JPH0827665B2 - AC power controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an AC power control device for controlling the energization period of an AC power supply supplied to a load.

[Conventional technology]

Generally, when an AC power supply is supplied to a load and its average power is controlled, a method of controlling the energization period of the AC power supply is used. For this reason, the thyristor is turned on for a required period of time, and in order to prevent the accumulation of stress due to rapid heating of the glass, the energization period is gradually increased with a small power at first, and when the continuous energization state is reached with that power, the power is further increased. The same control is performed by switching to electric power.

[Problems to be solved by the invention]

However, such a conventional method turns on and off the current during energization, so that noise is generated and the voltage fluctuation rate of the power supply in the aircraft is not so good.
There is a problem that flicker occurs in a fluorescent lamp for in-flight lighting due to switching of electric power, which gives passengers an uncomfortable feeling.

[Means for solving problems]

In order to solve such a problem, the present invention provides an AC
Energization is controlled with the cycle as the minimum unit, and the power supply is gradually increased while alternately switching between power supplies with different powers, and after a continuous energization state, that power supply and a power supply with a larger power than that are switched alternately. The energization period of the power source with the smaller electric power is shortened over time, and the energization period of the power source with the larger electric power is gradually lengthened.

To achieve this, the present invention provides a timer whose output level monotonically increases at the beginning of power supply, a sawtooth wave generator having a cycle sufficiently longer than the cycle of the AC power supply, and a timer output signal while the glass temperature is low. An amplifier that outputs a higher level and outputs an output signal of a level lower than the timer output signal when the glass temperature exceeds a predetermined temperature, a diode connected in the forward direction from the amplifier to the timer direction, and an amplifier output signal A comparator that outputs an output signal when is larger than the sawtooth wave generator output signal, and an energization control unit that outputs an AC signal when the comparator output signal is generated,
Corresponding to the level detector for detecting the amplifier output signal in two stages, switching means for alternately switching between power sources having different powers corresponding to the level detected by the level detector, and level detected by the level detector And a level shift means for level shifting the sawtooth wave level.

[Action]

When the power is turned on initially, the power supply with the minimum power is subjected to intermittent energization control at the zero level of the AC waveform, and when it is in the continuous energization state, that power supply and the power supply with a larger power are alternately energized to control the power supply. The energization period of the small power source becomes shorter with time, and the energization period of the power source having large power becomes longer with time. In that state, after the power source with the larger power is in the continuous energization state, the power source with the larger power is controlled to be in the continuous energization state while the power source and the power source with the larger power are alternately switched. It

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is a filter circuit, 2 is a power supply circuit,
3 is a zero level detection circuit, 4 is a heater energization time control circuit, 5 is a gate signal generation time control circuit, 6 is a gate signal generation circuit, 7 is a thyristor circuit, 8 is an overcurrent detection circuit, and 9 is a heater current detection circuit. , 10 is a sensor short detection circuit, 11 is an overheat detection circuit, 12, 13
Is a switching circuit, 15 is an AND circuit, 16 is a relay, 16
a is a contact of the relay 16, 17 is a transformer, 18 ₁ and 18 ₂ are interlocking type power switches, 19 is a switch for sensor check, 20 is a switch for overheat check, 21 is a switch for power-on check, 22 Is a heater, 23 is an operation display lamp, 24 is a thermistor for detecting the temperature of the window glass, and 25 is a resistance.

The filter circuit 1 prevents intrusion of noise from the outside and leakage of noise from this device to an external device.
The power supply circuit 2 is adapted to convert an AC voltage into a DC voltage required for the operation of this device. Zero level detection circuit 3
Detects a zero level in each cycle of the AC waveform and generates a pulse signal at the start of one cycle. As shown in Fig. 2, the input terminal 3a, the output terminal 3b, and the resistor are connected.
32a to 32d, diodes 33a to 33c, a transistor 34, a capacitor 35, and an inverter 36.

The heater energization time control circuit 4 performs the energization time control with one cycle of the AC waveform as the minimum unit, taking into consideration the temperature of the window glass and the elapsed time from the time when the power is turned on, with respect to the current supplied to the heater. As shown in FIG. 3, this circuit includes an amplifier circuit 40, a three-minute timer 41 in which the output voltage monotonically increases for approximately three minutes after the power is turned on, a comparator 42, an oscillator 43 for generating a triangular wave of about 8 Hz, and a level judgment circuit. It is composed of 44, which are resistors 40a-40f, 41a-41f, 42a, 42b, 43.
a to 43m, 44a to 44g, differential amplifier 40q, 41q, 42q, 43q to 43s, 44
q, 44r, diodes 41t to 41v, 42t, 43t to 43w, 44t, capacitors 40x, 40y, 41x, 42x, 43x, 44x, input terminals 4a to 4c, output terminal 4
It is composed of d ~ 4f.

