Automatic Impedance Matching in DC Circuits

The subject of impedance matching is well known in engineering. Whenever a power source containing some finite resistance is expected to supply power to a load, maximum power is obtained when the resistance of the load is made equal to the resistance of the source. This problem becomes serious as the ratings of the power sources become larger. In space applications, thermoelectric generators and solar cell arrays capable of supplying hundreds of watts of usable power are not uncommon. In order to utilize the maximum capabilities of sources such as these, the load impedance and the source impedance should be equal at all times. This paper describes a method whereby impedance matching can be accomplished automatically in a dc circuit, regardless of load or source characteristics.