Abstract: In the rectangular-wave voltage control mode, torque feedback control, in which the voltage phase of the rectangular-wave voltage is adjusted based on the deviation of the torque estimated value from the torque command value, is performed. A torque estimation portion calculates the torque estimated value using the motor currents calculated based on the values detected by a current sensor and a rotational position sensor, as in the case of the PWM control mode. Namely, the same state quantity (quantity detected by the sensors) of the alternating-current motor is used in the motor control in both the rectangular-wave voltage control mode and the PWM control mode.

Abstract: A fuel cell has a plurality of unit fuel cells and a gas manifold configured to path through the plurality of the unit fuel cells. Each of the plurality of unit fuel cells has an electrode and a separator. The separator includes in its interior a plurality of gas channels configured to communicate the gas manifold and a gas passage existing on a surface of the electrode. These gas channels include at least one gas through hole configured to open on a surface of the separator facing the electrode. The gas through holes provided on the plurality of gas channels include a first through hole group provided at a short distance from the gas manifold, and a second through hole group provided at a large distance from the gas manifold.

Abstract: A system for detecting engine speed in a multicylinder internal combustion engine provided with at least two sets of camshafts which are adapted for separate operation of valves connected to the sets of camshafts. The time detected is that for allowing one of the camshafts to rotate for an angle which is equal to or substantially equal to (720/N).times.n, where N is the number of cylinders and n is the number of sets of camshafts. The engine speed is calculated from the detected time. When the engine is in a predetermined state, such as an acceleration condition, the time is that for allowing the camshaft to rotate for an angle equal to or substantially equal to 720/N.