Multi-Input EV Charging via Motor Inverter Neutral Point
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Solution Overview
Problem
In electric vehicle charging systems, high-capacity converters are not feasible due to weight, volume, and cost constraints, and there is a risk of electrical shock from capacitors not being promptly discharged after charging, which poses safety hazards.
Innovation Solution
A multi-input charging system using a motor driving system that includes relays and a controller to manage the charging process, allowing for direct application of charging power to the battery or boosting voltage through an inverter, and compulsorily discharging capacitors after charging is completed to ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-capacity converter is used to boost voltage for battery charging, then the battery charging capability is improved, but the vehicle weight, volume, and cost increase significantly
Solution Approach 1:
The inverter is designed to perform multiple functions: it serves as both the motor drive inverter and the charging inverter. By utilizing the existing inverter and motor neutral point for charging operations, the system eliminates the need for a separate high-capacity boosting converter, thereby reducing vehicle weight, volume, and cost while maintaining battery charging capability
Solution Approach 2:
The patent merges the charging function with the existing motor drive inverter. The inverter that originally only served motor control now also handles battery charging by utilizing the motor neutral point as a charging interface, combining two separate functions into one device
2Adaptability or versatility
If capacitors are used to form neutral point voltage during charging, then the charging system functionality is improved, but the risk of electrical shock increases if capacitors are not promptly discharged
Solution Approach 1:
The system performs preliminary discharge action by automatically activating the discharging inverter operation immediately after charging completion. The controller detects charging termination and promptly initiates capacitor discharge through the inverter, preventing dangerous voltage accumulation before it can cause electrical shock
Solution Approach 2:
The inverter serves as an intermediary device that safely discharges the capacitors after charging. By using the inverter's switching elements and motor neutral point as a discharge path, the system provides a controlled intermediate step to dissipate capacitor energy safely rather than allowing dangerous voltage buildup
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
The system effectively eliminates the risk of electrical shock and reduces costs by avoiding the need for additional devices, while ensuring safe and efficient battery charging across various external charging voltages.
Implementation Method 1
boosting a voltage without an additional device and an additional increase in costs, providing the boosted voltage to a battery
Implementation Method 2
boosting the voltage of the motor neutral point to a voltage level that may charge the voltage by using a coil of the motor
Implementation Method 3
a high voltage of at least 400 to 800 V is formed in a capacitor that forms a neutral point voltage and a capacitor that forms an inverter output voltage
Data Source
AI summary
A multi-input charging system and a multi-input charging method using a motor driving system can promptly compulsorily discharge a high charging voltage formed in a neutral point capacitor forming a neutral point voltage in a charging process and formed in a DC capacitor between an inverter and a battery.