Hong-Hee Lee

University of Ulsan, Urusan, Ulsan, South Korea

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Publications (69)40.83 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: This paper develops the brushless dc (BLDC) motor sensorless control system for an automotive fuel pump. The sensorless techniques that are based on a hysteresis comparator and a potential start-up method with a high starting torque are suggested. The hysteresis comparator is used to compensate for the phase delay of the back EMFs due to a low-pass filter (LPF) and also prevent multiple output transitions from noise or ripple in the terminal voltages. The rotor position is aligned at standstill for maximum starting torque without an additional sensor and any information of motor parameters. Also, the stator current can be easily adjusted by modulating the pulse width of the switching devices during alignment. Some experiments are implemented on a single chip DSP controller to demonstrate the feasibility of the suggested sensorless and start-up techniques.
    IEEE Transactions on Power Electronics 01/2014; 29(3):1382-1391. · 4.08 Impact Factor
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  • Hong-Hee Lee, H.M. Nguyen
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    ABSTRACT: This paper focuses on the common-mode voltage reduction and the power quality of matrix converters for a low-voltage transfer ratio of less than 0.5 by the direct space vector modulation (DSVM) method. The principles of selecting suitable switching configurations based on new space vector sectors are described, and an entire switching table for the new control strategy is developed. The matrix converter with the proposed method reduces peak-to-peak common-mode voltage remarkably. The new DSVM method has advantages over the conventional DSVM method, such as lower total harmonic distortion of line-to-line output voltage and a reduction in switching loss by a minimum number of switching commutations. The proposed DSVM method can be easily implemented in software. Simulation and experimental results are shown to verify the effectiveness of the proposed DSVM method.
    IEEE Transactions on Power Electronics 01/2013; 28(2):920-929. · 4.08 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Use of the battery energy storage system (BESS) as a power buffer becomes a feasible solution to mitigate the intermittent wind power characteristic. Due to the cost, utilizing an economical battery capacity is a crucial requirement of the system design. In this paper, dispatch power strategies are overviewed and the min-max method is selected as the most suitable one for integrating the wind power to grid. A lifetime cost function, which indicates the BESS cost spent to dispatch 1kWh, is defined with the dispatch principle so that the battery capacity can be optimized. With using the optimal capacity, the minimum system operation cost is achieved and the dispatched power is able to satisfy its scheduled reference in any dispatching time period. Moreover, the battery state of charge (SOC) is also managed to be in a safe range so as to guarantee the system undamaged. In order to clarify the proposed determination method, a case study with a 3MW permanent magnet synchronous generator (PMSG) wind turbine model is investigated.
    Energy Conversion Congress and Exposition (ECCE), 2013 IEEE; 01/2013
  • Quoc-Nam Trinh, Hong-Hee Lee
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    ABSTRACT: This paper proposes an advanced control strategy to enhance performance of shunt active power filter (APF). The proposed control scheme requires only two current sensors at the supply side and does not need a harmonic detector. In order to make the supply currents sinusoidal, an effective harmonic compensation method is developed with the aid of a conventional proportional-integral (PI) and vector PI controllers. The absence of the harmonic detector not only simplifies the control scheme but also significantly improves the accuracy of the APF, since the control performance is no longer affected by the performance of the harmonic tracking process. Furthermore, the total cost to implement the proposed APF becomes lower, owing to the minimized current sensors and the use of a four-switch three-phase inverter. Despite the simplified hardware, the performance of the APF is improved significantly compared to the traditional control scheme, thanks to the effectiveness of the proposed compensation scheme. The proposed control scheme is theoretically analyzed, and a 1.5-kVA APF is built in the laboratory to validate the feasibility of the proposed control strategy.
    IEEE Transactions on Industrial Electronics 01/2013; 60(12):5400-5410. · 5.17 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: This paper proposes the control method for reducing a total harmonic distortion (THD) of the grid current at the three-phase grid-connected inverter systems when the grid voltages are distorted. The THD of the grid current caused by grid voltage harmonics is derived by considering the phase delay and attenuation due to a hardware low-pass filter. Both the gain and angle of a compensation voltage for suppressing the harmonic currents at the minimum point of THD of the grid current are derived. The simulation and experimental results show the validity of the proposed control method.
