µC/Probe Oscilloscope Feature: BLDC Design Case Study

µC/Probe 4.0, the latest release of Micrium’s embedded visualization tool, simplifies the design of Brushless DC (BLDC) Motor Control Applications by providing a unique capability to do system-debug on the motor drive power stage, motor performance, and the embedded application's control system algorithm.

µC/Probe 4.0 introduces its new oscilloscope control, which allows users to system-debug embedded applications in real-time and in even more detail. This new oscilloscope control allows users to analyze data in real-time by showing the value of multiple memory addresses in a screen akin to an oscilloscope. Similar to other controls in µC/Probe, simply select the variables you want to plot right from the µC/Probe screen.

The advantage over a traditional oscilloscope is that besides being able to plot any global variable in your embedded application, you can also plot any of the chip’s I/O registers without having to configure a DAC to convert it to a voltage signal, something that would be necessary if using a conventional oscilloscope.

To illustrate the benefits, consider the case of Brushless DC Motor Control Applications:

A brushless DC motor is a rotating electric machine with a classic three-phase stator like that of an induction motor. The rotor has surface-mounted permanent magnets. Polarity reversal is achieved by power transistors that switch in synch with the rotor position.

Typical designs use Hall Effect sensors or a rotary encoder to directly measure the rotor's position. Rectangular voltage strokes coupled with the given rotor position are what drive the brushless DC motor as shown by µC/Probe in the screen capture below. Notice how the three waveforms are phase shifted by 60 degrees to ensure a smooth operation:

Image 1 uCProbe Oscilloscope

The generated stator flux interacts with the rotor flux, which defines the torque and the motor's speed as shown in the following screen capture where the holding torque is 0.75 Nm, the cutoff speed is 600 RPM and the maximum speed is 1600 RPM:

Image 2 uCProbe Oscilloscope

Common applications of BLDC Motor Control include food packaging, logistics systems, power tools, robots and light electric vehicles, among others. To achieve higher demands in terms of dynamic behavior in the form of quiet motors with smooth acceleration, engineers use µC/Probe to system-debug the control algorithm in real-time as shown in the µC/Probe data screen below, where µC/Probe allows them to use an empirical tuning procedure to change the PI controller parameters and see the effects such as rise-time, settling-time, steady-state error and overshooting in real-time.

Image 3 uCProbe Oscilloscope

Image 4 uCProbe Oscilloscope

µC/Probe 4.0 is available today! Contact us to learn more.

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