GB1600332A

GB1600332A - Torque repeater self driver

Info

Publication number: GB1600332A
Application number: GB941778A
Authority: GB
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1978-03-09
Filing date: 1978-03-09
Publication date: 1981-10-14

Description

(54) TORQUE REPEATER SELF DRIVER (71) We, THE SINGER COMPANY, having its principal place of business at 30 Rockefeller Plaza, New York, New York, United States of America, and doing business at Kearfott Division. 1150 McBride Avenue, Little Falls, New Jersey, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention is related to torque repeaters. More importantly, this invention is related to a technique to position the rotor of a torque repeater by employment of its self-torquing properties.

Torque type synchros are generally characterized as transmitters (TX), differentials (TDX) or receivers (TR). A frequent use for torque repeater or receivers is for driving dials and pointers directlv without further amplification. Where there is a need for a small, highly efficient technique of torque repeater positioning from a digital source, the prior art taught only a torque repeater employing bulky servos or sophisticated high-power electronic circuitry to achieve the desired result.

The technique of the present invention utilizes the self-drive capability of the torquer repeater to position the unit to the desired angle. Thus, the disadvantages of large size and power as well as high cost are overcome.

The present invention comprises a torque repeater which includes a synchro converter which may have three stator windings and an output rotor. Depending upon the input to the stator windings the rotor will come to rest at a positional null which indicates the mechanical position of the electrical input. It is contemplated that the electrical input will be digital signals. However, the invention will perform equally well with time varying inputs or analogue signals. A plurality of electronic switching means are connected to the stator terminals and they operate under the control of a programmable switch control to short circuit predetermined stator windings to provide the desired positional output signals. A sectant detector connected to the stator windings detects signals on the stator windings and determines the desired positioning of the output windings. A duty cycle drive means acting in concert with the sectant detector positions the torque repeater between sectant positions.

Accordingly it is an object of this invention to provide a torque repeater which uses the inherent self-drive capability of the torque repeater to position the unit to the desired output angle.

According to one aspect of the invention there is provided a torque repeater comprising: a synchro converter having three stator windings, said synchro having inherent rotor sectant positions of 60 when discrete stator windings are short-circuited, switching means comprising three electronic switching circuits connected across said stator windings, a programmable switch control connected to said switching means, and a sectant detector connected to said switching means said stator windings and said programmable switch control, said detector sensing the sectant of the angle of rotation of said synchro converter.

According to another aspect of the invention there is provided a torque repeater comprising: a synchro converter having a plurality of stator windings and a rotor said rotor inherently rotating to a null position when certain stator windings are short-circuited, each of said null positions representing a sectant of rotation, a plurality of switching means connected across said stator windings, a programmable switch control connected to said plurality of switching means for applying signals to said switching means in a predetermined sequence, and a sectant detector comprising a plurality of comparator means for sensing the sectant of the angle of rotation of said rotor which corresponds to the shorting of selected stator windings, said sectant detector applying a signal to said programmable means for rotating said synchro to the desired positional output.

According to yet another aspect of the invention there is provided a torque repeater comprising: a synchro converter having a plurality of stator windings said synchro having rotation of its rotor through the application of signals on said stator windings, a plurality of switching means connected across said stator windings, a plurality of switchings means connected across said stator windings, a programmable switch control connected to said plurality of switch means for applying signals to said switch means in a predetermined sequence, and an analog-to-digital converter connected between said stator windings and said programmable switch control for converting the signals from said stator windings into digital inputs signals to said programmable switch control.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a block diagram of the self-driving torque repeater of the invention; Figure 2 is a graphical representation of the positional output of rotor with certain switch closures; Figure 3 is a graphical representation of voltage-sector relationship; Figure 4 is a graphical representation of a duty cycle voltage applied to the stator switches; and Figure 5 is a block diagram similar to Figure 1 employing an A/D converter to drive the switching means.

Referring to Figure 1. a block diagram of the torque repeater of the invention is shown.

