Step 4 – Controller & VCU Installation

Install the motor inverter and Vehicle Control Unit (VCU). The VCU manages the whole system via CAN bus, interpreting throttle inputs and communicating with the BMS, inverter, charger and dashboard.

Procedure

1. Select controller location: firewall, tunnel, or under boot floor
2. Fabricate aluminium mounting bracket with vibration isolation
3. Mount controller with thermal interface material to heat sink
4. Connect HV DC input from battery pack (observe polarity)
5. Connect AC motor phase outputs (U, V, W) to motor
6. Wire motor resolver or encoder to controller signal inputs
7. Install VCU on firewall — use DIN rail mount
8. Connect throttle position sensor to VCU analogue input
9. Wire brake sensor input for regenerative braking control
10. Program CAN bus network: VCU ↔ BMS ↔ Inverter ↔ Charger
11. Configure inverter: motor type, pole pairs, max current, voltage limits
12. Set up regen braking levels via VCU software

Safety Warnings

1. Controller DC link capacitors retain charge — wait 5 min after HV disconnect
2. Do not swap U, V, W motor phases under load
3. Incorrect VCU programming can cause uncontrolled motor activation

Pro tip

Popular open-source VCU solutions include openinverter and GEVCU. The Tesla Model S/X drivetrain with open-source controllers offers proven 200kW+ performance at lower cost.