Open-End Winding Battery Charging Using Motor Inverters
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Solution Overview
Problem
Existing vehicle battery charging systems face challenges in efficiently converting charging voltages without additional infrastructure or devices, leading to increased costs and reduced charging power due to voltage restrictions, and relays experience heating and degradation issues with high charging currents.
Innovation Solution
A vehicle battery charging system using a motor driving system with multiple inverters and a controller to convert charging voltages through open-end winding mode, utilizing semiconductor switching elements to connect and disconnect a charging capacitor and neutral terminal, eliminating the need for additional facilities and reducing relay-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relay is used to connect/disconnect the charging capacitor, then the charging system can operate, but the relay experiences heating, degradation, and burning due to large charging currents
Solution Approach 1:
The patent replaces the mechanical relay with semiconductor switching elements (IGBTs or MOSFETs) in the motor driving system. These semiconductor switches can handle large charging currents without the heating and degradation issues that plague mechanical relays, as they use electronic field effects rather than mechanical contacts. The semiconductor switches are integrated into the existing motor driving system, allowing the charging capacitor to be connected/disconnected without requiring a separate relay.
2Adaptability or versatility
If additional charging infrastructure is built to support various battery voltages, then charging compatibility is improved, but construction costs increase significantly
Solution Approach 1:
The patent makes the existing motor driving system perform multiple functions: it can both drive the motor and charge the battery with voltage conversion. By using the same semiconductor switching elements and control system for both motor control and battery charging, the system achieves versatility without requiring separate charging infrastructure. The open-end winding configuration allows the system to handle different battery voltages by appropriately controlling the switching elements.
Solution Approach 2:
The motor driving system charges the battery itself without needing external charging equipment. The system uses its own semiconductor switching elements and control circuitry to perform voltage conversion and charge the battery directly from the power grid, making the vehicle self-sufficient for charging and eliminating the need for specialized charging infrastructure.
3Productivity
If the charging voltage magnitude does not match the battery voltage, then charging cannot proceed efficiently, but voltage conversion requires additional dedicated devices
Solution Approach 1:
The patent merges the voltage conversion function with the existing motor driving system. The semiconductor switching elements and control circuitry that already exist for motor control are also used for voltage conversion during battery charging. This integration eliminates the need for separate voltage conversion devices and reduces overall system complexity while maintaining high charging efficiency.
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
Enables efficient battery charging across various voltages without additional infrastructure, minimizing social costs and improving reliability and efficiency by using semiconductor switching elements instead of relays.
Implementation Method 1
a charging capacitor provided between the second end of the plurality of third switching elements and a negative terminal of the battery, and to which a DC charging voltage is applied in a charging mode for charging the battery
Implementation Method 2
a first inverter including a plurality of first switching elements and having a direct current (DC) terminal connected to the battery and an alternative current (AC) terminal connected to a first end of the plurality of windings; a second inverter including a plurality of second switching elements and having a DC terminal connected to the battery and having an AC terminal connected to a second end of the plurality of windings
Data Source
AI summary
A battery charging system includes a first inverter including first switching elements and DC and AC terminals connected to the battery and a first end of the windings of a motor, respectively; a second inverter including second switching elements and DC and AC terminals connected to the battery and a second end of the windings, respectively; third switching elements each having a first end connected to the second end of the windings and a second end connected to each other; a charging capacitor provided between the second end of the third switching elements and a negative terminal of the battery, and to which a DC charging voltage is applied for charging the battery; a fourth switching element connected in series with the charging capacitor between the second end of the third switching elements and the negative terminal; and a controller configured to control the first to fourth switching elements.