Mechanism of interior permanent magnet machine initial position detection
AssigneeCaterpillar Inc.
InventorsBaojun Si, Osama Alkhouli
Life of this patent
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Abstract
A system for determining an initial rotor position of an interior permanent magnet (IPM) machine having a rotor and a stator is provided. The system may include a drive circuit in operative and electrical communication with each phase of the IPM machine, and a controller in electrical communication with the drive circuit. The controller may be configured to engage the drive circuit to selectively apply a voltage signal to each phase of the stator of the IPM machine, detect a current signal through each phase corresponding to the applied voltage signal, and calculate the initial rotor position based on a least squares analysis between at least the voltage signal, the current signal and a predefined inductance of the IPM machine.
Claims20
A system for determining an initial rotor position of an interior permanent magnet (IPM) machine having a rotor and a stator, the system comprising:
- a drive circuit in operative and electrical communication with each phase of the IPM machine;
- and
- a controller in electrical communication with the drive circuit, the controller configured to engage the drive circuit to selectively apply a voltage signal to each phase of the stator of the IPM machine, detect a current signal through each phase corresponding to the applied voltage signal, and calculate the initial rotor position based on a least squares analysis between at least the voltage signal, the current signal and a predefined inductance of the IPM machine including both self-inductance and mutual inductance associated with the IPM machine, the controller configured to calculate the initial rotor position based at least partially on the following equation:
- (
- cos
-
-
- 2
-
- θ
- sin
-
-
- 2
-
-
- θ
- )
- =
- (
- H
- H
-
- H
- )
- -
- 1
-
- H
- H
- [
- 1
- j
-
-
- ω
-
- (
- V
- a
- V
- b
- V
- c
- )
- -
- R
- jω
-
- (
- I
- a
- I
- b
- I
- c
- )
- -
- h
- 1
- ]
- .
A method of determining an initial rotor position of an interior permanent magnet (IPM) machine having a rotor and a stator, the method comprising the steps of:
- applying a voltage signal to each phase of the stator of the IPM machine;
- determining a current signal through each phase corresponding to the applied voltage;
- and
- calculating the initial rotor position based on a least squares analysis between at least an amplitude and a phase of each voltage signal, an amplitude and a phase of each current signal, and a predefined inductance of the IPM machine including at least a self-inductance value and a mutual inductance value associated with the IPM machine, the least squares analysis including the following equation:
- (
- cos
-
-
- 2
-
-
- θ
- sin
-
-
- 2
-
-
- θ
- )
- =
- (
- H
- H
-
- H
- )
- -
- 1
-
- H
- H
-
- [
- 1
- j
-
-
- ω
-
- (
- V
- a
- V
- b
- V
- c
- )
- -
- R
- jω
-
- (
- I
- a
- I
- b
- I
- c
- )
- -
- h
- 1
- ]
- .
A method of automatically determining an initial rotor position during startup of an interior permanent magnet (IPM) machine having a rotor and a stator, the method comprising the steps of:
- receiving a sensor signal from a rotor speed sensor indicative of a speed of the rotor relative to the stator to confirm zero rotor speed;
- applying a sinusoidal voltage signal to each phase of the stator of the IPM machine, each voltage signal having a substantially high frequency and a substantially low amplitude;
- detecting a current signal through each phase corresponding to the applied voltage signal;
- determining a relationship between the voltage signal, the current signal and the initial rotor position based on a least squares analysis and a predefined inductance of the IPM machine including at least a self-inductance value and a mutual inductance value associated with the IPM machine, the least squares analysis including the following equation:
- (
- cos
-
-
- 2
-
-
- θ
- sin
-
-
- 2
-
-
- θ
- )
- =
- (
- H
- H
-
- H
- )
- -
- 1
-
- H
- H
-
- [
- 1
- jω
-
- (
- V
- a
- V
- b
- V
- c
- )
- -
- R
- j
-
-
- ω
-
- (
- I
- a
- I
- b
- I
- c
- )
- -
- h
- 1
- ]
- ;
-
- and
- and
- calculating the initial rotor position based on the relationship.
Dependencies are inferred from the claim text.