A split-phase induction motor (SPIM) is obtained by splitting each of the three-phase stator windings of an induction motor into two equal halves. This results in two sets of three-phase windings with a spatial angle difference of 30◦ (electrical) between them. The two sets of windings are fed from two different voltage-source inverters for speed control of the split-phase motor drive. Low dc bus voltage requirement and improved torque profile are some of the advantages of the split-phase motor, compared to the normal three-phase induction motor. A pulse width modulation (PWM) technique is used to produce the gating signals for the power semiconductor devices in the two inverters. The PWM technique can either be a carrier comparison (CC) based method or a space-vector (SV) based scheme. The carrier based PWM methods employ six modulating waves, which are compared against a common triangular carrier to generate the gating pulses. In space-vector based PWM schemes, the voltage reference is specified in terms of a rotating reference vector. In each subcycle, a set of voltage vectors are applied for appropriate durations of time to produce an average vector equal to the reference vector. Unlike three-phase induction motor drives, where the voltage vectors are two dimensional, the voltage vectors in the case of SPIM drive are four dimensional. This thesis presents a detailed survey on carrier-comparison based and space-vector based PWM techniques for the SPIM drive. In this thesis, sine-triangle PWM (STPWM) is analyzed from a space-vector perspective. The set of voltage vectors applied and the sequence of application of the voltage vectors in each half-carrier cycle are studied. The analysis shows that the set of voltage vectors and the switching sequence employed by STPWM are different from those used by the well known SVPWM tech-niques. Two other CC based PWM techniques, based on common mode injection, are considered for the SPIM drive. In one method, the common-mode signal is derived from all the six modulating signals, and is the same for both the inverters. In the second method, the common-mode signal is different for the two inverters; each common-mode signal is derived from the three-phase sinusoidal signals of the respective inverter. The study shows that the latter method has the highest dc bus utilization and results in the lowest total harmonic distortion (THD) among the CC PWM techniques. An experimental comparison of the three carrier-comparison techniques with three well known space-vector PWM techniques is presented. Total harmonic distortion (THD) of the line current is measured at different modulation indices for all six techniques. The experimental results are obtained from a 6kW, 200V, 50Hz split-phase induction motor drive, with constant V /F ratio. The PWM techniques are implemented using an ALTERA cyclone II field programmable gate array (FPGA) digital controller. One of the SV techniques, termed here as 4-dimensional 24-sector (4D24SEC) PWM is found to be the best in terms of line current THD among all the CC and SV based PWM techniques considered. However, compared to any carrier-based technique, implementation of the 4D24SEC PWM based on the space vector approach is found to be resource intensive. Hence, an equivalent carrier-based implementation of 4D24SEC PWM is proposed in this thesis. The feasibility of the proposed approach is verified experimentally, and is found to be consuming much less logical resources than the space-vector implementation (i.e. 4102 logical elements for the CC approach as against 33,655 logical elements for the SV approach). A new space-vector PWM technique is also proposed in the thesis. This technique utilizes a new set of voltage vectors and a new switching sequence, which are motivated by the analyses of the carrier-based methods, presented earlier. The proposed technique is implemented, and is compared with other space-vector and carrier-based methods at different modulation indices and switching frequencies. The proposed PWM technique is found to have the same dc-bus utilization as the existing 4-dimensional SV based PWM techniques. The performance of the proposed method is found to be not better than existing 4-dimensional SV PWM methods. The possibilities for new switching sequence is being explored here.

This thesis reports on the design and evaluation of a microprocessor-controlled, high-speed analog-to-digital converter. The processor supervises and manages the digital conversion, split-phase encoding (Manchester) and framing of the input signal. This converter is designed to be applied in an underwater package which will serially transmit sensor data over a fiber optic link to a shore station. This intelligent sensor will provide for ease of future system enhancements. An example would be the implementation of one package to multiplex several analog channels from a local sensor network over the single fiber optic link to the shore station. Keywords: Analog-to-Digital converter, Digital conversion, Split phase encoding, and Manchester. (r.h.) / http://archive.org/details/microprocessorco00schl / U.S. Coast Guard (U.S.C.G.) author.

