The present paper describes an angle and speed estimation algorithm suitable for the control of a wound-field synchronous starter/generator (S/G) without position sensors for aircraft engine starting applications. The proposed control strategy is based on the injection of a high-frequency voltage signal and the subsequent demodulation of the resulting high-frequency stator current components. The coupling due to high-speed operation that degrades the estimation accuracy of similar algorithms based on signal injection is taken into account. Modeling of the machine response to a high-frequency voltage signal injected into the estimated d-axis is presented, also considering the influence of damping circuits both on the d- and q-axis. Local asymptotic stability of the proposed observer is also demonstrated. Through extensive experimental results, the proposed control technique is shown capable of guaranteeing full-torque sensorless operation at zero speed and sustained operation up to engine ignition speed.

This paper presents a quantitative performance analysis of a conventional passive cell balancing method and a proposed active cell balancing method for automotive batteries. The proposed active cell balancing method was designed to perform continuous cell balancing during charge and discharge with high balancing current. An experimentally validated model was used to simulate the balancing process of both balancing circuits for a high capacity battery module. The results suggest that the proposed method can improve the power loss and extend the discharge time of a battery module. Hence, a higher energy output can be yielded.

A simple analytical technique, which uses readily available datasheet parameters, is developed to model the low-current switching characteristics of insulated-gate bipolar transistors (IGBTs). Simulation and experimental results obtained using three differently rated inverters are presented to demonstrate the accuracy of the technique. The model is applied to compensate the nonlinear distortion, introduced by IGBT switching action in a three-phase inverter, of high-frequency injected voltage and current signals used in sensorless control of a permanent-magnet brushless ac machine. Experimental results show that the compensation technique improves rotor position estimation by up to 20° electrical.

This paper presents the development of a hardware-in-the-loop (HIL) simulation system that facilitates the experimental testing of cell balancing circuits by emulating energy storage components. The system is developed with four cell simulators, each of which can emulate the battery voltage with the capabilities of sourcing and sinking current for the cell balancing circuit being tested. The cell simulator can also operate in battery testing mode for characterizing the behavior of a battery. One Li-polymer cell has been characterized using the cell simulator and a battery model has been built by the extracted parameters from the measurements. An active cell balancing experiment was conducted with a real 4-cell Li-polymer module followed by the same experiment using the HIL simulation system to emulate the Li-polymer cells based upon the method described in this paper. With the real battery module having a 9.4% SOC deviation initially, the final SOC deviation is reduced to 1.0% and the balancing time is 51.4 min. The HIL simulation gives very close results where the final SOC deviation and the balancing time are 1.2% and 52.0 min, respectively. The results demonstrate that the system can provide representative results for testing cell-balancing circuits with minimum resources and time.