An intelligent DC circuit breaker electronic trip unit

Abstract

The present invention discloses an intelligent DC circuit breaker electronic trip unit, comprising a self-powered multi-switch input acquisition circuit, a dual-channel redundant current acquisition circuit, a dual-channel voltage acquisition circuit, a memory circuit, a CAN communication circuit, a control circuit, and an output circuit. The control circuit reads information from the self-powered multi-switch input acquisition circuit, the dual-channel redundant current acquisition circuit, the dual-channel voltage acquisition circuit, and the memory circuit, and outputs the information to the CAN communication circuit and the output circuit. The present invention can identify remote and local opening and closing operations of the circuit breaker, can acquire redundant current to implement protection functions, can identify and evaluate the state of the circuit breaker contacts, can calculate the number of electrical lifespans of the circuit breaker, and can determine the state of the circuit breaker operating mechanism. The present invention realizes intelligent monitoring of the circuit breaker state and intelligent control of the circuit breaker, and provides data support for auxiliary intelligent decision-making of the circuit breaker.

Description

Technical Field

[0001] The invention belongs to the technical field of low-voltage DC electrical appliance control, and relates to an intelligent DC circuit breaker electronic release, which is particularly suitable for intelligent low-voltage DC circuit breakers. Background Art

[0002] A low-voltage DC circuit breaker is a protective component used to interrupt fault currents in a circuit. The electronic trip unit is the control core of the DC circuit breaker, controlling the circuit breaker to implement various measurement, monitoring, and protection functions.

[0003] In power systems, circuit breakers require opening and closing operations. Furthermore, circuit breaker contacts are consumable parts and can erode after repeated use, affecting the breaker's current-carrying and breaking capabilities. Traditionally, visual inspection is the only way to determine the contact status of a circuit breaker. For applications requiring high safety, redundant protection is required. The electrical life of a circuit breaker is a critical parameter, but previous technology could only monitor its life using a mechanical counter.

[0004] Therefore, it is necessary to design an intelligent DC circuit breaker electronic trip unit to achieve redundant protection, record the circuit breaker operating status, intelligently monitor the circuit breaker contact status, statistically calculate the circuit breaker electrical life, detect the circuit breaker operating mechanism status, and upload data to realize auxiliary intelligent decision-making of the circuit breaker. Summary of the Invention

[0005] The purpose of the present invention is to provide an intelligent electronic trip unit for DC circuit breaker. In addition to realizing redundant protection functions, it can also collect opening and closing operation records during the circuit breaker operation, analyze and calculate the circuit breaker contact status, calculate the circuit breaker electrical life statistics, and upload the circuit breaker status information through a high-reliability communication network composed of CAN communication, thereby realizing intelligent monitoring and control of the circuit breaker status.

[0006] The technical solution adopted by the present invention to solve its technical problems is: an intelligent DC circuit breaker electronic trip unit, including a control circuit and a self-powered multi-switch input acquisition circuit, a dual-channel redundant current acquisition circuit, a dual-channel voltage acquisition circuit, a memory circuit, a CAN communication circuit and an output circuit respectively connected to the control circuit; the output circuit is connected to the shunt release coil and the pulse release coil of the circuit breaker; the self-powered multi-switch input acquisition circuit acquires dry node status signals including opening and closing operations before the external distribution board, local opening and closing operations of the circuit breaker, circuit breaker status, protection input, etc., and outputs the isolated signals to the control circuit through a photoelectric coupler; The dual-channel redundant current acquisition circuit acquires dual redundant currents consisting of the circuit breaker input pole current and output pole current, and outputs the signals to the control circuit after signal conditioning; the dual-channel voltage acquisition circuit acquires the circuit breaker input pole voltage and output pole voltage, and outputs the signals to the control circuit after signal conditioning; the CAN communication circuit is connected to the control circuit through an isolated CAN transceiver module, and at the same time transmits the data of the electronic release to the host computer terminal; the control circuit reads the circuit breaker status, circuit breaker contact status, circuit breaker electrical life times, distribution board operation status, electronic release events and other information stored in the memory circuit, outputs the signal to the output circuit, and outputs the information through the CAN communication circuit.

