A leakage current protection device for a three-phase intelligent power distribution unit for high-power supplies

Abstract

This utility model discloses a leakage current protection device for a three-phase intelligent power distribution unit with high power supply, belonging to the field of power technology. It includes an MCU, a communication module, a storage module, an address configuration module, a power supply module, a first leakage current detection unit, a second leakage current detection unit, a first AC contactor control unit, and a second AC contactor control unit. It solves the technical problem of realizing dual-path independent leakage current detection and fast and reliable disconnection control in a high-power three-phase power distribution unit. This utility model can realize independent detection and independent disconnection of different power circuits, avoiding power failure of the whole machine due to single-point fault. The detection signal is sent to the MCU through optocoupler isolation, which not only ensures human and machine safety but also improves anti-interference capability. The use of leakage current protection chip in conjunction with MOS + relay + AC contactor link can realize rapid response to leakage current faults and shorten the disconnection time.

Description

Technical Field

[0001] This utility model belongs to the field of power technology, and in particular relates to a leakage current protection device for a three-phase intelligent distribution unit of a high-power power supply. Background Technology

[0002] Existing high-power power distribution units are widely used in industrial power supply, data center power supply, and large equipment operation. Due to the large capacity and high current of three-phase power supplies, leakage faults can easily cause equipment damage, fires, and even personal injury. Traditional leakage protection devices mostly use single-channel leakage detection + single contactor control, which has the following shortcomings.

[0003] Single detection: Most systems only perform single-circuit leakage detection on the main incoming line, and cannot achieve independent protection for branch circuits. Once a leakage occurs in one circuit, it can easily lead to a power outage of the entire machine, affecting the continuity of the system.

[0004] Insufficient isolation: In some solutions, the isolation between signal detection and control circuits is not high, which poses a risk of electromagnetic interference, malfunction, or missed operation, resulting in insufficient reliability.

[0005] Slow control response: Traditional solutions often rely on simple mechanical protection devices, which have a large action delay and cannot meet the requirements for rapid cut-off in high-power scenarios. Utility Model Content

[0006] The purpose of this invention is to provide a leakage current protection device for a high-power three-phase intelligent power distribution unit, which solves the technical problem of achieving dual-path independent leakage current detection and fast and reliable disconnection control in a high-power three-phase power distribution unit.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A leakage current protection device for a three-phase intelligent power distribution unit for high-power power supplies includes an MCU, a communication module, a storage module, an address configuration module, a power supply module, a first leakage current detection unit, a second leakage current detection unit, a first AC contactor control unit, and a second AC contactor control unit. The communication module, storage module, address configuration module, first leakage current detection unit, second leakage current detection unit, first AC contactor control unit, and second AC contactor control unit are all connected to the MCU; The first leakage current detection unit is connected to the first AC contactor control unit; the second leakage current detection unit is connected to the second AC contactor control unit. The power supply module provides power to the MCU, communication module, storage module, address configuration module, first leakage current detection unit, second leakage current detection unit, first AC contactor control unit, and second AC contactor control unit.

