Motor drive and control circuit for electric power steering

An electric circuit for use in the control and drive of at least one electric motor, the electric circuit comprising:

• a first lane comprising a first set of motor windings arranged as a plurality of phases, the first set of motor windings being driven by a first motor drive bridge that comprises a network of first drive stage switches that selectively connect each phase of the first lane to a first supply voltage and a first supply lane ground, and further comprising a first control circuit that controls the first drive stage switches, the first control circuit being powered by an isolated first lane power supply that has a first floating ground;
• a second lane comprising a second set of motor windings arranged as a plurality of phases, the second set of motor windings being driven by a second motor drive bridge that comprises a network of second drive stage switches that selectively connect each phase of the second lane to a second supply voltage and a second supply lane ground, and further comprising a second control circuit that controls the second drive stage switches, the second control circuit being powered by an isolated second lane power supply that has a second floating ground;
• the first control circuit and the second control circuit in use exchanging digital control signals such that the control circuit of each of the first lane and the second lane can monitor the function of the other of the first lane and the second lane;
• and
• wherein the first and second floating grounds and the first and second supply lane grounds are connected together through a potential divider network that holds the first and second floating grounds at a potential that is between the potential of the first and second supply lane grounds for the first and second lanes.