Switched Capacitor Converter Control for Small Inductors
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Solution Overview
Problem
Conventional switched capacitor voltage converters face challenges in regulating output voltage and require large inductors to handle high input voltages, leading to increased switching losses and component size.
Innovation Solution
A switched capacitor voltage converter circuit and control method that uses pulse width modulation (PWM) and zero current detection signals to control a switched capacitor converter, allowing for unidirectional conduction and resonant processes to convert voltages efficiently, reducing switching losses and component size by eliminating the need for voltage balancing and using smaller inductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional buck converter uses a higher switching frequency to reduce inductor size, then the inductor size is reduced, but the switching power loss increases significantly
Solution Approach 1:
The patent employs periodic resonant oscillation between the inductor and capacitor to transfer energy, replacing traditional PWM switching with zero-voltage switching. The resonant tank circuit naturally oscillates at a specific frequency, enabling periodic energy transfer without requiring high-frequency switching operations, thus reducing switching losses while maintaining compact inductor design
Solution Approach 2:
The patent utilizes phase transition in the resonant current, where the current naturally reaches zero crossing points during resonant oscillation. This zero-current phase transition enables lossless switching moments, allowing the converter to transfer energy efficiently without the power losses associated with traditional hard switching methods
2Stress or pressure
If a conventional buck converter uses an inductor to withstand high input voltage, then the voltage handling capability is achieved, but the inductor requires large size and high inductance
Solution Approach 1:
The patent segments the voltage handling function by introducing a resonant capacitor that shares the voltage stress with the inductor. Instead of requiring the inductor alone to withstand the full input voltage, the resonant tank circuit divides the voltage stress between the inductor and capacitor through their series connection during resonant operation, enabling smaller inductor design
Solution Approach 2:
The resonant capacitor acts as an intermediary element between the input voltage source and the inductor. It mediates the voltage stress by creating a resonant relationship with the inductor, where the combined resonant tank system handles the voltage requirement rather than the inductor alone, reducing the inductor's size and inductance requirements
3Device complexity
If a voltage divider configuration is used for voltage conversion, then the circuit simplicity is maintained, but the output voltage cannot be regulated when input voltage changes
Solution Approach 1:
The patent transforms the static voltage divider into a dynamic resonant converter. The resonant tank circuit allows the system to adapt its operating characteristics based on input voltage conditions while maintaining a relatively simple circuit structure. The dynamic resonant oscillation enables voltage regulation capability without significantly increasing circuit complexity
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
The solution achieves zero current and zero voltage switching, reduces switching losses, and allows for adjustable output voltage with smaller, less stressed components, enhancing efficiency and reducing component size and cost.
Implementation Method 1
the resonant capacitor and the corresponding one of the at least one inductor are connected in series between the second voltage and a second DC potential, so as to form a first current path, so that the inductor current flowing through the at least one inductor and flowing toward the second voltage is a resonant current having a first resonant frequency
Data Source
AI summary
A switched capacitor voltage converter circuit includes: a switched capacitor converter and a control circuit. The switched capacitor converter includes at least one resonant capacitor, switches and at least one inductor. The control circuit generates a pulse width modulation (PWM) signal according to a first voltage or a second voltage and generates a control signal according to the PWM signal and a zero current detection signal. The control signal controls the switched capacitor converter by operating the corresponding switches to switch electrical connection of the inductor, so as to convert the first voltage to the second voltage or convert the second voltage to the first voltage.