Modern man is constantly surrounded by a huge amount of electrical equipment, both domestic and industrial. It is difficult to imagine our life without electrical appliances, they quietly penetrated into homes. Even in our pockets there are always several such devices. All this equipment for its stable operation requires an uninterrupted supply of electricity. After all, surges in mains voltage and current most often cause the failure of devices.
To ensure high-quality power supply for technical devices, it is best to use a current stabilizer. He will be able to compensate for network fluctuations and extend the life of the device.
A current stabilizer is a device that automatically maintains consumer current with a given accuracy. It compensates for surges in the frequency of the current in the network, changes in load power and ambient temperature. For example, an increase in the power consumed by the device will lead to a change in the current consumption, which will cause a voltage drop at the source resistance, as well as the wiring resistance. The larger the value of internal resistance, the stronger the voltage will change with increasing load current.
Compensating current stabilizer is a device with automatic regulation, which contains a negative feedback circuit. Stabilization is achieved as a result of changes in the parameters of the regulatory element, in the event of a feedback pulse acting on it. This parameter is called the output current function. By the type of regulation, compensation current stabilizers are: continuous, pulsed and mixed.
Main parameters:
1. The stabilization factor for the input voltage:
To st.t = (∆U in / ∆I H ) * (I H / U in ), where
I n , ∆I n - current value and increment of the current value in the load.
Coefficient K st.t is calculated with a constant load resistance.
2. The value of the stabilization coefficient in the event of a change in resistance :
K R H = (∆R n / R n ) * (I H / ∆I H ) = r i / R H, where
R h , ∆R n - resistance and increment of load resistance;
g i - the value of the internal resistance of the stabilizer.
The coefficient K R H is calculated at a constant input voltage.
3. The value of the temperature coefficient of the stabilizer: γ = ∆I n / ∆t okr.
The energy parameters of stabilizers include the efficiency: η = P o / P in.
Consider some stabilizer circuits.
A very widespread current stabilizer on the field effect transistor, with a shorted gate and source, respectively, U si = 0. A transistor in such a circuit is connected in series with the load resistance. The points of intersection of the direct loads with the output characteristic of the transistor will determine the current value at the lowest and highest input voltage values. When using such a scheme, the load current changes slightly with a significant change in the input voltage.
The pulsed current stabilizer has the distinguishing feature of the operation of a transistor - regulator in a switching state. This allows you to increase the efficiency of the device. Switching current stabilizer is a type of single-phase converter, covered by a negative feedback loop. Such devices, depending on the implementation of the power unit, can be divided into two types: with a serial connection of the inductor and transistor; with series connection of the inductor and parallel connection of the regulating transistor.