## 4 Experimental Testbench  
MATLAB/Simulink and the experimental platform are used to develop and implement, respectively, a laboratory prototype of the system, shown in Figure 9. For experimental validation, a 48 V, 850 W BLDCM, single-speed and with 7:1 gear arrangement, commonly used in three-wheelers, is employed. The specifications of the BLDCM are provided in Table 2. The motor is capable of producing up to 1.25 kW of power at its peak. The experimental setup comprises a PV emulator (solar simulator) to replicate the characteristics of a solar panel under varying irradiance conditions, providing a variable DC input to the SEPIC used as the DC/DC converter. The maximum solar power delivery is 420 W. The SEPIC is configured for MPPT and regulates the voltage supplied to the system. The switching frequency of the converter is 20 kHz. A 48 V, 100 Ah, lithium-ion battery pack serves as the energy storage unit, interfaced with the converter to support motoring and regenerative braking operations. The BLDCM is driven by a three-phase 10 kW VSI, controlled by a microcontroller (dSpace controller) that implements the sensorless QPLL-based back-EMF observer for rotor position estimation. Additional sensors are integrated to monitor phase currents, back-EMF voltages, and system performance metrics such as speed and torque. The feedback signals are acquired via analog-digital converters (ADCs) \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Value** & **Units** \\ \hline Rated power & 850 & W \\ Peak power & 1250 & W \\ Rated voltage & 48 & V \\ Rated current & 21 & A \\ Peak current & 50 & A \\ Rated speed & 3000 & rpm \\ Stator per-phase resistance & 0.18 & \(\Omega\) \\ Stator per-phase & 50 & mH \\ inductance & 2.7 & Nm \\ Peak torque & 20 & Nm \\ Pole pairs & 2 & \\ Inertia & 0.02 & kg\(\cdot\)m\({}^{2}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: BLDCM specifications. Figure 9: Experimental laboratory prototype. at a sampling rate of 20 kHz. The controller generates the final switch pulses for the VSI while processing inputs from voltage and current sensors, as well as the PWM signals for the SEPIC. A DC machine coupled to the BLDCM acts as a vehicle load emulator. Standard drive cycles of a light three-wheel EV vehicle, based on the characteristics of Table 3, are used as reference speed commands for load control. Figure 10 illustrates a simplified architecture of the overall vehicle control system. The system controller encompasses the primary drive structure, serving as the central component of the system. To replicate vehicle dynamics, both the drive cycle and the accelerator pedal are used as inputs to the controller. The drive cycle is employed to validate controller performance by comparing it to a preset reference speed command. Alternatively, the accelerator pedal provides an additional input method. The degree of pedal pressure determines the estimated reference torque command, which is then transmitted to the \"driver mode\" block. This block selects either the drive cycle or the accelerator mode as the input command to the motor controller block. The tests were conducted under a variety of operating scenarios to evaluate the system's performance. Motor operating conditions included a wide speed range, with particular focus on the lower range (from 100 to 1000 rpm). Steady-state operation tests were performed with constant speed, as well as dynamic tests with varying speed. Load torque was varied by controlling the DC generator, emulating the typical operating con  
Figure 10: Comprehensive drive train structure of BLDCM-driven light EV. \begin{table}
\begin{tabular}{c c} \hline \hline
**Component or Characteristic** & **Value or Type** \\ \hline Propulsion type & Electrical, 850 W BLDCM \\ Drive mode & Torque control \\ Maximum speed & 25 km/h \\ Wheel diameter & 304.80 mm \\ Vehicle dimensions & 2850 \(\times\) 1050 \(\times\) 1800 mm \\ Net weight & 190 kg \\ Peak loading capacity & 400 kg \\ \hline \hline \end{tabular}
\end{table}