What Are the Key Technologies Driving the Development of Electric Transaxles
As electric vehicles (EVs) continue to reshape the automotive industry, the electric transaxle has emerged as a cornerstone component that defines performance, efficiency, and design flexibility. More than just a replacement for traditional drivetrains, it integrates critical functions into a cohesive unit— and its evolution is fueled by breakthrough technologies that push the boundaries of what’s possible. Below, we explore the core technologies driving the advancement of electric transaxles, backed by real-world innovations from industry leaders.
1. X-in-1 Integration: The Pursuit of Compact, Lightweight Efficiency
The most transformative trend in electric transaxle development is component integration, embodied by the “X-in-1″ design philosophy. This approach consolidates previously discrete systems into a single unit, eliminating redundant parts, reducing size and weight, and unlocking significant efficiency gains.
Traditionally, electric transaxles relied on “3-in-1″ configurations that combined a motor, gearbox, and inverter. Today, industry pioneers are pushing far beyond this benchmark. Renesas and Nidec’s collaboration on the world’s first “8-in-1” proof of concept (PoC) represents the cutting edge of this trend. Their system integrates eight critical functions—including a 70~100 kW inverter (with over 99% efficiency), 1.5kW DC/DC converter, 6.6kW on-board charger, power distribution unit, and battery management system—all controlled by a single microcontroller (MCU) and power management IC (PMIC). Historically, each function required its own MCU and PMIC, making this integration a game-changer for simplifying EV design.
Aisin, another leader in the space, frames this as a generational evolution. Its first-generation “3-in-1″ transaxles power vehicles like the Toyota bZ4X, while the upcoming third generation aims to reduce size by 50% compared to the original. The benefits of such integration are multifaceted: reduced vehicle weight extends range, fewer components lower manufacturing costs, and compact designs free up space for larger cabins or batteries. For commercial vehicles, this translates to tangible value—Han De’s integrated 11.5-ton electric transaxle, for example, cuts chassis weight by over 600kg versus direct-drive systems.
2. High-Efficiency Motor & Gearbox Engineering: Maximizing Power Density
At the heart of every electric transaxle lies the motor-gearbox combination, where advancements in materials and design are delivering unprecedented power density and efficiency.
Motor Technology: Precision Winding & Thermal Optimization
Motor design innovations focus on two key goals: boosting power output and minimizing energy loss. Schaeffler leads here with diverse motor architectures, including radial flux, axial flux, wave winding, and hairpin winding designs. Hairpin winding—used in Chevrolet Volt’s Voltec 4ET50 transaxle—improves low-to-medium speed performance and thermal management compared to conventional stranded windings. Meanwhile, Schaeffler’s 23000rpm carbon fiber (CF) rotor and slot cooling technology for 800V platforms push motor efficiency to new heights, ensuring consistent performance even under extreme loads.
Silicon carbide (SiC) semiconductors are another critical enabler. Dana’s Spicer Electrified e-transmissions integrate SiC technology in their inverters, delivering peak performance while eliminating high-voltage phase cables for simpler installation. Vitesco’s VT EPF4 SiC 800V platform, used in Schaeffler’s latest transaxles, further enhances inverter efficiency, a key factor in achieving system-wide performance gains.
Gearbox Innovation: Compact, Quiet, and High-Torque
Gearboxes in modern electric transaxles prioritize efficiency, NVH (noise, vibration, harshness) reduction, and torque handling. Schaeffler’s stepped planetary design, featured in its coaxial transaxles, is a standout example—it enables gear ratios of 8.0~10.33, maximum input torque of 450 Nm, and efficiency exceeding 98.5% . The company’s upcoming TWIN coaxial gearbox, set to launch in late 2025, pushes efficiency even higher to 98.8% while weighing just 13kg (excluding oil) .
For commercial vehicles, multi-speed gearboxes are becoming essential. Han De’s 11.5-ton two-speed electric transaxle improves transmission efficiency by over 5% versus direct-drive systems, while its two-speed torque-boost variant delivers a staggering 35,000 Nm of output torque. Dana’s three-speed e-transmissions use Ravigneaux gearing to balance startability, gradeability, and road speed, making them versatile for medium-duty applications .
3. Intelligent Control Systems: From Torque Vectoring to Predictive Maintenance
As electric transaxles grow more complex, advanced control technologies are becoming indispensable for optimizing performance, safety, and reliability.
Torque Vectoring: Enhancing Handling and Stability
Torque vectoring—the ability to distribute torque independently to each wheel—transforms vehicle dynamics. Schaeffler’s dual-drive coaxial transaxle, used in the Audi e-tron Sportback, delivers 7,300 Nm of peak torque and uses torque vectoring to reduce yaw rate during high-speed lane changes, lower steering effort in corners, and improve traction on slippery surfaces. This technology doesn’t just boost performance; it enhances safety by adapting to real-time driving conditions.
Integrated Control Units: The Brain of the Transaxle
The shift to X-in-1 integration has elevated the role of control units. Renesas’ 32-bit RH850/U2B MCU serves as the “brain” of its 8-in-1 system, coordinating all eight functions seamlessly. Dana’s OpenECU platform goes further, offering next-generation control software with functional safety up to ASIL C and compliance with cybersecurity standards like ISO/SAE 21434. These systems ensure not just performance, but also the reliability and security required for modern EVs.
Predictive Maintenance: Minimizing Downtime
For commercial and industrial applications, predictive maintenance is a game-changer. ZF’s TerraCom condition monitoring system uses existing transaxle sensors to track component health, predict failures, and streamline warranty processing. This technology reduces vehicle downtime—a critical advantage for fleet operators—and provides valuable data for future transaxle development. Han De’s transaxles complement this with long maintenance intervals: 120,000~300,000 km oil change cycles and lifetime wheel-end maintenance-free, saving operators over $2,300 annually.
4. Voltage Platform Advancement: Moving to 800V for Faster Charging and More Power
The shift from 400V to 800V electrical architectures is a key enabler for high-performance electric transaxles. 800V systems reduce current levels for the same power output, minimizing energy loss in cables and components while enabling faster charging.
Schaeffler is at the forefront of this transition, with extensive experience in 800V 3-in-1 oil-lubricated transaxles. Its 800V coaxial transaxles support motors with 23,000rpm rotors and integrate SiC inverters, delivering both power and efficiency. For consumers, this means EVs that charge faster and drive farther; for commercial users, it translates to higher productivity and reduced downtime.
The Road Ahead: What’s Next for Electric Transaxle Technology?
The technologies driving electric transaxles today—integration, high-efficiency components, intelligent controls, and 800V platforms—are converging to create systems that are smaller, lighter, more powerful, and more reliable than ever before. Looking forward, we can expect even greater integration (perhaps “10-in-1″ or more), further advances in SiC and even gallium nitride (GaN) semiconductors, and deeper integration with vehicle-wide AI systems for predictive performance optimization.
Post time: Sep-24-2025