One of the main merits offered by multiphase machines is their high fault-tolerant capability Literature has demonstrated that the performance of multiphase induction machines under fault conditions is affected by the employed stator winding connection In open-loop controlled five-phase machines, the star connection is favorable under healthy conditions while the pentagon connection is favorable and yields a lower derating factor under the open phase condition In this paper, a new combined star/pentagon single layer winding layout that combines the advantages of both star and pentagon connections is proposed for a five-phase induction machine Although the proposed winding is intrinsically an asymmetrical ten-phase machine, the proposed connection allows for only five-phase terminals Moreover, the proposed winding not only yields better flux distribution compared to a conventional single layer winding, but also provides a complete cancellation of the third-order harmonic flux component caused by the induced third sequence currents due to the saturation effect and/or under unbalanced operation Hence, the machine losses are decreased, which improves the overall machine efficiency For the healthy case, the machine is similar to a conventional star connected five-phase machine However, with one phase open, the proposed connection results in a lower derating factor compared to conventional connections for both open-loop and optimal current control techniques A 1-kW prototype machine is used for experimental verification

An Improved Fault-Tolerant Five-Phase Induction Machine Using a Combined Star/Pentagon Single Layer Stator Winding Connection

A novel adaptive control method for induction motor based on Backstepping approach using dSpace DS 1104 control board

This study presents a backstepping direct power control (BS-DPC) strategy for the grid-connected AC/DC converter under both balanced and unbalanced grid conditions. The proposed BS-DPC adopts the non-linear BS controller to the DPC strategy in the stationary reference frame, thus phase-locked loop is unnecessary. A generalised power compensation method is applied to the proposed BS-DPC under unbalanced grid condition to achieve multiple control targets. To validate the effectiveness of the proposed BS-DPC, comparative experimental studies are conducted under both balanced and unbalanced grid conditions. Experimental results verify that the proposed BS-DPC inherits the excellent dynamic performance of the traditional DPC and has excellent steady-state performance as well. In addition, flexible control targets can be achieved and dynamically adjusted under unbalanced grid condition according to the grid safety operation requirement.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-pel.2015.0653

Backstepping direct power control without phase-locked loop of AC/DC converter under both balanced and unbalanced grid conditions

In three-phase induction motor drives, addition of certain zero-sequence signal which divides the null vector time equally between the two zero states is known to improve the harmonic performance over sinusoidal modulation. Similarly, in split-phase induction motor (SPIM) drives also, addition of such a zero-sequence signal to each set of three-phase sinusoidal modulating waves leads to reduction in total harmonic distortion (THD) in a motor current. However, the above method known as double zero-sequence injection pulse width modulation (DZIPWM) is significantly inferior to four-dimensional 24-sector space vector pulse width modulation (4D24SEC PWM) in terms of THD. This paper investigates and attempts to determine the zero-sequence signal, if any, whose injection could result in a harmonic performance comparable to that of 4D24SEC PWM. Such a zero-sequence signal is determined and is shown to be quite different from that used in DZIPWM. The analytical findings are used to propose a computationally efficient, carrier-based approach to implement the 4D24SEC PWM, whose implementation is otherwise highly resource intensive. The feasibility, computational efficiency, and accuracy of the proposed approach are demonstrated and validated on a 6-kW split-phase motor drive, controlled from a field programmable gate array platform. This paper enables good harmonic performance of the split-phase drive with low computational effort and resources.

Investigation on Zero-Sequence Signal Injection for Improved Harmonic Performance in Split-Phase Induction Motor Drives

This article presents the control possibility of five-phase induction machines. In the proposed solution, the machine model vector form is not transformed to the ( dq )-coordinate system, that is connected to the rotor flux vector, but utilizes the stationary system (α β ). Moreover, the nonlinear model linearization is based on demonstrated nonlinear variables transformation for i -orthogonal $(\alpha \beta)_{(n)}$ planes. By introducing the backstepping approach, the independent stabilization of electromagnetic torque and rotor flux in each plane is obtained. A practical stability analysis of the proposed controller for a multiphase machine is illustrated as well. Finally, experimental test results are demonstrated for a specific speed sensorless five-phase induction motor test setup.

Feedback Control of Multiphase Induction Machines With Backstepping Technique

In this study, a direct torque and flux control is described for a six-phase asymmetrical speed and voltage sensorless induction machine (IM) drive, based on non-linear backstepping control approach. First, the decoupled torque and flux controllers are developed based on Lyapunov theory, using the machine two axis equations in the stationary reference frame. In this control scheme, the actual stator voltages are determined from dc-link voltage using the switching pattern of the space vector pulse-width modulation inverter. Then, for a given motor load torque and rotor speed, a so-called fast search method is used to maximise the motor efficiency. According to this method, the rotor reference flux is decreased in the small steps, until the average of real input power to the motor reaches to a minimum value. In addition, a model reference adaptive system-based observer is employed for online estimating of the rotor speed. Finally, the feasibility of the proposed control scheme is verified by simulation and experimental results.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-pel.2013.0081

Seyed Mohammad Jalal Rastegar Fatemi

Papers

Speed sensorless control of a six-phase induction motor drive using backstepping control