Abstract: A method for a direct current (DC) islanding detection based on positive feedback of a bus voltage at a specific frequency, essentially including three steps: extraction of a specific frequency component of the bus voltage, injection of a disturbance component of the specific frequency, and determination of DC islanding. The extraction of the specific frequency component of the bus voltage and the injection of the disturbance component of the specific frequency constitute a positive feedback mechanism in a power management unit control loop. In a grid-connected mode of a DC grid, the positive feedback mechanism fails due to a control action of a voltage management unit on a bus, and the bus voltage remains stable. In an islanding mode of the DC grid, under an action of the positive feedback mechanism, the power management unit allows the bus voltage to generate a self-excited oscillation at the specific frequency.

Abstract: Disclosed in the present application is a driver for lighting means, preferably light emitting diodes, comprising a charge pump circuit, which is improved based on a common first-stage charge pump circuit. A fifth capacitor is added to connect a power source input end of the charge pump circuit to an LLC or LC circuit, a compensation current is provided for the power source input end using a resonant current generated by a resonant inductance in the LLC or LC circuit, an input angle of a power input current is widened and the input current is smoothed, so as to improve the problems, that a total harmonic distortion is larger and the harmonic does not satisfy the IEC standard, of a single-stage charge pump circuit where the output range is larger.

Abstract: Disclosed in the present application is a driver for lighting means, preferably light emitting diodes, comprising a charge pump circuit, which is improved based on a common first-stage charge pump circuit. A fifth capacitor is added to connect a power source input end of the charge pump circuit to an LLC or LC circuit, a compensation current is provided for the power source input end using a resonant current generated by a resonant inductance in the LLC or LC circuit, an input angle of a power input current is widened and the input current is smoothed, so as to improve the problems, that a total harmonic distortion is larger and the harmonic does not satisfy the IEC standard, of a single-stage charge pump circuit where the output range is larger.