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This article shows the possibility of more effective control of an asynchronous motor with a squirrel- cage rotor than in the formation of an electromagnetic torque under flux linkage stabilization. A comparative analysis of energy properties of asynchronous machine operation under different kinds of control in similar conditions was performed. One means of control provides the premagnetization of the motor and creates electromagnetic torque upon stabilization of the rotor flux linkage in the first control zone, ensuring a transition into the second zone. In another means of control, in accordance with the developed method of sequential synthesis, premagnetization of the motor is not carried out, and at a low rotor rotational speed creates the electromagnetic torque with a minimum of total loss. When the speed increases, the electromagnetic torque is created under the stabilization of efficiency owing to reducing the reactive power in the function of the rotor-rotation speed. With a further increase in speed, the control is fulfilled with a minimum of reactive power, regardless of the motor load. The energy properties of the motor operation were compared depending on the load and rotation speed under the different means of control. The change in the energy properties of electric-drive operation when generating a motor angular velocity up to double the rate under conditions of limitation of voltage of the power-supply source was considered.

The energy properties of an alternating-current drive are analyzed. The suggested method allows us to compare in an analytical form the energy quality indices of various drives under different means of electromagnetic- torque formation in an electrical machine. Using the relation between power and energy characteristics as functions of the energy state, the energy efficiency, and intensity of energy-conversion processes, as well as the usage efficiency of voltage and power applied to motor windings, are estimated. By means of the constructed relations between quality criteria, the developed method allows one to determine at the stage of design the main properties of an electric drive under static and dynamic conditions. Using energy-state functions and arguments based on means of electromagnetic-torque formation, the method allows us to determine the thermal state at selection or testing of an electrical machine on the basis of heating or overload conditions.

A two-channel system of stabilization of pressure in a fire chamber of a boiler unit is considered. Regulation of pressure is carried out by means of an automated electric drive by changing the speeds of rotation of the smoke exhauster and fan. It is suggested that smoke exhausters (the first channel of regulation) and fans (the second channel of regulation) be controlled. This increases the stability of depression in transitional regimes. It also reduces the time of transients and leads to a more efficient operating regime of the boiler unit. Regulators for the first and second control paths are synthesized. Synthesis is carried out by a modified modal method. The regulator of the first channel contains two components: a regulator of statics and a regulator of dynamics. It works in two regimes: established and transitional. The regulator of dynamics contains the regulator of the second channel only, and it works only in transitional regimes. This strategy allows not interfering with the main process of burning in the fire chamber of a boiler unit with quasi-established regimes. It also reduces the time of transients, when the process burning is not optimal. Regulation systems operating on one and two channels of influences are compared.