Energy consumed by trams is studied in many papers, with a wide diversity of approaches regarding how to model and solve this problem. A novel approach to modeling the power consumption of trams is presented in this paper. To identify the unknown parameters influencing the rolling resistance force acting on the tram, it is necessary to measure the power consumption and speed of a single tram (or multiple trams if there are different car types in operation). The developed model of the tram is calibrated with data from the Sarajevo tram system. Simulation results are compared with measurements and a good correlation was obtained. The power consumption model of the tram with identified parameters can be further used to develop a framework for the power consumption estimation of the traction substation.

This paper presents a nonlinear flatness-based approach for simultaneous control of the active and reactive power of a self-excited induction generator (SEIG) in wind energy conversion system (WECS). The proposed flatness-based controller (FBC) generates the control outputs which are applied to the current-controlled voltage source inverter (CC-VSI) and gearbox. A differential flatness theory is exploited to derive the flat outputs of the SEIG generator as well as to prove that the overall system is differentially flat one. This enables a transformation of this system into the linear canonical (Brunovsky) form and facilitates the design of the controller. The design methodology of the flatness-based controller relies on using a flux-based mathematical model of the SEIG in rotating $dq$ reference frame. The set points of the active and reactive powers are converted into system variables using a high-level reference trajectory generator (HLRTG). The proposed approach provides an efficient decoupled control for both the active and reactive power of the SEIG generator. The efficiency of the proposed control system is confirmed through simulation experiments.

This paper describes the transient characteristics and control of the output DC voltage of a stand-alone switched reluctance generator (SRG). A mathematical model of switched reluctance machine (SRM) is developed and implemented in Matlab/Simulink software. The mathematical model is verified experimentally. The robust controller based on the discrete-time sliding mode control (DT-SMC) technique is proposed for the SRG voltage control. The robustness is achieved using the disturbance estimator. The proposed control technique was implemented through simulations on a three phase 12/8-pole SRG with a variable speed and load. The proposed DT-SMC based controller is compared with a standard PI controller. Obtained results show the effectiveness and quality of DT-SMC based voltage control technique for the SRG.

This paper presents a nonlinear flatness-based control (FBC) approach for a full-order doubly fed induction generator (DFIG) in the wind turbine system. Flat outputs of the DFIG and the FBC controller are derived using differential flatness theory. The proposed approach ensures an efficient decoupled control for both active and reactive powers of the DFIG. Also, it provides a smooth trajectory tracking in the start-up and the rest to rest modes without any saturation. Therefore, the system satisfactory operates at a variable speed of the rotor with an effective active/reactive power tracking. The variable rotor speed represents a perturbation caused by changes in the wind speed or different wind energy capacity. The requirements on the active and the reactive power are converted into system variables using a high-level reference trajectory generator (HLRTG). The effectiveness of the proposed system is verified by simulations.

The digital speed control systems of a DC motor are treated in this paper. The parameters of DC motor were not known, so that the parameter estimation and model identification is carried out first. Two control systems are considered: a classical discrete PI controller and a discrete-time sliding mode controller. Problems of robustness to matched parameter uncertainties and outer disturbances were addressed by comparing PI controller outputs with DT-SMC controller with disturbance compensator. These control systems were compared in MATALB/Simulink, and on the laboratory setup using three characteristic scenarios. At the end, experimental results are compared with the results obtained by simulation.

A new design of a digital control system for the grid-connected doubly fed induction generator is described in this paper. A discrete-time state-space model of the controlled system is obtained in the stator stationary reference frame. Using this model, a discrete-time sliding mode based control system is designed. Its tasks are the grid synchronization and the direct power control. The discrete-time equivalent control method is applied, and the control vector is calculated from the samples of voltages and currents. The control vector is converted to a switching sequence in a power converter using the space vector modulation. The modulation period is equal to the sampling period. A disturbance compensator is designed to eliminate the influence of the discretization effect and model uncertainties. In this way, a robust control system with a constant switching frequency is designed. Its digital hardware implementation is simple. The performance of the designed control system is tested on a simulation model.

This paper describes fast analytical model for computation of the switched reluctance machine's (SRM) nonlinear magnetization characteristic and torque lookup table. The flux-tube and the gage-curve methods are used to develop this fast analytical model. Presented model is used for computation of the magnetization characteristic and torque lookup table of three and four-phase SRMs. The simulation results obtained using proposed analytical model are compared to the results of magnetostatic finite-element analysis (FEA) for a three-phase 12/8 SRM. Experimental verification of the analytical model is also presented for the same 12/8 SRM prototype.

