Determining Current Flow in an Ideal Transformer

[Infidel22]

I am having some difficulty detertming the directions current should flow in an ideal transformer given a certain dot convention. My general understanding in the past was that you simply used conservation of power: V1I1=V2I2, thus if the sign of V2 is opposite of V1, then the sign of I2 must be opposite of I1. However, when attempting to analyaze a forward converter, I end up getting the current directions backwards.

Is there any simple pattern to follow when deriving current directions through an ideal transformer?

 

[Astronuc]

A tutorial on the "dot convention" used in transformers.

http://www.allaboutcircuits.com/vol_2/chpt_9/4.html

The current direction in a wire conductor (rather than transformer magnetic conductor) is affected by the 'winding direction' with respect to the magnetic flux.

 

[piercas]

Thank you for sharing your current difficulties with determining current flow in an ideal transformer. I can understand how this can be a confusing concept. Let me help clarify some of the key principles involved in determining current flow in an ideal transformer.

Firstly, it is important to understand that an ideal transformer is a theoretical concept that assumes no losses or impedance in the transformer. In reality, there will always be some losses and impedance which can affect the actual current flow. However, in this ideal scenario, we can use the conservation of power principle you mentioned to determine the current flow.

As you correctly stated, the equation V1I1=V2I2 is a key principle in determining current flow in an ideal transformer. This equation is based on the law of energy conservation, which states that energy cannot be created or destroyed, only transferred from one form to another. In the case of a transformer, the energy is transferred from the primary winding to the secondary winding, and this relationship holds true.

Now, to understand the direction of current flow, we need to consider the dot convention. This convention is a standard used to indicate the polarity of the windings in a transformer. The dots are placed at the ends of the windings, and the winding with the dot on the left is considered the primary winding, while the one with the dot on the right is the secondary winding.

In an ideal transformer, current flows from the high voltage side (V1) to the low voltage side (V2). This means that the primary winding is where the energy is being supplied, and the secondary winding is where the energy is being received. Therefore, based on the conservation of power principle, the current direction in the primary winding (I1) must be opposite to the current direction in the secondary winding (I2).

In the case of a forward converter, the current directions may seem to be reversed because the transformer is being used in a different configuration. In this case, the primary winding is still the high voltage side, but it is now the winding that is receiving energy, while the secondary winding is the one supplying energy. This can cause confusion, but the key principle of energy conservation still applies. The current direction in the primary winding (I1) is still opposite to the current direction in the secondary winding (I2).

In summary, the key to determining current flow in an ideal transformer is to understand the conservation of power principle and the dot convention. By keeping these principles