CN218886478U - Non-optical coupling temperature control circuit of PTC (positive temperature coefficient) and NTC (negative temperature coefficient) characteristic heating wire and heating product - Google Patents

Non-optical coupling temperature control circuit of PTC (positive temperature coefficient) and NTC (negative temperature coefficient) characteristic heating wire and heating product Download PDF

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CN218886478U
CN218886478U CN202223123935.8U CN202223123935U CN218886478U CN 218886478 U CN218886478 U CN 218886478U CN 202223123935 U CN202223123935 U CN 202223123935U CN 218886478 U CN218886478 U CN 218886478U
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resistor
capacitor
ptc
heating
power supply
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黄首跃
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Ningbo Beloway Electric Appliance Co ltd
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Ningbo Beloway Electric Appliance Co ltd
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Abstract

The utility model relates to a no optical coupling temperature control circuit and the product that generates heat of PTC and NTC characteristic heating wire, this no optical coupling temperature control circuit includes PTC constant temperature control circuit, NTC overtemperature protection circuit, a drive circuit, DC power supply circuit and microcontroller, PTC constant temperature control circuit has the heating wire of PTC/NTC characteristic, the control switch and the current sampling resistor that generate heat that adopt main bidirectional thyristor, DC power supply circuit has mains voltage end and earthing terminal, AC power supply's live wire is connected to DC power supply circuit's mains voltage end, the live wire of AC power supply is connected through current sampling resistor to the first main terminal of control switch that generates heat. The trigger signal for controlling the main bidirectional controllable silicon to be turned off or turned on is always negative voltage, the main bidirectional controllable silicon of the non-optical coupling temperature control circuit works in the second quadrant and the third quadrant in a negative trigger mode, an expensive optical coupler is not needed, and cost is greatly reduced.

Description

PTC and NTC characteristic heating wire non-light coupling temperature control circuit and heating product
Technical Field
The utility model relates to a temperature control field of the product that generates heat especially relates to a no optical coupling temperature control circuit of PTC and NTC characteristic heating wire and the product that generates heat.
Background
The PTC and NTC characteristic heating wire (namely PTC/NTC characteristic heating wire) is characterized in that a detection wire and a PTC heating wire are arranged in a PVC insulating layer shell, and a layer of NTC insulating material is filled between the detection wire and the PTC heating wire. The heating elements of the existing heating products such as heating pads, electric blankets, pet pads and dinner plate heating pads and the like often adopt the PTC/NTC characteristic heating wire. The temperature control circuit is important for the work of heating products adopting PTC/NTC heating wires.
The existing temperature control circuit comprises a direct current power supply circuit, a microcontroller and a heating control switch (hereinafter referred to as main bidirectional thyristor or main silicon), wherein the direct current power supply circuit takes a zero line of an alternating current power supply as a reference, namely the zero line of the alternating current power supply is a ground terminal (GND) of the direct current power supply, and the heating control switch is positioned on a live wire side of the alternating current power supply. Although the trigger level (referring to the voltage of the trigger end G to the first main end) of the heating control switch is between-5V and 0V or between 0V and 5V, and the output level (referring to the voltage of the output pin to the ground end GND) of the microcontroller is between 0V and 5V, since the trigger level of the heating control switch and the output level of the microcontroller do not have a common reference point (for example, common 5V or common GND), in order to realize the control of the microcontroller on or off the heating control switch, an expensive thyristor output type optocoupler must be used to make the heating control switch work in the first quadrant (positive trigger mode) and the third quadrant (negative trigger mode), which will result in that the design cost of the temperature control circuit is greatly increased due to the use of the expensive thyristor output type optocoupler.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the first technical problem that provide one kind to above-mentioned prior art and need not silicon controlled rectifier output type opto-coupler, realize the no opto-coupler control circuit of temperature control's PTC and NTC characteristic heating wire with the low cost.
The utility model discloses the second technical problem that solve provides an application and has the product that generates heat of above-mentioned no opto-coupler control circuit to above-mentioned prior art.
The utility model provides a technical scheme that first technical problem adopted does: a non-optical coupling temperature control circuit of PTC and NTC characteristic heating wires comprises:
the PTC constant temperature control circuit comprises a heating wire with PTC/NTC characteristics and a heating control switch, wherein the heating control switch is connected with the heating wire; wherein, the heating control switch is a main bidirectional thyristor;
an NTC over-temperature protection circuit;
a drive circuit;
a DC power supply circuit having a power supply voltage terminal and a ground terminal; and (c) a second step of,
the microcontroller sends a trigger signal to the heating control switch;
the PTC constant temperature control circuit is characterized by further comprising a current sampling resistor, the power voltage end of the direct current power supply circuit is connected with the live wire of the alternating current power supply, and the first main end of the heating control switch is connected with the live wire of the alternating current power supply through the current sampling resistor.
