In the old days, motors used to be started by hand with a removable crank handle or other varius method. Fortunately, nowadays motors are started automatically by what is called a starter motor.
Starter motors are generally speaking a permanent magnet (usually ferrite sectors) direct current electric motor that is coupled directly to the engine. As the engine runs, it charges a battery that will power the starter motor when needed.
Requirements for the permanent magnets are high for starter motors; higher than any other direct current permanent magnet electric motor.
- A high magnetic density and resistance to demagnetization.
The motor has to be able to supply a high torque in order to be able to move and ultimately start the heavy engine. This can either be archieved by a high current intensity or by high magnetic density permanent magnets.
High current intensity means a high magnetic field going through the coils of the rotor and therefore a risk of demagnetization of the permanent magnets.
Ferrite permanent magnets can provide a high magnetic density and a strong resistance to demagnetization while being economically cheap. It is the material of choice for starter engine applications.
- A strong flux
The shape of the magnet has to be optimized in order to have the highest magnetic flux going between the rotor and the permanent magnets. A cylinder shape or sector shape is wildely used in this kind of application.
One can easily understand the importance of the quality of the permanent magnet in the speakers. It must be able to provide a strong field while having reduced dimensions and a relatively low cost.
We at Ugimag are working every day with OEM of automotive starter motors to supply them with millions of ferrite sectors permanent magnets for their starter motor applications.
We are always innovating with them, developping new materials and design to improve the starter DC motors and generally speaking all applications with highly optimized permanent magnets.
Please contact us and we will be happy to study your application with you.