Patent Application
20130221889
This application claims the benefit of Korean Patent Application No. 10-2012-0018647, filed on Feb. 23, 2012, entitled “Multi-Phase Switched Reluctance Motor Apparatus and Control Method Thereof”, which is hereby incorporated by reference in its entirety into this application.
1. Technical Field
The present invention relates to a multi-phase switched reluctance motor apparatus and a control method thereof.
2. Description of the Related Art
Recently, the demand for a motor has largely increased in various industries such as vehicles, aerospace, military, medical equipment, or the like. In particular, a cost of a motor using a permanent magnet is increased due to the sudden price increase of a rare earth material, such that a switched reluctance motor has again become prominent as a new alternative.
The switched reluctance motor (SRM) has a form in which it does not include a brush and has advantages such as a simple structure, firmness, high efficiency, and a low manufacturing cost, as described in Korean Patent No. 10-0600540 (registered on Jul. 6, 2006). Due to these advantages and the development of a power electronics technology, the SRM has been recently spotlighted significantly. The SRM having a structure in which a stator and a rotor are configured as a double salient pole has a reluctant torque generated depending on a magnetic structure when excitation energy is applied to the stator and has characteristics in which reluctance at a phase at which the excitation energy is applied is minimized.
A design principle of the SRM had a basic form prepared by Byrne, Lawrenson, and the like, and has been arranged by Miller, and the like. According to the prior art, research into a design and driving method of the SRM has been variously reported through several documents. In addition, according to the prior art, a method of finding an optimal geometric shape by a neural network algorithm has been introduced in order to reduce a torque ripple. They were suggested a design method of defining a stator and a rotor, which are mainly geometric parameters, as a design variable for reducing the torque ripple.
However, in the switched reluctance motor according to the prior art, since a torque is not generated in a continuous scheme by a rotor system, but a reluctance torque is used, high torque pulsation is generated, and significant noise and vibration is generated.
The present invention has been made in an effort to provide a multi-phase switched reluctance motor apparatus generating a torque in a multi-phase excitation scheme to reduce torque pulsation, noise, and vibration.
The present invention also has been made in an effort to provide a control method of a multi-phase switched reluctance motor for generating a torque in a multi-phase excitation scheme.
According to a preferred embodiment of the present invention, there is provided a multi-phase switched reluctance motor apparatus including: a multi-phase switched reluctance motor; a position sensing sensor provided at one side of the multi-phase switched reluctance motor; and a controller connected to the multi-phase switched reluctance motor and the position sensing sensor and controlling power in a multi-phase excitation scheme according to a detection angle of the position sensing sensor to supply the power to the multi-phase switched reluctance motor.
The multi-phase switched reluctance motor may include: a rotor formed with a plurality of salient poles protruded along an outer peripheral surface thereof; and a stator rotatably receiving the rotor and including a plurality of phi (π)-shaped stator cores each facing the plurality of salient poles and having a coil wound therearound, and a magnetic path may be formed along the phi shaped stator core and the salient pole facing the phi shaped stator core.
The stator core may include: a yoke; and two stator salient poles protruded from both sides of the yoke so as to face the salient pole, and a cross section of the stator core orthogonal to a shaft may have a phi (π) shape.
The stator may further include an insulating part filled between the plurality of stator cores to fixedly couple the respective stator cores to each other.
The stator may further include a cooling part provided in the insulating part filled between the stator cores in order to radiate heat generated in the motor.
The rotor may include: a rotor core formed with a hollow hole to which a shaft is fixedly coupled; and the salient poles each protruded from an outer peripheral surface of the rotor core so as to face the stator core.
The stator may be provided so that a ratio of the number of stator salient poles to the number of salient poles of the rotor is 12:10.
The controller may be connected to the coils provided to each of the stator cores to control and supply power to at least one of the coils according to a detection rotation angle section of the position sensing sensor.
The position sensing sensor may include any one of an encoder, a resolver, and a potentiometer.
