What is the braking function of Mitsubishi VFD?

As a supplier of Mitsubishi Variable Frequency Drives (VFDs), I often get asked about the braking function of these sophisticated devices. In this blog, I will delve into the details of the braking function in Mitsubishi VFDs, exploring its types, applications, and benefits.

Understanding the Basics of Braking in VFDs

Before we dive into the specifics of Mitsubishi VFDs, it's important to understand why braking is necessary in variable frequency drives. A VFD is used to control the speed of an electric motor by varying the frequency and voltage supplied to it. When the motor needs to decelerate quickly, the kinetic energy stored in the rotating parts of the motor and the load must be dissipated. If this energy is not properly managed, it can cause the DC bus voltage in the VFD to rise to dangerous levels, potentially damaging the drive.

Types of Braking Functions in Mitsubishi VFDs

Dynamic Braking

Dynamic braking is one of the most common braking methods used in Mitsubishi VFDs. In dynamic braking, the excess energy from the motor is dissipated as heat in a braking resistor. When the VFD detects that the motor is decelerating and the DC bus voltage is rising, it connects the braking resistor to the DC bus. The resistor then converts the electrical energy into heat, which is dissipated into the surrounding environment.

Mitsubishi offers a range of VFDs with built - in dynamic braking capabilities. For example, the Mitsubishi FR - E740 - 0.4K - CHT is a popular model that can be used with a braking resistor for dynamic braking. This type of braking is suitable for applications where the motor needs to decelerate quickly and the load inertia is relatively small.

Regenerative Braking

Regenerative braking is a more advanced braking method that allows the excess energy from the motor to be fed back into the power supply. Instead of dissipating the energy as heat, the VFD converts the DC power from the motor into AC power and returns it to the electrical grid. This not only reduces energy consumption but also helps to improve the overall efficiency of the system.

The Mitsubishi FR - E840 - 0095 - 4 - 60 is an example of a Mitsubishi VFD that supports regenerative braking. This drive is equipped with advanced power electronics that can efficiently convert and feed the energy back to the grid. Regenerative braking is ideal for applications with high - inertia loads or where frequent braking and acceleration cycles are required, such as in elevators, cranes, and conveyor systems.

DC Injection Braking

DC injection braking is another braking method available in Mitsubishi VFDs. In DC injection braking, a DC voltage is applied to the motor windings to create a stationary magnetic field. This magnetic field opposes the rotation of the motor, causing it to decelerate. DC injection braking is typically used for low - speed applications where a quick stop is required, such as in small conveyor belts or machine tools.

The Mitsubishi FR - A8NCE can be configured to use DC injection braking. This type of braking is relatively simple and cost - effective, but it may not be suitable for applications with high - speed or high - inertia loads.

Applications of Braking Functions in Mitsubishi VFDs

Industrial Machinery

In industrial machinery, such as milling machines, lathes, and presses, the braking function of Mitsubishi VFDs is crucial for ensuring safe and efficient operation. Dynamic braking can be used to quickly stop the motor when the machining operation is completed, reducing the cycle time and improving productivity. Regenerative braking can be beneficial in applications where the machinery has high - inertia loads, such as large presses, as it can save energy and reduce wear on the braking components.

HVAC Systems

In heating, ventilation, and air - conditioning (HVAC) systems, Mitsubishi VFDs with braking functions can help to improve the control and efficiency of fans and pumps. For example, when the demand for air or water flow decreases, the VFD can use dynamic braking to quickly reduce the speed of the motor, saving energy and reducing noise. DC injection braking can be used in small fans or pumps to provide a quick stop when the system is shut down.

Mitsubishi FR-E840-0095-4-60

Transportation Systems

In transportation systems, such as elevators and escalators, the braking function of Mitsubishi VFDs is essential for passenger safety. Regenerative braking is commonly used in elevators to recover energy during the descent and to provide smooth and precise control of the elevator car. Dynamic braking can be used in escalators to quickly stop the movement in case of an emergency.

Benefits of Using Mitsubishi VFDs with Braking Functions

Energy Savings

As mentioned earlier, regenerative braking allows the excess energy from the motor to be fed back into the power supply, resulting in significant energy savings. Even in dynamic braking applications, the use of a well - sized braking resistor can help to optimize the energy consumption by dissipating the energy in a controlled manner.

Improved System Performance

The braking function in Mitsubishi VFDs provides precise control over the motor's deceleration, which can improve the overall performance of the system. This is especially important in applications where accurate positioning or quick stops are required.

Extended Equipment Lifespan

By properly managing the energy during braking, Mitsubishi VFDs can reduce the stress on the motor and other components, extending their lifespan. This can lead to lower maintenance costs and less downtime for the system.

Conclusion

The braking function in Mitsubishi VFDs is a critical feature that offers a variety of benefits in different applications. Whether you need dynamic braking for quick stops, regenerative braking for energy savings, or DC injection braking for low - speed applications, Mitsubishi has a VFD solution to meet your needs.

If you are interested in learning more about Mitsubishi VFDs and their braking functions, or if you are looking to purchase these products for your application, I encourage you to contact me for further discussion. We can work together to determine the best VFD model and braking solution for your specific requirements.