• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.670-674
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• 2016

The control performance of hybrid PWM inverter using a phase current measurement is presented in this paper. The hybrid PWM technique consists of space vector pulse width modulation (SVPWM) and six-step voltage control operation. The SVPWM is performed to reduce the harmonic components in the low speed region, and the six-step modulation is applied to increase the maximum speed of the IPMSM in the high speed region. Therefore, it is possible to obtain a great performance in both the low speed range and high speed range. However, the six-step modulation cannot be completely implemented, since the inverter that includes the lag-shunt sensing method has an immeasurable current region. In this paper, a quasi-six-step modulation using a modified voltage vector is proposed. The validity and usefulness of the proposed PWM technique is verified by MATLAB/Simulink and experimental results.

• Journal of Power Electronics
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• v.19 no.1
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• pp.146-157
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• 2019

The inverter is an essential part of permanent magnet synchronous motor (PMSM) drive systems. The performance of an inverter is greatly influenced by its modulation strategy. Using a proper management of modulation strategies can guarantee high performance from a PMSM under various speed conditions. Switching between modulations is a pivotal technique that determines the performance of a PMSM. Most works on hybrid methods focus on two-level induction motors drive systems. In this paper, in order to improve the performance of PMSMs under various speed conditions, a hybrid method of a pulse width modulation (PWM) control scheme based on a neutral-point-clamped (NPC) three level topology was proposed. This hybrid PWM modulation comprised space vector PWM (SVPWM) and selective harmonic elimination PWM (SHEPWM). Under low speed conditions, the SVPWM is employed to cause the PMSM to start smoothly, and to obtain a rapid response from the control system. Under high speed conditions, the SHEPWM is employed to reduce the switching frequency and to eliminate particular current harmonics. Moreover, the harmonic characteristics of different modulations are analyzed to obtain a smooth transition between the SHEPWM and the SVPWM. Experimental and simulation results indicated the effectiveness of the proposed control method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.810-816
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• 2001

This paper proposes a Truncated Type-II Hybrid ARQ scheme using an adaptive modulation system to achieve high throughput data transmission systems for mobile communication systems. In this paper, the adaptive modulation system analyzed in Nakagami (m-distribution) fading channel environment. The adaptive modulation system controls the modulation level and symbol rate according to the Nakagami fading parameter(m). When the received $E_bN_0$ is high or the Nakagami fading parameter m is high, the propose system selects higher modulation level and higher symbol rate to increase throughput. On the other hand, this system selects lower modulation level and lower symbol rate to prevent throughput performance degradation when the received $E_bN_0$ is low. The modulation method have been adopted QPSK(Quadrature Phase Shift Keying), 16 QAM(Quadrature Amplitude Modulation), 64 QAM, 256 QAM. Therefore, Adaptive Modulation Systems with Truncated Type-II Hybrid ARQ Scheme is proper for mobile and radio for mobile and radio data communication system that require high reliability and delay-limited applications.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.64-69
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• 2012

This paper presents a hybrid pulse width modulation (PWM) method under low switching frequency conditions based on space vector PWM (SVPWM) and selective harmonic eliminated PWM (SHEPWM), which use asynchronous carrier modulation SVPWM at low frequency, and SHEPWM at high frequency, a square wave after rated conditions. A transitive strategy is proposed to realize a smooth transition of individual modes including SVPWM, SHEPWM and square waves. Experimental results confirm this hybrid modulation method and their transition are reasonable and proper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.227-232
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• 2009

The simple PSK signal generation method using a quadrature hybrid coupler and reflection coefficient elements was analyzed in this paper. The PSK modulation signal with a constant constellation is generated by reflection coefficient from 90o hybrid coupler output ports, the high-mode PSK signal is also generated by the hybrid structure of coupler, delay line and power combiner. The BPSK signal is simply generated by a 90o hybrid coupler and reflection elements, and QPSK with 90o phase constellation is generated by additional delay line and power combiner. By simulation results, the generated PSK signals by the proposed circuit get good modulation spectra within 3o phase error.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1119-1129
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• 2014

