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This paper presents a new topology of clamped diode multilevel DC/DC buck power converter for a DC motor system. The proposed converter circuit consists of four cascaded MOSFET power switches with three clamping diodes and four voltage sources (voltage cells) connected in series. The main objective of the new topology is to reduce current ripples and torque ripples that are associated with hard switching of the traditional chopper circuit. When the voltage profile of this converter is applied on a DC motor, it positively affects the performance of the DC motor armature current and the generated dynamic torque. The output voltage of the proposed topology shows an adequate performance for tracking of reference voltage with small ripples that are normally reflected into smaller EMI noise. Moreover, it has been shown that the operation of the DC motor with the newly proposed chopper topology greatly decreases the motor armature current ripples and torque ripples by a factor equal to the number of the connected voltage cells. Both simulation and experimental results on a prototype of a DC motor are provided to validate the proposed chopper topology. The results prove that the mechanical vibration and acoustic noises have also been reduced roughly by 13 dBs with a continuous variable input voltage pattern. INDEX TERMS Multilevel DC/DC converter, traditional DC/DC converter, and DC drive systems.

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Summary This paper presents an improved version of the direct power control (DPC) for the distributed generation systems. The improvement is exemplified in using an adaptive proportional‐integral (PI) controller, whose parameters are recursively tuned at any operating condition to reach the minimum error in the shortest possible transient time. This improved DPC is applied to a distributed generation unit that is based on the 5‐level diode‐clamped inverter so that its output power can be easily controlled in a grid‐connected mode. This paper also introduces an innovative technique called direct voltage control to stabilize the loads' voltage in a stand‐alone mode at balanced and unbalanced loads. Both control schemes for DPC and direct voltage control depend on this new combination of the self‐adaptive PI controllers and estimation of the feedback parameters. The simulation results are provided to show the superior performance of the proposed control schemes compared with some other common techniques such as voltage oriented control, conventional DPC, and conventional DPC operated by regular PI controllers. Experimental results are also presented to prove the practicality of the presented adaptive PI controller in a grid‐connected mode.

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This paper introduces a novel control scheme for the operation of multilevel inverters forming a microgrid. The core of the suggested control scheme is an advanced (power-rate) exponential sliding mode controller. This developed controller is robust toward any variation of the system’s parameters and loads in addition to its fast and accurate performance. The presented control scheme provides advantageous characteristics to the microgrid operation in an autonomous mode (microgrid mode) and grid-connected mode. In the microgrid mode, the voltages and frequency are stable at any variable balanced and unbalanced load. In the grid-connected mode, an effective procedure for connecting the microgrid to the main grid is proposed to guarantee a seamless and fast transition to the grid-connected mode. The performance of the presented control scheme along with its proposed controller is validated by comparing its results to another linear and non-linear controllers for the same microgrid loading conditions.