Inside Toyota’s Hybrid Synergy Drive System

Hybrid vehicles are all the rage these days. They offer a fuel-efficient system balanced between an electrified motor and an internal combustion engine – internal combustion for high-speed power and an electric motor for clean efficiency and low-speed torque. And as the popularity of hybrids grow, so do the number of car manufacturers offering models with a hybrid drivetrain option.

But no matter how many hybrids there are on the market, Toyota’s Hybrid Synergy Drive is still the original and most fuel-efficient hybrid drivetrain available. But how does it work? It can get pretty technical, so we’ll try to keep it simple. First, let’s look at the components used in a hybrid system.

• Combustion Engine – Different than a traditional engine, and custom engineered with features like an electric water pump to eliminate mechanical losses from a belt and exhaust heat recirculation to warm an engine faster, all to achieve optimum fuel efficiency.
• Electric Motor – Synchronous A/C motors used for compact size, light weight and high efficiency for smooth starts and high-torque acceleration.
• Generator – Transfers mechanical energy to electrical energy through magnetism and high speed axial rotation for maximum electrical power.
• Power Split Device – Distributes power generated from the combustion engine between the generator and the wheels that drive the vehicle. This device allows a hybrid system to charge the electric system and run on a combustion engine simultaneously.
• Battery – Typically a nickel metal hydride (Ni-MH) unit which has superior recharging and energy capacity capabilities to store energy from the generator and brakes.
• Regenerative Braking – Kinetic energy usually wasted as friction heat when braking is instead collected by electric motors to store energy in the batteries for later use.
• Power Control Unit – Exists to convert DC power to AC power, triples the voltage output from 200V to 650V to power electric motors while also reducing DC power down to 12 volts to run components like the combustion engine’s computer.
• Reduction Gear – Connected between the drive wheels and the power source (either electric, combustion or both). Reduces high RPM of front electric motors for maximum torque amplification, resulting in seamless acceleration of the vehicle.

Now let’s look at the three kinds of hybrid systems that use these components.

• Series Hybrid System – Combustion engine turns the generator. Electric power produced is fed to the electric motor that drives the wheels. Therefore, the combustion engine only operates to keep the generator and electric motors charged and running the vehicle.
• Parallel Hybrid System – Wheels are driven by both combustion engine and electric motor, but the source is selected by driving conditions. Combustion is the primary power source, and electric kicks in to help acceleration. But the electric motor cannot simultaneously generate electricity and power the vehicle.
• Series/Parallel System – This system can drive wheels using both power sources as well as generate electricity while running on electric motors. The vehicle can run on electric only or by using both combustion and electric together. Since the generator is built into the system, it allows the battery to charge while the electric motor is still running.

Toyota’s Hybrid Synergy Drive system is a series/parallel system, also known as a “full hybrid”. The power split device is the critical component that makes Toyota’s hybrid system superior to many competitors. The power split device allows some of the combustion engine’s energy to power the generator for either recharging or electric power and directly power the wheels for motion.

So in the end, what does all this really mean for you, the person driving the car? Toyota’s Hybrid Synergy Drive system is engineered to deliver maximum fuel efficiency combined with a drivetrain that seamlessly and smoothly transitions between electric motor and combustion engine power.

Now that you’ve had a quick tutorial on hybrids, if you’re in the market for buying a new Toyota hybrid like the Prius, Camry or Highlander, get directions to Acton Toyota and show off your knowledge!