Power Converter Selective Transformer Winding Input
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Solution Overview
Problem
Conventional power converters require large bulk capacitors due to high capacitance needs, which occupy significant space and increase in size as other components shrink, especially in low-power applications, and existing methods to reduce capacitance, such as using non-isolated boost converters, incur efficiency losses.
Innovation Solution
A power converter design that includes a first rectified voltage node not coupled to a bulk capacitor and a second rectified voltage node coupled to a bulk capacitor, with a controller managing switching between these nodes based on sensed voltage levels to determine the primary-side winding power source, reducing the required capacitance of the bulk capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large bulk capacitor is used to maintain constant DC intermediate voltage, then the voltage ripple is constrained within an acceptably narrow range, but the physical size and volume of the power converter increases significantly
Solution Approach 1:
The patent applies dynamics by making the bulk capacitor value variable rather than fixed. The system dynamically adjusts the bulk capacitor value based on operating conditions (input voltage, load power) by selectively connecting different capacitor values using switch elements. This allows the system to maintain voltage stability when needed while minimizing capacitor volume under other conditions, directly resolving the contradiction between voltage stability and volume.
Solution Approach 2:
The patent changes the parameter of bulk capacitor capacitance from a fixed value to a variable parameter that can be adjusted based on operating conditions. By controlling the switch elements, the system selects appropriate capacitor values to match different input voltages and power levels, thereby reducing the overall capacitor volume required while maintaining adequate voltage ripple constraints across all operating ranges.
2Volume of stationary object
If the bulk capacitor capacitance is reduced to decrease power converter size, then the physical footprint is reduced, but the DC intermediate voltage ripple increases beyond acceptable ranges
Solution Approach 1:
The system dynamically adjusts the bulk capacitor value based on operating conditions. When input voltage or load power changes, the controller modifies which capacitor values are connected in the circuit, ensuring adequate voltage ripple filtering is maintained even when the overall capacitor volume is reduced compared to conventional fixed designs.
Solution Approach 2:
The patent changes the capacitance parameter from fixed to variable, allowing the system to use smaller total capacitance while maintaining voltage stability through selective connection of different capacitor values optimized for specific operating conditions.
3Volume of stationary object
If a non-isolated boost converter is added to pre-regulate input voltage and reduce bulk capacitor needs, then the bulk capacitor size is reduced, but the overall device complexity and additional components increase
Solution Approach 1:
The existing bulk capacitor and associated circuitry in the power converter are made multi-functional. Instead of adding a separate boost converter stage, the patent enables the existing input stage to perform both voltage rectification and voltage regulation functions by dynamically adjusting the bulk capacitor value, thereby reducing bulk capacitor size without increasing overall device complexity.
Solution Approach 2:
The patent merges the voltage regulation function with the existing bulk capacitor circuitry by making the capacitor value variable. This combines what would traditionally be separate functions (boost conversion and bulk capacitance) into a unified system, avoiding the need for additional components and reducing overall complexity.
4Reliability
If the bulk capacitor value is optimized for maximum input voltage, then the capacitor can handle peak voltages with margin, but the capacitance is oversized for lower input voltages, increasing volume unnecessarily
Solution Approach 1:
The system dynamically adjusts the bulk capacitor value based on the detected input voltage level. When input voltage is high, larger capacitor values are connected to provide adequate voltage ripple filtering and handle peak voltages with appropriate margin. When input voltage is lower, smaller capacitor values are connected, reducing the overall capacitor volume and avoiding oversizing for conditions that don't require the full capacitance.
Solution Approach 2:
The patent changes the bulk capacitor capacitance parameter from a fixed value optimized for maximum voltage to a variable parameter that adapts to the actual input voltage level, thereby reducing volume while maintaining reliability across different operating conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for a 33% reduction in bulk capacitor capacitance, achieving the same voltage requirements with less physical space and maintaining efficiency, typically reducing capacitance to less than 1.4 μF per Watt of output power.
Implementation Method 1
The rectifier is configured to input the AC power and provide a rectified voltage at a rectified voltage node
Implementation Method 2
The transformer includes one or more primary-side windings... producing an AC voltage across the primary winding(s). This induces an AC voltage on the secondary winding(s)
Data Source
AI summary
Circuits and methods are provided for supplying power to a transformer of a switching DC/DC voltage converter within a power converter. The power converter includes separate nodes that can potentially supply such power. A first of these nodes is coupled, typically directly and with no energy-storing bulk capacitor, to a rectifier that supplies rectified power from an alternating current power source. A second node is also supplied power from the rectifier, but is coupled to a bulk capacitor that can store and supply energy as needed. The techniques disclosed herein use the first node to supply power to the transformer when feasible, and use the second node, and its associated bulk capacitor, to supply power otherwise. In so doing, the energy storage requirements of the bulk capacitor may be reduced, meaning that the capacitance and associated size of the bulk capacitor may be reduced relative to other power converter circuits.