• Journal of Power Electronics
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• v.8 no.4
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• pp.332-344
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• 2008

High frequency AC (HFAC) power distribution systems delivering power through a high frequency AC link with sinusoidal voltage have the advantages of simple structure and high efficiency. In a multiple module system, where multiple resonant inverters are paralleled to the high frequency AC bus through connection inductors, it is necessary for the output voltage phase angles of the inverters be controlled so that the circulating current among the inverters be minimized. However, the phase angle of the resonant inverters output voltage can not be controlled with conventional phase shift modulation or pulse width modulation. The phase angle is a function of both the phase of the gating signals and the impedance of the resonant tank. In this paper, we proposed a pulse phase modulation (PPM) concept for the resonant inverters, so that the phase angle of the output voltage can be regulated. The PPM can be used to minimize the circulating current between the resonant inverters. The mechanisms of the phase angle control and the PPM were explained. The small signal model of a PPM controlled half-bridge resonant inverter was analyzed. The concept was verified in a half bridge resonant inverter with a series-parallel resonant tank. An HFAC power distribution system with two resonant inverters connected in parallel to a 500kHz, 28V AC bus was presented to demonstrate the applicability of the concept in a high frequency power distribution system.

• Journal of Power Electronics
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• v.7 no.1
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• pp.81-88
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• 2007

This paper presents a new approach to the automatic control of the turn-off angle used to excite the Switched Reluctance Motor (SRM) employed in electric vehicles (EV). The controller selects the turn-off angle that supports and improves the performance of the motor drive system. This control scheme consisting of classical current control and speed control depends on a lookup table to take the best result of the motor. The turn-on angle of the main switches of the inverter is fixed at $0^{\circ}C$ and the turn-off angle is variable depending on the reference speed. The motor, inverter and control system are modeled in Simulink to demonstrate the operation of the system.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.752-755
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• 2000

This paper describes a new algorithm for active power filters which can be control source current symmetrically under unbalanced condition in power system. Positive sequency voltage is detected by symmetrical coordinate method and compensating reference current of active power filters is calculated using by accurate phase angle information of positive sequency voltage. The basic principle of the proposed method is described in detail and the conventional and proposed phase detecting methods are compared and discussed through the simulation results.

• International Journal of Automotive Technology
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• v.7 no.6
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• pp.681-686
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• 2006

The current flat type side slip tester measures only the total side slip. Therefore, measurement techniques which can be used to determine the side slip for each alignment element were examined. Because the side slip related to the camber angle varies depending on the unit load per travel wheel while the side slip related to the toe angle does not on the unit per travel wheel, but depends only on the direction of the tire, the side slip for each alignment element can be determined separately.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.6
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• pp.619-625
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• 1997

In this paper, we show that the rotor position of the bifilar-wound hybrid stepping motors for the closed-loop drives is detected by the phase current measurement. We propose an instantaneous phase current equation, which is the function of electrical angle, by modeling the stepping motor including motor driving circuits. We also analyze the relationship between phase current and rotor position from the computer simulation results. We show that the information about the rotor position is obtained from the phase current amplitude and its derivatives at the instance of ${\pi}/2$ electrical angle of excitation voltage.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.351-354
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• 2001

In this paper, we present self-tuning control of switched reluctance motor for maximum torque with phase current and shaft position sensor. Determination method of turn-on/off angle is realized by using self-tuning control method. During the sampling time, micro-controller checks the number of pulse from encoder and compare with the number of pre-checked pulse. After micro-controller calculates between two data, it moves forward or backward turn-off angle. When the turn-off angle is fixed optimal turn-off angle, the turn-on angle automatically moves forward or backward by a step using self-tuning control method. And then, optimal turn-off angle is searched once again. As such a repeating process, turn-on/off angle is moved automatically to obtain the maximum torque. The experimental results are presented to validate the self-tuning algorithm.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.5
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• pp.310-316
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• 2013

This paper reports a sinusoidal $180^{\circ}$ drive for a permanent magnet (PM) brushless motor employing automatic angle compensator to suppress the driving loss during the wide-range load operation. The proposed drive of the sinusoidal $180^{\circ}$ PM Brushless motor reduced the amplitude of the 3-phase current by compensating for the lead-angle of the fundamental waves of the 3-phase PWM signal. The conventional lead-angle method was implemented using the fixed angle or memorized table, whereas the proposed method was automatically compensated by calculating the angle of the current and voltage signal. The algorithm of the proposed method was verified in a 30 W PM brushless motor system using a PSIM simulator. The efficiency of the conventional method was decreased 90 % to 60 %, whereas that of proposed method maintained approximately 85 % when the load shift was 0 to $0.02N{\cdot}m$. Using an FPGA prototype, the proposed method was evaluated experimentally in a 30 W PM brushless motor system. The proposed method maintained the minimum phase RMS current and 79 % of the motor efficiency under 0 to $0.09N{\cdot}m$ load conditions. The proposed PM brushless motor driving method is suitable for a variety of applications with a wide range of load conditions.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.222-229
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• 1999

In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ration using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to cutting torque acting on a single tooth at the swept angle of cut and can be acquired form cutting torque signals. Average cutting torque per revolution can also be calculate form cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current.

• Journal of Welding and Joining
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• v.27 no.4
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• pp.67-72
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• 2009

In this paper, arc characteristics of V groove joints using pulsed GMA welding were found out. The bevel angles of $22.5^{\circ}$ and $30.0^{\circ}$ were chose to make the V groove configuration with the groove angles of $45^{\circ}$ and $60.0^{\circ}$, respectively. In the experiment, the arc current waveform measurement and the high speed photography were taken to investigate the arc characteristics for a single-beveled asymmetric workpiece. Consequently, the welding current was changed abnormally around the edge of groove. As the arc moved close to the groove face, the welding current was increased rapidly because the welding arc was affected by the inclined surface. Also the welding current waveforms were measured for the double-sided symmetric workpiece to verify the previous measurements for the single-beveled workpiece, and similar current waveforms were found.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.57-64
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• 2000

In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ratio using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to the cutting torque acting on a single tooth at the swept angle of cut and can be acquired from cutting torque signals. Average cutting torque per revolution can also be calculated from cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current. Varying immersion ratio is also estimated well using the presented algorithm.