Control circuit of ceramic heating element

Abstract

The utility model relates to a control circuit of a ceramic heating body. The control circuit comprises a power supply circuit. The sub-control circuit inputs alternating current mains supply and is connected with a heating body, and the heating body is connected with a current detection circuit; the sub-control circuit and the current detection circuit are both connected with the main control chip; when in use, the power supply circuit inputs alternating-current mains supply and then rectifies and outputs 5V direct current to provide power supply for the main control chip, and the main control chip controls the working gear of the heating body and pulse width modulation temperature regulation through the sub-control circuit and controls the working gear of the heating body according to first voltage alternating-current mains supply or second voltage alternating-current mains supply. And performing pulse width modulation temperature regulation on the heating body according to the working temperature of the heating body, and performing overcurrent protection on the heating body according to the working current of the heating body, therefore, accurate temperature control of the heating body is realized, and the device is adaptive to input of various power supply voltages, over-current protection, over-temperature protection and the like. And the circuit is high in safety, low in cost and small in size, and can be embedded into a small article for use.

Description

Technical Field

[0001] This utility model relates to the field of temperature control circuit technology, and more specifically, to a control circuit for a ceramic heating element. Background Technology

[0002] Most existing temperature control circuits directly control the temperature through thermal switches, which have poor safety, low accuracy (with an error of 5%), and cannot meet the application requirements of precise temperature control scenarios, nor can they be used with 110V AC power. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a control circuit for a ceramic heating element that can be adapted to multiple power supply voltages, has high-precision temperature control, low cost, small size, and high safety, in view of the above-mentioned defects of the prior art.

[0004] The technical solution adopted by this utility model to solve its technical problem is:

[0005] A control circuit for a ceramic heating element is constructed, including a power supply circuit; wherein, a sub-control circuit is input with AC mains power, the sub-control circuit is connected to a heating element, and the heating element is connected to a current detection circuit; both the sub-control circuit and the current detection circuit are connected to a main control chip.

[0006] The power supply circuit receives the AC mains power and rectifies it to output 5V DC power to provide power to the main control chip. The AC mains power includes a first voltage and a second voltage.

[0007] The main control chip controls the working level and pulse width modulation temperature adjustment of the heating element through the sub-control circuit. The working level of the heating element includes level one and level two.

[0008] The main control chip also detects the operating current of the heating element through the current detection circuit and the operating temperature of the heating element through a thermistor, the thermistor being connected to the main control chip;

[0009] The main control chip controls the operating level of the heating element according to the first voltage or the second voltage of the AC mains power, performs pulse width modulation temperature adjustment on the heating element according to its operating temperature, and provides overcurrent protection for the heating element according to its operating current.

[0010] The control circuit for the ceramic heating element of this utility model further includes: a zero-point detection circuit, which is connected to the AC mains power supply and the main control chip respectively;

[0011] The zero-point detection circuit detects whether the AC mains power is at zero point. When the AC mains power is at zero point, the main control chip controls the sub-control circuit or the main control circuit to stop working.

[0012] The control circuit for the ceramic heating element of this utility model further includes: a voltage detection circuit, which is connected to the AC mains power and the main control chip respectively;

[0013] The voltage detection circuit detects whether the AC mains power is a first voltage AC mains power or a second voltage AC mains power. When the AC mains power is the first voltage AC mains power, the main control chip controls the heating element to operate at level one. When the AC mains power is the second voltage AC mains power, the main control chip controls the heating element to operate at level two.

[0014] The control circuit for the ceramic heating element of this utility model includes a main control circuit connected in series between the AC mains power supply and the sub-control circuit. The main control circuit controls the on / off state of the AC mains power input to the sub-control circuit and is controlled by the main control chip.

[0015] The control circuit of the ceramic heating element of this utility model includes a temperature modulation switch or a self-resetting temperature fuse connected in series between the AC mains power and the main control circuit.

[0016] The temperature modulation switch or self-resetting temperature fuse detects the temperature of the heating element and disconnects and then self-resets after overheating.

[0017] In the control circuit of the ceramic heating element of this utility model, a varistor is connected in parallel on the live wire and the neutral wire of the AC mains power supply.

[0018] The varistor is used for overvoltage protection.

[0019] The control circuit of the ceramic heating element of this utility model includes a main control chip connected to a negative ion generator control circuit, which controls the negative ion generator to work or stop working.

[0020] The control circuit for the ceramic heating element of this utility model includes a main control chip that is also connected to a button control circuit or a display screen.

[0021] The button control circuit is used for function settings and switching;

[0022] The display screen is used to display temperature, countdown, function codes, and prompt codes, or one or more of these.

