Stepper Motor Tester. Stepper Motor Tester. Manual

Transcription

1 Stepper Motor Tester Manual

2 Introduction A stepper motor is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps. Stepper motors operation differs from the operation of DC brush motors, which rotate when there is a voltage applied to their terminals. To rotate, each step motor needs an external control circuit, such as a microcontroller. Stepper motors, on the other hand, effectively have multiple "toothed" electromagnets arranged around a central gear-shaped piece of iron. The electromagnets are energized by an external control circuit, such as a microcontroller. There are two basic winding arrangements for the electromagnetic coils in a two phase stepper motor: bipolar and unipolar. An unipolar stepper motor has two coils per phase, one for each direction of magnetic field. Bipolar motors have a single winding per phase. The current in a winding needs to be reversed in order to reverse a magnetic pole, so the driving circuit must be more complicated. There are two leads per phase; none are common. All automotive stepping motors are bipolar type. Fig.1 Schematic of bipolar stepper motor

3 The output signals of this tester simulate the signals coming from ECU or lambda control as only difference is that there is a possibility for the user to control the step and the direction of movement of the motor driving mechanism. Features Smart tool with MCU control Allows users to set three levels of operating current through the motor winding Reverse polarity protection Output short circuit protection Overheat protection Toggle switch for selection of the scheme for windings connection. Technical specifications: Power supply: 12V Imax through step motor: 1.5А (750mA for each winding) Adjustable max current: 250mA; 500mA ; 750mA Operating environment: 0 C to +50 C, at <70 % R.H. Dimensions: Weight: 0.25 kg Typical applications of Stepper Motor Tester Check the condition of idle control (IAC), which is filled with stepping motor. With it quickly and easily you can test all idle control motors (IAC) and the lambda control system for gas systems. Cleaning and lubrication of the mechanism of stepping motors. Dismantling and assembling of reciprocating mechanism. Manual control of idle speed. Testing of the stepping motor with lambda control system, in the older gas systems.

4 Operation of Stepper motor tester The stepper motor tester is supplied through 2.5mm DC Plug from 12V automotive battery. After the tester is being supplied the red LED display against Imax = 500mA is switched on. That means the maximum current through each winding is limited to 500mA. This current size is enough in most of the cases that can be met in the practice. By means of toggle switch, located at the front side of the box, the way of both windings connection in the motor coupling is chosen. If the switch is pushed down it turns on when the terminals of both windings are located in the sequence: A-B-C-D (see Fig.1). This is the most common case in the practice and it is shown on Fig.2. Fig.2 The windings terminals are in the following sequence: A-B-C-D The toggle switch is turned on in the up position when the terminals of both windings are located in the sequence: A-C-D-B (see Fig.1). This variant is rarely met in the practice. If there is no information about pin-out diagram of the stepper motor coupling, it can be determined by means of universal multimeter usage in mode

5 ohmmeter. DC resistance of each winding of automotive stepper motors usually is in the rage of 25Ω ~ 60Ω. Through the both buttons indicated with arrows, located in the upper panel of the tester, the stepper motor can be run on right or left direction. At every single pushing of one of the buttons, the motor turns with one step in the correspondent direction, at holding one of the buttons, the motor constantly turns in the correspondent direction till the button release. When there are driving impulses to the motor, the green LED on the box is blinking. Attention! When the exit button is pushed up, there is a danger for the shaft of reciprocal mechanism to pull suddenly out from the gearing position together with the spring! Therefore during the operation with this button, the conical terminal must be held with the finger in order to prevent the shaft pull out. After the automotive stepper motors cleaning and the usage of cleaning or lubrication spray, it is necessary the driving part to be run several times in both end positions by means of stepper motors tester. If the motor turns hardly i.e. its running at 500mA maximum voltage through one of the windings could not be sufficient. In such case the tester has to be set at Imax = 750mA. Thereby the possibility of damaging the stepper motor when moving the contaminated rotor or reciprocal mechanism is completely excluded. After finishing the procedure of stepper motor and its reciprocal mechanism cleaning a test for check of the cleaning quality can be done through setting Imax= 250mA. In case the motor is well cleaned and there are no mechanical defects, the motor should smoothly run at already set maximum value of the voltage through the winding.