An electrically controlled excavator dual-motor step-down starting system and a failure protection method thereof

Abstract

The application discloses an electrically controlled excavator double-motor step-down starting system and a failure protection method thereof. The system comprises an incoming line cabinet and a starting cabinet, and a signal measurement, motor power supply, state monitoring and logic control unit is integrated in the starting cabinet. The system adopts time-sharing control logic to sequentially start two motors through a shared starting transformer, so as to reduce the starting current impact. The state monitoring unit integrates a self-checking function and a vacuum contactor state feedback circuit, and can diagnose the loop health state in real time. The logic control unit executes motor start-stop control based on the above signals, and when overvoltage, overcurrent, short circuit, contact sticking and other faults occur, triggers a multi-level failure protection mechanism including breaking the contactor, tripping the incoming line circuit breaker or switching to the standby starting logic, thereby significantly improving the reliability and safety of the system.

Description

Technical Field

[0001] This invention relates to the field of high-voltage motor control for construction machinery, and in particular to a dual-motor reduced-voltage starting system for an electrically controlled excavator and its failure protection method. Background Technology

[0002] Electrification of construction machinery is a significant current development trend, with high-power electronically controlled excavators and other equipment gaining widespread application due to their energy-saving and environmentally friendly advantages. These machines typically employ high-voltage motors, making the reliability, economy, and safety of their starting and control systems crucial.

[0003] Currently, the common reactor step-down starting schemes used in this type of equipment have significant shortcomings: Cost and space issues: Traditional solutions require each motor to be equipped with an independent reactor, resulting in high equipment costs, large size, and excessive installation space. Safety and reliability issues: The existing system lacks real-time status monitoring of critical components such as fuses and contactors. In the event of faults such as overcurrent or short circuits, the system cannot make timely and accurate judgments and provide protection, posing a high risk of failure.

[0004] Therefore, there is an urgent need for a new solution to overcome the limitations of traditional starting systems in terms of cost, space and reliability, and to meet the higher requirements of modern electric construction machinery for motor control systems. Summary of the Invention

[0005] To address the above problems, this invention provides a dual-motor reduced-voltage starting system for electrically controlled excavators and its failure protection method. The system aims to significantly reduce system cost and space occupation by sharing a single starting transformer, and comprehensively improve system reliability, safety, and continuous operation capability under fault conditions by leveraging intelligent status monitoring with self-testing function and multi-layer protection mechanism.

[0006] In a first aspect, the present invention provides a dual-motor reduced-voltage starting system for an electrically controlled excavator, comprising: The incoming line cabinet is installed at the bottom of the electric control excavator. Its core component is a vacuum circuit breaker, which is used to realize the power supply opening and closing control, maintenance isolation and emergency protection of the whole vehicle. A starter cabinet, installed on an electrically controlled excavator, is used to achieve reduced-voltage starting and operation control of dual motors. The starter cabinet integrates: The signal measurement unit is used to monitor the system bus voltage, current, and equipment temperature in real time. The motor power supply unit includes a contactor group, a fuse group, and a shared starting transformer for starting and running two motors. The status monitoring unit is used to collect the operating status of fuses and contactors in real time; The logic control unit is used to collect signals from the signal measurement unit, status monitoring unit and motor power supply unit, and execute motor start-up, operation control and failure protection according to preset logic.

[0007] Furthermore, the signal measurement unit includes: The voltage measurement unit measures the bus voltage through a group of voltage transformers. The current measurement unit measures the current in each phase of the motor through a group of current transformers; The temperature measurement unit measures the temperature of the starting transformer and motor through a group of temperature sensors.

[0008] By clearly defining the signal measurement unit as including three measurement units—voltage, current, and temperature—a comprehensive, multi-parameter real-time monitoring system is constructed. This provides a precise data foundation for the execution of the logic control unit, enabling the system to accurately identify and quickly respond to various fault types such as overvoltage, undervoltage, overcurrent, and overtemperature, thereby achieving refined protection for critical equipment such as motors and starting transformers.

