An automatic phase sequence switch

Abstract

The utility model discloses an automatic phase sequence switch, relate to low voltage electrical apparatus field, can monitor the state of three -phase input voltage simultaneously, and when one phase or two -phase failure occurs, the output load is switched to the power supply circuit composed by the remaining normal phase line intelligently. Including three -phase power input terminal, two -way power output terminal, three -way voltage detection module, power processing module, execution module and control module, control module is connected with three -way voltage detection module, execution module electricity respectively, to receive three -way voltage detection module's signal, judges whether voltage exists overvoltage, under -voltage or phase -sequence abnormality, and according to preset overvoltage threshold value, under -voltage threshold value and phase -sequence priority logic, judges the available state of current each phase and generates switching control instruction, the execution module receives the switching control instruction that control module sent, and its output end connects two -way power output terminal, is used for according to instruction and carries out automatic switching between two different phase line combinations.

Description

Technical Field

[0001] This utility model relates to the field of low-voltage electrical appliances, and in particular to an automatic phase sequence changer switch. Background Technology

[0002] In low-voltage power distribution systems, three-phase four-wire power supply is widely used in various settings such as residences, shopping malls, schools, and factories. Due to factors such as power grid load fluctuations, line faults, and equipment start-ups and shutdowns, abnormal situations such as overvoltage, undervoltage, or even phase loss often occur in a particular phase. If such voltage abnormalities are not addressed promptly, they can, at best, affect the normal operation of electrical equipment, and at worst, cause equipment damage and economic losses.

[0003] To address these issues, various types of over / under voltage protectors and phase sequence switches have emerged in the market. Traditional over / under voltage protectors typically cut off the circuit directly upon detecting an abnormal voltage, requiring manual intervention for reset. They cannot provide continuous power supply and have a low level of intelligence. Existing automatic phase sequence switches can only achieve simple main / backup power switching and cannot simultaneously monitor the voltage status of multiple three-phase power sources. While these products can achieve some automatic switching functionality, their structure limits their ability to meet application scenarios requiring flexible selection and combination of two normal power outputs from three-phase power sources.

[0004] In practical applications, when one or two phases in a power line experience abnormal voltage, incorrect phase sequence, voltage instability due to loose connections, or sudden power outages followed by power restoration, the device cannot autonomously identify the remaining normal phase sequence power supply. Manual troubleshooting and switching of the power supply circuit are essential. This reliance on manual intervention not only prolongs power outage time but also increases the risk of damage to electrical equipment such as precision machine tools, air conditioning systems, and data servers due to unstable power supply caused by delayed switching, resulting in economic losses. Furthermore, existing devices suffer from insufficient functional adaptability and reliability. Most products lack flexible phase sequence adjustment functions, and over / under voltage protection parameters are fixed in the hardware circuitry, making it impossible to customize settings based on the characteristics of different regional power grids. For example, remote areas experience large voltage fluctuations, while urban power grids are prone to transient overvoltages; fixed parameters cannot adequately meet the protection needs of different scenarios. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing an automatic phase sequence switching switch that integrates multi-power source detection, intelligent phase sequence switching, and over / under voltage protection. It can simultaneously monitor the status of the three-phase input voltage and intelligently switch the output load to the power supply circuit composed of the remaining normal phase lines when one or two phases fail, thereby maintaining the continuity of power supply to the maximum extent.

[0006] The technical solution of this utility model is as follows: an automatic phase sequence switching switch, characterized in that it includes a three-phase power input terminal, two power output terminals, a three-channel voltage detection module, a power processing module, an execution module, and a control module; the three-phase power input terminal is connected to an external three-phase four-wire power supply, corresponding to phase lines L1, L2, and L3 and the neutral line N; the two power output terminals are connected to the corresponding external loads to provide power; the input terminals of the three-channel voltage detection modules are connected to the three-phase power input terminals to sample the effective voltage values ​​of the three-phase power input terminals in real time; the power processing module converts the external AC power into the stable DC voltage required by each module; the control module is electrically connected to the three-channel voltage detection module and the execution module to receive signals from the three-channel voltage detection module, determine whether there is overvoltage, undervoltage, or phase loss abnormality, and determine the current availability status of each phase and generate switching control commands based on preset overvoltage thresholds, undervoltage thresholds, and phase sequence priority logic; the execution module receives the switching control commands issued by the control module, and its output terminal is connected to the two power output terminals to automatically switch the output between two different phase line combinations according to the commands.

