CN1354545A - Prime phase wound rotor asynchronous motor with detection winding and cascade speed regulation method thereof - Google Patents

Abstract

The invention relates to a prime phase wound rotor asynchronous motor with a detection winding and a cascade speed regulation method thereof. The rotor of the asynchronous machine has a detection winding and a prime phase main winding. The main winding of the rotor forms a loop by a full-wave rectifier, an LCL low-pass filter and an electronic switch, and the size of the high-frequency on-off duty ratio of the electronic switch and the frequency and the phase of the change of the high-frequency on-off duty ratio are controlled according to signals detected by a secondary detection winding and the main winding, so that stepless speed regulation is realized, and the overload capacity and the rotor power factor are improved. The invention inherits the advantages of the common asynchronous machine and the traditional cascade speed regulation, has simple control and compensation equipment and small power grid pollution, and can be suitable for various loads.

Description

Band detects the prime phase wound-rotor asynchronous motor and the cascade speed control method thereof of winding

The present invention relates to a kind of with the prime phase wound-rotor formula asynchronous motor that detects winding and utilize this motor to realize the method for stepless tandem control.

AC asynchronous motor is most widely used a kind of power source in the modern production life.Why it is used widely, and is because it has numerous significant advantages than other motor.In industrial production, for improve production efficiency and product quality, usually require motor under different rotating speeds, to work, and the shortcoming of asynchronous motor speed adjusting performance difference and power factor are lower exactly, so the manufacturing machine higher to the speed governing performance requirement often used DC motor instead and dragged.In recent years, because the development of pole-amplitude modulation principle and the application of high power semiconductor component, the speed regulating method of asynchronous motor has had very great development, but some problems do not solve so far yet fully.

At present, the speed regulating method of asynchronous motor mainly contains four classes: pole changing, frequency control changes the revolutional slip speed governing, the electromagnetic clutch speed governing.Wherein changing the revolutional slip speed governing has three kinds of methods again, and the first changes supply voltage, and it two is (Wound-rotor type) rotor crosstalk resistances, and it three is tandem controls.Pole changing is a kind of simpler and economic method, not only go for constant torque load but also go for constant power load, but can not realize smooth stepless speed-regulating, generally only be applicable to the squirrel-cage asynchronism machine, and motor size is than big slightly with the common electric machine of capacity, terminal is more, and runnability is also poor slightly.Frequency control is all better from the aspect of performance of speed adjustable range, flatness and speed governing rear motor, but special variable frequency power supply must be arranged, and the more investment of equipment is big, should not safeguard and electrical network is had certain pollution.Change the supply voltage speed governing, not only make the mechanical performance variation of motor, the efficient step-down, and also speed adjustable range is generally little; Rotor series resistance speed, loss are too big, the electric efficiency reduction that is directly proportional with its speed, and speed adjustable range is very little when underloading, crosstalk resistance and change adjusting velocity by voltage and generally be used for chopping mode.The speed adjusting performance of tandem control, runnability and efficient etc. are all better, but will introduce a satisfactory electromotive force, and existing several technical schemes are all complicated, and equipment is also huge; As, common scheme be rotor circuit through over commutation, by inverter direct current is become interchange again, by transformer energy is sent back to electrical network, or directly feeds back to the additional winding (this needs the motor of a kind of being called " internal feedback series speed governing ") in the stator.The electromagnetic clutch speed governing, the rotating shaft of asynchronous machine is made " soft " by electromagnetic clutch and manufacturing machine and is connected, toward the contact negative feedback links that will gather way, though speed adjusting performance and runnability etc. are better, but equipment is complicated, and is not suitable for constant power load.

The objective of the invention is to overcome above-mentioned the deficiencies in the prior art, provide a kind of, and propose to utilize this motor to realize the method for stepless tandem control with the prime phase wound-rotor asynchronous motor that detects winding.Under the situation that does not need complex device, not only kept the plurality of advantages of asynchronous motor, and good speed adjustment features, the power factor height can be applicable to the multiclass load.

Realization of the present invention is according to following principle:

Principle of Electric Engine thinks that three-phase symmetrical alternating current power supply inserts the threephase stator winding of asynchronous motor, has just produced to have synchronous speed n _oRotating magnetic field, thereby induced electromotive force in stator and rotor winding, rotor loop form electric current under the induced electromotive force effect and rotating magnetic field interacts, and produce electromagnetic torque, drive rotor and rotate with asynchronous speed n, electric energy is converted into mechanical energy along the magnetic field direction of rotation.

