It all started when we couldn’t get the permanent magnet generator (PMG) we’d ordered from China. That led us to find a horizontal axis wind turbine PMG from Soga in Italy that had been ordered but never delivered. We were lucky because we could get the generator right away instead of waiting five months for them to make a new one. So we bought it and adapted it to our turbine by turning it on its side.  

Soon after installing it, we learned that its brake disk below the generator was problematic. We ended up moving it to fit between the driveshaft and the coupler that connects the driveshaft to the PMG. It worked, but our team’s analysis of the data showed something was wrong. One of the caliper brakes was rubbing against the disk.  

Last week, our engineers solved the problem by adding 2mm shims to widen the gap between the calipers and the brake disk. We’d initially set the tolerances too tight.  

Lower wind speed data collected immediately after the fix showed the turbine’s energy output increased by 5kW. Without the caliper rubbing, the turbine’s cut-in wind speed (the wind speed needed to start generating electricity) changed from 5m/s to 4.5m/s.  Both of these improvements matched our modeling predictions for power performance.  With a couple more weeks of methodical testing, we should confirm the improvements in the higher wind speeds and have a final power performance curve for third-party review and then publication. 

One of the benefits of facing problems and overcoming challenges is that we learn a great deal more than if those problems hadn’t occurred. We wish everything were perfect in our prototype, but the lack of perfection has its silver linings.

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