An input voltage adaptive electric heating control device

Abstract

The application discloses an input voltage adaptive electric heating control device and relates to the technical field of home appliances. The device comprises a detection unit, a control unit and an output unit. The detection unit is used for outputting a level combination signal according to a comparison result of an input voltage and a control voltage. The control unit is used for performing logical judgment according to an input starting signal and the level combination signal and outputting a control voltage signal. The output unit comprises an AC input live wire, an electric heating device and an AC input zero wire to form a series loop. A switching device is further connected in series in the series loop, and the switching device is controlled to be turned on or turned off by the control voltage signal. The application can adapt to different input voltages, does not need to switch a heating resistor, has a simple circuit, does not change electric heating selection and assembly and has low cost.

Description

Technical Field

[0001] This invention relates to the field of home appliance technology, specifically to an input voltage adaptive electric heating control device. Background Technology

[0002] Household appliances that use electric heating, such as refrigerator defrosting electric heating, air conditioner auxiliary electric heating, and washing machine drying electric heating, typically use different controllers and electric heaters matched to the local grid voltage (e.g., 200-240Vac or 100-120Vac), usually in a one-to-one relationship. This matching relationship becomes limiting in areas with large input voltage variations. For example, in Brazil, there are two grids: 127Vac and 220Vac. Using the currently used one-to-one matching method restricts user choice and usage, and also carries the risk of product damage and economic loss due to incorrect input voltage. To address this need, the requirement and technology for adaptive input voltage have emerged. Existing adaptive control of electric heating devices has two methods: (i) using two sets of heating resistors, selecting one or both sets to operate based on the detected voltage level; (ii) chopping the AC power at 220Vac input, activating the heating resistors for half the time. The disadvantage of method (i) is that it requires two sets of heating resistors and a switching circuit, resulting in complex circuitry, complicated assembly and installation, and increased costs. The disadvantage of scheme (2) is that the heating resistor is turned on for half the time. When the input is 220Vac, the electric heating is subjected to a high voltage and has a large instantaneous power, which affects the life of the heater. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides an input voltage adaptive electric heating control device that can adapt to different input voltages, does not require switching of heating resistors, has a simple circuit, and further solves the problem in existing methods where the heating resistor is turned on for half the time, the electric heating is subjected to high voltage during the 220Vac input, the instantaneous power is large, and the life of the heater is affected.

[0004] The present invention solves the above problems through the following technical solution:

[0005] An input voltage adaptive electric heating control device, comprising:

[0006] The detection unit is used to output a level combination signal based on the comparison result between the input voltage and the control voltage;

[0007] The control unit is used to make logical judgments based on the input start signal and the level combination signal, and output a control voltage signal;

[0008] The output unit consists of an AC input live wire, an electric heater, and an AC input neutral wire forming a series circuit. A switching device is also connected in series in the series circuit, and the switching device is controlled to be turned on or off by the control voltage signal.

[0009] In this invention, the detection unit is connected to the AC input live wire AC-L and the AC input neutral wire AC-N to detect the input voltage and output a level signal to the control unit. The control unit performs a logical AND operation based on the received level signal and the start signal to control the output unit's switching device to turn on or off, thereby turning the electric heating on and off. This eliminates the need for two sets of heating resistors and switching circuits, resulting in a simple circuit and low cost.

[0010] As a further improvement of the present invention, when the detection unit detects that the input voltage is in the first voltage mode, the input voltage is less than the control voltage, and outputs a first level combination signal; when the detection unit detects that the input voltage is in the second voltage mode, it outputs a second level combination signal when the voltage exceeds the control voltage during the positive half-cycle, and outputs a third level combination signal when the voltage exceeds the control voltage during the negative half-cycle; and outputs a fourth level combination signal when the voltages during the positive and negative half-cycles do not exceed the control voltage. The control voltage is set to satisfy the following condition: when the input voltage is in the second voltage mode, the heat generated by electric heating during the period when the voltages during the positive and negative half-cycles do not exceed the control voltage is equal to the heat generated by electric heating throughout the entire cycle when the input voltage is in the first voltage mode.

[0011] This invention utilizes different combinations of voltage level signals to ensure that, in the second voltage mode, when the voltage control voltage is high, the electric heater does not operate, thus achieving voltage peak clipping. This solves the problem in existing methods where the electric heater operates under high voltage during its on-time, resulting in high instantaneous power and reduced lifespan. Simultaneously, the control voltage is set and adjusted by the detection unit to ensure that, when the input voltage is in the second voltage mode, the heat generated by the electric heater during the positive and negative half-cycles (within the control voltage range) is equal to the heat generated by the electric heater throughout the entire cycle when the input voltage is in the first voltage mode.

