Energization system for linear motor transient reduction

Abstract

In a linear motor comprising a moving body and a plurality of electromagnets arranged along the path of the moving body, the electromagnets are divided into blocks, each block comprising one or more electromagnets which are energized simultaneously. The blocks are energized sequentially with the time lag between energizations of sequentially energized blocks being sufficient to allow the current in each block to reach substantially its steady state level before the next block is energized. When starting the linear motor, a first block is energized, and a transient state occurs in which the current drawn by the first block is higher than the steady state current drawn by the first block. At the end of the transient state of the first block, a second block is energized. Third and fourth are energized similarly, each block being energized only when the transient state of the preceding block is substantially over, i.e. when the current drawn by the preceding block is substantially at its steady state level. The blocks are sequentially deenergized so that the total current drawn on the power supply is limited to the steady state current of two blocks plus the transient current of one block.