An electrical conversion system includes: an inductor electrically connected to an alternating current (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; a plurality of circuit branches connected in parallel, wherein each circuit branch is connected to the MVDC bus via a corresponding converter; and a filtering network disposed between the AC power grid and the MVDC bus and is grounded through at least one capacitor.

A multi-level direct current converter includes a direct current conversion unit, a switching unit, a voltage management unit, and a controller. The direct current conversion unit includes a flying capacitor, a first power transistor, and a second power transistor. A first end of the first power transistor is connected to a voltage input end of the multi-level direct current converter, a second end of the first power transistor is connected to a first end of the second power transistor by using the flying capacitor, and a second end of the second power transistor is connected to a reference ground.

In a power supply system, a control device is configured to select one or more target batteries that are to perform requested energy management from a plurality of batteries included in an alternating-current battery string and a direct-current battery string, and perform the requested energy management using the one or more target batteries with the batteries other than the one or more target batteries being disconnected from a circuit.

A power supply system that outputs AC power to an object to which power is to be supplied includes: a first power supply circuit including a DC battery string and an inverter and configured to output first AC power; a second power supply circuit including an AC battery string and configured to output second AC power; and a control device. In the first mode, power is transferred between the object and the second power supply circuit. In the second mode, power is transferred between the object and each of the first and second power supply circuits. The control device starts supplying the second AC power to the object in the first mode, and when a power supply current becomes larger than a first threshold, supply the first and second AC power to the object in the second mode.

A power supply system that outputs AC power to an object to which power is to be supplied includes: a first power supply circuit including a DC battery string and an inverter and configured to output first AC power; a second power supply circuit including an AC battery string and configured to output second AC power; and a control device. In the first mode, power is transferred between the object and the second power supply circuit. In the second mode, power is transferred between the object and each of the first and second power supply circuits. The control device starts supplying the second AC power to the object in the first mode, and when a power supply current becomes larger than a first threshold, supply the first and second AC power to the object in the second mode.

The application provides a dispersed carrier phase-shifting method and system. The method includes connecting at least two power modules to form a modular system; each power module including a control module for sampling at least twice a common state variate, signs of slopes of the common state variate at a first and second sampling time are opposite, and a reference time of the first sampling time for each control module is the same; and regulating a carrier frequency of the power module according to a relative size between a sampled values at the first and second sampling time. According to embodiments herein, carrier phase-shifting of modular system may be implemented without communication between respective modules. Under closed-loop control, optimal carrier phase-shifting can be automatically achieved under various duty ratios, thereby having good stability.

An electrosurgical generator for an electrosurgical instrument includes a DC voltage supply and a high-voltage inverter that generates a high-frequency AC voltage having a variable voltage and frequency that is output at an output for the connection of the electrosurgical instrument. The inverter is configured as a multilevel inverter and includes a plurality of inverter cells connected in a cascaded manner that are driven by a control device. Thanks to the cascading, switching losses incurred in the power semiconductors are reduced, both in terms of value (through the divided and thus lower voltage) and in terms of frequency (through the reduced switching frequency).

An electrosurgical generator for an electrosurgical instrument includes a DC voltage supply and a high-voltage inverter that generates a high-frequency AC voltage having a variable voltage and frequency that is output at an output for the connection of the electrosurgical instrument. The inverter is configured as a multilevel inverter and includes a plurality of inverter cells connected in a cascaded manner that are driven by a control device. Thanks to the cascading, switching losses incurred in the power semiconductors are reduced, both in terms of value (through the divided and thus lower voltage) and in terms of frequency (through the reduced switching frequency).

An electrosurgical generator for an electrosurgical instrument includes DC voltage supply and high-voltage inverter that generates high-frequency AC voltage having variable voltage and frequency. Inverter is multilevel inverter controlled by reference signal and having at least two groups of series-connected inverter cells, wherein each group is supplied with different DC voltage and wherein the voltages output by the two groups are summed to be output at output. Group supplied with higher voltage enables fast and large voltage changes with its inverter cells, while inverter cells of other group supplied with lower voltage allow fine setting with high change speed. Dynamic range is improved both from temporal viewpoint and in terms of increased voltage span. The number of HVC cells to be switched may furthermore be varied by way of modulator, wherein further number of LVC cells are switched in an opposing manner for compensation purposes. Switching losses may be reduced.

An electrosurgical generator for an electrosurgical instrument includes DC voltage supply and high-voltage inverter that generates high-frequency AC voltage having variable voltage and frequency. Inverter is multilevel inverter controlled by reference signal and having at least two groups of series-connected inverter cells, wherein each group is supplied with different DC voltage and wherein the voltages output by the two groups are summed to be output at output. Group supplied with higher voltage enables fast and large voltage changes with its inverter cells, while inverter cells of other group supplied with lower voltage allow fine setting with high change speed. Dynamic range is improved both from temporal viewpoint and in terms of increased voltage span. The number of HVC cells to be switched may furthermore be varied by way of modulator, wherein further number of LVC cells are switched in an opposing manner for compensation purposes. Switching losses may be reduced.