared with the voltage level Vm of the manipulated variable MV, and therefore the manipulated variable MV. On the other hand, there is a dead zone of the AC power control, and the AC power supply amount changes stepwise with respect to the change of the operation amount MV, so that the AC power control tends to be oscillating. For example, in FIG. 10, even if the manipulated variable MV changes slightly and the voltage level Vm rises a little, the point at which the charge / discharge voltage level crosses the voltage level Vm of the manipulated variable MV, that is, the on / off standby instruction signals P and Q are output. The points may exist in the sections t1 and t3, respectively, and may not be used in the next sections t2 and t4, and the AC power supply waveform of FIG. 10C may not change.

As described above, even if the manipulated variable MV changes, the amount of increase or decrease is not postponed to the subsequent section from the section to which the point across the level of the charge / discharge voltage belongs, so that the manipulated quantity MV is large to some extent or more. As long as it does not change, the AC power supply cannot be changed, and there is room for improvement in control targets that require high accuracy. The present invention has been made under such circumstances, and it is possible to make use of this in the AC power supply control even when the operation amount is small.
An object of the present invention is to provide an AC power control device that can realize a highly accurate time-division control method.

[0012]

In order to solve such a problem, the present invention subtracts a constant signal as a power supply feedback signal from a load factor corresponding to a manipulated variable and integrates it, or an integrated output value thereof. An integral calculation unit that integrates the load factor and subtracts it with the constant signal to output an integrated output value that is the integrated value of the load factor, and a comparison that outputs a timing signal when the integrated output value exceeds a reference value. Department and A
An AC detection unit that detects the vicinity of the 0 potential of the C load power source and outputs a detection signal, and outputs a drive signal in which at least one unit between the vicinity of the 0 potential is based on the logical product of the timing signal and the detection signal. A drive unit that turns on the AC power supply to the load and a feedback signal supply unit that outputs the constant signal to the integral calculation unit during the ON period of the AC power supply to the load are provided. Further, in the present invention, the feedback signal supply section may be formed by the drive section, or may be formed independently of the above sections.

[0013]

According to the present invention having such means, the integral calculating section subtracts a constant signal from the load factor corresponding to the manipulated variable and integrates the integrated output value, or the load factor and integrates the constant signal. The subtracted integrated output value is output, the comparator outputs a timing signal when the integrated output value becomes equal to or greater than the reference value, and the detection signal output from the AC detector when the vicinity of 0 potential of the AC load power supply is detected. And a timing signal thereof, the drive section outputs a drive signal in which at least one unit is in the vicinity of the 0 potential to supply AC power to the load, and the feedback signal supply section supplies AC power to the load. The constant signal is output to the integral calculation unit during the supply ON period. If the feedback signal supply section is formed by the drive section, the circuit configuration can be simplified, and the feedback signal supply section can be formed independently of the above sections according to the signal form of the load factor to be handled.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an AC power control device according to the present invention. In FIG. 1, the integral calculation unit 23 inputs an operation amount MV from a controller (see FIG. 5) not shown in the form of a load factor X, and a power supply feedback signal (simply a feedback signal) from an output amount feedback unit 25 described later. G) Load factor X
Is subtracted from, and the subtracted value is sequentially integrated and output to the comparison unit 27. The subtracted value Y can be represented by Y = X−G.

Here, the load factor X can be expressed as follows, where MVmax is a value corresponding to 100% of the manipulated variable MV and MVmin is a value corresponding to 0%. X = (MV-MVmin) / (MVmax-MVmi
n) For example, in the controller with 4 to 20 mA output, the manipulated variable MV
Is 12 mA, the load factor X is (12-4) / (20-4) = 0.5. When the manipulated variable MV of the controller is expressed as 0 to 100%, X = MV (%) / 100 (%). Further, the integrated output value A that is integrated by the subtraction value Y and is output to the comparison unit 27 can be expressed by the following equation.

