Voltage self-adaptive conversion circuit of heating electric appliance

Abstract

The utility model discloses a voltage self-adaptive conversion circuit of a heating appliance, which comprises a control unit, a heating wire load module and a silicon controlled rectifier control circuit, and the heating wire load module comprises a first heating wire, a second heating wire and a third heating wire. The silicon controlled rectifier control circuit comprises a first silicon controlled rectifier, a second silicon controlled rectifier and a third silicon controlled rectifier; the control unit is used for monitoring input voltage of the heating electric appliance in real time and controlling on and off of each silicon controlled rectifier; when it is detected that the input voltage of the heating electric appliance is within a first voltage input range, the control unit controls the first silicon controlled rectifier to be conducted, controls the second silicon controlled rectifier and the third silicon controlled rectifier to be cut off and controls the first heating wire and the second heating wire to be connected in series; and when the input voltage of the heating electric appliance is detected to be within a second voltage input range, the control unit controls the first silicon controlled rectifier to be cut off, controls the second silicon controlled rectifier and the third silicon controlled rectifier to be switched on, and controls the second heating wire and the third heating wire to be switched on in parallel.

Description

Technical Field

[0001] The utility model relates to the technical field of heating appliances, in particular to a voltage adaptive conversion circuit for a heating appliance. Background Art

[0002] In the prior art, heating appliance products that use resistive loads to generate heat, such as hair dryers, hair dryers, rice cookers, steamers, electric irons, etc., due to different voltage standards adopted by each country, therefore, for the grid voltages of different countries and regions, heating appliance products with different voltages need to be designed accordingly. A single product is limited to use in countries and regions that adopt the same voltage standard and cannot be used globally in all different countries and regions. For example, the voltage of products with European specifications / CCC national standards is 220 - 240VAC, and the voltage of products with American and Japanese specifications is 100 - 120VAC. Suppose the normal power of the heating wire inside the heating appliance is 1500W when operating at 100 - 120VAC. If it is directly operated at 220 - 240Vac voltage, the power will reach 6000W, which will instantly damage the product and pose risks such as fire. Therefore, heating appliances with these two voltages of 220 - 240VAC and 100 - 120VAC are not interchangeable.

[0003] Due to different voltage standards adopted by each country, existing heating appliances cannot adapt to the grid voltages of different countries and regions globally. The heating appliances carried by travelers cannot be used globally in different countries and regions, resulting in poor product versatility and inconvenience in use. Summary of the Invention

[0004] The technical problem to be solved by the utility model is to provide a voltage adaptive conversion circuit for a heating appliance, so that the heating appliance can adapt to the grid voltages of different countries and regions globally, and the product has strong versatility.

[0005] To solve the above technical problem, the utility model adopts the following technical solutions:

[0006] A voltage adaptive conversion circuit for a heating appliance, comprising a control unit, a heating wire load module, and a thyristor control circuit. The heating wire load module includes a first heating wire, a second heating wire, and a third heating wire. The thyristor control circuit includes a first thyristor, a second thyristor, and a third thyristor. The control unit is used to monitor the input voltage of the heating appliance in real time and control the conduction and cut-off of each thyristor. When it is detected that the input voltage of the heating appliance is within the first voltage input range, the control unit controls the first thyristor to conduct and controls the second thyristor and the third thyristor to cut off. The first heating wire and the second heating wire are connected in series to conduct, so as to increase the load resistance. When it is detected that the input voltage of the heating appliance is within the second voltage input range, the control unit controls the first thyristor to cut off and controls the second thyristor and the third thyristor to conduct. The second heating wire and the third heating wire are connected in parallel to conduct, so as to reduce the load resistance. At the same time, the control unit controls one of the first thyristor and the third thyristor to conduct and the other to cut off.

[0007] Preferably, the heating wire load module further includes a thermal fuse, a temperature controller, and a thermistor. The thermistor is used to monitor the temperature of the heating wire load module in real time and feedback the temperature information to the control unit. The control unit controls the conduction and disconnection of the temperature controller according to the temperature information fed back by the thermistor.

