Inverters, methods for shutting down inverters and photovoltaic systems.

Claims

OCR07AP1. An inverter comprising an inverter circuit, switching module, and controller, where the input terminals of the inverter circuit are configured to connect to a DC source, the output terminals of each phase of the inverter circuit are connected to the corresponding switching module among the switching modules, and the output terminals of the switching modules are configured to connect to the power grid. The controller is configured to perform pulse blocking on the inverter circuit in response to a short circuit of the negative electrode of the DC source to ground. This pulse blocking involves disabling the drive pulses for each switching transistor in the inverter circuit, specifying the electrical parameters of the first switching module to reach a preset electrical parameter at a current time point, and determining whether the current of the first switching module tends to decrease after the inverter circuit experiences pulse blocking.Where the preset electrical parameters correspond to the safe current of switching module one and switch module one and switching module two, with the current being monitored as zero, are switched off in response to the first electrical parameter of switching module one reaching the preset electrical parameters, or switch module one and switching module two having zero current, within a time period one starting from the point in time when the actual electrical parameters of switching module one reach the preset electrical parameters, where switching module one and switching module two are both considered as switching modules 2. Inverter according to claim 1.Where, for determining whether the first electrical parameter of the first switching module reaches the preset electrical parameter, the controller is configured to indicate that the first electrical parameter of the first switching module reaches the preset electrical parameter if the first electrical parameter is current and the first electrical parameter of the first switching module is less than or equal to the first preset current, and to indicate that the first electrical parameter of the first switching module reaches the preset electrical parameter if the first electrical parameter is voltage and the first electrical parameter of the first switching module is greater than or equal to the first preset voltage.

3. Inverter according to claim 2,Where, after determining whether the first electrical parameter of the first switching module has reached the preset electrical parameter at the current point in time, the controller is further configured to continuously monitor the current of the first switching module if the first electrical parameter is current and the current of the first switching module is greater than the first preset current, until it is monitored that the current of the first switching module drops to less than or equal to the first preset current and indicates that the first electrical parameter of the first switching module has reached the preset electrical parameter, or to continuously monitor the voltage of the first switching module if the first electrical parameter is voltage and the voltage of the first switching module is less than the first preset voltage, until it is monitored that the voltage of the first switching module increases to greater than or equal to the first preset voltage and indicates that the first electrical parameter of the first switching module has reached the preset electrical parameter.

4. Inverter according to claim 3,Where, after the first and second switching modules are closed, the controller is simultaneously configured to close the open switching modules among the switching modules connected to the inverter circuit when it monitors that the current of the first switching module tends to decrease and the first electrical parameter of the switching module reaches the preset electrical parameter.

5. Inverter according to claim 1, where the actual electrical parameter reaching the preset electrical parameter is the actual current less than or equal to the preset electrical parameter.

6. Inverter according to claim 3, where the first time length is the time length from the point in time when the current of the first switching module drops to zero to the point in time closest to when the voltage of the first switching module is zero, where the preset electrical parameter is zero, the first period is the sum of the first time length and one-quarter of the phase power period corresponding to the first switching module, and the preset electrical parameter is the current corresponding to the first time point.The first time point is a periodic time point specified by subtracting the first delay period from the time point when the current in the periodic current curve corresponding to the first switching module drops to zero. The first delay period comprises the time period from the time point when the off signal is sent to the first switching module to the time point when the first switching module is actually switched off, and the first period is the sum of the length of the first time period and one-quarter of the phase power phase period corresponding to the first switching module or the preset electrical parameter as the current corresponding to the second time point. The second time point is a periodic time point specified by subtracting the second delay period from the time point when the current in the periodic current curve corresponding to the first switching module drops to zero.The second delay time comprises the time from the point in time when the shut-off signal is sent to the first switching module to the point in time when the first switching module is actually shut off, and the power resistance time from the point in time corresponding to the maximum impulse current that the first switching module can withstand to the point in time when the current in the drop portion of the periodic current curve drops to zero, and the first time is the sum of the first time length, one-quarter of the phase power period corresponding to the first switching module, and twice the power resistance time.

