High performance two stage power converter with enhanced light load management
AssigneeApple Inc.
InventorsVijay G. Phadke, Liang Zhou, Prudhvi Mohan Maddineni
Life of this patent
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Abstract
A two-stage power converter can incorporate a buck pre-regulator and a resonant bus converter. Such a converter may be operated to achieve unconditional soft switching operation (zero voltage switching a/k/a ZVS) over a wide input and output range, while delivering excellent power conversion efficiency at lower power levels and in a no load condition.
Claims20
A two stage power converter, comprising:
- a buck pre-regulator stage configured to receive an input voltage and produce an intermediate voltage lower than the input voltage;
- a resonant bus converter stage configured to receive the intermediate voltage produced by the buck pre-regulator stage and produce an output voltage that is a fixed multiple of the intermediate voltage;
- and
- control circuitry coupled to the buck pre-regulator stage and the resonant bus converter stage, wherein the control circuitry is configured to:
- detect a load condition at or below a point at which switching and bias power losses of the buck pre-regulator stage and conduction and magnetic core losses of the buck pre-regulator stage are in equilibrium;
- responsive to detecting the load condition at or below a point at which switching and bias power losses of the buck pre-regulator stage and conduction and magnetic core losses of the buck pre-regulator stage are in equilibrium, temporarily and intermittently disable and enable switching of the buck pre-regulator stage and the resonant bus converter stage;
- and
- enter a controlled burst mode responsive to a control signal reaching a first threshold and exit the controlled burst mode responsive to the control signal reaching a second threshold.
A method of operating a two-stage converter having a first buck pre-regulator stage and a second resonant bus converter stage, the method comprising controlled burst mode operation of the resonant bus converter, including:
- detecting a load condition at or below a point at which switching and bias power losses of the buck pre-regulator stage and conduction and magnetic core losses of the buck pre-regulator stage are in equilibrium;
- and
- responsive to the detected load condition at or below a point at which switching and bias power losses of the buck pre-regulator stage and conduction and magnetic core losses of the buck pre-regulator stage are in equilibrium, temporarily and intermittently disabling and enabling switching of the buck pre-regulator stage and the resonant bus converter stage;
- wherein detecting the load condition at or below a point at which switching and bias power losses of the buck pre-regulator stage and conduction and magnetic core losses of the buck pre-regulator stage are in equilibrium comprises detecting a lower disable control signal at a load current below a first predetermined threshold and a higher enable control signal.
A method of operating a two-stage converter having a first buck pre-regulator stage and a second resonant bus converter stage, the method comprising controlled burst mode operation of the resonant bus converter, including:
- detecting a load condition at or below a point at which switching and bias power losses of the buck pre-regulator stage and conduction and magnetic core losses of the buck pre-regulator stage are in equilibrium;
- responsive to detecting the load condition at or below a point at which switching and bias power losses of the buck pre-regulator stage and conduction and magnetic core losses of the buck pre-regulator stage are in equilibrium, temporarily and intermittently disabling and enabling switching of the buck pre-regulator stage and the resonant bus converter stage;
- and
- entering the controlled burst mode responsive to a control signal reaching a first threshold and exiting the controlled burst mode responsive to the control signal reaching a second threshold.
Dependencies are inferred from the claim text.