BYGEN

C7GAT – Advantages

Compact 7 Gears Auto Transmission

Pre-conditions of auto transmission

• There should be no shift interruption for comfortable riding and product durability.
• Fast gear shifting within 0.2 second
• Sophisticated TCU (Transmission Control Unit)

Qualified pre-conditions

• Seamless gear shifting without sifting time, TCU completed
※ ‘Zero-Time Gear Shifting’ in Bygen’s transmission overcoming the barrier of 0.2 second of shift time is the hidden technology and
cannot be duplicated without combined understanding of the design for mechanical hardware technology and software solutions in TCU.

Conventional auto transmission problems solved

• Eliminate the cause of battery consumption on transmission: No hydraulics (or alternates), which consume over 10% energy
out of the vehicle energy due to the increasing mass.

• Problems of vehicle weight gain and mounting space: Light weight and small dimensions enable it to be mounted without changing EV
platform. In-wheel type can be mounted on trailing arm, while axle type is done with the differential gear box

innovative shifting mechanism

• Gears are shifted by synchronizers, which are composed with more than two pawls at each speed and located in the main shaft.
Creatively, it is done while all gears are rotating with the same speed of the main axle, which using cam principles and the inertial power.

• Innovative shifting mechanism not using extra outer power for gear shift and maintaining

"Zero Shift Time" and no power
interruption

Innovative change of EV power control system

▶ Inefficient motor power control system in currently commercialized EVs
• Unlikely industrial electric motor, current EV motor control system should be accompanied by overheats and high frequency noise

Electric energy waste, Fluid cooling system, Complicated control algorithm

High EV manufacturing costs
• Impossible continuous driving at steep hill over 30% decline, which causes steep efficiency decline at continuous uphill drive

▶ Efficient motor power control system
• Motor always runs at the rated RPM range

No overheats & high frequency noise

Performances and efficiency improvement

Significant EV cost-cut
• Possible continuous driving at steep hill over 30%, while it does not cause any overheats and high frequency noise at high speed drive

NH6AT : Driving Efficiency

Total output vs. performances in single speed EV
▶ Comparing to ICE with the same output, EV should have outstanding performances in all areas with superior torque-rpm       characteristics to engine’s. However, performances (top speed, gradeability, passing acceleration) of single speed EV with       double output than ICE are inferior to ICE’s, except initial accelerations.
▶ Weak points of single speed EV using field weakening control (FWC): overheat at higher speed range (half of electric
      energy in battery is not converted into kinetic energy, wasted as a heat.) Overheat results in performance damage in
      electric motor.
▶ Overheat at maximum output has negative effects on motor and inverter, which should be temporally used (10~20
      seconds)

Driving system of NH6AT
▶ It always use rated torque (rated current) and rated rpm (rated voltage) at any speed, which is 1/3 to single speed EV
      using FWC.
      Max permitted current is 1.5 times of rated current, which is temporally used without overheat of motor and inverter.
▶ NH6AT with smaller motor than single speed provides wider range of torque and rpm without using FWC.
▶ With narrowing gear change ratio of compact 6-speed gearbox, it makes motor rotate at the most efficient rated range at       any speed.
▶ Initial battery energy is saved by starting and accelerating from lower gear to higher gear.

Current(A) is proportionally consumed to loads.
▶ Max current is permitted to 1.5 times of rated current at power mode “ON”. ⇒ Rarely used
    • Automatically “OFF” if permitted time (about 5 minute) is passed, and/or temperature of motor is saturated.
    • Continuous driving vehicle over rated output without water cooling system makes temperature of motor be over
      saturated, which radically drop motor efficiency as shown in above graph and motor get seriously damaged.

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