JPH01108611A - Temperature controller - Google Patents

Abstract

PURPOSE:To prevent a load side from being overhead due to the breakdown in a reverse direction of a thyristor by detecting the breakdown of the thyristor on the middle way immediately when it occurs, and stopping the operation of a device. CONSTITUTION:It is detected whether or not the breakdown in the reverse direction of the thyristor is generated at a position a little before the zero cross point of an AC voltage to be impressed on the thyristor 17. Since a temperature fuse 168 is melted compulsorily by turning ON the thyristor 166 when the breakdown in the reverse direction is detected, the fact that the breakdown of the thyristor 17 is generated on the middle way can be detected immediately, and the operation of the device is stopped. In such a way, it is possible to prevent overheat due to the breakdown in the reverse direction of the thyristor 17 from being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a temperature control device for controlling the temperature of electric blankets, electric carpets, electric floor heaters, and the like.

(Prior Art) Conventionally, in heating appliances such as electric blankets, the blanket body and a controller (temperature control device) are connected by a cable or the like, and the temperature control device controls the heating wires provided inside the blanket body. Many of them are designed to control the temperature of the blanket itself by controlling the amount of heat generated.

FIG. 8 is a block diagram showing such an electric blanket and a temperature control device for controlling the temperature of this electric blanket.

The temperature control device shown in this figure includes a sensor temperature detection circuit 1, a temperature setting circuit 2, a zero cross signal generation circuit 3, a sampling circuit 4, a comparison circuit 5, a drive circuit 9, a thyristor 6, and a stop circuit 8. It is equipped with an electric blanket with 7
The value of the temperature detection signal output from the temperature sensor 7a placed in the electric blanket 7a is compared with the set temperature set in the temperature setting circuit 2, and based on the comparison result, the heater wires placed in the electric blanket 7 are electric blanket 7 by controlling the amount of current flowing through 7b
control the temperature of the

The sensor temperature detection circuit 1 takes in a temperature detection signal output from a temperature sensor 7a provided in the electric blanket 7,
This is supplied to the comparator circuit 5 as a temperature detection signal S1.

Further, the temperature setting circuit 2 generates a temperature setting signal S2 having a value corresponding to a preset temperature setting value, and supplies this to the sampling circuit 4.

Further, the zero cross signal generation circuit 3 includes the heater wire 7b.
It is configured to take in the AC voltage of an AC commercial power supply 10 that supplies power to the circuit and detect its zero-crossing point, and when the zero-crossing point is detected, it generates a zero-crossing signal S3 and supplies it to the sampling circuit 4. do.

The sampling circuit 4 keeps its output terminal voltage in a latch-up state when the zero-crossing signal S3 is not supplied. When the zero cross signal S3 is supplied, the temperature setting signal S2 outputted from the temperature setting circuit 2 is taken in and supplied to the comparison circuit 5.

The comparison circuit 5 compares the value of the temperature setting signal S2 outputted from the sampling circuit 4 with the value of the temperature detection signal S1 outputted from the sensor temperature detection circuit 1, and calculates S1.
．． >82, that is, when the temperature of the electric blanket 7 is lower than the temperature set by the temperature setting circuit 2, a drive signal is generated and supplied to the drive circuit 9.

When the drive circuit 9 is supplied with the drive signal, it generates a trigger signal S4 and supplies this to the gate of the cyrisk 6.

As a result, this thyristor 6 becomes conductive, and one end 10a of the AC commercial power supply 10 → the heater wire 7b → the anode of the thyristor 6, the cathode of the thyristor 6 → the AC commercial power supply 10
A current flows through the heater wire 7b through the narrow end 10b of the heater wire 7b, and the temperature of the electric blanket 7 rises.

When the thyristor 6 causes reverse breakdown, the stop circuit 8 detects this and blows out the temperature fuse 8C to stop the operation of the device.

