This paper proposes an improved and robust method of minimizing the error in propulsion-drive line-currents that are reconstructed from a single dc-link current measurement. The proposed algorithm extends and then shortens the relevant phase pulse-widths in order to provide optimal sampling of the dc-link currents in two consecutive pulsewidth modulation (PWM) periods. The proposed PWM pattern control enables an improved sampling method which cancels offset jitter-like waveform errors present in all three reconstructed line-currents, which is due to a specific combination of nonsimultaneously sampled dc-link current and line-current PWM ripple. The improvement in induction motor drive accuracy using a single current-sensor and no shaft sensor (as proposed in this paper), over that of conventional methods, is shown. Thanks to an ultra-low latency hardware-in-the loop (HIL) emulator, the proposed algorithm, its implementation on a DSP processor, code optimization and “laboratory” testing were all merged into one development step. In order to perform final tests of the proposed current-reconstruction algorithm and to verify the usefulness of the developed HIL platform by means of comparison, experimental results obtained on a real hardware setup are provided.

The smart grid concept is a good example of a complex cyber-physical system (CPS) that exhibits intricate interplay between control, sensing, and communication infrastructure on one side, and power processing and actuation on the other side. The more extensive use of computation, sensing, and communication, tightly coupled with power processing, calls for a fundamental reassessment of some of the prevailing paradigms in the real-time control and communication abstractions. Today these abstractions are mostly thought of as embedded systems, and the overall framework needs to be reformed in order to fully realize the potential of the emerging field of cyber-physical systems. This paper details the design and application of a new ultrahigh speed real-time emulation platform for Hardware-in-the-Loop (HiL) testing and design of high-power power electronics systems. Our real-time hardware emulation for HiL systems is based on a reconfigurable, heterogeneous, multicore processor architecture that emulates power electronics, and includes a circuit compiler that translates graphic system models into processor executable machine code. We present the hardware architecture, and describe the process of power electronic circuit compilation. This approach yields real-time execution on the order of 1μs simulation time step (including input/output latency) for a broad class of power electronics converters. To the best of our knowledge, no current academic or industrial HiL system has such a fast emulation response time. We present HiL experimental results for three representative systems: a variable speed induction motor drive, a utility grid connected photovoltaic converter system, and a hybrid electric vehicle motor drive.

A lumped-parameter model of a piezoelectric stack actuator has been developed to describe actuator behavior for purposes of control system analysis and design, and in particular for microrobotic applications requiring accurate position and/or force control. In addition to describing the input-output dynamic behavior, the proposed model explains aspects of non-intuitive behavioral phenomena evinced by piezoelectric actuators, such as the input-output rate-independent hysteresis and the change in mechanical stiffness that results from altering electrical load. The authors incorporate a generalized Maxwell resistive capacitor as a lumped parameter causal representation of rate-independent hysteresis. Model formulation is validated by comparing results of numerical simulations to experimental data.