110v / 220v automatic identification voltage doubling rectifier circuit

Abstract

This invention belongs to the technical field of automatic identification voltage doubler rectifier circuits, and particularly relates to a 110V / 220V automatic identification voltage doubler rectifier circuit, including an MCU voltage sampling control module, a main rectifier circuit, an auxiliary voltage doubler circuit, a relay drive circuit, and a high-voltage divider sampling circuit; the main rectifier circuit includes a first relay K1, a current-limiting resistor R3, a rectifier bridge D2, an energy storage capacitor C2, and an energy storage capacitor C3, with the first relay K1 connected in series to the AC live wire L path; the auxiliary voltage doubler circuit includes a second relay K2, a high-voltage diode D1, and an energy storage capacitor C1, with the second relay K2 connected in series to the AC neutral wire N branch, and the positive terminal of the energy storage capacitor C1 coupled to the high-voltage bus HV+ of the main rectifier circuit.

Description

Technical Field

[0001] This invention belongs to the field of automatic identification voltage doubler rectifier circuit technology, and particularly relates to a 110V / 220V automatic identification voltage doubler rectifier circuit. Background Technology

[0002] Currently, switching power supplies, industrial frequency converters, and brushless motor drive equipment need to be compatible with both AC110V and AC220V mainstream AC power grids. Existing mature solutions in the industry have significant shortcomings. One type involves separate mold production for different voltage versions, resulting in numerous material models, heavy inventory management pressure, and an inability to achieve universal compatibility. Another type of product uses an external manual voltage switching DIP switch, requiring operators to manually identify the grid voltage and switch between voltage levels. This manual operation is cumbersome, cannot integrate a standardized built-in power module, and carries a very high risk of human error during switching. Connecting the wrong voltage can easily cause electrolytic capacitors to explode, rectifier bridges to break down, or even cause the entire machine to explode, posing serious safety hazards. Traditional adaptive voltage multiplier circuits mostly require additional independent auxiliary rectifier bridges and transformer secondary auxiliary power supply circuits to complete voltage sampling and voltage multiplication control. This results in a large number of components, complex PCB layout, and high overall material costs. Furthermore, they lack timing control logic for no-load identification and graded power-on, and power-on surge currents can easily interfere with voltage discrimination accuracy, making it difficult to balance universality, safety, and low cost requirements.

[0003] Existing conventional voltage multiplier rectifier structures can only perform fixed voltage multiplication or fixed full-bridge rectification, and cannot automatically identify the grid voltage level to achieve mode switching. The few automatic switching solutions on the market rely on dedicated power control chips, which have long procurement cycles and high costs. They also lack stability in industrial scenarios with high and low temperatures and strong electromagnetic interference. In addition, they do not adopt a single diode to simplify the voltage multiplier branch architecture, which adds additional rectifier devices and occupies circuit board space. This limits the miniaturization design of the whole machine and makes it difficult to meet the needs of cost reduction, high reliability, and no manual intervention in the mass production of universal power supplies with wide voltage. Summary of the Invention

[0004] In view of the above-mentioned problems, embodiments of the present invention provide a 110V / 220V automatic identification voltage doubler rectifier circuit, including an MCU voltage sampling control module, a main rectifier circuit, an auxiliary voltage doubler circuit, a relay drive circuit, and a high voltage divider sampling circuit; The main rectifier circuit includes a first relay K1, a current-limiting resistor R3, a rectifier bridge D2, an energy storage capacitor C2, and an energy storage capacitor C3. The first relay K1 is connected in series to the AC live wire L path. The auxiliary voltage multiplier circuit includes a second relay K2, a high-voltage diode D1, and an energy storage capacitor C1. The second relay K2 is connected in series to the AC neutral line N branch, and the positive terminal of the energy storage capacitor C1 is coupled to the high-voltage bus HV+ of the main rectifier circuit. The high-voltage divider sampling circuit is composed of high-voltage resistors R4, R5, and R6 connected in series. The POWER_IN sampling signal output by the voltage divider node is connected to the MCU's built-in ADC sampling pin. The relay drive circuit includes NPN switching transistors Q1 and Q2 and base limiting current resistors R1 and R2, with the transistors respectively driving the coils of the first relay K1 and the second relay K2. After the MCU is powered on, it controls both relays to disconnect, and automatically identifies the AC input voltage level by collecting the voltage divider under no-load and silent conditions. When the input is identified as AC110V low voltage, the second relay K2 is first turned on to connect to the auxiliary voltage multiplier circuit to complete the voltage boost. After a delay and stabilization, the first relay K1 is turned on to connect the main rectifier circuit. When the input is identified as AC220V high voltage, the second relay K2 remains open, and the first relay K1 is only turned on after a delay. Under both input conditions, the circuit outputs a stable 310V DC bus voltage.

