JPH06314130A - Alternating current electric power controller - Google Patents

Abstract

PURPOSE:To enable accurate temperature control with a small error by a home electric heating controller, etc., by varying and controlling the electric feeding rate to a load with a trigger phase matched with the phase of the power source. CONSTITUTION:A counter circuit 15 which counts zero-cross detection pulses of a zero voltage sensor 12 supplies a reset signal to a flip-flop(FF) circuit 18 when its counted value reaches a specific value. Therefore, the FF circuit 18 is reset at the end of one control cycle to stop driving a zero-cross trigger pulse generating circuit 14 and also stops supplying electric power to the load 2. When the electric power supply is interrupted, on the other hand, the counter circuit 15 begins to count pulses again and when its counted value reaches a specific value latched in a latch circuit 16, a comparator circuit 17 outputs a set signal to set the FF circuit 18; and the pulse generating circuit 14 is driven again to restart supplying the electric power. Therefore, control for holding, for example, an electronic carpet at desired temperature can be performed in extremely short cycles of a one-over-several second.

Description

Description: TECHNICAL FIELD The present invention relates to an AC power control device suitable for power control of a household electric heat control device or the like.

[Prior Art] Electric heat control devices that use electric energy as a heat source have been put to practical use in various fields such as heating appliances, cooking appliances, and sanitary appliances. The major difference between the electric heat control device and the motor control device or the lamp control device is that the time constant of the load is large and a somewhat slow control is allowed. In fact, the so-called on / off control method, which intermittently connects between the load and the power source according to the polarity of the control deviation, is often used for electric heating control of household electric appliances such as electric kotatsu and electronic carpet.

 An AC power control device 1 shown in FIG. 6 is a device for controlling an electronic carpet to a desired temperature. A load 2 composed of a heating element that generates heat when energized causes AC power to pass through a power switch 3 such as a triac. It is connected to the power supply 4. The desired temperature set via the temperature setting device 5 is compared with the actual carpet temperature in the arithmetic circuit 6 having the microcomputer function, and as shown in FIGS. 7 (A) and (B), If the carpet temperature detected by the temperature sensor 7 is lower than the desired temperature, the power switch 3 is closed in response to a command from the arithmetic circuit 6, and the temperature is raised by continuous energization. Then, when the carpet temperature exceeds the desired temperature, the power switch 3 is opened at that time, and the state is maintained as it is until the carpet temperature falls several degrees from the desired temperature due to heat dissipation from the carpet surface.

 Therefore, the actual carpet temperature will be variably controlled within a certain range below the desired temperature, and the carpet surface will feel warm directly to the skin (power switch 3 ON period). And the period in which the user feels warm only with residual heat (OFF period of the power switch 3) was clear, and it was far from a comfortable heat-retaining effect with little change in sensible temperature. In addition, the carpet temperature fluctuates from the desired temperature to the lower side, so it is necessary to set a higher temperature, and there is a problem that the reactive power increases and it goes against the saving of heating costs. Furthermore, in the AC power control device 1 that employs such an on / off control method, since the load 2 is energized with the rated power consumption while the power switch 3 is closed, for example, in a general household with a breaker capacity of 20A, Despite using a rice cooker with a power consumption of 800W and an electronic carpet with a power consumption of 640W at the same time, when an iron with a rated power consumption of 700W was used without notice, the total power consumption was 2140W and the breaker was activated. It is possible that the rice cooker, which had been de-energized during operation, failed to cook normally. This is because the instantaneous maximum power easily exceeds the fusing limit of the fusing fuse in the breaker during the on / off control process.

 On the other hand, a phase control method using a power switch 3 using a triac as a rectifying element is known as an AC power control method different from the ON / OFF control method. In this type of phase control method, the arithmetic circuit 6 triggers the power switch 3 which receives a trigger pulse and energizes with a trigger phase according to the control target power, and uses the triac property to reduce the AC voltage to zero voltage. The power switch 3 is conducted up to the point where it crosses, and the power switch 3 conducts a half-wave of electricity at the maximum.

