Three-phase Diode Clamped Inverter Research Articles

Modelling and Control of a Three-Level Diode-Clamped Medium Voltage Distribution Static Synchronous Compensator using Space Vector Pulse Width Modulation

Efficient utilization of power networks under extreme voltage sags and swells and reducing the losses are widely recognized as the most important issues in energy industry. Power electronic converter based flexible AC transmission system (FACTS) devices play a significant role in power flow control, power quality improvement, voltage regulation and efficient energy utilization. Distribution static synchronous series compensator (D-STATCOM) is a FACTS device and it compensates for voltage sags and swells by injecting or absorbing reactive power to/from the power network. Modulation of D-STATCOMs is mostly based on pulse width modulation (PWM) techniques and space vector PWM (SV-PWM) is attracting considerable interest due to its better DC utilization and wide linear modulation range. In this paper, a three-level SV-PWM is suggested for the modulation of D-STATCOM which is based on a three-phase diode-clamped inverter (DCI). A grid connected three-phase power system feeding a 1 MW and 500 kvar load is designed in simulation environment and D-STATCOM is tested under voltage sags and swells occurring on the generation side. Results demonstrate that D-STATCOM successfully injects/absorbs reactive power to/from the system under fluctuating grid conditions

Simplified Fault Detection Algorithm for Voltage Source Fed Induction Motor

Industrial applications of induction motor were increased these days due to robust construction. When a three-phase diode clamped inverter is driving this induction motor, the knowledge of inverter performance is very much necessary for the proper operation of induction motor drive. Conventional three-level inverter can drive the induction motor for its speed control. Out of various configurations of MLI, Diode clamped MLI is popular. It has the advantages of simple configuration and requires less number of individual DC sources. But the basic knowledge of faults in the inverter circuit can be very handy for the effective design of induction motor drive system. For the fault mitigation basically the fault detection is to be known. This paper introduces a simple algorithm for the fault identification. This algorithm is very much useful in finding the faulty phase. Out of different faults in the inverter circuit, gate driver faults are common and this paper discusses the gate open fault which is very often fault in the inverter circuit. The simple algorithm also can detect the switch in a leg where this fault occurs. This algorithm is very handy for the fault mitigation. The analysis was carried out using Matlab/Simulink software.

A New Modeling and Control of a Five Level Three-Phase Diode Clamped Inverter with Self-Stabilization of the DC Link Voltage

In this paper, the direct modulation strategy of a three-level inverter with self stabilization of the DC link voltage is extended to a five-level inverter. Therefore, a new modeling and control strategy of a five-level three-phase Diode Clamped Inverter (DCI) is presented. The obtained modeling shows that modulated multilevel voltages are obtained by combination of eight different three-level functions, which are called modulation functions. Therefore, a space vector scheme without using a Park transform is explained. Based on this algorithm, the location of the reference voltage vector can be easily determined. Then, the voltage vectors are selected to generate corresponding levels and simultaneously their durations are calculated. Moreover, the redundancies of different switch configurations for the generation of intermediate voltages are used to limit the deviation of capacitor voltages. Simulation results for a five-level three-phase Diode Clamped Inverter are presented to show the good performance of the proposed balancing modulation.

DC Link Capacitor Voltage Balancing in a Three-Phase Diode Clamped Inverter Controlled by a Direct Space Vector of Line-to-Line Voltages

In this paper, the direct modulation strategy of a three-level inverter with self stabilization of the dc link voltage is extended to a five-level inverter. Therefore, a new modeling and control strategy of a five-level three-phase diode-clamped inverter (DCI) is presented. The obtained modeling shows that modulated multilevel voltages are obtained by combination of eight different three-level functions, which are called modulation functions. Therefore, a space-vector scheme without using a Park transform is explained. Based on this algorithm, the location of the reference voltage vector can be easily determined. Then, the voltage vectors are selected to generate corresponding levels and simultaneously their durations are calculated. More over, the redundancies of different switch configurations for the generation of intermediate voltages are used to limit the deviation of capacitor voltages. Experimental results are given to illustrate the proposed control strategy of the three-phase three-level diode clamped inverter. Then, obtained results for a five-level three-phase DCI with the extended version of the control strategy are presented to show the good performances of the proposed balancing modulation.

A general modelling and control algorithm of a three-phase multilevel diode clamped inverter by means of a direct space vector control

This paper presents a simple and general direct modulation strategy that enables to copy directly modulated waveforms onto output voltages of a multilevel three-phase Diode Clamped Inverter (DCI). A general modelling of this converter is presented. A space vector scheme is developed without using Park transforms. Based on this algorithm, the location of the reference voltage vector is determined and the voltage vectors for the modulation are deduced. Simultaneously, their durations are calculated. The proposed algorithm is general and can be directly applied to a (n+1) levels inverter independently on its topology (Diode Clamped Inverter, Neutral Point Clamped, Flying Capacitor Inverter...). To verify this algorithm, both control algorithms of a 5-level DCI and a 11-level DCI are considered and simulation results are given.