Abstract: In the present uninterruptible power supply apparatus, in a switching period in which a bypass power feed mode is switched to an inverter power feed mode, a semiconductor switch is turned on, a first electromagnetic contactor is turned off, a second electromagnetic contactor is turned on and, in this state, an inverter is activated to start a lap power feed mode, and the semiconductor switch is turned off to end the lap power feed mode. Accordingly, the lap power feed mode can be completed in a short time to reduce an increase of a terminal-to-terminal voltage of a capacitor and thereby prevent the terminal-to-terminal voltage of the capacitor from exceeding an upper limit voltage.

Abstract: In an uninterruptible power supply apparatus, AC current, which includes a feedback component having a value corresponding to deviation between terminal-to-terminal voltage of a capacitor and reference voltage, and a feed forward component obtained by multiplying load current by a gain, is passed into a converter such that the terminal-to-terminal voltage of the capacitor becomes the reference voltage. The gain is set to a first gain in an inverter power feed mode and a bypass power feed mode, and the gain is set to a second gain smaller than the first gain in a switching period of switching between the inverter power feed mode and the bypass power feed mode, to prevent the terminal-to-terminal voltage of the capacitor from exceeding an upper limit voltage in a lap power feed mode.

Abstract: A gate drive circuit of an uninterruptible power supply apparatus generates first and second gate drive signals in response to first and second PWM signals, and alternately turns on first and second IGBTs. When the first IGBT is on, the gate drive circuit sets the first gate drive signal to the “L” level in response to the second PWM signal and sets the second gale drive signal to the “H” level in response to a voltage across terminals of the first IGBT exceeding a threshold voltage.

Abstract: In an uninterruptible power supply apparatus, AC current, which includes a feedback component having a value corresponding to deviation between terminal-to-terminal voltage of a capacitor and reference voltage, and a feed forward component obtained by multiplying load current by a gain, is passed into a converter such that the terminal-to-terminal voltage of the capacitor becomes the reference voltage. The gain is set to a first gain in an iverter power feed mode and a bypass power feed mode, and the gain is set to a second gain smaller than the first gain in a switching period of switching between the inverter power feed mode and the bypass power feed mode, to prevent the terminal-to-terminal voltage of the capacitor from exceeding an upper limit voltage in a lap power feed mode.

Abstract: An uninterruptible power supply apparatus includes: an electromagnetic contactor including a first terminal that receives a first AC voltage supplied from an AC power supply and a second terminal connected to an AC node; a capacitor that is connected to a DC line and stores DC power; a converter that transmits and receives electric power between the AC node and the DC line; and a controller. In an activation mode, the controller turns on the electromagnetic contactor after controlling the converter such that a frequency and a phase of a second AC voltage supplied from the converter to the AC node match a frequency and a phase of the first AC voltage. In a normal operation mode after the activation mode, the controller controls the converter such that a DC voltage of the DC node attains to a reference voltage.

Abstract: A power supply device includes an inverter, a voltage converter, a capacitor, a current detector, a counter, and a controller. The inverter converts DC power into AC power and supplies the converted AC power to a load. The voltage converter performs voltage conversion for a DC voltage from a battery. The capacitor smoothes the DC voltage from the voltage converter and inputs the smoothed DC voltage to the inverter. The current detector detects a battery current flowing from the battery into the voltage converter. The counter measures a discharge time of the battery. The controller stops the voltage converter when the measured discharge time of the battery exceeds a discharge permissible time. Based on an output from the current detector, the controller sets the discharge permissible time to be shorter as the battery current is higher when the battery current exceeds a threshold value during discharging of the battery.

Abstract: A cab capable of shielding solar radiation comprises a pair of front pillars and a pair of vertical beams; a front window glass member mounted movably along guide rails formed along the front pillars and the vertical beams, between a closing position for closing a front window formed between the front pillars and an opening position for opening the front window accommodated between the vertical beams; a roll screen and a winding member, wherein the winding member is disposed behind the inner surface of the front window glass member positioned at the closing position and in front of the front end of the front window glass member positioned at the opening position and on the outer side of the pair of guide rails; and a holding means attached to the front pillars and configured to releasably hold the leading end of the screen.

Abstract: A gate drive circuit of an uninterruptible power supply apparatus generates first and second gate drive signals in response to first and second PWM signals, and alternately turns on first and second IGBTs. When the first IGBT is on, the gate drive circuit sets the first gate drive signal to the “L” level in response to the second PWM signal and sets the second gale drive signal to the “H” level in response to a voltage across terminals of the first IGBT exceeding a threshold voltage.

Abstract: A control device controls an inverter such that a detected value of an output current of an inverter follows a current command value. The control device is configured to calculate a current deviation between the current command value and the detected value of the output current of the inverter, and control switching of switching elements to allow the calculated current deviation to be equal to or less than a current deviation command value. The control device sets a current limiter for a load current, the current limiter being smaller than an over current level, a load current with a current limiter smaller than an overcurrent level. When the detected value of the load current is larger than the current limiter, the control device reduces the current deviation command value to be smaller than that applied when the load current is smaller than the current limiter.

Abstract: A control device controls an inverter such that a detected value of an output current of an inverter follows a current command value. The control device is configured to calculate a current deviation between the current command value and the detected value of the output current of the inverter, and control switching of switching elements to allow the calculated current deviation to be equal to or less than a current deviation command value. The control device sets a current limiter for a load current, the current limiter being smaller than an over current level, a load current with a current limiter smaller than an overcurrent level. When the detected value of the load current is larger than the current limiter, the control device reduces the current deviation command value to be smaller than that applied when the load current is smaller than the current limiter.

Abstract: To provide a cab for construction machine capable of shielding at least a part of the solar radiation entering from the front window at any time of closing or opening a front window.

Abstract: A regulation device including a stopper receiving part mounted on the machine frame and/or the bottom of the cab includes a through hole formed at the center part, a shaft penetrating the through hole of the stopper receiving part and a stopper supported by the shaft. A spherical surface is formed on the side surface of a stopper where a stopper receiving part contacts. When the cab displaces in the direction away from the machine frame, the spherical surface of the stopper contacts in vicinity of a through hole of the receiving part to inhibit detachment.