Loss-less coil current estimator for peak current mode control SMPS

摘要

The present disclosure relates to a high efficiency switched mode power supply (SMPS) having increased efficiency due to loss-less coil current estimation for current control. A circuit in the control unit of SMPS comprises a capacitor and the voltage on the capacitor is an integral of the current flowing into the cap over time and if there are current sources which depend on the input and the output voltage, periodically switched with the same signals as the P and N switches, the voltage on the charged capacitor has the same shape as the current through the coil. The signal gleaned from the capacitor voltage are used the same manner by the control unit as it was with the signals from prior art current sensing.

主权项

1. A method to improve efficiency of a switched mode power supply (SMPS) system, the method comprising the steps of:
(1) providing a switched mode power supply system comprising a first and a second switch, a coil, wherein the coil is charged from an input voltage of the SMPS system while the first switch is closed during a first period and the coil is discharged to an output voltage while the second switch is closed during a second period, and a control circuit comprising a capacitor and a first and a second current source, wherein the second current source is depending on the output voltage and the first current source is periodically switched with a same signal as the first switch; and (2) estimating actual coil current without loss of power in order to control the SMPS; wherein a voltage across the capacitor has a same shape as the current through the coil and the estimation of the coil current is performed based on an equation:vC⁡(t)=1C⁢∫iC⁡(t)⁢ⅆt,,, wherein vc is the voltage across the capacitor, C is a capacitance of the capacitor and ic is a charging/discharging current of the capacitor.