Fernando Briz

Carrier-Signal Selection for Sensorless Control of PM Synchronous Machines at Zero and Very Low Speeds

This paper compares pulsating- and rotating-vector carrier-signal injection for self-sensing (or sensorless) control of permanent-magnet synchronous machines (PMSMs). The main focus of this paper is the evaluation of estimation errors due to the physical nonideal attributes of both the machine and the inverter. Initial-position and magnet-polarity estimations are analyzed as well. Transient response and signal processing for both techniques are discussed for completeness. The theoretical analysis is supported by experimental and simulation evidence obtained using interior PMSMs.

Inverter nonlinearity effects in high-frequency signal-injection-based sensorless control methods

An analysis of pulsewidth-modulation inverter nonlinearities influencing high-frequency carrier-signal voltage injection for saliency-tracking-based rotor/flux position estimation is presented in this paper. Distortion of the injected carrier voltage caused by the nonlinear behavior of the inverter has been reported to cause errors in the estimated rotor/flux position. Though a number of techniques have been developed to compensate for inverter nonlinearities, they have not been proven to be effective when a high-frequency low-magnitude voltage needs to be generated. Both the origins of the distortion as well as the requirements for compensation methods to be effective when producing such high-frequency voltages will be established in this paper.

Measurement and Adaptive Decoupling of Cross-Saturation Effects and Secondary Saliencies in Sensorless-Controlled IPM Synchronous Machines

This paper analyzes effects of magnetic saturation, including cross-saturation and secondary saliencies, on saliency- based sensorless control of interior PM synchronous machines. These effects are mitigated by adaptively decoupling saturation induced-saliencies via a structured neural network. The paper includes identification of the dominant, saturation-induced components of the carrier signal current interfering with the rotor position-dependent component being tracked, characterization of these components, and implementation of a non-linear, adaptive, saturation-induced components structured neural network model to perform their decoupling.

Discrete-Time Current Regulator Design for AC Machine Drives

This paper analyzes the behavior of discrete-time current regulators for ac machines operating at high ratios of fundamental-to-sampling frequencies, a situation common for high-speed automotive drives and large-traction drives. At high ratios of fundamental-to-sampling frequencies, highly oscillatory, or unstable, response can occur if the current regulator design does not properly incorporate the effects of the discrete nature of the controller, including delays between the sampling of signals and the application of the voltage commands through pulse-width modulation (PWM). This paper investigates these issues for different design methods and current regulator topologies. As part of this investigation, a simple discrete-time domain ac machine model is developed that includes the delays associated with PWM. This model is then used to design a discrete-time domain version of the complex vector PI current regulator that demonstrates improved response compared with the other regulators studied. Simulation and experimental results are provided to compare the performance, stability, and robustness of the current regulators analyzed.

Broken Rotor Bar Detection in Line-Fed Induction Machines Using Complex Wavelet Analysis of Startup Transients

Fault detection of line-connected induction machines using complex vector wavelets to analyze the transient stator currents during startup is proposed in this paper. When a machine is connected to the line, the startup transient is characterized by large stator (and rotor) currents, as well as by large slips (i.e., rotor speed significantly smaller than the excitation frequency). The stator current of machines with damaged rotors include large rotor speed dependent components during the startup transient. Such components, however, fade away or coincide with components not containing fault related information (e.g., saturation-induced components) once the machine reaches steady-state. Because of this, the startup transient provides an opportunity for performing diagnostics on the machine. The paper shows that the information contained in the startup transient signal can be effectively separated and detected using a complex vector wavelet transform.

Carrier Signal Selection for Sensorless Control of PM Synchronous Machines at Zero and Very Low Speeds

This paper compares pulsating and rotating vector carrier signal injection for self-sensing (or sensorless) control of PM synchronous machines. The main focus of the study is evaluation of estimation errors due to the physical non-ideal attributes of both the machine and the inverter. Initial position and magnet polarity estimation are analyzed as well. Transient response and signal processing for both techniques is discussed for completeness. The theoretical analysis is supported by experimental and simulation evidence obtained using interior PM synchronous machines.

Measuring, modeling and decoupling of saturation-induced saliencies in carrier signal injection-based sensorless AC drives

The focus of this paper is the measuring, modeling, and decoupling of saturation-induced saliencies in carrier signal injection based sensorless control. First techniques for the measurement of saturation-induced saliencies are presented. The goal of these measurements is to provide useful information on the position and magnitude of the various saturation-induced saliencies. Using the results from several different experimental measurements, models are developed explaining the source and behavior of the saturation-induced saliencies. The paper concludes by presenting methods for decoupling the effects caused by the parasitic saturation-induced saliencies, eliminating the errors that they cause in rotor position or flux angle estimation.

A comparative analysis of pulsating vs. rotating vector carrier signal injection-based sensorless control

This paper analyzes the sensitivity to non-ideal physical attributes of pulsating and rotating vector carrier-injection based sensorless techniques, as well as of the impact on the accuracy and robustness of the sensorless control. The analysis is mainly done on the basis of terminal attributes of machines. Initial observations on the subsequent finite element study are also given. Commonly used filtering and position estimation techniques associated with each carrier signal are considered. The analysis is supported by experimental evidence obtained using interior PM synchronous machines, but the findings are applicable to other AC machines as well.

Modeling and Adaptive Decoupling of High-Frequency Resistance and Temperature Effects in Carrier-Based Sensorless Control of PM Synchronous Machines

This paper analyzes the effects of the high-frequency resistances in saliency tracking-based sensorless control methods of permanent-magnet synchronous machines (PMSMs). A high-frequency model of the PMSM, including stator high-frequency resistance, is presented. From this model, potential sources of error in the estimated position due to the high-frequency resistances are analyzed, and their compensation by means of an adaptive decoupling mechanism is proposed. This paper also addresses the influence and compensation of temperature effects in carrier-signal-injection-based sensorless techniques.

Online diagnostics in inverter-fed induction machines using high-frequency signal injection

Fault diagnostics for induction machines using an injected high frequency carrier signal is presented and analyzed in this paper. Both stator winding fault and broken: rotor bar detection is covered. Measurement of the resulting high frequency negative sequence current is shown to be capable of detecting both types of faults at their incipient stage. Though sharing similar physical principles to techniques applied to line-connected machines, the use of a high frequency signal is shown to provide important advantages for inverter fed machines, such as providing the same performance and drastically reduced sensitivity to the working condition of the machine, i.e. torque and flux levels, and fundamental excitation frequency.