[0009] Furthermore, the status monitoring unit includes a fuse status feedback and self-test circuit, which includes a self-test relay, a micro switch, and a controller. The micro switch is installed at the end of the fuse, and the state of the micro switch is changed by the action of the impactor when the fuse fails. The coil of the self-test relay is connected to the output control channel of the controller, its common terminal contact is connected to the normally closed contact of the micro switch, the normally closed contact of the self-test relay is connected to the positive terminal of the power supply, and the normally open contact of the self-test relay is connected to the self-test output channel of the controller. The other end of the normally closed contact of the micro switch is connected to the digital input channel of the controller.

[0010] By introducing a specific connection method for self-testing relays and microswitches, it is possible not only to monitor whether the fuse has blown, but also to diagnose the monitoring circuit itself before the system is running. This effectively avoids false alarms or missed alarms caused by the monitoring circuit itself being disconnected or malfunctioning, and greatly improves the reliability and trustworthiness of the status monitoring function.

[0011] Furthermore, the self-test process of the fuse status feedback and self-test circuit is as follows: Before the system starts running, the controller outputs a digital control signal to drive the coil of the self-test relay to be energized, so that the high-level self-test signal output by the controller is fed back to the controller through the normally open contact of the self-test relay, the micro switch and the controller's digital input channel; the controller monitors the feedback signal in real time, and if it is high, it determines that the circuit is normal, and if it is low, it determines that there is a fault in the circuit.

[0012] By defining a specific pre-operation self-test process, the system is forced to verify the integrity of the fuse monitoring circuit before each startup. This ensures that the fuse status signals obtained by the system during subsequent operation are based on a proven and intact channel, thereby eliminating the risk of system misjudgment or protection failure caused by monitoring circuit failure at the source, and enhancing the system's pre-maintenance capability and initial state security.

[0013] Furthermore, the self-test process of the fuse status feedback and self-test circuit also includes: During system operation, the controller de-energizes the self-test relay coil, and the high-level signal of the system power supply is fed back to the controller through the normally closed contact of the self-test relay, the micro switch, and the controller's digital input channel. The controller monitors this feedback signal in real time. If it is high, the fuse is determined to be normal; if it is low, the fuse is determined to be faulty.

[0014] The runtime monitoring process is defined and combined with the pre-run self-test process, fully covering both self-test and monitoring modes. During operation, the circuit can accurately reflect the real state of the fuse in real time. Once the fuse blows, the controller can immediately detect it and trigger the protection action. This dynamic and real-time monitoring capability is the key to achieving rapid power-off protection and preventing the escalation of faults.

[0015] Furthermore, the status monitoring unit includes a vacuum contactor status feedback and self-test circuit, which includes a vacuum contactor, a self-test relay, and a controller. The coil of the self-test relay is connected to the output control channel of the controller; For the vacuum contactor closing status feedback circuit, the first common terminal contact of the self-test relay is connected to one end of the two sets of normally open contacts of the vacuum contactor connected in parallel, the other end of the normally open contacts of the vacuum contactor is connected to the controller, the first normally closed contact of the self-test relay is connected to the positive terminal of the power supply, and the first normally open contact of the self-test relay is connected to the self-test output channel of the controller. For the vacuum contactor tripping status feedback circuit, the second common terminal contact of the self-test relay is connected to one end of the two sets of normally closed contacts of the vacuum contactor connected in series, the other end of the normally closed contacts of the vacuum contactor is connected to the controller, the second normally closed contact of the self-test relay is connected to the positive terminal of the power supply, and the second normally open contact of the self-test relay is connected to the self-test output channel of the controller.

[0016] For vacuum contactors, a highly reliable status feedback mechanism is constructed by setting up auxiliary contacts in parallel (for closing feedback) and series (for opening feedback), combined with a self-testing relay. The parallel design provides redundant backup for the closing signal, preventing misjudgment due to a single point of failure; the series design provides safety interlocking for the opening signal, ensuring that normal feedback is only provided when all contacts confirm opening, greatly reducing the risk of serious accidents caused by misjudgment of the contactor status.