[Problems to be Solved by the Invention] The conventional AC power control device 1 of the phase control method described above is provided for each half cycle of the power cycle even when the carpet temperature does not reach the desired temperature or after reaching the desired temperature. Although the conduction period of the power switch 3 is variably controlled, the power switch 3 is closed at a phase according to the control power target, regardless of the power supply phase of the AC power supply, so that the power switch 3 is normally connected to the load 2. At the start of power transmission, a considerable load current was instantaneously passed or cut off, and as a result, a rapid change in load current generated radio noise. Such radio noise is a source of direct and indirect obstacles to other home electric appliances such as television receivers, audio equipment, or remote control devices, as well as fluorescent light noise and electric refrigerator start-up noise. The conventional AC power control device 1 that causes the radio noise disturbance at least once within one control cycle T has a problem that it is a continuous noise generation source throughout the entire process of electric heat control, although it is intermittent. It was

 Furthermore, in the conventional AC power control device 1, when the ambient temperature is low and heating is just started, there is often a considerable difference between the target temperature and the actual carpet temperature. An attempt is made to energize the load 2 at the maximum energization rate, which causes a considerable amount of power to be consumed by the electronic carpet. For this reason, commercial AC power supplied to ordinary households may temporarily cause a considerable voltage drop, for example, the illuminance of the lighting lamp in the same room suddenly decreases, or the TV The screen size of the receiver may fluctuate, and in extreme cases, power exceeding the current capacity may be consumed and the breaker may fall down.

[Means for Solving the Problems] The present invention is to solve the above problems, and is interposed between an AC power source and a load, receives a trigger pulse, and energizes a maximum of half a wave to the load. The power switch to perform, a zero voltage sensor that detects the output voltage of the AC power supply and outputs a zero-cross detection pulse when the output voltage of the AC power supply crosses the zero voltage, and the zero-cross detection pulse of this zero voltage sensor is limited to a certain value. Is cyclically counted and a zero-cross trigger pulse having the same phase as the output voltage of the AC power supply is supplied to the power switch during a series of counting periods in which both ends are defined by any two externally set count values. And a control unit.

[Operation] According to the present invention, the zero-crossing detection pulse obtained when the output voltage of the AC power supply crosses the zero voltage is cyclically counted within a fixed value, and both ends are defined by arbitrary two count values set externally. During a series of counting periods, a zero-cross trigger pulse of the same phase as the output voltage of the AC power supply is supplied to the power switch that is interposed between the AC power supply and its load, and the load switch is supplied with the trigger phase that matches the power supply phase. The duty ratio of is variably controlled.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. 1 and FIG. FIG. 1 is a circuit configuration diagram showing an embodiment of an AC power control device of this idea, and FIG. 2 is a signal waveform diagram of each part of the circuit shown in FIG.

 The AC power control device 11 shown in FIG. 1 is applied to the electric heat control of an electronic carpet, and a power switch 3 interposed between an AC power supply 4 and a load 2 composed of a carpet-like heating element is set to a zero voltage. The control unit 13 uses the output of the sensor 12 as a clock to control opening and closing. The zero voltage sensor 12 detects that the output voltage of the AC power supply 4 crosses the zero voltage, and outputs a zero-cross detection pulse having a very short pulse width shown in FIG. 2B at the time of detection. Since a triac is used as the power switch 3 in the embodiment, a zero-cross trigger pulse having the same phase as the output voltage of the AC power supply 4 is connected to the alternating power supply 4 as in the output zero-cross detection pulse of the zero voltage sensor 12. The power is supplied to the trigger input terminal of the power switch 3 via the trigger pulse generation circuit 14, and the trigger phase of the power switch 3 always matches the power supply phase.

 The control unit 13 cyclically counts the zero-cross detection pulse of the zero-voltage sensor 12 within a fixed value corresponding to, for example, a very short time of less than 1 second in terms of counting time, and is externally set. The trigger pulse is supplied to the power switch 3 through the zero-cross trigger pulse generation circuit 14 during a series of counting periods in which both ends are defined by the two count values. In the embodiment, the 4-bit counter circuit 15 which outputs a reset signal at the time of counting 1111 which is the upper limit of counting and the count value of the counter circuit 15 are compared with a predetermined value latched by the latch circuit 16, and both are compared. The comparator circuit 17 that outputs a set signal at the time of coincidence, and the set signal of the comparator circuit 17 and the reset signal of the counter circuit 15 are set or reset, and the zero cross trigger pulse generation circuit 14 with the set output or the reset output. And a flip-flop circuit 18 for driving The latch circuit 16 is given 4-bit data corresponding to the desired temperature via the arithmetic circuit 19, and continues to hold the data as a comparison reference of the comparator circuit 17 until the next latch command is given. Work.

