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Certain properties of electronic speed control of three-phase AC motors are described, including some properties that can be modified by the user in the field. Emphasis is placed on the closed-loop operation. Test results for one system are obtained. Using a standard control algorithm from the linear control theory, a method of reducing steady-state speed error is demonstrated. No case of instability is found using various starting speeds, final speeds, and controller parameters for test results. Simulation results are obtained for the closed-loop operation using a controller model previously obtained for open-loop operation of this type system. The model contains multiple nonlinearities. No case of instability is found for various starting speeds, final speeds, controller parameters, and motor parameters for the simulation.