• 한국자동차공학회논문집
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• 제14권4호
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• pp.164-173
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• 2006

In the electro-hydraulic injector for the common rail Diesel fuel injection system, the injection nozzle is being opened and closed by movement of a injector's needle which is balanced by pressure at the nozzle seat and at the needle control chamber, at the opposite end of the needle. In this study, the piezo actuator was considered as a prime movers in high pressure Diesel injector. Namely a piezo-driven Diesel injector, as a new method driven by piezoelectric energy, has been applied with a purpose to develop the analysis model of the piezo actuator to predict the dynamics characteristics of the hydraulic component(injector) by using the AMESim code. Aimed at simulating the hydraulic behavior of the piezo-driven injector, the circuit model has been developed and verified by comparison with the experimental results. As this research results, we found that the input voltage exerted on piezo stack is the dominant factor which affects on the initial needle behavior of piezo-driven injector than the hydraulic force generated by the constant injection pressure. Also we know the piezo-driven injector has more degrees of freedom in controlling the injection rate with the high pressure than a solenoid-driven injector.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.18-20
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• 2007

3상 계통 연계 형 인버터 시스템은 낮은 THD를 가지는 계통 전류를 공급해주기 위해 LCL 필터를 사용한다. LCL 필터를 사용하는 가장 큰 장점은 낮은 스위칭 주파수에서도 만족할 만한 수준의 THD를 가지는 계통 전류를 생성시킬 수 있다는 점이다. 반면에, 단점은 LCL필터를 포함하는 계통 연계 형 인버터 시스템의 전달함수에 하나의 공진 극점이 존재한다는 점이다. 이것은 계통 전류 제어 loop에서, 안정성 문제에 영향을 미친다. 정확한 제어를 위해서 시스템의 전달함수는 필수적이다. 여기서 중요한 점은 많은 저자들이 시뮬레이션과 실험을 할 때, 중성점이 없는 회로에서 행하지만 회로 해석을 할 때에는 중성점이 있는 회로에서 해석을 한다는 점이다. 그래서 우리는 등가 델타회로에서 LCL 필터를 포함한 전체 시스템의 수학적인 모델을 제안한다. 이 모델은 모든 인덕터와 커패시터의 기생 저항을 고려한다. 또한 이 논문은 계통 전류를 제어하기 위한 제어기의 해석적인 설계 절차를 포함한다. 제안한 수학적인 모델을 입증하기 위해, PSIM을 통한 시뮬레이션과 Simulink를 통한 시뮬레이션 결과를 비교하였다.

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1101-1107
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• 2017

In this paper, a robust and fast grid synchronization method of a three-phase power converter is proposed. The amplitude and phase information of grid voltages are essential for power converters to be properly connected into the utility. The phase-lock-loop in synchronous reference frame has been widely adopted for the three-phase converter system since it shows a satisfactory performance under balanced grid voltages. However, power converters often operate under abnormal grid conditions, i.e. unbalanced by grid faults and frequency variations, and thus a proper active and reactive power control cannot be guaranteed. The proposed method adopts a second order generalized integrator in synchronous reference frame to detect positive sequence components under unbalanced grid voltages. The proposed method has a fast and robust performance due to its higher gain and frequency adaptive capability. Simulation and experimental results show the verification of the proposed synchronization algorithm and the effectiveness to detect positive sequence voltage.

• Journal of Power Electronics
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• 제14권3호
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• pp.519-530
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• 2014

A novel simplified pulse width modulation(PWM) strategy for neutral point clamped (NPC) three-level converter is proposed in this paper.The direct output voltage modulation is applied to reduce the calculation time. Based on this strategy, several optimized control methods are proposed. The neutral point potential balancing algorithm is discussed and a fine neutral point potential balancing scheme is introduced. Moreover, the minimum pulse width compensation and switching losses reduction can be easily achieved using this modulation strategy. This strategy also gains good results even with the unequal DC link capacitor. The modulation principle is studied in detail and the validity of this simplified PWM strategy is experimentally verified in this paper. The experiment results indicated that the proposed PWM strategy has excellent performance, and the neutral point potential can be balanced well with unequal DC link captaincies.

• Journal of Electrical Engineering and Technology
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• 제4권2호
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• pp.219-228
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• 2009

The growing application and the numerous qualities of induction motors (1M) in industrial processes that require high security and reliability levels has led to the development of multiple methods for early fault detection. However, various faults can occur, such as stator short-circuits and rotor failures. Traditionally the diagnosis machine is done through a sinusoidal power supply, in the present paper we study experimentally the effects of the rotor failures, such as broken rotor bars in function of the ac supplying, the load and show the impact of the converter from diagnosis of the machine. The technique diagnosis used is based on the spectral analysis of stator currents or stator voltages respectively according to the types of induction motor ac supplying. So, four different ac supplying are considered: ${\odot}$ the IM is directly by the balanced three-phase network voltage source, ${\odot}$ the IM is fed by a sinusoidal current source given the controlled by hysteresis, ${\odot}$ the IM is fed (in open loop) by a scalar control imposing through ratio V/f=constant, ${\odot}$ the IM is controlled through a vector control using space vector pulse width modulation (SVPWM) technique inverter with an outer speed loop.