VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITY HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY FACULTY OF MECHANICAL ENGINEERING CAPSTONE PROJECT DESIGN CONVERSION MID-DRIVE MOTOR KIT FOR MTB (MOUNTAIN BIKE) TO E-MTB (ELECTRIC MOUNTAIN BIKE) Student’s name: Nguyen Cong Hieu Student ID: 1952048 Instructor: MSc. Luong Thanh Nhat Ho Chi Minh City, 2024 HCM City University of Technology SOCIALIST REPUBLIC OF VIETNAM Faculty of Mechanical Engineering Independence – Freedom – Happiness No.: _____/ĐHBK – CK FINAL YEAR PROJECT PROPOSAL (This form must be appeared at the first page in the report of the final year project) Students’s name: Nguyen Cong Hieu Student’s ID: 1952048 Program: Mechatronics Engineering Class: CC20COD1 1. Topic: Design conversion mid-drive motor kit for MTB (Mountain Bike) to e-MTB (Electric Mountain Bike) (Thiết kế bộ kit chuyển đổi dạng motor truyền động giữa cho xe đạp địa hình truyền thống thành xe đạp điện địa hình có trợ lực) Input: - Working in Off-Road conditions. - The type is pedal assist e-MTB.
- The rated power requirement to support 10% gradients at speeds of 10-12 mph, the weight of the cyclist and the bike are 95kg, and the rated power for the cyclist is about 220 watts. Expected outcomes: - Research overview of problems related to e-MTB: + Reasons why the market needs e-MTB, especially e-MTB conversion kits. + Explore torque control technologies for e-Bikes. + Explore torque measurement technologies for e-Bikes + Propose and analyze feasible options and select the appropriate solutions for whole conversion kit for MTB to e-MTB.
- Mechanical design + Design the gearbox for the motor. + Design the crankset system. - Electrical system design + Hall effect sensor circuit design for the motor. + Temperature sensor circuit design for the motor and MOTFETs.
+ Modify the design of the controller circuit of VESC Open Source. - Experimental + Assemble mechanical and electrical system. + Experimental evaluation of current controller. + Experimental evaluation of pedal assist ability.
- Technical drawings 5, including: + 1 A0 drawing, about: Conceptual design + 1 A0 drawing, about: Mechanical design + 2 A0 drawing, about: Electric and electronic design + 1 A0 drawing, about: Control algorithm design 3. Supervisor: Affiliation: Responsibility: MSc.Luong Thanh Nhat Department of Mechatronics 100% The proposal has been screened by the Head/Deputy Head of the department May…., 2024 Head of Department Main supervisor Luong Thanh Nhat FOR OFFICIAL USE ONLY Faculty: Department Date of defense Evaluation grade: Archived place: ACKNOWLEDGEMENT Design conversion mid-drive motor kit for MTB (Mountain Bike) to e-MTB (Electric Mountain Bike) is the subject I selected for our graduation project after our studies at the Ho Chi Minh City University of Technology - Vietnam National University Ho Chi Minh City, VNU-HCM. Throughout the research and completion of this project, we received substantial support and guidance from our teachers, family, siblings, and friends. We would like to express our heartfelt gratitude to all who have accompanied us during this period.
First and foremost, we extend our deepest thanks to our parents and family members for their unwavering trust, encouragement, and support throughout our educational journey. I wish to convey my sincere appreciation to MSc. Luong Thanh Nhat, who imparted not only the essential knowledge but also the professional demeanour required of an engineer. His patience and enthusiasm in pointing out deficiencies in technical drawings and practical machining techniques significantly broadened our understanding and enriched our experience for our future endeavours.
I am also profoundly grateful to VIEROBOT Co. for their invaluable assistance in providing ideas, equipment, research space, and funding for our project. Special thanks go to the electrical, mechanical, and embedded programming engineers who supported us throughout the implementation process. Lastly, I extend our gratitude to the teachers of the HCMUT for their instruction and assistance, enabling us to complete the Mechatronics Bachelor Program.