[0016]

[Equation 1] The symbol t0 in the equation 1 indicates the power-on time, the symbol t indicates an arbitrary time after the power-on, and the integrated output value A changes, for example, as shown by the solid line in FIG. 2A, which will be described in detail later. The comparison unit 27 compares whether or not the integrated output value A from the integration calculation unit 23 is equal to or larger than a predetermined reference value, and outputs the timing signal B to the zero-cross trigger circuit 29 if it is equal to or larger than the reference value. During the predetermined period T, high-frequency noise is not generated when the load power supply 31 is switched on and off, which will be described later.
Since it is turned on / off in the vicinity of 0 V (0 potential) of the AC load power supply waveform, it has a value shown by the following equation. T = n × (1 / 2f)

Here, the symbol f is a power source frequency of the load power source 31, and the symbol n is an arbitrary integer (generally selected to be 1 or 2). For example, in the case of the load power source 31 of 50 Hz, n = 1. Then, T = 10 ms, and the minimum on-time T is a half cycle of the load power supply 31. Hereinafter, a case where n = 1 will be described as an example. Symbols t1 to t7 ... Representing the sections in FIG. 2 are the predetermined period T. The reference value (1 × T) is the minimum unit of output and is an integral value during the minimum on-time T when the load factor X is “1”, and can be expressed by the following equation.

[0018]

[Equation 2] The AC detection unit 33 monitors the AC power supply voltage waveform of the load power supply 31 and outputs a detection signal C as shown in FIG. 2C to the zero-cross trigger circuit 29 when detecting the vicinity of 0 V of the waveform. The zero-cross trigger circuit 29 includes the comparison unit 2
When the timing signal B from 7 and the detection signal C from the AC detection unit 33 are aligned, that is, their logical product (AN
When D) is satisfied, it internally has an internal signal C ′ that is turned on only for a predetermined period T, and when the detection signal C from the AC detection unit 33 and the internal signal C ′ are complete, the load power supply 31 outputs 0.
The drive signal D is output so that the thyristor 35 is turned on (conducting) near V. Therefore, the zero-cross trigger circuit 29 is a drive unit of the thyristor 35, and the drive signal D can be expressed as shown in FIG. 2D.

The load power source 31, the thyristor 35 and the load 37 are connected in series to form a load circuit 39. The load power supply 31 is a general AC commercial power supply as it is or an AC power supply that has stepped up or down the voltage, and the thyristor 35 is a power control semiconductor switching unit (element) such as a triac, which is an amphipathic 3 that controls ON of the AC load power supply by a drive signal. It is a terminal type. That is, the zero-cross trigger circuit 37
Based on the drive signal D from the
Supply C power (half-wave power), if AC load power is 0V
Then, the power supply to the load 37 is cut off, and the next drive signal D
The AC power is again supplied to the load 37 by. FIG. 2E illustrates such a power supply state. The load 37 is a heater, a relay, or the like arranged in the mold or the like to be controlled as described above (see FIG. 5).

An output monitor 41 is provided at both ends of the thyristor 35.
Are connected. This output monitor 41 is a thyristor 3
5, the on-operation period is detected and the detection signal is output as the output amount feedback section 2
5, the voltage across the thyristor 35 is monitored to detect the ON operation period of the thyristor 35 from the voltage difference across the thyristor 35. FIG. 2F shows the transition of the voltage across the thyristor 35. The output amount feedback section 25 outputs a constant value as the feedback signal G to the integration calculation section 23 during the ON operation period of the thyristor 35 based on the detection signal from the output monitor 41, and together with the output monitor 41, the feedback signal supply section. 43 is formed. The constant value of the feedback signal G during the ON operation period is "1", which corresponds to the load factor 1, and is "0" during the OFF operation period.

That is, the feedback signal supplying section 43 is connected to the load 37.
Period (n is an integer multiple of the period T during which AC power is supplied to
2T only, a feedback signal G as shown in FIG.
And outputs "0" to the integration calculation unit 23 during the period when AC power is not supplied. The load power source 31 and the load 37 described above are the same as those of the present invention.
It is also possible that the thyristor 35 is located outside the C power control device, and in some cases, the thyristor 35 is located outside the AC power control device of the present invention.

By the way, the integral calculation unit 23, the comparison unit 27, the output amount feedback unit 25 and the output monitor 41, and the zero cross trigger circuit 29, which constitute the AC power control apparatus of FIG. As shown in FIG. 3, in many cases, the control unit 45 is mainly composed of a microcomputer. The control unit 45 has a CPU 45a having a calculation and comparison / judgment function, a ROM 45b storing an operation program of the CPU 45a, an input / output interface I / O 45c, and the like, and the ROM 45b has a reference for comparison with an integrated output value. The value is also stored.

