JPH03124287A - Equivalent disturbance observer employing no speed sensor - Google Patents

Abstract

PURPOSE:To compensate disturbance by adding an equivalent disturbance including all variation factors causing influence on the operational characteristic of an object to be controlled in a speed control system to a torque command value, i.e., the input amount of the object to be controlled. CONSTITUTION:An equivalent disturbance observer 8 for compensating for all disturbances to affect influence on an object to be controlled is arranged in a speed control system for a 3-phase induction motor 6 employing no speed sensor. An equivalent disturbance compensation output is calculated based on a torque command value T* as an input amount to the object to be controlled and an estimated rotor speed N of the motor 6, and added to the value T* of the input amount to the object to be controlled thus compensating all the disturbances. Thus, all the disturbances to cause influence on a speed control and operating characteristic of the induction motor 6 can be compensated for without requiring a speed sensor.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an instantaneous torque and instantaneous flux control system for a three-phase induction motor that applies the instantaneous space vector theory, and is capable of controlling the speed without using a speed sensor of the induction motor. The speed control system of the induction motor is constructed by calculation and estimation from known information, and in order to compensate for any disturbances that are applied to the speed control system, the torque command value T", which is the human power of the controlled object, and the state quantity of the induction motor, which is the state quantity, are calculated. The present invention relates to a speed sensorless equivalent disturbance observer in which the equivalent disturbance observer is constructed from the estimated rotor speed N.

Further, details regarding the equivalent disturbance observer used in the present invention can be found in Japanese Patent Application No. 1999, filed by the applicant on June 22, 1999. -159863 "Multifunctional control device".

[Conventional technology]

In order to explain the speed sensorless equivalent disturbance observer in the speed control method for an induction motor according to the present invention, a detailed description will be given by comparing it with a conventional speed control method.

In order to control the speed of an induction motor using a space vector, as shown in the block diagram of FIG. The deviation from the command N9 is given to the control circuit 7 as a torque command value T'', and the instantaneous torque,
The speed control system was constructed by performing instantaneous magnetic flux control.

Figure 3 is a simplified block diagram of Figure 6.
In the figure, Kt is the j-lux constant, D is the viscosity coefficient, J is the inertia, S is a differential operator, and the speed command N4 is input as a command, and the speed N is output as a state quantity. The torque command value T'' is calculated from the speed command N'' which is an input quantity and the speed N which is a state quantity to perform speed control.

FIG. 4 is a simplified block diagram showing speed control using a conventional equivalent disturbance observer. It is configured as a disturbance compensator surrounded by a rectangle indicated by a dotted line, which calculates an equivalent disturbance from the command value T* and the speed N, which is the state quantity a, and adds it to the torque command value T'', which is the input quantity of the controlled object. has been done.

Each symbol Kt shown in the figure of this equivalent disturbance observer 8,
The symbols above D and J represent the nominal values of the torque constant, viscosity coefficient, and inertia, respectively.

The motor speed N, which is the state quantity handled here, uses the output signal of PG or TG as a speed sensor, as in the case of FIG. 3, and the speed sensor 9 attached to the three-phase induction motor 6 is It was essential.

[Problem to be solved by the invention]

As explained above, a speed sensor has conventionally been indispensable in a speed control system, and as mentioned above, the rotation speed signal of the induction motor is used as a state quantity when configuring an equivalent disturbance observer that compensates for all kinds of disturbances. Speed sensors were also indispensable.

That is, unless an expensive speed sensor is provided to detect the speed of the induction motor, speed control and equivalent disturbance compensation are impossible, which is extremely disadvantageous in terms of cost. Furthermore, there is a problem in that the axial dimension of the electric motor becomes large due to the mechanism and space required for mounting the speed sensor. Furthermore, consideration must be given to wiring such as noise countermeasures for the detection signals of speed sensors such as PG and TG, and overrun countermeasures are required in the event of wire breakage of the speed sensor. Many problems remained.

[Means for solving problems]

Conventionally, a speed sensor has been indispensable as a means of controlling the speed of a three-phase induction motor and as a means of equivalent disturbance compensation for disturbances including all variable factors that affect the operating characteristics. is expensive,
Due to space constraints, it has been proposed to perform speed sensorless speed control without a speed sensor.

