JPS60200793A - Controller of induction motor - Google Patents

Abstract

PURPOSE:To preferably control a vector by providing a limiter in a circuit of a synchronous frequency command, setting the limiter set level to a value corresponding to the DC voltage value of an inverter, thereby obtaining a voltage necessary for an exciting current. CONSTITUTION:A voltage detector 26 which outputs a signal corresponding to an output voltage VDC of a converter 24 is provided, and a limiter level omegal is generated by a limiter level calculator 27 by the output Vc. A frequency command omega of the output of an adder 9 is suppressed by a limiter level omegal by a limiter 28, and applied to an integrator 10. Thus, it can be controlled response to the voltage of a DC power source of an inverter for generating the primary voltage to be applied to an induction motor, thereby performing a vector control adapted for obtaining a voltage necessary for an exciting current ides.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to the control of an induction motor driven by a frequency converter, and in particular, when the power supply voltage supplied to the frequency converter is lower than a fixed value due to some reason. The present invention relates to a control system for controlling the safety cage operation, which enables suitable control even when the temperature decreases.

[Prior art]

There are various types of control methods for controlling induction motors using frequency converters, including vector control and so-called V/f constant control, which controls the ratio of -order pressure and primary frequency to a constant value. method has been put into practical use, but in recent years -
By controlling the secondary current as a vector quantity, the induction
A vector control system has been developed that allows an electric motor to achieve performance comparable to that of a DC motor, and has long maintainability comparable to that of induction motors, as well as low cost. 7, - There are various methods for this vector control, and one that can achieve transient control performance equivalent to that of a DC machine is one that linearizes the torque transfer function by taking leakage inductance into consideration. method (H, Sugimoto etal.

: ENGEEElPE0ConferenceRecord
, 1983).

The principle of this vector control system will be explained below with reference to FIG.

The equation of state for an induction motor is de rotating at an angular frequency ω.
In the -qe coordinate system, the de and qe axis components of the -order current
, ies"qeIl] and the secondary current de and qe axis component 1char + 1qer are respectively the state variables and the waist-order voltage de and qe axis component v0゜8.■ are the input ee variables, it is expressed as equation (1). It will be done.

However, in equation 1), Rs and Rr are the primary and secondary resistances of the induction motor, L8. El, is the primary and secondary inductance, M is the mutual inductance between the primary windings, P is the number of pole pairs of the fat conductor, ωr is the mechanical angular velocity of the rotor, p
=a/at represents a differential operator, and σ represents a leakage coefficient shown in equation (2).

2 σ=1-〇...(2) 8Lr Similarly, the generated torque T0 of the Karasu @ = electric motor is as follows (3)
It is expressed by the formula.

Te””PM (1qeslder-'des'qer)
-P-(]q8Illλder-1desλqer)0
°@(3).

However, λ,. 1. λ is the secondary magnetic flux er It represents the de and qe axis components and is expressed by the following equation.

λqer""Lr'qer+Miqee (1) and (3
) As can be seen from equation (1), if the state matrix includes the angular frequency ω of the secondary current vector and the rotor angular velocity ω1, equation (3) is nonlinear at one point. It is nonlinear in that it includes the product of variables. Therefore, although speed control is good as it is, the principle of vector 1t1 control is that the primary electric current mL to be supplied to the induction motor is equal to the secondary magnetic flux vector, and the coordinate axis rotates (de-qe!
1IIIl), and this -order'
The component parallel to the total flux vector (i.e.,
By decomposing M2!4' into a component (excitation 1 existing current component) and an orthogonal component (i.e., torque' current component) and controlling each independently, non-interfering control of the secondary magnetic flux of the motive and torque is performed. be. When controlling the excitation constant, that is, 1
Considering the case where cles=des (constant value), the above objective is achieved by controlling the secondary current vector so that the de-axis component 1u8r becomes small. That is 1.186-
■. . 8 (constant value)... (5) der - 0° - (6) Under the conditions, the state equation (1) and generated torque equation (3) of the induction motor are respectively expressed as follows: nil
It takes shape.

Also, at this time, λ. r'-MIdeslλ9°r-0, and the secondary magnetic flux becomes a vector that rotates in synchronization with the de axis.

