Bygen Ltd. is a highly innovative startup company that is currently developing and commercializing a new disruptive transmission technology for the electric vehicles.
Bygen has developed a fully electric powertrain that is capable of increasing the driving range of electric vehicles in combined city traffic and highway driving by more than 50% in any road-speed conditions. By using new concept of mechanical technology it is possible to build a highly efficient fully electric multispeed transmission system for electric vehicles. Bygen's transmission system has no hydraulics to control clutch, which enables transmission to be light and tiny. This also makes it possible to be "in-wheel" type, which lifts efficiency higher. Much lowering cost is expected to contribute electric vehicle industry to expand faster and higher than ever.
1. 2018. 12
Significant improvement in efficiency (km/kWh) from 50% to 100% → Easily attainable by auto makers
Performance is verified by Eco Automotive Research Institute of
Seoul National University of Science & Technology
4-Speed Auto TransmissionMotor TM In-Wheel
Technical Information
World’s 1st Commercialized Auto Transmission w/o hydraulics (“Original Technology”)
→ Smaller & Lighter Transmission → “In-Wheel”
(5-speed under development)
2. Table of Contents
Bygen’s Original Technology2
Performance Test Results (SNUSC)3
RPM vs. Efficiency4
The Faster, the More Efficient5
TransmissionMotorTM1
Test Road Map in SeoulAppendix I
R&D for Future8
Main Drivers for Increase in Efficiency6
7 EV Cost Reduction for Automakers
3. Registered Patents
Applicable Industry/Fields
TransmissionMotorTM1
• All electrified vehicles such as battery electric automotives, electric motorcycles, and drones
• Windmills (Windmill gearboxes that are easily affected by severe weather conditions such as typhoon or hurricane and wind turbines that
cannot perform with weak wind power.)
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• 9 local patents registered in Korea
• 2 PCT patents registered (including a separate registration in Chinese Taipei)
Gear Types
Performance Test & Results
• Official test was performed by Eco Automotive Research Institute of Seoul National University of Science & Technology
• Performance test results : Increase in efficiency (km/kWh) from 50% to 100% (subject to speed and road conditions).
• 4-speed Auto Transmission In-Wheel → 300% Gear Ratio
• 5-speed Auto Transmission In-Wheel currently under development → 352% Gear Ratio → Difference in gear ratio by level of speed is less
than 40%
4. - 2 -
1
Out-runner Type
2-wheel
In-runner Type
4-wheel
TransmissionMotorTM
Multi-speed Auto TransmissionMotorTM In-Wheel
Various Output Designs
5. 1
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Motor Gear BoxReducer, Shock Absorber Gear Controller
Synchronizer with three pawls by
each gear
In-Wheel 5-speed Auto TrnasnsmissionMotor (Out-runner type)
TransmissionMotorTM
7. - 5 -
1 TransmissionMotorTM
In-Wheel TransmissionMotor applied to
2-wheel EV
8. Innovative Gear Shifting
IntegratedMotorandTransmission
Built-inShockAbsorber
Bygen’s Original Technology2
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• Implemented the parallel one-axle design which contains the motor, transmission, reduction gear, and shock absorber in a single row. →
Integrated and less complex
Thesynchronizer(consistingofthreepawlsineachgear)builtintothemotoraxle
swivelsatthesametimeasthetransmissionmountedonthesameshaft.The
originaltechnology,whichchangesthegearwhileallgearsandthe input/output
axlesimultaneouslyrotate,eliminatesthesynchronizationforce.
Assoonasthegearandthethreepawlsengage,theshockabsorber
completelyeliminatesthesynchronizationforcebyusingtheelasticityofthe
shockabsorberwhichisoneof Bygen’soriginaltechnology
※ BecausetheinitialtorqueofamotorisstrongerthanICE’s,the
synchronizationforceofamotorisgreaterthanICE’s.
※ Ittakesonly0.25secondfora gearchange.
1st Shock Absorber 2nd Shock Absorber
Fast and Smooth Automatic Gear Shifting
• Gear shifting is performed along with the rapidly rotating synchronizer which is built in the input shaft. There is no separate planet gear.
Non-hydraulics Transmission
◎ The world’s first automatic transmission without hydraulics → Bygen’s original technology uses the suvor motor which selects the gear
through the rotating pawls.
