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202results about How to "Constant voltage" patented technology

Active matrix displays having high contrast values

An active matrix display comprises a chiral smectic liquid crystal mixture which has the phase sequence I-N*-SmC*, a spontaneous polarization in the operating temperature range of <40 nC/cm2 and a pitch of >10 mum at at least one temperature in the nematic or cholesteric phase and comprises at least one compound each from at least two of the substance classes (A), (B) and (C) and one or more compounds from substance class (D):(A): compounds comprising two rings which are directly linked to one another and are selected from phenylene-1,4-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl and pyridazine-2,5-diyl with the proviso that at least one of these rings is a nitrogen heterocycle;(B): compounds comprising three rings selected from phenylene-1,4-diyl, two of the rings being directly linked to one another and the third ring being linked to one of the other two rings via an -OC(=O)- or -C(=O)-group, with the proviso that at least one of the three rings is fluorophenylene-1,4-diyl or ortho-difluorophenylene-1,4-diyl;(C): compounds comprising three rings which are directly linked to one another and are selected from phenylene-1,4-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl and pyridazine-2,5-diyl with the proviso that at least one of these rings is a nitrogen heterocycle;(D): compounds comprising mesogenic groups suitable as components of liquid crystal mixtures.
Owner:MERCK PATENT GMBH

Procedures and Control System to Control a Brushless Electric Motor

The present invention relates to a method and a control system for driving a three-strand brushless, electronically commutated electric motor (2), wherein a line AC voltage (UN) is rectified and fed via a slim DC link (8) with minimum DC link reactance as a DC link voltage (UZ) to an inverter (10) that can be driven to supply and commutate the electric motor (2). A pulsating DC voltage (UG) initially generated by rectifying the line AC voltage (UN) is dynamically increased with respect to its instantaneous values by a step-up chopper (18) in such a manner that the resulting DC link voltage (UZ) with a reduced ripple always lies above a defined limit voltage (U18/U1) over time. The control system consists of a network rectifier (6), a downstream slim DC link (8) with minimum DC link reactance and a controllable inverter (10) that can be supplied via the DC link and driven to commutate the electric motor (2). A step-up chopper (18) is integrated therein with a controller (20) designed in such a manner that, the pulsating DC voltage (UG) rectified by the network rectifier (6) is dynamically increased with respect to its instantaneous values in such a manner that the resulting DC link voltage (UZ) with a reduced ripple always lies above a defined limit voltage (U20/U1) over time. Stray inductances (Ls1-Ls3) of the motor winding heads present in the electric motor (2) are used as inductor (L) for the step-up chopper (18).
Owner:EBM PAPST MULFINGEN GMBH & CO KG

Electrified railway in-phase power supply device and multi-target coordinated instantaneous current control method

The invention relates to an electrified railway in-phase power supply device and a multi-target coordinated instantaneous current control method adopted by the device. After the in-phase power supply device is used, the electrified railway whole-line in-phase power supply can be realized, the output power of two power supply arms of a traction transformer can be balanced, and the negative sequence problem can be thoroughly solved; the load reactive power and the harmonic current can be compensated, and the electric energy quality of a traction power supply system can be comprehensively improved; the voltage of a traction electric network can be stabilized, the transient state stability of the voltage can be improved, the power supply distance of the power supply arms can be increased, and the amount of power substations can be reduced; the electrified railway in-phase power supply device and the multi-target coordinated instantaneous current control method are multiple in targets, the multi-target can be simultaneously controlled, the control harmony at two sides can be guaranteed, the dynamic response capability is stronger; a rectification side inverter takes the active power transfer and the stable direct voltage as a control target, and participates the reactive power control; and an inversion side inverter performs active power, reactive power and harmonic wave control, and participates the stable control of the direct voltage.
Owner:XUJI GRP +2
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