• Journal of Sensor Science and Technology
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• v.27 no.6
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• pp.380-385
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• 2018

Recently, interest in baseball has been increasing as the level of international baseball games, the popularity of domestic leagues, and the number of players entering the MLB has increased. In this paper, we propose a pitching system that can be applied to both professional and amateur baseball. The pitching system consists of a control module using MSB764T PLC, a pitching mechanism including AC motors and a ball feed rail, an HMI using the CHA-070WR model, inverter, etc. To pitch the breaking balls, the two AC motors each use an inverter to independently control the speed. The implemented pitching system was experimented on, investigating ball speed and ball movement according to RPM using the BUSHNELL Velocity Speed Gun. Experimental results on ball speed are similar to the theoretical data and the measured data. From the experimental data, it is confirmed that the damping coefficient value for the pitching ball is about 0.98. In the case of the breaking ball, the larger the difference between the speeds on the sides of the ball and the faster the ball speed, the larger the bending degree.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.348-349
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• 2019

본 논문은 전기자동차용 8.1kW/L의 높은 전력밀도를 갖는 저전압 DC-DC 컨버터(Low-voltage DC-DC converter, LDC)의 설계 방법을 제안한다. 넓은 전압범위에서 높은 전력밀도를 성취하기 위해 위상천이 풀-브릿지(Phase Shift Full-Bridge, PSFB) 컨버터의 2차측 토폴로지 후보군의 비교를 통해 전류-더블러 토폴로지로 토폴로지가 선정되었다. 또한 자속 상쇄 기법이 적용된 매트릭스 변압기를 적용한 PSFB 컨버터와 냉각기의 구조설계를 통해 8.1kW/L의 전력밀도를 달성하였으며 1.8kW 시작품을 제작하여 성능을 검증하였다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.68-70
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• 2019

본 논문은 8.1kW/L($132W/in^3$)의 전력밀도를 갖는 전기자동차(xEV)용 저전압 배터리 충전기(Low voltage DC-DC converter, LDC)를 위한 절연형 DC-DC컨버터의 설계 방법을 제안한다. 전체 부피 중 가장 큰 비중을 차지하는 자성체의 부피를 줄이기 위해 GaN소자를 채택하여 700kHz의 스위칭 주파수를 적용하였으며, GaN 스위치를 고주파에서 원활히 동작시키기 위한 게이트 드라이버를 직접 제작하였다. 또한 자속 상쇄 개념이 적용된 매트릭스 평면 변압기를 설계하여 적용함으로써 변압기의 부피를 크게 줄일 수 있었고, 8.1kW/L의 전력밀도를 달성하였다. 본 논문에서는 후보 토폴로지들의 비교를 통해 고 전력 밀도에 가장 적합한 토폴로지를 선정하였으며, 자속 상쇄 기법이 적용된 매트릭스 평면 변압기의 설계방법을 제안하였다.

• Journal of Power Electronics
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• v.19 no.3
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• pp.761-770
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• 2019

This paper proposes a hybrid phase windings excitation method for improving the efficiency of a 7-phase brushless DC (BLDC) motor in the electric propulsion system of a ship. The electrical losses of a BLDC motor system depend on the operating region and the number of excited phase windings (2-phase, 4-phase or general 6-phase windings). In this paper the operating region and torque/speed characteristics according to the motor rotation speed and propeller load are analyzed for a number of excitation methods. In addition, it analyzes the electrical losses of the system under each of the excitation methods in the entire operating region of the motor. In every sampling time, the proposed control method calculates the electrical loss of the system for each of the excitation methods and operates a 7-phase BLDC motor by selecting the excitation method that results a decreased electrical loss at the operating speed. The usefulness of the proposed control algorithm is verified through experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.364-371
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• 2021

A magnetic flux saturation model of Synchronous Reluctance Motors (SynRMs) and a parameter estimation method are proposed at standstill. The proposed magnetic flux model includes the nonlinear relationship between the current and the magnetic flux for self-saturation and cross-saturation. Voltage is injected at standstill to estimate the magnetic flux saturation model. Voltages are injected into the d-axis and q-axis to obtain data on self-saturation. Subsequently, voltages are simultaneously injected into the d-q axis to obtain data on cross-saturation. On the basis of the measured current and the calculated magnetic flux, the parameters of the proposed model are estimated using the least square method (LSM). Simulation and experiment were performed on a 1.5-kW SynRM to verify the proposed method. The proposed model can be used to create a high-efficiency operation table, a sensorless algorithm, and a current controller to improve the control performance of a motor.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1527-1535
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• 2019

