Abstract: In an MMC-based power conversion device, a control device generates, for each leg circuit, a first voltage command value not based on circulating current circulating between a plurality of leg circuits and a second voltage command value based on the circulating current. A plurality of individual controllers are provided respectively corresponding to a plurality of converter cells and generate a gate control signal for controlling turning on and off of a switching element of the corresponding converter cell, based on the first voltage command value and the second voltage command value. When generating the gate control signal using pulse width modulation, each individual controller modulates a carrier signal in accordance with the second voltage command value such that the pulse width of the gate control signal changes in accordance with the second voltage command value.

Abstract: In a power conversion system, a first power converter is connected between a first AC power system, and a first DC main line and a DC return line. A second power converter is connected between the first AC power system, and the DC return line and a second DC main line. A first control device controls the first power converter in accordance with a first active power command value. A second control device controls the second power converter in accordance with a second active power command value. A common control device sets the first active power command value and the second active power command value by distributing a command value of total active power output from the entire power conversion system to the first AC power system. The common control device makes the first active power command value and the second active power command value different from each other.

Abstract: A power conversion device includes a self-commutated power converter that performs power conversion between an AC circuit and a DC circuit, and a control device that controls switching operation of a switching element included in the self-commutated power converter. The control device calculates a deviation between a control command value for the self-commutated power converter and a feedback value from the self-commutated power converter, and performs first control to increase a switching frequency of the switching element when the deviation becomes equal to or greater than a first threshold value.

Abstract: A power conversion device includes a self-commutated power converter that performs power conversion between an AC circuit and a DC circuit, and a control device that controls switching operation of a switching element included in the self-commutated power converter. The control device performs first control to increase a switching frequency of the switching element when a control command value for the self-commutated power converter becomes equal to or greater than a first threshold value.

Abstract: A power conversion system including: a self-excited power converter that converts power between an alternating-current (AC) power system and a direct-current (DC) line; an AC circuit breaker disposed between the AC power system and the self-excited power converter; an arrester connected between the DC line and a ground or between an AC line and the ground, the AC line connecting the AC circuit breaker and the self-excited power converter; and a control device. The control device causes the self-excited power converter to stop a switching operation when the control device detects a ground fault accident on the DC line, and opens the AC circuit breaker after the self-excited power converter stops the switching operation.

Abstract: A power conversion system includes: a self-excited power converter to perform power conversion between a first AC system and a DC system; a first transformer having a primary side connected to the first AC system and a secondary side connected to the self-excited power converter; and a first impedance circuit connected between a ground and a neutral point on the secondary side of the first transformer, or between the ground and an AC line connecting the secondary side of the first transformer and the self-excited power converter. The first impedance circuit includes one of a reactor and another transformer.

Abstract: In an MMC-based power conversion device, a control device generates, for each leg circuit, a first voltage command value not based on circulating current circulating between a plurality of leg circuits and a second voltage command value based on the circulating current. A plurality of individual controllers are provided respectively corresponding to a plurality of converter cells and generate a gate control signal for controlling turning on and off of a switching element of the corresponding converter cell, based on the first voltage command value and the second voltage command value. When generating the gate control signal using pulse width modulation, each individual controller modulates a carrier signal in accordance with the second voltage command value such that the pulse width of the gate control signal changes in accordance with the second voltage command value.

Abstract: A power conversion system includes: a self-excited power converter to perform power conversion between a first AC system and a DC system; a first transformer having a primary side connected to the first AC system and a secondary side connected to the self-excited power converter; and a first impedance circuit connected between a ground and a neutral point on the secondary side of the first transformer, or between the ground and an AC line connecting the secondary side of the first transformer and the self-excited power converter. The first impedance circuit includes one of a reactor and another transformer.

Abstract: A high-frequency oscillation apparatus wherein an oscillation signal output from a voltage controlled oscillator (VCO) is transferred through a transfer line to a resonator and the resonator is excited. The resonator is coupled with a second transfer line and an RF signal having a level corresponding to the frequency of the oscillation signal is transferred through the second transfer line. When the resonant frequency of the resonator is set to a frequency higher than the oscillation-frequency modulation range of the VCO, the oscillation frequency and the RF-signal level have one-to-one correspondence. A detector detects the RF signal and outputs to a control section. The control section compensates a control voltage signal applied to the VCO according to the detected-signal level, and outputs the control voltage signal to the VCO to compensate the oscillation signal of the VCO.

Abstract: A radio wave reflector has a function of reflecting radio waves in every direction in the plane including the incoming direction of the radio waves and can be fitted to various miscellaneous structures. The radio wave reflector includes a radio wave reflection material which is a conductor, and a base material including the radio wave reflection material in a non-contact state, and the conductor which is the radio wave reflection material is formed of a flaky or granular metal. The radio wave reflector includes the radio wave reflection material which is a dielectric, and the base material including the radio wave reflection material, and the dielectric which is the radio wave reflection material is formed of a flaky or granular ceramic.

