A resonant power transfer system includes resonant circuitry (26) including an inductor coil (59) and a resonant capacitor (51) coupled to a first terminal (27) of the inductor coil, wherein the inductor coil and the resonant capacitor resonate to produce an excitation signal (I.sub.S) and a state variable signal (V.sub.CS1). Sub-sampling circuitry (30) samples first and second points of the state variable signal at a rate which is substantially less than the RF frequency of the state variable signal. Information recovery circuitry (32) produces a state variable parameter signal representing a parameter (A) of the state variable signal from information in the first and second sampled points. Control circuitry (38) produces a first control signal in response to the state variable parameter signal. Detection and optimization circuitry (41) produces a second control signal in response to the state variable parameter signal. Voltage regulation circuitry (45) produces a regulated supply voltage in response to the first control signal. Switching inverter circuitry produces the excitation signal in response to the regulated supply voltage and the second control signal.

A resonant inductive coupling extension cord and light emitting diode system having a plurality of light emitting diodes (LEDS) connected to a receiver coil designed to receive a pulsed DC current from a power supply by means of resonant inductive coupling. The power supply generates a pulsed DC current at a frequency of 0.8 KHz or greater, wherein the pulsed DC current is positive relative to ground. The power supply provides the pulsed DC current through a power coil and through the extension cords to the receiver coil. The (LEDs) are powered through resonant inductive coupling up to 160 volts. The light emitting diodes are self-limiting with respect to current. There is no potential for a spark or shock hazard when the extension cords are connected to the power supply, to the LED system or each other or whether the extension cords or LED are cut or broken.

An inductive power transmitter comprising: at least two switching elements connected across a resonant circuit, the resonant circuit including an inductance and a capacitance; wherein the transmitter is configured to adjust the value of the capacitance based on a desired operating frequency.

Embodiments of the subject invention are drawn to power supply units and systems for supplying power to loads. Specific embodiments relate to systems incorporating the loads. The power supply units and systems can include a feedback mechanism for monitoring the system and maintaining a parameter of interest at or near a desired value (e.g., for maintaining the frequency of operation at or near resonance). The feedback mechanism is configured such that, if the at least one parameter indicates that the frequency of operation is away from a resonant frequency of the power amplifier, the feedback mechanism adjusts the frequency of operation closer to the resonant frequency of the power amplifier. The at least one load can have a variable impedance, though embodiments are not limited thereto.

An electric power converter for converting AC to DC power or DC to AC power is disclosed. The converter includes a circuit for controlling the voltage and the circuit for controlling the current separately. The voltage is controlled by the switching modules and the up-side controller using the calculated target voltage. The current is controlled by the current controller using the calculated target current.

An electrical drive system for a vehicle. The system includes a plurality of electric propulsion motors and a plurality of corresponding inverter circuits. The system also includes an auxiliary motor for driving an auxiliary device located in the vehicle. The auxiliary motor is connected to the propulsion motors and is driven by the inverter circuits. The system does not include a separate inverter for driving the auxiliary motor.

To improve control characteristics of an inverter while suppressing manufacturing cost. An inverter control device 10 is a device for controlling an inverter device 1 having a plurality of switching elements. The inverter control device 10 includes a current control unit 13 that calculates three phase voltage command signals Vu*, Vv*, and Vw* based on a d-axis current command signal id* and a q-axis current command signal iq* at each predetermined calculation period T0, a sampling period conversion unit 14 that outputs three phase voltage command signals Vu**, Vv**, and Vw** after update at each predetermined update period T1 different from the calculation period T0 based on a calculation result of the three phase voltage command signals Vu*, Vv*, and Vw* by the current control unit 13, and a gate signal generation unit 15 that generates a gate signal for switching-driving a plurality of the switching elements based on the three phase voltage command signals Vu**, Vv**, and Vw** after update output from the sampling period conversion unit 14.

Disclosed herein is a DC-AC converter, in accordance with some embodiments. Accordingly, the DC-AC converter comprises a transformer, a pulse generator, a pulse modulator, a switching element, and an analog low pass filtering stage. Further, the pulse generator is configured for generating pulses characterized by a pulse frequency. Further, the pulse modulator is configured for generating a pulse density modulated signal based on modulating the pulses using a sine wave signal of a fundamental frequency. Further, the switching element is connected in series with a primary winding of the transformer. Further, the switching element is configured to be switched between an on state and an off state based on the pulse density modulated signal. Further, the analog low pass filtering stage is configured for generating an AC voltage of the fundamental frequency based on attenuating higher frequency components of an unfiltered AC voltage at a secondary winding of the transformer.

A method and an apparatus and system for producing light using LED lighting with output within a predetermined desired color temperature range for commercial lighting uses. A preferred embodiment includes a first and second group of LEDs arranged in an alternating matrix configuration, each group of LEDs configured to produce light in a predetermined color temperature range. In a preferred embodiment, an LED light system includes a tubular LED lamp having substantially the same size and dimensions as a traditional fluorescent lamp tube and a control box for controlling power input and power gain to the first, second, or both groups of LEDs.

A power conversion device includes a power conversion circuit, a memory, a voltage detection circuit, a current detection circuit, and a control circuit. The power conversion circuit controls a switching device based on a switching pulse signal to convert direct current power into alternating current power and output the alternating current power to a power supply target. The memory stores an alternating current phase difference. The voltage detection circuit detects an alternating current voltage effective value. The current detection circuit detects an alternating current effective value. Based on the alternating current phase difference, the alternating current voltage effective value, and the alternating current effective value, the control circuit stops output of the switching pulse signal at a time when an alternating current has a value of 0.