Switched Capacitor DC-DC Converter Pulse Frequency Modulation
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Solution Overview
Problem
Switched capacitor dc-dc converters experience significant switching losses due to the consistent operation of switches regardless of load current, leading to inefficiencies as they consume power for switching events regardless of the load being supplied.
Innovation Solution
The solution involves modifying the switching characteristics based on load characteristics by selectively activating or deactivating individual switches or groups of switches, using digital controllers to adjust switch impedance and employing sub-switches, allowing for precise control of switching events and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switches operate consistently regardless of load current, then the converter maintains stable switching operation, but switching losses increase and efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the switching operation adaptive rather than fixed. The controller dynamically adjusts the switching frequency and duty cycle based on real-time load current detection. When load current is low, the switching frequency is reduced to minimize switching losses. When load current is high, the switching frequency increases to maintain adequate power delivery. This dynamic adaptation resolves the contradiction between stable operation and energy loss.
Solution Approach 2:
The patent changes key operating parameters (switching frequency and duty cycle) based on load conditions. The controller monitors load current and adjusts the switching frequency parameter accordingly - lowering it during light loads to reduce switching losses, and raising it during heavy loads to maintain performance. This parameter adjustment strategy directly addresses the contradiction by making losses dependent on actual power delivery needs.
2Device complexity
If the same number of switches are used for a wide range of load currents, then the converter design is simplified, but switching losses do not scale with load current
Solution Approach 1:
The patent maintains a fixed switch configuration (simplifying device complexity) while dynamically adjusting the switching frequency and duty cycle based on load current. This approach allows the same physical switches to operate efficiently across different load conditions by changing operational parameters rather than physical configuration. The controller adapts the timing and duration of switch operations to match load demands, reducing losses without requiring complex reconfigurable switch networks.
3Loss of energy
If switching frequency is reduced to minimize switching losses, then energy efficiency improves, but the ability to regulate output voltage under varying load conditions deteriorates
Solution Approach 1:
The patent dynamically adjusts both switching frequency and duty cycle in coordination. When switching frequency is reduced to minimize losses during light loads, the duty cycle is simultaneously adjusted to maintain the required output voltage. The controller continuously monitors output voltage and load current, making real-time adjustments to both parameters to maintain regulation while optimizing efficiency. This coordinated dynamic control resolves the contradiction between loss reduction and voltage regulation.
Solution Approach 2:
The patent employs feedback control where the controller monitors output voltage and load current, then adjusts switching frequency and duty cycle accordingly. The feedback loop ensures that even when switching frequency is reduced to minimize losses, the output voltage remains properly regulated by adjusting the duty cycle to compensate. This closed-loop control mechanism maintains reliability while achieving energy efficiency.
Data Source
AI summary
Representative implementations of devices and techniques minimize switching losses in a switched capacitor de-de converter. Variable frequency control, including Pulse frequency modulation, is used to control switching based on an existing load. As an example, a system may include a direct current to direct current converter (dc-dc converter) including an energy storage element, switches coupled to the energy storage element, and a digital controller arranged to modulate a switch timing of at least one switch of the switches by adjustment of a transition of a signal pulse provided to adjust an impedance of the at least one switch based on a load coupled to an output of the dc-dc converter.