With Joseph Kover SpaceWire Mux-Demux architecture EPS (Electrical Power Subsystem): The EPS is composed of a PCDU (Power Control Distribution Unit), a rechargeable battery, and two deployable solar generators. The PCDU is designed to handle over 150 FET switch outlet channels, converts the primary 28 V to the users demand secondary voltage, as well as regulates solar power input to the spacecraft. The FS-5 battery has a capacity of 24 Ah provided by small cells in a 8 series 16 parallel configuration. Each solar panel contains of 19 solar strings with 20 TJ GaAs solar cells in series. The solar generators can support FS5 mission in 280 W orbit average power. The PCDU was domestically developed. The device contains seventeen circuitry modules with more than a hundred power distribution channels. Power is collected from 38 solar electricity control paths. The PCDU EM has been intensively tested on the satellite EDM (Engineering Development Module) along with the OBC EM and an early-released flight software build to verify the satellite command and telemetry contents. 10) 11) The main functions of the PCDU are to condition energy from the solar arrays and distribute power for all subsystems on the satellite. The PR (Power Relay) module, one of the major modules in the PCDU, is to manage the switchover of redundant DC-DC converter sections, secondary power distribution and power protections. Each set of internal/external DC-DC converter section which is protected by an OC (Over Current) protection with LCL (Latch-up Current Limiter) is controlled by the PR module’s FPGA. To avoid a short circuit in the DC-DC converter sections, the PR module provides UV (Under Voltage) protection to switch the nominal DC-DC converter to the redundant DC-DC section. In order to monitor the primary power voltage, an UVLO (Undervoltage-Lockout) detection circuit with majority voting in the FPGA is integrated in PR module. Figure 7 shows the main functional blocks of the PR module.
Posted on: Thu, 18 Sep 2014 12:48:50 +0000
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