According to another preferred embodiment of the present invention, there is provided a control method of a multi-phase switched reluctance motor apparatus comprising: controlling selectively power using a torque distribution function (TDF) according to the detection rotation angle section of the position sensing sensor; and supplying the power to the multi-phase switched reluctance motor.
The step of supplying the power to the multi-phase switched reluctance motor further comprises: supplying the power to a coil provided to at least one stator core corresponding to a phase having a maximum torque or a minimum torque in each of a plurality of rotation angle sections divided from a rotation angle of a salient pole.
The controller may supply the power to the coil provided to at least one stator core corresponding to the phase having the maximum torque in each of the plurality of divided rotation angle sections when a torque command value (Te*) satisfying a relationship of Te*=Tx*+Ty* is a positive value.
The controller may supply the power to the coil provided to at least one stator core corresponding to the phase having the minimum torque in each of the plurality of divided rotation angle sections when a torque command value (Te*) satisfying a relationship of Te*=Tx*+Ty* is a negative value.
The plurality of divided rotation angle sections may be divided according to the number of salient poles or an advance angle value.
The TDF may be defined as
f
x(θ)=gx2/(gx2+gy2±2gxy√{square root over (gxgy)})
f
y(θ)=gy2/(gx2+gy2±2gxy√{square root over (gxgy)})
with respect to the plurality of stator cores (where gx(θ)≡∂Lx(θ)/∂θ, gy(θ)≡∂Ly(θ)/∂θ, and gxy(θ)≡∂Mxy(θ)/∂θ, L indicates self-inductance, M indicates mutual inductance, and θ indicates a rotation angle of the salient pole).
The control method of a multi-phase switched reluctance motor apparatus according to the preferred embodiment of the present invention may reduce a torque ripple rate (Trip) to ⅓ using the TDF as compared to the single-phase excitation driving method according to the prior art.
The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
The objects, features and advantages of the present invention will be more clearly understood from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant descriptions thereof are omitted. Further, in the following description, the terms “first”, “second”, “one side”, “the other side” and the like are used to differentiate a certain component from other components, but the configuration of such components should not be construed to be limited by the terms. Further, in the description of the present invention, when it is determined that the detailed description of the related art would obscure the gist of the present invention, the description thereof will be omitted.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.
The multi-phase switched reluctance motor apparatus according to the first preferred embodiment of the present invention is configured to include a multi-phase switched reluctance motor, a position sensing sensor 600 provided at one side of the multi-phase switched reluctance motor; and a controller 700 connected to the multi-phase switched reluctance motor and the position sensing sensor 600 and controlling power in a multi-phase excitation scheme according to a detection angle of the position sensing sensor to supply the power to the multi-phase switched reluctance motor.
The multi-phase switched reluctance motor according to the first preferred embodiment of the present invention includes a stator including a plurality of stator cores 100a, 100b, and 100c, and a rotor 200 having a reluctance torque generated due to magnetic force with the stator by a multi-phase excitation control method of the controller to rotate in one direction.
In detail, the rotor 200 includes a rotor core 210 and a plurality of salient poles 220. As shown in
In addition, the multi-phase switched reluctance motor according to the first preferred embodiment of the present invention has a total of ten salient poles 220 protruded from an outer peripheral surface of the rotor core 210 as shown in
In addition, the rotor core 210 and the salient poles 220 are made of a metal material in order to generate the reluctance torque.
The stator includes the plurality of stator cores 100a, 100b, and 100c, an insulating part 140, and a cooling part 150.
In detail, the stator core includes a first stator core 100a, a second stator core 100b, a third stator core 100c, and the respective corresponding stator cores corresponding thereto, and is arranged to have the entire cylindrical shape to thereby rotatably receive the rotor 200 at the center of the arrangement having the cylindrical shape.
Each of the stator cores 100a, 100b, and 100c has the same shape. Typically, the first stator core 100a includes a yoke 110a and a plurality of stator salient poles 120a.
In order for each of these stator cores 100a, 100b, and 100c to configure one phase, for example, the first stator core 100a and another stator core 100a′ may be disposed on the same line so as to face each other.
