System and method for variable drive pump control

A method for controlling speed of a variable drive system driven AC electric motor connected to a cyclic load, the method comprising the step of:

• converting an AC electric signal to DC electric signal deriving a set of DC electric characteristic signals from the DC electrical signal;
• generating first and second sets of control signals in response to the set of DC electrical characteristic signals store DC current signal and a set point parameter;
• and
• inverting the DC electric signal in response to the first and second sets of control signals to generate a set of drive signals to modify the speed of the AC electric motor in response to indicated changes in the motor attribute to correspond to the set point parameter.

A method for controlling speed of an AC electric motor connected to a cyclic load, the method comprising the steps of:

• converting with a signal conversion circuit an AC electric signal to a DC electric signal;
• deriving with a signal measurement circuit a set of characteristic signals from the DC electric signal;
• generating with a control circuit first and second sets of control signals in response to the set of DC electric characteristic signals and a set of operational parameters, a voltage-frequency profile, and a set point parameter;
• and
• inverting with a signal inversion circuit the DC electric signal in response to the first and second sets of control signals to generate a set of drive signals to modify the speed of the AC electric motor.

A variable drive system for controlling speed of an AC electric motor connected to a cyclic load, the system comprising:

• a signal conversion circuit electrically connected to an alternating current source to convert a poly-phase AC power input from the alternating current source to a source of DC power on a DC bus;
• a user interface circuit to receive a selected set of operational parameters, a selected voltage-frequency profile, and a selected torque set point;
• a signal measurement circuit communicatively coupled to the control circuit for sensing DC current and voltage across the DC bus to provide a set of DC electric characteristic signals;
• a control circuit responsive to the selected set of operational parameters, the selected voltage-frequency profile, the torque set point, and the set of DC electric characteristic signals, the control circuit generating a set of control signals to modify the speed of the AC electric motor according to a selected motor speed characteristic for different portions of a cycle of the cyclic load;
• and
• a signal inversion circuit electrically coupled to the DC bus and the AC electric motor to generate a set of variable frequency and variable voltage motor drive signals responsive to the set of control signals.

A system for controlling the speed of an AC electric motor connected to a cyclical load, the system comprising:

• a signal conversion circuit to convert an AC electric signal to a DC electric signal;
• a signal measurement circuit to derive from the DC electrical signal, a DC electric characteristic signal corresponding to a motor attribute;
• a control circuit responsive to the DC electric characteristic signal and target torque range, the control circuit deriving a speed reference signal and using the speed reference signal to derive control signals;
• and
• a signal inversion circuit to generate drive signals in accordance with the control signals that modify the speed of the AC electric motor in response to indicated changes in the motor attribute to correspond to the set point parameter wherein the control signals are representative of a determined adjustment to a dimension of the drive signals generated by the signal inversion circuit to selectively drive the motor.

A method for controlling speed of a variable drive system driven AC electric motor connected to a cyclic loads the method comprising the steps of:

• converting an AC electric signal to a DC electric signal;
• deriving a set of DC electric characteristic signals from the DC electrical signal, wherein the steps of deriving the set includes the step of sensing the DC electric signal at a selected sampling frequency having a time period to produce the set of DC electric characteristic signals which includes a DC current signal and a DC voltage signal;
• and
• generating first and second sets of control signals in response to the set of DC electric characteristic signals and a set point parameter;
• wherein the steps of generating the first and second sets includes the steps:
• deriving a first reference signal from the set operational parameters;
• storing the DC current signal magnitude and deriving a desired parameter signal from the sensed DC voltage signal and the voltage-frequency profile in each of the time period of the selected sampling frequency;
• and
• inverting the DC electrical signal in response to the first and second sets of control signals to generate a set of drive signals to modify the speed of the AC electric motor in response to indicated changes in the motor attribute to correspond to the set point parameter.

A method for controlling speed of a variable drive system driven AC electric motor connected to a cyclic load, the method comprising the steps of:

• converting an AC electric signal to DC electric signal;
• deriving a set of DC electric characteristic signals from the DC electric signal;
• generating first and second sets of control signals in response to the set of DC electric characteristic signals and a second point parameter;
• wherein the step of generating first and second sets of control signals includes the step of receiving the set of operational parameters, the voltage-frequency profile, and the set point parameter;
• and
• inverting the DC electric signal in response to the first and second sets of control signals to generate a set of drive signals to modify the speed of the AC electric motor in response to indicated changes in the motor attribute to correspond to the set point parameter.

A method of controlling speed of a variable drive system driven AC electric motor connected to a cyclic load, the method comprising the steps of:

• converting an AC electric signal to a DC electric signal;
• deriving a set of DC electric characteristic signals from the DC electric signal;
• generating first and second sets of control signals in response to the set of DC electric characteristic signals and a set point parameter wherein the step of generating first and second sets of control signals includes the step of pre-loading the set of operation parameters, the voltage-frequency profile, and the set point parameter;
• and
• inverting the DC electric signal in response to the first and second sets of control signals to generate a set of drive signals to modify the speed of the AC electric motor in response to indicated changes in the motor attribute to correspond to the set point parameter.