Why is the transformer primary current determined by the secondary side?

The primary current of the transformer is determined by the secondary current: according to the magnetodynamic balance formula, the primary and secondary currents of the transformer are inverted. The magnetodynamic potential generated by the secondary current plays a demagnetizing role in the primary magnetokinetic potential.

i.e. i 1 w 1 12 w 2 . When the secondary current increases, the transformer must maintain the main magnetic flux in the core unchanged, and the primary current must also increase accordingly to balance the production of the secondary current. This is what we can see when the secondary current of the secondary side changes, the current on the primary side is also corresponding, so the current on the primary side is determined by the secondary side.

A transformer is a device that uses the principle of electromagnetic induction to change the alternating voltage, and the main components are the primary coil, the secondary coil and the iron core (magnetic core). The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage regulation (magnetic saturation transformer), etc.

According to the use, it can be divided into: power transformer and special transformer (electric furnace transformer, rectifier transformer, power frequency test transformer, voltage regulator, mining transformer, audio transformer, intermediate frequency transformer, high frequency transformer, impact transformer, instrument transformer, electronic transformer, reactor, transformer, etc.).

When the voltage of the transformer is constant, the power of the electrical appliance becomes larger, and the current will become larger, that is to say, the secondary winding needs to provide a larger current, and the current of the secondary winding is provided by the main winding. In terms of the main winding, the voltage is also constant, so in order to provide more energy to the secondary winding, that is, power, it has to increase the current. The opposite is true.

Therefore, if you want to use the electrical appliances that have been regulated by the transformer, you must pay attention to the output power of the transformer, and it cannot exceed its rated power, otherwise, it will die...

The primary current of the transformer is small, and the secondary current is large, mainly because the resistance is small, the wire diameter is large, and the current is large.

The transformer is also a device that transmits electrical energy while carrying out voltage conversion. The primary current, except for the excitation current, is determined by the power transmitted.

The rated voltage of the primary side U1 refers to the power supply voltage (or input voltage) that should be added to the primary winding, and the rated output voltage of the secondary side U2 usually refers to the open voltage of the secondary winding when the primary side is added to U1.

When using, the primary voltage is not allowed to exceed the rated value (generally the voltage rating is allowed to change by 5%), considering that the transformer has an internal impedance voltage drop during load operation, so the rated output voltage of the secondary side U2 should be 5-10% higher than the rated voltage required by the load, for the load is a fixed power transformer, the rated voltage of the secondary side U2 sometimes refers to the output voltage under the load.

U1 U2 N1 N2 (U1 Primary Voltage, U2 Secondary Voltage, N1 Primary Turns, N2 Secondary Turns Count) The relationship between current and turns (voltage): i1 i2 n2 n1 u2 u1 or: i1 u1 i2 u2 u2 i2 u2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i2 i

P1 P2 (P1 primary power, P2 secondary power).

Dear, I am glad to answer for you the method of determining the voltage of the secondary side of the transformer as follows: the relationship between the voltage and the number of turns of the coil: u1 u2 n1 n2 (u1 primary voltage, u2 secondary voltage, n1 primary turns and n2 secondary turns ) current and turns (voltage) of the current and turns (voltage) of the relationship between the current and the number of turns (voltage).

i1 i2 n2 n1 u2 u1 or: i1 u1 i2 u2 i.e.: p1 p2 (p1 primary power permeability, p2 secondary power).

Will it be ah, I'm in a hurry.

Pro, the first question consists of comparators, resistors, capacitors, and sine waveforms.

What about the second question. Pro, can not be interchangeable between groups, so it is called incomplete interchangeability. Parts that need to be picked or adjusted during assembly are also not fully interchangeable.

If you want to change the amplitude of the equivalent output sine wave, you only need to change the width of each pulse according to the same scale factor.