[0007] By adopting the above technical solution, and by setting up a three-phase power input and two power outputs, and integrating voltage detection, control, and execution modules, a complete intelligent switching system is constructed. This solves the problem that existing devices cannot flexibly select and combine two outputs from three-phase inputs. Specifically, the three-phase voltage detection module achieves comprehensive perception of the three-phase power status, avoiding the omission of voltage anomalies in existing devices. The cooperation between the execution and control modules can filter and combine two effective outputs from the three-phase power supply. The power processing module ensures stable power supply to each unit, guaranteeing the foundation for system operation. Thus, when any one or two phases experience overvoltage, undervoltage, or... In the event of a phase loss fault, the control module automatically shields the faulty phase and immediately drives the execution module to seamlessly switch the load to the remaining normal phase, ensuring that the two output terminals continuously output qualified voltage. This ultimately achieves real-time monitoring and intelligent judgment of the three-phase voltage status and can automatically generate switching commands. This overcomes the shortcomings of traditional protectors that can only provide power-off protection or simple switching and require manual reset, improving the continuity and reliability of the power supply system. It provides a foundation for making full use of the remaining normal phase lines to maintain power supply, minimizing the problem of a complete power outage of the load due to a single-phase fault, and effectively preventing damage to electrical equipment due to power outages or abnormal voltage.

[0008] In one possible design, the control module includes a main control microcontroller (U2). The main control microcontroller has built-in program logic configured as follows: upon power-up, it initiates an initialization process, loading preset overvoltage thresholds, undervoltage thresholds, phase sequence priorities, and detection delay parameters; it receives real-time voltage RMS data transmitted from three voltage detection modules, compares each phase voltage with the overvoltage and undervoltage thresholds, and determines whether each phase is in a usable state based on the presence or absence of voltage (voltage within the threshold range and without phase loss is considered usable); when an overvoltage, undervoltage, or phase loss anomaly is detected in the currently supplied phase line combination, it selects two valid phase line combinations from the remaining usable phase lines according to the phase sequence priority logic; if only one phase line combination is usable, the control execution module switches both power output terminals to that combination; if two or more phase line combinations are usable, they are allocated to the two output terminals according to priority; when the original abnormal phase line recovers to a usable state and the duration exceeds the preset recovery delay, it determines whether to switch back to the original phase line combination according to the priority logic.

[0009] By adopting the above design, the initialization loading of preset parameters in the program logic establishes the foundation for parameterized control, avoiding the problem of rigid functions in traditional devices. Real-time voltage comparison and availability status judgment ensure accurate identification of overvoltage, undervoltage, and phase loss anomalies, solving the pain points of low efficiency and high misjudgment rate of manual troubleshooting. The logic of selecting two sets of effective phase line combinations in case of anomalies specifically addresses the shortcomings of existing devices that cannot flexibly adapt to the two-way output requirements under multi-phase faults, ensuring uninterrupted power supply to the load. The recovery delay judgment mechanism avoids frequent switching caused by instantaneous fluctuations in the power grid, while preventing power supply lag after fault recovery, further improving power supply stability and switching rationality, and reducing equipment losses caused by frequent start-stop. Thus, through the program logic built into the main control microcontroller, the entire process of power-on initialization, parameter loading, voltage comparison, status judgment, priority selection, and delay recovery is fully automated and intelligently controlled, making switching decisions more accurate and reliable without manual intervention.

[0010] In one possible design, a human-machine interface module is also included, which includes setting buttons (K1-K4) and status indicator units (LED1-LED4). The setting buttons are connected to the corresponding ports of the control module and are used to set overvoltage protection values, undervoltage protection values, delay time, and switching priority parameters. The status indicator units are driven by the control module and are used to display the system operating status, fault information, and the current output phase sequence source.

[0011] By adopting the above design, key parameters such as overvoltage protection value and delay time can be customized by setting buttons. This allows the device to flexibly adapt to different power grid characteristics, such as large voltage fluctuations in remote areas and frequent transient overvoltages in urban areas. This enhances the product's environmental adaptability and user configurability, and solves the problem of fixed-parameter products having limited applicable scenarios. The status indicator unit displays the system's operating status, fault type, and phase sequence source in real time and intuitively, providing a good human-machine interaction experience. This makes it easy for users to quickly understand the equipment status and troubleshoot faults, improving the maintainability of the equipment.