No matter how the rotating speed of rotor changes the magnetic potential F that stator current produced ₁The magnetic potential F that is produced with rotor current ₂With respect to stator is with same rotating speed rotation, during the motor load operation, and F ₁With F ₂Composite magnetic power ∑ F always equal unloaded magnetic potential F ₀The number of poles of stator winding and rotor winding will equate, but the number of phases can equate or be unequal.

If the voltage of three-phase alternating-current supply (effective value) is U ₁, frequency is f ₁, the induced electromotive force E of stator winding then ₁Induced electromotive force E with the rotor winding ₂₈Size be respectively:

Wherein: W ₁, W ₂---be respectively the number of turn that whenever is in series of stator, rotor winding;

K _Dp1, K _Dp2---be respectively the winding coefficient of stator, rotor winding;

The main magnetic flux of Φ---every utmost point;

S=(n _o-n)/n _o---revolutional slip;

n _o=60f ₁/ p---synchronous speed;

The rotating speed of n---asynchronous motor;

P---number of pole-pairs;

According to the electromagnetic balance of asynchronous motor relation, earlier rotor rotated is converted equivalent motionless rotor, again each physical quantity in the rotor is converted the stator aspect, before at last excitatory branch road being moved, the equivalent circuit that obtains asynchronous motor is as shown in Figure 1.

The fundamental equation group of the electric potential balancing of asynchronous motor and magnetic potential balance is: Wherein: r ₁, r ₂---be respectively the resistance value of stator winding, rotor winding;

x _{σ 1}=2 π f ₁L _{σ 1}---the leakage field induction reactance of stator winding;

x _{σ 2s}=2 π sf ₁L _{σ 2}---the leakage field induction reactance of rotor winding;

L _{σ 1}, L _{σ 2}---be respectively the inductance value of stator, rotor winding leakage flux correspondence;

r _m---the equivalent resistance of loss in the reflection iron core;

x _m---corresponding to the excitatory reactance of main flux Φ;

Z ₁=r ₁+ jx _{σ 1}---be called the impedance of stator winding;

Z ₂=r ₂+ jx _{σ 2s}---be called the impedance of rotor winding;

Z _m=r _m+ jx _m---be called excitatory impedance;

K _s=l+Z ₁/ Z _m---be called excitatory branch road and move preceding correction factor;

I ₂---flow through the electric current of rotor winding;

I ₂'=I ₂/ K _i---the electric current after the conversion of rotor winding;

E ₂'=K _uE ₂---the induced potential after the conversion of rotor winding;

r ₂'=Kr ₂---the resistance after the rotor conversion;

x _{σ 2}'=Kx _{σ 2}=Kx _{σ 2s}/ s---the leakage field induction reactance after the rotor conversion;

K _i=m ₁W ₁K _Dp1/ m ₂W ₂K _Dp2---the electrorheological ratio;

K _u=W ₁K _Dp1/ W ₂K _Dp2---voltage change ratio;

K=K _iK _u---the resistance conversion factor;

m ₁, m ₂---be respectively the number of phases of stator winding, rotor winding;

Above-mentioned parameter is definite value for Manufactured asynchronous machine, can be by experiment or Calculation Method obtain.

The electromagnetic torque M of asynchronous motor has two kinds of expression formulas: one, M=C _M1Φ I ₂' cos φ ₂=C _M2Φ I ₂Cos φ ₂(3)

C _M1＝4.44?m ₁pW ₁K _dp1/2π

C _M2=4.44m ₂PW ₂K _Dp2/ 2 π cos φ ₂Be the power factor of rotor winding, $\cos {\mathrm{\φ}}_2=r_2/\sqrt{{r_2}^2+{x_{\mathrm{\σ}2s}}^2}$ $={r_2}^{\′}/\sqrt{{r_2}^{\′2}+{\left({{\mathrm{SX}}_{\mathrm{\σ}2}}^{\′}\right)}^2}$ Its two, $M\≈\frac{m_{1}p{U_1}^2{r_2}^{\′}/s}{2\mathrm{\π}{f}_1\·\[{(r_1+{r_2}^{\′}/s)}^2+{(x_{\mathrm{\σ}1}+{x_{\mathrm{\σ}2}}^{\′})}^2\]}----\left(4\right)$

