SU1640808A1 - Device for sensing angular position of shaft of two-phase synchronous motor with magnetically unbalanced rotor - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to simplify by using identical in composition functional circuits for generating output voltages. To this end, the device for determining the angular position of the shaft of a two-phase synchronous motor with magnetic asymmetry of the rotor includes 3 and 4 phase EMF shapers, adders 13 and 14, and a phase-sensitive rectifier 12. At the outputs of adders 8 and 14, t voltages are generated that vary according to the laws of cosine and sine of the double angle of rotation of the rotor of a synchronous motor, the inputs of the formers 3 and 4 are connected to different circuits. 1 Cp f-ly, 4 ill. with SS

Description

ABOUT

4 O 00

About 00

The invention relates to electrical engineering, namely, devices for controlling synchronous motors with different values of the longitudinal and transverse inductances of the stator phase windings can be used in electric drives in which, from the requirements for design and operation, it is impossible to install a separate rotor angle sensor. engine

The aim of the invention is to simplify by using identical in composition functional circuits for generating output voltages as well as improving the shape of the output voltages by eliminating the output voltage ripple.

FIG. Figure 1 shows the functional diagram of the device for determining the angle of the shaft position of a two-phase synchronous motor, in Figures 2-4, the main components of the device.

The device for determining the angular position of the shaft of a two-phase synchronous motor contains the first 1 and second 2 velocity meters for changing the phase current, the first 3 and second 4 formers of phase EMF, the first 5 and second 6 formers of reference voltages, the first 7 and second 8 adders, first through the fourth phase-sensitive rectifiers 9–12 and the third 13 and the fourth 14 adders. Meters 1 and 2 and drivers 3 and 4 are connected to the phase circuits of a synchronous motor (not shown) with their input circuits. The outputs of the meter 1 and the driver phase EMF. 3 are connected to the input of the adder 7, the outputs of the meter 2 and the phase emulator 4 are connected to the inputs of the adder 13.

The inputs of the driver 5 and 6 of the reference voltage are connected to the outputs of the meters 1 and 2 of the speeds of changing the phase current of the synchronous motor. The output of the adder is connected to the amplitude inputs of the phase-sensitive rectifiers 10 and 11, and the output of the adder 13 to the amplitude inputs of the phase-sensitive rectifiers 9 and 12 o The reference inputs of the rectifiers 9 and 11 are connected to the output of the reference voltage forcing 6, and the reference inputs of rectifiers miteles 10 and 12

5 0 5

0

connected to the output of the driver 5 of the reference voltage. The outputs of the phase-sensitive rectifiers 9 and 10 are connected to the inputs of the adder 8, and the rectifiers 11 and 12 to the inputs of the adder 14.

At the outputs of adders 8 and 14, voltages are generated, varying according to the laws of cosine and sine of the double angle Q of rotation of the rotor of a synchronous motor, respectively. These voltages are used in an electric drive to generate an electromagnetic moment.

To improve the shape of the output voltages by reducing the level of pulsating voltages in them, the device is additionally equipped with fifth and sixth adders 15 and 16 and the first and second RC filters 17 and 18. The first inputs of the adders 15 and 16 are connected respectively to the outputs of the meters 1 and 2 speeds of change of the phase current, and the second inputs - to the outputs of the formers 3 and 4 of the phase emf.

The adder 15 is connected in series with the filter 17, the output of which is connected to the third input of the adder 7. The adder 16 is connected in series with the filter 18, the output of which is connected to the third input of the adder 13.

The secondary windings of smoothing chokes in the phase circuits of a synchronous motor and additional measuring phase windings of this engine can be used as measuring instruments for the rate of change of the phase current and formers of the phase EMF. Instead of chokes, you can use differentiated output voltages of phase current meters.

The reference voltage drivers can be made on two operational amplifiers 19 and 20 (Fig. 2) and resistors with resistance r in the input and output circuits.

