Olivier Mourra

Buck Boost Regulator (B 2 R) for spacecraft Solar Array Power conversion

Solar Array Regulators (SAR) in a satellite Power Conditioning Unit (PCU) are implemented to transfer the power during sunlight from the solar arrays to the power bus. The objective of this paper is to present how Buck Boost Regulators (B2R) could be used as Step-Up, Direct Energy Transfer and Step-Down Solar Array Regulators. Control circuitries of a new kind are introduced for regulated and unregulated buses, illustrated by practical results demonstrating that such regulators can be used in satellite power systems.

Battery discharge regulator for space applications based on the boost converter

When a DC/DC converter is used to control the power on the main bus of a spacecraft it needs to comply with highly demanding requirements from the dynamic point of view. Hence, converters with very good dynamic performance, i.e. with no zero on the right-half plane are typically used. The conventional boost converter has not been used in European space applications mainly because of its poor dynamics. This paper addresses the way of using a boost converter in this application and demonstrates that this converter can cope with the very demanding requirements needed. A prototype has been built and tested to proof it.

Multiple port DC DC converter for spacecraft Power Conditioning Unit

In a satellite, the main function of a Power Conditioning Unit (PCU) is to manage the energy coming from several power sources (usually solar arrays and battery) and to deliver it continuously to the users in an appropriate form during the overall mission. The objective of this paper is to present an electronic switching DC-DC converter called Buck-Buck-Boost Regulator (B3R) that could be used as a modular and recurrent solution for regulated satellite power bus classes. The power conversion stages of the B3R topology are first described. Then theoretical equations and practical tests illustrate how the converter operates in term of power conversion, control loops performances and efficiency. The paper finally provides some examples of single point failure tolerant implementation using the B3R.

Large signal model with dynamic CCM - DCM detection

This paper proposes a large signal model for generic DC/DC converters that copes with both CCM and DCM modes. In the model, both the peak and the valley current of the inductor are also modeled. The mode change is detected dynamically by sensing the zero crossing of the valley current. The peak value needs some specific detection system to avoid mismatches during large transients. Voltage and current control modes are both used and the results are checked both by simulation and experimentally.

Simple self driven post-regulator for space applications

The secondary power system built inside the different units of a satellite typically needs several output voltages. The most common solution to achieve this is by means of a DC/DC converter with one or several outputs and linear regulators. The number of components available for European designers is relatively limited and hence, common solutions in ground applications are not so simple to implement in space applications. This paper presents the design of a switched post regulator with self driven synchronous rectification. The objective is to achieve a driving scheme for both converter switches based on a simple single output PWM IC. By replacing the linear regulators by switched converters, the efficiency improvement is very significant. A prototype has been built and tested and the results are presented in this paper.

28V bus solar array regulator based on converters with transformer and self-driven Synchronous Rectification

Satellite power systems are generally based on non isolated topologies. Simplicity, robustness and high efficiency are the key parameters and hence, these topologies are the leaders. However, extra switches are needed for protection; the design of the MOSFET drivers is not so simple if a full excursion from 0% to 100% is needed; the design has to be changed accordingly with the design of the solar array. An alternative concept is proposed in this paper and is based on topologies with transformer. Less switches are needed for protection and just by changing the transformer turns ratio, the converter can accommodate different designs of solar arrays. The main drawback is the efficiency, which is a key player in the space power systems. To overcome this, a Synchronous Rectification system is proposed in order to boost the efficiency with respect to the diode version counterpart. A new system based on the output inductor waveforms is also proposed in this paper.