Can provide the mechanical characteristic (M-S curve) of asynchronous motor according to (4) formula, as shown in Figure 2.Under electric motor state, 0＜s＜1.s _eBe rated slip, generally 0.015～0.05; s _mBe the revolutional slip of breakdown torque, generally 0.1～0.2; M _eBe nominal torque; M _MaxBe breakdown torque; M _StBe starting torque.Can be by (4) formula in the hope of the M of asynchronous motor _MaxAnd s _m: $M_{\max }=\frac{m_{1}p{U_1}^2}{4\mathrm{\π}{f}_1\·\[r_1+\sqrt{{r_1}^2+{(x_{\mathrm{\σ}1}+{x_{\mathrm{\σ}2}}^{\′})}^2\]}}$ $\left(5\right)s_m\frac{{r_2}^{\′}}{\sqrt{{r_1}^2+{(x_{\mathrm{\σ}1}+{x_{\mathrm{\σ}2}}^{\′})}^2}}$

National Specification, the overload capacity K of common threephase asynchronous _m(=M _Max/ M _e) be 1.8～2.2, general squirrel-cage asynchronism machine M _St/ M _e=1.0～1.8.

So-called tandem control is exactly to introduce an electromotive force in (Wound-rotor type) rotor loop of asynchronous motor, to regulate its rotating speed.The frequency of introducing electromotive force is identical with the rotor induced electromotive force, phase place can with rotor induced electromotive force homophase or anti-phase; When anti-phase, rotor current reduces (according to (3) formula), and torque reduces, and (by (4) formula as seen) rotating speed reduces; Otherwise then with phase time.

On the basis of above-mentioned principle, can develop and improve existing tandem control theory.

If in rotor loop, introduce " feedback electromotive force " E identical with rotor induced electromotive force frequency _f, its internal impedance is Z _fAccording to second formula in the fundamental equation group (2), rotor current becomes: $I_{2\mathrm{\Σ}}=\frac{E_{2s}+E_f}{(r_2+{\mathrm{jx}}_{\mathrm{\σ}2s})+Z_f}=\frac{E_{2s}+E_f}{Z_2+Z_f}----\left(6\right)$ If rotor current I _{2 ∑s}With rotor induced electromotive force E _2sHomophase, the power factor of rotor just brings up to 1 so, and I _{2 ∑s}Size variation, the rotating speed of motor also changes thereupon.Like this, by regulating " feedback electromotive force " E that is introduced _fAmplitude and phase place, both can speed governing, can improve the power factor of rotor again.

The power factor of rotor already brings up to 1, then by equivalent circuit shown in Figure 1 as seen, only needs at supply voltage U ₁Input capacitor C in parallel _m, make C _mWith move before equivalent excitatory branch road (Z _m+ Z ₁), at supply frequency f ₁Be in the parallel resonance state, just can make the total power factor of asynchronous motor bring up to 1.Because for the asynchronous machine that has manufactured, (Z _m+ Z ₁) be definite value, so capacitor C in parallel _mAlso be definite value, needn't change, make circuit simple with rotating speed.

Introduce " feedback electromotive force " E _f(and internal impedance Z _f) after, rotor current I _{2 ∑s}Reduce and with rotor induced electromotive force E _2sHomophase, this is equivalent to the leakage field induction reactance x of rotor _{σ 2s}Being cancelled is 0, and rotor resistance r ₂Be superimposed with a resistance value (in fact this resistance value does not consume active power) again, by (5) formula as seen, the breakdown torque M of asynchronous motor _MaxWith pairing revolutional slip s _mAll increase, so when reducing rotating speed, can also improve its overload capacity.

Introduce " feedback electromotive force " E _fAfter, if make rotor current I _{2 ∑s}With rotor induced electromotive force E _2sHomophase, then according to (3) formula, asynchronous machine produces the required rotor current I of torque M _{2 ∑s}Size is: $I_{2\mathrm{\Σ}}=\frac{M}{C_{M2}\·\mathrm{\Φ}}----\left(7\right)$ Simultaneous (6), (7) formula are tried to achieve: $E_f=\frac{M\·(Z_2+Z_f)}{C_{M2}\·\mathrm{\Φ}}-{\mathrm{sE}}_2----\left(8\right)$ Thereby,, can obtain " feedback electromotive force " E of required introducing by (8) formula according to the torque M and the revolutional slip s of the required output of motor _fAmplitude and phase place.

