Abstract: The power supply, well suited for powering a metal halide lamp, includes a rectifier with an AC input and a DC output. A power transformer has its primary winding connected to the DC output and its secondary winding connected to the lamp. A pulse-width-modulated (PWM) controller is coupled to the primary winding for controlling the flow of power therethrough. A smoothing circuit is connected to the lamp for reducing the rate of change of the current flowing through the lamp. Avoiding filtering of the rectifier output, maintaining a constant pulse width of the PWM controller throughout the period of the AC input power and filtering switching-frequency current components from the input to the rectifier provides a sinusoidal input current to the power supply which is substantially in phase with the input voltage. Such supply has a power factor of over 99%.

Abstract: To maintain tension on a fiber tow as it travels between a spool of the tow and a fiber placement head in a computer controlled fiber placement machine, closed tension loop servo control tow velocity feed forward is provided to control spool rotation so as to not only provide closed loop tension control but to also cause rotation in anticipation of expected tow movement such as due to tow payout upon commanded movements of the fiber placement head. Gain scheduling based on spool radius is also provided. Additionally, a compliant roller is provided to reduce tension dips and spikes from disturbances on the tow, and an inner velocity loop is included with the closed tension loop to provide more effective control of tow tension. The servo control is reconfigurable into an open or pseudo-closed loop mode with a safety low power supply to slowly reel-up slack tow after tow threading, for example, and to otherwise maintain low tension on the tow to hold it in the machine while allowing servicing thereof.