Could You Explain the Working Principle of a Programmable DC Power Supply?
With the continuous development of various electronic devices, they have higher requirements for DC power supply. Compared to electronic devices, using a single DC power supply cannot meet the power supply requirements, so different DC power supplies are needed to power electronic devices. Programmable DC power supply is one such type. In production testing, the wide range voltage output of programmable DC power supplies is suitable for testing and analyzing the characteristics of components, circuits, modules, and the entire machine. Today, Antai Test will introduce the working principle of programmable DC power supply to you.
Introduction to Programmable DC Power Supply
The non electrostatic force in a programmable DC power supply points from the negative pole to the positive pole. When a programmable DC power supply is connected to an external circuit, a current from the positive pole to the negative pole is formed outside the power supply (external circuit) due to the force of the electric field. In the power supply (internal circuit), the effect of non electrostatic forces causes current to flow from the negative pole to the positive pole, thereby forming a closed cycle of charge flow.
An important characteristic of a programmable DC power supply is its electromotive force, which is equal to the work done by non electrostatic forces when a unit of positive charge moves from the negative pole to the positive pole inside the power supply. When the power supply provides energy to the circuit, the power P provided is equal to the product of the electromotive force E of the power supply and the current I, P=EI. Another characteristic of a power supply is its internal resistance (referred to as internal resistance) R0. When the current passing through the power supply is I, the thermal power lost in the power supply (i.e. the Joule heat generated per unit time) is equal to R0I.
When the positive and negative electrodes of the power supply are not connected, the power supply is in an open circuit state, and the potential difference between the two electrodes of the power supply is equal in magnitude to the electromotive force of the power supply. In an open circuit state, there is no mutual conversion between non electric energy and electric energy. When the load resistor is connected to the two poles of the power supply to form a closed circuit, the current flowing through the power supply flows from the negative pole to the positive pole. At this point, the power EI provided by the power supply is equal to the sum of the power UI (U is the potential difference between the positive and negative poles of the power supply) and the thermal power R0I lost in the internal resistance, EI=UIR0I. Therefore, when the power supply supplies power to the load resistor, the potential difference between the two poles of the power supply is U=E-R0I.
When another power source with a larger electromotive force is connected to a power source with a smaller electromotive force, with the positive pole connected to the positive pole and the negative pole connected to the negative pole (such as using a DC generator to charge a battery pack), current flows from the positive pole to the negative pole in the power source with a smaller electromotive force. At this point, the external input electrical power UI is equal to the sum of the energy EI stored in the power source per unit time and the thermal power R0I lost in the internal resistance, and UI=EIR0I. Therefore, when an external input power supply is applied to the power supply, the external voltage applied between the two poles of the power supply should be U=ER0I.
When the internal resistance of a programmable DC power supply can be ignored, it can be considered that the electromotive force of the power supply is approximately equal in magnitude to the potential difference or voltage between the two poles of the power supply.
In order to obtain higher DC voltage, programmable DC power supplies are often used in series. At this point, the total electromotive force is the sum of the electromotive forces of all power sources, and the total internal resistance is also the sum of the internal resistances of all power sources. Due to the increase in internal resistance, it can only be used in circuits with low current intensity. In order to obtain a larger current intensity, programmable DC power sources with equal electromotive force can be used in parallel. At this time, the total electromotive force is the electromotive force of a single power source, and the total internal resistance is the parallel value of the internal resistance of each power source.
