US 12,289,074 B2
Back electromotive force sensing circuit, back electromotive force sensing method and driving module of three-phase permanent magnet motor
Zhenfeng Zhong, Hangzhou (CN); Xiaodong Huang, Hangzhou (CN); and Xinjian Huang, Hangzhou (CN)
Assigned to Silergy Semiconductor Technology (Hangzhou) LTD, Hangzhou (CN)
Filed by Silergy Semiconductor Technology (Hangzhou) LTD, Hangzhou (CN)
Filed on Feb. 9, 2023, as Appl. No. 18/107,602.
Claims priority of application No. 202210184110.2 (CN), filed on Feb. 24, 2022.
Prior Publication US 2023/0268854 A1, Aug. 24, 2023
Int. Cl. G11B 19/20 (2006.01); H02P 6/08 (2016.01); H02P 6/182 (2016.01); H02P 27/08 (2006.01)
CPC H02P 6/182 (2013.01) [H02P 6/085 (2013.01); H02P 27/08 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A back electromotive force sensing circuit, comprising:
a) a sampling circuit configured to acquire a sampling signal representing a phase current of one of three phases of a three-phase permanent magnet motor, wherein the three-phase permanent magnet motor adopts sine wave control;
b) a signal processing circuit configured to receive the sampling signal, and to obtain a back electromotive force of the one phase according to a difference between a phase voltage of the one phase and a sum of a voltage across a phase resistor and a voltage across a phase inductor of the one phase; and
c) wherein the signal processing circuit comprises a phase inductor voltage processing circuit configured to discretize a product of the phase inductor and a differential of the sampling signal to obtain the voltage across the phase inductor.
 
3. A back electromotive force sensing circuit, comprising:
a) a sampling circuit configured to acquire a sampling signal representing a phase current of one of three phases of a three-phase permanent magnet motor, wherein the three-phase permanent magnet motor adopts sine wave control;
b) a signal processing circuit configured to receive the sampling signal, and to obtain a back electromotive force of the one phase according to a difference between a phase voltage of the one phase and a sum of a voltage across a phase resistor and a voltage across a phase inductor of the one phase; and
c) wherein the signal processing circuit comprises a phase inductor voltage processing circuit configured to discretize a product of the phase inductor and a differential of the sampling signal, and to perform digital filtering to obtain the voltage across the phase inductor.
 
10. A method of back electromotive force sensing, the method comprising:
a) sampling only one phase current of one of the three phases of three-phase permanent magnet motor, wherein the three-phase permanent magnet motor adopts sine wave control;
b) obtaining a back electromotive force at a current sampling moment according to a difference between a phase voltage at the current sampling moment and a sum of a voltage across a phase resistor of the one phase and a voltage across a phase inductor of the one phase at the current sampling moment;
c) obtaining the phase voltage at the current sampling moment according to a DC bus voltage at the current sampling moment and PWM chopping duty ratios of three-phase bridge arms;
d) obtaining the voltage across the phase resistor of the one phase at the current sampling moment according to the sampling signal of the phase current of the one phase at the current sampling moment and the phase resistor of the one phase; and
e) obtaining the voltage across the phase inductor of the one phase at the current sampling moment according to the sampling signals of the phase current at the current sampling moment and at a last sampling moment and the phase inductor of the one phase.