A high voltage rectifier includes: a power divider (2) dividing power of high-frequency wave RF to be rectified; a capacitor (3) cutting-off direct current flowing between the power divider (2) and a first rectifier (10): and a capacitor (4) cutting-off direct current flowing between the power divider (2) and a second rectifier (20). The first rectifier (10) generates a direct-current voltage DC.sub.1 by rectifying a high-frequency wave RF.sub.1 output from the power divider (2), and outputs the direct-current voltage DC.sub.1 to one end of a load (7). The second rectifier (20) generates a direct-current voltage DC.sub.2 having a different polarity from that of the direct-current voltage DC.sub.1 by rectifying high-frequency wave RF.sub.2 output from the power divider (2), and outputs the direct-current voltage DC.sub.2 to the other end of the load (7).

A circuit and methods describing a complementary metal-oxide semiconductor (CMOS) rectifier for use in radio frequency (RF) energy harvesting with body biasing by the RF input to control the threshold voltage of each transistor. The CMOS rectifier includes an energy harvesting antenna, and multiple rectifier stages. The antenna receives electromagnetic radiation from the environment and generates a DC current. The oscillating input current is an RF.sup.+ positive current during a first half cycle and is an RF.sup.? negative current during a second half cycle. A first rectifier stage includes a first capacitor connected to the RF.sup.+ positive current, a second capacitor connected to the RF.sup.? negative current and a cross coupled CMOS circuit connected to the antenna.

In the present disclosure, the multi-level AC/DC conversion circuit and the multi-level DC/DC conversion circuit calculate the duty ratio of synchronous rectification switch according to the input voltage, the output voltage, the interval time of turning on the main switch, the switching cycle and the duty ratio of main switch, thereby eliminating the need for additional zero-current detecting function or zero-crossing detection circuit in conventional AC/DC conversion circuits. Accordingly, for the multi-level AC/DC conversion circuit and the multi-level DC/DC conversion circuit of the present disclosure, the cost is reduced, and the reliability is enhanced.

A multi-level conversion circuit and a control method for flying capacitor voltage thereof are provided. In the multi-level conversion circuit, each flying capacitor is connected between a common connection node of the lower switches connected therewith and a common connection node of the upper switches connected therewith. The control method includes steps of: (a) determining the main switch and synchronous rectification switch of the lower and upper switches; (b) acquiring an adjustment value corresponding to each flying capacitor; (c) adjusting a duty ratio of the main switch according to the adjustment value corresponding to the flying capacitor connected therewith; and (d) when the multi-level conversion circuit working in a CCM, increasing a phase-shift angle between the main switches by an angle to make a peak value or a valley value of an inductor current remain unchanged before and after adjusting the duty ratio.

A soft-switching Phase-Shift Full-Bridge (PSFB) converter system may include a transformer comprising a primary side and a secondary side. Phase-leading circuitry and phase-lagging circuitry may be located on the primary side of the transformer. The phase leading a phase lagging circuitry may include one or more bridge switches. The system may further include clamping circuitry coupled to the secondary side of the transformer. The clamping circuitry configurable to, when in an active clamping mode, short the secondary side of the transformer. An inductance may be included on the primary side of the transformer to collect and store energy from an input source when the secondary side of the transformer is shorted. The energy stored in the inductance may be used to enable soft-switching of the bridge switches in the phase-lagging circuitry during a dead time or a circulating time of the bridge switches in the phase-leading circuitry.

A converter circuit converts AC electric power into DC power. An inverter circuit converts the DC power into AC power. A capacitor is connected in parallel to each of the converter circuit and the inverter circuit between these circuits. The capacitor allows variation of an output voltage from the converter circuit, and absorbs variation of an output voltage from the inverter circuit due to a switching operation. An overvoltage protection circuit includes a resistor and a semiconductor element connected in series to each other. The overvoltage protection circuit is connected in parallel to the capacitor to protect the inverter circuit from an overvoltage. First and second control units respectively control the inverter circuit and the overvoltage protection circuit.

A multi-source power supply includes at least two power supply paths, both of which supply currents to a load. One of the power supply paths includes a voltage regulator configured to produce a first output voltage. The other power supply path constitutes an RF energy harvester which includes an RF antenna, a rectifier and a charge pump. The output voltage of the charge pump is clamped by the first output voltage from the voltage regulator of the first power path. Due to the clamped output voltage of the charge pump, the RF energy harvester undergoes self-impedance matching between the rectifier output and charge pump input.

A capacitor-drop power supply includes a rectifier and a switched capacitor converter coupled to the rectifier. The rectifier is configured to receive an alternating current (AC) signal at an AC voltage and convert the AC signal into a rectified direct current (DC) signal at a rectified voltage. The switched capacitor converter is configured to receive the rectified DC signal and generate a converter output signal at a converter voltage that is proportional to the rectified voltage and that is less than the AC voltage.

A device comprises a gate drive bridge coupled between a bias voltage of a power converter and ground and a transformer connected to the gate drive bridge, wherein the transformer comprises a primary winding connected to two legs of the gate drive bridge respectively and a plurality of secondary windings configured to generate gate drive signals for low side switches, high side switches and secondary switches of the power converter.

A control device for commercially available high voltage capacitor switches to close the circuit on electric utility power factor correction shunt capacitors or motor start assistance shunt capacitors precisely as each phase of the AC power source passes through zero volts.