[0017] Furthermore, the self-test process of the vacuum contactor status feedback and self-test circuit is as follows: The controller outputs a digital control signal to energize the coil of the self-test relay; For the vacuum contactor closing status feedback loop, the self-test high-level signal output by the controller is fed back to the controller via the first normally open contact of the self-test relay, the first common terminal contact, and the parallel normally open auxiliary contact of the vacuum contactor; if the controller detects that the feedback signal is high-level, it determines that the closing status feedback loop is normal. For the vacuum contactor tripping status feedback loop, the high-level self-test signal output by the controller is fed back to the controller via the second normally open contact, the second common terminal contact of the self-test relay, and the normally closed auxiliary contact of the vacuum contactor connected in series. If the controller detects that the feedback signal is low, it determines that the tripping status feedback loop is normal.

[0018] By proactively injecting test signals into the closing and opening circuits and verifying feedback before operation, potential faults such as auxiliary contact adhesion and circuit disconnection can be detected in advance. This proactive defense mechanism ensures that the monitoring of the contactor status is reliable at startup, preventing the system from operating under abnormal circuit conditions and improving the functional safety level of the entire control system.

[0019] Furthermore, the step of executing the motor start-up and operation control according to preset logic specifically includes: Close the first starting contactor, and after a preset delay, close the second starting contactor and the first motor contactor to start the first motor by reducing the voltage through the starting transformer; After the first motor starts, when the motor speed reaches near the preset speed value, the first and second starting contactors are disconnected. After a preset dead time, the first running contactor is closed, so that the first motor can switch to rated voltage operation. Close the first starting contactor, and after a preset delay, close the second starting contactor and the second motor contactor to start the second motor by reducing the voltage through the starting transformer; After the second motor starts, when the motor speed reaches near the preset speed value, the first and second starting contactors are disconnected. After a preset dead time, the second running contactor is closed, so that the second motor can switch to rated voltage operation.

[0020] By specifically defining the time-sharing and step-by-step starting process of the two motors, the two motors can smoothly and orderly complete the reduced-voltage starting process sequentially. This control strategy effectively reduces the instantaneous inrush current to the shared starting transformer and the power grid, while avoiding power competition and disturbances that may be caused when the two motors start or switch simultaneously, ensuring a smooth and reliable starting process.

[0021] Secondly, this invention provides a failure protection method for a dual-motor reduced-voltage starting system of an electrically controlled excavator, including the following failure protection modes: When the system is detected to have overvoltage, undervoltage, overcurrent, or overtemperature, the corresponding vacuum contactor will be disconnected. When a short-circuit fault is detected, the control disconnects the vacuum contactor, and the fuse provides circuit breaking protection at the same time. When contact sticking of the vacuum contactor is detected, a tripping command is sent to the vacuum circuit breaker in the incoming line cabinet to cut off the main power supply. If any motor power supply circuit device fails during self-testing, the system skips the faulty circuit or switches to the backup startup logic after user authorization interaction.

[0022] For faults of varying severity (such as over-temperature, over-current, short circuit, contact sticking, and device failure), progressively escalating measures are adopted, from disconnecting the contactor to tripping the main circuit breaker, and then to intelligent reconfiguration startup logic. This enables the system to accurately handle minor faults locally, completely isolate fatal faults, and maintain degraded operation capability through strategy adjustments when some devices are damaged, thereby maximizing system availability and operational efficiency.

[0023] Furthermore, the backup startup logic includes: If the operating circuit of the first motor fails, the first motor will be skipped, and the second motor will be started normally with reduced voltage. If the operating circuit of the second motor fails, the second motor will be skipped, and only the first motor will be started normally with reduced voltage. If the first motor contactor or the second motor contactor fails, the other motor will be started normally with reduced voltage. After obtaining user authorization, the corresponding running contactor of the faulty motor will be closed to start the motor directly with full voltage. If the first or second starting contactor fails, after obtaining user authorization, the first and second running contactors will be directly controlled to close, so that both the first and second motors can be started directly at full voltage.

