JPS5843198A - Induction motor control system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor control system, particularly to a motor control system for torque control of an induction motor.

Most industrial speed controlled equipment is not demanding in terms of speed control bandwidth and operating range, but in contrast, fast and accurate four-quadrant control (i.e., drive and brake are bidirectional) is required. - have several important uses. These applications range from forming machine tool drives to large-scale reversing presses and rolling main drives in the steel industry.
These requirements can be fully met by the 1) drive system using a DC machine supplied by a static converter.

Apart from similar problems associated with zero rectifiers, DC drives provide excellent response, with a torque control bandwidth of 500 rad/sec and a speed control bandwidth of approximately 30 rad/sec. available to the public.

Another device that powers an AC motor with a static power device is
To date, DC drives have not been seriously challenged in these specialized application areas, due to their relatively high cost and the lack of care in meeting their performance specifications. . However, current economic trends indicate that the ``overall price advantage'' of AC drives over **C* one-way systems must eventually emerge. From this point of view, the equivalent gender −
It is becoming increasingly important to expand the control capabilities of AC motor-driven devices with This is based on an AC drive system that has comparable performance.

Therefore, it is an object of the present invention to provide an AC motor control system that is comparable in performance to the current DC system and at the same time is economically practical.According to the present invention, the induction motor control system is means for generating signals representative of desired values of current amplitude and resulting slip angle; means for generating a rotor angle signal in response to rotor angular position; and means for generating a rotor angle signal in response to rotor angular position; means for decomposing into orthogonal required components proportional to the sine □ and cosine of, and said required component (target component)
′ and the equivalent stator * in response to said rotor angle signal.
and forward conversion means for generating the m drive signal.

□The separate drive signals can be configured to be combined (synthesized) with negative feedback signals generated from each stator phase winding to directly control the magnetomotive force of the stator. .

Preferably, reverse conversion means are provided which are responsive to the rotor angle signal, said conversion means converting a signal representative of the actual stator phase current into a signal representing the actual stator phase current by rotating synchronously with the rotor and converting the cosine of the resulting slip angle into a signal representing the actual stator phase current. and a cosine, and these actual components constitute a negative feedback signal in a closed control loop.

In systems where the stator of the motor does not have a zero-sequence component, one of the stator winding drive signals is preferably generated as the negative sum of the remaining. Therefore, a forward transformation is performed, and the stator phase current values gas, ics are converted into rotor reference components 1ds, iqs in the orthogonal direction, as follows:
We can incorporate the following matrix product, i.e., and the inverse transformation can incorporate the following matrix product 1°. □゛Means for calculating from the actual components of the magnetomotive force of the stator, means for generating a signal representing the actual torque from the actual components of the stator and rotor, and means for calculating this actual torque signal in a closed control loop. Preferably, means are provided for comparing the F-lux reference signal and the F-lux reference signal.

Next, several motor control methods will be described as specific examples with reference to the accompanying drawings.

FIG. 1 shows a block diagram of a direct control system for a three-phase a-induction motor that employs magnetomotive rotation axis conversion only in the forward direction.

In the magnetic field, as in other electric motors, it is necessary to control the amplitude and phase relationship between the stator and rotor magnetomotive forces to control the instantaneous torque. A fundamental feature of the invention is that the stator magnetomotive force is arbitrarily resolved relative to the rotor within a fixed reference frame. The rotor has a stator magnetomotive force and a slip frequency; C: Speeds that differ by the number A...Mo, instant rotation, stator magnetomotive force L-4@@-F7. -It is determined by the synthesis of the mine, 75, ゎ 8 ° frequency Ω ω and the synthesis of the right angle that is varied in size.

With a constant slip wave number, ωt can be seen as the resulting angle value, and the rotor slips by that angle with respect to the stator magnetomotive force. Let this slip angle be φ.The two orthogonal components are called the direct component and the orthogonal component, and ids
, jqs, and the corresponding component of the rotor magnetomotive force is expressed as i
ds, iqs″C” (for the same axis) sd
s=i billion φ 'QS = I stm φ However, ■ is the composite stator magnetomotive force.

The required torque can therefore be determined by controlling the amplitude of the stator current and the slip frequency, and directly by controlling the component id
s and the orthogonal component -$ and slit. They are called s and -3 to distinguish them from the values of the components that are actually rising.

Once the value '1da and qS are established, the individual stator phase currents Is, il), 16 can be obtained by the following conversion formula.

- Therefore, 1as = s/T7T (lds
ocis # −jqs siaθ), and similarly i
This also applies to bs and lcs. Furthermore, it becomes 1. The angle θ is the position-angle of the stator mentioned above and is determined by a position encoder mounted on the motor shaft.
There are phases 'H1a*bec, and these windings are fed by a thyristor power amplifier/converter shown as block 3. Each motor draw current 1as etc. is controlled by a closed loop including a current transformer 5, a unity gain feedback path 7, a differential circuit 9 and an amplifier 11, the amplifier 11 performing forward path compensation.

The reference or drive signal input to the differential circuit 9 is generated from the forward conversion circuit 13. This circuit is supplied with the rotor angle signal and the orthogonal demand components 1ds, iqs to produce the transformations described above.