[0008] Preferably, one end of the second heating wire is connected to the AC live wire terminal, the other end of the second heating wire is connected to one end of the first heating wire, and the other end of the first heating wire is connected to the AC neutral wire terminal through the first thyristor; the connection point between the first heating wire and the second heating wire is connected to the AC neutral wire terminal through the second thyristor; one end of the third heating wire is connected to the AC live wire terminal, and the other end is connected to the AC neutral wire terminal through the third thyristor.

[0009] Preferably, one end of the second heating wire is connected to the AC live wire terminal, the other end of the second heating wire is connected to one end of the first heating wire through the first thyristor, and the other end of the first heating wire is connected to the AC neutral wire terminal; the connection point between the first thyristor and the second heating wire is connected to the AC neutral wire terminal through the second thyristor; one end of the third heating wire is connected to the AC live wire terminal, and the other end is connected to the AC neutral wire terminal through the third thyristor.

[0010] Preferably, the thyristor control circuit includes a first thyristor optocoupler, a second thyristor optocoupler, and a third thyristor optocoupler; the anode of the input end of the first thyristor optocoupler is connected to a DC power supply, the cathode of the input end of the first thyristor optocoupler is connected to the control unit through a resistor R4, one pin of the output end of the first thyristor optocoupler is connected to the control electrode of the first thyristor, and the other pin of the output end of the first thyristor optocoupler is connected to the connection point between the first thyristor and the first heating wire through a resistor R3; the anode of the input end of the second thyristor optocoupler is connected to a DC power supply, the cathode of the input end of the second thyristor optocoupler is connected to the control unit through a resistor R1, one pin of the output end of the second thyristor optocoupler is connected to the control electrode of the second thyristor, and the other pin of the output end of the second thyristor optocoupler is connected to the zero line end of the alternating current through a resistor R2; the anode of the input end of the third thyristor optocoupler is connected to the control unit through a resistor R6, the cathode of the input end of the third thyristor optocoupler is connected to the control unit, one pin of the output end of the third thyristor optocoupler is connected to the control electrode of the third thyristor, and the other pin of the output end of the third thyristor optocoupler is connected to the connection point between the third thyristor and the third heating wire through a resistor R5.

[0011] Preferably, the control unit outputs a first signal to the cathode of the input end of the first thyristor optocoupler and the anode of the input end of the third thyristor optocoupler, outputs a second signal to the cathode of the input end of the second thyristor optocoupler, and outputs a third signal to the cathode of the input end of the third thyristor optocoupler; when it is detected that the input voltage of the heating appliance is within the first voltage input range, the first signal is at a low level, the second signal and the third signal are at a high level, the first thyristor conducts, and the second thyristor and the third thyristor are cut off; when it is detected that the input voltage of the heating appliance is within the second voltage input range, the first signal is at a high level, the second signal and the third signal are at a low level, the first thyristor is cut off, and the second thyristor and the third thyristor conduct.

[0012] Preferably, the first thyristor, the second thyristor, and the third thyristor all adopt bidirectional thyristors.

[0013] Preferably, the resistance values of the first heating wire, the second heating wire, and the third heating wire are equal.

[0014] Preferably, the voltage range defined by the first voltage input range is 220 - 240VAC; the voltage range defined by the second voltage input range is 100 - 120VAC.

[0015] Preferably, the heating appliance is a hair dryer, a hair blower, a rice cooker, a steam engine, or an electric iron.

