An Optimized Sensorless Charge Balance Controller Based on a Damped Current Model for Flyback Converter Operating in DCM

Abstract

This paper presents an Optimized Sensorless Charge Balance (OSCB) controller based on a damped current model for flyback converter operating in Discontinuous Conduction Mode (DCM). By solving total differential equations of non-ideal transformer currents, the damped current model is derived with consideration of parasitics, leakage inductance of transformer, and the Resistor-Capacitor-Diode (RCD) snubber circuit. Based on the proposed model, current observation and control algorithms of the Sensorless Charge Balance (SCB) controller are optimized, which forms the OSCB control strategy. The average current damping is considered in the equivalent discrete-time small signal model. Furthermore, frequency analyses show that OSCB controller achieves higher closed-loop bandwidth and lower overshoot than a SCB controller, which indicates an improved transient performance. Finally, both OSCB and conventional SCB controllers are experimentally evaluated on a flyback converter prototype.

A Compensated Peak Current Mode Control PWM for Primary-Side Controlled Flyback Converters

“…Voltage V− can be obtained and shown as ( 10) by using KCL law. Compared with ( 5), parameters k 1 , k 2 , and k 3 can be obtained and shown as ( 11)- (13).…”

“…Because the flyback converter has a simple structure and does not require a secondary side output inductor, it has considerable advantages in size and cost. Based on the above advantages, the flyback converter is widely used in low power applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]-especially in LED lighting [8][9][10] and battery balancing control [11][12][13][14][15][16] to show its many advantages. With the advancement of digital technology and the cost of microcontrollers has dropped significantly.…”