[0023] The control circuit for the ceramic heating element of this utility model, wherein both the sub-control circuit and the main control circuit are controlled by thyristors.

[0024] The beneficial effects of this utility model are as follows: When in use, the power supply circuit inputs AC mains power and rectifies it to output 5V DC power to provide power to the main control chip. The main control chip controls the working level of the heating element and pulse width modulation temperature adjustment through the sub-control circuit. The main control chip controls the working level of the heating element according to the first voltage AC mains power or the second voltage AC mains power, and performs pulse width modulation temperature adjustment on the heating element according to the working temperature of the heating element. It also provides overcurrent protection for the heating element according to the working current of the heating element. Thus, it achieves precise temperature control of the heating element, adapts to the input of multiple power supply voltages, and provides overcurrent protection, overtemperature protection, etc. It is also highly safe, has low circuit cost, small size, and can be embedded in small products. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the utility model will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a circuit diagram of the power supply circuit, sub-control circuit, main control circuit, current detection circuit, voltage detection circuit, and zero-point detection circuit of the control circuit of the ceramic heating element in a preferred embodiment of this utility model.

[0027] Figure 2 This is a circuit diagram of the main control chip of the control circuit of the ceramic heating element in a preferred embodiment of the present invention.

[0028] Figure 3 This is a circuit diagram of the thermistor in the control circuit of the ceramic heating element according to a preferred embodiment of the present invention.

[0029] Figure 4 This is a circuit diagram of the negative ion generator control circuit of the ceramic heating element control circuit of a preferred embodiment of this utility model.

[0030] Figure 5 This is a circuit diagram of the button control circuit of the control circuit of the ceramic heating element in a preferred embodiment of the present invention.

[0031] Figure 6 This is a circuit diagram of the display screen for the control circuit of the ceramic heating element in a preferred embodiment of this utility model. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, a clear and complete description will be provided below in conjunction with the technical solutions in the embodiments of this utility model. Obviously, the described embodiments are some, but not all, embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0033] The control circuit of the ceramic heating element in the preferred embodiment of this utility model is as follows: Figure 1 As shown, see also Figures 2 to 6 The circuit includes a power supply circuit 100; wherein, the sub-control circuit 200 is input with AC mains power, and the sub-control circuit 200 is connected to one or more heating elements M2, and the heating elements M2 are connected to a current detection circuit 300; both the sub-control circuit 200 and the current detection circuit 300 are connected to the main control chip U1.

[0034] The power supply circuit 100 takes in AC mains power and rectifies it to output 5V DC power to provide power to the main control chip U1 (power supply circuit 100 outputs 5V DC power). The AC mains power includes a first voltage (110V) and a second voltage (220V).

[0035] The main control chip U1 controls the operating level and pulse width modulation temperature adjustment of the heating element M2 through the sub-control circuit 200. The operating level of the heating element M2 includes level one and level two. The resistance values ​​of the heating element M2 at level one and level two are different to adapt to the operation of the first voltage and the second voltage. Compared with the heating element M2 that uses the same resistance value for both voltages, it avoids overcurrent burnout and reduces costs.

[0036] The main control chip U1 also detects the operating current of the heating element M2 through the current detection circuit 300, and detects the operating temperature of the heating element M2 through the thermistor NTC, and performs over-temperature protection for the heating element M2 based on the temperature of the heating element M2. The thermistor NTC is connected to the main control chip U1. The main control chip U1 supports analog input.

[0037] The main control chip U1 controls the working level of the heating element M2 according to the first voltage AC mains power or the second voltage AC mains power (the voltage detection circuit 500 can identify whether the AC mains power is the first voltage AC mains power or the second voltage AC mains power for automatic adjustment, or the button control circuit 800 can manually adjust the level to meet different usage needs), and performs pulse width modulation temperature adjustment on the heating element M2 according to the working temperature of the heating element M2, and performs overcurrent protection on the heating element M2 according to the working current of the heating element M2.

[0038] During operation, the power supply circuit 100 inputs AC mains power and rectifies it to output 5V DC power to provide power to the main control chip U1. The main control chip U1 controls the operating level and pulse width modulation temperature adjustment of the heating element M2 through the sub-control circuit 200. The main control chip U1 controls the operating level of the heating element M2 according to the first voltage AC mains power or the second voltage AC mains power, and performs pulse width modulation temperature adjustment on the heating element M2 according to its operating temperature. It also provides overcurrent protection for the heating element M2 according to its operating current. This achieves precise temperature control of the heating element M2, adapts to multiple power supply voltage inputs, and provides overcurrent and overtemperature protection. It is also highly safe, has low circuit cost, and is small in size, making it suitable for use in small products.

