# US 2010/0164458 A1 · Inductive power system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0164458 A1 - Document ID: US20100164458A1 - Status: Published application - Kind: A1 - Application number: 12/376,548 - Filed: 2007-08-03 - Published: 2010-07-01 - Earliest claimed: 2006-08-09 - Assignees: MBDA UL Limited - Inventors: Keith Graham Pollard - Web page: https://patentgrep.com/patent/US20100164458A1 ## CPC - H02J 50/80: involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices - F42C 11/04: with current induction - F42C 17/04: for electric fuzes - H02J 50/10: using inductive coupling - H02J 50/12: of the resonant type - H02J 2105/32: {for aircrafts} - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - F42C: AMMUNITION FUZES (blasting cartridge initiators F42B3/10; chemical aspects C06C); ARMING OR SAFETY MEANS THEREFOR (filling fuzes F42B33/02; fitting or extracting primers in or from fuzes F42B33/04; containers for fuzes F42B39/30) ## Abstract An inductive power transfer system for coupling a power source to a load across an air gap is provided, including a primary unit and a secondary unit separable from the primary unit and arranged to receive power inductively from the primary unit when placed proximate thereto. The system includes a multi stage comparator for monitoring operating conditions within the secondary unit and feedback loop for transmitting a feedback signal to the primary unit when predetermined operating conditions are detected within the secondary unit. The primary unit is arranged to operate in a low power mode where power is applied to the primary winding for a minimal period during each switching cycle when no feedback signal is received and a high power mode where power is applied to the primary winding for the majority of each switching cycle when a feedback signal is received. The power transfer system functions by applying bursts of power from the primary to the secondary unit, the bursts becoming more frequent and of longer duration as the load on the secondary unit increases or the air gap increases, so as to transfer more power or maintain power as air gap losses increase. The bursts of power will also change their duration and frequency in correspondence with variations of the input power supply to the primary unit, so as to maintain the voltage regulation of the power delivered to the secondary unit. ## Claims ### Claim at position 1 1-16. (canceled) ### Claim 17 An inductive power transfer system for coupling a power source to a load across an air gap, comprising: a primary unit associated with a host platform and a secondary unit for applying a voltage to a load, the secondary unit being separable from the primary unit and arranged to receive power inductively from the primary unit when placed proximate thereto, the primary unit comprising a primary transformer winding and switching means for controlling the application of power to the primary winding and the secondary unit comprising a secondary transformer winding; control means comprising a multi-stage comparator circuit for monitoring the applied voltage; and feedback means for transmitting a feedback signal to the primary unit when the applied voltage falls below a lower predetermined voltage and for deactivating said feedback signal when the applied voltage exceeds an upper predetermined voltage, wherein the primary unit is arranged to operate in a low power mode where power is applied to the primary winding for minimal period during each switching cycle when no feedback signal is received and a high power mode where power is applied to the primary winding for a majority of each switching cycle when a feedback signal is received so that the applied voltage can be regulated between the upper and the lower predetermined voltages. ### Claim 18 (depends on 17) An inductive power transfer system according to claim 17, wherein in the high power operating mode, power is applied to the primary winding except during a dead-band period at the beginning and end of each switching cycle. ### Claim 19 (depends on 17) An inductive power transfer system according to claims 17, wherein the multi-stage comparator is operable to monitor the voltage induced in the secondary winding and to output a signal to the feedback means when the induced voltage exceeds a first predetermined voltage causing a feedback signal to be transmitted to the primary unit. ### Claim 20 (depends on 17) An inductive power transfer system according to claim 17, wherein the multi-stage comparator is arranged to monitor the voltage level in a storage capacitor coupled to the secondary winding and to activate an output switch to apply power to the load when the voltage level exceeds a second predetermined voltage. ### Claim 21 (depends on 20) An inductive power transfer system according to claim 20, wherein the multi-stage comparator circuit is operable to monitor the voltage applied to the load and to output a signal to the feedback means when the applied voltage exceeds said upper predetermined voltage causing the feedback signal to the primary unit to be deactivated. ### Claim 22 (depends on 21) An inductive power transfer system according to claim 21, wherein the multi-stage comparator is operable to output a signal to the feedback means when the applied voltage falls below said lower predetermined voltage causing a feedback signal to be transmitted to the primary unit. ### Claim 23 (depends on 17) An inductive power transfer system according to claim 17, further comprising a tuning capacitor connected in parallel with the secondary winding. ### Claim 24 (depends on 23) An inductive power transfer system according to claim 23, wherein the tuning capacitor is arranged to resonate at a predetermined frequency when the width of the air gap separating the transformer cores of the primary and secondary windings is a predetermined maximum value. ### Claim 25 (depends on 17) An inductive power transfer system according to claim 17, wherein the width of the air gap between the primary and secondary windings lies in the range 1 to 6 mm. ### Claim 26 (depends on 17) An inductive power transfer system according to claim 17, wherein in low power mode operation, power is applied to the primary winding for 5% of the switching cycle. ### Claim 27 (depends on 17) An inductive power transfer system according to claim 17, wherein in high power mode operation, power is applied to the primary winding for 95% of the switching cycle. ### Claim 28 (depends on 17) An inductive power transfer system according to claim 17, wherein the power source is arranged to produce an output dc voltage of 270V. ### Claim 29 (depends on 17) An inductive power transfer system according to claim 17, wherein the power source includes a local power source arranged to supply components within the primary unit. ### Claim 30 (depends on 17) An inductive power transfer system according to claim 17, wherein the feedback means comprises an infrared system. ### Claim 31 (depends on 17) An inductive power transfer system according to claim 17, wherein the switching means comprises a power amplifier that applies power to the primary winding in a push-pull format. ### Claim 32 (depends on 17) An inductive power transfer system according to claim 17, wherein the primary unit (20) is carried by a host aircraft and the secondary unit is carried by a launchable vehicle. ### Claim 33 (depends on 17) An inductive power transfer system according to claim 17, wherein said applied voltage can be regulated between the upper and the lower predetermined voltages independent of variations of the input supply to the primary unit, variations in the air gap between the primary and secondary units and variations in the current demanded by the load. ### Claim 34 (depends on 17) An inductive power transfer system according to claim 17, wherein a storage capacitor is coupled to the secondary winding and when the applied voltage exceeds an upper predetermined voltage and the feedback signal is deactivated the storage capacitor discharges into the load. ### Claim 35 An inductive power transfer system for coupling a power source to a load across an air gap, comprising: a primary unit associated with a host platform and a secondary unit for applying a voltage to the load, the secondary unit being separable from the primary unit and arranged to receive power inductively from the primary unit when placed proximate thereto, the primary unit comprising a primary transformer winding and switches for controlling the application of power to the primary winding and the secondary unit comprising a secondary transformer winding; a control circuit comprising a multi-stage comparator circuit for monitoring the applied voltage; and a feedback loop for transmitting a feedback signal to the primary unit when the applied voltage falls below a lower predetermined voltage and for deactivating said feedback signal when the applied voltage exceeds an upper predetermined voltage, wherein the primary unit is arranged to operate in a low power mode where power is applied to the primary winding for minimal period during each switching cycle when no feedback signal is received and a high power mode where power is applied to the primary winding for the majority of each switching cycle when a feedback signal is received so that the applied voltage can be regulated between the upper and the lower predetermined voltages.