In speed control based on instantaneous torque and instantaneous magnetic flux control using the instantaneous space vector method, we focused on the fact that the secondary flux linkage vector φ2 can be calculated from the values calculated during control.
The rotor angular frequency ω is determined from this secondary flux linkage vector −φ2 and the instantaneous torque. , and the estimated rotor speed N of the induction motor can be obtained.

The present invention uses this estimated rotor speed N to construct a speed sensorless speed control system, and also uses this estimated rotor speed N as a control amount for the equivalent disturbance observer 8 to further perform equivalent disturbance compensation that compensates for all disturbances. By also configuring a control system, it is possible to perform highly functional control of the induction motor without an expensive speed sensor.

That is, the speed sensorless equivalent disturbance observer according to the present invention includes means for converting the voltage and current of the three-phase induction motor into space vector values and calculating the instantaneous value of the primary magnetic flux vector and the current. means for calculating an instantaneous value of torque from the vector; magnetic flux comparison means for comparing the magnetic flux command value and the magnitude of the primary magnetic flux vector; - A torque comparison means for comparing the instantaneous value of the torque and a magnetic flux vector direction determination means for determining the direction of the primary magnetic flux vector, and from the outputs of the magnetic flux comparison means, the torque comparison means and the magnetic flux vector direction determination means. Judge, variable voltage.

In a method of determining the optimum output voltage of a variable frequency inverter and controlling the instantaneous torque and instantaneous primary magnetic flux of an induction motor, a secondary flux linkage vector is calculated from the primary magnetic flux vector and the primary current vector, and this The secondary angular frequency ω2 of the induction motor is calculated from the calculated value of the secondary flux linkage vector, and the slip angular frequency is calculated using the calculated value of the torque, the secondary flux linkage vector, and the secondary winding resistance. By calculating ωs, the rotor angular frequency ωs of the induction motor is ωm−ω2
−ωs, and from the torque command value T* as an input quantity of the controlled object of the speed control system and the estimated rotor speed N of the motor as a state quantity, the operating characteristics of the controlled object of the speed control system The present invention is characterized in that it is configured to calculate an equivalent disturbance including all variable factors that affect the control object, and add the equivalent disturbance to the 1-lux command value T9, which is the amount of human effort of the controlled object.

[For production]

First, a speed sensorless speed control system for a three-phase induction motor based on instantaneous torque 7 and instantaneous magnetic flux control using the instantaneous space vector method will be explained with reference to FIG.

FIG. 2 shows the speed sensor 9 removed and blocks 714 to 7
16 is added, the block diagram is the same as the speed control block diagram of an induction motor using a space vector shown in FIG.

Power is supplied from a DC power supply 1 to a three-phase induction motor 6 via a power switch 4, a positive bus 1a and a negative bus 1b, and a three-phase PWM inverter 3. The control circuit 7 processes the command and the detected current and voltage signals, and generates an energization signal for the switching elements of the PWM inverter 3. 2 is a voltage detector of the DC power supply l; 5u, 5v, 5- are current detectors that respectively detect the instantaneous values of the currents of each phase of the induction motor 6; Su, Sv, S are PWM inverters; The switching elements of each phase are represented by one changeover switch.

Blocks 701 and 703b calculate the primary voltage vector V from the voltage of the DC power supply l and the states of the changeover switches Su to S8.
, and in block 702 each phase current i, xi
, the primary current vector 11 is calculated from .

Primary voltage vector V+ Primary current vector i+ and 1
An instantaneous primary magnetic flux vector φ1 is calculated from the secondary resistance value R1.

In block 707, an instantaneous torque value T is calculated from the primary magnetic flux vector φ1 and the primary current vector 11.

In blocks 706, 708 and 711, the magnetic flux command value φ1 is compared with the magnitude φ1 of the primary magnetic flux vector φ1,
In blocks 709 and 712, the torque command value T'' is compared with the instantaneous torque value T, and in block 710, the direction of the primary magnetic flux vector φ1 is determined.

Based on the outputs of these magnetic flux comparison means, torque comparison means, and magnetic flux direction determination means, a block 713 judges and determines the optimum output voltage of the PWM impark 3, and calculates the instantaneous torque and instantaneous primary magnetic flux of the induction motor 6. Control.

