Converter by stored switching pattern

An apparatus for digitally producing control signals for operating a converter to produce step-like approximations of predetermined waveforms, comprising:

• memory means for storing digital representations of the switching patterns for operating said converter to produce a predetermined segment of each one of a plurality of waveforms, respectively, said memory means being operable for repetitively outputting either at least a selected one or concurrently one per phase, of said switching patterns, each one of said waveforms being divided into equal angled zones, a respective predetermined segment when oriented in phase and made of appropriate polarity, substantially approximating the portion of its associated waveform within any of the zones of this waveform;
• and
• decoding means receptive of said selected switching pattern(s) from said memory means, for gating the digital representations of the switching pattern(s) onto particular ones of a plurality of control lines, for operating said converter to produce said segment(s) of the desired waveform(s) in a given zone, and with the appropriate phase and polarity, in an iterative manner, for producing an entire cycle of either one of a desired waveform or polyphase related waveforms.

Apparatus for deriving an N-phase periodic waveform from a DC power source, where N is a positive integer, comprising a switching converter having N branches responsive to the DC source, branch k including switch means and an output tap on which is derived the waveform of phase k, where k is selectively every one of N, means for controlling the activation of the switch means of branch k, said controlling means including a memory for storing a control pattern for the switch means of branch k for a portion of one period of the waveform, the duration of each portion being related to N, each portion having a duration equal to the same integral subdivision of the period, each portion being subdivided into plural equal length intervals, means for cycling the memory so that during each interval the switch means of branch k is activated to a combination of conditions to control the amplitude of the voltage applied by the source to the tap, the pattern controlling the combination of conditions over all of the intervals forming a portion, the memory being activated by the means for cycling to repeat the control pattern with different phases during successive portions of the same cycle of the waveform.

Apparatus for controlling a switching converter for deriving an N-phase periodic waveform from a DC power source, where N is a positive integer, said converter having N branches responsive to the DC source, branch k including switch means and an output tap on which is derived the waveform of phase k, where k is selectively every one of N, the controlling apparatus comprising:

• means for controlling the activation of the switch means of branch k, said controlling means including a memory for storing a control pattern for the switch means of branch k for a portion of one period of the waveform, the duration of each portion being related to N, each portion having a duration equal to the same integral subdivision of the period, each portion being subdivided into plural equal length intervals, means for cycling the memory so that during each interval the switch means of branch k is activated to a combination of conditions to control the amplitude of the voltage applied by the source to the tap, the pattern controlling the combination of conditions over all of the intervals forming a portion, the memory being activated by the means for cycling to repeat the control pattern with different phases during successive portions of the same cycle of the waveform.