Industry Transformation: Against the backdrop of continuous upgrades in the new energy vehicle industry, motor technology, as the core driving unit, is undergoing a dual revolution from structural optimization to cooling system innovation. Flat wire motors enhance power density through material and process breakthroughs, while oil cooling technology improves heat dissipation efficiency through thermal management innovation. Together, they are creating new pathways for motor efficiency improvement.
1. Flat Wire Motors: Structural Innovation Driving Efficiency Leap
Flat wire motors use rectangular cross-section copper wires to replace traditional round wires, achieving dual breakthroughs in power density and heat dissipation capability through high slot fill rate design. Their core technical advantages are reflected in three aspects:
High Slot Fill Rate Design Breakthrough
- Flat wire motor slot fill rate can reach over 75%, nearly 50% higher than round wire motors
- Actual measurement data from Fangzheng Motor shows that its flat wire motor stator slot copper wire fill volume increases by 20%-30%, directly driving output power improvement year-on-year
- By 2025, industry benchmark product slot fill rate has exceeded 80%, with power density reaching 6.2kW/kg
Heat Dissipation Performance Optimization
- Contact area between rectangular copper wires increases by 30%
- Combining C-type insulation paper with laser welding process, stator winding thermal resistance decreases by 40%
- Actual measurement data shows flat wire motor temperature rise decreases by 12°C compared to round wire motors, with average efficiency exceeding 96.5% under NEDC conditions
Comprehensive Lightweight and NVH Improvement
- By reducing end size by 20%, flat wire motor weight decreases by 11%, volume reduces by 30%
- Magnetic circuit structure optimization reduces electromagnetic noise by 5 decibels
- Combined with dual-V structure magnet rotor, torque output capability increases by 18%
During the technology iteration process, by increasing flat wire aspect ratio, reducing conductor size, and adopting multi-gear transmissions, issues of increased AC impedance due to skin effect and proximity effect have been gradually resolved. SAIC's E2 architecture has achieved modular production of three different power motors (150kW/180kW/250kW), validating the feasibility of large-scale application of this technology.
2. Oil Cooling Technology: Thermal Management Innovation Breaking Through Heat Dissipation Bottlenecks
Oil cooling technology utilizes oil's high insulation properties (non-conductive, non-magnetic) and high thermal conductivity to build direct contact cooling systems. Its technological breakthroughs are mainly reflected in three aspects:
Dual-Mode Oil Immersion/Spray Cooling System
- Oil immersion cooling achieves comprehensive heat exchange for stator and rotor
- Spray cooling through direct rotor oil cooling technology, heat dissipation efficiency increases by 35% compared to water cooling
- Xiaomi Auto's bidirectional full oil cooling technology adopts S-shaped oil path design, forming a spiral three-dimensional cooling surface, motor maximum temperature can decrease by 35°C, overall heat dissipation efficiency increases by 55%
Rotor Synchronous Cooling System
- Addressing high-speed motor (>25,000 RPM) rotor heat dissipation challenges, oil is introduced into the rotor through hollow shaft design, synchronously cooling magnets and bearings
- After Leapmotor's Pangu E-Drive system adopted this solution, bearing life increased by 18%, stator temperature difference decreased by 55%
Integrated Thermal Management System
- In three-in-one e-drive systems, oil cooling can simultaneously serve motor, electronic control, and reducer
- Huawei's DriveONE system, through oil cooling technology, achieves 10 consecutive launch starts without performance degradation, demonstrating strong continuous power output capability
Behind the technological breakthroughs, oil selection and sealing design have become key challenges. Requirements include low viscosity (freezing point -45°C), high thermal conductivity (boiling point >180°C), high temperature resistance (copper corrosion resistance), etc. Meanwhile, by establishing rotor temperature rise estimation models and optimizing sensor data, dynamic matching of cooling systems is achieved.
3. Synergistic Effects: Flat Wire + Oil Cooling Builds New Efficiency Paradigm
The combination of the two produces significant synergistic effects: the high slot fill rate design of flat wire motors enhances cooling oil penetration efficiency, while the efficient heat dissipation capability of oil cooling technology ensures stable operation of flat wire motors at high power density.
Breakthrough Power Density
Under 800V architecture, flat wire oil-cooled motor power density increases by 45%-55% compared to traditional motors
Significant Range Extension
By reducing motor losses and improving heat dissipation efficiency, overall vehicle range can increase by 8%-12%
Deep System Integration
Oil cooling technology can replace independent lubrication systems for reducers, gears, and bearings
4. 2025 Technology Development Trends
Material Innovation Continues to Advance
- Nano-crystalline soft magnetic material application, iron loss reduction by 25%
- High thermal conductivity insulation material development, thermal management efficiency improvement by 30%
Intelligent Manufacturing Level Improvement
- Full-automatic flat wire forming equipment precision reaches ±0.1mm
- Digital oil path detection system achieves 100% online quality control
Deep System Integration Optimization
- Deep integration of motor and electronic control, system efficiency increases to 98.5%
- Intelligent thermal management system achieves on-demand cooling, energy consumption reduction by 20%
Conclusion
From the structural innovation of flat wire motors to the thermal management breakthroughs of oil cooling technology, motor technology is building new pathways for efficiency improvement through material innovation, process optimization, and system integration. Driven by 800V high-voltage platforms and intelligentization trends, flat wire oil-cooled motors will become the core solution for new energy vehicle power systems, injecting strong momentum into the industry's high-quality development.
Frequently Asked Questions
Flat wire motors offer significantly higher slot fill rates (75%+ vs 45-50% for round wires), which directly translates to higher power density and better heat dissipation. This allows for more compact motor designs with higher efficiency and power output.
Oil cooling offers 35% better heat dissipation efficiency than water cooling. Oil's high insulation properties allow for direct contact with electrical components, enabling more effective cooling of critical areas like rotor magnets and windings that water cannot safely reach.
The combination addresses the thermal management challenges of high-power-density motors. Flat wires increase power but generate more heat in a smaller space. Oil cooling effectively removes this heat, allowing flat wire motors to operate at their full potential without thermal limitations.
By 2025, flat wire motors are expected to reach 92% penetration in new energy vehicles, with oil cooling becoming standard in premium vehicles (over $30,000) and achieving over 60% penetration in mid-range vehicles. The technology is rapidly becoming the industry standard for high-performance EVs.
The efficiency improvements from flat wire oil-cooled motors can increase overall vehicle range by 8-12% under real-world driving conditions. This is achieved through reduced energy losses, better thermal management, and optimized power delivery across different operating conditions.
