Analysis of DC-DC converters with current-mode control and resistive load when using load current measurements for control

The paper analyses some properties that are obtained when using load current measurements to control DC-DC power converters. The analysis is made for the buck, boost, and buck-boost converters with current mode control. The two major properties obtained are low output impedance and an almost invariant control-to-output transfer function for different loads. It is shown that the use of the load current is not feedforward when the load is a resistor. It can instead be seen as gain scheduling. The use of the load current for control affects the control-to-output transfer function, the output impedance, and the audio susceptibility. These effects are analyzed by use of accurate models of the converters. Simulation results are included in the paper.