O que fatores necessidade ser considerado em a seleção de regulado poder fornecimento

For engineers, the selection of switching power supply is a process that needs to be completed every time they plan a power supply. It is a single-choice question on the surface, but before the final selection, engineers need to consider many factors. Of course, we thought of it at the first moment It will be a question of cost. O que I quero explicar em hoje's artigo é isso em o processo de switching power supply selection, in addition to the cost, we need to pay attention to some internal factors in order to choose the most suitable power module.

Regarding the selection of switching power supply modules, we need to pay attention and consider many rules. For example, the nominal value of insurance wire is 1A, which refers to the target at 25 degrees, but if the equipment works at 50 degrees, the nominal value of insurance wire may be lower than 1A, and the design margin at this temperature must be selected Bigger. In the same way, the 1mH of the inductance is not always 1mH, it is at 1kHz, if you use it at 1MHz, the value of the 1mH inductance sent by the processor is not 1mH, because at 1M the inductance coil Distributed capacitance initially plays a big role, which will offset some of the inductance. The insertion loss of the filter IL=25dB is when MHz Rs/RL=50 ohms (source impedance and load impedance), but in practice, it is difficult to achieve the impedance to meet this requirement in our filter application, so 25dB The insertion loss will be greatly reduced. Beads, capacitors, diodes, resistors... all have similar rules. Let's talk about the rules of switching power supply module selection other than cost. There are many topologies of power modules, such as flyback, forward, push-pull, half-bridge, and full-bridge, each of which is superior in certain characteristic indicators because of its different principles.

Aqui nós explicamos o uso regras de vários típicos topológicos estruturas. O primeiro é o flyback power supply. Em um ciclo de o switch, lá está não descarga durante o carregamento período. Porque de esta característica, it é difícil alcançar excelente tempo gestão e ondulação características. Embora it can be alcançado through large energy storage Capacitors help solve it a little, but the principle defect is flawed after all, and the lack of intelligence can be compensated through hard work, but when making up for it and encountering critical problems, it will not be able to super a certain hurdle. Vazamento indutância é também grande e outros problemas, mas suas vantagens são simples circuito, baixo custo, pequeno tamanho, não necessidade para adicionar magnético reset enrolar, e a entrada tensão esquema é relativamente largo. É é precisamente porque de isso isso ela contas para mais que 70 percent de o total energia fornecimento mercado.

Let's talk about the topological structure of other important switching power supplies in the power supply market. The output voltage transient control characteristics of the forward power supply are better, and the load capacity is stronger, but its disadvantages are also obvious. A large energy storage filter inductor and a freewheeling diode are used, the volume is large, and the back electromotive voltage of the primary coil of the transformer is high. The requirements for the switching tube are high (easy to breakdown and damage). The push-pull power supply current transient response speed is very high, and the voltage output characteristics are excellent. Among all topological structures, it is a switching power supply with the highest utilization rate, no magnetic flux leakage, and simple driving circuit. But its disadvantage is that the two switching devices need a high withstand voltage value; there are two sets of primary coils, and the push-pull switching power supply with low power output is a disadvantage. If the two forward converters are not completely symmetrical or balanced, the accumulated bias magnetism after several cycles will make the magnetic core full, resulting in excessive excitation current of the high-frequency transformer, and even damage the switch tube. The output power of the bridge switching power supply is very large, the working power is very high, the withstand voltage value of the switch tube is relatively low, and the primary coil of the transformer only needs one winding. The disadvantage is that the power is low, there will be a semi-conducting region, and the loss is large.

O acima problemas são causados por o inerente vantagens e desvantagens de ses s topológicos estrutura. Embora nós pode considerar o poder módulo as a preto caixa, este é também a ponto devemos prestar atenção a quando escolher a poder suprir. Porque de as soluções que podem realizar a mesma função, um pode ser realizado facilmente, e o outro pode ser realizado com grande esforço.