• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.3
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• pp.273-279
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• 2015

A zero vector selection method to reduce switching losses for model predictive control (MPC) of voltage source inverter is proposed. A conventional MPC of voltage source inverter has not been proposed, and a method to select the redundancy of the zero vector is required for this study. In this paper, the redundancy of the zero vectors is selected with generating a zero sequence voltage to reduce switching losses. The zero vector of 2-level inverter is determined by determining sign of the zero sequence voltage. In the proposed method, the quality of the current is retained and switching loss can be reduced compared with the conventional method. This result was verified by P-sim simulation and experiments.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.274-284
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• 2003

Multi-level converter that is high-capacity electric power conversion system is used widely to electric motor drive system and FATCs(Flexible AC Transmission Systems). H-Bridge converter has been prevalently applied to shunt-type system because it can be easily expanded to the multi-level. In steady states, converter is normally operated in the range of 0.7∼0.8 of modulation Index. Even though zero vectors are not imposed to high modulation index, DC-Link voltage Is constant. It means that converter has another boost vector except for zero vectors among several vectors in 3-level converter. This paper has examined the principle of boost vector and investigated the difference between another boost vector and zero vectors in 3-level converter. In addition, this paper has analysed and compared the charging currents and the capacitor voltages of two topologies. The currents and voltages are related to reference voltage. Therefore, it proposed the calculation method for the voltage ripple and the charging current of each capacitor and compared various DC-Link voltage control methods through the simulation.

• Journal of Power Electronics
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• v.2 no.2
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• pp.77-87
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• 2002

The purpose of this paper is to improve power conversion efficiency of three-phase soft-switching voltage-source inverter with an auxiliary resonant dc link (ARDCL) snubber circuit. Firstly, the operation principle of ARDCL snubber circuit is described. Secondly, this paper proposes an effictive generation method of zero voltage vector for three-phase voltage-source soft-switching inverter in power losses in which power losses in the ARDCL snubber circuit can be reduced. In particular, zero voltage holding interval in the inverter DC busline can be controlled due to the new generation scheme of zero voltage vector. Thirdly, a simulator for power loss analysis for power loss characteristics based on actual system, is developed. the validity of developed. The validity of developed simulator of proved with experimental results. Finally, power efficency of three-phase inverter is estimated according to high carrier frequency by using the simulatior.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.31-34
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• 2003

There are several types of switching table for selection voltage vector in direct torque control of induction motor. In general, two-quadrant and four-quadrant operation switching table are used mostly. Two-quadrant operation has an advantage that reduced the torque ripples in comparison with four-quadrant operation, but it has the defect that is not constant average torque. Because the torque increasing slope size by non-zero voltage vector is different from the torque decreasing slope size by zero voltage vector as speed region. The main objective of this study is to maintain constant average torque using two-quadrant operation switching table. In proposed method, the torque increasing slope or decreasing slope are calculated before selected voltage vector is applied. Then, it is applied to zero voltage vector or non-zero voltage vector until the torque increasing slope and decreasing slope are equal. In total magnitude. Therefore it becomes to maintain average torque at whole operation speed. The validity of the proposed method is proven by simulated and experimental results.

• Journal of Power Electronics
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• v.15 no.3
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• pp.712-720
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• 2015

A model predictive current control (MPCC) method that does not employ a cost function is proposed. The MPCC method can decrease common-mode voltages in loads fed by three-phase voltage-source inverters. Only non-zero-voltage vectors are considered as finite control elements to regulate load currents and decrease common-mode voltages. Furthermore, the three-phase future reference voltage vector is calculated on the basis of an inverse dynamics model, and the location of the one-step future voltage vector is determined at every sampling period. Given this location, a non-zero optimal future voltage vector is directly determined without repeatedly calculating the cost values obtained by each voltage vector through a cost function. Without utilizing the zero-voltage vectors, the proposed MPCC method can restrict the common-mode voltage within ± V_dc/6, whereas the common-mode voltages of the conventional MPCC method vary within ± V_dc/2. The performance of the proposed method with the reduced common-mode voltage and no cost function is evaluated in terms of the total harmonic distortions and current errors of the load currents. Simulation and experimental results are presented to verify the effectiveness of the proposed method operated without a cost function, which can reduce the common-mode voltage.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.12
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• pp.739-750
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• 2004

