Abstract: An image forming apparatus includes a stack portion having recording materials, an image forming unit, a basis weight detection unit, an operating sound detection unit, and a mode selection unit. The basis weight detection unit detects a recording material basis weight based on an ultrasonic wave. The operating sound detection unit detect an abnormality of a generated operating sound. The mode selection unit selects, for each recording material fed to the image forming unit, between transmitting to the basis weight detection unit a first instruction for detecting the recording material basis weight and transmitting to the operating sound detection unit a second instruction for detecting the operating sound abnormality. In determining an interval at which each second instruction is transmitted, the mode selection unit determines the interval so that the interval and a cycle, in which properties of recording materials on the stack portion are repeated, do not continuously coincide.

Abstract: In a power conversion device for performing conversion from DC to AC, a positive-side capacitor and a negative-side capacitor with their connection point serving as a neutral point are provided between the positive and negative sides of the inputted DC power, and a switching pattern for specifying switching phases which are timings of ON/OFF driving switching elements of an inverter which outputs AC voltage having at least a positive-side potential, a negative-side potential, and a neutral point potential, is calculated so as to satisfy conditions for ensuring a modulation factor, eliminating harmonic components for respective orders of output voltage, ensuring a predetermined value for a phase difference between adjacent switching phases, and balancing voltage of the positive-side capacitor and voltage of the negative-side capacitor.

Abstract: A power conversion apparatus capable of supplying a required reactive power while dynamically changing a dead band near 0 reactive current and maintaining a balance of DC voltage is provided. The power conversion apparatus including a three-level converter, a PWM controller for the three-level converter, an input current detector of the three-level converter, a coordinate converter that converts the current into a d-axis and q-axis current feedback, the reactive power control unit that controls a reactive power and outputs an reactive current reference, a d-axis current control unit having a dead band part for setting the d-axis current reference with hysteresis characteristics in the q-axis current feedback, and outputs the d-axis voltage reference, a q-axis current control unit that outputs a q-axis voltage reference based on the q-axis current reference, an inverse coordinate converter that outputs a three-phase AC voltage command based on the d-axis and q-axis voltage reference.

Abstract: In a power conversion device for performing conversion from DC to AC, a positive-side capacitor (5a) and a negative-side capacitor (5b) with their connection point serving as a neutral point are provided between the positive and negative sides of the inputted DC power, and a switching pattern for specifying switching phases which are timings of ON/OFF driving switching elements (6) of an inverter (4) which outputs AC voltage having at least a positive-side potential, a negative-side potential, and a neutral point potential, is calculated so as to satisfy conditions for ensuring a modulation factor, eliminating harmonic components for respective orders of output voltage, ensuring a predetermined value for a phase difference between adjacent switching phases, and balancing voltage of the positive-side capacitor (5a) and voltage of the negative-side capacitor (5b).

Abstract: A sliding device includes a fixed rail, a movable rail, a shutter to close an opening of the fixed rail, an engaging body including a pressed portion, an engaged portion, a resilient element, and a pressing portion provided to the movable rail or the shutter. The shutter is slidable relative to the fixed rail by receiving a force from the movable rail. The engaging body is provided to one of the shutter and the fixed rail, and the engaged portion is provided to the other. The engaging body is displaceable between an engaged position where it is engageable with the engaged portion and a disengaged position displaced from the engaged position. The resilient element produces a resilient force maintaining the engaging body in the engaged position. The pressing portion contacts with the pressed portion when the movable rail slides, thus displacing the engaging body to the disengaged position.

Abstract: A power conversion device includes a transformer, a plurality of converter cells, and a control circuit that controls semiconductor switching elements in each of the converter cells to be turned on and off. The transformer includes: a primary winding group being connected in multiple phases to an AC power supply including multiple phases; and a plurality of secondary winding groups. Each secondary winding group includes, in each of the multiple phases, secondary windings each formed of a single-phase open winding. Each converter cell converts a single-phase AC voltage between AC nodes connected to the respective secondary windings into a DC voltage by control of the semiconductor switching elements to be turned on and off, and outputs the converted DC voltage between a pair of DC nodes. The DC nodes of the plurality of converter cells are connected in series between a first DC terminal and a second DC terminal.

Abstract: A power conversion apparatus capable of supplying a required reactive power while dynamically changing a dead band near 0 reactive current and maintaining a balance of DC voltage is provided. The power conversion apparatus comprises a three-level converter, a PWM controller for the three-level converter, an input current detector of the three-level converter, a coordinate converter that converts the current into a d-axis and q-axis current feedback, the reactive power control unit that controls a reactive power and outputs an reactive current reference, a d-axis current control unit having a dead band part for setting the d-axis current reference with hysteresis characteristics in the q-axis current feedback, and outputs the d-axis voltage reference, a q-axis current control unit that outputs a q-axis voltage reference based on the q-axis current reference, an inverse coordinate converter that outputs a three-phase AC voltage command based on the d-axis and q-axis voltage reference.

Abstract: A failure diagnosis system according to an embodiment includes a first power line, a second power line, a first main contact, a second main contact, a first electrical component, a second electrical component, and a control device. The first electrical component includes a first terminal electrically connected to a second part of the first power line and a second terminal electrically connected to a third part of the second power line. A state of the first electrical component is to be switched in a case where a voltage is applied between the first terminal and the second terminal. The control device is configured to determine whether an abnormality of the first main contact exists or not based on output of a control instruction relating to the first main contact and the state of the first electrical component.