• 90% smaller and lighter than conventional automatic hydraulic transmissions (5kg) → The base of In-Wheel
9. 1. TestSummary
Incline Test
PG
Test Objective Performance test of newly developed EV transmission (applied to electric motorcycle)
Developer Bygen Ltd.
Test Organization Seoul National University of Science & Technology (Eco Automotive Technology Institute)
Test Performer Professor In-Yong Ohm (Department of Mechanical & Automotive Engineering)
Tested Vehicle Bygen’s prototype electric motorcycle
Benchmarked Vehicle Model “G” of a local electric motorcycle company (best seller in 2017)
Venue PG at KIAPI (Korea Intelligent Automotive Parts Promotion Institute)
Date 17~19 September, 2018
Performance Test Results3
KIAPI HQ
12% Incline20% Incline30% Incline
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11. 3. TestResults
☆ The main reason for the decrease in efficiency of the two-wheel motorcycle at a higher speed is due to air resistance, which is proportional to the square of velocity, rather
than rolling resistance, which is heavily related to mass of total vehicle. (* Please refer to the graphs on slide 8 “RPM vs Efficiency” for details.)
Performance Test Results
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◎ Max Speed Test
Venue Measurement Bygen “G”
PG Speed at 400m after the starting point with full acceleration 63km/h 62km/h
◎ Constant Speed Test
Venue Constant Speed
Bygen “G” Efficiency
Improving
Ratio
(%)
Range
(km)
Remaining Voltage(V) Efficiency
(km/kWh)
Range
(km)
Remaining Voltage (V) Efficiency
(km/kWh)Total Per Cell Total Per Cell
PG
30km/h 202.1 42.5 3.27 84.2 101 62.5 3.13 41.3 over 103.9%
40km/h 140 42.2 3.25 58.3 84.1 60.5 3.03 34.4 over 69.5%
50km/h 90.6 43.5 3.35 37.7 61.6 60.85 3.04 25.1 over 50.2%
◎ Road Test in Urban Area
Test Area Item Bygen “G” Efficiency Improving Ratio (%)
Dong-Il Ro, Nowon-Gu, Seoul
※ Map seen in Appendix 1
Driving Range 102km 53.5km -
Remaining Voltage per Cell 43.85V, 3.373V 62.4V, 3.12V -
Efficiency (km/kWh) 42.5 21.8 over 95%
※ For more details on the test information, please refer to test report of SNUFT, which should be sent by request.
Bygen “G”
Consistentperformancewithgradientof20.9% Consistentperformancewithgradientof14.1%
◎ Grade Performance Test
☆ Please note that Bygen’s battery was used within normal range whereas the battery of “G” was discharged during the test which indicates that the actual efficiency improvement will be greater.
3
12. - 10 -
3
Picture of the prototype: TransmissionMotorTM in both front and rear wheel
Performance Test Results
13. RPM vs. Efficiency4
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Rated RPM
20%
40%
60%
80%
100%
20% 40% 60% 80% 100
%
0%
RPM/max rpm
Efficiency
Torque
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
5th Gear
4th Gear
3rd Gear
2nd Gear
1st Gear
[ Fig. 1 Efficiency Graph of PMDC Motor ] [ Fig. 2 Torque-RPM Graph with Gears]
Gear 1st 2nd
3rd 4th 5th
Gear Ratio 1.250:1 1.759:1 2.478:1 3.316:1 4.4:1
5-speed Auto Transmission
with total gear ratio of 352%
will be commercialized in early 2019
◎ Energy efficiency decreases significantly as the motor is not run within the range of rated RPM
▶ As shown in Fig.1, energy efficiency of motor proportionally decreases as RPM drops from rated RPM range.
▶ Especially, the efficiency drastically drops when the motor is run in excess of RPM range over rated RPM, which is not recommended due
to possible serious damage and over-heating of motor.
※ Multi-speed transmission of ICE automotive also keeps engine to operate within rated RPM range (around 2,000 RPM for a medium-
sized car), adjusted to speed and road condition, which enables to reduce fuel consumption and to drive smoothly.
※ As seen in Fig. 2, 5-speed TransmissionMotorTM , shifting ratio by gear of which is under 40%, will make motor run within
rated RPM at any load condition. This contributes to the most efficient and smooth driving to electric vehicles
( around 85% of
max RPM)
RPM/max rpm
Rated RPM
of ICE
14. 4
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◎ Why is the efficiency ratio higher at a lower speed than a higher speed at constant velocity?
