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Comparison common mode noise reducibility of full-bridge and buck converters for unidirectional DC motor drive
Author(s)
Thanasana, S.
Srisawang, A.
Panaudomsub, S.
Prempraneerach, Y.
Date Issued
December 1, 2005
Type
Conference Paper
Abstract
An unidirectional speed control of dc motor is more appropriate in some condition for specific application which is usually used by either buck converter or an unipolar switching mode of full-bridge converter. This paper is purposed to compare the common mode noise reduction ability of both buck converter and an unipolar switching mode of full-bridge converter. This comparison will help the driver design engineer to correctly select the dc motor driver for application must worry about the noise factor. With regard to an electromagnetic interference (EMI) causing in general dc-dc converters is necessary to determine the essential parameters in the circuit such as the parasitic capacitances of heat sink, a switching noise, an unbalanced characteristic of a circuit and so on. The general buck converter for dc motor drive usually uses unbalanced circuit topology between sending and returning power line. The unbalanced buck converter will generate the common mode current to flow through the parasitic capacitance of heat sink to a frame ground or chassis. This paper is also purposed to illustrate the common mode noise reduction ability of a full-bridge converter for dc motor drive. The most significant specific characteristic of a full-bridge converter is the simultaneous switching on and off of the two switching devices (Q1 and Q2 or Q3 and Q4) which are performed in both bipolar switching mode and unipolar switching mode operation. When the two switching devices are simultaneous operated on and off which has a dc motor to be existing between their switching actions, such a simultaneous switched performance is illustrated the characteristic of the active noise cancellation at the dc motor terminals. In addition, due to the full-bridge converter circuit has a symmetrical scheme when the four parasitic capacitances of the heat sink are connected to the frame ground or chassis will provide more circuit balance. The circuit balance and active noise cancellation characteristics of the unipolar switching mode of a full-bridge converter will show the ability to greatly reduce the common mode noise is confirmed by experimental results. © 2005 SICE.
Citation
Proceedings of the SICE Annual Conference, 1336-1341, 2005