 In the embodiment, the 4-bit data of 0000 to 1111 latched in the latch circuit 16 corresponds to the energization start timing for the load 2, and the 4-bit data becomes a smaller value as the desired temperature becomes higher. . Further, the temperature setter 20 connected to the arithmetic circuit 19 is composed of an electronic potentiometer, etc., and the desired temperature set by the volume operation is converted into 4-bit digital data in the arithmetic circuit 19, such as 0011. It Further, since the counter circuit 15 is reset when 16 half waves are counted, assuming that the power supply frequency is 50 cycles, 8/50 seconds is one control cycle T. Therefore, the constant value 1111 set in the counter circuit 15 corresponds to a very short time such as a fraction of a second in terms of counting time, and it can be said that the load fluctuation can be dealt with in such a short cycle.

 By the way, the counter circuit 15 which counts the zero-cross detection pulse output from the zero-voltage sensor 12 is reset to the flip-flop circuit 18 at the time when the numerical value reaches 1111, that is, when 16 zero-cross detection pulses are counted. Supply a signal. Therefore, the flip-flop circuit 18 is reset with the arrival of one control period T corresponding to eight times the power supply cycle, and the driving of the zero-cross trigger pulse generation circuit 14 is stopped. As a result, the supply of the zero-cross trigger pulse to the power switch 3 is cut off, and the power supply to the load 2 is stopped.

 On the other hand, when the power supply to the load 2 is interrupted, the counter circuit 15 having the count value 1111 as the count upper limit starts counting again from 0000, and the count value coincides with the predetermined value latched by the latch circuit 16, here 0011. At that time, that is, at the time when the fourth zero-cross detection pulse is counted after the reset of the flip-flop circuit 18, the comparator circuit 17 outputs the set signal. As a result, the flip-flop circuit 18 is set and the zero-cross trigger pulse generation circuit 14 is driven again, so that the zero-cross trigger pulse is given to the power switch 3 and the energization of the load 2 is restarted.

 Therefore, according to the AC power control device 11, the power switch 3 sets 12/16 · T as the on-period Ton in the control cycle T 1 in which one cycle is eight times the power cycle of 50 cycles or 60 cycles. In order to perform the opening / closing operation with the remaining 4/16 · T as the off period Toff, the power control for keeping the carpet temperature at the desired temperature is controlled by a very short control cycle T of about a fraction of a second. Since it can be carried out finely in units and the thermal time constant of the load 2 is large, it is a truly accurate and small error as an electric heat control device for electronic carpet, which was not previously subject to fine temperature control. Temperature control is possible.

 In addition, by limiting the energization period Ton in one control cycle T, the power consumption can be controlled freely. Therefore, even when used in a general home where the breaker capacity is limited, the breaker capacity can be selected by selecting the power. Safe and efficient power consumption that does not exceed the limit can be used, and it is possible to safely use household electric appliances such as rice cookers and irons that consume relatively large power.

 Furthermore, since the trigger phase of the power switch 3 by the zero-cross trigger pulse generation circuit 14 matches the power supply phase, no radio noise or the like is generated. Further, the arithmetic circuit 19 receives the setting input from the temperature setter 20 and causes the latch circuit 16 to latch the count value corresponding to the set temperature, and thereafter, the temperature of the carpet temperature detected by the temperature sensor 7 and the set temperature. The difference is calculated, and if the carpet temperature is lower than the set temperature, the power supplied to the load 2 is increased, and if the carpet temperature is higher than the set temperature, the power supplied to the load 2 is decreased. , Performs calculations required for power control.

 In the AC power control device 21 shown in FIG. 3, the power switch 22 is connected to the power supply line connecting the AC power supply 4 and the load 2, and the user closes the power switch 22 to load the load 2. Power is turned on. The power switch 22 is connected to the arithmetic circuit 19, and when the arithmetic circuit 19 receives a closing signal of the power switch 22, one of the two count values externally set in the control unit 13 is gradually changed. However, it works to gradually increase the duty ratio for the load 2. That is, in the embodiment, as shown in FIG. 4, when the power switch 22 is closed, the arithmetic circuit 19 gradually switches the 4-bit data set in the latch circuit 16 to a smaller value, and The duty ratio Ton / T for the load 2 is gradually increased. Therefore, even if the target temperature and the actual carpet temperature are significantly different when the ambient temperature is low and heating is just started, the arithmetic circuit 19 soft-starts the heating. The consumed power does not suddenly take a large value. Therefore, it is possible to avoid the inconvenience that the illuminance of the illumination lamp suddenly decreases with the voltage drop of the commercial AC power supply, or the screen size of the television receiver being viewed fluctuates as in the past. You can

