CN103296847A - Bearingless switched reluctance motor and control method thereof - Google Patents

Abstract

The invention provides a bearingless switched reluctance motor and a control method thereof. The difference between a rotor pole arc angle and a stator pole arc angle of the motor is 15 degrees, current of torque windings and suspension windings are controlled to generate suspension force, the current of the torque windings is controlled so as to generate torque, and current of the torque winding of each phase and turn-on and turn-off angle of the torque winding are regulated to achieve a speed closed loop; radial displacement of a rotor is detection, and radial force needed for rotor suspension is outputted via PID (proportion integration differentiation) regulators, so that closed-loop control of radial displacement of the rotor is achieved. The suspension windings are only excited and conducted in a maximum-inductance flat-top area and do not generate torque, so that the torque and the suspension force can be decoupled in control, and current magnitude of the torque windings and the suspension windings is optimized to make copper loss of the windings to be minimum; in addition, counter potential of the suspension windings and the torque windings is zero in the maximum-inductance flat-top area, and high-speed suspended running of the bearingless switched reluctance motor is benefitted so as to give full play to high-speed adaptability of the switched reluctance motor.

Description

A kind of bearing-free switch reluctance motor and control method thereof

Technical field

The invention belongs to the automatic control technology field, particularly a kind of bearing-free switch reluctance motor and control method thereof.

Background technology

Bearing-free switch reluctance motor is divided into double-winding structure and simplex winding structure.The double winding bearing-free switch reluctance motor be will produce the suspending windings of suspending power and switched reluctance machines winding together lap wound on the stator of motor, make motor have rotation simultaneously and from suspending power by controlling two cover winding currents, thereby realize the high-speed cruising of motor.The simplex winding bearing-free switch reluctance motor then is to make it have rotation simultaneously and from suspending power by the every cover winding current of independent control respectively.

Having complicated coupling relation between torque and suspending power, and be difficult in and realize the full decoupled of the two in control strategy and the Mathematical Modeling, is the key factor that the restriction bearing-free switch reluctance motor suspends and runnability is difficult to improve.In addition, in suspending power when control, need be carried out copped wave control to winding current, and during high-speed cruising, the surge of back electromotive force causes and can't winding current be followed the tracks of and copped wave control, electric current namely occurs and cut phenomenon incessantly, this has had a strong impact on the performance of bearing-free switch reluctance motor high speed performance.

Summary of the invention

The present invention is directed to above-mentioned technical problem, propose a kind of bearing-free switch reluctance motor and control method thereof.Described control method is on the basis of polar arc relation between optimal design 12/8 utmost point double winding bearing-free switch reluctance motor stator, rotor, a kind of control method of this motor is proposed, in the hope of utilizing simple control method to solve the problem of suspending power and torque decoupler, and make the copper loss minimum of winding.

The present invention adopts following technical scheme for solving the problems of the technologies described above:

A kind of bearing-free switch reluctance motor comprises stator and rotor, and described stator comprises 12 stator tooths, and described rotor comprises 8 rotor tooths, is wound with a torque winding and a suspending windings on each stator tooth respectively; Wherein the torque winding forward series connection on per 4 stator tooths of 90 ° of being separated by is a phase, and the torque winding of 12 stator tooths constitutes 3 phase torque winding strings; Two suspending windings of every phase are formed by the winding differential concatenation on the relative stator tooth on α direction of principal axis, the β direction of principal axis respectively, and the suspending windings of 12 stator tooths constitutes 6 suspending windings strings of 3 phases; The concrete winding mode of described torque winding and suspending windings is: the torque winding of each stator tooth and suspending windings successively are wound on the stator tooth or torque winding and suspending windings are wrapped on the stator tooth together; Described rotor pole arc angle is bigger 15 ° than stator poles arc angle, forms one 15 ° wide maximum induction flat-top district.

A kind of control method of bearing-free switch reluctance motor, described maximum induction flat-top district is as the excitation conducting region of suspending windings, and every phase suspending windings is only in the excitation conducting of maximum induction flat-top district, and suspension excitation conducting interval is 15 °; During rotor tooth no show maximum induction flat-top district, not conducting of suspending windings, controlling torque winding current controlling torque separately; When rotor tooth arrives maximum induction flat-top district, the suspending windings conducting, the floating winding current of α axle suspension and torque winding current produce the radial suspension force on the α direction jointly, the floating winding current of β axle suspension and torque winding current produce the radial suspension force on the β direction jointly, through the required radial load of PID adjuster output rotor suspension, realize rotor radial displacement closed-loop control by the detection rotor radial displacement; Close angle of rupture realization speed closed loop by regulating every phase torque winding current and opening.

