[Daily circuit diagram] 6, see a stepper motor drive circuit "turn"

!! Come from Elecfans : http://www.elecfans.com/article/88/131/194/2015/20151010385722.html

[Guide] Stepper motor in the control system has a wide range of applications. It can convert the pulse signal into angular displacement and be used as electromagnetic brake wheel, electromagnetic differential, or angular displacement generator.

First, preface:

Stepper Motor has a wide range of applications in the control system. It can convert the pulse signal into angular displacement and be used as electromagnetic brake wheel, electromagnetic differential, or angular displacement generator. Sometimes a stepper motor removed from some old equipment (which is generally undamaged) is designed to be used as a driver.

Second, the stepper motor working principle:

The stepper motor is a 14-phase stepper motor powered by a unipolar DC power supply. as long as the various phase windings of the stepper motor are energized by the appropriate timing, the stepper motor can be rotated in step . Figure 1 is the principle of the four-way stepper motor in reverse.

Figure 14 Phase stepping motor stepping

• At the beginning, the switch SB connected to the power supply, SA, SC, SD disconnect, B-phase magnetic poles and rotors 0, 3rd teeth alignment, while the rotor 1, 4th teeth and C, D-phase windings of the magnetic pole produces the wrong teeth, 2, 5th teeth and D, a phase windings of the magnetic pole to produce the wrong teeth.
• When the switch SC is plugged in, SB, SA, SD Disconnect, due to the C-phase winding of the magnetic field lines and 1, 4th teeth between the magnetic field lines between the role of the rotor rotation, 1, 4th teeth and the C-phase windings of the poles aligned. and 0, 3rd teeth and A, B-phase windings produce the wrong teeth, 2, 5th teeth and A, D-phase winding magnetic poles
• Produces the wrong tooth. Alternately, A, B, C, d four-phase windings are powered in turn, and the rotor rotates in the direction of a, B, C, D.

　　four-phase stepper motor according to the order of the power, can be divided into a single four beats, double four beats, eight beats three ways of working . The single four beats are equal to the step angle of the double four beats, but the rotation torque of the single four Beats is small. The step angle of the eight-beat working way is half of the Tanshi and the double four Beats, therefore, the eight-beat working method can maintain the high rotational torque and improve the control precision. The power-on timing and waveform of the Tanshi, double four-beat and eight-shot modes are shown in 2.a, B, and C respectively:

Figure 2: Step Motor operation Timing waveform diagram

Three, stepper motor drive circuit Analysis:

Figure 3 Stepper Motor driver system circuit schematic diagram

　　at89c2051 will control the pulse from the P1 port p1.4~p1.7 output, after 74LS14 reversed phase into 9014, after 9014 magnification control photoelectric switch, photoelectric isolation, by the power tube TIP122 pulse signal voltage and current amplification, driving stepper motor phase windings. so that stepper motor with different pulse signal for the positive, reverse, accelerate, deceleration and stop and other actions. The L1 is a one-phase winding of the stepper motor. at89c2051 Select the frequency of 22MHz crystal oscillator, the purpose of selecting a higher crystal oscillator is to minimize the effect of at89c2051 on the pulse signal period of the host computer under mode 2.

The RL1~RL4 in Figure 3 is the internal resistance of the windings, and the 50ω resistor is an external resistor that acts as a limiting current and is also a component that improves the loop time constant. The D1~D4 is a freewheeling diode that attenuates the back EMF generated by the motor windings through the freewheeling diode (D1~D4), thus protecting the power tube TIP122 from damage.

A 200μf capacitor in parallel with a 50ω external resistor can improve the current pulse front of the winding of the stepping motor and improve the high frequency performance of the stepping motor. The 200ω resistor in series with the freewheeling diode can reduce the discharge time constant of the circuit, make the back edge of the current pulse in the winding steep, the current drop time becomes smaller, and also play a role in improving the high-frequency working performance.

Iv. Software Design:

The drive is available in three ways depending on the different combinations of KX and KY on the dial switch:

Mode 1 is the interrupt mode: P3.5 (INT1) is the step pulse input, the P3.7 is the positive and negative pulse input terminal. The host computer (PC or MCU) is connected to the driver with only 2 lines.

Mode 2 is the serial communication mode: the host computer (PC or MCU) sends the control command to the drive, and the driver completes the control process by itself according to the control command.

Mode 3 is the Dial Code switch control mode: through the different combinations of K1~K5, direct control stepper motor.

When power on or press the reset key KR, the at89c2051 first detects the dialing switch KX, KY State, according to the different combinations of KX, KY, into different ways of working. The program flow diagram and source program for mode 1 are given below.

　　In the process of programming, special attention should be paid to the processing of stepper motor during commutation . In order to make the stepper motor smooth transition when reversing, do not create a wrong step, you should set the flag in each step. wherein the 20H units are stepper motor positive-turn sign, 21H units are reversed flag bit. In the positive rotation, not only the forward flag bit is assigned, but also the reversal flag bit is assigned; In this way, when the stepper motor commutation, it can be the position of the previous location as the starting point of the reverse movement, to avoid the motor reversing the wrong step.

Figure 4 Mode 1 program block diagram

Stepper Motor Subdivision Drive circuit:

In order to control the phase currents of stepping motor, so as to achieve the step angle of stepping motor, people have designed the subdivision drive circuit of many kinds of stepping motor. With the development of microcomputer, especially the appearance of single-chip computer, the subdivision drive of stepping motor brings convenience. At present, the Stepper motor subdivision drive circuit is mostly controlled by a single chip microcomputer. Single-chip microcomputer according to the required step angle calculation of the current value of each phase winding, and output to a digital-to-analog converter (DPA), from the DPA to the corresponding analog voltage, the loop splitter added to each phase of the amplifier circuit, the control amplifier circuit to each phase winding to the corresponding current, to achieve the subdivision of the stepper motor. Single-chip microcomputer-controlled stepper motor subdivision drive circuit according to the operation of the last stage amplifier tube can be divided into large-scale and switch-type two (see 5).

Figure 5 Stepper Motor Subdivision drive circuit

Editorial Review: This article describes a drive that is designed to be a stepper motor removed from a one-day old-fashioned printer. This paper introduces the working principle of the stepping motor, then introduces the hardware and software design of the driver.

[Daily circuit diagram] 6, see a stepper motor drive circuit "turn"