In detail, the yoke 110a is provided with two stator salient poles 120a, wherein the stator salient poles 120a are protruded inwardly from an inner peripheral surface of the yoke 110a so as to face the salient poles 220.
Therefore, a cross section of the yoke 110a and the stator salient poles 120a orthogonal to the shaft has a phi (π) shape or a Π shape.
According to the first preferred embodiment of the present invention, the plurality of stator cores 100a, 100b, and 100c have a phi (π) shape or a Π shape similar to each other.
In addition, according to the first preferred embodiment of the present invention that is to implement the multi-phase switched reluctance motor operated by a multi-phase excitation control method, a coil 130 to which power is applied from an external controller (not shown) by the multi-phase excitation control method is wound several times around each of the stator salient poles 120a, 120b, and 120c.
Further, the yoke 110a and the stator salient poles 120a are made of a metal material in order to generate the reluctance torque.
Further, as described above, since the multi-phase switched reluctance motor operated by the multi-phase excitation control method according to the first preferred embodiment of the present invention is configured of a three-phase stator core by forming one phase with each of the stator cores facing each of the stator cores 100a, 100b, and 100c so as to correspond to each of the stator cores 100a, 100b, and 100c, the stator includes a total of six stator cores having a phi (π) shape.
Therefore, the total number of stator salient poles 120a, 120b, and 120c is 12. In addition, although the multi-phase switched reluctance motor according to the first preferred embodiment of the present invention includes six stator cores having a phi shape so that a ratio of the number of stator salient poles 120 to the number of salient poles 220 of the rotor 200 is 12:10, the multi-phase switched reluctance motor may also include a plurality of stator cores having a phi shape so that a ratio of the number of stator salient poles to the number of salient poles of the rotor 24:20.
Further, an insulating part 140 is filled between the stator salient poles 120a configuring one stator core 100a and between the stator cores 100a, 100b, and 100c adjacent to each other.
In detail, according to the first preferred embodiment of the present invention, since the stator cores 100a, 100b, and 100c are separated from each other in a segment form, the insulating part 140 is filled in a space among the stator core 100a, the stator core 100b, and the stator core 100c in order to couple the stator cores to each other.
Further, according to the first preferred embodiment of the present invention, in order to block magnetic fluxes from moving among the stator cores 100a, 100b, and 100c, the insulating part 140 may be made of a resin material that is a non-magnetic material and an insulating material.
Therefore, in the case of the multi-phase switched reluctance motor according to the first preferred embodiment of the present invention, only a phi-shaped stator core in which a magnetic flux flows is formed of a metal material and the other portion is formed of an insulating part, thereby making it possible to reduce weight and a manufacturing cost of the stator, as compared to the switched reluctance motor in which the entire stator is made of a metal.
As shown in
In detail, the cooling part 150 may be provided at a center portion of the insulating part 140 so as not to contact the coil 130 wound around the stator cores 100a, 100b, and 100c adjacent to each other.
In addition, the cooling part 150 according to the first preferred embodiment of the present invention may be a water cooling pipe. However, the cooling part 150 according to the first preferred embodiment of the present invention is not limited thereto, but may be a cooling part using other coolants.
Therefore, as shown in
In this case, a magnetic flux flowing in the stator core 100a and the rotor 200 passes through the yoke 110a and two stator salient poles 120a that form a phi (π) shape, and the rotor 200, as shown in
In detail, the magnetic flux flows to one salient pole 220 facing one stator salient pole 120a, passes through the rotor core 210, flows to the other salient pole 220, and then passes through the other stator salient pole 120a.
As described above, in the multi-phase switched reluctance motor according to the first preferred embodiment of the present invention, the magnetic flux flows to the yoke 110a, thereby forming a magnetic flux path shorter than that of the switched reluctance motor according to the prior art.
Therefore, the magnetic flux path is shortened by the stator cores 100a, 100b, and 100c having the phi shape and the rotor 200 facing the stator cores 100a, 100b, and 100c, thereby making it possible to reduce core loss as compared with the switched reluctance motor of the prior art.
