When no transformer is used in a grid-connected photovoltaic (PV) system, a galvanic connection between the grid and the PV array exists. In these conditions, dangerous leakage currents (common-mode currents) can appear through the stray capacitance between the PV array and the ground. In order to avoid these leakage currents, different inverter topologies that generate no varying common-mode voltages, such as the half-bridge and the bipolar pulsewidth modulation (PWM) full-bridge topologies, have been proposed. The need of a high-input voltage represents an important drawback of the half-bridge. The bipolar PWM full bridge requires a lower input voltage but exhibits a low efficiency. This letter proposes a new high-efficiency topology that generates no varying common-mode voltage and requires the same low-input voltage as the bipolar PWM full bridge. The proposed topology has been verified in a 5-kW prototype with satisfactory results

Transformerless Inverter for Single-Phase Photovoltaic Systems

A device for optically scanning and measuring an environment is provided. The device includes a movable scanner having at least one first projector for producing at least one uncoded first pattern on an object in the environment. The scanner includes at least one camera for recording images of the object provided with the pattern and a controller coupled to the first projector and the camera. The device further includes at least one second projector which projects a stationary uncoded second pattern on the object while the scanner is moved. Wherein the controller has a processor configured to determine a set of three-dimensional coordinates of points on a surface of the object from a set of images acquired by the camera based at least in part on the first pattern. The controller is further configured to register the set of images relative based in part on the stationary second pattern.

Device for optically scanning and measuring an environment

A method for providing maximum power point tracking for an energy generating device (202) using a local buck-boost converter (206) coupled to the device (202) is provided. The method includes operating in a tracking mode, which includes initializing a conversion ratio for the buck-boost converter (206) based on a previous optimum conversion ratio. A device power associated with the initialized conversion ratio is calculated. The conversion ratio is repeatedly modified and a device power associated with each of the modified conversion ratios is calculated. A current optimum conversion ratio for the buck-boost converter (206) is identified based on the calculated device powers. The current optimum conversion ratio corresponds to one of a buck mode, a boost mode and a buck-boost mode for the buck-boost converter (206).

Method and system for providing local converters to provide maximum power point tracking in an energy generating system

A high efficiency photovoltaic DC-DC converter achieves solar power conversion from high voltage, highly varying photovoltaic power sources to harvest maximum power from a solar source or strings of panels for DC or AC use, perhaps for transfer to a power grid at high power levels with coordinated control possible for various elements. Photovoltaic DC-DC converters can achieve efficiencies in conversion that are extraordinarily high compared to traditional through substantially power isomorphic photovoltaic DC-DC power conversion capability that can achieve 97%, 98%, 99.2% efficiency, or even only wire transmission losses. Switchmode impedance or voltage conversion circuit embodiments may have pairs of photovoltaic power interrupt switch elements and pairs of photovoltaic power shunt switch elements to first increase voltage and then decrease voltage as part of the desired photovoltaic DC-DC power conversion.

Systems for highly efficient solar power conversion

A controller executes local generation and local consumption pathways of: supplying power from a solar cell to an appliance, and charging a storage cell with power that remains after subtracting power consumed by the appliance from the solar cell power. In the absence of excess power, the storage cell and solar cell supply power. Power supply from a commercial electrical grid covers a power shortage that remains after subtracting solar cell power and storage cell power from the power consumed by the appliance. The controller also executes a second excess power selling mode pathway wherein excess power flows into the commercial electrical grid, and an assist mode wherein all solar cell power flows into the commercial electrical grid, and storage cell power flows to the appliance.

Power supply system.

PROBLEM TO BE SOLVED: To provide a system interconnection inverter which can accurately form waveform of an output current, even if changes occur in the input voltage to the inverter and in the system voltage SOLUTION: The high-frequency switching of a switching element of an inverter 5 is controlled, so that the upper limit and lower limit of the command value are generated in the predetermined hysteresis width for the command value forming the waveform of an output current is with a command value upper limit generating means 13 an a command value lower limit generating means 14, and an output reactor current of an output reactor 6a detected with an output reactor current detecting means 12 is maintained between the command value upper limit and command value lower limit When the output reactor current becomes lower than the command value lower limit, a switching element Q1 is turned on and the switching element Q2 is turned off When such an output reactor current exceeds the command value upper limit, the switching element Q1 is turned off, while the Q2 is turned on The output reactor current takes values between the command upper limit and lower limit, and the average current thereof becomes an output, current depending on the command value

