Capacitor Module Voltage Doubler for Ripple Reduction
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Solution Overview
Problem
Existing AC to DC adapters face inefficiencies due to voltage ripples and low peak voltages, leading to reduced efficiency in DC to DC converters, and are often bulky due to the need for high voltage and high capacitance bulk capacitors.
Innovation Solution
The use of selectively switchable capacitors with low voltage ratings and high capacitance, and a series string configuration to increase peak voltage, allowing for reduced adapter size and improved efficiency by managing capacitance based on voltage thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage and high capacitance bulk capacitors are used to reduce voltage ripples, then voltage ripple reduction is improved, but adapter physical size increases
Solution Approach 1:
The bulk capacitor is divided into multiple smaller capacitor modules with lower individual voltage ratings. These modules are connected in series to achieve the required voltage handling capability while each module uses lower capacitance values, significantly reducing the total volume required compared to a single high-voltage high-capacitance capacitor.
Solution Approach 2:
The capacitor modules are dynamically switched in and out of the circuit based on the instantaneous rectified voltage level. When voltage exceeds the capacitor rating, the switching unit disconnects the capacitor module. This dynamic operation allows the use of lower capacitance capacitors that would otherwise be insufficient for ripple reduction, while maintaining safe operating limits.
2Reliability
If high capacitance capacitors are used to reduce voltage ripples, then voltage ripple reduction is improved, but device complexity increases
Solution Approach 1:
The switching unit continuously monitors the rectified voltage level and compares it against the capacitor voltage rating. When the voltage exceeds the rating, the switching unit disconnects the capacitor module; when voltage drops below the rating, the capacitor is reconnected. This feedback control ensures optimal ripple reduction while preventing overvoltage damage, managing the complexity through automated voltage-based decision making.
3Volume of stationary object
If low voltage rating capacitors are used, then adapter physical size is reduced, but voltage ripple reduction capability deteriorates
Solution Approach 1:
Multiple capacitor modules with low individual capacitance values are combined in series configuration. This merging approach allows each capacitor to operate within its safe voltage rating while the combined series string provides sufficient total capacitance for effective voltage ripple reduction, solving both the size and performance requirements simultaneously.
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 approach reduces the physical size of AC to DC adapters while enhancing efficiency by minimizing voltage ripples and optimizing capacitance usage, resulting in a more compact and effective power conversion system.
Implementation Method 1
The switching unit couples the second capacitor in parallel with the first capacitor in the closed state
Implementation Method 2
The first capacitor is configured to reduce a voltage ripple of the DC voltage
Data Source
AI summary
In one example, a circuit includes an alternating current (AC) voltage source, a voltage rail, a reference rail, a first capacitor, a second capacitor, and a switching unit. The AC voltage source is configured to supply voltage in a first direction during a first half of a cycle and supply voltage in a second direction during a second half of the cycle. During a first state of the circuit, the voltage in the first direction supplied by the AC voltage source charges the first capacitor and the voltage in the second direction supplied by the AC voltage source charges the first capacitor. During a second state of the circuit, the voltage in the first direction supplied by the AC voltage source charges the first capacitor and the voltage in the second direction supplied by the AC voltage source charges the second capacitor.