选择右离网逆变器伟德足球指数投注
这逆变器是独立能源系统中最重要，最复杂的组件之一。要选择逆变器，您不必了解其内部工作，但是您应该知道一些基本功能，功能和局限性。本文为您提供了选择正确的逆变器并明智地使用它所需的一些信息。
为什么需要逆变器
Independent electric energy systems are untethered from the electrical utility grid. They vary in size from tiny yard lights to remote homes, villages, parks, and medical and military facilities. They also include mobile, portable, and emergency backup systems. Their common bond is the storage battery, which absorbs and releases energy in the form of direct current (DC) electricity.
相比之下，公用电网为您提供交替的电流（AC）电力。交流是任何“插入”实用程序的任何电力的标准形式。直流向一个方向流动。AC每秒多次交替其方向。AC用于电网服务，因为它对于长距离传输更为实用。
大型逆变器
逆变器将直流转换为AC，并更换电压。换句话说，这是一个电源适配器。它允许abattery-based systemto run conventional appliances through conventional home wiring. There are ways to use DC directly, but for a modern lifestyle, you will need an inverter for the vast majority, if not all of your loads (loads are devices that use energy).
Incidentally, there is another type of inverter called grid-interactive. It is used to feed solar (or other renewable) energy into a grid-connected home and to feed excess energy back into the utility grid. If such a system does not use batteries for backup storage, it is not independent from the grid, and is not within the scope of this article.
Not a Simple Device
Outwardly, an inverter looks like a box with one or two switches on it, but inside there is a small universe of dynamic activity. A modern home inverter must cope with a wide range of loads, from a single night light to the big surge required to start a well pump or a power tool. The battery voltage of a solar or wind system can vary as much as 35 percent (with varying state of charge and activity).
通过所有这些，逆变器必须在狭窄的约束内调节其产出的质量，并减少功率损耗。这不是简单的任务。此外，一些逆变器提供电池备用充电，甚至可以将多余的电源馈入电网。
定义您的需求
To choose an inverter, you should first define your needs. Then you need to learn about the inverters that are available. Inverter manufacturers print everything you need to know on their specification sheets (commonly called “spec sheets”). Here is a list of the factors that you should consider.
应用环境
要在哪里使用逆变器？逆变器可用于建筑物（包括房屋），用于休闲车，船和便携式应用。它会以某种方式连接到公用电网吗？电气惯例和安全标准在各种应用方面有所不同，因此不要即兴创作。
电标准
这DC input voltage must conform to that of the electrical system and battery bank. 12 volts is no longer the dominant standard for home energy systems, except for very small, simple systems. 24 and 48 volts are the common standards now. A higher voltage system carries less current, which makes system wiring cheaper and easier.
逆变器的交流输出必须符合该区域中的常规功率，以便运行本地可用的电器。北美的AC公用事业服务标准为115和230伏，频率为60赫兹（每秒循环）。在欧洲，南美和大多数其他地方，有220伏特的伏特在50赫兹。
安全认证
逆变器应通过独立测试实验室（例如UL，ETL，CSA等）认证，并相应地盖章。这是您的保证，它将是安全的，将符合制造商的规格，并将在电气检查中获得批准。各种应用环境（建筑物，车辆，船只等）有不同的设计和评级标准。这些也因一个国家而异。
电力能力
逆变器可以承受多少负载？其功率输出以瓦数（瓦= AMPS X伏特）的额定值。有三个级别的功率评级 - 连续评级，限时评分和激增的评分。连续意味着逆变器可以无限期处理的功率。当逆变器以一定数量的瓦数进行额定值时，该数字通常是指其连续额定值。
限时评分是可以在定义的时间内（通常为10或20分钟）处理的较高数量的瓦特。逆变器规格应定义与环境温度（周围气氛的温度）有关的这些评分。当逆变器太热时，它将关闭。这将在炎热的气氛中更快地发生。第三级功率评级，电涌能力对于启动电动机的能力至关重要，并在下面进行讨论。
Some inverters are designed to be interconnected or expanded in a modular fashion, in order to increase their capacity. The most common scheme is to “stack” two inverters. A cable connects the two inverters to synchronize them so they perform as one unit.