How in rotor loop, to introduce required " feedback electromotive force " E _f? a kind of outstanding technical scheme is proposed below.

As shown in Figure 3, m ₂Phase (m ₂Be prime number) full-wave rectification of rotor circuit process, the pulsating dc voltage E when obtaining opening a way _2d, by the visible E of waveform _2dHave periodically, frequency is 2 m ₂f ₂According to rectification theory, ω t is at interval [pi/2 m ₂, pi/2 m ₂] in, E _2dExpression formula be: $E_{2d}=2\sqrt{2}\cos ((m_2-1)\mathrm{\π}/{2m}_2)\·E_{2s}\·\cos \mathrm{\ωt}----\left(9\right)$ Wherein, ω=2m ₂ω ₂, ω ₂=2 π f ₂

According to the Dai Weinan equivalent theorem, the circuit of Fig. 3 can equivalence become a voltage source, as shown in Figure 4.The electromotive force of this voltage source is E _2d, equivalent internal resistance is anti-to be Z _s, as asynchronous machine rotor m ₂During the phase winding symmetry,

Z _s=r _s+ j ω L _s=(r ₂+ j ω L _{σ 2})/m ₂(10) because E _2dPulsation amplitude, frequency and phase place, reflecting rotor induced electromotive force E _2sAmplitude, frequency and phase place, therefore, as long as introduce " feedback electromotive force " E of a pulsation _Fd(and internal impedance Z _Fd), the pulsating direct current electric current I that its ripple frequency and phase place make rectification output _{2 ∑ d}With E _2dHomophase has also just guaranteed rotor current I _{2 ∑s}With rotor induced electromotive force E _2sHomophase; Regulate E _FdAmplitude, then regulated the rotating speed of asynchronous machine.

With E _2dThe form of being write as Fourier series is: $E_{2d}=E_{2\mathrm{do}}\·\[1-\underset{k=1}{\overset{\∞}{\mathrm{\Σ}}}\frac{2\cos \mathrm{k\π}}{{\left({2m}_{2}k\right)}^2-1}\·\cos \left({2m}_{2}k{\mathrm{\ω}}_{2}t\right)\]----\left(11\right)$

Wherein, $E_{2\mathrm{do}}=2\sqrt{2}{E}_{2s}\·(m_2/\mathrm{\π})\·\sin (\mathrm{\π}/m_2)(m_2\≥2)$ E _2doBe E _2dMean value be DC component.Different number of phases m ₂The time, E _2dDC component E _2do, ripple coefficient of voltage γ _u, the mains ripple coefficient S _uBe listed as follows:

????m 2	????2	????3	????5	????7
					????E 2do	????1.80E 2s	????2.34E 2s	????2.65E 2s	????2.73E 2s
????γ u％	????9.77	????4.18	????1.49	????0.75
					????S u％	????13.3	????5.71	????2.02	????1.03

If the output at Fig. 3 circuit inserts "T"-shaped LCL low pass filter and high-speed high-power electronic switch SW, as shown in Figure 5.0 over the ground the voltage of setting up an office is E ₀, inductor L ₁, L ₂With capacitor C ₁, C ₂Impedance be respectively Z _L1, Z _L2, Z _C1, Z _C2

(12)Z _L1＝r _L1+jωL ₁；Z _L2＝r _L2+jωL ₂

Z _C1=1/j ω C ₁Z _C2=1/j ω C ₂₂Wherein, r _L1, r _L2Be respectively inductor L ₁, L ₂Coil resistance.Then when switch SW is connected, E ₀=0; When switch SW disconnects, $E_0=\frac{Z_{C1}//(Z_{C2}+Z_{L2})}{Z_s+Z_{L1}+Z_{C1}//(Z_{C2}+Z_{L2})}\·\frac{Z_{C2}}{Z_{C2}+Z_{L2}}\·E_{2d}=\frac{E_{2d}}{G}---\left(13\right)$ $G=1+\frac{Z_s+Z_{L1}+Z_{L2}}{Z_{C2}}+\frac{Z_s+Z_{L1}}{Z_{C1}}+\frac{(Z_s+Z_{L1})Z_{L2}}{Z_{C1}{Z}_{C2}}$ Wherein, " ∥ " is operator in parallel.According to the substitution theorem of network theory, along with the break-make of switch SW, the part in Fig. 5 frame of broken lines 2, an available ideal voltage source (internal impedance is 0 electromotive force) is replaced, and the voltage of this voltage source is:

