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EP-4088377-B1 - SENSORLESS POSITION DETECTION FOR ELECTRIC MOTOR

EP4088377B1EP 4088377 B1EP4088377 B1EP 4088377B1EP-4088377-B1

Inventors

  • WANG, RUI
  • HUISMAN, HENDRIK

Dates

Publication Date
20260506
Application Date
20201223

Claims (15)

  1. An apparatus (30) comprising: an electric motor (32) including a stator (34) and a translator (36); a three-phase inverter (38) electrically coupled to the electric motor (32); a power source (40) electrically coupled to the three-phase inverter (38); and a controller (42) communicatively coupled to the three-phase inverter (38), characterized in that the controller (42) is programmed to determine at least three measurements at different times of flux linkage from the electric motor (32); represent the measurements in Clarke coordinates; determine Clarke coordinates of a center of a circle defined by the Clarke coordinates of the measurements; and determine a position of the translator (36) relative to the stator (34) based on the Clarke coordinates of the center of the circle.
  2. The apparatus of claim 1, further comprising a position sensor (56) coupled to the electric motor (32) to detect a position of the translator (36) relative to the stator (34), wherein the controller (42) is further programmed to receive data indicating the position of the translator (36) relative to the stator (34) from the position sensor (56), and provide a warning in response to a difference between the position of the translator (36) from the position sensor (56) and the position of the translator (36) based on the center of the circle exceeding a threshold.
  3. The apparatus of claim 1, wherein the controller (42) is further programmed to charge the power source (40) with power generated by movement of the electric motor (32).
  4. The apparatus of any one of claims 1-3, further comprising a vehicle frame (20) and a wheel assembly (22) movable relative to the vehicle frame (20), wherein the electric motor (32) is coupled to the vehicle frame (20) and to the wheel assembly (22) so that as the wheel assembly (22) moves relative to the vehicle frame (20), the translator (36) moves relative to the stator (34).
  5. A method for controlling an electric motor (32) including a stator (34) and a translator (36), the method comprising: determining at least three flux-linkage measurements at different times from the electric motor (32); representing the flux-linkage measurements in Clarke coordinates; determining Clarke coordinates of a center of a circle defined by the Clarke coordinates of the flux-linkage measurements; and determining a position of the translator (36) relative to the stator (34) based on the Clarke coordinates of the center of the circle.
  6. The method of claim 5, further comprising providing proportional compensation to the center of the circle.
  7. The method of claim 6, further comprising providing integral compensation to the center of the circle.
  8. The method of claim 6, wherein the proportional compensation is further based on a weighting factor, wherein the weighting factor is inversely related to a condition number of a matrix of the measurements of flux linkage.
  9. The method of claim 8, wherein the weighting factor is given by an equation of this form: K R = 1 κ A T A x wherein K R is the weighting factor, κ (.) is the condition number of a matrix, x is a positive number, and the matrix A is given by the following equation: A = ψ α , 1 − ψ α , 2 ψ β , 1 − ψ β , 2 ⋮ ⋮ ψ α , N − 1 − ψ α , N ψ β , N − 1 − ψ β , N wherein ψ α,i is the i th flux-linkage measurement in the alpha dimension in Clarke coordinates, ψ β,i is the i th flux-linkage measurement in the beta dimension in Clarke coordinates, and N is the number of flux-linkage measurements.
  10. The method of claim 6, wherein the proportional compensation forms a feedback loop in which a measured back-emf is proportionally compensated and then, after integration, becomes one of the flux-linkage measurements used to determine the Clarke coordinates of the center of the circle.
  11. The method of claim 5, wherein collecting at least three flux-linkage measurements includes determining at least four flux-linkage measurements, and determining the Clarke coordinates of the center of the circle includes applying least-squares estimation to the Clarke coordinates of the flux-linkage measurements.
  12. The method of claim 11, wherein applying the least-squares estimation includes applying this equation: Ψ c = A † B wherein Ψ c is the center of the circle in Clarke coordinates, A and B are matrices given by the following equations, and the dagger symbol represents the pseudoinverse of a matrix: A = ψ α , 1 − ψ α , 2 ψ β , 1 − ψ β , 2 ⋮ ⋮ ψ α , N − 1 − ψ α , N ψ β , N − 1 − ψ β , N B = 1 2 ψ α , 1 2 − ψ α , 2 2 + ψ β , 1 2 − ψ β , 2 2 ⋮ ψ α , N − 1 2 − ψ α , N 2 + ψ β , N − 1 2 − ψ β , N 2 wherein ψ α,i is the i th flux-linkage measurement in the alpha dimension in Clarke coordinates, ψ β,i is the i th flux-linkage measurement in the beta dimension in Clarke coordinates, and N is the number of flux-linkage measurements.
  13. The method of any one of claims 5-12, further comprising charging a power source (40) with power generated by movement of the electric motor (32).
  14. The method of any one of claims 5-12, further comprising actuating the electric motor (32) based on the position of the translator (36) relative to the stator (34).
  15. A controller (42) comprising a processor and a memory storing instructions executable by the processor to: determine at least three flux-linkage measurements at different times from an electric motor (32), the electric motor (32) including a translator (36) and a stator (34); represent the flux-linkage measurements in Clarke coordinates; determine Clarke coordinates of a center of a circle defined by the Clarke coordinates of the flux-linkage measurements; and determine a position of the translator (36) relative to the stator (34) based on the Clarke coordinates of the center of the circle.