During conducting, described independent controlling torque winding current controlling torque does not adopt chopper current control or PWM control or pulse control to described suspending windings; After the suspending windings conducting, adopt chopper current control, and Current Control is constant, realizes rotor radial displacement closed-loop control.

The invention has the beneficial effects as follows: the present invention proposes a kind of bearing-free switch reluctance motor and control method thereof, the difference of described rotor polar arc angle and stator poles arc angle is 15 °, controlling torque winding and suspending windings electric current produce suspending power, the controlling torque winding current to be producing torque, and regulates every phase torque winding current and open and close the angle of rupture and realize speed closed loop; Through the required radial load of PID adjuster output rotor suspension, realize rotor radial displacement closed-loop control by the detection rotor radial displacement.Suspending windings of the present invention only in the excitation conducting of maximum induction flat-top zone, does not produce torque, so torque and suspending power can realize decoupling zero in control, and makes winding copper loss minimum by the current amplitude of optimal design torque winding, suspending windings; In addition, suspending windings and torque winding are zero at the flat intraparietal back-emf of maximum induction, are conducive to the high speed suspension operation of bearing-free switch reluctance motor, can give full play to the high speed adaptability of switched reluctance machines.

Description of drawings

Fig. 1 is structure and the A phase winding connection diagram of bearing-free switch reluctance motor of the present invention.

Fig. 2 is the winding inductance of bearing-free switch reluctance motor of the present invention and the change curve of current waveform.

Fig. 3 is that the inductance of A phase winding of bearing-free switch reluctance motor of the present invention is with the change curve of rotor position angle.

Fig. 4 is that the α direction suspending power of A phase winding of bearing-free switch reluctance motor of the present invention is with the change curve of rotor position angle.

Fig. 5 is that the torque of A phase winding of bearing-free switch reluctance motor of the present invention is with the change curve of rotor position angle.

Fig. 6 is system's control block diagram of bearing-free switch reluctance motor of the present invention.

Fig. 7 is the control algolithms of two cover winding currents between the floating zone of bearing-free switch reluctance motor of the present invention.

Description of reference numerals: among Fig. 2, the 1st, A phase winding inductance, the 2nd, A phase torque winding current i _Ma, the 3rd, A phase α direction suspending windings current i _Sa1, the 4th, A phase β direction suspending windings current i _Sa1

Embodiment

Below in conjunction with accompanying drawing, further specify a kind of bearing-free switch reluctance motor and control method thereof that the present invention proposes.

As shown in Figure 1, be structure and the A phase winding connection diagram of a kind of bearing-free switch reluctance motor of the present invention, this motor is three-phase 12/8 utmost point double winding bearing-free switch reluctance motor, wherein, and the 1st, stator, the 2nd, rotor, the 3rd, torque winding, the 4th, suspending windings.Its winding connection is: the winding configuration of torque winding and suspending windings all adopts concentrated winding, is wound with a torque winding and a suspending windings on each stator tooth respectively; Torque winding forward series connection on 4 stator tooths of 90 ° of being separated by is a phase, and two suspending windings of every phase are formed by the winding differential concatenation on the relative stator tooth on α direction of principal axis, the β direction of principal axis respectively.I wherein _Sa1+, i _Sa2+ be respectively the electric current that suspending windings on the both direction flows into, i _Sa1-, i _Sa2-Be respectively the electric current that suspending windings flows out on the both direction, i _a+ be the electric current that A phase torque winding flows into, i _A-Be the electric current that A phase torque winding flows out, α, β represent the both direction of rectangular coordinate system.B, C phase winding spatially differ 30 ° and-30 ° with the A phase winding respectively.The rotor pole arc angle of 12/8 electrode structure bearing-free switch reluctance motor and the difference of stator poles arc angle are 15 °.Based on this relation, winding inductance can form one 15 ° wide maximum induction flat-top district, as shown in Figure 3; In maximum induction flat-top district, suspending power is a constant, and torque is zero substantially, respectively as shown in Figure 4 and Figure 5; For this reason, motor of the present invention can structurally be realized the decoupling zero of suspending power and torque.