With E _2dExpression formula (11) substitution (14) formula, utilize superposition theorem can try to achieve E ₀

E ₀Through L ₂, C ₁, L ₁Behind the low pass filter that constitutes, introduce pulsation " feedback electromotive force " E of an equivalence for the rotor rectification circuit _Fd, according to equivalent source theorem, its internal impedance Z _Fd=Z _L1+ Z _L2∥ Z _C1E _FdInstantaneous value is recently controlled by the instantaneous duty of switch SW break-make, and the trigger impulse of switch SW can adopt to change pulse width type or change frequency type, and pulse frequency can be selected in several thousand Hz～tens Hz scopes and change.The angular frequency of the instantaneous change in duty cycle of trigger impulse should be (2m ₂ω ₂), it has determined E _FdRipple frequency and E _2dIdentical; The size of the instantaneous duty ratio of trigger impulse and phase decision E _FdAmplitude and phase place.Therefore,, control frequency, phase place and the size of the instantaneous change in duty cycle of trigger impulse in real time, both can make rotor current I by certain FEEDBACK CONTROL rule _{2 ∑s}With rotor induced electromotive force E _2sHomophase again can real time altering I _{2 ∑s}Size.In fact, with E _2dThe rotor pulsating direct current electric current I of homophase _{2 ∑ d}Can try to achieve by the following formula integration: $I_{2\mathrm{\Σd}}\left(t\right)=f_r\·\[{\∫}_t^{t+\mathrm{\τ}}\frac{E_{2d}}{Z_s+Z_{L1}+Z_{C1}//Z_{L2}}\mathrm{dt}+{\∫}_{t+\mathrm{\τ}}^{t+T}\frac{E_{2d}}{Z_s+Z_{L1}+Z_{C1}//(Z_{L2}+Z_{C2})}\mathrm{dt}\]--\left(15\right)$ Wherein, f _TBe the break-make frequency of switch SW, τ is the time that switch SW is connected.Below with I _{2 ∑ d}Carry out discretization.Order: ${\{}_{Z_D=Z_s+Z_{L1}+Z_{C1}//(Z_{L2}+Z_{C2})=r_D+j{X}_D}^{Z_T=Z_s+Z_{L1}+Z_{C1}//Z_{L2}=r_T+j{X}_T}$ Then: $I_{2\mathrm{\Σd}}\left(\mathrm{kT}\right)=f_T\·\[{\∫}_{\mathrm{kT}}^{\mathrm{kT}+\mathrm{\τ}}\frac{E_{2d}}{Z_T}\mathrm{dt}+{\∫}_{\mathrm{kT}+\mathrm{\τ}}^{(k+1)T}\frac{E_{2d}}{Z_D}\mathrm{dt}\]$

K=0,1,2 ... get: E _2d≈ E _2do+ E _2d1 $E_{2d1}=\frac{2}{{4m}_2^2-1}\·\cos \left({2m}_2{\mathrm{\ω}}_{2}t\right);$

$A_1=\frac{2}{({4m}_2^2-1)\·\left|Z_T\right|};A_2=\frac{2}{({4m}_2^2-1)\·\left|Z_D\right|}$

$\≈\frac{E_{2\mathrm{do}}\·\mathrm{\τ}}{(r_s+r_{L1}+r_{L2})\·T}----\left(16\right)$ +τ·A ₁·cos(2m ₂ω ₂kT- _T)+(T-τ)·A ₂·cos(2m ₂ω ₂(k+1)T- _D)

Components and parts in Fig. 5 circuit can be selected by following condition.If the cut-off frequency of low pass filter is f _CAt first require: f _C＜＜f _T $f_c=\frac{1}{2\mathrm{\&pi;}\sqrt{L_1\&CenterDot;C_1^{\&prime;}}}=\frac{1}{2\mathrm{\&pi;}\sqrt{L_2\&CenterDot;C_1^{\&prime;\&prime;}}};$ C ₁+ C ₁=C ₁° get $f_T=\frac{1}{2\mathrm{\&pi;}\sqrt{L_2\&CenterDot;C_2}}$ Then the correlation of components and parts selection is: $C_1=\frac{L_1+L_2}{{\left(2\mathrm{\&pi;}{f}_c\right)}^2\&CenterDot;L_1\&CenterDot;L_2};f_c<<f_T=\frac{1}{2\mathrm{\&pi;}\sqrt{L_2\&CenterDot;C_2}}----\left(17\right)$

Capacitor C ₂The main impacting with high pressure when preventing that switch from disconnecting is so capability value is unsuitable excessive; D is a damper diode, and when preventing switch connection, reverse current flows through SW.

