Direct control of air-gap flux in permanent-magnet machines

A new field weakening and adjustment technology for PM machines by direct control of air-gap fluxes is introduced. This new technology requires no current decomposition by the inverter eliminating the need for a position sensor. Demagnetization, which normally occurs during field weakening, does not occur with this new method. The field-weakening ratio can reach 10:1 or higher. This technology is robust and particularly useful for, but not limited to, electric vehicle drives and PM generators.