Hybrid Battery Voltage Control via Selective Power Interruption
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Solution Overview
Problem
The performance of electric machines in vehicle powertrain systems is constrained by the magnitude of the DC voltage at the DC link to the inverter, limiting mechanical power output, and existing solutions to increase voltage, such as using higher voltage batteries or adding DC/DC boost converters, increase system complexity and weight.
Innovation Solution
A hybrid powertrain system with a high-voltage electric circuit including a high-voltage battery and a DC link coupled to first and second inverters, where a method for operating the system involves receiving a motor torque command and selectively interrupting electric power flow between the battery and the DC link to achieve a preferred DC link voltage, allowing for increased voltage without adding weight or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the DC voltage at the DC link is increased to improve mechanical power output from the electric machine, then the motor torque output is improved, but the system complexity and weight increase due to requiring higher voltage batteries or DC/DC boost converters
Solution Approach 1:
The patent changes the operating voltage parameter dynamically by selectively connecting different high-voltage battery modules (first set with higher voltage, second set with lower voltage) to the DC link based on power demand conditions. This allows the system to achieve higher mechanical power output when needed by using the higher voltage battery modules, while avoiding increased system complexity by not requiring permanent DC/DC converters or higher voltage infrastructure throughout the system.
Solution Approach 2:
The high-voltage battery system is segmented into multiple battery modules (first set and second set of high-voltage battery modules) with different voltage characteristics. This segmentation allows selective connection of appropriate modules to the DC link based on power requirements, enabling the system to achieve higher power output when needed without permanently increasing system complexity or weight.
2Power
If higher voltage batteries or DC/DC boost converters are added to increase DC link voltage, then the motor torque output is improved, but the packaging space and weight increase
Solution Approach 1:
Instead of permanently increasing system weight through higher voltage batteries or DC/DC converters, the patent dynamically changes the voltage parameter by selectively connecting different battery modules. The first set of high-voltage battery modules provides higher voltage when needed for increased motor torque, while the second set provides lower voltage for normal operation, avoiding unnecessary weight increase.
3Power
If the DC voltage at the DC link is increased to improve mechanical power output, then the motor torque output is improved, but the system weight increases due to additional components
Solution Approach 1:
The battery system is divided into multiple modules that can be selectively connected. The first set of high-voltage battery modules and second set of high-voltage battery modules allow the system to achieve higher mechanical power output when needed without permanently adding weight through DC/DC converters or higher voltage infrastructure.
Solution Approach 2:
The same battery modules serve multiple functions: the first set provides high voltage for high power demand conditions, while the second set provides lower voltage for normal operation. This multi-functionality eliminates the need for separate DC/DC boost converters, reducing overall system weight.
4Power
If a DC/DC boost converter is added to increase DC link voltage, then the mechanical power output is improved, but the ease of manufacture decreases due to increased system complexity
Solution Approach 1:
The patent avoids the manufacturing complexity of DC/DC boost converters by instead changing the voltage parameter through selective connection of pre-configured battery modules. This approach simplifies assembly and manufacturing while still achieving the goal of increased mechanical power output when needed.
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 approach enables increased motor torque output from the second torque machine at lower motor currents, improving mechanical power output while maintaining balanced energy transfer between the first and second torque machines, thus enhancing the system's efficiency and performance without increasing packaging space or weight.
Implementation Method 1
an electric machine that transforms electric power to mechanical torque
Data Source
AI summary
A hybrid powertrain system has a high-voltage electric circuit including a high-voltage battery and a DC link coupled to first and second inverters electrically connected to first and second torque machines. A method for operating the hybrid powertrain system includes receiving a motor torque command for the second torque machine, determining a preferred DC link voltage for achieving the motor torque commanded from the second torque machine, selectively interrupting electric power flow between the high-voltage battery and the DC link to achieve the preferred DC link voltage.