[0039] like Figure 1 and Figure 2 As shown, it also includes: a zero-point detection circuit 400, which is connected to the AC mains power and the main control chip U1 respectively;

[0040] Zero-point detection circuit 400 detects whether the AC mains power is at zero point. When the AC mains power is at zero point, the main control chip U1 controls the sub-control circuit 200 or the main control circuit 600 to stop working, thus meeting the control requirements of the thyristor.

[0041] like Figure 1 and Figure 2 As shown, it also includes: a voltage detection circuit 500, which is connected to the AC mains power and the main control chip U1 respectively;

[0042] The voltage detection circuit 500 detects whether the AC mains power is a first voltage AC mains power or a second voltage AC mains power. When the AC mains power is a first voltage AC mains power, the main control chip U1 controls the heating element M2 to operate at the first level. When the AC mains power is a second voltage AC mains power, the main control chip U1 controls the heating element M2 to operate at the second level. The voltage detection circuit 500 performs voltage detection and identifies whether the AC mains power is a first voltage AC mains power or a second voltage AC mains power based on the detected voltage.

[0043] like Figure 1 As shown, a main control circuit 600 is connected in series between the AC mains power supply and the sub-control circuit 200. The main control circuit 600 controls the on / off of the AC mains power input of the sub-control circuit 200 and is controlled by the main control chip U1; it performs secondary power-off protection and performs double power-off on the heating element M2, which improves safety.

[0044] like Figure 1 As shown, a temperature modulation switch (not shown in the figure) or a self-resetting temperature fuse TF1 is connected in series between the AC mains power and the main control circuit 600.

[0045] The temperature modulation switch or self-resetting temperature fuse TF1 detects the temperature of the heating element M2 and automatically resets after disconnecting due to over-temperature; this dual over-temperature protection improves safety.

[0046] like Figure 1 As shown, a varistor MOV1 is connected in parallel on the live wire and the neutral wire of the AC mains power supply.

[0047] The MOV1 varistor is used for overvoltage protection to improve safety.

[0048] like Figure 2 and Figure 4 As shown, the main control chip U1 is also connected to a negative ion generator control circuit 700, which controls the negative ion generator (not shown in the figure) to work or stop working; to meet different usage needs, wherein the negative ion generator can be other electrical appliances or components.

[0049] like Figure 2 and Figure 5 as well as Figure 6 As shown, the main control chip U1 is also connected to a button control circuit 800 or a display LED1;

[0050] The button control circuit 800 is used for function setting and switching;

[0051] LED1 is used to display temperature, countdown, function codes, and prompt codes, thereby improving the level of intelligence.

[0052] like Figure 1 As shown, both the sub-control circuit 200 and the main control circuit 600 are controlled by thyristors; they meet the control requirements of AC, can control large currents, and have high safety.

[0053] Furthermore, the heating element M2 is composed of one or more heating wires (not shown in the figure). The heating wire M2 includes a first heating coil and a second heating coil. One end of the first heating coil is connected to one end of the second heating coil and is the common terminal of the heating wire M2. The other end of the first heating coil is the first input terminal of the heating wire M2, and the other end of the second heating coil is the second input terminal of the heating wire M2. That is, when the AC mains input is 110V, the main control chip U1 controls the first heating coil of the heating wire M2 to work through the sub-control circuit 200. Conversely, when the AC mains input is 220V, it controls the second heating coil of the heating wire M2 to work.

[0054] like Figures 3 to 6 As shown, the main control circuit 600 includes: a first thyristor optocoupler U6 and a first thyristor TR1, and the sub-control circuit 200 includes: a second thyristor optocoupler U5, a third thyristor optocoupler U4, a second thyristor TR2, and a third thyristor TR4.

[0055] One end of the self-resetting thermal fuse TF1 is connected to the live wire of the AC mains, and the other end is connected to the first main electrode of the first thyristor TR1. The second main electrode of the first thyristor TR1 is connected to the first main electrode of the second thyristor TR2 and the first main electrode of the third thyristor TR4, respectively. The second main electrode of the second thyristor TR2 is connected to the first input terminal of the heating wire M2, and the second main electrode of the third thyristor TR4 is connected to the second input terminal of the heating wire M2.

