What is an Inverter MIG Welder?
An Inverter MIG welder is an electronic piece of equipment that converts AC Input to a stable DC Output. A wire feed motor with a continuous welding wire is connected to this output via a welding torch, to enable consistent blowing of the wire when shorted to the workpiece.
HOW DOES AN INVERTER WELDER WORK?
Inverters use a system of hi-speed switches to facilitate voltage regulation.
The inverter works by increasing the frequency of the power supply from 50-60Hz AC (High Volts Low Amps) to 10000 - 20000 Hz AC (Low Volts High Amps). It then pushes this Low Volts High Amps through a small transformer and finally through another rectifier to convert back to welding DC.
Think of an electrical sinusoidal wave as a heat pulse, conventional transformer MIGs use 50Hz (pulses) per second, therefore the transformer needs to be larger in size compared to an inverter transformer receiving 20000Hz per second. This high frequency enables smaller transformer windings compared to normal welders.
The high frequency switching in the inverter module can be done by either MOSFETS (metal-oxide semiconductor field effect transistors) or preferably IGBTs (insulated-gate bipolar transistor).
Low-voltage, low-current and high switching frequencies favor MOSFETs.
High-voltage, high-current and low switching frequencies, favour IGBTs.
This makes IGBTs particularly suitable for welding equipment, and more importantly they are less vulnerable to power fluctuations. Remember, both MOSFETS and IGBTs are high speed switches, turning on, and off up to 20000 times a second, so it doesn't take much fluctuation to make them unstable. Its just IGBTs can handle it better.
WHAT ARE THE ADVANTAGES OF AN INVERTER WELDER?
Inverters of many advantages over there transformer rivals, namely:
They use less electricity.
Quality Inverters have an efficiency rating of 80-90% compared to conventional transformer welders which are 50% or less. This is due to the conventional machines having larger transformers with higher internal resistances and greater heat dissipation. High frequency AC pushed into a smaller transformer dramatically raises efficiency, which lowers input current draw, reduces circuit breaker size requirements and lowers the electricity used.
This is where inverters really win, because they are electronic, programmes can be inputted at the factory by qualified welders, enabling fast accurate parameters for any process application. This is where the term Synergic comes from as we explain in our post What does Synergic Mean On a Welder?Precise settings
Transformer machines can also have synergic settings though but they tend to be a lot less than available in and inverter machine.
The voltage steps are more precise between settings. A transformer machine can have 3-5v steps between each setting and some like the parweld will only have 8 settings. An Inverter meanwhile can have infinite settings all available in 0.1v steps.
Inverters, due to the electronics enclosed and the ability to programme them means they can perform many different processes MIG,MMA and TIG functions more easily. Functions such as hot start ,slope and TIG mode can all be incorporated into the one system.
ARE INVERTER MIG WELDERS BETTER?
Yes they are, for many of the reason explained above, the only downside used to be price but as the cost of electronics comes down inverter become more affordable.
ARE CHEAP INVERTERS WORTH IT?
Inverters are complicated machines and some of the units from China and India when we open them up can be very scary. Unlike standard European or American Inverters the quality can be a little hit and miss, you pays your money and you takes your choice. Some Chinese manufacturers are now using European IGBTs in manufacture to increase reliability and this is a good thing, but it doesn't mean its good.
As with anything electronic good maintenance and technical support are a must when purchasing.
CAN INVERTER MIG WELDERS WORK ON A GENERATOR?
The answer is YES but ensure the welder has PFC Power Factor Correction and the generator is at least a 1/3 higher in wattage supply for the welder.