• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.342-344
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• 2006

This paper present a method of current control for torque ripple reduction in brushless dc motor which have a trapezoid back EMF. In such drives the current ripples are generated by motor inductance in stator windings and the back EMF. The ripples suppression techniques that are practically effective in high speed as well as in low speed regions are rarely found. The proposed method here is based on a strategy that the commutation intervals of the incoming ang the outgoing phases can be equalized by a proper PWM control.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.229-236
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• 2019

This study proposes a DC-DC converter topology of solid-state transformer for low-voltage DC distribution. The proposed topology consists of a voltage balancer and bipolar DC-DC converter. The voltage and current equations are obtained on the basis of switching states to design the controller. The open-loop gain of the controller is achieved using the derived voltage and current equations. The controller gain is selected through the frequency analysis of the loop gain. The inductance and capacitance are calculated considering the voltage and current ripples. The prototype is fabricated in accordance with the designed system parameters. The proposed topology and designed controller are verified through simulation and experiment.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.307-318
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• 2010

In this work, an accurate analysis of low frequency current ripple in residential fuel cell power generation systems is performed based on the proposed residential load model and its unique operation algorithm. Rather than using a constant dc voltage source, a proton exchange membrane fuel cell (PEMFC) model is implemented in this research so that a system-level analysis considering the fuel cell stack, power conditioning system (PCS), and the actual load is possible. Using the attained results, a comparative study regarding the discrepancies of low frequency current ripple between a simple resistor load and a realistic residential load is performed. The data indicate that the low frequency current ripple of the proposed residential load model is increased by more than a factor of two when compared to the low frequency current ripple of a simple resistor load under identical conditions. Theoretical analysis, simulation data, and experimental results are provided, along with a model of the load usage pattern of low frequency current ripples.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.327-331
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• 2008

The problems of power factor and harmonics are occurred in converter system which used to SCRs and diodes as power semiconductor devices IGBT was solved that problem, maintain the input line current with sinusoidal wave current of input power source voltage. In this paper, three phase AC to DC boost converter that operates with unity power factor and sinusoidal input currents is presented. The current control of the converter is based on the space vector PWM strategy with fixed switching frequency and the input current tracks the reference current within one sampling time interval. Space vector PWM strategy for current control was materialized as a digital control method. By using this control strategy low ripples in the output voltage, low harmonics in the input current and fast dynamic responses are achieved with a small capacitance in the dc link.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.2
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• pp.182-189
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• 2012

In this paper, the input current and output voltage ripple of the soft switching interleaved boost converter was analyzed. Ripples of input current and output voltage with an interleaved method is analysed and as a result, the facts that it has lower ripple current than conventional interleaved method is verified. it means that a capacity of a main inductor can be reduced. Besides, a low capacitance of capacitor which means high lifetime and confidence can be used because of reducing ripples of output voltage. In order to verify the validity of the proposed converter used 10uF film capacitor, experiment was performed, and the efficiency of the proposed converter was measured with variable load and duty conditions.

• Journal of Power Electronics
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• v.7 no.3
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• pp.222-232
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• 2007

This paper presents the application of a single phase AC-to-DC converter using a three-phase series parallel (SPRC) resonant converter to variable speed dc-drive. The improved power quality converter gives the input power factor unity over a wide speed range, reduces the total harmonic distortion (THD) of ac input supply current, and makes very low ripples in the armature current and voltage waveform. This soft-switching converter not only possesses the advantages of achieving high switching frequencies with practically zero switching losses but also provides full ranges of voltage conversion and load variation. The proposed drive system is the most appropriate solution to preserve the present separately excited de motors in industry compared with the use of variable frequency ac drive technology. The simulation and experimental results are presented for variable load torque conditions. The variable frequency control scheme is implemented using a DSP- TMS320LF2402. This control reduces the switching losses and current ripples, eliminates the EMI and improves the efficiency of the drive system. Experimental results confirm the consistency of the proposed approach.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.958-961
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• 1998

In this paper, a three phase boost converter that operates with unity power factor and sinusodial input currents is presented. The current control of the converter is based on the space vector strategy with fixed switching frequency and the input current tracks the reference current within one sampling time interval. Space vector strategy for current control was materialized as a digital control method by using DSP. By using this control strategy low ripples in the output voltage, low harmonics in the input current and fast dynamic responses are achieved with a small capacitance in the dc link.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.11
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• pp.156-163
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• 1997

Recently, the three phase AC to DC boost converter has become one of the most widely used power converters as DC power source in the industry applications. In this paepr, a three phase PWM AC toDC boost converter that operates with unity power factor and sinusodial input currents is presented. The current control of the converter is based onthe predicted current control strategy with fixed switching frequency and the input current tracks the reference cuent within one sampling time interval. Therefore, by using this control strategy low ripples in the output voltage, low harmonics in the input current and fast dynamic responses are achieved with a small capacitance in the DC link.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2243-2257
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• 2016

This paper presents a two stage three-phase proton exchange membrane fuel cell (PEMFC) generation system. When the system is connected to a three-phase load, it is very sensitive to the characteristics and type of the load. Especially unbalanced three-phase loads, which result in a pulsating power that is twice the output frequency at the inverter output, and cause the dc-link to generate low frequency ripples. This penetrates to the fuel cell side through the front-end dc-dc converter, which makes the fuel cell work in an unsafe condition and degrades its lifespan. In this paper, the generation and propagation mechanism of low frequency ripple is analyzed and its impact on fuel cells is presented based on the PEMFC output characteristics model. Then a novel method to evaluate low frequency current ripple control capability is investigated. Moreover, a control scheme with bandpass filter inserted into the current feed-forward path, and ripple duty ratio compensation based on current mode control with notch filter is also proposed to achieve low frequency ripple suppression and dynamic characteristics improvement during load transients. Finally, different control methods are verified and compared by simulation and experimental results.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1477-1485
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• 2019

This paper proposes an effective model predictive current control (MPCC) that involves using 10 virtual voltage vectors to reduce the current harmonics and common-mode voltage (CMV) for a two-level five-phase voltage source inverter (VSI). In the proposed scheme, 10 virtual voltage vectors are included to reduce the CMV and low-order current harmonics. These virtual voltage vectors are employed as the input control set for the MPCC. Among the 10 virtual voltage vectors, two are applied throughout the whole sampling period to reduce current ripples. The two selected virtual voltage vectors are based on location information of the reference voltage vector, and their duration times are calculated using a simple algorithm. This significantly reduces the computational burden. Simulation and experimental results are provided to verify the effectiveness of the proposed scheme.