Considerations on the Angular Error Due to the Shaft Eccentricity and the Compensation Effect by Short-Circuit Winding on a Resolver

When a built-in resolver is incorporated into a motor shaft, there is sometimes a problem of an eccentricity error caused by mounting misalignment and tilting. This eccentricity error affects the sensing accuracy of the resolver and causes an angular error. A short-circuit winding applied in quadrature to the exciting winding helps to reduce the angular error due to the shaft eccentricity if the internal impedance of the short-circuit winding is optimally designed. This paper (1) analyzes the mechanism whereby the angular error leads to an error equation, (2) analyzes how the short-circuit winding reduces the magnetic flux in the quadrature axis, which acts to induce the angular error, and (3) clarifies the conditions for realizing a resolver error of under 10' at an eccentric rate (δ/g×100%) of under 50%.