Sizing Calculator
From vehicle data and your design choices to motor torque, speed and main dimensions, with every target checked.
Checks
DESIGN CARD · SIZING
- Peak power
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- Peak torque
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- Cont. power
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- Cont. torque
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- Base speed
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- Max speed
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- Ratio
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- Rotor Ø × L
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- Stator OD
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- Shear stress
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- Poles
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- Max frequency
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Torque and speed at the motor
Solid: peak envelope. Dashed, shaded: continuous. Dots: duty points of the targets.
Full-throttle acceleration
A · Vehicle to wheel
| Quantity | Value | Note |
|---|
B · Wheel to motor
| Quantity | Value | Note |
|---|
C · Main dimensions
| Quantity | Value | Note |
|---|
D · Electrical limits
| Quantity | Value | Note |
|---|
Design card
Save the card to keep your results. The other Motoreka tools open the same file. If saving a file is blocked on this computer, copy the text instead.
What the calculator does
- Acceleration is simulated in 1 ms steps: motor torque is the lesser of peak torque and peak power over speed, and drops to zero at maximum motor speed.
- The hand estimate in table A uses the textbook formula with the base vehicle speed from your ratio and CPSR.
- Stack length is rounded up to the next 5 mm and stator OD to the nearest 5 mm.
- Turns per phase and flux linkage are first estimates for the voltage budget. The winding design and the finite-element check refine them.
- Your inputs are remembered in this browser only.
A B-segment range-extended EV
The starting values describe a small range-extended car: about 1,300 kg on test and 1,600 kg laden, driven only by its traction motor through a single-speed gear. The targets below were set so that the design problem is well defined. They are Training targets, not the specification of any production vehicle. Vehicle data marked Inferred come from published figures for cars of this class.
| Id | Target or constraint | Value | Status |
|---|---|---|---|
| T1 | 0–100 km/h, test mass | 9.5 s, not more than | Training target |
| T2 | 80–120 km/h, test mass | 7 s, not more than | Training target |
| T3 | Top speed, level road | 150 km/h, at least | Training target |
| T4 | Hill start, laden mass | 30 % | Training target |
| T5 | Sustained climb, laden mass | 6 % at 80 km/h | Training target |
| C1 | DC bus voltage | 300 to 400 V | Training target |
| C2 | Maximum motor speed | 13,000 rpm, not more than | Training target |
| C4 | Stator outer diameter and stack length | 220 mm and 150 mm, not more than | Training target |
Sizing is the first of seven stages
This calculator covers the first stage of the Motoreka method: from the vehicle to the rating and the main dimensions. The training and its companion book carry the same motor through topology, materials, the inverter and cooling, and a finite-element check in FEMM.