Abstract: In a system for controlling a controlled variable of a rotary machine having plural-phase input terminals of the rotary machine in which plural-phase AC power is applied from an AC power applying module to the input terminals, a command-voltage setting module sets, based on a request value for the controlled variable, plural-phase AC command voltages for the plural-phase AC power as a feedforward manipulated variable. A current obtaining module obtains plural-phase AC currents flowing in the respective plural-phase input terminals of the rotary machine. An amplitude correcting module corrects the amplitude of at least one of the plural-phase AC command voltages based on the magnitudes of the plural-phase AC currents.

Abstract: In a system, a triangular carrier wave is compared in magnitude with first and second two-phase modulated command signals. Based on a result of the comparison, on-off operations of the high- and low-side switching elements of two phases of a three-phase inverter corresponding to the first and second two-phase modulated command signals are performed while the high- and low-side switching elements of the remaining phase of the three-phase inverter is fixed to be on or off. A value of a current flowing through a first or second bus connected between a DC power source and the three-phase inverter is measured when a local peak of the triangular carrier signal occurs while none of the high-side switching elements of all the three-phases are on or none of the low-side switching elements of all the three-phases are on.

Abstract: In a system, a triangular carrier wave is compared in magnitude with first and second two-phase modulated command signals. Based on a result of the comparison, on-off operations of the high- and low-side switching elements of two phases of a three-phase inverter corresponding to the first and second two-phase modulated command signals are performed while the high- and low-side switching elements of the remaining phase of the three-phase inverter is fixed to be on or off. A value of a current flowing through a first or second bus connected between a DC power source and the three-phase inverter is measured when a local peak of the triangular carrier signal occurs while none of the high-side switching elements of all the three-phases are on or none of the low-side switching elements of all the three-phases are on.

Abstract: In a system for controlling a controlled variable of a rotary machine having plural-phase input terminals of the rotary machine in which plural-phase AC power is applied from an AC power applying module to the input terminals, a command-voltage setting module sets, based on a request value for the controlled variable, plural-phase AC command voltages for the plural-phase AC power as a feedforward manipulated variable. A current obtaining module obtains plural-phase AC currents flowing in the respective plural-phase input terminals of the rotary machine. An amplitude correcting module corrects the amplitude of at least one of the plural-phase AC command voltages based on the magnitudes of the plural-phase AC currents.

Abstract: A fuel cell system includes a fuel cell constructed by plural stacked cells, a circulation path through which a thermal medium is circulated into each cell, a heater for heating the thermal medium, a bypass path through which the thermal medium is circulated into a part of each cell while bypassing the other part thereof, and a flow control valve for controlling a flow amount of the thermal medium circulated in the bypass path. The thermal medium can be circulated into only the part of each cell in a warm-up operation, so that the part of each cell is collectively heated. An amount of the thermal medium circulated into the other part of each cell is controlled, so that all of each cell is finally warmed up in the warm-up operation.

Abstract: A fuel cell generates electric power based on electrochemical reaction of reaction gases. A gas feed stopping device stops the feed of reaction gases into the fuel cell. At the time the power generation by the fuel cell is terminated, the fuel cell continues power generation for a while under a condition that the feed of one of the reaction gases is stopped by the gas feed stopping means. With this operation, the residual reaction gas in the fuel cell is consumed smoothly while the fuel cell continues power generation after the feed of one reaction gas is stopped. The electric potential of a cathode electrode decreases promptly. Deterioration of the cathode electrode is surely prevented.

Abstract: A plurality of individual fuel cells are connected in series with each other to construct the fuel cell. The fuel cell is diagnosed on the basis of an average output voltage Va of the individual cells, their standard deviation ?, individual output voltages, their variances ?2 of vibration components and their voltage drop speed of their non-vibration components. For example, if Va is within a normal range and moreover at least one of the individual output voltages is not within a normal range, it is diagnosed that water blocks the fuel electrode. If Va is not within a normal range and moreover ? is within a normal range, it is diagnosed that the electrolyte film is dried. Further, if Va is not within a normal range and moreover ? is not within a normal range, it is diagnosed that the fuel (hydrogen) supply is insufficient.

Abstract: A fuel cell system includes a fuel cell constructed by plural stacked cells, a circulation path through which a thermal medium is circulated into each cell, a heater for heating the thermal medium, a bypass path through which the thermal medium is circulated into a part of each cell while bypassing the other part thereof, and a flow control valve for controlling a flow amount of the thermal medium circulated in the bypass path. The thermal medium can be circulated into only the part of each cell in a warm-up operation, so that the part of each cell is collectively heated. An amount of the thermal medium circulated into the other part of each cell is controlled, so that all of each cell is finally warmed up in the warm-up operation.

