Abstract: A ground fault sensing device for a drive system that converts direct current electrical power from a direct current power supply into alternating current electrical power and drives an electric motor with that alternating current electrical power, comprises: an extraction circuit that is connected to a power supply line of the direct current power supply via a coupling capacitor, that detects an amplitude wave that is generated when an alternating current side including the electric motor is suffering a ground fault, and that extracts the envelope of the amplitude wave; a measurement circuit that measures the voltage level of the envelope; and a determination circuit that makes a decision as to whether or not a ground fault has occurred on the alternating current side by comparing together the voltage level measured by the measurement circuit and a ground fault decision value.

Abstract: A ground fault sensing device for a drive system that converts direct current electrical power from a direct current power supply into alternating current electrical power and drives an electric motor with that alternating current electrical power, comprises: an extraction circuit that is connected to a power supply line of the direct current power supply via a coupling capacitor, that detects an amplitude wave that is generated when an alternating current side including the electric motor is suffering a ground fault, and that extracts the envelope of the amplitude wave; a measurement circuit that measures the voltage level of the envelope; and a determination circuit that makes a decision as to whether or not a ground fault has occurred on the alternating current side by comparing together the voltage level measured by the measurement circuit and a ground fault decision value.

Abstract: A rotary sensor that outputs two analog signals, such as one sine wave and one cosine wave and has multiple periods within one period of the electrical angle of a motor is employed. The motor is energized at each position for a specified length of time upon its startup by using multiple electrical angles corresponding to the multiple candidate absolute angles obtained from the rotary sensor signal as the initial position of the motor, and the electrical angle at which the motor acceleration becomes maximum is determined as the absolute angle. While the motor drive is in operation, on the other hand, the phase difference ?? between the phase of the motor at the counter electromotive voltage and the control phase is directly computed from the parameters of the motor, sensed current, voltage command and angle speed so as to correct the shifted position.

Abstract: The AC motor driving apparatus comprises an inverter for supplying power to an AC motor, current sensors for detecting current that flows in the motor or inverter, a rotation sensor for detecting the rotation of the rotor in the motor, and a control unit for controlling the driving of the inverter. A current detection value detected by the current sensor and a rotor rotational position are used to estimate three-phase motor current values. The estimated motor current values are used to control the inverter. Thereby, an inexpensive, space-saving AC motor driving apparatus as well as an AC motor controller, electric actuator, or vehicle that can perform highly precise torque control from zero speed to high-speed rotation without depending on the PWM pulse pattern are provided.

Abstract: The AC motor driving apparatus comprises an inverter for supplying power to an AC motor, current sensors for detecting current that flows in the motor or inverter, a rotation sensor for detecting the rotation of the rotor in the motor, and a control unit for controlling the driving of the inverter. A current detection value detected by the current sensor and a rotor rotational position are used to estimate three-phase motor current values. The estimated motor current values are used to control the inverter. Thereby, an inexpensive, space-saving AC motor driving apparatus as well as an AC motor controller, electric actuator, or vehicle that can perform highly precise torque control from zero speed to high-speed rotation without depending on the PWM pulse pattern are provided.

Abstract: A rotary sensor that outputs two analog signals, such as one sine wave and one cosine wave and has multiple periods within one period of the electrical angle of a motor is employed. The motor is energized at each position for a specified length of time upon its startup by using multiple electrical angles corresponding to the multiple candidate absolute angles obtained from the rotary sensor signal as the initial position of the motor, and the electrical angle at which the motor acceleration becomes maximum is determined as the absolute angle. While the motor drive is in operation, on the other hand, the phase difference ?? between the phase of the motor at the counter electromotive voltage and the control phase is directly computed from the parameters of the motor, sensed current, voltage command and angle speed so as to correct the shifted position.

Abstract: A master station and a plurality of slave stations are connected in multi-drop connection. A carrier wave on an upstream transmission line between the master station and the slave stations is demodulated and re-modulated in each slave station and always maintained to be on-state. Both the modulating and demodulating devices are performed by a MODEM following the protocol CCITT V.28, respectively. Each MODEM used is connected to the respective slave station by a signal line following the protocol EIAR3 232C.

Abstract: In a status-change gathering apparatus wherein status-change data is supplied to a processor from a plurality of inputting devices having a function of detecting status changes in a process or the like, each of the inputting devices is capable of producing an enable signal at a period not greater than the maximum allowed time between a detected status change in a controlled process and the controlling action to be performed by the processor, and of supplying the processor directly with an interrupt signal for requesting data gathering only when the enable signal is "on" and the status change has been detected. Upon receiving an interrupt signal from at least one inputting device, the processor sends a sense signal to all inputting devices, and any inputting device which has generated an interrupt signal places a response signal on a unique line to the processor to identify that inputting device. In this way, sequential scanning of inputting devices to detect changes in status is avoided.