[0056] The gate of the first thyristor TR1 is connected to a first resistor R31 and a second resistor R30. The other end of the first resistor R31 is connected to the first main electrode of the backlight detector of the first thyristor optocoupler U6. The second main electrode of the backlight detector of the first thyristor optocoupler U6 is connected to the gate of the first thyristor TR1. The other end of the second resistor R30 is connected to the second main electrode of the first thyristor TR1.

[0057] The second main electrode of the first thyristor TR1 is connected to a third resistor R9. The other end of the third resistor R9 is connected to the first main electrode of the backlight detector of the second SCR optocoupler U5 and the first main electrode of the backlight detector of the third SCR optocoupler U4, respectively. The second main electrode of the backlight detector of the second SCR optocoupler U5 is connected to the gate of the second thyristor TR2 and is also connected to a fourth resistor R10. The other end of the fourth resistor R10 is connected to the second main electrode of the second thyristor TR2. The second main electrode of the backlight detector of the third SCR optocoupler U4 is connected to the gate of the third thyristor TR4 and is also connected to a fifth resistor R24. The other end of the fifth resistor R24 ​​is connected to the second main electrode of the third thyristor TR4.

[0058] The common terminal of the heating wire M2 is connected to a current sensing resistor R25 and a sixth resistor R26. The other end of the current sensing resistor R25 is connected to the neutral wire of the AC mains, and the other end of the sixth resistor R26 is connected to the main control chip. The current sensing resistor R25 and the sixth resistor R26 constitute the current sensing circuit 300.

[0059] The positive terminals of the LEDs of the first SCR optocoupler U6, the second SCR optocoupler U5, and the third SCR optocoupler U4 are all connected to the positive terminal of a 5V DC power supply. The negative terminals of the LEDs of the first SCR optocoupler U6, the second SCR optocoupler U5, and the third SCR optocoupler U4 are all connected to the main control chip. The circuit is simple, low-cost, and small in size. The use of SCR optocouplers for high and low voltage isolation improves the stability of the circuit.

[0060] like Figure 1 and Figure 2As shown, the thermistor NTC is connected to the negative terminal of the 5V DC power supply and the other end is connected to the main control chip. It is also connected to the seventh resistor R34, and the other end of the seventh resistor R34 is connected to the positive terminal of the 5V DC power supply.

[0061] It also includes: voltage detection circuit 500 and zero-point detection circuit 400. Voltage detection circuit 500 includes: eighth resistor R8 and ninth resistor R11. Zero-point detection circuit 400 includes: tenth resistor R27 and first diode Z1.

[0062] The eighth resistor R8 is connected to the live wire of the AC mains, and the other end is connected to the main control chip and the ninth resistor R11. The other end of the ninth resistor R11 is connected to the neutral wire of the AC mains.

[0063] The tenth resistor R27 is connected to the live wire of the AC mains, and the other end is connected to the main control chip and the positive terminal of the first diode Z1. The negative terminal of the first diode Z1 is connected to the neutral wire of the AC mains. The voltage detection circuit 500 is used to detect the voltage of the AC mains and determines whether it is a 110V AC input or a 220V AC input through the main control chip. The zero-point detection circuit 400 detects whether the waveform of the AC mains is at zero. When it is at zero, the main control chip can control the main control circuit 600 or the sub-control circuit 200 to disconnect.

[0064] like Figure 1 As shown, the power supply circuit 210 includes: a switching power supply chip U2, a second diode D3, a third diode D5, a fourth diode D4, a first capacitor C11, an eleventh resistor R4, and an inductor L3.

[0065] The DRAI N terminal of the switching power supply chip U2 is connected to the negative terminal of the second diode D3 and the second capacitor C6. The positive terminal of the second diode D3 is connected to the live wire of the AC mains, and the other end of the second capacitor C6 is connected to the neutral wire of the AC mains.

[0066] The CS terminal of the switching power supply chip U2 is connected to the eleventh resistor R4. The other end of the eleventh resistor R4 is connected to the inductor L3, the first capacitor C11, and the negative terminal of the fourth diode D4. The other end of the inductor L3 is connected to the neutral line of the AC mains. The other end of the first capacitor C11 is connected to the VDD terminal of the switching power supply chip U2.

[0067] The VDD terminal of the switching power supply chip U2 is connected to the negative terminal of the third diode D5, and the positive terminal of the third diode D5 is connected to the neutral wire of the AC mains.

[0068] A third capacitor C2 is connected in parallel between the neutral wire of the AC mains power and the positive terminal of the fourth diode D4. The neutral wire of the AC mains power is the positive output terminal of the 5V DC power, and the positive terminal of the fourth diode D4 is the negative output terminal of the 5V DC power. This meets the working requirements of the switching power supply chip U2, and the circuit is simple, low in cost, and small in size. Among them, the third diode D5 is used to provide DC power to the VDD terminal of the power switch chip, the fourth diode D4 is used for rectification, and the inductor L3 works with the first capacitor C11 to filter. The inductor L3 also plays the role of blocking DC and working with the fourth diode D4 to circulate the 5V DC power.

