Temperature Effects on a Simplified Self-Sensing Actuation Circuit for PZT Micro-Actuator in HDDs

This paper presents a simplified self-sensing actuation (SSA) circuit design to allow easy balancing and implementation for using the piezoelectric (PZT) micro-actuator in a hard disk drive (HDD) as both an actuator and a sensor simultaneously. Since temperature variation in HDDs can cause errors in the sensing signal, the effects of the temperature changes on the sensing signal measured by the proposed SSA circuit were studied. In simulations, the frequency response results of circuits demonstrate that the proposed SSA circuit had similar characteristics to the conventional SSA circuit. In experiments, the proposed SSA circuit was tested with the PZT micro-actuator in an HDD at temperatures from 10 °C to 60 °C. At the balancing condition 30 °C, the results show that the proposed SSA circuit did not affect the conventional read/write (R/W) head positioning control system. The frequency response of the PZT micro-actuator measured by the proposed SSA circuit was closely related to the frequency response of the R/W head displacement. In temperature effect tests, the experimental results show that the sensing signal errors linearly related to the absolute temperature change from the balancing point.