Abstract: In a fuel cell system, a fuel cell includes plural stacked cells, a circulation passage for circulating a thermal medium to the fuel cell. The fuel cell has therein a plurality of thermal medium passages through which the thermal medium flows, and the thermal medium passages are provided such that the thermal medium from the circulation passage independently flows through the thermal medium passages. The thermal medium passages in the fuel cell have inlet portions from which the thermal medium is introduced, and outlet portions from which the thermal medium is discharged. In the fuel cell system, at least one-side portions among the inlet portions and the outlet portions are provided independently. Accordingly, a circulation area of the thermal medium in the fuel cell can be selectively changed, and a part of the fuel cell can be effectively heated to generate electrical power in this part.

Abstract: Provided is a fuel cell system capable of preventing a drop of power stemming from the water residence at an electrode portion or the shortage of water content in an electrolyte membrane. The system is equipped with an air pressure regulating valve for adjusting the pressure of air to be supplied to a fuel cell stack and a hydrogen pressure regulating valve for adjusting the pressure of hydrogen. In this system, the pressure difference between the air pressure and the hydrogen pressure is controlled through the regulating valves so that a minimum hydrogen pressure becomes higher than a maximum air pressure, or so that a minimum air pressure becomes higher than a maximum hydrogen pressure.

Abstract: A fuel cell system includes a fuel cell constructed by plural stacked cells, a circulation path through which a thermal medium is circulated into each cell, a heater for heating the thermal medium, a bypass path through which the thermal medium is circulated into a part of each cell while bypassing the other part thereof, and a flow control valve for controlling a flow amount of the thermal medium circulated in the bypass path. The thermal medium can be circulated into only the part of each cell in a warm-up operation, so that the part of each cell is collectively heated. An amount of the thermal medium circulated into the other part of each cell is controlled, so that all of each cell is finally warmed up in the warm-up operation.

Abstract: A fuel cell generates electric power based on electrochemical reaction of reaction gases. A gas feed stopping device stops the feed of reaction gases into the fuel cell. At the time the power generation by the fuel cell is terminated, the fuel cell continues power generation for a while under a condition that the feed of one of the reaction gases is stopped by the gas feed stopping means. With this operation, the residual reaction gas in the fuel cell is consumed smoothly while the fuel cell continues power generation after the feed of one reaction gas is stopped. The electric potential of a cathode electrode decreases promptly. Deterioration of the cathode electrode is surely prevented.

Abstract: Provided is a fuel cell system capable of preventing a drop of power stemming from the water residence at an electrode portion or the shortage of water content in an electrolyte membrane. The system is equipped with an air pressure regulating valve for adjusting the pressure of air to be supplied to a fuel cell stack and a hydrogen pressure regulating valve for adjusting the pressure of hydrogen. In this system, the pressure difference between the air pressure and the hydrogen pressure is controlled through the regulating valves so that a minimum hydrogen pressure becomes higher than a maximum air pressure, or so that a minimum air pressure becomes higher than a maximum hydrogen pressure.

Abstract: A plurality of individual fuel cells are connected in series with each other to construct the fuel cell. The fuel cell is diagnosed on the basis of an average output voltage Va of the individual cells, their standard deviation &sgr;, individual output voltages, their variances &sgr;2 of vibration components and their voltage drop speed of their non-vibration components. For example, if Va is within a normal range and moreover at least one of the individual output voltages is not within a normal range, it is diagnosed that water blocks the fuel electrode. If Va is not within a normal range and moreover a is within a normal range, it is diagnosed that the electrolyte film is dried. Further, if Va is not within a normal range and moreover &sgr; is not within a normal range, it is diagnosed that the fuel (hydrogen) supply is insufficient.

Abstract: In a fuel cell system, a fuel cell includes plural stacked cells, a circulation passage for circulating a thermal medium to the fuel cell. The fuel cell has therein a plurality of thermal medium passages through which the thermal medium flows, and the thermal medium passages are provided such that the thermal medium from the circulation passage independently flows through the thermal medium passages. The thermal medium passages in the fuel cell have inlet portions from which the thermal medium is introduced, and outlet portions from which the thermal medium is discharged. In the fuel cell system, at least one-side portions among the inlet portions and the outlet portions are provided independently. Accordingly, a circulation area of the thermal medium in the fuel cell can be selectively changed, and a part of the fuel cell can be effectively heated to generate electrical power in this part.

Abstract: A fuel cell system includes a fuel cell constructed by plural stacked cells, a circulation path through which a thermal medium is circulated into each cell, a heater for heating the thermal medium, a bypass path through which the thermal medium is circulated into a part of each cell while bypassing the other part thereof, and a flow control valve for controlling a flow amount of the thermal medium circulated in the bypass path. The thermal medium can be circulated into only the part of each cell in a warm-up operation, so that the part of each cell is collectively heated. An amount of the thermal medium circulated into the other part of each cell is controlled, so that all of each cell is finally warmed up in the warm-up operation.