With its modular design, the power module has obvious advantages in troubleshooting.

With its modular design, the power module allows users to minimize the design and development cycle of the product. Its usage is simple, but do you really use the power module? If the power module is used improperly, it will be very destructive. How should we prevent it? This article will be unveiled for you.

The faults of the power module are mainly divided into two categories: parameter exceptions and usage anomalies. The author's previous article "[Engineering Notes] How to quickly locate and troubleshoot power supply modules (Part 1)" has already introduced the reasons for the abnormal power supply parameters and the corresponding solutions. This time, we will analyze the more common power module usage abnormalities. Failure problem. Compared with the parameter anomaly problem, this kind of problem is more destructive. A little poor pool may cause great economic loss. This article will analyze the different anomalies according to the degree of influence from small to large. I hope this article The technical dry goods help the engineer's power module application circuit design. If you encounter it, you can quickly troubleshoot and optimize.

First, the power module is difficult to start

The first is the case of less destructive power - the power module has difficulty starting up during startup and can't even start. During the process of using the power module, there may be a normal voltage at the output of the power module. There is no output at the output, and the power module is not damaged. What is the reason? The specific reasons are as follows:

The external capacitor is too large;

Capacitive load is too large;

The load current is too large;

The input power is not enough.

For this type of problem, you can improve by adjusting the capacitance of the output and the load or adjusting the power of the input, as shown below:

The external capacitor is too large, charging it for a long time when the power module is started, it is difficult to start, and it is necessary to select a suitable capacitive load;

When the capacitive load is too large, it is necessary to connect a suitable inductor first;

If the output load is too heavy, it will cause the startup time to be extended and select the appropriate load.

Switch to a more powerful input power supply.

Second, the module is hot

More serious use anomalies than startup difficulties is that the power module is very hot when it is in use. The root cause of this phenomenon is that the power module has energy loss during the voltage conversion process, and the heat generated by the module causes the module to generate heat and reduce the conversion efficiency of the power supply. This can affect the power module's normal operation and may affect the performance of other nearby devices, which needs to be checked immediately. So under what circumstances will the power module heat up more seriously? The specific reasons are as follows:

Using a linear power module;

Overloaded load;

The load is too small: the load power is less than 10% of the module's power output power, which may cause the module to heat up (the efficiency is too low);

The ambient temperature is too high or the heat is not good.

The heating power module observed by the thermal imager is shown in Figure 1:

Figure 1 Thermal imaging diagram of the power module

For this type of problem, it can be improved by optimizing the external environment or by adjusting the load, as shown below:

Use a heat sink when using a linear power supply;

Increase the load on the power module to ensure a rated load of not less than 10%;

Reduce the ambient temperature and keep the heat dissipation good.

Third, the module power supply is damaged faster

Then, it is more difficult to say that the power module is more serious than the power module. This is that the power module is directly damaged. Then the power module is damaged in a short time, and it is broken in a few days after the replacement. What is the reason? First of all, you need to rule out whether you are using a poor quality power supply. So what other factors can cause this problem? The specific reasons are as follows:

The output load is too light to reduce the reliability;

Excessive capacitance at the output causes damage when the module is started;

The long-term high voltage at the input terminal causes damage to the switch at the input of the module.

Figure 2 Power module is damaged

This type of problem is also caused by load mismatch, which can be improved by changing the output load, capacitance or changing the appropriate input voltage, as follows:

Ensure that the output is not less than 10% of the rated load. If there is no load in the actual circuit operation, connect a dummy load with a rated power of 10% at the output;

Select a capacitor that meets the specifications of the power module technical manual;

Choose the right input voltage.

4. The power module burns quickly after being powered on.

The more terrible situation than the case of the previous power module damage is that not only the power supply is broken but the entire circuit is burnt down. The specific phenomenon is that the power module burns and smokes when it is powered on, and the capacitor at the input end bursts. As shown in Figure 3, this type of problem is the most serious and needs to be avoided in the early design. If this has happened The situation, what is the cause of it? The details are as follows:

Figure 3 Power module burned down

The input voltage polarity is reversed;

The input voltage is much higher than the nominal voltage;

The polarity of the output terminal is reversed;

The output circuit is prone to cause a short circuit or an external load has a large current at the moment of power-on.

This type of problem is the most serious fault, you need to re-examine the circuit to optimize or adjust the voltage, as shown below:

Pay attention to check or add anti-reverse protection circuit before wiring;

Choose the appropriate input voltage;

Check the polarity of the capacitor before power-on to ensure correctness;

Short circuit protection is applied to the output of the power module.

Fifth, select high-quality isolated power modules to reduce the design risk of the circuit

ZLG Zhiyuan Electronics independently develops and produces isolated power modules with wide input voltage range, isolated 1000VDC, 1500VDC, 3000VDC series, various package types, compatible with international standard SIP, DIP and other packages. At the same time, ZLG Zhiyuan Electronics can provide users with professional power supply peripheral application circuit design experience reference based on rich power supply design and application experience to improve product reliability.

ZLG Zhiyuan electronic power module is widely used in power supply and industrial power because it has high efficiency, wide input voltage range, small size, high reliability, good impact resistance, good isolation and wide temperature range. Automation, communications, medical, transportation, building automation, instrumentation and automotive electronics.