Abstract: An electric riding mower efficiently cools a motor driver. The mower includes two running motors 16 independently driving paired rear tires 13; a mower blade mowing grass by being rotated; a mowing motor 15 rotating the mower blade; a battery 25 supplying electric power to the running motors 16 and the mowing motor 15; and a mower-motor driver MD controlling the rotational speed of the mowing motor 15, wherein the mower-motor driver MD is disposed in a driver storage part on a front part of the mower, and a slit 33SL taking in external air is disposed on a front surface of the driver storage part.

Abstract: There is provided a DC-DC converter circuit with which conduction loss between switching elements is lower than in the conventional art, which affords an increase in power conversion efficiency. A DC-DC converter circuit includes a first switching element including a first semiconductor switch and a first diode, a second switching element including a second semiconductor switch and a second diode, an inductor connected between the cathodes of the first and second diodes, and a third switching element and a fourth switching element provided so as to face in mutually opposite directions on the anode sides of the first and second diodes, wherein a first voltage supply is connected between the cathode side of the first diode and the anode side of the second diode, and a second voltage supply is connected between the anode side of the first diode and the cathode side of the second diode.

Abstract: Provided is a mobile electric work machine that can avoid overload operation of working parts. The mobile electric work machine is an electric lawn mowing work machine that carries out work by working parts driven by electric power supplied by blade inverters while being run by a running part. The blade rotational velocity of a blade or the rotational velocity of a blade is controlled such that the work load on the working parts is constant on the basis of blade inverter current values from blade inverters.

Abstract: An electrically-driven work machine can exchange electric power between a storage battery and an electric power system or between the storage battery and a load by utilizing an inverter equipped therein. When electric power is exchanged between the storage battery BT and the electric power system PW or the load, the connection between the inverter INV and the storage battery BT is disconnected by an on-off switch S0. Further, by change-over relays RY1 to RY3, one of AC phases from the inverter INV is connected to a wire LC1 via a DC inductor Ldc, and the other two phases are connected to the electric power system PW or the load via AC inductors Lac. When a motor Ma is driven by the storage battery, the on-off switch S0 provides a connection between the anode or cathode of the inverter and the storage battery BT.

Abstract: A pulse pattern generating configuration for a three-phase current source electric power converter is provided that ensures a minimal switching loss regardless of the level of power factor, and thus improves the electric power conversion efficiency. When an inter-line voltage non-maximum phase (U-phase) and a line current command value maximum phase (U-phase) match one another, in one modulation period T, a separation time T1 is established to separate, in time, switching pulses of two phases (V-phase, and W-phase) other than the line current command value maximum phase, and a short-circuit pulse SP is disposed in the line current command value maximum phase (U-phase).

Abstract: An electric riding mower efficiently cooling a motor driver with a simple configuration is provided. Provided are two running motors 16 independently driving paired rear tires 13; a mower blade mowing grass by being rotated; a mowing motor 15 rotating the mower blade; a battery 25 supplying electric power to the running motors 16 and the mowing motor 15; and a mower-motor driver MD controlling the rotational speed of the mowing motor 15, wherein the mower-motor driver MD is disposed in a driver storage part on a front part of the mower, and a slit 33SL taking in external air is disposed on a front surface of the driver storage part.

Abstract: There is provided a DC-DC converter circuit with which conduction loss between switching elements is lower than in the conventional art, which affords an increase in power conversion efficiency. A DC-DC converter circuit includes a first switching element including a first semiconductor switch and a first diode, a second switching element including a second semiconductor switch and a second diode, an inductor connected between the cathodes of the first and second diodes, and a third switching element and a fourth switching element provided so as to face in mutually opposite directions on the anode sides of the first and second, wherein a first voltage supply is connected between the cathode side of the first diode and the anode side of the second diode, and a second voltage supply is connected between the anode side of the first diode and the cathode side of the second diode.

Abstract: A DC-DC converter circuit includes first to sixth semiconductor switches and an inductor. The first to third semiconductor switches are connected to one end of the inductor. The fourth to sixth semiconductor switches are connected to the other end of the inductor. A first voltage supply is connected to opposite ends of the first and fourth semiconductor switches from the ends of the first and fourth semiconductor switches connected to the inductor. A second voltage supply is connected to opposite ends of the second and fifth semiconductor switches from the ends of the second and fifth semiconductor switches connected to the inductor. The first voltage supply and the second voltage supply are both connected to opposite ends of the third and sixth semiconductor switches from the ends of the third and sixth semiconductor switches connected to the inductor.

Abstract: A power generation system is provided that implements an efficient, labor-saving system interconnection in which an engine generator system, an external power supply system, and a capacitor are connected in parallel to each other, without the conventional practice to change the configuration of the engine generator system or provide an additional circuit. A power generation system implements a system interconnection in which an engine generator system, an external power supply system, and a capacitor are connected in parallel to each other. The power generation system includes discontinuing means for discontinuing direct-current voltage control by which a direct current voltage of the capacitor is controlled when electric power from a generator is supplied to the capacitor while direct current electric power that an external power supply supplies is lower than demand power that a power generation system is supposed to supply.

Abstract: The card connector has an eject operation detection switch SW arranged to turn on immediately after the ejection button has begun to be pressed, and an eject operation mechanism arranged to, in response to the pressing operation of the ejection button, start a card eject operation after the eject operation detection switch SW has turned on. This card connector reliably avoids a card error even when the ejection button is erroneously operated, thereby preventing a data loss.