(Problems to be Solved by the Invention) By the way, in the stop circuit 8 in such a conventional temperature control device, when the thyristor 6 causes reverse breakdown, the diode 8a becomes conductive and the resistor 8b
Electric current flows through and generates heat, which causes temperature fuse 8.
Since AC is melted down, the thyristor 6 breaks down midway as shown in FIG. 9(B) while AC voltage is being output from the AC commercial type m10 as shown in FIG. 9(A). There was a problem in that when the temperature fuse 8C was ignited, the amount of current flowing through the resistor 8b was too small and it took too long for the temperature fuse 8C to blow out.

In view of the above circumstances, the present invention is capable of immediately detecting when a thyristor breaks down midway through and stopping the device operation, thereby reducing the load caused by the reverse breakdown of the thyristor. The object of the present invention is to provide a temperature control device that can prevent side heating.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, a temperature control device according to the present invention uses a temperature detection signal outputted from a temperature sensor and a temperature setting section set to A periodic pulse is applied to the temperature control device that controls the heat generation amount of the heater by performing on/off control using thyristor based on the comparison result with the set temperature of the thyristor. A pulse generating section that generates a pulse, a determining section that determines whether or not this thyristor has caused reverse breakdown based on the reverse voltage of the thyristor when a periodic pulse is output from the pulse generating section, and this determination. The present invention further includes a stop section that stops the circuit operation when the thyristor is determined to have reverse breakdown by the section.

(Function) In the temperature control device according to the present invention, in the above configuration, when a periodic pulse is output from the pulse generation section, the determination section determines whether or not the thyristor has caused reverse breakdown, and the thyristor When it is determined that the reverse breakdown has occurred, the stop section stops the circuit operation.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of a temperature control device according to the present invention.

The temperature control device shown in this figure includes a sensor temperature detection circuit 11
, a temperature setting circuit 12, a pulse signal generation circuit 13,
Sampling circuit 14, comparison circuit 15, and drive circuit 1
6, a thyristor 17, and a stop circuit 160, the temperature sensor 1 is disposed inside the electric blanket 18 before the zero-crossing point of the AC voltage applied by the thyristor
The value of the temperature detection signal from 9 is compared with the set temperature set in the temperature setting circuit 12, and on/off of the thyristor 17 is determined based on the comparison result.

As a result, when the thyristor 17 is turned on, current begins to flow at the zero-crossing point of the AC voltage.

Further, it is determined whether the thyristor 17 is causing reverse breakdown before the zero-crossing point of the AC voltage, and if the thyristor 17 is causing reverse breakdown, the operation of the device is stopped.

The sensor temperature detection circuit 11 takes in a temperature detection signal output from a temperature sensor 19 provided in the electric blanket 18, and supplies it to the comparison circuit 15 as a temperature detection signal S10. In this case, if the temperature of the electric blanket 18 decreases,
Correspondingly, the value of the temperature detection signal S10 increases.

Further, the temperature setting circuit 12 includes a setting device such as a variable resistor, generates a temperature setting signal S11 having a value corresponding to the temperature setting value set in this setting device, and sends this to the sampling circuit 14. supply

The pulse signal generation circuit 13 also includes a current limiting resistor 21, a first pulse generator 22, and a second pulse generator 2.
3 and a zero-crossing period detection circuit 24, which takes in the AC voltage of the AC commercial power supply 25 that supplies power to the heater wire 20, and generates a first periodic pulse signal 312 before and after the zero-crossing point of this AC voltage. A second periodic pulse signal S13 is generated, respectively. - The first pulse generator 22 includes diodes 26a and 26b for voltage value limitation, a first negative voltage detection circuit 27, a second negative voltage detection circuit 28, and a first gate circuit 37, as shown in FIG. A little before the AC voltage applied to the thyristor 17 changes from negative to positive, it generates a first periodic pulse signal 812 and supplies it to the sampling circuit 1.4.

The first negative voltage detection circuit 27 includes the diodes 26a, 2
Three transistors 29.30.31 that turn on when a forward voltage greater than the value Vb1 is applied to 6b
and five resistors 32 to 36 that serve as current paths for each of these transistors 29, 30, and 31, as shown in FIG.
As shown in A), the polarity of the AC voltage output from the AC commercial power supply 25 becomes negative, and in response to this, the diode 2
When a forward voltage larger than the value Vb1 is applied to 6a and 26b, a negative voltage detection signal S30 as shown in FIG. 3(B) is generated and supplied to the first gate circuit 37.

