AC current heating of a battery is performed using a half-bridge based quasi-resonant circuit.

Duty cycles of pulse width modulation (“PWM”) pulses are determined by measurements taken with respect to an internally generated clock signal. One of these measurements calculates, in a continuous dynamic manner, a ratio of the number of cycles of the internally generated clock signal to one or more cycles of a PWM clock signal utilized as a time base for generation of the PWM pulses. This clock ratio measurement designates how many cycles of the internally generated clock signal will be used to designate a first portion of a duty cycle for each PWM pulse. Another measurement is utilized to determine a fractional portion of a cycle of the internally generated clock signal that will be used to designate a second portion of the duty cycle for each PWM pulse.

This control device is configured to control a converter comprising a piezoelectric element and several switches, and capable of delivering N output voltage(s) from of E input voltage(s), E≥1, N≥1.

The control device comprises a module for controlling, during a respective resonance cycle of the piezoelectric element, switching of the switches to alternate phases at substantially constant voltage and phases at a substantially constant charge at the terminals of the piezoelectric element, each cycle comprising first and second half-cycles, a current flowing in one direction in the piezoelectric element during first half-cycle and in an opposite direction during the second half-cycle.

The number of substantially constant voltage phases during a cycle is greater than or equal to E+N+2, and each of the half-cycles comprises at least two substantially constant voltage phases.

There is provided a high frequency AC inverter comprising a DC-DC circuit, an output power circuit and a load circuit and a controller, the load circuit comprising a load circuit detector configured to detect the electrical parameters of the load circuit. The output power circuit comprises a DC to AC driver having a variable frequency output, a HFAC driver circuit comprising a resonant network and a transformer coupled to the HFAC driver circuit and the load circuit. The controller is configured to control the output frequency of the DC to AC driver and the output of the DC to DC circuit in response to the detected electrical parameters of the load circuit.

A power supply includes an inverter configured to direct current (DC) power into alternating current (AC) power, an impedance matching circuit configured to supply the AC power to a load; and a controller configured to adjust disposition of a powering period, in which the AC power is output, and a freewheeling period, in which the AC power is not output, to adjust a power amount of the power supplied to the load through the impedance matching circuit by the inverter.

Method and apparatus include a first stage converter configured to generate a half sine wave, and a second stage converter in electrical communication with the first stage converter and configured to transform the half sine wave into a power signal. The second stage converter may further supply the power signal to an electrical grid. In one example, the second stage converter may include an isolated, unregulated, resonant direct current/alternating current (DC/AC) converter.

Methods and apparatus for active EMI cancellation in a switch mode power supply are provided herein. For example, an apparatus comprises an active EMI cancellation circuit coupled to a switch mode power supply circuit comprising an isolation transformer, wherein the active EMI cancellation circuit is positioned such that current flow through an EMI coupling capacitor substantially matches displacement current flow through a primary-to-secondary interwinding capacitance of the isolation transformer.

A system for plasma ignition and maintenance of an atmospheric pressure plasma. The system has a variable frequency alternating current (AC) power source, a transformer, a cable connected to a secondary winding of the transformer, a programmed microprocessor for control of power to the atmospheric pressure plasma. The microprocessor is configured to a) at pre-ignition, power the AC power source at an operational frequency f.sub.op higher than the resonant frequency f.sub.r, b) decrease the operational frequency f.sub.op of the AC power source until there is plasma ignition, and c) after the plasma ignition, further decrease the operational frequency f.sub.op of the AC power source to a frequency lower than the resonant frequency f.sub.r.

Embodiments relate to circuitry to provide amplitude modulated waveforms in electrosurgical devices. The circuitry can be included in an electrosurgical generator device to provide the amplitude modulated waveforms to an electrosurgical probe coupled with the electrosurgical generator device.

Method for operating an apparatus for wirelessly transferring energy in the direction of an electrical consumer by means of inductive coupling, wherein the apparatus comprises: a rectifier for generating a DC voltage from a power supply system voltage, an inverter fed from the DC voltage and configured to generate a pulse-width-modulated drive signal, and a coil driven by means of the pulse-width-modulated drive signal, by means of which coil an alternating magnetic field is generatable for the purpose of transferring the energy, wherein the method comprises the following steps: controlling an electrical actual power output by the inverter to a predefinable electrical target power, wherein a frequency and a duty cycle of the pulse-width-modulated drive signal serve as manipulated variables of the control, wherein the following steps are carried out for the purpose of adjustment to the target power: a) setting a start frequency (f_0), b) setting a start duty cycle (DC_1) in such a way that the target power is undershot, c) measuring an electrical actual power output by the inverter in the case of the start frequency (f_0) set and the start duty cycle (DC_1) set, d) choosing an adjustment target power which is less than or equal to the target power, e) calculating a duty cycle (DC_2) which computationally corresponds to the adjustment target power, f) setting the calculated duty cycle (DC_2), g) measuring an electrical actual power output by the inverter in the case of the frequency (f_0) set and the duty cycle (DC_2) set, and h) repeating steps d) to g) with increasing adjustment target power until a deviation between the target power and the actual power falls below a predefined threshold.