JP2004194477A - Apparatus and method for controlling electric power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To freely switch between phase control and cycle control. <P>SOLUTION: A power controller comprises: a phase control pulse generating means 6 which generates a phase control pulse with a phase angle corresponding to a controlled variable every half cycle; a cycle control pulse generating means 8 which generates cycle control pulses whose on-off ratio in a certain period corresponds to the controlled variable; and a control pulse selecting means 9 which selects either control pulse, the phase control pulse or the cycle control pulse, according to a control switching command for instructing to switch to phase control or cycle control. Then, the controller controls turn-on/off of a power switching means 7, using the selected control pulse as a trigger signal. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power control apparatus and a power control method for controlling AC power.
[0002]
[Prior art]
Conventionally, for example, there are phase control and cycle control as a power control method for controlling temperature by controlling power supplied to a load such as a heater.
[0003]
Phase control is to adjust the power to the load by controlling the phase angle through which the alternating current flows. If the power supply voltage at the moment when the power switching element such as a thyristor or triac is ignited is high, the current suddenly rises. Therefore, although it has a drawback that harmonic noise is likely to occur, it has high accuracy and has an advantage that the voltage can be reduced by reducing the phase angle through which the current flows.
[0004]
On the other hand, the cycle control has a drawback that the voltage cannot be adjusted by adjusting the power by controlling the energization time to the load by turning on and off the power switching element at the zero cross timing of the AC power supply. However, since switching is performed at zero-cross timing, there is an advantage that harmonic noise is small.
[0005]
By the way, in many lamp heaters, the electrical impedance of the heater largely changes depending on the heater temperature. When the temperature control is attempted by adjusting the power for such a load by cycle control, especially when the lamp heater is cold. In some cases, an excessive inrush current flows, the power switching element may break down, or flicker may occur in the power supply line.
[0006]
For this reason, for example, when energization to the heater is started, phase control is performed to suppress inrush current, and in steady state, cycle control is performed to perform power control with low noise. (For example, refer to Patent Document 1).
[0007]
[Patent Document 1]
Japanese Patent No. 3313044 (page 2-4, FIG. 2)
[0008]
[Problems to be solved by the invention]
However, in the conventional example such as Patent Document 1 described above, when energization of the heater is started, the phase angle is gradually increased from a small phase angle to shift to cycle control. For example, from phase control of an arbitrary phase angle. Switching to cycle control or switching from cycle control to phase control is not performed freely.
[0009]
The present invention has been made in view of the above points, and an object thereof is to provide a power control apparatus and a power control method capable of freely switching between phase control and cycle control.
[0010]
[Means for Solving the Problems]
The present invention is configured as follows in order to achieve the above-described object.
[0011]
That is, the power control device of the present invention is a device that controls the power switching means between the AC power supply and the load to control the power supplied to the load,
Phase control pulse generating means for generating a phase control pulse every half cycle at a phase angle corresponding to the control amount, and the phase control pulse or control amount in response to a control switching command for instructing switching to phase control or cycle control Control pulse selecting means for selecting any one of the cycle control pulses corresponding to the control pulse, and controlling on / off of the power switching means based on the selected control pulse.
[0012]
Here, the cycle control pulse refers to a pulse for controlling the energization time to the load by turning on / off the power switching means at the zero cross timing of the AC power supply.
[0013]
According to the present invention, either the phase control pulse or the input cycle control pulse is selected by the control switching command, and on / off of the power switching means is controlled based on the selected control pulse. And cycle control can be freely switched. In normal times, low-noise cycle control is performed. When energization to a load such as a lamp heater is started or when the control amount is small, phase control is performed to suppress peak voltage. It becomes possible to do. Further, as the cycle control pulse, for example, a cycle control pulse input from an external temperature controller or the like can be used.
[0014]
The power control device of the present invention is a device for controlling power supplied to the load by controlling a power switching means between the AC power source and the load, and is a half cycle at a phase angle corresponding to the control amount. In response to a phase control pulse generating means for generating a phase control pulse, a cycle control pulse generating means for generating a cycle control pulse corresponding to the control amount, and a control switching command for commanding switching to phase control or cycle control, Control pulse selecting means for selecting either the phase control pulse or the cycle control pulse, and controlling on / off of the power switching means based on the selected control pulse.
