Abstract:
The present invention provides a three-level ac generating circuit and the control method thereof. The three-level ac generating circuit includes a three-level boosting circuit connected to an input source and including a positive boosting portion and a negative boosting portion; and a three-level inverting circuit connected to the three-level boosting circuit and including a positive inverting portion and a negative inverting portion, wherein while the input source is a relative low voltage, the relatively low voltage is boosted via the three-level boosting circuit, inverted and output via the three-level inverting circuit; while the input source is a relatively high voltage, the relatively high voltage is inverted and output via the three-level inverting circuit and wherein the output of the three-level ac generating circuit is power grid.
Abstract:
A resonance converter and a synchronous rectification driving method thereof are provided. The resonance converter includes a switch circuit having at least two first switches, a resonance circuit having a resonance frequency, a transformer, and a full-wave rectification circuit having two second switches each of which has a drain and a source and generates a channel resistance voltage when a current flows through the drain and the source. The synchronous rectification driving method includes steps as follow. When an operating frequency of the resonance converter is less than the resonance frequency and the resonance converter is coupled to a heavy load, the channel resistance voltage is compared with a reference voltage for driving the second switches of the full-wave rectification circuit; and when the operating frequency of the resonance converter is not smaller than the resonance frequency, duplicated signals of signals used to drive the first switches are respectively used to drive the second switches of the full-wave rectification circuit.
Abstract:
Parallel inverters without any communication buses and the controlling method thereof are provided. The parallel inverters are controlled by an instant voltage. Each inverter includes an output voltage waveform controller and a load-sharing controller. The output voltage waveform controller is connected to an output terminal of the inverter to control the waveform of an output voltage of the inverter. The load-sharing controller is connected to the output voltage waveform controller to control the load-sharing of the inverter and to make each inverter have the same phase, active power and reactive power without communications.
Abstract:
A method for testing a motor having a rotor and a winding is provided. The method includes steps of (a) providing a power to rotate the rotor to a predetermined speed, (b) removing the power, (c) measuring a terminal voltage of the winding while a current within the winding is zero, (d) obtaining a back electromotive force in the winding by compensating the terminal voltage with a performance of the rotor, (e) selecting a characteristic of the back electromotive force and (f) determining a magnetization of the motor by comparing the characteristic with a predetermined parameter.
Abstract:
An improved electronic ballast for providing an electrical energy to a fluorescent lamp circuit is provided. It includes a pre-heating inductor; a first resonant circuit connected to the pre-heating inductor in parallel and coupled to the fluorescent lamp circuit for pre-heating the fluorescent lamp circuit according to a first resonant frequency; a second resonant circuit coupled to the fluorescent lamp circuit for igniting the fluorescent lamp circuit according to a second resonant frequency; and a driving circuit coupled to the second resonant circuit for continuously providing the electrical energy to the first resonant circuit and the second resonant circuit respectively according to the first resonant frequency and the second resonant frequency.
Abstract:
A converting device with PFC and dc/dc converting functions is provided. The converting device includes a power source providing a dc voltage, an inverter having an input terminal electrically connected to the power source and an output terminal, a transformer having a primary winding electrically connected to the output terminal of the inverter and a secondary winding, a rectifier/filter circuit having an input terminal electrically connected to the secondary winding of the transformer and an output terminal, and a PFC converter coupled to the output terminal of the rectifier/filter circuit and having an input terminal receiving an ac input voltage. The converting device converts the ac input voltage into an ac output voltage when the ac input voltage is normal, and converts the dc voltage to output the ac output voltage with the cooperation of the inverter, the transformer, the rectifier/filter circuit and the PFC converter when the ac input voltage is abnormal.
Abstract:
An improved electronic ballast for providing an electrical energy to a fluorescent lamp circuit is provided. It includes a pre-heating inductor; a first resonant circuit connected to the pre-heating inductor in parallel and coupled to the fluorescent lamp circuit for pre-heating the fluorescent lamp circuit according to a first resonant frequency; a second resonant circuit coupled to the fluorescent lamp circuit for igniting the fluorescent lamp circuit according to a second resonant frequency; and a driving circuit coupled to the second resonant circuit for continuously providing the electrical energy to the first resonant circuit and the second resonant circuit respectively according to the first resonant frequency and the second resonant frequency.
Abstract:
A converter includes a transformer module, a primary side circuit module, and a secondary side circuit module. The transformer module includes a magnetic core group and a winding. The winding includes a primary winding and a secondary winding, and is further installed on the magnetic core group. The primary side circuit module is coupled to the primary winding. The secondary side circuit module is coupled to the secondary winding. The primary side circuit modules or the secondary side circuit module has overlapping vertical projection area on a first plane with the winding, and the first plane is a plane in a horizontal direction of the winding.
Abstract:
A transformer capable of suppressing common mode current and a power converter thereof are provided. The transformer comprises a primary winding, a secondary winding, a magnet core and a shielding winding layer. The shielding winding layer has a first shielding winding and a second shielding winding. A voltage jump direction of the first shielding winding is constantly opposite to that of the second shielding winding. The shielding winding layer is coupled to a static terminal coupled with the primary winding or the secondary winding.
Abstract:
A DC/DC converter, a power converter and a control method thereof are disclosed, wherein the DC/DC converter includes an output circuit, a rectangular wave generator, a resonant tank, a detection unit and a control unit. The output circuit has a load. The rectangular wave generator converts an input voltage into driving pulses. The resonant tank provides a first voltage based on the driving pulses for the output circuit. The detection unit detects a signal related to a state of the load. When the state of the load is a light-load or a no-load, the control unit controls the rectangular wave generator in a hiccup mode to reduce a ratio of a work period to a stop period, or makes that number of the driving pulses within the current work period is less than the number of the driving pulses when a duty ratio is 50%.