Systems / 03

Powertrain

Motor, inverter, cooling and energy flow treated as one efficiency and thermal problem.

Illustrative · simulated demo dataOUTPUT: efficiency map, % (illustrative)

Efficiency map

Efficiency map · illustrative data matrix

Show duty points

≈ 60 % → 97 % (illustrative) Outside envelope Duty point

Selected cell

96.5 %

Efficiency · illustrative

Speed: 4,500 rpm
Torque: 225 Nm
Shaft power: 106.0 kW
Torque limit here: 318 Nm

Envelope: 400 Nm constant torque up to 3,581 rpm, then constant 150 kW. All values are an invented smooth surface, not a real machine.

Duty points

Urban2500 rpm · 120 Nm → 92.8 %
Cruise6500 rpm · 75 Nm → 93.5 %
Hill climb4500 rpm · 275 Nm → 96.1 %

Approach

A powertrain is judged where it actually operates, not at its peak. We map efficiency over speed and torque, overlay the duty a programme demands, and follow the lost energy to where it becomes heat that something must remove.

Methodology

Describe the operating envelope as torque against speed: a constant-torque region, then a constant-power region.
Overlay representative duty points on the efficiency map to see which regions matter.
Carry the losses into a thermal model so that cooling and packaging are decided together with the electrical design.

Deliverables

Efficiency map with duty overlay
Loss breakdown by component
Thermal envelope with cooling requirement

Scope and constraints

Efficiency maps are measured on a dynamometer at a controlled temperature; hot and cold behaviour differ.
Losses vary with switching strategy and DC-link voltage.
Peak efficiency is rarely where the vehicle spends its time.

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