Rotor and sensorless control method for rotor
Disclosed is a rotor including a sleeve part having a shape corresponding to a cylinder extending in a reference direction, and having an inner hole extending in the reference direction, in an interior thereof, a division part disposed in the inner hole, and dividing the inner hole into a first space and a second space, together with the sleeve part, a first magnet part disposed in the first space, and a second magnet part disposed in the second space, and disposed to have an opposite polarity to that of the first magnet part when viewed along the reference direction.
1. A rotor, comprising:
a sleeve part having a shape corresponding to a cylinder and extending lengthwise in a reference direction, and having an inner hole in an interior thereof and extending in the reference direction;
a division part disposed in the inner hole, and being configured to divide the inner hole into a first space and a second space;
a first magnet part disposed in the first space; and
a second magnet part disposed in the second space,
wherein, when viewed along the reference direction, the second magnet part is disposed to have an opposite polarity to that of the first magnet part.
2. The rotor of claim 1 , wherein the division part further includes:
a first portion extending in the reference direction and having a shape corresponding to a cylinder having a diameter that is smaller than a diameter of the inner hole, the first portion having a hole extending in the reference direction in an interior thereof;
a second portion extending in a first radial direction from a first point at an outer peripheral surface of the first portion; and
a third portion extending in a second radial direction from a second point at the outer peripheral surface of the first portion,
wherein the second radial direction is an opposite direction to the first radial direction.
3. The rotor of claim 2 , wherein the second portion and the third portion contact an inner peripheral surface of the sleeve part and divide the inner hole into the first space and the second space.
4. The rotor of claim 2 , wherein a thickness of the first portion in a radial direction is 0.9 mm to 1.1 mm, and
wherein thicknesses of the second portion and the third portion are 1 mm to 1.5 mm.
5. The rotor of claim 2 , wherein lengths of the first portion, the second portion, and the third portion in the reference direction correspond to each other.
6. The rotor of claim 2 , wherein the division part further includes:
a first division member including a portion of the first portion and the second portion; and
a second division member including remaining portions of the first portion, and the third portion, and
wherein the first division member and the second division member are formed as separate objects.
7. The rotor of claim 6 , wherein the first division member and the second division member have corresponding shapes.
8. The rotor of claim 1 , wherein the division part is configured to divide the inner hole such that shapes of the first space and the second space correspond to each other.
9. The rotor of claim 1 , wherein the first magnet part has a shape corresponding to the shape of the first space, and the second magnet part has a shape corresponding to the shape of the second space.
10. The rotor of claim 1 , wherein lengths of the sleeve part, the division part, the first magnet part, and the second magnet part in the reference direction correspond to each other.
11. A sensorless control method for a rotor, comprising:
providing the rotor of claim 1 ;
injecting a first voltage signal having a first sign;
injecting a second voltage signal having a second sign that is opposite to the first sign; and
estimating a location of the rotor by injecting the first voltage signal and the second voltage signal,
wherein the second voltage signal is a signal that has a frequency that is higher than that of the first voltage signal.
12. The sensorless control method of claim 11 , wherein the injecting of the second voltage signal step further includes:
injecting the second voltage signal to axis d-q of a stationary reference frame.
13. The sensorless control method of claim 11 , wherein the injecting of the second voltage signal step further includes:
injecting a voltage signal having a frequency in a range of 1/20 th to 1/12 th of a sampling frequency.
14. The sensorless control method of claim 11 , further comprising:
extracting a basic wave component current from a measured current signal by using a low pass filter (LPF); and
using a signal acquired by the low pass filter as an input signal of a current controller.
15. The sensorless control method of claim 11 , further comprising:
extracting a current of a high frequency component for estimating the location of the rotor from a measured current signal by using a band pass filter (BPF).
16. The sensorless control method of claim 11 , further comprising:
acquiring a signal including a location estimation error of the rotor by using a heterodyne method.
17. The sensorless control method of claim 16 , further comprising:
eliminating a high frequency component from the signal including the location estimation error of the rotor by using a notch filter; and
estimating the location of the rotor by using a signal acquired by eliminating the high frequency component.
18. The sensorless control method of claim 11 , wherein a calculation time period from a time point of sampling for controlling a current of the rotor to a time point for a pulse width modulation (PWM) update is 25 μs or less.
19. The sensorless control method of claim 18 , further comprising:
operating a location estimation algorithm of the rotor after the PWM update.
20. The sensorless control method of claim 19 , further comprising:
calibrating a sampling time period between an operation time point of the location estimation algorithm and a current control time point using an estimated location of the rotor to the estimated location.