[0007] The intelligent DC circuit breaker electronic trip unit has a self-powered multi-switch input acquisition circuit comprising a first switch input acquisition circuit, a second switch input acquisition circuit, a third switch input acquisition circuit, a fourth switch input acquisition circuit, a fifth switch input acquisition circuit, a sixth switch input acquisition circuit, and a seventh switch input acquisition circuit; the input ends of the first to seventh switch input acquisition circuits are respectively connected to one end of the switch dry node and the negative electrode of the power supply, and the other end of the switch dry node is connected to the positive electrode of the power supply, thereby forming a loop with the first to seventh switch input acquisition circuits; the first to second switch input acquisition circuits are respectively connected to the circuit breaker remote control circuit serving as the dry node. The circuit breaker remote opening button and the circuit breaker remote closing button are connected in series to the power supply VDIO and the input terminals INPUT1+ and INPUT2+ respectively. The third switch input acquisition circuit is connected to the local circuit breaker opening button, the fourth switch input acquisition circuit is connected to the local circuit breaker closing button, the fifth switch input acquisition circuit is connected to the circuit breaker auxiliary switch, the sixth switch input acquisition circuit is connected to the circuit breaker protection enable button, the seventh switch input acquisition circuit is connected to the circuit breaker reset operation button, the first to seventh switch input acquisition circuits are connected to the control circuit, and the electronic trip device collects the time from the circuit breaker operation button to the circuit breaker status signal to determine the status of the circuit breaker operating mechanism.

[0008] The intelligent DC circuit breaker electronic trip unit has a dual-channel redundant current acquisition circuit comprising a main current acquisition circuit connected to the circuit breaker input terminal and a redundant current acquisition circuit connected to the circuit breaker output terminal. The main current acquisition circuit and the redundant current acquisition circuit acquire current signals, which are conditioned and input into the control circuit. The control circuit converts the conditioned two analog signals into digital signals, calculates the actual current value, and performs protection logic operations. When either current signal reaches the protection threshold, the electronic trip unit protection is triggered, thereby realizing the redundant protection function of the input current channel.

[0009] The intelligent DC circuit breaker electronic trip unit has a dual-channel voltage acquisition circuit comprising an input pole voltage acquisition circuit connected to the circuit breaker input pole and an output pole voltage acquisition circuit connected to the circuit breaker output pole. The input pole voltage signal and the output pole voltage signal conditioned by the dual-channel voltage acquisition circuit are output to the control circuit. The control circuit converts the conditioned two analog signals into digital signals, calculates the actual voltage value, and uses it as input data for voltage protection, thereby realizing overvoltage protection and undervoltage protection functions.

[0010] In the intelligent DC circuit breaker electronic trip unit, the control circuit calculates the voltage difference between the input pole voltage and the output pole voltage, and divides the collected current value by it to obtain the circuit breaker contact resistance value. If the circuit breaker contact resistance value exceeds a threshold, it is determined that the circuit breaker contacts are worn and require repair. The above information is stored in the memory circuit and uploaded to the power system via the CAN communication circuit.

[0011] The output circuit of an intelligent DC circuit breaker electronic trip unit comprises an electromagnetic relay output circuit based on a mechanical electromagnetic relay K2 and a MOSFET switch output circuit based on first and second MOSFET switching devices. The electromagnetic relay output circuit and the MOSFET switch output circuit are connected in parallel and are mutually redundant, which can greatly improve the reliability of the electronic trip unit output. The first and second MOSFETs are connected in parallel and are mutually redundant to improve the reliability of the output circuit. The electromagnetic relay output circuit uses a first and second set of output contacts connected in parallel as output devices and connected to a load. The two sets of contacts are mutually redundant to improve the reliability of the output interface. The gate of the first MOSFET is connected in parallel with the gate of the second MOSFET and is connected to the control circuit. The source of the first MOSFET is connected in parallel with the source of the second MOSFET and is connected to one end of the load. The drain of the first MOSFET is connected in parallel with the drain of the second MOSFET and is connected to the negative electrode of the power supply. The MOSFETs have automatic current sharing capability. The first and second MOSFETs have the same load current. When one MOSFET output circuit fails, the other MOSFET output circuit can still operate normally.

