Temperature control circuit capable of keeping temperature unchanged in wide AC input voltage range

Abstract

The utility model provides a temperature control circuit capable of keeping temperature unchanged in a wide AC input voltage range, which comprises a controller and a blanket body. The controller comprises an AC power supply input module, a main control module, a commercial power partial voltage acquisition module, a 5V voltage stabilization module, an EMI circuit module, a zero-crossing signal input module, a controller over-temperature protection circuit module, a heating drive circuit module, a display and key control unit module, a silicon controlled rectifier short circuit, open circuit and heating wire open circuit detection module, and a PTC sampling temperature control module. The device comprises an NTC temperature detection module, an NTC broken line detection module, a contact pin H1, a contact pin H2, a contact pin H3 and a contact pin H4. One end of the commercial power partial voltage acquisition module is connected with the AC power supply input module, and the other end is connected with the master control module.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, and particularly relates to a temperature control circuit with a wide AC input voltage range and constant temperature. Background Technique

[0002] In traditional electric heating products, the method of controlling temperature only reads the PTC resistance value signal data of the heating wire to judge the temperature of the heating wire, and there is no control over the change of the grid voltage. The changes in the peak and trough periods of the grid voltage have the following impacts on electric heating products:

[0003] When the grid voltage is high at the low peak: When the grid voltage is high, the electric heating product may generate overheating, increasing the risk of scalding, especially for some electric heating products with strong contact, such as electric blankets; and it affects the product life. Using electric heating products under high voltage for a long time may shorten the product life and increase the risk of failure;

[0004] When the grid voltage is low at the peak: When the grid voltage is low, the heating temperature of the electric heating product may drop, resulting in a low heating temperature and poor heating effect, affecting the use effect and performance of the product.

[0005] Therefore, there is an urgent need for a temperature control circuit with a wide AC input voltage range and constant temperature to solve the above technical problems. Summary of the Utility Model

[0006] (1) Technical Problems to be Solved

[0007] In view of the deficiencies of the prior art, the utility model provides a temperature control circuit with a wide AC input voltage range and constant temperature, which solves the problems that the performance of electric heating products is affected or there is a risk of overheating and scalding due to the changes in the peak and trough periods of the grid voltage as mentioned in the above background technique.

[0008] (2) Technical Solutions

[0009] To achieve the above object, the utility model is realized through the following technical solutions:

[0010] An embodiment of the utility model provides a temperature control circuit with a wide AC input voltage range and constant temperature, including a controller and a blanket body, and the blanket body includes: a heating wire;

[0011] The controller includes: an AC power input module, a main control module, a mains voltage dividing and acquisition module, a 5V voltage stabilizing module, an EMI circuit module, a zero-crossing signal input module, a controller over-temperature protection circuit module, a heating drive circuit module, a display and button control unit module, a thyristor short-circuit, open-circuit, and heating wire open-circuit detection module, a PTC sampling temperature control module, an NTC temperature detection module, an NTC open-circuit detection module, and connection pins H1, H2, H3, and H4;

[0012] One end of the mains voltage dividing and acquisition module is connected to the AC power input module, and the other end is connected to the main control module;

[0013] The mains voltage dividing and acquisition module includes: resistors R1, R8, R13, R131, R132, and R133. One end of resistor R1 is connected to the input end of the AC power input module, and the other end is connected in series with resistor R8. Resistor R133 is connected in parallel with R13 and is connected in series with the series circuit of resistors R1 and R8;

[0014] Resistor R131 is connected in parallel with resistor R132 and is connected in series with the series circuit of resistor R133 and R13 in parallel.

[0015] Preferably, the L terminal of the AC power input module is grounded, and the N terminal is connected to the EMI module through fuse F1;

[0016] The EMI module is connected to the zero-crossing detection module and the 5V voltage stabilizing circuit;

[0017] The zero-crossing detection module includes resistors R4 and R5. Resistors R4 and R5 are connected in series to generate a zero-crossing signal and input it to the main control module.

[0018] Preferably, the display module is connected to the main control module to execute display indication drive output, and the button module is connected to the main control module to execute button signal input.

[0019] Preferably, the controller over-temperature protection circuit module includes: an NTC1 thermistor and a resistor R18 connected in series. One end of the NTC1 thermistor is connected to the +5V VCC power supply, and the resistor R18 is grounded.

