Abstract: Methods and apparatus for uninterruptible power supply (UPS) systems are provided. The UPS systems are configured to provide the advantages of an in-line device, and operate in a quasi-standby mode. The UPS includes a rectifier unit and inverter arranged to nominally deliver a portion (e.g. up to about 20%) of the primary AC power supply to a critical load through an output transformer. The rectifier unit preferably includes internal energy storage capabilities, such as a capacitor and inductor. The remaining portion of the AC power supply is nominally supplied directly to the critical load and is controlled by a transfer switch and the output transformer. When a fault is detected in the main AC power supply, the transfer switch switches to a faulted position and power is supplied from the rectifier inductor and capacitor or from a battery to the load through the inverter.

Abstract: A staggered-frequency AC inverter includes at least first and second pulse width modulated bridge circuits connected in series. The first bridge circuit receives a DC voltage and operates at a first pulse width modulated switch frequency to generate a first output corresponding to a first region of the AC signal. The second bridge circuit receives a DC voltage and operates at a second pulse width modulated switch frequency substantially lower than the first frequency. The second bridge circuit generates a second output corresponding to a second region of the AC signal in which the AC signal changes less rapidly than in the first region, minus a maximum voltage magnitude of the first region. Another aspect of the invention features a staggered-voltage multiple-phase circuit having at least a first-phase portion for generating a voltage signal in a first phase, and a second-phase portion for generating the voltage signal in a second phase.

Abstract: Movable aerodynamic control surfaces are mounted to a MAGLEV vehicle. They operate in combination with magnetically actuated coils that are located in the vehicle and cooperate with coils or metallic sheets located along the vehicle guideway. Sensors provide clearance information concerning the vehicle relative to the guideway as well as translational speed and vehicle rotational measurements. Based on input from these sensors, a computer positions the control surfaces and energizes the magnetic coils so as to unload dynamic forces and stresses imposed by the vehicle while providing smoother vehicle movement indicative of superior passenger comfort.

Abstract: A two-dimensional fast Fourier transform converter utilizes parallel digital fast Fourier transform processors and a frame serial processing path to convert two-dimensional images of large pixel count (512.times.512 or higher) and high dynamic range (16 bits of pixel intensity quantization) at a rate equal to or exceeding real time processing rate of 30 frames/second. The parallel processors are organized for performing the row and column transformations in a highly parallel and efficient manner. In one embodiment, a uni-directional processing path with segmented image data busses to streamline the data movement is used. In a second embodiment, a bi-directional processing path is utilized such that the fast Fourier transform processors perform row and column conversions sequentially, thus reducing by a factor of two the number of individual fast Fourier transform processors required.