• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.11-14
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• 2001

Direct torque control (DTC) scheme provides a very quick torque response without the complex field-orientation block and inner current regulation loop. DTC is known as an appropriate scheme for high power induction motor drives because it can be used at lower switching frequency There are a major drawbacks with the application of DTC schemes it is large current harmonics due to flux drooping in a low speed range. In order to solve the problem, the fuzzy variable switching sector scheme are adopted in this paper. A meaningful contribution of this paper is to propose a simple realization scheme of the fuzzy variable switching sector technique. Experimental results show the effectiveness of this proposition.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1096-1106
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• 2013

This paper presents the control of a Permanent Magnet Electric Variable Transmission (PM-EVT) for Hybrid Electric Vehicles (HEVs). Consisting of two electric machines, the EVT realizes the power split function in an electromagnetic way rather than in a mechanical way. A specific PM-EVT has been designed for Toyota Prius II. The control scheme of the entire vehicle is deduced using the Energetic Macroscopic Representation methodology. The energy management strategy yields local control references. A specific attention is paid for the field weakening for wide speed range. Simulation results are provided to illustrate the EVT modeling and control.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.6
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• pp.971-981
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• 1994

In this paper, we consider feedback-linearizing control of VR (Variable Reluctance) motors which have been increasingly used in high performance direct-drive applications. We characterize all torque controllers that can make the generated torque of a VR motor linear to torque command but without torque ripple. The torque controlles maximize the range of torque commands which are admissible under the physical limitation in stator currents. The whole class of all such torque controllers is parameterized in the explicit form which contains a function to be chosen freely. This free function can be used to achieve other control objectives as well as linear dynamic characteristics. As the examples for optimal choices of the free function, we actually determine two optimal free functions, one for minimal rate of change in current commands and the other for minimal power loss due to stator resistance. To illuminate further the practical use of torque controllers proposed in this paper, we present some experimental results for the case of a commercially available VR motor.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.2
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• pp.138-144
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• 2006

Kinematic and dynamic characteristics of a Stewart platform based parallel manipulators are fixed once they are constructed. Thus parallel manipulators with various configurations are required to meet a variety of applications. In this research a parallel manipulator with variable platform (PMVP) has been developed, in which the length of the arm linking the platform center to the platform-leg contact point can be varied by an actuator. The workspace of the PMVP is larger than that of a traditional Stewart platform and especially the range in which the maximum orientation angles can be maintained is significantly expanded. Furthermore, the characteristics of force and moment transmission between the legs and platform can be adjusted to meet the requirements of various tasks. Kinematic and dynamics analysis was performed to verify the usefulness of the PMVP and the actual hardware was built to demonstrate the feasibility.

• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.61-64
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• 1993

We have constructed a hysteresis loop tracer in order to measure the magnetic properties of amorphous wires under variable tensile stress. It has a force range of 0 N to 20 N and a magnetizing frequency of 1 kHz to 20 kHz. Using the ac-hysteresis loop tracer, we can measure the magnetic properties(maximum magnetic induction $B_{max}$, residual magnetic induction $B_{r}$, coercive field strength $H_{c}$, etc.) of amorphous wires with precision of 1% under variable tensile stresses.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.576-578
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• 1989

This paper describes a new pwm scheme of variable speed control for induction motor. The proposed scheme have the programmed pwm switching pattern which have the doninant harmonic elimination over the wide range of output speed in induction motor. Experimental results of proposed scheme hare high quality output current, voltage and torque than that of conventional pwm scheme. Therefore proposed scheme have the smooth operation and suitable for variable speed control in induction motor.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.70-74
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• 2003

The buck-boost converter is employed as the variable output PFC power stage. From the loss analysis, this topology has a high efficiency from light load to heavy load. A modified input current sensing scheme is presented to overcome the problem of the insufficient phase margin for the PFC circuit near the maximum output voltage. The variable output PFC circuit has a good performance in the wide output voltage range, under both the Boost mode when the output voltage is high and the Buck+Boost mode when the output voltage is low.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.5-14
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• 2005

Continuously variable transmission (CVT) mechanisms combine the functions of a K-H-V type differential gear unit and a V-belt type continuously variable unit (CVU). For the 24 different mechanisms, 12 of them are power circulation modes while the other 12 are power split modes. Some useful theoretical formulas related to speed ratio, power flow and efficiency were derived and analyzed. These mechanisms have many advantages: they decrease CVT size and weight, increase overall efficiency, extend speed ratio range, and generate geared neutral. Compound CVTs were developed by combining the power circulation mode and power split mode, which can offer backward motion, geared neutral, underdrive and overdrive.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.549-552
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• 2003

In this paper, an efficient architecture of a versatile Reed-Solomon (RS) decoder is designed, where the message length k as well as the block length n can be variable. The decoder permits 3-step pipelined processing based on the modified Euclid's algorithm(MEA). A new architecture for the MEA is designed for variable values of error correcting capability t. To maintain the throughput rate with less circuitry, the MEA block uses both the recursive and the overclocking technique. The decoder can decode a codeword received not only in a burst mode, but also in a continuous mode. It can be used in a wide range of applications due to its versatility. A versatile RS decoder over GF(2$^{8}$ ) having the error-correcting capability of up to 10 has been designed in VHDL, and successfully synthesized in an FPGA chip.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.205-215
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• 2001

Continuously variable transmission(CVT) mechanisms considered here combine the functions of a 2K-H I type differential gear unit and a V-belt continuously variable unit(CVU). One shaft of the V-belt CVU is connected directly to the differential gear unit and remaining shaft of it is linked to the output shaft. These mechanisms have many advantage which are the decrease of CVT size, the increase of overall efficiency, the extension of speed ratio range, and the generation of geared neutral. In this paper six different mechanisms of output coupled type CVT are proposed. Some useful theoretical formula related to speed ratio, power flow and efficiency are derived and analyzed, and theoretical analysis are proven by various experiments.