[0016] The beneficial technical effects of the present utility model are as follows: The voltage adaptive conversion circuit of the above heating appliance can adaptively adjust the thyristor according to the change of the input voltage to realize the adjustment of the load resistance, so that the heating wire of the heating wire load module can work normally within different voltage input ranges without being burned out, thereby enabling the heating appliance to adapt to the grid voltages of different countries and regions around the world. The heating appliances carried by travelers can be used universally in different countries and regions around the world, and the product has strong universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the circuit schematic diagram of the voltage adaptive conversion circuit of the heating appliance of the present utility model;

[0018] Figure 2 is Figure 1 the equivalent circuit diagram of. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To enable those of ordinary skill in the art to more clearly understand the purpose, technical solutions and advantages of the present utility model, the present utility model will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] The present utility model provides a voltage adaptive conversion circuit for a heating appliance, which is applied to a heating appliance, and the heating appliance is a hair dryer, a hair blower, a rice cooker, a steam engine, an electric iron or other heating appliances.

[0021] As Figure 1-2 shown, in an embodiment of the present utility model, the voltage adaptive conversion circuit of the heating appliance includes a control unit, a heating wire load module 10 and a thyristor control circuit 20. The heating wire load module 10 includes a first heating wire HT1, a second heating wire HT2 and a third heating wire HT3. The thyristor control circuit 20 includes a first thyristor Q1, a second thyristor Q2 and a third thyristor Q3. The control unit is used to monitor the input voltage of the heating appliance in real time and control the conduction and cut-off of each thyristor. When it is detected that the input voltage of the heating appliance is within the first voltage input range, the control unit controls the first thyristor Q1 to conduct and controls the second thyristor Q2 and the third thyristor Q3 to cut off. The first heating wire HT1 and the second heating wire HT2 are connected in series and conduct to increase the load resistance. When it is detected that the input voltage of the heating appliance is within the second voltage input range, the control unit controls the first thyristor Q1 to cut off and controls the second thyristor Q2 and the third thyristor Q3 to conduct. The second heating wire HT2 and the third heating wire HT3 are connected in parallel and conduct to reduce the load resistance. At the same time, the control unit controls one of the first thyristor Q1 and the third thyristor Q3 to conduct and the other to cut off.

[0022] In this embodiment, the voltage range defined by the first voltage input range is 220 - 240VAC; the voltage range defined by the second voltage input range is 100 - 120VAC.

[0023] The control unit uses an MCU, and the first thyristor Q1, the second thyristor Q2, and the third thyristor Q3 all use bidirectional thyristors and can conduct normally in both directions.

[0024] The resistance values of the first heating wire HT1, the second heating wire HT2, and the third heating wire HT3 are equal. In this embodiment, the resistance value of the heating wire is set to 18Ω, that is, HT1 = HT2 = HT3 = 18Ω. In other embodiments, the resistance value of the heating wire can also be set to other values according to actual needs, and the present utility model does not make any restrictions.

[0025] In this embodiment, one end of the second heating wire HT2 is connected to the AC live wire terminal AC_L, the other end of the second heating wire HT2 is connected to one end of the first heating wire HT1 through the first thyristor Q1, and the other end of the first heating wire HT1 is connected to the AC neutral wire terminal AC_N; the connection point between the first thyristor Q1 and the second heating wire HT2 is connected to the AC neutral wire terminal AC_N through the second thyristor Q2; one end of the third heating wire HT3 is connected to the AC live wire terminal AC_L, and the other end is connected to the AC neutral wire terminal AC_N through the third thyristor Q3. In other embodiments, the heating wires of the heating wire load module 10 can also be wired in other connection manners. For example, one end of the second heating wire HT2 is connected to the AC live wire terminal AC_L, the other end of the second heating wire HT2 is connected to one end of the first heating wire HT1, and the other end of the first heating wire HT2 is connected to the AC neutral wire terminal AC_N through the first thyristor Q1; the connection point between the first heating wire HT1 and the second heating wire HT2 is connected to the AC neutral wire terminal AC_N through the second thyristor Q2; one end of the third heating wire HT3 is connected to the AC live wire terminal AC_L, and the other end is connected to the AC neutral wire terminal AC_N through the third thyristor Q3.