Abstract: A power conversion device includes a transformer, a plurality of converter cells, and a control circuit that controls semiconductor switching elements in each of the converter cells to be turned on and off. The transformer includes: a primary winding group being connected in multiple phases to an AC power supply including multiple phases; and a plurality of secondary winding groups. Each secondary winding group includes, in each of the multiple phases, secondary windings each formed of a single-phase open winding. Each converter cell converts a single-phase AC voltage between AC nodes connected to the respective secondary windings into a DC voltage by control of the semiconductor switching elements to be turned on and off, and outputs the converted DC voltage between a pair of DC nodes. The DC nodes of the plurality of converter cells are connected in series between a first DC terminal and a second DC terminal.

Abstract: A power conversion apparatus and a power conversion system that ensure safety capable of reliably performing an emergency stop and have a failure monitoring function are provided. The command signal for emergency stop of the power conversion apparatus between the supervisory monitoring and control device and the power conversion apparatus is to be a dual system, and the supervisory monitoring and control device monitors a performance of emergency stop of the power conversion apparatus by delaying the start of operation for a predetermined time from the operation command signal output. The supervisory monitoring and control device check a soundness of the power conversion apparatus by generating a test operation signal during that delay period.

Abstract: A power conversion system that has two power conversion apparatuses each including a converter that can control a DC voltage and an inverter and that drives the AC motor by connecting the outputs of the two inverters in parallel is provided. The output voltage of one of the converters is controlled according to the difference between the detection currents detected by the two current detectors for detecting the output currents of the two inverters so that a cross current flowing through the two inverters is suppressed.

Abstract: A failure diagnosis system according to an embodiment includes a first power line, a second power line, a first main contact, a second main contact, a first electrical component, a second electrical component, and a control device. The first electrical component includes a first terminal electrically connected to a second part of the first power line and a second terminal electrically connected to a third part of the second power line. A state of the first electrical component is to be switched in a case where a voltage is applied between the first terminal and the second terminal. The control device is configured to determine whether an abnormality of the first main contact exists or not based on output of a control instruction relating to the first main contact and the state of the first electrical component.

Abstract: A power conversion system that has two power conversion apparatuses 2 each including a converter 21 that can control a DC voltage and an inverter 22 and that drives the AC motor 4 by connecting the outputs of the two inverters 22A and 22B in parallel is provided. The output voltage of one of the converters is controlled according to the difference between the detection currents detected by the two current detectors 6A and 6B for detecting the output currents of the two inverters 22A and 22B, respectively, so that a cross current flowing through the two inverters 22A and 22B is suppressed.

Abstract: In a motor drive system with inverter parallel connection, a laying cable impedance is identified by a test pulse, and a cross current suppression control gain is optimized to provide a power conversion apparatus that does not require a coupling reactor. In the motor drive system 1 in which the outputs of A-bank and B-bank inverters 20A and 20B are connected in parallel, a test pulse is outputted from the drive control unit 30 provided with the PWM controller 33 to the A and B bank inverters before operation. The laying cable impedance is identified from the DC voltage Vdc at the time of test pulse output and the response currents IA and IB. An adjustment gain is calculated from the ratio of installed cable impedance to specified cable impedance. Then, the proportional gain KP is multiplied to optimize the adjustment gain, and an on-delay time based on the optimized adjustment gain GL×KP is calculated during operation.

Abstract: A sliding device includes a fixed rail, a movable rail, a shutter to close an opening of the fixed rail, an engaging body including a pressed portion, an engaged portion, a resilient element, and a pressing portion provided to the movable rail or the shutter. The shutter is slidable relative to the fixed rail by receiving a force from the movable rail. The engaging body is provided to one of the shutter and the fixed rail, and the engaged portion is provided to the other. The engaging body is displaceable between an engaged position where it is engageable with the engaged portion and a disengaged position displaced from the engaged position. The resilient element produces a resilient force maintaining the engaging body in the engaged position. The pressing portion contacts with the pressed portion when the movable rail slides, thus displacing the engaging body to the disengaged position.

Abstract: A power conversion apparatus and a power conversion system that ensure safety capable of reliably performing an emergency stop and have a failure monitoring function are provided. The command signal for emergency stop of the power conversion apparatus between the supervisory monitoring and control device and the power conversion apparatus is to be a dual system, and the supervisory monitoring and control device monitors a performance of emergency stop of the power conversion apparatus by delaying the start of operation for a predetermined time from the operation command signal output. The supervisory monitoring and control device check a soundness of the power conversion apparatus by generating a test operation signal during that delay period.

Abstract: An inverter test apparatus includes a DC power supply, a second inverter which is connected to a DC side of the first inverter, an inductor which is connected between an AC side of the first inverter and an AC side of the second inverter, a first controller which controls an AC voltage of the first inverter to be at a constant amplitude and a constant frequency, a current detector which detects a current that flows through the inductor, a phase command value computation module which computes a phase command value of the second inverter so as to control the current detected by the current detector, and a second controller which controls a phase of the second inverter, based on the phase command value computed.

Abstract: In a motor drive system with inverter parallel connection, a laying cable impedance is identified by a test pulse, and a cross current suppression control gain is optimized to provide a power conversion apparatus that does not require a coupling reactor. In the motor drive system 1 in which the outputs of A-bank and B-bank inverters 20A and 20B are connected in parallel, a test pulse is outputted from the drive control unit 30 provided with the PWM controller 33 to the A and B bank inverters before operation. The laying cable impedance is identified from the DC voltage Vdc at the time of test pulse output and the response currents IA and IB. An adjustment gain is calculated from the ratio of installed cable impedance to specified cable impedance. Then, the proportional gain KP is multiplied to optimize the adjustment gain, and an on-delay time based on the optimized adjustment gain GL×KP is calculated during operation.