In the non-optical coupling temperature control circuit of the PTC and NTC characteristic heating wire, the direct current power supply circuit comprises a current-limiting resistor, a high-voltage capacitor, a first resistor, a first diode, a second diode, a voltage-regulator tube, a first capacitor, a second capacitor and a second resistor, wherein the first end of the second resistor is connected with a live wire of an alternating current power supply through a temperature fuse, the second end of the second resistor is connected with a grounding end, the first pole of the second capacitor is connected with the first end of the second resistor, the second pole of the second capacitor is connected with the grounding end, the positive pole of the first capacitor is connected with the first end of the second resistor, the negative pole of the first capacitor is connected with the grounding end, the positive pole of the voltage-regulator tube is connected with the grounding end, and the negative pole of the voltage-regulator tube is connected with the first end of the second resistor; the anode of the second diode is connected with the anode of the voltage-stabilizing tube, the cathode of the second diode is connected with the anode of the first diode, and the cathode of the first diode is connected with the cathode of the voltage-stabilizing tube; the first end of the current-limiting resistor is connected with a zero line of an alternating current power supply through a current fuse, the second end of the current-limiting resistor is connected with the anode of the first diode through the high-voltage capacitor, and the first resistor is connected in parallel with the two ends of the high-voltage capacitor.
Further, in the non-optical coupling temperature control circuit of the PTC and NTC characteristic heating wire, the microcontroller is provided with a HEAT signal end, a UR signal end and a SYN signal end, and the PTC constant temperature control circuit further comprises a third resistor, a third capacitor, a fourth resistor, a fifth resistor, a sixth resistor and a filter capacitor; the first end of the heating control switch is connected with the first end of the current sampling resistor, the second end of the current sampling resistor is connected with a live wire of the alternating current power supply through a temperature fuse, the second end of the heating control switch is connected with the first inserting end of the heating wire, and the second inserting end of the heating wire is connected with a zero line of the alternating current power supply through the current fuse; the first end of the third capacitor is connected with the first end of the current sampling resistor through a third resistor, and the second end of the third capacitor is connected with the second end of the current sampling resistor; the first end of the third capacitor is provided with a PTC detection point; the first end of the fourth resistor is connected with a zero line of an alternating current power supply through a current fuse, and the second end of the fourth resistor is connected with a SYN signal end of the microcontroller; the first end of the fifth resistor is connected with the first end of the fourth resistor, and the second end of the fifth resistor is connected with the UR signal end of the microcontroller; the first end of the sixth resistor is connected with the second end of the fifth resistor, and the second end of the sixth resistor is connected with + XV direct-current voltage; and the first pole of the filter capacitor is connected with the second end of the sixth resistor, and the second pole of the filter capacitor is connected with the UR signal end of the microcontroller.
In a further improvement, in the non-optical coupling temperature control circuit with the PTC and NTC characteristic heating wires, the driving circuit includes a fourth capacitor, a seventh resistor and an eighth resistor, a first end of the eighth resistor is connected to the first end of the heating control switch, a second end of the eighth resistor is connected to the third end of the heating control switch, a second end of the eighth resistor is connected to the first pole of the fourth capacitor through the seventh resistor, and a second pole of the fourth capacitor is connected to a HEAT signal end of the microcontroller.
In the non-optical coupling temperature control circuit of the PTC and NTC characteristic heating wire, the NTC over-temperature protection circuit comprises a ninth resistor, a tenth resistor, an eleventh resistor and a fifth capacitor, wherein the first end of the ninth resistor is connected with a live wire of an alternating current power supply through a temperature fuse, and the second end of the ninth resistor is connected with the third plug-in end of the heating wire; a first end of the tenth resistor is connected with a first end of the ninth resistor through the eleventh resistor, a second end of the tenth resistor is connected with a second end of the ninth resistor, a first pole of the fifth capacitor is connected with the first end of the eleventh resistor, and a second pole of the fifth capacitor is connected with the first end of the tenth resistor; and an NTC detection point is arranged on the second pole of the fifth capacitor.
Further, in the invention, the non-optical coupling temperature control circuit of the PTC and NTC characteristic heating wire further comprises a gear adjusting circuit connected with the microcontroller MCU.
In a further improvement, the non-light-coupling temperature control circuit of the PTC and NTC characteristic heating wire further comprises a gear indication circuit for indicating the gear state, and the gear indication circuit is connected with the microcontroller MCU.
