Bidirectional Converter Droop Sharing With Single Current Sensing
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Solution Overview
Problem
Bidirectional converters require a significant number of components due to dual current-sensing circuits, leading to increased costs and reduced efficiency from power dissipation through current-sensing resistors, especially in high-current applications.
Innovation Solution
Implement current sensing at only one input/output terminal of each bidirectional converter, using a single current-sensing circuit to modify the output voltage based on sensed current, and incorporate a pulse-width modulator and voltage measurement circuit to regulate the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two current-sensing circuits are provided for bidirectional operation, then current sensing accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the single current-sensing circuit bidirectional by connecting it to both input and output terminals through switching mechanisms. The same circuit serves dual purposes: sensing input current during charging and output current during discharging, eliminating the need for separate sensing circuits while maintaining measurement accuracy
Solution Approach 2:
The patent combines two separate current-sensing circuits into one shared circuit. By using a single current-sensing resistor and amplifier that can measure current in both directions, the design merges previously separate functions into a unified sensing system, reducing component count and complexity
2Measurement precision
If two current-sensing circuits are provided for bidirectional operation, then current sensing capability is improved, but manufacturing cost increases
Solution Approach 1:
The single current-sensing circuit is designed to perform multiple functions by sensing current in both charging and discharging modes. This universal approach reduces the bill of materials by eliminating redundant current-sensing resistors, amplifiers, and associated components, directly lowering manufacturing costs
Solution Approach 2:
By merging two separate current-sensing circuits into one, the patent reduces component procurement costs, assembly costs, and testing complexity. The unified circuit requires fewer discrete parts and simplifies the manufacturing process while maintaining full bidirectional sensing capability
3Measurement precision
If current-sensing resistors are implemented, then current sensing is achieved, but power dissipation increases and efficiency decreases
Solution Approach 1:
The patent reduces power dissipation by optimizing the current-sensing resistor value and using high-precision, low-ohmic resistors. By carefully selecting resistor parameters and using differential sensing techniques, the system achieves accurate current measurement while minimizing I²R losses and improving overall efficiency
Solution Approach 2:
The patent replaces traditional high-power current-sensing resistor approaches with more efficient sensing methods, including using the MOSFET on-resistance for sensing in certain modes and employing high-precision low-power amplifier circuits that require minimal sense voltage, thereby reducing power dissipation
4Loss of energy
If multiple resistors are provided in parallel to reduce power dissipation, then power efficiency is improved, but circuit footprint increases
Solution Approach 1:
The patent uses a single current-sensing resistor rather than multiple parallel resistors, which consolidates the sensing function into one compact component. This approach minimizes the PCB footprint and reduces the overall circuit area while achieving acceptable power dissipation through optimized resistor selection and efficient sensing architecture
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
Reduces the number of components, lowers costs, and enhances efficiency by minimizing power dissipation and circuit footprint while maintaining effective current sharing.
Implementation Method 1
The current-sensing circuit may include a current-sensing resistor through which the current flows
Implementation Method 2
Droop current sharing can be provided by a variety of implementations, including providing a series resistance for a parallel connection of electrical modules such that an output voltage droops across the series resistance
Data Source
AI summary
A bidirectional converter includes first and second terminals between which a current flows and a current-sensing circuit electrically connected to only one of the first and the second terminals to sense the current. Current sensing is only performed at the one of the first terminal and the second terminal to which the current-sensing circuit is connected, and an output voltage of the bidirectional converter droops based on the sensed current.