Electric Power Supply Contactor Control via Potential Difference Detection
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Solution Overview
Problem
The existing electric power supply systems for electric vehicles require highly accurate voltage sensors to detect voltage differences across contactors, which increases production and cost hurdles, hindering the popularization of electric vehicles and energy efficiency.
Innovation Solution
An electric power supply system that uses a bi-directional DC-DC converter and an electric potential difference detection circuit to pre-charge smoothing capacitors without needing highly accurate voltage sensors, by temporarily turning on one contactor and monitoring the potential difference to determine the optimal timing for turning on the other contactor, thus avoiding rush currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If highly accurate voltage sensors are used to detect voltages at both ends of the contactor, then the accuracy of voltage detection is improved, but the cost and manufacturing complexity increase
Solution Approach 1:
The patent introduces an electric potential difference detection circuit as an intermediary device that directly measures the voltage difference across the contactor terminals rather than measuring absolute voltages at both ends. This mediator approach simplifies the measurement system by eliminating the need for two high-precision voltage sensors while still providing the necessary information for rush current suppression control.
Solution Approach 2:
The patent extracts only the essential information needed for control - the electric potential difference across the contactor - rather than measuring and processing both absolute voltages. By taking out only the relevant parameter (voltage difference) needed for determining contactor switching timing, the system achieves the required measurement precision with simpler and less expensive components.
2Measurement precision
If highly accurate voltage sensors are used to detect voltages at both ends of the contactor, then the accuracy of voltage detection is improved, but the production cost increases
Solution Approach 1:
The patent replaces expensive, highly accurate voltage sensors with a more economical electric potential difference detection circuit that provides sufficient measurement precision for the application. This substitution uses cheaper components while still achieving the necessary control accuracy for suppressing rush currents, thereby reducing production costs.
Solution Approach 2:
By using an intermediary measurement approach that directly detects voltage difference rather than absolute voltages, the system achieves required measurement precision with lower-cost components, making the overall system more economical to manufacture and deploy.
3Object-generated harmful factors
If a pre-charge circuit with series coupling body is used, then the rush current is suppressed, but the device complexity increases
Solution Approach 1:
The patent employs feedback control by continuously monitoring the electric potential difference across the contactor terminals and using this information to control the timing of contactor switching. The feedback mechanism allows the system to dynamically adjust the switching timing based on real-time voltage difference measurements, effectively suppressing rush currents without requiring complex pre-charge circuits with series coupling bodies.
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
This solution reduces the cost and complexity of the electric power supply system, enabling efficient energy transfer without the need for expensive voltage sensors, thereby facilitating the adoption of electric vehicles and improving overall energy efficiency.
Implementation Method 1
a bi-directional direct current-direct current (DC-DC) converter is used to increase beforehand a voltage on a secondary side of a main contactor
Implementation Method 2
a circuit that supplies electric power from the electric power supply to drive the loads is provided with a smoothing capacitor that stabilizes an electric power supply voltage
Implementation Method 3
an electric potential difference detection circuit that detects an electric potential difference between both ends of the first polarity side contactor
Data Source
AI summary
An electric power supply system includes: a positive-electrode-side contactor inserted into a positive power line; a negative-electrode-side contactor inserted into a negative power line; a pre-charge circuit; an electric potential difference detector that detects an electric potential difference between both ends of the positive-electrode-side contactor; and a contactor controller that receives an output of the electric potential difference detection circuit, and controls the positive-electrode-side contactor and the negative-electrode-side contactor, in which the contactor controller temporarily turns on the positive-electrode-side contactor in a state where the negative-electrode-ide contactor is turned off when the electric power supply system is started, retains an output of the electric potential difference detection circuit during this on period as a correction value, turns off the positive-electrode-side contactor and turns on the negative-electrode-side-contactor after the retention, and turns on the positive-electrode-side contactor when an output of the electric potential difference detection circuit has reached the correction value.