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the Degree of Doctor of Philosophy. / Variable speed motors are achieved by varying the voltage of a DC machine or by varying the frequency of an AC machine, the former method being the simpler of the two. DC motors have the major disadvantage of brushes and commutators which require regular downtime for maintenance, a fact already recognised by Tesla [1] in 1888. Thus the AC motor, in particular the induction motor, is of a more rugged design and does not suffer from the commutator problem of its DC counterpart. Recent advances in the technology of the power electronics used to supply a variable frequency to the motor has allowed the induction motor to be a viable alternative to the DC motor in variable speed applications. Problems have been encountered in industry when an inverter is injudiciously selected to be combined with a motor. Such problems were highlighted by difficulties being experienced with some 400 kW inverter drives. The inverters had been bought from one supplier and the motors from another. When this system was coupled together, there was excessive heating in the motors and the overall plant was only able to operate well below its capacity, incurring a substantial weekly loss of income. The motor and inverter were evidently incompatible, and since the inverter could not be modified, the motor was redesigned to make it less susceptible to the harmonics present in the inverter waveform, These problems have led to the development of a variable speed drive simulation package at the University for use by the local industry which can accurately model the complete system of inverter, motor and its associated load. It is envisaged that this package could be used to predict the performance of a drive system and highlight problems that may occur. To be able to do this, an accurate model of the motor is required. This investigation gives the development of an induction motor model which is suitable . for variable speed drive system simulations. The model accounts for the deep bar effect by using lumped parameter circuits and includes saturation of the leakage paths using only information which is typically available from motor design data. A complete analysis is given of the different lumped parameter models and their suitability for use in this application. The thesis also shows the utilisation of the deep bar model to simulate reswitching transients and double cage motors. The author hopes that the models used in the simulation package wallow industry to predict problems prior to their occurrence, alter the designs and thereby avoid costly remanufacture of the system. / Andrew Chakane 2018

As the costs of large-scale power generation and transmission rise, distributed generation is becoming a prevalent alternative used by a growing number of both residences and businesses. Distributed generation systems typically consist of two main components: a small-scale, often high-efficiency or renewable power source, such as a fuel cell, solar panel, or wind turbine, and a power electronic converter to convert the raw power produced by the source to a usable form. In North America, the majority of power used in residential and light commercial locations is provided in a form known as single-phase three-wire, or split-phase. This consists of two half-phase AC voltages, each of 110 to 120V rms, and one combined AC voltage of 220 to 240V rms. It is therefore necessary for distributed generation systems to supply power in this same form so that it can be used by standard loads such as lighting or appliances, and the excess power can be fed back into the distribution grid. The most common type of converter used to make this conversion is the voltage-sourced inverter (VSI). There are, however, some advantages to using a current-sourced inverter (CSI) instead. These include improved output voltage waveform quality, built-in voltage boost, and built-in overcurrent protection. However, there are also two obstacles that have prevented the adoption of current-sourced inverters to date. The first obstacle to the use of current-sourced inverters is that they require a DC current input to operate. Therefore, a circuit and control algorithm must be developed to produce a DC current from a low DC voltage source. The first part of this thesis deals with the generation of a suitable DC current. The second major obstacle to adopting current-sourced inverters is that no algorithm for producing single-phase three-wire outputs with a CSI presently exists in literature. The second part of this thesis develops such a switching algorithm, using a three-leg current-sourced inverter. The algorithm is demonstrated using simulation and experimental results, which show that the proposed system is able to successfully generate balanced output voltages under unbalanced loading conditions while equalizing switch utilization and minimizing output voltage ripple.

As the costs of large-scale power generation and transmission rise, distributed generation is becoming a prevalent alternative used by a growing number of both residences and businesses. Distributed generation systems typically consist of two main components: a small-scale, often high-efficiency or renewable power source, such as a fuel cell, solar panel, or wind turbine, and a power electronic converter to convert the raw power produced by the source to a usable form. In North America, the majority of power used in residential and light commercial locations is provided in a form known as single-phase three-wire, or split-phase. This consists of two half-phase AC voltages, each of 110 to 120V rms, and one combined AC voltage of 220 to 240V rms. It is therefore necessary for distributed generation systems to supply power in this same form so that it can be used by standard loads such as lighting or appliances, and the excess power can be fed back into the distribution grid. The most common type of converter used to make this conversion is the voltage-sourced inverter (VSI). There are, however, some advantages to using a current-sourced inverter (CSI) instead. These include improved output voltage waveform quality, built-in voltage boost, and built-in overcurrent protection. However, there are also two obstacles that have prevented the adoption of current-sourced inverters to date. The first obstacle to the use of current-sourced inverters is that they require a DC current input to operate. Therefore, a circuit and control algorithm must be developed to produce a DC current from a low DC voltage source. The first part of this thesis deals with the generation of a suitable DC current. The second major obstacle to adopting current-sourced inverters is that no algorithm for producing single-phase three-wire outputs with a CSI presently exists in literature. The second part of this thesis develops such a switching algorithm, using a three-leg current-sourced inverter. The algorithm is demonstrated using simulation and experimental results, which show that the proposed system is able to successfully generate balanced output voltages under unbalanced loading conditions while equalizing switch utilization and minimizing output voltage ripple.

This work is in the first chapter deals with the basic properties of single phase and three-phase induction motors. The following describes the procedure for obtaining a starting torque of single-phase asynchronous motor. In the second part of the calculation is carried out single-phase induction motor with a permanently connected capacitor and its control, calculation of output values, the program proposed solution to this calculation in Microsoft Excel 2007 and calculated parameters of the development of methods of calculation were compared with measured, the values supplied by ATAS Náchod.