The main objective of this two-part state-of-the-art paper called “Recent Advances in the Design, Modeling, and Control of Multiphase Machines” is to present latest contributions in the multiphase machines' field. The first part of this paper focuses on the recent progress in the design, modeling, and control, whereas the drive is in healthy operation. This second part presents relevant contributions in two not analyzed fields. The first is in relation with the use of the additional degrees of freedom of multiphase machines and the exploitation of their fault-tolerant capabilities without adding extra hardware. The second one analyzes multiphase generation, particularly in grid-connected wind energy conversion systems and stand-alone applications. Recent progresses are shown and open challenges and future research directions are discussed.

Recent Advances in the Design, Modeling, and Control of Multiphase Machines—Part II

The paper presents a study of postfault control for an asymmetrical six-phase induction machine with single and two isolated neutral points, during single open-phase fault. Postfault control is based on the normal decoupling (Clarke) transformation, so that reconfiguration of the controller is minimized. Effect of the single open-phase fault on the machine equations under this control structure is discussed. Different modes of postfault operation are analyzed and are further compared in terms of the achievable torque and stator winding losses. Validity of the analysis is verified using experimental results obtained from a six-phase induction motor drive prototype.

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Post-fault operation of an asymmetrical six-phase induction machine with single and two isolated neutral points

The gastrointestinal tract - the largest endocrine network in human physiology - orchestrates signals from the external environment to maintain neural and hormonal control of homeostasis. Advances in understanding entero-endocrine cell biology in health and disease have important translational relevance. The gut-derived incretin hormone glucagon-like peptide 1 (GLP-1) is secreted upon meal ingestion and controls glucose metabolism by modulating pancreatic islet cell function, food intake and gastrointestinal motility, amongst other effects. The observation that the insulinotropic actions of GLP-1 are reduced in type 2 diabetes mellitus (T2DM) led to the development of incretin-based therapies - GLP-1 receptor agonists and dipeptidyl peptidase 4 (DPP-4) inhibitors - for the treatment of hyperglycaemia in these patients. Considerable interest exists in identifying effects of these drugs beyond glucose-lowering, possibly resulting in improved macrovascular and microvascular outcomes, including in diabetic kidney disease. As GLP-1 has been implicated as a mediator in the putative gut-renal axis (a rapid-acting feed-forward loop that regulates postprandial fluid and electrolyte homeostasis), direct actions on the kidney have been proposed. Here, we review the role of GLP-1 and the actions of associated therapies on glucose metabolism, the gut-renal axis, classical renal risk factors, and renal end points in randomized controlled trials of GLP-1 receptor agonists and DPP-4 inhibitors in patients with T2DM.

GLP-1 and the kidney : from physiology to pharmacology and outcomes in diabetes

The most serious and recent competitor to the standard field oriented control for induction motors (IM) is the finite control set model predictive control (FCS-MPC). Nevertheless, the extension to multiphase drives faces the impossibility to simultaneously regulate the flux/torque and the secondary current components (typically termed $x - y$ in the literature). The application of a single switching state during the whole sampling period inevitably implies the appearance of $x - y$ voltage/currents that increase the system losses and deteriorate the power quality. These circulating currents become intolerably high as per the unit $x - y$ impedance and the switching frequency diminish. Aiming to overcome this limitation, this work suggests the integration of virtual voltage vectors (VVs) into the FCS-MPC structure. The VVs ensure null $x - y$ voltages on average during the sampling period and the MPC approach selects the most suitable VV to fulfill the flux/torque requirements. The experimental results for a six-phase case study compare the standard FCS-MPC with the suggested method, confirming that the VV-based MPC maintains the flux/torque regulation and successfully improves the power quality and efficiency.

