Patent ID: 6519538
Filing Date: 2003-02-11
Classification: H02M

Abstract:
A method for determining relationships among loop gain, open loop output impedance, and load impedance as a function of frequency for a power converter apparatus to aid in predicting stability of said converter apparatus under various operating conditions; said converter apparatus having an open-loop output impedance and providing an output signal to an output locus; the method comprising the steps of:(a) vectorally measuring a first loop gain of said converter apparatus as a function of frequency with a first load impedance connected with said output locus, to record phase and gain of said first loop gain for a plurality of frequencies; (b) vectorally measuring open loop output impedance as a function of frequency of said converter apparatus, to record phase and gain of said open loop output impedance for a plurality of frequencies; (c) vectorally measuring said first load impedance as a function of frequency of said converter apparatus, to record phase and gain of said first load impedance for a plurality of frequencies; (d) calculating a first load distribution factor using said first load impedance and said open-loop output impedance; said calculating being effected in vectoral manner to record magnitude and phase of said first load distribution factor for a plurality of frequencies; (e) selecting a second impedance load with an output voltage sense point, said second impedance load being representable by a network of at least one resistor and at least one capacitor or inductor, said output voltage sense point being situated at a selected node of said network; (f) calculating a second load distribution factor for said second impedance load; using said open-loop output impedance and said second impedance load; said calculating being effected in vectoral manner to record magnitude and phase of said impedance-loop load distribution factor for a plurality of frequency values; and (g) calculating a second loop gain using said first loop g, said first load distribution factor and said second load distribution factor; said calculating being effected in vectoral manner to record magnitude and phase of said impedance-load gain for a plurality of frequency values.