JPS6036715B2 - Vector control device for induction motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called vector control device that controls the magnitude of the primary current of an induction motor and the phase of the primary current with respect to the magnetic flux.

One such vector control is the magnitude of the primary current,
There is a method to obtain a predetermined current phase by setting the slip angular frequency in relation to the magnitude of the primary current. consists of the transient slip angular frequency associated with the time variation of .

Conventionally, this transient slip angular frequency was obtained by applying a voltage signal corresponding to the time derivative of the current phase to an oscillator whose output frequency is proportional to the input voltage. In some cases, the differential value becomes excessive and the output of the differentiator saturates, or the output of the oscillator saturates and the specified current phase cannot be reached, which is one of the original purposes of vector control. The response to the torque generated by a certain electric motor was significantly inhibited.

In view of the drawbacks of the conventional method, the present invention provides the phase signal itself instead of providing the time-differentiated signal of the current phase to the oscillator, detects the phase from the output frequency of the oscillator, and combines the detected phase with the command. By phase feedback control,
The present invention aims to provide a motor control device characterized in that the saturation of components included in this feedback loop compensates for error factors such as temperature changes and always obtains a predetermined current phase.

FIG. 1 is a block diagram of an embodiment in which the present invention is applied to an induction motor driven by a three-phase current controlled inverter.

To explain with reference to Fig. 1, the three-phase current source inverter,
It consists of a converter unit CONV that supplies a current corresponding to a current command signal from an AC power supply SOU to an inverter unit INV, and an inverter unit NV that supplies a current with a frequency corresponding to an input frequency signal to an electric motor M.

The induction motor M has a rotational frequency detector POS attached to its rotor shaft to detect a rotational frequency corresponding to the number of rotations.

Now, the vector control device related to the present invention has a configuration in which the motor primary current i. is considered separately into excitation current component im and torque current component i7, and the current command value corresponding to each is set as 1, ,
1 skin 17, magnetic flux and torque current command value 1m
, 17 are the inputs of the vector control device, and the primary current command value 1 is calculated by the current calculator ``G'' as follows.

1, = no lm2 + 172 ... (Formula 1) The frequency command to the inverter is the sum of the slip angular frequency s related to the magnitude of the current command and the transient slip angular frequency f related to the time pseudoratio of the current phase. , the rotational angular frequency is given.

To calculate the wave number ws between slip angles, calculate the current command value 17,lm to 17/lm using the divider DIV, and then use the constant setter C.
At S, a value corresponding to the slip angular frequency is obtained by considering the motor constant R2/L2. Similarity = f-to - - - - (2 equations) However, R2 is the motor secondary circuit resistance, or the self-inductance of the motor secondary circuit.

This signal is applied to a slip frequency oscillator SGE and converted into a frequency signal having an angular frequency equal to the slip angular frequency.

Next, to calculate the small transient slip angle frequency, which is the subject of the present invention, first, the current angle calculator 1 is calculated so that the current phase angle ↓
A voltage signal proportional to J is obtained.

For example, the current angle calculator IJ is the following function generator.

17 ShiJ: KJSin-1 (ZokokoT completed)... (Formula 3) The calculated output is given to the small angle oscillator OE via the operational amplifier AMP with gain Ka.

The angular oscillator core GE is an oscillator whose output angular frequency is proportional to the input voltage, and its gain is Kg.

A voltage signal proportional to the angle is output by the angle detector DE from the output of the angle oscillator GE, and is negatively fed back to the input side of the operational amplifier AM. The relationship between the center of the phase command and the center of the detected value is 1 when there is no saturation in the constituent elements.
．． ．． ．． ．． ．． ．． (Formula 4) = 10S'KaKKg/Kg Here, K and Kg are the gains of the detector DE and the angle oscillator OE, but the gain Ka of the operational amplifier AMP should be made sufficiently large. If we take the direction value, we can see that the mind instantaneously commands the phase and responds to the mind.

Furthermore, the transient slip angle frequency center is output so that this relationship holds true.ヱ=, 10s/Ko other Kg・e ・・・・・・
(Formula 5) That is, the area within the dotted line frame in FIG. 2 can be said to be a transient slip angle frequency oscillator.

Also, if the components have nonlinearity such as saturation, (
Equation 4) does not hold partially, but in the end it holds
Since it is controlled in a centered manner, a transient slip angle frequency center that compensates for nonlinearity is output.