By the way, the conditions of equations (51 and (6)) are as follows: (9
), 0Vdes”””e-des”-ωσL8iqoB-, which is satisfied by controlling according to the equation
1-K(dc, s”-1des)...(10) However, PO2 in equation (9) is the slip angular frequency, (
10) The engineering in the formula. 8X represents the excitation current command value (constant value).

Figure 1 shows an example of the implementation of this vector control method, and shows an elevator control system that uses a pulse width modulation control (hereinafter referred to as FW!11) inverter to control the excitation sound of a fat conductor. There is. Note that the first term and the 82nd term on the right side of the above equation (1o) are omitted because the proportional key K of the sixth term is sufficiently large.

In Figure 1, (1) is an inverter for DC-AC conversion with variable frequency function, and (2) is an inverter (1).
The four-torque mechanism for the elevator is driven by the output of (
3) is a tachometer generator that detects the speed of the induction motor (2), and (4a) and (4b) are the U of the induction motor (2), respectively.
Cargo flow return signal iU, 1v in response to the primary current of phase and ■phase
(6j is the current feedback 1st signal i, , i
In addition to the addition circuit that adds the current feedback signals IU, iv, and 1w to calculate the current signal iw in response to the W-phase primary current, To the component on the coordinate axis that rotates in synchronization with the angular frequency ω of the secondary magnetic flux vector of the induction motor (2). This is a coordinate conversion circuit that converts 8 and 1q8sK.

This coordinate conversion circuit (5) performs coordinate conversion based on the following equation 01).

(11) where sin θ and cos θ in equation (11) are the sine wave outputs of the frequency generator (, 11), which will be described later.

Next, (6) Jakuyohi (7) il'i A circuit that calculates the slip angular frequency Pω8 according to the second term in the above equation (9)
A divider and a coefficient multiplier circuit for dividing 6 by qθ' cues are shown respectively, and Rr and Lr of the coefficient multiplier circuit (7) are
The more accurate values based on the actual machine are used for the secondary resistance and secondary inductance values of the induction motor (2), which are used for the supernatant and the purple π paratheta, the more accurate vector control becomes possible. . In addition, (8) is a multiplier that multiplies the rotor angular velocity ω by 9, and (9) is the angular frequency ω of the secondary magnetic flux vector from the angular frequency POJs and the rotor angular frequency Pω.
The adder (10) integrates the angular frequency ω and outputs the phase angle θ of the secondary magnetic flux vector.

(11) is a sine wave signal s with phase angle θ
A frequency generator that outputs inθ and a cosine wave signal cosOf, and can be easily configured with, for example, a V/F converter, a counter, and a ROM.

1, (12) is a comparator that compares the excitation current control circuit 6゜I and the excitation (jki current spiral signal.8) obtained by the coordinate conversion circuit (5), (]3) is a comparator ( 12) Excitation 'fjtb#LfrIi difference (■de
s'-1dos)'FcfM width, i'dj2j4 excitation of motor (2) 6R current 1°. 6 is always HI constant command value■
,. an excitation current control circuit that controls IK to be equal;
(14) is a comparator that compares the speed wave command ωI and the rotational speed ω of the induction motor (2) obtained by the tachometer generator (3). a speed control circuit (16
) are torque current command 18' and torque current feedback signals 1 and q
A comparator (07) for comparing the eqe date calculates the eqe based on the torque current deviation (i-'qes) detected by this comparator (16).
s Torque current control circuit that generates pressure command VS' (18)
qe is an addition circuit using an operational amplifier and a multiplier or D/
The two-phase voltage command Vdes"+vqes" generated by the excitation current control circuit (1B) and the torque current control circuit 07) is converted into the three-phase voltage commands V♂,v.
This is a coordinate conversion circuit that performs VwXK conversion.

This coordinate conversion circuit (18) is based on the following equation (]2)... (12) Next, (19) is the sheave directly connected to the induction motor (2), and Rope wrapped around the sheave, (2
1) is a basket connected to one end of the rope ()), and I) is a counterweight connected to the other end of this rope (goods). An example of this is a converter that converts this three-phase current into direct current.Y) is a smoothing capacitor that smooths the output of this converter and supplies DC power of 3 degrees F to the inverter (1).

The control device configured as described above has the excitation current component 1° of the primary current, which is the Jlt amount, and the torque current component 1.