[0026] The thyristor control circuit 20 includes a first thyristor optocoupler U1, a second thyristor optocoupler U1, and a third thyristor optocoupler U3. The anode of the input terminal of the first thyristor optocoupler U1 is connected to the DC power supply (5V). The cathode of the input terminal of the first thyristor optocoupler U1 is connected to the control unit (MCU) through a resistor R4. One pin of the output terminal of the first thyristor optocoupler U1 is connected to the control electrode of the first thyristor Q1, and the other pin of the output terminal of the first thyristor optocoupler U1 is connected to the joint point between the first thyristor Q1 and the first heating wire HT1 through a resistor R3. The anode of the input terminal of the second thyristor optocoupler U2 is connected to the DC power supply (5V). The cathode of the input terminal of the second thyristor optocoupler U2 is connected to the control unit through a resistor R1. One pin of the output terminal of the second thyristor optocoupler U2 is connected to the control electrode of the second thyristor Q2, and the other pin of the output terminal of the second thyristor optocoupler U2 is connected to the AC neutral line terminal AC_N through a resistor R2. The anode of the input terminal of the third thyristor optocoupler U3 is connected to the control unit through a resistor R6, and the cathode of the input terminal of the third thyristor optocoupler U3 is connected to the control unit. One pin of the output terminal of the third thyristor optocoupler U3 is connected to the control electrode of the third thyristor Q3, and the other pin of the output terminal of the third thyristor optocoupler U3 is connected to the joint point between the third thyristor Q3 and the third heating wire HT3 through a resistor R5.

[0027] The control unit (MCU) outputs a first signal HT_Ctrl1 to the cathode of the input terminal of the first thyristor optocoupler U1 and the anode of the input terminal of the third thyristor optocoupler U3, outputs a second signal HT_Ctrl2 to the cathode of the input terminal of the second thyristor optocoupler U2, and outputs a third signal HT_Ctrl3 to the cathode of the input terminal of the third thyristor optocoupler U3. When the first signal HT_Ctrl1 is at a low level, the first thyristor Q1 is turned on through the first thyristor optocoupler U1. When the first signal HT_Ctrl1 is at a high level, the first thyristor Q1 is turned off through the first thyristor optocoupler U1. When the second signal HT_Ctrl2 is at a low level, the second thyristor Q2 is turned on through the second thyristor optocoupler U2. When the second signal HT_Ctrl2 is at a high level, the second thyristor Q2 is turned off through the second thyristor optocoupler U2. When the first signal HT_Ctrl1 is at a high level and the third signal HT_Ctrl3 is at a low level, the third thyristor Q3 is turned on through the third thyristor optocoupler U3. When the first signal HT_Ctrl1 is at a high level and the third signal HT_Ctrl3 is at a high level, the third thyristor Q3 is turned off through the third thyristor optocoupler U3. The first thyristor Q1 and the third thyristor Q3 are interlocked by the first signal HT_Ctrl1, and only one of them is allowed to conduct (turn on) at the same time.

[0028] The working process of the voltage adaptive conversion circuit of the heating appliance of the present utility model is as follows:

[0029] When the input voltage of the heating appliance is detected to be 220 - 240VAC, the MCU outputs a low - level first signal HT_Ctrl1 to the cathode of the input terminal of the first thyristor optocoupler U1 and the anode of the input terminal of the third thyristor optocoupler U3, outputs a high - level second signal HT_Ctrl2 to the cathode of the input terminal of the second thyristor optocoupler U2, and outputs a high - level third signal HT_Ctrl3 to the cathode of the input terminal of the third thyristor optocoupler U3. The first thyristor Q1 conducts, the second thyristor Q2 and the third thyristor Q3 are cut off, and the first heating wire HT1 and the second heating wire HT2 are connected in series and conduct, increasing the load resistance to meet the power demand under high voltage. At this time, the load resistance R = HT1 + HT2 = 36Ω. Calculated with the input voltage of 230VAC, the power of the two groups of heating wires is finally: P = U 2 / R = 230 * 230 / 36 = 1470W.