In block 714, the primary flux vector φ, and from 2
By calculating the secondary angular frequency ω2 and calculating the slip angular frequency ωs from the instantaneous value T of the torque and the secondary flux linkage vector φ2, the rotor angular frequency ωs of the induction motor is set to ωo 8ω2 in the processor 715. Calculate as −ωs.

In block 716, the estimated rotor speed N of the induction motor is determined from the number of poles p of the motor and the rotor angular frequency ωs as N=1200 m/p.

This estimated rotor speed N is used as feedback to the speed control system, and is subtracted from the speed command N'' in block 717, and output to block 709 in the torque comparison means as a torque command value T9 as an input amount to the speed control system. .

The aforementioned speed sensorless speed estimation method for an induction motor is detailed in Japanese Patent Application No. 114094 filed by the applicant of the present invention.

As shown in the simplified control block diagram of FIG. 5, the present invention compensates for any disturbances that affect the controlled object in the speed sensorless speed control system of the three-phase induction motor shown in FIG. An equivalent disturbance observer 8 is configured, and an equivalent disturbance compensation output is calculated from the torque command value T1 as the input quantity of the controlled object and the estimated rotor speed N of the three-phase induction motor as the state quantity, and the equivalent disturbance compensation output is calculated as the input of the controlled object. By adding it to the torque command value T1, which is a quantity, all disturbances are compensated for.

Here, the operation of the equivalent disturbance observer will be explained using FIG. 4 again.

The equivalent disturbance observer 8 detects the torque command value T1, which is the deviation between the speed command N9 and the speed N, and is the input amount of the controlled object.
and speed N, which is a state quantity, to calculate an equivalent disturbance, and add this to the torque command 1 2 value T9.

There is a relationship between the load disturbance Tdis(S) and the motor rotational speed ω(S) with respect to the torque command value T″(S).
KL −Tdis(S) = (JS−1−D)ω(S
) ■ holds true.

Here, taking into account the variation of the parameters, the following is set.

However, as described above, one sign represents a nominal value, and Δ represents a variation.

Substituting equation 0 into equation 0, the equivalent disturbance TE (S) is equation 0 % equation % Therefore, the physical content of equation 0 is that the equivalent disturbance TE (S) includes the load disturbance Td i , (s) and each constant. It includes all the errors due to the nominal values, and by considering them as equivalent disturbances, it is shown that the equivalent disturbance observer 8 can be constructed using only the nominal values of each constant as shown on the right side of equation 0. There is.

For this reason, the equivalent disturbance observer 8 is controlled by the controlled object simulation calculation unit 81 . Torque simulation calculation section 82. By comprising the subtraction section 83, the torque simulation inverse operation section 84, and a low-pass filter (not shown), it is possible to compensate for all kinds of disturbances.

That is, the speed N, which is a state quantity, is input to the controlled object simulation calculation section 81 (JS+D'l is calculated), and the torque command value T9, which is the input amount of the controlled object, is inputted to the torque simulation calculation section 82 ( Kt) is calculated, and in the subtraction unit 83, the output of the controlled object simulation calculation unit 81 is subtracted from the output of the torque simulation calculation unit 82, and the result is passed through a low-pass filter (not shown).

This is to remove noise from the equivalent disturbance TE (s) that is the output of the subtractor 83. The output of the subtraction unit 83 after passing through the low-pass filter is input to the torque simulation inverse calculation unit 84, and the calculation 13 4 of 1/Kt) is performed, and the output is used as the output of the equivalent disturbance observer 8 to command the torque that is the input amount of the controlled object. Add to value T9,
Equivalent disturbance compensation is performed by setting the true torque command value.

FIG. 5 shows a block diagram when the equivalent disturbance observer 8 in FIG. 4 inputs the estimated rotor speed N instead of the actually measured speed N as the state quantity.
Speed performance is performed without a speed sensor, and the speed control system and equivalent disturbance compensator are operated based on the estimated rotor speed calculated by the calculation.

〔Example〕

An example in which the speed sensorless equivalent disturbance observer of the present invention is applied to a speed sensorless speed control system of an induction motor will be described below.

FIG. 1 is a block diagram of an embodiment of a speed control system that performs compensation control for all kinds of disturbances to which the speed sensorless equivalent disturbance observer of the present invention is applied, and the same reference numerals as in FIG. 2 indicate the same functional parts. The only parts added to FIG. 2 are the equivalent disturbance observer 8 surrounded by a dotted line and an addition block 718 that adds its output to the torque command value T*. Therefore, in this embodiment, only these will be explained.

