4169 results about "Short circuit fault" patented technology

A bidirectional switching device has a first main semiconductor element and a second main semiconductor element. The first main semiconductor element has a first main electrode connected to an ungrounded side of an AC power source, and a second main electrode. The first main semiconductor element contains a first parasitic diode whose cathode region is connected to the first main electrode and whose anode region is connected to the second main electrode. The second main semiconductor element has a third main electrode connected to the second main electrode, and a fourth main electrode connected to a load. The second main semiconductor element contains a second parasitic diode whose anode region is connected to the third main electrode and whose cathode region is connected to the fourth main electrode. A current flowing from the first main semiconductor element toward the second main semiconductor element passes through the second parasitic diode, and a current flowing from the second main semiconductor element toward the first main semiconductor element passes through the first parasitic diode. The bidirectional switching device is used to form a semiconductor active fuse for an AC power system. The semiconductor active fuse is capable of detecting an overcurrent without a shunt resistor, which was connected in series to a power supply cable, thereby minimizing heat dissipation as well as a conduction loss. The semiconductor active fuse is capable of easily and speedily detecting not only an overcurrent caused by a dead short but also an abnormal current caused by an incomplete short circuit failure having a certain extent of short-circuit resistance, and breaking alternating current in an AC power supply cable.

The invention discloses an intelligent fault diagnosis method suitable for a microgrid. The method comprises the following steps: monitoring the operation state of the microgrid through acquiring voltage current signals on a bus of the microgrid, determining whether an internal fault occurs in the microgrid, and accordingly, determining the starting mode of the diagnosis of the microgrid fault; according to the set condition of a fault diagnosis mode, acquiring the voltage current signals on the bus of the microgrid and carrying out preprocessing; by use of a multi-wavelet package decomposition technology, extracting fault signal transient components of different frequencies; calculating wavelet singular entropy as a characteristic vector of an RBF nerve network fault diagnosis mode of the microgrid; and inputting the characteristic vector into the diagnosis mode, outputting fault state information of the microgrid. According to the invention, a microgrid external fault diagnosis function and an internal short circuit fault diagnosis function are simultaneously provided, and a basis is provided for operation control and correlation protection of the microgrid.

The invention discloses a method for evaluating voltage dip sensitivity of sensitive equipment, belonging to the field of electric measurement. A voltage dip frequency of a power grid in a time section and depth and duration time of each voltage dip are monitored at a measurement point so as to establish a small sample set of practical voltage dips of the power grid in the time section, and a final evaluation result depends on equipment fault rate caused by measuring the voltage dip each time, so that influence degree of running conditions of the power grid in the time section on the sensitive equipment is really reflected, and influence of the voltage dips caused by various short-circuit faults in the power grids with different structures on the sensitive equipment can be reflected, so that related departments is guided to take more reasonable control measures or providing a basis for calculating economic loss caused by the voltage dips. Therefore, the method can be widely applied to the field of power supply quality control and management of the power grid.

A shift position of an electric powered vehicle is selected by operating a shift lever and a P position switch. A power source position is selected by operating a power switch. When any of switching elements forming an inverter device is short-circuited, selection of the shift position and the power source position is controlled such that simultaneous selection of a power source position at which inverter control is turned off and a shift position at which a parking lock mechanism is inactivated can be avoided. Therefore, inverter control for reducing short-circuit current caused by back electromotive force derived from rotation of a motor generator after occurrence of short-circuit failure can reliably be executed.

The invention provides a switch reluctance motor double master switch power converter master switch fault diagnosis method. A current sensor LEM1 is arranged on the master switch current circuit (DC)busand and is used for testing the total current of the main switch on the DC bus, a current sensor LEM2 is arranged on the free-wheeling diode DC bus and is used for testing the total current feedback by the free-wheeling diode on the DC bus, the wires of the two current sensors are connected with a receiver to obtain the total current signal of the master switch and the total current signal fedback by the free-wheeling diode. The invention can be used for judging that short trouble occurs to both the upper master switch tube and the lower master switch tube and open fault occurs to both theupper main switch tube and the lower main switch tube, and can be used for carrying out fault location, thus having convenient fault-tolerant control, and wide application prospects.

A controller identifies a condition of a hazardous internal short by comparing patterns of series element voltages to the last known balance condition of the series elements. If the loaded or resting voltage of one or more contiguous series elements uniformly drop from the previously known condition by an amount consistent with an over-current condition, an over-current internal short circuit fault is registered. The desired response is to prevent the affected series elements from heating to a hazardous temperature by summoning the maximum heat rejection capability of the system until the short ceases and the affected elements cool, the cooling function is no longer able to operate due to low voltage, or the affected series string has drained all of its energy through the short. Also includes are responses that allow the battery pack to continue to power the cooling system even though it may enter an over-discharged state.