Working principle and application of module power supply

Aguilera

Working principle and application of module power supply [Copy link]

According to the working state of the adjustment tube, we often divide the voltage-regulated power supply into two categories: linear voltage-regulated power supply and switching voltage-regulated power supply.

　　A linear regulated power supply refers to a regulated power supply in which the regulating tube works in a linear state. However, it is different in a switching power supply. The switching tube (in a switching power supply, we generally call the regulating tube a switching tube) works in two states: on and off: on - very small resistance; off - very large resistance.

　　The switching power supply is a relatively new type of power supply. It has the advantages of high efficiency, light weight, voltage step-up and step-down, and high output power. However, since the circuit works in a switching state, the noise is relatively large. Let's briefly talk about the working principle of the step-down switching power supply. During the switch closing period, the inductor stores energy; during the switch opening period, the inductor releases energy, so the inductor L is called an energy storage inductor. During the switch opening period, the diode D is responsible for providing a current path for the inductor L, so the diode D is called a freewheeling diode.

　　In actual switching power supplies, switch K is replaced by a triode or field effect tube. When the switch is off, the current is very small; when the switch is closed, the voltage is very small, so the heat generation power U×I will be very small. This is why the switching power supply has high efficiency.

　　Now the application of module power supply is analyzed as follows:

　　1. Selection

　　1. When choosing a module power supply, you should first choose the type of power supply reasonably according to the requirements of the application environment, such as voltage accuracy, load type, current range, use environment, etc. Understanding the product use environment and requirements is the premise and condition for the reasonable selection and customization of power supply.

　　2. Module power supply can be single-channel or dual-channel.

　　The performance and indicators of a single-channel power supply are higher than those of a dual-channel power supply, especially the load regulation rate. When the dual-channel power supply is under equal proportional load, the output voltage accuracy is less affected by the load. If the load is skewed, the output voltage accuracy will be greatly affected. Therefore, if the dual-channel output voltage accuracy is required to be higher or the output voltage symmetry is good, two sets of the same single-channel power supply can be used, or a special power supply can be selected to improve the output voltage accuracy. In the power supply controlled by the main and auxiliary circuits, in order to make each auxiliary circuit have corresponding voltage accuracy, the main circuit should have a certain load range (such as ≥10[%] rated load) and attention should be paid when selecting.

　　2. Testing

　　At present, the names of power supply technical indicators given by various manufacturers or power supply technical data, as well as the test methods, are somewhat different, but the principles are the same. The regulations and measurement methods are explained as follows:

　　1. Test environment conditions

　　Unless otherwise specified, the tests are conducted under the following environmental conditions: temperature: 15-35°C, relative humidity: 20%-80%, atmospheric pressure: 86-106Kpa, no strong electromagnetic field interference

　　2. Detailed requirements (under one normal test environment): output voltage accuracy and voltage regulation (voltage stability)

　　3. Application

　　1. Filtering measures are added to the input and output ends of the module power supply, which can generally effectively suppress EMI noise and user surge current from the input side. If the power supply quality is poor or there are more requirements for the power supply system, a filtering network can be added before and after the DC module power supply.

　　2. The polarity of the DC input voltage cannot be reversed, nor can it be used beyond the range, otherwise the DC module power supply will become permanently ineffective.

　　3. When using modular power supply, it is generally best to choose a rated power of 20[%] ~ 80[%], and do not use it beyond the rated power in the later stage, so as not to affect the service life of the power supply.

　　4. When the output current is large, the wire diameter for transmitting the current cannot be too long or too thin to avoid causing large interference and errors.

　　5. For module power supplies with natural heat dissipation, ensure that the ambient temperature does not exceed the given temperature range to avoid overheating and damage.