Abstract: A method for parallel non-redundancy operation of uninterruptible power supply apparatuses having a bypass circuit without using an additional common circuit. In the method of operating in parallel uninterruptible power supply apparatuses, each apparatus has two operational modes, a bypass feeding mode and an inverter feeding mode. An off-instruction for an AC switch that is turned on in the bypass feeding mode of one of the uninterruptible power supply apparatuses is produced in the respective uninterruptible power supply apparatuses when operated in the inverter feeding mode. The off-instruction is produced based on detection of coincidence of a bypass feeding signal which is active during the bypass feeding mode and a ready signal which becomes active when the inverter feeding mode is ready.

Abstract: A system for operating in parallel plural non-break power units, each unit including an inverter inserted between an input power source and a parallel bus and an AC switch inserted between the bypass power source and the parallel bus and having an inverter power supply mode via the inverter and a bypass source power supply mode via the AC switch when the inverter stops. Each unit includes a switch driver for generating an AC switch driving signal in response to an inverter power supply signal based on the output signal of a sequence control circuit. Inverter mode signal output terminals are mutually connected. The switch driver generates the relevant AC switch driving signal on the basis of an inverter supply signal synthesized on a per-unit basis.

Abstract: A system for operating in parallel plural non-break power units, each unit including an inverter inserted between an input power source and a parallel bus and an AC switch inserted between the bypass power source and the parallel bus and having an inverter power supply mode via the inverter and a bypass source power supply mode via the AC switch when the inverter stops. Each unit includes a switch driver for generating an AC switch driving signal in response to an inverter power supply signal based on the output signal of a sequence control circuit Inverter mode signal output terminals are mutually connected. The switch driver generates the relevant AC switch driving signal on the basis of an inverter supply signal synthesized on a per-unit basis.

Abstract: To obtain a parallel operation method for an uninterruptible power supply apparatus, the method being also capable of conducting a parallel non-redundancy operation of uninterruptible power supply apparatuses and having a bypass circuit incorporated therein without using an additional common circuit. In the parallel operation method for uninterruptible power supply apparatus of operating in parallel a plurality of uninterruptible power supply apparatuses, each having two operational modes including a bypass feeding mode and an inverter feeding mode, an off instruction for the AC switch is produced in the respective uninterruptible power supply apparatuses which are operated in parallel. The off instruction is produced based on a detection result showing coincidence of a pattern of (pattern coincidence detecting circuits 1002, 2002) the bypass feeding signal which is active during the bypass feeding state and a pattern of a ready signal which becomes active when the inverter feeding is ready for conducting.

Abstract: In a control circuit for a power converting apparatus, such as a three-phase inverter, unnecessary switching operations of switching elements are avoided.

Abstract: In a control circuit of a power converting apparatus such as a three-phase inverter, unnecessary switching operations of a plurality of switching elements employed in this three-phase inverter can be avoided.

Abstract: A rectifier control system with rectifiers connected in parallel operates constantly by ensuring balance between the rectifiers with respect to output voltage and current. The rectifiers apply a DC voltage to a single DC bus. Current detectors associated with the rectifiers detect the bus current flowing through the DC bus. Voltage control circuits associated with the rectifiers control the DC voltage to coincide with a voltage command value. Command value generating circuits associated with the rectifiers correct the voltage command value with a signal proportional to the detected bus current or a signal obtained by integrating or amplifying the bus current with an amplifier having a first order lag characteristic.

Abstract: A system for automatically detecting whether a power converter or inverter is correctly connected to a three-phase AC power source consisting of first, second, and third phases, the system comprising: a zero-crossing comparator (1) for determining whether the phase of the first-phase voltage (current) is in a positive half cycle or a negative half cycle and generating a first discrimination signal (C.sub.U); a zero-crossing comparator (2, 3) for determining whether the phase of the second- or third-phase voltages (current) is in a positive half cycle or a negative half cycle and generating a second discrimination signal (C.sub.V or C.sub.W); and a D-type flip-flop (5) which detects, in response to the first discrimination signal, that the second discrimination signal is in a predetermined half cycle.

Abstract: A 3-phase converter apparatus, in which a 3-phase A.C. power supply and a 3-phase converter operate in parallel on a common load BUS so as to share the load power, has an output voltage command generating device for generating an instantaneous command of the output voltage from the converter, and instantaneous voltage control device for controlling the converter so as to reduce the deviation of the instantaneous value of the output voltage of the converter from the instantaneous command generated by the output voltage command generating device. The converter includes at least one semiconductor switch for effecting a plurality of switching cycles in a half cycle of the A.C. power, so that the control of the phase of the output voltage of the converter with respect to the A.C. power supply is started at any moment.