Inductor DC Bias Testing Using an LCR Meter and DC Power Source
Inductor DC Bias Testing Using an LCR Meter and DC Power Source
Until now, DC bias testing has required an external bias circuit with a protective capacitor and coil. Used in conjunction with a DC bias power source from Voltech, the LCR Meter IM3536 makes it easy to perform inductor DC bias testing (DC superposition testing) without a protective capacitor or coil.
Problem
To measure inductance while applying a DC current to a coil, a capacitor is necessary to protect the LCR meter from the DC current. In addition, a coil is necessary to keep the LCR meter’s measurement AC signal from flowing to the DC bias power source. The coil must have an inductance value that is sufficiently large compared to the inductor being measured, and it must be able to withstand the DC bias current being tested; as a result, it's necessary to prepare multiple coils to accommodate various test current values and inductor inductance values.
Solutions
Voltech’s DC1000A DC bias current source eliminates the need for a protective capacitor and incorporates a built-in coil to keep the LCR meter’s measurement AC signal from flowing to the source. With voltage and frequency settings of 1 V and 100 kHz, respectively, the LCR meter can be used to test inductors of up to 790 μH. Hioki performed DC bias testing of a 1 μH chip inductor with this combination of equipment and settings.
Equipment used
LCR Meter: IM3536 HIOKI
DC Bias Current Source: DC1000A Voltech
DUT: Power Inductor: CLF7045T-1R0N-D TDK
Measured data
Hioki performed DC bias testing of an inductor under the following conditions:
·LCR meter measurement signal: V = 1.0 V, 100 kHz
·DC bias current: 0 to 13 A
Actual measurement video
The results closely tracked the catalog specifications of the power inductor CLF7045T-1R0N-D.
"Sequence Maker" for integrated control of measuring instruments
To automate testing by controlling the IM3536 and DC1000A, Hioki used Sequence Maker, an Excel® add-on that provides integrated control of instruments.
