EV Power Supply Relay Precharge Verification
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Solution Overview
Problem
The existing power supply systems for electric vehicles may experience a large current flow into the capacitor when the relay is closed, potentially damaging the capacitor and relay, due to voltage variations of the main power source after precharging is completed but before the relay is activated.
Innovation Solution
A power supply system with a controller that sets a target voltage based on the main power source measurement, uses a voltage converter to precharge the capacitor within a predetermined tolerance, and verifies the voltage difference before closing the relay to prevent large current flow, ensuring the capacitor is precharged accurately and safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the relay is closed immediately after precharging is completed, then the operation speed is improved, but a large current may flow into the capacitor causing damage
Solution Approach 1:
The system performs a preliminary verification of the voltage difference between the main power source and capacitor before closing the relay. The controller checks whether the voltage difference is within a predetermined threshold, and only closes the relay when the verification confirms safe conditions. This preliminary verification action prevents large current flow while enabling timely relay closure.
2Reliability
If the voltage difference threshold is set strictly to prevent large current, then the safety is improved, but the relay closure may be delayed
Solution Approach 1:
The system dynamically adjusts the voltage difference threshold parameter based on system conditions. The controller compares the real-time voltage difference between the main power source and capacitor against a predetermined threshold, and closes the relay when the parameter satisfies the safety condition. This parameter-based control ensures both safety and timely operation.
3Measurement precision
If the voltage converter is used to precharge the capacitor, then the voltage control precision is improved, but the device complexity increases
Solution Approach 1:
The voltage converter acts as an intermediary device between the main power source and the capacitor during the precharging phase. It provides controlled voltage transfer with precise regulation, ensuring the capacitor is charged to the appropriate voltage level before relay closure. The intermediary function enables precise voltage control while isolating the main power source from direct capacitor charging.
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 reliably prevents large currents from flowing into the capacitor when the relay is closed, maintaining voltage stability and preventing potential damage to the capacitor and relay, thereby ensuring safe and efficient operation of the power supply system.
Implementation Method 1
a voltage converter configured to charge the capacitor by boosting an output voltage of the auxiliary power source
Data Source
AI summary
A power supply system disclosed herein may include: a first voltage sensor measuring voltage of a main power source; a power converter connected to a main power source through a relay; a voltage converter; and a controller. The power converter includes a capacitor connected to the main power source and a second voltage sensor measuring voltage of the capacitor. The controller precharges the capacitor with the voltage converter before closing the relay. The controller may be configured to: set target voltage by a measurement value of the first voltage sensor; acquire the measurement value of the first voltage sensor again as verification voltage when a difference between the target voltage and control voltage which is a measurement value measured by the third voltage sensor has fallen within a predetermined tolerance; and close the relay if a difference between the control voltage and the verification voltage is within the tolerance.