Split Winding Research Articles

Calculating Leakage Inductances of Split-Windings in Dry-Type Traction Transformers

Calculating leakage inductances between windings of multi-winding traction transformers is one of the most important schemes in design procedure. In this paper, a new analytical method and finite element models have been introduced for electromagnetic modeling of traction transformers with four split windings. Using these methods, the leakage inductances between the split windings are calculated and the methods have been validated with the help of experimental data gathered from a typical 4000kVA cast-resin dry-type transformer. Some reformations are employed to improve the finite element results and effects of these reformations on accuracy of the models are studied. Employing the validated models, the effects of middle yoke on the leakage inductances of split-winding traction transformer are discussed in this paper.

A Study on the Design and Quench Protection of a Conduction-Cooled Magnet for a Superconducting Property Measurement System

A superconducting property measurement system (SPMS) is used to acquire electrical and thermal properties of short HTS tape samples. The SPMS is composed of a specimen holder for mounting an HTS tape and magnet for applying a magnetic field externally. The magnet consists of two split racetrack windings and is designed to produce maximum 3 T of center field at 20 K. In this paper, an HTS magnet for the SPMS cooled by a cryocooler was designed. A HTS magnet consists of several pancakes winding wound from YBCO CC tape. We report out design for a conduction-cooled magnet using YBCO CC tape. For varying the number of double pancake coils (DPCs) and the bending radius, an electromagnetic field analysis is used. We subsequently find a suitable HTS magnet type for an SPMS. This paper describes the quench protection system for an HTS magnet of the SPMS. The detection of any normal zone must be preceded to protect the HTS magnet. We use simulated protection circuit to estimate the trigger conditions. The presented results in this paper will be verified using fabricated protection circuit.

Comparative Study Of The Inductances Of An Induction Motor With Rotor Eccentricities

In this work, the inductances of an induction motor, which rotor may be misaligned, are evaluated. Two types of analysis are performed: Analytical Method (AM) and Finite Element Method (FEM). For radial displacements, both methods show equivalent results but to evaluate inductances as a function of angular displacements, only with FEM was possible to get results as with AM it would be necessary intricate functions. The inductances obtained with FEM were included in simulations of a bearingless induction motor with split windings. This approach shows a good agreement with experimental results.

A Conceptual Design of a Conduction-Cooled Magnet for a Superconducting Property Measurement System

We started a new project to develop the conduction-cooled measurement system for superconducting power apparatus. The measurement system is used to acquire electrical and thermal properties on short HTS tape samples and the system is composed of specimen holder for mounting HTS tape and a magnet for applying magnetic fields externally. The magnet consists of two split racetrack windings and is designed to produce maximum 3 T of center field at 20 K. The temperature of specimen holder can be varied in range from 10 K to 77 K. The field homogeneity, which is calculated the maximum magnetic field divided by the center field, is required less than 0.01 within 10 cm axially and 10 mm radially from origin. We have worked on the conceptual designs of the conduction-cooled magnet for the superconducting characteristic measurement system. The measurement system will be fabricated in near future based on the design parameters presented in this paper.

Reduction of force exciting influences to decrease radiation of acoustic noise in synchronous machines

PurposeThe paper aims to provide an approach to actively decrease the radiation of acoustic noise in synchronous machines.Design/methodology/approachSplitting regular three‐phase windings of synchronous machines into two independent three‐phase systems allows for an active influence of the current waveform if both winding systems are mutually displaced against each other. The harmonics content of each phase‐current varies due to the mutual inductive coupling with participating currents of both systems. Therefore, the ensuing force‐density distribution on the stator teeth varies accordingly. Resulting structure dynamics and furthermore the radiation of relevant harmonics of the acoustic noise are based on the mechanical excitation of considered force‐density distributions.FindingsConfigurations of mutual displacement of phase windings of both winding systems with significant decrease of mechanical deformation and emitted acoustic noise are found. Simulation methods to entirely describe and prove the behavior described are developed.Research limitations/implicationsThe proposed approach is developed for a particular synchronous machine. Other machine types are conceivable for analysis in the same manner. Tools need to be adapted. Universal and reliable statements regarding acoustic behavior depend on the mechanical restraint of the machine and may therefore vary.Practical implicationsActive force‐density distribution is used for the noise reduction of alternators in vehicle applications. Additionally, wind‐power generators are considered for the application of split stator winding systems to actively counteract inhomogeneous force distributions on the rotor, evoked by stalling of the propeller blades during pole passing.Originality/valueActive force‐density modification by stator winding modifications allows for the decrease of noise radiation of electrical machines with rotating‐field windings. Innovative simulation methods developed may now replace prototyping partially.

Sensorless operation of surface mount permanent magnet AC (PMAC) motors

A sensorless field oriented control scheme for a surface mount permanent magnet AC (PMAC) motor with split phase stator windings is presented. This motor is obtained by splitting the phase windings of a conventional three phase motor. The six-phase motor, however is run as a three-phase motor by connecting the split phase stator windings in series, while the taps are made available for voltage measurements. By measuring the terminal voltages and the line currents, absolute position of the permanent magnet AC motor driven by a current regulated PWM inverter with a hysteresis controller is estimated. The estimated position information is independent of the stator resistance, thus this scheme is even applicable at low speeds. Results are presented to show the effectiveness of the new controller, and it is also shown that the position error is negligible.

