Dyno Testing for Motor and Motor Controller Development
One piece of test equipment any serious motor or motor controller company will tell you is critical to their development and testing process is a dynamometer. It might not be the first item they name on their list of tools over an oscilloscope or an adjustable power supply, but that doesn’t diminish its importance.
Reading the word dynamometer (dyno) might conjure an image of a sports car or motorcycle strapped down to a large, low platform with the wheels on rollers, with it revving high as a fan blows on it to keep things cool. The output may be graphs of torque and power, showing how performant the vehicle is and used to guide engine tuning or parts upgrades.
The359, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
However, a dyno can take a different form entirely, while in principle remaining a device to measure torque and power. Electric motor dynos consist of:
A drive motor and motor controller, which are usually what’s being tested
A load and a load controller
This may be a variety of brakes: https://en.wikipedia.org/wiki/Dynamometer#Types_of_dynamometers
Or another electric motor and controller
A power supply or battery pack to power the system
Any desired instrumentation
They can range in size from compact, benchtop setups testing motors below 1 kW in output power, to room-size arrangements testing motors in the 100s of kW range. Here’s an example block diagram laying out the different components:
Dyno Block Diagram
What makes a dyno critical in the development of a motor or motor controller is the data it can collect and the simulated field conditions it can create. A well instrumented dyno can measure:
DC input voltage and current to the motor controller
3-phase AC output voltage and current from the motor controller
Motor torque and speed
This allows the calculation of:
Input and output power of the motor controller
Output power of the motor
Motor controller efficiency
Motor efficiency
This allows for the construction of the torque vs speed and efficiency graphs. These can be shared with customers to support their designs, as well as used internally to validate performance relative to the initial design goals.
The dyno can take development further, being used to simulate drive cycles and predict vehicle range. It is also a tool for reliability testing, allowing motors and controllers to be run at their thermal limits for extended periods of time. Lastly, it can be used to set continuous and peak current (for a controller) or torque (for a motor) values. This is done by adding thermal instrumentation and having calibrated and characterized air or water flow over the device under test.
Now, this testing isn’t just useful for companies developing the subcomponents. If you’re developing vehicles or integrating supplier-designed motors and controllers, dyno testing can help too. It can validate powertrain performance ahead of having complete vehicles built, understanding how fast and how far the vehicle will be able to go. It is also a tool to compare subcomponents – you can imagine having multiple controllers tested to see what their true efficiency under the same conditions is before making a final selection.
Boron Energy In-House Dyno
At Boron, our in-house dyno is modular and ready to test your motor or controller. It is built around a motor-to-motor design, where there is a load motor and a motor under test as you can see in the above image. One of these motors is speed controlled, and the other is torque controlled to allow for setting an arbitrary torque-speed point.
We have in-house power supplies capable of up to 120VDC, 150ADC, or 40VDC, 450ADC depending on the configuration. The dyno itself can measure up to 100 Nm of torque and 12000 RPM, and fit motors up to 300mm in diameter and 250mm in length. We have no restrictions on the controller and can provide our own if you’re interested in testing a motor only. Contact us to learn more!