[0030] When the input voltage of the heating appliance is detected to be 100 - 120VAC, the MCU outputs a high - level first signal HT_Ctrl1 to the cathode of the input terminal of the first thyristor optocoupler U1 and the anode of the input terminal of the third thyristor optocoupler U3, outputs a low - level second signal HT_Ctrl2 to the cathode of the input terminal of the second thyristor optocoupler U2, and outputs a low - level third signal HT_Ctrl3 to the cathode of the input terminal of the third thyristor optocoupler U3. The first thyristor Q1 is cut off, the second thyristor Q2 and the third thyristor Q3 conduct, and the second heating wire HT2 and the third heating wire HT3 are connected in parallel and conduct, reducing the load resistance to meet the power demand under low voltage. At this time, the load resistance R = HT2 * HT3 / (HT2 + HT3) = 9Ω. Calculated with the input voltage of 115VAC, the power of the two groups of heating wires is finally: P = U 2 / R = 115 * 115 / 9 = 1470W.

[0031] The voltage adaptive conversion circuit of the heating appliance in this embodiment can adaptively adjust the thyristor according to the change of the input voltage to realize the adjustment of the load resistance, so that the heating wires of the heating wire load module can work normally within different voltage input ranges without being burned out, so that the heating appliance can adapt to the grid voltages of different countries and regions around the world. The heating appliances carried by travelers can be used in different countries and regions around the world, and the product has strong universality. In addition, the first thyristor Q1 and the third thyristor Q3 are interlocked by the first signal HT_Ctrl1, and only one of them is allowed to conduct (turn on) at the same time, which can prevent all thyristors from conducting, thereby providing the safety and reliability of the circuit.

[0032] See again Figure 1 、 2, in a preferred embodiment of the present utility model, the heating wire load module 10 further includes a thermal fuse F1, a thermostat TCO, and a thermistor RT1. The thermistor RT1 is connected to the control unit (MCU) through the P2 port. The thermistor RT1 is used to monitor the temperature of the heating wire load module 10 in real time and feed back the temperature information to the control unit. The control unit controls the conduction and disconnection of the thermostat TCO according to the temperature information fed back by the thermistor RT1 to achieve closed-loop temperature control.

[0033] The above are only the preferred embodiments of the present utility model, and do not impose any formal restrictions on the present utility model. Those skilled in the art can make various equivalent changes and improvements on the basis of the above embodiments. Any equivalent changes or modifications made within the scope of the claims shall fall within the protection scope of the present utility model.

Claims

1. A voltage adaptive conversion circuit for a heating appliance, characterized in that: The invention comprises a control unit, a heating wire load module and a thyristor control circuit, wherein the heating wire load module comprises a first heating wire, a second heating wire and a third heating wire, and the thyristor control circuit comprises a first thyristor, a second thyristor and a third thyristor, and the control unit is used for real-time monitoring of the input voltage of the heating appliance and controlling the conduction and cutoff of each thyristor; When it is detected that the input voltage of the heating appliance is within the first voltage input range, the control unit controls the first thyristor to be turned on, and controls the second thyristor and the third thyristor to be turned off, and the first heating wire and the second heating wire are connected in series to increase the load resistance; When it is detected that the input voltage of the heating appliance is within the second voltage input range, the control unit controls the first thyristor to be turned off, and controls the second thyristor and the third thyristor to be turned on, and the second heating wire and the third heating wire are turned on in parallel to reduce the load resistance; At the same time, the control unit controls one of the first thyristor and the third thyristor to be turned on and the other to be turned off.

2. The voltage adaptive conversion circuit of the heating appliance according to claim 1, characterized in that: The heating wire load module also includes a thermal fuse, a thermostat and a thermistor. The thermistor is used to monitor the temperature of the heating wire load module in real time and feed back the temperature information to the control unit. The control unit controls the thermostat to be turned on and off according to the temperature information fed back by the thermistor.

