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CONTINUOUS CONDUCTION MODE HIGH POWER FACTOR BOOST RECTIFIERS USING A CONTROLLED COMPENSATING RAMP

IP.com Disclosure Number: IPCOM000008873D
Original Publication Date: 1998-Sep-01
Included in the Prior Art Database: 2002-Jul-19
Document File: 5 page(s) / 289K

Publishing Venue

Motorola

Related People

Joel P. Gegner: AUTHOR

Abstract

A Simplified Power Factor Correction (PFC) technique for Continuous Conduction Mode (CCM) operated converters is presented which has the fol- lowing advantages over conventional peak and average current mode PFC techniques: Elimination of the controller multiplier and input voltage sens- ing circuits, unconditional stability of the current loop, and ease of implementations using low cost standard PWM control [C's (e.g. UC2843). Simulation and experimental results will verify the viability of the new controller: current rather than the switch current, resulting in high power dissipation in the sensing resistor.

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MOTOROLA Technical Developments

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CONTINUOUS CONDUCTION MODE HIGH POWER FACTOR BOOST RECTIFIERS USING A CONTROLLED COMPENSATING RAMP

by Joel I? Gegner

ABSTRACT

  A Simplified Power Factor Correction (PFC) technique for Continuous Conduction Mode (CCM) operated converters is presented which has the fol-

lowing advantages over conventional peak and average current mode PFC techniques: Elimination of the controller multiplier and input voltage sens- ing circuits, unconditional stability of the current loop, and ease of implementations using low cost standard PWM control [C's (e.g. UC2843). Simulation and experimental results will verify the viability of the new controller:

current rather than the switch current, resulting in high power dissipation in the sensing resistor.

  The control technique presented in this papezr - Linear Peak Current Mode Control (LPCMC)- enables CCM operated rectifiers to be controlled using a much simpler controller (Figure I). LPCMC offers the following advantages: Elimination of the controller multiplier and input voltage sensing circuits, unconditional stability of the current loop, and ease of implementation using low cost standard PWM control IC's (e.g. UC2843).

INTRODUCTION

   Over the past few years, a number of control techniques have been developed for use in high power factor rectifiers. Among them are a number of techniques designed for use with continuous con- duction mode (CCM) operated power converters. Converters operated in CCM are typically associat- ed with higher power applications. Unfortunately, to date, the control techniques for use in CCM oper- ated rectifiers are more complex than those for criti- cal conduction mode (CrCM) or discontinuous con- duction mode (DCM). The two most popular tech- niques - peak current mode control, and average

current mode control - both require stabilization of their current control loops. In addition, sensing of the rectified AC voltage is necessary, and a multipli- er for generating a reference current proportional to the input voltage is required. Peak cm-rent control has the additional disadvantage of input current dis- tortion near the zero crossing of the input voltage as a result of the necessary slope compensation for sta- bilizing the current loop. Average current mode control suffers from having to sense the inductor

Fig. 1 Linear Peak Current Mode Controlhzr

  The control technique is based on designing a current loop whose static gain is linearly dependent upon the off-duty cycle of the switch. For the Boost converter, the off-duty cycle D' = 7-D= Vi No, As a result, the static gain of the current loop is propor- tional to the input voltage, and the hence the current loop inherently controls the inductor current to be proportional to the input voltage.

B M"mrda. 1°C. 19% 148 September I998

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  In section II, Peak Current Mode Control is review...