功率质量：正弦波与“修改正弦波”
Some inverters produce “cleaner” power than others. Simply stated, “sine wave” is clean; anything else is dirty. A sine wave has a naturally smooth geometry, like the track of a swinging pendulum. It is the ideal form of AC power. The utility grid produces sine wave power in its generators and (normally) delivers it to the customer relatively free of distortion. A sine wave inverter can deliver cleaner, more stable power than most grid connections.
“正弦波”有多干净？制造商可以使用“纯”或“ true”术语来暗示较低的失真程度。事实包括在逆变器的规格中。总谐波失真（THD）低于6％，应满足正常房屋要求。如果您有异常关键的电子设备，例如在录音室中，请寻找不到3％。
其他规格也很重要。RMS电压调节使您的灯保持稳定。它应该是加上或减去5％或更少。峰值电压（VP）调节必须加上10％或更少。
“修改的正弦波”逆变器的逆变器价格较低，但它产生了扭曲的方波形，类似于锤子来回猛击的摆的轨道。实际上，这根本不是正弦波。广告人发明了误导性的“修改正弦波”一词。工程师更喜欢称其为“修改的方波”。
“修饰的正弦波”对许多电荷有不利影响。它将电动机和变压器的能源效率降低了10％至20％。浪费的能量会导致异常热量，从而降低了电动机，变压器以及其他设备的可靠性和寿命，包括一些设备和计算机。波涛汹涌的波形使某些数字计时设备混淆了。
大约5％的家用电器根本无法使用修改后的正弦波功率。几乎所有音频设备的扬声器都会听到嗡嗡声。一些荧光灯，吊扇和变压器也会发出令人讨厌的嗡嗡声。一些微波炉嗡嗡声或产生更少的热量。电视和计算机经常在屏幕上显示滚动线。电涌保护器可能过热，不应使用。
改良的正弦波逆变器在1980年代被耐受，但是从那时起，真正的正弦波逆变器变得更加有效，更实惠。有些人通过使用改良的波逆变器来运行其较大的动力工具或其他偶尔的重载荷以及一个小的正弦波逆变器来妥协，以运行其较小，更频繁和更敏感的负载。可再生能源系统中的修改波逆变器已开始逐渐衰落。
效率
不可能转换电源而不会失去一些（就像摩擦一样）。动力以热的形式损失。效率是电力与电力的比率，表示为百分比。如果效率为90％，则逆变器中有10％的功率损失。逆变器的效率随负载而变化。通常，在逆变器能力的三分之二约为三分之二的情况下，它将是最高的。这称为其“峰值效率”。逆变器需要一些功率才能自行运行，因此在运行很小的负载时，大逆变器的效率将很低。
在典型的房屋中，一天中有很多小时的电荷非常低。在这些条件下，逆变器的效率可能约为50％或更低。逆变器制造商出版了效率与负载的图表，讲述了整个故事。这称为“效率曲线”。仔细阅读这些曲线。一些制造商通过以100瓦左右的速度启动曲线作弊，而不是为零！
Because the efficiency varies with load, don’t assume that an inverter with 93 percent peak efficiency is better than one with 85 percent peak efficiency. If the 85 percent efficient unit is more efficient at low power levels, it may waste less energy through the course of a typical day.
内部保护
逆变器的敏感组件必须得到很好的保护，以防止附近的闪电和静态，以及在过载条件下从电动机反弹的冲浪。还必须保护它免受过载。过载可能是由故障的设备，接线故障或一次运行过多的负载引起的。
An inverter must include several sensing circuits to shut itself off if it cannot properly serve the load. It also needs to shut off if the DC supply voltage is too low, due to a low battery state-of-charge or other weakness in the supply circuit. This protects the batteries from over-discharge damage, as well as protecting the inverter and the loads. These protective measures are all standard on inverters that are certified for use in buildings.
