Magnetic optimization

A method of designing at least one coil for producing a magnetic field, comprising:

• i) setting a performance target comprising:
• a target magnetic field, and at least two of a target power, a target resistance, a target size and/or weight, a target supply voltage or current, and a target inductance;
• ii) determining initial design parameters for the at least one coil, wherein the at least one coil is designed simultaneously with at least one permanent magnet;
• iii) modelling performance with the current design parameters to determine a simulated performance against each of the performance targets, and the modelling includes the field of both the at least one permanent magnet and the field of the at least one coil;
• iv) calculating a penalty function based on the difference between the simulated performance and the performance targets;
• v) modifying the design parameters in order to reduce the penalty function, wherein the target magnetic field comprises a first target field corresponding with a first coil current, and a second target field corresponding with a second coil current;
• wherein modifying step comprising optimizing the permanent magnet and coil design to minimize the power consumed by the coil, based on a duty cycle of second target field relative to the first target field while producing same magnetic field;
• vi) iterating steps iii) to v) until the penalty function or simulated performance has met an acceptance condition.