Research of dampher system damage physical processes of synchronous machines rotor

The physical processes in the damper system of the rotor with the appearance of a static eccentricity of the rotor for two types of salient-pole synchronous machines - a capsule hydrogenator SGK 538/160-70M with a capacity of 22 MW and a synchronous generator with a capacity of 500 kW were investigated by means of mathematical modeling. A field mathematical model has been developed that takes into account the combined action of three physical fields of different nature: electromagnetic, temperature and field of thermomechanical stresses, and makes it possible to evaluate the heating and three-dimensional distribution of thermomechanical stresses in the structural elements of the rotor damper system of a salient-pole synchronous machine. These physical processes cause gradual destruction of the structure of the rotor damper system. It is proved that the primary cause of degradation and damage of the damping system of the rotor of an open-pole synchronous machine is the uneven distribution of induced currents in the rods at the poles of the rotor, which occurs when the machine works asynchronously or with the appearance of rotor static eccentricity. The largest induced currents and heat occur in the rods located at the edges of the pole pieces, while the central rods at the pole are heated significantly less. This asymmetric heating of the damping system of the rotor leads to significant thermomechanical stresses in the elements of the damping system of the rotor, which significantly depend on the magnitude of the eccentricity and slippery of the rotor in asynchronous mode. The magnitude of the total thermomechanical stresses in the rods is influenced not only by axially directed forces but also by transverse forces in the end short-circuiting elements. At considerable slippery and eccentricities there are inadmissibly big breaking forces which break cores and face short-circuiting elements of a damping system of a rotor. According to the results of the analysis, the heating and thermomechanical stresses of the structural elements were determined and recommendations for its structural improvement were given.

Flux Estimator for Salient Pole Synchronous Machines Driven by the Cycloconverter Based on Enhanced Current and Voltage Model of the Machine with Fuzzy Logic Transition

Flux estimation is a key feature of the field-oriented control for the electrically excited synchronous machine which enables the high-performance, high-dynamic drive behavior. In this work, an electrically excited synchronous machine flux estimator based on a current and voltage model is proposed. In this case, the transition between the estimators is done with a fuzzy logic set of rules. The flux estimator based on the current model of the machine in this paper considers the saturation and cross-coupling effect in both axis and it is suitable for applications where a limited amount of the machine data is available. The flux estimator based on the voltage model is specially designed for the drives where high voltage and current ripple is present under normal operating conditions, e.g., like in cycloconverter applications. To exploit all the advantages of both models, a fuzzy logic transition is proposed based on multiple choices which manages the transition between the models based on a speed and torque reference. The proposed flux estimator is experimentally verified on a cycloconverter fed salient-pole electrically excited synchronous machine. The experimental results clearly show that the proposed flux estimator enables the accurate and stable operating conditions for different operating points of the cycloconverter-fed salient-pole electrically excited synchronous machine.

Overview of AC Motor Sensorless Algorithms: a Unified Perspective

This paper reviews sensorless algorithms for both induction motors and permanent magnet motors using the active flux model, such that any design applicable for non-salient pole ac motors can also be included in the review framework. The proposed review framework classifies all sensorless algorithms following a five-layer hierarchy abbreviated as O-I-M-A-I, resulting in four main categories as i) inherently sensorless position estimation, ii) non-inherently sensorless position estimation, iii) post-position-estimation speed estimation, and iv) speed estimation for indirect field orientation. Various ac motor models are derived by assuming a constant active flux amplitude, based on which seven generic sensorless algorithms are summarized in a tutorial. Recommendations are made for sensorless drive designers to begin with inherently sensorless method such that the two-way coupling between position estimation and speed estimation is avoided. Finally, classical induction motor model results from time-varying active flux amplitude and slip relation, for which a state transformation is recommended for achieving global stability.<br>

Overview of AC Motor Sensorless Algorithms: a Unified Perspective

This paper reviews sensorless algorithms for both induction motors and permanent magnet motors using the active flux model, such that any design applicable for non-salient pole ac motors can also be included in the review framework. The proposed review framework classifies all sensorless algorithms following a five-layer hierarchy abbreviated as O-I-M-A-I, resulting in four main categories as i) inherently sensorless position estimation, ii) non-inherently sensorless position estimation, iii) post-position-estimation speed estimation, and iv) speed estimation for indirect field orientation. Various ac motor models are derived by assuming a constant active flux amplitude, based on which seven generic sensorless algorithms are summarized in a tutorial. Recommendations are made for sensorless drive designers to begin with inherently sensorless method such that the two-way coupling between position estimation and speed estimation is avoided. Finally, classical induction motor model results from time-varying active flux amplitude and slip relation, for which a state transformation is recommended for achieving global stability.<br>

Research on Dual-Phase Non-Salient Pole Receiver for EV Dynamic Wireless Power Transfer System

Dynamic wireless power transfer (DWPT) technology shows a vast development prospect for EV application, with advantages of reducing the demand for battery capacity and improving the user experience. However, the need to improve output performance leads to a challenge in receiver design with limited space and allowable load on the EV side. In this paper, a design of a dual-phase non-salient pole (NSP) receiver for the EV DWPT system with bipolar transmitter is proposed, aiming at providing a solution to the contradiction between reducing the volume or cost and improving the misalignment tolerance of the receiver. The coupling principle of the proposed receiver is analyzed. The structure parameters are optimized by the finite-element simulation method. Combined with specific design indexes, it is proven by comparison with the existing dual-phase receiver that the proposed receiver is 35.4% smaller in volume and needs 47.0% shorter wires. Moreover, the significant advantage of the proposed dual-phase NSP receiver in misalignment tolerance is verified by simulations and experimental comparisons.

Active Q Flux Concept for Sensorless Control of Synchronous Reluctance Machines

<p>This paper proposes a new scheme to use active flux on q-axis for sensorless control of synchronous reluctance machines (SynRM). Conventionally, “Active Flux” on d-axis is adopted to convert a salient pole machine into a fictitious non-salient pole machine. However, the injected d-axis flux can deteriorate high frequency injection (HFI) sensorless control performance or even run the system into unstable region at low speed. This paper demonstrates active flux on q-axis can support back-EMF sensorless control at high speed and improve low speed HFI performance substantially. A seamless transition from HFI sensorless method to back-EMF voltage method is attained after adopting the proposed active q flux. Experiment results are used to validate the proposed method.</p>

Active Q Flux Concept for Sensorless Control of Synchronous Reluctance Machines

<p>This paper proposes a new scheme to use active flux on q-axis for sensorless control of synchronous reluctance machines (SynRM). Conventionally, “Active Flux” on d-axis is adopted to convert a salient pole machine into a fictitious non-salient pole machine. However, the injected d-axis flux can deteriorate high frequency injection (HFI) sensorless control performance or even run the system into unstable region at low speed. This paper demonstrates active flux on q-axis can support back-EMF sensorless control at high speed and improve low speed HFI performance substantially. A seamless transition from HFI sensorless method to back-EMF voltage method is attained after adopting the proposed active q flux. Experiment results are used to validate the proposed method.</p>