CN204462905U - A kind of dual control circuit temperature - Google Patents

Abstract

The utility model discloses a double temperature control circuit, which comprises a microprocessor, and a first NTC voltage detection unit connected with the microprocessor, a second NTC voltage detection unit, a PTC load detection unit, a PTC voltage sampling unit, a protection controllable Silicon unit, working thyristor unit, indicator light unit, key unit, RC step-down unit, signal synchronization unit, first reference voltage unit, second reference voltage unit and reference resistor, wherein the protection thyristor unit It is further connected with the L line and the N line of the AC power input end, and a fuse is provided on the L line of the AC power input end. The dual temperature control circuit described in the utility model can provide multiple fault detection, real-time detection of the heating element PTC heating line and NTC induction line disconnection, short circuit and other faults provide double protection to improve the safety of electric blankets, and the whole circuit structure is simple, easy to operate, and low cost.

Description

A dual temperature control circuit

technical field

The utility model relates to a double temperature control circuit, in particular to a double temperature control circuit for electric blankets.

Background technique

The main principle of the traditional low-voltage electric blanket and heating pad control circuit is to control the on-off of the switch. The principle of this temperature control circuit is simple, but it has obvious shortcomings in fault detection, mainly in: 1. The use time is short (that is, the heating time is not long. Long), when a fault occurs, it cannot be detected immediately and the power supply is cut off for protection; 2. Usually, disposable dry batteries are used for power supply, which cannot be recharged, causing waste and polluting the environment. An increase in temperature will easily affect the service life of the battery, or insufficient protection for the rechargeable battery will cause line failures and cause unnecessary property losses.

In view of this, the inventor researched this and specially developed a dual temperature control circuit, and this case arose therefrom. the

Utility model content

The purpose of the utility model is to provide a dual temperature control circuit, which has the characteristics of multiple fault detection, high reliability, and convenient operation.

In order to achieve the above object, the solution of the present utility model is:

A dual temperature control circuit, including a microprocessor, and a first NTC voltage detection unit connected to the microprocessor, a second NTC voltage detection unit, a PTC load detection unit, a PTC voltage sampling unit, a protection thyristor unit, and a working Thyristor unit, indicator light unit, button unit, RC step-down unit, signal synchronization unit, first reference voltage unit, second reference voltage unit and reference resistor, wherein, the protection thyristor unit is further connected with the AC power supply The L line at the input end is connected to the N line, and a fuse is provided on the L line at the input end of the AC power supply. The first NTC voltage detection unit and the second NTC voltage detection unit are connected to the terminal of the NTC induction line of the heating element, and the two ends of the PTC heating line of the heating element are respectively connected to the L line of the AC power input end and the PTC load The detection unit and the working thyristor unit are connected.

As a preference, the microprocessor adopts the microprocessor of model HT66F018, which performs relevant actions after analyzing and processing the input signals of each unit, so as to protect the normal operation of the heating element.

As preferably, the first NTC voltage detection unit includes interconnected capacitors, resistors and diodes, one end of the first NTC voltage detection unit is connected to the microprocessor, and the other end is connected to the terminal of the NTC induction line of the heating element. Similarly, the The second NTC voltage detection unit also includes interconnected capacitors, resistors and diodes. One end of the second NTC voltage detection unit is connected to the microprocessor, and the other end is connected to the terminal of the NTC induction line of the heating element. Through the first NTC voltage detection unit 1. The second NTC voltage detection unit respectively detects the voltage at both ends of the NTC sensing line of the heating element, and sends the detection signal to the microprocessor, and then detects whether the NTC sensing line is disconnected.

Preferably, the PTC load detection unit includes a resistor between the PTC heating wire and the microprocessor, which is used to detect whether the PTC heating wire is disconnected, and whether there is a short circuit inside the terminals of the PTC heating wire and the NTC sensing wire.

Preferably, the PTC voltage sampling unit includes a resistor connected between the microprocessor and the N line of the input terminal of the AC power supply, which is used to realize the voltage sampling of the PTC heating line, and then control the temperature of the heating element.

Preferably, the working thyristor unit includes a working thyristor, and a resistor and a capacitor connected to the working thyristor, wherein the working thyristor is a bidirectional thyristor, and the working thyristor unit is connected to the microprocessor Between the device and the PTC heating wire, the power on and off of the PTC heating wire is controlled by turning on and off the working thyristor.

