SU1205020A1 - Device for monitoring rotational speed of electric machine - Google Patents

Description

The invention relates to the measurement of the speed of electric machines and can be used in various systems for monitoring the rotational speed of electrical units, for example, in diagnostic systems and autocontrol.

The aim of the invention is to expand the range of controlled products.

On. functionality on the device diagram is presented; 2 shows timing diagrams explaining the principle of operation of the device; Fig "3 is an embodiment of a tunable comb filter; in Fig. A, the pulsation spectrum and frequency characteristics of a tunable comb filter in various modes of operation.

The device contains a clock generator 1, a second counter 2, a trigger 3, the first elements AND 4, a register 5, a display unit 6, a tunable generator 7, a sawtooth generator 8, a peak detector 9, a tunable comb filter 10, a pulsation sensor 11 current, the adder 12, the first and second keys 13 and 14, the first and second integrators 15 and 16, the first and second comparators 17 and 18, the second and third elements And 19, 20, the element OR 21, the first and second elements 22 and 23 of the delay , first counter 24 and notch filter 25.

The tunable comb filter 10 contains bandpass filters 26, each of which is implemented on an operational amplifier 27 with frequency reference capacitors 28 and 29, a field effect transistor 30 and an suppressor voltage divider consisting of a resistor 31 and a potentiometer 32.

Letters from A to P are designated points on the functional diagram (Fig.) Which correspond to the timing diagrams in Fig.2. The positions C and O denote the counting and zero inputs of the counters and the trigger, respectively.

Figure 4 shows the signal spectrum at the output of the pulsation sensor 11, the X, Y, Z, W denotes the frequency characteristics of the tunable comb filter 10 at periods of time 5 indicated similarly in the time diagrams of FIG. 2.

The principle of the device is a gradual restructuring

a comb filter with simultaneous automatic control of the voltage at its outputs until the maximum total signal of all components of the spectrum is obtained, after which the frequency of the first component of the pulse spectrum is indicated. .

Us; the trio works in the following way.

The pulses of the clock generator 1 are fed to the counting inputs G of counter 2, trigger 3, and through the delay element 23 after a time equal to the period of repetition of clock pulses to counter 24, odd-numbered pulses are generated at the forward output of trigger 3; (diagrams B, C in Fig. 2. Counter 2 counts the number of incoming clock pulses and accordingly tunes the tunable generator 7, which forms a sequence of pulses with a follow-up period constant within the clock cycle, but increasing ms with each subsequent cycle (diagram D in Fig. 2). The pulses from the output of the generator 7 start the generator 8 of the sawtooth voltage, the amplitude of the sawtooth pulses (diagram e) is proportional to the period of the pulse of the generator 7. The peak detector 9 generates a constant voltage, proportional to the amplitude of the sawtooth pulses, which is controlled by the tunable comb filter 10. The latter extracts from the spectrum of pulsations received at its input from sensor 11 through filter 25, those spectral components that orye set his comb filters. From the outputs of these filters, the voltage is applied to the adder 12, at the output of which a constant voltage is formed, proportional to the sum of the amplitudes of the spectral components separated by the comb filter. This voltage is supplied via switch 13, which is in a closed state by the voltage applied to it from the direct output of flip-flop 3, to integrator 15. The integrator remembers the maximum voltage applied to its input, which is compared with the output voltage second integrator. Because

in this cycle the first of them exceeds the second, then at the output of the comparator 17 there is a low level signal, as a result of which the signal at the output of element 19 also has a low level. At the output of the comparator 18, on the contrary, a high level signal appears, however, at the output of the And 20 element, the signal has a low level, since its second input has a low level voltage from the inverse output of trigger 3.

Thus, at the output of the OR element 21, there is also a low-level signal, which terminates the AND 4 elements, preventing the rewriting of the code recorded in the counter 24 into the register 5 and the indication by the display unit 6.

When subsequent clock pulses appear at the output of the generator 1, the states of the outputs of the trigger 3 change. The frequency of the pulses produced by the generator 7 decreases, which leads to a rearrangement of the comb filters in the direction of increasing frequency. Switched through the clock, the keys 13 and 14 are alternately connected to the output of the adder 12. Integrators 15 and 16, maintaining at their outputs a constant voltage equal to the maximum signal applied to their inputs.

In the ecech cycles up to the moment of fine tuning of the filters, inclusive, with each new cycle on the input of the integrators, higher and higher levels of signals arrive, and accordingly, the voltage at their outputs increases. The levels of the signals at the outputs of the Comparators and at the corresponding outputs of the trigger 3 do not coincide, which leads to the presence of a low level signal at the outputs of the elements AND 19, 20 OR 21.