The torque repeater includes a synchro converter 10 comprising stator windings S1, S2, S3 and rotor R1. The rotor winding is connected to a source of excitation voltage and under the influence of a signal voltage on the stator windings rotates through an angle ss. Connected to the input terminals of stator windings Sl, S2, and S3 are three solid state switches Swl, Sw2 and Sw. The solid state switches are shown in Figure 1 as mechanical switching elements only for the sake of simplicity. In the actual device, active electronic devices are employed and these devices are well-known to those skilled in the art. Swl is connected across stator windings Sl and S2 5w2 is connected across stator windings Sl and S3, SW3 is connected across stator windings S2 and 53. Sectant detector 11 is connected across stator windings Si, S., S3 and switches Sw1, Sw,, Sw. The function of sectant detector 11 is to sense the present angular position or quadrant in which the rotor of the synchro converter 10 is positioned and use this information to force the synchro converter to null at the desired position. The sectant detector is also connected to switch control 13 which has the function of providing the digital input signals, representative of mechanical position output, to switches Sw1, Sw2 and Sw3.

In operation, when nominal short-circuit is applied across any of two stator terminals (e.g. SIS2, 5153 or S2S3) the rotor, R1 of synchro converter 10 will position itself for minimal current null through the short-circuit. Away from null, a current will flow through the short-circuit producing a self-torque to drive the rotor to the null position. For example, with Sw, closed and Swl and Sw3 open, the rotor will position itself, to induce a minimum voltage between stator windings S, and S3. Two positions exist to satisfy this condition. The voltage induced by the rotor winding produces an output between stator windings S, and S3 proportional to: Vs1s3 = E k sinO1, where E is the rotor excitation voltage k is the transformation ratio between the rotor and secondary windings 61 is the angular position of the rotor Vs1s3 equals 0 for 0t, = 0 or 1800.

Individual shorting of Swl and SW3 will drive the rotor to other null conditions.

Figure 2 illustrates the rotor positions for switch closures. Closing of switches Sw1, 5w2 or Swx can drive the torque repeater to any one of six possible positions. Should it be required to only position the rotor to angles of 60 increments nothing more is required than three switches and controls. Since the closing of any one of the three switches will position the rotor to one of two possible positions for that individual switch, additional circuitry is required to determine that the desired position of the two is attained.

The circuit provided for achieving the desired position of any individual switch is provided in sectant detector 11 shown in Figure 1. The sectant detector comprises a group of three comparators (not shown) each of which samples the three synchro converter stator winding voltage polarity. The voltage polarities of the stator windings are shown in Figure 3. With the polarities as shown on each of the stator windings the sectors l through 6 will be determined. l:or example. assume that it is required to position the synchro converter to the tP position. Switch S2 would be closed and the sectant detector comparators sampled. If the comparator monitoring waveform B (Comparator B) reads negative and the comparator monitoring X-ax cform C (Comparator C) reads positive then the rotor is properly positioned at ()". If however, comparator B should indicate positive instead of negative and comparator ' indicate negative instead of positive, then the rotor has been incorrectly positioned to 18() instead of 0 . In this event, the following procedure would be taken.

Switch Sw1 would be closed which would position the rotor from 1800 to 1200. (see Figure Note that s-hell Swl is closed, the synchro converter will position to 1200 and not 3000 as the rotor will move to its nearest null position. Since 1200 is closer to 1800, (E = 600), than 3()t)3 is to 1800 ( < /S = 1200), the rotor will position itself to 1200. Subsequently, 5w3 would be closed and the svnchro converter will position itself to 600. Finally, 5w2 would be closed positioning the svnchro converter to the desired angle, namely 0 .

For most requirements positioning to 600 increments is not adequate and additional resolution is necessary. This is accomplished as follows. To position the torquer within 60 increments, an appropriate duty cycle is applied to the shorting switches. For example, to position the rotor to 30 (assuming the rotor has been positioned to the correct sector), Sw2 and 5w3 are closed alternately, each at a 50% duty cycle which would result in the torquer assuming the 300 position. A typical 50% duty cycle is illustrated in Figure 4.

T2 = T3 Thus T2/T = l or Duty Cvcle T2 = T2 T2 X 100% = 50% = T3 T2 + T3 A tvpical application for the duty cycle technique is the positioning whose output is geared to a display wheel with the digits 0 through 9 equally spaced on the wheel. Table I illustrates the approximate duty cycles required to position to each number.

