Damping of voltage-controlled brushless motors for electric power steering systems

An electric power steering system comprising a steering input member, a voltage-controlled electric assist motor coupled to the input member, and an electronic controller in signal communication with the assist motor;

• the electronic controller comprising:
• a first signal input or receiving a first signal indicative of a torque command to the assist motor;
• a second signal input for receiving a second signal indicative of an angular velocity of the assist motor;
• an assist-dependent damping function responsive to the first and second signal;
• and
• a signal output for providing a voltage signal in communication with the voltage-controlled electric assist motor;
• a phase advance function in signal communication with the assist motor, wherein the phase advance function in responsive to at least one of the first and second signal;
• and
• wherein the voltage signal is responsive to the assist-dependent damping function.

A method for controlling an electric power steering system comprising a steering input member, a voltage-controlled electric assist motor coupled to the input member, and an electronic controller in signal communication with the assist motor;

• the method comprising:
• receiving a first signal indicative of a torque command to the assist motor;
• receiving a second signal indicative of an angular velocity of the assist motor;
• computing an assist-dependent damping function responsive to the first and second signals;
• and
• adapting an output voltage in signal communication with the voltage-controlled electric assist motor in response to the assist-dependent damping function.

A method for controlling an electric power steering system comprising a steering input member, a voltage-controlled electric assist motor coupled to the input member, and an electronic controller in signal communication with the assist motor;

• the method comprising:
• receiving a first signal indicative of a torque command to the assist motor;
• receiving a second signal indicative of an angular velocity of the assist motor;
• computing an assist-dependent damping function responsive to the first and second signals;
• adapting an output voltage in signal communication with the voltage-controlled electric assist motor in response to the assist-dependent damping function;
• adding the first signal to the computed assist-dependent damping function;
• and
• limiting the added assist-dependent damping function.

A method for controlling an electric power steering system comprising a steering input member, a voltage-controlled electric assist motor coupled to the input member, and an electronic controller in signal communication with the assist motor;

• the method comprising:
• receiving a first signal indicative of a torque command to the assist motor;
• receiving a second signal indicative of an angular velocity of the assist motor;
• computing an assist-dependent damping function responsive to the first and second signal;
• adapting an output voltage in signal communication with the voltage-controlled electric assist motor in response to the assist-dependent damping function;
• limiting the computed assist-dependent damping function;
• and
• adding the first signal to limited assist-dependent damping function.

A method for controlling an electric power steering system comprising a steering input member, a voltage-controlled electric assist motor coupled to the input member, a torque sensor coupled to the steering input member, and an electronic controller in signal communication with the assist motor;

• the method comprising:
• receiving a first signal indicative of a torque command to the assist motor;
• receiving a second signal indicative of an angular velocity of the assist motor;
• computing an assist-dependent damping function responsive to the first and second signals;
• adapting an output voltage in signal communication with the voltage-controlled electric assist motor in response to the assist-dependent damping function;
• receiving a third signal indicative of a vehicular road speed;
• computing a first input-dependent damping function responsive to the third signal;
• adapting the output voltage in response to the fist input-dependent damping function;
• receiving a fourth signal indicative of a driver torque input upon the steering input member;
• computing a second input-dependent damping function responsive to the driver torque input;
• and
• adapting the output voltage in response to the second input-dependent damping function.

An electric power steering, system for a vehicle comprising a steering input member, a voltage-controlled electric assist motor coupled to the input member, and an electronic controller in signal communication with the assist motor;

• the electronic controller comprising:
• means for receiving a first signal indicative of a torque command to the assist motor;
• means for receiving a second signal indicative of an angular velocity of the assist motor;
• means for computing an assist-dependent damping function responsive to the first and second signals;
• means for receiving a third signal indicative of a road speed of the vehicle;
• means for receiving a fourth signal indicative of a driver torque on the input member;
• means for computing an input-dependent damping function responsive to the third and fourth signals;
• and
• means for producing an output voltage in signal communication with the assist motor that is responsive to at least one of the assist-dependent damping function and the input-dependent damping function.