In case while M(modulation index) is more than 0.7, the spectrum of motor voltage and current of a conventional two-phase SRP-PWM scheme are not reduced considerably. To solve the problems of a conventional two-phase SRP-PWM, this paper proposes a two-phase SRP-PWM(DZSRP-PWM) with double zero vector mode which zero vector is selected as V(111) in case of M >0.7, and zero vector is selected as V(000) if M < 0.7. For the validity of the proposed method, the PSIM simulations and experiments were achieved. And the simulation and experiment results show that the voltage and current harmonics all over the modulation index are spread to a wide band area.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.5-9
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• 2003

Conventional variable-speed Induction motor drives with inverters are subject to detrimental effect of zero-sequence voltages, such a shaft voltage and bearing current. This paper presents a way of the suppression of the zero-sequence components in multilevel H-bridge inverters. First examined Is the inherent zero-sequence characteristic of the conventional subharmonic PW method. Then it is shown that the zero-sequence voltage can be eliminated with proper -selection of switching states with space vector modulation. Although this method alone restricts the linear modulation range of control, a combination of the proposed method and the minimum switching method appears to be effective in suppressing the zero-sequence voltage to minimum level while maintaining the linear control range.

• Journal of Power Electronics
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• v.3 no.4
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• pp.239-248
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• 2003

This paper presents a novel prototype of three-phase voltage source type zero voltage soft-switching inverter with the auxiliary resonant snubbers suitable for high-power applications with IGBT power module packages in order to reduce their switching power losses as well as electromagnetic conductive and radiative noises. A proposed single inductor-assisted resonant AC link snubber circuit topology as one of some auxiliary resonant commutation snubbers developed previously to achieve the zero voltage soft-switching (ZVS) for the three-phase voltage source type sinewave PWM inverter operating under the instantaneous space voltage vector modulation is originally demonstrated as compared with the other types of resonant AC link snubber circuit topologies. In addition to this, its operation principle and unique features are described in this paper. Furthermore, the practical basic operating performances of the new conceptual instantaneous space voltage vector modulation resonant AC link snubber-assisted three-phase voltage source type soft-switching PWM inverter using IGBT power module packages are evaluated and discussed on the basis of switching voltage and current waveforms, output line to line voltage quality, power loss analysis, actual power conversion efficiency and electromagnetic conductive and radiative noises from an experimental point of view, comparing with those of conventional three-phase voltage source hard-switching PWM inverter using IGBT power modules.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.279-285
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• 2020

An open-end winding (OEW) permanent magnet synchronous motor with dual inverters can synthesize large voltages for a motor with the same DC link voltage. This ability has the advantage of reducing the use of DC/DC boost converters or high voltage batteries. However, zero-sequence voltage (ZSV), which is caused by the difference in the combined voltage between the primary and secondary inverters, can generate a zero-sequence current (ZSC) that increases system losses. Among the methods for eliminating this phenomenon, combining voltage vector eliminated ZSV cannot be accomplished by the conventional Pulse Width Modulation(PWM) method. In this study, a PWM carrier generation method using functionalization to generate a switching pattern to suppress ZSC is proposed and applied to analyze the control influence of the center-zero vector in the switching sequence about the current ripple.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.2
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• pp.75-82
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• 1999

A compensation method of the motor parameters using zero sequence third harmonic voltage is presented for the speed sensorless vector control of the induction motor considering saturation of the flux. Generally, the air-gap flux of the saturated induction motor contains the space harmonic components rotating with the synchronous frequency of the motor. Because the EMF of the saturated induction motor contains the zero sequence harmonic voltages at the neutral point of the motor, those harmonic voltages can be used as a saturation index. In this work, the rotor flux observer is firstly designed for the speed sensorless vector control of induction motor. And a novel measurement method of the space harmonic voltage and a compensation method of th LPF(Low Pass Filter) are proposed. For compensating the non-linear variations of the magnetizing inductance depending on the saturation level of the motor, the dominant third harmonic voltage of the motor is used as a saturation function of the air-gap flux. And the variation of the stator resistance owing to the motor temperature can also be measured with the phase angle between the impressed voltage vector and the zero sequence voltage. The validity of the proposed parameter compensation scheme in the speed sensorless vector control using rotor flux observer is verified by the result of the simulations and the experiments.