[0008] Preferably, the first leakage current detection unit includes a relay RL1, a field-effect transistor Q5, resistors R123, R126, and R120, an AC current transformer ZCT1, a resistor R129, a TVS diode DS1, a resistor R134, capacitors C115, C119, C114, and C111, a leakage current protection switch U20, capacitors C121, C116, and C117, resistors R128, R127, R130, and C118, an optocoupler U21, and a resistor R125. The gate of the field-effect transistor Q5 is connected to an IO port of the MCU through a resistor R123. The source is connected to ground, and the drain is connected to pin 2 of the relay RL1. The resistor R126 connects the gate and source of the field-effect transistor Q5. Relay RL1 has pin 1 connected to a 12V power supply, pin 4 connected to the first AC contactor control unit, and pin 3 connected to the first AC contactor control unit through resistor R120. AC current transformer ZCT1 measures the three-phase current signal input to the first AC contactor. Pin 1 of AC current transformer ZCT1 is connected to pin 1 of leakage current protection switch U20, and pin 2 is connected to pin 2 of leakage current protection switch U20 through resistor R134. A resistor R129 is connected between pins 1 and 2 of the AC current transformer ZCT1; Pin 3 of the TVS diode is connected to pin 1 of the AC current transformer ZCT1, and pins 1 and 2 are all connected to pin 2 of the AC current transformer ZCT1. Capacitor C115 is connected between pins 1 and 2 of the residual current device (RCD) U20. Pin 1 of the RCD U20 is connected to ground via capacitor C114, pin 2 is connected to ground via capacitor C119, pin 3 is connected to ground, pins 4 and 5 are both connected to ground via capacitor C121, pin 6 is connected to pin 7 of the RCD U20 via capacitor C116, pin 7 is connected to pin 1 of the optocoupler U21, and pin 8 is connected to the 12V power supply. Pin 7 of the residual current circuit breaker U20 is also connected to the ground wire through resistors R117 and R128 connected in parallel; A capacitor C118 and a resistor R127 are connected in parallel between pins 1 and 2 of the optocoupler U21. Pin 2 of the optocoupler U21 is connected to the ground line through resistor R130, pin 3 is connected to the ground line, and pin 4 is connected to an IO port of the MCU. Pin 4 of the optocoupler U21 is also connected to a 3.3V power supply through resistor R125. The circuit principle of the second leakage current detection unit is the same as that of the first leakage current detection unit.

[0009] Preferably, the leakage current protection switch U20 is model M54123L, the TVS diode DS1 is model MMBD7000, the relay RL1 is model HF46F / 12-HS1, the field effect transistor Q5 is model AO3400A, and the optocoupler U21 is model JC3H7.

[0010] Preferably, the power module includes a 3-phase power input module, a 12V switching power supply, a 5V power module, and a 3.3V power module; The input terminal of the 12V switching power supply is connected to a 3-phase power input module, the output terminal is connected to a 5V power module, and the 5V power module is connected to a 3.3V power module. The 3.3V power supply module provides power to the MCU, communication module, storage module, and address configuration module; The 5V power module supplies power to the 3.3V power module; The 12V switching power supply module outputs 12V power, and the 3.3V power supply module outputs 3.3V power. The 12V switching power supply module provides 12V power to the first leakage current detection unit, the second leakage current detection unit, the first AC contactor control unit, and the second AC contactor control unit; The 3-phase power input module includes an air switch K1, a transformer T1, and a transformer T2. Pins 1, 2, and 3 of the air switch K1 are connected to phases A, B, and C of the three-phase power supply, respectively. Pins 6 and 4 of the air switch K1 are connected to pin 1 of the transformer T1 and pin 2 of the transformer T2, respectively. Pin 5 of the air switch K1 is connected to pin 2 of the transformer T1 and pin 1 of the transformer T2, respectively. The circuit breaker K1 outputs phase L1-IN, phase L2-IN, and phase L3-IN power respectively from pins 6, 5, and 4. Transformer T1 outputs neutral wire N1 at pin 3 and live wire 220V-L1 at pin 4; transformer T2 outputs neutral wire N2 at pin 3 and live wire 220V-L2 at pin 4. The input terminals of the 12V switching power supply are connected to the neutral wire N2 and the live wire 220V-L2.

[0011] Preferably, the first AC contactor control unit includes a field-effect transistor Q4, a resistor R122, a resistor R124, a relay K2, an AC contactor JQ1, a capacitor C120, a resistor R135, and an LED D17. The gate of the field-effect transistor Q4 is connected to an I / O port of the MCU through the resistor R122, the source is connected to the ground wire, and the drain is connected to pin 2 of the relay K2. Relay K2's pin 1 is connected to a 12V power supply, pins 5 and 6 are both connected to AC contactor JQ1's pins 1, 4, and 3 are all connected to the 220V-L2 live wire; Pins 3, 4, and 5 of AC contactor JQ1 are connected to phase L1-IN, phase L2-IN, and phase L3-IN respectively; Pin 7 of AC contactor JQ1 is connected to the positive terminal of LED D17 through resistor R135, and the negative terminal of LED D17 is connected to pin 8 of AC contactor JQ1. Pin 2 of AC contactor JQ1 is connected to the neutral wire N2; Pins 1, 2, and 3 of capacitor 120 are connected to pins 8, 7, and 6 of AC contactor JQ1, respectively, and pin 4 of capacitor 120 is connected to ground. The circuit principle of the second AC contactor is the same as that of the first AC contactor.