[0005] Preferably, the auxiliary voltage multiplier circuit uses only a single high-voltage diode D1 to achieve voltage multiplication charging.

[0006] Preferably, during the circuit power-on detection stage, the first relay K1 and the second relay K2 are kept in the open state simultaneously, and the no-load silent sampling mode is adopted.

[0007] Preferably, the high-voltage voltage divider sampling circuit adopts a multi-high-voltage chip resistor series voltage divider structure.

[0008] Preferably, the energy storage capacitors C2 and C3 are arranged in series, both of which are 450V withstand voltage electrolytic capacitors. Each energy storage capacitor is connected in parallel with an independent high voltage discharge resistor, so that the residual high voltage of the capacitor can be quickly released after the equipment is powered off.

[0009] Preferably, the current-limiting resistor R3 is a high-power cement resistor, connected in series between the first relay K1 and the rectifier bridge D2, to suppress the surge current of the energy storage capacitor during power-on.

[0010] Preferably, both ends of the coils of the first relay K1 and the second relay K2 are connected in reverse parallel with freewheeling diodes to absorb the reverse induced electromotive force at the moment the relays are disconnected.

[0011] A 110V / 220V adaptive universal voltage doubler rectifier control method includes the following steps: Step 1: The device is powered on, the MCU completes initialization, and controls the first relay K1 and the second relay K2 to disconnect, and the circuit enters the no-load silent state; Step 2: The MCU repeatedly collects the POWER_IN voltage divider sampled voltage, removes noise interference through the mean filtering algorithm, compares the calculated average voltage with the internal preset threshold, and determines whether the current power grid is under AC110V low voltage condition or AC220V high voltage condition. Step 3: If the AC110V low voltage condition is determined, the MCU controls the transistor Q2 to turn on and the second relay K2 to be activated, connecting the auxiliary voltage multiplier circuit. After the bus voltage stabilizes and is delayed for 150ms-300ms, the transistor Q1 is turned on and the first relay K1 is activated, and the main rectifier circuit is connected to the load and operates normally. Step 4: If the AC220V high voltage condition is determined, the MCU keeps transistor Q2 off and the second relay K2 open. The auxiliary voltage multiplier circuit does not participate in the work. After a 100ms delay, transistor Q1 is turned on and the first relay K1 is energized after the rectified voltage stabilizes. Step 5: During the normal load operation phase of the whole machine, the MCU continuously collects the bus voltage in real time. When a large abnormal fluctuation in the bus voltage is detected, the current on / off state of the two relays is locked, and the relay switching action is prohibited to realize voltage abnormality protection.

[0012] Preferably, in step two, the MCU continuously collects at least three sets of sampled voltages to calculate the average value, filtering out sampling errors caused by power-on instantaneous interference and power grid harmonics.

[0013] Preferably, after the MCU locks the relay drive level in step five, the lock is not released until the device is powered off and restarted.

[0014] Based on the above, a combination of no-load silent sampling and hierarchical power-on timing control is adopted. During the initial power-on phase, both relays are disconnected, allowing for grid voltage identification before selectively engaging the voltage multiplier branch and finally connecting the main circuit. This effectively suppresses power-on surge impacts, improving voltage identification accuracy and comprehensively protecting power devices such as the rectifier bridge and electrolytic capacitors. The external manual voltage switching switch is eliminated, relying on the MCU to automatically distinguish between AC110V and AC220V inputs, completely preventing machine failures and component burnouts caused by human error. A single hardware circuit board is compatible with both mainstream grids, eliminating the need for version-specific production and significantly reducing material types and lowering warehousing and production management costs. Furthermore, a single high-voltage diode is used to build the voltage multiplier unit, eliminating the need for the auxiliary rectifier bridge and secondary auxiliary power supply circuit required in traditional solutions. This reduces the number of components, simplifies PCB layout, and shrinks the overall circuit board size. All components are general-purpose discrete devices, eliminating the need for dedicated power management chips, facilitating material procurement, lowering overall hardware costs, and enhancing operational stability in high / low temperature and strong electromagnetic interference industrial environments.

