Multi-Mode Battery Inverter Circuit for Vehicle DC Voltage
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Solution Overview
Problem
Existing circuit arrangements for electric vehicles fail to efficiently manage the reception of electric power for charging battery cells, output of electric power to the drive, and provision of DC voltage for vehicle electrical systems, especially at low motor speeds or when stationary, with high technical complexity and component count.
Innovation Solution
A circuit arrangement featuring multiple battery direct inverters connected via switching devices, a DC voltage section for providing DC voltage, and a charging section that includes a bridge rectifier and EMC filter, with a control unit for managing switching devices and voltage distribution, allowing for flexible operation during charging and driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate circuit arrangements are used for charging, driving, and DC voltage provision, then functional reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines three separate circuit arrangements (charging circuit, driving circuit, and DC voltage provision circuit) into a single integrated circuit arrangement. The battery direct inverter serves as a common component that can operate in three different modes: charging mode (rectifying AC to DC), driving mode (converting DC to three-phase AC for the motor), and DC voltage provision mode (providing DC voltage to the vehicle electrical system). This merging eliminates the need for separate dedicated circuits for each function, thereby reducing device complexity while maintaining functional reliability through a single multi-functional system.
Solution Approach 2:
The battery direct inverter is designed as a universal component that can perform multiple functions depending on the operating state. It can function as a rectifier for charging, as an inverter for motor driving, and as a DC-DC converter for providing DC voltage to the vehicle electrical system. The control unit manages the switching between these different operating states, allowing a single component to replace multiple specialized components, thus reducing overall system complexity while ensuring reliable performance across all functions.
2Reliability
If dedicated charging circuits are used, then charging reliability is improved, but technical complexity and component count increase
Solution Approach 1:
The charging function is merged into the battery direct inverter circuit rather than using a separate dedicated charging circuit. The same power electronic components and control mechanisms used for motor driving are also utilized for charging operations. During charging, the battery direct inverter operates in rectifier mode to convert AC charging voltage to DC for battery charging. This merging approach ensures charging reliability through proven hardware while significantly reducing technical complexity and component count compared to dedicated separate circuits.
3Reliability
If separate DC voltage provision circuits are used, then DC voltage reliability is improved, but device complexity increases
Solution Approach 1:
The DC voltage provision function is merged into the battery direct inverter circuit. During DC voltage provision mode, the battery direct inverter converts battery DC voltage to a regulated DC voltage suitable for the vehicle electrical system (12V or 24V). The same power electronic switches, diodes, and control unit that manage motor driving and charging operations are reused for DC voltage provision. This integration ensures reliable DC voltage output through proven hardware while reducing circuit complexity by eliminating separate dedicated DC-DC converter circuits.
4Adaptability or versatility
If multiple battery direct inverters are used for different functions, then functional versatility is improved, but device complexity increases
Solution Approach 1:
Instead of using multiple separate battery direct inverters for different functions (charging, driving, DC voltage provision), the patent employs a single universal battery direct inverter that can perform all three functions. The control unit switches the operating state of the single inverter based on the required function: rectifier mode for charging, inverter mode for motor driving, and DC-DC converter mode for DC voltage provision. This approach achieves full functional versatility while reducing circuit complexity by a factor of three compared to using separate dedicated inverters for each function.
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 reception of electrical energy from the grid, output to the drive, and feeding of vehicle electrical components with DC voltage across all operating states, reducing technical complexity and harmonic distortion while maintaining power factor control.
Implementation Method 1
the charging section includes a bridge rectifier circuit for rectifying an input voltage
Implementation Method 2
the charging section includes a grid filter or EMC filter for filtering an input voltage
Implementation Method 3
a first battery direct inverter is connectable to the electric machine via a first switching device
Data Source
AI summary
The present invention relates to a circuit arrangement (100) for operating an electrical machine (101) in a motor vehicle, having a first electrical drive train (103-1) in which a first battery direct converter (105-1) can be connected to the electrical machine (101) via a first switching device (107-1); a second electrical drive train (103-2) in which a second battery direct converter (105-2) can be connected to the electrical machine (101) via a second switching device (107-2); a third electrical drive train (103-3) in which a third battery direct converter (105-3) is connected to the electrical machine (101), one converter connection of which can be connected to the second drive train (103-2) via a third switching device (107-3) and the other converter connection of which can be connected to the second drive train (103-2) via a fourth switching device (107-4); a DC voltage section (109) for providing a DC voltage for a vehicle electrical system, which DC voltage section is connected to the first, second and third drive trains (103-1, 103-2, 103-3) via a rectifier (111-1, 111-2, 111-3) in each case; and a charging section (113) for supplying a charging current to the first, second and third battery direct converters (105-1, 105-2, 105-3), which charging section is connected to the first drive train (103-1) and to the third drive train (103-3).