[0012] Compared with the existing known technologies, the technical solution provided by the present invention has the following significant effects:

[0013] The present invention designs a self-powered multi-channel switch input acquisition circuit, and records the circuit breaker process operation data, judges the circuit breaker state, and configures the working state of the electronic trip unit through calculation; designs a dual-channel redundant current acquisition circuit, and realizes the circuit breaker redundant current protection function through calculation, thereby improving the protection reliability; designs a dual-channel voltage acquisition circuit, and realizes the circuit breaker redundant voltage protection function through calculation, thereby improving the protection reliability; realizes the circuit breaker contact state monitoring function by calculating the circuit breaker contact impedance, thereby greatly improving the maintainability of the circuit breaker; and designs a memory circuit to store the circuit breaker operation process data, working state, etc. The invention can store the circuit breaker's operating process data, circuit breaker's electrical life times, working status data and configuration information, realize intelligent status monitoring of the circuit breaker, and improve the maintainability of the circuit breaker; by designing a memory circuit, it can store the circuit breaker's operating process data, circuit breaker's electrical life times, working status data and configuration information, realize intelligent status monitoring of the circuit breaker, and realize auxiliary intelligent decision-making of the circuit breaker, thereby improving the maintainability of the circuit breaker; by designing a CAN communication circuit and filtering, the robustness and reliability of CAN communication are improved; by designing an electromagnetic relay redundant output circuit and a MOSFET parallel redundant output circuit, the present invention greatly improves the reliability of the electronic trip protection output. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a functional block diagram of an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of a self-powered multi-switch input circuit;

[0016] Figure 3 It is a schematic diagram of a dual-channel redundant current acquisition circuit and a dual-channel voltage acquisition circuit;

[0017] Figure 4 Schematic diagram for CAN filter setup;

[0018] Figure 5 Schematic diagram of circuit breaker contact status detection algorithm;

[0019] Figure 6 Schematic diagram of redundant current protection algorithm;

[0020] Figure 7 This is a schematic diagram of the electric operation counting algorithm;

[0021] Figure 8 This is a schematic diagram of the redundant output current of the electromagnetic relay;

[0022] Figure 9This is a schematic diagram of the MOSFET redundant output circuit.

[0023] The figures are marked as follows: 1—self-powered multi-switch input acquisition circuit, 2—dual-channel redundant current acquisition circuit, 21—main current, 22—redundant current, 3—dual-channel voltage acquisition circuit, 31—input pole voltage, 32—output pole voltage, 4—memory circuit, 5—CAN communication circuit, 6—control circuit, 7—output circuit, S1—circuit breaker remote opening button, S2—circuit breaker remote closing button. DETAILED DESCRIPTION

[0024] To further illustrate the purpose and technical solutions of the present invention, the present invention will be described in further detail below with reference to the specific embodiments of the drawings.

[0025] Reference Figure 1 As shown, the present invention discloses an intelligent DC circuit breaker electronic release, comprising a self-powered multi-switch input acquisition circuit 1, a dual-channel redundant current acquisition circuit 2, a dual-channel voltage acquisition circuit 3, a memory circuit 4, a CAN communication circuit 5, a control circuit 6, and an output circuit 7. The control circuit 6 runs the high-reliability DC circuit breaker electronic release software to implement various intelligent functions. The output circuit 7 connects the circuit breaker's shunt release coil and pulse release coil. The self-powered multi-switch input acquisition circuit 1 acquires dry node status signals, including opening and closing operations before the external distribution board, local opening and closing operations of the circuit breaker, circuit breaker status, and protection activation, and outputs the isolated signals to the control circuit 6 via a photoelectric coupler. The electronic release acquires the time difference between the circuit breaker operation button and the circuit breaker status signal, and compares it with the inherent action time of the circuit breaker operating mechanism to determine the status of the circuit breaker operating mechanism.

