Patent ID: 8878473

Claim:
An apparatus for controlling current in a winding of an electric motor, the apparatus comprising: a current switching structure including first and second nodes adapted for coupling the winding in series therebetween, a pair of power supply nodes configured to provide power supply current to an electric motor winding being driven by said current switching structure, and a current blocking device coupled between one of said first and second nodes and one of said power supply nodes, the current blocking device configured to ensure that freewheeling inductive current at the first and second nodes is not clamped to one of said power supply nodes; a controller coupled to said current switching structure and configured to control said current switching structure when the winding is coupled between said first and second nodes, said controller configured for controlling said current switching structure to assume a first configuration that permits power supply current flow in a first direction from said first node through the winding to said second node, and for thereafter controlling said current switching structure to execute a first transition from said first configuration to a second configuration that permits power supply current flow in a second direction from said second node through the winding to said first node; and an energy storage device coupled to said one of said first and second nodes and cooperable with an inductive current that persists in said first direction through the winding during a first interval of said first transition for one of storing energy and releasing energy during said first interval, said current blocking device blocking said inductive current from said one power supply node during said first interval, said energy storage device operable, during said first transition and after said first interval, for the other of storing and releasing energy to permit a further current flow in said second direction from said second node through the winding to said first node.