 In addition, a voltage detection circuit 32 is branched and connected to a power supply line connecting the AC power supply 4 and the load 2, just like the AC power control device 31 shown in FIG. 5, and the voltage detected by the voltage detection circuit 22 is calculated by an arithmetic circuit. When the output voltage of the voltage detection circuit 32 drops below a preset constant value, one of the two count values externally set in the control unit 13 is changed to energize the load 2. It can also be configured to reduce the rate. In this embodiment, the arithmetic circuit 19 changes the 4-bit data set in the latch circuit 16 when the AC voltage supplied to the load 2 drops below a preset constant voltage, and energizes the load 2. It works to reduce the rate Ton / T. Therefore, when the ambient temperature is low and only when heating is started, or when many people step on the electronic carpet at once, there is a considerable difference between the set temperature and the actual carpet temperature. However, since the calculation circuit 19 automatically reduces the energization rate to the load 2, the electric power consumed by the electronic carpet is also reduced, and as in the conventional case, the illumination of the illumination lamp is reduced as the voltage of the commercial AC power supply is reduced. It is possible to avoid inconveniences such as a sudden drop in power consumption or a change in the screen size of the television receiver you are watching, and the power consumption exceeding the current capacity is consumed, causing the breaker to trip. Nothing.

 Further, in these embodiments, the electronic carpet which is the load 2 has a structure in which the heater wire 23 is energized to heat the carpet, as shown in FIG. The heat-sensitive wire 25 receives a current leaking from the heater wire 23 through the heat-sensitive wire 25 and senses the temperature of the carpet according to the value of the current flowing into the heat-sensitive wire 25.

 In each of the above embodiments, the counter circuit 15 is not limited to 4 bits, but 2 or 3 bits, or 5 or more bits can be used, and the number of bits according to the resolution in power control can be set. Adopt it. Furthermore, the flip-flop circuit 18 may connect the counter circuit 15 to the set input terminal and the comparator circuit 17 to the reset input terminal. In that case, the latched data of the latch circuit 16 ends the energization of the load 2. As the desired temperature rises, the latch data also takes a larger value to correspond to the time.

 Further, in each of the above embodiments, the AC power control device 11, 21, 31 is applied to the electric heat control device for the electronic carpet as an example, but other household electric heating appliances such as an electric kotatsu and an air conditioner are used. Further, it may be applied to cooking utensils and sanitary appliances.

[Effects of the Invention] As described above, according to the present invention, the zero-crossing detection pulse obtained when the output voltage of the AC power supply crosses the zero voltage is cyclically counted within a fixed value and is externally set. Supply a zero-cross trigger pulse in phase with the output voltage of the AC power supply to the power switch interposed between the AC power supply and its load during the series of counting periods whose both ends are defined by the arbitrary two count values. However, because the duty ratio to the load is variably controlled by the trigger phase that matches the power supply phase, the thermal time constant of the load is large, so conventionally it was not targeted for fine temperature control. When applied to a household electric heat control device, power control especially near the desired temperature can be finely performed in units of a very short control cycle such as less than 1 second. Small error Therefore, it is possible to perform uniform temperature control instead of the rough temperature control in which warmth and coolness are alternately felt on the skin like the conventional AC power control device of the on / off control method. Comfortable heat retention is possible, and power consumption can be controlled freely by limiting the energization period in one control cycle. Therefore, even when used in general households where the breaker capacity is limited, power consumption is limited. The selection allows safe and efficient power consumption that does not exceed the breaker capacity, and the trigger pulse is applied to the power switch differently from the asynchronous method in which the trigger pulse and the power supply phase are unrelated. Since it is a zero-cross trigger pulse method that is set near zero voltage, it has excellent features such as good suppression of radio noise generation. Achieve the results.

 Also, the present invention compares the count value of this counter circuit with a counter circuit that outputs a reset signal at the time of counting a constant value to a preset predetermined value, and when the two values match, It has a comparator circuit that outputs a set signal, a flip-flop circuit that is set or reset by receiving the set signal of this comparator circuit and the reset signal of the counter circuit, and the set output or reset output of this flip-flop circuit. By configuring a zero-cross trigger pulse generation circuit that is driven and supplies zero-cross trigger pulses to the power switch during the driving period, the predetermined value set as the comparison reference in the comparator circuit is set to the start timing (or end timing). ), And the counter circuit upper limit for the It is possible to freely change the energization time by adapting to the (time), which makes digital power setting via an arithmetic circuit, etc. extremely easy, and also allows proportional control to perform differential control or integration. By combining the controls, it is possible to introduce more sophisticated and complicated power control.

