Measuring device and method for direct current supply output impedance

The invention discloses a measuring device and method for direct current supply output impedance. The measured direct current supply output impedance is defined at a specific operating point and a specific test cross section, the presented equivalent impedance is seen in the direction of the test cross section facing a power supply, and system deviation in the measuring process, caused by load input impedance, is avoided. The measuring device comprises a test frequency point voltage phasor extraction module, a test frequency point current phasor extraction module, a low-current excitation load module, a sweep frequency phasor analysis module and a control computer, wherein the test frequency point voltage phasor extraction module and the test frequency point current phasor extraction module are respectively connected with a voltage input end and a current input end of the sweep frequency phasor analysis module; the signal output end of the sweep frequency phasor analysis module is connected with the low-current excitation load module; and the sweep frequency phasor analysis module is further connected with the control computer.