[0024] The specific scenarios and coping strategies for the backup startup logic have been further refined, clarifying how the system can reconfigure its functions through methods such as "skipping" or "authorized full-pressure startup" when different components (such as the operating circuit, motor contactor, and starting contactor) fail. This endows the system with strong fault tolerance and emergency handling capabilities, ensuring that the excavator can still operate partially or escape from a predicament through emergency mode in the event of a non-fatal failure, greatly improving the equipment's uptime and practicality under complex working conditions.

[0025] Compared with existing technologies, the beneficial effects of this invention are as follows: Through highly integrated and intelligent design, the system of this invention achieves synergistic optimization of cost, reliability, and operating efficiency. The system adopts an architecture where a single starting transformer is shared by two motors, fundamentally overcoming the high cost and space waste problems caused by independently configuring reactors in traditional solutions. In terms of monitoring, the system integrates a status monitoring unit with self-testing capabilities, which can automatically diagnose circuit integrity before operation and collect the status of key components in real time during operation. Combined with redundant and interlocked circuit design, this greatly improves the accuracy and reliability of system status perception. At the control level, the system achieves smooth and orderly motor startup through a time-sharing and step-by-step startup strategy, effectively suppressing inrush current. Simultaneously, its intelligent failure protection mechanism can perform graded protection according to the fault type and support degraded operation or emergency startup when some components fail, significantly improving the system's fault tolerance and continuous operation capability under complex working conditions, comprehensively enhancing the practical value and economy of the entire machine. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 This invention provides an architectural block diagram of a dual-motor reduced-voltage starting system for an electrically controlled excavator. Figure 2 An electrical connection diagram of a dual-motor reduced-voltage starting system for an electrically controlled excavator provided by the present invention; Figure 3 The circuit diagram for fuse status feedback and self-test provided by the present invention; Figure 4 The present invention provides a circuit diagram for the vacuum contactor status feedback and self-test. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention.

[0029] This invention provides a dual-motor reduced-voltage starting system for an electrically controlled excavator, such as... Figure 1 As shown, it specifically includes: The incoming line cabinet is installed at the bottom of the electric control excavator. Its core component is a vacuum circuit breaker, which is used to realize the power supply opening and closing control, maintenance isolation and emergency protection of the whole vehicle.

[0030] Specifically, the equipment is disconnected from the 6000V power supply during maintenance to ensure a clear break between the starter cabinet and the power supply; and the circuit breaker is quickly tripped in case of an emergency failure in the system to ensure system safety.

[0031] A starter cabinet, installed on an electrically controlled excavator, is used to achieve reduced-voltage starting and operation control of dual motors. The starter cabinet integrates: The signal measurement unit is used to monitor the system bus voltage, current, and equipment temperature in real time, and specifically includes: The voltage measurement unit includes a first voltage transformer TV1 and a second voltage transformer TV2. The two voltage transformers are connected by a VV connection. The primary side is connected to a 6kV bus, and the secondary side outputs a 100V voltage signal for measuring the bus voltage.

[0032] The current measurement unit includes a first current transformer group CT1 and a second current transformer group CT2, which are used to measure the phase current values ​​of the first and second motors in real time.

[0033] The temperature measurement unit includes a first temperature sensor group PT1, a second temperature sensor group PT2, and a third temperature sensor group PT3, which measures the temperature values ​​of the first starting transformer and the first and second motors in real time.

[0034] The motor power supply unit includes a contactor group, a fuse group, and a shared starting transformer for starting and running two motors.

[0035] Specifically, such as Figure 2 As shown, the motor power supply unit includes a first motor protection fuse group FU1, a second motor protection fuse group FU2, a first starting contactor KS1, a second starting contactor KS2, a first motor contactor KM1, a second motor contactor KM2, a first running contactor KR1, a second running contactor KR2, and a first starting transformer OS1, which together form the motor start-stop control circuit.

