Disclosed are a power circuit and an automated external defibrillator including the same. The power circuit may include a battery-driven power source, and a transformer comprising a primary winding and N secondary windings, wherein N is an integer greater than or equal to 2, and wherein the primary winding is electrically coupled to the power source. The power circuit may include N charging and discharging branches, wherein the N charging and discharging branches are respectively connected to the N secondary windings and are cascaded in sequence. The power circuit may include a plurality of electrode plates configured to be connected to an external load, wherein electrode plates of the plurality of electrode plates are electrically coupled to one or more output nodes of the N charging and discharging branches.

A controller of a switching converter includes an error amplifying circuit, a first comparison circuit, a valley detection circuit, a valley selection circuit and a frequency control circuit. The error amplifying circuit generates a compensation signal based on the difference between a reference signal and a feedback signal. The first comparison circuit compares the compensation signal with a modulation signal and generates a pulse frequency modulation signal. The valley detection circuit detects valleys of a resonant voltage of the switching converter and generates a valley pulse signal. The valley selection circuit generates a valley enable signal corresponding to a target valley number based on the pulse frequency modulation signal and the valley pulse signal. The frequency control circuit generates a frequency control signal to control the switching frequency of the first switch based on the valley enable signal and the valley pulse signal.

A dual-input power conversion system includes a first primary side power network comprising a first hold-up capacitor, wherein the first primary side power network has inputs configured to be coupled to a first power source, and outputs coupled to a transformer, a second primary side power network comprising a second hold-up capacitor, wherein the second primary side power network has inputs configured to be coupled to a second power source, and outputs coupled to the transformer, and a secondary side power network having inputs coupled to a secondary side of the transformer, and outputs coupled to a load, wherein the first primary side power network and the second primary side power network are configured such that a voltage across one of the first hold-up capacitor and the second hold-up capacitor is maintained by a voltage reflected from the secondary side to a corresponding primary side.

A power converter includes: a switching transistor, a transformer, a control circuit; the control circuit is configured to determine a target voltage in a process that the switching transistor is driven to conduct; the target voltage can represent a voltage change of an input terminal of the switching transistor; when the target voltage starts to drop but is higher than a reference voltage, drive a control terminal of the switching transistor with a first driving current; when the target voltage decreases to be lower than the reference voltage, drive the switching transistor with a second driving current; the second driving current is higher than the first driving current; the switching transistor is driven by the first driving current for part or all of the time before entering the Miller plateau stage, and is driven by the second driving current after starting to enter the Miller plateau stage.

A voltage regulator with dynamic voltage and frequency tracking is shown. The voltage regulator has power switches converting an input voltage into an output voltage, a control loop, a voltage comparator, and a target voltage generator. The control loop is coupled to the power switches to control the power switches to perform voltage regulation. The voltage comparator compares the output voltage to the target voltage to generate a first control signal to control the control loop. The target voltage generator generates the target voltage for the voltage comparator based on the frequency difference between the target frequency and the critical-path-related frequency, wherein the critical-path-related frequency depends on the output voltage. The power efficiency and response time are improved.

A failure detection circuit for a power switch transistor in a power switching converter is provided that compares a drive voltage for driving a gate of the power switch transistor to a plurality of thresholds. Based upon when the drive voltage crosses each threshold in the plurality of thresholds, a logic circuit determines whether a fault condition exists for the power switch transistor.

System and method via which a switching element is switched in a regulated state of a switching converter at a predetermined stable switching frequency, wherein a switch-on point of the switching element is predetermined by a switching signal generated via a sawtooth signal reaching/exceeding a switch-on threshold value such that the switch-on point of the switching element falls in a valley of an oscillating voltage prevailing at the switched-off switching element, where a prevailing period duration of the switching signal is continuously determined to detect the period duration that is compared with a predetermined reference period duration of a period duration reference unit, a control variable is generated from the comparison and a gap is changed between the sawtooth signal, which is influenced with the valley-identifying signal, and the switch-on threshold value until ascertaining, with reference to the determined prevailing period duration, the stable switching frequency has been reached.

Embodiments of this application provide charging apparatuses, charging apparatus control methods, and charging systems, and relate to the field of terminal device charging technologies. The charging apparatus includes a rectifier circuit, a transformer, a lower bridge switch, a clamp capacitor, an upper bridge switch, and a controller. The transformer includes a primary coil and at least one secondary coil. The controller is configured to control the upper bridge switch and the lower bridge switch to be alternatively turned on. The controller is further configured to obtain a sampling waveform at a location at which the controller is electrically connected to the transformer when the lower bridge switch is turned off, and, when the sampling waveform is abnormal, turn off the lower bridge switch in a first phase of a next charging cycle. The sampling waveform includes a voltage waveform of the primary coil or a voltage waveform of the secondary coil.

An AC to DC conversion device has first and second AC input terminals arranged to be coupled respectively to first and second terminals of a phase of an AC current generator, an H-bridge rectification device comprising two pairs of diodes, each pair being coupled to a respective one of the AC terminals to produce a DC output comprising a rectified back EMF waveform, and a waveform generator. The waveform generator comprises an output coupled to the DC output of the H-bridge rectification device, and is configured to input a unidirectional waveform to the DC output having the same magnitude and fundamental frequency as the rectified back EMF, phase shifted by a predetermined angle relative to the rectified back EMF waveform.

A flyback converter and forward converter is described that include an input coil, a primary switch connected in series with the input coil, and an output coil magnetically coupled to the input coil. The input coil has an input side connected to an input of the circuit and a switch side connected to the primary switch. The converter further includes an input side clamp circuit, the input side clamp circuit including an energy store and a switch arrangement controlled such that the leakage inductance energy stored, in use, in the energy store, can be discharged to the input side of the input coil.