Abstract: A controller uses a differential pressure between a discharge pressure and a suction pressure to estimate an execution time of braking control needed to fix a position of a rotor at a specific angle. Further, the controller executes the braking control by the estimated execution time. This prevents the controller from unnecessarily continuing to execute the braking control.

Abstract: The motor-driven compressor includes an electric motor, a housing, a compression portion, and an inverter device. The inverter device includes an inverter circuit, a current sensor, a coordinate converter, a speed controller, a current controller, a PWM controller, and a rotation angle estimator. The speed controller generates a d-axis current command value and a q-axis current command value such that a necessary torque to drive the electric motor occurs. The inverter device includes a heat-generating current command section that increases a temperature of the electric motor by changing the d-axis current command value and the q-axis current command value. The heat-generating current command section changes the d-axis current command value and the q-axis current command value so as to shift them in a direction in which a d-axis current value increases along a constant torque curve in a d-q coordinate system.

Abstract: A motor drive device drives a multi-phase synchronous motor in an electric compressor. The multi-phase synchronous motor includes a rotor that is provided with a permanent magnet and a stator having coils of different phases. The motor drive device includes an inverter that supplies current to the coils and a control unit that controls the inverter. The control unit executes an initial angular position calculation processing of detecting a d-axis and a q-axis as an initial angular position of the rotor, a rotating processing of rotating the d-axis and the q-axis in a direction opposite to rotation of the rotor, an acceleration processing of accelerating the rotation of the rotor, and a sensorless control processing of controlling the rotation of the rotor.

Abstract: A direct-current to three-phase alternating-current inverter system includes a three-phase motor, a plurality of switching elements, an inverter circuit for the three-phase motor, a capacitor, a direct-current power source and a control circuit. The switching elements arranged in the inverter circuit serve as upper and lower arms for the respective three phases of the three-phase motor, respectively. The capacitor is connected in parallel to the respective pairs of the upper and lower arms. The direct-current power source is arranged between the neutral-point of the three-phase motor and the respective lower arms or the respective upper arms. The control circuit controls the switching elements such that at least the switching frequency of one pair of the switching elements for one phase through which the current having the greatest value flows is lower than the switching frequencies of the other pairs of the switching elements for the other phases.

Abstract: A DC to three-phase AC inverter system includes a three-phase motor, an inverter circuit, switching elements, a capacitor, a DC power source and a control circuit. The DC power source is connected to the three-phase motor at a neutral point thereof. The control circuit calculates voltage commands, first through third divided boost commands by dividing a boost command, and first through third drive signals based on the voltage commands and the first through third divided boost commands. The second and third divided boost commands are used when the PWM control is performed by turning on and off the switching elements for the second and third phases while the switching elements for the first phase continues to be on or off state is set larger than those used when the PWM control is performed by turning on and off the switching elements for the first through third phases.

Abstract: A portable communication apparatus is provided, in which a plurality of event information items are acquired, each of which includes information acquired when a user executes a predetermined function of mobile phone and a date and time of this execution, and the plurality of event information items are stored in a memory in the form of an event list. When the user operates an operational unit and selects desired event information from the event list displayed on a display device, control means control such that the selected event information is read from the memory and sent to a server by communication means as information displayed with a predetermined display format. A server provides a simplified website including information sent from the portable communication apparatus. Accordingly, daily activities of the user are automatically recorded, and the user can easily build a simplified website (blog) based on the recorded contents of action.