An electric system of an electromechanical power transmission chain is provided that includes a first capacitive circuit, converter equipment between the first capacitive circuit and one or more electric machines, a second capacitive circuit, and a direct voltage converter between the first and second capacitive circuits. The electric system includes a control system for controlling the direct voltage converter in response to changes in first direct voltage of the first capacitive circuit and for controlling the converter equipment in response to changes in second direct voltage of the second capacitive circuit. The control of the first direct voltage is faster than the control of the second direct voltage so as to keep the first direct voltage on a predetermined voltage range and to allow the second direct voltage to fluctuate in order to respond to peak power needs.

An apparatus for controlling an inverter includes a volatile, first storage part; a nonvolatile, second storage part; and a control part configured to store data related to the status of the inverter in the first storage part when the inverter is driven and configured to select some of the data stored in the first storage part depending on the type of failure event when a failure event occurs and store the selected data in the second storage part.

An apparatus for controlling an inverter includes a volatile, first storage part; a nonvolatile, second storage part; and a control part configured to store data related to the status of the inverter in the first storage part when the inverter is driven and configured to select some of the data stored in the first storage part depending on the type of failure event when a failure event occurs and store the selected data in the second storage part.

In a current detection apparatus, one or more first plate portions, one or more second plate portions, and one or more third plate portions of one or more magnetic shields are opposed to side surfaces of the one or more protrusions. The one or more protrusions, the one or more magnetic field detection elements, and one or more conductive members are respectively surrounded by the one or more magnetic shields, respectively. Consequently, the current detection apparatus is downsized and has high current detection accuracy.

A press device includes a press device main body and a main breaker to supply or stop power from an external power supply to the press device main body. The press device main body includes a slide, a bolster disposed below the slide, a servomotor configured to drive the slide, a power storage unit able to supply stored power to the servomotor, a discharge unit configured to discharge a charge stored in the power storage unit, and a first contactor. An upper die can be mounted on the slide. A lower die can be disposed on the bolster. The first contactor interrupts an electrical connection between the power storage unit and the discharge unit in an energized state and electrically connects the power storage unit and the discharge unit in a non-energized state. The first contactor is supplied with power for energization from the external power source without passing through the main breaker.

A vehicle control apparatus capable of protecting a pre-charge circuit is provided. When a voltage has entered an operating voltage range, a microcomputer determines whether a preset period has elapsed from then. Upon determining that the preset period has elapsed, the microcomputer starts initial check. To carry out the initial check, the microcomputer starts charging a capacitor for power supply stabilization of a drive circuit by turning on the pre-charge circuit and, when the charging of the capacitor is completed, turns on a power supply relay provided on a power supply line that connects between a battery and the drive circuit.

A vehicle control apparatus capable of protecting a pre-charge circuit is provided. When a voltage has entered an operating voltage range, a microcomputer determines whether a preset period has elapsed from then. Upon determining that the preset period has elapsed, the microcomputer starts initial check. To carry out the initial check, the microcomputer starts charging a capacitor for power supply stabilization of a drive circuit by turning on the pre-charge circuit and, when the charging of the capacitor is completed, turns on a power supply relay provided on a power supply line that connects between a battery and the drive circuit.

A method for reducing noise at a wellsite includes transmitting a plurality of first signals from a variable frequency drive (VFD) to an alternating current (AC) induction motor. A timing of a plurality of second signals is varied to control transistors in an inverter of the VFD, thereby reducing harmonic distortion of the first signals output from the VFD. The timing is varied based at least partially upon an estimation of the harmonic distortion.

An electrical system for operating an AC electric motor in conjunction with a DC electrical energy storage and a DC electrical energy source is presented. It includes a multi-phase inverter or set of inverters, wherein multiple AC phases of the inverter or inverters are coupled to the motor, and separate DC connections of the inverter or inverters are coupled to the DC electrical energy source and the DC electrical energy storage.

A motor drive device is proposed. The motor drive device is configured to drive a motor having a plurality of windings respectively corresponding to a plurality of phases, and includes: a first inverter including a plurality of first switching elements, and connected to a first end of each of the plurality of windings; a second inverter including a plurality of second switching elements, and connected to a second end of each of the plurality of windings; and a controller configured to generate phase voltage commands of the first inverter and phase voltage commands of the second inverter based on preset voltage commands of the motor so that the phase voltage commands of the first inverter and the phase voltage commands of the second inverter are respectively represented as vectors of different angles.