JPS59103566A - Pulsation removing device for tachometer generator - Google Patents

Abstract

PURPOSE:To effectively remove the pulsation of a tachometer generator by storing a pulsation waveform signal of the output of the generator, multiplying the output by the output of the generator and reducing the multiplied output from the generator. CONSTITUTION:A pulsation waveform signal of the output of a tachometer generator 1 is stored in a memory. A pulsation waveform signal is produced from the memory by a read-out circuit 5 in response to the rotary position output of a rotary position detector 3. The output of the circuit 5 and the output of the generator 1 are multiplied by a multiplier 8, the output of the multiplier 8 is applied to a subtractor 10 through an attenuator 9, and the output is reduced from the output of the generator 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for removing ripple waveform pulsations from the output of a tacho generator 9.

A tacho generator is often used as a speed detector in a speed feedback loop of a servo system used in speed control devices, NO machine tools, robots, and the like.

Ripples occur in the output of the tacho generator due to non-uniformity of the field and disturbances in rectification due to brushes.

This ripple causes disadvantageous characteristics such as speed fluctuations and vibrations in the speed control system.

Therefore, the output of the tacho generator is filtered through the low-pass filter 7.
Ripples are removed by passing it through.

The ripple removal method using a low-pass filter is as follows.The ripple frequency component of the tacho generator is proportional to the rotation, so when the engine is running at low speed, the ripple frequency component is also low frequency, and the ripple removal effect of the low-pass filter decreases.

■Low-pass filters inherently cause a phase lag, which limits the responsiveness of the speed control system.

The problem is that money matters.

Figure 1 shows the output of the tachogenerator passed through a low-pass filter.
A configuration diagram of a conventional circuit is shown.

The input voltage e from the tacho generator l to the low-pass filter 2 is the component resistor 21. Output voltage e via capacitor 22. is taken out.

Fig. 2a shows the input voltage e in the high speed range of the tacho generator 1, and Fig. 2b shows the output voltage e. All of these represent characteristics due to the passage of time t, and ripples have been removed. - However, in the low speed range of the tacho generator 1 as shown in Fig. 3a, the output e in Fig. 3b is low for the input voltage el. is the output 'voltage e' which is difficult to eliminate ripples. The dotted line is the input/output voltage without ripple.

FIG. 4 shows the input voltage e of this first-order slow filter 2.

from the output voltage e. FIG. 4 is a diagram showing a characteristic curve of the logarithm of the frequency (horizontal axis) and the phase delay 4t (vertical axis) when transitioning to .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pulsation elimination device for a tacho generator, which overcomes the drawbacks of conventional means.

FIG. 5 is a block diagram showing the configuration of an embodiment of the present invention.

The pulse output (+pulse 301.-pulse 302) from the pulse generator 3 directly connected to the tachometer generator 1 is counted by a counter 4 to measure the rotational position of the tachometer generator 1. The counter 4 is reset by the synchronization pulse 300 outputted from the pulse generator 3, and is reset periodically at the synchronization pulse interval.

A memory 6 for storing ripple waveforms is provided, and this memory 6
Data D corresponding to the value i of the counter 4 is extracted from the readout circuit 5 and converted into an analog signal via the D/A converter 7.

The multiplier 8 calculates the product of the D/Af converter 7 output and the output 101 of the tacho generator l, and the multiplier 8 output is applied to the attenuator 9.
Multiply by 1 to obtain the calculated ripple signal.

The difference between the output signal 101 of the tacho generator 1 and the calculated ripple signal 91 is calculated by a subtracter 10 to obtain an output with ripples removed.

The principle of the present invention will now be described.

The present invention provides that the ripple P(t) of the tacho generator l is
) = v(t) ' (θ) ``''° (Equation 1).

Here, V(1,) is the output of an ideal tacho generator with no ripple, t is time, θ is the mechanical rotational position of the tacho generator, and ) is a function indicating the ripple waveform expressed as a function of θ. It is.

The function f() is a periodic function of the rotational position θ, and the maximum period is 2E□d for one revolution. Due to the structure ζ of the tacho generator 1, the period may be smaller than one revolution.

The function f(θ) and the output 101 of the tacho generator 1 are v(t
) + P(t) ......(Equation 2), so the actual output including ripple of tacho generator 1 is (v(t) 0P(t) ) '(θ)'' P (t)+
(P(t)) ”/v(t) (3) Normally, the ripple P(t) of tacho generator 1 is expressed as the output v(t) of ideal tacho generator 1 with no ripple. Since it is less than 5 at most, '(t)'' in equation (3)
(V(t)+P(1,))f(θ) = (Equation 4). In other words, the ripple is the output 101 of the tacho generator l
and to the function, ) is approximated next to. Figure 5 shows an example of a circuit that implements this principle.

The operation of the circuit of the embodiment shown in FIG. 5 will be explained.

The pulse generator 3 is directly connected to the tachometer generator 1, and generates + pulse 301° - pulse 302 in response to positive and negative rotations.
At the same time, the ripple wave # is expressed as t) fX number f(
A synchronization pulse 300 synchronized with the period of θ) is generated.