[0012] Preferably, the field-effect transistor Q4 is model AO3400A, the relay K2 is model HF115F1DS3A, the AC contactor JQ1 is model JLJCQ-01, and the capacitor C120 is model CZMK-01.

[0013] Preferably, pin 4 of the relay RL1 is connected to the L2-IN phase of the input terminal of the AC contactor JQ1, and pin 3 is connected to the L1-IN phase of the input terminal of the AC contactor JQ1 through resistor R120. The AC current transformer ZCT1 is used to measure the current signals of phases L1-IN, L2-IN, L3-IN, and N2 entering the AC contactor JQ1.

[0014] This invention relates to a leakage current protection device for a high-power three-phase intelligent power distribution unit. It solves the technical problem of achieving independent dual-path leakage current detection and fast, reliable disconnection control in a high-power three-phase power distribution unit. The invention includes first and second leakage current detection units and corresponding AC contactor control units, enabling independent detection and disconnection of different power circuits. This avoids single-point faults causing power loss to the entire unit. The detection signal is sent to the MCU through optocoupler isolation, ensuring human-machine safety and improving anti-interference capabilities. The use of a leakage current protection chip in conjunction with a MOS + relay + AC contactor link enables rapid response to leakage current faults and shortens disconnection time. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the present invention. Figure 2 This is the circuit diagram of the 3-phase power input module of this utility model; Figure 3 This is the circuit diagram of the 12V switching power supply of this utility model; Figure 4 This is the circuit diagram of the MCU of this utility model; Figure 5 This is a circuit diagram of the address configuration module of this utility model; Figure 6 This is a circuit diagram of the 5V power supply module and the 3.3V power supply module of this utility model; Figure 7 This is the circuit diagram of the first leakage current detection unit of this utility model; Figure 8 This is the circuit diagram of the second leakage current detection unit of this utility model; Figure 9 This is the circuit diagram of the first AC contactor control unit of this utility model; Figure 10 This is the circuit diagram of the second AC contactor control unit of this utility model. Detailed Implementation

[0016] Depend on Figures 1-10 The leakage current protection device shown is for a three-phase intelligent power distribution unit for high-power power supply, including MCU, communication module, storage module, address configuration module, power module, first leakage current detection unit, second leakage current detection unit, first AC contactor control unit and second AC contactor control unit; In this embodiment, the MCU is an STM32F103C8T6, the communication module is an SP485EN, the storage module is a 24C02C-E / P, and the address configuration module is an address encoder composed of DIP switches CN3.

[0017] The power supply module provides power to the MCU, communication module, storage module, address configuration module, first leakage current detection unit, second leakage current detection unit, first AC contactor control unit, and second AC contactor control unit. The power module includes a 3-phase power input module, a 12V switching power supply, a 5V power module, and a 3.3V power module; The input terminal of the 12V switching power supply is connected to a 3-phase power input module, the output terminal is connected to a 5V power module, and the 5V power module is connected to a 3.3V power module. The 3.3V power supply module provides power to the MCU, communication module, storage module, and address configuration module; The 5V power module supplies power to the 3.3V power module; In this embodiment, the 5V power module is model 78M05, and the 3.3V power module is model AMS1117.

[0018] The 12V switching power supply module outputs 12V power, and the 3.3V power supply module outputs 3.3V power. The 12V switching power supply module provides 12V power to the first leakage current detection unit, the second leakage current detection unit, the first AC contactor control unit, and the second AC contactor control unit; The 3-phase power input module includes an air switch K1, a transformer T1, and a transformer T2. Pins 1, 2, and 3 of the air switch K1 are connected to phases A, B, and C of the three-phase power supply, respectively. Pins 6 and 4 of the air switch K1 are connected to pin 1 of the transformer T1 and pin 2 of the transformer T2, respectively. Pin 5 of the air switch K1 is connected to pin 2 of the transformer T1 and pin 1 of the transformer T2, respectively. The circuit breaker K1 outputs phase L1-IN, phase L2-IN, and phase L3-IN power respectively from pins 6, 5, and 4. Transformer T1 outputs neutral wire N1 at pin 3 and live wire 220V-L1 at pin 4; transformer T2 outputs neutral wire N2 at pin 3 and live wire 220V-L2 at pin 4. The input terminals of the 12V switching power supply are connected to the neutral wire N2 and the live wire 220V-L2.

