Electric Drive Module Layout With Liquid Cooling and Current Sensing
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Solution Overview
Problem
The electrification of vehicle drivelines faces challenges such as high cost, volume constraints, and the robustness of electronics in packaging and space within vehicles, which hinder their widespread adoption compared to internal combustion engine-powered vehicles.
Innovation Solution
An electric drive module is designed with a housing assembly, electric motor, and inverter, featuring a stator with field windings and phase leads, a rotor, and an inverter with power semiconductor devices and heat sinks, along with a liquid cooling system to enhance thermal management and packaging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional air cooling is used for the stator, then the structure is simple, but the thermal management efficiency is insufficient leading to overheating issues
Solution Approach 1:
The patent implements a liquid cooling system where a coolant flows through cooling channels formed in the stator core. The coolant absorbs heat from the stator windings and core, effectively removing excess heat. This hydraulic cooling approach replaces insufficient air cooling with a more efficient liquid-based thermal management system.
Solution Approach 2:
The patent changes the thermal management parameter from air cooling to liquid cooling by introducing cooling channels with specific flow paths. The coolant flow rate, temperature, and channel geometry are optimized parameters that enable effective heat removal while managing the increased system complexity.
2Volume of moving object
If the inverter components are arranged in a conventional layout, then the assembly is simple, but the packaging efficiency is low and volume is excessive
Solution Approach 1:
The patent merges the inverter components (power semiconductor devices, heat sinks, circuit board assembly) into a single integrated inverter housing. The retaining member combines multiple functions: mechanical support for power devices, mounting structure for heat sinks, electrical insulation, and fluid sealing. This consolidation reduces overall volume while managing the complexity of component integration.
Solution Approach 2:
The patent employs a nested arrangement where the circuit board assembly is positioned within the inverter housing, power semiconductor devices are mounted on heat sinks that are themselves mounted within the housing, and the entire inverter assembly is contained within the electric drive module housing. This nested structure maximizes packaging efficiency.
3Reliability
If robust electronics are used to withstand thermal and mechanical stresses, then reliability is improved, but cost increases
Solution Approach 1:
The patent introduces thermal management intermediaries (cooling channels, heat sinks, coolant flow paths) that protect the electronics from thermal stress. The inverter housing and retaining member act as mechanical and thermal barriers, shielding sensitive electronic components while using standard, cost-effective materials and manufacturing processes.
Solution Approach 2:
The patent implements beforehand cushioning by designing the inverter assembly with pre-integrated thermal management features and mechanical protection structures. The cooling channels are formed in the stator before winding installation, and the inverter housing is designed with built-in thermal and mechanical protection, reducing the need for additional protective measures and lowering overall cost.
4Temperature
If the stator cooling passages are formed through the stator core, then thermal management is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the stator core into sections with cooling channels formed between the laminations. The cooling passages are created by providing spaced apart laminations with cooling channels formed between them, rather than drilling through the entire stator core. This segmentation approach simplifies manufacturing while maintaining effective cooling.
Solution Approach 2:
The patent implements preliminary action by forming the cooling channels between laminations during the stator assembly process, before the windings are installed. The cooling channels are pre-formed in the laminated core structure, allowing coolant flow paths to be established before final assembly, reducing subsequent manufacturing 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
The solution improves the packaging efficiency and thermal management of electric drive modules, addressing cost and volume issues while enhancing the robustness of electronics, thus facilitating the adoption of electrified drivelines in vehicles.
Implementation Method 1
The power terminal of each of the power semiconductor devices is mounted to the one or more heat sinks. Each of the one or more heat sinks has a plurality of fins. The fins of the heat sinks are disposed in an annular region that is adjacent to the axial ends of the sets of field windings.
Implementation Method 2
An inlet port is formed through the end plate. The inlet port is adapted to receive a liquid cooling fluid therethrough. The inlet port is coupled in fluid communication to the annular region.
Data Source
AI summary
An electric drive unit having a stator body, a plurality of sets of field windings mounted to the stator body, a rotor received in the stator body and rotatable relative to the stator body, a plurality of phase terminals, and a current sensor assembly. Each of the phase terminals is coupled to an associated one of the sets of field windings. The current sensor assembly has a plurality of current sensor laminations, and a sensor. The current sensor laminations are generally C-shaped and are abutted against one another to form a sensor lamination stack. The sensor lamination stack defines a gap. The current sensor laminations are disposed about a corresponding one of the phase terminals. The sensor is disposed in the gap.