The design and implementation of a linear brushless DC motor (LBDCM) drive
with robust position control are presented. Hall-effect sensors and linear
encoders are employed to obtain information of moving member position. A si
mple but practical zeroing approach is proposed to correct the phase errors
of current commands due to the mechanical installation misalignment of Hal
l-effect sensors. Then a current-controlled PWM inverter is properly design
ed to yield excellent armature current tracking control characteristics. As
to position control, the dynamic model of the LBDCM drive is first estimat
ed from measurements. Then a two-degrees-of-freedom controller is quantitat
ively designed to meet the given position-control specifications. A robust
controller is designed to reduce the control peformance degradation due to
system parameter changes and the effect of cogging force. Simulated and mea
sured results are provided to demonstrate the driving performance of the wh
ole linear motor drive.