During a light load (or no-load) operation of a totem pole power factor correction circuit (i.e., PFC), a pulse width modulation (PWM) controller can operate in a skip mode. Further, the PWM controller may disable portions of the PFC to reduce standby power consumption. In this mode, and in this disabled configuration, the output of the PFC may be peak charged over time to a voltage that could be damaging or destructive. This peak charging results from the PFC circuit's inability to fully charge/discharge EMI capacitors between half cycles of the input line voltage. The present disclosure provides circuits and methods to fully charge/discharge the EMI capacitors to prevent peak charging the output.

An OLED driving power source includes a power supply board connected to main board and OLED screen, power supply board includes standby circuit, power supply circuit, first conversion module, second conversion module and switch; after powering on, standby circuit supplies mainboard and power supply circuit, power supply circuit starts first conversion module to output first voltage and second voltage to power mainboard and output HVDC to second conversion module, switch converts first voltage to first enabling voltage to supply OLED screen according to first enabling signal from mainboard; power supply circuit starts second conversion module to convert HVDC into second enabling voltage to power and light up OLED screen, first conversion module comprises bridgeless PFC circuit and auxiliary path LLC control circuit integrated into same semiconductor chip encapsulation, and omitting specific standby circuit, circuit structure is simplified, area of power supply board is reduced, and production cost is reduced.

A method for operating a power converter and a control circuit are disclosed. The method includes, in a power converter including an input, a converter stage, a first switch connected between the input and the converter stage, a second switch connected between input nodes of the converter stage, and an output capacitor connected between output nodes of the converter stage: detecting an operating state of the power converter; and operating the power converter in a first operating mode when the power converter is in a first operating state. Operating the power converter in the first operating mode includes regulating an input current received at the input by a switched-mode operation of the first and second electronic switches.

A two-stage power converter has a Power-Factor Converter (PFC) and a Dual Active Bridge (DAB) converter connected together by a DC link voltage. The DAB converter outputs a battery voltage with a battery current. A PFC controller divides a reference power constant by the battery voltage to get a battery current reference that is multiplied by a constant and compared to the DC link voltage to adjust Pulse-Width-Modulation (PWM) control signals to the PFC. The reference power constant is compared to the battery current during Constant-Power mode to cause a DAB controller to modulate duty ratio and phase difference between primary and secondary-side PWM control signals to the DAB converter. The DAB converter duty ratio and phase difference are modulated by comparing the battery current to a battery current limit during Constant-Current mode and by comparing the battery voltage to a battery voltage limit during Constant-Voltage mode.

Power converters with power factor correction circuits and controllers thereof that are configured to generate frequency-adjustable first and second pulsed signals having respective and complementary phases separated by an adjustable deadtime. For example, a power converter may be configured to receive an alternating current (AC) input signal and output a direct current (DC) output signal. The power converter may include at least one DC/DC converter and a power factor correction circuit. The power factor correction circuit may include a first switching transistor comprising a first gate; a second switching transistor in series with the first switching transistor and comprising a second gate; and a controller configured to generate first and second pulsed signals having respective and complementary phases and separated by an adjustable deadtime and apply the generated first and second pulsed signals to the first and second gates, respectively.

Power factor correction circuits and controllers thereof that are configured to generate frequency-adjustable first and second pulsed signals having respective and complementary phases separated by an adjustable deadtime. For example, a controller for a power factor correction circuit may include a comparator, a frequency controller, and a deadtime controller. The controller may be configured to: receive an input signal comprising a measured output voltage of the power factor correction circuit; compare, via the comparator, the measured output voltage with a set point, resulting in a difference between the measured output voltage and the set point; feed the difference into the frequency controller and adjust a frequency of the first and second pulsed signals based on an output of the frequency controller; and provide the difference to the deadtime controller and adjust the deadtime of the first and second pulsed signals based on an output of the deadtime controller.

A control circuit for a plurality of metal-oxide semiconductor field-effect transistors (MOSFETs) in a bridge circuit for rectifying an alternating current (AC) input to generate a direct-current (DC) output includes first and second high side controls and first and second low side controls for providing gate voltage signals to respective MOSFETs in the bridge circuit. Dead time controls are provided for establishing dead time intervals between activation of complementary MOSFETs in the bridge circuit. The low side controls provide gate voltage signals having sloped edges and the dead time controls include Zener diodes having reverse bias thresholds for determining the duration of the dead time intervals.

A controller for an AC-DC converter including a rectifier circuit that converts AC input voltage into DC output voltage uses control logic to control the rectifier circuit according to two or more operating modes. Each operating mode determines a gain of the rectifier circuit. The controller selects an operating mode from the two or more operating modes based on at least one of an AC input voltage value and a required DC output voltage value. The AC-DC converter provides a wide range of DC output voltage with power factor correction. The controller may be used with AC-DC converter topologies such as boost converter, isolated boost converter, PWM converter, LLC resonant converter, and LCC resonant converter.

The present disclosure provides a three-phase AC/DC converter aiming for low input current harmonic. The converter includes an input stage for receiving a three-phase AC input voltage, an output stage for at least one load, and one or more switching conversion stages, each stage including a plurality of half bridge modules. The switches in each module operate with a substantially fixed 50% duty cycle and are connected in a specific pattern to couple a DC-link and a neutral node of the input voltage. The AC/DC converter further includes one or more controllers adapted to vary the switching frequency of the switches in the switching conversion stages based on at least one of load voltage, load current, input voltage, and DC-link voltage. The converter can also include one or more decoupling stages, such as, inductive components adapted to decouple the output stage from the switching conversion stages.

A conversion apparatus with a three-level switching circuit includes a DC conversion module, a three-level circuit, and a control unit. The three-level circuit includes a bridge arm assembly and a capacitor assembly. The capacitor assembly includes a first capacitor and a second capacitor connected to the first capacitor in series. The DC conversion module has a positive output end and a negative output end, and the positive output end and the negative output end are coupled to the bridge arm assembly. The control unit controls the switching of a second switch unit and a third switch unit to make the three-level circuit operate in a first state where the positive output end and the negative output end are connected to the first capacitor, and operate in a second state where the positive output end and the negative output end are connected to the second capacitor.