Abstract: The invention discloses an inverter and a soft-start method for the same. The inverter is electrically connected between a DC power supply and a grid and includes a main power circuit electrically coupled to the grid through a relay, a filter, the relay, and a controller electrically connected with the main power circuit and the relay, respectively. The soft-start method includes: sampling a grid voltage of the grid; calculating an output voltage of the controller, and calculating a virtual current based on the output voltage of the controller, the grid voltage and a virtual impedance; and performing current closed-loop control by taking the virtual current as a feedback signal and sending a relay control signal to turn on the relay when a steady state is reached. The invention enables the soft start of the inverter without increasing any hardware circuit, such as a starting resistor, or the like.

Abstract: A method for identifying type of a grid automatically and an inverter device thereof are provided. The inverter device comprises a power line L1, a power line L2, a neutral line N and a ground line electrically connectable to a first power line, a second power line, a neutral line and a ground line of the grid, respectively. The method comprises: sampling at least two of voltages between L1 and L2, between L1 to N and between L2 to N when the two neutral lines are connected, and identifying the type of the grid based on the sampling result; and sampling the voltage between L1 and L2 when the two neutral lines are not connected, sampling at least one of a voltage between L1 and GND and between L2 and GND with cooperation of a grid-connected switching unit, and identifying the type of the grid based on the sampling results.

Abstract: The invention discloses an inverter and a soft-start method for the same. The inverter is electrically connected between a DC power supply and a grid and includes a main power circuit electrically coupled to the grid through a relay, a filter, the relay, and a controller electrically connected with the main power circuit and the relay, respectively. The soft-start method includes: sampling a grid voltage of the grid; calculating an output voltage of the controller, and calculating a virtual current based on the output voltage of the controller, the grid voltage and a virtual impedance; and performing current closed-loop control by taking the virtual current as a feedback signal and sending a relay control signal to turn on the relay when a steady state is reached. The invention enables the soft start of the inverter without increasing any hardware circuit, such as a starting resistor, or the like.

Abstract: A hysteresis control method for inverter and an inverter based on hysteresis control are disclosed. The inverter is electrically connected to a power grid, and the method includes: Step S1, sampling a grid voltage Vg(z) and an output current Ig(z) of the inverter; Step S2, calculating a present period hysteresis bandwidth H(z) based on the grid voltage Vg(z) sampled in step S1; Step S3, predicting a next period hysteresis bandwidth H(z+1); Step S4, correcting the present period hysteresis bandwidth H(z) based on the next period hysteresis bandwidth H(z+1) obtained in step S3, to obtain a final hysteresis bandwidth Hout(z); and Step S5, controlling an output driving signal according to the output current Ig(z) of the inverter and the final hysteresis bandwidth Hout(z) to control the operation of the inverter.

Abstract: A method for identifying type of a grid automatically and an inverter device thereof are provided. The inverter device comprises a power line L1, a power line L2, a neutral line N and a ground line electrically connectable to a first power line, a second power line, a neutral line and a ground line of the grid, respectively. The method comprises: sampling at least two of voltages between L1 and L2, between L1 to N and between L2 to N when the two neutral lines are connected, and identifying the type of the grid based on the sampling result; and sampling the voltage between L1 and L2 when the two neutral lines are not connected, sampling at least one of a voltage between L1 and GND and between L2 and GND with cooperation of a grid-connected switching unit, and identifying the type of the grid based on the sampling results.

Abstract: A hysteresis control method for inverter and an inverter based on hysteresis control are disclosed. The inverter is electrically connected to a power grid, and the method includes: Step S1, sampling a grid voltage Vg(z) and an output current Ig(z) of the inverter; Step S2, calculating a present period hysteresis bandwidth H(z) based on the grid voltage Vg(z) sampled in step S1; Step S3, predicting a next period hysteresis bandwidth H(z+1); Step S4, correcting the present period hysteresis bandwidth H(z) based on the next period hysteresis bandwidth H(z+1) obtained in step S3, to obtain a final hysteresis bandwidth Hout(z); and Step S5, controlling an output driving signal according to the output current Ig(z) of the inverter and the final hysteresis bandwidth Hout(z) to control the operation of the inverter.