Steady State Analysis Of Single Phase IPM Motors By D-Q Harmonic Balance Method

A concise steady-state analysis of a single-phase line-start permanent magnet (SPLSPM) machine is conducted from a developed d-q model using the d-q harmonic balance technique. The d-q model was developed in rotor reference frame from a phase variable model of the machine. SPLSPM whose performance indices were characterized by high torque ripples has detailed analysis docile mostly in computer simulations quite unlike the three-phase types. The main cause is not far-fetched, it was due to nonexistence of precise mathematical model in d-q rotor frame of the motor due to the unbalanced field winding, the rotor saliency and the presence of the capacitor in the auxiliary windings. Even after model has been developed, the simple traditional procedure of setting all time varying component to zero for steady-state analysis fails because the rotor position dependence on the inductance expressions could not be eliminated. The d-q harmonic-balance technique was then applied. An important feature of the harmonic balance technique was that it decoupled all equations to simple sine waveforms in a style that resembled Fourier series. Results yield torque pulsation, current and load characteristics in the steady state.

Double Sliding-Surface Multiloop Control Reducing Semiconductor Voltage Stress on the Boost Inverter

Sliding-mode control (SMC) has been successfully applied to boost inverters, which solves the tracking problem of imposing sinusoidal behavior to the output voltage despite the coupled or decoupled operation of both boost cells in the converter. Most of the results reported in the literature were obtained using the conventional cascade-control structure involving outer loops that generate references for one or two sliding surfaces defined using linear combinations of inductor currents and capacitor voltages. As expected, all proposed methods share the inherent robustness and insensitivity to the uncertainties of SMC, which are the reasons why one of the few comparison criteria between them is the simplicity of their implementation that is evaluated according to the required measurements and mathematical operations. Furthermore, the slight differences between the obtained dynamic performances do not allow a clear distinction of the best solution. This study presents a new SMC approach applied to a boost inverter in which two boost cells are independently commutated. Each of these boost cells integrates an outer loop, enforcing the tracking of harmonic-enriched waveforms to the capacitor voltage. Although this approach increases by two the number of measurements and requires multiloop controllers, it allows effective alleviation of the semiconductor voltage stress by reducing the required voltage gain. A complete analytical study using harmonic balance technique allows deducing a simplified model allowing to obtain a PI controller valid into to the whole set of operation conditions. The several simulation results completely verified the potential of the control proposal and the accuracy of the employed methods.