# US 2026/0074635 A1 · Linear parameter-varying observer for estimating phase current of an electric motor controller

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- Number: US 2026/0074635 A1
- Document ID: US20260074635A1
- Status: Published application
- Kind: A1
- Application number: 19/304,726
- Filed: 2025-08-20
- Published: 2026-03-12
- Earliest claimed: 2024-09-10
- Assignees: NXP B.V.
- Applicants: NXP B.V.
- Inventors: Erik Santiago; Jérôme Dietsch; Bui-Tuan Viet-Long
- Web page: https://patentgrep.com/patent/US20260074635A1

## CPC

- H02P 21/13: Observer control, e.g. using Luenberger observers or Kalman filters
- G01R 31/343: {in operation}
- G01R 35/02: of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
- H02P 21/141: {Flux estimation}
- H02P 21/18: Estimation of position or speed
- H02P 21/22: Current control, e.g. using a current control loop
- H02P 29/024: Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load
- H02P 29/028: the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A linear parameter-varying (LPV) observer for an electric motor controller. The controller includes a control loop with a current sensor that senses phase current signals driving an electric motor and that provides sensed current values used in the control loop. The observer includes an input interface and a processor. The input interface provides a sensed angular speed value, a sensed angular position value, physical parameters of the electric motor, and a pair of control loop control voltages used in the control loop. The processor calculates estimated current values indicative of the sensed current values using the angular speed value, the angular position value, the pair of control voltages, and the electric motor physical parameters. A failure detector may compare the sensed current values with the estimated current values to detect a failure, and substitute the estimated current signals for the sensed current signals when a failure is detected.

## Claims

### Claim 1

A reconfiguration system for an electric motor controller, the electric motor controller including a control loop with a current sensor configured to sense phase current signals driving an electric motor to provide sensed current values used for determining feedback current values that are used to determine control voltages in the control loop for generating the phase current signals, and an angular speed and position sensor that provides angular speed and position information of the electric motor, the reconfiguration system comprising:
a linear parameter-varying (LPV) observer including circuitry, the LPV observer configured to calculate estimated current values using the control voltages and the angular speed and position information; and
a failure detector including circuitry, the failure detector configured to compare the sensed current values with the estimated current values for detecting a failure, and to substitute the estimated current signals for the sensed current signals when a failure is detected.

### Claim 2 (depends on 1)

The reconfiguration system of claim 1, wherein the LPV observer is configured to combine the control voltages and the angular speed and position information with physical constants of the electric motor and gain information to calculate the estimated current values.

### Claim 3 (depends on 1)

The reconfiguration system of claim 1, wherein the physical constants of the electric motor include stator winding resistance, stator winding inductance, flux leakage, inertia of rotor and load, and a coefficient of viscous friction.

### Claim 4 (depends on 1)

The reconfiguration system of claim 1, wherein the electric motor controller includes a Clarke transformation converter including circuitry, the converter configured to convert sensed three-phase currents into the sensed current values comprising αβ-axis stationary stator current values, and wherein the estimated current values comprise estimated αβ-axis stationary stator current values.

### Claim 5 (depends on 1)

The reconfiguration system of claim 1, wherein the failure detector comprises:
adder circuitry configured to determine a residual value between at least one sensed current value and at least one estimated current value;
comparator circuitry configured to compare the residual value with a threshold value to determine an error value; and
selection circuitry configured to select the sensed current values for determining the feedback current values when the error value does not indicate a failure, and to select the estimated current values for determining the feedback current values when the error value indicates a failure.

### Claim 6 (depends on 1)

The reconfiguration system of claim 1, wherein the estimated and sensed current values each comprise αβ-axis stationary stator current values including an α current value and a β current value, and wherein the failure detector comprises:
a first adder configured to subtract an estimated a current value from a sensed α current value to determine an α residual value;
a second adder configured to subtract an estimated β current value from a sensed β current value to determine a β residual value;
a first comparator configured to compare the α residual value with an α threshold value to determine an α error value;
a second comparator configured to compare the β residual value with a β threshold value to determine a β error value; and
selection circuitry configured to select the sensed current values for determining the feedback current values when the α and β error values do not indicate a failure, and to select the estimated current values for determining the feedback current values when either one or both of the α and β error values indicate a failure.

### Claim 7

A method for estimating current values in an electric motor controller including a control loop including a current sensor configured to sense phase current signals driving an electric motor and to provide sensed current values used in the control loop for generating the phase current signals, the method comprising:
receiving, by an input interface including circuitry, a sensed angular speed value, a sensed angular position value, and a plurality of physical parameters of the electric motor;
developing, by the control loop including circuitry, a pair of control voltages; and
calculating, by a linear parameter-varying (LPV) observer including circuitry, estimated current values indicative of the sensed current values using the sensed angular speed value, the sensed angular position value, the pair of control voltages, and the plurality of physical parameters of the electric motor.

### Claim 8 (depends on 7)

The method of claim 7, wherein the calculating by an LPV observer comprises combining the pair of control voltages, the sensed angular speed value, the sensed angular position value, the plurality of physical parameters and gain information to calculate the estimated current values.

### Claim 9 (depends on 7)

The method of claim 7, wherein the receiving comprises receiving a plurality of physical parameters of the electric motor including stator winding resistance, stator winding inductance, flux leakage, inertia of rotor and load, and a coefficient of viscous friction of the electric motor.

### Claim 10 (depends on 7)

The method of claim 7, further comprising:
performing a Clarke transformation to convert sensed three-phase currents into the sensed current values comprising αβ-axis stationary stator current values; and
wherein the calculating estimated current values comprises calculating estimated αβ-axis stationary stator current values.

