Torque controller in an electric motor

A controller for an electric motor, comprising:

• means for switching a voltage within power electronics at a first fundamental frequency to drive said motor
• means for providing a high frequency pulse width modulated component within said first fundamental frequency, said high frequency component having a frequency greater than said fundamental frequency;
• means for detecting a rotation speed of said motor;
• and,
• means responsive to said detecting means for altering said frequency of said high frequency pulse width modulated component from a first switching frequency to a second switching frequency to control efficiency in said power electronics, said altering means further comprising means for switching said high frequency component means to a third switching frequency when said rotation speed of said motor increases to a high rotation speed, wherein said third switching frequency is higher than said second switching frequency.

A method of generating a smooth, rated torque at a slow rotation speed of a motor, said motor including a rotor, comprising:

• passing a first switched pulse width modulated voltage to power electronics driving said motor at a first switching frequency when said rotor is rotating at a rotation speed above said slow rotation speed;
• passing a second switched pulse width modulated voltage to said power electronics at a second switching frequency when said rotor is rotating at a rotation speed at or below said slow rotation speed, said second switching frequency being less than said first switching frequency;
• wherein a single specified torque of said motor is produced at both said first switching frequency and said second switching frequency;
• and
• further comprising determining said second switching frequency as a linear relationship to said first switching frequency given by the equation,
• f
• 2
• =
• k
• *
• v
• cur
• +
• b
• k
• =
• f
• max
• -
• f
• min
• v
• max
• -
• v
• min
• wherein f2=said second switching frequency;
• vcur=rotation speed of said rotor;
• b=a linear offset frequency equal to a minimum switching frequency;
• fmax=a maximum switching frequency;
• fmin=a minimum switching frequency;
• vmax=a maximum rotation speed for said rotor;
• and vmin=a minimum rotation speed of said rotor.

A controller for an electric motor, comprising:

• a switching converter configured to alter a drive signal to power electronics from a first pulse width modulated switching frequency to a second pulse width modulated switching frequency;
• and
• a position sensor configured to detect a rotation speed of said motor,
• wherein said switching converter switches said frequencies when said position sensor detects a rotation speed of said motor equivalent to a predetermined rotation speed, said switching converter being configured to alter said drive signal at a third switching frequency when said rotation speed of said motor increases to a predetermined fast rotation speed, said third switching frequency being higher than said second switching frequency.

A method of controlling the efficiency of power electronics driving a motor, comprising:

• switching a voltage within said power electronics at a first fundamental frequency;
• providing a high frequency pulse width modulated component within said first fundamental frequency, said high frequency component have a frequency greater than said fundamental frequency;
• detecting a rotation speed of said motor;
• and
• responsive to said rotation speed, altering said frequency of said high frequency pulse width modulated component from a first switching frequency to a second switching frequency to control efficiency in said power electronics, said altering said frequency of said high frequency pulse width modulated component from a first switching frequency to a second switching frequency further comprises altering said frequency of said high frequency pulse width modulated component to a third switching frequency when said rotation speed of said motor increases to a high rotation speed, and wherein said third switching frequency is higher than said second switching frequency.

A method of controlling the efficiency of power electronics driving a motor, comprising:

• switching a voltage within said power electronics at a first fundamental frequency;
• providing a high frequency pulse width modulated component within said first fundamental frequency, said high frequency component have a frequency greater than said fundamental frequency;
• detecting a rotation speed of said motor;
• and
• responsive to said rotation speed, altering said frequency of said high frequency pulse width modulated component from a first switching frequency to a second switching frequency to control efficiency in said power electronics, said altering said frequency of said high frequency pulse width modulated component from a first switching frequency to a second switching frequency being dependant upon a torque requirement of said motor.

A method of generating a smooth, rated torque at a slow rotation speed of a motor, said motor including a rotor, comprising:

• passing a first switched pulse width modulated voltage to power electronics driving said motor at a first switching frequency when said rotor is rotating at a rotation speed above said slow rotation speed;
• passing a second switched pulse width modulated voltage to said power electronics at a second switching frequency when said rotor is rotating at a rotation speed at or below said slow rotation speed, said second switching frequency being less than said first switching frequency, a single specified torque of said motor being produced at both said first switching frequency and said second switching frequency;
• and
• switching said current at a third switching frequency when said rotation speed of said rotor increases to a high rotation speed, wherein said third switching frequency is higher than said second switching frequency.