[0020] Preferably, the controller is connected to the heating wire of the blanket body through connection pins H1, H2, H3, and H4.

[0021] Preferably, the thyristor short-circuit, open-circuit, heating wire open-circuit detection module, PTC sampling temperature control module, NTC temperature detection module, and NTC open-circuit detection module are connected to the main control module.

[0022] Preferably, the PTC sampling temperature control module is connected to the heating drive circuit module, and is connected in series with the parallel connection circuit of resistor R311 and R31 and grounded.

[0023] Preferably, the NTC temperature detection module is connected to and grounded through capacitor C12, and the NTC open circuit detection module is connected to and grounded through capacitor C13; the NTC temperature detection module is connected to the blanket heating wire through the plug pin H2; the NTC open circuit detection module is connected to the blanket heating wire through the plug pin H2.

[0024] The present invention also provides an electric blanket, which is made based on a temperature control circuit for maintaining a constant temperature within a wide AC input voltage range as described in any one of the foregoing.

[0025] (III) Beneficial effects

[0026] The present invention provides a temperature control circuit for maintaining a constant temperature within a wide AC input voltage range. It has the following beneficial effects:

[0027] Based on the temperature control circuit for maintaining a constant temperature within a wide AC input voltage range of the present invention, a mains voltage division detection signal is combined with the PTC resistance feedback signal of the heating wire. After the main control module reads the relative value of the two and compares it with the previously set value to control the temperature of the product. When any one of the two signals changes, the value read by the main control module also changes accordingly, so as to achieve real-time control of the temperature of the heating product when the grid voltage changes and the PTC resistance of the heating wire changes. Description of the drawings

[0028] Figure 1 It is a functional block diagram of a temperature control circuit for maintaining a constant temperature within a wide AC input voltage range provided by an embodiment of the present invention;

[0029] Figure 2 It is a circuit diagram of a temperature control circuit for maintaining a constant temperature within a wide AC input voltage range provided by an embodiment of the present invention. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention.

[0031] As Figure 1 shown, an embodiment of the present invention provides a temperature control circuit for maintaining a constant temperature within a wide AC input voltage range, including a controller and a blanket body, and the blanket body includes: a heating wire;

[0032] The controller includes: an AC power input module, a main control module, a mains voltage dividing and sampling module, a 5V voltage stabilizing module, an EMI circuit module, a zero-crossing signal input module, a controller over-temperature protection circuit module, a heating drive circuit module, a display and button control unit module, a thyristor short-circuit, open-circuit, and heating wire open-circuit detection module, a PTC sampling temperature control module, an NTC temperature detection module, an NTC open-circuit detection module, and plug pins H1, H2, H3, and H4;

[0033] One end of the mains voltage dividing and sampling module is connected to the AC power input module, and the other end is connected to the main control module;

[0034] The mains voltage dividing and sampling module includes: resistors R1, R8, R13, R131, R132, and R133. One end of resistor R1 is connected to the input end of the AC power input module, and the other end is connected in series with resistor R8. Resistor R133 is connected in parallel with R13 and is connected in series with the series circuit of resistors R1 and R8;

[0035] Resistor R131 is connected in parallel with resistor R132 and is connected in series with the circuit in which resistor R133 is connected in parallel with R13.

[0036] Preferably, the L terminal of the AC power input module is grounded, and the N terminal is connected to the EMI module through fuse F1;

[0037] The EMI module is connected to the zero-crossing detection module and the 5V voltage stabilizing circuit;

[0038] The zero-crossing detection module includes resistors R4 and R5. Resistors R4 and R5 are connected in series to generate a zero-crossing signal and input it to the main control module.

[0039] Preferably, the display module is connected to the main control module to execute display indication drive output, and the button module is connected to the main control module to execute button signal input.

[0040] Preferably, the controller over-temperature protection circuit module includes: an NTC1 thermistor and a resistor R18 connected in series. One end of the NTC1 thermistor is connected to the +5V VCC power supply, and the resistor R18 is grounded.

[0041] Preferably, the controller is connected to the heating wire of the blanket through plug pins H1, H2, H3, and H4.

[0042] Preferably, the thyristor short-circuit, open-circuit, heating wire open-circuit detection module, PTC sampling temperature control module, NTC temperature detection module, and NTC open-circuit detection module are connected to the main control module.

[0043] Preferably, the PTC sampling temperature control module is connected to the heating drive circuit module, and is connected in series with the parallel connection circuit of resistor R311 and R31 and grounded.