Next question. If you want to change the amplitude of the equivalent output sine wave, you only need to change the width of each pulse according to the same scale factor, which is the <> of the third question

Hello, the method of calculating the current of the transformer side such as the rock side is: firstly, calculate the current of the main side of the transformer through the transformation coefficient (conversion ratio) of the transformer: i1=v2 v1*i2 where v1 is the voltage of the main side of the transformer, v2 is the voltage of the secondary side of the transformer slag oak, and i2 is the secondary current of the transformer.

Then, calculate the transformer main side current: i1=v1 v2*i2, where v1 is the transformer main side voltage, v2 is the transformer secondary side voltage, and i2 is the transformer secondary side current. Finally, calculate the transformer secondary current:

i2=v2 v1*i1, where v1 is the voltage of the main side of the transformer, v2 is the voltage of the secondary side of the transformer, and i1 is the current of the main side of the transformer.

Hello Ye Sleepy Huai, pro, let the transformer secondary side voltage effective value ruler letter for Songyou U, load resistance for r, then the diode bears the maximum voltage of 2 times the root number of U, the average current is divided by 2r, that is, divided by r, the diode bears the maximum current of 2 times the root number of U divided by r. In this structure, if the same DC voltage is output, the transformer secondary winding only needs half the winding compared to the full-wave rectification, but if the same amount of current is to be output, the wire diameter of the winding should be thickened accordingly. As for the pulsation, it is exactly the same as the full-wave rectifier circuit mentioned earlier.

The relation is l1 l2=(n1) 2 (n2) 2. According to the principle of the transformer, the magnetic flux in the primary and secondary coils is the same, then: the number of turns of the primary magnetic flux and the beat-sensitive coil:

1=φ*n1=l1*i1。The number of turns of the secondary magnetic flux and the coil: 2= *n2=l2*i2.

From the two forms of the upper vertical code: the remaining 1: 2= *n1:

n2=l1*i1：l2*i2，l1：l2=φ*n1*i2：

n2*i1=n1*i2:n2*i1 and because i2:i1=n1:

n2，l1：l2=(n1)^2/(n2)^2。

Because the load current of the secondary side winding must be provided by the primary side, the primary side current is small if the secondary side load is small, and the primary side current is also large if the load is large.

As mentioned upstairs, if the secondary side is not connected to the load, that is, there is no current on the secondary side, the primary side only has the no-load current required by the transformer to establish excitation, which is called "excitation current", which is basically equivalent to the no-load current in the case of the motor without load, and this current value is very small relative to the rated load current value, only a few percent of the rated load current value. When the secondary side is connected to the load, it begins to consume electric energy to produce the secondary current, and the magnetic field line formed by the secondary side current passes through the primary and secondary coils at the same time, and the primary current is induced on the primary side, and the magnitude of the primary current value is determined by the load size of the secondary side; The larger the load on the secondary side, the greater the current on the secondary side, and the greater the current induced on the primary side, so the magnitude of the primary current is determined by the secondary current. Ignoring the no-load loss, then all the electrical power of the primary side is transmitted to the secondary side, ui=ui, u is the rated voltage of the primary side system, and u is the rated voltage of the secondary side system, so i i.

This problem can be talked about from the electromagnetic balance effect of the transformer: when the secondary side of the transformer is open, after the voltage is added to the primary side, a current will be generated, and an alternating magnetic flux will be generated in the core, and this alternating magnetic flux will also induce an electromotive force in the primary coil, and the direction of this electromotive force is opposite to the direction of the input voltage, preventing the current on the primary side from increasing and maintaining a balance, and the current at this time is called "magnetizing current" and also called "no-load current" When the secondary current is connected, The current on the secondary side will produce an alternating magnetic flux opposite to the primary current in the core, which destroys the equilibrium state, and reduces the electromotive force induced by the primary coil, which will increase the current on the primary side, and the increase in current will increase the electromotive force, making up for the alternating magnetic flux opposite to the primary current generated by the current on the secondary side, and reaching a new equilibrium Therefore, the primary current of the transformer is determined by the secondary current (except for the magnetizing current part).

Because supply is determined by demand.