A hybrid diode/thyristor AC/DC converter includes a thyristor bridge (21) poled oppositely to a diode bridge (13), current through the thyristor bridge being controlled by IGBTs (30, 31). A thyristor turn-off circuit (40-42, 45-47) is responsive to turn-off of the IGBT to reverse bias the thyristors, thereby causing them to turn off. The thyristors and IGBTs are controlled (50) in response to voltage (55-57) of and current flowing (51-53) in the AC mains so as to cause the current flowing to or from the AC mains to be more nearly sinusoidal. The hybrid bridge handles application of regenerative power to the AC mains.
Elevator installations with electric drive systems are equipped with devices (10) to reduce the power supply connection rating which have energy storage units (11) which are formed entirely or partly from so-called supercapacitors (13). The device (10) according to the invention has the effect on the one hand that power peaks during starting and braking operations are compensated by the exchange of energy between the storage unit (11) and motor supply, and on the other hand that the power consumption occurring during a trip is also spread over a part of the at-rest time. Supercapacitors (13) as energy stores tolerate by comparison with electrochemically acting accumulators a much higher number of charging and discharging cycles at high values of current.
A power factor correcting power supply includes an input stage power converter and an output stage power converter. The input stage power converter includes a plurality of series connected boost switches and a power factor correction controller. The power factor correction controller may direct the operation of the boost switches with series interleave phasing to perform power factor correction and voltage regulation. The boost switches are supplied input voltage and input current from a power source. The input voltage is converted to a DC boost voltage by high frequency series interleaved switching of the boost switches. The DC boost voltage is converted to a DC output voltage by the output stage power converter. The DC output voltage is provided on a DC rail for a load of the power factor correcting power supply.
A multilevel converter-based, intelligent, universal transformer includes back-to-back, interconnected, multi-level converters coupled to a switched inverter circuit via a high-frequency transformer. The input of the universal transformer can be coupled to a high-voltage distribution system and the output of the universal transformer can be coupled to low-voltage applications. The universal transformer is smaller in size than conventional copper-and-iron based transformers, yet provides enhanced power quality performance and increased functionality.
A multifunction hybrid intelligent universal transformer includes a conventional transformer coupled with power electronics on the secondary side to enhance the functionality of power conversion. The universal transformer includes features for overcoming the deficiencies associated with conventional transformers, including voltage sag compensation, instantaneous voltage regulation, outage compensation, capacitor switching protection, harmonic compensation, single-phasing protection, DC output, and variable frequency output.
