US 11,876,477 B2
Position observer for electrical machines
Charles Pollock, Oakham (GB); and Helen Pollock, Oakham (GB)
Assigned to Technelec Ltd, Oakham (GB)
Appl. No. 17/268,586
Filed by Technelec Ltd, Oakham (GB)
PCT Filed Aug. 15, 2019, PCT No. PCT/GB2019/052297
§ 371(c)(1), (2) Date Feb. 15, 2021,
PCT Pub. No. WO2020/035693, PCT Pub. Date Feb. 20, 2020.
Claims priority of application No. 1813335 (GB), filed on Aug. 15, 2018; and application No. 1903255 (GB), filed on Mar. 11, 2019.
Prior Publication US 2021/0351728 A1, Nov. 11, 2021
Int. Cl. H02P 6/18 (2016.01); H02P 6/182 (2016.01); H02P 21/14 (2016.01); H02P 21/18 (2016.01); H02P 21/28 (2016.01); G01R 15/18 (2006.01)
CPC H02P 6/181 (2013.01) [G01R 15/181 (2013.01); H02P 6/182 (2013.01); H02P 21/141 (2013.01); H02P 21/18 (2016.02); H02P 21/28 (2016.02); H02P 2203/05 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A control system for an electrical motor comprising a rotor, a stator having a plurality of phase windings, and an inverter for applying voltage to the plurality of phase windings by connecting individual phase windings to a first or second voltage level, the control system configured:
a) to measure a first rate of change of current in a first phase winding, of said plurality of phase windings, connected to the first voltage level;
b) to measure a second rate of change of current in a second, different phase winding connected to the first voltage level;
c) to calculate a difference between the first and second rate of change of current to obtain a first signal, A;
d) to repeat steps a) to c) for one of (i) the first and a third phase windings or (ii) the second and third phase windings when both phase windings are connected to the same first or second voltage level to obtain a second signal, B;
e) to use the first, second and third signals, A and B, to obtain data related to a position of the rotor and to use the data related to the position of the rotor to determine the position of the rotor relative to the stator;
f) to operate the motor in a low speed regime; and
g) while operating in the low speed regime, to measure a stator current in the phase windings of the stator arising from an application of a stator voltage, and to calculate a motor characteristic of the electrical motor from positions of the rotor, the stator voltage, the stator current, and a resistance of the phase windings.