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Measurement of Inductance Using Microcontrollers

Technological advances in microcontroller design allow a wide range of electrical inductances to be measured, and most microcontrollers also include auto-ranging capabilities. Inductance readings are reliant on the method of measurement used. Measuring inductance using microcontrollers currently relies upon three methods: the current-voltage method, the bridge and differential method, and the resonance method.

  1. Inductance

    • Inductors are electric circuit elements comprising two- or four-terminal networks that magnetize as current passes through them. Inductance is an electrical parameter with a physical dimension and a reference standard. Its measurement unit is called the Henry (H). All electrical conductors have inductance properties, described as either self-inductance for single conductors, or mutual inductance for more than two conductors.

    Microcontrollers

    • Generally, microcontrollers are multifunctional, universal devices that facilitate either the triggered or cyclic measurement of additional inductive parameters such as resistance, capacitance dissipation and quality factors. They are also operational in digital measuring systems. Microcontrollers contain a zero-out switch that resets the initial conductance capacitance to ensure an accurate final reading, which is displayed on the LCD screen.

    Microcontroller Operation

    • Microcontrollers are optimally designed to reduce error-causing factors in measurement, such as distortions and stray couplings. However, precautions are still needed to prevent additional coupling of the measured inductor to the environment. Ensuring a proper connection between the inductor and the microcontroller, and the right operating frequency is important for accurate readings.

    Methods of Measurement

    • All inductors use the current-voltage method, which is based on the evaluation of either phase angles of impedance or transmittance, using special equations. Bridge and differential methods use selected reference values from a bridge circuit to reduce the differential voltage to zero, which is done automatically or manually. This causes wide frequency bands, small errors and high resolutions. The resonance method involves the application of a series or parallel circuit from a bridge circuit or two-port network.

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