• Journal of Power Electronics
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• v.16 no.6
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• pp.2045-2056
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• 2016

The input impedances of pulse width modulated (PWM) dc-to-dc converters, which dictate the outcomes of the dynamic interaction between dc-to-dc converters and their source subsystem, are analyzed in a general and unified manner. The input impedances of three basic PWM dc-to-dc converters are derived with both voltage mode control and current mode control. This paper presents the analytical expressions of the 24 input impedances of three basic PWM dc-to-dc converters with the two different control schemes in a factorized time-constant form. It also provides a comprehensive reference for future dynamic interaction analyses requiring knowledge of the converters' input impedances. The theoretical predictions of the paper are all supported by measurements on prototype dc-to-dc converters. The use of the presented results is demonstrated via a practical application example, which analyzes the small-signal dynamics of an input-filter coupled current-mode controlled buck converter. This elucidates the theoretical background for the previously-reported eccentric behavior of the converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.10-16
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• 2004

In this thesis, improved full wave mode ZVT(Zero-Voltage-Transition) PMW DC-DC Converters are presented to maximize the regeneration ratio of resonant energy by only putting an additional diode In series with the auxiliary switch. The operation of the auxiliary switch in a half wave mode makes it possible soft switching operation of all switches including the auxiliary switch whereas it is turned off with hard switching in conventional converter. The increase of the regeneration ratio to resonant energy results in low commutation losses and minimum voltage and current stresses. The operation principles of the improved ZVT PWM DC-DC Converters are theoretically analyzed using the boost converter topology as an example. Both theoretical analysis and experimental results verify the validity of the PWM boost converter topology with the improved full wave mode ZVT PWM converters.

• Journal of Power Electronics
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• v.1 no.2
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• pp.107-116
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• 2001

Two AC-DC PWM full-bridge converters that can input current to improve input power factor while performing dc-dc conversion are investigated in this paper. Both converters are simple in that they are similar to the standard PWM full-bridge converter with a diode rectifier/LC low-pass filter input, and both can operate with a simple method of PWM control. In the paper, the operation of the converters is explained and their steady-state characteristics are discussed. The feasibility of the converters and their ability to meet EN61000-3-2 Class D Standards for electrical equipment are shown with results obtained from experimental prototypes. The performance of both converters in terms of dc bus voltage level, input power factor and efficiency is compared and discussed.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.4
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• pp.371-374
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• 2012

DC/DC switching power converters produce DC output voltages from different stable DC input sources regulated by a bi-polar transistor. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The voltage mode DC/DC converter is composed of a PWM (Pulse Width Modulation) controller, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an inductor, and capacitors, etc. PWM is applied to control and regulate the total output voltage. It is shown that the output of DC/DC converter depends on the variation of threshold voltage at MOSFET and the variation of pulse width. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by SPICE (Simulation Program with Integrated Circuit Emphasis) and experiments.

• Journal of Power Electronics
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• v.4 no.4
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• pp.246-255
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• 2004

Ac-dc PWM single-stage converters that integrate the PFC and dc-dc conversion functions in a single switching converter have been proposed to try to minimize the cost and complexity associated with implementing two separate and independent switch-mode converters. In this paper, two simple ac-dc single-stage PWM full-bridge converters are considered - one current-fed, the other voltage-fed. The operation of both converters is explained and their properties are noted. Experimental results obtained from simple lab prototypes of both converters are presented, then compared and discussed.

• Journal of the Korean Society for Railway
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• v.14 no.5
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• pp.411-415
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• 2011

DC/DC switching power converters are commonly used to generate a regulated DC output voltages with high efficiencies from different DC input sources. The voltage mode DC/DC converter utilizes MOSFET (metal-oxide semiconductor field effect transistor), inductor, and a PWM (pulse-width modulation) controller with oscillator, amplifier, and comparator, etc. to efficiently transfer energy from the input to the output at periodic intervals. The fundamental boost converter and a buck converter containing a switched-mode power supply are studied. In this paper, the electrical characteristics of DC/DC power converters are simulated by program of SPICE, and the PWM controller is implemented to check the operation. In addition, power efficiency is analyzed based on the specification of each component.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.3
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• pp.244-252
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• 2002

In this paper, do link ripple currents for three-phase ac/dc/ac PWM converters feeding adjustable speed ac machine drives are analysed in a frequency domain. The expression of the harmonic currents is developed by using switching functions of the converter and exponential courier series expansion. The effect of the displacement angle between the switching Periods of line-side converters and motor-side inverters on the dc link ripple currents is Investigated. Also, the influence of asynchronization of PWM is observed. The result of analysis is compared with frequency spectrum which results from PSIM simulation. The proposed analysis technique is useful to understand the principles of P% and to derive an equivalent model of the dc link capacitors in a high frequency range.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.685-692
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• 2011

DC/DC switching power converters produce DC output voltages from different DC input sources. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The current mode DC/DC converter is composed of a PWM (pulse width modulation) controller, a MOSFET, and inductor, etc. Pulse width modulation is applied to control and regulate the total output voltage. It is shown that the variation of threshold voltage at MOSFET and the offset voltage increase caused by radiation effects make the PWM pulse unstable. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by simulation program with integrated circuit emphasis (SPICE) and experiments.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.777-780
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• 2003

In this paper, an improved full wave mode ZVT-PWM DC-DC Converter is presented to maximize the regeneration ratio of resonant energy by only putting an additional diode in series with auxiliary switch. The operation of auxiliary switch in a half wave mode makes possible the soft switching condition of all switches. Furthermore, the increase of the regeneration ratio to resonant energy results in low conduction losses and minimum voltage and current stresses. The operation principles of the proposed converters are analyzed using the PWM boost converter topology as an example. Theoretically analysis and experimental results verify the validity of the boost converter topology with the proposed full wave mode ZVT-PWM converters

• Journal of IKEEE
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• v.16 no.3
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• pp.203-210
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• 2012

Since the non-overlapping gate driver used in conventional DC-DC boost converters generates fixed dead-times, the converters suffer from the body-diode conduction loss or the charge-sharing loss. To reduce the efficiency degradation due to these losses, this paper presents a PWM DC-DC boost converter with adaptive dead-time control. The proposed DC-DC boost converter delivering 3.3V output from a 2.5V input is designed with CMOS $0.3{\mu}m$ technology. It operates at 500kHz and has a maximum power efficiency of 97.3%.