A device for power factor correction can include a converter housing having an inner surface; a first converter substrate mounted on the inner surface of the converter housing; a second converter substrate mounted on another surface of first converter housing opposite to the inner surface; and a housing cover covering the first converter substrate and coupled to an upper surface of the converter housing, in which the second converter substrate includes a first surface having a first region including a source pad, and a second region including a drain pad spaced apart from the source pad, the source pad including a source pad extension portion extending into the second region; and a second surface including a heat dissipation pad for communicating heat from the source and drain pads to an outside of the device, in which the first region of the second converter substrate overlaps with the another surface of first converter housing, and the second region of the second converter substrate faces the housing cover without overlapping with the first converter substrate.

A power tool is configured to receive power from a power supply. The power tool may include a rectifier that may output a rectified signal to a DC power bus. A switching arrangement may operate to deliver electric power from the DC power bus to an electric motor. A switch path may be electrically coupled in parallel with the rectifier on the DC power bus. The switch path includes an auxiliary capacitor in series with a switch and a state of the switch controls a discharging path for the auxiliary capacitor. A switch control circuit may be configured to detect voltage associated with at least one of the AC power supply or the DC power bus and to control state of the switch in accordance with magnitude of the detected voltage.

The present patent application relates to a method and equipment for eliminating harmonics based on two complementary techniques, namely the elimination of harmonics by selective harmonic elimination pulse-width modulation in conjunction with the multiple-wiring transformer. The association of these two resources is capable of reducing the harmonic distortion of currents to extremely low values, providing a truly unitary power factor. The technology is suitable for low and medium intensity alternating current—direct current and direct current—alternating current converters, which make interface with the electricity network and should have low harmonic distortion of the current because of the high power value involved, and also because of fragility of the electricity network (low power of short circuit at the coupling point).

The present patent application relates to a method and equipment for eliminating harmonics based on two complementary techniques, namely the elimination of harmonics by selective harmonic elimination pulse-width modulation in conjunction with the multiple-wiring transformer. The association of these two resources is capable of reducing the harmonic distortion of currents to extremely low values, providing a truly unitary power factor. The technology is suitable for low and medium intensity alternating current—direct current and direct current—alternating current converters, which make interface with the electricity network and should have low harmonic distortion of the current because of the high power value involved, and also because of fragility of the electricity network (low power of short circuit at the coupling point).

A method of controlling reactive power in a power generation system that includes a grid and a cross compound turbine generator system having a first turbine arranged to drive a first generator and a second turbine arranged to drive a second generator includes replacing the first turbine with a motor, the motor coupled to the first generator and operable to drive the first generator. The method also includes decoupling the second turbine and the second generator to allow the second generator to rotate separate from the second turbine, connecting an electrical output of the first generator to the second generator, and powering the motor to drive the first generator and to synchronize the first generator to the grid. The method further includes providing electrical power to the second generator from the first generator to power the second generator and synchronize the second generator to the grid and varying an excitation voltage for one of the first generator and the second generator to vary the reactive power output of the first generator and the second generator.

A method of controlling reactive power in a power generation system that includes a grid and a cross compound turbine generator system having a first turbine arranged to drive a first generator and a second turbine arranged to drive a second generator includes replacing the first turbine with a motor, the motor coupled to the first generator and operable to drive the first generator. The method also includes decoupling the second turbine and the second generator to allow the second generator to rotate separate from the second turbine, connecting an electrical output of the first generator to the second generator, and powering the motor to drive the first generator and to synchronize the first generator to the grid. The method further includes providing electrical power to the second generator from the first generator to power the second generator and synchronize the second generator to the grid and varying an excitation voltage for one of the first generator and the second generator to vary the reactive power output of the first generator and the second generator.

A protective redundancy circuit is provided for a power tool having an electric motor. The protective redundant subsystem is comprised of: a motor switch coupled in series with the motor; a motor control module that controls the switching operation of the motor switch; and a protective control module that monitors switching operation of the motor switch and disables the power tool when the switching operation of the motor switch fails. In the context of an AC powered tool, the switching operation of the motor switch is correlated to and synchronized to the waveform of the AC input signal. During each cycle or half cycle, the motor control module introduces a delay period before closing the motor switch and the protective control module determines the operational status of the motor switch by measuring the voltage across the motor switch during the delay period.

A protective redundancy circuit is provided for a power tool having an electric motor. The protective redundant subsystem is comprised of: a motor switch coupled in series with the motor; a motor control module that controls the switching operation of the motor switch; and a protective control module that monitors switching operation of the motor switch and disables the power tool when the switching operation of the motor switch fails. In the context of an AC powered tool, the switching operation of the motor switch is correlated to and synchronized to the waveform of the AC input signal. During each cycle or half cycle, the motor control module introduces a delay period before closing the motor switch and the protective control module determines the operational status of the motor switch by measuring the voltage across the motor switch during the delay period.

An inverter control apparatus and a control method thereof are provided. The inverter control apparatus and a control method thereof stably operate a three-phase motor using a capacitor having a small capacitance for a DC link. The inverter control apparatus includes a current sensor to sense an output current of the inverter, a voltage sensor to sense a DC-link voltage of the inverter, and a controller to generate an average of a periodically varying rotor based q-axis current boundary value based on the output current and the DC-link voltage to generate a current reference on the basis of the average of the rotor based q-axis current boundary value, and to drive a three-phase motor based on the current reference. Stabilized variable speed control of a motor by using a small-capacitance capacitor for a DC link of an inverter is performed and reliability of an inverter circuit improved.

An inverter control apparatus and a control method thereof are provided. The inverter control apparatus and a control method thereof stably operate a three-phase motor using a capacitor having a small capacitance for a DC link. The inverter control apparatus includes a current sensor to sense an output current of the inverter, a voltage sensor to sense a DC-link voltage of the inverter, and a controller to generate an average of a periodically varying rotor based q-axis current boundary value based on the output current and the DC-link voltage to generate a current reference on the basis of the average of the rotor based q-axis current boundary value, and to drive a three-phase motor based on the current reference. Stabilized variable speed control of a motor by using a small-capacitance capacitor for a DC link of an inverter is performed and reliability of an inverter circuit improved.