Preferably, in the non-optical-coupling temperature control circuit with the PTC and NTC characteristic heating wires, the + XV dc voltage is +5V dc voltage, the voltage input end of the microcontroller MCU is connected to the +5V dc voltage, and the first end of the second resistor is connected to the +5V dc voltage.
The utility model provides a technical scheme that second technical problem adopted does: the heating product is characterized in that a non-optical coupling temperature control circuit with any PTC and NTC characteristic heating wire is applied.
Further, in the utility model, the heating product is a heating pad, an electric blanket, a pet pad, or a dinner plate heating pad.
Compared with the prior art, the utility model has the advantages of: the utility model discloses an among the no light coupling temperature control circuit, the live wire of alternating current power supply is connected through making direct current power supply circuit's power voltage end to the live wire that adopts main bidirectional thyristor's the first main end rethread current sampling resistor connection alternating current power supply that generates heat control switch. Thus, once the HEAT signal terminal of the microcontroller outputs a high level, the trigger terminal of the master triac will get the same high level as the first master terminal (i.e. live wire) of the master triac, and the master triac turns off. Once the HEAT signal terminal of the microcontroller outputs a low level, the trigger terminal of the master triac will get a lower low level relative to the first master terminal (i.e., live line) of the master triac, and the master triac turns on. Namely, the trigger signal for controlling the main bidirectional thyristor to be turned off or turned on is always negative voltage, that is, the main bidirectional thyristor of the non-optical coupling temperature control circuit works in the second quadrant (negative trigger mode) and the third quadrant (negative trigger mode), and an expensive optical coupler is not needed, so that the cost is greatly reduced.
Drawings
FIG. 1 is a schematic diagram of a non-optical-coupling temperature control circuit for PTC and NTC heating wires according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a portion A of the non-optical-coupling temperature control circuit shown in FIG. 1;
fig. 3 is a circuit diagram of a portion B of the non-optical coupling temperature control circuit shown in fig. 1.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments.
The present embodiment provides a non-optical coupling control circuit for a PTC and NTC characteristic heating wire. Referring to fig. 1, the non-optical-coupling temperature control circuit for the PTC and NTC characteristic heating wires of the embodiment includes a PTC constant temperature control circuit, an NTC over-temperature protection circuit, a driving circuit, a dc power supply circuit, a gear adjustment circuit, a gear indication circuit for indicating a gear state, and a microcontroller MCU, for example, the microcontroller may be a CMS79F112, the gear adjustment circuit and the gear indication circuit are both connected to the microcontroller MCU, the microcontroller MCU has a HEAT signal terminal (i.e., a heating driving signal terminal), a UR signal terminal (i.e., a grid voltage signal terminal), and a SYN signal terminal (i.e., a synchronization signal terminal), and a voltage input terminal of the microcontroller MCU is connected to a +5V dc voltage. Wherein: the PTC constant temperature control circuit is provided with a heating wire 402 with PTC/NTC characteristics, a heating control switch 401 and a current sampling resistor R403, wherein the heating control switch 401 is connected with the heating wire 402, and the heating control switch 401 is a main bidirectional thyristor; the direct current power supply circuit is provided with a power supply voltage end V and a grounding end GND; the microcontroller MCU sends a trigger signal to the heating control switch 401. The power supply voltage end V of the dc power supply circuit is connected to the live line L of the ac power supply, and the first main end of the heating control switch 401 is connected to the live line L of the ac power supply through the current sampling resistor R403. Wherein, the power voltage end V is 5V.
In an embodiment, the dc power circuit includes a current-limiting resistor R201, a high-voltage capacitor C202, a first resistor R203, a first diode D204, a second diode D205, a regulator D206, a first capacitor C207, a second capacitor C208, and a second resistor R209, where a first end of the second resistor R209 is connected to a live wire L of the ac power supply through a thermal fuse FU101, a second end of the second resistor R209 is connected to a ground terminal GND, a first pole of the second capacitor C208 is connected to a first end of the second resistor R209, a second pole of the second capacitor C208 is connected to the ground terminal GND, a positive pole of the first capacitor C207 is connected to the first end of the second resistor R209, a negative pole of the first capacitor C207 is connected to the ground terminal GND, a positive pole of the regulator D206 is connected to the ground terminal, and a negative pole of the regulator D206 is connected to the first end of the second resistor R209; the anode of the second diode D205 is connected with the anode of the voltage regulator tube D206, the cathode of the second diode D205 is connected with the anode of the first diode D204, and the cathode of the first diode D204 is connected with the cathode of the voltage regulator tube D206; the first end of the current limiting resistor R201 is connected with a zero line N of an alternating current power supply through a current fuse FU100, the second end of the current limiting resistor R201 is connected with the anode of a first diode D204 through a high-voltage capacitor C202, and a first resistor R203 is connected with two ends of the high-voltage capacitor C202 in parallel. The first end of the third resistor R209 is connected with +5V direct current voltage.
