![]() To achieve high performance in robotic designs, a field-oriented control (FOC) servo controller with a dedicated CANopen over EtherCAT® protocol stack can provide the best in real-time critical tasks handling – faster than any software-based solution. Sometimes, even a simple upgrade in hardware can make a big difference as we head towards more decentralized systems that demand more power and precision. While intelligent design and proper planning is crucial for innovation, we wouldn’t be where we are now if the technology to achieve it wasn’t available. Since the current on the d-axis is zero, the q-axis current corresponds to the envelope of the phase currents.Pushing the limits of robotics means using the most advanced technology available. The corresponding phase currents are also shown below. Experimental results for the field-oriented control (FOC) of a PMSM – current tracking performance The current controllers on both axes can follow their respective references with fast dynamics and no overshoot. The tracking performance of the torque control was validated experimentally on a modular three-phase inverter by performing a reference step from -1 Nm to 3.9 Nm (nominal torque). Current measurements filtered with a 1.6 kHz cut-off frequency (using the front panel of the B-Box RCP)Įxperimental results of field oriented control.Load torque: 3.9 Nm (PMSM with resistors as load). ![]() Parameter table of Control Techniques 095U2B300BACAA100190 Test conditions The implemented field-oriented control algorithm was validated experimentally on the following PMSM. Another PMSM connected to 3 power resistors is used as a brake to generate a load torque. The power converter is built from 4x PEB 8032 phase-leg modules (3 phases and 1 braking chopper leg). The FOC algorithm is implemented using the graphical programming of ACG SDK library for Simulink. The experimental setup consists of a PMSM supplied by a voltage source inverter controlled by a B-Box prototyping controller. Let us first consider the stator equations of a PMSM in the RRF : The working principle of FOC relies on the machine’s equations in that RRF. Both options are presented in PN104 and TN136, respectively. The position is either measured with an encoder or estimated with a sensorless technique. The position of the rotor must be known in order to orient the RRF. ![]() Therefore, a natural choice is to orient the RRF such as its d-axis is aligned with the rotor flux. In the case of a synchronous machine, the stator and rotor fluxes are synchronous. The currents, voltages, and magnetic fluxes of the machine are expressed as space vectors inside a Rotating Reference Frame (RRF). The Field Oriented Control (FOC) is a form of vector control . ![]() General principles of field oriented control Note: For PLECS users, a model is available for download in the TN114. ![]()
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