Suspension and the operation logic of three-phase 12/8 utmost point double winding bearing-free switch reluctance motor of the present invention: setting, rotor tooth aligned position are the zero angle position, are example and operation and the suspension theory that motor of the present invention is described in conjunction with Fig. 2 with the A phase winding.When rotor position angle is in [22.5 ° ,-7.5 °], the conducting of A phase torque winding excitation, not conducting of suspending windings, torque this moment is produced separately by the torque winding current, does not produce suspending power; Rotor position angle is in [7.5 °, 7.5 °] time, suspending windings begins conducting, the conducting still of torque winding this moment, this interval internal torque winding and suspending windings electric current produce suspending power jointly, but do not produce torque, in this interval, winding inductance is maximum and invariable, claim that these 15 ° of maximum induction flat-top districts are suspension excitation interval, and the suspension excitation interval of every phase winding is 15 °.When rotor position angle was in [7.5 °, 7.5 °], α direction suspending power was by torque winding current i _MaWith α direction suspending windings current i _Sa1I is worked as in control _Sa10 o'clock, α positive direction suspending power on the product, on the contrary i worked as _Sa1, produce α negative direction suspending power at＜0 o'clock; In like manner, β direction suspending power is by winding current i _MaWith, β direction suspending windings current i _Sa2I is worked as in control _Sa20 o'clock, β positive direction suspending power on the product, on the contrary i worked as _Sa2, produce β negative direction suspending power at＜0 o'clock; α direction and β direction suspending power can synthesize the suspending power of any direction, therefore by torque winding and two cover suspending windings electric currents, produce the suspending power of any direction and size, and then realize the suspension function certainly of motor.During conducting, method for controlling torque is not identical with the current control method of switched reluctance machines for suspending windings, and concrete current control method is chopper current control or PWM control or pulse control; And after the suspending windings conducting, the current control method of torque winding and suspending windings adopts chopper current control, and Current Control is constant.

The torque winding adopts the power inverter of three-phase asymmetrical half-bridge structure, and suspending windings adopts H bridging parallel operation.

As shown in Figure 2, the zone that the A phase winding produces suspending power is [7.5 °, 7.5 °], at this moment A phase α direction suspending power F _αWith β direction suspending power F _βExpression formula be:

$F_{\mathrm{\α}}=K_f{i}_{\mathrm{ma}}{i}_{\mathrm{sa}1}$

$F_{\mathrm{\β}}=K_f{i}_{\mathrm{ma}}{i}_{\mathrm{sa}2}$

$k_f=\frac{l_{c}r{\mathrm{\&beta;}}_{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA00003192327100011.png,HDA00003192327100012.png"\; state="\{\{state\}\}">s</figure-callout>}}}{2{\mathrm{\&delta;}}^2}{N}_m{N}_b$

In the formula, l _cBe the axial length of cylindrical rotor iron core, r is the cylindrical rotor radius, β _sBe stator polar arc, N _mBe torque umber of turn, N _bBe the suspending windings number of turn, δ is the gas length of cylindrical rotor part, k _fBeing the suspending power coefficient, is the constant relevant with electric machine structure and electromagnetic parameter, i _Ma, i _Sa1, i _Sa2Be respectively A phase torque winding, α direction suspending windings and β direction suspending windings electric current.

Above-mentioned suspending power expression formula shows that suspending power and rotor position angle are irrelevant, so the present invention can realize the decoupling zero control of torque and suspending power.

At suspension excitation stage [7.5 °, 7.5 °], radial suspension force one timing, the copper loss P of A phase torque winding and suspending windings _CuFor:

$R_{\mathrm{cu}}=R_{\mathrm{ma}}{i}_{\mathrm{<figure-callout\; id="2"\; label="ma"\; filenames="HDA00003192327100011.png,HDA00003192327100012.png"\; state="\{\{state\}\}">ma</figure-callout>}}^2+R_{\mathrm{sa}}(i_{\mathrm{sa}1}^2+i_{\mathrm{sa}1}^2)$

$=R_{\mathrm{ma}}{i}_{\mathrm{<figure-callout\; id="2"\; label="ma"\; filenames="HDA00003192327100011.png,HDA00003192327100012.png"\; state="\{\{state\}\}">ma</figure-callout>}}^2+R_{\mathrm{sa}}(F_{\mathrm{\&alpha;}}^2+F_{\mathrm{\&beta;}}^2)/\left(k_f^2{i}_{\mathrm{ma}}^2\right)$

In the formula, R _Ma, R _SaBe respectively the resistance of A phase torque winding and suspending windings.

