Low power brushless direct current (BLDC) motors are used in many consumer appliances. These motors have a relatively high winding resistance and therefore current control loop can be avoided in some cases, but fast and accurate speed regulation can be still needed. To minimize harmonics and generated sound noise, improved sinusoidal pulse width modulation (PWM) has been tested in the paper. As the most suitable commutation type, the sine wave with the third harmonic component has been selected. This type of communication reduced the torque ripple of the motor. This paper analyses the possibility to improve traditional proportional-integral-derivative (PID) speed regulator with Fuzzy logic block. A simulation model of BLDC motor, inverter, speed detection circuit and controller have been created. Simulation results showed that by applying the Fuzzy-based PID controller, the transient time can be reduced from 0.2 s to 0.05 s and overshoot can be avoided in comparison with traditional PID controller. Experimental results show a significant improvement in the motor dynamics—the overshoot and transient time were reduced twice. The difference with simulation results and experimental ones can be explained by delays introduced by the microcontroller.

This work analyzes and compares the differences in efficiency between supercapacitor constant-current and constant-power charging under the same boundary conditions, i.e., charging from the same initial voltage to the same final voltage in equal charging times in both variants. Similarly, supercapacitor constant-current and constant-power discharging are compared under the same boundary conditions, i.e., discharging from the same initial voltage to the same final voltage in equal discharging times for both variants. The study included calculations and virtual simulations based on the most frequently used equivalent RC model of supercapacitors. As a result, theoretical calculations and simulations with the RC model confirmed that constant-current charging/discharging is more efficient than constant-power charging/discharging. The results show that this difference is usually not higher than 1%. Practical experiments confirm an almost equal efficiency of both strategies, but it was difficult to validate exactly such small, theoretically calculated differences. Overall, from a practical point of view, the two charging/discharging methods can be considered as close, and nearly equal in terms of efficiency.

Battery energy storage systems are becoming more and more popular solution in the household applications, especially, in combination with renewable energy sources. The bidirectional AC-DC power electronic converter have great impact to the overall efficiency, size, mass and reliability of the storage system. This paper reviews the literature that deals with high efficiency converter technologies for connecting low voltage battery energy storage to an AC distribution grid. Due to low voltage of the battery isolated bidirectional AC-DC converter or a dedicated topology of the non isolated converter is required. Review on single stage, two stage power converters and integrated solutions are done in the paper.

This paper analyzes the control method of a multiphase interleaved DC–DC converter for supercapacitor energy storage system integration in a DC bus with reduced input and output filter size. A reduction in filter size is achieved by operating only in modes with duty cycles that correspond to smaller output current ripples. This leads to limited control of the charging and discharging process of the supercapacitor energy storage system. Therefore, a detailed analysis of the optimal charging strategy is provided in this paper for interleaved converters with different numbers of phases. The results show that such control can be used, albeit with some percentage loss in efficiency. Experimental results are presented in this paper to verify the theoretical results.

The paper presents the concept of supercapacitor based plug-in retrofit kit that can be easily installed on the electric vehicle powered by lead-acid or by other type of batteries without the intervention in the control system to store regenerative braking energy, improve battery lifetime and efficiency. The installation of the retrofit can be done in a simple manner by connecting of only two wires to the DC bus and by installing contactless current sensor on the battery wire. Many control strategies can be implemented to control such system. The energy storage system operation algorithm that stabilizes battery current is studied to extend the battery lifetime. The paper is focused on the efficiency optimization. This purpose is achieved through regulation of supercapacitor based energy storage current proportionally to the battery current in the discharge process. Theoretical equations, Matlab simulation results and experimental results on the test bench are presented in the paper and shows the validity of the approach.

The increasing number of zero-emission vehicles on the roads demands novel vehicle charging solutions that ensure convenience, safety, increased charging infrastructure availability, and aesthetics. Wireless charging technology is seen as the one that could assure these desirable properties and could be applied not just in conventional implementations but also in off-grid solutions together with roadway energy harvesting systems. Both approaches require proper transfer of energy metering methods. In this paper, a method for measuring the power transferred to the load in a wireless charging system is presented, and its systematic error is assessed in the relevant range of influencing factors. The novelty of the method is that it does not require any metrologically certified measurement instrumentation on the receiver side of the wireless charging system. The error analysis is performed using a numerical simulation. Considered error-influencing factors included secondary side electrical load, coils’ coupling coefficient and quality factor, current and voltage quantization resolution, and compensation topology type (serial-serial (SS) and serial-parallel (SP)). It was determined that the systematic error of the power assessment does not exceed 0.7% for SS and 1.1% for SP topologies when the coupling coefficient is in the range of 0.05 to 0.4 and the quality factor of the resonant system is in the range of 100 to 800.