[0015] The circuit automatically engages the voltage doubler branch to raise the bus to 310V under AC110V conditions, and disconnects the voltage doubler branch to directly rectify and output 310V DC to the bus under AC220V conditions. The downstream power conversion circuit requires no design changes, making it highly versatile. During operation, the circuit continuously monitors the bus voltage in real time, locking the relay's on / off state when abnormal voltage fluctuations occur to prevent frequent switching that could cause bus oscillations and component damage, providing independent voltage protection. The high-voltage voltage divider sampling circuit uses multiple high-voltage resistors in series, offering excellent insulation and withstand voltage performance. Sampling errors are controlled within 5%, ensuring accurate and reliable voltage identification. The energy storage capacitor is equipped with an independent discharge resistor, quickly releasing residual high voltage after power failure, reducing the risk of electric shock during equipment maintenance. It is widely adaptable to various wide-voltage power supply equipment, including civilian switching power supplies, brushless motor drives, and industrial frequency converters. Attached Figure Description

[0016] Figure 1 This is a circuit diagram of a 110V / 220V automatic identification voltage doubler rectifier circuit provided in an embodiment of the present invention. Detailed Implementation

[0017] The following is in conjunction with the instruction manual appendix. Figure 1 The present invention will be described in detail below; The overall circuit consists of five parts: an MCU voltage sampling and control module, a main rectifier circuit, a neutral-side auxiliary voltage multiplier circuit, a dual-channel relay drive circuit, and a high-voltage bus voltage divider sampling circuit. All components are built using general-purpose discrete parts, requiring no dedicated wide-voltage power supply chip and not relying on the transformer secondary auxiliary power supply branch. Only a single high-voltage diode is used to build the voltage multiplier unit. Combined with the MCU's hierarchical and time-sharing power-on control logic, it automatically identifies both AC110V and AC220V mains voltages, ensuring a stable 310V DC bus voltage output regardless of the input. This makes it suitable for industrial frequency converters, brushless motor drivers, and general industrial switching power supplies. The AC input is defined as L for the live wire and N for the neutral wire. The DC outputs HV+ and HV- serve as the downstream power conversion buses. The MCU uses an independent 3.3V low-voltage power supply, and strong and weak currents are isolated from the high-voltage bus using voltage divider resistors. The PCB layout separates strong and weak current circuits to meet safety regulations for insulation and withstand voltage.

[0018] The main rectifier circuit is responsible for the main rectification, filtering, and surge current limiting of the grid power. A relay K1 is connected in series with the live wire to control the on / off state. K1 is a 12V DC electromagnetic relay with a contact withstand voltage of 600V and a rated current carrying capacity of 10A. A freewheeling diode is connected in reverse parallel across the coil to absorb the reverse induced electromotive force generated when the coil is de-energized, preventing the drive transistor Q1 from being damaged by high voltage. A 10Ω / 10W cement power current-limiting resistor R3 is connected in series at the rear of the K1 contacts to specifically suppress the surge current generated by the charging of the energy storage capacitor during power-on, protecting the rectifier bridge and electrolytic capacitor from damage by the instantaneous surge current. The rectifier bridge D2 uses a 10A / 600V single-phase full-bridge rectifier module. One AC end is connected to the current-limiting resistor R3, and the other end is directly connected to the AC neutral line N. The positive terminal of the rectified output is connected to the high-voltage bus HV+, and the negative terminal is connected to the common high-voltage ground HV-. The full-bridge structure completes the conversion from AC to pulsating DC. The energy storage filter unit consists of two 450V, 220μF aluminum electrolytic capacitors, C2 and C3, connected in series. The overall withstand voltage after series connection reaches 900V, providing ample voltage margin for the 310V bus. Each capacitor is connected in parallel with a 1MΩ high-voltage discharge resistor, quickly releasing residual high voltage after power failure, reducing the risk of electric shock during maintenance. During the initial power-on phase, K1 has no drive signal and its contacts remain open, completely cutting off high voltage to the main circuit and preventing surge current interference with the MCU's voltage sampling accuracy. When connected to an AC 220V grid, the voltage multiplier branch is completely disconnected. After a delay, K1 engages, and the AC power is directly rectified by the full-bridge rectifier. After being filtered in series by C2 and C3, a stable 310V output is output to the bus. When connected to an AC 110V grid, the circuit first performs a pre-boost in the voltage multiplier branch, and only after the voltage stabilizes does it close K1 to connect to the main circuit for load operation.