[0069] like Figure 1 As shown, the switching power supply chip U2, model KP3111, can operate directly with a 220V input voltage, eliminating the need for a transformer and reducing cost and product size.

[0070] like Figure 1 As shown, a twelfth resistor R3 is connected in series between the positive terminal of the second diode D3 and the live wire of the AC mains to limit the current.

[0071] like Figure 1 As shown, a varistor MOV1 is connected in parallel between the live wire and the neutral wire of the AC mains for overvoltage protection.

[0072] like Figure 1 and Figure 4 As shown, the main control chip U1 is also connected to a second thyristor TR3. The gate of the second thyristor TR3 is connected to a thirteenth resistor R29, and the other end of the thirteenth resistor R29 is connected to the P3.7 terminal of the main control chip U1. The second thyristor TR3 and the thirteenth resistor R29 constitute the negative ion generator control circuit 700. The first main electrode of the second thyristor TR3 is connected to the neutral wire of the negative ion generator, and the second main electrode is connected to the neutral wire of the AC mains. The live wire of the negative ion generator is connected to the live wire of the AC mains. The circuit is simple and low in cost.

[0073] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A control circuit for a ceramic heating element, comprising a power supply circuit and a sub-control circuit; characterized in that, The sub-control circuit is input with AC mains power, and a heating element is connected to the sub-control circuit. The heating element is connected to a current detection circuit. Both the sub-control circuit and the current detection circuit are connected to the main control chip. The power supply circuit inputs the AC mains power and rectifies it to output 5V DC power to provide power to the main control chip. The AC mains power includes a first voltage and a second voltage. The main control chip controls the working level and pulse width modulation temperature adjustment of the heating element through the sub-control circuit. The working level of the heating element includes level one and level two. The main control chip also detects the operating current of the heating element through the current detection circuit and the operating temperature of the heating element through a thermistor, the thermistor being connected to the main control chip; The main control chip controls the operating level of the heating element according to the first voltage or the second voltage of the AC mains power, performs pulse width modulation temperature adjustment on the heating element according to its operating temperature, and provides overcurrent protection for the heating element according to its operating current.

2. The control circuit for the ceramic heating element according to claim 1, characterized in that, Also includes: A zero-point detection circuit, which is connected to the AC mains power supply and the main control chip respectively; The zero-point detection circuit detects whether the AC mains power is at zero point. When the AC mains power is at zero point, the main control chip controls the sub-control circuit or the main control circuit to stop working.

3. The control circuit for the ceramic heating element according to claim 1, characterized in that, Also includes: A voltage detection circuit is connected to both the AC mains power supply and the main control chip. The voltage detection circuit detects whether the AC mains power is a first voltage AC mains power or a second voltage AC mains power. When the AC mains power is the first voltage AC mains power, the main control chip controls the heating element to operate at level one. When the AC mains power is the second voltage AC mains power, the main control chip controls the heating element to operate at level two.

4. The control circuit for the ceramic heating element according to claim 2, characterized in that, The main control circuit is connected in series between the AC mains power supply and the sub-control circuit. The main control circuit controls the on / off state of the AC mains power input of the sub-control circuit and is controlled by the main control chip.

5. The control circuit for the ceramic heating element according to claim 4, characterized in that, A temperature modulation switch or a self-resetting temperature fuse is connected in series between the AC mains power supply and the main control circuit. The temperature modulation switch or self-resetting temperature fuse detects the temperature of the heating element and disconnects and then self-resets after overheating.

6. The control circuit for the ceramic heating element according to claim 1, characterized in that, A varistor is connected in parallel on the live wire and the neutral wire of the AC mains power supply; The varistor is used for overvoltage protection.

7. The control circuit for the ceramic heating element according to claim 1, characterized in that, The main control chip is also connected to a negative ion generator control circuit, which controls the negative ion generator to work or stop working.

8. The control circuit for the ceramic heating element according to claim 1, characterized in that, The main control chip is also connected to a button control circuit or a display screen; The button control circuit is used for function settings and switching; The display screen is used to display temperature, countdown, function codes, and prompt codes, or one or more of these.

9. The control circuit for the ceramic heating element according to claim 2, characterized in that, Both the sub-control circuit and the main control circuit are controlled by thyristors.

Images