This paper presents a current blocking strategy of brushless DC (BLDC) motor drive to prolong the capacity voltage of batteries per charge in electric vehicle applications. The BLDC motor employs a simple torque hysteresis control (THC) that can offer a robust control and quick torque dynamic performance. At first, a mathematical modeling of BLDC motor and principle of torque hysteresis control will be described, so that the benefit offered by the proposed current blocking strategy can be highlighted. It can be shown that the current control method naturally provides current limitation, in which the current error (or ripple) is restricted within the pre-defined band-gap furthermore provide current protection. The benefit of proposed current blocking strategy will be highlighted such that it can prevent the current drained from the batteries when the torque demand is released to set to 0 Nm. The control scheme is validated and verified by the simulation and experimental results.
2. Brushless DC motor
3. Hall effect
4. Current controller
5. Electric vehicle (EV)
6. Hybrid electric vehicle (HEV)
7. Torque hysteresis controller (THC)
Fig 1. Structure of Optimal Current Control drive for BLDC motor.
CONTROL BLOCK DIAGRAM:
Fig 2. Proposed current blocking strategy based on hysteresis comparator
EXPECTED SIMULATION RESULTS:
Fig 3. Motor currents are controlled such that follow their references which are generated according to the hall effect signals (Time/div=0.5s/div).
Fig 4. Waveforms of output torque, speed and currents (a) THC without current blocking strategy (b) THC with current blocking strategy.
This paper presented the modelling and experimental result of THC for BLDC motor. The current controller has been applied to a BLDC drive and the results shows that the current ripple stays within the hysteresis band as defined by the controller. The proposed current blocking strategy shows that the energy wastage from the batteries is prevented such that it can prolong the capacity of voltage battery and it also showed that the hysteresis controller can offer inherent current protection/limitation and robustness in controlling the motor torque.
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 Norhazilina Binti Bahari; Jidin, Auzani bin; Abdullah, Abdul Rahim bin; Md Nazri bin Othman; Manap, Mustafa bin, "Modeling and simulation of torque hysteresis controller for brushless DC motor drives," Industrial Electronics and Applications (ISIEA), 2012 IEEE Symposium on , vol., no., pp.152,155, 23-26 Sept. 2012