The c l o s e d -l m p c o n v e r t e r -c o n t r o l l e d d c d r i v e is modelled a s a t h i r d o r d e r non-linear system. Lyapunov's Second Method is a p p l i e d to s t u d y t h e s t a b i l i t y o f t h e system. From t h e c o n d i t i o n s f o r s t a b i l i t y , o b t a i n e d from t h e Lyapunov f u n c t i o n d e r i v e d using t h e I n t e g r a l Method o f Chin [S], a s t a b i l i t y boundary is o b t a i n e d i n t h e parameter plane. F u r t h e r , s u i t a b l e ranges o f c o n t r o l l e r parameters a r e o b t a i n e d from t h e s e c o n d i t i o n s f o r s t a b i l i t y . An example is s t u d i e d .