The maximum signal at the output of the adder 12 is at the time of fine tuning (tick Z, diagram G). In the next cycle, the peaks of the spectral components of the pulsations pass through the filters, and the total signal at the output of the adder 12 is reduced (the cycle W, the G diagram). This leads to the fact that at the outputs of the integrators the signal level does not change as compared with the preceding cycle, and

205020

it also changes at the corresponding inputs of the comparators, while at the other inputs the levels of the signals from the outputs of the trigger change

5 compared with the previous tact on the opposite. As a result, the levels of the signals at the inputs of the And 19, 20 elements coincide, which appears on one of their inputs

10 high level signals (clock cycle W, diagram n) and accordingly the same signal level at the output of the element OR 21. The latter opens AND 4 elements through which the code,

15 is proportional to the frequency of the filter settings in the previous clock cycle, is recorded in register 5 and is displayed in display unit 6. Since in the previous cycle the filters were

20 are tuned to the maxima of the spectral components of the pulsation spectrum, the indicator displays the code for the frequency of the fundamental harmonic of the pulsations. At the same time, the signal from the output of the element OR 21 is fed to the element 22 of the delay and through the time delay

t From the output of the latter, it resets all elements of the device accumulation to the zero state than

returns it to its original state. After that, the whole process is repeated. The delay time of the element 22 t corresponds to the minimum required time from the beginning of the cycle, for which the code from counter 24 has time to be overwritten in register 5. During the tuning frequency search periods, register 5 and indicator 6 store the last of certain values until the next time the extremum is detected, and then in register 5 and on the indicator is updated. The discreteness of the process can be reduced by increasing the frequency of clock pulses generated by the generator 1. I -.

As the sensor 11 pulsation current (voltage) in the device, you can use a shunt in the circuit of the electric machine. As a filter 25 for DC machines, a low-pass filter is used with a cut-off frequency equal to the maximum tuning frequency of the comb

filter 10, and for AC machines - notch filter., suppressing the component of the spectrum of pulsations with a frequency c;

Thus, the controler device provides for tuning filters on the η spectral components of the current (starting with the first, which are multiples of the rotational frequency, and thus allows unambiguously to determine the rotational frequency of the electric machine. At the same time, failures and inaccuracies in the estimation are excluded. rotational frequencies that are characteristic of the known 12050206

devices and are caused by the ingress of an off-design component in the passband of the filter

5 The device is universal, as it is applicable for any electric masks of collector machines of direct and alternating current with different excitation, asyn10 chronic, etc.).

I

g

1PPTPPPPPPPPPPPPPPPP P P P P P P

-IU

I

LLLLLLL / 1 / l / i

i

Well

n

P

/

Phi2.2

entrance

Output 1

- ..

76

s

26

Controllable

FIG.

BhtXDi2

Bbfxodn

 I

II

w

Compiler M.Khaustov Editor I.Rybchenko Tehred A.Ach Proofreader E.Roshko

Order 8521/45 Circulation 896 Subscription VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch ShSh Patent, Uzhgorod, 4 Project St.

II

lllll

f

Fy

Claims (1)

ELECTRIC MACHINE ROTATION CONTROL DEVICE, comprising a current ripple sensor, an indication unit and a tunable filter, to the control input of which an output of the control voltage generating unit is connected, characterized in that, in order to expand the range of controlled products, a clock generator, a first counter, are introduced into the device trigger, adder, notch filter, first and second keys, two integrators, two comparators, first AND elements, second and third AND elements, OR element, register and two back elements hob, tunable filter is made in the form of a comb filter, the control voltage generating unit is made in the form of a second counter, tunable generator, sawtooth generator and peak detector connected in series, the output of the clock generator being connected to the counting input of the trigger and to the counting input of the second counter, and through the second delay element to the counting input of the first counter, the information outputs of which are connected to the first inputs of the corresponding first elements And, the second with inputs connected to the output of the OR element and to the input of the first delay element, and the outputs to the corresponding inputs of the register, the output of which is connected to the input of the display unit, the output of the current ripple sensor through a notch filter is connected to the information input of the tunable comb filter, the outputs connected to the inputs an adder, the output of which through the first key and the first integrator connected in series is connected to the first input of the first and second comparators, and through the second key connected in series h and a second integrator to the second input of the first and second comparators, the output of the first comparator is connected to the first input of the first AND element, the second input of which is connected to the direct output of the trigger and to the control input of the first key, and the output to the first input of the OR element, the second input connected to the output of the second element And, the first input of which is connected to the output of the second comparator, and the second input to the inverse output of the trigger and to the control input of the second key, while the output of the first element of the delay is connected to the inputs of the set and zero trigger, first and second integrators of the first and second counters.