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Two-phase residential installations have become very common in Ecuador since different policies prompt the users to replace gas stoves and water heaters by electric appliances. The addition of a second phase to the originally installed single-phase wiring is required to obtain 220Vrms. This fact carries an intrinsic unbalance since single- and two-phase loads coexist. In this paper a topology for...
The maximum speed of ultra-high speed switched reluctance machines (SRMs) is limited by commercial rotary encoders due to mechanical considerations. In this paper a novel direct position control for ultra-high speed SRMs based on non-contact optical sensors is proposed. The paper presents the use of reflective optical sensors to detect the relative position between the rotor and the stator so as to...
This paper evaluates the use of a Photo Voltaic (PV) parameter estimation method based on implicit optimization algorithms and its use in power controller strategies by explicit model representation obtained with First and Second Order Approximation Models (FOAM, SOAM). An explicit function linking voltage, current and power of PV) cells is presented using the parameters obtained during the implicit...
The use of a second phase in household electric wiring is a requirement for feeding heavy loads in those countries using 100 ~ 127 Vrms as the standard voltage. One problem of this wiring is the unbalance between phase currents since single-and two-phase loads coexist. A back-to-back topology is proposed for an active power filter to add it the ability of active power compensation. The presented topology...
This paper presents a direct and approximate model of PV cell that considers variations in surrounding temperature and solar irradiation. The method uses the one diode model approximation and PV parameters from the manufacturer's data, together with a selective (first or second order) Taylor series. In this paper, a recursive solution for the PV cell's complete implicit model equations supplies data...
The complete design of the current control loop for single-phase inverters connected to weak grids is presented. The problems associated to the design of current control loop when highly distorted grid voltages are present and LCL filters are used to couple the inverters to the grid, are analyzed. Fourier coefficients decomposition is used to obtain an ahead-of-time version for the nonideal voltage...
Grid-connected inverters are an essential component of modern photovoltaic systems. They allow the users to obtain a faster recovery of the investment given their capability of injecting the excess of generated energy to the grid. Proper operation of the inverters requires a current loop with the capability to deal with eventually distorted grid voltages and with LCL coupling filters. This makes the...
A case study for designing the current control loop for single-phase inverters connected to weak grids is presented. The problems associated to the design of current control loop when highly distorted grid voltages are present and LCL filters are used to couple the inverters to the grid, are analyzed. Fourier coefficients decomposition is used to obtain an ahead-of-time version for the nonideal voltage...
This paper proposes an improved signal-injection-based stator-winding thermal-monitoring method for field-oriented-controlled (FOC) induction motors. In this method, stator-winding DC resistance is normally used as a direct indicator of winding temperature, and is obtained from injected DC currents and voltages in the motor winding. Conventionally, however, implementation of this DC-injection method...
This paper investigates the use of fractional order PIα controllers, applied to inverter driven induction machines. Fractional order controllers provide additional degrees of freedom for their design, and the non-linearity introduced by the fractional part of the controller provides better tuning for the operation of the controller. In this work a fractional PI controller is applied to the current...
In this paper an active power filter is presented based on a multilevel converter. The active power filter is intended to be used in domestic applications where reactive power compensation in two-phase networks is required. An innovative technique to balance the DC bus voltages of the power converter capacitors is proposed and also an estimation algorithm for those voltages is developed, allowing...
This paper proposes a control scheme for a wind turbine using a DFIG electromechanical converter, implemented through an NPC three-level back to back converter, that keeps a unitary power factor injection to the grid and maximizes the energy harvested from wind, using a maximum power point tracking algorithm (MPPT). A predictive direct power control (DPC) strategy drives the grid-side converter, to...
This paper presents the use of a training algorithm based on a Lyapunov function approach applied to a stator current controller based on a state variable description of the induction machine plus a reference model. The results obtained with the proposed controller are compared with a previously reported method based on a Nonlinear Auto-Regressive Moving Average with eXogenous inputs (NARMAX) description...
The closed-loop speed control for a high speed switched reluctance machine (SRM) is studied in this paper. A speed-and-current dual closed-loop control scheme is selected for speeds as high as 50 krpm. The novelty of the proposed control method is inclusion of the inductance profile selection for a flux-bridge rotor. In this paper, the nonlinear SRM is modeled in a linearized form by small signal...
The switched reluctance machine (SRM) is a reliable machine and has received much attention in recent years. The SRM electromagnetic design is studied in this paper. A novel design method using current-fed excitation is proposed. It is applicable to a wide variety of SRM design cases, and efforts are made to reduce the computational costs. This method is used to optimize the SRM's geometry parameters...
A predictive control scheme to control the phase currents of a three-phase power converter coupled to the electric grid by means of an LCL network is developed. This kind of coupling offers several advantages when compared to pure inductive coupling networks, namely a greater attenuation of switching harmonics and a smaller size. Equations that model the behavior of the current through the LCL network...
This paper proposes an approach for modeling a Switched Reluctance Machine with fuzzy logic. The proposed model is verified under a Model Reference Adaptive Control scheme. Calculating Fuzzy Inference Systems instead of the nonlinear terms of state equations decreases the model complexity and computing costs, which is important for the MRAC scheme, and provides a mathematical model for adaptive control...
This work presents the design and development of a three-phase multilevel hardware platform for applications in power electronics. The emphasis of the proposed converter is in its flexibility to allow rapid set-ups of different experiments typically required in power electronics teaching and research. The proposed converter uses a cascaded H-bridge topology whereby multilevel operation with up to...
This paper proposes a new positive and negative sequence detector for fast system's protection. The proposed detector scheme uses Savitzky-Golay filters, to get a filtered version of the signals' time derivatives. A comparison, using simulations and experimental tests, of the proposed detector and of a second order generalized integrator (SOGI) based detector, shows the advantages of the former.
A new topology for a two-phase shunt active power filter using a voltage source converter is proposed. The converter is controlled with a predictive control algorithm based in a discrete mathematical model of the system which allows to minimize the quadratic error between the lines currents and the reference currents. The whole system is tested with simulations and with a prototype experimental setup,...
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