The article substantiates the necessity of identifying the dynamics of asynchronous electric drives with frequency control. It is proposed to use nonlinear transfer functions and the formula of a family of frequency responses of an electric drive, depending on the frequency of the stator voltage and slip. Experiments and simulations confirming theoretical conclusions are presented. The frequency responses of the drive of the stand calculated by the proposed method allowed to explain those problems of frequency control that were not explained by traditional methods - analytical, vector diagrams, substitution schemes, etc. This same technique allowed us to formulate a structural correction of the asynchronous electric drives. In contrast to the previously published research materials of asynchronous electric drives, a detailed qualitative analysis of the obtained nonlinear frequency responses and the interrelation of these characteristics with experimental results is shown for the first time in the article.

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The dynamics identification of asynchronous electric drives via frequency response

The article presents the results of a study into the asynchronous electric drive with positive dynamic feedback on stator current. The experiments were carried out with external analog processing and generating a control signal unit and the programmable logic controller. Correction algorithms are based on previously conducted theoretical studies and computer modeling. The resulting diagrams of transient processes confirm that the proposed correction in static modes is much more efficient than the traditional IR-compensation, and the reaction to the load sketch exceeds the closed-speed electric drive by dynamic characteristics. The ndustrial equipment by Schneider Electric — Frequency converter ATV71 and PLC Modicon TM241 — was used as a pilot.

Experimental research of asynchronous electric drive with positive dynamic feedback on stator current

In this paper, the stability problem of Furuta pendulum controlled by the fractional order PD controller is presented. A mathematical model of rotational inverted pendulum is derived and the fractional order PD controller is introduced in order to stabilize the same. The problem of asymptotic stability of a closed loop system is solved using the D-decomposition approach. On the basis of this method, analytical forms expressing the boundaries of stability regions in the parameters space have been determined. The D-decomposition method is investigated for linear fractional order systems and for the case of linear parameter dependence. In addition, some results for the case of nonlinear parameter dependence are presented. An example is given and tests are made in order to confirm that stability domains have been well calculated. When the stability regions have been determined, tuning of the fractional order PD controller can be carried out.

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D-decomposition technique for stabilization of Furuta pendulum: fractional approach

Well, someone can decide by themselves what they want to do and need to do but sometimes, that kind of person will need some control of non conventional synchronous motors references. People with open minded will always try to seek for the new things and information from many sources. On the contrary, people with closed mind will always think that they can do it by their principals. So, what kind of person are you?

Control of Non-conventional Synchronous Motors

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The analysis of the quality of the frequency control of induction motor carried out on the basis of the processes in the rotor circuit

This paper considers features of mechanical characteristics of induction motor drives, as well as methods that increase their efficiency in a static regime under overloading. The induction motor vector diagrams are constructed by an L-shaped equivalent circuit taking into account and neglecting the stator resistance in order to describe the physical process of reducing the electromagnetic torque with increasing frequency of the supply voltage. Using vectors of rotor current codirected with the main magnetic flux of magnetizing current and the angle between them, it is shown how the shape of a torque triangle changes with increasing frequency of the supply voltage. Mathematical analysis of the elaborated formula of Kloss showed that the derivative of the electromagnetic torque of the induction motor has a negative sign in terms of the frequency of the supply voltage. Due to this, the conventional methods of correction under overloading, which increase the supply voltage frequency with the increasing stator currents, lead to even higher currents and reduction of the actual engine speed. Algorithms for improving the efficiency of frequency control of induction electric drives are proposed. Under a heavy load, it is required to increase the flux in the motor voltage by increasing the voltage, and if this is not possible, by reducing the frequency. The proposed algorithms are confirmed by experimental studies of the traction drive of a shaft self-propelled car.

Effective frequency control for induction electric drives under overloading

The efficiency of analyzing the rotor currents of asynchronous electric drives with frequency control is substantiated in the article. To assess the quality of torque generation in the engine it is suggested to use the spectral analysis of these currents and the fundamental harmonic, as the most accurate "conformity" of slip in an asynchronous motor. The proposed method showed that "sensorless vector" control leads to the appearance of high-frequency harmonics with significant amplitude. Because of these harmonics, a non-sinusoidal electromagnetic moment is created and the performance of the drive is decreased. The most effective method of torque generation is the frequency control with positive stator current feedback. This control is dominated by pronounced harmonic components, which indicates the proximity of this structure to linear and significantly better controllability of the drives, which makes promising their use in high-tech mechanisms, in particular, in industrial robots. Simulation and experiments confirm the proposed theoretical propositions.

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Vladimir L. Kodkin

Papers

The dynamics identification of asynchronous electric drives via frequency response

Experimental research of asynchronous electric drive with positive dynamic feedback on stator current

The analysis of the quality of the frequency control of induction motor carried out on the basis of the processes in the rotor circuit

Effective frequency control for induction electric drives under overloading

Performance identification of the asynchronous electric drives by the spectrum of rotor currents