[0012] In one possible design, the three-channel voltage detection module includes three independent voltage detection circuits, each corresponding to a three-phase voltage. Each voltage detection circuit includes a current-limiting resistor (R29, R30, or R31) connected in series, a sampling resistor (R26, R27, or R28), and a voltage divider resistor (R39, R32, or R33) connected in parallel between the two.

[0013] The above design employs a series voltage divider network consisting of a current-limiting resistor, a sampling resistor, and a voltage divider resistor. This network can safely and accurately attenuate the high-voltage AC signal to a low-voltage range that the microcontroller can process, achieving electrical isolation between the high-voltage side and the low-voltage control circuit and ensuring system safety. At the same time, the three independent and identical detection circuits ensure the consistency and accuracy of the three-phase voltage sampling, providing a solid foundation for the control module to make accurate voltage judgments and reliable switching decisions.

[0014] In one possible design, the power processing module includes a rectifier unit, a switching converter unit, and a linear regulator unit connected in sequence. The input terminal of the rectifier unit is connected to a three-phase power input terminal and includes rectifier diodes (D1-D6). The switching converter unit is an AC220V to DC12V switching converter unit, composed of a resistor (R40), a switching power supply chip (IC1), diodes (D10, D11), and filter capacitors (EC1, EC2). The linear regulator unit is a DC12V to DC5V regulator unit, composed of a three-terminal regulator chip (IC5), a capacitor C11, and a filter capacitor (EC4). The output terminal of the switching converter unit provides the +12V DC operating power required by the execution module, and the output terminal of the linear regulator unit provides the +5V DC operating power required by the control module and the human-machine interface module.

[0015] With the above design, the power processing module adopts a multi-stage structure of rectification, switching conversion, and linear regulation. First, the switching power supply performs high-efficiency AC / DC step-down conversion, and then the linear regulator provides clean and stable low-voltage DC power, balancing conversion efficiency and output power quality. The two-stage power supply provides independently optimized power to the execution module and the control and human-machine interaction module, respectively, meeting the voltage and current requirements of different circuit modules and ensuring the stable and reliable operation of the entire system.

[0016] In one possible design, the execution module includes three magnetic latching relays (K5, K6, K7) and three identical relay drive circuits. Each drive circuit consists of a driver chip (IC2, IC3, or IC4), a current-limiting resistor (R36, R14, or R18), a bias resistor (R37, R38, or R16), and a filter capacitor (C8, C9, or C10). The input terminals of the three magnetic latching relays are respectively connected to the L1, L2, and L3 phase lines of the three-phase power input terminals, and the output terminals are connected to the two power output terminals through the O1-1 / O1-2, O2-1 / O2-2, and O3-1 / O3-2 contact combinations. The control terminal of the driver chip is electrically connected to the I / O port of the main control microcontroller (U2).

[0017] With the above design, the three-way magnetic latching relays achieve flexible phase switching through contact combinations such as O1-1 / O1-2. Only one pulse current is needed to complete the switching or reset action and maintain the state, resulting in a faster response speed. Moreover, each magnetic latching relay is equipped with a drive circuit composed of a dedicated drive chip, forming a standardized drive circuit that can provide a large instantaneous current sufficient to drive the relay coil. Thus, through the combined control of the three relays, the connection relationship between the three-phase input and the two-way output is flexibly configured, ensuring that the switching commands of the control module can be executed accurately, realizing reliable switching between the two outputs in different phase combinations, and maintaining power supply continuity even in multi-phase alternating fault scenarios, thereby improving the reliability and response efficiency of the device's execution links. Attached Figure Description

[0018] Figure 1 This is a block diagram of the operational logic of this utility model; Figure 2 This is a circuit diagram of the three-channel voltage detection module and the power processing module of this utility model; Figure 3 This is a circuit schematic diagram of the execution module of this utility model; Figure 4 This is the circuit schematic diagram of the control module of this utility model; Figure 5 This is the circuit schematic diagram of the human-computer interaction module of this utility model; The system includes: 1. Three-channel voltage detection module; 2. Power processing module; 21. Rectifier unit; 22. Switching conversion unit; 23. Linear voltage regulation unit; 3. Execution module; 4. Control module; and 5. Human-machine interaction module. Detailed Implementation