The gate signal generation time control circuit 5 is adapted to generate a gate signal necessary for controlling the energization time of the thyristor circuit 7 for one cycle. As shown in FIG. 4, resistors 50a to 50e and capacitors are provided. 51a to 51d, timer 52a to 52
c, buffers 53a to 53c, OR circuit 54, diodes 55a to 55c,
The inverters 56a and 56b, a set-set type flip-flop 57, an AND circuit 58, input terminals 5a to 5d, and output terminals 5e to 5h.

The thyristor circuit 7 is, as shown in FIG.
70a to 70f, input terminals 7a to 7m, and output terminals 7p to 7r.

As shown in FIG. 6, the gate signal generating circuit 6 includes NAND circuits 60a and 60b, resistors 61a to 61k, capacitors 62a to 62d, inverters 63a to 63d, buffers 64a and 64b, AND circuits 65a to 65l, RS.
-Type flip-flops 66a, 66b, diodes 67a-67s, transistors 68a-68d, pulse transformers 69a-69c, input terminals
6a to 6g, output terminals 6j to 6m, 6p to 6z.

As shown in FIG. 7, the overcurrent detection circuit 8 includes resistors 81a to 81h, capacitors 82a and 82b, diodes 83a to.
83c, differential amplifiers 84 and 85, input terminal 8a, output terminals 8b and 8c.

The heater current detection circuit 9 includes a transformer 9 as shown in FIG.
It is composed of 1, diode 92, differential amplifier 93, and reference voltage 94. When the rectified voltage generated by the heater current exceeds the value of the reference voltage 94, the signal of "1" level is sent out. 94 is selected to be slightly larger than the rectified voltage generated by the maximum standard value of the heater current supplied to the heater 22. Therefore, when the heater current is normally supplied, the heater current detection circuit 9 outputs a "1" level signal.

The sensor short detection circuit 10 is composed of a differential amplifier 10a, a reference voltage 10b, and inverters 10c and 10d, and normally activates the relay 16, but the voltage supplied to the input terminal 10e is the reference voltage 10b. When the sensor short becomes smaller, the relay 16 is deactivated at the time of overcurrent detection when the "1" level signal is supplied to the input terminal 10f and the overheat detection when the "0" level signal is supplied to the input terminal 10g. It is getting done.

Overheat detection circuit 11 is a differential amplifier 11a, reference voltage
11b, an inverter 11c, and a diode 11d, and a signal of "0" level is sent from the output terminal 11g at the time of overheat detection in which a voltage larger than the reference voltage 11b is supplied to the input terminal 11e.

The operation of the apparatus configured as described above is as follows, but for the sake of easy understanding, the power supplied to the heater will be described as one kind. Switch in FIG.
When 18 ₁ and 18 ₂ are on, the power supply circuit 2 supplies the voltage + V necessary for operation to each circuit, and the relay 16 is operating normally, so the filter circuit 1 is switched on. The passed AC waveform is supplied to the zero level detection circuit 3.
In this circuit, as shown in FIG. 2, a Zener diode 33c is inserted in series in the base circuit of the transistor, and a DC voltage + V is supplied to the transistor 34. For this reason, if the Zener diode 33c is short-circuited, the transistor 34 is supplied with the DC voltage + V, and the operation start level is as shown in FIG.
When the value of the AC waveform becomes smaller than that value, the transistor 34 is turned on.
Then, assuming now that the Zener diode 33c is working effectively, assuming that its breakdown voltage is equal to the DC voltage + V supplied to the transistor 34, the transistor 34 has an AC waveform from the original operation start level + V. Is turned on only after the level of
The signal shown in FIG. That is, the transistor 34 turns on at the zero level of the AC waveform and turns off at the next zero level.

In the above description, the reverse voltage between the base emitters of the transistor 34 is zero. However, this value is about 0.7 volt, and this level is inevitable as the inherent operation start level of the transistor 34. However, by properly selecting the DC voltage and the breakdown voltage of the Zener diode 33c, the operation start level of the entire circuit can be adjusted to zero level.

That is, for the transistor 34 to which a DC bias voltage is supplied in the operation direction, insert a level shift zener diode 33c for canceling the DC bias voltage so that the operation start level of the transistor 34 becomes zero volt. Therefore, the zero level can be detected. The voltage shown in FIG. 8 (b) generated at the resistor 32c is differentiated by the capacitor 35 and the resistor 32d to become a signal shown in FIG. 8 (c), which is clamped by the diode 33b and output by the inverter 36. The pulse is inverted and output from the output terminal 3b as a pulse shown in FIG. 8 (d).