Preferably, the protection thyristor unit includes a protection thyristor, and resistors and capacitors connected to the protection thyristor, and the protection thyristor is further connected to the fuse on the AC power input terminal L line, when the heating wire When it burns out, the protection thyristor will act, and the fuse will be blown, so that the heating element will be de-energized.

Preferably, the indicator light unit includes a plurality of LED indicator lights, and resistors connected to the LED indicator lights for indicating various working states of the dual temperature control circuit; the button unit includes buttons and resistors.

Preferably, the RC step-down unit includes interconnected capacitors, step-down resistors, diodes, Zener diodes, etc., and the RC step-down unit is connected to the AC power input terminal L line for rectifying and stepping down the high-voltage AC power to 5 V The VCC voltage supplies power to the microprocessor and each unit respectively.

Preferably, the first reference voltage unit includes a diode, and a plurality of resistors connected to the diode, mainly providing a first reference voltage of 1.5V for the microprocessor. Similarly, the second reference voltage unit also includes a diode, And a plurality of resistors connected with the diodes provide the microprocessor with second reference voltages of different specifications according to different gear positions.

Preferably, the signal synchronization unit includes two resistors connected in series, and the signal synchronization unit is connected between the power input terminal L line and the microprocessor to provide a reference signal for the zero-crossing trigger of the thyristor.

The working principle of the above dual temperature control circuit: enter the working mode by pressing the button, the corresponding indicator light is on, the heating element starts to heat up, the resistance of the PTC heating line gradually increases, the PTC load detection unit sends the detection signal to the microprocessor, and the microprocessor The non-inverting voltage of the built-in voltage comparator decreases slowly. When it is lower than the first voltage reference of the corresponding gear at the inverting terminal, the microprocessor controls the working thyristor to cut off. Generally, after heating two sine waves, it passes through the first NTC. The voltage detection unit and the second NTC voltage detection unit detect the voltage value of the NTC induction line, if it is greater than the PTC voltage value of the corresponding gear, continue heating (stop 2 sine waves every 3 seconds to detect the NTC voltage, NTC load), if it is less than the set The value enters the constant temperature state. When the temperature of the heating element rises to the NTC temperature control setting value due to other reasons or abnormal use, the microprocessor will control the SCR to stop, stop for 1 minute, and then heat for 3 seconds after 1 minute and pass the first NTC The voltage detection unit and the second NTC voltage detection unit detect the NTC voltage value, and if it is lower than the second reference voltage, continue to operate in the heating mode of the PTC heating wire. (Because the NTC temperature control point is above the PTC high-grade temperature control point, the NTC mode will only operate when the heating element is folded or used abnormally).

Adopting the dual temperature control circuit described in the utility model can provide multiple fault detection, real-time detection of faults such as disconnection and short circuit of the PTC heating wire of the heating element and the NTC induction wire, and improves the safety of the electric blanket, and the whole circuit structure Simple, easy to operate and low cost. It has the following protection functions:

1. When the PTC heating wire is disconnected at any time (standby or working state), the microprocessor can detect it through the PTC load detection unit, and at the same time the corresponding fault light flashes (LED indicator light) to prompt;

2. The terminal of the NTC sensing line or the internal open circuit (standby or working state), the microprocessor can detect the voltage difference at both ends of the sensing line, and the corresponding fault light will flash to prompt;

3. There is an internal short circuit at the terminal of the PTC heating wire and the NTC induction wire, the microprocessor can detect it through the NTC load detection, and the corresponding fault light will flash to prompt;

4. Folding protection function: when the heating pad is folded during use, the temperature at the folded place will be very high, the resistance value of the folded place of the PTC heating wire and the NTC layer will become smaller, and the total resistance value will also become smaller, which also keeps the circuit at a constant temperature and will not Burn out the heating element.           

The utility model is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is the dual temperature control circuit module block diagram of the present embodiment;

Fig. 2 is a schematic diagram of the dual temperature control circuit of the present embodiment.