The first stage (operational amplifier 19) is made according to a scheme with positive feedback and serves as a square voltage driver. The second stage (operational amplifier 20) is made according to the usual-amplifier circuit with a gain equal to one,

and serves as a voltage inverter. The input voltage UgX comes from a rate meter of 1 or 2 phase currents. Output Voltages U

6S

and -U

Bych perform the role of

reference voltages for phase sensitive rectifiers 9-12.

Each adder included in the device is a conventional linear voltage amplifier circuit based on operational amplifier 21 (Fig. 3) with two resistors with resistances r and R at the output and a resistor with resistance RJ in the feedback circuit. Depending on the location, voltages U6Ji come to the inputs of the adder (n U61 (ii either from meter 1 and shaper 3, or from meter 2 and shaper 4, or from the outputs of phase-sensitive rectifiers 9 and 10, 11 and 12. At the same time, The goal of reducing the noise level with the frequency f, coming from the outputs of phase-sensitive rectifiers, uses capacitors in the feedback circuits of the adders 8 and 14, i.e., combining the summation functions with the filtering functions.

Phase-sensitive rectifiers can be built on an operational amplifier 22 (FIG. 4) with a switch 23 in the input circuit. If the amplitude input of the phase-sensitive rectifier has a voltage UQ, constant in value, and its reference input (control input key 23) receives the alternating voltage Uon, then the output voltage

U

8S

will be alternating and meaningful

its proportion is proportional to ua. If the voltage UQ is a variable voltage of frequency f and the voltage U op also has a frequency f, then a constant voltage is formed at the output of the phase-sensitive rectifier with a value proportional to the value of voltage U ..

The formation of voltages at the outputs of the device, varying according to the laws of sin 20 and cos 20, is considered on the example of a two-phase synchronous machine with excitation from permanent magnets, the phase circuits of which are powered by current amplifiers built on semiconductor switches switching with frequency f. In this case, in phase circuits

bodies flow pulsating currents of frequency f. These currents create voltage drops across the main and mutual inductances of the motor phases. Among these voltages are components that vary in accordance with the laws of cos 2Q and sin 20, where 9 is the angle of rotation of the engine.

For phase voltages U and Uq of a two-phase synchronous motor, the terms

15

20

(one)

Where

25

thirty

35

phase inductance g;

t. - dax LMHH

h 2

sin

2940

mutual inductance of stator windings f and g;

Jmmh

five

0

1 max

4d

H a max

T make

- minimum and maximum inductance of stator windings f and g

cos 9 - mutual inductance of the winding f with the winding d of the rotor along the longitudinal axis,

sin9 is the mutual inductance of the winding g with the winding d of the rotor; maximum mutual inductance of any stator winding with winding d of the rotor.

When considering a synchronous motor with magnets on the rotor (DBM) in the mathematical description

Lhwakc

instead of the magnetizing force of the magnet, the magnetizing force of the fictitious winding d of the rotor is used, considering that a direct current flows through it.

In DBM Lmaco-, UL is a significant value (not less than 510% of L0 -JlMfflb | ± L "M). Availability

AL characterizes the difference of magnetic resistances along the longitudinal d and transverse q of the axis of the rotor.

After substituting the values of inductances in (1) and transformations, we obtain

cos29

sin2Q

U - Ґ4 -1F L ° + W MaKe sinGX. Ch-no. +

FM + 1, .0, W4 + (.,.

A19

+ (s-L "- VS, -L

Where

Ј2i - rotor speed

 synchronous motor. Expressions (2) for the sin 29 and cos 2Q functions are very cumbersome and their full implementation leads to a rather complicated circuit of the device. The functional diagram of the device is constructed according to the expressions obtained under certain assumptions (E di t N. Ik. DU

cos 2G

dt

lv

dt

(Efl di $

3 dt

t h UL .dig.