The PTC constant temperature control circuit comprises a third resistor R404, a third capacitor C405, a fourth resistor R801, a fifth resistor R901, a sixth resistor R902 and a filter capacitor C903; the first end of the heating control switch 401 is connected with the first end of the current sampling resistor R403, the second end of the current sampling resistor R403 is connected with the live wire L of the alternating current power supply through the temperature fuse FU101, the second end of the heating control switch 401 is connected with the first plugging end H1 of the heating wire 402, and the second plugging end H2 of the heating wire 402 is connected with the zero wire N of the alternating current power supply through the current fuse FU 100; a first end of the third capacitor C405 is connected to a first end of the current sampling resistor R403 through the third resistor R404, and a second end of the third capacitor C405 is connected to a second end of the current sampling resistor R403; a PTC detection point is arranged at the first end of the third capacitor C405; a first end of the fourth resistor R801 is connected with a zero line N of an alternating current power supply through the current fuse FU100, and a second end of the fourth resistor R801 is connected with a SYN signal end of the microcontroller MCU; a first end of the fifth resistor R901 is connected with a first end of the fourth resistor R801, and a second end of the fifth resistor R901 is connected with a UR signal end of the microcontroller MCU; a first end of the sixth resistor R902 is connected to a second end of the fifth resistor R901, and a second end of the sixth resistor R902 is connected to + XV dc voltage; the first pole of the filter capacitor C903 is connected with the second end of the sixth resistor R902, and the second pole of the filter capacitor C903 is connected with the UR signal end of the microcontroller MCU. Wherein the + XV DC voltage is +5V DC voltage.
The driving circuit comprises a fourth capacitor C301, a seventh resistor R302 and an eighth resistor R303, the first end of the eighth resistor R303 is connected with the first end of the heating control switch 401, the second end of the eighth resistor R303 is connected with the third end of the heating control switch 401, the second end of the eighth resistor R303 is connected with the first pole of the fourth capacitor C301 through the seventh resistor R302, and the second pole of the fourth capacitor C301 is connected with the HEAT signal end of the microcontroller MCU.
The NTC over-temperature protection circuit comprises a ninth resistor R106, a tenth resistor R107, an eleventh resistor R108 and a fifth capacitor C109, wherein a first end of the ninth resistor R106 is connected with a live wire L of an alternating current power supply through a temperature fuse FU101, and a second end of the ninth resistor R106 is connected with a third plugging end H3 of the heating wire 402; a first end of the tenth resistor R107 is connected to a first end of the ninth resistor R106 via the eleventh resistor R108, a second end of the tenth resistor R107 is connected to a second end of the ninth resistor R106, a first pole of the fifth capacitor C109 is connected to a first end of the eleventh resistor R108, and a second pole of the fifth capacitor C109 is connected to a first end of the tenth resistor R107; an NTC detection point is disposed on the second pole of the fifth capacitor C109.
The gear adjusting circuit comprises three gear circuits which are connected in parallel. Wherein: the first gear circuit comprises a switch 503 and a resistor R502 which are mutually connected in series, wherein the first end of the switch 503 is grounded, the second end of the switch 503 is connected with the first end of the resistor R502, and the second end of the resistor R502 is connected with 5V direct-current voltage through the resistor R501; the second gear circuit comprises a switch 505 and a resistor R504 which are connected in series, wherein a first end of the switch 505 is grounded, a second end of the switch 505 is connected with a first end of the resistor R504, and a second end of the resistor R504 is connected with a second end of the resistor R502; the third gear circuit comprises a switch 507 and a resistor R506 which are connected in series, wherein a first end of the switch 507 is grounded, a second end of the switch 507 is connected with a first end of the resistor R506, and a second end of the resistor R506 is connected with a second end of the resistor R502. The second end of the resistor R502, the second end of the resistor R504, and the second end of the resistor R506 are all connected to the SW pin of the microcontroller MCU.
