The time and the space waveform of electric and magnetic magnitudes of AC machines are a non-sinusoidal including the case of powered by the grid. The reasons of the deformation are in the actual design layout of electrical machines, at various asymmetry generated in the production or as a result of failures in electric, magnetic and mechanical parts of the machine. The rotating electric machine may produce several types of harmonics. Some may be suppressed by construction modifications (skewing slots, magnetic conducting slot wedges, the air gap increasing and the winding pitch reducing). Many of these modifications are often not each other exclude or inconsistent with other requirements of the machine. Therefore, these harmonics cannot be completely suppressed. The possibility way how to reduce harmonics of induction machine using slot wedges optimization is presented.

The paper describe design of battery powered drive unit intended for tree harvester application. Battery powered hybrid drive unit in working machine is currently quite common (1). The battery capacitance is not sufficient to realize harvester as an only battery powered machine. Nevertheless, the hybrid concept of electric drive is useful to cover short power peaks demands during the harvester standard operation. In harvester application there is typical high ratio between short power peak and average demanded power. The development in batteries increases of significance and possibility of electric drive utilization in three harvesters.

The paper describes a new universal infinitesimal method which enables the analysis and synthesis of arbitrary AC motor windings. The method is based on the notion of the local angular density of conductors n(α) = dN(α)/dα. It will be proved the proportionality B(α) ≈ ∫ _n (α)dα for the magnetic flux density in the air gap. The function n(α) can be arbitrary, i.e. of continual or impulse character. In a special case, when the function n(α) is given in the form of Dirac impulses, this new method generates the same results as the classical method. Spatial functions n(α), B(α) may be evolved into Fourier series. The first harmonic components of these functions serve to the electromagnetic design of the induction or synchronous motor. Higher harmonic components serve to the calculation of the differential leakages. New method enables to calculate linkage fluxes, and self as well as mutual inductances of any stator and rotor windings, too.

A derivation of the dynamic model of a medium voltage vacuum circuit breaker and induction motor in space vectors in coordinates $\alpha \beta 0$ allow us to model switching transients in various dynamic states of the motor. In the case of the Clark transformation, the corresponding numerical integration technique can be selected including variable time-step integration techniques to avoid numerical instabilities due to the stiffness of the system. Assymetrical operations such as switching cause the power system to become unbalanced and the transformed equations $\alpha$, $\beta ,$ and $0$ are not uncoupled. Therefore, it is necessary to derive a coupling matrix between circuit breaker voltages and currents in the coordinate system $\alpha \beta 0$. The subject of our interest is switching overvoltages that arise when turning off small inductive currents by a vacuum circuit breaker. When deriving the model of a vacuum circuit breaker, all its properties encountered during this action are taken into account, i.e., current chop, virtual current chop, dielectric barrier in the circuit breaker and its recovery rate, and the ability of the vacuum circuit breaker to extinguish high frequency currents. Simulation results are compared with the measured results on a medium voltage motor as well as with the simulation results of the mathematical model of the test circuit according to IEC 62271-110 resolved using the nodal method (EMTP algorithm). Models are implemented in the MATLAB/Simulink programming environment.