A Hybrid Sensorless Observer for the Robust Global Asymptotic Flux Reconstruction of Permanent Magnet Synchronous Machines

We propose a hybrid sensorless observer for permanent magnet synchronous machines with global asymptotic stability guarantees. Exploiting the constraint of the rotor flux on a circle of unknown radius, we design an integrator system with periodic jumps triggered by a clock to generate a linear regression containing the flux estimation error. Then, a normalized projected gradient descent identifier provides the observer estimates. For the closed-loop system, it is shown that there exists a robustly globally asymptotically stable compact attractor, which, additionally, ensures zero estimation error if appropriate Persistency of Excitation (PE) conditions are satisfied. In this respect, sufficient conditions ensuring PE are provided for the angular speed and the clock period

Adaptive Observer for Three Phase Source Voltage Under Unbalanced Conditions

In this paper the problem of estimating amplitude, phase and frequency of the main component of three-phase line voltage under unbalanced conditions is considered. Unbalancing is a common condition and generates a so-called negative sequence in the line voltage, which may affect relevantly estimation of main components dynamics. Different adaptive schemes are proposed and analyzed. First of all, a straightforward solution derived by LTI observer with frequency adaptation is analyzed and its high sensitivity to negative sequence component is underlined. Hence, an adaptive nonlinear observer is proposed, exploiting the properties of a synchronous reference frame to represent the line voltage. Its larger robustness to negative sequence and voltage harmonics is verified by analysis and simulations. Finally, the latter solution is enhanced by adding the negative sequence model to the basic observer structure. This allows for perfect compensation if the unbalancing effects. Adaptation law for this solution is fairly different form the previous one and a completely different stability analysis is required. Simulation results are also provided to demonstrate the effectiveness of the proposed scheme even under large unbalancing

Speed Control for Medium Power Wind Turbines: An Integrated Approach oriented to MPPT

Maximum Power Point Tracking (MPPT) algorithms are receiving particular attention to maximize the wind energy captured by medium power wind turbines (a few hundreds of kW), whose aerodynamics curves are usually not known accurately and where wind-speed sensors are missing or not reliable. Wind turbine speed control, over a wide operating range, is usually assumed to give a reliable basis for most common MPPT algorithms. In this paper a novel simple, but effective, speed controller is presented. Speed control knobs, i.e. blade pitch angles and generator torque, are suitably combined in order to take into account generator torque and power limits without using hybrid controllers, which could lead to bumps and limit cycles under variable wind and uncertain aerodynamics characteristics. In defining torque and power limits at generator side, thermal dynamics are taken into account leading to time-varying bounds adopted in the proposed control solution. This allows a better exploitation of the generator capabilities, but still preventing from shut down related to thermal problems. A full stability analysis under unknown wind speed and uncertain aerodynamics curves is carried out showing how to tune the proposed controller, with a simple PI structure, for wide stability domain. A standard MPPT algorithm is mounted on top of the proposed solution, highlighting the constrains in shaping the speed reference trajectory to avoid motor behavior of the electric generator. Finally, simulations are reported to show the effectiveness of the proposed solution

Globally asymptotically stable reconstruction of flux, rotor position and speed for permanent magnets machines

An original full-order observer is presented for stator fluxes and speed reconstruction for Permanent Magnet Synchronous Machines. The estimation is carried out in a fixed reference frame exploiting the stator currents and voltages as the only known variables. Global asymptotic convergence properties of the proposed scheme are drawn, casting the estimation problem into adaptive systems theoretical framework. Insightful modification to the flux estimation dynamics is proposed in order to improve the observer performance in the low speed region. Simulation tests asses the features of the presented method

A UGAS Sensorless Observer for Permanent Magnets Synchronous Machines including Estimation and Compensation of Dead-Times Effects

In this work, a novel sensorless observer is proposed for Permanent Magnet Synchronous Machines, formally dealing with stator voltage actuation non-idealities. Rotor speed, position and stator fluxes, as well as the unknown parameters of the voltage perturbations are reconstructed considering a fixed reference frame for both the machine and the voltage actuator non-linear effects. Stator currents and commands for the voltage actuator are assumed to be the only known signals. The estimation scheme is proven to be Uniformly Globally Asymptotically Stable by means of rigorous results from adaptive systems theory. The effectiveness of this solution is validated by realistic simulation tests, including a detailed model of the power converter. Discretization of the presented solution is addressed accurately. A comparison is provided to show the advantages of the proposed observer against a solution which does not adopt any mechanism to compensate for the mismatch between ideal and actuated stator voltages

A Synchronous Coordinates Approach in Position and Speed Estimation for Permanent Magnet Synchronous Machines

A novel and simple observer scheme is proposed for rotor speed and position reconstruction for Permanent Magnet Synchronous Machines. The reference frame adopted in the observer is pushed toward the synchronous one by forcing it to be intrinsically aligned with the estimated back-emf vector and by designing suitable adaptations law for its speed and angle along with the back-emf amplitude. Stator flux dynamics are not used in this approach, leading to an improved robustness with respect to voltage and current measurement uncertainties. Stability analysis is carried out by using singular perturbation approach. Effective tuning rules are drawn exploiting insightful linearization of the proposed nonlinear adaptive observer. Simulations show the properties of the presented method

An Open-Source Scalable Thermal and Power Controller for HPC Processors

In the last decade, high performance multi-core processor designs have followed an increase in number of cores, interfaces, heterogeneity and System-on-chip (SoC) complexity. HPC applications also require tailored chip designs with specific operating points and performance indexes. In this scenario, an advanced and configurable Power Controller System (PCS) is necessary to meet power and thermal constraints, without the necessity of static ultra-conservative margins on the operating points. In this paper, we propose an open-source PCS design, based on a parallel ultra-low power microcontroller with RISC-V cores, and an open-source software environment based on a Real-time operating system (RTOS) with a configurable Power-thermal control algorithm. Considering a 1ms control interval, the overhead of the RTOS is about 6% of the cycles in the nominal case. The control algorithm is able to limit temperature and power consumption within given bounds, while maximizing performance. The PCS is able to control up to 76 different cores/computing units with headroom for larger core counts

A PULP-based parallel power controller for future exascale systems

Power management of digital circuits is raising of importance in a broad spectrum of computing domains. High-performance computing systems as the effect of the stop of Dennard's scaling have become power and thermal limited. In this manuscript, we evaluate the feasibility of using an open-source RISC-V based power controller for the high-performance computing market

An Open-Source Scalable Thermal and Power Controller for HPC Processors

In the last decade, high performance multi-core processor designs have followed an increase in number of cores, interfaces, heterogeneity and System-on-chip (SoC) complexity. HPC applications also require tailored chip designs with specific operating points and performance indexes. In this scenario, an advanced and configurable Power Controller System (PCS) is necessary to meet power and thermal constraints, without the necessity of static ultra-conservative margins on the operating points. In this paper, we propose an open-source PCS design, based on a parallel ultra-low power microcontroller with RISC-V cores, and an open-source software environment based on a Real-time operating system (RTOS) with a configurable Power-thermal control algorithm. Considering a 1ms control interval, the overhead of the RTOS is about 6% of the cycles in the nominal case. The control algorithm is able to limit temperature and power consumption within given bounds, while maximizing performance. The PCS is able to control up to 76 different cores/computing units with headroom for larger core counts