Dual-Inverter Electric Drive With Split Battery Packs for Peak Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric drive systems face challenges in achieving high torque levels and reliable operation under varying load conditions due to increased inverter current requirements and battery pack failures from multiple cells in series, leading to oversizing and voltage loading issues.
Innovation Solution
A dual powertrain system with two energy storage means and inverters, each with a multiphase winding, allows independent operation and coordinated power flow between them, optimizing power distribution and reducing overload risks by activating additional powertrain components only under high loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the voltage of the battery is increased by having more battery packs or battery cells in series to reduce inverter current, then the inverter current is reduced, but the likelihood of battery packs failing increases and the inverter and electric machine become oversized
Solution Approach 1:
The battery system is segmented into multiple independent battery packs, each operating at a lower voltage level. This segmentation prevents the need for high-voltage series connections while maintaining the required power output through parallel configuration and inverter coordination.
Solution Approach 2:
Multiple battery packs are merged in parallel configuration to achieve the required power output without increasing individual pack voltage. The inverters coordinate to combine the power from multiple lower-voltage packs, avoiding the reliability issues of high-voltage series connections.
2Power
If the battery voltage is increased to reduce inverter current, then the inverter current is reduced, but the inverter and electric machine become oversized
Solution Approach 1:
The power conversion system is segmented into multiple independent inverter units, each handling a portion of the total power. This allows each inverter to be sized appropriately for its individual load rather than requiring one oversized inverter, reducing overall system complexity and cost.
Solution Approach 2:
The inverter system is designed with multi-functionality to handle both individual and combined power outputs from multiple battery packs. The inverters can operate independently or in coordination, providing flexibility in power delivery without requiring oversized components.
3Power
If multiple battery cells are arranged in series to increase voltage, then the voltage output is increased, but the weakest cell limits the power output of the entire pack
Solution Approach 1:
The battery system is divided into multiple independent packs, each operating at lower voltage. This segmentation eliminates the series connection bottleneck where the weakest cell limits overall pack performance, as each pack operates independently at its own optimal voltage level.
Solution Approach 2:
The system changes the voltage parameter configuration from high-voltage series connections to lower-voltage parallel connections. This parameter change allows the system to achieve required power output without being constrained by the weakest cell in a series string, as parallel connections allow independent operation of each pack.
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
Enhances power output and reliability by balancing the advantages of different battery technologies, reducing voltage drop, and optimizing power flow to handle peak loads without overloading individual components.
Implementation Method 1
Clocked inverters operate according to the principle of pulse width modulation (PWM) or pulse amplitude modulation (PAM). Pulse width modulation (PWM) is found more frequently in electric drives.
Implementation Method 2
The electric motor is powered by a traction battery, and voltage source inverters (VSI) typically are used to convert the voltage and drive the electric motor.
Data Source
AI summary
A method is provided for operating an electric drive system (20) with an electric machine (27) that comprises a first multiphase winding operatively coupled to a first inverter (25), and has at least one second multiphase winding that is coupled to a second inverter (26), A first energy storage (23) is arranged upstream of the first inverter (25), and a second energy storage (24) is arranged upstream of the second inverter (26). The method includes: operating the electric machine (27) by providing a first power flow between the first energy storage (23) and the first multiphase winding; and energizing the second inverter (26) so that a second power flow can be provided between the first energy storage (24) and the second multiphase winding. An electric drive system also is provided for carrying out the method.