Description

BACKGROUND Vehicles typically include suspension systems. The suspension system of a vehicle is coupled to the vehicle frame and to each wheel assembly. The suspension system absorbs and dampens shocks and vibrations from the wheel assemblies to the vehicle frame. For each wheel assembly, the suspension system includes an upper control arm, a lower control arm, a coil spring, and a shock absorber. The shock absorber extends through the coil spring. One end of the shock absorber and the coil spring may be connected to the lower control arm, and the other end of the shock absorber and the coil spring may be connected to the upper control arm or to the vehicle frame. The shock absorber is typically hydraulic or pneumatic, but the shock absorber can instead be electromagnetic, in which an electric motor serves to absorb and dampen shocks and vibrations transmitted to the wheels by a road surface. US 2016/065109 A1 discloses a position estimation device for estimating a position of a rotator of a motor. The position estimation device includes an estimation unit configured to estimate a rotational position of the rotator of the motor using a magnetic flux estimation value of the motor, which is calculated by inputting an electric voltage instruction value to be inputted to the motor and a coil electric current value detected from the motor into a motor model in which the motor is identified; and a derivation unit configured to derive a magnetic flux deviation amount due to a distortion of a magnetic flux waveform of the motor according to the estimated rotational position. The estimation unit corrects the magnetic flux estimation value based on the derived magnetic flux deviation amount, modifies the estimated rotational position based on the corrected magnetic flux estimation value, and outputs the modified rotational position. CN 104 723 818 B discloses a linear motor shock absorber used for an automobile in-wheel active suspension, and belongs to the technical field of automobile accessories. The linear motor shock absorber mainly comprises a motor shock absorber body, supports, wheels, a passive suspension spring and a passive shock absorber body. The motor shock absorber body is arranged in the wheels through the supports and comprises a peripheral magnetic insulation sleeve, end covers, a rotor, a stator and linear cylindrical slide rails. The stator comprises a cylindrical supporting shaft, annular stator magnetic conduction back iron, annular S-pole permanent magnets and N-pole permanent magnets. The rotor comprises an annular rotor iron core magnetic conductor, winding coils, Hall sensors, annular grooves and rotor teeth. The movable ring structure with the stator on the inner portion and the rotor on the outer portion is adopted for the motor shock absorber body. The rotor can slide up and down along the stator through the cylindrical slide rails. The motor shock absorber body is connected with the passive suspension spring and the passive shock absorber body in parallel, wherein the passive suspension spring and the passive shock absorber body are arranged outside the wheels. The linear motor shock absorber used for the automobile in-wheel active suspension has the advantages that the operation force is adjustable, passive energy recovery is achieved, the size is small, and the stroke is large. US 2011/043145 Al discloses a method of processing a resolver fault in a motor generator unit (MGU). The method includes receiving a position signal from a resolver describing a measured angular position of a rotor of the MGU, determining the presence of the resolver fault using the position signal, and calculating or extrapolating an estimated rotor position when the resolver fault is determined. A predetermined resolver fault state may be determined using a measured duration of the resolver fault, and the MGU may be controlled using the estimated rotor position for at least a portion of the duration of the resolver fault. A motor control circuit is operable for processing the resolver fault using the above method, and may automatically vary a torque output or a pulse-width modulation (PWM) of the MGU depending on the duration of the resolver fault. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an example suspension system.Figure 2 is diagram of an example electric motor.Figure 3 is a circuit diagram of an apparatus including the electric motor.Figure 4 is a feedback block diagram for determining a flux linkage of the electric motor.Figure 5 is a process flow diagram of an example process for determining a center of a flux-linkage circle in Clarke coordinates.Figure 6 is a plot of flux linkage of the electric motor in Clarke coordinates.Figure 7A is a plot showing the flux linkage of the electric motor in the alpha dimension versus time.Figure 7B is a plot showing the flux linkage of the electric motor in the beta dimension versus time.Figure 7C is a plot of a weighting factor for the flux