The pulse output from the output terminal 3b is supplied to the input terminal 5a of the gate signal generation time control circuit 5 shown in FIG.
It is supplied to the terminal B of the timer 52b via the buffer 53b.
The timer 52b generates a signal of "1" level from the terminal Q and a signal of "0" level from the terminal at the falling edge of the signal supplied to the terminal B when the signal of "1" level is supplied to the terminal CD, This state continues for a time determined by the resistor 50b and the capacitor 51b. When the terminal CD goes to the “0” level, the level of the terminal Q is inverted. Accordingly, each time a pulse from the zero level detection circuit 3 as shown in FIG. 8D is supplied to the input terminal 5a, a pulse having a period T shown in FIG. 8E is output. During this period T, the resistor 50b and the capacitor 5
It is determined so as to be longer than a half cycle of the AC power supply and shorter than one cycle. The output signal of the timer 52b is supplied to the terminal 6d of the gate signal generating circuit 7 via the buffer 53c, the AND circuit 58, and the output terminal 5g (the AND condition of the AND circuit 58 is satisfied as described later). Therefore, as shown in FIG. 6, the NAND circuit 60b and the inverter 63b
The oscillating circuit consisting of (1) generates the gate signal shown in FIG. 8 (f), which has a short cycle determined by the resistor 61d and the capacitor 62b while the "1" level signal is supplied to the input terminal 6d.

On the other hand, when the power is turned on, the 3-minute timer 41 of the heater energization time control circuit shown in FIG. 3 sends out a "0" level signal, and this level gradually rises for about 3 minutes. . Therefore, the differential amplifiers 44q and 44r are “1”
The signal of the level is transmitted, and this is output through the terminals 4f and 4g, and the terminal of the gate signal generation circuit 6 shown in FIG.
It is supplied to one terminal of the AND circuits 65a and 65c via 6e and 6f and buffers 64a and 64b. The other terminals of the AND circuits 65a and 65c are supplied with the output of the zero level detection circuit 3 shown in FIG. 4 via the inverter 56b of the gate signal generation time control circuit 5. Then, as shown in FIG. 8 (d), the zero level detection circuit 3 is at the "0" level only for a short time after detecting the zero level, and is at the "1" level during the other periods. Therefore, the signal shown in FIG. 8 (d) is supplied to the other input of the AND circuits 65a and 65c of the gate signal generation circuit 6 shown in FIG. 6, and the period when the signal is at "1" level. The AND circuits 65a and 65c send out a "1" level signal. As a result, the flip-flops 66a and 66b are set, and both generate an "1" level signal from the output terminal Q.
Since this signal is sent from the AND circuit 65e at the "1" level, the high-frequency oscillation waveform sent from the inverter 63b is supplied to the transistor 68a via the AND circuit 65i, the diode 67b, and the resistor 61f. Turn on. As a result, the gate signal is supplied to the thyristors 70a and 70b of the thyristor circuit 7 via the pulse transformer 69a, and the thyristors are turned on. Since the thyristors 70a and 70b are supplied to the transformer 17 as shown in FIG. 5, the signal supplied to the transformer 17 is transformed and supplied to the heater 22.

Since the thyristors are connected in antiparallel as shown in FIG. 5, one of the thyristors is turned on by the positive half wave of the AC waveform. Generally, a thyristor turns on when a gate signal is supplied to the gate for a short time when a forward voltage is supplied to the anode, but it does not necessarily turn on depending on the operating environment conditions. Sometimes.
If used under good environmental conditions, this will not happen, but it is economically inefficient to always demand good environmental conditions. Even in such a case, the gate signal can be surely turned on by supplying the gate signal not only once but repeatedly. Therefore, with this device, 20KH
A gate signal having a frequency of about z is generated, and this gate signal is supplied to the thyristor for reliable operation.

The thyristor in the on state turns into the off state by reversing the polarity of the power supply voltage supplied between the anode and the cathode. Therefore, as shown in FIG. 5, if the thyristors are placed in anti-parallel and the high-frequency gate signal is continuously supplied even when the AC waveform becomes a negative half-wave, the thyristor is turned off at the time of the positive half-wave. The thyristor is turned on when the AC waveform becomes a negative half-wave. Here, if the gate signal exceeds the half cycle of the input AC waveform and is turned off within one cycle, the thyristor turned on at the end of one cycle of the input AC waveform is turned off. Become.

In this device, as shown in FIG. 8 (g), the thyristor is turned on from a negative half-wave. Then, since the gate signal is supplied even after the time point t1 at which the negative half-wave changes to the positive half-wave, when the positive half-wave occurs,
The thyristor, which was off at the time of the negative half-wave, is turned on, and the positive half-wave is output. Although the gate signal is not supplied at the time point t2, the thyristor that is on remains on until the time point t3 when the polarity of the power supply is a positive half-wave. At time t3, the negative half-wave occurs, so the thyristor that was on until now, that is, the positive half-wave, turns off, but from this time the gate signal is supplied again as shown in (f). Therefore, the thyristor which has been turned off by the positive half wave is turned on, and the output of the negative half wave is output from the thyristor circuit 7 continuously to the positive half wave as shown in (g). . In this way, if the gate signal is generated every time the AC waveform crosses the zero level in one direction, that is, from the positive direction to the negative direction, the AC waveform is continuously output.

