Single-Sided Magnetic Field Apparatus

Technology #16611

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Professor Steven Leeb
Department of Electrical Engineering and Computer Science, MIT
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Al-Thaddeus Avestruz
Department of Electrical Engineering and Computer Science, MIT
Arijit Banerjee
Department of Electrical Engineering and Computer Science, MIT
Arthur Chang
Department of Electrical Engineering and Computer Science, MIT
Shahriar Khushrushahi
Department of Electrical Engineering and Computer Science, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Method and Apparatus for Producing an Asymmetric Magnetic Field

US Patent Pending 2015-0116887
Uniform Single-Sided Induction Heating Using Multiphase, Multi-Resonant Halbach Windings
IEEE, March 2014, p. 844
Single-Sided AC Magnetic Fields for Induction Heating
IEEE, November 2013, p. 5052


This technology can be applied to any magnetic induction system that could benefit from an efficient single-sided magnetic field.  Examples include induction cooking and wireless power transfer such as phone charging.

Problems Addressed

Magnetic induction systems often require a targeted AC (alternating current) magnetic field that is strong on one side while weak on another.  Such magnetic fields can be created by magnetic shields but the shields are often bulky, heavy, and expensive.  This technology  eliminates the need for such shields by efficiently generating single-sided magnetic fields.  This technology can also generate traveling magnetic fields capable of heating induction surfaces uniformly.


This invention uses multiple layers of conductive windings coupled to a drive to generate asymmetric  magnetic fields.  The windings are stacked and arranged so that the magnetic field generated by each winding layer adds on one side of the stack and cancels on the other side.  The net magnetic field is thus much higher on one side than the other, allowing the magnetic field to be directed towards a target efficiently.  This eliminates the need for bulky magnetic shielding and the associated weight and cost.  Each layer in the winding stack can be driven at a different frequency to create a traveling magnetic field that will produce a uniform heating profile for induction cooking.


  • Efficient generation of single-sided magnetic field
  • No magnetic shielding required 
  • Uniform induction heating