Chan H. Ham

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Based on the Lyapunov's direct method, a new learning control design is proposed. The proposed technique can be applied in two ways: it is either the standard backward recursive design or its extension. In the "rst case, the design yields a class of learning control with a di!erence learning law, under which the class of nonlinear systems is guaranteed to(More)
This paper presents the development of an ultra-high-speed permanent magnet synchronous motor (PMSM) that produces output shaft power of 2000 W at 200 000 rpm with around 90% efficiency. Due to the guaranteed open-loop stability over the full operating speed range, the developed motor system is compact and low cost since it can avoid the design complexity(More)
This paper presents the design and simulation of a superhigh-speed permanent magnet synchronous motor (PMSM) that operates in the cryogenic temperature of 77 K. The designed PMSM is used to drive a two-stage cryocooler for zero boil-off and long duration storage of liquid hydrogen systems. The paper addresses electromagnetic and thermal finite-element(More)
In this paper, a systematic procedure to design the robust ∞ H fuzzy controller for a nonli-near active magnetic bearing (AMB) system affected by time-varying parametric uncertainties is presented. First, the continuous-time Takagi-Sugeno (T-S) fuzzy model is employed to represent the non-linear AMB system. Next, based on the obtained fuzzy model,(More)
This paper presents the design and implementation of a DSP-based controller for a super high-speed (>80,000 rpm) permanent magnet synchronous motor (PMSM). The PMSM is a key component of the centrifugal compressor drive of a reverse Brayton cryocooler that is currently under development for NASA and Florida Solar Energy Center. The design of the PMSM(More)
Flywheel energy storage (FES) devices have been a popular method of energy storage because of their low maintenance requirements and ability to charge and release substantial amounts of energy in a short period of time. The amount of energy stored in an FES device mainly depends on the angular velocity of the rotor. The objective of the rotor design is to(More)
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