| 摘要 |
<p>An exercise system including an exercise device having a user actuatable pedal mechanism (16) coupled to a permanent magnet, DC motor operated as a generator (18) and a load control arrangement for controlling a braking effect exerted by the DC motor on the pedal mechanism (16). The output of the DC motor (18) is connected to a power dissipation circuit including plurality of power MOSFETs (42). The system can be operated in a constant power or a constant force mode. In the constant power mode, the load control monitors the output of the DC generator (18) and compares it with a selected power level and in response to detected errors between the signals, adjusts the conductivity of the power MOSFETs (42) to maintain the power output independent of actuation speed. Current flow through the power MOSFETs (42) is monitored and the relative conductivity between the MOSFETs is adjusted in order to maintain substantially equal current flows through each MOSFET (42). Power for the electronics is obtained from the DC generator (18) using a two-stage power regulation circuit (102) in which the second stage includes positive and negative regulators (302) and the first stage includes a means for limiting the input voltage to the regulators to a predetermined maximum. <IMAGE></p> |
