Abstract: A method and system for determining an inductance value of an inductive element are presented. The method includes energizing the inductive element using an N-pulse AC to DC converter in electrical communication with the inductive element and an AC source. The method further includes determining at each of a plurality of periodic time intervals an inductive element voltage value, an inductive element current value, and an equivalent source phase angle. An Nth harmonic impedance squared value is then determined for the inductive element using the inductive element voltage and current values and the equivalent source phase angles. The inductive element inductance value is then calculated using the Nth harmonic impedance squared value and an AC source frequency value.

Abstract: A drive system comprises a rotor position and velocity tracker adapted to decouple fundamental frequency effects of a zero sequence signal of an induction machine from the zero sequence signal and to use a resulting error signal to estimate a position and a velocity of a rotor of the induction machine.

Abstract: A method and system for determining zero current level occurrences in a reversible power converter without requiring additional component complexity and costs. A digital controller selectively determines the line to line voltage for the most recently fired thyristor pair. The selected line to line voltage is identified as the bridge reconstruction voltage and is compared against the actual bridge output voltage for the conducting bridge. The difference between the two voltage signals is identified as the bridge error voltage and the sign of its magnitude is indicative of a load current zero level occurrence. A zero current level occurrence happens whenever the bridge error voltage drops below zero. This indication is positive and substantially instantaneous and safely enables the reversal of power flow without the risk of line faults due to cross-bridge short circuits.

Abstract: A power electrical system is disclosed to connect a microturbine and an electrical machine to electrical power sources and a load. The invention permits the microturbine to be started using an external DC power source and/or an external AC power source. DC power is converted to AC power by means of a buck-boost chopper, DC bus and a DC-to-AC converter. AC power, from the AC power source, is converted to frequencies and voltages suitable to start a microturbine by a pair of DC-to-AC converters and the DC bus. The frequency and voltage levels of the AC power are gradually increased to accelerate the microturbine to startup speed. Once the microturbine is started, the external power sources are disconnected, and the DC bus and the DC-to-AC converters produce output AC power at a voltage level and frequency to match an electrical load.

Abstract: A method and system for compensating for voltage notches in phase locked loop (PLL) control devices. A bridge firing controller receives signals representative of two of the line to line voltages received by the bridge. The controller includes a PLL synchronizing tool which receives the line to line voltage signals and generates a synchronizing phase error signal for aligning the phases of the two input signals. The controller, for a predetermined period following bridge firing, determines whether a voltage notch has occurred. If so, the controller substitutes model control signals for actual control signals so as to reduce the effect of the notch on the generated phase error signal used for synchronization. If not, the controller continues to use the actual control signals to generate the phase error signal. Once the predetermined period has expired, the controller utilizes the actual control signals to generate the phase error signal.