Patent ID: 7253625

Claim:
A controlled power supply for driving a magnetic field gradient coil of a magnetic resonance imaging apparatus, the power supply including: a plurality of switching power regulators electrically connected in series to deliver power to the gradient coil; and a control circuit that delivers phase staggered pulse width modulated control signals to the switching power regulators, the control circuit including: phase shifting circuits that each introduce a different selected phase shift to an a.c. carrier signal to define phase staggered a.c. carrier signals, pulse width modulation circuits that each receive one of the phase staggered a.c. carrier signals and produce a pulse train at a frequency and phase selected by the received phase staggered a.c. carrier signal, and a feedback controller communicating with the pulse width modulation circuits to control a pulse width of pulses of the pulse trains based on a set point and a feedback signal from the magnetic field gradient coil.