In the control unit 45, the load factor X is A / D converted into a digital signal and the converted count value is given to the control unit 45.
To the load factor input section 47, a storage section (RAM) 49 for temporarily storing the integrated output value A, and a trigger circuit 51 for generating a drive signal for turning on and off the thyristor 35 by a trigger active signal from the control section 45. And the above A
The C detector 33 is connected. That is, the control unit 45
1 functions as the integration calculation unit 23 and the comparison unit 27 in FIG. 1 and outputs the trigger active signal to the trigger circuit 51 when the detection signal C from the AC detection unit 33 and the internal signal C ′ are aligned. , Which functions as the feedback signal supply unit 43, and the control unit 45 and the trigger circuit 51 of FIG. 3 form the zero-cross trigger circuit 37 of FIG. Note that the load power source 31 and the load 37 are located outside the AC power control device according to the present invention as in FIG.

Next, the AC of the present invention thus constructed
The operation of the power control device will be described with reference to FIG. Figure 2A
In the sections t1 and t2, the feedback signal G is “0” because the thyristor 35 is not on-operation, and the load factor X of the manipulated variable MV is subtracted from “0” in the integration calculation unit 23 (substantially unchanged). 2) and sequentially integrated, as shown in FIG.
It rises like the solid line of A. This integrated output value A is in the section t
When the reference value (1 × T) is exceeded in the latter half of 2, the comparison unit 27 outputs the timing signal B to the zero-cross trigger circuit 29.

The AC detection unit 33 monitors the AC power supply waveform of the load power supply 31 and outputs a detection signal C to the zero-cross trigger circuit 29 when detecting the vicinity of 0V. The zero-cross trigger circuit 29 forms an internal signal C ′ that is turned on for a predetermined period T from the logical product of the timing signal B and the detection signal C, and when the detection signal C and the internal signal C ′ are aligned, the drive signal D To the thyristor 35 to turn it on. Therefore, in the section t3, the load circuit 39
Turns on to supply AC power to the load 37.

Further, the output monitor 41 monitors the ON operation period of the thyristor 35, and during the ON operation period (section t3), the output amount feedback unit 25 transfers to the integral calculation unit 23 a constant value "1" for a minus amount. Is output as a feedback signal G.
Since the load factor X is equal to or less than “1” (X ≦ 1), the integrated output value A from the integral calculation unit 23 decreases as in the section t3 in FIG. 2A and drops beyond the reference value (1 × T). As a result, since the timing signal B is not output, the thyristor 35 does not operate in the section t4. Therefore, the feedback signal G from the feedback signal supply unit 43 becomes “0”, and the section t4
In the same manner as in the section t2, the integrated output value A from the integrating unit 27 rises and exceeds the reference value (1 × T), and the thyristor 35 is turned on by the action of the timing signal B. After that, such an operation is repeated.

As described above, the AC power control device is operated by the operation amount M.
When the integrated output value A of the load factor X based on V is equal to or larger than the reference value, AC power is supplied to the load, and when the AC power is supplied, the supplied amount is fed back and integrated while subtracting from the load factor X as a constant value. Control the AC power supply to the load,
The output amount from the controller is effectively used in the AC power control in the form of the load factor X, which enables highly accurate time-division control. Moreover, even if the manipulated variable MV changes, the amount of increase or decrease is utilized as the integrated output value A in the integration calculation and compared with the reference value, and therefore is utilized in the subsequent AC power control,
There is an advantage that the AC power supply to the load 37 can be continuously controlled even if the manipulated variable MV does not significantly change. In such an AC power control device, the load factor X corresponding to the manipulated variable MV can be implemented in either form of an analog signal or a digital signal.

