Summary of "Embedded Systems and Design & Development - Feb 6, 2026 | Afternoon | VisionAstraa EV Academy"
Embedded Systems and Design & Development — VisionAstraa EV Academy
Feb 6, 2026 (Afternoon)
Core topics covered
Battery cells: form-factors and chemistry
- Comparison of common cylindrical formats: 18650 vs larger LFP cylindrical cells (examples referenced: 18×65 vs ~32×70 dimensions).
- LFP cells are physically larger than typical NMC cells for similar capacity.
- Example cell used in demos: LFP cylindrical ≈32×70, 3.2 V nominal, 6,000 mAh.
Nickel strips & spot welding
- Two common nickel tab types:
- Straight (single) strips — used when series and parallel connections are made separately.
- H-type (H-nickel) — allows simultaneous series + parallel connections for a more compact layout.
- Strip width varies with cell size (≈18 mm for 18650; larger widths for 32×70 class cells).
- Spot-weld practice performed on dead cells for safety.
Pack design fundamentals (practical tutorial)
- Example design: build a 48 V LFP pack using 3.2 V nominal cells.
- Series count: S = 48 / 3.2 → 15s.
- With 6,000 mAh cells and selecting 4P → pack Ah = 6 Ah × 4 = 24 Ah.
- Total cells = S × P = 15 × 4 = 60 cells.
- Pack energy: Wh = V × Ah = 48 V × 24 Ah = 1,152 Wh = 1.152 kWh.
- Demonstrated physical assembly using cell holders and dead cells.
- Important assembly points:
- Cell orientation and terminal sequencing (positive/negative alternation).
- Common errors: wrong cell direction, incomplete parallel connections.
- Layout strategies to reduce pack length: stacking/folding series groups and insulating/placing parallel groups over others to make a more compact footprint.
- Options to implement series and parallel connections: H-tabs (simultaneous S+P) vs straight strips (separate S and P).
Practical constraints & design tradeoffs
- Vehicle packaging constraints affect pack geometry (example: bicycle frame limits width so length may be used instead).
- Use of cell holders and planning cell count to match holder capacity.
- Tradeoffs between compactness, manufacturability, and safety.
Controller, motor and throttle basics
- Motor controller (MCU) architecture overview:
- MOSFET switching topology; speaker noted 12 MOSFETs as part of a controller driving a 3‑phase BLDC.
- BLDC motor fundamentals:
- Three windings; controller modulates current to control speed.
- Throttle operation:
- Typical 3-wire throttle: red = +, black = GND, green = signal.
- Throttle is usually a potentiometer: idle position = high resistance (low current), twisting reduces resistance and increases current and motor speed.
- Relationship explained: resistance ↔ current ↔ speed.
System architecture, safety & telemetry
- Key EV subsystems: Battery (and BMS), MCU (controller), BLDC hub motor, throttle, wiring harness.
- Vehicle Control Unit (VCU) role:
- Supervisory unit aggregating data from subsystems (temperature, currents, faults).
- Coordinates safety and interfaces to IoT/cloud for alerts and telemetry (example: fall alert).
- IoT/cloud linkage: VCU → IoT → cloud → mobile app for remote monitoring and alerts.
Practical tutorial / step-by-step guide
- Choose cell chemistry and cell specifications → determine nominal cell voltage and capacity.
- Calculate series count (S) for target pack voltage: S = V_pack / V_cell_nominal.
- Choose parallel count (P) for desired pack Ah: Ah_pack = Ah_cell × P.
- Compute total cells: total = S × P; compute pack energy: Wh = V_pack × Ah_pack.
- Plan mechanical layout: select holders, determine cell orientation, choose nickel strips (H-tabs for compact S+P connections), and plan spot-welding points.
- During assembly: verify cell orientation and electrical continuity for each series and parallel group before final welding; practice with dead cells if possible.
- Design pack geometry according to vehicle packaging constraints; use insulation and stacked group layouts to minimize dimensions.
Common mistakes highlighted
- Incorrect cell orientation (reverse polarity) during placement.
- Poor planning of parallel connections, causing isolated sub-packs or incomplete connectivity.
- Using the wrong nickel strip type for the intended layout (e.g., straight strip where an H-tab would be needed for space-efficient S+P connections).
What’s next / follow-up
- Upcoming sessions will dive deeper into embedded design, VCU design, and VCU-to-IoT/cloud communication.
- Additional practical exercises and more detailed embedded programming/VCU topics are planned.
- PPT/notes for this session will be shared with attendees after they complete the feedback form.
Materials / components demonstrated
- LFP cylindrical cells (≈32×70 series, 3.2 V, 6,000 mAh)
- Cell holders (various capacities)
- Nickel strips (straight and H-type)
- Spot-weld practice on dead cells
- Example BLDC hub motor, MCU/controller, throttle, wiring harness
Main source: Instructor(s) from VisionAstraa EV Academy (session delivered by the academy’s EV training team).
Category
Technology
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