According to above-mentioned principle, a kind of prime phase wound-rotor asynchronous motor with the detection winding is made up of stator and two essential parts of rotor; Stator is made of support, stator core, stator winding three parts, and stator winding is a three-phase or single-phase; Rotor is made of rotating shaft, rotor core and rotor winding three parts.It is characterized in that: the rotor winding has main winding and detection winding of a cover symmetry, and main winding is prime number (m ₂) phase---specifically adopt three-phase or five phase or two-phases, with Y-connection (preferably adopt three-phase or five phases for threephase asynchronous, preferably adopt two-phase or three-phase) for monopole asynchronous motor; Detecting winding is a phase, and its thin number of turn in line footpath is less, and with arbitrary being distributed in mutually in the same facies tract in the main winding, it is identical with the induced electromotive force phase place of that phase main winding in same facies tract to detect winding.Main winding and detection winding are drawn terminals by collector ring in the rotating shaft and brush respectively, detecting the two ends of winding can independently draw separately, shown in Fig. 6 (a), perhaps an end and that one the terminating at together and draw jointly of main winding mutually in same facies tract, and the other end is drawn separately, shown in Fig. 6 (b).

Utilize this asynchronous motor, propose to realize the method for stepless tandem control, as shown in Figure 7.Per two alternate parallel capacitor C at this asynchronous motor stator winding _m, to improve the power factor (can arrive 1 in theory) of stator.The m of rotor ₂The phase main winding is through m ₂After not controlling full-wave rectification mutually, obtain pulsating dc voltage E _2d, insert "T"-shaped LCL low pass filter and high-speed high-power electronic switch SW and form the loop.High-speed high-power electronic switch SW can be single also can be a plurality of in parallel the use, and its control end G sends trigger impulse by the detection control circuit that with the single-chip microcomputer is core and controls, and makes switch SW be in the high frequency on off operating mode; Inductance L in the LCL low pass filter adopts high frequency ferrite core, because the filter action of LCL low pass filter, the induced current of rotor main winding is level and smooth and continuous.The size of the instantaneous duty ratio of trigger impulse and frequency and the phase place that changes thereof are regulated according to the control signal of detection signal and the input of outside S end by the core single-chip microcomputer that detects control circuit.Detection signal one tunnel is to detect the voltage signal u that winding takes out from rotor, and this signal is reflecting that the frequency of rotor main winding induced electromotive force and phase place (and cross the null value correspondence and E _2dMaximum), and can further calculate revolutional slip s, rotation speed n by single-chip microcomputer; Rotation speed n also can directly be detected from shaft of motor by electromagnetic sensor or Hall element and obtain.Another road of detection signal is the current signal i that is obtained by arbitrary phase of current transformer access rotor main winding, and this signal is reflecting frequency, phase place and the amplitude (frequency can be adopted by single-chip microcomputer and survey the periodic method measurement) of rotor main winding induced current.Frequency and phase place according to detected rotor main winding induced electromotive force and induced current, regulate the frequency and the phase place of the instantaneous change in duty cycle of trigger impulse, control rotor main winding induced electromotive force and induced current homophase, thereby the rotor power factor is brought up to 1, and improved the overload capacity K of motor _mRequired rotating speed (trying to achieve revolutional slip s) according to input, simultaneous (3) formula and (4) formula can be calculated the induced current of required motor rotor main winding, regulate the size of the instantaneous duty ratio of trigger impulse again according to (16) formula, and utilize calculate the actual speed n of (or directly detecting) as negative-feedback signal, the control motor reaches required rotating speed rapidly and accurately and settles out, thereby has realized level and smooth stepless tandem control.

The present invention compared with prior art has following superiority:

1, principle science, advanced technology have been inherited the advantage of traditional tandem control, and promptly speed adjusting performance, runnability and efficient etc. are all better.And, owing to adopted the HF switch scheme of real-time control, make that the inductance in the filter adopts high frequency ferrite core, the building-out capacitor in motor stator loop adopts fixed value, so control appliance and compensation arrangement volume are little in light weight, and reduced pollution to electrical network; Control circuit is core with the single-chip microcomputer, and the rapidity of control procedure, accuracy and stability are all fine.

