What is the working principle of BYD's DM-i Super Hybrid?
3 Answers
DM-i Super Hybrid is based on a high-capacity battery and a high-power motor, with the vehicle being driven by the high-power motor during operation. The core component of BYD's DM-i Super Hybrid technology is the newly developed Xiaoyun plug-in hybrid-specific engine by BYD, which comes in two different versions—the 1.5L engine is mainly used in the Qin PLUS and Song PLUS, while the 1.5T turbocharged engine is used in the larger Tang DM-i model. The DM-i Super Hybrid is introduced as follows: 1. DM-i Super Hybrid models also include two key components: the EHS dual motor and the DM-i Super Hybrid-specific Blade Battery, along with a series of vehicle control systems, engine control systems, motor control systems, and battery management systems, collectively forming the Super Hybrid system. Most importantly, these core components and key technologies are entirely independently developed by BYD. 2. Power: The high-capacity, high-power battery can also support the efficient power system, keeping it operating in the high-efficiency zone for extended periods. Speaking of the world's most efficient power system equipped in the DM-i Super Hybrid, it features the Xiaoyun plug-in hybrid-specific 1.5L high-efficiency engine with a thermal efficiency of 43.04%, and the Xiaoyun plug-in hybrid-specific turbocharged 1.5Ti high-efficiency engine with a thermal efficiency of up to 40%.
Last time I researched this, I even took notes. The core of BYD's DM-i system relies on the partnership between a large battery and a highly efficient engine. At low speeds, it drives purely on electric power, just like an electric car—super quiet. The engine only kicks in to generate electricity when the battery is low, but electric drive is still prioritized. During high-speed cruising, the engine directly connects to the wheels for better efficiency, taking the lead as the primary fuel source. The key is that this engine is specifically optimized for power generation, featuring ultra-high thermal efficiency and an Atkinson cycle, operating mostly in the optimal RPM range when generating electricity. I’ve seen real-world test data showing just 4L/100km in city driving even with a depleted battery, burning half as much fuel as conventional hybrids. If charging is convenient, it can also run purely electric for about 100km, eliminating range anxiety on long trips. This power-split and energy recovery system is truly smart.
From an energy flow perspective, it's quite fascinating. The DM-i system operates in three modes: In full charge state, it runs in pure EV mode where the dedicated 1.5L engine doesn't intervene at all, delivering exceptional quietness; When battery is low, it switches to hybrid mode with the engine only generating electricity (not driving wheels), and surplus energy recharges the battery; During high-speed cruising, the system automatically engages parallel direct drive where the engine propels wheels directly through a single-speed transmission, achieving 44% thermal efficiency in this mode. The two motors have distinct roles - the generator motor solely serves the engine while the traction motor handles power output, and can also function as a generator during regenerative braking. The key advantage lies in its large 18kWh battery (ten times larger than Toyota's hybrid system), enabling extended pure-electric driving range.
