Failure analysis and troubleshooting of stepper motor drivers

1, fault phenomenon: once started, the Driver external fuse (INSUR) will be burned, the device can not run (Windows). The stepper motor driver is an actuator that converts electrical pulse into angular displacement. When the stepper driver receives a pulse signal, it drives the stepper motor to turn at a fixed Angle (called the "step Angle") in a set direction, and its rotation moves step by step at a fixed Angle.

2, fault analysis: maintenance personnel in the inspection, found a power tube has been damaged, but because there is no information (Means), not clear the role of the tube, thought it is the power drive forward push, replace a power tube, after power, the insurance was burned again, replace the tube is also damaged. Stepper motor drive Stepper motor can not be directly connected to the industrial frequency AC or DC power supply work, and must use a special driver, as shown in the figure, it is composed of pulse generation control unit, power drive unit, protection unit and so on. The two units enclosed by dotted lines in the diagram can be realized by microcomputer control. Stepper motor is a kind of induction motor, its working principle is to use electronic circuit, the direct current into time-sharing power supply, multi-phase timing control current, with this current for the stepper motor power supply, the stepper motor can work normally, the driver is a time-sharing power supply for the stepper motor, multi-phase timing controller. After inspection by the maintenance personnel of Specialty, the initial analysis is correct, that is, the fuse is broken again and again, there must be an abnormal large current flow in the driver, and a power tube is damaged. But the function of the tube is not clear. In fact, the tube is the stepper motor power drive tube, the stepper motor for high voltage starting, so it has to bear high voltage current. Static inspection found that in the circuit of the pulse ring distributor, the resistance value from the power supply to the ground is very small, but there is no short circuit (the current does not go through the electrical appliances, directly connected to the power supply poles). According to the number of components in the line and their power consumption, the resistance value from the power supply to the ground should not be so small, so it is suspected that some components in the line are damaged. Power check, found a chip abnormal heating. After power failure, cut off the power pin of the chip, static inspection, the increase of resistance from power to ground should be normal. The resistance of power supply to ground of the chip is very small. Check the chip model, it is a non-standard model, not found in many manuals. Through circuit analysis, it is confirmed that it is the main component in the board: ring pulse distributor. In order to further confirm the problem of the chip, firstly replace the power drive tube of the stepping motor with the same voltage current power, restore the power pin of the chip, and replace the winding of the stepping motor with Electric circuit (replace another substance with one substance (mostly the position of the strong to replace the weak) as the analog load. After power, light emitting diodes are bright, that is, the windings are energized, which is not in line with the requirements of the input step pulse no reaction, import pump

3. Fault (Remove) : Confirm that the chip is damaged. But not on the chip market, under the condition of the drive casing space allows, adopted the combination line which is already at hand D flip-flop and the combination of the nand gate Design (Design) of a circular pulse generator, production on a small PCB, dismantling the original chips will small PCB by pin is installed on the original chip bonding pad. Leds are still used as analog (definition: a virtual load of a real thing or process), which are powered on and then illuminated by stepping pulses in phase sequence. Remove the analog load, connect the host, power on, and the device (SHEBEI) runs normally. The example shows that the Analyse personnel not only need to be able to Analyse Analyse phenomena (overflow), find out the more obvious cause (power tube damage), but also be able to Analyse the primary cause of the failure step by step (pulse generator damage), and use the existing components on hand to replace the difficult component problems.