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Modular Multilevel Converters (MMCs) are a new circuit topology to realize multilevel converters. Major advantages of MMCs in comparison to other multilevel converters or standard Voltage Source Converters (VSCs) are lower costs and a modular design for high voltage applications, higher reliability and longer maintenance intervals. However, modular multilevel topologies generally require advanced...
Compared to the conventional analog-circuit control and linear power amplifier for permanent-magnet electrodynamic shaker (PMEDS), a DSP-based digital current control with switched-mode power amplifier is proposed in this paper. A full-bridge converter is connected directly to PMEDS without LC filter in order to directly regulate the shaker current and simplify the digital current control. To meet...
Conventional hysteresis controllers have a major disadvantage of a variable switching frequency. This paper presents a variable hysteresis control method for implementing multilevel modulation of multilevel inverters with constant switching frequency, by using the current error zero crossing time to calculate the hysteresis bands in a switching period. This strategy makes algorithm independent of...
Solid state transformer (SST) is considered the key unit for power processing and conversion in the future distributed renewable energy network. The role of SST is to enable the active management of distributed energy resources, energy storage devices and different type of loads in a distribution grid. Inverter stage of SST supplies sinusoidal voltage to the users. In this paper an improved inductor...
In the low inductance and small-sized brushless DC motor, the conventional PWM driving method makes relatively large copper loss because of an unintended directional transition current caused by ordinary complementary switching in the halfbridge circuits. We implemented the experimental feedforward current control system based on the method proposed by us in which the bridge circuits are driven non-complementarily...
The servo system of a permanent magnet (PM) motor is always required to maintain fine torque and speed response. The current-control system is designed by using the electric parameters of the PM motor. However, motor parameters vary and the current sensors have offset values. When each U-phase and V-phase current sensor has an offset value, the PM motor servo system has the torque ripple and cannot...
A new hybrid excitation permanent machine-doubly fed hybrid excitation permanent magnet synchronous machine without rotor winding is presented. The structure, mathematic model and operation principle of the machine are introduced. It is shown that excitation regulation can be realized by changing the current of stator control winding. The field control performance in the generator and motor operation...
Non-sinusoidal back electromagnetic forces cause torque ripple in permanent magnet synchronous motors. These harmonics should be reduced by means of an appropriate current control to improve performance. Good results have been obtained with linear regulators such as repetitive controllers in synchronous reference frame (SRF) and resonant controllers in stationary frame. Repetitive controllers present...
Conventional control strategies, used in shunt active power filters (SAPF), employ real-time instantaneous harmonic detection schemes which are usually implemented with digital filters. This increases the number of current sensors on the filter structure which results in high cost. Furthermore, these detection schemes introduce time delays which can deteriorate the harmonic compensation performance...
This paper presents design and implementation of a Shunt Active Filters (SAF) for aircrafts power networks using an accurate wide-band current control method based on Iterative Learning Control (ILC). The SAF control system is designed to compensate harmonic currents, within a 400 Hz supply voltage. This work introduces useful design strategies to increase the error-decay speed and improve the robustness...
Interior Permanent Magnet Synchronous Motors (IPMSM) are generally driven by the current control based on the vector control system. However, there exist harmonic components in the current control loop. For the harmonic current, suppression control methods using a repetitive control have been proposed. In the conventional repetitive control, the amount of memory for implementation has not been considered...
Acoustic resonance has been an important problem in high pressure discharge lamp supplies at high frequency due to its undesirable effects such as arc distortion, fluctuation, lamp life reduction, discharge extinction and lamp destruction in the most severe cases. Our method for the injection of adjacent signals allows the restriction of certain selected power harmonics in the lamp in order to avoid...
The article introduces an off-line constant current LEDs driver controller, using the HVLED, an innovative all-primary controller, by STMicroelectronics. Using the proprietary patented technique, the IC is able of providing a constant output current using primary sensing feedback, thus eliminating the need for the optocoupler, secondary voltage reference and current sensor, still maintaining quite...
The paper proposes finite state model based current control of a three-level neutral point clamped (NPC) five-phase voltage source inverter. The space vector model of a five-phase voltage source inverter (VSI) yield 243 space vectors, with 240 active and three zero vectors. The presented technique utilizes only 21 space vectors for the current control and hence the name finite state is given. Search...
This paper introduces a new technique for the distributed voltage and frequency control of the local ac-grid in off-shore wind farms based on synchronous generators. The proposed control technique allows the connection of the off-shore wind farm using a diode based HVDC rectifier. The system comprising the wind farm and the diode HVDC rectifier can be operated in current or voltage control mode. Fault...
In this paper, a dual-loop control scheme is proposed for inverters in three-phase four-wire microgrid applications to improve the power quality within the microgrid and the power quality of the current flowing between the microgrid and the utility grid. The control scheme involves an inner voltage loop and an outer current loop, with both controllers designed using the H∞ repetitive strategy. This...
The article focuses on control strategies of single-phase two-stage grid connected photovoltaic (PV) generation systems. The principle and digital implementation of instantaneous current control, based upon the parameters of the inverter, is presented. This method can be used to achieve accurate tracking results and lower Total Harmonic Distortion (THD) of current. A novel Phase Locked Loop (PLL)...
This paper presents a second order sliding mode current controller for the switched reluctance machine (SRM). This strategy is first analysed theoretically, then tested by simulation and on an experimental test bench. Dynamic, current ripples and robustness of this controller are discussed.
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