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Indian scientists have designed a water pump drive system that runs exclusively on photovoltaic energy. It appears that the proposed system configuration ensures efficient use of both the solar modules and the motor.
Researchers in India have developed a novel photovoltaic-powered open-wound induction machine (OWIM) for pumping water in agriculture.
In an OWIM system, the end points of each phase are separated, allowing for more flexible control and operation of the motor. “This configuration facilitates the optimal arrangement of solar panels, eliminates the need for large strings and improves the performance of solar systems by allowing a wide operating voltage range,” explains the research group. “In addition, reducing the nominal potentials of the DC link capacitances and switching elements of the scheme results in cost savings.”
The scientists performed numerical modeling of the system using MATLAB software. It consisted of photovoltaic panels with a combined capacity of 3.65 kW, dual inverters that enabled the functionalities of three-level inverters while using lower value DC bus voltages, and a three-phase OWIM with 4, 2 kW. Additionally, they included a maximum power point tracking (MPPT) controller that uses pulse width modulation (PWM) and modified particle swarm optimization (MPSO) algorithms.
“This algorithm creates the PWM controller pulses necessary for dual segmented inverters,” they stressed. “The MPPT technique maximizes power extraction from the solar source for efficient utilization. The PWM integrates V/f controls, keeping the rated flux fixed in the machine to optimize torque capacity. “This ensures maximum utilization of the photovoltaic source in pump drive applications where torque depends on speed.”
This switching algorithm is reportedly able to calculate the activation time of the upper switches of one of the two inverters, while the activation period of the second inverter is directly obtained using its activation time. “In addition, the control system only needs to detect solar voltage and current, which reduces the number of sensors and improves the simplicity and cost-effectiveness of the system,” underlines the research group.
The academics simulated the operation of the system under different conditions, such as temperature and irradiation. “A notable observation is the presence of ripple content in the motor phase current and torque waveforms, which corresponds directly to milliamps. Torque ripple is very pronounced under conditions of reduced insolation and decreases as insolation increases,” they said.
Furthermore, they found that the systems total harmonic distortion (THD) performance improves with higher PV power. “By examining the result, the dynamic behavior of the system can be observed, which illustrates how the proposed solution using OWIM and double inverters responds during operation,” they concluded.
Their conclusions are presented in the published article “ A novel approach for solar combined open-ended winding induction machine for agricultural water pumping applications .” in Measurement: Sensors . The research was carried out by scientists from Inbdias Karunya Institute of Technology and Jyothi College of Engineering. |
