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diy solar

Appropriate generator characteristics for small wind turbine


New Member
Jan 25, 2024
Hello guys. I am working on a project that aims to implement an MPPT controller for a small wind turbine and evaluate the performance gain compared to having no MPPT. I have built a wind turbine prototype using pvc pipes for rotor blades, 3d-printed rotor hub and nacelle, and a metal pole tower. It is probably not the best wind turbine out there, but I think it will be sufficient for testing the controller. I have a PMSG that I want to use, but I am unsure if it fits the application. I am studying digital and embedded electronics, so I am a bit unfamiliar with electrical machines. Here is my thought process:

The prototype has a rotor radius R=0.6 m, and I will assume an efficiency Cp= 0.25 (while operating at the optimal tip speed ratio). For a wind speed Vw=10 m/s, the output power is P=Cp*(1/2)*ρ*π*R^2*Vw^3=173 W where ρ is the air density (1.225 kg/m^3). If the optimal tip speed ratio if TSR=7, it means that the rotor tip speed is Vr=70 m/s, which leads to an angular velocity of ω=116 rad/s and RPM=1114. The voltage constant of my PMSG is Kv=8.18 V/kRPM, which means that the output voltage is 9.11 V. Since the output power is 173 W, the output current will be 19 A.

It seems to me that it would be beneficial to operate at a higher voltage/RPM to avoid high currents so that the power electronics will be easier and cheaper. I'm thinking of using a three-phase uncontrolled rectifier, and maybe a boost converter to implement MPPT by controlling the load with the PWM signal. Ideally, I am able to find modules for these so that I can focus on the control logic (sensors and MCU programming). Gears don't make sense for a wind turbine of this size. Should I have a different generator? What should I look for? A PMSM with a higher Kv? Or are such current values normal/acceptable?