Heat dissipation principle of high-power DC power supply
In high-power DC power supplies, the main circuit generally uses a thyristor three-phase fully controlled bridge rectifier circuit. The key lies in how to accurately, reliably and stably control the conduction angle of the thyristor. At present, the most common control method in field applications of high-power DC power supplies mostly uses KC or KJ series small-scale integrated circuits, that is, the phase-shifted signal obtained by comparing the three-phase sawtooth wave signal and the DC control signal. However, the slope, duty cycle, amplitude, etc. of the three-phase sawtooth wave signal are closely related to the device parameters of each phase, and small interference in the comparison signal may cause large phase shift errors, so the reliability and automatic balancing capabilities of the circuit are relatively low. Difference.
The high-power DC power supply uses a single-chip microcomputer as the control circuit and directly generates six-phase highly balanced trigger pulses based on the logical relationship between the three-phase fully controlled bridge trigger pulses, which can overcome the shortcomings of poor balance in KC and KJ series circuits. However, since the on-site system works in an environment with severe strong electric interference, in order to reduce the interference, it may cause the program to run disorderly, causing the system to lose control and causing damage to the main circuit components;
In addition, in order to enhance the function of the system, enhance human-computer dialogue capabilities, and realize functions such as display, printing, command input, cycle detection, overvoltage and overcurrent protection, and software PI regulator, dual CPUs must be used to work in parallel. However, dual CPU parallel work not only increases the complexity of the system, but also reduces the reliability and practicality of the system.
The chips of electronic products are highly integrated, with more and more functional requirements and smaller and smaller volume requirements. Today's high-power DC power supplies are rapidly developing towards miniaturization, high functionality and high efficiency. High-performance components will generate a large amount of heat when running at high speeds. This heat must be removed immediately to ensure that the components can operate at maximum efficiency at normal operating temperatures. Therefore, heat conduction related technologies are constantly being challenged with the development of the electronics industry. .
Heat dissipation principle:
The heat dissipation forms of radiators mainly include radiation and convection.
Radiation heat exchange: Heat energy is transmitted in the form of radiation without the aid of any medium and can be transmitted in a vacuum state. For example, the heat energy of the sun is transmitted to the earth through the universe.
Convection heat transfer: The spread of heat energy through air or other media, such as a convection radiator that heats the air. The air heats everything in the room, and the six-unit device mainly relies on air movement to spread heat energy.
In the traditional sense, a radiant radiator refers to a radiator in which the radiant radiator accounts for a relative share of the total heat dissipation. Currently, the most typical radiant radiators are cast iron, steel column radiators, and copper-aluminum composite radiators. Etc., only 30% of the heat energy is transmitted by radiation, and the other 70% of the heat energy is transmitted by convection. The convection radiator is a radiator with basically no radiation heat exchange (or very small), such as a copper tube convection radiator. The copper tube convection radiator uses the principle of light and upward flow of hot air. The air circulation reaches the temperature rise of the whole room. Radiant radiators are more comfortable and heat up faster.
The heat dissipation principle of high-power DC power supply is shared with you here. The high-power DC power supply adopts linear series and thyristor adjustment mode internally. Specifically, it has ultra-high precision, high stability, low ripple coefficient and high anti-interference. It is mainly used in scientific research institutions, laboratories and electronic production lines when high-precision DC stabilized voltage and current power supply testing is required.
