Low voltage side precharge circuitry

A method for precharging a converter implemented by controller circuitry within a controller system of an electric system, the electric system comprising precharge circuitry comprising one or more low voltage switches to regulate precharge energy flow from an energy source to a low voltage side of a converter, the converter comprising converter circuitry, the converter circuitry including a grid connection switch and a medium voltage link capacitor coupled to a medium voltage side of the converter, the controller system comprising a controller and one or more interfaces communicating with the precharge circuitry or with the converter circuitry of the converter, the method comprising:

• obtaining a precharge circuitry attribute corresponding to the precharge circuitry;
• obtaining a converter circuitry attribute corresponding to the converter circuitry;
• regulating one or more switching statuses of the one or more low voltage switches based on the precharge circuitry attribute or on the converter circuitry attribute;
• in response to the one or more switching statuses of the one or more low voltage switches corresponding to an ON status, for each converter cell corresponding to the converter circuitry:
• obtaining a controller circuitry attribute, the controller circuitry attribute corresponding to a link voltage across the medium voltage link capacitor coupled to the medium voltage side;
• based on the controller circuitry attribute, selecting between an open loop mode and a closed loop mode of regulating the link voltage;
• and
• in response to selecting the closed loop mode:
• switching the one or more switching statuses of the one or more low voltage switches to an OFF status;
• and
• switching a switching status of the grid connection switch to an ON status to connect the converter to an electric grid.