Pulsed power system and control method thereof

A controlling method of a pulsed power system comprising at least two H-bridges cascaded for providing pulsed current to a load, comprising:

• receiving a load current signal and a reference current signal;
• generating a voltage command signal based on the load current signal and reference current signal;
• determining a slew rate and a current amplitude of the load current associated with the reference current signal;
• and
• reducing switching loss in response to the slew rate being lower than a threshold;
• wherein each H-bridges comprises at least two legs, each leg comprises a plurality of modules connected in parallel, each module comprises two transistor switches connected in series, the diode is configured to conduct current to cause zero voltage potential across a source and a drain of the transistor, and nodes between two transistor switches of each module are electrically connected, wherein reducing the switching loss comprises keeping at least one module off, and making rest of the modules switching, in response to the slew rate being lower than the threshold and the current amplitude being lower than a predetermined level.

A MRI system, comprising:

• a primary field magnet;
• a plurality of gradient coils;
• a RF transmit coil;
• and
• a pulsed power system comprising:
• at least two H-bridges cascaded for providing pulsed current to a load of the gradient coils, wherein each H-bridge comprises at least two legs, and each leg comprises at least two transistor switches connected in series, wherein each transistor switch comprises a transistor and a diode electrically coupled with the transistor in parallel, and the gradient coils are connected between a node between the two transistor switches of a first leg of a first H-bridge of the at least two H-bridges and a node between the two transistor switches of a second leg of a second H-bridge of the at least two H-bridges;
• and
• a controller configured to:
• determine if a slew rate of the load current across the load of the gradient coil is lower than a threshold, and
• reduce switching loss in response to the slew rate being lower than the threshold.