[0019] In this embodiment, the 12V switching power supply consists of an AC-DC module BD2, a switching power supply chip U5, and a transformer T4. The AC-DC module BD2 is an ABS210, and the switching power supply chip U5 is a PN8395. The switching power supply circuit composed of PN8395 and ABS210 is a typical application circuit of PN8395, so it will not be described in detail.

[0020] The communication module, storage module, address configuration module, first leakage current detection unit, second leakage current detection unit, first AC contactor control unit, and second AC contactor control unit are all connected to the MCU; The first leakage current detection unit is connected to the first AC contactor control unit; the second leakage current detection unit is connected to the second AC contactor control unit. The first leakage current detection unit includes a relay RL1, a field-effect transistor Q5, resistors R123, R126, and R120, an AC current transformer ZCT1, a resistor R129, a TVS diode DS1, a resistor R134, capacitors C115, C119, C114, and C111, a leakage current protection switch U20, capacitors C121, C116, and C117, resistors R128, R127, R130, and C118, an optocoupler U21, and a resistor R125. The gate of the field-effect transistor Q5 is connected to an IO port of the MCU through a resistor R123. The source is connected to ground, and the drain is connected to pin 2 of the relay RL1. The resistor R126 connects the gate and source of the field-effect transistor Q5. Relay RL1 has pin 1 connected to a 12V power supply, pin 4 connected to the first AC contactor control unit, and pin 3 connected to the first AC contactor control unit through resistor R120. AC current transformer ZCT1 measures the three-phase current signal input to the first AC contactor. Pin 1 of AC current transformer ZCT1 is connected to pin 1 of leakage current protection switch U20, and pin 2 is connected to pin 2 of leakage current protection switch U20 through resistor R134. A resistor R129 is connected between pins 1 and 2 of the AC current transformer ZCT1; Pin 3 of the TVS diode is connected to pin 1 of the AC current transformer ZCT1, and pins 1 and 2 are all connected to pin 2 of the AC current transformer ZCT1. Capacitor C115 is connected between pins 1 and 2 of the residual current device (RCD) U20. Pin 1 of the RCD U20 is connected to ground via capacitor C114, pin 2 is connected to ground via capacitor C119, pin 3 is connected to ground, pins 4 and 5 are both connected to ground via capacitor C121, pin 6 is connected to pin 7 of the RCD U20 via capacitor C116, pin 7 is connected to pin 1 of the optocoupler U21, and pin 8 is connected to the 12V power supply. Pin 7 of the residual current circuit breaker U20 is also connected to the ground wire through resistors R117 and R128 connected in parallel; A capacitor C118 and a resistor R127 are connected in parallel between pins 1 and 2 of the optocoupler U21. Pin 2 of the optocoupler U21 is connected to the ground line through resistor R130, pin 3 is connected to the ground line, and pin 4 is connected to an IO port of the MCU. Pin 4 of the optocoupler U21 is also connected to a 3.3V power supply through resistor R125. The relay RL1 has its 4th pin connected to the L2-IN phase of the AC contactor JQ1, and its 3rd pin connected to the L1-IN phase of the AC contactor JQ1 via resistor R120. The AC current transformer ZCT1 is used to measure the current signals of phases L1-IN, L2-IN, L3-IN, and N2 entering the AC contactor JQ1.

[0021] Resistor R120 is the equivalent resistance of the external load. In actual use, a socket can be used as an equivalent replacement.

[0022] Relay RL1 is used in equipment that uses a mix of 220V and 380V to meet the requirement that only two phases of a three-phase system are used as the load power supply.

[0023] The leakage current protection switch U20 is model M54123L, the TVS diode DS1 is model MMBD7000, the relay RL1 is model HF46F / 12-HS1, the field effect transistor Q5 is model AO3400A, and the optocoupler U21 is model JC3H7.

