How to Test the Performance of the Brushed DC Motor?

The test includes stator test, rotor (armature) test, motor no-load test, motor load test and dynamometer test. In order to make customers get better experience, improve the test accuracy and test stability while reducing the test time, it is the guarantee of factory product quality and brand service.

There is brushed motors as a general motor, its structure is very simple. It consists of an armature, permanent magnet, brush, end cover and shaft, etc. First is the armature, which is the main part. It is made up of a set of coils capable of rotating freely that are mounted on a positioning platform, which is mounted in the casing. The armature usually consists of multiple windings to increase the efficiency. The second is the permanent magnet, which is the fixed part of the common permanent magnet block (usually ferrite or Ndfeb and other high-performance permanent magnet materials). Its role is to bring a stable magnetic field for the armature, so that the motor can run smoothly. Again, the brush, which is placed on both ends of the armature to connect the armature to the external circuit. Brushes are usually made up of metal carbon, a material that is wear-resistant and can withstand high temperatures. Then comes the end cover, which sits on both ends of the armature to fix the armature and permanent magnet and support the rotating shaft of the motor. End caps are usually made of metal to effectively prevent electronic parts from being contaminated or damaged. Finally, there is the axis, which is the core part of the rotation, connecting the rotating part and the fixed part. Shaafts are usually made of steel or alloy with sufficient strength and corrosion resistance to support operation.

Test resistance value. Before testing your performance, you first need to test its resistance value. This can be done by using a multimeter. Connect two external wiring heads for the motor and two test pins for the multimeter. Read the resistance value and compare whether it matches the resistance value specified in the specification. If not match, this could mean an internal failure. Test the no-load performance. No-load performance test is a method to test the no-load rotation speed and no-load current. To test the no-load performance, you need to connect, drive it using a power supply, and record the speed and current in the no-load state. Comparing these data with the values specified in the specification determines whether the motor is operating properly within the specification range. Test the load performance. Load performance testing is a method to test performance under load, such as torque, current, and rotational speed. Using a load device connected to the micromotor, record the torque, current and rotational speed under different loads. Comparing these data with the specification-specified workshop values evaluates the load performance. Test for efficiency and power. Efficiency and power are one of the most important performance indicators in the practical application. During testing, the test equipment is used to record the output power and the input power. Efficiency and power outputs are calculated from them to compare them with the values specified in the specification. Test life and reliability. Life and reliability are the key factors that determine whether the motor can operate for a long time. For testing, special test equipment is needed to simulate the loss and wear of the motor after long operation. This allows for an assessment of the expected lifetime and reliability in practical applications.

01The stator test

test item： Determine the test instrument: the stator test needs to use the multimeter, electric bridge and other instruments; Disassemble the stator: require disassembly, Remove the stator for testing; Wwiring: connect the test head of the test instrument to the stator, Ensure a secure connection; Test resistance: test the stator winding for resistance with the multimeter, Compare the value and the standard value to judge whether the stator winding is normal; Test the insulation resistance: use a multimeter to test the insulation resistance of the stator winding, Confirm the insulation condition; Test inductance: determine the inductance value of the stator winding using a bridge or LCR table, To understand the winding situation of the stator; Test the open circuit: use a multimeter to detect the open circuit and short circuit of the stator, Make sure that the stator is already cleaned, No winding damage has occurred.

02 Armature test

test item：First, before the test, confirm the model and parameters of the motor structure, and prepare test tools such as multimeter and resistance meter; second, disconnect the power supply, remove the armature and clean, and then measure the resistance value of the brush rotor armature with the multimeter. Generally speaking, the resistance value of the armature should be within the specified range. Beyond the range, there may be a broken circuit or short circuit fault. In addition, the resistance meter can measure the resistance value between the armature and the ground. If the armature insulation performance is not good, there will be short circuit or leakage problems, need to be repaired or replaced in time.

03 Motor no-load test

Its principle is to measure the operation situation under the no-load condition through the no-load operation, so as to understand its performance and reliability, and to provide an important reference basis for the subsequent work. In the no-load test, the current, voltage, speed and other parameters, as well as output power, efficiency and other indicators. These indicators can reflect the output capacity, energy consumption and heat consumption, and provide a strong basis for performance evaluation. In addition, the no-load test can also test the stability and performance of the drive circuit, including the operation of the controller, inverter and other components. By detecting the current, voltage, temperature and other parameters of these components, we can judge the working status, quality and reliability of these components, and provide useful information and technical support for subsequent applications.

test item： First, the motor needs to be connected to the proper power supply. Ensure that the connection is correct to avoid damage. Make sure your test power supply meets the rated voltage and rated current; start the motor and let it run under no load. This means that no load is added to the motor, so it only needs to cope with rotational resistance. You can manually rotate the motor shaft to ensure it works smoothly; use voltages and ammeters to measure voltage and current. You can record data to help you evaluate performance. Ensure the voltage and current match with its rating; test different speeds and record the voltage and current. By testing different speeds, you can assess efficiency and stability and its dynamic response; finally, turn off the motor and remove the test device and plug. Cover a cover to avoid dust. Store them in a dry and safe place for future use.

04 Motor load test

Based on the principle of load test, the motor is tested by adding the load to detect its stability, rotation speed, torque and other parameters. Here's a detailed look at how this test works. Its operation principle is based on the direct current, through the magnetic field to achieve power conversion. When energized, the power supply generates a magnetic field, and the brush draws the current to the armature AC ring to excite the magnetic field on the armature. The magnetic field on the armature changes constantly with the brush, eventually causing the armature to turn. In load tests, we will usually connect it to a certain load. This simulates situations in real runs to better evaluate the performance. The load may be a mechanical load, such as fan, pumps, wheels, etc., or an electronic load, such as a resistors, capacitor, etc. By adding a load, the current and voltage will change. According to Ohm's law, the current is directly proportional to the voltage. Therefore, adding the load will increase the current, reflecting the load capacity. At the same time, we can also measure the performance by measuring the rotation speed and the torque. If it can run smoothly under load and the speed and torque can remain stable, then the performance of the motor is good.

test item： Preparation tool: multimeter, DC power supply, ammeter, resistor, etc. wiring: connect the positive and negative electrodes to the power supply, the ammeter is connected between the motor and the power supply, and the resistor is connected between the ammeter and the motor; adjust the resistor: adjust the initial resistance to the minimum resistance value; measure the current: turn on the power supply, record the current value on the ammeter; adjust the resistor: gradually adjust the resistance of the resistor and measure the corresponding current value. After each adjustment, we should wait for a period of time to ensure the motor steady state; draw the load characteristic curve: record the resistance and speed of different current values, and draw the load characteristic curve in the coordinate system; Through the above tests, we can understand the load characteristics, find out the best working point, to provide support for the normal operation of the equipment.

The above are some professional knowledges on micro brush motor performance test by VSD Motors. For more relevant information, please contact us.