公开(公告)号：US09604666B2

公开(公告)日：2017-03-28

申请号：US14777547

申请日：2013-03-18

Applicant: NSK LTD.

Inventor： Sachio Nakayama ,  Toru Sakaguchi ,  Yuzuru Hoshi ,  Shinichi Tanaka ,  Masanori Shingou

IPC: B62D5/04

CPC classification number: B62D5/0463 ,  B62D5/0481

Abstract: An electric power steering apparatus that protects Zener diodes without impairing steering performances by time-integrating a loss power of the Zener diodes for protecting FETs and gradually limiting a duty ratio with an increase in an integrating loss. The apparatus includes a loss power calculating section that calculates a loss power when a difference between an ignition voltage and an inverter applying voltage is equal to or more than a predetermined voltage; an integrating loss calculating section to calculate an integrating loss of the loss power; a permissible loss calculating section to calculate a permissible loss based on a temperature; a minimum value selecting section to select a minimum value of a loss difference of the permissible loss and the integrating loss; and a limit value calculating section to calculate a limit value of the PWM-signal based on the minimum value of the loss difference and the permissible loss.