How Toyota’s Hybrid Synergy Drive (HSD) Technology Works?

What is Hybrid Synergy Drive?

Japanese automotive brand, Toyota, revolutionized the way a  hybrid car works. Toyota introduced a technology called Hybrid Synergy Drive which is a full hybrid technology; i.e with this technology, the car can cover a distance of 1.5 km – 16 km in various modes even without the engine running. Most of the other hybrids are called mild hybrids. They won’t work without an IC engine or the IC engine is running along with electric motors.

The Hybrid Synergy Drive is necessary for developing countries because of emission problems. Pure electric cars like Tesla, find it difficult to operate there because of the lack of proper infrastructure and electricity supply. Such hybrid vehicles will prove to be of a great worth there!

The concept of Hybrid Synergy Drive:

In Hybrid Synergy Drive, engines feature the ‘Drive by Wire‘ technology. In this technology, there is no physical connection between engine and accelerator paddle. Drive by wire is totally controlled by the bunch of electronic sensors and the ECU. Furthermore, the throttle position sensor determines the power required by the engine at the given throttle response.

Most of the traditional engines don’t work at optimum efficiency. So, the engine loses torque and precious fuel. Even the manufacturers have limited gears to work with such cases. But in case of Hybrid Synergy Drive, the e-CVT (electronic continuously variable transmission) or the computer selects best possible gear ratio at any given time. Thus, the engine runs at its optimum RPM resulting in more efficiency. This system can also shut down the IC engine when not required.

Hybrid Synergy Drive maintains proper co-ordination between wheel speed and engine. It tries to maintain constant engine RPM of 1500-2000; at which, IC engines are said to be most efficient.

Working of Hybrid Synergy Drive:

Hybrid Synergy Drive Equiped Engine
Hybrid Synergy Drive Equipped Engine (Courtesy: Toyota Corporation)

Typically this technology involves two electric motors or generators and one IC engine. These motors or generators named MG1 & MG2 can produce electricity or can utilize it to give power to the engine directly or indirectly.

The system uses MG1 is to start the engine, provide power to MG2 by generating electricity and charge the battery while MG2 drives the wheel with the help of power generated by MG1 and battery. It also charges the battery by acting as a generator during regenerative braking.

Hybrid Synergy Drive
Hybrid Synergy Drive

To explain the working mechanism easily we will take two scenarios – working in low gear and in high gear. In low gear, engine turns more rapidly while the wheels are moving slow. MG1 utilizes this additional speed of the engine to produce electricity by acting as a generator. The electricity is fed to MG2 which acts as an electric motor and provides torque to the wheels.

In high gears, wheels are moving fast while the engine is moving at slow or idle speed. This excess speed is fed to MG2 that generates electricity; which is again fed to MG1, that acts as an electric motor giving power to the wheels helping maintain a high speed. All these electric motors help in making more efficient drive than ever before.

Hybrid Synergy Drive is mainly used in Toyota Prius hybrid, Yaris, Auris, Highlander Hybrid, Camry Hybrid, Estima, Alphard, Lexus & in some Nissan models. This technology has tremendous potential in emerging countries like India and China which are struggling with emission problems!

For more information go to the link below:

Watch Hybrid Synergy Drive in Action here:


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Sushant is an entrepreneur, marketing consultant, and an auto-enthusiastic blogger. He regularly publishes specific articles on the latest happenings in automotive technology. When not writing a blog, he engages in his other ventures or goes on long-distance motorcycle rides. Follow me on Twitter.