[0012] As a further improvement of the present invention, the detection unit includes a first operational amplifier. The first input terminal of the first operational amplifier is connected in sequence to a first resistor unit and a first diode, and then connected to the AC input live wire. The second input terminal of the first operational amplifier is connected in sequence to a second resistor unit and a second diode, and then connected to the AC input neutral wire. The first input terminal of the first operational amplifier is grounded through a first grounding resistor, and the second input terminal is grounded through a second grounding resistor. The first output terminal and the second output terminal of the first operational amplifier are respectively connected to the control unit. The control voltage is determined by the first resistor unit, the second resistor unit, the first grounding resistor, and the second grounding resistor. The resistance values ​​of the first resistor unit, the second resistor unit, the first grounding resistor, and the second grounding resistor are adjustable.

[0013] As a further improvement of the present invention, the control unit outputs a first control voltage signal to the output unit according to the first level combination signal and the fourth level combination signal, and outputs a second control voltage signal to the output unit according to the second level combination signal and the third level combination signal.

[0014] As a further improvement of the present invention, the switching device includes a first MOS transistor and a second MOS transistor, and the control unit includes a first AND gate, a second AND gate, a first transistor, a second transistor, a first optocoupler unit and a second optocoupler unit. The first input terminal of the first AND gate and the first input terminal of the second AND gate are connected to the start signal. The second input terminal of the first AND gate is connected to the first output terminal of the first operational amplifier, and the second input terminal of the second AND gate is connected to the second output terminal of the first operational amplifier.

[0015] The output of the first AND gate is connected to the base of the first transistor, the emitter of the first transistor is grounded, the collector of the first transistor is connected to the input of the first optocoupler unit, and the output of the first optocoupler unit is connected to the gate of the first MOS transistor.

[0016] The output of the second AND gate is connected to the base of the second transistor, the emitter of the second transistor is grounded, the collector of the second transistor is connected to the input side of the second optocoupler unit, and the output side of the second optocoupler unit is connected to the gate of the second MOS transistor.

[0017] As a further improvement of the present invention, the first optocoupler unit includes a first optocoupler, the first end of the input side of the first optocoupler is connected to a first operating voltage through a third current-limiting resistor, the second end of the input side of the first optocoupler is connected to the collector of the first transistor; the first end of the output side of the first optocoupler is connected to a third diode and a fourth current-limiting resistor in sequence and then connected to a second operating voltage.

[0018] The second optocoupler unit includes a second optocoupler. The first end of the input side of the second optocoupler is connected to the first operating voltage through a fifth current-limiting resistor. The second end of the input side of the second optocoupler is connected to the collector of the second transistor. The first end of the output side of the second optocoupler is connected to the fourth diode and the sixth current-limiting resistor in sequence, and then connected to the second operating voltage.

[0019] As a further improvement of the present invention, the first optocoupler unit includes a first optocoupler, the first end of the input side of the first optocoupler is connected to a first operating voltage through a third current-limiting resistor, the second end of the input side of the first optocoupler is connected to the collector of the first transistor; the first end of the output side of the first optocoupler is connected to the base of a third transistor, the emitter of the third transistor is connected to a third diode and a fourth current-limiting resistor in sequence and then connected to a second operating voltage; the collector of the third transistor is connected to the gate of the first MOS transistor and the first end of the third resistor, the second end of the third resistor is connected to the second end of the output side of the first optocoupler and the anode of a fifth diode, the cathode of the fifth diode is connected to the source of the first MOS transistor and the AC input neutral line, and the drain of the first MOS transistor is connected to the first end of the electric heating.

[0020] The second optocoupler unit includes a second optocoupler. The first end of the input side of the second optocoupler is connected to the first operating voltage through a fifth current-limiting resistor. The second end of the input side of the second optocoupler is connected to the collector of the second transistor. The first end of the output side of the second optocoupler is connected to the base of a fourth transistor. The emitter of the fourth transistor is connected to a fourth diode and a sixth current-limiting resistor in sequence, and then connected to the second operating voltage. The collector of the fourth transistor is connected to the gate of the second MOSFET and the first end of the fourth resistor. The second end of the fourth resistor is connected to the second end of the output side of the second optocoupler and the anode of the sixth diode. The cathode of the sixth diode is connected to the drain of the second MOSFET and the AC input live wire. The drain of the second MOSFET is connected to the second end of the electric heating element.

[0021] As a further improvement of the present invention, a seventh current-limiting resistor is connected between the input terminal of the first AND gate and the start signal, and an eighth current-limiting resistor is provided between the second input terminal of the first AND gate and the first output terminal of the first operational amplifier; a ninth current-limiting resistor is connected between the first input terminal of the second AND gate and the start signal, and a tenth current-limiting resistor is provided between the second input terminal of the second AND gate and the second output terminal of the first operational amplifier.