Vector Control of Induction Motor with Split Phase Windings

A vector controlled scheme is described for an induction motor with split phase windings. Such a motor is obtained by splitting the phase windings of a conventional three phase motor with an angular separation of 30 electrical degrees between the axes of the two halves. In the proposed scheme the motor is run as a three phase machine by connecting the split phase windings in series. An appropriate split phase induction motor model based on space phasor notations is proposed. From this space phasor model of the split phase machine, a simple technique for measuring the equivalent circuit parameters for the motor is presented. Based on the proposed model a method for acquiring the position of the rotor flux is developed. The scheme is based only on the voltage and current measurements, without the need for position encoders. It is also independent of machine resistance values. Results from computer simulation as well as from an experimental prototype drive are presented and discussed.

A high-efficiency high-power-generation system for automobiles

This paper presents a new scheme for the efficient generation of high electric power demanded for future automobiles. The new system consists of a permanent-magnet (PM) alternator having high-energy MAGNEQUENCH (MQ) magnets and split winding and a novel electronic voltage regulation scheme. A proof-of-concept system, capable of providing 100/250 A (idle/cruising) at 14 V, has been built and tested in the laboratory with encouraging results. This high output is provided at 15-20 percentage points higher efficiencies than conventional automotive alternators, which translates into considerable fuel economy savings. The system is 8 dB quieter and has a rotor inertia of only 2/3 that of an equivalent production alternator, thus allowing for a belt drive without excessive slippage.

Uniformity condition for a rectangular field coil with a split winding

A generalized Helmholtz condition for field uniformity is derived from the closed form solution of the magnetic field in a multilayer rectangular coil pair as a function of coil dimensions and pair separation. The relation among the dimensions satisfying this condition is found and plotted in parametric form for single layer coils and for a multilayer coil with a specific winding thickness. For square coils of cross section small compared to their mean radius, the gap separation approaches half the coil radius, analogous to the classical condition for circular coils. Comparison between theoretical and measured values for tolerances within +/-5% of the field at the system center agree within a 6% maximum deviation. For the experimental coil, the area enclosed by the +/-5% contour was 58% of the area of the full coil.

Superconducting maglev and LSM development in canada

Studies on the use of superconducting magnets for levitation, synchronous propulsion and guidance of high speed intercity ground transportation in Canada are reported. For a 100 passenger vehicle weighing 300 kN, a levitation height of 22 cms at 480 Km/hr. is obtained by the interaction of eight 3.85 × 105amp turn 100 × 30 cm magnets with eddy currents induced in two 80 × 1 cm aluminum guideway strips. In low speed sections, aluminum thickness is graded to 3 cms to maintain total drag (aerodynamic and magnetic) almost speed independent. The variable speed LSM uses fifty 5 × 105amp turn 40 × 150 cm magnets on a half pitch of 45 cms. The motor, with split 3-phase guideway windings energized in 5 Km block lengths, has 72% efficiency and 0.82 power factor. A favoured guidance scheme for a flat-topped elevated guideway (minimizing snow accumulation) uses the interactions of the propulsion magnets with flat null-flux loops overlying the LSM windings and with the edges of the levitation strips. This scheme produces a lateral stiffness of 106N/m and a maximum guidance force equal to vehicle weight. The Canadian test facility, presently being commissioned, uses full scale magnets and a 7.6 m diameter wheel rotated about a vertical axis with a maximum peripheral speed of 100 Km/hr.

Effect of material structure on the stability of a laminated-plastic cylindrical shell

A compact equation is proposed for analyzing the stability of layered shells in relation to their structure. The case of a shell with split longitudinal-transverse winding subjected to hydrostatic pressure is investigated.

Magnetic Core Circuits for Digital Data-Processing Systems

A magnetic core has a switching time of a few microseconds and has the ability to store binary information indefinitely without application of power. New techniques for using cores in digital data-processing systems are described. Reference is made to a system containing eight hundred cores to indicate reliability, and size and power requirements relative to a vacuum tube version. Three fundamental interconnecting circuits for data transfer are described. These are the single-diode loop, and a new split winding loop, and new inhibit loop. The single-diode loop permits unconditional transfer of information from one or more transmitting cores to one or more receiving cores. The split-winding loop allows conditional transfer between cores and thus permits logical operations upon isolated cores. The inhibit loop offers a reliable method for conditionally inhibiting the transfer of information from one core to another. A logical symbolism for these loops has been found useful in system design and analysis. Units performing the functions of storage, control, and logic are explained. These are shift registers (serial, parallel, and reversible); cycle distributors and counters; negation, inclusive- or, conjunction, exclusive- or, and material equivalence (compare). System design considerations are illustrated by two examples of half-adders.

Split winding transformers

A discussion of the application of and advantages derived from the use of split winding transformers for separating bus sections and for avoiding undue concentration of power from high voltage lines. An explanation is given of the characteristics of these units with respect to the reactances and the effect of load unbalance on the windings.

Split Winding Transformers

A discussion of the application of and advantages derived from the use of split winding transformers for separating bus sections and For avoiding undue concentration of power from high voltage lines. An explanation is given of the characteristics of these units with respect to the reactances and the effect of load unbalance on the windings.