Electric power steering apparatus

An electric power steering apparatus, comprising:

• a multi-phase motor that assists steering effort of a driver;
• driving means provided with an upper switching element that connects or disconnects the winding of each phase of said multi-phase motor and a power supply, and a lower switching element that connects or disconnects the winding of each phase of said multi-phase motor and grounding;
• and
• a logic circuit that determines ON/OFF of said upper switching element and said lower switching element;
• first and second controlling means for controlling said driving means via said logic circuit,
• wherein said logic circuit determines ON/OFF of said upper switching element and said lower switching element so that the power to the winding of said each phase is stopped according to an instruction of either said first control means or said second control means, and
• wherein said first controlling means and said second controlling means are connected in such a way as to exchange predetermined data, monitor errors of each other based on the exchanged data and control said logic circuit in such a way as to interrupt the power to said multi-phase motor in the event of an error in said first or second controlling means.