Patent ID: 9602009
Date: 2017-03-21
CPC Classifications: H02M,Y02B

Claim:
1. An energy storage circuit for use with a power converter, the power converter having an energy transfer element that receives a fluctuating input voltage produced from a rectified AC input line voltage, the fluctuating input voltage being provided on an input bus coupled to a primary side of the energy transfer element, the energy transfer element having an output side that delivers an output signal to a load, a power switch being coupled to the primary side of the energy transfer element for regulating a transfer of energy to the output signal delivered to the load, a bias supply of the energy transfer element being coupled between first and second nodes, the bias supply producing a bias voltage at the first node, the energy storage circuit comprising: a base capacitor coupled between the input bus and a ground potential, the base capacitor having a first capacitance; an adjust capacitor having a second capacitance; a switching device coupled in series with the adjust capacitor between the input bus and the ground potential; and a control circuit that includes a voltage regulator having first and second terminals respectively coupled to a control terminal of the switching device and the ground potential, the control circuit further including a resistor coupled between the first node and the control terminal, the voltage regulator further having an input coupled to the second node, wherein during normal operation when the power switch is turned on a signal at the second node is representative of the fluctuating input voltage, the voltage regulator being activated when the fluctuating input voltage is in a crest region thereby turning the switching device off and disengaging the adjust capacitor, the voltage regulator being deactivated when the fluctuating input voltage is in a valley region, thereby turning the switching device on and engaging the adjust capacitor, such that when the adjust capacitor is engaged a total capacitance of the energy storage circuit is equal to a sum of the first and second capacitances.