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 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)
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)
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)
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