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Somani A.,University of Minnesota | Somani A.,Dynapower Company | Gupta R.K.,General Electric | Mohapatra K.K.,University of Minnesota | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2013

Electric drives with open-end winding ac machines offer certain advantages over drives with star-or delta-connected machines. Such drives have been recently considered for some applications such as electric vehicles. Circulating currents have been experimentally observed in such open-end winding ac drives. These currents have the effect of increasing conduction losses in the stator winding resistance of the ac machine. Two major causes for these currents have been identified as device voltage drops in power semiconductor devices and dead time used for shoot-through current protection. These effects are analyzed, and a mathematical description for predicting their severity is provided. Experimental results are presented that support the theory. The theory developed should be useful for devising solutions for this problem such as the design of common-mode filters. Two methods of suppressing the circulating currents are also outlined, and their experimental results are presented. © 1982-2012 IEEE.


Basu K.,Dynapower Company | Mohan N.,University of Minnesota
IEEE Transactions on Industrial Electronics | Year: 2014

This paper presents a novel topology for the generation of adjustable frequency and magnitude pulsewidth-modulated (PWM) three-phase ac from a balanced three-phase ac source with a high-frequency ac link. The proposed single-stage power electronic transformer (PET) with bidirectional power flow capability may find application in compact isolated PWM ac drives. This topology along with the proposed control has the following advantages: 1) input power factor correction; 2) common-mode voltage suppression at the load end; 3) high-quality output voltage waveform (comparable with conventional space vector PWM); and 4) minimization of output voltage loss, common-mode voltage switching, and distortion of the load current waveform due to leakage inductance commutation. A source-based commutation of currents associated with energy in leakage inductance (termed as leakage energy) has been proposed. This results in soft-switching of the output-side converter and recovery of the leakage energy. The entire topology along with the proposed control scheme has been analyzed. The simulation and experimental results verify the analysis and advantages of the proposed PET. © 1982-2012 IEEE.


Basu K.,Dynapower Corporation | Mohan N.,University of Minnesota
IEEE Transactions on Power Electronics | Year: 2014

This paper presents a single-stage bidirectional high-frequency transformer (HFT) link dc/ac converter topology for a three-phase adjustable magnitude and frequency PWM ac drive. This type of converters find a wide range of applications including UPS systems, drives involving renewable energy sources (Solar, Fuel cell), and energy storage systems (typically low voltage dc to high voltage PWM ac). The HFT results in reduction in cost and weight along with a considerable increase in power density. The adverse effects of common-mode voltage are well known in this kind of applications. The proposed topology along with a modulation technique reduces common-mode voltage to practically zero and generates high-quality output voltage waveform comparable to conventional space vector PWM (CSVPWM). A source-based commutation method, presented in this paper, to commute the energy stored in the leakage inductance of the HFT resulting in the following advantages 1) no need for any auxiliary circuits with passive components; 2) almost complete recovery of the leakage energy; 3) soft switching of the output side converter for all load conditions; and 4) minimization of common-mode voltage switching due to commutation. The converter along with the suggested control has been analyzed in detail. The presented simulation and experimental results confirm the operation of the proposed converter. © 2014 IEEE.


Basu K.,Dynapower Corporation | Sahoo A.K.,University of Minnesota | Chandrasekaran V.,Trane Inc. | Mohan N.,University of Minnesota
IEEE Transactions on Power Electronics | Year: 2014

This paper presents a systematic step-by-step design procedure for the input filter of a current source rectifier (CSR). The design is based on the specifications of allowable ripple in the input voltage of the CSR and high-frequency harmonic components in the grid current. Analytical techniques have been developed to estimate the ripple present in the input current and to model the converter for fundamental or grid frequency. The analysis is done for carrier-based and space-vector modulation of the current source rectifier and the model at grid frequency is used to evaluate the design of the filter for grid power factor, voltage drop across filter, etc. A damping resistance is designed ensuring a minimum power loss. The analysis and design of the input filter have been verified by simulations in MATLAB/Simulink and experimental tests on a laboratory prototype. © 2014 IEEE.


The present invention provides a novel electrical power system for micro-grid and distributed generation systems. The invention provides a common, singular Alternating Current (AC) electrical port for multiple Direct Current (DC) generation sources, DC loads and DC electrical energy storage sources. The invention balances the flow of energy through said storage, load and generation sources to provide a constant voltage and frequency to a micro-grid or a regulated real and reactive power component to an electric utility grid. A centralized controller is capable of commanding bi-directional current flow on each DC port in order to maintain an optimum State of Charge such that the storage medium can service both the utility grid and a micro-grid and dynamically transfer between the two operational modes.


Patent
Dynapower Company Llc | Date: 2016-06-29

A power system having a plurality of power converters coupled together at a point of common coupling (PCC). The power converters are coupled to a load and provide a combined power converter output to the load. A switch is coupled in series between the PCC and an external grid. When the switch is closed, the power system is in a grid-tied configuration and when the switch is open, the power system is in a microgrid configuration. A control system coupled to the power converters enables the switch to open and close in response to a signal received from one or more sensors monitoring the external grid, enables the power converters to operate in a current control mode when the switch is closed, and transitions the power converters from grid-tied mode to microgrid mode and synchronize the power converters such that the converters share the load.


A power system having a plurality of operating modes including an active mode and an active standby mode includes a power converter and a controller the power converter is configured to adapt a power supply to a desired output, and the power converter includes a plurality of semiconductor switches that receive a gating signal when the power system is in the active mode such that the power converter is in a gating state. The controller controls the power converter in the active mode and the active standby mode, and the controller is configured to: while the power converter is synchronized to the grid, determine whether the power system should enter into the active standby mode in which the power converter is in a non-gating state; when it is determined the power system should enter into the active standby mode, control the power converter to be in a non-gating state such that the power system is in the active standby mode.


Trademark
Dynapower Company | Date: 2012-07-05

Inverters; Power inverters.


Trademark
Dynapower Company LLC | Date: 2012-09-04

AC and DC power supplies, rectifiers, electric power converters and custom transformers. maintenance and remanufacture of electrical industrial rectifiers and electrical transformers. custom production and manufacture of electrical industrial rectifiers and electrical transformers. design and engineering services in the field of electrical industrial rectifiers and electrical transformers.


Trademark
Dynapower Company | Date: 2013-08-27

Inverters; Power inverters; Power and deep cycle battery storage systems composed of batteries, charge controllers, and inverters with integrated LED bulbs and LED light fixtures.

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