Omron Corporation

Tokyo Institute of Technology

Omron Coproration

Masao Mabuchi

Yasuhiro Tsubota

Takao Mizokami

Kotaro Nakamura

Nobuyuki Toyoura

Kenji Kobayashi

Kazuyoshi Imamura

Hideaki Fujita

Katsutaka Tanabe

Shinichi Hosomi

Seiji Oka

Kenichi Inoue

Akihiro Funamoto

Takuya Nakai

Katsumi Ohashi

Teruyuki Maeda

Mio Yamada

Mio Miyamoto

Yuji Tsurukawa

Kunio Aono

Naoki Maki

Masaya Kato

Hironobu Hisashi

Kohei Takahashi

Akiyuki Tsunaga

Tomoya Irie

Satoru Ikemoto

Tomomi Yamashita

A converter is configured for connecting between a solar cell and an inverter configured to convert direct-current power output from the solar cell into alternating current power, and the converter is configured to increase the potential-to-ground at the negative terminal of the solar cell to greater than the potential-to-ground at the negative terminal of the inverter when outputting the direct-current power generated by the solar cell to the inverter side.

Solar power system and converter

During a single-phase three-wire output control process for causing a neutral point clamped inverter circuit to have a single-phase three-wire output, a power converter performs a potential control process for changing a potential of the O terminal to a positive or negative value to allow more power to be consumed from power stored in one of first and second capacitors with a higher voltage than from power stored in the other one of the first and second capacitors.

Power converter with capacitor voltage balancing

A distributed power system that is connected to a utility grid during both daytime and nighttime includes a plurality of power supplies including a solar array, a non-isolated DC-DC converter that has an input terminal and an output terminal and raises, at a predetermined step-up ratio, a DC voltage input from the power supplies via the input terminal and outputs the DC voltage via the output terminal, an inverter that converts the DC voltage output from the DC-DC converter via the output terminal into an alternating current, and a potential adjustment section that adjusts a potential at a negative electrode of the solar array to a potential higher than a potential at a negative electrode of the inverter at least during nighttime.

Distributed power system, DC-DC converter, and power conditioner

An inverter apparatus comprising a first switch group that is connected to a DC power source and includes a first switch and a second switch connected in series; a capacitor that has one end thereof connected to a first connection point between the first switch and the second switch; a second switch group that is connected in parallel with the capacitor and includes a third switch and a fourth switch that are connected in series; a switch control section that controls an ON/OFF state of the first switch, the second switch, the third switch, and the fourth switch to convert DC voltage from the DC power source into AC voltage and output the AC voltage from a second connection point between the third switch and the fourth switch; and a smoothing circuit that is connected to the second connection point and normalizes a pulse waveform of the AC voltage.

Inverter apparatus and solar power generation system

A power conditioner that suppresses distortion in a waveform of a sinusoidal generated voltage includes a first and second group including two switches each connected in inverse parallel and in series. The power conditioner alternately turns on and off both switches in the first group at a prescribed chopping frequency and alternately turns on and off both switches in the second group at a PWM frequency higher than the chopping frequency. If control is performed with a dead-time provided in the on/off timing for both switches in each group, the power conditioner adjusts and controls the on/off duty for the second group switches to correspond to the effective on drive in one switch by each diode during the dead-time for each switch in the first group.

Power conditioner

A power conditioner that suppresses generation of voltage spikes in a part of a generated sinusoidal voltage waveform. An offset between the timing of chopping, which depends on whether the voltage difference between the voltage of a third pulse voltage series and a sinusoidal voltage is positive or negative, and the timing of the switching between on/off duty cycles of a seventh and eighth switch is calculated, and the on/off duty cycles of the seventh and eighth switches are controlled on the basis of the timing offset.

A power conditioner of a photovoltaic system is configured operate at higher accuracy. A chopper circuit, a capacitor connected in parallel to the chopper circuit, and a control circuit that controls an ON/OFF status of switch elements in the chopper circuit to control charging and discharging of the capacitor are provided. The control circuit includes a measurement control section that measures an inter-end voltage of the capacitor and a control circuit section that performs a predetermined control operation from a measurement output of the measurement circuit section. The measurement circuit section includes a differential amplifier circuit that differentially amplifies the inter-end voltage of the capacitor. The circuit control section calibrates an in-phase component in the output of the differential amplifier circuit as an in-phase error and performs the control from the calibrated output from the differential amplifier circuit.

Control circuit, power conditioner including the control circuit, and photovoltaic system

A power converter enhances conversion efficiency from DC power to AC power. A first chopper circuit chops DC voltage from a photovoltaic panel at a system frequency producing a first square-wave whose voltage level changes positively. A second chopper circuit chops the first square-wave at a frequency double the system frequency producing a second square-wave whose voltage level changes negatively and adds the first square-wave and the second square-wave to produce a third square-wave that changes positively and negatively in a sine-wave manner. A third chopper circuit charges and discharges by chopping the third square-wave at a third frequency fixed by timing according to a difference between the third square-wave and a sine-wave voltage. PWM control is performed on the charge and discharge outputs such that the difference is corrected, producing a sine-wave voltage that continuously changes positively and negatively. A spike noise of an output voltage is suppressed.