The gear indication circuit comprises four paths of indication circuits. Wherein:
the first path of indicating circuit comprises a resistor R701, a light emitting diode D709 and a light emitting diode D710, wherein the first end of the resistor R701 is connected with a pin 4 of the microcontroller MCU, and the second end of the resistor R701 is respectively connected with the anode of the light emitting diode D709 and the cathode of the light emitting diode D710;
the second path of indicating circuit comprises a resistor R702, a light emitting diode D707 and a light emitting diode D708, wherein the first end of the resistor R702 is connected with a pin 5 of the microcontroller MCU, and the second end of the resistor R702 is respectively connected with the anode of the light emitting diode D707 and the cathode of the light emitting diode D708;
the third path of indicating circuit comprises a resistor R703, a light emitting diode D705 and a light emitting diode D706, wherein the first end of the resistor R703 is connected with a pin 6 of the microcontroller MCU, and the second end of the resistor R703 is respectively connected with the anode of the light emitting diode D705 and the cathode of the light emitting diode D706;
the fourth path of indicating circuit comprises a resistor R704, a light emitting diode D711 and a light emitting diode D712, wherein the first end of the resistor R704 is connected with a pin 7 of the microcontroller MCU, and the second end of the resistor R704 is respectively connected with the cathode of the light emitting diode D711 and the anode of the light emitting diode D712;
the anode of the light emitting diode D711 and the cathode of the light emitting diode D712 are both connected to the second end of the resistor R701.
In this embodiment, the dc power circuit converts the high-voltage ac into the low-voltage dc by using a resistance-capacitance step-down and half-wave rectification filtering method. And in the positive half cycle of alternating current, 5V direct current voltage is obtained at two ends of the first capacitor C207 and the second capacitor C208 through an alternating current power supply live wire L, a temperature fuse FU101, a voltage regulator tube D206, a first capacitor C207, a second capacitor C208, a second resistor R209, a second diode D205, a high-voltage capacitor C202, a current limiting resistor R201, a current fuse FU100 and an alternating current power supply zero line N, and the direct current voltage is used by a microcontroller MCU and a peripheral circuit thereof.
In the PTC constant temperature control circuit of this embodiment, the heat generating layer of the heat generating wire 402 has a characteristic of Positive Temperature Coefficient (PTC) variation of 0.0044 Ω/° c.
At the positive half cycle peak point of alternating current, the alternating current power supply is started from the live wire L, the temperature fuse FU101, the current sampling resistor R403 and the heating control switchA loop current I is generated in a heating loop formed by a switch 401 (main bidirectional thyristor), a heating wire 402, a current fuse FU100 and a zero line N ptc (ii) a Inversely proportional to the resistance (i.e. temperature) of the heating layer, a current proportional to the loop current I is generated at the two ends of the current sampling resistor R403 ptc The voltage is filtered by a third resistor R404 and a third capacitor C405 to obtain a stable and collectable voltage V ptc And the signals are sent to a microcontroller MCU for A/D conversion. Meanwhile, an alternating current power supply is arranged in a loop formed by a live wire L, a temperature fuse FU101, a sixth resistor R902, a filter capacitor C903, a fifth resistor R901, a current fuse FU100 and a zero line N, and voltage V proportional to the alternating current power supply is generated at two ends of the filter capacitor C903 ref And also sent to the microcontroller MCU for A/D conversion. In the microcontroller MCU, dividing two paths of AD values by V ref /V ptc Equivalent to V ref /I ptc The resistance value R of the heating layer at the current temperature can be obtained ptc The current temperature of the heat generating layer is also known.
If the current temperature is lower than the set temperature, the heating control switch 401 (namely, the main bidirectional controllable silicon) is switched on, and heating is started.
If the current temperature is higher than the set temperature, the heating control switch 401 (i.e. the main triac) is turned off, and the heating is stopped.
During the heating stop period, if the heating loop current I can still be detected ptc If the short circuit phenomenon occurs in the main triac of the heating control switch 401, the microcontroller MCU immediately outputs a low level (0V) through the PROT pin, then the low level is divided by the resistor R104 and the resistor R105, the triac (secondary silicon for short) 103 for protection is turned on, the ac power supply will act on the resistor R102 completely to cause the resistor R102 to heat rapidly, the thermal fuse FU101 tightly attached to the resistor R102 reaches an operating temperature in a short time to be fused, and the connection between the ac power supply and the heating circuit is cut off to achieve the final protection purpose. Here is the first re-protection of the opto-coupler free control circuit in this embodiment.
During the start-up heating, if the heating loop current I cannot be detected ptc This indicates that the heating control switch 401 (i.e., the main triac) has opened or that the heating control switch is openThe heating layer of the hot wire is open-circuited, the heating loop cannot be established, and the safety problem cannot occur. But for production convenience and user-friendliness, the microcontroller immediately turns off the main silicon trigger signal and displays an alarm code through the display circuit. Here is a second protection of the optocoupler-free control circuit in this embodiment.
