Abstract: An inverter unit includes a first temperature detector that detects a first temperature of at least one of semiconductor elements and a periphery of the semiconductor elements, current detectors that detect a current of a motor, and a controller that switches a modulation mode of the motor to a two-phase modulation mode or a three-phase modulation mode on the basis of a detection result of the first temperature by the first temperature detector and detection results of the current by the current detectors.

Abstract: An inverter unit includes a first temperature detector that detects a first temperature of at least one of semiconductor elements and a periphery of the semiconductor elements, current detectors that detect a current of a motor, and a controller that switches a modulation mode of the motor to a two-phase modulation mode or a three-phase modulation mode on the basis of a detection result of the first temperature by the first temperature detector and detection results of the current by the current detectors.

Abstract: An inverter device includes a three-phase inverter, which has switching elements, and a controller, which is programmed to perform two-phase modulation control on switching of the switching elements between an ON state and an OFF state. The controller computes the power factor of a load. The controller determines whether or not the computed power factor is less than a preset threshold value. If the computed power factor is greater than or equal to the threshold value, the controller performs a phase shift to shift the central time point of an ON period or an OFF period for two phases other than a stop phase in the two-phase modulation control by 180 degrees, and if the computed power factor is less than the threshold value, the controller supplies the switching elements with ON and OFF control commands to perform the two-phase modulation control without performing the phase shift.

Abstract: An inverter device includes a three-phase inverter, which has switching elements, and a controller, which is programmed to perform two-phase modulation control on switching of the switching elements between an ON state and an OFF state. The controller computes the power factor of a load. The controller determines whether or not the computed power factor is less than a preset threshold value. If the computed power factor is greater than or equal to the threshold value, the controller performs a phase shift to shift the central time point of an ON period or an OFF period for two phases other than a stop phase in the two-phase modulation control by 180 degrees, and if the computed power factor is less than the threshold value, the controller supplies the switching elements with ON and OFF control commands to perform the two-phase modulation control without performing the phase shift.

Abstract: A probing test device is provided for contacting a plurality of probes with pads on a semiconductor wafer to be tested and supplying a test signal to a tester comprising a CPU for previously storing, as a reference image, the image signal obtained when the probes are correctly contacted with the electrode pads. The probing test device includes a mechanism for positioning these probes to be contacted with the pads on the wafer by moving the tested wafer relative to the probes, an optical system for image sensing those portions at which the probes are contacted with the pads, and a mechanism for positioning the optical system near to the pads by moving the optical system relative to the wafer. The CPU performs a comparison of the reference image signal with that image signal sensed for those portions at which the probes are contacted with the pads.