[0015]
According to the present invention, either a phase control pulse or a cycle control pulse is selected by a control switching command, and on / off of the power switching means is controlled based on the selected control pulse, so that phase control and cycle control can be switched freely. In normal times, low-noise cycle control is performed, and when energization to a load such as a lamp heater is started or the control amount is small, phase control can be performed to suppress the peak voltage.
[0016]
In one embodiment of the present invention, the cycle control pulse is a control pulse whose ON / OFF ratio in a fixed period corresponds to a control amount, and a zero-cross pulse generating unit that generates a zero-cross pulse at a zero-cross timing of the AC power supply, and a selection Trigger signal generating means for generating a trigger signal for turning on the power switching means on the basis of the control pulse and the zero cross pulse that are generated, and the trigger signal is generated at the timing of the zero cross pulse every half cycle. Is prohibited.
[0017]
According to the present invention, the generation of the trigger signal is prohibited at the timing of the zero cross pulse every half cycle, that is, the trigger signal is cleared every half cycle. In the case of deviation, power switching means such as a thyristor is prevented from being erroneously ignited, and high-precision control is possible.
[0018]
In another embodiment of the present invention, the control switching command instructs phase control at the start of energization of the load, and then commands switching to cycle control, and the phase control pulse generating means In the period in which the phase control at the start of energization is commanded, the phase angle is made constant or gradually increased.
[0019]
According to the present invention, the inrush current at the start of energization of the load can be suppressed.
[0020]
In a preferred embodiment of the present invention, load current detecting means for detecting a load current flowing through the load is provided, and the phase control pulse generating means detects the detected load current in the phase control command at the start of energization. Is smaller than a preset set current value, the phase angle is increased, and when the detected load current is larger than the set current value for a predetermined time, the phase angle is increased.
[0021]
According to the present invention, when the state in which the load current is larger than the set current value continues for a certain time or longer, the phase angle is forcibly increased because the phase angle is small and the load impedance does not increase. Smooth transition from phase control to cycle control can be performed.
[0022]
In another embodiment of the present invention, the control switching command instructs switching to phase control when the control amount is smaller than a predetermined control amount during a period in which cycle control is commanded. It is.
[0023]
According to the present invention, the control amount is small and the impedance of the load such as the heater is small. Therefore, in the cycle control, when the peak current during energization becomes large, the peak current is suppressed by switching to the phase control. can do.
[0024]
The power control method of the present invention is a method for controlling the power supplied to the load by controlling the power switching means between the AC power source and the load, and the phase is controlled every half cycle at a phase angle corresponding to the control amount. In addition to generating a control pulse, a cycle control pulse corresponding to a control amount is generated, and either the phase control pulse or the cycle control pulse is generated in response to a control switching command that instructs switching to phase control or cycle control. The control pulse is switched and selected, and on / off of the power switching means is controlled based on the selected control pulse.
[0025]
According to the present invention, either a phase control pulse or a cycle control pulse is selected by a control switching command, and on / off of the power switching means is controlled based on the selected control pulse, so that phase control and cycle control can be switched freely. In normal times, low-noise cycle control is performed, and when energization to a load such as a lamp heater is started or the control amount is small, phase control can be performed to suppress the peak voltage.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0027]
(Embodiment 1)
FIG. 1 is a functional block diagram showing a schematic configuration of a temperature control system including a power control device according to one embodiment of the present invention.
[0028]
The power control apparatus 1 of this embodiment controls the power supplied to the heater 4 as a load connected to the AC power source 3 in accordance with, for example, a control amount command (operation amount) from the temperature regulator 2. Further, for example, control is performed by switching between phase control and cycle control in accordance with a control switching command given from a PLC (programmable logic controller) 5.
