Electric car with torque wrench connecting engine to wheels, symbolizing torque-based engine management system.

Power Trip: How Torque-Based Engine Management is Revolutionizing Electric Vehicles

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Soraya Malik in Tech & Innovation August 2025 • 4 min read.

"Unlock the potential of range extender engines with innovative torque management strategies, enhancing efficiency and comfort in electric vehicles."


The electric vehicle (EV) revolution is charging ahead, but range anxiety and lengthy recharge times remain significant hurdles. Enter the range extender (RE), a compact engine-generator combo that provides on-demand battery charging, effectively extending the EV's operational range. But how do you ensure this RE operates optimally, providing the necessary power efficiently and smoothly? The answer lies in sophisticated engine management systems (EMS), and torque-based systems are emerging as a frontrunner.

Conventional engine management often relies on a speed-density approach, which calculates air intake based on sensor readings to determine fuel injection. However, torque-based EMS offers a more direct and coordinated method. It translates power demands into precise torque commands, adjusting throttle angle and spark timing to meet those demands. This approach allows for finer control and better integration with the overall vehicle management system.

This article explores the development and advantages of torque-based EMS for range extender engines, focusing on a research project that implemented such a system on a 125cc semi-direct injection LPG engine. We will delve into the system's architecture, control strategies, and experimental results, revealing how this technology contributes to improved fuel economy, reduced emissions, and a more comfortable ride.

The Architecture of Torque-Based Engine Management

Electric car with torque wrench connecting engine to wheels, symbolizing torque-based engine management system.

At the heart of a torque-based EMS is the ability to translate power requirements into precise torque commands. This process begins with the vehicle's power management strategy, which assesses battery state of charge (SOC) and driver demands to determine the necessary charging power. This power demand is then converted into specific torque and rotational speed targets for the RE engine. The EMS then takes over, coordinating various engine control parameters to achieve the desired torque output.

A crucial component of this system is the electronic throttle control (ETC), which precisely regulates the throttle angle to control air intake. Spark timing is another key factor, influencing combustion efficiency and torque delivery. The EMS carefully adjusts both ETC and spark timing to match the torque command while maintaining engine stability and preventing undesirable effects like knocking or excessive vibration. The research described developed torque-based EMS for a RE engine which is a 125cc four-stroke semi-direct injection engine and fueled by liquefied petroleum gas (LPG).

Key features of torque-based EMS include:
  • Centrally coordinated torque management
  • Centrally coordinated air-fuel (A/F) management
  • Aided calculations for EMS by physical models
This system offers a significant advantage over traditional speed-density EMS, particularly in its ability to respond quickly and accurately to changing power demands. By directly controlling torque output, the EMS can optimize engine performance for various operating conditions, ensuring efficient battery charging and a seamless driving experience. Moreover, torque-based EMS is easier to integrate with advanced control strategies, such as those that prioritize fuel economy or minimize emissions.

The Future of Range Extender Technology

Torque-based engine management systems represent a significant step forward in optimizing the performance and efficiency of range extender engines in electric vehicles. By providing precise control over torque output, these systems enable better fuel economy, reduced emissions, and a smoother driving experience. As EV technology continues to evolve, torque-based EMS will likely play an increasingly important role in extending the range and practicality of electric vehicles, bridging the gap between pure electric and traditional combustion engine powertrains.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

1

What is a range extender engine, and what problem does it solve in electric vehicles?

A range extender engine is a compact engine-generator combination used in electric vehicles to provide on-demand battery charging, effectively extending the vehicle's operational range. It addresses range anxiety and lengthy recharge times associated with EVs, bridging the gap between pure electric and traditional combustion engine powertrains.

2

How does a torque-based engine management system differ from conventional engine management approaches in electric vehicles?

Torque-based engine management systems offer finer control and better integration with the overall vehicle management system compared to conventional speed-density engine management. It translates power demands into precise torque commands, adjusting throttle angle and spark timing to meet those demands. This allows for improved fuel economy, reduced emissions, and a smoother driving experience.

3

What are the crucial components of a torque-based engine management system, and how do they work together?

Key components of a torque-based engine management system include the electronic throttle control (ETC) and spark timing mechanisms. The ETC precisely regulates the throttle angle to control air intake, while spark timing influences combustion efficiency and torque delivery. The engine management system carefully adjusts both to match the torque command while maintaining engine stability and preventing undesirable effects.

4

What are the key features of torque-based EMS and what advantages does this system offer over traditional speed-density EMS?

Torque-based engine management systems coordinate torque and air-fuel management centrally and utilize physical models to aid calculations. This system is better than traditional speed-density engine management because it responds quickly and accurately to changing power demands. By directly controlling torque output, the engine management system optimizes engine performance for efficient battery charging and a seamless driving experience. This also allows easier integration of advanced control strategies to prioritize fuel economy or minimize emissions. Other advanced strategies such as centrally coordinated exhaust gas recirculation are not discussed.

5

What are the specific benefits of using torque-based engine management systems in electric vehicles with range extenders?

Torque-based engine management systems improve fuel economy, reduce emissions, and provide a smoother driving experience in electric vehicles. By precisely controlling torque output, these systems optimize the performance and efficiency of range extender engines, contributing to a more practical and user-friendly electric vehicle experience. An interesting area not covered is a cost analysis of the overall torque based EMS. Are electric vehicles with torque based EMS more expensive than current EV's on the market.

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