Further, the second negative voltage detection circuit 28, like the first negative voltage detection circuit 27, includes the diode 26a.

Three transistors 38°39.40 that turn on when a forward voltage greater than the value Vb2 is applied to 26b
and five resistors 41 to 45 that serve as current paths for each of these transistors 38.39° 40, and the polarity of the AC voltage output from the AC commercial type [25 becomes negative, and and the value V is applied to the diodes 26a and 26b.
When a forward voltage larger than b2 is applied, a negative voltage detection signal S31 as shown in FIG. 3(C) is generated and supplied to the first gate circuit 37. Note that here, the value Vb2 and the value Vb1 are the values of the diode 2 connected in series.
The forward conduction voltage of 6a and 26b is set to be smaller than 2VF. Further, the value of the resistor 32 provided in the first negative voltage detection circuit 27 is equal to the value of the resistor 32 provided in the first negative voltage detection circuit 27.
The value of the resistor 41 provided at the resistor 8 is set to be larger than the value of the resistor 41 provided at the resistor 8, so that 1Vb21>1Vb11.

Further, the first gate circuit 37 receives the negative voltage detection signal S30.
an inverter 46 that inverts the output of the inverter 46, the negative voltage detection signal 831, and the zero cross period signal 5.
32 (see (F) in FIG. 3) and an AND gate 47 which performs a logical product with the negative voltage detection signal S30, the negative voltage detection signal 831, and the zero cross period signal S32.
The first periodic pulse signal S shown in FIG. 3(G) is based on
Generate 12.

Further, the second pulse generator 23 includes diodes 48a and 48b for voltage value limitation, a first positive voltage detection circuit 49, a second positive voltage detection circuit 50, and a second gate circuit 51. A little later after the AC voltage applied to the thyristor 17 changes from negative to positive, a second periodic pulse signal S13 is generated and supplied to the drive circuit 16.

The first positive voltage detection circuit 49 includes the diode 48a,
Two transistors 52.53 are turned on when a forward voltage larger than the value Vb3 is applied to 48b, and three resistors 54, 55.56 serve as current paths for each of these transistors 52.53. Then, as shown in FIG. 3(A), the polarity of the AC voltage output from the AC commercial N source 25 becomes positive, and correspondingly, the diode 4'8a
, 48b, a positive voltage detection signal S33 as shown in FIG. 3(D) is generated and supplied to the second gate circuit 51. Further, the second positive voltage detection circuit 50 includes the first positive voltage detection circuit 4
9, the value Vb is applied to the diodes 48a and 48b.
Two transistors 57, 58 that turn on when a forward voltage greater than 4 is applied, and three resistors 59, 60 that form a current path for each of these transistors 57, 58.
．． 61, when the polarity of the AC voltage output from the AC commercial power supply 25 becomes positive and a forward voltage larger than the value Vb4 is applied to the □ diodes 26a and 26b correspondingly. A positive voltage detection signal 834 as shown in FIG. 3(E) is generated and supplied to the second gate circuit 51. Note that here, the value Vb4 and the value Vb
3 is set smaller than the forward conduction voltage 2VF of the diodes 48a and 48b- connected in series. In addition, a resistor 5 provided in the first positive voltage detection circuit 49
The value of 4 is set larger than the value of the resistor 59 provided in the second positive voltage detection circuit 51.
Vb 41 > l Vb 31.

Further, the second gate circuit 51 receives the positive voltage detection signal 833.
an inverter 62 that inverts the output of the inverter 62, the positive voltage detection signal S34, and the zero cross period signal 8.
32, and an AND gate 63 that takes a logical AND with S32, and the positive voltage detection signal 833 and the positive voltage detection signal S34
3 (H
) generates a second periodic pulse signal 313 shown in FIG.

