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.

An AC to DC converter includes a plurality of rectifier circuits connected in series to an AC voltage source at an input side to collectively receive an output voltage of the AC voltage source; and a plurality of switching units respectively connected to the plurality of rectifier circuits, each of the switching units having a semiconductor switching device, a diode, and a capacitor, and performing ON/OFF switching of the semiconductor switching device provided therein to step up a voltage received from the corresponding rectifier circuit, each of the switching units supplying the stepped-up voltage to said capacitor through said diode so that a resulting DC across said capacitor can be provided, as a DC output voltage of the switching unit, to a respective load to be connected to terminals of said capacitor.

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.

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.

A control method and system are provided for regulating operation of power factor correction rectifiers based on the non-symmetric boost converter topology. Control of both the front-end stage is enabled taking sinusoidal current from the utility network and a downstream converter providing isolated DC output voltage. Also provided are a method and system for reducing volume of reactive components in boost-based rectifiers with power factor correction. Flux density through the inductor is reduced with a biasing inductor current having a much lower frequency than the switching frequency of the converter.

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 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 circuit for controlling an anode-gate thyristor includes a first transistor that couples a thyristor gate to a first terminal to receive a potential lower than a potential of a second terminal connected to the thyristor anode. A control terminal of the first transistor is driven by a control signal which is positive with respect to the potential of the first terminal.

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.