What is the Peak Power of an Electric-Axle (e-axle)?

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Editorial Team - everything PE

Dec 20, 2023

Peak power or maximum power is the highest output power of an e-axle that can deliver for short durations, typically a few seconds or less. It represents the electric axle's ability to handle brief bursts of high load or acceleration, such as during rapid acceleration or climbing steep hills. Peak power is important for achieving high acceleration and top speed, but it's not sustainable for continuous operation.  It is a fundamental variable that affects the acceleration, top speed, and overall performance of an electric vehicle. The peak power of electric axles plays a crucial role in designing and determining the efficiency of EVs. It is influenced by various factors, including the electric motor's characteristics, voltage, and current ratings. 

The peak power is reached when the electric axle operates at its maximum voltage and current ratings. This can be expressed as:


  • Ppeak is the peak power,
  • Vmax is the maximum voltage,
  • Imax is the maximum current.

Torque and power curves of the motor of an EV

Factors Affecting Peak Power

  • Motor Design: The design of the electric motor, including its size, type (e.g., brushless DC, induction, synchronous), and efficiency, significantly affects peak power.
  • Torque-Speed Characteristics: The torque-speed curve of the motor influences the point at which peak power occurs. Balancing torque and speed is crucial for maximizing power output.
  • Voltage and Current Limits: Electric axles are designed with specific voltage and current ratings. Operating within these limits is essential to ensure reliability and prevent damage to the components.
  • State of Charge (SoC): The state of charge of the battery influences its ability to deliver the required current for peak power. Maintaining optimal SoC levels is critical for peak performance.
  • Acceleration Requirements: The need for rapid acceleration in certain driving scenarios influences the design considerations for achieving higher peak power output.
  • Regenerative Braking: Systems that incorporate regenerative braking may influence peak power by recovering and utilizing energy during deceleration.
  • Vehicle Load Conditions: The weight and payload of the vehicle can impact the power required for acceleration, influencing the design considerations for peak power.

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