(3)

sin

{п оо / р .. ц т AL.lis-

in 2 - tE1 dt -L0) Y dt

(v di $ v & L di.Ј (EG dT

where E is the emf of phase f,

including the EMF of the transformation and the EMF of rotation, E Un-ij-Rc) - the EMF of the phase §. Upon receipt (3) accepted

j 2

liЈ

dt

ia.Q,}

,

1MIX

cost

C) sAM + c.s2, w

2 dt

Since the rates of change of the currents ii and in at the switching frequencies f of the power switches of the phase current amplifiers feeding the phase circuits of the synchronous motor are significantly higher than the rates of change of these currents at the rotational frequencies J2t.

0

five

0

five

Also, it is taken into account that the voltage ij-Q, IMdMQKC-sin0 and i b, 1 L1dMQKe cos 9 is a voltage of relatively low frequency G2 and essentially represent phase EMF-rotations. If these voltages are not formed, as was done in the voltages (3), then this results in the appearance of pulsations of the frequency f at the outputs of the phase-sensitive rectifiers. These pulsations are easy to filter using capacitors in reverse circuits of adders 8 and 14, as discussed above. In addition, it is taken into account that the voltages in the denominators of expressions (2) reflect only the scale of the voltages obtained, varying according to the laws of sin 20 and cos 2b. Thus, the device is simple to implement and has an accuracy of voltages varying according to the laws of sin 2b and

cos 20, is quite sufficient for use in the circuits of real electric drives.

Claims (2)

1. Device for determining the angular position of a shaft of a two-phase synchronous motor with magnetic asymmetry of a rotor, containing two measuring instruments for the rate of change of phase current with inputs for connecting a synchronous motor to the corresponding phase terminals, two reference voltage formers, the input of one of which is combined with the first input of the first adder and connected to the output of the first meter of the rate of change of the phase current, the input of the second driver of the reference voltage is connected to the output of the second meter of the speed and phase current changes, three phase-sensitive rectifiers, the combined reference inputs of the first and third and the reference input of the second phase-sensitive rectifiers are connected respectively to the outputs of the second and first formers of the reference voltages, and the outputs of the first and second phase-sensitive rectifiers are connected to the corresponding inputs of the second adder, the output which forms the first output of the device, on which a voltage is formed, varying according to the cosine law of the two legs about the angle of rotation of the rotor of the synchronous motor The device is equipped with a second output, at which a voltage is formed, varying according to the sine law of the double rotation angle of the rotor of the synchronous motor, the output of the first adder is connected to the amplitude input of the third phase-sensitive rectifier, characterized by the fact that by using the same n composition of the functional schemes for the formation of the aforementioned output voltage s ten 15 20 25 55 40 15 080810 two phase forcing emf with inputs for connecting to the corresponding phase outputs of a synchronous motor, the third and fourth adders and the fourth phase-sensing rectifier, the reference input of which is connected to the output of the first voltage-generating unit, the amplitude input is combined with the amplitude input of the first phase sensing - rectifier and connected to the output of the third adder, the inputs of which are connected respectively to the outputs of the second meter of the rate of change of the phase current and driver the emf, the output of the first phase voltage emf is connected to the second input of the first adder, the output of which is connected to the amplitude input of the second phase-sensitive rectifier, and the outputs of the third and fourth phase-sensitive rectifiers are connected respectively to the inputs of the fourth adder, the output of which forms the second output of the device . 2. The device according to claim 1, characterized in that, in order to improve the improvement of the shape of the output voltages by eliminating pulsations, the first and third adders are provided with third inputs and a fifth adder connected in series and a first filter and a sixth adder connected in series and a second filter , while the inputs of the pdd adder are connected to the outputs of the first meter measuring the rate of change of the phase current and the phase emulator, and the inputs of the sixth adder to the outputs of the second meter measuring the rate of change of phase current and Atel phase emf, and the outputs of the first and second filters are connected to third inputs of the first and third adders. thirty UVH.1 gЈ-gN-, R Shh.g YaMSHN Uafr- r 4 you FIG. 2 # & / FIG. t / Bmx.