EV Charging Inverter Control for Smoothing Capacitor Discharge
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Solution Overview
Problem
Existing electrified vehicles face the issue of electric charge accumulation in charging smoothing capacitors during battery charging, which can flow into unintended paths, leading to undesirable charging of the battery.
Innovation Solution
Implementing a control device to execute a boosting operation by the inverter to discharge electric charge from the charging smoothing capacitor to the battery side, and using relays to manage the flow of charge through inverters and motors to prevent unintended charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a charging smoothing capacitor is provided in the charging circuit, then the charging efficiency is improved and voltage fluctuations are reduced, but electric charge accumulates in the capacitor after charging is completed and may flow in unintended paths
Solution Approach 1:
The patent extracts the accumulated charge from the charging smoothing capacitor by providing a dedicated discharge path through the inverter to the battery. This separates the charge accumulation function (during charging) from the charge disposal function (after charging), preventing the harmful unintended flow while preserving the beneficial voltage stabilization during charging.
Solution Approach 2:
The inverter serves as an intermediary component that mediates the discharge of accumulated charge from the charging smoothing capacitor to the battery. By controlling the inverter's switching elements, the system creates a controlled path for charge transfer, preventing direct unintended flow while efficiently removing the accumulated charge.
2Object-generated harmful factors
If the inverter executes a boosting operation to discharge charge from the charging smoothing capacitor, then the remaining charge is reduced, but the system complexity increases
Solution Approach 1:
The patent applies multi-functionality to the inverter, which normally converts DC from the battery to AC for the motor. The same inverter is also used to discharge accumulated charge from the charging smoothing capacitor back to the battery through boosting operation. This eliminates the need for separate discharge circuitry, reducing overall system complexity while effectively removing harmful charge accumulation.
Solution Approach 2:
The system changes the operating parameters of the inverter by controlling the switching elements to execute boosting operation at specific times (after charging completion). By dynamically adjusting the inverter's function based on charging state, the system efficiently discharges accumulated charge without requiring additional hardware complexity.
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
Effectively reduces and directs the electric charge accumulated in the charging smoothing capacitor, preventing unintended battery charging and ensuring efficient discharge.
Implementation Method 1
a first inverter that is provided between the battery and the first motor and converts direct current power from the battery to alternating current power supplied to the first motor
Implementation Method 2
a charging smoothing capacitor provided between the charging inlet and the first motor, and after charging of the battery by the charging device is completed, the control device causes the first inverter to execute a boosting operation, and discharges electric charge accumulated in the charging smoothing capacitor
Data Source
AI summary
Electrified vehicle includes a first motor, a battery for supplying power to the first motor, a first inverter for converting DC power from the battery into AC power supplied to the first motor, a charging inlet for receiving charging power for charging the battery, a charging circuit for connecting the charging inlet to the first inverter via a neutral point of the first motor, and a control device for controlling the operation of the first inverter. The charging circuit includes a charging smoothing capacitor provided between the charging inlet and the first motor. After the charging of the battery by the charging device is completed, the control device causes the first inverter to perform the boosting operation to discharge the charge accumulated in the charging smoothing capacitor from the first inverter to the battery side.