为供水泵供电
在偏远的地点，水井或压力泵通常会对逆变器施加最大的需求。它值得特别考虑。大多数泵在启动过程中吸引了极高的电流。逆变器必须具有足够的电涌能力来处理它，同时运行任何其他负载。足够尺寸足够大的逆变器很重要，尤其是处理起始激增。如果您希望它启动泵而不会导致灯光变暗或眨眼，则它将进一步超大。向您的供应商询问此操作，因为逆变器制造商尚未提供足够的数据来与泵有关。
In North America, most pumps (especially submersibles) run on 230 volts, while smaller appliances and lights use 115 volts. To obtain 230 volts from a 115 volt inverter, either use two inverters “stacked” (if they are designed for that) or use a transformer to step up the voltage.
如果您尚未安装泵，则如果您不需要超过1/2 hp，则可以获得115伏泵。水泵承包商通常会提供比持有资源的家庭所需的更高的电动泵。您可以要求较小的泵，或者可能是可行的（和经济），以较小的泵代替现有的泵。您还可以考虑可用的越来越多的高效DC泵之一，以消除逆变器的负载。
Battery Charging Features
Backup battery charging is essential to most renewable energy systems because there are likely to be occasions when the natural energy supply is insufficient. Some inverters have a built-in battery charger that will recharge the battery bank whenever power is applied from an AC generator or from the utility grid (if the batteries are not already charged). This also means that an inverter can be a complete emergency backup system for on-grid power needs (just add batteries).
备用电池充电器不必内置逆变器。在某些情况下，单独的充电器优于内置的逆变器。在低开关频率逆变器的情况下，尤其如此，这往往需要超大型发电机来产生完整的额定电荷电流。
与电池充电系统相关的规格包括最大充电率（AMP）和交流输入功率要求。最好的充电器具有两个或三阶段的电荷控制，不同电池类型（洪水泛滥或密封），温度补偿和其他改进。
Be careful when sizing a generator to meet the requirements of an inverter/charger. Some inverters require that the generator be over-sized (because of low power factor, which is beyond the scope of this article). Be sure to get experienced advice on this, or you may be disappointed by the results.
Inductive Loads and Surge Capacity
一些负载会以时间延迟吸收交流波的能量（例如用橡胶表带拖动汽车）。这些称为电感载荷。电动机是最严重的电感载荷。它们是在井泵，洗衣机，冰箱，电动工具等中发现的。电视和微波炉也是电感载荷。像电动机一样，他们开始时吸引了力量激增。
如果逆变器无法有效地供电负载，则可以简单地关闭而不是启动设备。如果逆变器的激增能力很小，则其输出电压将在激增期间下降。这可能会导致房屋中的灯光变暗，有时会崩溃计算机。
Any weakness in the battery and cabling to the inverter will further limit its ability to start a motor. A battery bank that is undersized, in poor condition, or has corroded connections, can be a weak link in the power chain. The inverter cables and the battery interconnect cables must be big, and I mean REALLY big, perhaps the size of a large thumb! The spike of DC current through these cables is many hundreds of amps at the instant of motor starting. Follow the inverter’s instruction manual when sizing the cables, or you’ll cheat yourself. Coat battery connections with a protective coating to reduce corrosion.
Idle Power
Idle power is the consumption of the inverter when it is on, but no loads are running. It is “wasted” power, so if you expect the inverter to be on for many hours during which there is very little load (as in most residential situations), you want this to be as low as possible. Typical idle power ranges from 15 watts to 50 watts for a home-size inverter. An inverter’s spec sheet may describe the inverter’s “idle current” in amps. To get watts, just multiply the amps times the DC voltage of the system.
低开关频率与高开关频率
这re are two ways to build an inverter. Without diving into theory, I’ll simply say that there are differences in weight, cost, surge capacity, idle power, and noise.