In addition, the zero-crossing period detection circuit 24 detects when the power switch is turned on and sends a reset signal S.
3'5, an inverter 65 for inverting the positive voltage detection signal S34, an OR gate 66 for logically ORing the output of the inverter 65 and the reset signal 835, and the second negative voltage detection When the circuit 28 stops outputting the negative voltage detection signal $31, it takes in the output of the first positive voltage detection circuit 49 and latches it, and then when the reset signal @836 is supplied from the OR gate 66, the output of the first positive voltage detection circuit 49 is latched. It also includes a D-type flip-flop 67 for clearing the latch result. Then, each time the second negative voltage detection circuit 28 stops outputting the negative voltage detection signal S31, it takes in the output of the first positive voltage detection circuit 49 and latches it, as shown in FIG. 3(F). Zero cross period signal 3
32, which is connected to the first gate circuit 37 and the second gate circuit 37.
It is supplied to the gate circuit 51.

In this way, this pulse signal generation circuit 13 generates the first periodic pulse signal S12 and the second periodic pulse signal S13 before and after the point at which the AC voltage output from the AC commercial type [25 changes from negative to positive. is generated, and this is sent to sampling circuit 1.
4 and the drive circuit 16, respectively.

The sampling circuit 14 receives the first periodic pulse signal 81
2, a transistor 71 that turns on when the inverter 69 outputs an LL, I II signal, a resistor 70 that limits the base current of the transistor 71, and a resistor 70 that divides the output of the transistor 71. resistors 72, 73 and these resistors 72.7
3, and a resistor 75 that limits the output current value of the temperature setting circuit 12.
12 is not supplied, its output terminal voltage is held at the power supply voltage Vcc. In this state, when the first periodic pulse signal S12 is supplied, the temperature setting signal S11 outputted from the temperature setting circuit 2 is taken in and supplied to the comparison circuit 15.

The comparison circuit 15 has the output of the sampling circuit 14;
It is equipped with an operational amplifier 76 that compares the value of the temperature detection signal S10 outputted from the sensor temperature detection circuit 1, and the sampling circuit 14 converts the output terminal voltage into the power supply voltage Vc.
When it is held at C, its output terminal is set to 'Lo' level.

Then, a temperature setting signal 8 is sent from this sampling circuit 14.
11 is output, the value of this temperature setting signal 811 is compared with the value of the temperature detection signal 810 output from the sensor temperature detection circuit 1, and when S10>811, that is, the temperature of the electric blanket 18 is As soon as the temperature is lower than the temperature set by the temperature setting circuit 12, the heater on signal 8 is activated.
14 and supplies it to the drive circuit 16.

The circuit 16 is set when the heater-on signal S14 is supplied, and thereafter the second periodic pulse signal S
When the R8 type Noritsubu flop 80 is reset when 13 is supplied, and the set output terminal of this R3 type flip-flop 80 is at the "'L0" level, it is charged and becomes the LL Hi l' level. It includes a capacitor 82 that discharges at times, a resistor 81 that determines the charging/discharging time constant of the capacitor 82, and a resistor 83 that converts the current discharged from the capacitor 82 into voltage and generates a trigger signal S15. and the heater on signal S
14 is supplied, the charge stored in the capacitor 82 generates a trigger signal S15 to trigger the thyristor 17.
conduction. Thereafter, when the second periodic pulse signal 813 is supplied, generation of the trigger signal 815 is stopped and the capacitor 82 is caused to perform a charging operation.

The stop circuit 160 also includes a voltage detection circuit 162, an AND gate 163, a drive circuit 165, and a thyristor 166.
, a resistor 167, and a temperature fuse 168, and when the thyristor 17 causes reverse breakdown, this is detected and the operation of the device is stopped.

As shown in FIG. 4, the voltage detection circuit 162 includes a transistor 180 that turns on when the voltage between the seven nodes and the cathode of the thyristor 17 exceeds a predetermined voltage in the opposite direction, and a diode 181 that protects the transistor 180.
a to 181d, a transistor 182 that is turned on when the transistor 180 is turned on, and a resistor 183 that becomes a current path for these transistors 180 and 183. ．．
184 and 185, and generates the rt LO++ voltage when the voltage between the anode and cathode of the thyristor 17 exceeds a predetermined voltage in the reverse direction, and otherwise generates the II Fl i 11 voltage. These voltages are supplied to the AND gate 163.

