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

1. Choose cell chemistry and cell specifications → determine nominal cell voltage and capacity.
2. Calculate series count (S) for target pack voltage: S = V_pack / V_cell_nominal.
3. Choose parallel count (P) for desired pack Ah: Ah_pack = Ah_cell × P.
4. Compute total cells: total = S × P; compute pack energy: Wh = V_pack × Ah_pack.
5. Plan mechanical layout: select holders, determine cell orientation, choose nickel strips (H-tabs for compact S+P connections), and plan spot-welding points.
6. During assembly: verify cell orientation and electrical continuity for each series and parallel group before final welding; practice with dead cells if possible.
7. 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).