SU983965A1 - Device for control of multi-phase stepping motor - Google Patents

Description

(54) DEVICE FOR CONTROLLING MULTI-PHASE STEP ENGINE

12

The invention relates to electrical engineering, in particular, to controlling stepper motors, and can be used, for example, in drives for feeding machine tools with programmed control, coordinate graphs, etc.

A device for controlling multiphase stepper motors is known, comprising a pulse distributor and a multichannel power amplifier, each channel of which includes a main switch connecting the phase, a motor with a low-level DC power supply through a separation diode, and an auxiliary switch connecting the motor phase to high level power source: n and connected by its input to the main key input via a time element specifying the duration of the boost pulse 1

A disadvantage of this device is a large error in the development of a step during asymmetrical switching, when the maximum static torque changes when the number of simultaneously switched phases of an engine changes. In addition, the change in phase currents during oscillations

power supply voltage causes additional phase loss.

The closest in technical essence and the achieved result is a device for controlling a multi-phase stepper motor, which contains a pulse distributor, a multi-channel power amplifier, each channel of which includes an OS10. a key connecting the motor phase with a low-level DC power supply through the isolation diode and an auxiliary key connecting the motor phase.

15 q high level power source, current stabilizer with power and control inputs and output, and elements OR 2 J.

The disadvantage of the known device. 20 va also results in the error in the development of the pitch during asymmetrical switching of phases and the increased losses in the engine at the maximum, the number of included phases and in the parking mode.

25

The purpose of the invention is to increase the efficiency and accuracy of the development of the pitch with non-symmetric switching of the engine phases.

The goal is achieved by

30 that in the device for controlling a multiphase stepper motor containing a pulse distributor, a multichannel amplifier, a current stabilizer and OR elements, elements AND are introduced according to the number of phases of the motor with the number of inputs, equal to half of the number of phases, two additional switches, an inverter and additional stabilizers current, the number of which is one less than half of the number of phases, all current stabilizers are connected by their power inputs to the low-level power supply driver, the outputs to the separation diodes of the power amplifier channels, via two and control inputs, to the outputs of both additional keys, associated control inputs with the output of the OR element, one directly and the other through an inverter, and the inputs of the OR elements are connected to the outputs of all AND elements, each of which is connected to the inputs of the main switches of the power amplifier of adjacent channels with the offset of the connection of the inputs of the subsequent element AND relative to the previous one by one channel. In addition, the third, fourth, fifth, and sixth additional switches, the second inverter, and the pulse width former connected to the inputs are introduced into the device. to the inputs of the distributor, and the output to the control inputs of the third and fourth keys directly, and the fifth and sixth through the second inverter, the outputs of the third and fourth keys are connected to the signal input of the first additional key and the fifth and sixth keys to the signal input of the second additional key . Such an embodiment of the device makes it possible to reduce the difference in the maximum moments of a stepper motor with a different number of simultaneously excited phases due to the regulation of currents in the phases. At the same time, the decrease in phase currents with the maximum number of simultaneously excited phases leads to an increase in efficiency. This is facilitated by the reduction of current in the phases of the engine in the parking mode. Figure 1 shows the functional diagram of the device with respect to a six-phase stepper motor with a twelve-cycle asymmetrical switching; Fig. 2 shows the ve1: torus diagrams of the moments of a six-phase motor with different, number of simultaneously switched on phases. The device contains a pulse distributor 1 connected by outputs to the inputs of multichannel power amplifier 2. Each channel of amplifier 2 includes a main 3 and auxiliary 4 keys that connect the phase of the motor 5 to a low-level DC source and to a high source Level and - directly. The activation time of the auxiliary key 4 is set by the time element 7. Phase 5. The stepper motor is connected to the high level source through the diode 8. A current regulator 9 is connected between the low level power source and the separation diodes 6 (they can be parametric, and pulsed). The current settings at the inputs of all stabilizers are changed by means of keys 10-15, to the inputs of which signals are sent from the buses of the current settings of GT. About Art. Max; IT vr.min; J time Max. The keys 10 and 11 are controlled by a switch mode decoder that detects the number of simultaneously excited phases. The decoder is built on the element OR 16 and elements I. 17. The key 10 is connected to the output of the element OR 16 directly, and the key 11 through the inverter 18. The keys 12-15 are controlled by a speed meter (control frequency) of a stepper motor, for example as . the element OR 19, and the formation of the pulse duration 20. The keys 12 and 14 are connected with the output of the imaging unit 20 directly, and the keys 13 and 15 through the inverter 21. When the pulse distributor 1 is executed according to the circuit with one clock (signal) input and two inputs . By the direction of movement, the element OR 19 is excluded from the speed meter. The device works as follows. If there are no control pulses 1 at inputs B or H of fy, a certain combination of single and zero signal signals is established at its outputs corresponding to a certain number of simultaneously excited phases 5 of a stepper motor. With reference to a six-phase stepper motor controlled by a twelve-cycle switching system, either two or three phases can be simultaneously excited (figure 2). When two phases of 5 resultings are excited, the moment is 1t, for example, for phases that create moments Vl or Hl 11, the number of phase switching cycles where n is a stepping motor (for a twelve-stroke com- mutation); maximum static moment of one phase.