2, can realize level and smooth stepless speed regulation.When reducing rotating speed, can also improve the overload capacity of asynchronous machine, thereby can be applicable to multiclass loads such as permanent power, permanent torque, fan type.

3, the power factor of rotor can be brought up to 1 speed governing the time.The capacitor that so only needs to adopt fixed value just can be with the power factor compensation to 1 of stator, thereby improves the total power factor of asynchronous machine (can arrive 1 in theory) easily.

4, the asynchronous motor of this invention has just increased by one and detected winding, and is simple in structure, and volume does not have and increases, and has kept whole advantages of common alternating current asynchronous machine, also can be used as common asynchronous machine fully and uses.

With most preferred embodiment in detail the present invention is described in detail below in conjunction with accompanying drawing.

Fig. 1 is the equivalent circuit of asynchronous motor;

Fig. 2 is the mechanical characteristic of asynchronous motor;

Fig. 3 is asynchronous machine m ₂Phase (coiling) rotor full-wave rectifying circuit and rectifier output voltage waveform;

Fig. 4 is the voltage source with Fig. 3 circuit equivalent;

Fig. 5 is a tandem control principle sketch of the present invention;

Fig. 6 is asynchronous motor rotor winding circuit figure of the present invention;

Fig. 7 is a technical scheme schematic diagram of the present invention.

As shown in Figure 6, a kind of prime phase wound-rotor asynchronous motor with the detection winding is made up of stator and two essential parts of rotor, and stator winding adopts three-phase.It is characterized in that: the rotor winding has main winding and detection winding of a cover symmetry, and main winding (a, b, c) is that three-phase is with Y-connection; Detecting winding (f) is a phase, and its thin number of turn in line footpath is less, is distributed in mutually in the same facies tract with c in the main winding, identical with the induced electromotive force frequency and the phase place of c phase main winding to guarantee detecting winding (f).Main winding (a, b, c) is drawn terminals A, B, C by collector ring in the rotating shaft and brush; Detect the two ends of winding (f) and can independently draw terminals E, F separately, shown in Fig. 6 (a), perhaps an end and c mutually an end of main winding link together and draw with terminals C jointly, and the other end is drawn terminals F separately, shown in Fig. 6 (b).

As shown in Figure 7, utilize band of the present invention to detect the prime phase wound-rotor asynchronous motor of winding, proposition realizes the method for stepless tandem control.Shunt capacitor C between every two-phase of this asynchronous motor stator winding _m, can compensate the power factor to 1 of stator.The three-phase main winding of rotor (a, b, c) does not obtain pulsating dc voltage E as shown in Figure 3 after not controlling the full-wave rectifying circuit rectification through three-phase _2d, insert by L ₁, C ₁, L ₂"T"-shaped low pass filter of forming and high speed switch type high-power FET SW form the loop.Preferably a plurality of in parallel uses of high speed switch type high-power FET SW, its control end G sends trigger impulse by the detection control circuit that with the single-chip microcomputer is core and controls, and makes SW be in the high frequency on off operating mode; Inductance L in the low pass filter ₁, L ₂Adopt high frequency ferrite core, because the filter action of low pass filter, the induced current of rotor main winding (a, b, c) is level and smooth and continuous.The size of the instantaneous duty ratio of trigger impulse and frequency and the phase place that changes thereof are regulated according to the control signal of detection signal and the input of outside S end by the core single-chip microcomputer that detects control circuit.Detection signal one tunnel is to detect the voltage signal u that winding (f) takes out from rotor, and this signal is reflecting that the frequency of rotor main winding (a, b, c) induced electromotive force and phase place (and cross the null value correspondence and E _2dMaximum), and can further calculate revolutional slip s (=f by single-chip microcomputer ₂/ f ₁), rotation speed n (=60 (f ₁-f ₂)/p); Another road of detection signal is the current signal i that is obtained by current transformer access rotor c phase main winding, this signal is reflecting that (its frequency is adopted by the Timer of single-chip microcomputer and surveys periodic method and measure for frequency, phase place and the amplitude of rotor main winding (a, b, c) induced current, being located at signal i one-period inside counting value is N, and the frequency of clock pulse is f _s, the frequency f of rotor main winding induced current then ₂=f _s/ N).According to detected voltage signal u and current signal i (they are reflecting the frequency and the phase place of rotor main winding induced electromotive force and induced current), regulate the frequency and the phase place of the instantaneous change in duty cycle of trigger impulse, control rotor main winding (a, b, c) induced electromotive force and induced current homophase, thereby the rotor power factor is brought up to 1, and improved the overload capacity K of motor _mRequired running speed (trying to achieve revolutional slip s) according to the input of S end, simultaneous (3) formula and (4) formula can be calculated the induced current of required motor rotor main winding (a, b, c), regulate the size of the instantaneous duty ratio of trigger impulse again according to (16) formula, and utilize calculate actual speed n as negative-feedback signal, the control motor reaches required rotating speed rapidly and accurately and settles out, thereby has realized level and smooth stepless tandem control.If the break-make frequency of switch SW is f _T, the cut-off frequency of low pass filter is f _C, then the correlation of components and parts selection is: $C_1=\frac{L_1+L_2}{{\left({2\mathrm{\&pi;f}}_c\right)}^2\&CenterDot;L_1\&CenterDot;L_2};f_c<<f_T=\frac{1}{2\mathrm{\&pi;}\sqrt{L_2\&CenterDot;C_2}}$ Capacitor C ₂The main impacting with high pressure when preventing that switch from disconnecting is so capability value is unsuitable excessive; In addition, D is a damper diode, and when preventing switch connection, reverse current flows through SW.

