Abstract-This paper examines a shortcoming of the classical phasor diagram of a salient-pole synchronous machine based on the well-established two-reaction theory. Unlike in the phasor diagram of a smooth-air-gap machine, it is not possible to readily identify the internally-developed electromagnetic power of a salient-pole synchronous machine from this phasor diagram. By de ning new machine reactances, a single equivalent circuit of a salient-pole synchronous machine is proposed together with a phasor diagram where the internally-developed electromagnetic power is made apparent. The revised two-reaction theory is illustrated using the mathematical model of a two-phase salientpole synchronous machine whose equations are manipulated using complex space vectors instead of traditional matrix transformations.

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The more-electric trend is there in almost all the corners of the automotive industry. The same trend is followed by the maritime transportation industry as well and as a result, conventional mechanical transmission based propulsion systems are gradually being overtaken by electric power transmission based propulsion systems. An azimuth thruster driven by an electric motor is a common configuration found in modern electric propulsion systems. Due to the tight speed control and stiff drivetrain in these propulsion systems load transients easily get propagated into the dc-link of the motor drive and subsequently into the upstream power bus as well. These transients can cause disturbances to the other loads connected to the power system. In the worst case, stability of the shipboard power system gets affected by the transients. This paper proposes to use the capacitor-clamped inverter based motor drive itself to absorb such transients and thereby prevent the propagation into the power bus. The efficacy of the proposed concept is verified through computer simulations. Simulation results show that the capacitor-clamped inverter is capable of absorbing load transients without passing them to the upstream power bus.

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