[0026] The electronic trip unit of the present invention is designed with a dual redundant current acquisition circuit 2: the signals of the main current 21 and the redundant current 22 are connected to the dual redundant current acquisition circuit 2, which conditions the signals and connects them to the control circuit 6. The control circuit 6 implements the redundant protection function of the electronic trip unit based on the current value of the main current 21 or the redundant current 22, thereby improving the reliability of the electronic trip unit protection. Figure 2 The electronic trip unit of the present invention is designed with a dual-path voltage acquisition circuit 3: the input pole voltage 31 and the output pole voltage 32 of the circuit breaker CB1 are connected to the dual-path voltage acquisition circuit 3, and are also connected to a control circuit 6. The control circuit 6 calculates the voltage value of the input pole voltage 31 and the output pole voltage 32 and the voltage difference between them. The control circuit 6 determines the operating state of the circuit breaker contacts based on the input pole voltage 31 and the output pole voltage 32, thus realizing intelligent status monitoring of the circuit breaker.

[0027] The memory circuit 4 includes a non-volatile memory device for storing the configuration file of the electronic trip unit. The memory device is connected to the control circuit 6. The control circuit 6 reads and writes data information such as the circuit breaker status, distribution board operation status, and electronic trip unit events stored in the memory circuit 4. When an event occurs in the electronic trip unit, the memory circuit 4 writes the event information to the memory device and reads the configuration information during the power-on process of the electronic trip unit to implement the corresponding function.

[0028] Reference Figure 2 As shown, the self-powered multi-switch input acquisition circuit 1 includes a first switch input acquisition circuit, a second switch input acquisition circuit, a third switch input acquisition circuit, a fourth switch input acquisition circuit, a fifth switch input acquisition circuit, a sixth switch input acquisition circuit and a seventh switch input acquisition circuit; the input ends of the first to seventh switch input acquisition circuits are respectively connected to one end of the switch dry node and the negative pole of the power supply; the switch dry node is connected to the positive pole of the power supply and the other end of the switch dry node, thereby forming a loop with the first to seventh switch input acquisition circuits; the first switch input acquisition circuit is connected to the circuit breaker remote trip button S1, and the second switch input acquisition circuit is connected to The circuit breaker's remote closing button S2 is connected to the circuit breaker's remote opening button S1 and remote closing button S2, which are dry terminals. Their two terminals are connected in series to the power supply VDIO and input terminals INPUT1+ and INPUT2+ of the self-powered multi-digital input acquisition circuit 1, respectively. The third digital input acquisition circuit is connected to the circuit breaker's local opening button, the fourth digital input acquisition circuit is connected to the circuit breaker's local closing button, the fifth digital input acquisition circuit is connected to the circuit breaker's auxiliary switch, the sixth digital input acquisition circuit is connected to the circuit breaker's protection enable button, and the seventh digital input acquisition circuit is connected to the circuit breaker's reset operation button. The first through seventh digital input acquisition circuits are connected to the electronic trip unit control circuit 6. The digital inputs are dry terminals and are input in pairs, which simplifies circuit breaker wiring, prevents input circuit burnout due to reverse connection, and improves the reliability and maintainability of the self-powered multi-digital inputs. The electronic trip unit collects the difference between the opening and closing button operation time of the circuit breaker CB1 and the circuit breaker opening and closing time, and can analyze whether the circuit breaker opening and closing mechanism is working normally, thus realizing the intelligent status monitoring of the circuit breaker. Figure 1 .