System interconnection inverter

A novel utility-interactive inverter for photovoltaic system is proposed. This inverter has no transformer to reduce the size but has a unique power processing system consisting of a DC-DC converter and a single-phase semibridge inverter. The DC-DC converter is a two-quadrant type and performs boost/buck-mode operations to feed-forward/feed-back the instantaneous power to/from the utility. The feed-backing function is rarely utilized for such as controlling the power-factor in utility side to regulate the utility voltage. Although both the DC-DC converter and the inverter operate with high-frequency switching at all the time in the conventional scheme, only the DC-DC converter or the inverter operate with high-frequency switching in the proposed one. Thus, the switching losses are reduced significantly in the new system. Additionally, the DC-DC converter controls the input current so that the DC-inductor traps the ripple-power fed back from the utility. As a result, a large capacitor is not necessary to connect in the input of inverter in this new system. In the products, the efficiency marked very high value (i.e., 95.5 [%] and 95.1 [%] in the half-load and the rated full-load condition of 4.5 kW, respectively) where the utility voltage is 240 [V/sub RMS/] and the solar-cells voltage is 200 [V]. On the other hand, the total-harmonic-distortion of the utility current of the product marked very low value (i.e., 1.6 [%]) in the rated condition. The size of the power unit including the heat sink is reduced to 2/3 of the conventional one.

http://ieeexplore.ieee.org/iel5/9465/30041/01377019.pdf

A novel type of utility-interactive inverter for photovoltaic system

A novel utility-interactive inverter for photovoltaic system is proposed. This inverter has no transformer to reduce the size but has a unique power processing system consisting of a dc-dc converter and a single-phase full-bridge inverter. The dc-dc converter is a two-quadrant type and performs boost/buck-mode operations to feed-forward/feed-back the instantaneous power to/from the utility. The feed-backing function is rarely utilized for such as controlling the power-factor in utility side to regulate the utility voltage. Although both the dc-dc converter and the inverter operate with high-frequency switching at all the time in the conventional scheme, only the dc-dc converter or the inverter operate with high-frequency switching in the proposed one. Thus, the switching losses are reduced significantly in the new system. Additionally, the dc-dc converter controls the input current so that the dc-inductor traps the ripple-power fed back from the utility. As a result, a large capacitor is not necessary to connect in the input of inverter in this new system. In the products, the efficiency marked very high value (i.e., 95.5 [%] and 95.1 [%] in the half load and the rated load condition of 4.5 kW, respectively) where the utility voltage is 240 [V/sub RMS/] and the solar-cells voltage is 200 [V]. On the other hand, total harmonic distortion of the utility current of the product marked very low value (i.e., 1.6 [%]) in the rated condition. The size of the power unit including the heat-sink is reduced to 2/3 of the conventional one.

/pdf/a-novel-type-of-utility-interactive-inverter-for-4b661xlbuj.pdf

PROBLEM TO BE SOLVED: To attain both the followability and stability of maximum power point tracking control in a method for controlling a DC/DC converter connected to a solar light power generation device. SOLUTION: A control part 7 changes continuity rate change amounts in accordance with an operating point and can attain both the followability and stability of maximum power point tracking control in changing a continuity rate of a switching element 11 to perform maximum power point tracking control of the solar light power generation device 1. Since this method for controlling a DC/DC converter can be realized only with software, the converter can be produced at a low cost. COPYRIGHT: (C)2003,JPO

Method for controlling converter in solar power generation device

This paper deals with the new generation prototype of one-stage boost-half bridge (B-HB) series load resonant softswitching high-frequency inverter with a lossless snubbing edge resonant capacitor and two selective resonant capacitors in series with inductive load for consumer induction heating (IH) appliances. The B-HB high frequency inverter treated here is based upon a dual series load resonant frequency selection strategy, changed automatically in accordance with resistivity of metallic materials as IH loads. In the first place, the triplex series load resonant high frequency (three times of switching frequency) operated B-HB inverter is demonstrated for IH non-magnetic low resistivity metallic pans/utensils fabricated by aluminum, copper and multi-layer of aluminum and stainless steel. In the second place, the fundamental series load resonant frequency (switching frequency) operated B-HB high frequency inverter is also described for IH magnetic high resistivity metallic pans/utensils fabricated by iron, iron cast and stainless steel. Finally, the principle of operation and inherent unique features of the B-HB high frequency inverter employing dual series load resonant frequency selection scheme in accordance with either low resistivity or high resistivity IH loads is presented from an experimental point of view, along with its operating steady state performance. This new generation B-HB frequency inverter type built-in IH cooktop with two/three ranges is put into practice for home energy utilizations in all electricity residential systems.

Latest practical developments of triplex series load resonant frequency-operated high frequency inverter for induction-heated low resistivity metallic appliances in consumer built-in cooktops

Shinichiro Sumiyoshi

Papers

System interconnection inverter

A novel type of utility-interactive inverter for photovoltaic system

A novel type of utility-interactive inverter for photovoltaic system

Method for controlling converter in solar power generation device

Latest practical developments of triplex series load resonant frequency-operated high frequency inverter for induction-heated low resistivity metallic appliances in consumer built-in cooktops