DC electrical machine with center-tap windings systems and methods

A method of operating a direct current electrical machine, comprising:

• receiving, using a controller communicatively coupled to the direct current electrical machine, first sensor data from first a sensor indicating a first voltage induced in a first center-tapped coil in a first commutation cell of the direct current electrical machine by rotation of a rotor;
• comparing, using the controller, the first voltage with a first voltage threshold;
• instructing, using the controller, a first switching unit in the first commutation cell to conduct current through a first half of the first center-tapped coil when the first voltage is greater than the first voltage threshold;
• instructing, using the controller, a second switching unit in the first commutation cell to conduct current through a second half of the first center-tapped coil when the first voltage is not greater than the first voltage threshold, wherein the second switching unit and the second half of the first center-tapped coil are coupled in parallel with the first switching unit and the first half;
• instructing, using the controller, a third switching unit in a second commutation cell coupled in series with the first commutation cell to conduct current through a third half of a second center-tapped coil in the second commutation cell after instructing the first switching unit to conduct current through the first half;
• and
• instructing, using the controller, a fourth switching unit in the second commutation cell to conduct current through a fourth half of the second center-tapped coil after instructing the second switching unit to conduct current through the second half.

A tangible, non-transitory, computer-readable medium configured to store instructions executable by one or more processors in a machine system, wherein the instructions comprise instructions to:

• determine, using the one or more processors, a first voltage induced in a first coil in a first commutation cell of an electrical machine by rotation of a rotor in the electrical machine, wherein the first commutation cell does not comprise an energy storage capacitor or a resonance capacitor;
• instruct, using the one or more processors, a first switching device in the first commutation cell to open to block current from flowing through the first coil and to close to enable current to flow only in one direction through the first coil to a second commutation cell electrically connected to the first commutation cell in series based at least in part on the first voltage;
• and
• instruct, using the one or more processors, a second switching device in the first commutation cell to open to block current from flowing through a second coil in the first commutation cell and to close to enable current to flow only in the one direction through the second coil to the second commutation cell based at least in part on the first voltage, wherein the first coil and the second coil are electromechanically coupled.