At time t4, the gate signal is not supplied. However, as described above, the thyristor that has been turned on at this time is in the on state even when the gate signal is not supplied. However, at time t5, the polarity of the AC waveform changes, so the thyristor that was on until now turns off. Then, as shown in (f), since the trigger signal is not supplied after the time point t4, the thyristor circuit 7 also does not generate the output signal after this time point.

The heater energization time control circuit 4 is configured as shown in FIG. 3, and the three-minute timer 41, as shown in FIG. The oscillator 43 is saturated, and the oscillator 43 is shown in FIG. 9 (b).
As shown in, a triangular wave of about 8 Hz is generated. Therefore, as shown in FIG. 9 (c), the differential amplifier 42q outputs a "0" level signal while the output signal level from the 3-minute timer 41 is larger than the triangular wave. This signal is sent from the output terminal 4e and supplied to the terminal CD of the timer 52b via the terminal 5b of the gate signal generation time control circuit 5, the inverter 56a and the OR circuit 54 shown in FIG. Therefore, the signal shown in FIG. 9 (d) is supplied to the terminal CD of the timer 52b. On the other hand, since the frequency of the AC power supply is approximately 400 Hz, the cycle of the triangular wave is 50 times the cycle of the AC power supply, so that one cycle of the triangular wave corresponds to 50 cycles of the waveform of the AC power supply. Then, the signal shown in (d) is "1".
Since the gate signal is supplied to the thyristor circuit 7 during the level, the thyristor circuit 7 is intermittently turned on for 3 minutes after the power is turned on, and the period during which the thyristor circuit 7 is on becomes longer as time passes, ( After the output voltage of the timer shown in a) is saturated, it is continuously turned on. Therefore, the ninth
As shown in FIG. 6E, the AC waveform output from the thyristor circuit 7 has a large number of cycles during the output period with the passage of time.

The above description is for the case where the temperature of the glass is not taken into account.However, since the thermistor attached to the glass actually has a resistance value according to the temperature of the glass, the temperature is low when the power is turned on, and the resistance value is also low. The lower is the normal state. For this reason, since the voltage of the non-inverting input terminal of the differential amplifier 40q of the amplifying circuit 40 is higher than the voltage of the inverting input terminal, this circuit outputs a "1" level signal,
Is outputting a signal for heating so that the temperature becomes high. However, as mentioned above, when the power is turned on, the 3 minute timer
Since the output voltage of 41 gradually increases, the output level of the differential amplifier 41q is lower than the output level of the differential amplifier 40q, and the output level of the differential amplifier 41q becomes the output level of the differential amplifier 41q via the diode 41t. The signal of the clamped level is clamped and supplied to the inverting input terminal of the differential amplifier 42q. Then, when the heater is heated and the glass temperature rises, the resistance of the thermistor increases and the voltage supplied to the inverting input terminal of the differential amplifier 40q also increases, so that the output level of the differential amplifier 40q eventually increases. It is going down. The output level of the differential amplifier 40q is
When the output level is lower than 1q, the diode 41t is biased in the reverse direction, so the signal supplied to the inverting input terminal of the differential amplifier 42q is dominated by the output signal of the differential amplifier 40q, and the glass temperature is at the equilibrium temperature. The control is performed so that

The AC waveform output from the thyristor circuit 7 is the transformer 17
Is supplied to the heater 22, converted into a voltage required by the standard of the heater 22, and supplied to the heater 22. When performing intermittent energization time control using a transformer, if the intermittent time is shorter than a certain value, the next energization will start before the electromagnetic energy in the transformer is extinguished. When restarting, do not supply a current of the opposite polarity to the previous polarity,
The pole bundle in the iron core saturates and a large current flows. Therefore, an AC waveform as shown in Fig. 10 (a) is supplied, and when intermittently controlling this AC waveform, as shown in Fig. 10 (b), energization of the current that has been completed by the positive half wave is completed. When restarting, it is necessary to restart energization from the negative half-wave. In order to realize this, this device generates a gate signal when the waveform shown in FIG. 10 (a) changes in the negative direction as shown in FIG. 10 (c). Turn into a positive half-wave, stop before the half-wave ends,
The stop timing is selected to ensure that the thyristor is turned off when the positive half-wave changes to the negative half-wave.