The transient slip angular frequency center is added to the previous slip angular frequency s, and is further input to a frequency adder FAD.

In the frequency counter FAD, the rotation angle frequency signal from the rotation angle frequency detector POS is added to the rotation angle wave number wr to create a signal similar to the rotation angle wave number of the inverter current.

■i=■S ten J ten r... (Formula 6) Figure 2 is
FIG. 3 is a block diagram of main parts of another embodiment of the present invention.

In fact, the linearity of the angle oscillator JGE has the required accuracy,
In many cases, only output saturation is a problem, and detecting a phase signal from the frequency output J of the angle oscillator core GE requires a complex detector such as a vector filter.

Another embodiment is the case where the angle oscillator JGE
The input is limited to a range within which linearity is established between input and output, and the output phase is detected by integral feedback of the input voltage, resulting in an extremely simple circuit configuration and increased practicality. FIG. 2 shows only the part from the phase command J to the output of the transient slip angle frequency center.

Other parts are similar to the embodiment shown in FIG. In FIG. 2, the output voltage of the operational amplifier AMP is the angle oscillator center G
The angle oscillator JCE is limited to a value V, L lower than the saturation input voltage VgL of E, and consideration is given to using the angle oscillator JCE in a linear region.

The phase command signal AMP' is applied to the operational amplifier AMP', and its output is integrated by the integrator INT to become an exposure voltage proportional to the detected phase, which is then negatively fed back to the input terminal of the operational amplifier AMP.

On the other hand, the output voltage center of the operational amplifier AMP is input to the angle oscillator peak GE, and a transient slip angle frequency center is obtained from the angle oscillator peak GE.

The detected phase voltage is 1. ．． ．． ．． ．． ．． (Formula 7) Shi'shin=・10S/KaK Small Kg-Ra Mountain Output voltage level of operational amplifier AMP is S.shi↓ ...(Formula 8) Shi〃J2・10S'KaKJKg KJKg (7 formula),(
Equation 8), like Equations 4 and 5, is a formula within the range where the constituent elements are directly acidic, but even if there is saturation, the final result is a Additionally, the output voltage level of the operational amplifier is also compensated.

Therefore, the transient slip angular frequency J' and the angle oscillator center G
This is because E is designed to be used in the linear range.
S }: 10 s/KaK Shows the same characteristics as Lung and Toronari (Formula 5).

In this conventional method, the current phase of the motor is compensated by applying the time differential value of the phase to a slip frequency oscillator, but with this method, the output of the differentiator and oscillator becomes saturated, making it impossible to control the phase to a predetermined value.

According to the present invention, as is clear from the above description, instead of using the time differential of the phase, the phase itself is commanded, the phase is detected from the oscillator, and feedback control is performed, so that the phase is not affected by the saturation of the component devices. A vector control device for a motor that performs control is obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the invention, and FIG. 2 is a block diagram of another embodiment of the invention. SOU... AC power supply, CONV... converter section, INV... inverter section, M...
...Induction motor, "G...Current calculator, DIV
......Divider, CS...Constant setter, S
GE...Frequency oscillator, 1 core...Current angle calculation motor, its output core, Ah center...operational amplifier, its gain K core, GE...... Angle oscillator's gain Kg, JDE... Angle detector's gain KJ, output center, FAD... Frequency adder, POS...
... Rotation angular frequency detector, INT ... Integrator, 17 ... Current command value of torque current component i7,
lm...Current command value of excitation current component lm, 1,
......Current command value of electric primary current i, Qs...slip angular frequency, core...transient slip angular frequency, r...rotation angular frequency, mountain i...angular frequency of inverter current. Figure 2 Figure 1

Claims (1)

[Claims] 1. In a device for controlling the supply current phase with respect to the internal magnetic flux of an induction motor equipped with a power supply device capable of adjusting the frequency of the supply current by feeding back the slip angular frequency with respect to the current command value, a triangular a current angle calculator that generates a voltage in proportion to the current phase angle by the calculation operation of a function; an operational amplifier that amplifies the output; an angle oscillator that generates a frequency proportional to the output; A vector for an induction motor, comprising a transient slip angle frequency oscillator comprising a control system that detects the output and provides negative feedback to the output side of the current angle calculator, and controls the output frequency of the power supply device by the output of the transient slip angle frequency oscillator. Control device.