SU1363417A1 - Method of start-stop control of stepping motor - Google Patents

Abstract

The invention relates to electrical engineering, to the control of stepper motors. The purpose of the invention is to increase the efficiency by forming a given dependence of the braking torque on the displacement. The method consists in disconnecting the previous winding, connecting the subsequent winding and setting the maximum current in it due to the power supply from the current source. The acceleration of the rotor of the stepper motor is measured using an acceleration sensor 1. The acceleration value is integrated twice by integrators 3 and 4, as a result of which the path is found. Using the nonlinearity unit 13, the desired law of acceleration variation is formed when braking as a function of the path. The signal from the output of the acceleration sensor 1 is compared with the signal of the nonlinearity unit 13 and their difference control the current of the gas source. When the difference in the set value is increased by means of the adder 22 and the switch, the subsequent winding is turned off and the distance is switched on until the specified difference is reduced to the set value, 1 hp. f-ly, 3 ill. d 5S (L with O5 with 4

Description

 13

The invention relates to the control of electric machines and can be used to control a stepper motor (AHC).

The purpose of the invention is to increase the speed and efficiency by forming a predetermined dependence of the braking torque on the displacement.

Figure 1 shows a diagram of the moment, speed and displacement of the rotor of the scapular engine when performing one step; Fig. 2 shows diagrams of the moment dependence on the rotor movement; on fig.Z - diagram of the device that implements the method.

The method is implemented as follows.

The previous winding is disconnected and the next is connected using the switch. The power is supplied from the current source and in the winding the maximum current value is created according to the operating conditions. The law of change of the dynamic moment is not regulated here; it depends on the engine design and the electromechanical transient process during the development of a step.

The acceleration of the rotor of the stepper motor is measured, the dynamic moment is determined by the magnitude of the acceleration.

M M - M AYAN dv with

, do dt

- engine torque;

35

- moment of resistance;

- the moment of inertia of the drive;

Angular acceleration of the rotor. 40

The acceleration value is integrated twice, as a result of which the dependences of the speed and the path traveled by the rotor are obtained during the development of the step. (figure 1).

They are given by the necessary dependence of the dynamic moment in the process of braking. This dependence is determined by a given intensity of braking. Figure 1 shows the relationship, allowing for intra-step movement without overshoot. This is achieved by a lower average deceleration value compared with acceleration and the formation of a triangular deceleration graph at the end of braking. Such a law allows to achieve high

F

0 5

0

five

0

five

Q gg

72

speed and efficiency with a small overshoot.

The value of the traversed path S is determined, inside the step, with which it is not necessary to begin the braking process. This value depends on the ratio of average values of dynamic moments during start and braking, determined during the drive tuning process. At the same time, it is necessary that the kinetic energy reserve during acceleration does not exceed the kinetic energy reserve — on the braking path.

Upon reaching a predetermined path, the braking process is carried out. To control it with the help of the block, the nonlinearity is determined from the acceleration and path plots (Fig. 1). The graph of the change in the dynamic moment M depending on the distance; 1; about the path (Fig. 2).

The difference d between the current value of the dynamic moment M and the desired M is measured (Fig. 2).

The difference value is used to reduce the magnitude of the current in the winding. In this case, two cases are possible: the moment of resistance of the electric drive is significant and the change of the dynamic moment in accordance with the preset is possible due to the change (decrease) of the engine torque; the moment of resistance is insignificant and the desired change in dynamic moment cannot be achieved by changing the moment created by the subsequent winding.

In order to ensure the operability of the stepper electric drive, in the latter case, the difference between the current value of the dynamic moment and the set one is controlled.

If the difference value d exceeds the specified value d, the reverse switching of the windings is performed, i.e. the following winding is turned off and the winding of the search is turned on. In this case, the current is set to the maximum possible, which ensures the continuous operation mode of the AHC (Fig. 2).

When the difference decreases below the set one, the subsequent winding is switched on again and the deceleration mode is implemented with control of the current in the winding.

