i-MiEV Technology

The AC synchronous permanent magnet motor develops 49kW (66bhp) and a high 180Nm (133 lb.ft) of torque - but importantly all of the latter is available instantly, from 0rpm right up to 2,000rpm, enabling the i-MiEV to easily keep up with city traffic. The motor continues to pull strongly beyond 2,000rpm ensuring a relaxed driving experience.

The motor’s high torque output and ability to spin to 8,000rpm means no gear changes are necessary, and the single gear ratio (6.066:1) delivers optimal performance. The transmission includes a conventional differential but no reverse gear is required since the motor spins in the opposite direction when R (Reverse) is selected via the gearshift.

The traction battery pack, located below the i-MiEV’s floor, consists of 88 lithium-ion 3.7V/50Ah cells connected in series to deliver 330V/16kWh, and powers the electric motor (via the inverter), air conditioning and cabin heater. Other devices are powered by a conventional 12V auxiliary battery, charged by the traction battery via a DC-DC converter integrated with the on-board charger. Safety features include a cell monitoring device, electrical leakage detector and a very strong protective casing.

The inverter unit converts the traction battery’s DC output voltage into a 3-phase AC supply required by the electric motor.

Battery charging from a normal domestic electricity supply is achieved via an on-board charger which converts mains AC voltage to a suitable charging voltage for the traction battery. A full charge from at or near empty can be achieved in around 7 hours. i-MiEV is supplied with a dedicated 5-metre domestic charging cable (N.B. A conventional extension cable must never be used!) The normal charging socket is located on the rear right-hand side of the vehicle.

If access to a rapid charging point is available, i-MiEV can be charged from empty to 80% in as little as 30 minutes. The rapid charging socket is located on the rear left-hand side of the vehicle, and is designed to be compatible with the standardised connector on the end of the rapid charging unit's heavy-duty cable.

When the accelerator is released the vehicle will slow down due to the regenerative braking effect - under this condition the inertia of the vehicle turns the motor into a generator which momentarily recharges the traction battery. i-MiEV has three driving modes, marked D, B and C on the gearshift panel. D mode is for urban driving, tuned to be energy efficient; B mode increases regenerative braking during downhill driving; C mode decreases it for smoother driving characteristics on longer runs.

Lateral slippage can easily occur if the rear wheels lock up due to braking hard on slippery surfaces or braking hard when at high speeds. ABS suppresses this by controlling the brakes’ hydraulic pressure. EBD adjusts the rear wheels’ braking force to the number of occupants and load to deliver braking force that is ideally matched to almost any situation.

Active Stability Control - If sensors located throughout the car detect unstable movement, such as lateral slippage, the Stability Control function automatically controls the brakes and motor torque to stabilise the car.

Traction Control - If the sensors detect wheel slip when starting on slick surfaces, such as a snow-covered road, the Traction Control function automatically brakes the slipping wheel and governs motor torque to enable a smoother start. Unlike other vehicles it also functions while decelerating, to improve stability during regenerative braking.

The i-MiEV adopts a MacPherson strut design for its front suspension which, assisted by a stabiliser bar, provides excellent on-road handling characteristics. The rear suspension employs a 3-link de Dion system. The traction battery position also provides i-MiEV with a low centre of gravity for stable cornering performance.

To keep occupants in every seat safe in the event of a collision, the i-MiEV is equipped with a 6-airbag system to provide protection from all sides. Curtain airbags extending along both sides protect front and 2nd-row occupants in a side collision, while the 1st-row occupants are additionally protected by front and side airbags.