    Power Engineering, Energy and Electrical Drives (POWERENG), 2013 Fourth International Conference on; 01/2013
  • Quoc-Hoan Tran, Tae-Won Chun, Hong-Hee Lee
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    ABSTRACT: This paper proposes an open circuit fault tolerant strategy with a fault detector for the inverter stage in indirect matrix converter (IMC). When an open switch fault occurs in IMC, the location of faulty switches in the inverter stage can be exactly identified by the fault detector which compares the output voltages of the analytical model with the measured output voltages. In order to keep the continuous operation without output voltage fluctuation, the fault tolerant strategy is developed to control indirect matrix converter based on the concept of four-leg matrix converter. The proposed fault tolerant strategy can maintain the same output performance during the faulty condition as the healthy condition. Simulation results are given to verify the effectiveness of the proposed method.
    Industrial Electronics Society, IECON 2013 - 39th Annual Conference of the IEEE; 01/2013
  • Quoc-Nam Trinh, Hong-Hee Lee
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    ABSTRACT: This paper proposes an enhanced current controller for three-phase shunt active power filters (SAPFs). The proposed current controller is composed of a proportional-integral (PI) controller and two repetitive controllers (RCs) where the RCs are designed with a delay time of one sixth of the fundamental period (T/6). With the combination of these RCs, the SAPF can offer a good harmonic compensation performance under various types of nonlinear loads (three-phase or single-phase nonlinear loads). As consequence, the supply current is effectively compensated to be sinusoidal despite the nonlinear load current. In addition, the proposed SAPF also can provide a fast dynamic response under load variations to maintain the supply current sinusoidal. The effectiveness of the proposed controller is verified through simulation results.
    Electrical Machines and Systems (ICEMS), 2013 International Conference on; 01/2013
  • [show abstract] [hide abstract]
    ABSTRACT: Single-stage topology and the maximum power point tracking (MPPT) algorithm have advantages such as simple configuration and high efficiency in grid-connected photovoltaic (PV) systems. However, in conventional systems, current and voltage sensors of PV system are normally used for MPPT. This paper presents a low-cost single-stage grid- connected PV system without PV current sensor with a modified MPPT method. This method is not derived from complex state equations and is not dependent on any circuit parameters. It simply calculates the output power of the inverter to replace the input power of the PV systems in the MPPT algorithm. The new algorithm is simulated by using Matlab/Simulink software and implemented in the experimental prototype. With the one-stage configuration and PV current sensorless method, the prototype is suitable for lowcost implementation in the practice.
    Power System Technology (POWERCON), 2012 IEEE International Conference on; 01/2012
  • Van-Tung Phan, Hong-Hee Lee
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    ABSTRACT: In this paper, the control of a stand-alone doubly fed induction generator (DFIG)-based wind power conversion system with unbalanced and nonlinear loads is investigated. Under these load conditions, the quality of stator voltage and current waveforms of the DFIG is strongly affected due to the negative and distorted components, reducing the performance of other normal loads connected to the DFIG. To tackle this problem, the control strategy is comprehensively developed in both rotor-side converter (RSC) and load-side converter (LSC) of the DFIG. The LSC is used as an active power filter to compensate for unbalanced and distorted stator currents whereas the RSC is developed to fully eliminate unbalanced and harmonic voltages at the point of common coupling. The proposed compensation method is based on current controllers in either the RSC or the LSC, which employ a proportional integral plus a resonant controller. These current controllers are controlled in the positive synchronous reference frame so that the rotor current and stator current are directly regulated without decomposing sequential components. Analytical issues on how to eliminate unbalanced and distorted components in the stator voltage and current are also described in this paper. To verify the effectiveness of the proposed control strategy, experimental results with 2.2-kW DFIG topology are presented and discussed in the paper.
    IEEE Transactions on Industry Applications 01/2012; 48(1):199-210. · 1.67 Impact Factor
  • Hoang M. Nguyen, Hong-Hee Lee, Tae-Won Chun
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    ABSTRACT: This article proposes a novel direct space vector modulation (DSVM) strategy that can restrict the common-mode voltage of a three-phase-to-three-phase matrix converter and maintain sinusoidal input/output waveforms, as well as a unity power factor at the input side. The proposed control method has been developed using active, non-zero space vectors instead of zero space vectors. A new space vector modulation table is also presented with the space vector rearrangement. One advantage of the proposed method is a 42% reduction of the peak value of the common-mode voltage besides the lower harmonic components compared to the conventional DSVM method. Furthermore, the maximum voltage transfer ratio is unaffected by the proposed method. Simulation and experimental results are shown to validate the advantages of the proposed DSVM method.
    International Journal of Electronics - INT J ELECTRON. 01/2012; 99(1):1-14.