[0036] The incoming terminals of the first operating contactor KR1, the second operating contactor KR2, and the second starting contactor KS2 are all connected to the incoming insulator via cables. The outgoing terminal of the first operating contactor KR1 is connected to the incoming terminal of the first motor protection fuse group FU1 via a cable. The outgoing terminal of the second starting contactor KS2 is connected to the incoming terminal of the first starting transformer OS1 via a cable. The outgoing terminal of the second operating contactor KR2 is connected to the incoming terminal of the second motor protection fuse group FU2 via a cable. The outgoing terminal of the first motor protection fuse group FU1 is connected to the output insulator of the first motor M1 via a cable. The outgoing terminals of circuit breaker group FU2 are connected to the output insulator of the second motor M2 via a cable. The output terminal of the first starting transformer OS1 is connected to the incoming terminals of the first motor contactor KM1 and the second motor contactor KM2 via a cable. The output terminal of the first motor contactor KM1 is connected to the incoming terminal of the first motor protection fuse group FU1 via a cable. The output terminal of the second motor contactor KM2 is connected to the incoming terminal of the second motor protection fuse group FU2 via a cable. The incoming terminal of the first starting contactor KS1 is connected to the common terminal of the first starting transformer OS1 via a wire. The outgoing terminals of the first starting contactor KS1 are connected to the contacts via a wire.

[0037] The status monitoring unit is used to collect the operating status of fuses and contactors in real time.

[0038] Specifically, such as Figure 3 As shown, the status monitoring unit includes fuse status feedback and self-test circuits and vacuum contactor status feedback and self-test circuits: The fuse status feedback and self-test circuit includes a self-test relay, a micro switch, a controller, and the necessary power supply; The micro switch is installed at the end of the fuse. When the fuse fails, the state of the micro switch is changed by the action of the striker. The coil of the self-test relay is connected to the output control channel of the controller, its common terminal contact is connected to the normally closed contact of the micro switch, the normally closed contact of the self-test relay is connected to the positive terminal of the DC24V power supply, and the normally open contact of the self-test relay is connected to the self-test output channel of the controller. The other end of the normally closed contact of the micro switch is connected to the digital input channel of the controller.

[0039] The self-test procedure for the fuse status feedback and self-test circuit is as follows: Before the system starts running, the controller outputs a digital control signal to drive the coil of the self-test relay to be energized, so that the high-level self-test signal output by the controller is fed back to the controller through the normally open contact of the self-test relay, the micro switch and the controller's digital input channel; the controller monitors the feedback signal in real time, and if it is high, it determines that the circuit is normal, and if it is low, it determines that there is a fault in the circuit.

[0040] During system operation, the controller de-energizes the self-test relay coil, and the high-level signal of the system power supply is fed back to the controller through the normally closed contact of the self-test relay, the micro switch, and the controller's digital input channel. The controller monitors this feedback signal in real time. If it is high, the fuse is determined to be normal; if it is low, the fuse is determined to be faulty.

[0041] like Figure 4 As shown, the vacuum contactor status feedback and self-test circuit includes a vacuum contactor, a self-test relay, and a controller; The coil of the self-test relay is connected to the output control channel of the controller; For the vacuum contactor closing status feedback circuit, the first common terminal contact of the self-test relay is connected to one end of the two sets of normally open contacts of the vacuum contactor connected in parallel, the other end of the normally open contacts of the vacuum contactor is connected to the controller, the first normally closed contact of the self-test relay is connected to the positive terminal of the power supply, and the first normally open contact of the self-test relay is connected to the self-test output channel of the controller. For the vacuum contactor tripping status feedback circuit, the second common terminal contact of the self-test relay is connected to one end of the two sets of normally closed contacts of the vacuum contactor connected in series, and the other end of the normally closed contacts of the vacuum contactor is connected to the controller. The second normally closed contact of the self-test relay is connected to the positive terminal of the DC24V power supply, and the second normally open contact of the self-test relay is connected to the self-test output channel of the controller.

