• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.52 no.2
• /
• pp.49-55
• /
• 2003

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.217-221
• /
• 2001

This paper presents a new prototype of soft-switching DC-DC power converter with a high frequency transformer link which has two active power controlled switches in full bridge rectifier with capacitor input type smoothing filter. In this DC-DC converter, ZVS of the inverter in transformer primary side and ZCS of active rectifier area in secondary side can be completely achieved by taking advantage of parasitic inductor component of high-frequency transformer and loss less snubbing capacitors. Its operation principle and salient features are described. The steady-state operating characteristics of the proposed DC-DC power converter are illustrated and discussed on the basis of the simulation results in addition to the experimental ones obtained by 2kw-40kHz power converter breadboard set up.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.61 no.3
• /
• pp.111-115
• /
• 2012

Generally, brushless DC motor(BLDCM) driving system uses hall sensors or encoders as the mechanical position or speed sensor. It is necessary to achieve the informations of rotor position for driving trapezoidal type brushless DC motor without any position sensor. In this paper, the commutation signals are obtained without the motor neutral voltage, multistage analog filters, A/D converters, or the complex digital phase shift circuits which are indispensable in the conventional sensorless control algorithms. In the proposed method, in stead of detecting the zero crossing point of the nonexcited motor back electromagnetic force for the average motor terminal to neutral voltage, the commutation signal are extracted directly from the specific average line to line voltage with low-pass filter, adder and comparators circuit. In contrast to conventional methods, the neutral voltage is not need; therefore, the commutation signals are insensitive to the common mode noise. Moreover, the complex phase shift circuit can be eliminated. The effectiveness of the proposed method is verified through simulation results.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.1015-1019
• /
• 2001

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• Proceedings of the KIEE Conference
• /
• 2002.06a
• /
• pp.55-59
• /
• 2002

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current -fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.7
• /
• pp.581-588
• /
• 2013

In the basic GMSK, the modulated signals are generated by the preprocessing of NRZ pulse trains with the gaussian low pass filter. In this paper, we proposed the GMSK modulation system with the delta pulse trains. The proposed system constructed with the gaussian pulse generator triggered by the bipolar delta pulse, the differentiator between $+T_b/2$ and $-T_b/2$, and then a matched filter for frequency-modulation function. The spectrum of proposed system was found to be smaller than about 35[%] at 40[dB] attenuated bandwidth, and the center spectrum to be lower than the basic GMSK with zero-crossing property.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2005.11a
• /
• pp.387-390
• /
• 2005

A This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched- capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft-switching commutation. In the first place, the steady-state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment or set-up in laboratory system or this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.3A
• /
• pp.225-234
• /
• 2008

Orthogonal Frequency Division Multiplexing (OFDM) systems utilizing direct conversion receiver suffer from frequency selective (FS) and frequency independent (FI) phase and gain imbalances caused by imperfect local oscillator and low pass filter. In this paper, we analyze the impacts of the transmit/receive IQ imbalances on the system and propose the estimation and compensation schemes for those imbalances. The preamble signals coded by Alamouti scheme in the frequency domain could be used in the estimation of relatively large IQ imbalances with FS and FI characteristics and the estimation results are used for the compensation of distortions caused by the FI and FS IQ imbalances. The optimal maximum likelihood (ML) receiver or suboptimal ordered successive interference cancallation (OSIC) receiver utilizing the estimation results show symbol error rate (SER) performance improvement compared to zero-forcing (ZF) technique due to diversity gain inherent in the frequency domain IQ imbalances combined with the frequency selective channels.