For low voltage motor drive applications, in order to enhance the utilisation rate of dc bus voltage and extend the operating boundary of induction motors, the modulation index is often extended from the linear modula...
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For low voltage motor drive applications, in order to enhance the utilisation rate of dc bus voltage and extend the operating boundary of induction motors, the modulation index is often extended from the linear modulation region to the over-modulation region. The relationship between two-level space-vector pulse-width modulation (svpwm) and carrier-based pulse-width modulation (CBPWM) in the linear modulation region has been widely investigated and it was shown that the conventional svpwm is a special type of CBPWM algorithm with zero sequence components injection. On the basis of that, this study focuses on investigating their relationship in the over-modulation region. Firstly, the superposition principle is adopted to analyse the features of svpwm algorithm in the over-modulation region. Second, the modulating functions of CBPWM equivalent to svpwm in the over-modulation modes I and II are derived, respectively, which are on the basis of the CBPWM regular sampling rule. Theoretical analysis shows that svpwm is a special type of CBPWM algorithm not only in the linear modulation region but also in the over-modulation region, which provides a bidirectional bridge for the transformation between svpwm and CBPWM in the full modulation region. Finally, the validity and effectiveness of the theoretical analysis are verified by simulation and experimental results.
This study presents the structure and the space vector pulse-width modulation (svpwm) for power electronic transformer (PET) based on two seven-level cascade H-bridge (CHB) inverters. The DC links of CHB inverters are...
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This study presents the structure and the space vector pulse-width modulation (svpwm) for power electronic transformer (PET) based on two seven-level cascade H-bridge (CHB) inverters. The DC links of CHB inverters are coupled with nine dual-active bridge (DAB) converters with medium-frequency transformers. The DC-link voltages are equalised with two methods - through the control of DAB voltages and through the modulation strategy applied to both CHB inverters. In the proposed svpwm, the influence of vector sequences on predicted DC-link voltages is analysed, and the optimum vector sequence is selected to equalise them. Regardless of this, the proposed svpwm strategy enables the proper generation of output voltage vector also in the case of DC-link voltage imbalance - the calculation of the space-vector area takes into consideration the inequality of the DC-link voltages and its influence on the lengths and positions of active vectors. To simplify the modulation algorithm, the multilevel CHB inverter is considered as a set of three-level inverters connected in series. Each of them is controlled using the same svpwm algorithm. The proposed modulation method reuses the H-bridges with zero duty cycles determined in the initial stages of the output voltage generation process. This enables the optimal management of the DC-link voltage distribution. The experimental research was carried out on a 600 kW/3.3 kV PET. The results are presented in this study.
A space vector pulse-width modulation (svpwm) algorithm and a DC-side voltage control strategy for three-phase four-switch shunt active power filters are proposed. The basic principle of three-phase four-switch invert...
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A space vector pulse-width modulation (svpwm) algorithm and a DC-side voltage control strategy for three-phase four-switch shunt active power filters are proposed. The basic principle of three-phase four-switch inverters to output three-phase balanced voltages is investigated in detail. Based on an advanced coordinate transformation, the proposed algorithm ensures basic voltage vectors to be right on the coordinate axes of alpha beta-coordinate system, which has the advantages of less computation and higher accuracy than the traditional. It synthesises zero vectors by equalising the duration time of two basic voltage vectors, which are equivalent in amplitude and opposite in phase, to simplify control logic and decrease harmonics of output voltages. To stabilise the DC bus voltage and balance the DC-side capacitor voltages, a DC-side voltage control strategy is presented. The former objective is obtained by controlling the active partition of the output currents, and the latter one by adapting the direct partition of phase C output current. An overall control method combining the proposed svpwm algorithm with the DC-side voltage control strategy is presented. Experimental results have shown the validity and feasibility of the proposed algorithm and strategy.
In this study, an artificial neural-network (ANN)-based space-vector pulse-width modulation (svpwm) for capacitor voltage balancing of a three-phase three-level neutral-point clamped converter with improved power qual...
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In this study, an artificial neural-network (ANN)-based space-vector pulse-width modulation (svpwm) for capacitor voltage balancing of a three-phase three-level neutral-point clamped converter with improved power quality is presented. The neural-network-based controller offers the advantage of very fast implementation of the svpwm algorithm. This makes it possible to use an application specific integrated circuit chip in place of a digital signal processor. The proposed scheme employs single layer feed-forward neural-networks at different stages along with a control algorithm using modified reference vector for capacitor voltage balancing of an improved power quality three-phase neutral-point clamped converter. In other words, the neural-network receives three-phase voltages and currents as input and generates symmetrical pulse-width modulation waves for three phases of the converter. A simulated digital signal processor (DSP)-based modulator generates the data which are used to train the network by a back-propagation algorithm in the MATLAB Neural Network Toolbox. The simulation of converter with ANN-based space-vector modulator shows excellent performance when compared with that of conventional DSP-based modulator.
Uniform constant amplitude rotating current vector subdivision and svpwm technology are applied to micro-stepping driving system of three-phase hybrid stepping motor. Decompose the stator current vector of the steppin...
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ISBN:
(纸本)9783037857595
Uniform constant amplitude rotating current vector subdivision and svpwm technology are applied to micro-stepping driving system of three-phase hybrid stepping motor. Decompose the stator current vector of the stepping motor into the torque current and the magnetizing current, and then control the currents of decomposition, which makes the amplitude of the resultant stator current vector remain the same. Simulation results show that the designed micro-stepping driving system realizes equal stepper angle, constant torque, and arbitrary variable micro-stepping driving. The use of micro-stepping driving technology improves the stepping motor's control accuracy and stability, which promotes the application range of stepping motor and has good practical value.
With the rapid development of power electronic devices and microprocessors,AC variable frequency and speed regulating system has also made a *** thesis introduces the hardware circuit design based on TMS320F28335,and ...
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With the rapid development of power electronic devices and microprocessors,AC variable frequency and speed regulating system has also made a *** thesis introduces the hardware circuit design based on TMS320F28335,and the result of the experiment proves the svpwm algorithm is *** also does some research on VF control system of the inverter and the result of the experiments proves that the control system achieves the purpose,and has a quick dynamic response.
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