A bidirectional energy storage converter and an energy storage system are provided. The bidirectional energy storage converter includes at least one bridge arm. Each bridge arm includes a first switching circuit, a second switching circuit and a third switching circuit. A first end of the first switching circuit is connected to a positive electrode of a direct-current busbar and a second end is connected to a neutral point of the direct-current busbar. A first end of the second switching circuit is connected to the neutral point of the direct-current busbar, and a second end is connected to a negative electrode of the direct-current busbar. A first end of the third switching circuit is connected to a third end of the second switching circuit, a second end is connected to a third end of the first switching circuit, and a third end is connected to an alternating-current busbar.

A bidirectional energy storage converter and an energy storage system are provided. The bidirectional energy storage converter includes at least one bridge arm. Each bridge arm includes a first switching circuit, a second switching circuit and a third switching circuit. A first end of the first switching circuit is connected to a positive electrode of a direct-current busbar and a second end is connected to a neutral point of the direct-current busbar. A first end of the second switching circuit is connected to the neutral point of the direct-current busbar, and a second end is connected to a negative electrode of the direct-current busbar. A first end of the third switching circuit is connected to a third end of the second switching circuit, a second end is connected to a third end of the first switching circuit, and a third end is connected to an alternating-current busbar.

Disclosed examples include power conversion systems, methods and computer readable mediums to operate an inverter to drive a motor load through an intervening filter, by computing a speed error value according to a speed reference value and a speed feedback value, computing a torque reference value according to the speed error value, computing a motor current reference value according to the torque reference value, compensating the motor current reference value according to capacitor currents of the output filter using a transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load, and controlling the inverter according to the inverter output current reference value.

A voltage converter system includes a first DC-AC voltage converter that converts a first DC voltage signal to a first AC voltage signal. A DC link converts the first AC voltage signal to a second DC voltage signal. A second DC-AC voltage converter converts the second DC voltage signal to a second AC voltage signal. In another configuration a DC-AC voltage converter converts a DC voltage signal to a first AC voltage signal. An AC-AC voltage converter converts the first AC voltage signal to a second, lower-frequency AC voltage signal. In yet another configuration a first voltage converter portion converts a DC voltage signal to pulses of DC voltage. A second voltage converter portion converts the pulses of DC voltage to a relatively low-frequency AC voltage signal. The voltage converter system is selectably configurable as a DC-AC voltage converter or an AC-DC voltage converter.

The present invention relates to an energy conversion circuit comprising a switching stage with a positive DC voltage terminal (1), a negative DC voltage terminal (3), m1 intermediate DC voltage terminals (2) m DC bus capacitors (5); and p linked cells consisting of m+1 switches (9) and at least one capacitor (10), connecting cell 1 to the positive DC voltage terminal (1), negative DC voltage terminals (3) and intermediate DC voltage terminals (2); and a multilevel converter, the output of which is connected to the AC voltage terminal (4), with a positive voltage terminal (12) and a negative voltage terminal (14) of the multilevel converter and m1 intermediate voltage terminals of the multilevel converter (13), which are connected to the positive output terminal of the switching stage (6), to the negative output terminal of the switching stage (8), and to the m1 intermediate output terminals of the switching stage (7), respectively.

The present invention relates to an energy conversion circuit comprising a switching stage with a positive DC voltage terminal (1), a negative DC voltage terminal (3), m1 intermediate DC voltage terminals (2) m DC bus capacitors (5); and p linked cells consisting of m+1 switches (9) and at least one capacitor (10), connecting cell 1 to the positive DC voltage terminal (1), negative DC voltage terminals (3) and intermediate DC voltage terminals (2); and a multilevel converter, the output of which is connected to the AC voltage terminal (4), with a positive voltage terminal (12) and a negative voltage terminal (14) of the multilevel converter and m1 intermediate voltage terminals of the multilevel converter (13), which are connected to the positive output terminal of the switching stage (6), to the negative output terminal of the switching stage (8), and to the m1 intermediate output terminals of the switching stage (7), respectively.

A bi-directional medium voltage converter topology includes an n-pulse line-interphase-transformer, LIT; a plurality of bi-directional medium voltage, MV converters connected to the LIT on an AC side thereof and connected in parallel on a DC side thereof; a bi-directional multi-stage DC/DC converter connected to the plurality of bi-directional MV converters; and a bi-directional low voltage, LV, DC/DC converter; wherein the multi-stage DC/DC converter and the LV DC/DC converter are connected to each other galvanically insulated.

A bi-directional medium voltage converter topology includes an n-pulse line-interphase-transformer, LIT; a plurality of bi-directional medium voltage, MV converters connected to the LIT on an AC side thereof and connected in parallel on a DC side thereof; a bi-directional multi-stage DC/DC converter connected to the plurality of bi-directional MV converters; and a bi-directional low voltage, LV, DC/DC converter; wherein the multi-stage DC/DC converter and the LV DC/DC converter are connected to each other galvanically insulated.

A bi-directional medium voltage converter topology includes an n-pulse line-interphase-transformer, LIT; a plurality of bi-directional medium voltage, MV converters connected to the LIT on an AC side thereof and connected in parallel on a DC side thereof; a bi-directional multi-stage DC/DC converter connected to the plurality of bi-directional MV converters; and a bi-directional low voltage, LV, DC/DC converter; wherein the multi-stage DC/DC converter and the LV DC/DC converter are connected to each other galvanically insulated.

A bi-directional medium voltage converter topology includes an n-pulse line-interphase-transformer, LIT; a plurality of bi-directional medium voltage, MV converters connected to the LIT on an AC side thereof and connected in parallel on a DC side thereof; a bi-directional multi-stage DC/DC converter connected to the plurality of bi-directional MV converters; and a bi-directional low voltage, LV, DC/DC converter; wherein the multi-stage DC/DC converter and the LV DC/DC converter are connected to each other galvanically insulated.