[0019] like Figures 1 to 5 An automatic phase sequence changeover switch is shown, comprising a three-phase power input terminal, two power output terminals, a three-channel voltage detection module 1, a power processing module 2, an execution module 3, and a control module 4. All modules are integrated into a 3P+N pole housing, suitable for three-phase four-wire power distribution systems, and can be deployed in factory distribution cabinets or shopping mall distribution rooms. The three-phase power input terminal is connected to external phase lines L1, L2, and L3 and the neutral line N. The input terminals of the three-channel voltage detection module 1 are connected one-to-one with the three-phase power input terminals, and the output terminals are connected to the control module 4 via VA, VB, and VC signal lines through pins. The input terminal of the power processing module 2 is connected to any phase line and the neutral line of the three-phase power input terminal, and the output terminals are respectively led out as DC12V and DC5V, with power signals transmitted synchronously via pin headers. The control module 4 is electrically connected to the control terminal of the driver chip of the execution module 3 through an I / O port, and the relay output contacts of the execution module 3 are correspondingly connected to the two power output terminals. The two power output terminals are respectively connected to loads such as data servers, air conditioning systems, and machine tools to achieve dual-channel continuous power supply.

[0020] The control module 4 is based on the main control microcontroller U2, which is a 45-pin package and has 15 built-in ADC interfaces. The ADC2 pin is configured on P54 and is used to receive the analog signals from the three voltage detection modules 1. The power supply voltage is DC5V.

[0021] Program logic execution flow 1. Power-on initialization: After the device is powered on, the microcontroller loads preset parameters after a 100ms start-up delay, such as overvoltage threshold 270V, undervoltage threshold 170V, phase sequence priority ABC, detection delay 10s, and recovery delay 10s.

[0022] 2. Status detection: The VA, VB, and VC signals are acquired in real time through the ADC interface (sampling frequency 10Hz). The converted digital voltage values ​​are compared with preset thresholds. If the voltage of a certain phase is >270V or <170V, or the signal amplitude is close to 0 (phase loss), it is determined to be in an unusable state.

[0023] 3. Abnormal switching: If L1 in the current power supply L1-L2 combination is overvoltage, the microcontroller detects that L2 and L3 are normal according to the ABC priority logic and generates a switching instruction: the control execution module 3 switches the first output to the L2-L3 combination, and the second output remains in the L2-L3 combination (dual-channel multiplexing when only one set is available).

[0024] 4. Recovery control: After the L1 voltage recovers to 230V and remains there for 10 seconds, the microcontroller detects that it is available and generates an instruction according to priority logic to switch the first output back to the L1-L2 combination, thus achieving seamless recovery.

[0025] The human-machine interface module 5 includes a setting button circuit and a status indicator unit, both of which are directly electrically connected to the I / O ports of the main control microcontroller. The setting buttons are configured as follows: K1 is the SET button, K2 is the ADD button, K3 is the DEC button, and K4 is the SW button. All are touch-sensitive buttons, with one end connected to the corresponding pin of the microcontroller and the other end grounded. A short press of the SET button enters the parameter menu. Parameters are adjusted using the ADD / DEC buttons. Pressing the SET button continues until all parameters are set, then saving and exiting. Parameters are stored in the microcontroller's built-in EEPROM and are not lost when power is off. The status indicator unit includes LED1 (fault light, red), LED2 (L1 phase closed light, red), LED3 (L2 phase closed light, red), and LED4 (L3 phase closed light, red). Additionally, three digital tubes are added to display the L1, L2, and L3 voltage values ​​respectively, enabling dynamic voltage value refresh display. During normal operation, the corresponding phase closing indicator light is always on; when a phase experiences overvoltage, the corresponding phase closing indicator light goes out, and the digital display shows the corresponding phase voltage and the corresponding letter code for the fault; after the fault is cleared, the indicator light automatically turns off.

[0026] The three-channel voltage detection module 1 includes three independent voltage detection circuits, each with the same circuit structure, corresponding to the detection of phase lines L1, L2, and L3. For example, one voltage detection circuit consists of a current-limiting resistor R29, a sampling resistor R26, and a voltage divider resistor R39. One end of the current-limiting resistor R29 is connected to the live wire input terminal L1, and the other end is connected in series with the sampling resistor R26. One end of the 10KΩ voltage divider resistor R39 is connected to the common node of the current-limiting resistor R29 and the sampling resistor R26, and the other end is grounded. The current-limiting resistor prevents high voltage from directly impacting subsequent circuits, ensuring the hardware safety of the three-channel voltage detection module 1. The combination of the sampling resistor and the voltage divider resistor optimizes the voltage division ratio and improves the accuracy of voltage sampling. In addition, the three-channel voltage detection module 1 also includes a voltage filtering circuit, which can filter out signal ripple caused by power grid fluctuations and electromagnetic interference, ensuring that the voltage signal transmitted to the control module 4 is stable and reliable. In this way, the high-voltage AC signal is safely divided into a low-voltage signal that can be acquired by the microcontroller, and high-frequency interference is filtered out by the voltage filtering circuit, ensuring the accuracy and stability of the sampled data.

