A classification scheme is used to categorize tapped-inductor switched-mode power supplies. This new scheme allows the many possible circuit variants to be displayed in a logical manner and analyzed for practicality and performance. The scheme offers a way of ensuring that no tapped inductor converter circuit is neglected when a tapped-inductor circuit is to be chosen for any particular application.

Synthesis of Tapped-Inductor Switched-Mode Converters

The single-ended primary inductance converter (SEPIC) presents several advantages over boost and flyback topologies which make this converter convenient for use as a power factor preregulator (PFP). Due to this fact, both the pulsewidth modulation (PWM) and the zero-current switched quasi-resonant (ZCS-QR) SEPIC used as PFPs are studied. Stress in components and operation in continuous and discontinuous conduction mode are considered in the PWM case, while the use of full-wave and half-wave resonant switches is considered in the ZCS-QR case. The study of the PWM SEPIC used as a PFP reveals that both types of PFP control, multiplier approach and voltage-follower approach, can be used in PWM SEPIC, the first one when it operates in continuous conduction mode and the second one when it operates in discontinuous conduction mode. Regarding the ZCS-QR SEPIC used as PFP, both types of resonant switch (half-wave and full-wave) can be used. >

Improving power factor correction in distributed power supply systems using PWM and ZCS-QR SEPIC topologies

A small-signal circuit model for pulsewidth-modulated DC-DC converters operated in discontinuous conduction mode is presented. The model is composed of controlled current sources, an independent voltage source and resistances. The principle of energy conservation approach is used to take into account parasitic resistances of the transistor and diode and the diode threshold voltage. The proposed model is suitable for small-signal, frequency-domain representation of the converters. This model is used to derive the expressions for a boost converter control-to-output transfer function, input-to-output voltage transfer function, input impedance and the output impedance. Bode plots are also given for these transfer functions. The predicted and experimental results were in excellent agreement.

Small-signal model of PWM converters for discontinuous conduction mode and its application for boost converter

This paper describes a new, systematic, and unified approach to model the low-frequency behavior of power switches in Switch-Mode Power Supplies (SMPS). This approach starts with a simplification of the switching converter circuit to a Minimum Separable Switching Configuration (MISSCO) containing all power switches but a minimum number of other components, before analysis on the MISSCO is carried out. Then by making use of an impulse-response method and averaging technique, a set of equations describing the low-frequency behavior of the MISSCO are derived. The resultant equations can be used to generate a low-frequency equivalent circuit of the MISSCO, which can then be combined with the rest of the SMPS circuit to form a complete equivalent circuit.

A Systematic and Unified Approach to Modeling Switches in Switch-Mode Power Supplies

In this paper, a new single-phase ac–dc PFC bridgeless rectifier with multiplier stage to improve the efficiency at low input voltage and reduce the switch-voltage stress is introduced. The absence of an input rectifier bridge in the proposed rectifier and the presence of only two semiconductor switches in the current flowing path during each switching cycle result in less conduction losses and improved thermal management compared to the conventional full bridge topology. Lower switch voltage stress allows utilizing a MOSFET with lower $R_{\rm{DS-on}}$ . The proposed topology is designed to operate in discontinuous conduction mode (DCM) to achieve almost a unity power factor and low total harmonic distortion (THD) of the input current. The DCM operation gives additional advantages such as zero-current turn-on in the power switches and simple control circuitry. The proposed topology is compared with modified full-bridge SEPIC rectifier in terms of efficiency, THD, and power factor. Detailed converter analysis, small signal model, and closed-loop analysis are presented. Experimental results for a 200 W/400 $V_{{\rm dc}}$ at universal line voltage range to evaluate the performance of the proposed bridgeless PFC rectifiers are detailed.

Bridgeless PFC-Modified SEPIC Rectifier With Extended Gain for Universal Input Voltage Applications

A new current injected equivalent circuit approach (CIECA) to modeling switching dc-dc converter power stages is developed, which starts with current injected approach, and results in a set of equations which describe completely input and output properties and an equivalent linear circuit model valid at small signal low frequency levels.

P. R. K. Chetty

Papers

Current Injected Equivalent Circuit Approach to Modeling of Switching DC-DC Converters in Discontinuous Inductor Conduction Mode