In the parallel operation of power supply units, a high line ripple current may be observed in output when the power supply units (PSUs) are supplied with different inputs. For example, a high line ripple current may be observed when PSUs were supplied with different line frequency inputs and/or when PSUs were supplied with different phase angle input lines. A low pass filter is in a control loop which is capable of filtering the line frequency to get an average current reference signal. The average current reference signal is compared with the real time output current to generate an error signal. This error signal is fed back to a voltage control loop to adjust the output in order to compensate the line ripple.

Multilevel conversion circuit having a flying capacitor and method for precharging the same are provided. The multilevel conversion circuit includes: a first bridge arm including a plurality of switches connected in series; a second bridge arm including a plurality of switches connected in series and a flying capacitor group, midpoints of the two bridge arms connected to a power supply and an inductor to form a series branch; a DC bus capacitor to which the two bridge arms are connected in parallel; a first voltage clamping module connected between a first end of the flying capacitor group and a first end of the DC bus capacitor; and a second voltage clamping module connected between a second end of the flying capacitor group and a second end of the DC bus capacitor.

A multilevel conversion circuit having a flying capacitor is provided, including: a first bridge arm; a second bridge arm including a flying capacitor, the midpoints of the second and first bridge arms connected to a series branch defined by a first current limiting circuit, a power supply and an inductor; a DC bus capacitor connected in parallel to the first and second bridge arms; a rectifier circuit having an input end coupled to the power supply and an output end connected to a first auxiliary power supply; and a controller coupled to the first auxiliary power supply and the plurality of switches of the second bridge arm to control corresponding switches of the second bridge arm, the power supply charges the flying capacitor through the corresponding switches of the first and second bridge arms and the first current limiting circuit.

Provided is a control apparatus including a sensing unit configured to output a short circuit sensing signal in response to sensing, in a turn-on period of a main switching device by a switching device for on control, of short circuit of the main switching device, a protection operation control unit configured to output an instruction signal of a short circuit protection operation at delayed timing relative to the short circuit sensing signal, and a protection unit configured to turn off the switching device for on control in response to the instruction signal, in which the protection operation control unit outputs the instruction signal in response to continuation of the short circuit sensing signal beyond a first reference time period.

The disclosure provides a power supply unit, including: a first high-frequency isolating converter including a first end connected to a first voltage, a second end and a third end; and a second high-frequency isolating converter including a first end connected to a second voltage, a second end and a third end, wherein the second end of the second high-frequency isolating converter and the second end of the first high-frequency isolating converter are connected in parallel to a first end of a first load, and the third end of the second high-frequency isolating converter and the third end of the first high-frequency isolating converter are connected in parallel to a second end of the first load. The disclosure further provides a loop power supply system having the power supply unit.

A zero-voltage switching (ZVS) buck-boost converter to reduce or even minimize switching power loss and improve EMI performance is described herein. The buck-boost converter may include an auxiliary path to generate an auxiliary current to charge and discharge respective nodes in the converter during select switching times. The converter may operate in buck-boost mode, buck mode, or boost mode. Moreover, the auxiliary path may include components, such as a pair of power switches and an inductor, arranged in a symmetrical fashion so that the converter may achieve ZVS in bidirectional operation as well.

An inductor is connected between a switching node and an output line. The first switch and the second switch are connected in series between an input line and a ground line. A third switch is connected between the switching node and the input line. A flying capacitor is connected across the third switch and the first switch. A controller IC drives the first switch to the third switch.

A power supply used to convert an input voltage into an output voltage, and the power supply includes an input detection circuit, a conversion circuit, a detection circuit, and a controller. The input detection circuit provides a power good signal or a power fail signal according to the input voltage. The conversion circuit converts the input voltage into an output voltage, and the detection circuit detects the output voltage according to the power good signal to accordingly provide an output feedback signal with a first feedback value. The controller stabilizes a voltage level of the output voltage according to the first feedback value. The detection circuit self-adjusts a feedback condition according to the power fail signal, and correspondingly adjusts the output feedback signal to a second feedback value according to the feedback condition. The controller reduces the voltage level of the output voltage according to the second feedback value.

An apparatus includes a controller. The controller monitors a magnitude of first current supplied by an output voltage of a first power converter to power a dynamic load. The controller controls a second power converter to supply second current through the dynamic load based on the monitored magnitude of first current.

Embodiments provide a method and apparatus for capacitor demand evaluation in a PDN that includes at least one power bus provided with multiple nodes. The multiple nodes are distributed at different positions of the power bus. Each of the multiple nodes is connected to multiple capacitors connected in parallel. Each of the multiple capacitors is provided with a respective one of control switches. The method includes: Multiple adjustment operations are performed. Upon accomplishment of each of the multiple adjustment operations, a respective IR drop of the power bus and a respective running speed of the load circuit are detected; for each of different nodes on the power bus, an ideal capacitance of the node is determined according to the IR drops of the power bus and running speeds of the load circuit detected through the multiple adjustment operations.