The effects of magnetic circuit geometry on torque generation of switched reluctance motor with higher number of rotor poles are investigated in this paper. Specifically, the torque generation of novel switched reluctance machine with 8 stator and 14 rotor poles (SRM 8/14) is explored. A few suggested values of design ratios are derived for this novel SRM. The machine characteristics are computed using two-dimensional finite element method (2-D FEM).

This paper presents a novel analytical model for computation of the switched reluctance machine's (SRM) nonlinear magnetization characteristic and torque lookup table. The flux-tube and the gage-curve methods are used to develop the novel analytical model. Presented model is used for computation of the magnetization characteristic and torque lookup table of three and four phase SRMs. The simulation results obtained using proposed analytical model are compared to finite-element method (FEM) results. Experimental verification of the analytical model is presented for an 8/6 SRM.

Two methods of the multi-objective design optimization of switched reluctance motor with 8 stator and 14 rotor poles (SRM 8/14) are compared in this paper. The first optimization method is based on using the results of Two-Dimensional Finite Element Method (2D FEM) parametric analysis of SRM 8/14. Augmented Lagrangian Genetic Algorithm (ALGA) and 2D FEM are coupled in the second optimization process. The optimization objectives are to minimize torque ripple and maximize average steady-state torque, torque factor, torque quality factor, torque density and losses factor. The optimization variables are the stator and rotor poles arc angles, the taper angles of the stator and rotor poles, stator yoke radius, rotor yoke radius, and stator coil height.

This paper presents a study on output voltage of a self-excited 8/6 switched reluctance generator (SRG). A nonlinear Matlab/Simulink® model of the machine has been developed and used to determine dynamic behavior of SRG. SRG has been simulated in open loop with fixed conducting angle strategy in low speed range, with variable turn-on angle being basic excitation parameter. A relationship between output voltage and turn-on angle has been established. Load current is found to have significant influence on output voltage and stability. Boundaries of stable operation in open loop with respect to load current are determined. A proposed operation mode has been presented and tested in simulation and validated through experimental results.

Analysis and static characteristics optimization of the new four-phase switched reluctance machine with 8 stator and 14 rotor poles (SRM 8/14) is presented in this paper. This new configuration with higher number of rotor poles is considered to be suitable for high performance electric vehicle (EV) drives. Optimization variables were the stator and rotor poles arc angles, and the taper angle of the stator poles. The optimization objectives were to minimize torque ripple and maximize torque factor, torque quality factor, torque density and losses factor. Calculation of the static characteristics and optimization is performed by a combination of high-level technical computing language Matlab and 2D FEM software Ansoft Maxwell. The genetic algorithm (GA) is used for minimizing a weighted sum of five normalized objectives.

In this paper a comparative evaluation of three, four-phase, switched reluctance machines (SRMs) is presented. Configurations 8/6 and 8/10 are conventional SRMs with standard relationship between number of stator and rotor poles. Configuration 8/14 has number of rotor poles calculated according to the new pole design formula introduced recently. Design considerations for novel SRM 8/14 are given. Static characteristics of SRM 8/6, SRM 8/10 and SRM 8/14 are investigated using finite element analysis (FEA). Comparison of these characteristics is given regarding several criterions for torque profiles evaluation and torque density assessment.

Magnetic circuit design of wound rotor low-voltage three-phase synchronous generator for autonomous operation is presented in this paper. The Maxwell software based on two-dimensional finite element method (2D FEM) is used to study the performance of the synchronous generator in specified static operating regime. Two machines with different configurations are analyzed. These machines are characterized by the same stator and rotor external dimensions and used materials. Moreover, stators of all machines are exactly the same while the rotor magnetic circuit structures and excitation windings are different. Calculated characteristics and their comparisons are presented and discussed. Some characteristics of prototype, which is currently under construction, are given.

The digital control of speed of a permanent magnet DC motor based on a digital computer is analyzed in this paper. Datasheet information about the DC motor was initially unknown. Therefore, the parameter identification and parameter estimation of the motor was done. A type of PID controller, which parameters were optimized (PI), was used in process of controlling the speed of the motor. DAQ acquisition card was used for the purposes of motor's parameter identification and realization of computer control of motor speed in closed feedback loop. Manipulations with the same DAQ card were done using Matlab/Simulink software package. Experimental results were compared with the results obtained by simulation.