SDFT-QTPLL Based Position Sensorless BLDCM Drive With Regenerative Braking For Solar-LEV

This paper presents the design and control of an improved position sensorless BLDC motor drive using sliding discrete Fourier transform (SDFT)-quadrature tangent (QT) phase-locked loop (PLL) for solar and battery-powered light electric vehicle (LEV). Conventional position estimation methods of BLDC motor using back-EMF and line voltages of the motor are not suitable for low and medium speed ranges. Moreover, the usage of low-pass filter attenuates the back-EMF magnitude and induces a phase lag, which is corrected using a lead compensator or making a filter cutoff frequency a variable for different speeds. Here rotor position is extracted directly from the line voltages using SDFT-PLL logic, which is proven to be applicable in a wide speed range. It is found that the phase of the PLL coincides with the rotor angle and is used for rotor position extraction. SDFT algorithm has an inherent filtering ability for fundamental extraction with harmonics rejection and also eliminates DC offset. Furthermore, a modified boost converter with an input/output current continuous is introduced for MPPT operation of solar-PV array. Regenerative braking and solar-PV array help to increase driving range making overall powertrain more energy efficient.