 Further, the present invention operates when the AC power supply starts energizing the load, and gradually changes at least one of the two count values externally set in the control unit to change the energization rate to the load. By providing a gradually increasing arithmetic circuit, even if there is a considerable gap between the target load state and the actual load when the energization is just started, the arithmetic circuit energizes the load. The power consumption is not suddenly consumed by the load because the rate is gradually increased.Therefore, as in the conventional case, the illuminance of the illumination lamp suddenly drops with the voltage drop of the commercial AC power supply, or It is possible to avoid inconveniences such as the screen size of the current television receiver fluctuating, and it is possible to prevent the breaker from dropping due to power consumption exceeding the current capacity. Achieve the effect.

 Further, according to the present invention, a voltage detection circuit for detecting the output voltage of the AC power supply, and when the output voltage detected by the voltage detection circuit drops below a preset constant value, the voltage is externally set in the control unit. 2 By providing at least one of the count values to reduce the energization rate to the load, an arithmetic circuit is provided so that the energization of the load is just started or the power consumption of the load increases rapidly. Even when there is a considerable gap between the target load state and the actual load, the arithmetic circuit automatically reduces the duty ratio to the load, so the power consumed by the load also decreases. As in the past, the illuminance of the illumination lamp suddenly drops with the voltage drop of the commercial AC power supply, or the screen size of the TV receiver being viewed fluctuates. It is possible to avoid the inconvenience in advance, an effect such as never like are consumed power exceeds the current capacity circuit breaker falls.

[Brief description of drawings]

 FIG. 1 is a circuit configuration diagram showing an embodiment of the AC power control device of the present invention, FIG. 2 is a signal waveform diagram of each part of the circuit shown in FIG. 1, and FIGS. FIG. 5 is a circuit configuration diagram showing another embodiment of the AC power control device of the present invention, a signal waveform diagram of each part of the circuit, and FIG. 5 is a circuit configuration showing still another embodiment of the AC power control device of the present invention. FIG. 6, FIG. 6 and FIG. 7 are respectively a circuit configuration diagram showing an example of a conventional on / off control type AC power control device and a waveform diagram showing the temperature control process thereof. 2. ． ． Load, 3. ． ． Power switch, 4. ． ． AC power supply, 11, 21, 31. ． ． AC power controller, 12. ． ． Zero voltage sensor, 13. ． ． Control unit, 14. ． ． Zero-cross trigger pulse generation circuit, 15. ． ． Counter circuit, 16. ． ． Latch circuit, 17. ． ． Comparator circuit, 18. ． ． Flip-flop circuit, 19. ． ． Arithmetic circuit, 20. ． ． Temperature setter, 22. ． ． Power switch, 32. ． ． Voltage detection circuit.

Claims (4)

[Claims] 1. A power switch which is interposed between an AC power supply and a load and receives a trigger pulse to energize the load for a maximum of half a wave, and an output voltage of the AC power supply crosses zero voltage. Finally, a zero voltage sensor that detects this and outputs a zero-crossing detection pulse, and counts the zero-crossing detection pulse of this zero-voltage sensor cyclically up to a fixed value, and uses any two externally set count values. An AC power control apparatus comprising: a control unit that supplies a zero-cross trigger pulse having the same phase as the output voltage of the AC power supply to the power switch during a series of counting periods in which both ends are defined. 2. The control unit compares the count value of the counter circuit, which outputs a reset signal at the time when the constant value is counted, with the predetermined value set in advance, and when the two values match each other. A comparator circuit that outputs a set signal, a flip-flop circuit that is set or reset by receiving the set signal of this comparator circuit and the reset signal of the counter circuit, and driven by the set output or reset output of this flip-flop circuit. The AC power control apparatus according to claim 1, further comprising a zero-cross trigger pulse generation circuit that supplies a zero-cross trigger pulse to the power switch during the driving period. 3. The AC power supply operates when the energization of the load starts, and gradually changes at least one of two count values set externally to the control unit to change the energization rate to the load. The power control apparatus according to claim 1, further comprising: an arithmetic circuit that gradually increases. 4. A voltage detection circuit for detecting the output voltage of the AC power supply, and an external setting for the control unit when the output voltage detected by the voltage detection circuit drops below a preset constant value. 2. The power control device according to claim 1, further comprising an arithmetic circuit that varies at least one of the two count values to reduce the duty ratio to the load.