Multiloop control apparatus and method for switching mode power converter with bandpass current control

摘要

A switched mode power converter includes a periodically switched power switch (103) which is switched under the control of a multiple loop feedback controlling the power switch in order to supply a regulated output (across 120). The output voltage and power switch current are sensed (on 113, and by 124 respectively). An error voltage is generated (by 115) which is representative of the deviation of the output voltage from a regulated value. A voltage (on 124) derived from the power switch current is limited in its low frequency response (by 131,135,132,133) and is then combined with the error voltage. The low frequency response of the current loop gain is used to maintain an advantageously low output impedance for the power supply. This shaped loop gain response advantageously allows accurate adjustment of the current loop gain and reduces the system to a lower order while maintaining adequate loop stability. The low frequency response may be attained by limiting the low frequency response of the sensed current or by inserting an operational amplifier (121) in the feedback path to limit its low frequency response.