For six-phase motors with two excited phases, the moment is

M .2M -cos. | 1.73MJ. / i-j, ll rtV

When three phases are excited, the resulting moment, due, for example, to moments M; M (figure 2) will be for a six-phase motor

M 2M ... itb. W

Asymmetrical co-knockout of a stepper motor is characterized, as a rule, by a change in the number of simultaneously excited phases by one with the maximum number of simultaneously excited phases close to half the number of phases of the motor (rounded up with an odd number of phases). Thus, with a twelve-stroke switching system of a six-phase stepper motor., Characterizing the sequence by alternating the excitation of either two (M) or three (M-. Phase 5, the resulting moment changes. Approximately 15%, because

Mr-

2-1,73

0.156. 1.73 i

A change in the maximum moment from one switching cycle to another leads to an error in the development of the step, since the magnitude of the rotation angle of the rotor of the engine & is {function of the maximum value of the recurring moment

Mn

& arcsin

M,

mr

where MH is. load moment;

 the maximum value of the resultant moment, equal to H) .1 with two excited phases and M. with three phases. Reducing the motor current with three simultaneously excited phases eliminates the oscillation of the resulting torque, reducing the error in working out the step and reducing the losses at the same time. In the described scheme, this is achieved by introducing three current stabilizers 9 (they can be of any type), the control inputs of which are connected to the outputs of two keys 10 and 11. The signal inputs of keys 10 and 11 are supplied with current settings corresponding to three (3 min) and two (J max excited phases. These signals can come directly from the setpoint buses (as indicated by the dotted line in FIG. 1) if the current in the motor phases 5 remains unchanged as in the parking lot (fi P® 1). T In most

In cases of time, the stepper motor in the parking mode can be reduced (by reducing the current) without detriment to the quality of the system. To change the current in phases 5, in modes 5 of rotation and parking, keys 12–15 are inserted in the circuit, connecting the signal inputs of keys 10 and 11 with the current setting buses and st. min; tl art. Max; 3 times min; GG vr. Max.

ten

The value of the current setpoint at the inputs of the stabilizers 9 and, respectively, IB phases 5 is determined by the state of the elements controlling the motor excitation modes. In the parking mode (f 0), the output of the pulse width generator 20 produces a logical zero signal. In this case, the keys 12 and 14 are closed and, through the inverter 21, the keys are open (are in the conducting state)

20 13 and 15. In this case, the signal inputs of the keys 10 and 11 receive signals of settings J st. min and J Art. max., corresponding to the parking mode (low current in the phases). In this case, the setpoint J st. Min corresponds to three excited phases 5, and the setpoint ZT st. max - two phases. The current settings at the inputs of the stabiq bilizers 9 will be determined

however, the number of simultaneously excited phases 5.

With three excited phases of 5, which corresponds to the presence of a single signal on any three outputs

5 of the distributor 1, one of the logical elements AND 17 detects this combination and produces at its output also a signal of a logical unit that passes through the element OR 16 to the input of the key 10 and unlocks it (puts it in the conducting state). The zero signal at the output of the inverter 18 locks the key 11. As a result, the control inputs of all the stabilizers 9 receive a signal I st. min If the signal of a logical unit is present only at two outputs of the distributor 1 (any), all elements 0 and 17 (their number must be equal to the number of phases of the engine) viral signal of the logical zero, which through the element OR 16 and inverter 18 unlocks the key 11 and locks the key 10 5 At the same time, the inputs of the stabilizers 9 receive a signal of the setpoint I st max that corresponds to two excited phases.

Claims (2)

1. Lutsenko V.E. and others. Electric motor with stepping motors VINITI. Electric drive and automation of industrial installations. Tom.b, 1978, p. 59-60. 2. USSR author's certificate 551788, cl. H 02 R 7/62, 1975. "T ff i / t HUH iBpfow. IcmftaJic. .Ifm. / RaiiA flexcu / f ffaSo / fr6 / ff ffMfof / fezo jfc / n / ffft / c / rnifa ftti.f 8 / y J ffe