Battery voltage-balancing applications of disk-type radial mode Pb(Zr•Ti)O3 ceramic resonator

In this paper, we propose a novel technique to build a charge-balancing circuit for series-connected battery strings using various kinds of disk-type ceramic Pb(Zr center dot Ti)O-3 piezoelectric resonators (PRs). The use of PRs replaces the whole external battery voltage-balancer circuit, which consists mainly of a bulky magnetic element. The proposed technique is validated using different ceramic PRs and the results are analyzed in terms of their physical properties. A series-connected battery string with a voltage rating of 61.5 V is set as a hardware prototype under test, then the power transfer efficiency of the system is measured at different imbalance voltages. The performance of the proposed battery voltage-balancer circuit employed with a PR is also validated through hardware implementation. Furthermore, the temperature distribution image of the PR is obtained to compare power transfer efficiency and thermal stress under different operating conditions. The test results show that the battery voltage-balancer circuit can be successfully implemented using PRs with the maximum power conversion efficiency of over 96% for energy storage systems. (C) 2017 The Japan Society of Applied Physics