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Load Current (load + current)
Selected AbstractsNew structures of vector control systems for permanent magnet synchronous motors with core lossELECTRICAL ENGINEERING IN JAPAN, Issue 3 2010Shinji Shinnaka Abstract This paper investigates and proposes new system structures for vector control of permanent-magnet synchronous motors (PMSMs) with core loss. The proposed vector control systems have the following versatile features. (a) The systems employ the structures allowing control of the stator current through control of the load current. (b) The systems employ unique "stator voltage feedback-use" structures in order to accomplish simply the load current control. (c) The produced torque is directly related to the load current, and the precise torque control can be attained through the load current control. (d) The relation between produced torque and the load current is nonlinear for salient-pole PMSMs similar to the case of no core loss, and a variety of the load current commands can be selected from viewpoints of minimum loss and/or wide speed range drives. The system structures add no constraint to the selection of the load current commands. (e) In addition to the torque control, the speed control can be allowed, where linearity between output of the speed controller and produced torque is kept. The validity of versatile features is verified through the numerical experiments. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(3): 28,39, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20910 [source] A linearly adaptive gate drive technique for light-load efficiency improvement of DC,DC convertersINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 10 2009Pang-Jung Liu Abstract This paper presents a linearly adaptive gate drive technique to improve the light-load efficiency of DC,DC converters. The optimal-driving voltages of the power MOSFETs for reducing gate-driving loss can be well modeled by a linear function of the load current. By scaling the gate drive voltage dynamically with respect to load current, the light-load efficiency can be enhanced. The experimental result shows that the proposed gate drive technique can attain about 9% incremental light-load efficiency enhancement. Copyright © 2008 John Wiley & Sons, Ltd. [source] Trans-admittance control for eliminating the temperature effect of piezoelectric transformer in the CCFL backlight moduleINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 8 2008Yu-Kang Lo Abstract A half-bridge (HB) resonant inverter for driving a cold cathode fluorescent lamp (CCFL) backlight module with a piezoelectric transformer (PT) is analyzed in this paper. The resonant inductance of the HB inverter is expressed as a function of the load current, the load resistance and the PT circuit parameters. Also, the trans-admittance of the PT-CCFL combination network is measured to track the operating frequency for the HB resonant inverter, which may be varied due to the temperature rise of PT. The lamp driving current and power can thus remain almost constant in a wide temperature range. Experiments show that the observed results match the theoretical analyses. Copyright © 2008 John Wiley & Sons, Ltd. [source] Computation of locational and hourly maximum output of a distributed generator connected to a distribution feederELECTRICAL ENGINEERING IN JAPAN, Issue 2 2009Yasuhiro Hayashi Abstract Recently, the total number of distributed generation such as photovoltaic generation systems and wind turbine generation systems connected to a distribution network has drastically increased. Distributed generation using renewable energy can reduce the distribution loss and emission of CO2. However, the distribution network with the distributed generators must be operated while maintaining the reliability of the power supply and power quality. In this paper, the authors propose a computational method to determine the maximum output of a distributed generator under operational constraints [(1) voltage limit, (2) line current capacity, and (3) no reverse flow to bank] at arbitrary connection points and hourly periods. In the proposed method, a three-phase iterative load flow calculation is applied to evaluate the above operational constraints. The three-phase iterative load flow calculation has two simple procedures: (Procedure 1) addition of load currents from the terminal node of the feeder to root one, and (Procedure 2) subtraction of voltage drop from the root node of the feeder to terminal one. In order to check the validity of the proposed method, numerical simulations are performed for a distribution system model. Furthermore, the characteristics of locational and hourly maximum output of a distributed generator connected to a distribution feeder are analyzed using several numerical examples. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 38,47, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20610 [source] Optimal transformations of asymmetric elements in three-phase networksEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 2 2005Zdzislaw W. Trzaska Abstract This paper presents a procedure for optimal transformation of asymmetric three-phase elements. The proposed algorithm is based on the solution of the corresponding Steiner problem and improves the network voltage and current profiles. After identifying the phase quantities, the problem is formulated as a non-linear programming problem of the minimization of the sum of the r.m.s. values of the phase voltages and line currents under some constraint equations. A few test networks are used to verify the effectiveness and accuracy of the method. It is believed that practical applications of the proposed method will enhance the estimation of the phase asymmetry of the three-phase generator voltages and load currents. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||