6, each having an independent feedback control system and a predetermined excitation current command function. I, speed command ωI, and rotational range ω of the induction motor (2).

If the torque current command 16' corresponding to the deviation of A voltage command Vcues'''v'' is generated by qeθ, and then a response is generated by controlling these voltage commands as manipulated variables so that the primary current vector of the induction motor (2) matches the primary current reference vector. This enables highly accurate speed control with excellent performance.

In addition, by calculating the slip angular frequency Pω8 using the -order current feedback No. 16 of the induction motor (2) and giving the instantaneous value of the -order voltage of the induction motor (2) according to this, it is possible to It enables six degrees of vector control that satisfies the same performance as a DC machine.

This means that suitable control performance can be achieved in elevator control that emphasizes transient response.

However, this control device cannot control the excitation current command
This is based on the assumption that the excitation current in response to the current will reliably flow to the induction motor (2), and if this assumption is violated, vibrations may occur in the torque generated by the induction motor (2).

That is, the voltage to be applied to the inverter (1) is set as low as possible in order to allow the withstand voltage of the semiconductor elements to withstand the pulse voltage generated when the semiconductor elements constituting the inverter switch. ing. Therefore, the voltage requirement for passing a constant ρOt through the induction motor (2) is generally not very large.

Therefore, due to a drop in the three-phase current power supply voltage, etc., the output voltage of the converter example becomes lower than the converter voltage command value set according to the angular frequency ω, and the above-mentioned excitation current command value decreases. If the excitation current that responds to I cannot flow, vibrations will occur in the torque generated by the induction motor (2), and when this is applied to elevator control, it is common knowledge that V will cause problems such as a loss of riding comfort. Found out by Yon.

[Summary of the invention]

The present invention has been made for the purpose of eliminating the above-mentioned drawbacks of the conventional ones. The induction motor is controlled in response to the excitation current component command, so that the excitation current can flow through the induction motor in accordance with the excitation current component command, and even if the inverter power supply voltage drops, it is possible to perform suitable vector control. This paper proposes a device.

[Embodiments of the invention]

FIG. 2 is a block circuit diagram showing the configuration of an embodiment of the present invention, and is an example used for controlling an elevator in the same manner as described above. In FIG. 2, the same reference numerals as in FIG. 1 indicate elements that are the same or have the same effect, and represent the output voltage vD of the converter.

a voltage detector 4 that outputs a signal corresponding to the voltage detector 4, a limiter level calculation circuit (27) that generates a limiter value of the frequency command ω according to the output signal V0 of the voltage detector 4, and the output of the adder (9). The difference from FIG. 1 is that a limiter circuit (10) for suppressing the frequency command ω to the output value ω7 of the limiter level calculation circuit and adding it to the integrating circuit (10) is newly added.

FIG. 6 is a circuit diagram showing the detailed configuration of the voltage detector (261trs=resistance (26a), (26b), (26b),
26c) and an isolation amplifier (26cL), and the limiter level calculation circuit (27) consists of resistors (27b) to (27g) and a diode (27h).
and a limiter generation circuit (27j) consisting of an operational amplifier (27j).
272) and resistance (271), (27m).

Logic level signal circuit (272) consisting of (27p), (27q), operational amplifier (27n), and diode (27r)
It is made up of.

Next, Figure 4 is a circuit diagram showing the detailed configuration of the limiter circuit (a), which includes an operational amplifier (28d), a comparator (28e), and a
), (28j), buffer amplifier (28g), (281
) limiter (28+) and an analog switch (2
82).

The operation of this embodiment configured as described above will be explained with reference to FIG. 5, with the portion in which new elements have been added to FIG. 1 shown in the upper middle.

The voltage detector (V) is a signal V corresponding to the output voltage VDC of the converter (throttle). When the limiter level calculation circuit (z7) outputs the negative box pressure (
27a), the limiter level ω4 shown in FIG. 5 having negative polarity is generated from the value obtained by subtracting the first set voltage VB set by the resistors (27b) and (27c).

At the same time, the output ω6 of the operational amplifier (27j)
and negative power supply (27k), resistor (27u), (27rn)
A comparator (27n) compares the second set voltage △ω that corresponds to the voltage of vref""B set at Setting 11
1 or less and when ωt≦△ω, a logic level signal for controlling the limiter circuit that becomes “LJ” is generated.