Model Predictive Control of Six-Phase Induction Motor Drives Using Virtual Voltage Vectors

The fault tolerance of electric drives is highly appreciated at industry for security and economic reasons, and the inherent redundancy of six-phase machines provides the desired fault-tolerant capability with no extra hardware. For this reason some recent research efforts have been focused on the fault-tolerant design, modeling, and control of six-phase machines. Nevertheless, a unified and conclusive analysis of the postfault capability of six-phase machine is still missing. This paper provides a full picture of the postfault derating in generic six-phase machines and a specific analysis of the fault-tolerant capability of the three mainstream six-phase induction machines (asymmetrical, symmetrical, and dual three phase). Experimental results confirm the theoretical post fault current limits and allow concluding, which is the best six-phase machine for each fault scenario and neutral arrangement.

A Unified Analysis of the Fault Tolerance Capability in Six-Phase Induction Motor Drives

This paper presents a nine-phase permanent-magnet synchronous motor (PMSM) drive system based on multiple three-phase voltage source inverters. The nine-phase PMSM was developed as a traction motor for an ultrahigh-speed elevator. The mathematical model of the motor was simplified through symmetry of the system. Using the simplified model, the drive system can be controlled by the well-known d-q control theory. The feasibility and validity of the drive system were experimentally demonstrated at the world's tallest elevator test tower. Moreover, an additional experiment was performed to ensure the fault-tolerance capability of the system.

A Nine-Phase Permanent-Magnet Motor Drive System for an Ultrahigh-Speed Elevator

Gemigliptin improves renal function and attenuates podocyte injury in mice with diabetic nephropathy.

This paper presents an application of a disturbance observer for a relative position control system. In this system, since the prefixed motion profile is not defined ex ante, the acceleration state which is generated based on the profile is also not available. Therefore, feedforward acceleration controls cannot be used, and the position control performance is restricted solely by the bandwidth of the position controller. To enhance the control performance, disturbance observers can be utilized actively. The proposed method considers the position reference just as the result of a disturbance. Therefore, the relative position control can be performed by a disturbance observer as well as a position controller. As a result, the position control performance of the proposed method has been enhanced by up to 30% compared with that of the conventional method. The feasibility of the proposed method has been verified by experimental results using a high-precision linear motion control system as well as by analysis based on Bode plots.

Application of a Disturbance Observer for a Relative Position Control System

In a relative position control system, where feedfoword control can not be applied and the position control performance is restricted only by the bandwidth of the position controller, a disturbance observer are used actively to enhance the control performance. The position reference is considered as a disturbance by the proposed method. Therefore, the relative position control is performed by the disturbance observer as well as by the position controller. As a result, the position control performance is enhanced up to about 33 [%] compared to that of the conventional method with the disturbance observer. The feasibility of the proposed method has been verified by the experimental results using a high precision linear motion control system as well as by the analysis based on Bode plot.

Application of a disturbance observer for a relative position control system

In this paper, a motion controller based on a Field Programmable Gate Array (FPGA) with a high performance current regulator is presented. This system contains a processor and a high bandwidth current regulator as a peripheral, and all of these are implemented on a single-chip FPGA. The execution time of the current regulator is less than 200 ns at 100 MHz clock frequency. Thanks to this fast execution, the inevitable digital delay, which is 1.5 times the sampling period in a PWM inverter has been reduced to a half of the sampling period. As the result, the control bandwidth of the current regulator has been extended up to about 3 kHz at 10 kHz PWM switching frequency. By exploiting the performance of the current regulator, the speed regulation bandwidth also enhanced up to 700 Hz. The experimental results are presented to demonstrate the validity of the proposed system and the performance of the regulator.

Eunsoo Jung

Papers

A Nine-Phase Permanent-Magnet Motor Drive System for an Ultrahigh-Speed Elevator

Gemigliptin improves renal function and attenuates podocyte injury in mice with diabetic nephropathy.

Application of a Disturbance Observer for a Relative Position Control System

Application of a disturbance observer for a relative position control system

FPGA-based motion controller with a high bandwidth current regulator