In addition, according to the first preferred embodiment of the present invention, only the phi shaped stator core in which the magnetic flux flows is made of a metal material and the other portion is made of an insulating material, thereby making it possible to reduce the weight and the manufacturing cost of the stator, as compared with the switched reluctance motor according to the prior art in which the entire stator is made of a metal.
The multi-phase switched reluctance motor according to the preferred embodiment of the present invention configured as described above includes the position sensing sensor 600 mounted at one side of the shaft and connected to the controller 700. Here, the position sensing sensor 600 is mounted with an encoder, a resolver, a potentiometer, or the like, that is generally used.
The controller 700 controls power according to each divided rotation angle range in a multi-phase excitation scheme to be described using rotation angle information detected through the position sensing sensor 600 to provide the power to the multi-phase switched reluctance motor according to the first preferred embodiment of the present invention.
The controller controls the power in the multi-phase excitation scheme as described above to provide the power, such that the multi-phase switched reluctance motor according to the first preferred embodiment of the present invention may generate a reluctance torque while reducing torque pulsation, noise, and vibration.
Hereinafter, a switched reluctance motor apparatus according to a second preferred embodiment of the present invention will be described with reference to
The multi-phase switched reluctance motor apparatus according to the second preferred embodiment of the present invention is configured to include a multi-phase switched reluctance motor, a position sensing sensor provided at one side of the multi-phase switched reluctance motor; and a controller connected to the multi-phase switched reluctance motor and the position sensing sensor and controlling power in a multi-phase excitation scheme according to a detection angle of the position sensing sensor to supply the power to the multi-phase switched reluctance motor.
In the multi-phase switched reluctance motor according to the second preferred embodiment of the present invention, both ends 330a and 332a of one stator yoke 310a are extended toward ends 332b and 330c of stator yokes adjacent thereto to thereby be coupled to the ends 332b and 330c.
More specifically, at a portion “A” of
In addition, at a portion “B” of
Therefore, as shown in enlarged “A” and “B” of
Therefore, in the case of the multi-phase switched reluctance motor according to the second preferred embodiment of the present invention, since the stator cores may be easily coupled to each other in a process of manufacturing the motor, a yield of assembling may be improved. Further, exchange or repair of the stator core due to damage during an operation of the motor may be facilitated.
Additionally, in the multi-phase switched reluctance motor according to the second preferred embodiment of the present invention, a plurality of blocking holes 340 for blocking a magnetic flux from moving from one stator yoke 310a toward the stator cores 300b and 300c coupled to both sides thereof are formed.
Therefore, as shown in
Further, the magnetic flux entering the yoke 310a from the salient pole 220 via the stator salient pole 320a flows in the blocking hole 340, thereby making it possible to obtain a short magnetic flux path.
Therefore, the multi-phase switched reluctance motor according to the second preferred embodiment of the present invention may shorten the magnetic flux path as compared to the switched reluctance motor according to the prior art and control the power in the multi-phase excitation scheme, thereby making it possible to generate a torque while reducing torque pulsation, noise, and vibration.
Hereinafter, a switched reluctance motor apparatus according to a third preferred embodiment of the present invention will be described with reference to
The multi-phase switched reluctance motor apparatus according to the third preferred embodiment of the present invention is configured to include a multi-phase switched reluctance motor, a position sensing sensor provided at one side of the multi-phase switched reluctance motor; and a controller connected to the multi-phase switched reluctance motor and the position sensing sensor and controlling power in a multi-phase excitation scheme according to a detection angle of the position sensing sensor to supply the power to the multi-phase switched reluctance motor.
As shown in
Therefore, in the multi-phase switched reluctance motor according to the third preferred embodiment of the present invention, a plurality of stator cores 500a, 500b, and 500c having a phi (π) shape may be manufactured integrally with each other.
