Controlled Dynamic Braking for Switched Reluctance Motor Drives With a Rectifier Front End

Switched reluctance motors (SRMs) have ease of manufacturing, low cost, and robustness in withstanding centrifugal force advantages. Therefore, they are very suitable for high-speed applications. However, when running at high speeds, rapid braking becomes difficult because the regeneration energy may increase the dc-link voltage to a critical level if a diode rectifier bridge is used for ac-dc conversion. This paper investigates the relationship between the regeneration energy and the dc-link voltage and proposes an electric braking scheme employing two-phase excitations. During braking, instead of regenerating the excessive rotor kinetic energy back to the dc link, the energy is dissipated in the stator winding resistance. Therefore, the rotor can stop safely within a short time. The proposed control scheme is verified experimentally using a four-phase SRM.