SU928593A1 - Method and device for control of single-phase stepping motor - Google Patents

Description

The invention relates to electrical engineering and can be used to control stepper motors, in particular single-phase stepper motors, in time devices.

There is a known method and apparatus for controlling a single-phase stepper motor, which provide for a reduction in the consumption of the motor in the mode of testing single steps. Stepper motor control in this method is carried out according to a feedback scheme without special feedback sensors. The necessary information about the time of the winding disconnection is obtained on the basis of an analysis of the current in it. The feedback signal is generated using an analog comparator. The power of a single-phase stepper motor is supplied from a generator of opposite-wave pulses, and the moment of the end of the pulse is determined by the signal of the angleswitch comparator, which is produced when the current value of the current coincides with the value of the current in the timing element 1.

A disadvantage of the known method and device for controlling a single-phase I-step motor is that

A comparator that generates a signal to turn off the power of an engine is built on the basis of analogue circuitry, while the generator of power supply impulses of different polarities is based on digital circuitry. Their joint implementation is unjustifiably difficult, requires high supply voltages, increases the energy consumption, so that the known device for controlling a single-phase stepper motor is not advisable to use in miniature time devices with autonomous power supply, in particular in wrist watches. The closest to the proposed technical entity is a method of controlling a single-phase stepper motor, for example, an electronic clock, by applying control pulses to the winding

polarity. A device for implementing this method comprises a clock pulse generator, a divider

25 frequencies, two keys, commuting motor winding, a load detector on the motor shaft and a unit for forming and changing the pulse duration with a time interval setting counter 2J.

A disadvantage of the known control method, in which each positive and negative supply pulse corresponds to a step movement cL ЗЬО / 2р (where p is the number of rotor pole pairs), is the impossibility of increasing the step price to over 180 ° (with p 1), which reduces the efficiency of the drive.

The aim of the invention is to increase the efficiency of the drive.

This goal is achieved by the fact that, in a known control method, the supply to the control winding of current pulses of different polarities while reducing the load, the switching mode changes and the current pulses of one polarity are fed to the motor winding, the duration of which exceeds the duration of current pulses of different polarity.

To implement this method of control, a device containing a clock pulse generator, a frequency divider, two keys, a commutator is used to control the control winding of a single-phase stepper motor, a motor shaft load detector, a forcing unit and a pulse width change with a time counter, an element I is entered, one input of which connected to the output of the shaping unit and changing the pulse duration., the second to the output of the time interval setting counter, and the output to the input of one of the keys, commuting their winding.

The proposed control method and device for its implementation allows one to save the energy of the power source under variable load conditions. At the same time, the step value is increased to ci. 3foO / p, i.e. up to 360 °. This, in turn, allows one to optimize a series of electric drives with single-phase stepper motors, for example, for electronic clocks, in terms of weight and size indicators and efficiency.

Figure 1 shows the angular GL (V) and temporary U (t) diagrams illustrating the operation of a stepper motor; Fig, 2 is a functional diagram of the device that implements the proposed method.

The essence of the method is as follows.

In the case of a low load of the motor (Fig. 1a), the control is carried out by relatively wide unipolar current pulses (voltage and), the duration t. In this case, the rotor is connected with energy -1 sufficient to test the angular displacement equal to the angular period d% 0 ° / f of the electromagnetic synchronizing moment 5t OL increasing the load, starting from some critical level, the energy imparted to the rotor by unipolar pulses becomes insufficient This displacement and the rotor only work out half a step d / 2. The reduction of the step is detected with the help of a motor shaft load detector, which causes a change in the switching mode with unipolar impulses ov

current on opposite polarity with a simultaneous decrease in the duration of the latter (Fig. 16). Unipolar pulses have a shorter duration tf than unipolar and follow one

after another with a small interval. The frequency of occurrence of double opposite-polarity pulses is equal to the frequency of the clock generator f-. Energy W, reported to the rotor at elevated

the load of CPM with each of the opposite-polarity pulses is sufficient to test the displacement equal to d / 2. When the load is reduced, the engine is again switched to single-pole mode.

commutation. Thus, at an increased load of Mc — for working off the displacement of the oL, the rotor is supplied with energy 2W (j, and at reduced load — the energy W -,

moreover, energy W is less than energy

2W.

The proposed control method is most effective in the case when the time interval of an engine for increased load is a small part of the total engine operating time. This, for example, takes place in an electronic clock with additional devices,

such as the calendar and others

which include only 20-30% of the total hours.

A device that implements the proposed control method (Fig. 2) contains a clock pulse generator 1, a frequency divider 2, two

keys 3 and 4, switching the control winding 5 of a single-phase stepper motor, the load sensing on the motor shaft 6, the forming unit 7

and changes in the duration of the pulse of the winding of the engine, the counter set the time interval 8 and the logic element And 9. Clock pulses from the gene, the generator 1 comes

to the input of the frequency divider 2, the output of which is connected to the input of the generating unit 7 and changing the duration of the winding impulses and the input of the counter 8. The counter stroke is connected to the second input of the forming unit 7 and one of the inputs of the logic element I. The third input of the forming unit 7 is connected to the output load detector 6, and the output with the second input of the logic element I. alkhod element And is connected to

key 7. The keys 3 and 4 are connected to the coil 5 of the stepper motor, the output of which is connected to the input of the load detector 6.

The device works as follows.

. In the standard mode with a relatively low load, the unit 7 generates wide single-pole pulses of duration t (Fig. Id), which, via switch 3, power the single-phase stepper motor. The key 4 is closed by an element E 9. When the load from the detector b is increased, a signal is sent to block 7, according to which block 7 forms a sequence of different polar short pulses, the duration of tti (Fig. 15). At the same time, the filling of the time interval setting counter 8 begins, and the And 9 element enables the normally closed key 4 to work. After the counter is filled, the stepping motor is again switched to the control mode of single-pole pulses.

The technical and economic effect of introducing the proposed control method and device for its realization is achieved by reducing energy consumption and increasing the price of the engine pitch, which, as applied to electronic clocks, increases the battery life and reduces the dimensions of the clock.

Claims (2)

1. US patent 41i4364, -kl. G 04 C 5/00, 1978. 2. The patent of Great Britain 35 1.557.408, cl. G 04 C 3/00, H 02 R 8/00, 1977.