Claims (2)

1, a kind of with the prime phase wound-rotor asynchronous motor that detects winding, form by stator and two essential parts of rotor, stator is made of support, stator core, stator winding three parts, and stator winding is a three-phase or single-phase, and rotor is made of rotating shaft, rotor core and rotor winding three parts; It is characterized in that: the rotor winding has main winding and detection winding of a cover symmetry, main winding is the prime number phase---specifically adopt three-phase or five phase or two-phases, with Y-connection (preferably adopt three-phase or five phases for threephase asynchronous, preferably adopt two-phase or three-phase) for monopole asynchronous motor; Detecting winding is a phase, and its thin number of turn in line footpath is less, with arbitrary being distributed in mutually in the same facies tract in the main winding; Main winding and detection winding are drawn terminals by collector ring in the rotating shaft and brush respectively, detecting the two ends of winding can independently draw separately, perhaps an end with in same facies tract that mutually an end of main winding link together and draw jointly, and the other end is drawn separately.

2, utilize claim 1 described a kind of, propose to realize the method for stepless tandem control, at first the power factor correction capacitor C of fixed value in parallel between every two-phase of stator winding with the prime phase wound-rotor asynchronous motor that detects winding _mIt is characterized in that: the main winding of this asynchronous motor rotor inserts "T"-shaped LCL low pass filter and high-speed high-power electronic switch and forms the loop through after not controlling the full-wave rectifying circuit rectification; Inductance L in the LCL low pass filter adopts high frequency ferrite core; The high-speed high-power electronic switch can be single also can be a plurality of in parallel the use, and its control end sends trigger impulse by the detection control circuit that with the single-chip microcomputer is core and controls, and makes the high-speed high-power electronic switch be in the high frequency on off operating mode; The size of the instantaneous change in duty cycle of trigger impulse and frequency thereof and phase place are regulated according to the control signal of detection signal and outside input by the core single-chip microcomputer that detects control circuit; Detection signal one tunnel is voltage signal u, take out from the detection winding of rotor, this signal is reflecting the frequency and the phase place of rotor main winding induced electromotive force, and can further calculate revolutional slip s, rotation speed n (rotation speed n also can directly be detected from shaft of motor by electromagnetic sensor or Hall element and obtain) by single-chip microcomputer; Another road of detection signal is current signal i, is inserted arbitrary phase of rotor main winding and is obtained by current transformer, and this signal is reflecting frequency, phase place and the amplitude of rotor main winding induced current; The rotor main winding induced electromotive force that is reflected according to detected voltage signal u, current signal i, the frequency and the phase place of induced current, regulate the frequency and the phase place of the instantaneous change in duty cycle of trigger impulse, control rotor main winding induced electromotive force and induced current homophase; Required running speed (trying to achieve revolutional slip s) according to the outside input, calculate the induced current of required motor rotor main winding, regulate the size of the instantaneous duty ratio of trigger impulse, and utilize calculate the actual speed n of (or directly detecting) as negative-feedback signal, the control motor reaches required rotating speed rapidly and accurately and settles out, thereby has realized level and smooth stepless tandem control.

Images