The AND gate 163 is configured to logically multiply the output of the voltage detection circuit 162 and the output of the first pulse generator 22, and outputs the first periodic pulse signal S12 from the first pulse generator 22. is output, and if the voltage detecting circuit 162 outputs a voltage of "+-+r", it generates a reverse break detection signal 816 indicating that the thyristor 17 has caused a reverse breakdown. The signal is supplied to the starting circuit 165.

The drive circuit 165 includes an R8 type flip-flop 164 which is set when the reverse break detection signal 816 is supplied and then reset when the second periodic pulse signal 813 is supplied, and this R8 type flip-flop. A capacitor 169 is charged when the set output terminal 164 is at the 'lo' level and discharged when the set output terminal reaches the '#Hi'l level, and this capacitor 169
and a resistor 171 that converts the current discharged from the capacitor 169 into a voltage and generates a trigger signal 817, and is supplied with the reverse break detection signal S16. When the trigger signal 817 is generated by the electric charge stored in the capacitor 169,
is generated and supplied to the gate of the thyristor 166. As a result, when a forward voltage is applied to the thyristor 166, the thyristor 166 becomes conductive.
The resistor 167 is made to generate heat. And this resistor 167
The temperature fuse 168 is blown by the heat, and all circuit operations are stopped.

Next, the operation of this embodiment will be explained with reference to the waveform diagrams shown in FIGS. 5(A) to 5(H).

First, as shown in FIG. 5(A), just before the AC voltage output from the AC commercial power supply 10 changes from negative to positive (for example,
At time t1), the first pulse generating circuit 22 detects this and generates a first periodic pulse signal 812 as shown in FIG. 4(B), thereby causing the sampling circuit 14 to select the output of the temperature setting circuit 12.

As a result, the operational amplifier 76 constituting the comparator circuit 15
As shown in FIG. 5(D), a temperature setting signal S11 from the temperature setting circuit 12 and a temperature detection signal S10 from the sensor temperature detection circuit 11 are supplied to each input terminal of the sensor.

Here, if the temperature of the electric blanket 18 is lower than the temperature set by the temperature setting circuit 12, and correspondingly 810>311, the comparison will be made as shown in FIG. 5(E). The circuit 15 generates the heater-on signal S14, causes the drive circuit 16 to output a trigger signal 815, and supplies this to the gate of the thyristor 17, as shown in FIG. 5(F).

As a result, when a forward voltage is applied between the anode and cathode of this thyristor 17, this thyristor 17 becomes conductive as shown in FIG.
While a forward voltage is applied to the heater wire 7, a driving current flows through the heater wire 20 as shown in FIG. 5(G).

Furthermore, if a little time has passed since the AC voltage output from the AC commercial power supply 10 changes from negative to positive (for example, time t2
), the second pulse generating circuit 23 detects this, and the second pulse generating circuit 23 detects this, and as shown in FIG.
Generate a second periodic pulse signal 813 as shown in C),
This is supplied to the drive circuit 16.

As a result, the drive circuit 16 stops generating the trigger signal S15 and returns to the initial state.

Also, during this operation, the thyristor 17 causes reverse breakdown as shown in FIG. 6(B), and as shown in FIG.
When a reverse current flows through the heater wire 20 as shown in A), the voltage detection circuit 162 detects this and outputs a voltage as shown in FIG. 6C.

As a result, from when the first pulse generator 22 outputs the first period pulse signal S12 as shown in FIG. 6(D), the second pulse generator 23 outputs the second period pulse signal S12 as shown in FIG. 6(E). FIG. 6(F) until the pulse signal S13 is output.
As shown in , the AND gate 163 outputs the reverse break detection signal S.
16 is generated and supplied to the gate of thyristor 166.

