SU1138919A1 - Device for controlling step motor - Google Patents

Abstract

A DEVICE FOR CONTROLLING A STEP ENGINE, containing the first. a key element. connecting a high voltage direct current source output to one motor phase terminal connected through a separate diode to the source output. direct current low voltage, the second key element connecting the other terminal of the motor phase connected to the discharge diode, with a common beer sources of high and low stress through a current sensor connected to the output of the first input of the comparator connected to the inverse trigger input connected to the direct input with the control signal source and the direct output with the input of the first key element, characterized in that, in order to increase the reliability of the i stepper motor with a passive rotor during for mechanical decoupling (A fire rate, introduced into it amplitude detector, a signal input coupled to the current sensor ,, control input connected to the output .inversnomu triggeraj and an output - to a second input of the comparator. about eo w

Description

The invention relates to electrical engineering, namely, devices for controlling stepper motors. A device for controlling a stepper motor, comprising a current sensor in a negative current feedback circuit, keys that connect the motor windings on the feedback signal from high to low voltage, and keys that connect the motor windings to a low voltage source, and also switching circuits consisting of triggers, elements AND and OR, inverters and amplifiers 1. The drawback of the device is the low reliability when the stepper motor operates on varying mechanical load on its shaft, caused by possibility of loss of step when the load increases. The closest to the invention in its technical essence is a device for controlling a step motor, comprising a first key element connecting the output of a high voltage direct current source to a single motor phase terminal connected through a separation diode to the output of a low voltage direct current source The second key element connecting the other motor phase terminal connected to the discharge diode to the common source bus. high and low voltages. through a current sensor connected by the output to the nepBbiM input of the comparator, connected by an output to the inverse input of the trigger, connected directly to the control signal source, and the direct output to the input of the first key element Zj. However, the conduction period of the key element connecting the motor phase to a high voltage is chosen in accordance with a given moment of inertia of the stepper motor and the mechanical load on its shaft. A change in the mechanical load of the motor can lead to a failure in the development of a step, which reduces the reliability of the engine, since the current sensor is rated for a nominal load. The goal is achieved in that a device for controlling a stepper motor, comprising a first key element connecting the high voltage direct current source output to one motor phase terminal, connected via a separation diode to the low voltage direct current source output connecting the other terminal of the motor phase, connected to the discharge diode, with the high-voltage and low-voltage busbars through the current sensor connected to the output of the first comparator output connected by an output to an inverted trigger input connected by a direct input to a control source and a direct output to an input of the first key element, an amplitude detector is inputted, a signal input of which is connected to a current sensor, a control input connected to the inverted output of a trigger, and exit - to the second entrance of the comparator. FIG. 1 shows a diagram of a device for controlling one phase of a stepper motor; in fig. 2 - time diagrams of voltages and currents on the main circuit elements; in fig. 3 - one of the possible schemes of the amplitude detector. The device contains a phase 1 stepwise motor voltage, the first key element on transistor 2, the second key element on transistor 3, resistive current sensor A, high voltage source 5, low voltage source 6 and separation diode 7. Between the common junction point 1 transistor 3 and low voltage source 6 is enabled. The circuit from diode 8 and resistor 9. Device input bus 10 is connected to the forward input of trigger 11 through an inverter 12. Direct output of trigger 11 is connected to the base of transistor 2 through amplifier 13, and the base of transistor 3 a bus coupled to the input device 10 through the second amplifier 14. The input bus 10 is connected to the output of control signal source (not shown). The amplitude detector 15 ft comparator 16 forms a negative current feedback circuit for the load current. Timing diagrams of signals 17-24 on the elements of the device circuit are shown in FIG. 2. One of the possible schemes for the amplitude detector 15 (FIG. 3) consists of operational amplifiers 25 and 26, capacitor 27 and switch 28. Inputs 29 and 30 of the amplitude detector are the signal and control inputs respectively, and the output of operational amplifier 26 - output 31 of the amplitude detector 15. The device operates as follows. When a pulse 17 arrives at the input bus 10 of the control device (Fig. 2). The inverted pulse 18 from the output of the inverter 12 flips the trigger 11 into the opening opening state of transistor 2, causing the transistors 2 and 3 to open in motor 1 a current signal 19 begins to flow, the rate of rise of which is determined by the magnitude of high voltage source 5. The current in the phase of a stepper motor with a passive rotor varies according to a certain law, depending on the movement of the core and changes in the magnetic parameters of the system, and the decrease in current (tfl in Fig. 2) corresponds to the development of the step. A voltage drop across a resistive current sensor 4, proportional to the current 19 of the phase 1 motor, is fed to the signal input 30 (Fig. 3) of the amplitude detector 15, which serves to memorize the extremum t, (Fig. 2) of the current signal 19 and its storage on the capacitor 27 The feedback circuit of the amplitude detector 15 includes a repeater on the operational amplifier 26, which reduces the detection error caused by the bias voltage zero input currents and the final amplification of the operational amplifier 25. The capacitor 27 is biased by key 28, for example This transistor is designed to reset the voltage stored in the amplitude detector 15. The input 29 of the 28 is the control input of the amplitude detector 15 The signal 21 from the output 31 (Fig. 3) of the amplitude detector 15 is fed to the second input of the comparator 16, To the first input of which comes a resistor from a resistive sensor 4 current The comparator 16 compares the instantaneous voltage values in the signal diagram 19 and 21. At the output of the comparator 16. a pulse 22 is formed, which arrives at the inverse input of the trigger 11, returning it to the initial state corresponding to the closed state of the transistor 2. At the same time 23 from the inverted trigger output 11 is fed to the control input of the amplitude detector 15 (to the input 219 of the switch 28), discharging the capacitor 27 and disconnecting the negative feedback before the next trigger pulse 17 arrives at the input bus 10 of the devices control. The transistor 3 remains open and the current signal 19 in phase 1 is supported by a low voltage source 6. Upon termination of the input pulse 24, the transistor 3 closes and the current signal 1p in phase 1 drops to zero. I Acceleration of the decline of the current signal 19 in the switchable winding 1 of the motor is provided by a discharge circuit consisting of a diode 8 and a resistor 9.; Introduction to negative current coupling in the proposed amplitude detector device allows the conduction period of transistor 2, during which a high voltage of source 5 is applied to the motor phase, automatically adjusted depending on the mechanical load applied to the motor shaft. Moreover, the duration of the forced pulse corresponds to the energy required to move the rotor one step. Reducing the mechanical load leads to faster working out of the step and earlier disconnecting the increased voltage (t. On the signal diagram 20, figure 2). An increase in the mechanical load leads to an increase in the duration of the period (0-t in the signal diagram 20, fig. 2) application to phase 1 of an overvoltage voltage. Thus, the invention reduces engine losses and increases the reliability of its operation under varying load on its shaft.

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Claims (1)

DEVICE FOR CONTROLLING A STEP ENGINE, containing the first. a key element. that connects the output of a high voltage direct current source with one motor phase clamp connected via a diode to the source output. DC low voltage, the second key element connecting the other terminal of the motor phase connected to the discharge diode, 'with a common bus of high and low voltage sources through a current sensor connected to the output of the first input of the comparator, connected to the inverse input of the trigger connected direct input with a control signal source, and direct output with the input of the first key element, characterized in that, in order to increase the reliability of the stepper motor with a passive rotor with changing mechanical load, an amplitude detector is introduced into it, the signal input of which is connected to a current sensor, the control input is connected to the inverse output of the trigger; and the output goes to the second input of the comparator. Figure 1 1 113891