Parallel DC/DC Converter Current Sensing Without Ground Impedance Error
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Solution Overview
Problem
Existing power supply systems for electric vehicles face challenges in accurately monitoring the current information of individual DC/DC converters due to complex circuit designs and ground impedance issues, leading to inaccurate current sensing and increased manufacturing costs.
Innovation Solution
A power supply system with a current sensor disposed between the first power supply and the low potential side of DC/DC converters, utilizing a current sensing resistor and pulse-width modulation controller to independently monitor current information of each converter without additional differential amplifiers or potential conversion circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a current sensing resistor is disposed between the low potential output side of the DC/DC converter and the second battery, then the circuit structure is simple, but the current sensing accuracy deteriorates due to different ground impedances of parallel converters
Solution Approach 1:
The patent segments the current sensing function by providing separate current sensing resistors for each DC/DC converter. Instead of using a single shared sensing resistor that suffers from ground impedance issues in parallel configurations, each converter has its own dedicated sensing resistor connected to a common reference potential, enabling independent and accurate current measurement for each converter channel.
2Measurement precision
If a current sensing resistor is disposed on the high-potential output side of the DC/DC converter, then the current sensing accuracy is improved, but the device complexity increases due to additional differential amplifier circuits and potential conversion circuits
Solution Approach 1:
The patent inverts the conventional approach by placing the current sensing resistor on the low-potential side rather than the high-potential side. This inversion allows the sensing resistor to be connected directly to a stable reference potential without requiring complex differential amplification or potential conversion circuits, thereby achieving accurate current sensing with a simplified circuit structure.
3Power
If multiple DC/DC converters are used in parallel for high power output, then the power output capability is improved, but the current monitoring capability deteriorates due to ground impedance issues preventing individual converter monitoring
Solution Approach 1:
The patent applies segmentation by providing dedicated current sensing resistors for each DC/DC converter in the parallel configuration. Each converter's current can be independently measured through its own sensing resistor connected to the common reference potential, preserving individual converter current information while maintaining the high power output capability of the parallel multi-converter system.
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 accurate and cost-effective monitoring of individual DC/DC converter currents with a simple circuit structure, improving sensing accuracy and reducing manufacturing costs.
Implementation Method 1
a current sensor comprising a sensing resistor disposed between the first power supply and a low potential side of the DC/DC converters
Data Source
AI summary
A power supply system for outputting current to a load comprises a first power supply, a plurality of DC/DC converters connected to the first power supply in parallel, a second power source connected in parallel with the DC/DC converters and coupled to the load and a current sensor. The current sensor is configured between the first power supply and a low potential side of input terminals of the plurality of DC/DC converters, and the current sensor is configured for sensing a current information of the power supply system. When the power supply system outputs current to the load or the load can be charged back to the power supply system, the current sensor can measure the current information of each DC/DC converter through the current change of the switching states of the power switches inside the DC/DC converters, and has a simple circuit structure.