The bidirectional controllable silicon adopts a second quadrant (negative trigger mode) and a third quadrant (negative trigger mode) working modes of zero-crossing triggering.
After the SYN signal end of the microcontroller MCU detects the zero-crossing signal of the ac power through the fourth resistor R801, a trigger pulse synchronized with the zero-crossing signal of the ac power is output from the HEAT signal end, and the heating control switch 401 (i.e., the main triac) is triggered to be turned on through a differential circuit formed by the fourth capacitor C301, the seventh resistor R302, and the eighth resistor R303, so that the heating layer receives the ac power to HEAT.
Because the capacitive coupling is adopted to transmit the trigger pulse signal, even if the MCU fails or the HEAT port is damaged, the low level is always output and can be isolated by the fourth capacitor C301, the heating control switch 401 (namely, the main bidirectional triode thyristor) cannot be conducted due to the fact that the trigger current cannot be obtained, the heating wire cannot be heated, and the safety and the reliability of the product are ensured. Here is the third protection of the opto-coupler-free control circuit in this embodiment.
For the NTC over-temperature protection circuit, when the product is not normally used, a local or single-point over-high temperature may occur, and since the middle insulating layer of the heating line 402 has a Negative Temperature Coefficient (NTC) characteristic, the high temperature may cause the insulation resistance of the NTC insulating layer to decrease, and detecting the leakage current generated by the ac power supply in the NTC insulating layer of the heating line 402 may determine whether the heating line has a high temperature phenomenon.
First, the heating control switch 401 (i.e. the main triac) is turned off to avoid other interference signals or shunt loops from affecting the inspection result, so as to form an NTC over-temperature protection circuit, wherein the live line L of the AC power supply-the temperature fuse FU 101-the ninth resistor R106-the heating line 402 (NTC insulation layer) -the current fuse FU 100-the zero line N generate a voltage proportional to the leakage current on the ninth resistor R106, and then pass through the tenth resistor R107 and the eleventh resistor R108 to obtain a voltage V in the range of 0 to 5V still proportional to the leakage current ntc Microcontroller MCU pair V ntc A/D conversion is performed. Once V is ntc And when the temperature is higher than the over-temperature protection set value, the heating control switch 401 (namely, the main bidirectional controllable silicon) is turned off, heating is stopped, and reheating is allowed until the temperature of the local high-temperature point returns to the safety range, so that the purpose of over-temperature protection is achieved. Here is the fourth protection of the opto-coupler free control circuit in this embodiment.
If the product is not normally used, the heating layer and the detection layer of the heating wire 402 are short-circuited, the resistance values of the tenth resistor R107 and the eleventh resistor R108 are large, the alternating current power supply completely acts on the ninth resistor R106 to cause the ninth resistor R106 to rapidly heat, the temperature fuse FU101 which is tightly attached to the ninth resistor R106 reaches the operating temperature in a short time and is fused, the connection between the alternating current power supply and the heating loop is cut off, and the final protection purpose is achieved. Here is a fifth protection of the opto-coupler free control circuit in this embodiment.
In this embodiment, the overcurrent protection circuit is composed of a current fuse FU100 connected to the N-terminal of the neutral line of the ac power supply. When the whole circuit connected to the rear end of the current fuse FU100 has abnormal conditions such as short circuit and the like, and the total current flowing through the current fuse FU100 exceeds the rated current of the current fuse FU100, the current fuse FU100 can be fused, and the connection between an alternating current power supply and the whole non-light coupling temperature control circuit is cut off, so that the final protection purpose is achieved. Here is the sixth protection of the opto-coupler-less control circuit in this embodiment.
As a modification, the non-optical-coupling control circuit of the PTC and NTC characteristic heating wire of this embodiment further includes a board temperature protection circuit. Specifically, the board temperature protection circuit in this embodiment is composed of an NTC thermistor R601, a voltage dividing resistor R602, and a filter capacitor C603, and is connected between the motherboard 5V and GND. The voltage of the voltage dividing resistor R602 is increased along with the rise of the board temperature of the circuit board arranged in the shell of the microcontroller, when the set temperature is exceeded, the microcontroller MCU immediately turns off a trigger signal aiming at the heating control switch 401 (namely, the main bidirectional triode thyristor), the heating is stopped, and an alarm code is displayed through the display circuit. Here is a seventh protection of the opto-coupler free control circuit in this embodiment.
