In order to solve the low precision problem of speed sampling circuit and complexity problem of applying encoder for brushless DC motor.Brushless DC motor control system based on CPLD six frequency multiplication speed collection is proposed.According to the characteristics of brushless DC motor with Hall sensor

three Hall signals are integrated logically by using CPLD to generate six frequency multiplication.The drive system took frequency-multiplier signals as speed feedback

and the precision of speed sampling is improved.The results of simulation and actual experiment is consistent with theoretical analysis.It proves the reasonability and validity of this method

and show that the precision of speed sampling is increased by 6 times.This novel method offers a new thinking for designing actual motor control system.