Further, in the above-described embodiment, the feedback signal supply section 43 detects the supply period (ON period) of the AC power to the load 39 and feeds back the supply amount to the integration calculation section 23. However, in the present invention, as indicated by the broken line in FIG.
The feedback signal G may be fed back to the integration calculator 23 during the AC power supply period of the AC power from the zero-cross trigger circuit 29, and the zero-cross trigger circuit 29 may be formed accordingly. In this way, the zero-cross trigger circuit 2
In the configuration in which the feedback signal G from 9 is fed back to the integration calculation unit 23, it is not necessary to separately provide the feedback signal supply unit 43,
There is an advantage that the configuration is not complicated. However, load factor X
When operating as an analog signal, it is possible to simplify the circuit configuration by detecting the waveforms at both ends of the thyristor 35 accurately by the independent feedback signal supply section 43 and feeding back the feedback signal G to the integration calculation section 23. Moreover, it can be operated reliably.

In the above-described embodiment, when the load factor X is operated as a digital signal, the load factor X obtained in a sampling period shorter than the predetermined period T, that is, the minimum ON period is integrated. The invention is not limited to this. For example, every predetermined period T (minimum on-time 1 /
An operation of integrating the load factor X obtained by sampling every 2f) is also possible. That is, in the AC power control device of FIG. 1, the integral calculation unit 23 synchronizes the A / D converted load factor X1 (X1n to X1n + 5 ..., see FIG. 4) with the detection signal b from the AC detection unit 33. The integrated output value ICn subtracted by the feedback signal Z is output to the comparison section 27 when a feedback signal Z as a feedback signal from a feedback signal supply section 43 described later is input. Has been formed. The detailed operation of the integral calculator 23 will be described later.

It should be noted that it is also possible to form the load factor X into the digital value X1 by the A / D conversion by the integration calculation section 23 in synchronization with the detection signal b from the AC detection section 33. FIG. 4a is a voltage waveform of the AC load power supply 31,
4b is a waveform of the detection signal b from the AC detection unit 33, FIG.
c is the transition of the load factor X, the symbols Xn to Xn + 5 ... Are the load factors to be A / D converted, and the symbols X1n to X1n in FIG. 4d.
+5 ... is the load factor that has been A / D converted. Then, the integral value ICn in the integral calculator 23 can be expressed by the following equation.

[0031]

[Equation 3] In the equation 3, the reference sign Fm is “0” when the AC power is not supplied to the load 37 (OFF), and the feedback signal Z is a constant value when the AC power is supplied (ON) (the A / D conversion value when X = 1).
And the integrated value IC (n-
It is added to 1) and the following operation is performed. That is, the integrated value ICn of the integral calculator 23 is represented by ICn = IC (n-1) + X1n. Here, the symbol n indicates the time point n, and the item (n-
1) indicates one point before the n point.

The integral calculator 23 outputs an integral output signal ICn obtained by subtracting the feedback signal Z from the integral value ICn. Therefore, when the integrated value ICn is ICn ≧ Z, the integral calculating unit 23 performs the following calculation to replace it, and the solid line in FIG. 5e shows the relationship. ICn = IC (n-1) + X1n-Z The comparison unit 27 compares whether or not the integrated output value ICn from the integration calculation unit 23 is equal to or greater than a predetermined reference value Z, and if it is equal to or greater than the reference value, the above-described minimum on-time. The timing signal is output by T to the zero-cross trigger circuit 29 as a driving unit.

The load power supply 31, the AC detection unit 33, the thyristor 35, the load 37, and the output monitor 41 have the same configurations as those in FIG. 1 described above. The output quantity feedback section 43, which forms the feedback signal supply section 43 together with the output monitor 41, is
The constant value Z described above is output to the integration calculation unit 23 as a feedback signal based on the detection signal from. The feedback signal Z is a value when 100% of the output is output for the minimum ON time T, and is a count value corresponding to the reference value (1 × T) of FIG. 2 described above.

By the way, the AC power control device having such a configuration is also actually configured by a microcomputer mainly including the control unit 45 as shown in FIG. 3, and the ROM 45b has a reference value (feedback) for comparison with the output value ICn. Signal) Z is stored, and the replaced integrated output value ICn is temporarily stored in the storage section 49 sequentially. In the second embodiment, when the load circuit 39 operates, the integral value IC
2A is subtracted from the reference value Z, the load factor X (X1) is integrated as shown by the dotted line in FIG.
4E, and the AC power waveform supplied to the load 33 also has the same supply waveform as in FIG. 2E as shown in FIG. 4g.