Hereinafter, a control method of a multi-phase switched reluctance motor apparatus according to a preferred embodiment of the present invention will be described with reference to
In the multi-phase switched reluctance motor capable of being variously implemented according to the first to third preferred embodiment of the present invention, power is selectively applied to the coil provided in at least one of the stator cores related to a corresponding phase according to each divided rotation angle range by the multi-phase excitation control method by the external controller, and the reluctance torque is generated according to a change in magnetic reluctance due to the application of the power.
In the multi-phase excitation control method according to the preferred embodiment of the present invention, a torque command value (Te*) for two phase sections such as a first stator core 100a and a second stator core 100b adjacent to each other among the first stator core 100a, the second stator core 100b, and a third stator core 100c shown in
The torque command value may be the sum of phase torque command values at two phases adjacent to each other, for example, a phase torque command value (Tx*) of the first stator core 100a and a phase torque command value (Ty*) of the second stator core 100b as represented by the following Equation 1.
T
e
*=T
x
*+T
y* [Equation 1]
With respect to Equation 1, in the case in which phase current (ix) applied to the coil 130 provided in the first stator core 100a and phase current (iy) applied to the coil 130 provided in the second stator core 100b are maintained to be tolerance values or less for current command values (ix* and iy*), that is, in the case in which it may be assumed that ix*≈ix and iy*≈iy, Equation 1 may be changed into Equation 2.
T
e*=(1/2)gx(ix*)2+(1/2)gy(iy*)2+gxyix*iy*≈(1/2)gx(ix)2+(1/2)gy(iy)2+gxyixiy≈Te
In the case in which mutual inductance is also considered, a relationship of the following Equation 3 is satisfied.
T
e
=T
x
+T
y
+T
xy
T
x=(1/2)gx(θ)ix2=fx(θ)Te [Equation 3]
T
y=(1/2)gy(θ)iy2=fy(θ)Te
T
xy
=g
xy(θ)ixy=fxy(θ)Te
Where gx(θ)≡∂Lx(θ)/∂θ, gy(θ)≡∂Ly(θ)/∂θ, and gxy(θ)≡∂Mxy(θ)/∂θ, indicates self-inductance, M indicates mutual inductance, and 0 indicates a rotation angle of the salient pole 220.
A torque distribution function (TDF) of fx(θ), fy(θ), and fxy(θ) of Equation 3 satisfies a constrained condition of the following Equation 4.
f
x(θ)+fy(θ)+fxy(θ)=1 [Equation 4]
(0≦fx(θ)≦1, fx(θf)=0,0≦fy(θ)≦2, fy(θi)=0, fy(θf)=1(θi≦θ≦θf))
Although a TDF satisfying the above Equation may be defined in various forms, a TDF represented by the following Equation 5 according to the preferred embodiment of the present invention is defined.
f
x(θ)=gx2/(gx2+gy2±2gxy√{square root over (gxgy)})
f
y(θ)=gy2/(gx2+gy2±2gxy√{square root over (gxgy)}) [Equation 5]
Here, the phase current (ix) applied to the coil 130 provided in the first stator core 100a and the phase current (iy) applied to the coil 130 provided in the second stator core 100b are calculated as represented by the following Equation 6.
The multi-phase excitation control method optimized for this 12/10 multi-phase switched reluctance motor is implemented by dividing a rotation angle range between the salient poles into six angle sections and applying the TDF thereto.
In detail, since the 12/10 multi-phase switched reluctance motor has ten salient poles 220, the multi-phase excitation control method is implemented by uniformly dividing a 36 degree rotation angle region between continuous two salient poles 220 into six divided angle sections and applying to the TDF to each divided angle section.
Therefore, with respect to each of the case in which the torque command value (Te*) is positive and the case in which the torque command value (Te*) is negative, TDFs for each rotation angle section may be arranged as shown in Table 1 and Table 2. Here, the following Table 1 and Table 2 shows the case in which the rotation angle range is uniformly divided into six rotation angle sections by six degrees by way of example, but is not limited thereto. That is, the rotation angle range may also be divided into non-uniform rotation angle sections in consideration of the number of salient poles 220, an advance angle value, or the like, such that the sum of non-uniform rotation angle sections is 36 degrees.