[0022] As a further improvement of the present invention, when it is necessary to turn on the electric heating, the start signal is high level, and the following is determined:

[0023] When the input voltage is in the first voltage mode, both the first and second output terminals of the first operational amplifier output a high level.

[0024] When the input voltage is in the second voltage mode, the control voltage Uac is determined by the first resistor unit, the second resistor unit, the first grounding resistor, and the second grounding resistor.

[0025] During the positive half-cycle, when the voltage is less than or equal to Uac, both the first and second output terminals of the first operational amplifier output a high level; when the voltage is greater than Uac, the first output terminal of the first operational amplifier outputs a low level, and the second output terminal outputs a high level.

[0026] During the negative half-cycle, when the voltage is less than or equal to Uac, both the first and second output terminals of the first operational amplifier output a high level; when the voltage is greater than Uac, the first output terminal of the first operational amplifier outputs a high level, and the second output terminal outputs a low level.

[0027] When both the first and second output terminals of the first operational amplifier output high levels, they are respectively subjected to logical AND operations with the first AND gate and the second AND gate input to the start signal. Both the output terminals of the first AND gate and the second AND gate output high levels, and the first transistor and the second transistor are turned on. The first optocoupler unit and the second optocoupler unit drive the first MOS transistor and the second MOS transistor to turn on, and the AC input live wire, electric heating, and AC input neutral wire form a loop.

[0028] When the first output terminal of the first operational amplifier outputs a low level and the second output terminal outputs a high level, after performing a logical AND operation with the first AND gate and the second AND gate respectively, the output terminal of the first AND gate outputs a low level and the output terminal of the second AND gate outputs a high level. The first transistor is cut off and the second transistor is turned on. Only the second optocoupler unit drives the second MOS transistor to turn on, and the first MOS transistor is cut off. The AC input live wire, electric heating, and AC input neutral wire cannot form a loop.

[0029] When the first output terminal of the first operational amplifier outputs a high level and the second output terminal outputs a low level, after performing a logical AND operation with the first AND gate and the second AND gate respectively, the output terminal of the first AND gate outputs a high level and the output terminal of the second AND gate outputs a low level. The first transistor is turned on and the second transistor is turned off. Only the first optocoupler unit drives the first MOS transistor to turn on and the second MOS transistor to turn off. The AC input live wire, electric heating and AC input neutral wire cannot form a loop.

[0030] As a further improvement of the present invention, when the input voltage is in the second voltage mode, the method for ensuring that the heat generated by electric heating during the positive and negative half-cycles when the voltage does not exceed the control voltage is equal to the heat generated by electric heating throughout the entire cycle when the input voltage is in the first voltage mode is as follows:

[0031] By integrating the voltage and current, the heat generated during the electric heating operation in the second voltage mode is made equal to the heat generated during the electric heating operation in the first voltage mode throughout the entire cycle.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] (1) The present invention can adapt to different input voltages and does not require switching of heating resistors. The circuit is simple, does not change the selection and assembly of electric heating, and has low cost.

[0034] (2) This invention solves the problem in the prior art that the time-heating device, which is turned on when the input is 220Vac, has a high voltage and high instantaneous power, which affects the life of the heater by peak shaving. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of an embodiment of the present invention;

[0036] Figure 2 This is a circuit schematic diagram of the first specific embodiment of the present invention;

[0037] Figure 3 This is a circuit schematic diagram of a second specific embodiment of the present invention;

[0038] Figure 4 This is a voltage waveform diagram of the first voltage input of the present invention applied to the electric heater;

[0039] Figure 5 This is a voltage waveform diagram of the second voltage input of the present invention applied to the electric heater;

[0040] Figure 6 This is a waveform diagram of the first voltage input of the present invention, wherein V(ga) is the voltage waveform at the first output terminal of the first operational amplifier, V(gb) is the voltage waveform at the second output terminal of the first operational amplifier, V(AC-N, AC_L) is the AC input voltage waveform, V(localA, localB) is the electric heating voltage waveform, and Id(M2) is the electric heating current waveform.

