Motor Controller Boost Charging for Low-Voltage DC Pile Compatibility
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Solution Overview
Problem
Current charging systems face difficulties in charging high-voltage power batteries due to the limited voltage of most low-voltage DC charging piles, which cannot meet the high-voltage requirements of modern electric vehicles, leading to charging inefficiencies and incompatibilities.
Innovation Solution
A charging system that includes a power module, a permanent magnet synchronous motor, and a control strategy using a CAN bus to switch between DC boost and direct charging circuits, allowing the system to convert low-voltage DC from charging piles to high-voltage DC for battery charging without an external boost module, utilizing the motor winding and power module to achieve voltage boosting through interleaving control of the motor winding inductances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-voltage power battery is used to increase vehicle driving range and power, then the vehicle performance is improved, but the compatibility with existing low-voltage DC charging piles deteriorates
Solution Approach 1:
The motor controller acts as an intermediary device that bridges the voltage gap between low-voltage DC charging piles and high-voltage power batteries. By utilizing the existing motor winding inductances as boost inductors and controlling the power module switches, the system converts low-voltage DC to high-voltage DC, enabling compatibility with existing charging infrastructure while maintaining high-voltage battery performance
Solution Approach 2:
The motor controller is designed to perform multiple functions: it not only controls the permanent magnet synchronous motor for vehicle propulsion but also serves as a DC-DC boost converter for charging. The power module and motor winding inductances are utilized for both motor operation and voltage boosting during charging, eliminating the need for separate dedicated components
2Adaptability or versatility
If an external boost module is added to enable low-voltage DC to high-voltage DC conversion, then charging compatibility is improved, but device complexity and cost increase
Solution Approach 1:
The charging boost function is merged with the existing motor controller, power module, and motor winding inductances. By combining these existing components into a unified DC-DC boost conversion system, the patent eliminates the need for separate external boost modules, reducing overall system complexity and cost while achieving voltage conversion capability
Solution Approach 2:
The motor controller and existing motor components serve dual purposes: they provide both motor propulsion functionality and voltage boosting capability for charging. The system uses its own existing components (power module switches and motor winding inductances) to perform the boost conversion, rather than relying on external dedicated equipment
3Device complexity
If traditional DC charging circuit is used directly from charging pile to battery, then the charging system is simple, but it cannot charge when charging pile voltage is lower than battery voltage
Solution Approach 1:
The charging system dynamically switches between direct charging mode and boost charging mode based on voltage compatibility. The controller detects the charging pile voltage and automatically selects the appropriate charging path: direct connection when voltages match, or boost conversion when the charging pile voltage is lower than the battery voltage, providing adaptive voltage compatibility
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 enables electric vehicles to be compatible with low-voltage DC charging piles, reducing costs by eliminating the need for an external boost module, improving charging convenience, and minimizing energy losses through interleaving control, which reduces current ripple and output fluctuations.
Implementation Method 1
the motor controller is configured to control lower three-phase bridge arms to perform interleaved charging, and when one inductance of the motor winding is turned on, a charging time required for the current thereof to reach the maximum is t1-t0; when one inductance of the motor winding is turned off, a discharging time required for the current thereof to reduce to the minimum is t3-t2
Data Source
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AI summary
A charging system compatible with a low-voltage DC charging pile, a control method and a vehicle are provided. The charging system includes a power module, a motor winding, a motor controller, a battery controller and a vehicle controller, further includes a third switch module to connect with a power battery; and a first and a second switch module. Input ends of the first and second switch modules are connected with a high-voltage output end of the charging pile, output end of the first switch module passes through motor winding, power module to third switch module to form a DC boost charging circuit; output end of the second switch module connects the third switch module to form a DC charging circuit. The first, second and third switch modules are connected to and controlled by the motor controller.