Power Electronics

Recent U.S. Power Electronics Patents

Direct Conversion Programmable Power Source Controller
U.S. No. Patent 6,466,468
Oct. 15, 2002

This invention is a system and method for a direct conversion programmable power source controller. It uses a sampling rate optimized for a transformer used to isolate or to step-up or step-down the power. The power is sampled at the source frequency, and that sampling is phase-angle modulated according to a modulating signal at a frequency representing the sum of the frequencies of the power source and the desired output. After passing the power through the transformer, the invention then again chops that power to produce a multiplication of the power sinusoid with the modulation sinusoid. The output is filtered to integrate the waveform and fed to a load in delta. Between any two terminals of the delta connection, the output voltage presents as a well-formed sinusoid of controlled amplitude and frequency.
Inventors: York; Douglas S. (Langley, Wash.)
Assignee: The Boeing Co. (Seattle, Wash.)


Digital Control of Voltage Harmonic Distortion and Overload Current Protection for Inverters
United States Patent No. 6,466,465
Oct. 15, 2002

This method reduces transient overshoot of an output signal of an uninterruptable power supply, including: (a) an inverter having at least one power switch; (b) a digital controller that generates a pulse width modulated (PWM) signal for controlling the power switch, the PWM signal having a fixed period T.sub.PWM and (c) an analog to digital signal corresponding to the sampled output signal, the method comprising the steps of (1) operating the A/D converter to sample the output signal at a first time to generate a first sampled output value; (2) operating the A/D converter to sample the output signal at a second time to generate a second sampled output value, the period between the second time and the first time being equal to T.sub.PWM ; (3) generating a control input value that is equal to 1.5 times the second sampled output value minus 0.5 times the first sampled output value; (4) computing a PWM signal at a third time, the PWM pulse having a duration equal to the PWM pulse duration, the period between the second time and the third time being equal to 0.5 T.sub.PWM.
Inventors: Marwali; Mohammad N. (Columbus, Ohio)
Assignee: Liebert Corp. (Columbus, Ohio)


Power Factor Correction Circuit
U.S. Patent No. 6,465,990
Oct. 15, 2002

The parallel charge, series discharge method and apparatus for power factor correction and improved efficiency comprises an energy source, two (or more) impedance(s) capable of storing and delivering electrical energy, a switching circuit having one position so that impedance(s) charge in a parallel mode with a fraction of the electrical energy incoming from one (or more) rectified AC input generator(s), and another position so that impedance(s) discharge some of the electrical energy stored into the load, the switch having a frequency and duty cycle so that the input current rectified waveform from the energy source will approximate the voltage rectified waveform from the energy source.
Inventors: Acatrinei; Beniamin (San Jose, Calif.); Lesea; Ronald A. (Redwood City, Calif.)
Assignee: Bensys Corp. (Sunnyvale, Calif.)


Method and Apparatus for Providing a Continuous Supply of Electric Power
U.S. Patent No. 6,463,738
Oct. 15, 2002

This continuous power system provides a continuous supply of power to a load in the event that primary power fails or is degraded. The continuous power system includes an electrical machine, a turbine, and a flywheel coupled to a shaft. When utility power is present, the machine operates as a motor to drive the shaft. During outages, the electrical machine operates as a generator to provide power to the load. Kinetic energy stored in the flywheel drives the shaft during initial power interruptions. During further short-term interruptions, a thermal energy supply (or thermal storage device) is used to provide vaporized liquid to the turbine so that the turbine drives the shaft. If the power loss or failure is extended, the turbine is driven by vapor produced by an evaporator heated from an external fuel supply. Numerous methods and apparatus are also described for reducing system losses and improving overall performance.
Inventors: Pinkerton; Joseph F. (Austin, Texas); Clifton; David B. (Leander, Texas); Nichols; Kenneth E. (Arvada, Colo.); Forsha; Michael D. (Golden, Colo.); Dillard; James E. (Denver, Colo.); Batton; William D. (Arvada, Colo.)
Assignee: Active Power Inc. (Austin, Texas)


Lossless Switching DC-DC Converter
U.S. Patent No. 6,462,962
Oct. 8, 2002

This lossless switching DC-DC converter with novel lossless switching time control for up to four controllable switches, with each switch meeting the specific current-voltage switching characteristics, operates at ultrahigh efficiency in a compact size and offers additional performance advantages, such as low EMI noise, low switching ripple currents, and improved reliability.
Inventors: Cuk; Slobodan (Laguna Hills, Calif.)


Method of Connecting Synchronous Rectifier Modules in Parallel without Output Voltage Faults
U.S. Patent No. 6,459,600
Oct. 1, 2002

This method prevents a fault condition in a DC-DC converter (10, 20, 50) having a first secondary winding (Ns1) coupled to a first synchronous rectifier (SQ1) and a second secondary winding (Ns2) coupled to a second synchronous rectifier (SQ2). The first synchronous rectifier (SQ1) is turned on based on a voltage across the first secondary winding (Ns1) and is turned off based on a first driver signal. The second synchronous rectifier (SQ2) is turned on based on a voltage across the second secondary winding (Ns2) and is turned off based on a second driver signal. It also provides a DC-DC converter (10, 20, 50) wherein a first control circuit is coupled to and controls the first synchronous rectifier (SQ1) pursuant to the method described above, and a second control circuit is coupled to and controls the second synchronous rectifier (SQ2) pursuant to the method described above.
Inventors: Farrington; Richard W. (Heath, Texas); Svardsjo; Claes (Richardson, Texas); Hart; William (Plano, Texas)
Assignee: Ericsson Inc. (Richardson, Texas)


Power Electronics Cooling for a Hybrid Electric Vehicle
U.S. Patent No. 6,450,275
Sept. 17, 2002

This invention is a method and system for cooling Hybrid Electric Vehicle (HEV) components. It cools HEV components, including an ac system, an internal combustion engine and its associated parts, an electric drive system and its associated parts, including an inverter, a DC-DC converter, a generator motor, and a traction motor. Cooling these components is accomplished by implementing a cooling system that is comprised of fluid filled cooling loops, radiators, fans, pumps, an air conditioning condenser, and a controller. The pumps move the fluid through the cooling loops, allowing the fluid to absorb heat from the components and vent through the radiators with help from the fan's airflow. The controller monitors component temperature data by measuring actual component temperature or corresponding coolant temperature, and compares the component temperature data to a calibratable threshold to determine whether the fan should operate. By controlling fan speed, the controller regulates airflow across the radiator and air condenser to maintain coolant temperature and, subsequently, component temperatures within acceptable parameters.
Inventors: Gabriel; David (Royal Oak, Mich.); Kotre; Stephen John (Ann Arbor, Mich.)
Assignee: Ford Motor Co. (Dearborn, Mich.)


Multilevel Quasi-resonant Power Inverter
U.S. Patent No. 6,449,179
Sept. 10, 2002

This power inverter includes a multilevel switching circuit for switching between any two voltage levels selected from a set of N voltage levels. The switching circuit includes at least N+1 switching elements. Each switching element has a corresponding resonant capacitor connected parallel to it. As the switching elements turn on and off, different ones of the resonant capacitors cooperate with a resonant inductor connected to a pole of the switching circuit and with an output capacitor in maintaining a resonance condition as seen from the active switching elements.
Inventors: Reichard; Jeffrey A. (Oconomowoc, Wisc.)
Assignee: American Superconductor Corp. (Westborough, Mass.)

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