Linear Electric Machines, Drives, and MAGLEVs Handbook

15 Plunger Solenoids and Their Control

15.1 Introduction

Plunger solenoids are electromagnetic actuators with 1(2) dc- or ac-fed coils, without or with permanent magnets, with limited (from a few tens of mm to 10–20 mm) linear motion of a soft magnetic core (Figure 15.1a) or PM mover (plunger Figure 15.1b) via attraction or even repulsive electromagnetic forces. Plunger solenoids are also called electromagnets and are used extensively in standard applications such as electric power switches (relays), door lockers etc., enjoying substantial worldwide markets.

Reference [1] presents a classical study of electromagnets.

Essentially, for plunger solenoids, on–off supply control is used as the forward motion is secured by the electromagnetic force ...