The performance of active power filter (APF) mainly depends on its harmonic detection method. Empirical mode decomposition (EMD) is applied to APF because of its effectiveness for any complicated signal analysis. Ensemble empirical mode decomposition (EEMD) can suppress mode mixing caused by EMD to a certain extent, but the amplitude and energy of fundamental is severely attenuated. To solve this problem, in this article, the causes of attenuation are discussed from the perspective of intrinsic mode functions (IMFs) energy, and an approach based on two-step improved EEMD is proposed. The first improved step (FI-EEMD) is to suppress the mode mixing and fundamental attenuation by injecting white noise and analytical signal with determined parameters into the target signal. The parameters of the analytical signal are selected according to the power grid conditions and signal characteristics. The second improved step (SI-EEMD) puts forward a signal reconstruction method based on the distribution of IMF energy extreme points and the distinguishing law of signal and noise to reduce the influence of noise-dominated components. The results show that the two-step improved EEMD not only has high-quality extracted fundamental with low total harmonic distortion (THD) and energy attenuation, but also has good applicability to aperiodic and nonstationary signals, which greatly improve the harmonic detection accuracy of APF.

Power module packaging technologies are undergoing extensive changes to satisfy compact high-power-density systems. The advantages of double-sided cooling power module in thermal and electrical compared to wire-bonding are summarized. Some typical double-sided cooling power modules developed by institutes or companies are introduced in detail. The challenges and future trends of double-sided cooling power modules are also highlighted.

DC-Link has been widely used in power electronics applications like photovoltaic systems, electric vehicles, aircraft, and LED drivers. Film capacitors often present a thermal management bottleneck in DC-Link. A significant number of novel film materials have been designed to enhance the high-temperature performance of film capacitors. However, the cost of fabricating these materials into capacitor cores and conducting tests is exceedingly high. Therefore, proposing an efficient modeling method to evaluate the hotspot temperature of film capacitors becomes a burning issue. This article proposes a multi-scale finite element modeling (FEM) method to determine the equivalent characteristics of metallized films composed of various materials, as well as the temperature rise in film capacitor units. Initially, equivalent electromagnetic and thermal micro-scale models of multilayer metallized films are established to analyze the principle of film capacitors and obtain equivalent parameters of metallized polymer film. Subsequently, the temperature rise of the capacitor unit is simulated using the macro-scale model, with validation provided by temperature rise tests and data from product manuals. The proposed approach is straightforward, making it applicable to capacitors with various polymer materials and different shapes, and the error in hotspot temperatures obtained through this method is 2.20%.

Film capacitors are widely used in electric vehicles (EVs) controllers to reduce the adverse effects of ripple current on batteries and converters. But the upper limit of the working temperature for film capacitors is relatively low. High ambient temperatures in EVs can lead to premature failure of film capacitors, thereby impacting the reliability of the controllers. Therefore, proposing a corresponding capacitor lifetime prediction method is a burning issue. This paper analyzes the accumulation of damage and degradation processes in film capacitors and proposes a method to predict their lifetime, which accounts for changes in ESR, thermal conductivity, and internal losses. An analysis on a 440μF film capacitor bank is performed using this method as an example. In addition, the effectiveness of optimizing the capacitor structure to extend capacitor lifetime is analyzed based on finite element modeling (FEM), and the Monte Carlo method is employed to consider the influence of manufacturing tolerances on the reliability of film capacitors. The analysis results indicate that, compared to the original capacitor, the B10 life of the optimized capacitor can be extended by 54.11%.

This paper presents the control strategies for a novel dual-stator flux-modulated (DSFM) motor for application in electric vehicles (EVs). The DSFM motor can be applied to EVs because of its simple winding structure, high reliability, and its use of two stators and rotating modulation steels in the air gap. Moreover, it outperforms conventional brushless doubly-fed machines in terms of control performance. Two stator-current-oriented vector controls with different excitation in the primary winding, direct and alternating current excitation, are designed, simulated, and evaluated on a custom-made DSFM prototype allowing the decoupled control of torque. The stable speed response and available current characteristics strongly validate the feasibility of the two control methods. Furthermore, the proposed control methods can be employed in other applications of flux-modulated motors.

In-wheel direct drive (IWDD) of electric vehicles (EVs), which simplifies the transmission system and facilitates flexible control of vehicle dynamics, has evolved considerably in the EV sector. This paper proposes a novel double-stator double-rotor motor (DSDRM) with a bidirectional flux modulation effect for in-wheel direct drive of EVs. With the proposed special design, a synthetic-slot structure with synthetic materials containing copper and permanent magnets (PMs) in the slots of the motor is ingeniously employed, and the outer and inner rotors are mechanically connected together as a single rotor, making its mechanical structure less complicated than those of two-rotor machines. The main work of this paper involves the design, analysis, construction, and testing of the proposed machine. The DSDRM with a synthetic-slot structure was demonstrated to be feasible by finite element analysis (FEA), prototype fabrication, and experimental results. In addition, vehicle layout with DSDRM is presented and verified by the vehicle road test experiment. Thus, the DSDRM with the synthetic-slot structure can be used as a hub motor for in-wheel direct drive of EVs.