Conversion system and conversion device

A conversion device, connected between an alternating current (AC) power grid and a circuit branch, the conversion device comprising:

• an inductor electrically connected to the AC power grid;
• a medium voltage direct current (MVDC) bus;
• a non-isolated AC/DC converter, provided with a first terminal electrically connected to the inductor and a second terminal electrically connected to the MVDC bus, wherein the non-isolated AC/DC converter is configured to output a bus voltage based on an input voltage from the AC power grid;
• at least one isolated DC/DC converter, provided with a first terminal electrically connected to the MVDC bus and a second terminal electrically connected to the circuit branch, wherein the isolated DC/DC converter is configured to convert the bus voltage into an output voltage to the circuit branch;
• and
• a filtering network, provided with a first terminal, a second terminal and a third terminal, wherein a first resistance-capacitance circuit is disposed between the first terminal and the third terminal of the filtering network, a second resistance-capacitance circuit is disposed between the second terminal and the third terminal of the filtering network, the first terminal of the filtering network is electrically connected to the AC power grid, the second terminal of the filtering network is electrically connected to the MVDC bus, and the third terminal of the filtering network is grounded through at least one first capacitor.

A conversion device, connected between an alternating current (AC) power grid and a circuit branch, the conversion device comprising:

• an inductor electrically connected to the AC power grid;
• a medium voltage direct current (MVDC) bus;
• a non-isolated AC/DC converter, provided with a first terminal electrically connected to the inductor and a second terminal electrically connected to the MVDC bus, wherein the non-isolated AC/DC converter is configured to output a bus voltage based on an input voltage from the AC power grid;
• at least one non-isolated DC/DC converter, provided with a first terminal electrically connected to the MVDC bus and a second terminal electrically connected to the circuit branch, wherein the non-isolated DC/DC converter is configured to convert the bus voltage into an output voltage to provide energy to the circuit branch;
• and
• a filtering network, provided with a first terminal, a second terminal and a third terminal, wherein a first resistance-capacitance circuit is disposed between the first terminal and the third terminal of the filtering network, a second resistance-capacitance circuit is disposed between the second terminal and the third terminal of the filtering network, the first terminal of the filtering network is electrically connected to the AC power grid, the second terminal of the filtering network is electrically connected to the MVDC bus or the second terminal of the non-isolated DC/DC converter, and the third terminal of the filtering network is grounded through a first capacitor.