Research of braking mode of permanent magnet brushless motors without special brake devices

A subject of this paper is an automatic braking method of the permanent magnet brushless motors (PMBD) equipped with a two-stage frequency converter without special brake devices. The most important feature of the PMBD is an ability to control the position of stator current vector relative to the position of motor rotor field vector. An automatic voltage controller when braking limits the DC-link capacitor voltage to the safe level by the direct stator current component increase. Thus, the surplus of braking power is dissipated in motor stator windings. The proposed braking control approach minimizes the hardware of electric drives. Computation example of automatic braking process characteristics is given.