Extended speed range operation of permanent magnet brushless machines using optimal phase angle control in the voltage mode operation

A voltage mode control method for reducing torque ripple in an electric motor, comprising:

• providing a sinusoidally excited permanent magnet motor without current sensors;
• determining a known maximum allowed value from a first set of parameters with each parameter having said known maximum value;
• reading a second set of parameters;
• computing a first derived angle using said first set of parameters and said second set of parameters;
• computing amplitude and a second derived angle of phase voltage vector using said first derived angle and a third set of parameters;
• and
• outputting a set of derived command voltages for controlling a power circuit whereby the said power circuit can achieve required torque levels with lower currents for power switches.

A storage medium encoded with machine-readable computer program code for extending speed range operation from a sinusoidally excited permanent magnet motor, said storage medium including instructions for causing a computer to implement a method comprising:

• determining a known maximum allowed value from a first set of parameters with each parameter having said known maximum value;
• reading a second set of parameters;
• computing a first derived angle using said first set of parameters and said second set of parameters;
• computing amplitude and a second derived angle of phase voltage vector using said first derived angle and a third set of parameters;
• and
• outputting a set of derived command voltages for controlling a power circuit whereby the said power circuit can achieve required torque levels with lower currents for power switches.

A method of reducing torque ripple in an electric motor, comprising:

• providing a sinusoidally excited permanent magnet electric motor without current sensors;
• providing a controller for controller said electric motor;
• said controller having a storage medium encoded with machine-readable computer program code, said code comprising instructions for causing a computer to implement a procedure comprising:
• determining a known maximum allowed value from a first set of parameters with each parameter having said known maximum value;
• reading a second set of parameters;
• computing a first derived angle using said first set of parameters and said second set of parameters;
• computing amplitude and a second derived angle of phase voltage vector using said first derived angle and a third set of parameters;
• and
• outputting a set of derived command voltages for controlling a power circuit whereby the said power circuit can achieve required torque levels with lower currents for power switches.