A combined circuit for single-phase switching of a voltage-controlled induction electric drive with a three-phase motor is proposed for pump plants, which allows to obtain satisfactory operational and power characteristics in starting and operating modes at a constant capacitance of a phase-shift capacitor. It is proved that it is possible to reduce power losses due to the use of different switching the circuits of the motor windings at different speed control ranges as compared to schemes with a constant structure. References 9, figures 5.

Introduction. Single-phase power supply of induction motors is used in public utilities, in microclimate control systems for remote agricultural consumers, in water supply and pipeline transport systems, etc. In practice, there is the use of induction motors with three-phase stator winding in the conditions of single-phase power supply. Starting and operating capacitors are used to enable their operation when powered by a single-phase network. Problem. There are many fairly accurate methods for calculating the characteristics of an induction motor in asymmetric, including single-phase, modes of operation, but they are based on differential equations, which does not allow to obtain analytical expressions for preliminary analysis and synthesis of such systems. Goal. The purpose of this article is to develop the analytical method of definition of electromagnetic torque and energy losses of voltage-regulated three-phase induction motors working according to the scheme of single-phase inclusion with the phase-shifting capacitor. Methodology. The method is based on the theory of symmetric components and analysis of replacement schemes of induction machine in motor and generator modes. Results. The analysis of the obtained data shows that at a constant value of the phase-shifting capacitor capacity induction motor working according to the scheme of single-phase inclusion has a minimum of losses at one value of slip at different values of supply voltage. Therefore, if you keep this slip constant when the load changes, you can achieve a mode of minimizing losses at a constant value of the capacity, optimal for this slip. This shows that the thyristor voltage regulator can be used as an energy-saving element under variable load, while the capacitance of the phase-shifting capacitor can remain constant when changing the load in a wide range provided that this slip is stabilized. Originality. The developed method allows to obtain analytical expressions for comparative analysis of electromagnetic torque and energy losses of three-phase induction motors powered by a single-phase network at different values of the capacity of the phase-shifting capacitor, supply voltage for different variants of schemes for including three-phase induction motors in a single-phase network. Practical value. Based on the developed analytical method, the optimal parameters of phase-shifting capacitors and rational schemes for including three-phase induction motors in a single-phase network can be determined.

Purpose. The purpose of this article is to provide a comparative analysis of influence of the phase controlled single-phase induction electric drive coordinates harmonic components on the operational characteristics of the electric drive under different variants of the power part. Methodology. A mathematical model of the combined circuit of a single-phase induction motor with a variable structure of the power part and a constant capacitance of the phase-shifting capacitor is generalized for various variants of connection of the power part of the electric drive with thyristor control. The comparative harmonic analysis of currents and torques of the motor is carried out and the factors influencing the energy efficiency of the electric drive at different circuit of connection of the power part are determined. Results. The analysis of the obtained data shows that the series-parallel circuit has the best harmonic composition of the consumed current in practically the whole range of changes of load torque and speed. The main effect on the loss increase is due to the asymmetry of the currents in the series-parallel circuit and the higher harmonics in the Steinmetz circuit. Originality. For the analysis of the processes in these circuits, a generalized thyristor control single-phase electric drive mathematical model, in which the structure of differential equations remains unchanged regardless of the circuit of connections of the power part, is developed. Practical value. Using of the combined circuit of single-phase switching on of a three-phase induction motor allows to use a constant capacity in the range of slips from nominal to critical without exceeding the nominal losses. References 4, tables 1, figures 5.

The peculiarities of the modes of operation of the hydraulic drive of translational motion with throttle speed control, in which the asynchronous motor with single-phase power supply is used as the primary actuator. A combined circuit of such an actuator with a phase-shifting capacitor is proposed, which allows to increase its energy efficiency in the forward and reverse modes of the hydraulic rod when changing the degree of opening of the hydraulic control valve by switching power circuits and using voltage regulation. References 10, figures 6, table 1.

On the basis of the method of symmetric components, an analytical method is proposed for calculating the coefficients that determine the relationship between the components of the positive and negative sequences of the parameters of the operating mode of an induction motor and the parameters of its power supply for some circuits for the inclusion of voltage-controlled three-phase induction motors with phase-shifting capacitors powered by a single-phase network. On the basis of this technique, the optimal parameters of phase-shifting capacitors can be determined and rational schemes for connecting three-phase induction motors to a single-phase network can be selected. Ref. 7, fig. 3, tables 2.