CS238704B1 - Connection for stepper motor speed control - Google Patents

Abstract

The generator is connected via the first counter to the first input of the switching logic, which is connected in parallel with the second input of the closed-loop logic, corresponding to the "MAX" mode, via two outputs via the logical speed switches, corresponding to the "FORWARD" and "REVERSE STEPPING SPEED" modes. The third output of the switching logic is connected to the first input of the closed-loop logic, corresponding to the "STOP" mode. The stepper motor sensor connected to the closed-loop logic is feedback-connected via the second counter to the second input of the switching logic. By alternating switching of the "MAX" and "REVERSE" modes depending on which of the counters is filled first, the stepping frequency is maintained at a preset level. The connection can be advantageously used wherever a smooth speed change is required without the risk of falling out of synchronism. Furthermore, in devices where extreme speed changes occur, since starting stages are not needed here. Practical implementation is e.g. in machine tool control, technological processes, in the textile and metallurgical industries.

Description

The invention relates to a circuit for speed control of at least one closed loop stepper motor comprising a generator, counters, switching logic and closed loop logic.

There is known a method of regulating a stepper motor in a closed loop, described in US. AO No. 179 244 and MS. AO No. 176 509. According to the cited inventions, this control is performed by the combined operation of the stepper motor in a closed loop and an open loop. If the speed of the stepper motor changes, if not set, the stepper motor runs in a closed loop. However, when the stepper motor reaches the set speed, it runs in the open loop. The speed control conceived in this way is not suitable for synchronous running of two stepper motors over the area corresponding to the start-stop frequency.

This disadvantage is substantially eliminated by the speed control circuit of at least one stepper motor according to the invention. Its principle is that the generator is connected via a first counter to the first input of the switching logic, the first output of which is connected to the first input of the closed loop logic. The second switching logic output is connected via the first speed logic switch to the second closed loop logic input. A third output of the changeover logic is connected in parallel via a second logic speed switch. The closed loop logic output is coupled to a stepper motor, whose sensor is feedback coupled via a second counter to the second switching logic input.

The circuit according to the invention realizes the desired stepless change of the speed of the stepper motor without the risk of falling out of synchronism and thus stopping the stepper motor. No acceleration steps are required for the required extreme speed changes.

A specific circuit diagram for speed control is shown in the attached drawing. The generator G is connected via the first counter CTI to the first input of the switching logic PL. the second input of which the sensor <3 of the stepper motor KM is feedbacked via the second counter CT2.

The first switching logic output PL is connected to the first closed loop logic input LUS. corresponding to STOP mode **. The second output B of the toggle logic FL is connected via the first logic switch VP speed, defined and corresponding to the FORWARD STEP SPEED mode, to the second input M of the closed loop logic IAJS. This second input corresponding to the MAXIMUM SPEED mode is connected in parallel via the second speed logic switch jTZ, timed and corresponding to the REVERSE STEP SPEED mode, the third output C of the switching logic PL.

The generator G sets the desired jog frequency. When the supply voltage is switched on, the first CTI counter is filled first and the PL switching logic commences the stepper motor. preselected MAX mode speed corresponding to the first closed loop LUS logic input M. When the second speed logic switch 22 is actuated, the stepper motor KM rotates in REVERSE STEP SPEED to the preset MAX speed. If the first CTI counter fills up earlier than the second CT2 counter. the selected mode remains. Once the stepper motor KM reaches the preset speed and the second counter CT2 is filled earlier than the first ATI counter. the PL switching logic instructs the closed loop logic block to switch to the STOP mode. A braking process occurs. Switching the MAX and STOP modes alternately, whichever the CTI or CT2 ee counters fill earlier, keeps the stepping motor KM frequency at a constant preset value.

The practical implementation of the circuitry according to the invention is particularly applicable to the control of machine tools of various technological processes.

Claims (1)

Circuit for closed-loop stepper motor control, consisting of a generator, counters, switching logic and closed loop logic, characterized in that the generator (G) is connected via a first counter (CT1) to the first input of the switching logic (PL), the first output (A) is connected to the first closed loop logic input (S) (LUS), the second switching logic (PL) output (B) is connected via the first speed logic switch (VP) to the second closed loop logic input (M) ( LUS), to which the third logic output (C) of the switching logic (PL) is connected in parallel via the second logic switch (VZ), the closed loop logic output (LUS) is connected to a stepper motor (KM) whose sensor (C) is feedback coupled via the second counter (Cl2) to the second switching logic input (PL).