Electromagnetically actuated active balancer with flux guides

Use of flux guides in order to increase force/current ratio in electromagnetically actuated active balancer is proposed and experimentally verified. The active balancer is in a shape of ring with a number of grooves displaced around axis of rotation. Steel balls are placed into the grooves and electromagnet actively controls the movement of the steel balls. The electromagnet is activated to generate force on a steel ball, so as to displace it and to vary the balancing status. Proposed flux guides are placed above and below the grooves. Presented results show that use of flux guides doubles force/current ratio by reducing the required driving current by 50%. Main advantages of this type of balancer are in its high sensitivity, complete control over the balancing process, and low sensitivity to operational speed. In addition, no power is required to maintain the balanced, state, and it can operate in both vertical and horizontal position. Active balancers are very attractive to be used in applications where rotational imbalance frequently varies, for example in servo pack writers used in hard disk drive industry. Imbalance can affect positioning accuracy of the read/write head element, result in disc slippage and excessive wear of bearings.