| 摘要 |
<p>A method and system for controlling the output current (12) of a large, low-voltage, DC power supply which includes at least one transformer primary (10) by controllably switching an AC power line voltage (22) to the primary as a function of actual and desired output currents (12). SCRs (18) are used to switch, using phase control, the AC primary voltage (22) to the transformer(s) (10) of the power supply in order to control the output current (12). Given the incoming power line voltage (22), the current value from the previous power line cycle and the desired current for the present cycle, the function is used to find the SCR firing angle to attain the desired output current (12) in the present power line cycle. Actual measurements of output current (12) and power line voltage (22) are used to modify the function to reflect changes in power line voltage (22) and/or circuit impedance to obtain a modified function. Preferably, instantaneous changes in power line voltage (22) are measured and used to change the input variables to the function in order to provide instantaneous corrections for power line voltage changes. Diagnostic information concerning the operation of the DC power supply is determined from the modified function.</p> |