+Pulse 301. - the pulses 302 are counted by a counter 4, the value of which corresponds to the rotational position of the pulse generator 3 and the co-generator l; The counter 4 is incremented by the synchronization pulse 300, and the counter 4 also changes periodically in synchronization with the period of the function f( ) representing the ripple waveform.

In FIG. 6, * shows the change in the value of the counter 4 when rotating in the forward direction.

Assuming that the synchronization pulse 300 is output every N pulse intervals of + pulse 301 or one pulse 302, the value of the counter 4 is reset to zero each time the synchronization pulse 300 is input, and the value of the counter 4 is reset to zero every time the synchronization pulse 300 is input. It is incremented every time 0.1. ..., N-1 integer
takes on individual states.

Similarly, when rotated in the negative direction, Oy l , -9
-(N'-1) takes N states.

When the period is N, N pieces of ripple waveform data D, , D, . . . , DI-1 are stored in the ripple waveform memory 6.

To determine the data D0 to DN, for example, the ripple waveform when the tacho generator 1 is rotated at a constant value V0 is sampled at one pulse interval of the pulse generator 3, and this sample value is input to the effective bit length of the memory 6. This is done by multiplying the data in the cave by a constant for normalization.

FIG. 7 shows data D0 to DN-□ stored in this ripple waveform memory 6.

Ripple waveform data Di corresponding to the value i of the counter 4 is selected by the readout circuit 5.

however, When i≧O, D When i<o, , j=N+i Select.

The selected data is converted into an analog signal by the D/A converter 7.

The product of this analog signal and the output signal 101 of the tacho generator is calculated by the multiplier 8, and multiplied by r (r<1) by the attenuator 9.
to get the calculated ripple value. The constant r is the constant value mentioned above■
. , a constant and a constant of the D/A converter.

Tacho generator l output 101 and ripple calculation value 91
A subtracter 1o calculates the difference between the ripples and the output 11, and a ripple-free signal is obtained as an output 11.

The circuit for obtaining an analog signal from which ripples have been removed has been described, but when it is desired to obtain a digital signal as an output, a configuration as shown in FIG. 8 is used.

That is, FIG. 8 is a block diagram of another embodiment of the present invention.

12 is an analog output signal 101' of tacho generator 1
8o is a multiplier, 90 is an attenuator, 100 is a subtracter, 110 is a digital output signal from which ripples have been removed, and 1000 is its digital circuit.

All operations on analog signals (FIG. 5) are performed using digital signals, and the operation is exactly the same.

However, if the ripple waveform differs between positive and negative rotations,
The ripple waveform memory 6 may be prepared in types 2a for positive rotation and for negative rotation, and either one may be selected according to the rotation direction.

Note that a conventional ripple removal method may also be applied to the output 11 of the present invention.

Thus, according to the present invention, it is possible to eliminate the portion of the ripple of the tacho generator due to deterministic factors such as non-uniformity of the field and brush behavior, resulting in a tacho generator with small ripples in an equi-frugal manner.

Furthermore, the means of the present invention can remove ripples independent of the rotational speed, and is particularly advantageous at low rotational speeds.

Furthermore, since it does not include a phase delay element, when used as a feedback loop detector, the feedback loop can be installed at the station gain compared to the conventional method.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional circuit, Figures 2a and b are high-speed range output voltage diagrams of the tacho generator, Figures 3a and b are low-speed range output voltage diagrams, and Figure 4 is its input, FIG. 5 is a block diagram showing the configuration of an embodiment of the present invention; FIG. Explanatory diagram, Figure 7,
1. A diagram of the data to be recorded in the reliable waveform memory,
Section 8 is a block diagram showing the entire configuration of the song tongue embodiment of the invention. DESCRIPTION OF SYMBOLS 1...L Kozei-Rake, 2...1st-order slow milli-low-pass filter, 3...Pulse generator, 4...Counter, 5...Readout circuit, 6...Ripple waveform memory,
7... D/A converter, 8.80... Multiplier, 9,9
0...attenuator, 10,100...attenuator, 11.
... Output (analog signal), 12... A/D converter,
91... Calculated ripple signal, 101... Output signal of tacho generator 1, 300... Synchronization pulse,
301...+pulse, 302...-pulse, 100
0...Tasital circuit. Applicant's agent Kiyoshi Inomata Figure 2α Child? Figure b Figure 3a Figure 3b Figure 4

Claims (1)

[Claims] 1. A rotational position detector connected to the tacho zeolator, a storage circuit for storing the pulsating waveform signal output from the tacho generator, and extracting the pulsating waveform signal from the storage circuit in accordance with the rotational position output of the rotational position detector. A pulsation of the output of the tacho generator, characterized by comprising a readout circuit, a multiplier that multiplies the output of the readout circuit and the output of the tacho generator, and a subtracter that subtracts the output of the multiplier from the output of the tacho generator. removal device.