A feed unit includes: a power transmission section configured to perform power transmission with use of a magnetic field or an electronic field; a power limiting section provided on a power supply line from an external power source to the power transmission section; and a control section provided on a side closer to the external power source than the power limiting section, and including a power transmission control section, the power transmission control section being configured to control the power transmission.

A power supply apparatus includes a controller that performs the following action. The controller determines a target direct-current electric amount value in accordance with an external input. Then, the controller performs feedback control in such a manner that an amount of direct-current electric power input to an inverter reaches the target direct-current electric amount value.

A frequency generator for generating a working frequency for a transmission signal of a rail contact of an axle counter includes a series resonant circuit having a transmitter coil unit of the rail contact and a capacitor. The frequency generator has an inverter, the output of which is connected to the capacitor. The inverter is configured to generate an oscillating voltage and to feed the generated oscillating voltage to the transmitter coil unit of the rail contact via the capacitor. A current transformer synchronizes the output voltage of the inverter to the current in the series resonant circuit. A start-up circuit electrically connected to the inverter is configured to trigger the inverter and to be electrically connected to an input power supply. The frequency generator is a robust and effective circuit for generation of magnetic fields where manufacturing effort and expensive components can be reduced.

An apparatus for wireless power transfer may be configured to receive power wirelessly and to output power to a load. The apparatus may include a wireless power transfer pad configured to receive power wirelessly. The apparatus may include a secondary circuit having a rectification section arranged to receive alternating current from the wireless power transfer pad and output rectified current to the load via a positive bus. The rectification section may include a first rectification device connected to the positive bus. The rectification section may include a capacitor connected between the first rectification device and a negative bus connected to the rectification section and arranged for connection to the load. Other examples may be described and claimed.

[OBJECT] To provide a radio-frequency power source capable of outputting radio-frequency power having a desired waveform changing at high speed.

[SOLUTION] A radio-frequency power source 1 includes two DC-RF converting circuits 4A, 4B and an RF combining circuit 5 for combining the outputs from both DC-RF converting circuits 4A, 4B. The DC-RF converting circuits 4A, 4B amplify radio-frequency voltages v.sub.a, v.sub.b inputted from a radio-frequency signal generating circuit 8, and output radio-frequency voltages v.sub.PA, v.sub.PB. The RF combining circuit 5 outputs radio-frequency voltage v.sub.PX at a ratio corresponding to the phase difference θ between the radio-frequency voltages v.sub.PA and v.sub.PB. A controlling circuit 9 switches the phase difference θ between θ1 and θ2. As a result, the power P.sub.X outputted from the RF combining circuit 5 becomes pulsed radio-frequency power having a high level period and a low level period. Since the switching of the phase difference θ can be performed at high speed, it is possible to output pulsed radio-frequency power with a high switching frequency between the first level and the second level.

There is provided a power supply device that supplies an output current to an electric processing device which performs electric processing on workpieces. The device includes: a first power supply; a magnetic energy recovery switch that receives a current supplied from the first power supply, and converts the received current into the output current; and a control unit that controls the magnetic energy recovery switch such that an electric current frequency of the output current includes a first electric current frequency and a second electric current frequency which are different from each other within a one-time electric processing time using the electric processing device.

According to some embodiments, an electronic drive circuit is disclosed. The electronic drive circuit includes an energy storage device and a first bridge circuit coupled to the energy storage device. The first bridge circuit includes at least one leg having two switches. The electronic drive circuit also includes a transformer. The transformer includes a first winding coupled to the first bridge circuit and a second winding coupled to the energy storage device through a center tap. The electronic drive circuit further includes a second bridge circuit coupled to the second winding of the transformer. The second bridge circuit includes a pair of switches operable to conduct in both directions and block voltage in both directions. The electronic drive circuit additionally includes a DC bus coupled to the second bridge circuit and a controller, which is configured to buck or boost a DC voltage from the energy storage device to supply to the DC bus as well as buck or boost a DC voltage from the DC bus to supply to the energy storage device.

A system to induce electrical muscle relaxation for airway management. The illustrative system includes a power control system targeted to relax muscles associated with an airway channel, and more particularly, to assist in human intubation by placement of an endotracheal tube within the trachea of a patient, mask ventilation, and/or resolution of laryngospasm. The relaxation of the muscles is achieved through external stimulation of nerves through the skin by an output electrical current pattern applied by the power control system. The illustrative system is configured to independently regulate an output current frequency and an output current amplitude of the output electrical current pattern.

A time-multiplexing resonant drive scheme is described that reuses an inductor circuit for multiple functional purposes in a Mixed Reality (MR) device. A driver circuit and a multiplexer circuit are dynamically configured by a controller circuit for three operating modes. In the first mode, energy is coupled from a battery to the inductor circuit in a forward direction to charge the inductor circuit and generate a positive power supply voltage. In the second mode, energy is coupled from to the inductor circuit in a reverse direction to charge the inductor circuit and generate a negative power supply voltage. In the third mode, the inductor is operated with an antenna as part of a resonance drive circuit, where facial movements of the user can be detected based on the response. Reduced component count and reduced cost requirements are achieved by the described scheme.

A signal analysis circuit for a supplying-end module includes a first voltage divider circuit, for attenuating a coil signal of a supplying-end coil; a first amplifier circuit, for obtaining parts of the attenuated coil signal higher than a reference voltage to output a half-wave signal; a first envelope detector, for performing envelope extraction on the half-wave signal to obtain a DC signal; a second voltage divider circuit, for attenuating the half-wave signal; a second amplifier circuit, for obtaining parts of the attenuated half-wave signal higher than the DC signal to output an amplified half-wave signal; a second envelope detector, for performing envelope extraction on the amplified half-wave signal to generate an envelope signal; a coupling capacitor, for filtering out the DC component of the envelope signal; a third voltage divider circuit, for combining the AC component of the envelope signal with a DC voltage to retrieve a trigger signal.