[0029] Taking the first switch input acquisition circuit as an example, the first switch input acquisition circuit is used to acquire the operation of the remote trip button S1. One end of the remote trip button S1 is connected to the internal power supply VDIO of the electronic trip unit, and the other end is connected to the photocoupler input resistor R135. The negative input resistor R139 of the photocoupler is connected to the negative power supply GND_DIO. When the remote trip button S1 is closed, the photocoupler D5 is turned on, INPUT1 changes from a high level to a low level, and INPUT1 is input to the control circuit to realize the remote trip button status acquisition. The internal power supply VDIO is implemented using an isolated power supply to ensure the isolation of the external input from the weak current circuit inside the electronic trip unit. The second to eighth switch input circuits are implemented in the same way as the first switch input circuit. The self-powered multi-switch input circuit can acquire circuit breaker status signals, local circuit breaker opening and closing operation signals, circuit breaker remote opening and closing operation signals, etc., to realize intelligent monitoring of the circuit breaker operating status and provide data support for auxiliary intelligent decision-making of the circuit breaker.

[0030] The electronic trip unit collects the time the circuit breaker closing button is pressed and the time the circuit breaker is in the closed state, and calculates the time difference between the two times to obtain the closing actuation time of the circuit breaker operating mechanism. The electronic trip unit also collects the time the circuit breaker opening button is pressed and the time the circuit breaker is in the open state, and calculates the time difference between the two times to obtain the opening actuation time of the circuit breaker operating mechanism. By comparing these times with the circuit breaker's inherent actuation time, the circuit breaker operating mechanism status information can be determined, enabling intelligent detection and judgment of the circuit breaker operating mechanism status, providing data support for preventive maintenance of the circuit breaker.

[0031] The dual redundant current acquisition circuit 2 acquires the dual redundant current composed of the input terminal current and the output terminal current of the circuit breaker input pole, and outputs the signal to the control circuit 6 after signal conditioning. Figure 3 As shown, the dual-channel redundant current acquisition circuit 2 includes a main current acquisition circuit connected to the circuit breaker input terminal and a redundant current acquisition circuit connected to the circuit breaker output terminal. The main and redundant current acquisition circuits collect current signals, condition them, and input them into the control circuit 6. The control circuit 6 converts the conditioned analog signals into digital signals, calculates the actual current value, and performs protection logic operations. If either current signal reaches the protection threshold, the electronic trip device protection is triggered, thus implementing redundant protection for the input current channels. The main current 21 of the circuit breaker input terminal is collected from the input terminal of the circuit breaker CB1, conditioned by the dual-channel redundant current acquisition circuit 2, and then input into the control circuit. The redundant current 22 is collected from the output terminal of the circuit breaker CB1, conditioned by the dual-channel redundant current acquisition circuit 2, and then input into the control circuit.

[0032] The dual-path voltage acquisition circuit 3 acquires the input and output voltages of the circuit breaker, and outputs the signals to the control circuit 6 after signal conditioning. Figure 3 As shown, the dual-channel voltage acquisition circuit 3 includes an input voltage acquisition circuit connected to the circuit breaker input terminal and an output voltage acquisition circuit connected to the circuit breaker output terminal. The input and output voltage signals, conditioned by the dual-channel voltage acquisition circuit 3, are output to the control circuit 6. The control circuit 6 converts the conditioned analog signals into digital signals and calculates the actual voltage values, which serve as input data for voltage protection, implementing overvoltage and undervoltage protection functions. The circuit breaker input voltage 31 is acquired from the input terminal of circuit breaker CB1, conditioned by the dual-channel voltage acquisition channel 3, and then input to the control circuit. The output voltage 32 is acquired from the output terminal of circuit breaker CB1, conditioned by the dual-channel voltage acquisition channel 3, and then input to the control circuit.

[0033] The control circuit 6 calculates the voltage difference between the input and output voltages and divides the collected current value by the difference to obtain the circuit breaker contact resistance. If the circuit breaker contact resistance exceeds a threshold, the circuit breaker contacts are determined to be worn and require repair. This information is stored in the memory circuit 4 and uploaded to the power system via the CAN communication circuit 5. The control circuit 6 collects the status of the self-powered multi-switch input circuit, signals from the dual-redundant current acquisition circuit, and signals from the dual-voltage acquisition circuit. It calculates and processes this information to implement the electronic trip unit's circuit breaker status determination, protection functions, contact status determination, and electrical operation counting functions, and controls the output circuit to trip the circuit breaker.