[0027] The power processing module 2 adopts a three-stage architecture consisting of a rectifier unit 21, a switching conversion unit 22, and a linear voltage regulator unit 23 to complete AC-DC conversion and multi-stage voltage regulation. The rectifier unit 21 consists of a three-phase bridge rectifier circuit composed of six rectifier diodes D1-D6. The input terminal is connected to the three-phase power input terminals L1, L2, L3, and N, and the output terminal is approximately 325V pulsating DC. The switching converter unit 22 consists of a switching power supply chip IC1, an energy storage inductor L4, diodes D10 and D11, a current-limiting resistor R40, and filter capacitors EC1 and EC2. The current-limiting resistor R40 is connected to the high-voltage input terminal of the switching power supply chip IC1, and the chip output terminal is connected to one end of the energy storage inductor L4. The other end of L4 is connected to the anode of diode D10. The cathode of D10 is connected to the positive terminal of EC3 and the DC12V output terminal, and the negative terminal of EC2 is grounded, forming a flyback switching power supply topology. The pulsating DC power is filtered by the high-voltage filter capacitors EC1 and EC2 and then sent to the switching power supply controller IC1 and its peripheral circuits to be converted into a stable +12V DC power supply. The linear voltage regulator unit 23 consists of a three-terminal voltage regulator chip IC5, and filter capacitors EC4 and C11. The DC12V input terminal is connected to the input terminal of the voltage regulator chip IC5, and the output terminal of the voltage regulator chip IC5 is connected in parallel with the filter capacitors EC4 and C11 to lead out DC5V. All capacitors are grounded; this realizes the conversion of DC12V to DC5V to power the microcontroller and other precision circuits such as digital tubes.

[0028] Execution module 3 includes magnetic latching relays K5, K6, and K7 and their corresponding drive circuits, with each drive circuit having the same structure. For example, taking the drive circuit of magnetic latching relay K5 as an example, a single-channel relay drive circuit consists of a driver chip IC2, a current-limiting resistor R36, a bias resistor R37, and a filter capacitor C8. The control signal from the microcontroller U2 is connected to the INA pin of the driver chip IC2 via resistor R37. The chip's VDD terminal is connected to DC12V, and its GND terminal is grounded. The OA output terminal is connected to one end of the relay K5 coil via R36, and the other end of the coil is connected to DC12V. C8 is connected in parallel between the chip's VDD and GND to stabilize the drive voltage. The coils of the three magnetic latching relays are independently controlled by three drive circuits. Their common terminal contacts are connected to the L1, L2, and L3 inputs respectively, while their normally open / normally closed output contacts are cross-connected to terminals O1-1 / O1-2, O2-1 / O2-2, and O3-1 / O3-2. By controlling the on / off combination of the three relays through a microcontroller, the function of connecting any two phases to the output terminal can be realized.

[0029] The overall working process of the automatic phase sequence changer in this application is as follows: 1. After the device is powered on, the power processing module 2 outputs DC12V and DC5V, the control module 4 initializes the parameters, LED1 lights up, and the digital tube displays the three-phase voltage; 2. The three-channel voltage detection module 1 samples the voltage signal in real time, and transmits it to the control module 4 after filtering; 3. If phase L3 experiences undervoltage, control module 4 determines that it is unavailable, selects L1-L2 as a valid combination based on ABC priority, and generates a switching command; 4. The driver chip of the execution module 3 receives the instruction, controls K5 and K6 to engage and K7 to disengage, switches both outputs to the L1-L2 combination, LED3 flashes, and the digital tube displays the L3 voltage and "UV". 5. After the L3 voltage returns to 220V and remains there for 10 seconds, the control module 4 drives K7 to engage, the second output switches back to the L2-L3 combination, LED3 turns off, and the normal display is restored.

[0030] This embodiment achieves accurate detection of three-phase voltage anomalies and intelligent switching between two outputs through the cooperation of various modules, effectively ensuring power supply continuity and adapting to the load requirements of multiple scenarios.