With the above configuration, as shown in FIG. 10, energization control is performed with one cycle of the AC waveform as the minimum unit, and the energization time is as shown in FIG. 9 (e). It gradually becomes longer than the time, and as shown in Fig. 10 (b), energization is started from the time when the AC waveform crosses the zero level in a certain polarity direction, and the AC waveform has a zero level in the same polarity direction as when the energization started. Energization is stopped at the time of crossing. Then, this control is continued until the glass temperature reaches a predetermined temperature. After the temperature reaches the predetermined temperature, if the glass temperature changes due to a change in the outside air temperature or the like, control is performed to return the glass temperature to the predetermined temperature.

In the above description, one type of power is supplied to the heater 22. However, as described in the section of problems to be solved by the invention, controlling the power required for the heater 22 on and off is not a problem in controlling the temperature of the heater 22, but the power source of the aircraft is stable. Since the degree is not so good, the voltage inside the machine drops when the heater is energized, and the fluorescent lamp used for internal lighting flickers, which gives passengers an unpleasant feeling. For this reason, in the present invention, first, the energization time is controlled with low power, the energization period is gradually increased, and when the entire period is energized (this state corresponds to the state described above), The power of the value and the power larger than the power are alternately supplied to the heater. At that time, the energization time of the larger power is short at first,
Lengthen gradually over time. On the contrary, the energization time of small electric power is set to be shorter with the passage of time.

The following control operation will be described. As described above, in the timers 52a and 52b shown in FIG. 4, when the terminal CD is at "1" level, the output Q changes from "0" level to "1" level at the falling edge of the signal supplied to the terminal B. The reset terminal Q is unconditionally set to the "0" level when a "0" level signal is supplied to the terminal CD. Therefore, when a "1" level signal is generated from the terminal Q of the timer 52b, the timer
52a generates a "0" level signal from the terminal Q.
Then, the timer 52b is adapted to send a "1" level signal from the terminal Q while the signal shown in FIG. 9 (e) is being output, and the timer 52a is a signal shown in FIG. 9 (e). The signal of "1" level is output from the terminal Q during the period when is not output.

As shown in FIG. 4, the output of the timer 52a is supplied to the NAND circuit 60a of the gate signal generating circuit 6, and the output of the timer 52b is supplied to the NAND circuit 60b of the gate signal generating circuit 6 via the flip-flop 57 and the AND circuit 58. As shown in FIG. 6, the NAND circuit 60a and the NAND circuit 60b are provided.
Form an oscillating circuit (oscillating frequency of about 20 KHz), and these oscillating circuits are oscillating while a "1" level signal is supplied to each NAND circuit. As described above, since the timers 52a and 52b alternately generate outputs, the oscillation circuit including the NAND circuits 60a and 60b also alternately outputs. Each of these oscillation outputs is an AND circuit
65h and 65l, and the other inputs of these AND circuits are supplied to flip-flops 66a and 66 via AND circuits 65f and 65g.
Output from 6b is provided. This flip-flop circuit is controlled by a signal supplied from the heater conduction time control circuit 4 via the buffer 64a and the AND circuit 65a and a signal supplied via the buffer 64b and the AND circuit 65c. . The heater energization time control circuit 4
While the output level of the differential amplifier 40q shown in the figure is low, both the differential amplifiers 44q and 44r output a "1" level signal, but when the output of the differential amplifier 40q increases to a certain level, the differential amplifier 44q Sends a signal of "0" level. Then, when the output level of the differential amplifier 40q is further increased, both the differential amplifiers 44q and 44r transmit a signal of “0” level. The output of the differential amplifier 40q varies with its input, that is, the resistance value of the thermistor 24 connected to the terminal 4a, and the thermistor 24 changes according to the temperature of the cockpit window glass in which the heater 22 shown in FIG. 1 is embedded. Change. Since the temperature of the window glass changes depending on the magnitude of the current flowing through the heater 22,
When the heater temperature is higher than the first temperature, the differential amplifier 44q outputs a signal of "0" level. When the heater temperature is higher than the second temperature and is higher than the second temperature, the differential amplifier 44r is also "0".
Set a constant so that the level signal is output.

Therefore, when the power is turned on, the third minute timer 41 works
Both the differential amplifiers 44q and 44r in the figure send out a signal of "1" level, and this signal is applied to one terminal of the AND circuits 65a and 65c of the gate signal generating circuit 6 in FIG. AND circuit 6
Since the pulse generated by the zero level detection circuit is supplied to the other terminal of 5a, 65c, when the pulse is supplied, the AND circuits 65a, 65c transmit a "1" level signal, and the flip-flops 66a, 65c. 66b is set and its Q
Both outputs are at "1" level.