I am also thankful to our dear friends for their companionship, support, and collaboration on various assignments and projects. I hope to have the opportunity to work together again in the future. ii TABLE OF CONTENT ACKNOWLEDGEMENT. ii TABLE OF CONTENT.
iii INDEX OF FIGURE. vi INDEX OF TABLE. ix CHAPTER 1: OVERVIEW. Growing demand for sustainable transportation source.
The best solution for developing sustainable personal transportation. Definition of e-Bikes and e-MTB. The development potential of e-MTB and the need for e-MTB conversion kits. Necessity of product research and development.
Research and implementation range.6 Criteria 1: Working in Off-Road condition & Require power.6 Criteria 2: Pedal assistance .6 Criteria 3: Lower limit for maximum speed at crankset. Structure of the thesis .7 CHAPTER 2: SELECTION METHODS. Position of actuator & working principal. Battery cover selection.
Control method selection. Crankset system selection. Torque sensor selection. Temperature sensor selection.
Rotor position sensor selection. Select ESC open source. Select BMS & Cell pins .24 CHAPTER 3: MECHANICAL DESIGN. Method to measure torque from both legs.
Method motor assist the system. Motor selection and transmission ratio. Calculate the power for the motor and motor selection. Transmission ratio distribution.
Technical specification of the transmission. Chain drive design. Transmission gears: sun gear and planetary gear. Transmission gears: planetary gear and ring gear.
Holder motor design .51 CHAPTER 4: ELECTRICAL – ELECTRONIC DESIGN. Controller hardware module. Hall effect sensors module. Position arrangement for hall effect sensors .60 CHAPTER 5: CONTROL – ALGORITHM DESIGN.
Current reference generator .63 CHAPTER 6: EXPERIMENTAL RESULTS AND EVALUATION. Mechanical processing and assembly. Electronic processing and assembly. Controller and driver.
Hall effect sensors. Switch from sensors to sensorless mode in FOC.86 CHAPTER 7: CONCLUSIONS AND OUTLOOKS. The achieved results .93 v INDEX OF FIGURE Figure 1.1: Compare the carbon footprints of the different vehicles .2: Growth Trends & Forecasts of e-MTB market size (2024 - 2029).3: Growth Trends & Forecasts of e-Bikes market size (2024 - 2029) .4: A prototype mid-drive conversion kit to e-Bikes in IndieGoGo.3: Mid-drive motor e-Bikes.4: Hub-drive motor e-Bikes .5: The way to measure torque of the right leg .6: Proposed principle diagram .7: The system working without assistance .8: The system working with assistance .9: Product drawing from the RYOBI manufacturer .10: How to measure the current of the phases in FOC .11: Error between measured current vector and desired current vector .12: Converting to the fixed coordinate .13: Converting to the synchronous rotation coordinate .14: States of converting 3-phase to controllable 2-phase in FOC .15: Controllers for id and iq .16: States of converting controlled 2-phase to 3-phase in FOC .17: Additional reluctance torque of Toyota/ Prius Hybrid THS II Motor [25] .18: Stationary frame state observer for a salient machine [26] .19: Product drawing from the manufacturer .1: Working principle & main blocks for mechanical design .2: How the system measures the torque of the left leg .3: How the system measures the torque of the right leg .4: How does the system separate the torque of the motor and the cyclist .5: How does the system assist the cyclist .6: Tab Design of Chain Design in Autodesk Inventor .7: Tab Calculation of Chain Design in Autodesk Inventor .8: Tab Selection Chain of Chain Design in Autodesk Inventor .9: Working principle of the planetary gearbox with fixing the ring gear .10: Tab Design of Gear Design (Sun + Planet gears) in Autodesk Inventor .11: Tab Calculation of Gear Design (Sun + Planet gears) in Autodesk Inventor .12: Tab Design of Gear Design (Ring + Planet gears) in Autodesk Inventor .13: Tab Calculation of Gear Design (Ring + Planet gears) in Autodesk Inventor .14: Arrange the distance on the shaft .15: Tab Design of Shaft Design in Autodesk Inventor .16: Analyzing the force acting on the shaft .17: Tab Calculation of Shaft Design in Autodesk Inventor .18: Shear Force Graph, YZ Plane .19: Shear Force Graph, XZ Plane .20: Bending Moment Graph, YZ Plane .21: Bending