  • [show abstract] [hide abstract]
    ABSTRACT: This paper describes a simple grid current control method for the grid-connected operation, and inverter voltage control method based on the phase locked loop (PLL) for the intentional islanding operation at the three-phase grid-connected inverter. The PLL controller based on the pq theory with a simple P-controller is used to synchronize the phase of inverter output voltage with a grid voltage at the grid-connected operation or generate a desired inverter output voltage at the islanding operation. The outputs of current controller are connected together to those of voltage controller, in order to prevent a sudden change of the outputs of both controllers during the transfer instant. The simulation and experimental results are carried out to verify the effectiveness of the proposed control strategies.
    Renewable Energy Research and Applications (ICRERA), 2012 International Conference on; 01/2012
  • Tuyen D. Nguyen, Hong-Hee Lee
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    ABSTRACT: Common-mode voltage (CMV) is responsible for overvoltage stress to the winding insulation and bearing damage of an ac motor. High dv/dt of CMV raises leakage currents, which can cause serious problems such as motor damage and elec- tromagnetic noise to the equipment installed near the converter. This paper proposes two modulation strategies for indirect matrix converters that substantially eliminate CMV. The first method is developed by using the suitable couple of nonzero space vectors instead of zero space vectors in the inverter stage. The maximum voltage transfer ratio of this method is unaffected and remains 0.866. The second one, which is useful for low-voltage operation, is approached by choosing the medium and the lowest positive line- to-line input voltages in the rectifier stage to generate the dc-link voltage and by placing suitable zero space vectors in the inverter stage. In the second method, the maximum voltage transfer ratio is 0.5. Both methods can mitigate the peak value to 42%. In addition, while the first method provides the same performance to the con- ventional method, the second method can reduce significantly the harmonic components of line-to-line output voltage. Simulation and experimental results are shown to verify the effectiveness of the proposed methods. Index Terms—AC/AC converter, common-mode voltage (CMV), direct matrix converter (DMC), indirect matrix converter (IMC), matrix converters (MCs), space vector pulsewidth modulation (SVPWM).
    IEEE Transactions on Industrial Electronics 01/2012; 59(1):129-140. · 5.17 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: This paper proposes the development of modified carrier-based PWM algorithms for AC output voltage control in the Z-source three-phase inverter (ZSI), which is based on the relationship with space-vector PWM method. This approach combines advantages of the both modulation strategies for ZSI by obtaining the wide linear modulation range, less total harmonic distortion (THD) in the spectrum of output waveform and maximum boost factor. The proposed method is simulated by using Matlab/Simulink software and implemented in the experimental model. The simulation and practical results demonstrate feasibilities of proposed modified carrier-based PWM algorithms for ZSI.
    Power System Technology (POWERCON), 2012 IEEE International Conference on; 01/2012
  • [show abstract] [hide abstract]
    ABSTRACT: The input current harmonics of battery chargers affect harmfully on the overall power distribution network. They result in voltage distortion, heating transformers, reducing conduction capacity of cable, and affecting the interrupting capability of circuit breakers. In order to eliminate these problems, this paper presents an effective control scheme to remove input current harmonics of battery charger by controlling the current in phase with fundamental component of the grid voltage. The proposed control scheme not only achieves near-unity input power factor but also eliminates current harmonics in the battery charger regardless of the grid voltage disturbance. To validate performance of the proposed control scheme, both simulation and experiment are carried out.
    Vehicle Power and Propulsion Conference (VPPC), 2012 IEEE; 01/2012
  • Cong-Long Nguyen, Hong-Hee Lee
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    ABSTRACT: This paper presents an effective control scheme for an electric vehicle battery charger where a symmetrical bridgeless power factor-corrected converter and a buck converter are cascaded. Both converters have been popular in industries because of their high efficiency, low cost, and compact size, hence combining these two converters makes the overall battery charging system strongly efficient. Moreover, this charger topology can operate under universal input voltage condition and attain a desired battery voltage and charging current without any ripple. In order to reduce the system cost, an estimating ac input voltage technique is introduced, which especially does not require the converter component information and therefore it is robust to the circuit parameters variation. Additionally, by adopting a duty ratio feed-forward path in current control loop, a unity input power factor and zero input current harmonic are achieved. The feasibility and practical value of the proposed approach are verified by simulation and experimental results.