[0019] The auxiliary voltage multiplier circuit is located on the AC neutral side and consists of relay K2, high-voltage fast recovery diode D1, and energy storage capacitor C1. It abandons the traditional design of adding an auxiliary rectifier bridge and an independent secondary power supply circuit, relying solely on a single diode to complete the voltage multiplication charging. K2 is also a 12V, 600V / 10A electromagnetic relay, with its coil matched to a freewheeling protection diode. The contacts are connected in series in the neutral branch, with one end connected to the AC neutral line N and the other end connected to the anode of the high-voltage diode D1. D1 is a 1000V high-voltage fast recovery diode with sufficient reverse withstand voltage margin. Its cathode is connected to the negative terminal of energy storage capacitor C1, and the positive terminal of C1 is directly coupled to the main circuit high-voltage bus HV+. C1 is a 450V, 220μF electrolytic capacitor, with an independent high-voltage discharge resistor connected in parallel across its two ends. When the device detects a low AC110V input, the MCU controls K2 to engage the conduction branch. The AC half-wave, through the unidirectional conduction of D1, continuously charges C1. The stored voltage in C1 is superimposed on the terminals of C2 and C3 in the main circuit, raising the original rectifier bus voltage from approximately 150V to the standard 310V. When a high AC220V input is detected, K2 remains disconnected, and the voltage multiplier branch is completely disconnected from the circuit, preventing voltage superposition and avoiding overvoltage damage to the downstream power devices. The entire voltage multiplier unit has no redundant rectifier components, significantly simplifying the PCB wiring, reducing the board area, and simultaneously reducing the number of materials and overall production costs.

[0020] The dual-channel relay drive circuit consists of two independent NPN switching transistors and base-limiting current-limiting resistors, respectively controlling the power supply of coils K1 and K2. The base of transistor Q1, which drives K1, is connected in series with a 1kΩ current-limiting resistor R1, and the base of transistor Q2, which drives K2, is connected in series with a 1kΩ current-limiting resistor R2. These two resistors are directly connected to the MCU's general-purpose I / O control pins. When the MCU outputs a high level, the transistor base conducts, and the collector current flows through the relay coil, causing the contacts to close. When the I / O outputs a low level, the transistor is cut off, and the relay coil is de-energized and disconnects. Q1 and Q2 are general-purpose NPN switching transistors with a withstand voltage of 50V or higher, featuring low saturation voltage drop, fast switching response, and an operating temperature range covering -40℃ to 105℃, suitable for industrial high and low temperature environments. The current-limiting resistors limit the output current of the MCU pins to prevent overcurrent burnout of the I / O ports, while also matching the transistor's conduction threshold to ensure lag-free and error-free high-low level switching.

[0021] The high-voltage voltage divider sampling circuit consists of three high-precision high-voltage surface-mount resistors R4, R5, and R6 connected in series. All are 1% precision, high-voltage withstand surface-mount resistors, with the total series resistance controlled within the tens of megohms range. One end is connected to the high-voltage bus HV+, and the other end is connected to the MCU's built-in ADC sampling pin to generate the POWER_IN sampling signal. The lower end of the resistor is connected to the MCU's low-voltage analog ground, achieving linear attenuation of the high-voltage to 0~3.3V low-voltage sampling signal. The three-resistor series structure improves the overall insulation withstand voltage level, reduces the voltage division amplitude of a single resistor, avoids accelerated aging of a single resistor under long-term high voltage, and controls the linearity error of the sampling signal within 5%. The MCU can accurately distinguish between 110V and 220V input levels. The sampling circuit only collects voltage during the power-on no-load phase. When the main circuit relay is not closed, there is only a weak induced voltage on the bus, with no load voltage drop interference, which greatly improves the identification accuracy. During normal operation of the whole machine, the voltage divider circuit continuously collects the bus voltage in real time. Once a large abnormal voltage fluctuation occurs, the MCU will lock the current on / off state of the two relays and no longer perform switching actions to prevent frequent switching of relays from causing device damage and violent oscillation of bus voltage.