[0041] Figure 7 This is a waveform diagram for the second voltage input of the present invention, wherein V(ga) is the voltage waveform at the first output terminal of the first operational amplifier, V(gb) is the voltage waveform at the second output terminal of the first operational amplifier, V(AC-N, AC_L) is the AC input voltage waveform, V(localA, localB) is the electric heating voltage waveform, and Id(M2) is the electric heating current waveform. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0043] Example 1:

[0044] Combined with appendix Figure 1 As shown, an input voltage adaptive electric heating control device includes:

[0045] The detection unit is used to output a level combination signal based on the comparison result between the input voltage and the control voltage;

[0046] The control unit is used to make logical judgments based on the input start signal and the level combination signal, and output a control voltage signal;

[0047] The output unit consists of an AC input live wire, an electric heater, and an AC input neutral wire forming a series circuit. A switching device is also connected in series in the series circuit, and the switching device is controlled to be turned on or off by the control voltage signal.

[0048] The detection unit is connected to the AC input live wire AC-L and neutral wire AC-N, and the output of the detection unit is connected to the input of the control unit. The control unit performs a logical AND operation based on the transmitted signals and the start signal JRQKZ to control the power devices, i.e., switching devices (MOSFETs, transistors, etc.), to turn on and off, thereby controlling the on / off state of the output unit loop, realizing the on / off state of the electric heating and providing the required heat.

[0049] Example 2:

[0050] Based on Example 1, combined with Figure 2 As shown, the detection unit includes a first operational amplifier U20. The first input terminal (pin 2) of the first operational amplifier U20 is connected to resistor R01 and diode D01 in sequence, and then connected to the AC input live wire AC-L. The first input terminal of the first operational amplifier U20 is grounded through resistor R03, and the second input terminal (pin 6) of the first operational amplifier U20 is grounded through resistor R04. The second input terminal of the first operational amplifier U20 is connected to resistor R02 and diode D02 in sequence, and then connected to the AC input neutral wire AC-N. The first and second output terminals of the first operational amplifier U20 are respectively connected to the control unit. The control voltage Uac is determined by the resistance values ​​of resistors R01, R02, R03, and R04. The calculation method is common knowledge in the field and will not be elaborated further. It is worth noting that the resistance values ​​of resistors R01, R02, R03, and R04 are adjustable, and Uac can be set according to the voltage of the application scenario.

[0051] In this embodiment, the control unit includes a first AND gate U02, a second AND gate U03, a transistor Q01, and a transistor Q02. The first input terminal (pin 1) of the first AND gate U02 and the first input terminal (pin 1) of the second AND gate U03 are connected to the start signal JRQKZ. The second input terminals (pin 2) of the first AND gate U02 and the second input terminals (pin 2) of the second AND gate U03 are respectively connected to the first output terminal (pin 1) and the second output terminal (pin 7) of the first operational amplifier U20. The output terminal (pin 4) of the first AND gate U02 is connected to the base of transistor Q01. The emitter of transistor Q01 is grounded, and the collector of transistor Q01 is connected to the first optocoupler U04. The second terminal of the input side of the first optocoupler U04 is connected to the first working voltage through resistor R05. The first working voltage is 15V. The first terminal of the output side of the first optocoupler U04 is connected to diode D03 and resistor R07 in sequence and then connected to the second working voltage. The second working voltage is 12V. The second terminal of the output side of the first optocoupler U04 is connected to the gate of MOS transistor Q03 in the output unit. The source of MOS transistor Q03 is connected to the AC input neutral line AC-N. The drain of MOS transistor Q03 is connected to one end of the electric heating Rload. The other end of the electric heating Rload is connected to the source of MOS transistor Q04. The drain of MOS transistor Q04 is connected to the AC input live line AC-L.

[0052] The output terminal (pin 4) of the second AND gate U03 is connected to the base of the transistor Q02. The emitter of the transistor Q02 is grounded. The collector of the transistor Q02 is connected to the second terminal of the input side of the second optocoupler U05. The first terminal of the input side of the second optocoupler U05 is connected to the first working voltage through the resistor R06. The first terminal of the output side of the second optocoupler U05 is connected to the diode D04 and the resistor R08 in sequence and then connected to the second working voltage. The second terminal of the output side of the second optocoupler U05 is connected to the gate of the second MOS transistor Q04.

[0053] The control method is as follows:

[0054] When the electric heating needs to be turned on, the start signal JRQKZ is at a high level. When the input voltage is 110Vac, pins 1 and 7 of the first operational amplifier U20 output a high level. After passing through the first AND gate U02 and the second AND gate U03, both the first AND gate U02 and the second AND gate U03 output a high level, transistors Q01 and Q02 are turned on, and the primary windings of the first optocoupler U04 and the second optocoupler U05 are turned on, which turns on MOSFETs Q03 and Q04. The AC input live wire AC-L, the AC input neutral wire AC-N, the electric heating Rload, and MOSFETs Q03 and Q04 form a loop, and the electric heating is put into operation.

