Vehicle Battery Charging Circuit Harmonic Damping
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Solution Overview
Problem
Existing circuit arrangements for charging vehicle batteries in vehicles generate impermissibly high harmonic currents in the network, necessitating measures to reduce harmonic content while avoiding the use of expensive and bulky components.
Innovation Solution
A second inverter is connected to the second star-connected windings of the electric drive motor, sharing a common star point with the first inverter, which can be separated to form a three-phase reactor or choke, damping harmonics during charging and allowing for dual functionality in driving and charging operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter and windings are used to charge the vehicle batteries, then the charging function is achieved, but the harmonic currents absorbed by the network become impermissibly high
Solution Approach 1:
The patent combines the drive motor windings with the charging circuit by connecting the inverter to the battery charger through the motor windings. The windings serve dual purposes: driving the motor during operation and functioning as a three-phase reactor for harmonic damping during charging. This merging eliminates the need for separate damping components while reducing network harmonic currents to permissible levels.
Solution Approach 2:
The drive motor windings are designed to perform multiple functions: they serve as armature windings during driving operation and as a three-phase reactor for harmonic damping during battery charging. The inverter similarly operates in both driving mode (converting DC to three-phase AC) and charging mode (functioning as a controlled rectifier). This multi-functionality reduces component count and eliminates the need for additional expensive damping equipment.
2Object-generated harmful factors
If additional components are added to reduce harmonic content, then the harmonic loading is reduced, but expensive components with large volume and weight are required
Solution Approach 1:
The patent merges the function of harmonic damping into the existing drive motor windings and inverter circuitry. By configuring the windings to operate as a three-phase reactor during charging and using the inverter in rectifier mode, the system achieves harmonic damping without requiring separate reactors, filters, or other additional components. This eliminates the weight and volume that would be required for dedicated harmonic reduction equipment.
Solution Approach 2:
The drive motor windings and inverter serve themselves by performing both driving and charging functions. The windings automatically function as a damping reactor when configured for charging, and the inverter automatically operates as a controlled rectifier. This self-service capability eliminates the need for additional components that would otherwise be required to reduce harmonic loading on the network.
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 effectively reduces harmonic loading on the network, eliminates the need for additional costly components, and ensures the drive motor remains torque-free during charging, enabling continued operation with reduced power if one inverter fails.
Implementation Method 1
the first and second windings together form a three-phase reactor for damping harmonics
Implementation Method 2
a first inverter (I1) connected downstream of the vehicle batteries (1), to which the first star-connected windings (U1, V1, W1) of an electric drive motor are connected, and which can be connected to a three-phase network for charging the vehicle batteries
Data Source
AI summary
The invention relates to a circuit arrangement for the charging of vehicle batteries (1) in a vehicle. The circuit arrangement comprises a first inverter (I1) mounted downstream of the vehicle batteries (1), to which first windings (U1, V1, W1) of an electric drive motor are connected and which can be connected to a DC network for the charging operation of the vehicle batteries. Furthermore, a second inverter (I2) is provided and mounted downstream of the vehicle batteries, to which second windings (U2, V2, W2) of the electric drive motor are connected. According to the invention, the first (U1, V1, W1) and second windings (U2, V2, W2) have a common star point which is formed in the closed state by a switch (S) and which can be separated for the charging operation by opening the switch (S). In this way, the first (U1, V1, W1) and second windings (U2, V2, W2) together form a DC throttle for damping harmonics.