    IPEC, 2012 Conference on Power & Energy; 01/2012
  • Cong-Long Nguyen, Hong-Hee Lee
    [show abstract] [hide abstract]
    ABSTRACT: This paper presents an effective control scheme for an electric vehicle battery charger where a symmetrical bridgeless power factor-corrected converter and a buck converter are cascaded. Both converters have been popular in industries because of their high efficiency, low cost, and compact size, hence combining these converters makes the overall battery charging system strongly efficient. Moreover, this charger topology can operate at universal input voltage and attain a desired battery current and voltage without ripple. In order to achieve a unity input power factor and zero input current harmonic distortion, the proposed control scheme adopts duty ratio feed-forward control technique in both current and voltage control loop. Additionally, in the current loop, its reference is created by a phase-locked loop (PLL) block, leading to a pure sinusoidal input current although the input voltage waveform is being distorted. The feasibility and practical value of the proposed approach are verified by simulation and experimental results with an 110V/60Hz ac line input and 1.5kW-72V dc output of the battery charging system.
    Strategic Technology (IFOST), 2012 7th International Forum on; 01/2012
  • H.M. Nguyen, Hong-Hee Lee, Tae-Won Chun
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    ABSTRACT: An input filter is necessary for a matrix converter (MC) system to improve the input current quality with low harmonic components, as well as to reduce the input voltage distortion supplied to the MC. However, the input filter's characteristics make the input power factor (IPF) obtained at unity only in the presence of high output loads, and the IPF degrades significantly under light-load conditions. In this paper, we propose a new direct space vector modulation (DSVM) method to achieve the required displacement angle between the input voltage and input current of the MC. A new switching strategy is introduced based on the maximum compensated angle. Then, power factor compensation algorithms using the new DSVM method to achieve the maximum IPF are presented, in which compensation algorithm I is based on using the input filter and power supply parameters to estimate the optimal compensated angle. Compensation algorithm II is subsequently proposed using a proportional-integral controller to overcome drawbacks presented in compensation algorithm I. Simulation and experimental results are shown to validate the effectiveness of the proposed compensation algorithms.
    IEEE Transactions on Industrial Electronics 02/2011; · 5.17 Impact Factor
  • Quoc-Nam Trinh, Hong-Hee Lee, Tae-Won Chun
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    ABSTRACT: In this paper, a new Z-source inverter (ZSI) topology is developed to improve a voltage boost ability of ZSI. Some more inductors and diodes are added into the impedance network of the conventional ZSI. The modulation methods that have been developed in the conventional ZSI can be easily utilized in the proposed ZSI. The voltage boost ratio becomes much higher compared with the conventional ZSI under the same shoot-through duty ratio. In addition, the proposed ZSI can reduce the voltage stress on Z-source capacitor and inverter-bridge significantly because a smaller shoot-through duty ratio is required for high voltage boost ratio. Theoretical analysis of the proposed topology is investigated and the improved performances are validated by both simulation study and experimental results.
    01/2011;
  • Van-Tung Phan, Hong-Hee Lee
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    ABSTRACT: This paper proposes a new control strategy of effective fifth and seventh harmonic elimination in the stator output voltage at the point of common coupling for a stand-alone doubly fed induc- tion generator (DFIG) feeding a three-phase diode rectifier. This load regularly causes such harmonic distortions, which harmfully affect the performance of other loads connected to the DFIG. In order to allow the DFIG to deliver a pure sinusoidal stator output voltage, these harmonics must be rejected. The proposed elimina- tion method is investigated based on the rotor current controller employing a proportional integral and a resonant controller, which is implemented in the fundamental reference frame. In this frame, both positive seventh and negative fifth voltage harmonic can be eliminated by using only single resonant compensator tuned at six multiples of synchronous frequency in the rotor current controller. The control scheme is developed in the rotor-side converter for the control and operation of the DFIG. Simulations and experimental results with 2.2-kW DFIG feeding a nonlinear load are shown to verify prominent features of the proposed control method. Index Terms—Doubly fed induction generator (DFIG), nonlin- ear loads, resonant controller, stand-alone system, wind turbine system. NOMENCLATURE
    IEEE Transactions on Power Electronics 01/2011; 26(9):2662-2675. · 4.08 Impact Factor

Publication Stats

103 Citations
19 Downloads
2k Views
40.83 Total Impact Points

Institutions

  • 2003–2013
    • University of Ulsan
      • Department of Electrical Engineering
      Urusan, Ulsan, South Korea
  • 2004
    • Novosibirsk State Technical University
      Novo-Nikolaevsk, Novosibirsk, Russia