• Journal of Power Electronics
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• v.14 no.1
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• pp.61-73
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• 2014

Multiphase machines are characterized by high power density, enhanced fault-tolerant capacity, and low torque pulsation. For a voltage source inverter supplied multiphase machine, the probability of load imbalances becomes greater and unwanted low-order stator voltage harmonics occur. This paper deals with the PWM control of multiphase inverters under unbalanced load conditions and it proposes a novel near-five-vector SVPWM algorithm based on the five-phase six-leg inverter. The proposed algorithm can output symmetrical phase voltages under unbalanced load conditions, which is not possible for the conventional SVPWM algorithms based on the five-phase five-leg inverters. The cause of extra harmonics in the phase voltages is analyzed, and an xy coordinate system orthogonal to the ${\alpha}{\beta}z$ coordinate system is introduced to eliminate low-order harmonics in the output phase voltages. Moreover, the digital implementation of the near-five-vector SVPWM algorithm is discussed, and the optimal approach with reduced complexity and low execution time is elaborated. A comparison of the proposed algorithm and other existing PWM algorithms is provided, and the pros and cons of the proposed algorithm are concluded. Simulation and experimental results are also given. It is shown that the proposed algorithm works well under unbalanced load conditions. However, its maximum modulation index is reduced by 5.15% in the linear modulation region, and its algorithm complexity and memory requirement increase. The basic principle in this paper can be easily extended to other inverters with different phase numbers.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1289-1292
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• 1997

Typical biomechanical system such as human body and mammals possess abundant muscles which are more than required for motion generation of such systems. We have shown that the excess number of muscles play important roles in spring-like impedance modulation. redundant kinematic structure, which is another feature of biomechanical systems, allows modulations of inertia and damping properties of such systems. In this work, we propose a frequency modulation algorithm which combines the spring-like impedance with inertia impedance. also, a load distribution method for frequency modulation is also introduced. The frequency modulation represents a simulataneous control of force and kinematic redundancies, which has not been addressed in the literature.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.226-228
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• 2006

This paper presents the two lossless auxiliary inducors-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 forwide its output power regulation ranges and load variations under constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operatprinciple 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 charactertics-based on the high frequency PDM strategy. The experimenoperating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimenones. 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 appliimplemented here is proved from the practical point of view.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.4
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• pp.51-58
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• 2004

Push-pull structure with balun transformer is presented for load modulation technique which improves the overall efficiency of power amplifier Under the assumption that output impedance of fumed-off amplifier is high, conventional Doherty amplifier is composed of impedance inverter and peaking amplifier, of which operation is controlled by the input power level. In many case, however, impedance of 'off'amplifier is very low due to matching network or parasitic output capacitance. This paper introduces novel load modulation technique which uses low output impedance of 'off'amplifier. Experimental results show that good linearity and efficient!'enhancement of the proposed push-pull structure

• ETRI Journal
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• v.39 no.5
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• pp.737-745
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• 2017

A 6-GHz-to-18-GHz monolithic nonuniform distributed power amplifier has been designed using the load modulation of increased series gate capacitance. This amplifier was implemented using a $0.25-{\mu}m$ AlGaN/GaN HEMT process on a SiC substrate. With the proposed load modulation, we enhanced the amplifier's simulated performance by 4.8 dB in output power, and by 13.1% in power-added efficiency (PAE) at the upper limit of the bandwidth, compared with an amplifier with uniform gate coupling capacitors. Under the pulse-mode condition of a $100-{\mu}s$ pulse period and a 10% duty cycle, the fabricated power amplifier showed a saturated output power of 39.5 dBm (9 W) to 40.4 dBm (11 W) with an associated PAE of 17% to 22%, and input/output return losses of more than 10 dB within 6 GHz to 18 GHz.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.252-258
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• 2012

This paper studies the power line communication method with splitting of power transmission interval in the small DC power system using pulse width modulation. The method divides the entire interval for transmitting power and data into a power transmission interval where power is supplied to a load and a data transmission interval where power from the power supply to the load is disconnected. The circuit is designed for the implementation to separate the power line from the power supply and load. The results of tests show the feasibility of the proposed power line communication method.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.3
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• pp.101-105
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• 2004

The efficient power MOSFET inverter applied for a simple and low cost power supply is proposed for driving the dielectric barrier discharge (DBD) lamp load. For decades, the DBD phenomenon has been used for ozone gas production in industry. In this research, the ultraviolet and visible light sources utilizing the DBD lamp is considered as the load for solid-state high frequency power supply. It is found that the simple voltage-source single-ended quasi-resonant ZVS inverter with only one active power switch could effectively drive this load with the output power up to 700 W. The pulse density modulation based control scheme for the single-ended quasi-resonant ZVS inverter using a low voltage and high current power MOSFET switching device is proposed to provide a linear power regulation characteristic in the wide range 0-100％ of the full power as compared with the conventional control based Royer type parallel resonant inverter type power supplies.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.123-126
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• 1996

In this paper, optimal modulation controller is designed to improve the stability of A.C. and A.C.-D.C. power system, and optimal theory is applied to select optimal modulation controller input signal Optimal modulation controller for speed governor and exciter controller system is constructed in A.C. power system, while the controller is constructed to the both control systems like AC. power system, considering ACR-AVR, APR-$A{\gamma}R$ as the control method of direct current system. It is considered that the stability of A.C. power system only and A.C.-D.C. power system against load fluctuations and disturbances under case of optimal modulation control.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.5
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• pp.313-320
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• 2001

In the present study, various experiments were performed to investigate capacity modulation and refrigerant flow distribution of a multi-heat pump using a variable speed compressor and electronic expansion valves(EEVs) in the cooling mode. Based on the experimental results, it was possible to understand the interrelation of dual indoor units which provides some difficulties in capacity control of each indoor unit. The characteristics of capacity modulation of two indoor units were measured by controlling two EEVs with a cooling load of each indoor unit.

• Journal of Power Electronics
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• v.17 no.3
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• pp.664-673
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• 2017

With the development of multilevel converters, cascaded single-phase H-bridge rectifiers (CHBRs) has become widely adopted in high-voltage high-power applications. In this study, sequence pulse modulation (SPM) is proposed for CHBRs. SPM is designed to balance the dc-link voltage and maintain the smooth changes of switch states. In contrast to phase disposition modulation, SPM balances the dc-link voltage even after removing the load of one submodule. The operation principle of SPM is deduced, and the unbalance degree of SPM is analyzed. All the proposed approaches are experimentally verified through a prototype of a four-module (nine-level) CHBR. Conclusions are drawn in accordance with the results of SPM and its imbalance degree analysis.