Snubber circuit design in power electronic circuits
8:48 AM
In this blogpost i will explain the importance of snubber circuits in power electronic applications. Additionally, the types of snubber circuits will also be discussed and some of the circuits that were published in past years.
Snubber circuits snubs the extra stress on the power semiconductors either during turn on or in turn off condition. They can be classified in various forms. For example , based on efficiency they can be classified as lossy snubber and lossless snubbers. They can also be classified on the basis of components used. In this case there are two classes namely passive and active snubbers. Based on the switching time period they are called as turn on snubber and turn off snubber.
Snubber circuits are primarily used in circuits with inductance either in the form of inductor or leakage inductance. They are very useful in reducing power dissipation due to switching loss and electromagnetic compatibility (EMC) effects [1].
The losses in a semiconductor switch occur either at turn on or at turn off because it is the time when a transition of voltage across and current through the device occurs. The turn on losses are dependent on the load current, the supply voltage, diode reverse recovery effects, rate of rise of current di/dt and the frequency of operation.
Passive snubber : The most common type of passive snubber to control the turn on loss is an inductor. The use of inductor slows down the di/dt in a switch. Moreover, it also compensates the effects of diode reverse recovery. However, this method inherits the issue of inductor reset i.e this inductor has to release the stored energy (1/2 Li2). This counts for a loss if the operation is at high frequency. Therefore this kind of snubber is a passive lossy snubber. However, this kind of snubber can be made losseless by using resonant tank, auxiliary commutation and passive energy recovery snubbers [1] . Another passive lossless snubber circuit is presented in [2]. These methods are more complex.
Another way is to use a saturable core snubber circuit that is reported by [1] as an effective method. This method when used with a bridge leg requires two saturable inductors. This is because these saturable inductors are only effective when used in high inductance unsaturated region (click here to read more on saturable inductor).
Active snubber circuits use auxiliary switch to reduce the stress on power semiconductor. They are lossless snubbers because they do not waste energy. However, these snubber circuits add complexity to not only the topology but also to the control structure and
[1] Finney, S.J., Tooth, D.J., Flethcer, J.E. and Williams, B.W., 1999. The application of saturable turn-on snubbers to IGBT bridge-leg circuits. Power Electronics, IEEE Transactions on, 14(6), pp.1101-1110.
[2] Fujiwara, K. and Nomura, H., 1999. A novel lossless passive snubber for soft-switching boost-type converters. Power Electronics, IEEE Transactions on, 14(6), pp.1065-1069.
Snubber circuits snubs the extra stress on the power semiconductors either during turn on or in turn off condition. They can be classified in various forms. For example , based on efficiency they can be classified as lossy snubber and lossless snubbers. They can also be classified on the basis of components used. In this case there are two classes namely passive and active snubbers. Based on the switching time period they are called as turn on snubber and turn off snubber.
Snubber circuits are primarily used in circuits with inductance either in the form of inductor or leakage inductance. They are very useful in reducing power dissipation due to switching loss and electromagnetic compatibility (EMC) effects [1].
The losses in a semiconductor switch occur either at turn on or at turn off because it is the time when a transition of voltage across and current through the device occurs. The turn on losses are dependent on the load current, the supply voltage, diode reverse recovery effects, rate of rise of current di/dt and the frequency of operation.
Passive snubber : The most common type of passive snubber to control the turn on loss is an inductor. The use of inductor slows down the di/dt in a switch. Moreover, it also compensates the effects of diode reverse recovery. However, this method inherits the issue of inductor reset i.e this inductor has to release the stored energy (1/2 Li2). This counts for a loss if the operation is at high frequency. Therefore this kind of snubber is a passive lossy snubber. However, this kind of snubber can be made losseless by using resonant tank, auxiliary commutation and passive energy recovery snubbers [1] . Another passive lossless snubber circuit is presented in [2]. These methods are more complex.
Another way is to use a saturable core snubber circuit that is reported by [1] as an effective method. This method when used with a bridge leg requires two saturable inductors. This is because these saturable inductors are only effective when used in high inductance unsaturated region (click here to read more on saturable inductor).
Active snubber circuits use auxiliary switch to reduce the stress on power semiconductor. They are lossless snubbers because they do not waste energy. However, these snubber circuits add complexity to not only the topology but also to the control structure and
[1] Finney, S.J., Tooth, D.J., Flethcer, J.E. and Williams, B.W., 1999. The application of saturable turn-on snubbers to IGBT bridge-leg circuits. Power Electronics, IEEE Transactions on, 14(6), pp.1101-1110.
[2] Fujiwara, K. and Nomura, H., 1999. A novel lossless passive snubber for soft-switching boost-type converters. Power Electronics, IEEE Transactions on, 14(6), pp.1065-1069.
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