What is the principle of Honda's i-MMD hybrid technology?
2 Answers
i-MMD hybrid system working principle: For most of the time, the engine is decoupled from the wheels, allowing it to operate entirely within its most efficient range. The energy is either stored in the battery or directly couples the generator and motor to drive the motor. During high-speed cruising, it can completely detach from the electric system and focus on driving the wheels to improve transmission efficiency. Below is an introduction to the hybrid modes achievable by i-MMD: EV Driving Mode: Pure electric mode, known as EV drive. In this mode, the engine is inactive, the clutch is disengaged, and the motor directly outputs torque through the gear mechanism. Series hybrid mode, known as Hybrid drive. In this mode, the engine generates electricity via the generator, the clutch is disengaged, and the motor outputs torque through the gear mechanism. Parallel hybrid mode, known as Engine drive. In this mode, the engine directly outputs torque, the clutch is engaged, and the motor simultaneously outputs torque. Hybrid Driving Mode: Essentially a series configuration, characterized by the engine being connected only to the generator. The engine is responsible for generating electricity to power the motor that drives the vehicle. In this mode, the battery can be in either a "charging" or "assisting" state. Additionally, the wheels are not connected to the engine, allowing the engine to always operate at its optimal fuel efficiency speed, independent of vehicle speed. Engine Driving Mode: The engine driving mode is one of the most distinctive features of the i-MMD system. In direct drive mode, a clutch connects the engine directly to the wheels, enabling the engine to drive the vehicle forward. Meanwhile, the battery can be in either a "charging" or "assisting" state, both of which are facilitated by the motor. In this state, the generator is stationary, and when the battery is in the "assisting" state, the system effectively operates in a parallel hybrid mode.
As a Honda hybrid owner, I find the i-MMD system's working principle quite intuitive, relying mainly on the clever combination of electricity and the engine. When driving at low speeds, it operates almost entirely on electric power, with the vehicle being driven by the electric motor, making it as quiet as an electric car. When the battery is low or during acceleration uphill, the engine starts to generate electricity but only operates within its most efficient range, supplying power to the electric motor to drive the wheels, rarely providing direct power—this avoids fuel wastage. At high speeds, the system allows the engine to directly engage in driving, reducing conversion losses. Regenerative braking recovers braking energy, feeding it back to the battery for storage. Daily fuel consumption is impressively low, around 4L per 100 kilometers. The overall driving experience is smooth and jerk-free, with simple maintenance. After two years of driving an Accord hybrid, the battery life remains long with no major issues, making it both economical and worry-free.