The Q outputs of the flip-flops 66a, 66b of the gate signal generation circuit 6 are connected to the diodes 43u, 43 of the heater energization time control circuit 4.
t, so that the third
A voltage is generated across the resistor 43i shown in the figure. Since this voltage is supplied to the inverting input terminal of the differential amplifier 43r, the differential amplifier 43r shifts the level of the triangular wave supplied to the non-inverting input terminal and outputs the triangular wave shown by the waveform a in FIG. . The characteristic d in FIG. 11 is the output of the three-minute timer 41.

As a result, the duration of the 20 KHz signal output from the inverter 63b of the gate signal generating circuit 6 gradually increases as the level of the 3-minute timer 41 changes, as described with reference to FIG. 9 (e). Then, from the AND circuit 65e in FIG.
Since the level signal is being sent, the 20 KHz signal output from the inverter 63b is the AND circuit 65i, diode 6
It is supplied to the transistor 68a via the 7b and the resistor 61f and turns on / off the transistor at about 20 KHz. Therefore, the gate signal is supplied to the thyristors 70a and 70b, and the thyristor turns on. As a result, the heater current is supplied to the heater 22 via the transformer 17. The output of the inverter 63b is the ninth
As shown in FIG. 7E, the duration is increased intermittently and as the time elapses. Since the primary winding of the transformer 17 of the thyristor that is turned on / off at this time is connected to the maximum tap, the heater current is correspondingly 7 ampere, and the current is shown in FIG. 12 (a).
Flow as shown in.

The period during which the heater current of 7 amperes flows gradually increases as described above, and eventually the continuous energization state occurs, so that the glass temperature eventually reaches the above-mentioned first temperature. As a result, the output level of the differential amplifier 40q shown in FIG. 3 has risen to a value corresponding to the temperature, and this is detected by the differential amplifier 44q, and the "1" level signal which has been transmitted so far has been detected. The signal is set to “0” level. This signal is supplied to the reset terminal R of the flip-flop 66a shown in FIG. 6, and resets the flip-flop. Therefore, the AND circuit 65e, which has been sending the "1" level until now, does not satisfy the AND condition. Instead, the AND circuit 65f satisfies the AND condition, so that the "1" level signal is sent from there. It is supplied to the AND circuits 65j and 65h.

On the other hand, as the output of the flip-flop 66a changes from the "1" level to the "0" level, the level of the triangular wave is shifted as shown by the waveform b in FIG. 11 as described above.
Therefore, the output waveform of the inverter 63b shown in FIG. 6 again outputs an intermittent signal as shown in FIG. 9 (d). On the other hand, the timers 52a and 52b shown in FIG.
Since the other one does not send the output when one is producing the output, the inverter 63a in FIG. 6 stops the signal shown in (e) as shown in FIG. 9 (f). During this period, a signal of about 20 KHz is transmitted, and this signal (f) has a shorter duration as time elapses, contrary to (e). Therefore, the AND circuit 65b and the AND circuit 65j alternately output a signal of 20 KHz, whereby the set of thyristors 70a and 70b and the set of thyristors 70c and 70d are alternately turned on. Since the set of thyristors 70c and 70d is connected to the one having the smaller number of primary windings of the transformer 17, the current supplied to the heater 22 is larger when the thyristor is on. , A current of 14 amps flows through the heater 22. At this time, AND circuit
The duration of the signal sent from 65j becomes longer with the passage of time, and the duration of the signal sent from the AND circuit 65h becomes shorter with the passage of time. As shown in (b). First
In FIG. 12 (b), a portion with a small amplitude is a portion where a current of 7 amps is flowing, and a portion with a large amplitude is a portion where a current of 14 amps is flowing.

When the current flowing through the heater is increased in this way, the window glass eventually reaches the second temperature, so that the flip-flop 66b shown in FIG. 6 is also reset. Therefore, the AND circuit 65f does not satisfy the AND condition, and instead the AND circuit 65g satisfies the AND condition.This time, the AND circuit 65k, 65l alternately outputs the signal of 20 KHz and the combination of the thyristors 70c, 70d. And the set of thyristors 70e and 70f are alternately turned on. These are connected to the heater 22 via the transformer 17.
Since a current of 14 amps and a current of 20 amps are alternately supplied to the heater, the current flowing through the heater 22 is as shown in FIG. 12 (c). In (c), the large amplitude portion is 20 amps, and the small amplitude portion is 14 amps.

As described above, even if phase control is performed in units of one wavelength, if the supplied current is changed stepwise, the voltage fluctuation is reduced and the flicker of the fluorescent lamp in the machine is eliminated.