[0055] When the input voltage is 220Vac, the control voltage Uac is set by adjusting the resistance values ​​of resistors R01, R03 and R02, R04. When the AC voltage is less than Uac, pins 1 and 7 of the first operational amplifier U20 are at a high level, operating as when the input voltage is 110Vac, driving power transistors Q03 and Q04 to conduct. During the positive half-cycle of the AC voltage, when the AC voltage is greater than Uac, pin 1 of the first operational amplifier U20 is at a low level; when it is less than Uac, pin 1 is at a high level, and pin 7 is always at a high level. During the negative half-cycle, when the AC voltage is greater than Uac, pin 7 of the first operational amplifier U20 is at a low level; when it is less than Uac, pin 7 is at a high level, and pin 1 is always at a high level. When pin 1 of the first operational amplifier U20 is high and pin 7 is low (the input voltage is in the negative half-cycle), power device Q03 is turned on and Q04 is turned off. Because the AC current is in the negative half-cycle, the AC input live wire AC-L, neutral wire AC-N, electric heater Rload, Q03, and Q04 cannot form a loop, and the electric heater cannot operate. When pin 1 of U01 is low and pin 7 is high (the input voltage is in the positive half-cycle), power device Q04 is turned on and Q03 is turned off. Because the AC current is in the positive half-cycle, the AC input live wire AC-L, neutral wire AC-N, electric heater Rload, Q03, and Q04 cannot form a loop, and the electric heater cannot operate. By integrating the voltage and current, the heat generated by the electric heater during the corresponding operating time (Uac) is made equal to the heat generated by the electric heater during the entire cycle when the input is 110Vac. That is, the device automatically adapts to both 110Vac and 220Vac voltages, and the heat generated by the electric heater is the same regardless of the input voltage.

[0056] Heating amount = (Input voltage * Input voltage / Heating wire internal resistance) * Heating time.

[0057] With a 110Vac input, the control switch makes the operating voltage on the heater as follows: Figure 4 The heater operates continuously throughout the entire cycle; with a 220Vac input, the control switch keeps the operating voltage on the heater as... Figure 5 The switching transistor is turned off at the dotted line, and heating is not activated, thus achieving the same heating output as under a 110Vac input condition. This achieves the goal of adapting the same hardware to two input voltages.

[0058] This invention achieves full-cycle conduction with 110Vac input and, with 220Vac input, removes some peaks, ensuring that the electric heating generates the same amount of heat as with 110Vac input. Simultaneously, by reducing peaks, it solves the problem in existing technologies where the electric heating withstands higher voltage and instantaneous power during 220Vac input, thus affecting the heater's lifespan.

[0059] Example 3:

[0060] Based on Example 1, such as Figure 3 As shown, the detection unit includes a first operational amplifier U1. The first input terminal (pin 2) of the first operational amplifier U1 is connected to resistors R3, R2, R1, and diode D1 in sequence, and then connected to the AC input live wire AC-L. The first input terminal of the first operational amplifier U1 is also grounded through resistor R7. The second input terminal (pin 6) of the first operational amplifier U1 is grounded through resistor R8. The second input terminal of the first operational amplifier U1 is connected to resistors R6, R5, R4, and diode D2 in sequence, and then connected to the AC input neutral wire AC-N. The control voltage Uac is determined by the resistance values ​​of resistors R1 to R8. It is worth noting that the resistance values ​​of resistors R1 to R8 are adjustable, and Uac can be set according to the voltage of the application scenario.

[0061] The first output terminal and the second output terminal of the first operational amplifier U1 are respectively connected to the second input terminals of the first AND gate U2 and the second AND gate U3 of the control unit. The first input terminal (pin 1) of the first AND gate U2 and the first input terminal (pin 1) of the second AND gate U3 are respectively connected to the start signal JRQKZ through resistors R9 and R11. The second input terminal (pin 2) of the first AND gate U2 and the second input terminal (pin 2) of the second AND gate U3 are respectively connected to the first output terminal (pin 1) and the second output terminal (pin 7) of the first operational amplifier U1 through resistors R10 and R12.

[0062] The output terminal (pin 4) of the first AND gate U2 is connected to the base of transistor Q1. The emitter of transistor Q1 is grounded. The collector of transistor Q1 is connected to the second terminal of the input terminal of the first optocoupler U4. The first terminal of the input terminal of the first optocoupler U4 is connected to the first working voltage through resistor R13. The first working voltage is 15V. The first terminal of the output side of the first optocoupler U4 is connected to the base of transistor Q1. The emitter of transistor Q1 is connected to diode D3 and resistor R15 in sequence and then connected to the second working voltage. The second working voltage is 12V. The collector of transistor Q1 is connected to the gate of MOS transistor Q5 in the output unit and the first terminal of resistor R17. The second terminal of resistor R17 is connected to the second terminal of the output terminal of the first optocoupler U4 and the anode of diode D4. The cathode of diode D4 is connected to the AC input neutral line AC-N.

