The key to motor transient testing - synchronization

When it comes to motor testing, people often think of how to ensure test accuracy, which requires the use of high-precision measuring instruments, sensors, etc. However, with the development of the motor industry, especially the increasing maturity of motor control technologies such as vector frequency conversion control, testers need to analyze the transient characteristics of motors. At this time, they need to pay attention to a new test point - how to ensure the synchronization of the test.

 

 

 

Why should you care about synchronization of tests?

 

The so-called synchronization means ensuring that each measurement parameter is collected at the same time point in the motor test, which is mainly reflected in the synchronous collection of parameters such as speed, position, torque, voltage, current, temperature, and vibration.

 

 

The most obvious impact of test synchronization on the results is in efficiency measurement. If mechanical parameters such as speed n and torque T and electrical parameters such as voltage U and current I are not collected at the same time point, the results calculated according to the efficiency calculation formula will also be wrong.

 

Motor efficiency calculation formula

 

In addition, for new energy vehicles, variable frequency motors, servo motors, etc., it is necessary to measure the motor driver and the motor synchronously to analyze the system performance of the motor. The synchronization of the test is also the key to analyzing the impact of the motor controller efficiency and motor efficiency on the system in real time. 

 

 

 

Why has there been no focus on synchronization of tests in the past?

 

In the past, the motors tested were mainly asynchronous motors. Testers only needed to measure the parameters under various constant working conditions to obtain their output performance and draw Tn curves or efficiency curves. Even if the test process data is not collected at the same time point, the motor working conditions (speed, torque, etc.) at different times are stable, so the test results are correct.

 

Tn curve of motor

 

However, with the development of motor control technology, more and more motors need to measure their parameters when the working conditions change, such as speed regulation process, load step impact, etc. These transient measurements of dynamic change processes need to ensure real-time synchronization during data collection, so that the obtained real-time data curve has reference value, so the industry has also begun to pay attention to the synchronization of measurements.

 

Motor speed regulation response curve

 

How to ensure the synchronization of tests?

 

Ensuring the synchronization of tests, especially the synchronization of collecting the four most critical parameters of the motor, namely voltage, current, speed and torque, has always been a difficult problem in the industry. The traditional solution is to use multiple instruments and sensors to collect data, and finally upload them through the bus, and perform efficiency calculations on the host computer, which often introduces a delay of ms. For the current motor control change response time of several ms, this delay is unacceptable.

 

Traditional solution vs. Zhiyuan Electronics' synchronous acquisition solution

 

To address this problem, Guangzhou Zhiyuan Electronics' MPT motor testing system adopts a single acquisition terminal solution. Through the new generation of MDA power analyzer designed completely independently, it simultaneously collects and records the motor's voltage, current, speed, torque, and angular position in real time, and calculates the efficiency directly on the acquisition terminal. The synchronization error delay is as low as 10ns, which truly solves the synchronization problem of motor transient testing or dynamic testing.