In this direct control system, each control loop is required to track its oscillating reference signal with acceptably small errors.

FIG. 2 shows a similar morph configuration with phase current feedback, but in this case the ζ feedback signal is inversely transformed (block 15) to the feedback value in the rotating reference 7 frames.
(denoted as C). Conversion value i
ds and lqs are subtracted from the corresponding required values IJs and i5s in the differential circuit 17 to provide a forward direction signal. In this case, these error signals arise as voltage inputs to the power amplifier 3, which voltage signals are given by the determinant below and can be viewed as a series of effects of the loop components.

Unfortunately, the real-time complexity required for this induction of motor phase voltages may be considered excessive. In this case, the above derivation can be considerably simplified by using the following limited run type % formula %.

This assumes that the phase current does not include any instantaneous zero sequence component, and under this condition, the inverse transformation becomes 1 as shown below.

・、” Then, the forward transformation is as follows.

If you expand this, it will look like this:

The remaining phase current ibs is expressed by the following equation.

1bs=-(quantity as+1cs) These simplified conversion equations are incorporated into the control device shown in FIG.
and Was, and the remaining voltage signal Vbs is vCI
◇ The torque demand is determined from r and φ, the resultant stator magnetomotive force and the resulting slip angle. The sine and cosine functions of φ are generated by analog or digital lookup tables 19- and 2.1, and the results are multiplied by I* in circuits 23 and 25 to give 1q8 and ida, respectively.

and 1 ml. Also, an analysis circuit or digital look-up table (which has corresponding input and output signals) is used to give the sine and cosine of (#-g15) and the sine and cosine of O. There is.

The product from equation (3) above is given by multiplier 35.57.59.41. Multipliers 65 and 37 provide a feedback value ids that is subtracted from the desired value lds'' in summing amplifier 43 (P and I denote proportional and integral).Similarly,
lqs is subtracted from -30 in the summing amplifier 45.

These amplifiers 45 and 45 correspond to the differential circuit 17 in FIG.

The forward transformation of equation (4) is then performed by the multiplier 47.49°51
．． 55, these multipliers are obtained by ids sm e , lqs cm L, i
ds su (θskewer w15) * OJ: IJ lqg+ am (#-
w15) gives 0 further amplifier and in. By combining the voltages, the required phase voltages Vcs, Vbi, Wis to be applied to the power amplifier 3 are given.

Instead of a total 3 × 3 matrix, a 2 × 2 matrix (Equations (1) and (2)
) (FIG. 5) is a very practical device capable of accommodating a microprocessor. The microphone processor can perform all of the above device sets in addition to providing the sine and cosine values from the roof-up table. It also handles the 9-frequency resolution of the sleeve "□" as well as other clock up needles associated with the induction motor controller.
- Figures 4 and 5 show another induction motor torque control method based on the control system shown in Figure 3. value and then also the stator phase voltage as described above. The torque reference input 55, which corresponds to the slip frequency, is applied to a transfer circuit 57 that relates the total stator magnetomotive force I to the slip frequency with constant stator flux leakage.

Additionally, the slip frequency ω is integrated to give the slip angle ω+ or φ produced by an integrator 59. (2) These required values for 0 and φ are given to the magnetomotive force control device 61 as shown in FIG. The motor 65 is the second
It is driven by the power amplifier 3 shown in the figure and provides feedback for the phase currents -1as and lcl and rotor angle 0 as required by the control system.

Figure 4(b) shows the achieved torque value and the corresponding oscillation value l.
ds and tq Lu are shown. Torque control using this method is sufficient for certain purposes, but there are still some deficiencies.

In FIG. 5, a similar internal control is utilized, but the orthogonal component values 14s, iqs actually rise and are generated at the inputs of the fifth amplifiers 45 and 45, but their The component values are used in torque calculator 65 to provide the actual torque value. This value is the differential circuit 67
is compared with the required torque value of and subtracted from it. The error signal is then converted to a total magnetomotive force to produce an angular value as shown in FIG.

FIG. 5(b) shows an example of an improvement for obtaining steady torque without oscillation of the magnetomotive force component. The improved torque control system of FIG. 5 is a feature of this embodiment of the invention.
This results in a relatively simple relationship existing between the stator magnetomotive force and the rotating rotor magnetomotive force components in a rotor-based reference frame. In other words, these relational expressions enable very simple torque calculation. That is, T = K (iq@idr - ids iqr), and torque calculation can be performed very easily only in the reference frame of the rotor.

After calculating the torque in this manner, it is simple to approximate the torque loop as shown in FIG. 5, thereby centering the slip frequency associated with the magnetomotive force control.

FIG. 6 shows a block diagram of a complete induction motor drive circuit using ring-connected cycloconverters. In the same figure, 3
A phase power supply is connected to the cycloconverter, which comprises a 5-phase silis bridge 67, 68, 69 fed in parallel from said power supply. The DC output of the bridge is connected in series with the porcelain-connected stator phase winding a,
b, c are connected to the bridge interconnection point. The bridge thyristor is fired by an ignition circuit 71 controlled from a ring interface control circuit 73.

