Digital pulse generator for controlled thyristor switches and motor drive embodying the same
First Claim
1. In a digital pulse generator for gating a plurality of thyristor switches sequentially for conduction under a three-phase AC power supply by gate pulses under a predetermined firing angle α
- , including phase-locked loop means coupled to said AC power supply for deriving an instantaneous electrical angle representative signal;
the combination of;
computer means responsive to said predetermined firing angle α
for calculating α
=K. (60)+α
'"'"', where K is an integer number of 60 electrical angles and α
'"'"' is a residual angle in excess of such K. (60) number of electrical angles in said predetermined firing angle α
, and for deriving a first control signal representative of said integer number K and for deriving a second control signal representative of said residual angle α
'"'"';
first timer means responsive to said instantaneous electrical angle representative signal for repeatedly establishing a running count through a sixty degrees time interval, each such time interval corresponding to a thyristor switch in the sequence of conduction thereof;
counter means responsive to said first timer means for counting successive said time intervals;
distributor means responsive to said counter means for selecting said thyristor switches sequentially and accordingly;
second timer means responsive to said running count and to said second control signal for enabling said distributor means to gate a selected thyristor switch;
with said distributor means being controlled by said first control signal to shift the order of gating in said sequence by an amount in relation to said integer number.
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Accused Products
Abstract
In a microcomputer-based multi-function thyristor-controlled AC induction motor drive, the microcomputer effectuates the several control functions of the motor drive during respective time intervals corresponding to the sequence of firing of the thyristors, and upon each new time interval, depending upon the required delay angle, firing is effected as a function of a residual angle in terms of a multiple of said time intervals, and the firing sequence is shifted by an amount of time intervals in relation to the integer number of such time intervals within such delay angle. As a result, firing of the thyristor is performed by the microcomputer without impeding control function determination and with improved response to change in the delay angle.
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Citations
7 Claims
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1. In a digital pulse generator for gating a plurality of thyristor switches sequentially for conduction under a three-phase AC power supply by gate pulses under a predetermined firing angle α
- , including phase-locked loop means coupled to said AC power supply for deriving an instantaneous electrical angle representative signal;
the combination of;computer means responsive to said predetermined firing angle α
for calculating α
=K. (60)+α
'"'"', where K is an integer number of 60 electrical angles and α
'"'"' is a residual angle in excess of such K. (60) number of electrical angles in said predetermined firing angle α
, and for deriving a first control signal representative of said integer number K and for deriving a second control signal representative of said residual angle α
'"'"';first timer means responsive to said instantaneous electrical angle representative signal for repeatedly establishing a running count through a sixty degrees time interval, each such time interval corresponding to a thyristor switch in the sequence of conduction thereof; counter means responsive to said first timer means for counting successive said time intervals; distributor means responsive to said counter means for selecting said thyristor switches sequentially and accordingly; second timer means responsive to said running count and to said second control signal for enabling said distributor means to gate a selected thyristor switch;
with said distributor means being controlled by said first control signal to shift the order of gating in said sequence by an amount in relation to said integer number. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- , including phase-locked loop means coupled to said AC power supply for deriving an instantaneous electrical angle representative signal;
Specification