Gabriel Gallegos-Lopez

Optimum torque control of permanent magnet AC machines in the field-weakened region

This paper presents a novel current regulation algorithm for permanent-magnet ac (PMAC) machines that provides maximum torque-per-ampere capability in the entire field-weakened region. The algorithm provides robust current regulation with maximum efficiency and torque capability for PMAC machines despite significant changes in the voltage source and machine parameters. The algorithm identifies when the current regulator starts to saturate and determines the optimum d-axis current command for the machine. The q-axis current command is determined from the torque command and d-axis current feedback. When the voltage angle reaches the maximum angle, the current magnitude is decreased to provide maximum torque per ampere. Experimental results from a machine prototype show that the algorithm provides good overall dynamic response and smooth transitions into the field-weakened region with maximum torque-per-ampere capability in all four quadrants of operation.

Current Control of Induction Machines in the Field-Weakened Region

This paper presents a novel current regulation algorithm for induction machines that enables smooth operation and maximum torque-per-ampere capability over the entire field-weakened region. The algorithm enables robust current regulation with maximum torque capability despite significant variation in voltage source and machine parameters. The algorithm identifies when the current regulator begins to saturate and determines the optimum d-axis current command for the machine. The q-axis current command is determined as a function of the torque command and the d-axis current feedback. In the field-weakened region, the q-axis current is monitored not to exceed the maximum q-axis current. The maximum q-axis current is calculated based on the maximum slip frequency, which is a function of rotor frequency, q-axis current ges maximum q-axis current (in motoring mode) indicates that the machine entered field-weakened region II, and the q-axis current is limited to its maximum value. Experimental results from a machine prototype show that the algorithm provides good overall dynamic response and smooth transitions into the field-weakened region with maximum torque-per-ampere capability in all four quadrants of operation

Peak PWM current control of switched reluctance and AC machines

Fast response and insensitivity to parameter variation are among the most desired characteristics for current regulators in electric drives. This paper presents a new switching strategy with current regulation for switched reluctance machines (SRM), and the same concept is extended to other inverter fed AC machines to achieve instantaneous torque response. The technique is based on detecting the peak current in each phase and regulating the current by turning off the phase when the phase current reaches the commanded current, and turning on the phase at the leading edge of the clock signal at a fixed frequency. This peak-PWM current regulation (PPWMCR) strategy offers instantaneous torque response, fixed switching frequency, robustness, stability, inherent protection, no tuning, and simple implementation. The paper discusses detailed PPWMCR implementation for SRM and AC machines. Experimental results are presented to compare PPWMCR with hysteresis (HCR), delta modulation (DCR), and proportional-integral-PWM (PI-PWMCR) current regulators for a four phase SRM.

Comparison of full pitch and concentrated coil switched reluctance machines

While the switched reluctance machine (SRM) is traditionally a concentrated coil machine, efforts with full pitch windings have spurred interest. With the full pitch winding, twice the area of copper is energized at any given time as compared to the concentrated winding SRM, leading to potentially higher machine efficiency. This paper investigates the performance of 15 kW full pitch winding SRM under the following three current excitation patterns: unipolar, bipolar 120-degree conduction, and bipolar 180-degree conduction. In addition, the full pitch winding SRM is compared with the standard concentrated coil SRM. Finite element analysis (FEA) shows the highly nonlinear behavior of the mutual inductance of full pitch winding SRM. It is shown that the mutual inductance and self inductance change significantly depending on the current excitation patterns. Simulation results based on Simulink for each full pitch topology and concentrated coil SRM are presented at low and high speeds.

Optimum torque control of induction machines in the field-weakened region

This paper presents a novel current regulation algorithm for induction machines that enables maximum torque-per-ampere capability over the entire field-weakened region. The algorithm enables robust current regulation with maximum efficiency and torque capability despite significant variation in voltage source and machine parameters. The algorithm identifies when the current regulator begins to saturate and determines the optimum d-axis current command for the machine. The q-axis current command is determined as a function of the torque command and the d-axis current feedback. When the voltage angle reaches the maximum allowable angle, the output of the q-axis and the d-axis current regulators are clamped, and the slip frequency that provides maximum torque is maintained. Experimental results from a machine prototype show that the algorithm provides good overall dynamic response and smooth transitions into the field-weakened region with maximum torque-per-ampere capability in all four quadrants of operation