• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.462-473
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• 1999

This paper addresses the current measurement issue of all digital field oriented control of ac motors. The p paper focuses on the effect of low-pass filter and also on the sampling of the fundamental component of the m motor current. The low-pass filter, which suppresses the switching noise of the motor current, introduces v variable phase delay according to the current ripple frequency. It is shown that the current sampling error c consists of the fundamental component and high frL'quency ripple components. In this paper, the dependency of t this current sampling e$\pi$or on the reference voltage vector is investigated analytically and a sampling technique i is proposed to minimize the error. The work is based on the three phase symmetry pulse width modulation l inverter driving an induction machine. With this technique, the bandwidth of current regulator can be extended t to the limit given by the switching frequency of the inverter and more precise torque regulation is possible.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1066-1071
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• 2005

This paper presents the two lossless auxiliary inductors-assisted voltage source type half bridge (single ended push pull: SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation for wide its output power regulation ranges and load variations under its constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operating principle is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation characteristics-based on the high frequency PDM strategy. The experimental operating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimental ones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliance implemented here is proved from the practical point of view.

• Journal of IKEEE
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• v.21 no.2
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• pp.105-114
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• 2017

This paper proposes a design method of an LCL-filter for grid-tied three-level inverter systems. The demand for three-phase PWM inverters in applications such as wind or solar power generation systems has been increase in recent years. To reduce harmonic components caused by switching operation, such inverters are connected to the grid via an LCL filter. Although there are research results for designing LCL-filter, the modulation method should be fully considered to make the filter perform desired cancellation ability with minimized size. This paper presents the design methodology for an LCL-filter that is optimized for SVM switching operations. The simulation and experimental results verify the validity of the LCL-filter designed with proposed method in this paper.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.11
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• pp.84-91
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• 2009

A high speed serial link transmitter using multi-level signaling is proposed. To achieve high data rate m high speed serial link, 4-pulse amplitude modulation (PAM) is used. By transmitting 2 bit data in each symbol time, high speed data transmission, two times than binary signaling, is achieved. The transmitter transmits current-mode output instead of voltage-mode output Current-mode output is much faster than voltage-mode output, so higher data transmission is available by increasing switching speed of driver. $2^5-1$ pseudo-random bit sequence (PRBS) generator is contained to perform built-in self test (BIST). The 4-PAM transmitter is designed in Dongbu HiTek $0.18{\mu}m$ CMOS technology and achieves 8 Gb/s, 160 mV of eye height with 1.8 V supply voltage. The transmitter consumes only 98 mW for 8 Gb/s transmission.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.10
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• pp.910-916
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• 2015

A sensorless motor control scheme with conventional back-Electro Motive Force (EMF) sensing based on zero crossing point (ZCP) detection has been widely used in various applications. However, there are several problems with the conventional method for effectively driving sensorless brushless motors. For example, a phase mismatch of 30 degrees occurs between the ZCP and commutation time. Additionally, most of the motor speed/current controls are achieved based on a pulse width modulation (PWM) method, which generates significant noise that distracts the back-EMF sensing. Due to the PWM switching, the ZCP is not deterministic, and thus the efficiency of the motor is reduced because the phase transition points become uncertain. Moreover, the motor driving performance is degraded at a low speed range due to the effect of PWM noise. To solve these problems, an improved back-EMF detection method based on a differential line method is proposed in this paper. In addition, the proposed sensorless BLDC driver addresses the problems by using a variable voltage driver generated from a buck converter. The variable voltage driver does not generate the PWM switching noise. Consequently, the proposed sensorless motor driver improves 1) the signal-to-noise ratio of back-EMF, 2) the operation range of a BLDC motor, and 3) the torque characteristics. The proposed sensorless motor driver is verified through simulations and experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.10-16
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• 2005

This paper suggested the sulfur lamp power supply using Fuzzy Gain Scheduling(FGS), which was designed and confirmed the performance through manufacturing. it was based on Series Resonant Half Bridge Inverter(SRHBI), so that was applied Pulse Frequency Modulation(PFM), Zero Voltage Switching(ZVS), soft switching and soft start for input power variation and output power compensation. In order to get the lengthened life time of magnetron and stabilized output or power, power ratter and efficiency were improved by fuzzy gain algorism. It also made it possible to get not the existing foxed output power but continuous variable output power$(900\~1250[W])$. The manufactured power supply showed good results in input power $220[V]{\pm}15[\%]$ with stabilized output of power, luminous efficiency 97[1m/W] and power factor $96[\%]$.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.448-457
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• 2017

In this paper, for high speed railway propulsion systems, a single phase PWM Converter using discontinuous PWM (DPWM) was investigated. The conventional PWM Converter uses a low frequency modulation index of less than 10 to reduce switching losses due to high power characteristics, which results in low control frequency bandwidth and requires an additional compensation method. To solve these problems, the DPWM method, which is commonly used in three phase PWM Inverters, was adopted to a single phase PWM Converter. The proposed method was easily implemented using offset voltage techniques. Method can improve the control performance by doubling the frequency modulation index for the same switching loss, and can also bring the same dynamic characteristics among switches. Proposed DPWM method was verified by simulation of 100 kW PWM converter.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.415-420
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• 2005

This paper presents the two lossless auxiliary inductors-assisted voltage source type half bridge (single ended push pull: SEPP) series resonant high frequency inverter for induction heated king roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation for wide its output power regulation ranges and load variations under its constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operating principle is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation characteristics-based on the high frequency PDM strategy. The experimental operating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimental ones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliance implemented here is proved from the practical point of view.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.4
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• pp.293-301
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• 2006

This paper proposes a control algorithm for STATic synchronous COMpensator(STATCOM), based on Space Vector Modulation(SVM) and Hysteresis Current Controller(HCC) techniques. STATCOM is used to reactive power compensation on a distribution network. The proposed algorithm utilizes the advantages of the fast dynamic response of the hysteresis current control and the reduced switching number of the SVM scheme. The controller determines a set of space vectors from a region detector and applies a space vector. A set of space vectors including the zero vector, to reduce the number of switching, is determined from output signals of two hysteresis comparators. The presented control system was tested with digital simulation in the Borland C++ program and demonstrate the advantage of the proposed hysteresis current controller.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.1 s.307
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• pp.45-52
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• 2006

In this paper, authors propose a step-up converter of pulse width modulation (PWM) and power factor correction (PFC) by using a novel loss-less snubber. The proposed converter for a discontinuous conduction mode (DCM) eliminates the complicated circuit control requirement and reduces the size of components. The input current waveform in the proposed converter is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching. Thereupon, the input power factor is nearly unity and the control method is simple. In the general DCM converters, the switching devices are fumed-on with the zero current switching (ZCS), and the switching devices must be switched-off at a maximum reactor current. To achieve a soft switching (ZCS and ZVS) of the switching turn-off, the proposed converter is constructed by using a new loss-less snubber which is operated with a partial resonant circuit. The result is that the switching loss is very low and the efficiency of converter is high. Some simulative results on computer and experimental results are included to confirm the validity of the analytical results.