Carles Jaen

Voltage-Balance Compensator for a Carrier-Based Modulation in the Neutral-Point-Clamped Converter

This paper presents an optimal voltage-balancing compensator for a specific modulation technique applied to a neutral-point-clamped converter. The technique uses two modulation signals per phase, and it is called double-signal pulsewidth modulation. It completely eliminates low-frequency oscillations in the neutral-point voltage. However, it does not provide natural voltage balancing; therefore, a compensation loop is required. The proposed control generates a feedback compensation signal that correctly modifies the three-phase modulation signals. The optimal compensation signal is calculated by a dynamic limiter according to the intrinsic limitations of the system related to the variability range of the modulation signals. It significantly improves the voltage balancing under all operating conditions of the converter. In addition, this compensation strategy does not increase the switching frequencies of the power devices. The algorithm is tested and verified using both simulation and experimentation.

Overview of maximum power point tracking control techniques used in photovoltaic systems

Nowadays power supply systems based on photovoltaic cells have two main drawbacks even the primary energy is free and renewable. They are production cost and efficiency. In order to increase their efficiency should be interesting that the energy transfer between cells and load was done at maximum level. In this paper an overview of control techniques oriented to obtain the maximum power point tracking (MPPT) is presented. Then a specific method is fully developed and finally, some simulation and experimental results are also included.

A Linear-Quadratic Regulator with Integral Action Applied to PWM DC-DC Converters

Averaging techniques have been widely applied to model PWM power electronic converters. The averaged models obtained by using this technique are very useful for the simulation of the systems as well as for the design of controllers. In this work, some general considerations about linear-quadratic regulators (LQR) are made. Then, an LQR is designed and applied to the particular case of a DC-DC buck converter. Some simulation and experimental results show very good performance of the system under start-up and transient events

On the use of sun trackers to improve maximum power point tracking controllers applied to photovoltaic systems

Nowadays power supply systems based on photovoltaic cells have two main drawbacks, even the primary energy is free and renewable. They are: production cost and efficiency. In order to increase their efficiency, it should be interesting that the energy transfer between cells and load was done at maximum level. In this paper the use of a sun tracker system is presented as an additional improvement applied to a photovoltaic installation that works under a maximum power point tracking (MPPT) control technique. A 50W-prototype has been assembled. Some experimental results are also included in order to validate the whole system.

Power losses calculation methodology to evaluate inverter efficiency in electrical vehicles

Nowadays, electrical vehicles (EVs) are of special interest and fuel engines are starting to be substituted by electrical motors. Besides the batteries and the motor, the power electronic devices are important parts in an EV, especially the inverter. This ac/dc power converter drives the electrical motor. Several tools may be needed to achieve an optimal design of the inverter. This paper presents a simplified methodology to estimate power losses in a two-level inverter made up with isolated gate bipolar transistors (IGBTs). This methodology is based on the IGBT manufacturer datasheet; therefore, the knowledge of internal parameters used in other more complex methodologies is not required. The model is implemented in Matlab-Simulink and allows simulation of different power devices, modulation techniques, and operating conditions very easily. Some results are obtained and validated with commercial electronic software and also with the simulation tool Semisel, provided by the manufacturer of the IGBTs.

Optimal Voltage-Balancing Compensator in the Modulation of a Neutral-Point-Clamped Converter

This paper presents an optimal voltage-balancing compensator for a particular type of modulation technique applied to the neutral-point-clamped converter. This modulation technique is able to completely eliminate low- frequency voltage oscillations in the neutral point. However, its dynamic for balancing voltages on the dc-link capacitors is slow. The proposed compensator generates an optimal offset for the modulation signals that improves significantly the voltage balancing issue for any operation condition of the converter. Furthermore, this strategy does not increase switching frequencies of the devices. The algorithm is tested and verified by simulation and experiment.

Adaptive Model Applied to PWM DC-DC Converters Using Averaging Techniques

An adaptive model applied to PWM DC-DC converters is presented in this paper. Parasitic resistors have been considered in the converter. The coefficients of the state-space matrices, which depend on the parameters of the circuit, are calculated on-line. In the proposed method, the state vector variables should be sampled in real time. Then, the coefficients of state-space matrices are estimated by means of a simple matrix calculation. The values of the components of the averaged circuit can also be calculated from the matrix coefficients. Therefore, the changes in the values of the parameters of the circuit are quickly updated in the averaged model. As a result, robust control strategies can be implemented by using these models. In this paper, the method is applied to a buck-boost converter. Some simulation results are included in this work to validate the procedure. The estimated matrices coefficients match very well the expected values

Sliding Mode Controller Applied to PWM DC-DC Converters Based on an Averaged Model

A modeling methodology applied to PWM DC-DC converters is presented in this paper. Parasitic resistors have been considered in inductor and power supply. A generalised equivalent circuit based on averaged variables is obtained for the basic structures of DC-DC converters. This circuit and the associated model are valid for continuous conduction mode and discontinuous conduction mode. This contribution contains expressions to detect changes of the converter operation mode and to estimate the value of the diode duty cycle operating under discontinuous conduction mode. A sliding mode controller for the regulation of the output voltage has been designed in terms of averaged state variables and converter parameters. The procedure is applied to a 100 W Buck converter prototype. Simulations and experimental results are presented.

Control to reduce leading current in a Shunt Hybrid power filter

The main drawback of Shunt Hybrid Filters is the need of leading current injection. This paper describes a strategy to reduce the leading current in a three phase four wires LC coupled parallel hybrid filter for harmonics cancellation. Simulation and experimental results are given to show the behavior of the system.

Permanent Magnet Synchronous Motor Sensorless Control using pulse test shorter voltage Matrix Converters vectors

This paper deals with the sensorless field oriented control of permanent magnet synchronous machines using test matrix converters voltage vectors. The novelty of this paper is the fact that a matrix converter is used instead of the conventional voltage source inverter and that the uncommon shorter matrix converter vectors are used as a test signals for tracking the machinepsila saliency (difference between Ld and Lq). Sensorless field oriented control scheme is detailed and position signals are calculated to properly estimate the permanent magnet position. Finally, some simulation results are presented, confirming the proper performance when sensorless control at low speed reversal and load impact at zero speed.