The control circuit 73 receives the stator phase voltages Was, Vbs, Yes from the magnetomotive force control unit 61 and either relays the actual stator phase current 1ml, icI or the latter is connected to the current transformer via the bridge current monitoring circuit 77. Generated from 75. Conventional zero current detector 79 and bridge inhibition circuit 81
Also provided.

The rotation stagger θ is determined by a shaft angle converter 83 and the speed of the rotor is determined by a shaft speed converter 85. The rotor angle signal 0- is given to the magnetomotive force control circuit 61, the chassis 7 speed signal is sent to the differential circuit 87,
The shaft speed signal is then subtracted from the speed base -.1 signal.

The error output of circuit 87 is applied to speed control circuit 89 to generate the necessary slip frequency signal, which is sent to transfer circuit 57 and integration circuit 59 to perform the function described in connection with FIG. These circuits generate the total magnetomotive force request signal 0 and the slip angle signal φ which is generated for the magnetomotive force control circuit 61. The circuit of FIG. 6 operates according to FIG. Therefore, direct magnetomotive force control is performed on the stator phase voltage.

FIG. 7 shows a similar induction motor drive circuit, but modified according to FIG. 5.

The calculated torque feedback from block 65 is compared in differential circuit 67 with the required torque signal or torque reference signal generated from the speed comparison.

``Therefore, the drive circuit provides the various benefits 44 of the present invention and allows for an mechanical drive with fast response speed to torque requirements.

-\,- Fig. 4 shows a direct control system for a three-phase induction motor that uses magnetomotive force rotational axis conversion only in the forward direction, and Fig. 2 shows a direct control system for a three-phase induction motor that uses magnetomotive force rotational axis conversion in the forward direction only, and Fig. 2 shows a system in which feedback is given by reverse rotational axis conversion. FIG. 5 is a pull diagram of a transformer circuit incorporating forward and reverse transforms related to FIG. 2; FIG.
<b) The figure shows the system related to Figures 2 and 3N and the corresponding wave shadows of the magnetomotive force component and motor torque.
) (b) shows a contrasting system and its characteristics in which the right-angle stator magnetomotive force component is extracted for torque calculation and direct torque control; 1 shows a cycloconverter induction motor drive with a control device according to the figure; FIG.

In the figure, (S) is a thyristor power amplifier/converter, (at
b, c) are the three-phase windings of the induction motor, (5) are the current transformers, (9) are the differential circuits, (11) are the amplifiers, (15)
) indicate the reverse conversion circuit, respectively.

Patent applicant's agent Mei 1) Nobuyuki The yj (inside') 'i' in the drawing has an unusual point 1. )Fig, 1
゜Fka, 2 Procedural Amendment C Item) September 2nd, 1981 Kazuo Wakasugi, Commissioner of the Patent Office, Patent Application No. 140475/1982 2. Name of Invention Induction Motor Control System 3. Case of Person Who Makes Amendment Relationship with Patent Applicant Name G-Eazy Eliot Automation Limited 4, Agent Postal Honor Number 100

Claims (1)

[Claims] Means (83) for generating a signal in response to a desired torque or speed indicating output; and means (83) for decomposing the stator current amplitude signal into the sine and cosine of the resulting slip angle signal. means (61) for producing a proportional quadrature demand component; and forward converting means (13) for generating an equivalent stator winding drive signal in response to said demand component and said rotor angle signal. ). 2. In the control method according to claim 1,
An induction motor control system characterized in that each of the drive signals is combined with a negative feedback signal generated from each fixed prephase 49!1 to directly control the stator magnetomotive force. 3) In the control method according to claim 1,
In response to said rotor angle signal (#), the actual stator I current rotates synchronously with said rotor and changes as the sine and cosine of the resulting slip angle (φ). An induction monitor control system comprising an inverse conversion means (15) for converting into a stator phase current, and the actual component constitutes a negative feedback signal of a closed control loop.4) Claims: In the control method according to clause 5, the motor stator is free of any zero sequence component;
and the stator winding drive current is generated as a remaining negative sum. 5) In the control method according to claim 4,
Stator currents iai and i giving forward transformation (13)
An induction motor control system characterized in that ts is converted into the right-angle rotor reference components ids and 1qs and becomes the following determinant, and the inverse transformation (15) is a product of the following determinants. 6) In the control method according to claim 3,
means (67) for calculating a corresponding component for the rotor magnetomotive force from the actual component for the stator magnetomotive force; and means (67) for comparing said actual torque signal with a torque reference signal in said closed control loop. 7) Means (IS, 45) for generating a feedback signal from the motor representing the actual motor torque, and means for generating a feedback signal representing the desired monitor torque. Means to do: Duck) 5.
:. (57, 49) A device for controlling the operation of an AC induction motor, comprising: a feedback signal and an instantaneous amplitude of a composite stator magnetomotive force; An operation control device for an induction motor, characterized in that the angle (φ) of magnetomotive force is minimized in response to a difference between the angle (φ) and a request signal for controlling said difference.