On-Board Charger Precharge Control for Soft-Start Current Suppression
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Solution Overview
Problem
The existing on-board chargers (OBCs) for electric vehicles face damage due to large instantaneous currents when starting the charging process, which is mitigated by adding a soft-start circuit, but this increases circuit complexity and hinders miniaturization.
Innovation Solution
A charger design that precharges a bus capacitor using battery energy, allowing the control module to send a signal to the charging pile to initiate charging when the capacitor voltage reaches a threshold, thereby reducing the instantaneous current without the need for a soft-start circuit, simplifying the circuit structure and facilitating miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a soft-start circuit is disposed in the OBC to reduce instantaneous current, then the charger is protected from damage, but the circuit complexity increases and miniaturization is hindered
Solution Approach 1:
The patent applies preliminary action by precharging the bus capacitor using battery energy before the charging pile starts outputting charging electric energy. The control module controls the DC-DC conversion circuit to charge the first capacitor by using battery electric energy output by the battery system, and only after the capacitance voltage of the first capacitor reaches a first threshold voltage does it send first indication information to the charging pile to output charging electric energy. This preliminary charging action eliminates the need for a soft-start circuit while protecting the charger from instantaneous current damage.
2Reliability
If a soft-start circuit is disposed in the OBC to reduce instantaneous current, then the charger is protected from damage, but miniaturization of the charger is hindered
Solution Approach 1:
The patent applies preliminary action by precharging the bus capacitor using battery energy before the charging pile starts outputting charging electric energy. The control module controls the DC-DC conversion circuit to charge the first capacitor by using battery electric energy output by the battery system, and only after the capacitance voltage of the first capacitor reaches a first threshold voltage does it send first indication information to the charging pile to output charging electric energy. This preliminary charging action eliminates the need for a soft-start circuit while protecting the charger from instantaneous current damage.
3Productivity
If the bus capacitor is directly connected to the charging pile, then the charging process is simple, but large instantaneous current damages the charger
Solution Approach 1:
The patent applies preliminary action by precharging the bus capacitor using battery energy before the charging pile starts outputting charging electric energy. The control module controls the DC-DC conversion circuit to charge the first capacitor by using battery electric energy output by the battery system, and only after the capacitance voltage of the first capacitor reaches a first threshold voltage does it send first indication information to the charging pile to output charging electric energy. This preliminary charging action eliminates the need for a soft-start circuit while protecting the charger from instantaneous current damage.
Solution Approach 2:
The patent uses the battery system as an intermediary to precharge the bus capacitor. The battery system provides battery electric energy to the DC-DC conversion circuit, which charges the first capacitor (bus capacitor) before the charging pile connects. This intermediary charging process prevents large instantaneous current from the charging pile while maintaining efficient energy transfer.
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 approach effectively reduces the instantaneous current at the start of charging, protecting the charger and enabling miniaturization by eliminating the need for a soft-start circuit, while ensuring efficient energy transfer and adaptation to various charging voltage types.
Implementation Method 1
A bus capacitor may be disposed in the OBC and the bus capacitor may filter the charging electric energy transmitted in the OBC
Implementation Method 2
The OBC may receive charging electric energy provided by a charging pile, and convert a voltage of the charging electric energy, so that a converted voltage of the charging electric energy can adapt to the power battery
Data Source
AI summary
A charger, a soft-start method, an electric vehicle, and a charging system. The charger includes a control module, a DC-DC conversion circuit, and a first capacitor. When the electric vehicle is charged, the control module in the charger may first control the DC-DC conversion circuit to charge the first capacitor by using battery electric energy output by a battery system, and after determining that a capacitance voltage of the first capacitor reaches a first threshold voltage, indicate a charging pile to output charging electric energy. A soft-start circuit does not need to be disposed in a soft-start process of the charger, which helps simplify a circuit of the charger and implement a miniaturization design of the charger.