Nustenil S. M. L. Marinus

AC-AC single-phase DC-link converter with four controlled switches

An unidirectional single-phase to single-phase component minimized dc-link converter is discussed in this paper. It is composed of one unidirectional rectifier and one bidirectional inverter, using only four controlled switches. Suitable modeling and control strategy of the system, including a synchronization method, are proposed. The synchronization method, associated with the PWM command, guarantees a sinusoidal input current with the same phase angle of the input converter voltage. In this approach, the output converter voltage is also in synchronization with the grid. Proposed method eliminates zero-crossing distortion caused by the use of diodes, as well. Additionally, the control strategy permits the converter to operate with same dc-link voltage value required for the conventional six-switch converter. Simulated and experimental results are presented.

Synchronization method for asymmetrical bridgeless boost rectifier

In this paper a synchronization method and a compatible PWM strategy for the asymmetrical bridgeless boost rectifier are proposed. In this method the grid current is forced to have the same phase angle as the voltage generated by the rectifier. The proposed method eliminates zero-crossing distortion caused by the use of diodes, thus reducing the harmonic distortions of input current. Simulated and experimental results are presented.

AC–DC–AC Three-Phase Converter Based on Three Three-Leg Converters Connected in Series

An unidirectional three-phase to three-phase dc-link converter is proposed, in this paper. It is composed of three unidirectional ac-dc-ac three-leg converters with a shared-leg. The three-leg converter is composed of a non-controlled leg, two controlled legs and a dc-link. A suitable model and control strategy of the systems, including a synchronization method, are proposed. The synchronization method, associated with the PWM strategy allow the grid currents and load voltages have the same phase angle of the input converter voltages. This method ensures sinusoidal grid currents and mitigate the zero-crossing distortions normally caused by the use of diodes. Simulation and experimental results are also presented for validation purposes.

Open-end winding permanent magnet synchronous generator system with reduced controlled switch count

This paper presents an open-end winding permanent magnet synchronous generator system with reduced controlled switch count, which may be applied to Wind Energy Conversion Systems (WECS). The configuration is obtained from the blend of a three-phase controlled rectifier (composed only of controlled switches), a non-controlled rectifier (composed only of diodes) and an open-end winding machine. A detailed model and a PWM control strategy of the systems, including the synchronism technique are presented to ensure the elimination of zero-crossover distortion normally caused by the use of diodes. Simulation and experimental results are also presented.

AC–DC–AC Single-Phase Multilevel Six-Leg Converter With a Reduced Number of Controlled Switches

This paper proposes two unidirectional single-phase ac–dc–ac converters with a reduced number of controlled switches composed of two three-leg converters connected in series. The proposed converters allow us to feed the load voltage with sinusoidal voltages with constant amplitude and frequency and to operate with sinusoidal grid current with a high power factor. The converters can then be used as uninterruptible power supplies and unified power quality conditioners for nonregenerative applications. The system model, space-vector pulse width modulation technique, and a complete control system are given. A method to regulate the dc-link voltages using the voltage vector redundancies is presented. The proposed topologies are compared with the conventional one in terms of operation range, capability to operate with a unity grid power factor, voltage harmonic distortions, semiconductor losses, and others characteristics. Simulation and experimental results in many operating conditions are provided to validate the feasibility of the system.

Six-phase open-end machine conversion system with reduced number of controlled components

This paper presents two six-phase open-end machine conversion systems. They are composed of three three-leg converters connected in series to a six-phase machine with open terminals, in an open-end winding connection. The converters use diodes to replace controlled switches, making the conversion system non-reversible and with a reduced number of controlled components. In this case, the machine must work always as a generator. A study concerning harmonic distortion and semiconductor losses is carried out. PWM and control strategies are developed. Simulation and experimental results in order to test these strategies are presented.

Parallel AC-DC single-phase asymmetrical boost rectifiers

In this paper, three unidirectional single-phase rectifiers are proposed. Each converter is composed of two non-controlled legs and two controlled legs. Modelling and control strategy of the system, including a synchronization method, are proposed. In the synchronization method, the grid current is synchronized with the generated voltage ensuring a sinusoidal grid current without zero-crossover distortions. Analysis of harmonic distortion and semiconductor losses are presented. Simulation and experimental results are shown for validation purposes.

An unidirectional single-phase AC-DC-AC three-level three-leg converter

An unidirectional AC-DC-AC three-level three-leg converter is proposed in this paper. This converter is composed of an unidirectional rectifier and a bidirectional inverter, using two bidirectional NPC legs and an unidirectional NPC leg. A bidirectional NPC leg is shared between rectifier and inverter. When compared with the two-level leg, the three-level leg presents voltage stress reduction on switches for the same DC-link voltage level and also allows a reduction in harmonic distortion for the same switching frequency. Suitable modeling, PWM and control strategies of the system are presented. As the converter is unidirectional, the grid current and the generated voltage at load side must be synchronized with generated voltage at grid side. That eliminates the zero-crossover distortion in the grid current caused by the use of diodes without the hysteresis control. Simulation and experimental results are also presented.

A Bridgeless Controlled Rectifier for Single Split-Phase Systems

An unidirectional single-phase three-wire rectifier is proposed in this paper. Such a proposed topology is composed of a non-controlled leg, two controlled legs and a capacitor bank. A suitable model and control strategy of the system, including a synchronization method, are proposed as well. The synchronization method, associated with the PWM strategy, imposes the grid currents to have the same phase angle of the generated voltages by rectifier. This method ensures sinusoidal grid currents and mitigate the zero-crossover distortions normally caused by the use of diodes. A comprehensive comparison with two conventional configurations is also presented in this paper. Simulation and experimental results are also presented for validation purposes.

A bridgeless controlled rectifier for single split-phase systems

An unidirectional single-phase three-wire rectifier is proposed in this paper. Such topology is composed of a noncontrolled leg, two controlled legs, and a capacitor bank. A suitable model, pulse-width modulation, and control strategies of the system are proposed as well. The control strategy includes the synchronization method, in which it imposes the grid currents with the same phase angle of the voltages generated by the rectifier. This method ensures sinusoidal grid currents and mitigates the zero-crossover distortions normally caused by the use of diodes. A comprehensive comparison with two conventional configurations is also presented in this paper. Simulation and experimental results are also presented for validation purposes.