VSDs are more than just speed controllers

VSDs are more than just speed controllers

In a Schneider Electric machine and automation blog, François Malrait explains why VSDs are more than just speed controllers. Engineers use drives for a variety of purposes depending on the function required. This means the task is the focus, rather than the product. For many, the purpose of a VSD (Variable Speed Drive) is to run a motor at variable speeds, but it is capable of much more.

It is also a smart actuator capable of connection and integrated into automation, safety or power conversion systems. Moreover, it acts at all the levels of an application by protecting, controlling, and monitoring connected equipment. This includes pump systems, machines, conveyors, cranes and more. In many applications it can replace a servo system.


A frequency converter

If we look at its input/output. It can deliver full current from 0 to 599Hz, but also up to 2000Hz as a fundamental frequency.


A power converter

It is possible to connect drives together through DC bus sharing architecture. It is also possible to use the power converters to optimize the power conversion solution, connecting them in series or in parallel.


An automation safe controller PLC

A drive is a connectable low-level controller because of its embedded capability, making it a low-level controller with fieldbus communication. Insulated from power mains supply, it’s a safe and certified device. It can store data from its environment and exchange it with connected devices. Additionally, its embedded communication link will exchange data between drives in an optimal and transparent way.



You can quickly start a drive configuration for an application, and it can be stored and applied to other drives. Aditionally, you can start, stop, and locally reset a drive, check the application and alert the user.


A motor control solution

A VSD can control all types of machines. This includes induction motors, permanent magnet motors, and synchronous reluctant motors. It optimises the machine energy consumption and maximises the mechanical power capability. The settings functions (manual or automatic) complete the electrical motor control.


A mechanical control solution

A motor is a power converter from an electrical energy to a mechanical power. The mechanics being managed by fundamental principles linking position, speed, torque through dynamic equations. Embedded within the drives are the mechanical principles addressing torque, speed and position.


An application control solution

A drive is application oriented. Embedded within it are application functions for pumps, compressors, fan and so on. The model-based approach ensures, management of application control functions dealing with process variables.

In a service-oriented and solution approach, the variable speed drive has grown up to become something much more. It is an optimized energy drive (OED), acting efficiently to command, protect, connect and monitor in every field of application.


VSDs are more than just speed controllers

Finally, is it time for a name change? after all they are smart machines in their own right?


For more Smart Automation visit 999 Schneider

Recent blog posts