Recently, consumers are interested in eco-friendly cars more than ever. In the first half of 2020, Hyundai Motor Group sold 67,798 vehicles (+36.2%) compared to the previous year. Among those, hybrid cars were the most popular. The total sales of hybrid vehicles, including plug-in hybrids, rose by 53.3% to 53,000 units, comprising 76.2% of all eco-friendly car sales. This is a huge implication of how many consumers are actually interested in eco-friendly vehicles.
Exports of eco-friendly cars have also increased by 14 percent in the first half of 2020, compared to the previous year, according to a report released by the Ministry of Trade, Industry, and Energy. And among them, the plug-in hybrid car sales increased by more than 25% compared to the previous year. The eco-friendly cars manufactured by Korean automakers, especially, are gaining high recognition in the European market, where environmental regulations are strict.
It’s only natural that people are becoming interested in eco-friendly cars as more and more environmental issues emerge every day. For consumers that might be hesitant in replacing their internal combustion engines with EVs or FCEVs, the hybrid cars serve a great alternative. And the increasing hybrid car sales prove this. Besides, the introduction of slow chargers for plug-in hybrid cars that allows charging as we do with home appliances has broadened the concept of eco-friendly cars.
The term hybrid, which means ‘mixed’, and combined with the word ‘car’, it signifies a vehicle that uses two power sources together. Hybrid cars are designed to sense when exactly the driver wants to accelerate, and then combine the power from the engine and the motor at the highest efficiency.
So, when the driver goes at a low speed with a start signal, the vehicle only uses the motor. And when the driver accelerates or the vehicle is all the way up a hill, it burns extra gas. The motor can also charge high-voltage battery by converting the remaining kinetic energy of the motor, which is leftover during deceleration, braking, or downhill. The hybrid car does not require extra charging because the engine’s generator and regenerative braking are enough to recharge the battery.
Plug-in hybrid cars and hybrid cars share the same basic design. Both vehicles house the internal combustion engine and the electric motor, but the plug-in hybrid vehicles have bigger batteries than the other one does. They also include On-Board Charger (OBC) for additional low-speed charging. The vehicle runs on electric power, and then the car automatically switches over to use the ICE depending on the road or the driver’s condition. In particular, the plug-in hybrid vehicles expanded the battery capacity and increased the range in electric mode. The vehicle will work the same as hybrid cars when the battery is depleted.
There is one key difference that the electric motor of an eco-friendly vehicle features between DC (direct current) motors, which are widely used in ordinary appliances: an AC Interior Permanent Magnet (IPM) synchronous motor. The motor generates a constant force and Hyundai Motor Group developed a more efficient and durable one. What’s notable is that this is the essential part that makes the regenerative braking system of eco-friendly car work. Sometimes the motor becomes a power generator when kinetic energy is applied from the outside; during the deceleration or downhill running, the motor’s energy flow changes in the opposite direction, and the motor converts the kinetic energy into electrical energy to deposit in the battery.
The chemical energy stored in the batteries of eco-friendly cars is converted into electric energy while driving and stored back in the battery in a chemical form during deceleration to enhance fuel efficiency and performance. Hyundai Motor Group’s lithium-ion polymer batteries have gone through countless safety performance tests before their application. The Group also focused on enhancing battery safety through extreme crash tests and prepared thoroughly for any possible accidents through quadruple safety barriers – ceramic coating separator, structures for manual protection, battery controllers, and safety repair support.
Usually, the high voltage battery required for driving is separated from the vehicle’s standard 12-volt lead-acid auxiliary battery, but Hyundai Motor Group has integrated these two batteries and put under the second-row seat; so, the trunk space has been secured, and the center of gravity also got closer to the middle of the vehicle, improving power performance.
Hybrid cars also use internal combustion engines, so they require a transmission. In an ICE, the power generated from the engine goes to the wheels through the transmission – and automatic transmission plays a vital role in manipulating the power before sent to the wheels, depending on the road condition, body weight, speed, etc.
Hybrid vehicles have an additional hybrid motor between the internal combustion engine and the automatic transmission; the power is generated from every three areas and delivered to the wheels through the transmission. This improves fuel efficiency and acceleration since the motor also gets to generate power, supporting the engine.
However, Hyundai Motor Group’s hybrid cars do not use the ‘torque converter’, a power conversion device for automatic transmissions. This is related to fuel efficiency. Torque converters convey power through a fluid inside the converter. Hence, there is energy loss. Furthermore, torque converters are heavy components and disadvantageous to fuel economy. This makes the transmission in a hybrid car not operate on cue and become sluggish.
This is the exact reason why Hyundai Motor Group redefined the role for motors. The newly added Active Shift Control (ASC) technology allows the hybrid’s electric motor to also take control of gear shifts by applying new software logic to the Hybrid Control Unit (HCU) to mitigate issues with slower shift time. The HCU monitors the rotational speed of transmission with a sensor installed inside the electric motor at 500 times per second to quickly synchronize the rotational speed with that of the engine.
With the synchronization, shift time is reduced by 30% from 500ms to 350ms. This not only improves hybrid vehicle’s acceleration performance and fuel economy but also durability of the transmission by minimizing friction during a gear shift.
HMG Journal Operation Teamgroup@hyundai.com
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