An apparatus can include: a linear drive circuit configured to control a drive current flowing through an LED load; a control circuit configured to acquire a conduction angle signal of a silicon-controlled rectifier dimmer and control the linear drive circuit; and the control circuit being configured to control the drive current to be decreased to reduce a current ripple and to maintain the silicon-controlled rectifier dimmer in a turn-on state when the conduction angle signal is less than a predetermined value.

An apparatus can include: a linear drive circuit configured to control a drive current flowing through an LED load; a control circuit configured to acquire a conduction angle signal of a silicon-controlled rectifier dimmer and control the linear drive circuit; and the control circuit being configured to control the drive current to be decreased to reduce a current ripple and to maintain the silicon-controlled rectifier dimmer in a turn-on state when the conduction angle signal is less than a predetermined value.

A multi-port power supply apparatus and its operation method are provided. The multi-port power supply apparatus includes a voltage source circuit, a first voltage converter, a second voltage converter and a first common control circuit. The voltage source circuit provides a source voltage. The first voltage converter converts the source voltage into a first output voltage and outputs the first output voltage to a first connecting port of the multi-port power supply apparatus. The second voltage converter converts the source voltage into a second output voltage and outputs the second output voltage to a second connecting port of the multi-port power supply apparatus. The first common control circuit adjusts the source voltage according to a first voltage demand of the first connecting port and a second voltage demand of the second connecting port. Thus, a voltage conversion efficiency of the multi-port power supply apparatus is enhanced.

A boost chopper circuit is described that an alternating current (AC) power source; at least one inductor connected to said AC power source; a rectifier connected to said inductor and AC power source; at least one switch shorting our said rectifier; a series circuit connected in parallel with said switch of at least one diode and a capacitor; and a load connected in parallel with said capacitor. A control technique is employed that includes turning on and off the switch in order to keep the average current per pulse cycle proportional to the AC input voltage during the same pulse cycle.

An apparatus can include: a linear drive circuit configured to control a drive current flowing through an LED load; a control circuit configured to acquire a conduction angle signal of a silicon-controlled rectifier dimmer and control the linear drive circuit; and the control circuit being configured to control the drive current to be decreased to reduce a current ripple and to maintain the silicon-controlled rectifier dimmer in a turn-on state when the conduction angle signal is less than a predetermined value.

A rectifier cell includes a first cell branch and a second cell branch that extend in parallel between two opposite nodes receiving an a.c. signal. The first cell branch includes a first pair of transistors arranged with their current paths cascaded, with a first intermediate point in-between. The second cell branch includes a second pair of transistors arranged with their current paths cascaded, with a second intermediate point in-between. Each of the pairs of transistors includes a first transistor with a control terminal coupled to one of the two opposite nodes and a second transistor with a control terminal coupled to the other of the two opposite nodes. The bulks of the transistors receive voltages in order to vary the transistor threshold voltage by bringing the threshold voltage to a first value during forward conduction and to a second value during reverse conduction.

A boost chopper circuit is described that an alternating current (AC) power source; at least one inductor connected to said AC power source; a rectifier connected to said inductor and AC power source; at least one switch shorting our said rectifier; a series circuit connected in parallel with said switch of at least one diode and a capacitor; and a load connected in parallel with said capacitor. A control technique is employed that includes turning on and off the switch in order to keep the average current per pulse cycle proportional to the AC input voltage during the same pulse cycle.

A power conversion device comprising: a plurality of first power semiconductor modules incorporating a series circuit of a first semiconductor device and a second semiconductor device, the series circuit connected in parallel to a series circuit of a first capacitor and a second capacitor which are connected in series to a direct current power supply; a plurality of second power semiconductor modules incorporating a bi-directional semiconductor device connected between a connection point between the first capacitor and the second capacitor and a connection point between the first semiconductor device and the second semiconductor device; and a laminated bus bar connecting main circuit terminals of the plurality of first power semiconductor modules and the plurality of second power semiconductor modules to each other. The laminated bus bar includes a pair of output bas bars disposed at a front side and a back side, respectively so as to facing each other.

A power supply includes multiple power modules and a control circuit. Input terminals of the power modules are connected in star connection such that each power module receives a phase input voltage. Output terminals of the power modules are connected in parallel. Each power modules includes a first and a second converter. The first converter converts the phase input voltage into an intermediate bus voltage. The second converter outputs a DC supply voltage according to the intermediate bus voltage. The control circuit is coupled to the power modules and configured to output first and second driving signals to control the first and second converters in the power modules. A bus voltage average value is calculated by the control circuit according to the intermediate bus voltages of the power modules, and the first and the second driving signals for the power modules are generated according to the bus voltage average value.

A grid-tie inverter (the inverter) may include a power converter that receives a direct current (DC) output voltage from a DC input power source, and generates an alternating current (AC) output voltage for transmission to a utility power grid. The inverter may also include a system controller that regulates the AC output voltage to efficiently transfer power to the utility power grid while a system AC load may be terminated across the output of the inverter. The inverter may also provide active power factor correction between the utility grid voltage and current. Furthermore, the inverter may also offer harmonic cancellation, which minimizes or eliminates the harmonic content out of the utility power grid voltage and current.