US 11,860,198 B2
Mutual inductance-type current sensing
Andrew Dames, Cambridge (GB); Mark England, Milton (GB); and Joseph Adam, Impington (GB)
Assigned to SENTEC LTD, Cambridge (GB)
Appl. No. 17/295,111
Filed by SENTEC LTD, Cambridge (GB)
PCT Filed Nov. 19, 2019, PCT No. PCT/GB2019/053280
§ 371(c)(1), (2) Date May 19, 2021,
PCT Pub. No. WO2020/104794, PCT Pub. Date May 28, 2020.
Claims priority of application No. 1818835 (GB), filed on Nov. 19, 2018.
Prior Publication US 2022/0018878 A1, Jan. 20, 2022
Int. Cl. H03M 1/10 (2006.01); G01R 15/18 (2006.01); G01R 19/252 (2006.01)
CPC G01R 15/181 (2013.01) [G01R 19/252 (2013.01)] 20 Claims
OG exemplary drawing
 
1. Apparatus comprising:
a mutual inductance current sensor having a first transfer function;
a low-pass filter which receives a signal from the current sensor, the low-pass filter having a second transfer function configured to attenuate one or more harmonic components of the signal;
an analogue-to-digital converter which receives and digitises a filtered signal output from the low-pass filter;
a controller configured to process a digitised signal from the analogue-to-digital converter using a digital processing chain configured to compensate for the frequency and phase responses of the first transfer function and the second transfer function;
wherein the apparatus is for measuring a signal corresponding to an alternating current having a fundamental frequency and wherein the apparatus is configured to measure up to a predetermined harmonic of the fundamental frequency;
wherein the second transfer function of the low-pass filter has a −3 dB corner frequency which lies between the fundamental frequency and the predetermined harmonic.