DC/AC chopper type power converter for non-insulated type power conditioner with gain calibration of measuring circuit

A first circuit generates a first sequence of square wave voltages having a voltage level that changes to a positive side relative to a first reference potential, which is a potential on a negative-electrode side of a direct current power source, from a direct current voltage. A second circuit generates a second sequence of square wave voltages having a voltage level lower than the voltage level of the first sequence of square wave voltages on the positive side that changes to a negative side relative to a second reference potential. The second chopper circuit further generates a third sequence of square wave voltages having a voltage level that changes to the positive and negative side in turns in the manner of sinusoidal wave relative to the first reference potential by summing the first sequence of square wave voltages and the second sequence of square wave voltages. A third circuit outputs the third sequence of square wave voltages as a charge/discharge output. The third circuit further PWM-controls the charge/discharge output so that a difference of the third sequence of square wave voltages to a sinusoidal wave voltage is corrected and thereby generates a sinusoidal wave voltage that continuously changes to the positive and negative sides relative to the first reference potential from the third sequence of square wave voltages and the PWM-controlled output, and outputs the generated sinusoidal wave voltage to a load.

Power conditioner and solar photovoltaic power generation system

A first chopper circuit generates a first sequence of square wave voltages having a voltage level that changes to a positive side by chopping a direct current voltage at a system frequency. A second chopper circuit generates a second sequence of square wave voltages having a voltage level that changes to a negative side by chopping a direct current voltage at a frequency twice as high as the system frequency. The second chopper circuit further generates a third sequence of square wave voltages having a voltage level that changes to the positive and negative side in turns in the manner of sinusoidal wave by summing the first sequence of square wave voltages and the second sequence of square wave voltages. A third chopper circuit chops the third sequence of square wave voltages at a frequency determined by a timing that depends on if a voltage difference thereof to a sinusoidal wave voltage results in a positive value or a negative value and outputting the chopped third sequence of square wave voltages as a charge/discharge output. The third chopper circuit PWM-controls the charge/discharge output at a PWM frequency so that the difference is corrected to thereby generate a sinusoidal wave voltage that continuously changes to the positive and negative sides.

Power conversion apparatus, power conditioner, and power generation system

An isolated operation detecting method according to the present invention includes: a first step that injects a power fluctuation into the power system; a second step that measures a system cycle; a third step that adjusts the injection of the power fluctuation so that the system cycle increases when the system cycle is found increased than the previous system cycle as a result of the measuring, and decreases when the system cycle is found decreased than the previous system cycle; a fourth step that produces a change pattern of a latest system cycle on the basis of a deviation of the latest system cycle from a fixed number of cycle-passed previous system cycle; and a fifth step that determines an isolated operation on the basis of the change pattern.

Isolated operation detecting method, control apparatus for detecting isolated operation for distributed power supply

A direct current detection circuit has a zero-phase current transformer with source lines inserted therethrough for detecting current differences among them and generates a comparison voltage value based on a divided voltage value obtained between the zero-phase current transformer and a voltage divider resistor according to a change in the self-impedance of the zero-phase current transformer. An offset current is passed through the zero-phase current transformer to make it possible to detect on the basis of the comparison voltage value a direct current value in a range which is otherwise difficult to detect accurately on the basis of the comparison voltage value because of influence of hysteresis characteristic of the zero-phase current transformer. A control circuit detects a present direct current value based on the comparison voltage value and the value of the offset current.

Direct current detection circuit

A power conditioneris provided with a maximum power follow-up control portionfor setting a DC operating voltage of a power converter, which converts output power of a power generatorinto AC power, for making a power point corresponding to the output level of the power generator follow up with a maximum power point, and comprises an approximate function memoryfor storing approximate functions related to the maximum power point, a follow-up control portionfor making the present power point reach proximate of the maximum power point on the basis of the approximate function, and a hill-climbing method follow-up control portionfor making the present power point reach the maximum power point by using a hill-climbing method when the present power point has reached proximate of the maximum power point.

Maximum power follow-up control apparatus

An electric power conversion device comprises switching elements making up a push-pull converter, a pulse transformer T, a rectification diode D , a rectification diode D , a choke coil L, a smoothing capacitor C, a DC magnetic deviation prevention means , and an inverter . The DC magnetic deviation prevention means detects the coil currents I , I flowing in the primary windings M , M of the pulse transformer T. By controlling (shortening) the on time of the switching element having a greater amount of current, the coil currents I , I are balanced (I &equals;I ), thereby preventing the magnetic deviation phenomena of the pulse transformer T.

Growing community of inventors

Moriyama, Japan

Masao Mabuchi