Abstract
One of the main power quality issues that can affect variable speed drives (VSDs) is the occurrence of voltage sags on their AC power supply. Voltage sags can affect the inverter nominal operation, leading to a malfunction of the AC motor. This paper presents an inverter with resilient capability to voltage sags. The topology consists of two conventional three-phase bridge inverters arranged to require just a single DC source. This inverter is also characterized by a voltage multilevel operation, providing the full advantages of multilevel converters without the need for level balancing. Associated with this AC motor driver, a control system based on a field-oriented controller with a vector voltage modulator that will enable voltage sag ride-through capability is proposed. The proposed control system does not require any changes in the occurrence of voltage sags. To verify the characteristics of the proposed drive and control system, simulation tests are provided. Simulation results confirm the voltage sag resilient capability of the proposed multilevel converter.
Highlights
A major issue in industry applications is related to the power quality in the AC electrical grids [1].due to the lack of AC power quality, important and costly losses in several industrial and business companies have been reported [2]
This work addressed the issue of voltage sags in AC variable speed drives (VSDs) with open-winding motors
To voltage the floating capacitor. capability, a multilevel inverter was proposed based in a Dual provideofvoltage sag ride-through
Summary
A major issue in industry applications is related to the power quality in the AC electrical grids [1]. A solution that was used to overcome the problem of voltage sags based on a similar approach to the cascaded H-bridge inverter but that does not require DC voltage sources was proposed in [30] In this approach, three single-phase inverters with a floating capacitor connected between the grid and the motor were used. To obtain multilevel inverters using just well-known three-phase two-level VSIs, a new topology was proposed in [31], where the motor windings, in open-end configuration, are connected to two three-phase VSIs, each one at one side of the windings This structure has the disadvantage of requiring two DC voltage sources. To provide a better voltage sag ride-through capability in VSDs, this paper proposes the use of open-end windings and dual VSI structure for the AC VSD This solution does need any extra power converter or components. The performance of AC VSDs fitted with the dual VSI structure is tested through several simulation tests
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