How to measure the quality of thyristor

Date：2024-03-18 17:04:02Views：39

In the field of power electronics, thyristor is an important control component widely used in various circuits to achieve precise control of voltage and current. With the increase of usage time or the influence of external factors, the performance of thyristor may decrease or be damaged. Therefore, accurately measuring the quality of thyristor is of great significance for ensuring the normal operation of the circuit.

The quality of a thyristor can usually be measured by checking its forward and reverse resistance, triggering characteristics, and switching characteristics. If the forward resistance is small and the reverse resistance is large, and the triggering and switching characteristics are normal, it can be determined that the thyristor is in good condition; On the contrary, if the above characteristics are abnormal, it may indicate that the thyristor is damaged or has poor performance.

Detailed explanation of measurement methods

Measurement of forward and reverse resistance

Firstly, use a multimeter to measure the forward and reverse resistance of the thyristor. Set the multimeter to the resistance range and connect any two poles of the thyristor to the positive and negative probes of the multimeter. Under normal circumstances, the forward resistance of a thyristor (i.e. the resistance between T1-T2 or G-T1 poles) should be small, while the reverse resistance (i.e. the resistance between T1-G or T2-G poles) should be large. If the measured forward resistance is large or the reverse resistance is small, it may indicate that the thyristor is damaged.

Trigger characteristic measurement

The triggering characteristic is one of the important performance indicators of thyristor. In order to measure the triggering characteristics, a simple testing circuit needs to be built, including equipment such as power supply, current limiting resistor, thyristor, and oscilloscope. Connect the G pole (control pole) of the thyristor to a small trigger signal and observe the voltage change between the T1 and T2 poles. Under normal circumstances, when the trigger signal is applied to the G pole, the thyristor should conduct quickly, and the voltage between T1 and T2 poles should decrease rapidly. If the thyristor does not respond or responds slowly after the trigger signal is applied, it may indicate poor triggering characteristics.

Measurement of switch characteristics

Switching characteristics are another important performance indicator of thyristor. When measuring switch characteristics, it is also necessary to build a testing circuit that includes equipment such as power supply, load, thyristor, and oscilloscope. By controlling the application and revocation of trigger signals, observe the changes in the switching state of the thyristor. Under normal circumstances, when a trigger signal is applied, the thyristor should quickly conduct and the load should be powered; When the trigger signal is cancelled, the thyristor should quickly turn off and the load should be powered off. If there are delays, jitters, or incomplete turnoffs in the switching process of thyristor, it may indicate poor switching characteristics.

Measurement precautions

When measuring the quality of thyristor, the following points should be noted:

Ensure the safety of the testing circuit: When building the testing circuit, ensure that the power supply voltage is within the rated voltage range of the thyristor, and set appropriate current limiting resistors to prevent overcurrent damage. Meanwhile, safety should be taken into consideration during the testing process to avoid accidents such as electric shock.

Choose appropriate testing instruments: During the measurement process, high-precision testing instruments such as multimeter and oscilloscope should be used to ensure the accuracy of the measurement results.

Pay attention to the testing environment: The testing environment should be stable to avoid the influence of environmental factors such as temperature and humidity on the measurement results. Meanwhile, external interference such as vibration and impact should be avoided during the testing process.

Correct operation: During the measurement process, it is necessary to strictly follow the testing steps to avoid inaccurate measurement results or equipment damage caused by misoperation.

In summary, through methods such as forward and reverse resistance measurement, trigger characteristic measurement, and switch characteristic measurement, we can accurately judge the quality of thyristor. In practical applications, appropriate measurement methods should be selected based on specific needs and conditions, and relevant safety operating procedures should be followed to ensure the accuracy and safety of measurements. Meanwhile, for damaged or poorly performing thyristors, they should be replaced in a timely manner to ensure the normal operation of the circuit.

With the continuous development of power electronics technology, the application fields of thyristor will become increasingly widespread. Therefore, mastering the measurement methods for its quality is of great significance for power electronics engineers. I hope this article can provide useful references and assistance for readers in practical applications.