Abstract: A guide marker includes a substrate and a radio-wave reflecting unit for reflecting radio waves at certain intensity in all directions in a virtual plane, including the incident direction of the radio waves, the radio-wave reflecting unit being provided in the surface of the substrate. The radio-wave reflecting unit includes a concave and convex portions provided in the substrate or radio-wave reflectors which resonate at the frequency of incident radio waves and which reflect the radio waves in the incident direction. The radio-wave reflectors are mounted on the substrate. A visual guide marker device includes one of a light-reflecting component having a reflection characteristic and a light-generating component which self-generates light, and a guide marker including a dielectric material.

Abstract: An antenna device capable of increasing the speed of scanning as well as extending the scanning angular range of a beam to obtain a high gain. A radar module and a communication apparatus having enhanced detection capabilities obtainable by using the antenna device. In the antenna device, electromagnetic waves radiated from a primary radiator are transmitted to a plurality of openings, e.g., dielectric lenses and/or reflectors or optical transmitters. The dielectric openings are arranged on a fixed portion and the primary radiator is arranged on a moving portion. The moving portion is displaced relatively with respect to the fixed portion. This arrangement enables the selection of an opening used for receiving each of the electromagnetic waves from the primary radiator to change the direction of the beam.

Abstract: A high-frequency oscillation apparatus wherein an oscillation signal output from a voltage controlled oscillator (VCO) is transferred through a transfer line to a resonator and the resonator is excited. The resonator is coupled with a second transfer line and an RF signal having a level corresponding to the frequency of the oscillation signal is transferred through the second transfer line. When the resonant frequency of the resonator is set to a frequency higher than the oscillation-frequency modulation range of the VCO, the oscillation frequency and the RF-signal level have one-to-one correspondence. A detector detects the RF signal and outputs to a control section. The control section compensates a control voltage signal applied to the VCO according to the detected-signal level, and outputs the control voltage signal to the VCO to compensate the oscillation signal of the VCO.

Abstract: An antenna apparatus such that a dielectric strip and a dielectric resonator are provided for form a primary vertical radiator, another dielectric strip is provided which is coupled to the dielectric strip to form a directional coupler, and a radiation beam is tilted by changing the relative position of the primary radiator with respect to the dielectric lens by displacing the primary vertical radiator in the direction coupler.

Abstract: A guide marker includes a substrate and a radio-wave reflecting unit for reflecting radio waves at certain intensity in all directions in a virtual plane, including the incident direction of the radio waves, the radio-wave reflecting unit being provided in the surface of the substrate. The radio-wave reflecting unit includes a concave and convex portions provided in the substrate or radio-wave reflectors which resonate at the frequency of incident radio waves and which reflect the radio waves in the incident direction. The radio-wave reflectors are mounted on the substrate. A visual guide marker device includes one of a light-reflecting component having a reflection characteristic and a light-generating component which self-generates light, and a guide marker including a dielectric material.

Abstract: A radio wave reflector has a function of reflecting radio waves in every direction in the plane including the incoming direction of the radio waves and can be fitted to various miscellaneous structures. The radio wave reflector includes a radio wave reflection material which is a conductor, and a base material including the radio wave reflection material in a non-contact state, and the conductor which is the radio wave reflection material is formed of a flaky or granular metal. The radio wave reflector includes the radio wave reflection material which is a dielectric, and the base material including the radio wave reflection material, and the dielectric which is the radio wave reflection material is formed of a flaky or granular ceramic.

Abstract: An antenna apparatus such that a dielectric strip and a dielectric resonator are provided to form a primary vertical radiator, another dielectric strip is provided which is coupled to the dielectric strip to form a directional coupler, and a radiation beam is tilted by changing the relative position of the primary radiator with respect to the dielectric lens by displacing the primary vertical radiator in the directional coupler.

Abstract: A power transfer device includes a first current transferring section connected between a first AC power source and a load, a second current transferring section with first and second switches which have opposite conduction directions, connected in parallel, and connected between a second AC power source and the load; a current detector for detecting a current flowing from the first AC power source to the load; a generator for generating a power transfer signal instructing transfer from the first AC power source to the second AC power source; a current direction estimator for estimating the direction of a current which flows from the first AC power source to the load when the second current transferring section enters the conduction state after a time period; and a conduction signal generator for causing one of the first and second switches to be conductive, so that the current flowing from the first AC power source to the load is cancelled, and, thereafter, causing the other of the first and second switches

Abstract: An antenna device capable of increasing the speed of scanning as well as extending the scanning angular range of a beam to obtain a high gain. A radar module and a communication apparatus having enhanced detection capabilities obtainable by using the antenna device. In the antenna device, electromagnetic waves radiated from a primary radiator are transmitted to a plurality of openings, e.g., dielectric lenses and/or reflectors or optical transmitters. The dielectric openings are arranged on a fixed portion and the primary radiator is arranged on a moving portion. The moving portion is displaced relatively with respect to the fixed portion. This arrangement enables the selection of an opening used for receiving each of the electromagnetic waves from the primary radiator to change the direction of the beam.

Abstract: An antenna apparatus such that a dielectric strip and a dielectric resonator are provided to form a primary vertical radiator, another dielectric strip is provided which is coupled to the dielectric strip to form a directional coupler, and a radiation beam is tilted by changing the relative position of the primary radiator with respect to the dielectric lens by displacing the primary vertical radiator in the directional coupler.