Synthesis of improved zero-impedance converter

DETAILED DESCRIPTION An improved zero-impedance converter embodying the principles of the invention applied to synthesizing electric motor drive systems of infinite disturbance rejection ratio and zero-dynamics/instantaneous response is shown in FIG.
1.
In FIG.
1, it is assumed that input voltage V.
sub.
in (not illustrated) applied to a pulse width modulated )PWM) power stage within block 111 is constant so that a gain constant A characteristics transfer function of the PWM control and power stage 111.
The power stage within block 111 is implemented appropriately for the kind of motor which it powers; for example, it may be a dc-to-dc converter for dc motors or dc-to-ac converter for ac motors or a PWM power stage employed for driving step motors (in this latter case some additional circuits may be used without affecting the embodiment ).
The PWM control portion within block 111 then performs appropriate control function.
What is of interest here is that the overall voltage gain of the control and power PWM stage 111 is a constant A.
Thus, a signal applied to lead 110 is voltage-amplified A times to appear as voltage .
DELTA.
V(s) on lead 107 with an associated power/current .
DELTA.
I(s) supplied by the input voltage source V.
sub.
in.
In FIG.
1, portion between boundaries 140-140a and 141-141a denotes improved zero-impedance converter; the remaining portion illustrates an application of the improved zero-impedance converter in synthesizing an electric motor drive system of infinite disturbance rejection ratio and zero-dynamics/instantaneous response.
The improved zero-impedance converter employs a positive current feedback loop and a negative voltage feedback loop.
The positive current feedback loop incorporates a current feedback circuit 129 whose transfer function is H(s).
Either analog or digital (microprocessor) realization of the current feedback circuit 129 may be done.
The negative voltage feedback loop incorporates a voltage feedback circuit 106 whose transfer function is a constant K