This control method can be implemented using a device that contains an acceleration sensor .1,

313

amplifier 2, integrators 3 and 4, switches 5 and 6, switches 7 and 8, sum-amplifiers 9 and 10, comparators 11 and 12, nonlinearity unit 13, voltage-current converter 14, element 15, step motor ( SSC) 16, multiplexers 1 and 18, shaper 19, power key block 20, decoder 21, adder 22, reversible counter 23.

The inputs of the first switch 7 are connected to supply voltage buses of different polarity, and the output is connected to the input of the first integrator 3 and the first input of the summing amplifier 10 through the acceleration sensor 1 and amplifier 2,

The output of the first integrator 3 is connected to the input of the second integrator 4, the output of which is connected to the first inputs of the first summing amplifier 9 and the first comparator 11. The output of the first summing amplifier 9 is connected to the second input of the second summing amplifier 10, the output of which is connected to the first inputs of the second comparator 12 and the second switch 8. The rank of the third reference voltage is connected to the second input of the second comparator 12, the output of which is connected to the first input of the And 15 element and to the first addresses first and second MULTIPLEKSO-

Ditch 17 and 18. The bus of the first reference voltage is connected to the second inputs of the first summing amplifier 9 and the first comparator 11, the output of which is connected to the second input of the And 15 element and to the gate inputs of the first and second multiplexers 17 and 18. the reference voltage is connected to the second input of the second switch 8, the control input; which is connected to the output of the element And 15, and the output - to the input, the voltage-current converter 14. The output of the voltage-current converter 14 is connected to the common terminal of the windings of the stepper motor 16.

The second address inputs of the two multiplexers 17 and 18, the control input of the first switch 7 and the count direction input of the reversible counter 23 are interconnected and are the input of the direction of motion of the device. The outputs of the reversible counter 23 are connected to the first inputs of the totalizer 174

22, the inputs of which are connected to the output of the windings of the stepper motor 16 through the series-connected decoder 21 and the power switch block 20. The second inputs of the adder 22 are connected to the outputs of the first and second multiplexers 17 and 18 whose switched inputs are connected to buses O and 1 in accordance with control codes. The terminals of the capacitors of the first and second integrators 3 and 4 are connected respectively to the outputs of the first and second switches 5 and 6, the control inputs of which are connected to the output of the driver 19, the input of which is combined with the counting input of the reversing counter 23 and is a clock input of the device.

Transducer 14 voltage is linear and reversible. Summing amplifiers 9 and 10 realize the characteristic of a precision diode.

The device works as follows.

A clock pulse arrives at the counting input of the reversible counter 23 and the driver 19 input. In the driver 23, the clock pulse is differentiated and a control pulse is formed along its leading edge, which opens the keys 5 and 6, which discharges the capacitors of the integrators 3 and 4, preparing them for operation. At the same time, the state of the reversible counter 23 changes, the output code of which through the adder 22 enters the inputs of the decoder 21, is decrypted and turns on the corresponding power key of the power key block 22. In the initial state, the voltage-current converter 14 sets the current through winding W. 16. TsTs 16 begins testing the step. .The value of the current, and consequently, the moment of the SC-16, can be changed by varying the voltage value V power Acceleration sensor 1 fixes its value, and hence the value of dynamic moment, which is integrated twice by integrators 3 and 4. At the output of integrator 3, the signal is proportional to speed, and at the output of the integrator 4 - the path. The magnitude of the path S, from which the braking begins, is recorded by the comparator 11. To do this, a signal is generated at one of the inputs of the comparator 11.

13

proportional to the current path, and on the second - Qfn, proportional to the path S,.

