SU1697055A1 - Analog and digital servosystem - Google Patents

Abstract

The invention relates to automation and can be used to control objects based on signals from computing devices. The aim of the invention is to simplify the design and increase reliability. The goal is achieved by the fact that in a digital-to-analogue tracking system containing a rotation angle sensor (sine-cosine rotating transformer) 1. a generator 5 of the reference frequency, a digital-to-analog converter (DAC) 10, phase-sensitive rectifiers (FW) 7 and 8 , switch 9, three elements EXCLUSIVE OR 14-16, comparator 6, unit 11 is integrated by integrating. The voltages from the outputs of sinus 3 and cosine 4 windings are rectified in FFV 7 and 8 in such a way that their signs are always opposite. the output is a mismatch signal. The latter is integrated in block 11 and is fed to the input of electric drive 12 for error processing. 3 il. SP

Description

The invention relates to automation and can be used to control objects based on signals from computing devices.

The purpose of the invention is to simplify the design and increase reliability. FIG. 1 is a block diagram of the system; in fig. 2 - table of function values; in fig. 3 - plots showing system operation.

The system contains a rotation angle sensor in the form of a sine-cosine rotating transformer (CCT) 1 with excitation winding 2, as well as with a sine 3 and cosine 4 windings, reference frequency generator 5, comparator b, first and second phase-sensitive rectifiers (FCF) 7 and 8, switch 9, digital-to-analog converter 10, integration block 11, electric drive 12, memory block 13, first, second and third elements EXCLUSIVE OR 14-16, control bus 17, sine-cosmic digital-analog converter 18.

The system works as follows.

The reference frequency generator 5 forms the voltage of a sinusoidal form, which feeds the excitation winding 2 of the ACS 1 (Fig. 3). The voltage Us is compared with a zero comparator 6: if Us is 0, the voltage Ue at the output of comparator 6 is 1, if Us is 0, the voltage (cM. Fig. 3). On the output windings of 3.4 SSCT 1, the voltage of the conductor is formed

xj o

eaten

portioned by sine and cosine of angle o. shaft rotation:

  sin a sin a t, U0K cosasinan, where K is the transformation ratio of SCWT 1.

For the sake of simplicity, suppose that Wo ° K-1, Then

Uz sin with sin o) t, - cos a sin a) t.

To form a signal proportional to the magnitude of the mismatch between the control signal and the shaft of the electric drive 12, the lower bits of the control signal N from the digital computer (not shown in black) go to memory block 13, in which the functions sinN and cosN are recorded. At the outputs of memory block 13, there is a sinNj function, if a higher input is present at O, and a cosNi function, if at a high address input 1. As the senior address input receives a signal from comparator 6 with a frequency of ol, and digital inputs of the DAC 10 are received alternately sinN, cosN functions. The voltages Uz and LM are fed to the information inputs of the FWC 7 and 8. The FWF is operated by the following edge. If O is present at the control input of the FWH, the voltage at its output is equal to the voltage at its output. If there is 1 at the control descent of the FWH, the voltage at its output is equal in absolute value to the voltage at its input, but opposite in sign.

In FSV 7 and 8, a phase-sensitive rectification of the voltage Uz and UY occurs, which are then alternately fed by the switch 9 to the analog input of the DAC 10. Moreover, at different angles of mismatch between N and a. A condition is provided in which at the outputs of the FWV 7 and 8, the voltages U and UV have opposite signs. For this, in the first quadrant (Fig. 2), the signals Uis and Uie on the outputs of the EXCLUSIVE OR elements 15 and 16 are changed in phase. Sine and cosine functions in the range from 0 to 90 ° have positive signs, but since sine 3 and cosine 4 windings of SQWT 1 are included in antiphase, the voltages Y and Uz are opposite in sign (Y7 is negative. Us- positive). In the second quadrant, the signals U is and Uie at the outputs of the EXCLUSIVE OR elements 15 and 16 change in antiphase, the sine and cosine functions in the range of 90-180 ° have different signs, therefore the voltage Y and UV have different signs (Y positive, Us - negative). In the third quadrant, the voltage Y is negative, and La is positive. 8, in the fourth quadrant, the voltage U is positive, and let is the negative of which (see Fig. 2 and 3).

In the first quadrant, the voltage U and Us at the outputs of the FVC 7 and 8 are the same Ut sin a, Ue cos a, and the bits Up 0 and Un-i 0. We assume that with a positive voltage on

the drive rotates in the positive direction (to the right in FIG. 3), and in the negative direction, vice versa.

At those times when, at the output of the switch 9, the function

cos a. At the same time, the function sinN is present at the output of memory block 13. The DAC 10 multiplies the signals present at its digital and analog inputs, so the output of the DAC 10 is the voltage sinNcos a.

With the appearance of 1 at the output of the comparator 6. Switch 9 connects to its output the function si pa, and at the output of the memory block 13 appears the function cosN. Therefore, the signal at the output of the DAC 10 is equal to cosNsIn a. Since the signal at the output of the comparator 6 continuously changes with the frequency of the excitation voltage, after averaging in the integration block 11, the voltage at the output of the latter

one

Un-y (cosas., IN-sin acosN)

 Ј sin (N-a).