Moment Graph, XZ Plane .22: Ideal Diameter of Shaft .23: Tab Design of Key (Chain Sprocket) in Autodesk Inventor .24: Tab Calculation of Key (Chain Sprocket) in Autodesk Inventor .25: Tab Design of Key (Chain Clutch) in Autodesk Inventor.26: Tab Calculation of Key (Chain Clutch) in Autodesk Inventor .27: Tab Calculation of Bearing Selection in Autodesk Inventor .28: Put the force the chain system exerts on the shaft in Autodesk Fusion .29: Define the material for objects being analyzed .30: Displacement of the Motor after solving in Autodesk Fusion .31: Safety factor of the Motor after solving in Autodesk Fusion .1: Reference schematic design of Open source VESC .2: General schematic of the controller hardware .3: 3D images of the controller hardware .4: Hall effect sensors arrangement .5: Prototype schematic of the hall effect sensors module .6: Hall effect sensors module signal at the prototype version .7: Final schematic of the hall effect sensors module .8: Hall effect sensors module signal at the final version .9: Reference design for NTC sensors .10: Wiring diagram of temperature sensors inside of the ESC (left side) and motor (right side) .11: Schematic of the Bluetooth module .1: General block diagram of motor support .2: Block diagram of current control by the FOC .3: The current control system is divided into two blocks .4: Block diagram after prediction and reduction .5: Pole suppression plan in current control .6: Transfer function prediction results in VESC Tool .1: Some images about components of the gearbox are 3D printed .2: Some images after machining and assembly the gearbox .3: The prototype version of the crankset .4: Version 1 of the crankset with changing to block aluminium.5: Freewheel damage when going off-road for over 60km.6: The crankset version 2 has replaced the freewheel with the bearing.7: Several images after whole assembly .8: Several render image of mechanical system Version 2.9: Moisture damage, particularly those subjected to significant loads and high temperatures.10: A layer of nylon is applied to the torque sensor to enhance its durability and resistance to moisture .11: Component replacement process .12: The PCB circuit after processing .13: Mounting the PCB into the stator of the motor .14: Sensor signal when they are placed in the wrong face angle .15: Sensor signal when they are far the rotor .16: The usable signal of hall effect sensors .17: Some temperature sensor installation locations .18: Reading the temperature signal .19: Some images about installation the Bluetooth module .20: The experimental setup for recalibrating the cadence speed .22: Balance the battery cells before packaging the battery.23: Balance the battery cells after packaging the battery .24: Preparation for the current control experiment .25:Experiment result with the step inputs (8A to 19A, each step 1A) .26: Experiment result with the step input (0A to 10A, one step 10A) .27: Motor speed work no load at sensor mode .28: Motor speed work no load at sensorless mode .29: Motor speed work on the heavy load at sensorless mode .30: Motor speed work on the heavy load at sensor mode .31: The motor operates under heavy load in sensor mode when the ERPM is below 5000, and transitions to sensorless mode when the ERPM exceeds 5000.32: Setup motor before the pedal-assist experiment .33: Logging data at Tour Mode .1: Total distance traveled under assistive mode .90 viii INDEX OF TABLE Table 1.1: Constraints for Criteria 1 in summary .1: Comparison between Mid-drive and Hub-drive .2: Comparison between current control methods .3: Comparison between types of clutches in gearbox .4: Comparison between types of clutches in crankset .5: Comparison between types of torque sensors .6: Specification of T13 torque sensor .7: Comparison between types of rotation position sensors .8: Comparison between two popular FOC open sources .1: Specification of the motor .2: Select transmission ratio for planetary gear box .3: Transmission ratio distribution .1: Specifications of the A3144EUA hall effect sensor .1: Compare upgrades in two gearbox versions .2: Compare upgrades in two crankset versions .3: Compare other upgrades in two versions .71 ix Chapter 1: Overview CHAPTER 1: OVERVIEW 1.