European Space Agency Esa Tender

Tenders are invited for: power unit for high power radars and altimeters improving the dynamic performance under pulsed operation Tender issuepulsed loads like radars altimeters and scatterometers usually have very demanding power requirements. the power is delivered in short pulses which require precision synchronisation and the ability to deliver high power in very short time. in general the platform is highly affected by these pulses and it is key to minimise the noise injection at platform level. future mission will have todouble the pulse repetition frequency reduce the duty cycle and increase the power.Missions with pulsed payloads usually show problems related to the interaction of the power pulses with the rest of the platform. thus an improvement of theperformance and reliability of those units is highly needed. missions with radars altimeters and scatterometers will all benefit from this development.The improvement of the performance of pulsed payloads has to be tackled from multiple sides. the system level concept is important in order to channel the highpower pulses through paths that have the least disturbance effect. thus a power system trade-off is necessary to understand the best possible system configuration.In terms of reducing the electrical noise the development of active filtering techniques is key. given the frequency of the pulses passive filtering is cumbersome and active filtering seems the best alternative.The dc/dc converter topology is also a key point due to the high current capability needed. concepts with current doublers or multi-phase converters will be needed to comply with the requirements. since the conversion stage is located as close as possible to the antenna mass and volume is a key aspect. in that sense the tradeoff related to the number of converters needed in parallel or in a matrix configuration will define many aspects of the topology. the matrix concept using a high number of converters (>200) looks like a very promising option.Operation at high switching frequency will be needed to reduce mass and volume. thus the exploration of gan switches operating in the mhz range is a viable option.Encapsulation of these building block converters could be anoption that enables very high integration levels. this high switching frequency can enable theelimination of tantalum capacitors which is a source of problems in this high current applications.In order to handle the high power pulses with multi-converter solutions digital control can enable complex connection/disconnection patterns of the matrixconfiguration that can enable a higher performance of the system.This activity encompasses the following tasks:- power system analysis to trade off different concepts at platform level- payload power subsystem trade off to identify the main building blocks and redundancy concept- identification of