A current-controlled variable inductor

The paper begins by looking at different techniques for implementing a variable inductor: moving cores, switched decade boxes, gyrator circuitry and saturable core reactors. We present the pros and cons of the different technologies and then the development of a saturable core reactor as the chosen technology. We present fundamental formulae used during the development of the variable inductor, test results for a number of developed prototypes, and the development of a highly-accurate control loop used to precisely maintain the value of the controlled inductance. The paper concludes with a brief discussion of the ATS that ultimately housed the variable inductor.