Fail-safe system for electric power steering in vehicles

A system, comprising:

• a) a vehicle;
• b) an electric motor which drives a power steering system in the vehicle, and which
• i) contains a first and a second set of stator coils, wherein the current in each set is independent of current in the other;
• ii) receives power for the first set of stator coils from a first inverter, and receives power for the second set of stator coils from a second inverter;
• c) a first relay which controls current delivered to the first inverter, and
• d) a second relay which controls current delivered to the second inverter.

A method of operating a motor which is powered by an inverter in a vehicle which contains an engine, comprising the steps of:

• a) maintaining a relay which
• i) terminates current to the inverter when in an open state, and
• ii) delivers current to the inverter when in a closed state;
• b) ascertaining whether battery polarity is correct and
• i) if not correct, maintaining the relay in the open state;
• and
• ii) if correct, closing the relay;
• and
• d) monitoring the inverter, the motor, or both and if a predetermined type of fault occurs, opening the relay.

For an electric motor which drives a power steering system in a vehicle which contains a primary storage battery, a method comprising the steps of:

• a) maintaining a first and a second set of stator coils in the motor, wherein the current in each set is independent of current in the other;
• b) maintaining a first inverter which delivers current to the first set of stator coils;
• c) maintaining a second inverter which delivers current to the second set of stator coils;
• d) maintaining a first relay which controls current delivered to the first inverter, and
• e) maintaining a second relay which controls current delivered to the second inverter.

A method of operating a motor in a vehicle which contains a primary storage battery, comprising:

• a) maintaining two independent sets of stator coils in the motor;
• b) maintaining two inverters, one for each set of stator coils;
• c) ascertaining whether the primary storage battery is installed in the vehicle with proper polarity and, if not, blocking current to both inverters;
• d) ascertaining whether a fault exists in a set of stator coils or its associated inverter and, if so, blocking current to the stator coils or inverter containing the fault.

A method, comprising:

• a) maintaining a relay in series with an inverter which powers a motor in a vehicle;
• b) if a primary storage battery in the vehicle is installed with incorrect polarity, opening the relay;
• and
• c) if a predetermined fault is detected in the motor or inverter, opening the relay.