A systematic approach to the design of VSC systems has been given. Using the hyperstability theory, the stability of the global system has been established and the existence of the sliding modes. Simple control laws can be used and high speed of response is obtainable by forcing the system with maximum allowable signals, e.g. by means of relay or unit-vector laws. A simple way to gain confidence with synthesis is an extensive and accurate simulation before implementing the control system. To this end it is very useful to realise effective CAD packages for variable structure control system design.