Because of the shortcomings of the PID controllers and traditional drive systems of permanent magnet synchronous motors (PMSMs), a PMSM passivity-based control (PBC) drive system based on a quasi-Z source matrix converter (QZMC) is proposed in this paper. The traditional matrix converter is a buck converter with a maximum voltage transmission ratio of only 0.866, which limits the performance of the driven motor. Therefore, in this paper a quasi-Z source circuit is added to the input side of the two-stage matrix converter (TSMC) and its working principle has also been verified. In addition, the controller of the speed loop and current loop in the conventional vector control of a PMSM is a PID controller. The PID controller has the problem since its parameters are difficult to adjust and its anti-interference capability is limited. As a result, a port controlled dissipative Hamiltonian model (PCHD) of a PMSM is established. Thereafter a passivity-based controller based on the interconnection and damping assignment (IDA) of a QZMC-PMSM is designed, and the stability of the equilibrium point is theoretically verified. Simulation and experimental results show that the designed PBC control system of a PMSM based on a QZMC can make the PMSM run stably at the rated speed. In addition, the system has strong robustness, as well as good dynamic and static performances.

• Journal of IKEEE
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• v.25 no.1
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• pp.116-127
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• 2021

In this paper, we propose simultaneous control which improve in transient state performance of mechanical parking facilities through simultaneous control of PLC and inverter. In conventional mechanical parking facilities, it is controlled only by PLC, and it is more likely to generate over-currents in induction motors, and the ride comfort is reduced due to wear and damage caused by friction on the brake pads, and the life is shortened. To improve this problems the application of control techniques through simultaneous control of PLC and inverter prevents over-currents in induction motors, protects brake pads, improves ride comfort, increases control and ensures safety. We verify its validity by applying the proposed control method via simultaneous control of PLC and inverter to a mechanical parking facility.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.540-544
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• 2011

Novel phosphrous flame retardant tetramethylene bis(orthophosphorylurea) (TBPU) was synthesized by the reaction of diphosphoric acid with 1,4-butanediol and urea, and charaterized by Fourier transform infrared spectroscopy (FT-IR). As the amount of TBPU added in polyurethane foam (PUF) was increased, the flame retardancy of PUF was increased and the mechanical properties were not decreased. Also, in the flame resistance test after the reduced pressure storage, the flame retardancy of TBPU added PUF was retained. We could find out that the thermal resistance of TBPU added PUF increased compared to that of pure PUF.

• Journal of Auto-vehicle Safety Association
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• v.13 no.1
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• pp.6-13
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• 2021

This paper presents yaw moment control for modification of steering characteristic in rear-driven vehicle with front in-wheel motors (IWMs). The proposed control algorithm is designed to modify yaw rate response of the test vehicle. General approach for modification of steering characteristic is to define the desired yaw rate and track the yaw rate. This yaw rate tracking method can cause the chattering problem because of the IWM actuator response. Large overshoot and settling time in IWM torque response can amplify the oscillation in control input and yaw rate. To resolve these problems, open-loop IWM controller for cornering agility was designed to modify the understeer gradient of the vehicle. The proposed algorithm has been investigated via the computer simulations and the vehicle tests. The performance evaluation has been conducted on dry asphalt using E-segment test vehicle. The performance of the proposed algorithm has been compared to general yaw rate tracking algorithm in the vehicle tests. It has been shown that the proposed control law improved the cornering agility without chattering problem.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.18-30
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• 2020

This study deals an estimation method of thrust measurement uncertainty in solid rocket motors. Guidelines of the force measurement uncertainty estimation have been provided by ISO, domestic and international organizations. However, all of them are described by focusing on the force calibration machines and force transducers with a conceptually-driven way. Thus the guidelines cannot be directly applicable to uncertainty estimation of calibration equation and its linear approximation, which are critical error sources in the thrust measurement. In this paper, the equations taking into account effects of both error sources are derived based on fundamental concepts of measurement uncertainty. These are applied to the real thrust measurement system where a relatively simple estimation method for the thrust measurement uncertainty is proposed.