System for charging electrical storage device and method of making same

A method of assembling a control system comprising:

• coupling a first energy storage device (ESD) to a first bi-directional DC-DC converter, the first bi-directional DC-DC converter comprising:
• a first pair of power switches coupled in series;
• and
• an inductor coupled to a first node formed between the first pair of power switches;
• coupling the first ESD to a second bi-directional DC-DC converter, the second bi-directional DC-DC converter comprising:
• a second pair of power switches coupled in series;
• and
• an inductor coupled to a second node formed between the second pair of power switches;
• coupling the first and second bi-directional DC-DC converters to a DC link;
• coupling the DC link to a motor drive;
• coupling a transformer of a charge circuit to the first and second nodes;
• coupling a second ESD to the charge circuit to receive a charge voltage therefrom;
• and
• coupling a controller to the first and second bi-directional DC-DC converters and configuring the controller to interleave control of the first and second bi-directional DC-DC converters to cause a variable voltage difference between the first and second nodes during an interleave portion of a frequency period to generate the charge voltage, wherein the second ESD can be charged during operation of the motor drive.

An energy storage arrangement for an electrically powered system, the arrangement comprising:

• a first bi-directional DC-DC converter comprising:
• a first pair of power switches comprising a first power switch coupled in series with a second power switch via a first node;
• and
• a first inductor coupled to the first node;
• a first energy storage device coupled to the first inductor;
• a DC link comprising:
• a first bus coupled to the first bi-directional DC-DC converter;
• and
• a second bus coupled to the first bi-directional DC-DC converter;
• a second pair of power switches comprising:
• a third power switch coupled to the first bus;
• and
• a fourth power switch coupled to the second bus and coupled in series with the third power switch via a second node;
• a second inductor coupled to the first energy storage device;
• a transformer having a first winding comprising:
• a first terminal coupled to the first node;
• and
• a second terminal coupled to the second node;
• a second energy storage device coupled to receive a charge voltage from the transformer;
• a controller coupled to the first and second pairs of power switches and configured to cause a voltage difference between the first and second nodes during an interleave portion of a frequency period to generate the charge voltage;
• and
• an inductor switch coupled between the second inductor and the second node, wherein the controller is further configured to:
• close the inductor switch;
• and
• control the second pair of power switches to cause the second pair of power switches to boost a voltage of the first energy storage device to the DC link.

A propulsion system comprising:

• a motor drive;
• a direct current (DC) link electrically coupled to the motor drive;
• a first leg coupled to the DC link and comprising a first power switch coupled in series with a second power switch via a first node;
• a first inductor coupled to the first node, wherein the first leg and inductor form a first bi-directional DC-DC voltage converter;
• a first energy storage device (ESD) electrically coupled to the first inductor;
• a second leg coupled to the DC link and comprising a third power switch coupled in series with a fourth power switch via a second node;
• a charging circuit comprising a transformer having a first terminal coupled to the first node and having a second terminal coupled to the second node;
• a second ESD coupled to receive charging energy from the transformer;
• and
• a controller coupled to the first and second legs and configured to cause a variable voltage difference between the first and second nodes during an interleave duration of a frequency period to generate the charging energy, wherein the second ESD can be charged during operation of the motor drive.