◎ Why does the efficiency of 2-wheel motorcycle decrease more at higher speed during constant speed driving?
▶ The prototype of Bygen reduces its speed by lower gear and same rated RPM, which makes the vehicle run at the most efficient RPM.
→ Current consumption at low load/speed can be minimized when EV is driven at low gear with stronger torque. According to the test, we find that
consumption of starting current at each gear is inversely proportional to voltage. → Starting with low gear consumes low current, which ensures higher
efficiency.
▶ On the contrary, electric motorcycle of “G”, rated RPM of which is around velocity of 50km/h, reduces its speed by lowering RPM of PMDC motor.
→ Efficiency is proportional to range of rated RPM. The more speed gets off from rated RPM, the lower the efficiency. → Efficiency at low RPM Is very
low.
◎ Efficiency of electric vehicles with max speed over 100km/h would decrease proportionally to increasing RPM range. Fast automotive has to run more
frequently at an inefficient RPM range out of rated RPM range to adopt wider RPM range. High speed vehicles must use multi-speed transmission to
extend driving range as well as to increase other performance. → proved by constant speed test at PG of KIAPI
▶ Driving efficiency heavily depends on the resistance forces. Total resistance in auto drive with constant speed consists of rolling resistance,
which is proportional to vehicle mass and air resistance, which is proportional to square of velocity. Acceleration (Inertial) resistance
and grade resistance does not depend on a level road and at constant speed. (TR=RR+AR, Frr α Mg, Far α V2 )
▶ Efficiency of 2-wheel vehicle decreases faster along with the increase velocity, because air resistance increases proportionally in spite of
relatively small rolling resistance of its lighter mass. → With higher air resistance coefficient of 0.2 compared to 0.3 of 4-wheel vehicle,
the increase in velocity of motorcycle sensitively drops efficiency. In a passenger car, the rolling resistance is double of air resistance until
velocity of 80km/h., which results in low decrease of efficiency.
▶ Initial strongest torque of motor enables electric vehicles to start with enough power without transmission. However, it requires large current to rotate
motor, whereas transmission lessens consumption of current due to strong torque supplies at start and drive.
RPM vs. Efficiency
15. The Faster, the More Efficient5
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When a vehicle runs faster, it uses a wider rpm range.
This means that the out-of-rated rpm range gets wider.
When a 5-speed auto in-wheel transmission with a gear ratio of under 40% is used,
EV with max speed over 100km/h will perform at a higher efficiency
Driving range of 4WEV is expected to increases by more than 100% .
16. Main Drivers for Increase in Efficiency6
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Motor always operates within the
rated RPM range,
without creating “HEAT”
No need for hydraulics &
Gear connecting parts
Downsizing the motor by half
i.e. less battery usage
Highly efficient In-Wheel type
Minimizing loss of energy delivery
to wheels
Efficiency
Increase
17. EV Cost Reduction for Auto Makers7
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No Need for Cooling System
(No heat creation in rated RPM)
Battery Usage
Reduced by 50%
For same Distance
Simpler, Cost Effective
Controlling System
(PMDC Motor, Simple Inverter)
Smaller Motor
Cost Cut
Over 50%
18. 5-Speed Auto Transmission
R&D for Future8
⚫ In-Wheel 5-speed auto transmission is targeted to be developed in the first quarter of 2019.
⚫ For more sophisticated control of gear change, difference of gear ratio will be under 40%. (Refer to Fig. 2 on page 8)
⚫ This will enable the vehicle to be driven within the rated RPM range at any load and road condition.
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3-Wheel Vehicle
⚫ In consideration of the increase in trend of fewer passengers, Bygen is developing 3-wheel compact vehicle for two passengers.
⚫ With total length between front and rear wheels of 1.2m and total weight of 300kg, the 3-wheel vehicle (one front wheel and two rear
wheels) will have TransmissionMotorTM separately which will give smooth cornering for low tilting point and in-wheel type.
⚫ Decrease in production cost will contribute to the rapid growth of EV market.
Applicable Fields/Industries
• TransmissionMotorTM can be applied and used in other products and industries such as drones and windmills.
19. 8
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3-wheel (1 for front, 2 for rear) tilting vehicle
• Design will be open in 2019.
R&D for Future
20. Appendix I: Test Map in Seoul
Test Location :
Around Dong-Il-Ro, Nowon-Gu, Seoul
Distance for one
loop : 9.5km
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Altitude (m)
Distance (km)
: one loop