Kia will launch its first diesel mild-hybrid powertrain in the second half of this year. The new technology, dubbed EcoDynamics+, supplements powertrain acceleration with a 48V electric motor, extending the ‘off time’ of the combustion engine.
Power is supplied by a 48V battery, and the system utilizes Kia’s new Mild-Hybrid Starter-Generator (MHSG) unit. The powertrain’s components have been designed to be compact, making it easier to integrate the technology into existing architectures without a detrimental impact on packaging.
The EcoDynamics+ system doesn’t have plug-in recharging capability, Kia states, so as not to impact on consumers’ lives.
The Sportage will be the first Kia model to offer the mild-hybrid diesel powertrain, and will be launched later in 2018. The third-generation Ceed will be the second vehicle to feature the drivetrain, and will be launched in 2019.
The 48V system is the first new technology to be revealed as part of Kia’s long-term electrification strategy – which will see the OEM launch 16 advanced powertrain vehicles by 2025 (including five new hybrids, five PHEVs, five BEVs and, in 2020, a fuel-cell electric vehicle).
The EcoDynamics+ system is paired with Kia’s Selective Catalytic Reduction emissions control technology, with the auto maker claiming CO₂ emissions reductions of up to 4% on the WLTP, and up to 7% on NEDS.
The technology uses a compact 0.46kWh 48V lithium-ion battery and the MHSG. By electronically controlling the MHSG using the inverter, the system switches between motor and generator modes. The MHSG is connected to the diesel engine’s crankshaft via a belt and, under acceleration, provides up to 10kW of electric power assistance to the powertrain in motor mode. In generator mode, the system recovers kinetic energy during in-gear deceleration and braking, using the power to charge the battery.
In motor mode, the battery is discharged under acceleration – providing additional torque for a performance boost when accelerating hard, or reducing engine load during light acceleration. Deceleration (or when driving downhill or toward a junction), triggers a switch to generator mode.
The system is controlled by the ECU, which calculates the most efficient use of available energy. Battery power can also be used to provide the Moving Stop & Start functionality. When the battery has sufficient charge, the ICE switches off during in-gear deceleration and braking – it is restarted by the MHSG when the driver presses the throttle pedal.
Depending on the vehicle, the 48V battery can be installed beneath the floor of the boot, minimizing impact on architecture. As the MHSG is connected directly to the engine, repackaging in the engine bay is kept to a minimum.
The 48V battery’s DC/DC converter enables the new battery pack to connect with the vehicle’s onboard power supply, reducing the size of the 12V battery needed to power vehicle ancillaries. The conventional starter motor can be downsized and used largely for cold starts at low temperatures. Charge from the 48V battery can be used to assist in engine starts in most conditions.
The mild-hybrid powertrain can be used with manual and automatic transmissions, and can be adapted for front-, rear- and all-wheel drivetrain layouts. The technology can also be used in petrol applications.