As a result, when a forward voltage is applied to this thyristor 166, this thyristor 166 becomes conductive, and the resistor 1
A current flows through 67. The heat generated by this resistor 167 blows out the temperature fuse 168, stopping the operation of the entire device.

In this way, in this embodiment, it is detected whether or not the thyristor 17 is causing reverse breakdown slightly before the zero-crossing point of the AC voltage applied to the thyristor 17, and when reverse breakdown is detected, , the thyristor 166 is turned on to forcibly blow out the temperature fuse 168, so the thyristor 17
Even if a breakdown occurs midway through, this can be detected immediately and the device operation can be stopped.

This can prevent overheating of the electric blanket 18 due to reverse breakdown of the thyristor 17.

Furthermore, in each of the above-mentioned embodiments ('S-), the pulse signal generating circuit 13 is constituted by discrete components, but as shown in FIG. 141, the polarity of this voltage division result is detected by a comparator circuit 142, and based on this detection result, the microcomputer 143 detects the zero-crossing point of the AC voltage output from the AC commercial power supply 25, The first and second periodic pulse signals S12 and S13 may be generated.In this case, these first and second periodic pulse signals S12 and S13 may be generated with an accuracy corresponding to the frequency of the crystal oscillator 144 that supplies the clock signal to the microcomputer. The generation timing of the second periodic pulse signal S1.813 can be controlled.

Further, in each of the embodiments described above, the trigger signal S15 is generated by the charging/discharging operation of the capacitor 82, but even if a pulse transformer is provided in place of the capacitor 82, the same effect as in each of the embodiments described above can be obtained. Obtainable.

Furthermore, in each of the embodiments described above, the thyristor 17 is used to energize the heater wire 20, but the thyristor 17 may be replaced with a bidirectional switching element such as a triac. In this case as well, the first . Second periodic pulse signal S12. If S13 is caused to occur in each case, the same effects as in each of the above-described embodiments can be obtained.

Further, in each of the embodiments described above, the present invention has been explained by taking as an example the electric blanket 18 in which the heater wire 20 and the temperature sensor 19 are separated. Even when the thyristor and the thyristor are integrated, reverse breakdown of the thyristor can be similarly detected and the circuit operation can be stopped.

[Effects of the Invention] As explained above, according to the present invention, when a thyristor breaks down midway through, it is possible to immediately detect this and stop the device operation, thereby preventing reverse breakdown of the thyristor. It is possible to prevent overheating on the load side caused by

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the temperature control device according to the present invention, FIG. 2 is a circuit diagram showing a specific example of the pulse signal generating circuit shown in FIG. 1, and FIG. 3 is a block diagram showing a specific example of the pulse signal generating circuit shown in FIG. 4 is a circuit diagram showing a specific example of the voltage detection circuit shown in FIG. 1, FIG. 5 is a waveform diagram showing an example of the operation of this embodiment, and FIG. 6 is a waveform diagram of this embodiment. A waveform diagram showing an example of operation; FIG. 7 is a circuit diagram showing an example of a pulse signal generating circuit that can be used in the temperature control device according to the present invention;
FIG. 8 is a block diagram, not showing a conventional temperature control device, and FIG. 9 is a waveform diagram for explaining the operation of this temperature control device. 12...Temperature setting section (temperature setting circuit) 17...Thyristor 19...Temperature sensor 22...Pulse generation section (first pulse generator) 163...Judgment section (and goo) 166. ... Stop part (1 noise risk) 168 ... Temperature fuse

Claims (1)

[Claims] The temperature detection signal output from the temperature sensor is compared with the set temperature set in the temperature setting section, and based on the comparison result, on/off control is performed by the thyristor to control the amount of heat generated by the heater. The temperature control device includes a pulse generator that generates a periodic pulse before a zero-crossing point of an alternating current voltage applied to the thyristor; a determination unit that determines whether or not the thyristor is causing reverse breakdown based on the determination unit; and a stop that stops circuit operation when the determination unit determines that the thyristor is causing reverse breakdown. A temperature control device comprising: