How Does A Power Inverter Work? by Jason Miller

People always ask us “exactly how does a power inverter work?” The answer to this question often surprises our customers. Car power inverters work much more simply than mysteriously, and the learning curve required to understand them requires no more than a very basic knowledge of electricity. Essentially, there are two forms of electrical power in the Universe: Direct Current (DC) and Alternating Current (AC). Direct current flows continuously from the positive electrical pole to the negative electrical pole. Alternating current flows back and forth between the two poles. DC current occurs in Nature and batteries, while AC current is man-made and supplies power through the public utility grid that supports human industry and infrastructure. Car batteries presented a problem in the past when people realized they needed to operate traditionally AC-powered devices in their cars but could not do so because of incompatible current requirements. Manufacturers like Vector stepped up to solve this dilemma by working to design car power inverters that would safely and efficiently convert DC to AC. Their successful engineering has resulted in a wide range of compact, rectangular devices that connect to batteries and output the resulting alternating current safely through one or more standard electrical plugs.

Two factors determine how a power inverter works: wave output and wattage output. Wave output describes the physical appearance of electrical signals as they move across an oscilloscope. Square waves appear exactly as their name specifies: like squares on a grid. Pure sine waves, also called true sine waves, appear as visible waves on the screen. Sine wave car power inverters work better than square wave power inverters when uninterrupted power flow is a critical issue. In fact, true sine output is sometimes slightly superior to that of public utility power grids! Because of this, they are also the most expensive devices of their kind on the market. Recent advances in technology have accommodated users on a budget with a hybrid design generally referred to as either a modified square or modified sine wave power inverter. The technical differences that determine how a true sine car power inverter works and how a modified sine power inverter works are too minor to produce any noticeable effects with standard electronics. Only the most high-end equipment requires true sine output, and the cost of these devices may justify the additional investment in pure sine technology to deliver maximum quality and reliable performance.

Another new development that allows car power inverters to work with even more reliability than ever before is the sophisticated Soft Start Technology, branded “SST” by manufacturers such as Vector. SST is the next step in the evolution of how power inverters work. The very first power inverters for cars would only work intermittently during cold engine starts. Because they could not pull enough power from the battery, they would shut down from current underload and require a manual restart. SST resolves this issue by gradually increasing voltage ramp up during engine startup. If the output dips for any reason, SST makes instant adjustments to compensate and will prevent most shutdowns. If in the rare event a shutdown does occur, the newer car power inverters work automatically to restart themselves without distracting the driver from the road.

Red Hill Supply delivers only the best and most reliable power inverters that will work in virtually any situation requiring DC-AC conversion. Learn more about how power inverters work in our Resources section, and browse our online catalogue to obtain the most high end and specialized devices through our simple, convenient online order process.

About the Author

Jason has been in the construction equipment and industrial sales business for over 10 years. He owns and operates Red Hill Supply to better serve the automotive and industrial industries. - Automotive Tools