[0024] In this embodiment, the first leakage current detection unit mainly consists of an AC current transformer ZCT1, a leakage current protection switch U20, an optocoupler U21, a relay RL1, and a MOSFET Q5. Its working principle is as follows: Leakage detection: The AC current transformer ZCT1 detects the phase current of the power supply circuit. Under normal circumstances, the vector sum of the three-phase currents is zero. If leakage to ground occurs, the three-phase currents will be unbalanced, and ZCT1 will output a differential mode current signal.

[0025] Signal conditioning and protection: The differential mode current signal is sent to the leakage protection chip U20 (M54123L) through a resistor voltage divider and RC filter circuit.

[0026] TVS tube DS1 is responsible for preventing surge interference.

[0027] U20 integrates leakage current detection and delay logic. When the leakage current exceeds the set threshold, its output is triggered, and the output signal is sent to the MCU through optocoupler U21 for isolation.

[0028] The MCU drives the MOSFET Q5 to activate the relay RL1, thereby turning on the detection circuit of the AC current transformer ZCT1.

[0029] The circuit principle of the second leakage current detection unit is the same as that of the first leakage current detection unit.

[0030] like Figure 8 The second leakage current detection unit consists of a relay RL2, a leakage protection switch U23, an optocoupler U24, and external resistors and capacitors.

[0031] The first AC contactor control unit includes a field-effect transistor Q4, a resistor R122, a resistor R124, a relay K2, an AC contactor JQ1, a capacitor C120, a resistor R135, and an LED D17. The gate of the field-effect transistor Q4 is connected to an IO port of the MCU through the resistor R122, the source is connected to the ground wire, and the drain is connected to pin 2 of the relay K2. Relay K2's pin 1 is connected to a 12V power supply, pins 5 and 6 are both connected to AC contactor JQ1's pins 1, 4, and 3 are all connected to the 220V-L2 live wire; Pins 1 and 2 of relay K2 are the coil terminals, and a freewheeling diode D16 is also connected between pins 1 and 2 of relay K2.

[0032] Pins 3, 4, and 5 of AC contactor JQ1 are connected to phase L1-IN, phase L2-IN, and phase L3-IN respectively; Pin 7 of AC contactor JQ1 is connected to the positive terminal of LED D17 through resistor R135, and the negative terminal of LED D17 is connected to pin 8 of AC contactor JQ1. Pin 2 of AC contactor JQ1 is connected to the neutral wire N2; Pins 1, 2, and 3 of capacitor 120 are connected to pins 8, 7, and 6 of AC contactor JQ1, respectively, and pin 4 of capacitor 120 is connected to ground. The field-effect transistor Q4 is model AO3400A, the relay K2 is model HF115F1DS3A, the AC contactor JQ1 is model JLJCQ-01, and the capacitor C120 is model CZMK-01.

[0033] The first AC contactor control unit mainly consists of MOSFET Q4, relay K2, AC contactor JQ1, and indicator light D17. Its working principle is as follows: The MCU's I / O port can drive MOSFET Q4 via resistor R122. When Q4 is turned on, relay K2 is energized and engaged. After relay K2 is engaged, its contacts provide 220V-L2 and neutral N2 control power to AC contactor JQ1. After Q1 is activated, its main contacts connect the three-phase input (L1-IN, L2-IN, L3-IN) to the load. Capacitor C120 is used for surge absorption to reduce the impact on the contactor coil. Resistor R135 and LED D17 form an indicator circuit to indicate the engaged status of AC contactor JQ1.

[0034] During use, users can use the detection results of the first leakage current detection unit to customize the control of the first AC contactor control unit. For example, when the first leakage current detection unit detects leakage, the MCU can control the disconnection of AC contactor JQ1 in the first AC contactor control unit to achieve a protection effect.

[0035] The circuit principle of the second AC contactor is the same as that of the first AC contactor.

[0036] The second AC contactor mainly consists of a field-effect transistor Q8, a relay K3, an AC contactor JQ2, and a capacitor C135.