[0029]
The power control device 1 includes a phase control pulse generator 6 that generates a phase control pulse in response to a control amount command from the temperature regulator 2, and an AC power source in response to a control amount command from the temperature regulator 2. A cycle control pulse is generated to turn on the power switching means 7 such as an SSR (solid state relay) or thyristor interposed between the heater 3 and the heater 4 for at least a half cycle (half cycle) of the AC power supply. In response to a control switching command given from the PLC 5 and the cycle control pulse generating means 8 that performs the control pulse, either a phase control pulse from the phase control pulse generating means 6 or a cycle control pulse from the cycle control pulse generating means 8 And a control pulse selection means 9 for switching and selecting, and triggering the control pulse selected by the control pulse selection means 9 And controls the on-off of the power switching means 7 as No..
[0030]
FIG. 2 is a block diagram showing a detailed configuration of the power control apparatus in FIG. 1, and parts corresponding to those in FIG. 1 are denoted by the same reference numerals.
[0031]
The phase control pulse generator 6 includes a microcomputer 10 to which a control amount command from the temperature controller 2 is given, and a phase angle corresponding to the control amount based on the zero cross of the AC power supply 3 based on the output of the microcomputer 10. And a phase control pulse generating circuit 11 for generating a phase control pulse every half cycle. The phase control pulse generation circuit 11 includes a phase control timer data generation circuit 12, a timer 13, and a count-up clock generation circuit 14, and sets a count value corresponding to the phase angle in the timer 13 and counts it. The up clock is counted, and when the count value matches the set count value, a phase control pulse is output from the CP terminal of the timer 13.
[0032]
The cycle control pulse generation means 8 is a cycle control pulse in which the on / off ratio in a fixed period is based on the control amount based on the microcomputer 10 to which the control amount command is given from the temperature regulator 2 and the output of the microcomputer 10. And a cycle control pulse generating circuit 15 for generating.
[0033]
The control pulse selection means 9 includes an inverter 16 to which a control switching signal from the PLC 5 is input, a first AND gate 17 to which a control switching command signal and a phase control pulse from the PLC 5 are input, and an output and cycle of the inverter 16. A second AND gate 18 to which a control pulse is input and an OR gate 19 to which outputs of both AND gates 17 and 18 are provided are provided. The output of the OR gate 19 turns on the SSR 20 constituting the power switching means 7. Trigger signal to be generated.
[0034]
Next, the operation of the power control apparatus 1 having the above configuration will be described based on the time chart of FIG. FIG. 3 shows an example of switching from cycle control to phase control.
[0035]
In the figure, (a) is a phase control pulse output from the phase control pulse generating means 6, (b) is a cycle control pulse output from the cycle control pulse generating means 8, (c) is a control switching command signal, ( d) is a trigger signal which is an output of the control pulse selection means 9, and (e) is an output of the SSR 20.
[0036]
The phase control pulse generating means 6 and the cycle control pulse generating means 8 output the phase control pulse and the cycle control pulse shown in (a) and (b), respectively, in response to the control command from the temperature controller 2.
[0037]
When the control switching command signal from the PLC 5 shown in (c) is a low level commanding cycle control, the cycle control pulse shown in (b) is output to the SSR 20 as a trigger signal as shown in (d). As shown in (e), cycle control is performed.
[0038]
When the control switching command signal from the PLC 5 is switched from the low level commanding the cycle control to the high level commanding the phase control, the phase control pulse in (a) is sent to the SSR as the trigger signal shown in (d). The output is switched to the phase control as shown in (e).
[0039]
Here, the control switching command signal from the PLC 5 is preferably switched at the timing of zero crossing. In this case, the zero cross of the AC power supply 3 is detected and a zero cross pulse is given to the PLC 5 so that the level of the control switching command signal is changed at the zero cross timing in the PLC 5. Of course, the control switching command signal may be output by a switching operation of the user.
[0040]
The level of the cycle control pulse is preferably changed at the zero cross timing, but may be switched at an intermediate timing.
[0041]
Switching from phase control to cycle control is performed in the same way.
[0042]
Since phase control and cycle control can be freely switched in this way, low-noise cycle control is normally performed, and when energization to a load such as a lamp heater is started or when the control amount is small, the phase control is performed. It is possible to reduce the load current by controlling the peak voltage, resulting in energy saving.