The limiter circuit applies a limit to the synchronous frequency signal ω in response to the limiter level signal ω and the logic level signal, and operates as follows depending on the polarity of ω.

First, when ω is positive, the comparator (28e)
a), (28'b), (28c) and operational amplifier (28d
) The limiter level signal ω4 is converted to positive polarity by a polarity inversion circuit consisting of a 2se) is compared with the synchronous frequency command ω applied to the inverting input of
When the magnitude of ω becomes larger than the limiter level ω7, the comparator (28θ) outputs a negative voltage and the diode (
28f) is made conductive, and the input and output of the buffer amplifier (281) are lowered by ω until the inverting input of the comparator (28e) becomes equal to the non-inverting input level ω, and ωt
l: Works so that L is always kept below limiter d level ω6.

When ω is negative, a comparator (28a) similarly compares ω and ω7, and a buffer amplifier is connected via a diode (2sk) and a resistor (28h) to keep ωt1 below ω7. (281) In these cases, the input voltage is smaller than ω7 or △ω, so there is an enemy ground level signal. is at "L" level, and the output ωtd of the buffer amplifier (281) is the output ω of the analog switch.

On the contrary, when the primary voltage of the fat conduction motor satisfies a predetermined value and ω4 is
If it is larger than ω, there is a logic level signal.

becomes the rHJ level, and the analog switch (282) divides ω, which is not limited by the limiter, between ω and (,
and output it.

In this way, the set level of the limiter provided in the frequency command circuit can be controlled in accordance with the direct current pressure of the inverter that generates the primary pressure applied to the induction motor, and thereby the excitation current An extremely suitable vector control rl14I is performed that can secure the voltage necessary for 1dee.

Next, FIG. 6 is a block circuit diagram showing the configuration of another embodiment of the present invention, in which the same reference numerals as in FIGS. 1 to 4 indicate the same elements. In Fig. 2, a limiter circuit (11B) is provided after the adder (9), but here the limiter circuit (28+) shown in Fig. 4 is provided.
The primary voltage of the induction motor is detected by a voltage detector (2), and the limiter level calculation circuit (27+) controls the limiter (281) based on this voltage detection signal. FIG. 7 is a circuit diagram showing a detailed configuration of this voltage detector (2+11.IJ) level calculation circuit (271) and limiter (28+).

In FIGS. 6 and 7, a voltage detector (b) detects the negative voltage of the induction motor (2), and a signal V corresponding to this negative voltage value is generated. , full output is produced, but this voltage (broiler (4)) is connected to capacitors (29a), (29b), (2
9c) and resistors (29d), (29e), (29f)
A low-pass filter is formed by the above, and outputs the nTh signal corresponding to the fundamental wave component of the primary voltage including harmonics subjected to pulse width modulation (PWM). This 'voltage signal■.

1 is added to the limiter level calculation circuit (27+).

In response to this, the limiter level calculation circuit (27+) generates a limiter level value ωt in the same manner as described above and adds it to the limiter (2B+).

Thus, in this embodiment as well, the frequency command ω is limited in accordance with the -order voltage value of the induction motor (2), so
A margin is ensured so that the desired dynamic current is transmitted to the induction motor, and thereby suitable vector control is performed.

Next, FIG. 8 is a block circuit diagram showing the configuration of another embodiment of the present invention, in which the same reference numerals as in FIG. 2 indicate the same elements. Then, the voltage detector ■υ) and limiter level calculation circuit (z
7) Instead of excitation current command■. . I and excitation current value 1
The limiter level signal ω4 and the logic level signal to be added to the limiter circuit (to) in response to the deviation from des.

A circuit (dO) is provided to generate the following.

Figure 9 is a circuit diagram showing the detailed configuration of this IJ Mitsutarepel operation circuit (301).
30d) and a negative power supply (30b), a threshold setting rectangular circuit, a diode (30g), and a capacitor (3oh).
, an operational amplifier (30j), and a resistor (3
0m), (3Dn) and a positive power supply (301), a comparator (30s) that uses this limiter level as a reference signal, and a threshold value of the above-mentioned threshold value addition circuit. A comparator (30V) with a hysteresis of magnitude 1. It consists of a diode (30z) that converts +lJ military pressure into a logic level signal.