Detailed ways

In this embodiment, the heating element 14 of the electric blanket includes a PTC heating wire, an NTC layer, and an NTC induction wire connected to the NTC layer. As shown in Figure 1-2, a dual temperature control circuit includes a microprocessor 1, and a first NTC voltage detection unit 2 connected to the microprocessor 1, a second NTC voltage detection unit 3, and a PTC load detection unit 4 , PTC voltage sampling unit 5, protection thyristor unit 6, working thyristor unit 7, indicator light unit 8, button unit 9, RC step-down unit 10, signal synchronization unit 11, first reference voltage unit 12, second Two reference voltage units 13 and a reference resistor R35, wherein, the protection thyristor unit 6 is further connected with the L line and the N line of the 120V AC power input end, and a fuse F1 is arranged on the L line of the 120V AC power input end, and the resistance Capacitor step-down unit 10, signal synchronization unit 11, first reference voltage unit 12, and second reference voltage unit 13 are connected to the L line of the AC power input end, the first NTC voltage detection unit 2, the second NTC voltage detection unit 2 It is connected to the terminal of the NTC induction line of the heating element 14, and the two ends of the PTC heating line of the heating element 14 are respectively connected to the L line of the AC power input end, the PTC load detection unit 4, and the working thyristor unit 7.

The microprocessor 1 adopts a microprocessor model of HT66F018, and the microprocessor 1 performs relevant actions after analyzing and processing the input signals of each unit to protect the heating element 14 from working normally.

The first NTC voltage detection unit 2 includes a plurality of interconnected capacitors C4, resistors R24, R25, R26 and diodes D4, D5, one end of the first NTC voltage detection unit 2 is connected to the microprocessor 1, and the other end is connected to the heating element The terminal of the NTC induction line; Similarly, the second NTC voltage detection unit 3 also includes a plurality of interconnected capacitors C5, resistors R27, R28, R29 and diodes D6, D7, one end of the second NTC voltage detection unit 3 and The microprocessor 1 is connected, and the other end is connected to the terminal of the NTC induction line of the heating element, and the voltage at both ends of the NTC induction line of the heating element is respectively detected by the first NTC voltage detection unit 2 and the second NTC voltage detection unit 3, and the detection signal is sent to Give the microprocessor 1, and then detect whether the NTC sensing line is disconnected.

The PTC load detection unit 4 includes resistors R30 and R31 between the PTC heating wire and the microprocessor 1, which are used to detect whether the PTC heating wire is disconnected, and whether there is a short circuit inside the PTC heating wire and the NTC sensing wire terminal.

The PTC voltage sampling unit 5 includes resistors R35 and R36 connected between the microprocessor and the N line of the input terminal of the AC power supply, for realizing the voltage sampling of the PTC heating line, and then controlling the temperature of the heating element 14 .

The working thyristor unit 7 includes a working thyristor T1, and resistors R34, R35, and a capacitor C6 connected to the working thyristor T1, wherein the working thyristor T1 is a bidirectional thyristor, and the working thyristor Unit 7 is connected between the microprocessor 2 and the PTC heating wire, and controls the power on and off of the PTC heating wire by turning on and off the working thyristor T1.

The protection thyristor unit 6 includes a protection thyristor T2, resistors R37, R38, and a capacitor C7 connected to the protection thyristor T2, and the protection thyristor T2 is further connected to the fuse on the AC power input terminal L line F1 is connected, and when the heating wire burns out, the protection thyristor T2 will act, and the fuse F1 will be blown, so that the heating element 10 will be de-energized.

The indicator light unit 8 includes a plurality of LED indicator lights and resistors connected to the LED indicator lights for indicating the working states of the dual temperature control circuit. In this embodiment, the LED indicator lights include light-emitting diodes L1 , L2 , L3 , L4 , and resistors R13 , R14 , R15 , R16 connected to the light-emitting diodes; the key unit includes a key K1 and a resistor R32 .

The RC step-down unit 10 includes interconnected capacitors C1, C2, C3, step-down resistor R1, diode D1, and Zener diode ZD1, and the RC step-down unit 10 is connected to the AC power input terminal L line for connecting the The high-voltage alternating current is rectified and stepped down to a VCC voltage of 5 V, which supplies power for the microprocessor 1 and each unit respectively.

The first reference voltage unit 12 includes a diode D3, and a plurality of resistors R17, R18, and R19 connected to the diode D3, which mainly provide the microprocessor 1 with a first reference voltage of 1.5V. Similarly, the second reference The voltage unit 13 also includes a diode D2, and a plurality of resistors R2, R3, R4, R5, R6, R7, R8, R9, R10, R11 connected to the diode, which provide the microprocessor 1 with different specifications according to different gears. second reference voltage.