### Claim 11 (depends on 7)

The method of claim 7, further comprising:
comparing the sensed current values with the estimated current values for detecting a failure; and
substituting the estimated current signals for the sensed current signals when a failure is detected.

### Claim 12

A linear parameter-varying (LPV) observer for an electric motor controller, the electric motor controller including a control loop with a current sensor configured to sense phase current signals driving an electric motor and to provide sensed current values used in the control loop, the LPV observer comprising:
an input interface for providing a sensed angular speed value, a sensed angular position value, and a plurality of physical parameters of the electric motor, and for providing a pair of control voltages in the control loop used for generating the phase current signals; and
an LPV processor including circuitry, the LPV processor configured to calculate estimated current values indicative of the sensed current values using the sensed angular speed value, the sensed angular position value, the pair of control voltages, and the plurality of physical parameters of the electric motor.

### Claim 13 (depends on 12)

The LPV observer of claim 12,
wherein the input interface provides trigonometric angular position values comprising a sine function of the sensed angular position value and a cosine function of the sensed angular position value; and
wherein the plurality of physical parameters of the electric motor includes a stator winding inductance, a stator winding resistance, flux leakage, and inertia of rotor and load.

### Claim 14 (depends on 12)

The LPV observer of claim 12, wherein the LPV processor comprises:
a first adder configured to subtract an estimated angular speed value from the sensed angular speed value and to subtract an estimated angular position value from the sensed angular position value to provide an angular speed and position difference value;
a first gain block configured to combine the angular speed and position difference value with a gain-scheduling value of the angular position using the trigonometric angular position values to calculate a first add value;
a second gain block configured to combine the pair of control voltages with the stator winding inductance to provide a second add value;
a third gain block configured to combine estimated current values with the stator winding inductance and the stator winding resistance to provide a third add value;
a fourth gain block configured to combine the estimated angular speed value with the flux leakage, the stator winding inductance, and the trigonometric angular position values to provide a fourth add value;
at least one second adder configured to add the first add value, the second add value, the third add value, and the fourth add value to provide a derivative of the estimated current values;
a first integrator that integrates the derivative of the estimated current values to provide the estimated current values;
a fifth gain block configured to combine the estimated current values with the flux leakage, the inertia of rotor and load, and the trigonometric angular position values to provide a fifth add value;
a sixth gain block configured to combine the estimated angular speed value with a coefficient of viscous friction and the inertia of rotor and load to provide a sixth add value;
a third adder configured to add the first add value, the fifth add value, and the sixth add value to provide a derivative of the estimated angular speed value; and
a second integrator configured to integrate the derivative of the estimated angular speed value to provide the estimated angular speed value, and a third integrator configured to integrate the estimated angular speed value to provide the estimated angular position value.

### Claim 15 (depends on 14)

The LPV observer of claim 14, wherein the sensed angular speed value is a value ωe, wherein the sensed angular position value is a value θe, wherein the estimated angular speed value is a value {circumflex over (ω)}e, wherein the estimated angular position value is a value {circumflex over (θ)}e, wherein the angular speed and position difference value comprises a value
[
ω
e
-
ω
^
e
θ
e
-
θ
e
ˆ
]
=
Δ
ω
e
,
θ
e
,
wherein the gain-scheduling value is a value K(θe)=K1 sin θe+K2 cos θe+K3 wherein K1, K2, and K3 are gain values, and wherein the first add value comprises a value K(θe) Δωe,θe.

### Claim 16 (depends on 14)

The LPV observer of claim 14, wherein the stator winding inductance is a value Ls, wherein the pair of control voltages comprise values Uα and Uβ in an αβ-axis that are determined by subtracting the feedback current values from reference current values to provide corresponding error values, by applying the error values to proportional-integral controllers to provide stator reference direct and quadrature values, and by performing an inverse Park transformation conversion on the stator reference direct and quadrature values, and wherein the second add value is
1
L
s
[
u
α
(
t
)
u
β
(
t
)
]
.

### Claim 17 (depends on 14)

The LPV observer of claim 14, wherein the stator winding inductance is a value Ls, wherein the stator winding resistance is a value Rs, wherein the estimated current values comprise values îα and îβ, and wherein the third add value comprises a value
R
s
L
s
[
I
^
α
I
^
β
]
.

### Claim 18 (depends on 14)

The LPV observer of claim 14, wherein the estimated angular speed value is a value {circumflex over (ω)}e, wherein flux leakage comprises a value φm, wherein the stator winding inductance is a value Ls, wherein the trigonometric angular position values comprise in θe and cos θe, and wherein the fourth add value comprises a value
p
L
s
⁢
ϕ
m
[
sin
⁢
θ
e
-
cos
⁢
θ
e
]
⁢
ω
ˆ
e
in which p is a poles pair value.

### Claim 19 (depends on 14)

The LPV observer of claim 14, wherein the estimated current values comprise values îα and îβ, wherein flux leakage comprises a value φm, wherein the inertia of rotor and load comprises a value J, wherein the trigonometric angular position values comprise sin θe and cos θe, and wherein the fifth add value comprises a value
-
p
J
⁢
ϕ
m
⁢
sin
⁢
θ
e
⁢
I
^
α
+
p
J
⁢
ϕ
m
⁢
cos
⁢
θ
e
⁢
I
^
β
.

### Claim 20 (depends on 14)

The LPV observer of claim 14, wherein the estimated angular speed value is a value {circumflex over (ω)}e, wherein the coefficient of viscous friction comprises a value Fv, wherein the inertia of rotor and load comprises a value J, and wherein the sixth add value comprises a value
F
v
J
⁢
ω
ˆ
e
.