[0044] Preferably, the NTC temperature detection module is connected to and grounded through capacitor C12, and the NTC open circuit detection module is connected to and grounded through capacitor C13; the NTC temperature detection module is connected to the blanket heating wire through the plug pin H2; the NTC open circuit detection module is connected to the blanket heating wire through the plug pin H2.

[0045] The present utility model further provides an electric blanket, which is made based on the temperature control circuit for maintaining a constant temperature within a wide AC input voltage range as described in any one of the foregoing.

[0046] As Figure 2 shown is the circuit diagram of a temperature control circuit for maintaining a constant temperature within a wide AC input voltage range provided by an embodiment of the present utility model.

[0047] Working principle: The 1st pin of the main control circuit U1 is the VCC power supply pin. The 2nd pin is the temperature monitoring pin of the control system. The 3rd pin is for LED indication drive. The 4th pin is the ICSPCLK communication pin. The 5th pin is the ICSPDAT communication pin and the external key command input pin, the 6th pin is the LED indication drive pin. The 7th pin is the LED indication drive pin. The 8th pin is the LED indication drive pin. The 9th pin is the thyristor drive pin. The 10th pin is the thyristor and heating wire abnormal monitoring pin. The 11th and 12th pins are the detection line NTC abnormal monitoring pins. The 13th pin is the PTC heating wire sampling signal pin. The 14th pin is the AC input voltage dividing sampling pin. The 15th pin is the AC input voltage zero-crossing detection pin. The 16th pin is the GND pin of the U1 chip. The chip U1 is internally provided with a multifunctional and reusable IO port, which can be used corresponding to the corresponding functions. For example, in this application, the 13th and 14th pins of U1 with AD functions are used for the sampling signal.

[0048] The mains voltage dividing and acquisition module includes resistors R1, R8, R13, R131, R132, R133, capacitors C10, and capacitor C11. Resistors R1 and R8 can also be regarded as one resistor, and resistors R13, R131, R132, and R133 can be regarded as one resistor. One end of resistor R1 is connected to the AC input terminal, the other end of resistor R1 is connected to R8, the other end of R8 is connected to R13 and R133, the other ends of R13 and R133 are connected to one end of R131 and R132, the other ends of R131 and R132 are connected to one of the AD ports of C10 and the main control circuit U1, and the other end of C10 is grounded. One ends of resistors R31 and R311 are connected to the thyristor and R30, the other ends of R31 and R311 are grounded, and the other end of R30 is connected to another AD port of U1 and C11. One end of capacitor C11 is grounded. The parameters of resistors R1, R8, R13, R131, R132, R133, R31, and R311 can be adjusted arbitrarily according to different chips and control systems.

[0049] Principle of voltage division and temperature control of the mains voltage dividing circuit module:

[0050] The calculation formula is as follows:

[0051] Calculate the value of AR, AR = [R131 × R132 / (R131 + 132)] + [R133 × R13 / (R133 + R13)];

[0052] Calculate the value of V1, V1 = AR / (AR + R1 + R8) × VIN × 1.414;

[0053] Calculate the value of BR, BR = R31 × R311 / (R31 + R311);

[0054] Calculate the value of V2, V2 = BR / (BR + T1 + T2 + PTC (resistance value of the heating wire PTC)) × VIN × 1.414;

[0055] Then, based on the values obtained above, the temperature control value can be calculated. AD = V1 / V2 × 12-bit or 10-bit ADC value, and the AD value of the set temperature can be obtained.

[0056] When this circuit is working, U1 will read the current temperature AD value. If it exceeds the set value, the heating will stop. If it is lower than the set value, the heating will continue, and so on.

[0057] Whether it is the change of the AC power grid voltage or the change of the resistance value of the heating wire PTC, it will cause the change of the temperature AD value, so as to achieve the purpose of controlling or keeping the temperature constant.

[0058] When the circuit is turned on, the mains power passes through the fuse F1, one end of the heating wire via the plug pin H1, through D2 and D5 to the voltage regulator U3 to output DC 5V to U1, then through R3 and R7 to the 15th pin INT zero-crossing signal of U1, and then the voltage-dividing signal composed of resistors R1, R8, R13, R131, R132, and R133 reaches the 14th pin of U1. At this time, the power-on preparation is completed.