[0063] The source of MOSFET Q5 is connected to the AC input neutral line AC-N, the drain of MOSFET Q5 is connected to one end of the electric heater DJR, the other end of the electric heater DJR is connected to the source of MOSFET Q6, and the drain of MOSFET Q6 is connected to the AC input live line AC-L.

[0064] The output terminal (pin 4) of the second AND gate U3 is connected to the base of the transistor Q2. The emitter of the transistor Q2 is grounded. The collector of the transistor Q2 is connected to the second terminal of the input terminal of the second optocoupler U5. The first terminal of the input terminal of the second optocoupler U5 is connected to the first working voltage through resistor R14. The first terminal of the output side of the second optocoupler U5 is connected to the base of the transistor Q4. The emitter of the transistor Q4 is connected to diode D5 and resistor R16 in sequence and then connected to the second working voltage. The collector of the transistor Q4 is connected to the gate of MOSFET Q6 and the first terminal of resistor R18. The second terminal of resistor R18 is connected to the second terminal of the output terminal of the second optocoupler U5 and the anode of diode D6. The cathode of diode Q6 is connected to the source of MOSFET Q6 and the AC input neutral line AC-L.

[0065] The control method is as follows:

[0066] When the electric heating needs to be turned on, the start signal JRQKZ is high. When the input voltage is in the first voltage mode, such as 110Vac, the first operational amplifier U1 outputs a high level at pins 1 and 7. After passing through the first AND gate U2 and the second AND gate U3, the fourth pin of the first AND gate U2 and the second AND gate U3 is high, transistors Q1 and Q2 are turned on, the primary windings of the first optocoupler U4 and the second optocoupler U5 are turned on, and transistors Q3 and Q4 drive MOSFETs Q5 and Q6 to turn on. The AC input live wire AC-L, neutral wire AC-N, electric heating DJR, MOSFET Q5, and MOSFET Q6 form a loop, and the electric heating is put into operation.

[0067] When the input voltage is 110Vac, the waveforms of the first output terminal, the second output terminal, the AC input voltage, the electric heating voltage, and the current of the first operational amplifier are as follows: Figure 6 As shown, the electric heating works throughout the entire cycle.

[0068] When the input voltage is in the second voltage mode, such as 220Vac, the control voltage Uac is set by adjusting the resistance values ​​of resistors R1, R2, R3, and R7, and resistors R4, R5, R6, and R8. When the AC current is less than Uac, pins 1 and 7 of the first operational amplifier U1 are at a high level, operating as with an input of 110Vac. During the positive half-cycle, pin 1 is at a low level when the AC current is greater than Uac, and at a high level when it is less than Uac. During the negative half-cycle, pin 7 is at a low level when the AC current is greater than Uac, and at a high level when it is less than Uac. When pin 1 of U1 is high and pin 7 is low (the input voltage is in the negative half-cycle), MOSFET Q5 is turned on and Q6 is turned off. Because the AC current is in the negative half-cycle, the AC input live wire AC-L, neutral wire AC-N, electric heater DJR, Q5, and Q6 cannot form a loop, and the electric heater cannot operate. When pin 1 of U1 is low and pin 7 is high (the input voltage is in the positive half-cycle), MOSFET Q6 is turned on and Q5 is turned off. Because the AC current is in the positive half-cycle, the AC input live wire (AC-L), neutral wire (AC-N), electric heater DJR, Q5, and Q6 cannot form a loop, and the electric heater cannot operate. By integrating the voltage and current, the heat generated by the electric heater during the corresponding operating time (Uac) is made equal to the heat generated by the electric heater during the entire cycle when the input is 110Vac. That is, the device automatically adapts to both 110Vac and 220Vac voltages, and the heat generated by the electric heater is the same regardless of the input voltage.

[0069] When the input voltage is 220Vac, the waveforms of the first output terminal, the second output terminal, the AC input voltage, the electric heating voltage, and the current of the first operational amplifier are as follows: Figure 7 As shown, this invention achieves full-cycle conduction when inputting 110Vac, and removes some peaks when inputting 220Vac, so that electric heating generates the same amount of heat as 110Vac input, thus realizing adaptive control of electric heating.

[0070] This invention enables adaptive operation to both 220Vac and 110Vac input voltages, allowing the same refrigerator, air conditioner, and washing machine to operate in both 220Vac and 110Vac voltage modes. It is low-cost and suitable for mass production of household appliances.