[0042] The self-test procedure for the vacuum contactor status feedback and self-test circuit is as follows: The controller outputs a digital control signal to energize the coil of the self-test relay; For the vacuum contactor closing status feedback loop, the self-test high-level signal output by the controller is fed back to the controller via the first normally open contact of the self-test relay, the first common terminal contact, and the parallel normally open auxiliary contact of the vacuum contactor; if the controller detects that the feedback signal is high-level, it determines that the closing status feedback loop is normal. For the vacuum contactor tripping status feedback loop, the high-level self-test signal output by the controller is fed back to the controller via the second normally open contact, the second common terminal contact of the self-test relay, and the normally closed auxiliary contact of the vacuum contactor connected in series. If the controller detects that the feedback signal is low, it determines that the tripping status feedback loop is normal.

[0043] The logic control unit is used to collect signals from the signal measurement unit, status monitoring unit and motor power supply unit, and execute motor start-up, operation control and failure protection according to preset logic.

[0044] Specifically, when the system is operating normally, the motor startup and operation steps are as follows: Close the first starting contactor KS1, and after a preset time delay, close the second starting contactor KS2 and the first motor contactor KM1. Then, the first motor M1 is started by stepping down the voltage through the first starting transformer OS1. After the first motor starts, when the motor speed rises from 0 to near the preset speed value, the first starting contactor KS1 and the second starting contactor KS2 are disconnected. After a preset dead time, the first running contactor KR1 is closed, so that the first motor switches to rated voltage operation. Close the first starting contactor KS1, and after a preset delay, close the second starting contactor KS2 and the second motor contactor KM2. Then, the second motor M2 is started by stepping down the voltage through the first starting transformer OS1. After the second motor starts, when the motor speed rises from 0 to near the preset speed value, the first starting contactor KS1 and the second starting contactor KS2 are disconnected. After a preset dead time, the second running contactor KR2 is closed, so that the second motor switches to rated voltage operation.

[0045] This system has the following four failure protection modes: First failure protection mode: When overvoltage, undervoltage, overcurrent or overtemperature is detected in the system, the corresponding vacuum contactor is disconnected.

[0046] This mode is triggered when any of the following fault conditions are detected: Overvoltage fault: The system voltage is ≥ a certain threshold (e.g., 1.2 times the rated voltage) and lasts for a certain period of time (e.g., 3 seconds). Undervoltage fault: The system voltage is less than a certain threshold (e.g., 0.8 times the rated voltage) and lasts for a certain period of time (e.g., 3 seconds). Overcurrent fault: The current in either phase of the first or second motor is greater than or equal to a certain threshold (e.g., 1.5 times the rated current) and lasts for a certain period of time (e.g., 10 seconds). Motor stator winding over-temperature fault: The temperature of either the first or second motor stator winding is ≥ a certain threshold (e.g., 150℃) and lasts for a certain period of time (e.g., 2 seconds). Motor bearing overheating fault: The temperature of either bearing in the first or second motor is ≥ a certain threshold (e.g., 90℃) and lasts for a certain period of time (e.g., 2 seconds). Starting transformer overheating fault: The temperature of the first starting transformer is ≥ a certain threshold (e.g., 130℃) and lasts for a certain period of time (e.g., 2 seconds).

[0047] Second failure protection mode: When a short circuit fault is detected, the vacuum contactor is controlled to disconnect, and the fuse provides circuit breaking protection.

[0048] Third failure protection mode: When contact sticking of the vacuum contactor is detected, a trip command is sent to the vacuum circuit breaker in the incoming line cabinet to cut off the main power supply.

[0049] Fourth Failure Protection Mode: When any motor power supply circuit device fails during self-test, the system skips the faulty circuit, or switches to the backup startup logic after user authorization interaction.

