A New Gradient Driver with only a Single DC Voltage Source For Using In MRI Systems

Magnetic Resonance Imaging (MRI) systems use a gradient field for space encoding. The gradient drivers must drive gradient coils with a high current, greater than 1kA, and a high voltage, greater than 2kV, for fast slew rate and fast imaging. These drivers use multi-level staked H-bridges with several isolated voltages and high switching frequency to achieve high voltage, high fidelity, and high current values. The MRI systems use power supplies (PS) to generate and regulate these isolated voltages from a power source provided by the power distribution unit (PDU). A typical waveform of the gradient unit results in pulse power up to ten times of the average power. Moreover, all the power chain must be designed to deliver peak power, properly. A new gradient driver with one dc source and two capacitors, as energy storage (ES), is proposed in this paper that can minimize the peak power and does not need several isolated dc voltage sources for each gradient driver. Thus, the PS unit can be eliminated from the power chain; and the gradient driver can connect directly to the PDU. A switching strategy is chosen for controlling the output current, which minimizes the power drawn from the capacitors. The proposed topology has been simulated under different conditions to verify its performance.