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Users often get confused between electromagnetic braking, regenerative braking, and dynamic braking, which can lead to choosing the wrong accessories. Understanding the differences between these braking methods is essential for proper system design and operation.

Dynamic braking involves a resistor that dissipates energy during faults, emergency stops, or power outages, helping to reduce the mechanical feed distance of the servo motor. This method doesn't require the system to be powered on, making it reliable in critical situations.

Regenerative braking, on the other hand, returns the energy generated during deceleration or stopping back to the DC bus via an inverter loop. The energy is then absorbed by an RC circuit, allowing for more efficient use of power in normal operating conditions.

Electromagnetic braking works by mechanically locking the motor shaft, providing a physical stop without relying on electrical components. It is typically activated after the servo is turned off to prevent overload on the amplifier.

The key differences between the three are as follows:

(1) Regenerative braking only works when the system is functioning normally. It cannot be used during faults, emergency stops, or power failures. Dynamic and electromagnetic brakes, however, do not require power to operate.

(2) Regenerative braking is usually handled automatically by the system, while dynamic and electromagnetic braking often require external relay control.

(3) Electromagnetic brakes should be engaged after the servo is turned off to avoid overloading the amplifier. Similarly, dynamic braking should be used after the servo is off or the main circuit is de-energized to prevent overheating of the resistor.

When selecting the right accessories, consider the following:

(1) For systems like conveyors or lifting devices that need rapid stopping, especially in emergencies or power failures, dynamic braking is often necessary. The choice should depend on the load weight and motor speed to ensure safe and effective braking.

(2) If a system requires long holding torque to maintain position, using the servo's self-locking function may cause overheating or overload. In such cases, a motor with an electromagnetic brake is recommended to provide a mechanical lock.

(3) Some servo systems, like those from Mitsubishi, include built-in regenerative braking units. However, frequent regenerative braking can cause high DC bus voltage, requiring an additional regenerative resistor. Always check the manufacturer’s guidelines for specific requirements. Keep in mind that the numbers listed in the sample are based on no-load conditions. When selecting, calculate the inertia ratio of your system and divide the sample number by (inertia ratio + 1) to determine the correct braking capacity.