[0034] The control steps of the control circuit 6 refer to Figure 5 、 Figure 6 、 Figure 7 shown. Figure 5 This is the step for judging the state of the circuit breaker contact. The contact resistance of the circuit breaker is R CB When the circuit breaker is fed with current I, the voltages at the input and output poles of the circuit breaker are U IN and U OUT . When (U IN -U OUT ) / I>R CB , it can be determined that the circuit breaker contact state is abnormal, and the electronic trip unit will issue an abnormal circuit breaker contact state alarm to realize intelligent monitoring of the circuit breaker contact state.

[0035] The control circuit 6 reads information such as the circuit breaker status, distribution board operation status, and electronic trip unit events stored in the memory circuit 4, and outputs the signal to the output circuit 7. The control circuit 6 reads the signal from the CAN communication circuit 5, outputs the signal to the output circuit 7, and controls the output circuit 7 to output. The control circuit 6 is designed with a hardware filtering method to filter out useless data frames, ensuring that the electronic trip unit only receives useful data frames, reducing the computing burden of the microcontroller in the controller, ensuring the reliability of CAN communication, and providing data support for the circuit breaker's auxiliary intelligent decision-making.

[0036] When an event occurs in the electronic trip unit, the control circuit 6 writes the event information to the storage device. The configuration file of the electronic trip unit is also stored in the storage device. During the power-on process of the electronic trip unit, the configuration information is read to implement the corresponding function. The CAN communication circuit 5 mainly includes a CAN interface device. The CAN communication circuit 5 is connected to the control circuit 6 through the CAN interface device and transmits the data of the electronic trip unit to the host computer terminal. The CAN communication steps refer to Figure 4 shown.

[0037] Redundancy protection steps are shown in Figure 6 .exist Figure 6 Both the main current and the redundant current are used as inputs to the electronic trip unit's protection algorithm. After the protection is asserted, control circuit 6 collects the circuit breaker status and the input and output currents via a self-powered multi-switch input circuit. If the circuit breaker position remains unchanged or the input or output currents remain non-zero, the circuit breaker is deemed to have failed, and the electronic trip unit issues a breaker failure alarm, enabling intelligent monitoring of the circuit breaker contact status.

[0038] The steps for counting the electrical life of the circuit breaker are shown in Figure 7 The electronic trip unit collects current I through a dual-channel redundant current acquisition circuit 2. When current I is greater than a certain set threshold value Ir of the circuit breaker and the circuit breaker state CBstate changes from closed to open, the number of times the circuit breaker's electrical life is determined to be increased by 1. If current I is less than a certain set threshold value Ir of the circuit breaker and the circuit breaker state CBstate changes from closed to open, the number of times the circuit breaker's mechanical life is determined to be increased by 1, thereby realizing intelligent monitoring of the circuit breaker's electrical life.

[0039] Reference Figure 8 、 Figure 9As shown, the output circuit 7 includes an electromagnetic relay output circuit and a MOSFET switch output circuit. The electromagnetic relay output circuit uses a dual-contact relay as the output device. The electromagnetic relay includes a first set of output contacts and a second set of output contacts. The first set of output contacts is connected in parallel with the second set of output contacts and connected to the load, improving the reliability of the output interface. The MOSFET switch output circuit mainly includes a first MOSFET and a second MOSFET as switching devices. The gate of the first MOSFET is connected in parallel with the gate of the second MOSFET and connected to the control circuit 6. The source of the first MOSFET is connected in parallel with the source of the second MOSFET and connected to one end of the load. The drain of the first MOSFET is connected in parallel with the drain of the second MOSFET and connected to the negative terminal of the power supply. The MOSFETs have automatic current sharing capability, and the load current of the first and second MOSFETs is the same. If one MOSFET output circuit fails, the other MOSFET output circuit can still operate normally. The parallel connection of the first and second sets of output contacts, the first and second MOSFETs, and the electromagnetic relay output circuit and the MOSFET switch output circuit greatly improves the reliability of the electronic trip unit output. The output circuit consists of the mechanical electromagnetic relay K2 and the MOSFET switch output circuit. The electromagnetic relay's two sets of contacts are redundant, and the MOSFET switch output circuit, consisting of two MOSFETs connected in parallel, is redundant. This redundant nature of the electromagnetic relay and MOSFET switch output circuits improves the reliability of the output circuit. The output circuit 7, comprising a dual-set parallel electromagnetic relay and dual MOSFET output circuits, improves the reliability of the electronic trip unit's output.

