Patent ID: 8672733
Filing Date: 2014-03-18
Classification: F04D,F24F,Y02B

Abstract:
1. An air-handling unit for ventilating an at-least partially enclosed space, the air-handling unit comprising: a first fan configured to blow air through the air-handling unit to the space; an electric first motor connected to and configured to turn the first fan; a drive unit powering the electric first motor wherein the drive unit produces a variable frequency AC output or a variable voltage DC output to the electric first motor; a current sensor measuring electrical current into the drive unit; and a control system configured to use an input to control and vary speed of the electric first motor by controlling the drive unit, wherein the input is a representation of the electrical current into the drive unit obtained from the current sensor, and wherein the control system is configured to vary the speed of the electric first motor to obtain a substantially fixed airflow rate through the air-handling unit over a range of varying amount of airflow restriction, and wherein the control system includes instructions to repeatedly calculate a preliminary new speed, and calculation of the preliminary new speed includes multiplying a speed of a present input setting times a target speed, and dividing by a speed at which a present motor current would be predicted to occur in a nominal ventilation system, wherein the target speed is a speed at which a target airflow rate would be predicted to occur in the nominal ventilation system in which a nominal airflow restriction would be encountered at a nominal design airflow rate and the present motor current is a present electrical current into the drive unit measured using the current sensor.