# US 10,768,249 B2 · Pulsed power system and control method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,768,249 B2 - Document ID: US10768249B2 - Status: Granted - Kind: B2 - Application number: 16/029,324 - Filed: 2018-07-06 - Published: 2019-01-10 - Granted: 2020-09-08 - Earliest claimed: 2017-07-07 - Assignees: GE Precision Healthcare LLC - Applicants: GE Precision Healthcare LLC - Inventors: Ruxi Wang; Juan Antonio Sabate; Fei Xu; Xiaohu Liu - Web page: https://patentgrep.com/patent/US10768249B2 ## CPC - G01R 33/3852: {Gradient amplifiers; means for controlling the application of a gradient magnetic field to the sample, e.g. a gradient signal synthesizer} - H02M 3/07: using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps} - H02M 7/5387: in a bridge configuration - H03K 3/012: Modifications of generator to improve response time or to decrease power consumption - H03K 17/102: {in field-effect transistor switches} - H03K 17/687: the devices being field-effect transistors - H02M 1/0054: {Transistor switching losses (periodically suspending operation of switching converter in low power mode H02M1/0035)} - H02M 1/0077: {Plural converter units whose outputs are connected in series} - H03K 2217/0036: Means reducing energy consumption - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract A pulsed power system is disclosed, which comprises at least two H-bridges cascaded for providing pulsed current to a load. Each H-bridge comprises at least two legs, and each leg comprises at least two transistor switches connected in series. Each transistor switch comprises a transistor and a diode electrically coupled with the transistor in parallel. The pulsed power system also comprises a controller configured to determine if a slew rate of the load current is lower than a threshold, and to reduce switching loss in response to the slew rate being lower than the threshold. ## Claims ### Claim 1 A pulsed power system, comprising: at least two H-bridges cascaded for providing pulsed current to a load, 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 diode is configured to conduct current across a source and a drain of the transistor, and the load is 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 a load current across the load is lower than a threshold; and reduce switching loss in response to the slew rate being lower than the threshold. ### Claim 2 (depends on 1) The pulsed power system of claim 1, wherein the controller is configured to use a first switching frequency in response to the slew rate being not lower than a threshold, and use a second switching frequency, which is lower than the first frequency, in response to the slew rate being lower than a threshold. ### Claim 3 (depends on 1) The pulsed power system of claim 1, wherein the controller is further configured to: determine if a current amplitude of the load current is lower than a predetermined level; and make at least one H-bridge in conducting, and make rest of the H-bridges in switching in response to the slew rate being lower than the threshold and the current amplitude being lower than the predetermined level. ### Claim 4 (depends on 1) The pulsed power system of claim 1, wherein the controller is further configured to: determine if a current amplitude of the load current is lower than a predetermined level; and raise the current amplitude of the load current to higher than a predetermined value in response to the slew rate being lower than the threshold and the current amplitude being lower than the predetermined level. ### Claim 5 (depends on 1) The pulsed power system of claim 1, wherein 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 across a source and a drain of the transistor, and nodes between two transistor switches of each module are electrically connected, wherein the controller is further configured to: determine if a current amplitude of the load current is lower than a predetermined level; and keep at least one module off, and make rest of the modules switching, in response to the slew rate being lower than the threshold and the current amplitude being lower than the predetermined level. ### Claim 6 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. ### Claim 7 (depends on 6) The method of claim 6, wherein reducing the switching loss comprises using a first switching frequency in response to the slew rate being not lower than the threshold, and using a second switching frequency, which is lower than the first frequency, in response to the slew rate being lower than a threshold. ### Claim 8 (depends on 6) The method of claim 6, wherein reducing the switching loss comprises making at least one H-bridge in conducting, and making rest of the H-bridges in switching, in response to the slew rate being lower than the threshold and the current amplitude being lower than a predetermined level. ### Claim 9 (depends on 6) The method of claim 6, wherein reducing the switching loss comprises raising the current amplitude of the load current to higher than a predetermined level, in response to the slew rate being lower than the threshold and the current amplitude being lower than the predetermined level. ### Claim 10 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. ### Claim 11 (depends on 10) The MRI system of claim 10, wherein the controller is configured to use a first switching frequency in response to the slew rate being not lower than the threshold, and using a second switching frequency, which is lower than the first frequency, when the slew rate is lower than the threshold. ### Claim 12 (depends on 10) The MRI system of claim 10, wherein the controller is further configured to: determine if a current amplitude of the load current is lower than a predetermined level; and make at least one H-bridge in conducting, and make rest of the H-bridges in switching in response to the slew rate being lower than the threshold and the current amplitude being lower than the predetermined level. ### Claim 13 (depends on 10) The MRI system of claim 10, wherein the controller is further configured to: determine if a current amplitude of the load current is lower than a predetermined level; and raise the current amplitude of the load current to higher than a predetermined value in response to the slew rate being lower than the threshold and the current amplitude being lower than the predetermined level. ### Claim 14 (depends on 10) The MRI system of claim 10, wherein 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 across a source and a drain of the transistor, and nodes between two transistor switches of each module are electrically connected, wherein the controller is further configured to: determine if a current amplitude of the load current is lower than a predetermined level; and keep at least one module off, and make rest of the modules switching, in response to the slew rate being lower than the threshold and the current amplitude being lower than the predetermined level.