Frequency Converter and Energy Saving: How Does It Work?

Most frequency converters have two operating modes: one for constant-torque loads, where the load does not depend on speed (e.g., conveyor, hoist drive, compressor, etc.), and one for M~n² mode, where the load is proportional to the square of the speed (e.g., centrifugal pump, fan, etc.). In constant-torque mode, the frequency converter attempts to maintain high torque by keeping the magnetic field as strong as possible. In the second mode, the torque is reduced according to a calculated curve, helping to achieve energy savings. However, neither of these modes considers the actual behavior of the load.

Mitsubishi frequency converters’ Optimum Excitation Control takes the load’s real-time behavior into account and provides exactly the amount of motor torque required at any given moment.

Optimum Excitation Control

The Optimum Excitation Control function in Mitsubishi frequency converters aims to optimize motor energy consumption by providing precise control and reducing unnecessary power usage. This function allows the frequency converter to automatically adjust the motor excitation (i.e., the electrical energy needed to create the magnetic field) according to the actual load and operating conditions.

Optimum Excitation Control increases motor efficiency and reduces energy consumption. Thanks to high CPU performance and precise measurement, Mitsubishi converters implement this function with exceptional accuracy: the converter can measure motor parameters more frequently and precisely, enabling even more efficient control and energy savings.

Operating Principles of Optimum Excitation Control

1. Excitation adjustment: The function continuously monitors changes in motor load and adjusts the excitation to achieve optimal energy efficiency. When the load decreases, the frequency converter reduces the motor’s excitation to avoid the energy losses that typically occur during underload conditions.

2. Real-time control and monitoring software: Mitsubishi frequency converters use advanced algorithms that monitor motor operation and regulate excitation according to load conditions. This ensures that the motor operates with exactly the amount of energy needed, avoiding unnecessary over-excitation or under-powering.

3. Reduced heat loss: When the motor operates with lower excitation, less energy is wasted as heat. As a result, the motor runs at a lower temperature, extending its lifespan and reducing cooling costs.

4. Balancing energy efficiency and performance: Optimum Excitation Control in Mitsubishi converters ensures a balance between motor performance and energy consumption. This means the converter can maintain the required performance level even when energy usage is optimized and reduced.

How to Set It Up?

Select parameter P.60 in the frequency converter and set its value to 9.