JP3431601B2 - Control method and device for sensorless induction machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor magnetic flux adjusting method and apparatus.

[0002]

2. Description of the Related Art Generally, when the speed of an induction motor is calculated from the detected primary voltage and primary current, it can be explained as follows by the equations (1) and (2) of the steady state of the induction motor.

[0003]

Here, R1: primary resistance, R2: secondary resistance, M: mutual inductance, L1: primary self-inductance, L2: secondary self-inductance, ω: primary angular frequency, ωs: slip angular frequency, V: primary Voltage vector,
I1: primary current vector, I2: secondary current vector. If the primary voltage vector V, the primary current vector I1, and the primary angular frequency ω are obtained, the secondary current I2 can be obtained from the equation (1), and the slip angular frequency ωs can be obtained by substituting it into the equation (2). Therefore, the rotational speed ωm of the induction motor can be calculated by the equation (3). ωm = ω−ωs (3)

[0005]

When the rotational speed of the induction motor is obtained by detecting the primary voltage and the primary current supplied to the induction motor as described above, if the primary angular frequency ω is 0, (1) The secondary current vector I2 cannot be obtained from the equation, and the slip angular frequency ωs cannot be obtained from the equation (2). Therefore, the rotational speed ωm cannot be obtained from the equation (3). The present invention was devised in view of the above-mentioned points, and an object thereof is to provide a control method for a sensorless induction machine and a device therefor capable of promptly avoiding a state in which a rotational speed cannot be calculated.

[0006]

[Means for Solving the Problems] That is, the means for achieving the object are as follows: 1) In claim 1, a sensorless device for controlling the torque and magnetic flux of the induction motor without using the information on the rotational speed of the induction motor. In the induction motor control method, two magnetic flux commands, large and small, are prepared, and when the torque command is positive, either 1 or -1 is multiplied by the frequency of the primary current of the induction motor. The value fx is calculated, and this value fx is the predetermined frequency f0.
If it is smaller than the above, select the larger magnetic flux command,
When the fx is equal to or greater than the f0, the smaller magnetic flux command is selected, and the torque and the magnetic flux of the induction motor are controlled based on the magnetic flux command and the torque command. Is.

2) According to a second aspect of the present invention, there is provided a controller for a sensorless induction machine, which controls torque and magnetic flux of the induction motor without using information on the rotational speed of the induction motor, and which has two magnetic flux commands, large and small, and torque. When the command is positive, 1 when the command is negative, -1 is multiplied by the frequency of the primary current of the induction motor to obtain a value fx, and a value f which is the output of the multiplier.
a magnetic flux command selector for selecting the larger magnetic flux command when x is smaller than a predetermined frequency f0, and for selecting the smaller magnetic flux command when fx is greater than or equal to f0. A control device for a sensorless induction machine, characterized in that the torque and the magnetic flux of the induction motor are controlled based on the magnetic flux command of the output of the command selector and the torque command. An embodiment of the control method and apparatus of the present invention will be described below in detail with reference to the drawings.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of claims 1 and 2 of the present invention, which will be described below with reference to this drawing.
The control device of the present invention is provided with two large and small magnetic flux commands, and when the torque command is positive, when the torque command is negative, -1 is multiplied by the frequency of the primary current of the induction motor 2 to obtain a value fx. If the value fx which is the output of the multiplier 53 and the multiplier 53 is smaller than a predetermined frequency f0, the larger magnetic flux command is selected, and if the fx is equal to or larger than the f0, the smaller magnetic flux command is selected. A sensorless induction machine comprising: a magnetic flux command selector 5 for selecting; controlling the torque and magnetic flux of the induction motor 2 based on the magnetic flux command output from the magnetic flux command selector 5 and the torque command. It is a control device.