The estimated rotor speed N output from block 716 is input to the controlled object simulation calculation unit 81 of the equivalent disturbance observer 8.
JS+D) and block 709
The true torque command value 'F'', which is the output of the addition block 719 sent to
The calculation is performed. A subtraction unit 83 in the equivalent disturbance observer 8 subtracts the output of the controlled object simulation calculation unit 81 from the output of the torque simulation calculation unit 82 to obtain an equivalent disturbance TE (s).
get. The output of this subtraction section 83 is passed through a low-pass filter (not shown) and then sent to a torque simulation inverse calculation section 84 (
1/Kt) and sends it to addition block 718.

Addition block 718 adds the temporary I.
The torque simulation calculation unit 82 adds the output of the torque simulation inverse calculation unit 84 to the torque command value T1 and obtains the true torque command T′″.
At the same time, the signal is sent to block 709 in the control circuit 7 to configure a speed sensorless speed control system.

By configuring as described above, it is possible to perform compensation control for all kinds of disturbances without affecting the speed control and driving characteristics of the induction motor without a speed sensor.

〔Effect of the invention〕

Conventionally, when performing various types of control on induction motors, expensive speed sensors such as PG and TG were indispensable to detect the actual speed of the induction motor, but with the speed sensorless equivalent disturbance observer of the present invention, A high-performance speed sensor-less control method can be provided.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of a speed control system for an induction motor using a space vector to which the speed sensorless equivalent disturbance observer of the present invention is applied, and Fig. 2 is a block diagram of an example of a speed control system for an induction motor using a conventional space vector. Block diagram. Figure 3 is a simplified block diagram of the basic speed control system for an induction motor using a conventional speed sensor. Figure 4 is a simplified diagram of the speed control system using an equivalent disturbance observer for an induction motor using a speed sensor. Block diagram: Figure 5 is a simplified block diagram of a speed control system for an induction motor to which the speed sensorless equivalent disturbance observer of the present invention is applied; Figure 6 is an example of a speed control system using a space vector for an induction motor using a speed sensor. It is a block diagram. ■...DC power supply 1a...Positive bus 1b...
- Negative bus 2...Voltage detector 3...Voltage PWM inverter 4...Power switch 5u, 5v, 5cm...Current detector 6...3-phase induction motor 7...Control circuit 8 Equivalent disturbance observer 9 Speed sensor 81 Controlled object simulation calculation section 82 Torque simulation calculation section 83 Subtraction section 84 Torque simulation inverse calculation section 718 Addition block 7

Claims (1)

[Claims] Means for calculating the instantaneous value of the primary magnetic flux vector by converting the voltage and current of the 1- and 3-phase induction motors into space vector values, and calculating the torque from the primary magnetic flux vector and the current vector. A means for calculating an instantaneous value, a magnetic flux command value, and the above-mentioned 1.
magnetic flux comparison means for comparing the magnitude of the next magnetic flux vector;
A torque comparison means for comparing a torque command value and the instantaneous value of the torque, and a magnetic flux vector direction determination means for determining the direction of the primary magnetic flux vector, the magnetic flux comparison means, the torque comparison means, and the magnetic flux vector direction determination means. In a method of determining the optimum output voltage of a variable voltage, variable frequency inverter based on the output of the means and controlling the instantaneous torque and instantaneous primary magnetic flux of an induction motor, 2
A secondary magnetic flux linkage vector is calculated, and a secondary angular frequency ω_2 of the induction motor is calculated from the calculated value of this secondary magnetic flux linkage vector. The slip angular frequency ω_s is calculated using the winding resistance, and the rotor angular frequency ω_m of the induction motor is calculated as ω_m=ω_2−ω_s, and the torque command is obtained as the input quantity of the controlled object of the speed control system. From the value T^* and the estimated rotor speed of the motor as a state quantity, an equivalent disturbance including all variable elements that affect the operating characteristics of the speed control system controlled object is calculated, and the equivalent disturbance is A speed sensorless equivalent disturbance observer characterized in that it is configured to add to a torque command value T^* which is an input amount of a controlled object.