Switching power inverter supplies are widely used in almost all electronic devices due to their small size, light weight and high efficiency. It is an indispensable power supply method for the rapid development of the electronic information industry.
1, should pay attention to when choosing switching power supply
1) Select the appropriate input voltage specifications;
2) Choose the right power. In order to increase the life of the power supply, a model with a maximum output power rating of 30% can be selected.
Switching power supply adapter
3) Consider the load characteristics. If the load is a motor, a bulb or a capacitive load, the current is large when the power is turned on. A suitable power source should be used to avoid overload. If the load is a motor, consider the voltage backflow at shutdown.
4) In addition, it is necessary to consider the working environment temperature of the power inverter supply, and whether there is additional auxiliary heat dissipation equipment. In the case of excessively high temperature, the power supply needs to be derated. The derating curve of the ring temperature to the output power.
5) Select each function according to the application:
Protection functions: over voltage protection (OVP), over temperature protection (OTP), overload protection (OLP), etc.
Application functions: signal function (normal power supply, power failure), remote control function, telemetry function, parallel function, etc.
Special features: power factor correction (PFC), uninterruptible power (UPS)
6) Select the required safety and electromagnetic compatibility (EMC) certification.
2, the use of switching power supply precautions
1) Before using the power supply, first determine whether the input and output voltage specifications match the nominal value of the power supply used;
2) Before power-on, check whether the input and output leads are connected correctly to avoid damage to the user equipment;
3) Check whether the installation is firm, whether the mounting screws are in contact with the power inverter board device, and measure the insulation resistance of the housing and the input and output to avoid electric shock;
4) To ensure the safety of use and reduce interference, please ensure that the grounding terminal is reliably grounded;
5) The power supply of multi-output is generally divided into main and auxiliary outputs, and the main output characteristic is superior to the auxiliary output. Under normal circumstances, the output current is large as the main output. In order to ensure the output load regulation rate and output dynamics and other indicators, it is generally required to have at least 10% load per channel. If the auxiliary road is not used, the main road must be added with a proper dummy load. For details, refer to the specifications of the corresponding model;
6) Please note: Frequent switching of the power supply will affect its life;
7) The working environment and the degree of loading will also affect its life.
3, common faults
Fuse blown
In general, a blown fuse indicates a problem with the internal wiring of the power supply. Due to the high voltage and high current of the power supply, the fluctuations and surges of the power grid voltage will cause the current in the power supply to increase instantaneously and the fuse will be blown. The key points should be to check the rectifier diode of the power input terminal, high-voltage filter electrolytic capacitor, inverter power switch tube, etc., check whether the component has breakdown, open circuit, damage, etc. If the fuse is really blown, you should first check the components on the board to see if the appearance of these components is burnt and there is no electrolyte overflow. If the above is not found, use a multimeter to measure whether the switch has a breakdown short circuit. . It is necessary to pay special attention to: Do ??not directly detect the damage of a component when it is damaged. It is very likely that the other high-voltage components will still be damaged and the replacement components will be damaged. It is necessary to comprehensively apply all the high-voltage components of the above circuit. After the measurement is checked, the fuse blowout can be completely eliminated.
No DC voltage output or unstable voltage output
If the fuse is intact, there is no output of DC voltage at all levels under load. This situation is mainly caused by the following reasons: open circuit, short circuit phenomenon in the power supply, overvoltage, overcurrent protection circuit failure, auxiliary power failure, oscillating circuit not working, power supply overload, rectifier diode in high frequency rectification and filtering circuit It is broken down, the filter capacitor is leaking, and so on. After measuring the secondary component with a multimeter and eliminating the breakdown of the high-frequency rectifier diode and the short-circuit of the load, if the output is zero at this time, it is sure that the control circuit of the power supply has failed. If some of the voltage output indicates that the pre-stage circuit is working properly, the fault is in the high-frequency rectification and filtering circuit. The high-frequency filter circuit mainly consists of a rectifier diode and a low-voltage filter capacitor to form a DC voltage output. The breakdown of the rectifier diode causes the circuit to have no voltage output, and the leakage of the filter capacitor causes the output voltage to be unstable. Statically measure the corresponding component with a multimeter to check the damaged component.
Poor power load capacity
Poor power inverter load capacity is a common fault. It is usually found in old-fashioned or long-running power supplies. The main reason is that the components are aging, the switching tube is unstable, and there is no heat dissipation in time. It is important to check whether the Zener diode is hot or leaky, the rectifier diode is damaged, and the high voltage filter capacitor is damaged.
POWER INVERTER 