However, the amplitude of the current must be switched between two circuits and the phase must be continuous, but phase mismatch easily occurs at the time of switching, in which case an excessive current flows, and the voltage fluctuation rate also becomes large. I will end up. Therefore, in order to eliminate this mismatch, a flip-flop 57, resistors 50d and 50e, capacitors 51d, diodes 55a and 55b, and an AND circuit 58 shown in FIG. 4 are provided, and at the time of switching the current value, the first 1 I am trying to follow the cycle with a slight delay. That is, when the flip-flop 57 is set, its output is delayed by the time determined by the resistor 50d and the capacitor 51d, and the AND circuit 58 is activated by the delay time. Further, the timer 52c is provided to slightly lengthen the duration of the waveform before the switching at the time of switching the waveform. This prevents overcurrent due to phase mismatch. Since a delay after the first cycle is unnecessary, the delay after the second cycle is prevented by the diode 55b.

The AC waveform output from the thyristor circuit is converted by the transformer 17 into a voltage required by the standard of the heater 22. At this time, a part of the winding of the transformer 17 is transferred to the transformer 91 of the heater current detection circuit 9. It's composed. Therefore, the current supplied to the heater 22 is picked up by the transformer 91, rectified by the diode 92 and supplied to the inverting input terminal of the differential amplifier 93. As described above, the differential amplifier 93 supplies the non-inverting input terminal with the reference voltage 94 which is slightly higher than the voltage supplied to the inverting input terminal by the maximum specified value of the heater current. When the heater current flows, an output signal of "0" level is transmitted. On the other hand, the output terminal 5e of the gate signal generation time control circuit 5 sends out a signal of "1" level during most of the period during which the heater current is supplied. When both the "0" level signals output from 9 are supplied to the AND circuit 15, the thyristor is turned on and the operation display lamp 23 is turned on to indicate that the heater current is being supplied to the heater 22. Let it.

The current output from the thyristor circuit 7 is passed through a part of the voltmeter 17 to the input terminal 8a of the overcurrent detection circuit 8.
Is supplied to. This current flows into the resistor 81a shown in FIG. 7 to generate an AC voltage having a magnitude corresponding to the current value flowing in the thyristor as shown in FIG. 13 (a), and the voltage is the difference shown in FIG. It is supplied to the inverting input terminal of the dynamic amplifier 84. If a bias of V / 2 is supplied to the non-inverting input terminal of the differential amplifier 84, a signal shown in FIG. However, if this is the case, the input waveform must be rectified. However, the differential amplifier
A close examination of the 84 standards shows that the inputs are guaranteed to operate above -0.3 volts (eg LM29
There is 04). When the non-inverting input terminal is grounded to form the circuit shown in FIG. 7 and a signal having an amplitude up to about minus 0.6 volt is supplied to the inverting input terminal as an input, a positive half-wave waveform having an amplitude V is output. . That is, the differential amplifier 84 simultaneously performs rectification and amplification.

The output of the differential amplifier 84 is smoothed by the resistor 81c and the capacitor 82b, and when the smoothed output becomes larger than the reference potential determined by the resistors 81f and 81e, the differential amplifier 85 sends out an output signal of "1" level. This "1" level signal is output terminal
It is output via 8b and 8c, and the input terminal 6g of the gate signal generation circuit 6 and the input terminal 10f of the sensor short detection circuit 10
Is supplied to. Therefore, the gate signal generating circuit 6 turns on the transistor 68d shown in FIG.
Since the bases of 8a to 68c are set to the ground potential, the gate signal is not supplied to all thyristors and the thyristors are turned off. On the other hand, in the sensor short detection circuit 10, the relay 16 is deenergized by the signal supplied to the input terminal 10f, and the contact 16a is opened.

When the window glass becomes overheated for some reason, the resistance value of the thermistor 24 increases. Since current is supplied to the thermistor from the heater energization time control circuit 4, when the window glass overheats, the voltage supplied to the non-inverting input terminal of the differential amplifier 11a in the overheat detection circuit 11 increases. When this voltage exceeds the reference voltage 11b, the differential amplifier 11a generates an output signal of "1" level, and this signal is inverted by the inverter 11c and supplied to the inverter 10d of the sensor short detection circuit 10. At this time, Also relay 16 is de-energized.

If the thermistor 24 short-circuits for any reason, the voltage supplied to the inverting input terminal of the differential amplifier 10a of the sensor short-circuit detection circuit 10 becomes smaller than the voltage supplied to the non-inverting input terminal. The dynamic amplifier 10a outputs a "1" level signal. Therefore, the relay 16 is de-energized, and the power supply to the thyristor circuit 7 is stopped.