[0040] When the control circuit 6 runs the protection algorithm and outputs the protection signal, it outputs the OPEN signal and the PULSE signal at the same time. Figure 8 As shown. The electromagnetic relay K2 has two sets of normally open contacts. When the relay is driven by the OPEN signal, the first set of contacts 3, 5 and the second set of contacts 6, 7 are simultaneously turned on. The first set of contacts and the second set of contacts are redundant with each other, which improves the reliability of the output. Figure 9 As shown in the figure, Q1 and Q2 are output MOSFETs, V1 is an anti-parallel diode, and LOAD is the load, i.e., the circuit breaker pulse trip coil. PAULSE is the MOSFET drive signal. When the control circuit outputs the PAULSE signal, MOSFETs Q1 and Q2 conduct simultaneously, activating the protection output. Due to the automatic current sharing characteristics of the MOSFETs, the load current is evenly distributed through Q1 and Q2, effectively extending the service life of Q1 and Q2. Q1 and Q2 provide mutual redundancy. Furthermore, relay K2 provides mutual redundancy with Q1 and Q2.

[0041] The electronic trip unit of the circuit breaker of the present invention can intelligently collect information such as the contact status, electrical life and operating status of the circuit breaker, realize intelligent control of the circuit breaker, and provide data support for auxiliary intelligent decision-making of the circuit breaker.

[0042] By collecting input and output voltages, the device determines the voltage drop across the circuit breaker contacts, and thus the contact status. It also identifies and stores circuit breaker operation records and the number of electrical life operations, storing this information and transmitting it to a host computer via CAN communication. Furthermore, redundant current acquisition channels, redundant relay contacts, and MOSFET parallel outputs enhance the protection reliability of the electronic trip unit, making it suitable for DC circuit breakers and power systems requiring high reliability.

[0043] The specific embodiments described herein are merely illustrative of the principles and specific implementations of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the principles, topologies, or exceeding the scope of the present invention as defined by the appended claims.

Claims

1. An intelligent DC circuit breaker electronic trip unit, characterized by: The invention comprises a control circuit (6) and a self-powered multi-switch input acquisition circuit (1), a dual-channel redundant current acquisition circuit (2), a dual-channel voltage acquisition circuit (3), a memory circuit (4), a CAN communication circuit (5) and an output circuit (7) respectively connected to the control circuit (6); the output circuit (7) is connected to the shunt release coil and the pulse release coil of the circuit breaker; the self-powered multi-switch input acquisition circuit (1) acquires dry node status signals including the opening and closing operations before the external distribution board, the local opening and closing operations of the circuit breaker, the circuit breaker status, and the protection input, and outputs them to the control circuit (6); the The dual-channel redundant current acquisition circuit (2) acquires the dual redundant current composed of the circuit breaker input pole current and the output pole current, and outputs the signal to the control circuit (6) after signal conditioning; the dual-channel voltage acquisition circuit (3) acquires the circuit breaker input pole voltage and the output pole voltage, and outputs the signal to the control circuit (6) after signal conditioning; the CAN communication circuit (5) is connected to the control circuit (6) through the isolation CAN transceiver module, and transmits the data to the host computer terminal; the control circuit (6) reads the circuit breaker information stored in the memory circuit (4) and the signal of the CAN communication circuit (5), outputs the signal to the output circuit (7), and transmits the signal to the host computer terminal; The circuit breaker status information is output through the CAN communication circuit (5). The control circuit (6) calculates the voltage difference between the input pole voltage and the output pole voltage, and divides the collected current value to obtain the circuit breaker contact resistance value. If the circuit breaker contact resistance value exceeds the threshold, it is determined that the circuit breaker contact is worn and needs to be repaired. The information is stored in the memory circuit (4) and uploaded to the power system through the CAN communication circuit (5). The output circuit (7) is composed of an electromagnetic relay output circuit based on the mechanical electromagnetic relay K2 and a MOSFET switch output circuit based on the first MOSFET and the second MOSFET. The electromagnetic relay output circuit is connected in parallel with the MOSFET switch output circuit, the first MOSFET is connected in parallel with the second MOSFET, and the electromagnetic relay output circuit uses the parallel first group of output contacts and the second group of output contacts as output devices and is connected to the load; the gate of the first MOSFET is connected in parallel with the gate of the second MOSFET and then connected to the control circuit (6), the source of the first MOSFET is connected in parallel with the source of the second MOSFET and then connected to one end of the load, the drain of the first MOSFET is connected in parallel with the drain of the second MOSFET and then connected to the negative pole of the power supply, and the load current of the first MOSFET and the second MOSFET is the same.

