Techniques For Limiting Electrical Current Provided To A Motor In An Electric Power Steering System

The controller as set forth in any preceding claim further being configured to:

• input the second filtered estimated temperature of the motor into an electrical current limiting factor lookup table;
• determine an electrical current limiting factor using the electrical current limiting factor lookup table;
• and
• set the limit on electrical current provided to the motor by applying the electrical current limiting factor to a preset maximum electrical current allowed to the motor.

A controller for limiting electrical current provided to a motor for an electric power steering system, said controller being configured to:

• estimate temperatures of the motor over time;
• filter the estimated temperatures of the motor using a filter;
• adjust the filter in response to changes in the estimated temperatures of the motor over time;
• and
• limit electrical current provided to the motor over time based on the adjusted filter.

A method for limiting electrical current provided to a motor for an electric power steering system, said method comprising the steps of:

• determining a first estimated temperature of the motor for a first time step;
• filtering the first estimated temperature of the motor with a filter to produce a first filtered estimated temperature of the motor;
• determining a second estimated temperature of the motor for a second time step subsequent to the first time step;
• comparing the first filtered estimated temperature of the motor with the second estimated temperature of the motor to determine whether the motor is heating or cooling;
• adjusting the filter in response to determining whether the motor is heating or cooling;
• filtering the second estimated temperature of the motor with the adjusted filter to produce a second filtered estimated temperature of the motor;
• and
• setting a limit on electrical current provided to the motor using the second filtered estimated temperature of the motor.

A method for limiting electrical current provided to a motor for an electric power steering system, said method comprising the steps of:

• estimating temperatures of the motor over time;
• filtering the estimated temperatures of the motor using a filter;
• adjusting the filter in response to changes in the estimated temperatures of the motor over time;
• and
• limiting electrical current provided to the motor over time based on the adjusted filter.

An electric power steering unit comprising:

• a motor;
• at least one temperature sensor being configured to measure an ambient temperature relating to the motor;
• at least one current sensor being configured to measure an electrical current of the motor;
• and
• a controller coupled to the motor, the at least one temperature sensor, and the at least one current sensor, said controller being configured to:
• receive the ambient temperature measurement relating to the motor from the at least one temperature sensor;
• receive the electrical current measurement of the motor from the at least one current sensor;
• estimate temperatures of the motor over time using the ambient temperature measurement relating to the motor and the electrical current measurement of the motor;
• filter the estimated temperatures of the motor using a filter;
• adjust the filter in response to changes in the estimated temperatures of the motor over time;
• and
• limit electrical current provided to the motor over time based on the adjusted filter.

A controller for limiting electrical current provided to a motor for an electric power steering system, said controller comprising:

• a motor temperature estimating portion comprising:
• a first input being configured to receive an ambient temperature measurement relating to the motor;
• a second input being configured to receive an electrical current measurement of the motor;
• a first combiner coupled to the first input and the second input and being configured to combine the ambient temperature measurement relating to the motor and the electrical current measurement of the motor for determining an estimated temperature of the motor;
• a temperature filtering portion comprising a filter coupled to the first combiner and the first input and being configured to receive and to filter the estimated temperature of the motor;
• and
• a first output coupled to the temperature filtering portion and being configured to output a filtered estimated temperature of the motor;
• a motor current control portion coupled to the motor temperature estimating portion and configured to limit electrical current provided to the motor in response to the filtered estimated temperature of the motor.