The operation of this embodiment will be explained below.

First of all, for some reason the primary voltage of the fat conductor marker machine drops,
The command value is excitation current 1des. . It becomes impossible to follow I, and the 118th day value of the deviation signal (engine - 1des) is a negative power supply (3ob), resistance (30c) + (3oa)
When the negative threshold defined by TE is exceeded, the negative threshold is resisted by (30a) + (30") from the deviation code (Icues"-'88). The summed signal (des”-1dee)-tkh is the resistance (30
a), (30e), (30f), capacitor (30h)
, an integrator consisting of a tie auto (50g) and an operational amplifier (30j). Generates a negative integral output signal. This negative integral output Cairo is the power source of the stop (30
1) The resistors (30m) and (30n) are used to reduce the set positive constant frequency limiter level and push the limiter level signal ωt down to a constant low level.

At this time, the comparator (30v), which has a hysteresis width of the same size as the above negative threshold value - th, outputs a negative saturated direct pressure due to the resistors (30u) and (30w), and this shell tvfMKl ] It is converted into the logic signal L0 of rLJ by the voltage Ba (30X), (307), Gui, t-to (30z). Then, by the limiter level signal ω4 pushed down to a predetermined low level and the logic level signal L0 of the rLJ level, the limiter (2B) outputs a frequency command signal ωt suppressed below the limiter level signal ω.
Output d. Therefore, the frequencies of the primary voltage and secondary current applied to the induction motor are suppressed to below predetermined values.

〔Effect of the invention〕

As is clear from the above theory BA, according to the control device for the electric motor of the present invention, a limiter is provided in the circuit of the synchronous cycle mantissa command ω, which is the number of cycles V of the primary current given to the shoulder-driving motor, and the limiter The setting level of the current is controlled according to the DC' voltage value of the inverter that generates the primary voltage applied to the induction motor, or a value related to this, so the voltage required for the excitation current is secured, and the voltage required for the elevator operation is maintained. Very convenient vector control becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the configuration of a conventional device, FIG. 2 is a block circuit diagram showing an embodiment of the present invention, and FIGS. 6 and 4 are main elements of the same embodiment. A circuit diagram showing a detailed configuration, FIG. 5 is a performance diagram for explaining the operation of the same embodiment, FIG. 6 is a block circuit diagram showing the formation of another embodiment, and FIG. 7 is a diagram of the same embodiment. FIG. 8 is a block circuit diagram showing the configuration of another embodiment, and FIG. 9 is a circuit diagram showing the detailed configuration of the main elements of the same embodiment.
FIG. 2 is a circuit diagram showing a second configuration. (1) Φ・Inverter (2)・Induction motor (51, (
18) Coordinate conversion circuit (11) Frequency generator 1. (b) 1...'Voltage detector Hl, Gat! l...Limiter level calculation circuit (prior -
Limiter circuit Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa Figure 9 Procedural Amendment (Voluntary) 1938 AR38 To the Commissioner of the Japan Patent Office 2.3 Name of control device for induction motor 3, person making the amendment Representative Hitoshi Katayama Dept. 1, Agent Contents of Supplement No. 6 (1) The statement "Formula 1" on page 4 of statement sheet 1 is amended to "." - between the secondary winding and the secondary winding." (The statement "P is a rib 24 electric motor" in the first line of page 5 of the 81 specification sheet is amended to read "piIi induction barrel electric motor.")

Claims (3)

[Claims] (1) Calculate the primary frequency from the sum of the overall frequency command and rotational frequency of the induction motor, and convert the primary current of the induction motor using a frequency converter based on the primary current command or primary voltage command having this -order frequency. In the control device for the induction motor to be controlled, the induction motor is provided with a limiter that limits the upper limit of the -order frequency in accordance with a primary voltage value of the four-stage electric motor or a value related to the generation of the primary voltage. Electric motor control device. (2) A self-mounted induction motor as claimed in claim 1, characterized in that the limiter is controlled in accordance with the primary voltage of the misconducting motor or the power supply voltage of the frequency converter;
MushibI old man's market control device. (3) The limiter is controlled in response to a deviation between a magnetic flux command of the induction motor and an actual magnetic flux determined by actual measurement or calculation, or a deviation between an excitation current component command and an actual excitation component. A control device for an induction motor according to claim 1.