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Design of a three phase four quadrant variable speed drive for permanent magnet brushless DC motorsDakora, Jonas-Yelee January 2016 (has links)
Submitted in fulfillment of the requirements for the Master of Engineering Degree, Department of Electronic Engineering, Durban University of Technology, Durban, South Africa, 2016. / The aim of this research project is to design a three phase four quadrant variable speed drive (VSD) for a permanent magnet brushless direct current motor (PMBLDC) that can be applied to an electric bicycle (e-bike). The design is confined to PMBLDC motors with a maximum power rating of 1.5kW. The speed controller operates in current mode at a maximum voltage and current rating of 50V and 30A, respectively. The VSD has the ability to smoothly control the current delivered to the DC motor and therefore controls its torque. The motor’s current is limited in all four quadrants of operation, and its speed is limited in the forward and reverse directions. The performance of the proposed DC motor VSD system is tested on an electric- bicycle.
The PMBLDC motor has three hall sensors embedded into the stator to determine rotor position. A phase switcher module interprets the position signals and produces a switching pattern. This effectively transforms the BLDC motor into a direct current (DC) brushed motor. The unipolar switching scheme used ensures that current flows out of the battery only for motoring operation and into the battery during regenerative braking. The current and torque are directly proportional in a BLDC motor. Torque control is achieved in the BLDC motor using a single channel current controller. The phase switcher current is monitored and used to control the duty cycle of the synchronous converter switches.
The proposed e-bike speed control system provides efficient control in all four quadrants of operation and it is a suitable alternative for a low cost transportation mode. / M
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Two-axis torque control of BLDC motors for electric vehicle applications.Shields, Bradley. 29 October 2014 (has links)
This thesis begins with a literature review focusing on electric vehicle (EV) applications. Systems
used for steering, braking and energy storage are investigated, with specific concentration on
torque control in various DC and AC motors commonly used in EVs. A final solution for a low range
personal transportation EV in the form of a wheelchair is proposed.
The theme for this thesis is motion control, focusing on a two axis (or two wheel drive) brushless
DC hub motor (BLDCHM) EV, with torque and direction control tracking a user reference. The
operation principle for a BLDCHM is documented and the dynamic and electrical equations
derived. Simulation results for motor response under different load and speed conditions are
compared to practical measurements. Current and torque control loops are designed, implemented
and tuned on a single-axis test-bed with an induction motor (IM) load coupled via a torque
transducer. A Texas Instrument DSP development kit is used for the control algorithm bench
testing.
The final control algorithm is then duplicated and expanded in simulation to form a dynamic two axis
system for an electric wheelchair. It incorporates both motor drive and regenerative
capabilities. After demonstrating two axis controls for BLDCHMs, a control algorithm is designed
simulated and compared to traditional systems. The final solution focuses specifically on an
intuitive response to the driver input whilst maintaining direction tracking, even when there is a
difference in smoothness of the individual terrains traversed by the left and right wheels. In
addition the motor drives are equipped with controllers that ensure regenerative braking in order to
recover as much energy as possible when the wheelchair is commanded to decelerate. / M. Sc. Eng. University of KwaZulu-Natal, Durban 2014.
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Detection of Rotor and Load Faults in BLDC Motors Operating Under Stationary and Non-Stationary ConditionsRajagopalan, Satish 23 June 2006 (has links)
Brushless Direct Current (BLDC) motors are one of the motor types rapidly gaining popularity. BLDC motors are being increasingly used in critical high performance industries such as appliances, automotive, aerospace, consumer, medical, industrial automation equipment and instrumentation. Fault detection and condition monitoring of BLDC machines is therefore assuming a new importance. The objective of this research is to advance the field of rotor and load fault diagnosis in BLDC machines operating in a variety of operating conditions ranging from constant speed to continuous transient operation. This objective is addressed as three parts in this research. The first part experimentally characterizes the effects of rotor faults in the stator current and voltage of the BLDC motor. This helps in better understanding the behavior of rotor defects in BLDC motors. The second part develops methods to detect faults in loads coupled to BLDC motors by monitoring the stator current. As most BLDC applications involve non-stationary operating conditions, the diagnosis of rotor faults in non-stationary conditions forms the third and most important part of this research. Several signal processing techniques are reviewed to analyze non-stationary signals. Three new algorithms are proposed that can track and detect rotor faults in non-stationary or transient current signals.
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