In Table 1 and Table 2, fa indicates a TDF regarding the first stator core 100a, fb indicates a TDF regarding the second stator core 100b, and fc indicates a TDF regarding the third stator core 100c.
Results arranged in Table 1 and Table 2 may be represented by a torque graph shown in
Meanwhile, in the multi-phase excitation control method according to the preferred embodiment of the present invention, when the torque command value (Te*) is negative, the power is applied to the coil of the stator core corresponding to a phase having a minimum torque in each rotation angle section.
In detail,
As shown in
In a section “II”, the power is selectively applied only to a 100a phase, that is, the first stator core 100a, indicating a maximum reluctance torque and a coil 130 of a stator core corresponding thereto to generate the reluctance torque.
In a section “III”, the power is selectively applied only to a (100a+100b) phase, that is, the first stator core 100a and the second stator core 100b, indicating a maximum reluctance torque and each coil 130 of stator cores corresponding thereto to generate the reluctance torque.
In a section “IV”, the power is selectively applied only to a 100b phase, that is, the second stator core 100b, indicating a maximum reluctance torque and a coil 130 of a stator core corresponding thereto, such that current flows in the second stator core 100b and the stator core corresponding thereto as shown in an image on the graph, thereby generating the reluctance torque.
In a section “V”, as shown in
Further, in a section “VI”, as shown in
As described above, in the multi-phase excitation control method according to the preferred embodiment of the present invention, in the case in which the torque command value (Te*) is positive, the power is selectively applied to the coil of the stator core corresponding to a phase having the maximum torque in each rotation angle section as in a portion “C” represented by “o o o o o” of
On the other hand, in the multi-phase excitation control method according to the preferred embodiment of the present invention, in the case in which the torque command value (Te*) is negative, the power is selectively applied to the coil of the stator core corresponding to a phase having the minimum torque in each rotation angle section as in a portion represented by “o o o o o” at a lower portion of
An effect of the multi-phase excitation control method according to the preferred embodiment of the present invention may be compared with that of the single-phase excitation driving method according to the prior art using a torque ripple rate (Trip).
In detail, the torque ripple rate (Trip) is defined as represented by the following Equation 7.
Where Trip indicates a torque ripple rate, Tmax indicates a maximum torque, Tmin indicates a minimum torque, Tave indicates an average torque, and τ indicates an instantaneous torque.
Comparing the multi-phase excitation control method according to the preferred embodiment of the present invention and the single-phase excitation driving method according to the prior art with each other according to Equation 7 related to the torque ripple rate (Trip), in a region “D” represented by “xxxxx” of
Therefore, it could be appreciated that a torque ripple rate (Trip) was reduced by ⅓ or more in the multi-phase excitation control method according to the preferred embodiment of the present invention as compared to the single-phase excitation driving method according to the prior art.
Therefore, the multi-phase excitation control method according to the preferred embodiment of the present invention reduces the torque ripple rate (Trip) as compared to the single-phase excitation driving method according to the prior art, thereby making it possible to reduce the torque pulsation, noise, and vibration.
As set forth above, the multi-phase switched reluctance motor according to the preferred embodiment of the present invention may generate the reluctance torque while reducing the torque pulsation, noise, and vibration.
In addition, the control method of a multi-phase switched reluctance motor apparatus according to the preferred embodiment of the present invention reduces the torque ripple rate to ⅓ as compared to the single-phase excitation driving method according to the prior art, thereby making it possible to reduce the torque pulsation, noise, and vibration.
Although the embodiments of the present invention have been disclosed for illustrative purposes, it will be appreciated that the present invention is not limited thereto, and those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention.
Accordingly, any and all modifications, variations or equivalent arrangements should be considered to be within the scope of the invention, and the detailed scope of the invention will be disclosed by the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2012-0018647 | Feb 2012 | KR | national |
