Abstract
In the five-phase induction machine (IM), it is possible to better use the electromagnetic circuit than in the three-phase IM. This requires the use of an adequate converter system which will be supplied by an induction machine. The electric drive system described, in this article, includes the five-phase induction machine supplied by the current source inverter (CSI). The proposed novelty—not presented previously—is the control system structures for the five-phase IM, which is supplied by CSI. The proposed control systems allow for independent control of IM state variables in the first and the second system plane to inject the third harmonic. However, the third harmonic must be suitably associated with the fundamental harmonic. In the proposed solution, the machine vector model is not transformed into the ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d–q</i> ) coordinate system that is connected to the rotor flux vector but utilizes the stationary system ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">α–β</i> ). The nonlinear model linearization is based on the demonstrated nonlinear variables transformation for i-orthogonal ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">α–β</i> ) (i) planes. Voltage control is applied to the control system structure. The control variables of the five-phase IM are the voltage in the dc link and the angular speed of the output current vector. In the control strategy, the control variables are determined for both system planes. Therefore, the transformation of these control variables to the dc link of CSI is proposed. The proposed control structure allows for independent control of variables in the first and second system planes. It leads to the possibility to increase the value of electromagnetic torque up to 12% for the five-phase IM, which has not been used before in the case of the machine supplied by the CSI. All theoretical issues are confirmed by experimental tests in the 5.5 kW five-phase IM.
Highlights
The controlling idea of a five-phase induction motor (IM) is from 1969 [1]
In the literature of the subject, the authors have not utilized the 3rd harmonic injection in the drive system supplied by the current source inverter (CSI)
The control strategy presented in this paper allows controlling the state variables of IM in the 1st and the 2nd system planes independently
Summary
The controlling idea of a five-phase induction motor (IM) is from 1969 [1]. The main advantages of multi (five)-phase drives compared to their three-phase counterparts are [1,2,3,4]: better stator material utilization, lower-rated current per phase, and greater reliability which means the ability to operate during an open phase fault and the possibility to increase the value of electromagnetic torque up to about 10-12 % [1, 3,4, 5,6,7]. Better properties of the control system can be achieved, when a transformation of nonlinear state variables of IM to a linear form is applied [2627] The use of such an input-output linearization [17] was presented in [18] for multi-phase IM. These control variables are obtained under classical feedback control laws for the 1st and 2nd system planes presented in Sec. III, using the introduced state variables transformation. The proposed solutions have never been presented before for the five-phase machine supplied by the CSI It gives possibilities of independent generation of the 1st and the 3rd harmonics –to better use the electromagnetic circuit of the fivephase machine
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