To select a power conversion circuit suitable for a missile-borne power module, it is necessary to consider many factors comprehensively to ensure that the power module can reliably and efficiently power the missile-borne equipment in the complex working environment of the missile. Here are some key considerations and selection methods:

1. Power Requirements:

• Determine The Load Power:

Accurately calculate the power requirements of each device on the missile under different working conditions, including peak power and average power. For example, the guidance system of a missile consumes relatively little power when searching for targets, but may require more power when accurately tracking and adjusting attitude. For devices that require high power supply, such as the drive motor of a booster, it may be necessary to select a conversion circuit that can provide high power output, such as a full-bridge type or other double-ended DC converter; for devices with lower power, such as sensors or small control chips, a flyback converter or a simple Buck circuit may be sufficient to meet the needs.

• Consider Power Margin:

In order to cope with possible load changes and emergencies, a certain power margin should be reserved when selecting a power conversion circuit. Generally speaking, the power margin can be set at around 10% - 20%, but the specific value needs to be determined according to the actual situation and reliability requirements of the missile. For example, for military applications with extremely high reliability requirements, the power margin may be appropriately increased.

2. Voltage Conversion Requirements:

• Input voltage range:

Clearly define the input voltage range of the missile-borne power supply, including the normal operating voltage range and the possible fluctuation range. Different power conversion circuits have different adaptability to input voltage. For example, the Buck circuit is suitable for situations where the input voltage is higher than the output voltage, while the Buck-Boost circuit can adapt to situations where the input voltage is higher or lower than the output voltage. Select a conversion circuit that can work stably within a given input voltage range to ensure the stability of the output voltage.

• Output voltage accuracy:

Select a suitable conversion circuit based on the requirements of the missile-borne equipment for power supply voltage accuracy. Some equipment with extremely high voltage accuracy requirements, such as high-precision guidance chips, may need to select circuits with high-precision voltage regulation control, such as forward converters or LLC resonant converters with closed-loop feedback control; while for equipment with relatively low voltage accuracy requirements, low-cost circuits can be selected, such as simple Buck circuits.

3. Efficiency Requirements:

• Consider working efficiency:

Missiles have limited energy, so the efficiency of the power conversion circuit is crucial. An efficient conversion circuit can reduce energy loss and extend the working time of the missile. LLC resonant converters are usually more efficient because they can achieve soft switching and reduce switching losses. They are suitable for missile-borne power modules with high efficiency requirements; while some simple non-isolated converters, such as Buck circuits, may have reduced efficiency under light loads, and need to be comprehensively considered according to the actual load conditions.

• Heat dissipation requirements:

High-efficiency conversion circuits generate relatively less heat, which is conducive to simplifying heat dissipation design. Heat dissipation is particularly important in the limited space of missiles. Selecting a high-efficiency conversion circuit can reduce the volume and weight of the heat dissipation device and improve the overall performance of the missile-borne power module.

4. Reliability and stability:

• Environmental Adaptability:

Missiles will experience severe vibration, impact, high temperature, low temperature and other harsh environments during flight. The selected power conversion circuit should have good vibration and impact resistance, and be able to work stably under extreme temperature conditions. For example, circuits using potting technology or reinforcement design can improve their vibration and impact resistance; and selecting components and circuit topologies with wide temperature range working capabilities can ensure the stability of the circuit under different temperature conditions.

• Circuit Protection Function:

The missile-borne power module needs to have complete protection functions, such as overvoltage protection, overcurrent protection, short circuit protection and overheating protection. Different power conversion circuits may differ in the implementation of protection functions. Some circuit topologies themselves have certain protection characteristics, such as the flyback converter has certain self-protection capabilities when short-circuited; and for some applications that require more powerful protection functions, conversion circuits with special protection circuits can be selected to ensure the safety of circuits and equipment under various fault conditions.

5. Volume And Weight Restrictions:

• Miniaturization And Lightweight Requirements:

The internal space of the missile is limited, and there are strict restrictions on the volume and weight of the power module. When selecting a power conversion circuit, circuit topologies with small size and light weight should be given priority. For example, the use of highly integrated chips and miniaturized components, as well as optimized circuit layout, can reduce the volume of the circuit; while the selection of lightweight materials and packaging forms can reduce the weight of the circuit. Some new power conversion circuits, such as circuits based on wide bandgap semiconductor materials such as gallium nitride (GaN) or silicon carbide (SiC), have higher power density and can achieve higher power output in a smaller volume, which is more suitable for the application requirements of missile-borne power modules.

6. Electromagnetic Compatibility (EMC):

• Reduce electromagnetic interference:

The electromagnetic interference (EMI) generated by the missile-borne power module may affect the normal operation of other equipment on the missile, so it is necessary to select a power conversion circuit with good electromagnetic compatibility. Some circuit topologies, such as Cuk converters and Sepic converters, have good electromagnetic compatibility due to their continuous input and output currents and small ripples; and for some circuits that are prone to generate large electromagnetic interference, such as circuits with high switching frequencies, effective electromagnetic shielding and filtering measures need to be taken to reduce the impact of electromagnetic interference on other equipment.

• 7. Cost And Maintainability:

• Cost Control:

On the premise of meeting performance requirements, the cost of the power conversion circuit needs to be considered. Different circuit topologies and component selection will have a great impact on the cost. Some complex circuit topologies, such as LLC resonant converters, have superior performance but high costs; while some simple circuit topologies, such as Buck circuits, have relatively low costs. It is necessary to comprehensively consider cost factors based on the actual needs and budget of the missile and select a cost-effective conversion circuit.

• Maintainability:

Considering the convenience of the missile during use and maintenance, the selected power conversion circuit should have good maintainability. The circuit structure should be as simple as possible, and the selection of components should be easy to replace and repair. At the same time, necessary test points and diagnostic functions should be provided so that faults can be quickly located and eliminated when they occur.