[0037] In this embodiment, the first leakage current detection unit and the second leakage current detection unit can monitor the leakage current of the two circuits in real time, and the first AC contactor control unit and the second AC contactor control unit can jointly complete the independent switching control of different three-phase power supply circuits to achieve multi-path distribution and independent protection.

[0038] This invention relates to a leakage current protection device for a high-power three-phase intelligent power distribution unit. It solves the technical problem of achieving independent dual-path leakage current detection and fast, reliable disconnection control in a high-power three-phase power distribution unit. The invention includes first and second leakage current detection units and corresponding AC contactor control units, enabling independent detection and disconnection of different power circuits. This avoids single-point faults causing power loss to the entire unit. The detection signal is sent to the MCU through optocoupler isolation, ensuring human-machine safety and improving anti-interference capabilities. The use of a leakage current protection chip in conjunction with a MOS + relay + AC contactor link enables rapid response to leakage current faults and shortens disconnection time.

Claims

1. A leakage protection device for a three-phase intelligent distribution unit of a high-power power supply, characterized in that: It includes an MCU, a communication module, a storage module, an address configuration module, a power supply module, a first leakage current detection unit, a second leakage current detection unit, a first AC contactor control unit, and a second AC contactor control unit; The communication module, storage module, address configuration module, first leakage current detection unit, second leakage current detection unit, first AC contactor control unit, and second AC contactor control unit are all connected to the MCU; The first leakage current detection unit is connected to the first AC contactor control unit; the second leakage current detection unit is connected to the second AC contactor control unit. The power supply module provides power to the MCU, communication module, storage module, address configuration module, first leakage current detection unit, second leakage current detection unit, first AC contactor control unit, and second AC contactor control unit.

2. The leakage current protection device for a three-phase intelligent power distribution unit as described in claim 1, characterized in that: The first leakage current detection unit includes a relay RL1, a field-effect transistor Q5, resistors R123, R126, and R120, an AC current transformer ZCT1, a resistor R129, a TVS diode DS1, a resistor R134, capacitors C115, C119, C114, and C111, a leakage current protection switch U20, capacitors C121, C116, and C117, resistors R128, R127, R130, and C118, an optocoupler U21, and a resistor R125. The gate of the field-effect transistor Q5 is connected to an IO port of the MCU through a resistor R123. The source is connected to ground, and the drain is connected to pin 2 of the relay RL1. The resistor R126 connects the gate and source of the field-effect transistor Q5. Relay RL1 has pin 1 connected to a 12V power supply, pin 4 connected to the first AC contactor control unit, and pin 3 connected to the first AC contactor control unit through resistor R120. AC current transformer ZCT1 measures the three-phase current signal input to the first AC contactor. Pin 1 of AC current transformer ZCT1 is connected to pin 1 of leakage current protection switch U20, and pin 2 is connected to pin 2 of leakage current protection switch U20 through resistor R134. A resistor R129 is connected between pins 1 and 2 of the AC current transformer ZCT1; Pin 3 of the TVS diode is connected to pin 1 of the AC current transformer ZCT1, and pins 1 and 2 are all connected to pin 2 of the AC current transformer ZCT1. Capacitor C115 is connected between pins 1 and 2 of the residual current device (RCD) U20. Pin 1 of the RCD U20 is connected to ground via capacitor C114, pin 2 is connected to ground via capacitor C119, pin 3 is connected to ground, pins 4 and 5 are both connected to ground via capacitor C121, pin 6 is connected to pin 7 of the RCD U20 via capacitor C116, pin 7 is connected to pin 1 of the optocoupler U21, and pin 8 is connected to the 12V power supply. Pin 7 of the residual current circuit breaker U20 is also connected to the ground wire through resistors R117 and R128 connected in parallel; A capacitor C118 and a resistor R127 are connected in parallel between pins 1 and 2 of the optocoupler U21. Pin 2 of the optocoupler U21 is connected to the ground line through resistor R130, pin 3 is connected to the ground line, and pin 4 is connected to an IO port of the MCU. Pin 4 of the optocoupler U21 is also connected to a 3.3V power supply through resistor R125. The circuit principle of the second leakage current detection unit is the same as that of the first leakage current detection unit.