[0050] The backup startup logic is as follows: If the first running contactor KR1 or the first motor protection fuse group FU1 fails, the system will skip the first motor and start the second motor with reduced voltage. If the second operating contactor KR2 or the second motor protection fuse group FU2 fails, the first motor will be started with reduced voltage. If the first motor contactor KM1 fails, the second motor will be started with reduced voltage. With user authorization, the system will drive the first running contactor KR1 to close, and the first motor will be started with full voltage. If the second motor contactor KM2 fails, the first motor will start with reduced voltage. With user authorization, the system will drive the second running contactor KR2 to close, and the second motor will start with full voltage. If the first starting contactor KS1 or the second starting contactor KS2 fails, the first and second motors shall be started at full voltage with user authorization (for emergency conditions).

[0051] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A dual-motor reduced-voltage starting system for an electrically controlled excavator, characterized in that, include: The incoming line cabinet is installed at the bottom of the electric control excavator. Its core component is a vacuum circuit breaker, which is used to realize the power supply opening and closing control, maintenance isolation and emergency protection of the whole vehicle. A starter cabinet, installed on an electrically controlled excavator, is used to achieve reduced-voltage starting and operation control of dual motors. The starter cabinet integrates: The signal measurement unit is used to monitor the system bus voltage, current, and equipment temperature in real time. The motor power supply unit includes a contactor group, a fuse group, and a shared starting transformer for starting and running two motors. The status monitoring unit is used to collect the operating status of fuses and contactors in real time; The logic control unit is used to collect signals from the signal measurement unit, status monitoring unit and motor power supply unit, and execute motor start-up, operation control and failure protection according to preset logic. The status monitoring unit includes a fuse status feedback and self-test circuit and a vacuum contactor status feedback and self-test circuit. The fuse status feedback and self-test circuit includes a self-test relay, a micro switch, and a controller; The micro switch is installed at the end of the fuse, and the state of the micro switch is changed by the action of the impactor when the fuse fails. The coil of the self-test relay is connected to the output control channel of the controller, its common terminal contact is connected to the normally closed contact of the micro switch, the normally closed contact of the self-test relay is connected to the positive terminal of the power supply, and the normally open contact of the self-test relay is connected to the self-test output channel of the controller. The other end of the normally closed contact of the micro switch is connected to the digital input channel of the controller; The vacuum contactor status feedback and self-test circuit includes a vacuum contactor, a self-test relay, and a controller; The coil of the self-test relay is connected to the output control channel of the controller; For the vacuum contactor closing status feedback circuit, the first common terminal contact of the self-test relay is connected to one end of the two sets of normally open contacts of the vacuum contactor connected in parallel, the other end of the normally open contacts of the vacuum contactor is connected to the controller, the first normally closed contact of the self-test relay is connected to the positive terminal of the power supply, and the first normally open contact of the self-test relay is connected to the self-test output channel of the controller. For the vacuum contactor tripping status feedback circuit, the second common terminal contact of the self-test relay is connected to one end of the two sets of normally closed contacts of the vacuum contactor connected in series, the other end of the normally closed contacts of the vacuum contactor is connected to the controller, the second normally closed contact of the self-test relay is connected to the positive terminal of the power supply, and the second normally open contact of the self-test relay is connected to the self-test output channel of the controller.

2. The dual-motor reduced-voltage starting system for an electrically controlled excavator as described in claim 1, characterized in that, The signal measurement unit includes: The voltage measurement unit measures the bus voltage through a group of voltage transformers. The current measurement unit measures the current in each phase of the motor through a group of current transformers; The temperature measurement unit measures the temperature of the starting transformer and motor through a group of temperature sensors.