较低的开关频率逆变器大而重（通常约20磅（每千瓦）约20磅（10千克）），并且更昂贵。它具有启动大型电动机所需的高电涌能力（是连续容量的四到八倍）。当心低转换频率逆变器所产生的声学嗡嗡声。如果您在生活空间附近安装一个，则可能对噪音不满意。
高开关频率逆变器要小得多，更轻（通常约5磅（2.5 kg）每千瓦），而且价格便宜。它的电涌能力较小，通常是连续容量的两倍。它几乎没有听到声音。闲置功率通常更高。如果逆变器超大尺寸用于电动机的启动，则其怠速功率将更高，并且可能会令人难以置信。大多数具有泵或其他电动机大于1 hp的房屋都会发现低开关频率逆变器更经济。
Both types of inverter have their virtues. Some people “divide and conquer” by splitting their loads and using two inverters. This adds a measure of redundancy. If one ever fails, the other one can serve as backup.
Automatic On/Off
逆变器空转可能是小型电源系统的重大负载。大多数用于家用电源系统的逆变器具有自动负载感应。逆变器大约每秒（或多或少）伸出一个短暂的力量脉冲。当您打开交流负载时，它会感觉到电流绘制并打开自身。制造商为此功能提供了各种名称，包括“负载需求”，“睡眠模式”，“电力避免”，“ Autostart”和“待机”。
自动开/关可能会使生活变得尴尬，因为微小的负载可能不会触发逆变器打开或保持。例如，洗衣机可以在周期之间停顿，只有计时器运行。计时器的绘制少于10瓦。逆变器的“阈值”可能为10或15瓦。逆变器关闭，直到看到其他设备的额外负载后才重新启动。运行洗衣机时，您可能必须留下灯。
有些人无法适应这种情况。因此，具有自动开/关的逆变器也具有始终的设置。有了它，您可以运行低功耗的夜灯，时钟，传真，接听机和其他微小的负载，而不会失去连续性。在这种情况下，一个好的系统设计师会将逆变器的空闲功率添加到负载计算中（每天24小时）。电力系统的成本将更高，但它将满足现代生活的期望。
幻影负载和空转负载
高科技消费者（美国大多数美国人）都陷入了小工具时，每当插入时会吸引力量。其中一些人完全没有做任何事情。一个示例是具有遥控器的电视。它的电动眼系统在白天和黑夜都在观察您的信号以打开屏幕。即使关闭设备，每个带有外部壁插入变压器的设备即使电源也使用电源。这些小恶魔被称为“幻影负载”，因为它们的力量抽签是出乎意料的，看不见的，并且容易被遗忘。
A similar concern is “idling loads.” These are devices that must be on all the time in order to function when needed. These include smoke detectors, alarm systems, motion detector lights, fax machines, and answering machines. Central heating systems have a transformer in their thermostat circuit that stays on all the time. Cordless (rechargeable) appliances draw power even after their batteries reach a full charge. If in doubt, feel the device. If it’s warm, that indicates wasted energy. How many phantom or idling loads do you have?
这re are several ways to cope with phantom and idling loads:
- 您也许可以避免使用它们（在小型小屋或简单的情况下）。
- 您可以在不需要的情况下最小化它们的使用并断开它们的连接，使用外部开关（例如开关的插件条或容器）。
- You can work around them by modifying certain equipment to shut off completely (central heating thermostat circuits, for example).
- You can use some DC appliances.
- You can pay the additional cost for a large enough power system to handle the extra loads plus the inverter’s idle current.
如果您考虑避免所有幻影和空转负荷，请小心和诚实。您不能总是预期未来的需求或人类行为。
Quality Pays
A good inverter is an industrial quality device that is proven reliable, certified for safety, and can last for decades. A cheap inverter may soon end up in the junk pile, and can even be a fire hazard. Consider your inverter to be a foundation component. Buy a good one that allows for future expansion of your needs.
Your Final Choice
选择逆变器并不是一项艰巨的任务。定义要在哪里使用。定义您将要供电的负载类型（设备）。确定逆变器需要处理的最大功率。力量的质量至关重要吗？尺寸和体重重要吗？逆变器选择表将帮助您确定哪种类型的逆变器最适合您。
Your next step is to learn what inverters are available on the market. Study advertisements and catalogs, or ask your favorite dealer. It is best to listen to professional advice, and to purchase your equipment from a trained and experienced dealer/installer. We hope this article helps you make the right choice.