[0022] The MCU voltage sampling control module uses an 8-bit general-purpose microcontroller with a built-in multi-channel ADC, operates on a 3.3V power supply, and has internally embedded voltage judgment thresholds and graded power-on timing programs, eliminating the need for external complex algorithm chips. Upon power-up, the MCU completes peripheral initialization, defaulting to a low-level output to disable Q1 and Q2, and disconnecting K1 and K2 to enter a no-load silent sampling state. The MCU continuously samples the POWER_IN voltage divider three times, performs mean filtering on the three sets of values ​​to filter out sampling interference caused by power-on noise and grid harmonics, and determines the grid specifications by comparing the mean value with an internally preset threshold. If the voltage condition is determined to be AC110V low voltage, the MCU first outputs a high level to Q2 to conduct K2, connecting the voltage doubler branch. It maintains this high level for a delay of 150ms to 300ms, waiting for C1 to charge and the bus voltage to stabilize and rise. After the delay, it outputs a high level to conduct Q1 and engage K1, allowing the main rectifier circuit to operate normally with the load connected. If the voltage condition is determined to be AC220V high voltage, the MCU continuously maintains a low level output for Q2, keeping K2 always open. The voltage doubler branch does not participate in the operation. After waiting 100ms for the voltage to stabilize, it conducts Q1 to close the main circuit relay. During the load operation phase, the MCU continuously and cyclically collects the bus voltage. When it detects a drastic fluctuation in the bus voltage exceeding the normal range, it immediately locks the drive levels of both relays, prohibiting any on / off switching actions. Hardware-level overvoltage and surge protection is achieved through timing logic to prevent the downstream inverter and switching power devices from burning out due to abnormal voltage.

[0023] The entire solution uses universal standard discrete components, without custom-designed dedicated power management chips. This allows for a wide range of material sourcing channels and low costs, resulting in enhanced operational stability under high and low temperatures and electromagnetic interference environments. The single hardware circuit board eliminates the need to differentiate between 110V and 220V versions, removing the external manual voltage switch and completely avoiding safety hazards such as capacitor explosion, rectifier bridge burnout, and even system failure caused by manual operation. Its unique staged power-on sequence—first sampling under no-load conditions, then voltage multiplication, and finally closing the main circuit—suppresses power surge impacts from the source. Simultaneously, the single diode simplifies the voltage multiplier branch structure, eliminating the secondary auxiliary rectifier power supply circuit required in traditional solutions, simplifying PCB wiring and reducing overall size. It can be widely applied to civilian switching power supplies, brushless motor drivers, industrial frequency converter control power supplies, and other equipment requiring compatibility with global wide-voltage power grids.

[0024] It should be noted that, in order to simplify the description of the present invention and thus help to understand one or more embodiments of the invention, multiple features may sometimes be grouped into one embodiment, drawing or description thereof in the foregoing description of the embodiments of the present invention.

[0025] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A 110V / 220V automatic identification voltage doubler rectifier circuit, characterized in that: Includes an MCU voltage sampling control module, a main rectifier circuit, an auxiliary voltage multiplier circuit, a relay drive circuit, and a high-voltage divider sampling circuit; The main rectifier circuit includes a first relay K1, a current-limiting resistor R3, a rectifier bridge D2, an energy storage capacitor C2, and an energy storage capacitor C3. The first relay K1 is connected in series to the AC live wire L path. The auxiliary voltage multiplier circuit includes a second relay K2, a high-voltage diode D1, and an energy storage capacitor C1. The second relay K2 is connected in series to the AC neutral line N branch, and the positive terminal of the energy storage capacitor C1 is coupled to the high-voltage bus HV+ of the main rectifier circuit. The high-voltage divider sampling circuit is composed of high-voltage resistors R4, R5, and R6 connected in series. The POWER_IN sampling signal output by the voltage divider node is connected to the MCU's built-in ADC sampling pin. The relay drive circuit includes NPN switching transistors Q1 and Q2 and base limiting current resistors R1 and R2, with the transistors respectively driving the coils of the first relay K1 and the second relay K2. After the MCU is powered on, it controls both relays to disconnect, and automatically identifies the AC input voltage level by collecting the voltage divider under no-load and silent conditions. When the input is identified as AC110V low voltage, the second relay K2 is first turned on to connect to the auxiliary voltage multiplier circuit to complete the voltage boost. After a delay and stabilization, the first relay K1 is turned on to connect the main rectifier circuit. When the input is identified as AC220V high voltage, the second relay K2 remains open, and the first relay K1 is only turned on after a delay. Under both input conditions, the circuit outputs a stable 310V DC bus voltage.

