Very high bandwidth digital current controller for high-performance motor drives

A fully digital current controller for high-performance motor drives is presented. It is implemented in wired-logic (FPGA). This one-chip controller comprises features such as nonlinear delta-modulated (bang-bang) current control, PWM duty-cycle regulation by PI-loop with anti-windup, programmable and variable switching frequency, flux linkage observer, all for up to 4 phases with 12 bit resolution. The control loops can be executed and the phase currents sampled at rates selectable between 2.5 and 20 kHz. This new, fully digital hardware approach eliminates the noise problems and inflexibility of analog designs, avoids the computational overhead found in DSP software controllers, yet remains flexible and versatile. All the features have been implemented on one device. The design has potential for ASIC implementation as a single-chip current regulator. Tests demonstrate the versatility and performance of the controller and excellent dynamics and large-signal bandwidths in the kHz range are reported.