This study proposes a novel five-level three-phase hybrid-clamped converter composed of only six switches and one flying capacitor (FC) per phase. The capacitor-voltage-drift phenomenon of the converter under the classical sinusoidal pulse width modulation (SPWM) strategy is comprehensively analyzed. The average current, which flows into the FC, is a function of power factor and modulation index and does not remain at zero. Thus, a specific modulation strategy based on space vector modulation (SVM) is developed to balance the voltage of DC-link and FCs by injecting a common-mode voltage. This strategy applies the five-segment method to synthesize the voltage vector, such that switching losses are reduced while optional vector sequences are increased. The best vector sequence is then selected on the basis of the minimized cost function to suppress the divergence of the capacitor voltage. This study further proposes a startup method that charges the DC-link and FCs without any additional circuits. Simulation and experimental results verify the validity of the proposed converter, modulation strategy, and precharge method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.661-667
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• 2001

This paper proposes a Truncated Type-II Hybrid ARQ scheme using an adaptive modulation system to achieve high throughput data transmission systems for DS-CDMA cellular mobile communication systems. In this paper, the adaptive modulation system analyzed in Nakagami (m-distribution) fading channel environment. The adaptive modulation system controls the modulation level and symbol rate according to the Nakagami fading parameter( m). When the received Eb/No is high or the Nakagami fading parameter m is high, the propose system selects higher modulation level and higher symbol rate to increase throughput. On the other hand, this system selects lower modulation level and lower symbol rate to prevent throughput performance degradation when the received Eb/No is low. The modulation method have been adopted QPSK 16QAM, 64QAM, 256QAM. Therefore, adaptive modulation systems with Truncated Type II Hybrid ARQ Scheme is proper for mobile and radio data communication system that require high reliability and delay-limited applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.893-898
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• 2003

This paper proposes a Truncated Type-II Hybrid ARQ scheme and coding techniques using an adaptive modulation system to achieve high throughput data transmission systems for wireless multimedia communication systems. In this paper, the adaptive modulation system analyzed in Nakagami (m-distribution) fading channel environment. The adaptive modulation system controls the modulation level and symbol rate according to the Nakagami fading parameter(m). When the received Eb/No is high or the Nakagami fading parameter m is high, the propose system selects higher modulation level and higher symbol rate to increase throughput. On the other hand, this system selects lower modulation level and lower symbol rate to prevent throughput performance degradation when the received Eb/No is low. The modulation method have been adopted QPSK(Quadrature Phase Shift Keying), 16QAM(Quadrature Amplitude Modulation), 64QAM, 256QAM. Therefore, adaptive modulation systems with truncated type-II hybrid ARQ scheme is proper for wireless multimedia communication system that require high reliability and delay-limited applications.

• Journal of Power Electronics
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• v.16 no.2
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• pp.480-489
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• 2016

A novel hybrid carrier-based pulse width modulation (CBPWM) scheme that combines unipolar and dipolar modulations is proposed for single-phase three-level rectifiers, which are widely applied in railway traction drive systems. The proposed CBPWM method can satisfy the volt-second balancing principle in the complete modulation index region through overmodulation compensation. The modulation scheme features two modulation modes: unipolar and dipolar. The operation range limits of these modulation modes can be modified by changing the separation coefficient. In comparison with the traditional unipolar CBPWM, the proposed hybrid CBPWM scheme can provide advantageous features, such as lower high-order harmonic distortion of the line current and better utilization of switching frequency. The separation coefficient value is optimized to achieve the maximum utilization of these advantages. The experimental results verify the feasibility and effectiveness of the proposed hybrid CBPWM scheme.

• Journal of Power Electronics
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• v.17 no.1
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• pp.96-105
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• 2017

In this paper, a hybrid modular multilevel converter (MMC) topology with an improved nearest level modulation method is proposed for medium-voltage high-power applications. The arm of the proposed topology contains N series connected half-bridge submodules (HBSMs), one full-bridge submodule (FBSM) and an inductor. By exploiting the FBSM, half-level voltages are obtained in the arm voltages. Therefore, an output voltage with a 2N+1 level number can be generated. Moreover, the total level number of the inserted submodules (SMs) is a constant. Thus, there is no pulse voltage across the arm inductors, and the SM capacitor voltage is rated. With the proposed voltage balancing method, the capacitor voltage of the HBSM is twice the voltage of the FBSM, and each IGBT of the FBSM has a relatively low switching frequency and an equalized conduction loss. The capacitor voltage balancing methods of the two kinds of SMs are implemented independently. As a result, the switching frequency of the HBSM is not increased compared to the conventional MMC. In addition, according to a theoretical calculation of the total harmonic distortion of the electromotive force (EMF), the voltage quality with the presented method can be significantly enhanced when the SM number is relatively small. Simulation and experimental results obtained with a MMC-based inverter verify the validity of the developed method.