[0071] Although the present invention has been described herein with reference to illustrative embodiments, the above embodiments are merely preferred embodiments of the present invention, and the implementation of the present invention is not limited to the above embodiments. It should be understood that those skilled in the art can devise many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in this application.

Claims

1. An input voltage adaptive electric heating control device, characterized in that, include: The detection unit is used to output a level combination signal based on the comparison result between the input voltage and the control voltage; The control unit is used to make logical judgments based on the input start signal and the level combination signal, and output a control voltage signal; The output unit consists of an AC input live wire, an electric heater, and an AC input neutral wire forming a series circuit. A switching device is also connected in series in the series circuit, and the switching device is controlled to be turned on or off by the control voltage signal.

2. The input voltage adaptive electric heating control device according to claim 1, characterized in that, When the detection unit detects that the input voltage is in the first voltage mode, the input voltage is less than the control voltage, and outputs a first level combination signal. When the detection unit detects that the input voltage is in the second voltage mode, it outputs a second level combination signal when the voltage exceeds the control voltage during the positive half-cycle, and outputs a third level combination signal when the voltage exceeds the control voltage during the negative half-cycle. When the voltages during the positive and negative half-cycles do not exceed the control voltage, it outputs a fourth level combination signal. The control voltage is set to satisfy the following condition: when the input voltage is in the second voltage mode, the heat generated by electric heating during the period when the voltages during the positive and negative half-cycles do not exceed the control voltage is equal to the heat generated by electric heating throughout the entire cycle when the input voltage is in the first voltage mode.

3. The input voltage adaptive electric heating control device according to claim 2, characterized in that, The detection unit includes a first operational amplifier. The first input terminal of the first operational amplifier is connected in sequence to a first resistor unit and a first diode, and then connected to the AC input live wire. The second input terminal of the first operational amplifier is connected in sequence to a second resistor unit and a second diode, and then connected to the AC input neutral wire. The first input terminal of the first operational amplifier is grounded through a first grounding resistor, and the second input terminal is grounded through a second grounding resistor. The first output terminal and the second output terminal of the first operational amplifier are respectively connected to the control unit. The control voltage is determined by the first resistor unit, the second resistor unit, the first grounding resistor, and the second grounding resistor. The resistance values ​​of the first resistor unit, the second resistor unit, the first grounding resistor, and the second grounding resistor are adjustable.

4. The input voltage adaptive electric heating control device according to claim 3, characterized in that, The control unit outputs a first control voltage signal to the output unit based on the first level combination signal and the fourth level combination signal, and outputs a second control voltage signal to the output unit based on the second level combination signal and the third level combination signal.

5. The input voltage adaptive electric heating control device according to claim 4, characterized in that, The switching device includes a first MOSFET and a second MOSFET, and the control unit includes a first AND gate, a second AND gate, a first transistor, a second transistor, a first optocoupler unit, and a second optocoupler unit. The first input terminal of the first AND gate and the first input terminal of the second AND gate are connected to the start signal. The second input terminal of the first AND gate is connected to the first output terminal of the first operational amplifier, and the second input terminal of the second AND gate is connected to the second output terminal of the first operational amplifier. The output of the first AND gate is connected to the base of the first transistor, the emitter of the first transistor is grounded, the collector of the first transistor is connected to the input of the first optocoupler unit, and the output of the first optocoupler unit is connected to the gate of the first MOS transistor. The output of the second AND gate is connected to the base of the second transistor, the emitter of the second transistor is grounded, the collector of the second transistor is connected to the input side of the second optocoupler unit, and the output side of the second optocoupler unit is connected to the gate of the second MOS transistor.

6. The input voltage adaptive electric heating control device according to claim 5, characterized in that, The first optocoupler unit includes a first optocoupler, the first end of the input side of the first optocoupler is connected to a first operating voltage through a third current-limiting resistor, the second end of the input side of the first optocoupler is connected to the collector of the first transistor; the first end of the output side of the first optocoupler is connected to a third diode and a fourth current-limiting resistor in sequence and then connected to a second operating voltage. The second optocoupler unit includes a second optocoupler. The first end of the input side of the second optocoupler is connected to the first operating voltage through a fifth current-limiting resistor. The second end of the input side of the second optocoupler is connected to the collector of the second transistor. The first end of the output side of the second optocoupler is connected to the fourth diode and the sixth current-limiting resistor in sequence, and then connected to the second operating voltage.