2. The intelligent DC circuit breaker electronic trip unit according to claim 1, characterized in that: The self-powered multi-switch input acquisition circuit (1) comprises a first switch input acquisition circuit, a second switch input acquisition circuit, a third switch input acquisition circuit, a fourth switch input acquisition circuit, a fifth switch input acquisition circuit, a sixth switch input acquisition circuit and a seventh switch input acquisition circuit; The input ends of the first to seventh switch value input acquisition circuits are respectively connected to one end of the switch value dry node and the negative pole of the power supply, and the other end of the switch value dry node is connected to the positive pole of the power supply to form a loop; the first to seventh switch value input acquisition circuits are respectively connected to the circuit breaker remote opening button (S1) and the circuit breaker remote closing button (S2) as dry nodes, and the two ends of the circuit breaker remote opening button (S1) and the circuit breaker remote closing button (S2) are respectively connected in series to the power supply VDIO and the input ends INPUT1+ and INPUT2+; the third switch value input acquisition circuit is connected to the circuit breaker local opening button, the fourth switch value input acquisition circuit is connected to the circuit breaker local closing button, the fifth switch value input acquisition circuit is connected to the circuit breaker auxiliary switch, the sixth switch value input acquisition circuit is connected to the circuit breaker protection enable button, the seventh switch value input acquisition circuit is connected to the circuit breaker reset operation button, and the first to seventh switch value input acquisition circuits are connected to the control circuit (6).

3. An intelligent DC circuit breaker electronic trip unit according to claim 1 or 2, characterized in that: The dual-path redundant current acquisition circuit (2) comprises a main current acquisition circuit connected to the input pole of the circuit breaker and a redundant current acquisition circuit connected to the output pole of the circuit breaker; The main current acquisition circuit and the redundant current acquisition circuit acquire current signals, which are input to the control circuit (6) after conditioning. The control circuit (6) converts the two analog signals into digital signals, calculates the actual current value, and performs protection logic operations. When any current signal reaches the protection threshold, the electronic trip protection is triggered, thereby realizing redundant protection of the input current channel.

4. The intelligent DC circuit breaker electronic trip unit according to claim 3, characterized in that: The dual-path voltage acquisition circuit (3) comprises an input pole voltage acquisition circuit connected to the input pole of the circuit breaker and an output pole voltage acquisition circuit connected to the output pole of the circuit breaker; the input pole voltage signal and the output pole voltage signal conditioned by the dual-path voltage acquisition circuit (3) are output to the control circuit (6); the control circuit (6) converts the two-path analog signals into digital signals, calculates the actual voltage value, and uses it as input data for voltage protection, thereby realizing overvoltage protection and undervoltage protection.

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