When therefore the torque winding current satisfies following the relation, the copper loss minimum of winding.The torque winding current is:

$i_{\mathrm{ma}}=[R_{\mathrm{sa}}/R_{\mathrm{ma}}\&CenterDot;(F_{\mathrm{\&alpha;}}^2+F_{\mathrm{\&beta;}}^2)/k_f^2{]}^{\frac{1}{4}}$

At this moment, minimum winding copper loss is:

${\left(P_{\mathrm{cu}}\right)}_{\min }={2R}_{\mathrm{ma}}{i}_{\mathrm{<figure-callout\; id="2"\; label="ma"\; filenames="HDA00003192327100011.png,HDA00003192327100012.png"\; state="\{\{state\}\}">ma</figure-callout>}}^2$

As shown in Figure 2, between the floating zone [7.5 °, 7.5 °], the torque winding is invariable, and the suspending windings electric current all adopts square wave control, and the suspending windings electric current obtains by suspending power computing formula (1)～(9), and then by power inverter tracking realization calculated value, the specific implementation process as shown in Figure 7.

Concrete control system block diagram detects rotor-position by photoelectric sensor and obtains the real-time rotating speed of motor by location compute shown in 6, and the difference of itself and given rotating speed is output as torque winding current i through pi regulator _M1 ^*Two radial displacements are converted to the signal of telecommunication through current vortex sensor, are output as suspending power set-point F through the PID adjuster _α ^*And F _β ^*According to measured value, calculate torque winding current i between the floating zone by the suspension current Control Algorithm _M2 ^*With the suspending windings current i _S1 ^*And i _S2 ^*At last, by the power controller real-time tracking electric current set-point of two cover windings, the stable suspersion during with the operation of realization motor.

Formula table

Annotate: the three-phase distribution formula is formula (1)～(6); Symbolic significance in the above-mentioned formula: F _{A α}---be assigned to suspending power, F on the A phase α axle _{A β}---be assigned to suspending power, F on the A phase β axle _{B α}---be assigned to suspending power, F on the B phase α axle _{B β}---be assigned to suspending power, F on the B phase β axle _{C α}---be assigned to suspending power, F on the C phase α axle _{C β}---be assigned to the suspending power on the C phase β axle.

For those skilled in the art, can be easy to other advantage and distortion of association according to above implementation type.Therefore, the present invention is not limited to above-mentioned instantiation, and it carries out detailed, exemplary explanation as just example to a kind of form of the present invention.In the scope that does not deviate from aim of the present invention, those of ordinary skills replace resulting technical scheme according to above-mentioned instantiation by various being equal to, and all should be included within claim scope of the present invention and the equivalency range thereof.

Claims (3)

1. a bearing-free switch reluctance motor comprises stator and rotor, and described stator comprises 12 stator tooths, and described rotor comprises 8 rotor tooths, is wound with a torque winding and a suspending windings on each stator tooth respectively; Wherein the torque winding forward series connection on per 4 stator tooths of 90 ° of being separated by is a phase, and the torque winding of 12 stator tooths constitutes 3 phase torque winding strings; Two suspending windings of every phase are formed by the winding differential concatenation on the relative stator tooth on α direction of principal axis, the β direction of principal axis respectively, and the suspending windings of 12 stator tooths constitutes 6 suspending windings strings of 3 phases; The concrete winding mode of described torque winding and suspending windings is: the torque winding of each stator tooth and suspending windings successively are wound on the stator tooth or torque winding and suspending windings are wrapped on the stator tooth together; It is characterized in that described rotor pole arc angle is bigger 15 ° than stator poles arc angle, form one 15 ° wide maximum induction flat-top district.

2. control method of bearing-free switch reluctance motor according to claim 1, it is characterized in that, described maximum induction flat-top district is as the excitation conducting region of suspending windings, and every phase suspending windings is only in the excitation conducting of maximum induction flat-top district, and suspension excitation conducting interval is 15 °; During rotor tooth no show maximum induction flat-top district, not conducting of suspending windings, controlling torque winding current controlling torque separately; When rotor tooth arrives maximum induction flat-top district, the suspending windings conducting, the floating winding current of α axle suspension and torque winding current produce the radial suspension force on the α direction jointly, the floating winding current of β axle suspension and torque winding current produce the radial suspension force on the β direction jointly, through the required radial load of PID adjuster output rotor suspension, realize rotor radial displacement closed-loop control by the detection rotor radial displacement; Close angle of rupture realization speed closed loop by regulating every phase torque winding current and opening.

3. want 2 described a kind of bearing-free switch reluctance motor control methods as right, it is characterized in that, during conducting, described independent controlling torque winding current controlling torque does not adopt chopper current control or PWM control or pulse control to suspending windings; After the suspending windings conducting, adopt chopper current control, and Current Control is constant, realizes rotor radial displacement closed-loop control.

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