Claims

1. An automatic phase sequence changeover switch, characterized in that: It includes a three-phase power input terminal, a two-way power output terminal, a three-way voltage detection module, a power processing module, an execution module, and a control module; The three-phase power input terminal is connected to an external three-phase four-wire power supply, and corresponds to phase lines L1, L2, and L3 and the neutral line N; The two power output terminals are connected to the corresponding external loads to provide power. The input terminal of the three-channel voltage detection module is connected to the three-phase power input terminal to sample the effective voltage value of the three-phase power input terminal in real time. The power processing module converts external AC power into a stable DC voltage required by each module. The control module is electrically connected to the three voltage detection modules and the execution module respectively, so as to receive the signals from the three voltage detection modules, determine whether there is overvoltage, undervoltage or phase loss abnormality, and determine the availability status of each phase and generate switching control commands based on the preset overvoltage threshold, undervoltage threshold and phase sequence priority logic. The execution module receives the switching control command issued by the control module, and its output terminal is connected to the two power output terminals to automatically switch the output between two different phase line combinations according to the command.

2. The automatic phase sequence changer according to claim 1, characterized in that: The control module includes a main control microcontroller (U2), which has built-in program logic configured as follows: After power-on, the initialization process is started, loading preset overvoltage threshold, undervoltage threshold, phase sequence priority and detection delay parameters; The system receives the effective voltage data transmitted from the three voltage detection modules in real time, compares the voltage of each phase with the overvoltage threshold and undervoltage threshold, and determines whether each phase is in a usable state based on the presence or absence of voltage (the phase is usable if the voltage is within the threshold range and there is no missing phase). When an overvoltage, undervoltage, or phase loss anomaly is detected in the current power supply phase line combination, two valid phase line combinations are selected from the remaining available phase lines according to the phase sequence priority logic. If only one phase wire combination is available, the control execution module will switch both power output terminals to that combination; if two or more phase wire combinations are available, they will be allocated to the two output terminals according to priority. Once the original abnormal phase line returns to a usable state and the duration exceeds the preset recovery delay, the system will determine whether to switch back to the original phase line combination based on priority logic.

3. The automatic phase sequence changeover switch according to claim 1, characterized in that: It also includes a human-machine interaction module, which includes setting buttons (K1-K4) and status indicator units (LED1-LED4); the setting buttons are connected to the corresponding ports of the control module and are used to set overvoltage protection values, undervoltage protection values, delay time and switching priority parameters; the status indicator units are driven by the control module and are used to display the system working status, fault information and the current output phase sequence source.

4. The automatic phase sequence changeover switch according to claim 1, characterized in that: The three-channel voltage detection module includes three independent voltage detection circuits, each corresponding to a three-phase voltage. Each voltage detection circuit includes a current-limiting resistor (R29, R30 or R31) connected in series, a sampling resistor (R26, R27 or R28), and a voltage divider resistor (R39, R32 or R33) connected in parallel between the two.

5. The automatic phase sequence changer according to claim 2, characterized in that: The power processing module includes a rectifier unit, a switching converter unit, and a linear regulator unit connected in sequence. The input terminal of the rectifier unit is connected to the three-phase power input terminal and includes rectifier diodes (D1-D6). The switching converter unit is an AC220V to DC12V switching converter unit, composed of a resistor (R40), a switching power supply chip (IC1), diodes (D10, D11), and filter capacitors (EC1, EC2). The linear regulator unit is a DC12V to DC5V regulator unit, composed of a three-terminal regulator chip (IC5), a capacitor (C11), and a filter capacitor (EC4). The output terminal of the switching converter unit provides the +12V DC operating power required by the execution module, and the output terminal of the linear regulator unit provides the +5V DC operating power required by the control module and the human-machine interaction module.

6. The automatic phase sequence changer according to claim 2, characterized in that: The execution module includes three magnetic latching relays (K5, K6, K7) and three identical relay drive circuits. Each drive circuit consists of a drive chip (IC2, IC3, or IC4), a current-limiting resistor (R36, R14, or R18), a bias resistor (R37, R38, or R16), and a filter capacitor (C8, C9, or C10). The input terminals of the three magnetic latching relays are respectively connected to the L1, L2, and L3 phase lines of the three-phase power input terminals, and the output terminals are connected to the two power output terminals through the O1-1 / O1-2, O2-1 / O2-2, and O3-1 / O3-2 contact combinations. The control terminal of the drive chip is electrically connected to the I / O port of the main control microcontroller (U2).

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