[0059] When an external key inputs an instruction, the 9th pin of U1 outputs a pulse to drive the thyristors T1 and T2 to conduct, and the corresponding indicator light lights up. Then, according to the corresponding values of the external key instruction, the relative values of pins 13 and 14 are read and compared to control the conduction of T1 and T2, thereby controlling the temperature of the heating wire. For example: when the values detected by pins 13 and 14 are greater than the values of the corresponding key instruction, the driving of T1 and T2 is stopped. Conversely, the 9th pin of U1 outputs a pulse signal to drive T1 and T2 to conduct and heat the heating wire until it is constant with the value of the input corresponding instruction or the timing time ends.

[0060] When the timing ends, the 3rd pin of U1 will output a 1Hz signal indicating that this cyclic operation has been completed.

[0061] During this period, if there is an abnormal temperature in the heating wire thyristor control system, U1 will issue an error warning. Thus, all cyclic operations are completed.

[0062] The voltage-dividing signal composed of resistors R1, R8, R13, R131, R132, and R133 and the sampling resistor signal composed of R31 and R311 can be flexibly adjusted according to the range supported by different chips and different models.

[0063] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A temperature control circuit for maintaining a constant temperature within a wide AC input voltage range, comprising a controller, the temperature control circuit being applied to a blanket, characterized in that: The controller includes: an AC power input module, a main control module, a mains voltage collection module, a 5V voltage stabilization module, an EMI circuit module, a zero-crossing signal input module, a controller over-temperature protection circuit module, a heating drive circuit module, a display module, a key control unit module, a thyristor short circuit, a circuit break, a heating line circuit break detection module, a PTC sampling temperature control module, an NTC temperature detection module, an NTC line break detection module, a connector pin H1, a connector pin H2, a connector pin H3, and a connector pin H4; One end of the mains voltage collection module is connected to the AC power input module, and the other end is connected to the main control module; The mains voltage division acquisition module includes: resistors R1, R8, R13, R131, R132, and R133, one end of the resistor R1 is connected to the input end of the AC power input module, and the other end is connected in series with the resistor R8, and the resistor R133 is connected in parallel with R13 and in series with the series circuit of the resistors R1 and R8; Resistor R131 is connected in parallel with resistor R132, and resistor R133 is connected in parallel with R13 to form a series circuit.

2. A temperature control circuit for maintaining a constant temperature within a wide AC input voltage range according to claim 1, characterized in that: The L end of the AC power input module is grounded, and the N end is connected to the EMI module through a fuse F1; The EMI module is connected to the zero-crossing detection module and the 5V voltage stabilizing circuit; The zero-crossing detection module includes a resistor R4 and a resistor R5, which are connected in series to generate a zero-crossing signal that is input to the main control module.

3. A temperature control circuit for maintaining a constant temperature within a wide AC input voltage range according to claim 1, characterized in that: The display module is connected to the main control module to perform display, and the key control unit module is connected to the main control module to perform key signal input.

4. The temperature control circuit for maintaining a constant temperature within a wide AC input voltage range according to claim 1, characterized in that: The controller over-temperature protection circuit module is specifically: an NTC1 thermistor and a resistor R18 are connected in series, one end of the NTC1 thermistor is connected to a +5V VCC power supply, and the resistor R18 is grounded.

5. The temperature control circuit for maintaining a constant temperature within a wide AC input voltage range according to claim 1, characterized in that: The controller is connected to the heating wire of the blanket body through the plug pins H1, H2, H3 and H4.

6. The temperature control circuit for maintaining a constant temperature within a wide AC input voltage range according to claim 1, characterized in that: The silicon controlled short circuit, open circuit, heating line open circuit detection module, PTC sampling temperature control module, NTC temperature detection module, and NTC open circuit detection module are connected to the main control module.

7. The temperature control circuit for maintaining a constant temperature within a wide AC input voltage range according to claim 1, characterized in that: The PTC sampling temperature control module is connected to the heating drive circuit module and is connected in series to ground via a circuit in which resistors R311 and R31 are connected in parallel.

8. The temperature control circuit for maintaining a constant temperature within a wide AC input voltage range according to claim 7, characterized in that: The NTC temperature detection module is connected to the capacitor C12 and grounded, and the NTC disconnection detection module is connected to the capacitor C13 and grounded; the NTC temperature detection module is connected to the blanket heating wire through the connector pin H2; the NTC disconnection detection module is connected to the blanket heating wire through the connector pin H2.

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