[0043]
Further, the phase control pulse from the phase control pulse generating means 6 and the cycle control pulse from the cycle control pulse generating means 8 are independently phase control pulses corresponding to the control amount regardless of which control is commanded. Since cycle control pulses are generated, these control pulses can also be used for other controls.
[0044]
In this embodiment, although the SSR is used as the power switching means, a power switching element such as a thyristor or a triac may be used, and either a self-extinguishing type or a non-self-extinguishing type may be used.
[0045]
(Embodiment 2)
FIG. 4 is a functional block diagram showing a schematic configuration of a temperature control system including a power control device according to another embodiment of the present invention, and parts corresponding to those in FIG. .
[0046]
In the power control device 1-1 of this embodiment, as in the above-described embodiment, the control pulse selected by the control pulse selection means 9 is not used as a trigger signal, but the zero cross pulse is generated at the zero cross timing of the AC power supply 3. And a trigger signal generating means 22 for generating a trigger signal based on the zero cross pulse from the zero cross pulse generating means 21 and the control pulse selected by the control pulse selecting means 9 are provided, The on / off state of the power switching means 7 is controlled by the trigger signal from the trigger signal generating means 22 so that more precise control switching can be performed.
[0047]
FIG. 5 is a block diagram showing a detailed configuration of the power control device 1-1 in FIG. 4, and parts corresponding to those in FIG. 2 are given the same reference numerals.
[0048]
The zero cross pulse generating means 21 has a phototriac coupler 23, detects a zero cross of the AC power supply 3, and outputs a zero cross pulse.
[0049]
The trigger signal generating means 22 is an RS flip-flop that outputs the trigger signal from the Q output, while the control pulse from the control pulse selecting means 9 is given to the set input and the zero cross pulse from the zero cross pulse generating means is given to the reset input. 24.
[0050]
The RS flip-flop 24 is a level input type. When the reset (R) input is at a low level, the Q output is set to a high level when the set (S) input is at a high level. When the reset input is at a high level, the Q output is reset to a low level regardless of the level of the set input. That is, it is once cleared at the rising edge of the zero cross pulse, but if the control pulse is at a high level, as soon as the zero cross pulse falls, the set input becomes a high level, so that it rises every half cycle.
[0051]
Other configurations are the same as those in the first embodiment.
[0052]
FIG. 6 is a time cheat for explaining the operation of the power control device 1-1 of this embodiment, and corresponds to FIG. 3 described above.
[0053]
In the figure, (a) is a phase control pulse output from the phase control pulse generating means 6, (b) is a cycle control pulse output from the cycle control pulse generating means 8, (c) is a control switching command signal, ( d) is a zero cross pulse output from the zero cross pulse generating means 21, (e) is a trigger signal which is an output of the trigger signal generating means 22, and (f) is an output of the SSR 20.
[0054]
The zero cross pulse generating means 21 detects the zero cross of the AC power source 3 and generates the zero cross pulse shown in (d) at that timing.
[0055]
Based on the zero cross pulse and the control pulse from the control pulse selecting means 9, the trigger signal generating means 22 triggers a control pulse that is off while the zero cross pulse is input, as shown in (e). It is output as a signal.
[0056]
That is, in this embodiment, the trigger signal is cleared by a zero cross pulse every half cycle.
[0057]
To further explain the relationship between the zero cross pulse and the trigger signal, the trigger signal is not output while the zero cross pulse is present (high level), cycle control is selected, and the cycle control pulse is high level. The trigger signal is output at the falling timing of the zero cross pulse, and when the phase control is selected, the trigger signal is output at the rising timing of the phase control pulse, the cycle control is selected, and When the cycle control pulse is at a low level, the trigger signal is not output.
[0058]
Here, the preferred pulse width of the zero cross pulse is preferably about 0.4 ms, for example.
[0059]
That is, the SSR is generally turned on when the voltage is about 10% of the effective value of the rated load voltage. For example, if the SSR is for 200V, the SSR is turned on at 20V. That is, if the trigger signal is input until the voltage on the load side of the SSR reaches 20V, false firing occurs.
[0060]
Here, the time t until the load side voltage becomes 20 V from the zero cross timing is calculated by the following equation when the power cycle is 20 ms (50 Hz). That is,
From load power peak value × sin (2πt / power cycle) = 20 [V],
√2 × 200 × sin (2πt / 20) = 20 [V]
As a result, t = 0.23 ms, and the pulse width of the zero cross pulse is twice this, that is, about 0.4 ms as described above.
[0061]
If the width of the zero cross pulse is too wide, the zero cross switching is not performed and noise increases.
[0062]
The trigger signal shown in (e) is turned off as described above during the period in which the zero cross pulse is output. However, since the zero cross pulse has the pulse width as described above, the output of the SSR 20 in the cycle control. Is the same as that of the first embodiment as shown in FIG.
[0063]
In the power control device 1-1 of this embodiment, compared to the above-described first embodiment, it is possible to prevent erroneous firing of the SSR 20 of the power switching means 7 and to switch control with high accuracy.
[0064]
This will be described in detail below.
[0065]
FIGS. 7 and 8 are time charts of the above-described first embodiment and this embodiment. These diagrams show that the cycle control pulse is at a high level (SSR ON command when switching from cycle control to phase control). ) And the rise of the control switching command signal is delayed from the zero cross timing. In these drawings, the vertical broken line indicates the zero cross timing Tz.
[0066]
In FIG. 7, since the trigger signal of (d) is not cleared every half cycle by the zero cross pulse, the control switching command signal is shifted from the cycle control command (low level) to the phase as shown in (c). When the timing for switching to the control command (high level) is delayed from the zero cross timing, the cycle control pulse in (b) is enabled and a trigger signal is output for a moment as shown in (d). As a result, as shown by the arrow A in (e), false firing occurs.
[0067]
On the other hand, in this embodiment shown in FIG. 8, the trigger signal is cleared every half cycle as shown in (e) by the zero cross pulse in (d), that is, in the zero cross timing. Since the output of the trigger signal is prohibited, the timing at which the control switching command signal is switched from the cycle control command (low level) to the phase control command (high level) as shown in (c). Even if it is later than the zero-cross timing, if it is earlier than the falling edge of the zero-cross pulse, the trigger signal is not output, and no false firing occurs as shown in (f).
[0068]
FIGS. 9 and 10 are the time charts of the above-described first embodiment and this embodiment, and these figures show a case where the falling edge of the cycle control pulse is delayed from the zero cross timing in the cycle control. ing.
[0069]
In FIG. 9, during the cycle control, the falling timing of the cycle control pulse in (b) is later than the zero cross timing, so that a trigger signal is output for a moment as shown in (d). As a result, as indicated by the arrow B in FIG.
[0070]
On the other hand, in this embodiment shown in FIG. 10, the trigger signal is cleared every half cycle as shown in (e) by the zero cross pulse in (d), that is, in the zero cross timing. Since the trigger signal output is prohibited, as shown in (c), if the timing at which the cycle control pulse falls is delayed from the zero cross timing but earlier than the falling of the zero cross pulse, the trigger signal Is not output, and no false firing occurs as shown in (f).
[0071]
As described above, in this embodiment, switching of half cycles is performed with high accuracy to prevent erroneous firing of the SSR 20, and highly accurate temperature control is possible.
[0072]
(Embodiment 3)
FIG. 11 is a functional block diagram of another embodiment of the present invention, and parts corresponding to those in FIG. 4 are given the same reference numerals.
[0073]
In this embodiment, since there are many temperature regulators that output a cycle control pulse as a control output, the cycle controller pulse generating means 8 of the above-described embodiment is replaced with a temperature regulator 25. In this embodiment, the phase control pulse generating means 6 is given a control command from the PLC 5 and generates a phase control pulse in accordance with this control command. Other configurations are the same as those in FIG.
[0074]
In this embodiment, in combination with the temperature regulator 25, cycle control can be performed by the temperature regulator 25 during steady state, and phase control can be performed as necessary.
[0075]
(Embodiment 4)
FIG. 12 is a functional block diagram of still another embodiment of the present invention, and portions corresponding to those in FIG.
[0076]
In this embodiment, a soft start timer circuit 26 is provided which outputs a start signal and a timer set value from the PLC 5 and outputs a control switching command signal based on them.