The control method will be described below with reference to this control device. That is, the power converter 1 supplies electric power to the induction motor 2. The torque magnetic flux controller 3 sends a control signal such that the output torque of the induction motor and the magnetic flux follow the input torque command T * and magnetic flux command φ * to the power converter 1.
Output to. The current frequency calculator 4 calculates and outputs the frequency f of the current detected by the induction motor 2. This may be the frequency f of the voltage or the frequency of the magnetic flux instead of the frequency of the current. If the torque magnetic flux controller 3 has a signal that is constantly equivalent to the frequency of the current, the signal may be used.

In the magnetic flux command selector 5, the polarity discriminator 5
The polarity of the torque command T * is determined by 5 and the product with the frequency f is calculated by the multiplier 53 to obtain the value fx. Adder / subtractor 5
4 and the polarity discriminator 51 and the selector 52, when fx is smaller than the predetermined frequency f0, φ1 * is selected and output as the magnetic flux command φ *. When f0 <fx, φ2
Select * and output as magnetic flux command φ *. In this case φ
There is a relationship of 1 *> φ2 *. Generally f0 is -0.1 Hz
It is negative and has a very small value.

The reason why the drawbacks of the prior art can be solved by the present invention will be described below. For example, consider the case where T *> 0 and the frequency f is f <f0. In this case, the large magnetic flux command φ1 * is selected. Generally, the slip frequency is inversely proportional to the square of the magnitude of magnetic flux. Therefore, when φ1 * is selected, the slip frequency is small. When the vehicle decelerates in this state and the frequency f becomes 0>f> f0, the small magnetic flux command φ2 * is selected, and the slip frequency fs
Grows larger.

From this, f = fm + fs
Since the rotation speed does not change abruptly, the frequency f suddenly changes to the positive side. If this amount of change is larger than the absolute value of f0, f> f0 can be set to f> 0. . That is, the frequency f = 0 can be quickly passed. Here, fm is a frequency corresponding to the rotation speed. From the above, the state of frequency f = 0 becomes very short, that is, the state of primary angular frequency ω = 0 becomes very short,
It is possible to quickly avoid the situation where the rotation speed cannot be calculated when ω = 0.

[0013]

As described above, according to the present invention, it is possible to quickly avoid a state in which the rotation speed cannot be calculated.
It is extremely useful.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Power converter 2 ... Induction motor 3 ... Torque flux controller 4 Current frequency calculator 5 ... Magnetic flux command selector 51 ... Polarity discriminator 52 ... Selector 53 ... Multiplier 54 ... Adder / subtractor 55 ・ ・ ・ Polarity discriminator

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02P 5/408-5/142 H02P 7/628-7/632 H02P 21/00 H02P 6/00-6 / 24 H02P 1/00-1/58 H02M 7/42-7/98

Claims (2)

(57) [Claims] 1. A sensorless induction machine control method for controlling torque and magnetic flux of the induction motor without using information on the rotational speed of the induction motor, wherein two magnetic flux commands, large and small, are prepared and the torque command is positive. A value fx is calculated by multiplying the frequency of the primary current of the induction motor by either 1 for negative 1 or -1 for negative, and if the value fx is smaller than a predetermined frequency f0, the larger magnetic flux command. And select fx
Is greater than or equal to the f0, the smaller magnetic flux command is selected, and the torque and magnetic flux of the induction motor are controlled based on the magnetic flux command and the torque command. 2. A controller for a sensorless induction machine, which controls torque and magnetic flux of the induction motor without using information on the rotational speed of the induction motor, has two magnetic flux commands of large and small, and 1 when the torque command is positive. When negative, a multiplier that obtains a value fx by multiplying the frequency of the primary current of the induction motor by -1 and a value fx that is the output of the multiplier is a predetermined frequency f.
A magnetic flux command selector that selects the larger magnetic flux command when the value is smaller than 0, and selects the smaller magnetic flux command when the fx is greater than or equal to f0, and the output of the magnetic flux command selector A controller for a sensorless induction machine, which controls the torque and the magnetic flux of the induction motor based on the magnetic flux command and the torque command.