3. The dual-motor reduced-voltage starting system for an electrically controlled excavator as described in claim 1, characterized in that, The self-test process of the fuse status feedback and self-test circuit is as follows: Before the system starts running, the controller outputs a digital control signal to drive the coil of the self-test relay to be energized, so that the high-level self-test signal output by the controller is fed back to the controller through the normally open contact of the self-test relay, the micro switch and the controller's digital input channel; the controller monitors the feedback signal in real time, and if it is high, it determines that the circuit is normal, and if it is low, it determines that there is a fault in the circuit.

4. The dual-motor reduced-voltage starting system for an electrically controlled excavator as described in claim 3, characterized in that, The self-test process of the fuse status feedback and self-test circuit also includes: During system operation, the controller de-energizes the self-test relay coil, and the high-level signal of the system power supply is fed back to the controller through the normally closed contact of the self-test relay, the micro switch, and the controller's digital input channel. The controller monitors this feedback signal in real time. If it is high, the fuse is determined to be normal; if it is low, the fuse is determined to be faulty.

5. The dual-motor reduced-voltage starting system for an electrically controlled excavator as described in claim 1, characterized in that, The self-test process of the vacuum contactor status feedback and self-test circuit is as follows: The controller outputs a digital control signal to energize the coil of the self-test relay; For the vacuum contactor closing status feedback loop, the self-test high-level signal output by the controller is fed back to the controller via the first normally open contact of the self-test relay, the first common terminal contact, and the parallel normally open auxiliary contact of the vacuum contactor; if the controller detects that the feedback signal is high-level, it determines that the closing status feedback loop is normal. For the vacuum contactor tripping status feedback loop, the high-level self-test signal output by the controller is fed back to the controller via the second normally open contact, the second common terminal contact of the self-test relay, and the normally closed auxiliary contact of the vacuum contactor connected in series. If the controller detects that the feedback signal is low, it determines that the tripping status feedback loop is normal.

6. The dual-motor reduced-voltage starting system for an electrically controlled excavator as described in claim 1, characterized in that, The step of executing the motor start-up and operation control according to preset logic specifically includes: Close the first starting contactor, and after a preset delay, close the second starting contactor and the first motor contactor to start the first motor by reducing the voltage through the starting transformer; After the first motor starts, when the motor speed reaches the preset speed value, the first starting contactor and the second starting contactor are disconnected. After a preset dead time, the first running contactor is closed, so that the first motor can switch to rated voltage operation. Close the first starting contactor, and after a preset delay, close the second starting contactor and the second motor contactor to start the second motor by reducing the voltage through the starting transformer; After the second motor starts, when the motor speed reaches the preset speed value, the first and second starting contactors are disconnected. After a preset dead time, the second running contactor is closed, so that the second motor can switch to rated voltage operation.

7. A failure protection method for the dual-motor reduced-voltage starting system of an electrically controlled excavator as described in any one of claims 1-6, characterized in that, Includes the following failure protection modes: When the system is detected to have overvoltage, undervoltage, overcurrent, or overtemperature, the corresponding vacuum contactor will be disconnected. When a short-circuit fault is detected, the control disconnects the vacuum contactor, and the fuse provides circuit breaking protection at the same time. When contact sticking of the vacuum contactor is detected, a tripping command is sent to the vacuum circuit breaker in the incoming line cabinet to cut off the main power supply. If any motor power supply circuit device fails during self-testing, the system skips the faulty circuit or switches to the backup startup logic after user authorization interaction.

8. The failure protection method for a dual-motor reduced-voltage starting system of an electrically controlled excavator as described in claim 7, characterized in that, The backup startup logic includes: If the operating circuit of the first motor fails, the first motor will be skipped, and the second motor will be started normally with reduced voltage. If the operating circuit of the second motor fails, the second motor will be skipped, and only the first motor will be started normally with reduced voltage. If the first motor contactor or the second motor contactor fails, the other motor will be started normally with reduced voltage. After obtaining user authorization, the corresponding running contactor of the faulty motor will be closed to start the motor directly with full voltage. If the first or second starting contactor fails, after obtaining user authorization, the first and second running contactors will be directly controlled to close, so that both the first and second motors can be started directly at full voltage.

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