JPS6040278B2 - Induction motor speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for an induction motor, and more particularly to a speed control device for a wound induction motor that performs speed control using a supersynchronous Servius method.

When controlling the speed of an induction motor using the super-synchronous Servius method, the gate signal of the static converter connected to the secondary side of the induction motor must be synchronized with the secondary voltage of the transfer motor. , it is necessary to detect this secondary voltage.

However, the secondary voltage becomes approximately zero when the transfer machine rotates around the synchronous speed, and the voltage cannot be directly extracted. To solve this problem, methods using Hall elements, photodetectors, and even mechanical commutators have been proposed, but Hall elements have poor temperature characteristics and There were problems such as being easily influenced by magnetic fields. Further, when a photodetector is used, a detection section for three phases is required, and the output phase of the detector must be electrically shifted by 12. The purpose of the present invention is to eliminate the above-mentioned drawbacks. To achieve this purpose, a detection means consisting of two slit disks is provided on the rotor of an induction motor, and the induction It is characterized by speed control based on the output voltage synchronized with the secondary voltage of the electric motor.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

Before explaining the embodiments, the principle of the present invention will be described.

Now, if the angular velocity of the rotating magnetic field of the induction motor is w, the rotational speed of the rotor is 2, and the rotational speed of the secondary voltage is s, then
COS St ni COS (no・1 no 2) t ni COS l
tCOS's 2t Ten Sin's Itsin's 2t...{・} ■S(St+Kumuchi＞=S(■lt-'s 2t Juzuma)
COS (It's Totsuma) COS thing's Totsuma. t+
2t of cloud water > Sin...■■S (■St+vine water) = S
(lt - 2t 10 extra): COS (■lt + listen) C
OS's 2t+Sinkunolt+sage) Sin's 2t...
(It will be 31.

Therefore, the speed of the induction motor can be controlled by using the control voltage determined by the above equations (1}, '2}, {31) as the control amount of the static converter connected to the secondary side of the induction motor. FIG. 1 is a circuit block diagram of a speed control device for a power transmission motor according to the present invention.

1 is a main induction motor (hereinafter abbreviated as IM); 2 and 3 are a slit disk for phase detection and a slit disk for rotational angle detection, respectively attached to the rotor shaft of this IMI; 4, 5
are a first slit position detector and a second slit position detector arranged near the slit disks 2 and 3 to detect the position of the slit, respectively.
This is a slit position detector.

These slit position detectors are implemented optically, magnetically, or using a Hall element. 10 is an arithmetic circuit, and in this arithmetic circuit 1, 6 and 7 are converters that convert the outputs from the slit position detectors 2 and 3 into frequency outputs.

12, 14, and 16 are multiplication units each including a pair of multipliers;
81 is an adder that performs addition of multipliers 12A and 12B, 18
Adder 18 that performs addition of 0' multipliers 14A and 14B
The prisoner is an adder that performs addition of multipliers 16A and 16B,
As the output of these adders 181, 180, 18m, c
os (no s), cos (similar t Tozumatake), ■S (no St+
It is configured so that it can be used as a light.

FIG. 2 is a block diagram showing the internal configuration of the converters 6, 7 and the multipliers 12, 14, 16.
2' is an up/down counter, 24, 24' are polarity conversion circuits for positive/negative switching amplifiers 26, 26', 28, 28' are analog switches, and 30 is a dividing circuit.

The reset pulse is obtained by the slit disk 2 attached to the rotor shaft of the plate 1 described above, and by changing the position of this disk 2, an output voltage matching the phase of the secondary voltage can be obtained. This output voltage (2t of sin, 2t of cosine) matching the phase of the secondary voltage is the power supply voltage {
cos. t, ■S (of. t + cloud), S of (of . t + cloud)}, and satisfy each term on the right side of formula m, '21, {31. :1
6A and 16B, the outputs of multipliers 12A and 12B are added to adder 181, the outputs of multipliers 14A and 14B are added to adder 1801, and the outputs of multipliers 16A and 16B are added to adder 18m. , three-phase output voltages cos(■st), cos(St+word), and ■S(St+10) having the same phase and frequency as the secondary voltage are obtained, respectively.

As described above, the speed control device for an induction motor according to the present invention includes a detection means consisting of two slit disks provided in the rotor of the induction motor, and the detection means detects the rotation speed as a pulse number. Therefore, there is no distortion of the detected waveform due to ambient temperature, magnetic field, etc., which occurs when a Hall element or the like is used, and an output matching the phase of the secondary voltage can always be obtained.

Further, there is no variation in the detection characteristics of the detection means described above, and speed control based on highly accurate detection can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a speed control device for an induction motor according to the present invention, and FIG. 2 is a block diagram showing the internal configuration of a part of the arithmetic circuit shown in FIG. 1. 1... Induction motor, 2, 3... Disc with slit, 6y 7... Converter, 10... Arithmetic circuit, 12, 14, 16... Multiplier, 181,180,
18m...Adder. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. In a speed control device for an induction motor that performs speed control using the super-synchronous Servius method, a detection system comprising a slit disk for phase detection and a slit disk for rotation angle detection provided on the rotor of the induction motor. a first slit position detector and a second slit position detector for detecting the slit positions of the slit disk for phase detection and the slit disk for rotation angle detection, respectively;
a slit position detector, and a counter that takes the pulse signal from the first slit position detector as a reset input and counts the pulse signal from the second slit position detector, and A speed control device for an induction motor, comprising a converter that outputs a voltage signal, and a control means that performs speed control based on the output voltage of the converter. 2. The control means calculates a control voltage for three phases by calculating the output voltage and the primary three-phase voltage, and uses the calculated output to control a static converter connected to the secondary side of the induction motor. 2. The speed control device for an induction motor according to claim 1, further comprising an arithmetic circuit for calculating the speed of the induction motor.