In this case, their equality at the output of the comparator 11 signal changes its value from the signal O to 1, which creates the combination 11 at the input of the element 15 and enables the multiplexers to work. The element 15 transmits the output signal 1 and switches the second switch 8, which turns off the converter input 14 from the reference voltage Ujn and connects to the output of the summing amplifier 10. Simultaneously, the output of the first summing amplifier 9 appears voltage proportional to the difference of the current path and S ,, This signal is fed to the input of the nonlinearity unit 13, which has The dependence of the output voltage on the input proportional function M (S) (Figure 2). The second summing amplifier 10, the inputs of which receive signals of the desired and current dynamic moments, forms their difference. Moreover, this signal is formed only if the braking current dynamic moment exceeds the desired one. Otherwise, the signal at the output of the second summing amplifier 10 is zero. The value of the current through the winding decreases and the braking process begins under the effect of a static moment. If the stock of kinetic energy is significant, and the moment of resistance is small, then the change in the current dynamic moment largely lags behind the desired one. This fixes the second comparator 12. When the specified difference exceeds the value specified by the reference voltage, the comparator 12 is triggered and its output signal changes its value from 1 to O. At the input of element 15, a combination of 01 is created, Its output signal again switches the switch 8, connects the input of the voltage-current converter 14 to the reference voltage U and creates a significant current in the winding of the switch board 16. Simultaneously, the multiplexers 17 and 18 and the adder 22 switch the reverse search current 16, Generated with the top braking mode is 11Sh 16 ,, which lasts until the value of the difference A is below & At the same time, again

the second comparator 12 will work and the circuit will return to the initial state, continuing the deceleration process with the current control in the SM step 16 winding.

The reverse switching of the windings of the CS 16 when the second comparator 12 is triggered is carried out as follows. If the forward movement is carried out, then the number code (N-1) is added to the code of the reversible counter 23, where N is the number of switched windings and 1 backwards - then 1.

In the diagram (Fig. 3), the SD is considered that has four windings. At the same time, the reversible counter 23 is two-bit and the corresponding binary numbers are 11 and 01. The data codes of the numbers are formed by multiplexers 17 and 18. The high address bit of the control code of multiplexers 17 and 18 is connected to the input of the direction of movement and corresponds to O when moving forward and 1 - backwards When the second comparator is triggered; 12 and when the signal O is received at the lower address bit of the control code, the control code corresponds to 00 — when moving forward and 01 — when moving backward. The first switched inputs create a combination of 11, the second - 01, the third and fourth - 00. This code goes to the second inputs of the adder 22 and is added to the code of the reversible counter 23. When the operation of multiplexers 17 and 18 is prohibited on the path O - S, the output signal the first comparator 11, then the signals O are present at their outputs.

In order for the control circuit not to contain bipolar-blocks 3, 4, 9, 10, 11, 12, 13, when changing the direction of movement with the first switch 7, the sign of the supply voltage of the acceleration sensor 1 is changed. In this case, the sign of the output voltage of the sensor .1 is not. depends on the direction of movement of the SM 16.

If necessary, create

in the winding U, after testing the step of the given current in the moment curve, a shelf Mj is formed, the amplitude of which corresponds to the given current.

The use of this device allows the formation of an internal transient process, which expands the range of application of stepper electric drives, improves speed and efficiency.

Claims (1)

1. A start-stop control method for a stepper motor, which includes, in each movement cycle, disconnecting the previous winding, turning on the next winding and reducing the current in it, characterized in that, in order to improve performance and efficiency by forming a given dependence of the braking torque ot displacement , specify the indicated dependence and the length of the movement at the beginning of braking, after disconnecting the previous one, and turning on the subsequent winding, measure the acceleration of the moving element of the engine, by double integration of the ate dissolved its movement, it is compared with a given 78 In excess of this, the current in the subsequent winding is reduced, the current value of the braking torque is determined by acceleration, and the current in the subsequent winding is adjusted by the difference in the current and set values of the braking torque. 2, Method POP.1., Characterized in that, in order to apply the method with a low engine load, the admissible value of the difference between this braking torque and the current is additionally set, after the start of current reduction in the subsequent winding, the difference between the set current braking torque is compared with the permissible value, at which the subsequent winding is disconnected and the previous winding is turned on for the time of reduction of the specified difference to the permissible value. 1 U2.l