[0077]
This soft start timer circuit 26 outputs a control switching command signal that performs phase control for a preset time (timer set value) after the start signal is input from the PLC 5, and then performs cycle control. It is.
[0078]
In this embodiment, for example, when the heater 4 is cold, such as at the start of a day's operation, as shown in FIG. 13, by performing phase control with a reduced voltage for a certain period of time, the heater 4 The inrush current is reduced, and then cycle control is performed to control low noise.
[0079]
(Other embodiments)
As another embodiment of the present invention, the soft start shown in the flowchart of FIG. 14 may be performed.
[0080]
In this embodiment, load current detection means (not shown) for detecting the load current flowing through the load is provided, and the control amount of the phase control is adjusted while detecting the load current.
[0081]
That is, only when the detected current is smaller than the preset current value, the phase angle is increased by a fixed step, and when the phase angle (conduction phase angle) reaches 90 °, the inrush current is switched to cycle control. Is suppressed to an arbitrary value, and the phase control period is shortened.
[0082]
When the control amount of the phase control is small, the temperature of the heater 4 does not increase forever and the heater impedance does not increase, so the phase angle may not increase forever. Therefore, when the detected current value shows the same current value for a certain time or longer (the current does not decrease even at the same phase angle), the phase angle is forcibly increased by a certain amount, so that the heater 4 starts up. This is to prevent time trouble.
[0083]
A detailed description will be given based on the flowchart of FIG. 14. First, a current limit setting value set by the user is read (step n1). This current limit set value is a set value for which the user wants to limit the inrush current. For example, when the user wants to set the inrush current within 10 A, 10 A is set. Next, the same conduction phase angle counter for measuring the above-mentioned fixed time is cleared (step n2), the conduction phase angle is set to a preset conduction phase angle initial value (step n3), and half wave Each peak current is detected (step n4), and it is determined whether or not the peak current is smaller than the current limit set value (step n5). When the peak current is small, the conduction phase angle is increased by a certain step (step n6). The same angle counter is cleared (step n7), and it is determined whether or not the conduction phase angle is 90 ° or more (step n8). If not 90 ° or more, the process returns to step n4.
[0084]
In step n5, when the peak current is not smaller than the current limit set value, the conduction phase angle identical counter is incremented (step n9), and whether or not the count value of the conduction phase angle identical counter becomes 10 or more, It is determined whether or not the state in which the peak current is equal to or greater than the current limit set value has continued for a certain period of time (step n10). Forcibly increased by a certain step, and if not 10 or more, the process proceeds to step n8.
[0085]
In step n8, when the conduction phase angle is 90 ° or more, the process shifts to cycle control.
[0086]
Further, as another embodiment of the present invention, the following may be adopted.
That is, when the control amount is small, the heater 4 generates a small amount of heat because the amount of heat generated by the heater 4 is small. In cycle control, the peak current during energization increases as shown in FIG.
[0087]
Therefore, when the control amount is smaller than a predetermined control amount, for example, several percent, the peak current may be suppressed by switching to phase control as shown in FIG.
[0088]
In each of the embodiments described above, the power control device is controlled by the temperature controller and the PLC. However, as another embodiment of the present invention, the power control device is controlled by a single control device, for example, the PLC. May be.
[0089]
The cycle control is AC power control in which the power switching means is turned on and off at the zero crossing point. The applicant of the present application filed on March 15, 2000, “Cycle control device, power regulator, temperature regulator and temperature The present invention can also be applied to the cycle control proposed in “Control Device” (Japanese Patent Application No. 2000-71642).
[0090]
【The invention's effect】
As described above, according to the present invention, either the phase control pulse or the cycle control pulse is selected by the control switching command, and on / off of the power switching means is controlled based on the selected control pulse. Phase control and cycle control can be switched freely. Normally, low-noise cycle control is performed, and when energization to a load such as a lamp heater is started or when the control amount is small, phase control is performed to obtain a peak voltage. Can be suppressed.
[0091]
In addition, at the timing of the zero cross pulse every half cycle, by preventing the generation of the trigger signal, erroneous firing can be prevented and high-precision control can be performed.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a temperature control system including a power control device according to an embodiment of the present invention.
