Capacitive Power Conversion Circuit for Fast Charging
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Solution Overview
Problem
Existing capacitive power conversion circuits face challenges in optimizing charging current and efficiency, requiring specialized cables and larger diameters for faster charging, and struggle with optimizing inductor and switch specifications in switching conversion circuits.
Innovation Solution
A capacitive power conversion circuit using a conversion switch circuit with plural conversion switches and capacitors, controlled by a conversion control circuit to scale up charging and supply voltages and currents, allowing for increased charging current without the need for an inductor, using standard cables and optimizing component selection for efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a standard USB cable is used for charging, then the cable is flexible and easy to use, but the maximum charging current is limited to 5A or lower resulting in longer charging time
Solution Approach 1:
The patent changes the electrical parameters of the charging system by introducing a capacitive power conversion circuit that transforms the current relationship between input and output. The circuit uses capacitive switching to achieve current scaling, where the charging current can be a multiple of the input current from a standard USB cable, thereby enabling fast charging through standard cables without modifying the cable itself.
2Loss of time
If a specially-designed fast charging cable with larger diameter is used to raise charging current to 8A or higher, then the charging time is reduced, but the cable is less flexible and less convenient to use
Solution Approach 1:
The patent extracts the current scaling function from the cable itself and relocates it to a separate capacitive power conversion circuit. This allows the cable to remain a standard, flexible USB cable while the circuit handles the current transformation, achieving fast charging without requiring specialized high-current cables.
3Power
If a switching conversion circuit with inductor is used to convert power and increase charging current, then the charging current can exceed the DC current from adaptor, but it is very difficult to optimize the specifications of inductor and switches resulting in suboptimal power conversion efficiency
Solution Approach 1:
The patent substitutes the traditional inductor-based magnetic energy storage mechanism with a capacitive switching mechanism. Instead of using an inductor to store and transfer energy magnetically, the circuit uses capacitors to store and transfer energy electrically through switching operations. This substitution simplifies the optimization process as capacitive circuits have fewer parameters to tune compared to inductive switching circuits.
4Power
If a switching conversion circuit with inductor is used for power conversion, then the charging current can be increased, but the circuit size increases due to the inductor component
Solution Approach 1:
The patent removes the inductor component from the power conversion circuit and replaces it with a capacitive switching architecture. This extraction of the magnetic energy storage element eliminates the need for bulky inductors, thereby reducing the overall circuit size while maintaining the ability to perform power conversion and current scaling.
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
Enables faster battery charging with standard cables by scaling up charging current and voltage efficiently, reducing charging time and circuit size and cost while maintaining high power conversion efficiency.
Implementation Method 1
the switch control signal operates the plural conversion switches so as to electrically connect the one or more conversion capacitors between a pair of nodes selected from one or more charging voltage division nodes, the DC output voltage, and a ground node periodically during plural charging conversion time periods, such that the charging current is scaled-up of the DC current
Implementation Method 2
the switch control signal operates the plural conversion switches so as to electrically connect the one or more conversion capacitors between a pair of nodes selected from one or more supply voltage division nodes, the battery voltage, and the ground node periodically during plural supply conversion time periods, to generate an output signal on one of the one or more supply voltage division nodes, and generate a supply voltage on the bus node according to the output signal, such that the supply voltage is scaled-up of the battery voltage
Data Source
AI summary
A capacitive power converter circuit converts a DC power from a bus node to a charging power for charging a battery in a charging mode, and converts a battery voltage to a supply voltage through the bus node in a supply mode. The capacitive power converter circuit includes a conversion switch circuit including plural conversion switches configured to be operably coupled to one or more conversion capacitors, and a conversion control circuit for controlling the plural conversion switches. In the charging mode, the plural conversion switches control the conversion capacitors such that the charging current is scaled-up, and in the supply mode, the plural conversion switches control the conversion capacitors such that the supply voltage is scaled-up.