In the non-optical coupling temperature control circuit of this embodiment, the power supply voltage terminal of the dc power supply circuit is connected to the live wire of the ac power supply, and the first main terminal of the heating control switch using the main triac is connected to the live wire of the ac power supply through the current sampling resistor. Thus, once the HEAT signal end of the microcontroller outputs a high level, the trigger end of the master triac will get the same high level as the first master end (i.e., live line) of the master triac, and the master triac will turn off. Once the HEAT signal terminal of the microcontroller outputs a low level, the trigger terminal of the master triac will get a lower low level relative to the first master terminal (i.e., live line) of the master triac, and the master triac turns on. Namely, the trigger signal for controlling the main bidirectional thyristor is always negative voltage, that is, the main bidirectional thyristor of the no-optical coupling temperature control circuit works in the second quadrant (negative trigger mode) and the third quadrant (negative trigger mode), and an expensive optical coupler is not needed, so that the cost is greatly reduced.
The embodiment also provides a heating product, in particular to a heating pad. Specifically, the heating pad applies a non-optical coupling temperature control circuit with the PTC and NTC characteristic heating wire.
Of course, the heating product can also be a common heating product such as an electric blanket, a pet mat or a dinner plate heating mat and the like according to the requirement.
Although the preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that modifications and variations of the present invention are possible to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

  1. A non-optical coupling temperature control circuit of heating wires with PTC and NTC characteristics, comprising:
    a PTC constant temperature control circuit, a heating wire (402) with PTC/NTC characteristic and a heating control switch (401), wherein the heating control switch (401) is connected with the heating wire (402); wherein, the heating control switch (401) is a main bidirectional controllable silicon;
    an NTC over-temperature protection circuit;
    a drive circuit;
    a DC power supply circuit having a power supply voltage terminal (V) and a ground terminal (GND); and the number of the first and second groups,
    a Microcontroller (MCU) for sending a trigger signal to the heating control switch (401);
    the PTC constant temperature control circuit is characterized by further comprising a current sampling resistor (R403), a power voltage end (V) of the direct current power supply circuit is connected with a live wire (L) of the alternating current power supply, and a first main end of the heating control switch (401) is connected with the live wire (L) of the alternating current power supply through the current sampling resistor (R403).
  2. 2. The non-optical coupling temperature control circuit of the PTC and NTC characteristic heating wire according to claim 1, wherein the DC power supply circuit comprises a current limiting resistor (R201), a high voltage capacitor (C202), a first resistor (R203), a first diode (D204), a second diode (D205), a voltage regulator (D206), a first capacitor (C207), a second capacitor (C208), and a second resistor (R209), a first end of the second resistor (R209) is connected to the live wire (L) of the AC power supply through a temperature fuse (FU 101), a second end of the second resistor (R209) is connected to the Ground (GND), a first pole of the second capacitor (C208) is connected to a first end of the second resistor (R209), a second pole of the second capacitor (C208) is connected to the Ground (GND), a positive pole of the first capacitor (C207) is connected to a first end of the second resistor (R209), a negative pole of the first capacitor (C207) is connected to the Ground (GND), and a negative pole of the voltage regulator (D) is connected to the first end of the first resistor (R209) and the second resistor (D) is connected to the ground (D) and the first end of the second resistor (R209); the anode of the second diode (D205) is connected with the anode of the voltage regulator tube (D206), the cathode of the second diode (D205) is connected with the anode of the first diode (D204), and the cathode of the first diode (D204) is connected with the cathode of the voltage regulator tube (D206); the first end of the current limiting resistor (R201) is connected with a zero line (N) of an alternating current power supply through a current fuse (FU 100), the second end of the current limiting resistor (R201) is connected with the anode of a first diode (D204) through a high-voltage capacitor (C202), and a first resistor (R203) is connected with the two ends of the high-voltage capacitor (C202) in parallel.