3. The voltage adaptive conversion circuit of the heating appliance according to claim 1, characterized in that: One end of the second heating wire is connected to the live wire end of the AC power, the other end of the second heating wire is connected to one end of the first heating wire, and the other end of the first heating wire is connected to the neutral wire end of the AC power through the first thyristor; the connection point between the first heating wire and the second heating wire is connected to the neutral wire end of the AC power through the second thyristor; one end of the third heating wire is connected to the live wire end of the AC power, and the other end is connected to the neutral wire end of the AC power through the third thyristor.

4. The voltage adaptive conversion circuit of the heating appliance according to claim 1, characterized in that: One end of the second heating wire is connected to the live wire end of the AC power, and the other end of the second heating wire is connected to one end of the first heating wire through the first thyristor, and the other end of the first heating wire is connected to the neutral wire end of the AC power; the connection point between the first thyristor and the second heating wire is connected to the neutral wire end of the AC power through the second thyristor; one end of the third heating wire is connected to the live wire end of the AC power, and the other end is connected to the neutral wire end of the AC power through the third thyristor.

5. The voltage adaptive conversion circuit of the heating appliance according to claim 3 or 4, characterized in that: The thyristor control circuit includes a first thyristor optocoupler, a second thyristor optocoupler and a third thyristor optocoupler; The anode of the first thyristor optocoupler input end is connected to a DC power supply, the cathode of the first thyristor optocoupler input end is connected to the control unit through a resistor R4, one pin of the first thyristor optocoupler output end is connected to the control electrode of the first thyristor, and the other pin of the first thyristor optocoupler output end is connected to the connection point between the first thyristor and the first heating wire through a resistor R3; The anode of the second thyristor optocoupler input end is connected to the DC power supply, the cathode of the second thyristor optocoupler input end is connected to the control unit through the resistor R1, one pin of the second thyristor optocoupler output end is connected to the control electrode of the second thyristor, and the other pin of the second thyristor optocoupler output end is connected to the AC neutral terminal through the resistor R2; The anode of the third thyristor optocoupler input end is connected to the control unit through resistor R6, the cathode of the third thyristor optocoupler input end is connected to the control unit, one pin of the third thyristor optocoupler output end is connected to the control electrode of the third thyristor, and the other pin of the third thyristor optocoupler output end is connected to the connection point between the third thyristor and the third heating wire through resistor R5.

6. The voltage adaptive conversion circuit of the heating appliance as claimed in claim 5, characterized in that: The control unit outputs a first signal to the cathode of the first thyristor optocoupler input terminal and the anode of the third thyristor optocoupler input terminal, outputs a second signal to the cathode of the second thyristor optocoupler input terminal, and outputs a third signal to the cathode of the third thyristor optocoupler input terminal; When it is detected that the input voltage of the heating appliance is within the first voltage input range, the first signal is at a low level, the second signal and the third signal are at a high level, the first thyristor is turned on, and the second thyristor and the third thyristor are turned off; When it is detected that the input voltage of the heating appliance is within the second voltage input range, the first signal is at a high level, the second signal and the third signal are at a low level, the first thyristor is turned off, and the second thyristor and the third thyristor are turned on.

7. The voltage adaptive conversion circuit of the heating appliance according to claim 1, characterized in that: The first thyristor, the second thyristor and the third thyristor are all bidirectional thyristors.

8. The voltage adaptive conversion circuit of the heating appliance according to claim 1, characterized in that: The resistance values ​​of the first heating wire, the second heating wire and the third heating wire are equal.

9. The voltage adaptive conversion circuit of a heating appliance as claimed in claim 1, characterized in that: The voltage range defined by the first voltage input range is 220-240VAC; the voltage range defined by the second voltage input range is 100-120VAC.

10. The voltage adaptive conversion circuit of the heating appliance according to claim 9, characterized in that: The heating appliance is a hair dryer, a hair dryer, an electric rice cooker, a steam machine or an electric iron.

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