Window glass overheats due to overcurrent,
Since it overheats when exposed to high temperature outside air, the overcurrent detection circuit also detects overheating of the window glass at this time. Therefore, in the present invention, the heater current is detected, and the overcurrent detection circuit does not operate when the heater current has a normal value. That is, the heater current detection circuit 9 shown in FIG. 1 sends a "1" level signal when the heater current is normal. Therefore, this "1" level signal is supplied to the inverting input terminal of the differential amplifier 11a of the overheat detection circuit 11. On the other hand, a current generated in the thermistor 24 is supplied to a non-inverting input terminal of the differential amplifier circuit. However, the voltage at the non-inverting input terminal is a voltage that changes according to the temperature of the window glass and is lower than the power supply voltage, but the voltage at the inverting input terminal is at the "1" level, so it is almost the same level as the power supply voltage. . From this, when the heater current value is equal to or lower than the normal value, the voltage of the inverting input terminal of the differential amplifier 11a is always higher and its output is at "0" level. Therefore, the inverter 11c outputs a "1" level signal and does not affect the operation of the sensor short detection circuit 10, that is, the operation of the relay 16.

However, when an overcurrent flows through the heater 22, the heater current detection circuit 9 sends a "0" level signal, so this output signal does not affect the overheat detection circuit 11. For this reason, the overheat detection circuit 11 is
The voltage generated at 24 is detected, and when the value is equal to or higher than the allowable value, the sensor short detection circuit 10 is driven, and the relay 16 is deactivated by this, so that no current is supplied to the heater 22, Prevent window glass from overheating. Further, at this time, since the AND condition of the AND circuit 15 is also satisfied, the lamp 23 is turned on, and the abnormality is notified.

When the power is turned on, the switch 20 is turned on by the timer 41 shown in FIG.
Since the output voltage of the (3 minute timer) is saturated, the temperature control state by the thermistor 24 can be checked at the same time when the power is turned on.

The switch 21 is a switch that simulates an overheat state.

In the above embodiment, the heating circuit for the heater of the glass window of the cockpit has been described. However, the present invention is not limited to this and can be generally used for performing variable control of AC power.

〔The invention's effect〕

As described above, the present invention has the effect that the thyristor can be reliably turned on even under normal environmental conditions because the signal is repeatedly supplied to the gate of the thyristor, and the economy is improved.

[Brief description of drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a zero level detection circuit, FIG. 3 is a circuit diagram showing a heater energization time control circuit, and FIG. 4 is a gate signal generation time. FIG. 5 is a circuit diagram showing a control circuit, FIG. 5 is a circuit diagram showing a thyristor circuit, FIG. 6 is a circuit diagram showing a gate signal generating circuit, FIG. 7 is a circuit diagram showing an overcurrent detection circuit, and FIG. 8 is a gate. Waveforms of respective parts for explaining the signal generation state, FIG. 9 is a waveform diagram of each part for explaining the operating state of the thyristor at the time of power-on, and FIG. 10 is a waveform diagram showing the energized state of the thyristor, 11 Figure is a graph showing the generation state of the comparison signal with the temperature of the controlled object, FIG. 12 is a graph showing the waveform of the radio wave supplied to the heater, FIG. 13 is for explaining the operation of the overcurrent detection circuit It is a waveform diagram. 3 ... Zero level detection circuit, 4 ... Heater energization time control circuit, 5 ... Gate signal generation time control circuit, 6 ... Gate signal generation circuit, 7 ... Thyristor circuit, 8 ... Overcurrent detection circuit, 9: Heater current detection circuit, 10
…… Sensor short detection circuit, 11 …… Overheat detection circuit.

Claims (1)

[Claims] 1. An AC power control device for heating a glass by intermittently or continuously supplying an AC power to a heater mounted on a window glass of an aircraft, the temperature of a glass detected by a temperature sensor is increased. The output signal level of the amplifier circuit (40) whose output signal level is lowered, and a signal of a level lower than the output signal level of the amplifier circuit is output for a predetermined period after the power is turned on and the level monotonically increases immediately after the power is turned on. A timer (41) for generating a signal whose level is saturated after a period of time, and a diode (41t) having an anode connected to the output side of the amplifier circuit and a cathode connected to the output side of the timer.
An oscillator (43) for generating a sawtooth wave having a period sufficiently longer than the period of the AC signal; and the amplifier circuit output signal being at a first level other than zero and at a second level higher than the first level. A level judgment circuit (44) for detecting and transmitting an output signal corresponding to each level, and a level shift means (43) for level-shifting the oscillator output signal level according to the judgment level of the level judgment circuit.
i, 43j, 43k, 43l, 43t, 43u), and a comparison unit (42) for sending an output signal when the amplifier circuit output signal level is higher than the oscillator output signal level.
, And the first to third power supplies (69a, 69b, 69)
c), and sending a first selection signal for selecting a power source having a small power and a power source closest to the power and having a larger power than the power by the output signal of the level determination circuit,
Selection means (64a, 64b, 63c, 63d, 65) for transmitting a second selection signal for selecting the level shift amount of the level shift means.
a to 65d, 66a, 66b, 65e to 65l) and energization time ratio determining means (5) for determining the energization time ratio of the power source selected by the comparison unit output signal. Control device.