Although the concept of variable-speed drives, based on utilization of multiphase machines, dates back to the late 1960s, it was not until the mid- to late 1990s that multiphase drives became serious contenders for various applications. These include electric ship propulsion, locomotive traction, electric and hybrid electric vehicles, ldquomore-electricrdquo aircraft, and high-power industrial applications. As a consequence, there has been a substantial increase in the interest for such drive systems worldwide, resulting in a huge volume of work published during the last ten years. An attempt is made in this paper to provide a brief review of the current state of the art in the area. After addressing the reasons for potential use of multiphase rather than three-phase drives and the available approaches to multiphase machine designs, various control schemes are surveyed. This is followed by a discussion of the multiphase voltage source inverter control. Various possibilities for the use of additional degrees of freedom that exist in multiphase machines are further elaborated. Finally, multiphase machine applications in electric energy generation are addressed.

Multiphase Electric Machines for Variable-Speed Applications

The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operation.

/pdf/multiphase-induction-motor-drives-a-technology-status-review-1ir91893ja.pdf

Multiphase induction motor drives - : a technology status review

Thank you very much for downloading design of analog cmos integrated circuits. Maybe you have knowledge that, people have look hundreds times for their favorite novels like this design of analog cmos integrated circuits, but end up in malicious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they cope with some malicious virus inside their laptop. design of analog cmos integrated circuits is available in our book collection an online access to it is set as public so you can download it instantly. Our digital library saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Merely said, the design of analog cmos integrated circuits is universally compatible with any devices to read.

Design Of Analog Cmos Integrated Circuits

The solid-state transformer (SST), which has been regarded as one of the 10 most emerging technologies by Massachusetts Institute of Technology (MIT) Technology Review in 2010, has gained increasing importance in the future power distribution system. This paper presents a systematical technology review essential for the development and application of SST in the distribution system. The state-of-the-art technologies of four critical areas are reviewed, including high-voltage power devices, high-power and high-frequency transformers, ac/ac converter topologies, and applications of SST in the distribution system. In addition, future research directions are presented. It is concluded that the SST is an emerging technology for the future distribution system.

Review of Solid-State Transformer Technologies and Their Application in Power Distribution Systems

This paper investigates the capacitor-current-feedback active damping for the digitally controlled LCL-type grid-connected inverter. It turns out that proportional feedback of the capacitor current is equivalent to virtual impedance connected in parallel with the filter capacitor due to the computation and pulse width modulation (PWM) delays. The LCL-filter resonance frequency is changed by this virtual impedance. If the actual resonance frequency is higher than one-sixth of the sampling frequency (fs/6), where the virtual impedance contains a negative resistor component, a pair of open-loop unstable poles will be generated. As a result, the LCL-type grid-connected inverter becomes much easier to be unstable if the resonance frequency is moved closer to fs/6 due to the variation of grid impedance. To address this issue, this paper proposes a capacitor-current-feedback active damping with reduced computation delay, which is achieved by shifting the capacitor current sampling instant towards the PWM reference update instant. With this method, the virtual impedance exhibits more like a resistor in a wider frequency range, and the open-loop unstable poles are removed; thus, high robustness against the grid-impedance variation is acquired. Experimental results from a 6-kW prototype confirm the theoretical expectations.

Capacitor-Current-Feedback Active Damping With Reduced Computation Delay for Improving Robustness of LCL-Type Grid-Connected Inverter

The Cascaded H-Bridge (CHB) multilevel inverter topology has found widespread acceptance in Medium Voltage (MV) drive applications. But a high count of semiconductor devices increases the probability of converter faults in these drives. Therefore, fault tolerant control techniques have been developed which would enable balanced operation even with internal cell faults. Upon detecting a fault, the gate pulses to the drive are interrupted for a short time to take the faulty cell out of service online using bypass contactors, and the drive then resumes operation with the remaining healthy cells. However, the reconnection of the converter to the machine after bypassing the faulty cell results in transient overshoots in the machine input current, due to lack of synchronism between the converter output voltage and the machine terminal voltage. These overshoots may even result in overcurrent trips thereby reducing the reliability of the drive. This paper proposes a method for online soft reconnection of the converter to the machine post fault clearing in a vector controlled drive, in both speed sensor based and sensorless control techniques. The proposed methods are validated by simulation for a 6600 V, 1050 kW13-level CHB inverter fed induction motor drive, and experimentally on a 400 V, 30 kW laboratory machine using a 7-level CHB inverter.