The signal synchronization unit 11 includes two resistors R20 and R21 connected in series. The signal synchronization unit is connected between the power input terminal L line and the microprocessor 1 to provide a reference signal for the SCR zero-crossing trigger.

The above-mentioned embodiments and drawings do not limit the product form and style of the present utility model, and any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present utility model.

Claims (10)

1. a dual control circuit temperature, is characterized in that: comprise microprocessor, and the NTC voltage detection unit be connected with microprocessor, 2nd NTC voltage detection unit, PTC load detecting unit, PTC voltage sampling unit, protection controllable silicon unit, work controllable silicon unit, indicator unit, push-button unit, resistance-capacitance depressurization unit, signal synchronization unit, first reference voltage unit, second reference voltage unit and reference resistance, wherein, described protection controllable silicon unit is connected with N line with the L line of ac power input end further, and the L line of ac power input end is provided with fuse, described resistance-capacitance depressurization unit, signal synchronization unit, first reference voltage unit, second reference voltage unit is all connected with the L line of ac power input end, a described NTC voltage detection unit, 2nd NTC voltage detection unit is connected with the terminals of the heater NTC line of induction, the two ends of heater PTC line with heating function respectively with the L line of ac power input end, and PTC load detecting unit, work controllable silicon unit is connected.

2. a kind of dual control circuit temperature as claimed in claim 1, is characterized in that: described microprocessor adopts model to be the microprocessor of HT66F018.

3. a kind of dual control circuit temperature as claimed in claim 1, it is characterized in that: a described NTC voltage detection unit comprises multiple interconnective resistance and diode, one NTC voltage detection unit one end is connected with microprocessor, and the other end connects the terminals of the heater NTC line of induction; Described 2nd NTC voltage detection unit also comprises multiple interconnective resistance and diode, 2nd NTC voltage detection unit one end is connected with microprocessor, the other end connects the terminals of the heater NTC line of induction, the voltage at heater NTC line of induction two ends is detected respectively by a NTC voltage detection unit, the 2nd NTC voltage detection unit, and detection signal is sent to microprocessor, and then detect the whether open circuit of the NTC line of induction.

4. a kind of dual control circuit temperature as claimed in claim 1, it is characterized in that: described PTC load detecting unit is included in the resistance between PTC line with heating function and microprocessor, whether disconnect for detecting PTC line with heating function, and the whether short circuit of PTC line with heating function and NTC line of induction terminals inside.

5. a kind of dual control circuit temperature as claimed in claim 1, is characterized in that: institute PTC voltage sampling unit comprises the resistance be connected between microprocessor and ac power input end N line, for realizing the voltage sample of PTC line with heating function.

6. a kind of dual control circuit temperature as claimed in claim 1, it is characterized in that: described work controllable silicon unit comprises work controllable silicon, and with work the controllable silicon resistance, the electric capacity that are connected, wherein said work controllable silicon is bidirectional triode thyristor, work controllable silicon unit is connected between microprocessor and PTC line with heating function, is come energising and the power-off of control PTC line with heating function by work silicon controlled conducting and cut-off; Described protection controllable silicon unit comprises protection controllable silicon, and the resistance, the electric capacity that are connected with protection controllable silicon, and described protection controllable silicon is connected with the fuse on ac power input end L line further.

7. a kind of dual control circuit temperature as claimed in claim 1, is characterized in that: described indicator unit comprises multiple LED light, and the resistance be connected with LED light, is used to indicate, the work in every state of dual control circuit temperature; Described push-button unit comprises button and resistance.

8. a kind of dual control circuit temperature as claimed in claim 1, it is characterized in that: resistance-capacitance depressurization unit comprises interconnective electric capacity, dropping resistor, diode, voltage stabilizing diode, resistance-capacitance depressurization unit is connected with ac power input end L line, for being the VCC voltage of 5 V by the step-down of high-voltage alternating electric rectification, be respectively microprocessor and unit is powered.

9. a kind of dual control circuit temperature as claimed in claim 1, it is characterized in that: described first reference voltage unit comprises diode, and the multiple resistance to be connected with diode, for microprocessor provides first reference voltage of 1.5V, in like manner, described second reference voltage unit also comprises diode, and the multiple resistance be connected with diode, according to different gear, for microprocessor provides the second reference voltage of different size.

10. a kind of dual control circuit temperature as claimed in claim 1, is characterized in that: described signal synchronization unit comprises two resistance of mutually connecting, and signal synchronization unit is connected between power input L line and microprocessor.