Fast recovery diode detection method and analysis of fault causes

Fast recovery diode detection method and analysis of fault causes

Fast Recovery Diode (FRD) is a semiconductor diode with good switching characteristics and short reverse recovery time. It is mainly used in electronic circuits such as switching power supplies, PWM pulse width modulators, and frequency converters, as a high-frequency rectifier diode, freewheeling diode, or damping diode. The fast recovery diode adopts gold doping and simple diffusion processes in the manufacturing process, which can achieve high switching speed and high withstand voltage. At present, fast recovery diodes are mainly used as rectifying components in inverter power supplies.

Conventional detection methods for fast recovery diodes

1、 Place the multimeter in the Rx1k range and measure the forward and reverse resistance of the fast recovery diode. The forward resistance is generally a few ohms and the reverse resistance is ∞. If the measured resistance values are ∞ or 0, it indicates that the tested diode is damaged.

2、 The detection method for fast recovery diodes is basically the same as the above method, but it is necessary to first determine which pin their common terminal is, and then use the above method to detect each fast recovery diode.

Quick recovery diode precautions:

1) Some single diodes have three pins, with the middle one being an empty pin, which is usually cut off at the factory, but there are also some that are not cut.

2) If one of the pipes is damaged, it can be used as a single pipe.

3) When measuring the pressure drop of the positive guide, the R × 1 gear must be used. If using the R × 1k gear, the measured VF value will be significantly lower due to the test current being too small, far below the normal operating current of the diode. In the above example, if the R × 1k measurement is selected, the forward resistance is equal to 2.2k Ω, and n '=9 grids. The VF value calculated from this is only 0.27V, much lower than the normal value (0.6V).

Analysis of the causes of fast recovery diode faults

1、 The voltage used is too high, exceeding the reverse breakdown voltage of the fast recovery diode, resulting in breakdown.

2、 Excessive current can cause the current through the fast recovery diode to exceed its rated current for a long time, leading to overheating and burnout, which is a common cause.

3、 Buying low-frequency diodes for use in high-frequency circuits can cause the diodes to overheat and burn out.

4、 The specification and model of the fast recovery diode do not match. When replacing a new diode, mistakenly replacing a diode with parameters that do not meet the requirements or making wiring errors can cause the diode diode to break down and be damaged.

5、 Circuit board short circuit, caused by water after cleaning the circuit board with steam and not drying it out. After cleaning with steam, please blow it again with compressed air before testing to avoid such damage.

The above is the complete content of "Fast Recovery Diode Detection Method and Fault Cause Analysis", hoping to be helpful to everyone.