AC drives are widely used in mechanical systems to control speed and power. They are essential because they provide a stable or fixed speed to the system, which is not always achievable with DC drives. Furthermore, an AC drive can be used as a stand-alone or in combination with DC drives. They are also employed in generators and motors to control the speed of power production, where the output shaft is mechanically coupled to the input shaft of the engine or generator. While most users are aware of its application and benefits, not many are knowledgeable about the components of an AC drive circuit. To mitigate that here’s an easy guide to help you learn about it.

Overview of an AC drive circuit

The Rectifier Section

The rectifiers take AC input voltage and convert it to DC voltage. Basically, the rectifier section in an AC drive converts the high-voltage, low-current AC input from a line source into high-voltage, high-current DC output.

However, the power output of the rectifier section can get very high, so the AC drive must use a large transformer to step down the voltage.

The Filter Section

The filter section of an AC drive can be found between the input and output sections of the power supply. The filter section is designed to filter out AC ripples that may have been introduced into the power supply, which can consequently cause the AC drive to malfunction. Thus, with the help of a capacitor and an inductor, these ripples are rejected, and the power is essentially cleaned. Apart from filtering out these fluctuations, a variety of noise reduction filters can also be employed in the system. 

The Inverter Section

The inverter section of an AC drive converts the now filtered DC input current into a high-frequency, high-voltage, low-current output that mimics AC current, which is finally used to run variable frequency drives. This is done with the help of electronic switches, which gives the current a pulsating stimulus, essentially mimicking the AC current. The frequency of this output current is directly proportional to the rate of switching.

To conclude, this is how AC drives receive the input current that allows them to operate efficiently.

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