32results about How to "Avoid overcurrent faults" patented technology

The invention discloses a crossing control device, system and method for train pantograph-catenary disconnection. The device comprises a pantograph-catenary disconnection detecting unit, a rectification control unit and an inverter control unit. The pantograph-catenary disconnection detecting unit is used for detecting the pantograph-catenary disconnection state of a train; the rectification control unit is used for controlling a rectifying module to realize stable direct voltage of a middle DC circuit when the train is in normal operating conditions; the rectification control unit is used forcontrolling the rectifying module to realize stable primary voltage of a traction transformer when the train is in pantograph-catenary disconnection conditions; the inverter control unit is used forcontrolling an inverter module to realize the consistency of output torque of a traction motor and the given torque when the train is in normal operating conditions; the inverter control unit is usedfor controlling the inverter module to realize the stable direct voltage of the middle DC circuit when the train is in pantograph-catenary disconnection conditions. The crossing control device, system, andmethod disclosed by the invention can solve the technical problems that transformer primary overcurrent fault or four-quadrant AC side overcurrent fault as well as DC voltage shortage or auxiliary transformer shutdown fault in a traction system can be easily caused in pantograph-catenary disconnection, in particular to arc-free pantograph-catenary disconnection.

The invention discloses a current-limiting and controlling method of active damping of a current-limiting and tank circuit. The output of a first half bridge (HB1) of a first current source inverter (CSC1) has the same phase with a first filter capacitor (C1) and the current with the amplitude of 1 / R; the output of a second half bridge (HB2) of the first current source inverter (CSC1) has the same phase with a second filter capacitor (C2) and the current with the amplitude of 1 / R; the output of a third half bridge (HB3) of the first current source inverter (CSC1) has the same phase with a third filter capacitor (C3) and the current with the amplitude of 1 / R; or the output of the first current source inverter (CSC1) has the same phase with the first filter capacitor (C1) and the current with the amplitude of 1 / R; the output of a second current source inverter (CSC2) has the same phase with the second filter capacitor (C2) and the current with the amplitude of 1 / R; and the output of a third current source inverter (CSC3) has the same phase with the third filter capacitor (C3) and the current with the amplitude of 1 / R. In the invention, open-loop control is needed only and the response speed is nearly instantaneous.

The invention discloses a two-stage matrix converter based starting / generating system and a control method thereof. In the system, a starter / generator is disposed on a unidirectional switch side of a converter, and a starting power source and a load are disposed on a bidirectional switch side. On hardware, only a switch needs to be arranged between the starting power source and the load to achieve switching from a starting state to a generating state; during state switching, control algorithms need not to be changed too much; the whole starting / generating system has the advantages of compact structure, efficiency and reliability, achieves starting / generating integrated operation easily, and is suitable for aviation starting / generating systems.

The invention discloses a method for preventing overcurrent of a three-phase motor, comprising: performing inverse Park transformation and inverse Clark transformation on the obtained D-axis demand current and Q-axis demand current to obtain the three-phase current of the motor; when the three-phase current When the preset three-phase current threshold is exceeded, the three-phase current is corrected to obtain the corrected three-phase current; Park transformation and Clark transformation are performed on the corrected three-phase current to obtain the corrected D-axis demand current and Q-axis demand current; When the absolute value of the motor speed is less than the preset speed threshold, output the corrected D-axis demand current and Q-axis demand current; when the absolute value of the motor speed is greater than the preset speed threshold, reacquire the D-axis demand current and Q-axis according to the formula shaft demand current, repeat all the above steps. Through the above method, the motor can avoid the overcurrent fault.

The invention discloses a current control method for automatically judging the current state of a switch reluctance motor. The method comprises the following steps: judging whether the reluctance motor is in an electric state or a generating state by judging the relation between the actual current of a phase coil winding and upper and lower given currents; then controlling the on / off of switch tubes inside a power switching circuit according to the result of the judgment, alternately turning off a single switch tube to limit current when the reluctance motor is in the electric operation state,and turning off two switch tubes when the reluctance motor is in the generating state to feed back energy to a bus capacitor, so that overcurrent faults caused by the fact that the off of the switchtubes is not controlled in time are avoided. The judgments for the electric and generating states depend on current signals, and external signals are not needed, so that the circuit structure is simplified, and the operation efficiency is improved.

The invention provides a parallel control method for high-capacity energy accumulation converters of an energy accumulation power station. The parallel control method comprises the steps that first, all electrical equipment in the energy accumulation power station is initialized; second, communication information is sent between PCS units; third, if the quantity of the communication information sent by the PCS units and the quantity of response information received by the PCS units are the same, the PCS units start to conduct grid connection; fourth, one PCS unit is determined to be used as a main machine, and the rest PCS units are slave machines; fifth, the slave machines conduct adjusting according to the output voltage of the main machine, and grid connection begins; sixth, if the slave machines do not complete grid connection within preset time, grid connection is stopped, and grid connection failure signals are sent. Compared with the prior art, according to the parallel control method for the high-capacity energy accumulation converters of the energy accumulation power station, on-line reliable parallel connection of the multiple energy accumulation converters can be achieved, and the capacity of the energy accumulation power station is expanded. The strategy of electrically free main machine seizing of the energy accumulation converters is adopted, the risk of faults caused by manually setting the main machine is avoided, and the reliability of the energy accumulation power station is improved.

The invention discloses a protection device and method for an electric vehicle air compressor energy supply system. The method includes: detecting the current state of the air compressor energy supply system; starting a first current limiting mode when the current state is an overshoot state, wherein the air compressor energy supply is reduced in the first current limiting mode The output frequency of the system. According to the device of the present invention, the overcurrent fault of the functional system of the air compressor of the electric vehicle can be avoided, thereby greatly improving the stability and safety of the electric vehicle; compared with the prior art, the device of the present invention is simple in structure, easy to implement, and has the advantages of High practical value and promotion value.

The invention discloses a motor control method, comprising the following steps: detecting the rotational speed of the motor; calculating the rotational speed change rate of the motor according to the detected rotational speed of the motor and a given rotational speed of the motor; when the rotational speed change rate of the motor is greater than a preset value , adjust the proportional-integral parameter of the speed loop in the motor control system, and adjust the lower limit of the q-axis current upper limit of the motor. The control method of the motor avoids motor overcurrent or stall failure caused by abnormal current, and ensures safe and reliable operation of the motor under low-frequency heavy load and during the entire operation process. The invention also discloses a motor control system.