Let us analyze the resulting expression. If N a, i.e. the set point is to the left (in accordance with FIG. 3) of the actual, Un 0, and the actuator 12 moves in the negative direction (left). If N about: The given point is to the right. given, Mc 0, and the actuator 12 moves in the positive direction (to the right).

Drive 12 moves until Uz

-J -z sin (N a) will become zero. This will happen when N and. When a transition command is received in the second quadrant, 1 () appears on the bit of code N. This leads to the fact that the signal at the output of element 16 EXCLUSIVE OR changes by 180 ° (if there is O at the first input of the EXCLUSIVE element OR, the signal at its output is equal to the signal at its second input, if the first input is 1, the signal at output is opposite to the signal at the second input). This leads to a change in the voltage value U. It becomes positive, as well as the voltage Ua, and, consequently, the voltage Yz is positively positive, and the electric drive

12 moves toward the second quadrant. When the angle a reaches the second quadrant, the sign of the voltage Ua changes due to a change in the sign of the function cos a when passing through an angle of 90 °. The voltages U and Us again have opposite signs.

Un - j voltage (sina sinN +

- cos acosN), however, taking into account that cos cr sln (a + 90 °), a sin a -cos (a + 90 °), Un

 - cosas n ("+ 900) -sinNcos (a + 90 °)

 t | -sin (a-N-90 °) I sin (N-a-90 °).

The drive stops at an angle of + 90 ° in the second quadrant. When a transition command is received in the third quadrant of 180 ° and 270 °, the values of the bits correspond,. In this case, the phase of the signal Uie does not change, and the phase of the signal Uis changes by 180 °. This leads to a change in the polarity of the signal Us. It becomes positive as well as the voltage U, and hence the voltage Un turns out to be positive. Consequently, the electric drive rotates toward the third quadrant. When passing through an angle of 180 °, the voltage U changes its sign (transition of the sine function through an angle of 180 °). and the voltages U and Us again become oppositely opposed

and the voltage Un - (sina cosN-

cos a slnN) - -sin (N - a) - sin (N - a-180 °).

Consequently, the electric drive stops at an angle of N "+ 180 °. When a transition command is received in the fourth quadrant 270 a 360, the phase of the signal Uie changes by 180 °, and the voltage U becomes positive, as does the voltage Us. Consequently, the voltage Un also turns out to be positive, and the actuator 12 rotates in a positive direction towards the fourth quadrant. When the fourth quadrant is reached, the voltages U and Us become again polarized, and the voltage

U C - (sin a slnN + cosa cosN) cos (N-

-a) | sln (N-a + 90 °) -sln (N-a-270 °).

Consequently, the electric drive stops at an angle of N a + 270 °. If there is a command to go to a quadrant with a smaller number, for example, from the third to the second, or from the second to the first, then at the first moment of time the voltages U and Us, and hence the voltage Un, are negative, but only until then. until the shaft of the electric drive 12 reaches the predetermined quadrant.

If a command comes in from the first quadrant to the third or from the second to the fourth and vice versa, the voltage sign is undefined. If the error value is less than 180 °, the voltage Un has one polarity, and if the error value is more than 180 °, the voltage Un has opposite polarity, i.e. the actuator rotates to the desired position along the shortest path.

The use of simpler elements, a decrease in their total number, the use of memory chips that do not require preliminary programming increases the reliability of the system and reduces the cost of production.

Claims (1)

Invention Formula A digital-analogue tracking system comprising a reference frequency generator, an electric drive, a rotation angle sensor, the rotor of which is mechanically connected to the drive shaft, a sine-cosine digital-to-analog converter, the lower bits of the digital input are the lower bits of the control input of the system, a switch, two phase-sensitive rectifiers connected by information inputs to the corresponding outputs of the angle sensor, a comparator, the first input of which is connected to the output of the reference voltage generator and the input of the angle sensor, and the second input is connected to the common bus, the three elements are EXCLUSIVE OR, the first inputs of the first and second elements are EXCLUSIVE OR are the upper bits of the control input of the system, the second inputs of the first and second elements are EXCLUSIVE OR connected with a comparator output, the analog input of a sinus-to-sinus D / A converter is connected to the output of the switch, the first and second information inputs of which are connected to the outputs of the corresponding phase-sensitive rectifiers , the output of the second element EXCLUSIVE OR is connected to the control input of the second phase-sensitive rectifier, the first input of the first element EXCLUSIVE OR is connected to the first input of the third element EXCLUSIVE OR, in order to simplify the design and increase reliability, a block is entered into it integration, the output of which is connected to the drive input, the second inputs of the first and second elements are EXCLUSIVE OR associated with the higher-order digital input of the sine-cosine D / A converter, the output connected to the input of the integrator, the output A torus controlling the input of the first phase sensitive detector is connected to the output of the third element EXCLUSIVE OR, the output of the second element is EXCLUSIVE OR 5 ALREADY OR 5 connected to the second input of the third one connected to the control input of the switch of the EXCLUSIVE OR element. the torus, the control input of the first faeo-sensitive rectifier is connected to the output of the third element EXCLUSIVE OR, the output of the second element is EX. FTs2.Ј. ppppppppppppppp Vn1 L Vn 4te TUP P П П П П П П П П П П about№ ppppp n n p p p p p p RPPPPPPPPPPPPPP U7 eight about and rYYW Od t MLL / t