The Physics of Timing in Motors

Timing in a brushless motor refers to the point at which current is delivered to the coils, relative to the position of the rotor. By adjusting this point, you can influence the motor's torque, speed, and efficiency.

The neutral plane is the position at which the rotor's magnetic field aligns perfectly with the stator's magnetic field. Ideally, the motor is most efficient when commutation (current switching) occurs close to this neutral plane. However, as the RPM (revolutions per minute) changes, the ideal timing point also shifts.

Physics Behind Dynamic Timing ("Boost")

The reason why dynamic timing can be more efficient is due to its adaptability. When a motor is running at low RPMs, keeping the timing advance low reduces the current draw, which in turn reduces heat generation. At higher RPMs, the timing advance increases to maintain optimal efficiency and power output.

Dynamic Timing (Boost) and its Benefits

Dynamic timing, often termed "boost," lets you adjust the motor's timing based on its RPM. As opposed to static timing where the timing remains constant, dynamic timing varies with the RPM. This adaptability means:

1. Efficiency & Temperature Control: At low RPMs, the timing is kept low, which is closer to the neutral plane, leading to cooler motor operation. As RPMs rise, the timing advances, maintaining proximity to the neutral plane. This adjustment ensures that the motor runs more efficiently across a broader RPM range.
2. Power Management: A motor with dynamic timing can deliver more consistent power throughout its RPM range, optimizing performance across different racing scenarios.

Electronic Speed Controllers (ESC) and Timing Advance

ESC devices control the timing. Older models were simplistic, applying a more abrupt timing adjustment, leading to rough transitions. Modern ESCs offer smooth, progressive timing changes, making them superior in performance.

Blinky vs. Boosted: Both methods can achieve similar high RPM characteristics. However, in a blinky setup with a high static timing, the motor might run hotter at low RPMs due to inefficiencies. In contrast, a boosted setup can efficiently manage the low RPMs, keeping the motor cooler.

Practical Challenges

While, in theory, one could determine the optimal timing at every RPM using a dynamometer, most racers rely on experience and trial and error. Determining the neutral plane and the precise timing settings for optimal performance is a complex task.

Boost vs. Turbo in ESCs

Boost is a straightforward setting controlled by three parameters: (Traditionally)

• Start RPM: Where timing begins to advance.
• Finish RPM: Where the maximum timing advance is reached.
• Timing Advance: The degree of advancement.
• Throttle based boost is an option on some electronic speed controllers, where the principal is the same except the range is defined with throttle input (0-100%) instead of RPM range.

Turbo provides an additional, more aggressive timing advance to give that extra punch of power, primarily for straight paths in racing tracks. It's activated under specific conditions, like full throttle or upon reaching a particular RPM.

How They Work Together

All these timing mechanisms combine to provide the total timing advance. The static timing on the motor (endbell setting), the dynamic timing from the boost, and the aggressive adjustment from the turbo all sum up.

Example: If your motor is set at 20°, your boost provides an additional 35°, and your turbo adds another 20°; at the end of a straight stretch on a race track, you could be running at a total of 75° of timing advance.

Conclusion

Dynamic timing provides a nuanced approach to motor performance, balancing efficiency, temperature, and power across different RPMs. While understanding and setting up these systems can be complex, the benefits in terms of motor performance and efficiency are significant. Always monitor heat, especially with high timing values, to ensure motor longevity and optimal performance.