31 results about "Three phase diode rectifier" patented technology

The invention provides a T-connected autotransformer for converting three-phase ac input voltages to nine phase shifted ac voltages feeding three sets of three-phase diode rectifier bridges. The nine phase shifted voltages are at an angle of +20 degree or −20 degree with respect to the supply voltages and their magnitudes are essentially identical. The present design requires substantially fewer coils than other autotransformers for 18-pulse AC-DC converters, resulting in saving in space, volume, weight, size and cost of the converter. The magnetics requirement is only about 30% of the drive rating. The output voltage ratio can also be selected to give an average dc output from the proposed converter same as that of a conventional three-phase diode bridge rectifier. However, it is also possible to step up or step down the output voltage as required.

The invention relates to control equipment of power electronics and aims to provide a soft starter used for continuous frequency conversion and voltage transformation of the motor. The soft starter comprises a mechanical switch K1 which is connected with a three-phase electric network power supply, and further comprises a series circuit which consists of an inverter and a fully-controlled high-frequency electronic switch Kd, wherein the series circuit and a capacitor C0 are connected to two output terminals of a three-phase diode rectifier bridge in parallel; the mechanical switch K1 is connected to an input terminal of the three-phase diode rectifier bridge; in the inverter, three pairs of bridge arms are formed by six sets of thyristors Th1,1' to Th6,6'; each pair of bridge arms consistof two anti-parallel thyristors; and the center point of an upper bridge arm and a lower bridge arm of each of the three pairs of bridge arms leads a lead out respectively and is connected to a three-phase asynchronous motor through a mechanical switch K4. In the soft starter used for continuous frequency conversion and voltage transformation of the motor, three functions of regulating voltage, switching off an inverter thyristor, and switching off the main circuit when protection is needed can be simultaneously realized by using only one fully-controlled electronic switch Kd. Simultaneously,due to the adoption of the thyristor inverter, the soft starter has the advantages of simple and reliable circuit, low cost, and great use flexibility.

The invention discloses a high-power and high-step-up ratio photovoltaic DC converter device and a control method. An intermediate frequency 400Hz transformer-based high-power and high-step-up ratio photovoltaic DC converter device with low cost and high efficiency is firstly provided. The high-power and high-step-up ratio photovoltaic DC converter device comprises a multi-channel boost DC transformer, a modular parallel photovoltaic inverter, an intermediate frequency 400Hz three-winding boost transformer, three-phase diode rectifier bridges and high-voltage filter circuits. A control method is disclosed according to the converter device. According to the control method, voltage of an output end of a photovoltaic array is firstly adjusted by using the boost DC transformer, so that the power of the output end of the photovoltaic array is adjusted, and then the power of the output end of the photovoltaic array is transmitted to a transformer side through double loop control of AC / DC side voltage and bridge arm side inductance current of the modular parallel photovoltaic inverter and is transmitted to the final high-voltage DC bus through transformer boosting conversion, diode rectification and the high-voltage filter circuit.

The invention relates to a rectifying technology in the field of power electronics, aiming at providing a three-phase rectifier for realizing current distribution by utilizing auxiliary bridge feedback. The three-phase rectifier comprises k numbered main rectifiers connected in parallel, and k numbered current transformers, wherein the current transformers are respectively connected to the input ends of the main rectifiers, the output ends of the current transformer are respectively connected with three-phase diode rectifiers serving as auxiliary rectifiers; and the auxiliary rectifiers are mutually connected in series, and then are connected in parallel to both ends of the output ends of the main rectifiers connected in parallel. In the invention, the three-phase rectifier of the invention does not need active devices in the process of realizing current distribution, the circuit is simple and reliable, the cost is low; and particularly, the invention can automatically keep current equalization along with the change of loads. Meanwhile, the main rectifiers distribute currents according to a certain ratio rather than a current equalization mode according to the difference of turn ratios of the current transformers matched with the main rectifiers, thereby adapting to the demands of different conditions.

The present invention proposes a high-power high-voltage photovoltaic DC step-up converter device and a control method thereof suitable for direct-current transmission of photovoltaic power stations. The high-power high-voltage photovoltaic DC step-up converter device includes N-way photovoltaic power generation units and Corresponding N-way boost conversion unit, high-power three-phase square wave inverter, modular high-frequency three-phase step-up transformer unit and modular three-phase diode rectifier bridge unit. The converter device modulation adopts open-loop square wave PAM (pulse amplitude modulation), and the pulse amplitude is controlled by the photovoltaic power generation unit and the boost conversion unit, and the control is simple and efficient.