1,721,084 research outputs found
SISTEMA DI PROPULSIONE PER VELIVOLO E METODO DI CONTROLLO DEL SISTEMA DI PROPULSIONE PER VELIVOLO
Full text linkBrevetto per invenzione industriale intitolato "Sistema di propulsione per velivolo e metodo di controllo di sistema di propulsione per velivolo". Titolari: Politecnico di Torino, Torino; Alenia Aermacchi S.P.A., Venegono Superiore (VA). Inventori: Ronchetto Davide, Chiesa Sergio, Ragusa Carlo Stefano, Armando Eric Giacomo, Farfaglia Salvatore
Sensorless Synchronous Reluctance Motor Drives: Auxiliary Flux based Position Observer
Full text linkThe concept of auxiliary flux vector is defined for the nonlinear magnetic model of a synchronous reluctance (SyR) machine. An auxiliary flux based position observer is developed to circumvent the stability problems of other schemes, notably active flux position observer, without compromising on the simplicity. Stability analysis and sensitivity to parameter errors are presented. The proposed observer is augmented with high-frequency signal injection based position estimation for sustained operation at low speeds region. Proposed technique is experimentally validated on a 1.1 kW SyR machine test bench
Direct Flux Vector Control of Synchronous Motor Drives: Accurate Decoupled Control with Online Adaptive MTPA and MTPV Evaluation
Full text linkDirect flux vector control (DFVC) has an unique advantage in facilitating flux-weakening operation due to the choice of controlled variables: stator flux linkage magnitude and torque producing current. However, the dynamics in stator flux oriented reference frame is heavily affected by the nonlinear cross-coupling between the two axes. This paper presents a nonlinear transformation method to decouple the axes for a uniform bandwidth at all operating points. Respect to the literature, the proposed transformation takes magnetic saturation into account without approximation. Furthermore, the auxiliary-flux and auxiliary-current vectors are introduced to design a new adaptive evaluation of maximum torque per ampere (MTPA) and maximum torque per volt (MTPV) control laws, enabling to track the optimal control laws without the need for pre-processed look-up-tables (LUTs). The proposed scheme is experimentally validated on a 1.1 kW synchronous reluctance (SyR) machine test bench
Electric Loss Measurement Technique for Synchronous PM Brushless Machines
No full textA novel technique to identify, by direct electric measurements, the total losses at full load in synchronous permanent-magnet brushless ac machines is here presented. The proposed procedure can anyway be extended to anisotropic machines. The procedure adopts a back-to-back electric and mechanic connection capable to use a single three-phase power converter to perform a full power test. The coupled motors are driven in speed as an equivalent electric machine at no load. The motor load can be regulated by the physical angular displacement in between the rotors of the two machines, and the converter will control the speed and equalize the current amplitude in the motors. In this condition, the motors exchange active power at the shaft in mechanical form and at the electric connections in electrical form. The active power supplied by the converter in steady state results in the total power dissipated by the two motors. A simple algorithm to identify the current-to-mechanical angle relationship at a given speed is proposed. The measurement technique is simulated and verified using an experimental test bench that adopts two low-power high-torque electric machines
Inverter Side RL Filter Precise Design for Motor Overvoltage Mitigation in SiC Based Drives
No full textThis study investigates the use of resistor-inductor (RL) filters for motor overvoltage issues caused by cables connecting inverters to electric machines. Using existing filter design formulae and fixing the desired peak motor voltage, an RL filter was designed for a 15 kW industrial drive. This filter was used with a Si IGBT inverter and a matching between the design targets and the experimental results was found. Using the same filter with an SiC MOSFET inverter, a detrimental effect in overvoltage mitigation task was found. From simulations, it was noticed that combination of filter resistor parasitic inductance and high dv/dt causes unpredicted additional high-frequency motor overvoltages. These phenomena require higher filter inductance values with respect to the standard one, thus previous filter design formulae cannot be used. New design formulae, valid when inverters with high dv/dt are used, are proposed and experimentally validated. Interestingly, using the proposed formulae, it was discovered that the best filter resistance is not equal to the characteristic impedance of the cable. A design guideline that permits to optimally design the RL filter without simulation tool, considering the resistor parasitic inductance and the inverter dv/dt is finally proposed
Direct Flux Vector Control of Synchronous Motor Drives: A Small-Signal Model for Optimal Reference Generation
Full text linkA novel Direct Flux Vector Control (DFVC) scheme is presented based on the real-time use of the motor small-signal model for optimal reference generation without pre-processed look-up tables (LUTs). The control scheme is valid for Reluctance- and PM-Synchronous machines. The stator flux magnitude and the load angle are the controlled variables and the optimal reference values respecting maximum torque per ampere (MTPA), maximum torque per volts (MTPV), voltage and current limit conditions are computed in real-time from the small-signal model. Analytical expressions of MTPA and MTPV criteria are derived to enable online adaptation according to the small-signal approximation of the motor model. The motor parameters reside in the flux-map LUTs used in the flux observer; besides that, no additional tables are necessary. Furthermore, online parameter adaptation is proposed to further improve torque tracking accuracy against flux-map LUTs errors. The feasibility of proposed scheme is demonstrated through experiments on a 1.1. kW synchronous reluctance (SyR) machine test-bench. The proposed control scheme simplifies the implementation and calibration of the DFVC, while improving its MTPV control and its roughness against model parameter errors. Prospective fields of application are spindle and traction drives
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