What are the methods for calculating and testing common mode inductance parameters

Common mode inductance is an inductive element used to suppress common mode interference in circuits, usually made of magnetic materials. The calculation of its parameters involves factors such as inductance, power supply current, load resistance, and output power in the circuit. The following is a brief analysis of the common mode inductance parameter calculation and testing methods for your reference.

Common mode inductance parameter calculation steps

Determine the required common mode inductance value. This depends on the common mode noise capability in the circuit and the amount of common mode noise that needs to be suppressed.

Determine the output power. Measuring the parameters of a common mode inductor requires consideration of the impact of output power on the inductance value. Generally, the output power of a common mode inductor should be the same as the operating frequency of the power supply.

Determine the power supply current and load resistance. These parameters affect the current and power of the common mode inductor.

Calculate the required common mode inductance parameters based on the above parameters. The following formula can be used for calculation:

L = V / (I * f)

Where L is the inductance value of the common mode inductor (in constant units), V is the power supply current (in volts), I is the current of the common mode inductor (in amperes), and F is the output power (in HZ). This formula is only used for single turn coil inductance. If the inductance has multiple turns, it must be calculated using other formulas.

Common Mode Inductance Test Methods

DC resistance test: Use a multimeter or bridge to test the resistance measurement of the inductor. Resistance measurement is an important parameter because it reflects the consumption of inductance and energy conversion efficiency.

Frequency response detection: Apply a signal generator and an oscilloscope to detect the response of the inductance at each frequency. This helps to detect the frequency characteristics of the inductor, such as resonance frequency and quality factor.

Frequency scanning detection: Use a frequency scanner or network analyzer to measure the frequency response of the inductor and generate a corresponding frequency response graph. This helps to check the characteristics of the inductance over the entire frequency range.

Transformer detection: Apply a transformer to detect the turn ratio and mutual inductance value of the inductance. This helps to detect the coupling and conversion efficiency of the inductor.

Transient response detection: Using pulse signals to detect the transient response and frequency characteristics of an inductor. This helps to detect the inductance's ability to suppress temporary noise.

The main purpose of common mode inductance testing is to check whether the inductance performance meets design requirements. During the testing process, the correct testing methods should be followed, and the relevant operating procedures should be strictly implemented.