The incremental voltage control mode for PWM regulators

The possibility of direct connections in parallel and inherent overload protection, which are typical advantages of current-controlled pulsewidth-modulated (PWM) regulators, are obtained by another control technique that is based on the sensing of the voltage waveform across a capacitor ( Delta V mode). This method, which eliminates the drawbacks of inductor current acquisition, has been applied to a Cuk DC/DC converter and can be extended to the step-down and step-up built around a fourth-order switching cell. With exact dynamic analysis of Delta V-mode-controlled converters, closed-form expressions of the transfer functions are achieved. The circuits are modeled as two-port networks when the feedback loop is closed and as three-port networks when it is open. Loop-gain behavior vs. frequency is found to be better suited to frequency compensation. Full theoretical and experimental characteristics are given.<
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