Maine Campus September 26 1957

In traction applications, electrical drivetrain components are subjected to unpredictable load and temperature variations depending on the driving cycle and ambient conditions. As performance and power density requirements are getting increasingly stringent, the power electronic devices and electromagnetic actuators are stressed heavily due to temperature cycling effects and face the risk of overheating, compromising lifetime and reliability. To protect the drivetrain from thermally induced failure, a model-based thermal management strategy is proposed in this paper. Critical component temperatures are calculated online with a combined loss and thermal model and are limited progressively by applying constraints to loss-influencing operating variables. Starting from the requested torque, the dq-current setpoint calculation is formulated as a constraint optimization problem in order to protect all drivetrain components while maximizing overall efficiency over the entire torque speed operating range, including field weakening at elevated speed. Unlike conventional approaches, which are often adhoc or based on de-rating, the proposed strategy allows the drivetrain to operate safely at maximum performance limits, without unnecessarily degrading performance.status: publishe

Dynamic DC-link voltage adaptation for thermal management of traction drives

Power density and reliability specifications for motor drives in traction applications are getting increasingly stringent. The main challenge in meeting these conflicting requirements, is managing heat dissipation. A drive’s peak torque rating is limited by switching device temperatures which must be kept below critical values at all times for the sake of reliability, preferably without major hardware adaptations. In this challenge lies a large potential for advanced control algorithms. This paper proposes a PMSM drive control strategy which combines active thermal management with dynamic DC-link voltage adaptation. The bus voltage level is adjusted to the required PMSM terminal voltage in each operating point. Doing so, switching losses can be reduced at low speed by lowering the bus voltage. At high speed, the voltage level is boosted and field-weakening operation and the associated additional losses are avoided. An 11 kW PMSM drive, with an active front-end controlling the bus voltage, is used as a test setup to mimic a series-hybrid drivetrain. Compared to a fixed DC-link voltage, efficiency maps show a significant inverter loss reduction at low speed. This results in lower switching device temperatures which in turn allows a higher peak torque rating.status: publishe

Comparison of virtual circuit-based control designs for half-bridge converters with LCL output filters

This paper compares the design and performance of two controls for half-bridge converters with LCL output filters based on Virtual Circuit Design method, which is an intuitive way to achieve desired closed-loop behaviours as well as resonance damping and low-frequency behaviours. The first control is represented by a circuit employing a resistor in series with a converter-side inductor to stabilize the resonance while the second one by a resistor in parallel with a filter capacitor. This yields different low-frequency behaviours and different designs of the current controllers. Moreover, both circuits feature the adjustable virtual inductance to improve the bandwidth and the robustness. The experiment illustrates excellent performances from the step response and fair robustness against grid-inductance variation.info:eu-repo/semantics/publishe

Active-Damping Virtual Circuit Control for Grid-Tied Converters with Differential-Mode and Common-Mode Output Filters

This paper presents a virtual circuit control (VCC) method of designing a resonant-damping discrete-time controller for grid-tied voltage source converters with differential-mode (DM) and common-mode (CM) output filters. The method provides an intuitive way to specify the desired closed-loop behavior by means of a virtual reference circuit rather than abstract mathematical criteria such as closed-loop poles and weighting matrices. Therefore, the existing passive filter designs, which cannot be practically implemented due to excessive losses, and the well-established theory of filters can be exploited. The DM grid current and the CM capacitor voltage, which are the primary control objectives, inherit the main properties of their underlying virtual reference circuits, e.g. resonance damping and low-frequency behavior. On this account, to fortify the controller against grid impedance variations, a virtual circuit with a series resistor at the grid side is considered. Accordingly, the CM voltage and DM current controllers can be easily designed based on the low-frequency behavior of virtual circuits. The method can also be straightforwardly equipped with conventional controllers to enhance system performance, such as harmonic compensation. The simulation and experimental results verify the effectiveness of the DM and CM resonant damping and dynamic performance.status: Published onlin