2. The 110V / 220V automatic identification voltage doubler rectifier circuit according to claim 1, characterized in that: The auxiliary voltage multiplier circuit uses only a single high-voltage diode D1 to achieve voltage multiplication charging.

3. The 110V / 220V automatic identification voltage doubler rectifier circuit according to claim 2, characterized in that: During the circuit power-on detection phase, the first relay K1 and the second relay K2 remain in the open state simultaneously, adopting the no-load silent sampling mode.

4. The 110V / 220V automatic identification voltage doubler rectifier circuit according to claim 2, characterized in that: The high-voltage voltage divider sampling circuit adopts a voltage divider structure with multiple high-voltage chip resistors connected in series.

5. The 110V / 220V automatic identification voltage doubler rectifier circuit according to claim 1, characterized in that: Energy storage capacitors C2 and C3 are arranged in series. Both are 450V withstand voltage electrolytic capacitors. Each energy storage capacitor is connected in parallel with an independent high voltage discharge resistor to quickly release the residual high voltage of the capacitor after the equipment is powered off.

6. The 110V / 220V automatic identification voltage doubler rectifier circuit according to claim 5, characterized in that: The current-limiting resistor R3 is a high-power cement resistor, connected in series between the first relay K1 and the rectifier bridge D2, to suppress the surge current of the energy storage capacitor during power-on.

7. The 110V / 220V automatic identification voltage doubler rectifier circuit according to claim 5, characterized in that: Both the coils of the first relay K1 and the second relay K2 are connected in reverse parallel with freewheeling diodes to absorb the reverse induced electromotive force at the moment the relays are disconnected.

8. A 110V / 220V adaptive universal voltage doubler rectifier control method, applied to the adaptive universal voltage doubler rectifier circuit according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: The device is powered on, the MCU completes initialization, and controls the first relay K1 and the second relay K2 to disconnect, and the circuit enters the no-load silent state; Step 2: The MCU repeatedly collects the POWER_IN voltage divider sampled voltage, removes noise interference through the mean filtering algorithm, compares the calculated average voltage with the internal preset threshold, and determines whether the current power grid is under AC110V low voltage condition or AC220V high voltage condition. Step 3: If the AC110V low voltage condition is determined, the MCU controls the transistor Q2 to turn on and the second relay K2 to be activated, connecting the auxiliary voltage multiplier circuit. After the bus voltage stabilizes and is delayed for 150ms-300ms, the transistor Q1 is turned on and the first relay K1 is activated, and the main rectifier circuit is connected to the load and operates normally. Step 4: If the AC220V high voltage condition is determined, the MCU keeps transistor Q2 off and the second relay K2 open. The auxiliary voltage multiplier circuit does not participate in the work. After a 100ms delay, transistor Q1 is turned on and the first relay K1 is energized after the rectified voltage stabilizes. Step 5: During the normal load operation phase of the whole machine, the MCU continuously collects the bus voltage in real time. When a large abnormal fluctuation in the bus voltage is detected, the current on / off state of the two relays is locked, and the relay switching action is prohibited to realize voltage abnormality protection.

9. A 110V / 220V adaptive universal voltage doubler rectifier control method according to claim 8, characterized in that, In step two, the MCU continuously collects at least three sets of sampled voltages to calculate the average value, filtering out sampling errors caused by power-on instantaneous interference and power grid harmonics.

10. The 110V / 220V adaptive universal voltage doubler rectifier control method according to claim 8, characterized in that, In step five, after the MCU locks the relay drive level, the lock is not released until the device is powered off and restarted.

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