Three effective methods for heat dissipation of power modules
There are two basic methods for power module energy transfer from high temperature area to low temperature area: radiation and convection.
Radiation: The electromagnetic induction transfer of heat generated between two blocks of different temperatures.
Convection: heat transfer through fluid medium (gas).
In a variety of specific applications, all three methods of heat transfer often have different levels of effect. In most applications, convection is the most critical heat transfer method. If the other two heat dissipation methods are added, the actual effect will be better. However, in some situations, these two methods may also have counterproductive effects. Therefore, when designing a high-quality heat dissipation system, all three heat transfer methods should be carefully considered.
Power module
1. Radiation source heat dissipation
When two interfaces with different temperatures face each other, it will cause continuous radiation transfer of heat.
The final influence of radiation on the temperature of certain objects is determined by many factors: the temperature difference of various components, the orientation of related components, the smoothness of the surface of the components and the distance between them. Because there is no way to quantitatively analyze this element, plus the influence of the surrounding environment's own radiative kinetic energy exchange, it is very complicated to measure the harm of radiation to temperature, and it is difficult to accurately calculate.
In the specific application of the switching power supply converter control module, it is unlikely to rely solely on radiant heat dissipation as the cooling method of the converter. In most cases, the radiant source only dissipates 10% or less of the total heat generation. Therefore, radiant heat is generally only used as an auxiliary method in addition to the key heat dissipation method, and the thermal design plan generally does not consider its effect. The influence of the temperature of the power supply module. In specific applications, the temperature of the general converter control module is higher than the natural ambient temperature. Therefore, the radiant kinetic energy transfer is conducive to heat dissipation. However, under some conditions, the temperature of some heat sources (electronic device boards, high-power resistors, etc.) around the control module is higher than the temperature of the power module, and the radiant heat of these objects will increase the temperature of the control module.
In the heat dissipation design plan, the relative positions of the peripheral components of the converter control module should be arranged scientifically according to the influence that the heat radiation will cause. When the hot components are close to the converter control module, in order to weaken the heating effect of the radiation source, the thin fins of the heat insulation board should be inserted between the control module and the hot components.
2. Convection heat dissipation
Convection heat dissipation is the most commonly used heat dissipation method for Epson power converters. Convection is generally divided into two types: natural convection and forced convection. The transfer of heat from the surface of the hot block to the surrounding static gas with a lower temperature is called natural convection; the transfer of heat from the surface of the hot block to the fluid gas is called forced convection.
The advantages of natural convection are that it is very easy to implement, does not require electric fans, is low in cost, and has high reliability in heat dissipation. However, in contrast to forced convection, in order to achieve the same substrate temperature, a large heat sink is required.
The design of natural convection radiator should also pay attention to the following:
Generally, only the main parameters of the vertical heat sink are given for the heat sink. The actual heat dissipation effect of the horizontal heat sink is weak. If horizontal installation is required, the area of the radiator should be increased appropriately, and forced convection heat dissipation can also be used.
