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Stability of multi-converter power systems, which exist in advanced more electric vehicles, is of great importance. The stability issue is investigated in this paper, and design considerations and limitations of the methods that stabilize the open-loop converters are presented. By stabilizing the open-loop converter, it is shown that the feedback loop design is usually translated into a conventional feedback design task. The behavior of the unstable converter is also discussed, and a method for decreasing the amplitude of the output voltage oscillations is proposed. The model of a tightly regulated practical converter is presented. This model is used to decide how much damping should be added to make the feeder converter stable. Furthermore, because we have this information about the load converter, the feeder converter can be redesigned so that it does not see the load converter as a constant power load. Index Terms--Constant power loads (CPLs), continuous-conduction mode (CCM), damping methods, DC/DC converters, feedback, loop gain and bandwidth, multi-converter power systems, stability, vehicular power systems.

This paper proposes a novel inductor-capacitor-inductor wireless power pickup with directional tuning control (DTC) for a magnetic amplifier. The proposed technique allows the power pickup to achieve full-range tuning/detuning operation to regulate power flow and maintain the output voltage to be constant. The method eliminates the tedious fine-tuning process associated with traditional fixed power pickup tuning methods and eases the component selection. Moreover, it can overcome the online circuit parameter variations and automatically achieve the maximum power transfer capacity when required. In order to meet dynamic load demands, a magnetic amplifier is used as a variable inductor and is controlled by a novel DTC algorithm to change the tuning condition of the power pickup. The effectiveness of the proposed power pickup and its applicability to general wireless power transfer applications have been demonstrated by both simulation and experimental results. Index Terms--Contactless power transfer, magnetic amplifiers, power flow control, resonant power converter, wireless power transfer.

Frequency modulation of the switching signal controlling the electromagnetic interference (EMI) performance of a switching power converter (SPC) is a quite well-known theme that has been previously discussed. Generic Spread Spectrum Clock Generation methods have been theoretically analyzed and finally applied to an SPC's emissions reduction (whereas the previous real applications were focused on digital signals operated by a clock line). From this point of view, a more general denomination of these methods is necessary and Spread Spectrum Switching Generation is here proposed. Effects on EMI emissions reduction are clearly worthy when selecting the modulation parameters in a convenient way. However, most references are focused on reducing the EMI emissions generated by the SPC without taking into account the influence of such frequency modulation methods on the output voltage of the power supply. This paper aims at this point because, in fact, this is the main purpose of a power converter: supplying energy at an ideally constant voltage. Continuous conduction mode of a buck converter is theoretically studied and compared to the practical results obtained from a real power supply. In a first approximation, open-loop configuration was selected as the operation mode before closing the loop, where influence of the modulation is also present but is much more complicated to analyze. Index Terms--Electromagnetic compatibility, frequency modulation, power supplies, Spread Spectrum Clock Generation.

The continuous advance in mechatronics has long attracted researchers toward the development of new highly integrated actuators for automotive applications where reduced space and low weight are common constraints. In this context, Shape Memory Alloys (SMAs) offer many peculiar characteristics that make this technology very attractive for the construction of miniature mechatronic actuators. This paper presents the design, the prototype fabrication, and the functional testing of a case study, where an SMA binary actuator is used for automotive tumble flaps. The innovative solid-state actuation system is proposed as an alternative to electromagnetic and pneumatic effectors, traditionally used to drive the tumble shaft of an air intake manifold for internal combustion engines. Original features of the linear actuator involve the mechanical architecture and the control structure. On the mechanical side, two contrasting sets of SMA springs are used to actively generate the net actuating force during both outstroke and instroke. On the control side, a current feedback is exploited for sensorless real-time monitoring of the working temperature of the SMA springs during electrical supply. Major shortcomings of the proposed solution are a low response time and a power consumption higher than pneumatic and electromagnetic counterparts. Index Terms--Actuators, mechatronics, power converters, shape memory alloys (SMAs).