7. Inverter according to claim 1, where the actual electrical parameter reaching the preset electrical parameter is the actual voltage greater than or equal to the preset electrical parameter.

8. Inverter according to claim 7, where the first time length is the time length from the point in time when the current of the first switching module drops to zero to the point in time closest to when the voltage of the first switching module is zero.Where the preset electrical parameter is the voltage corresponding to the time point when the current of the first switching module drops to zero, and the first period is the sum of the length of the first time and a quarter of the phase power phase corresponding to the first switching module; the preset electrical parameter is the voltage corresponding to the time point specified by subtracting the first delay period from the time point when the current of the first switching module drops to zero; the first delay period comprises the period from the time point when the closing signal is sent to the first switching module to the time point when the first switching module is actually closed, and the first period is the sum of the length of the first time and a quarter of the phase power phase corresponding to the first switching module; or the preset electrical parameter is the voltage corresponding to the time point specified by subtracting the second delay period from the time point when the current of the first switching module drops to zero.The second delay time comprises the time from the time point when the shut-off signal is sent to the first switching module to the time point when the first switching module is actually shut off, and the power resistance time from the time point corresponding to the maximum impulse current that the first switching module can withstand to the time point when the current in the drop portion of the periodic current curve drops to zero, and the first time is the sum of the length of the first time, one-quarter of the phase power period corresponding to the first switching module, and twice the power resistance time.

9. Inverter according to claim 6 or 8, where the length of the first time is calculated by the following equation (equation), where U represents the rated voltage of the phase power corresponding to the first switching module, V represents the voltage of the phase power corresponding to the first switching module, and f represents the frequency of the phase power corresponding to the first switching module.

10. Inverter according to claim 9,Where, after closing the first and second switching modules with zero current, the controller is simultaneously configured to further close the open switching modules among the switching modules connected to the inverter circuit when it is detected that the current of the switching module tends to decrease and the actual electrical parameters of the switching modules reach the preset electrical parameters.

11. Inverter according to claim 1, where, for the indication that the current of the first switching module tends to decrease, the controller is further configured to continuously obtain a certain amount of current of the first switching module and indicates that the current of the first switching module tends to decrease in response to a certain amount of current of the first switching module that tends to decrease, or indicates that the current of the first switching module tends to decrease when it is observed that the periodic voltage curve of the phase power corresponding to the first switching module tends to increase.

12. Method for closing the inverter, where the inverter consists of the inverter circuit and switching modules,The lead end of the inverter circuit is configured to connect to a DC source, the lead end of each phase of the inverter circuit is connected to the corresponding switching module among the switching modules, and the lead end of the switching module is configured to connect to the power grid. The assembly method involves the operation of pulse blocking on the inverter circuit in response to a short circuit of the negative electrode of the DC source to ground, where the pulse blocking is integrated with the shutdown of the drive pulse for each switching transistor in the inverter circuit and the determination of the first electrical parameter of the first switching module to the preset electrical parameter at the current time point, when it is determined whether the current of the first switching module tends to decrease after the inverter circuit experiences pulse blocking.Where the preset electrical parameters correspond to the safety current of the first switching module, and the shutdown of the first and second switching modules with the monitored current is zero, simultaneously responding to the first electrical parameter of the first switching module reaching the preset electrical parameters, or the shutdown of the first and second switching modules with the current being zero within a time period starting from the point in time when the actual electrical parameters of the first switching module reach the preset electrical parameters, where the first and second switching modules are both considered as switching modules.

13. A photovoltaic system comprising a photovoltaic cable and an inverter, where the photovoltaic cable is connected to the inlet end of the inverter and configured to supply direct current (DC) power to the inverter, and the outlet end of the inverter is configured to connect to the power grid.Converts DC power to alternating current (AC) power and transmits the AC power to the power grid and is an inverter, or at least one of the inverters under claims 1 through 11, or an inverter where the method under claim 12 is used;

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