What you’ll learn:
- Differentiation between power and energy density.
- The key role of GaN-on-SiC in achieving power-density goals.
- 应用程序在设计中寻求更大的功率密度。
设计强大的电源，设计师需要了解一些基础和陷阱。
功率密度与能量密度相同吗？
功率密度和能量密度完全不同。
Energy density (W/kg) can be described as the amount of energy stored per unit with mass (kg), area (cm2), or volume (L). Power density (W/kg) is the amount of energy flow per unit (mass, area, volume) per unit time (s). A system is said to have a high energy density when it’s able to store a large quantity of energy in a small amount of mass.
Regarding batteries: Energy density relates to the amount of energy that can be stored per battery unit, whereas power density relates to the maximum amount of energy that can be discharged or delivered per battery unit.
By comparison, capacitors offer very high power density but low energy density. Capacitors are good for short bursts of very high current and batteries excel at providing lower currents for extended periods of time.
为什么电力密度重要？
功率密度在电源中很重要，尤其是空间限制区域。这里的一个很好的例子是数据中心 - 设计师需要有效地填充尽可能多的处理能力的空间。加工功率速度继续加速跨越式和界限，耐力处理器需要大量的功率。这意味着更高功率密度的电源变得更加重要。
最重要的一个权力densit的领域y is vital to humans on Planet Earth is the amount of energy we can extract from renewable sources per section of land—that is, power density in W/m2.
正在做什么样的研究来优化阿宝wer density?
Essentially, reducing the size of a power supply will lead to better power density（见图）.
The电源制造商协会（PSMA）通过在印刷电路板（PCB）刻度上的3D包装开发，在电力密度方面做了重要的工作。该组还有助于开发设计以提高电流密度和功率密度电动机具有改进的热管理.
The PSMA is involved in PCB embedding technologies in high-volume production. This, along with 3D packaging technology, will lead to a significant performance and size reduction in a power supply. In addition, high-power-density component embedding and 3D packaging of power semiconductors must overcome a “thermal barrier.” That’s because it’s more challenging to remove heat generated within the body of a 3D integrated system than from a planar surface.
Gan-on-SIC如何提高功率密度？
碳化硅上的氮化镓（GaN-On-SiC）具有GaN-On-Si的导热率的三倍，使设备能够以更高的电压和更高的功率密度运行。电信和无线行业需要良好的导热率。
Silicon devices can’t even come close to this level of power density. Power-supply designers are now able to select a GaN transistor instead of silicon for its small form factor and high efficiency. GaN transistors also dissipate less power and offer higher thermal conductivity compared to silicon devices with higher thermal-management requirements.
How important is the physical size of a power supply to power density?
First of all, improving power-supply efficiency leads to the physical size reduction of the supply. So, power-density numbers are essentially based on the power-converter power rating and the “box volume” (length × width × height) of the power solution with all associated components included. Designers’ first efforts are usually to simply reduce the size of bulky, but important, passive energy-conversion components like capacitors, inductors, and transformers.
Modern power supplies can usually run at higher switching frequencies via the use of wide-bandgap (WBG) power-transistor components primarily from the GaN and SiC transistor variety. Drawbacks of WBG devices running at higher switching speeds are the power-transistor switching losses at high frequencies that lead to higher temperatures and higher switching losses. These problems can be addressed by innovative thermal designs to remove heat and creative gate-driver designs.
此外，PSMA在集成中具有一些非常先进的技术，导致较小的“框卷”。输入3D电源包装。
3D Power Packaging
PCB房地产处于溢价，因此PSMA已选择在Z轴上垂直构建。半导体IC和无源元件（包括磁性）都是向上堆叠的。
电力器件集成到模压包装内的PCB中;巧妙的设计正在用包装中的3D堆叠实施;甚至衬底嵌入的被动甚至用于增加分量密度并大大降低互连长度。
New design ideas have cleverly made use of many other technologies. They include techniques that move toward shrinking a conventional PCB to the point of ultimately eliminating it altogether while increasing power density (W/cm3).
需要高功率密度的主要区域是什么？
Drones
电动推进是无人机的主要技术之一，因为它具有效率，可靠性，降低噪声和热签名等许多优点，以及精密控制。内燃机（ICE）缺乏这些关键特征，尽管其高功率和能量密度，但仍然可以使用它。
燃料电池和电池：无人机，当由燃料电池作为独特的电源供电时，将有一些限制。电池将提供起飞和攀登所需的峰值功率，因为它具有更高的功率密度和更快的响应。
与电池相比，超级电容器具有更高的特定功率。超级电容器技术的特征在于快速充电/放电速度，过度充电公差以及极低降低直流母线电压波动的能力。因此，超级电容器将通过允许更高的功率密度和快速功率响应来加强混合电源系统。
Data Centers
Data centers have experienced a growing need for higher density and higher levels of redundancy.
Dramatic changes in how power is utilized in data centers have challenged a 40-year-old architecture, specifically driven by increasing power density. Looking at the power density of IT racks, the per-rack power density has increased exponentially. A modern metric in data centers is the higher a particular facility’s power density, the better it could support the needs of clients as well as end users.
以40至80 w / ft的传统密度指定数据中心。2（430至861 w / m2）将导致无法可靠地部署最新一代IT设备。
RF传播
对于您的RF设计人员：从各向同性天线辐射的RF发射器的功率将在所有方向上具有均匀的功率密度（功率/单位区域）。距各向同性天线的任何距离处的功率密度仅仅是由球体的表面积除以的发射器功率（4π.
R2）在那个距离。
The surface area of the sphere increases by the square of the radius; therefore, the power density, PD, (watts/square meter) decreases by the square of the radius.
结论
功率密度是功率设计人员需要完全理解和利用以实现稳健和高效的功率转换器设计的有用指标。电力系统设计将在温度和环境极值上变化，因此设计人员必须识别环境的特定需求，并且电源需要服务的具体功能。了解电力密度及其在设计中的重要性将提高整体系统效率和长寿未来。
