In 1960’s and 1970’s motors were controlled by means of hardwired control which uses gears, levers and other basic mechanical devices. The primary negative aspect of mechanical control was that reliability was in contrast to the maintenance costs associated with keeping these panels operating which were extremely high. A second major factor was the time, expense and labor required when a change in control needs dedicated a control panel modification. Depending on application, changing the speed of motor using hardwired control is tedious because hardwired control involves both manual and mechanical operation i.e. changing the terminals etc. To overcome the drawbacks of hardwired control several modern techniques had been developed. Among them a very easiest technique to control the stepper motor speed control by using UCN5804B translator. With this technique almost endless variety of motion systems can be controlled. Our project deals with speed control of stepper Motor through UCN5804B translator. Owing easy understandable and more efficient and performance. We have done project on speed Control.
This project allows you to control the speed, direction, and step size of a unipolar four phase stepper motor. The controller is capable of handling motor winding currents of up to 1.25 amps per phase and it operates from a single supply voltage of 6-30 volts DC.A unique feature of this project is that the circuit can operate in either remote mode or stand-alone mode. In the stand-alone mode, an on-board pulse generator and a four-position DIP switch allows you to demonstrate all of the functions without any additional connections. This mode is perfect for demonstrating basic stepper motor control principles. The circuit even has LEDs that show the energized phases for each step. In remote mode, all motor functions can be interfaced to external logic or a microcontroller. This allows the controller to be incorporated into a robot, an X-Y plotter, or any motion control project.
Refer to the schematic of the stepper driver shown in Figure 1. Power is supplied by a DC wall transformer or DC power supply at P1.The voltage can be anything from 6 to 30 volts, depending upon the rating of the stepper motor. The stepper motor uses most of the current in this circuit, so it is powered directly from the transformer output through resistors R1 & R2.These resistors limit the current to the motor and allow the motor to be operated with a power supply voltage greater than the voltage rating of the motor for improved performance. Stable voltage for the rest of the circuit is obtained by regulating the input voltage down to 5V with U4, a LM78L05 voltage regulator IC. Capacitors C7, C1, and C5 provide additional voltage filtering. U1 is capable of supplying up to 100 am of current. The heart of the stepper controller is U1, UCN5804B stepper-motor translator/driver IC. It contains a CMOS logic section for these quenching logic and a high voltage bipolar output section to directly drive a unipolar stepper motor.
U1 can generate waveforms for three different sequence modes:
- FULL-STEP with two phases energized
- FULL-STEP WAVE
The waveforms for these three sequence modes are shown in Figure 5. Diodes D1-4 are clamps to prevent damage to U1 if the outputs swing below ground when driving The inductive load of the motor. Each of the LEDs L1-4 light when the corresponding output goes LOW and are useful for observing the output waveforms. Resistor R3 provides current limiting to the LEDs. Pins 9, 10, 14, and 15 of U1 are control inputs for phase, half step, direction, and output-enable. These signals are pulled-down to a logic LOW level by resistors R7-11.
The control signals go to both connector P3 and the four-position DIP switch (S1-4). Switches 1-4 allow for manual control of each function, or alternatively, connector P3 allows the functions to be controlled by external logic or a microcontroller chip. The UCN5804B requires an external pulse input on pin 11 to advance the stepper motor. This signal can be supplied by external logic via connector P3 or can be provided byU2 or U3. U2 and U3 are LM555N timer ICs and are used to provide single step or continuous pulses to U1.U2 is configured as an astable oscillator that delivers continuous pulses. The pulse rate is controlled by potentiometer R13 and capacitor C2.Jumper J2 connects C6 in parallel with C2 to give a LOW SPEED range. U3 is configured in a monostable mode to produce a single pulse when S5 is pressed. Jumper J1 selects between the single-step or continuous mode.