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Five-level neutral point clamped H-bridge (NPCH) converter has been found practical application due to its low EMI and high output capacity. However, the unbalanced loss distribution of semiconductor devices in NPCH converter would limit the lifetime and the output capacity. In this paper, a five-level active neutral point clamped H-bridge (ANPCH) converter topology is studied, which is composed two...
On the basis of the novel single-phase five-level rectifier based coupled inductor, two-octave instantaneous power of this rectifier is analyzed and the method of removing LC resonant filter circuit is proposed which can simplify the circuit structure, reduce the circuit size, and improve the power density of the rectifier. Corresponding formula derivation is carried on which shows that two-octave...
This paper proposes a novel PWM strategy for three-level active neutral-point-clamped (ANPC) converter, this strategy can balance the power losses of all semiconductors and eliminate the fluctuation in the neutral point voltage over full range of converter output voltage and for all load power factors of ANPC converter. The performance of this modulation approach and its benefits are verified through...
High-power single-phase PWM rectifiers for medium voltage drives operate at low switching frequency to maintain the switching losses of the power semi-conductor devices at an acceptable level. For these applications, selective harmonic eliminated pulse width modulation and synchronous optimal pulse width modulation methods permit a good trade-off between switching losses and harmonic distortion of...
In the application of power converters constructed by IGBTs, the temperature rise of IGBTs is often considered to ensure safe operation of the system. The thermal distribution of a single-phase Pulse Width Modulation (PWM) rectifier is studied here. Based on accurate power dissipation of IGBTs and DC busbar, a thermal circuit model and a Finite Element Method (FEM) model are given to solve the temperature...
The acoustic noise spectrum in power electronic system is closely related to the spectrum of the voltage waveform and can be reduced by avoiding the concentration of harmonic energy in distinct tones. Frequency jitter and randomized pulse width modulation are two methods to reduce mechanical vibration and acoustic noise in power electronic. These two techniques can make the harmonic spectrum of inverter...
The voltage balancing control (VBC) ability of the three-level neutral point clamped (NPC) rectifier under standby and light load conditions is weakened because the phase current direction changes very quickly and the self-balancing ability of conventional space vector modulation (SVM) is not ensured. In order to improve the VBC ability, current prediction method together with the multi-sampling technique...
This paper presents a three-level neutral point clamped (NPC) back-to-back converter with IGCT for high power ac drive. The power circuit topology of the three-level NPC back-to-back converter and the hardware control system based VMEBUS and TMS320F28335 DSP are introduced. Voltage-Oriented Control (VOC) with feed-forward decoupling control for the front-end PWM rectifier and rotor field oriented...
Nowadays, most of the electrical railway tractions, especially the high-speed tractions are using AC-DC-AC power driving system. The best choice for the AC-DC link is four-quadrant PWM rectifier, which can provide controllable DC link voltage and better power factor for the grid. In high power drive applications, the switch frequency of the power semiconductor device cannot be very high, usually less...
Nowadays, with the demand of high speed traction applications, for example traditional locomotive or Electric Multiple Units, medium-voltage high power AC drives are required. In the high power AC drives, the switch frequency of the devices has to be limited in order to reduce the loss of the power semiconductor devices. The modulation strategy is made up of asynchronous modulation, synchronous modulation...
The Specific Harmonic Elimination Pulse Width Modulation (SHEPWM) is used in a neutral-point-clamped converter. The SHEPWM is implemented in a DSP chip by software. Transient current between different PWM in open loop operation is small. Simulations of close loop control show that work of SHEPWM in dynamic process requires the voltage vector rotate steadily while the requirement on its length change...
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