Multi Quadrant Operation Of DC Motor, Dual Converter, Field Reversal

Hello guys, welcome back to my blog. In this blog, I will discuss the multi quadrant operation of a dc motor fed from a fully controlled rectifier, dual converter, and field reversal.

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Multi Quadrant Operation Of DC Motor Fed From Fully Controlled Rectifier, Dual Converter, Field Reversal

What is a multi quadrant operation?

The multi quadrant operation means making the motor operate in four quadrants such as forward motoring, forward braking, reverse motoring, reverse braking, etc.

Multi Quadrant Operation Of DC Motor Fed From Fully Controlled Rectifier

A fully controlled rectifier feeds the motor through a reversing switch RS which is used to reverse the armature connection with regard to the rectifier. A fully-controlled rectifier is able of providing operation in quadrants one and fourth. The reversal of the armature connection provides operation in quadrants third and second.

The reversing switch may consist of a relay-operated contactor with two normally open and two normally closed contacts as shown in the above figure. When slow operation and regular maintenance associated with the contactor are not acceptable, the reversing switch is realized using a thyristor as shown in the above figure.

With thyristor pair, Tf on, and pair Tr off we can obtain operation in quadrants one and four. With pair Tr on and Tf off, we can obtain operation in the third and second quadrant. In both the configurations of RS, the switching is done to zero current in order to avoid voltage spikes and to reduce its rating.

Multi Quadrant Operation Of DC Motor Fed From Dual Converter

The dual converter the name itself means that it has two converters in it. It is an electric device mostly found in variable speed drives. It is a power electronics control system to get either polarity DC from AC rectification by the forward converter or reverse converter. In a dual converter, two converters are connected together back to back.

One of the bridges works as a rectifier (converts AC to DC), and another bridge works as an inverter (converts DC to AC) and is connected commonly to a DC load. Here two conversion processes take place simultaneously, so it is called a dual converter. The dual converter can provide four-quadrant operations.

Rectifier A which provides positive motor current and voltage in either direction allows motor control in quadrants one and four. Rectifier B provides motor control in quadrants third and four because it gives negative motor current and voltage in either direction.

Four Quadrant Drive With Field Reversal

Four quadrants drive with field reversal as shown in the above figure. The armature is fed from a fully-controlled rectifier and the field from a dual converter so that the field current can be reversed. With field current in one direction, the motor operates in quadrants one and four. When the field current is reversed it operates in quadrants third and second.

I hope this article may help you all a lot. Thank you for reading.

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Chetan Shidling

Automotive | Technical Blogger | Engineer | Content Creator

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