Abstract: Certain embodiments of the invention may include systems, methods, and apparatus for sensing AC voltage. According to an example embodiment of the invention, a method is provided for sensing AC voltage. The method includes providing a voltage sensing circuit in communication with an AC power source; rectifying an AC signal from the AC power source with rectifier circuitry of the voltage sensing circuit; applying a first voltage to an analog-to-digital (A-to-D) converter circuit, wherein the first voltage is across a second resistive element of a first half cycle voltage divider comprising a first resistive element and the second resistive element and in communication with a positive DC output of the rectifier circuitry; and analyzing the first digital voltage value and the second digital voltage value by a processor to determine a voltage of the AC power source.

Abstract: Certain embodiments of the invention may include systems, methods, and apparatus for sensing AC voltage. According to an example embodiment of the invention, a method is provided for sensing AC voltage. The method includes providing a voltage sensing circuit in communication with an AC power source; rectifying an AC signal from the AC power source with rectifier circuitry of the voltage sensing circuit; applying a first voltage to an analog-to-digital (A-to-D) converter circuit, wherein the first voltage is across a second resistive element of a first half cycle voltage divider comprising a first resistive element and the second resistive element and in communication with a positive DC output of the rectifier circuitry; and analyzing the first digital voltage value and the second digital voltage value by a processor to determine a voltage of the AC power source.

Abstract: A scheme for measuring the frequency of an alternating current signal provides for the development of first and second values which are respectively representative of the time the alternating current signal exist in alternate half cycles; e.g., the period of a half cycle. The most recently developed of the first and second values is retained and continuously compared with the other value which is presently being developed to thus provide an output signal representative of the greater thereof. This output signal is indicative of the period and, hence by its reciprocal, a measure of the apparent instantaneous frequency of the alternating current signal.

Abstract: A scheme for determining the stator resistance of an alternating current motor includes the determination of the actual flux of the motor through the sensing of motor voltage and motor current. The motor current is also utilized to develop a signal representing the anticipated motor flux which will result from that current. These two flux signals are combined to develop a flux error signal, the polarity of which is determined by whether the motor is in the motoring or regenerative mode of operation, which in turn is integrated to give the signal representing the motor stator resistance. Additionally, when the motor changes mode of operation, there is provided a step function which assures a motor stator resistance value being used which insures control stability.