In the AC power control device having the second structure as described above, the integral calculation unit 23 integrates the load factor X obtained by sampling every predetermined period T, and subtracts the feedback signal Z from the integrated value. When the integrated output value is equal to or larger than the reference value Z, the AC power is supplied to the load, and the load of the AC power 3
7 is supplied from the feedback signal supply section 43, and the integral calculation section 23 subtracts the subtraction signal Z from the integrated value and replaces it with the integrated output value to control the AC power supply of the load 33. In addition to the effect of the first embodiment described above, it is possible to control the time division method with high accuracy by only sampling and loading the load factor X at every predetermined period T.

[0036]

As described above, according to the present invention, the integrated output value obtained by subtracting a constant signal from the load factor corresponding to the manipulated variable and integrating it, or the integrated output obtained by integrating the load factor and subtracting it with the constant signal. A value is output, and a timing signal is output when the integrated output value becomes equal to or greater than a reference value. A unit of a drive signal is output, the AC power is supplied to the load based on the drive signal, and the constant signal is fed back to the integral calculation during the ON period of the AC power supply to the load. Therefore, since the load factor can be sequentially contributed to the integrated value, the load factor of the manipulated variable, which is the load factor before the AC power supply, is effectively used for the subsequent calculations, and the manipulated variable does not change significantly. Load improves points as said not be variably controlled, it is possible to accurately control the time-sharing manner. Further, in the configuration in which the feedback signal supply section is formed by the drive section, the entire circuit configuration can be simplified. further,
If the feedback signal supply unit is formed independently of the above units, there is an advantage that an accurate operation can be secured without complicating the circuit configuration when the load factor is an analog signal form, for example.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an AC power control device according to the present invention.

2 is a waveform diagram illustrating a first operation of the AC power control device of FIG.

FIG. 3 is a block diagram showing an actual circuit configuration when the AC power control device of the present invention is commercialized.

FIG. 4 is a waveform diagram illustrating a second operation of the AC power control device shown in FIG.

FIG. 5 is a general block diagram illustrating a temperature control system.

FIG. 6 is an AC load power supply waveform diagram for explaining a phase control method adapted to the AC power control apparatus in FIG.

FIG. 7 is an AC load power supply waveform diagram illustrating a time proportional on / off control method adapted to the AC power control device in FIG.

FIG. 8 is an AC load power supply waveform diagram for explaining a time division control method applicable to the AC power control device in FIG.

FIG. 9 is a block diagram showing a conventional AC power control apparatus using a time division control method.

FIG. 10 is a diagram illustrating an operation of the AC power control device of FIG. 9.

[Explanation of symbols]

 1 Control Target 3 Sensor 5 Controller 7 AC Power Control Device 9, 37 Load 11, 31 Load Power Supply 13 Charge / Discharge Circuit 15 Comparison Circuit 17, 33 AC Detection Section 19 Zero Cross Trigger Circuit 21, 35 Thyristor 23 Integral Calculation Section 25 Output Quantity Feedback unit 27 Comparison unit 29 Zero cross trigger circuit (driving unit) 39 Load circuit 41 Output monitor 43 Feedback signal supply unit 45 Control unit 45a CPU 45b ROM 45c Interface I / O 47 Load factor input unit 49 Storage unit (RAM) 51 Trigger circuit

Claims (3)

[Claims] 1. An integrated output value obtained by subtracting and integrating a constant signal as a power supply feedback signal from a load factor corresponding to a manipulated variable, or integrating the load factor and subtracting with the constant signal to obtain the load factor. An integral calculation unit that outputs an integrated output value that is an integrated value, a comparison unit that outputs a timing signal when the integrated output value becomes a reference value or more, and a detection signal by detecting the vicinity of 0 potential of the AC load power supply. An AC detection unit that outputs, and a drive unit that outputs a drive signal in which at least one unit is in the vicinity of the 0 potential based on the logical product of the timing signal and the detection signal to turn on the AC power supply to the load. An AC power control apparatus, comprising: a feedback signal supply unit that outputs the constant signal to the integration calculation unit during an ON period of AC power supply to the load. 2. The AC power control device according to claim 1, wherein the feedback signal supply unit is the drive unit. 3. The AC power control device according to claim 1, wherein the feedback signal supply unit is formed independently of each unit.