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World-first Tiny 5-speed auto transmission for evs

Transmission ‘Should-be-used’ in EV
BYGEN NHC 6AT
NHC 6AT - Advantages
Competitiveness of NHC 6AT
NHC 6AT – Design & Connecting
Product Story
Competitiveness of NHC 6AT
No Hydraulic & Clutch 6Gears Auto Transmission
Transmission effects
Efficiency(km/kWh) increases by over 50%
compared to the same output performances (Refer to Test Data)
Battery usage: “60kWh
40kWh

▶ Significant cost-cut
   • Over 50% efficiency improvement
1/3 smaller battery
       (from 60kWh to 40kWh)
   • No overheat
No need of cooling systems
   • No high frequency noise
No cost for preventing noise
   • 50% Cost reduction of core powertrain (PCU + Motor + Transmission)
Feasibility of mass production
• Ultra-compact design: No hydraulics (complicated structure to have many control parts), No clutches (torque converters), No revolutionizing planetary gears
and ring gears, No multistage clutches, brakes, and valve body.
• NHC 6AT has one rotating gearbox (to consist of six gears and a shaft), and three driven gearboxes (to consist of six gears and a shaft each). Servo motor
of 2 Watt power controls gear shifting mechanism.
• Ultra-compact design grants simple production process. No huddles for mass production.
Feasibility of mounting on vehicle
• Due to ultra-compact design, it could be mounted without changing of existing EV platform.
• In-wheel type mounting method is applied to trailing arm with connecting parts, using small diameter.
• Axle type mounting method is directly applied to differential gear on the axle.
※ It could be used in ICEs even now.
Production Cost
NHC 6AT Transmission Cost
Owing to compact design without hydraulics (or substitutes) and clutches (torque converter), total production costs will be less than 30% of conventional 6-speed auto transmission.

Core Powertrain (PCU + Motor + Transmission) Cost
   • PCU cost with simple control algorithm is about 30% of sophisticated inverter to use field weakening control.
No fluid cooling systems
   • Motor cost should be lower because of smaller output, no rotating in field weakening region, and no fluid cooing systems.
   • Total core powertrain cost (PCU + Motor + Transmission) should be lower than existing system (PCU + Motor + Reducer).

EV Cost
   • Total powertrain cost including NHC 6AT is lower than that of single speed EVs.
   • Reduced battery capacity, no expenses for fluid cooling systems, reduced powertrain cost, no expenses for high frequency noise protection
   
Realize total production cost of EVs is equal to or less than that of ICEs.
AS-IS vs. TO-BE
Based on EV4W (as for EV2W, Refer to Test Data)
Items Single Speed EV
(AS-IS)
NHC 6AT EV
(TO-BE)
Remarks
Energy Efficiency - Improved by about 50%
Battery Capacity 60kWh 40kWh
Driving System RPM control by inverter Motor runs within the wide range of RPM Torque and RPM control by transmission Motor always runs within the rated range
Cooling System Cooling system indispensable for high temperature of motor and inverter No need of cooling system Motor does not produce high temperature, if it runs in the rated range
Motor IPMSM Motor
AC
IPMDC(BLDC) Motor
IPMSM Motor
Combined size with motor and inverter is smaller than motor including reducer
Control System Expensive inverter to use FOC PCU(Powertrain Control Unit)
MCU(Motor Control Unit) +
TCU(Transmission Control Unit)
Size and price of the PCU are 50% of Those of the inverter
Transmission Size Reducer (Single speed) Size for sub-compact car is under Ø200mm
Total weight is less than 10kg.
Warranty No torque interruption to decide warrant period. Auto transmission with small parts (see video in the website)
Curb Weight Smaller battery, No cooling system, etc.
Torque/RPM Range Narrow & Limited Wide by gear ratios Bygen transmission provides a seamless shift and wide range of torque and RPM
Powertrain Costs Expensive inverter & High power motor Overall powertrain cost including transmission is cheaper than that of single speed EVs • PCU cost is one-third of inverter
• Smaller motor w/o cooling systems
• T/M material cost: around $100~200
Vehicle Price • Large battery
Cost burden
• Cooling system in inverter and motor
• High frequency noise
• Expensive powertrain
• 1/3 battery enough for the same range
• No need of cooling system
• No cost for preventing high frequency noise
• Reduction of core powertrain expenses
Lowering price for using 6-speed auto transmission enables EV to compete with ICE