3. A leakage protection device for a three-phase intelligent distribution unit of a high-power power supply as claimed in claim 2, characterized in that: The leakage current protection switch U20 is model M54123L, the TVS diode DS1 is model MMBD7000, the relay RL1 is model HF46F / 12-HS1, the field effect transistor Q5 is model AO3400A, and the optocoupler U21 is model JC3H7.

4. A leakage protection device for a three-phase intelligent distribution unit of a high power supply as claimed in claim 2, wherein: The power module includes a 3-phase power input module, a 12V switching power supply, a 5V power module, and a 3.3V power module; The input terminal of the 12V switching power supply is connected to a 3-phase power input module, the output terminal is connected to a 5V power module, and the 5V power module is connected to a 3.3V power module. The 3.3V power supply module provides power to the MCU, communication module, storage module, and address configuration module; The 5V power module supplies power to the 3.3V power module; The 12V switching power supply module outputs 12V power, and the 3.3V power supply module outputs 3.3V power. The 12V switching power supply module provides 12V power to the first leakage current detection unit, the second leakage current detection unit, the first AC contactor control unit, and the second AC contactor control unit; The 3-phase power input module includes an air switch K1, a transformer T1, and a transformer T2. Pins 1, 2, and 3 of the air switch K1 are connected to phases A, B, and C of the three-phase power supply, respectively. Pins 6 and 4 of the air switch K1 are connected to pin 1 of the transformer T1 and pin 2 of the transformer T2, respectively. Pin 5 of the air switch K1 is connected to pin 2 of the transformer T1 and pin 1 of the transformer T2, respectively. The circuit breaker K1 outputs phase L1-IN, phase L2-IN, and phase L3-IN power respectively from pins 6, 5, and 4. Transformer T1 outputs neutral wire N1 at pin 3 and live wire 220V-L1 at pin 4; transformer T2 outputs neutral wire N2 at pin 3 and live wire 220V-L2 at pin 4. The input terminals of the 12V switching power supply are connected to the neutral wire N2 and the live wire 220V-L2.

5. A leakage current protection device for a three-phase intelligent power distribution unit as described in claim 4, characterized in that: The first AC contactor control unit includes a field-effect transistor Q4, a resistor R122, a resistor R124, a relay K2, an AC contactor JQ1, a capacitor C120, a resistor R135, and an LED D17. The gate of the field-effect transistor Q4 is connected to an IO port of the MCU through the resistor R122, the source is connected to the ground wire, and the drain is connected to pin 2 of the relay K2. Relay K2's pin 1 is connected to a 12V power supply, pins 5 and 6 are both connected to AC contactor JQ1's pins 1, 4, and 3 are all connected to the 220V-L2 live wire; The 3rd, 4th, and 5th pins of AC contactor JQ1 are connected to the L1-IN phase power, L2-IN phase power, and L3-IN phase power, respectively; Pin 7 of AC contactor JQ1 is connected to the positive terminal of LED D17 through resistor R135, and the negative terminal of LED D17 is connected to pin 8 of AC contactor JQ1. Pin 2 of AC contactor JQ1 is connected to the neutral wire N2; Pins 1, 2, and 3 of capacitor 120 are connected to pins 8, 7, and 6 of AC contactor JQ1, respectively, and pin 4 of capacitor 120 is connected to ground. The circuit principle of the second AC contactor is the same as that of the first AC contactor.

6. The leakage current protection device for a three-phase intelligent power distribution unit as described in claim 5, characterized in that: The field-effect transistor Q4 is model AO3400A, the relay K2 is model HF115F1DS3A, the AC contactor JQ1 is model JLJCQ-01, and the capacitor C120 is model CZMK-01.

7. A leakage current protection device for a three-phase intelligent power distribution unit as described in claim 5, characterized in that: The relay RL1 has its 4th pin connected to the L2-IN-F phase power of the AC contactor JQ1's input terminal, and its 3rd pin connected to the L1-IN phase power of the AC contactor JQ1's input terminal through resistor R120. The AC current transformer ZCT1 is used to measure the current signals of phases L1-IN, L2-IN, L3-IN, and N2 entering the AC contactor JQ1.

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