  3. 3. A non-optical coupling temperature control circuit of a PTC and NTC characteristic HEAT generating line according to claim 2, wherein the Microcontroller (MCU) has a HEAT signal terminal, a UR signal terminal and a SYN signal terminal, the PTC constant temperature control circuit further comprises a third resistor (R404), a third capacitor (C405), a fourth resistor (R801), a fifth resistor (R901), a sixth resistor (R902) and a filter capacitor (C903); the first end of the heating control switch (401) is connected with the first end of the current sampling resistor (R403), the second end of the current sampling resistor (R403) is connected with a live wire (L) of an alternating current power supply through a temperature fuse (FU 101), the second end of the heating control switch (401) is connected with a first plug-in end (H1) of the heating wire (402), and a second plug-in end (H2) of the heating wire (402) is connected with a zero line (N) of the alternating current power supply through a current fuse (FU 100); a first end of the third capacitor (C405) is connected with a first end of the current sampling resistor (R403) through a third resistor (R404), and a second end of the third capacitor (C405) is connected with a second end of the current sampling resistor (R403); wherein a PTC detection point is arranged at the first end of the third capacitor (C405); a first end of the fourth resistor (R801) is connected with a zero line (N) of an alternating current power supply through a current fuse (FU 100), and a second end of the fourth resistor (R801) is connected with a SYN signal end of a Microcontroller (MCU); a first end of a fifth resistor (R901) is connected with a first end of a fourth resistor (R801), and a second end of the fifth resistor (R901) is connected with a UR signal end of a Microcontroller (MCU); a first end of the sixth resistor (R902) is connected with a second end of the fifth resistor (R901), and a second end of the sixth resistor (R902) is connected with + XV direct-current voltage; and a first pole of the filter capacitor (C903) is connected with a second end of the sixth resistor (R902), and a second pole of the filter capacitor (C903) is connected with a UR signal end of the Microcontroller (MCU).
  4. 4. A non-optical coupling temperature control circuit of a PTC and NTC characteristic HEAT line according to claim 3, wherein the driving circuit includes a fourth capacitor (C301), a seventh resistor (R302) and an eighth resistor (R303), a first end of the eighth resistor (R303) is connected to the first end of the HEAT control switch (401), a second end of the eighth resistor (R303) is connected to the third end of the HEAT control switch (401), and a second end of the eighth resistor (R303) is connected to the first pole of the fourth capacitor (C301) through the seventh resistor (R302), and a second pole of the fourth capacitor (C301) is connected to the HEAT signal terminal of the Microcontroller (MCU).
  5. 5. A non-optical coupling temperature control circuit of a heating wire with PTC and NTC characteristics as claimed in claim 4, wherein the NTC over-temperature protection circuit comprises a ninth resistor (R106), a tenth resistor (R107), an eleventh resistor (R108) and a fifth capacitor (C109), a first end of the ninth resistor (R106) is connected to the live wire (L) of the AC power supply through the temperature fuse (FU 101), and a second end of the ninth resistor (R106) is connected to the third connection end (H3) of the heating wire (402); a first end of the tenth resistor (R107) is connected with a first end of the ninth resistor (R106) through the eleventh resistor (R108), a second end of the tenth resistor (R107) is connected with a second end of the ninth resistor (R106), a first pole of the fifth capacitor (C109) is connected with a first end of the eleventh resistor (R108), and a second pole of the fifth capacitor (C109) is connected with a first end of the tenth resistor (R107); wherein, an NTC detection point is arranged on the second pole of the fifth capacitor (C109).
  6. 6. A non-optical coupling temperature control circuit of PTC and NTC characteristic heating wire according to claim 5, further comprising a shift adjusting circuit connected to a Micro Controller Unit (MCU).
  7. 7. The non-optical coupling temperature control circuit of the PTC and NTC characteristic heating wire according to claim 6, further comprising a gear indication circuit for indicating a gear state, wherein the gear indication circuit is connected to a Microcontroller (MCU).
  8. 8. A non-optical coupling temperature control circuit of PTC and NTC characteristic heating wire according to any one of claims 3 to 7, characterized in that the + XV DC voltage is +5V DC voltage, the voltage input terminal of the Microcontroller (MCU) is connected with +5V DC voltage, the first terminal of the second resistor (R209) is connected with +5V DC voltage.
  9. 9. A heat-generating product, characterized in that a non-optical coupling temperature control circuit having a PTC and NTC characteristic heat-generating wire according to any one of claims 1 to 8 is applied.
  10. 10. The heating product according to claim 9, wherein the heating product is an electric blanket or a pet mat or a dining plate heating mat.
CN202223123935.8U 2022-11-23 2022-11-23 Non-optical coupling temperature control circuit of PTC (positive temperature coefficient) and NTC (negative temperature coefficient) characteristic heating wire and heating product Active CN218886478U (en)

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CN202223123935.8U CN218886478U (en) 2022-11-23 2022-11-23 Non-optical coupling temperature control circuit of PTC (positive temperature coefficient) and NTC (negative temperature coefficient) characteristic heating wire and heating product

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CN202223123935.8U CN218886478U (en) 2022-11-23 2022-11-23 Non-optical coupling temperature control circuit of PTC (positive temperature coefficient) and NTC (negative temperature coefficient) characteristic heating wire and heating product

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