2 is a block diagram showing a detailed configuration of the power control apparatus of FIG. 1; FIG.
FIG. 3 is a time chart for explaining the operation of the embodiment of FIG. 1;
FIG. 4 is a functional block diagram of a temperature control system including a power control device according to another embodiment of the present invention.
5 is a block diagram showing a detailed configuration of the power control apparatus of FIG. 4;
6 is a time chart for explaining the operation of the embodiment of FIG. 4;
FIG. 7 is a time chart for explaining the operation of the embodiment of FIG. 1;
8 is a time chart corresponding to FIG. 7 of the embodiment of FIG.
FIG. 9 is a time chart for explaining the operation of the embodiment of FIG. 1;
10 is a time chart corresponding to FIG. 9 of the embodiment of FIG. 4;
FIG. 11 is a functional block diagram of a temperature control system including a power control device according to still another embodiment of the present invention.
FIG. 12 is a functional block diagram of a temperature control system including a power control device according to another embodiment of the present invention.
13 is a waveform diagram of an output voltage of the embodiment of FIG.
FIG. 14 is a flowchart for explaining the operation of still another embodiment of the present invention.
FIG. 15 is a diagram showing a peak current during energization of cycle control when the control amount is small.
FIG. 16 is a diagram corresponding to FIG. 15 in the case of phase control.
[Explanation of symbols]
1,1-1-3 power control device
2,25 Temperature controller
3 AC power supply
4 Heater
6 Phase control pulse generation means
7 Power switching means
8 Cycle control pulse generation means
9 Control pulse selection means
5 PLC
20 SSR
21 Zero cross pulse generation means
22 Trigger signal generation means

Claims (7)

An apparatus for controlling power supplied to the load by controlling power switching means between the AC power source and the load,
Phase control pulse generating means for generating a phase control pulse every half cycle at a phase angle according to the control amount;
Control pulse selection means for selecting either one of the phase control pulse or the cycle control pulse corresponding to the control amount in response to a control switching command for commanding switching to phase control or cycle control;
A power control apparatus for controlling on / off of the power switching means based on a selected control pulse. An apparatus for controlling power supplied to the load by controlling power switching means between the AC power source and the load,
Phase control pulse generating means for generating a phase control pulse every half cycle at a phase angle according to the control amount;
Cycle control pulse generating means for generating a cycle control pulse corresponding to the controlled variable;
Control pulse selection means for selecting a control pulse of either the phase control pulse or the cycle control pulse in response to a control switching command for commanding switching to phase control or cycle control;
A power control apparatus for controlling on / off of the power switching means based on a selected control pulse. The cycle control pulse is a control pulse in which an on / off ratio in a fixed period corresponds to a control amount,
A zero cross pulse generating means for generating a zero cross pulse at a zero cross timing of the AC power supply;
A trigger signal generating means for generating a trigger signal for turning on the power switching means based on the selected control pulse and the zero cross pulse; and
The power control device according to claim 1, wherein the trigger signal is prohibited from being generated at a timing of the zero cross pulse every half cycle. The control switching command is for instructing phase control at the start of energization to the load, and then for switching to cycle control,
4. The phase control pulse generation means is configured to increase or gradually increase the phase angle during a period in which the phase control at the start of energization is commanded. Power control device. Load current detection means for detecting a load current flowing through the load,
In the phase control command at the start of energization, the phase control pulse generating means increases the phase angle when the detected load current is smaller than a preset set current value, and the detected load current is The power control apparatus according to claim 4, wherein the phase angle is increased when a state larger than the set current value continues for a predetermined time. 6. The control switching command is a command for switching to phase control when the control amount is smaller than a predetermined control amount during a period in which cycle control is commanded. The power control apparatus described in 1. A method for controlling power supplied to the load by controlling power switching means between an AC power source and the load,
A phase control pulse is generated every half cycle with a phase angle corresponding to the control amount, and a cycle control pulse corresponding to the control amount is generated,
In response to a control switching command that commands switching to phase control or cycle control, either the control pulse of the phase control pulse or the cycle control pulse is selected by switching,
A power control method comprising controlling on / off of the power switching means based on a selected control pulse.

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