Online Soft Restart of a Cascaded H-Bridge Inverter fed Induction Motor Drive After Cell Faults

Cascaded H-Bridge (CHB) inverter-fed drives are quite popular in high-power industrial applications. However, these drives are extremely sensitive to power supply disturbances on the input grid side, such as voltage sags or short-duration power interruptions that cause the drive to trip on under-voltage protection resulting in production losses. Therefore, it is necessary to employ techniques that improve the resilience of the drive by enabling it to smoothly ‘ride-through’ such short-duration disturbances. The traditional ride-through solutions in CHB drives typically necessitate additional hardware or multiple DC link voltage sensors, which increase the cost and complexity of the system. This paper proposes a simple and cost-effective approach for power-loss ride-through in CHB inverter based vector-controlled induction motor drives. In this method, the kinetic energy stored in the rotating mass is recovered and fed back to the DC-link capacitors to keep all the DC link voltages constant during momentary supply interruptions or voltage sags. The proposed technique works by controlling the voltage space phasor without the need for extra hardware and voltage sensors at the CHB cells. The proposed scheme is experimentally validated on a 30 kW, 7-level CHB inverter based vector controlled induction motor drive.

Power-Loss Ride-Through With Reduced Number of Voltage Sensors in a Cascaded H-Bridge Inverter Fed Vector Controlled Induction Motor Drive

The fault tolerant operation of the drive is a critical requirement in medium voltage high power applications. In these drives, at an event of converter failure, a continuous operation with reduced power rating is preferred over a complete shutdown of the system. Hence, multi-phase machines are widely used for such applications since they offer inherent fault tolerance operation. This paper proposes a new fault tolerance and on-the-fly re-connection algorithm for an LCI and VSI fed multi-phase induction machine drive. The proposed method offers continuous operation of the drive with half the rated power when an LCI is faulty. The proposed algorithm is experimentally validated on a 75 kW multi-phase induction machine drive and the results are presented.

Fault Tolerant Operation of an LCI and VSI fed Hybrid Induction Machine Drive for Medium Voltage High Power Applications

High frequency (50-100 kHz) power electronic converters enable attractive technology for various motor drive applications where the weight and size are largely constrained, like marine propulsion systems. SiC-based converters are the most suitable choice for high-frequency applications because of their lower switching losses than Si-IGBT based converters. However, the SiC-based MV multilevel converter solution for high-power applications is very costly in the current scenario. This paper presents a three stage (LV/DC-DC/MV) Solid State Transformer(SST) fed field oriented controlled (FOC) induction motor drive. In order to minimise cost and electrical losses, Si-IGBT and SiC devices are adopted, and a novel hybrid modulation technique is proposed for the MV stage. The MV stage of the SST-fed drive is realised with an Si-IGBT based Cascaded H-Bridge (CHB) inverter connected in series with a SiC based 2L-VSI. In the proposed control, the CHB inverter is switched at the stator frequency of the drive to supply the fundamental component of demanded voltage from the drive. As a result, it reduces switching losses to a great extent. The 2L-VSI is switched at a high frequency to supply the harmonic content, resulting in a higher effective switching frequency of the drive. The proposed technique is validated on a 300 V(LV)/1.65kV (MV), CHB based SST-fed FOC induction motor drive with different speeds and loading conditions in MATLAB Simulink environment.

MV Propulsion Drive using Solid State Transformer (SST) Technology

In order to achieve wide flux regulation capability, parallel hybrid excitation alternators which comprise of two rotor cores are proposed in the literature. The size of parallel hybrid excitation alternator increases as it has two rotors. In order to reduce the size of the alternator, a parallel hybrid excitation alternator with single rotor is also proposed in the literature. But the proposed rotor configuration is not the best configuration from mechanical point of view. Hence an improved rotor structure is proposed in the present paper to increase the mechanical strength of the rotor without degrading the performance of hybrid excitation alternator. Detailed simulation results are presented in the paper.

Kamalesh Hatua

Papers

Online Soft Restart of a Cascaded H-Bridge Inverter fed Induction Motor Drive After Cell Faults

Power-Loss Ride-Through With Reduced Number of Voltage Sensors in a Cascaded H-Bridge Inverter Fed Vector Controlled Induction Motor Drive

Fault Tolerant Operation of an LCI and VSI fed Hybrid Induction Machine Drive for Medium Voltage High Power Applications

MV Propulsion Drive using Solid State Transformer (SST) Technology

Improved rotor structure of hybrid excitation alternator