7. The input voltage adaptive electric heating control device according to claim 5, characterized in that, The first optocoupler unit includes a first optocoupler, the first terminal of the input side of the first optocoupler is connected to a first operating voltage through a third current-limiting resistor, and the second terminal of the input side of the first optocoupler is connected to the collector of the first transistor; the first terminal of the output side of the first optocoupler is connected to the base of a third transistor, and the emitter of the third transistor is connected to a third diode and a fourth current-limiting resistor in sequence, and then connected to a second operating voltage; the collector of the third transistor is connected to the gate of the first MOS transistor and the first terminal of the third resistor, the second terminal of the third resistor is connected to the second terminal of the output side of the first optocoupler and the anode of a fifth diode, the cathode of the fifth diode is connected to the source of the first MOS transistor and the AC input neutral line, and the drain of the first MOS transistor is connected to the first terminal of the electric heating element; The second optocoupler unit includes a second optocoupler. The first end of the input side of the second optocoupler is connected to the first operating voltage through a fifth current-limiting resistor. The second end of the input side of the second optocoupler is connected to the collector of the second transistor. The first end of the output side of the second optocoupler is connected to the base of a fourth transistor. The emitter of the fourth transistor is connected to a fourth diode and a sixth current-limiting resistor in sequence, and then connected to the second operating voltage. The collector of the fourth transistor is connected to the gate of the second MOS transistor and the first end of the fourth resistor. The second end of the fourth resistor is connected to the second end of the output side of the second optocoupler and the anode of the sixth diode. The cathode of the sixth diode is connected to the drain of the second MOS transistor and the AC input live wire. The source of the second MOS transistor is connected to the second end of the electric heating element.

8. An input voltage adaptive electric heating control device according to any one of claims 5-7, characterized in that, A seventh current-limiting resistor is connected between the input terminal of the first AND gate and the start signal; an eighth current-limiting resistor is provided between the second input terminal of the first AND gate and the first output terminal of the first operational amplifier; a ninth current-limiting resistor is connected between the first input terminal of the second AND gate and the start signal; and a tenth current-limiting resistor is provided between the second input terminal of the second AND gate and the second output terminal of the first operational amplifier.

9. An input voltage adaptive electric heating control device according to any one of claims 5-7, characterized in that, When electric heating needs to be turned on, the start signal is high, and the following judgment is made: When the input voltage is in the first voltage mode, both the first and second output terminals of the first operational amplifier output a high level. When the input voltage is in the second voltage mode, the control voltage Uac is determined by the first resistor unit, the second resistor unit, the first grounding resistor, and the second grounding resistor. During the positive half-cycle, when the voltage is less than or equal to Uac, both the first and second output terminals of the first operational amplifier output a high level; when the voltage is greater than Uac, the first output terminal of the first operational amplifier outputs a low level, and the second output terminal outputs a high level. During the negative half-cycle, when the voltage is less than or equal to Uac, both the first and second output terminals of the first operational amplifier output a high level; when the voltage is greater than Uac, the first output terminal of the first operational amplifier outputs a high level, and the second output terminal outputs a low level. When both the first and second output terminals of the first operational amplifier output high levels, they are respectively subjected to logical AND operations with the first AND gate and the second AND gate input to the start signal. Both the output terminals of the first AND gate and the second AND gate output high levels, and the first transistor and the second transistor are turned on. The first optocoupler unit and the second optocoupler unit drive the first MOS transistor and the second MOS transistor to turn on, and the AC input live wire, electric heating, and AC input neutral wire form a loop. When the first output terminal of the first operational amplifier outputs a low level and the second output terminal outputs a high level, after performing a logical AND operation with the first AND gate and the second AND gate respectively, the output terminal of the first AND gate outputs a low level and the output terminal of the second AND gate outputs a high level. The first transistor is cut off and the second transistor is turned on. Only the second optocoupler unit drives the second MOS transistor to turn on, and the first MOS transistor is cut off. The AC input live wire, electric heating, and AC input neutral wire cannot form a loop. When the first output terminal of the first operational amplifier outputs a high level and the second output terminal outputs a low level, after performing a logical AND operation with the first AND gate and the second AND gate respectively, the output terminal of the first AND gate outputs a high level and the output terminal of the second AND gate outputs a low level. The first transistor is turned on and the second transistor is turned off. Only the first optocoupler unit drives the first MOS transistor to turn on and the second MOS transistor to turn off. The AC input live wire, electric heating and AC input neutral wire cannot form a loop.

10. The input voltage adaptive electric heating control device according to claim 9, characterized in that, When the input voltage is in the second voltage mode, the method to ensure that the heat generated by electric heating during the positive and negative half-cycles when the voltage does not exceed the control voltage is equal to the heat generated by electric heating throughout the entire cycle when the input voltage is in the first voltage mode is as follows: By integrating the voltage and current, the heat generated during the electric heating operation in the second voltage mode is made equal to the heat generated during the electric heating operation in the first voltage mode throughout the entire cycle.

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