Patent ID: 8111055
Filing Date: 2012-02-07
Classification: H02M,Y02B

Abstract:
1. A method of controlling a direct current chopper controller having a transistor switch and a storage choke, wherein the storage choke has a coil current which depends on the switching of the switch on and off, the method comprising: calculating a coil current variable derived from one of the time averaged value of the coil current of the storage choke and the peak value of the coil current of the storage choke; calculating a switching frequency for synchronizing the turning on and the turning off of the switch as a function of the coil current variable and on the condition of whether the coil current variable exceeds a predetermined current threshold; if the calculated switching frequency is lower than a predetermined low switching frequency, then setting the calculated switching frequency to be equal to the predetermined low switching frequency; if the coil current variable is less than the predetermined current threshold, then setting the calculated switching frequency to be equal to the predetermined low switching frequency; if the calculated switching frequency is greater than a predetermined high switching frequency, then setting the calculated switching frequency to be equal to the predetermined high switching frequency; and switching the switch on and off in accordance with the calculated switching frequency.