TABLE 1 Switch Duty Cycle for 0 o9 Display Logic Equivalent Input Rotor Code Numeric Angle SW#1 SW&num;2 SW&num;3 0000 0 0 0% 100% 0% 0001 1 36 0% 40% 60% 0010 2 72" 20% 0% 80% 0011 3 108 80% 0% 20% 0100 4 144" 60% 40% 0% 0101 5 1800 0% 100% 0% 0110 6 216 0% 40% 60% 0111 7 252 20% 0% 80% 1000 8 288 80% 0% 20% 1001 9 324" 60% 40% 0% It should be noted that the requirements for positions 0 through 4 are identical to positions 5 through 9 simplifying control circuitry.

Thus. upon receipt of a digital command a code representing the desired rotor angle, the appropriate switches are closed with the proper duty cycle to provide the desired result.

The total circuitry required for this device can be implemented with straight-forward logic techniques utilizing gates, counters, PROMS/ROMS, etc., all well-known to those skilled in the art.

An alternate method of positioning the synchro converter is shown in Figure 5. That system operates as follows: synchro converter angle Oi from synchro converter 50 is fed to an A/D converter 51. The resultant digital outputs l from A/D converter 51 in conjunction with 0O the desired angular output, is used to drive switches Swl or 5w2 or 5w3 to momentary or timed shorting periods allowing synchro converter 50 to self-drive to the desired angle no until the feedback loop is satisfied whereupon 81 = 0().

WHAT WE CLAIM IS: 1. A torque repeater comprising: a synchro converter having three stator windings, said synchro having inherent rotor sectant positions of 60 when discrete stator windings are short-circuited, switching means comprising three electronic switching circuits connected across said stator windings, a programmable switch control connected to said switching means, and a sectant detector connected to said switching means said stator windings and said programmable switch control said detector sensing the sectant of the angle of rotation of said synchro converter.

2. A torque repeater as claimed in Claim 1 further comprising means for applying a time varying signal to said switching means whereby the rotor of said synchro is positioned between said inherent sectant positions.

3. A torque repeater comprising: a synchro converter having a plurality of stator windings and a rotor said rotor inherently rotating to a null position when certain stator windings are short-circuited, each of said null positions representing a sectant of rotation, a plurality of switching means connected across said stator windings, a programmable switch control connected to said plurality of switching means for applying signals to said switching means in a predetermined sequence, and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

TABLE 1 Switch Duty Cycle for 0 o9 Display Logic Equivalent Input Rotor Code Numeric Angle SW#1 SW&num;2 SW&num;3 0000 0 0 0% 100% 0%

0001 1 36 0% 40% 60%

0010 2 72" 20% 0% 80%

0011 3 108 80% 0% 20%

0100 4 144" 60% 40% 0%

0101 5 1800 0% 100% 0%

0110 6 216 0% 40% 60%

0111 7 252 20% 0% 80%

1000 8 288 80% 0% 20%

1001 9 324" 60% 40% 0% It should be noted that the requirements for positions 0 through 4 are identical to positions 5 through 9 simplifying control circuitry.

Thus. upon receipt of a digital command a code representing the desired rotor angle, the appropriate switches are closed with the proper duty cycle to provide the desired result.

The total circuitry required for this device can be implemented with straight-forward logic techniques utilizing gates, counters, PROMS/ROMS, etc., all well-known to those skilled in the art.

An alternate method of positioning the synchro converter is shown in Figure 5. That system operates as follows: synchro converter angle Oi from synchro converter 50 is fed to an A/D converter 51. The resultant digital outputs l from A/D converter 51 in conjunction with 0O the desired angular output, is used to drive switches Swl or 5w2 or 5w3 to momentary or timed shorting periods allowing synchro converter 50 to self-drive to the desired angle no until the feedback loop is satisfied whereupon 81 = 0().

WHAT WE CLAIM IS: 1. A torque repeater comprising: a synchro converter having three stator windings, said synchro having inherent rotor sectant positions of 60 when discrete stator windings are short-circuited, switching means comprising three electronic switching circuits connected across said stator windings, a programmable switch control connected to said switching means, and a sectant detector connected to said switching means said stator windings and said programmable switch control said detector sensing the sectant of the angle of rotation of said synchro converter.
2. A torque repeater as claimed in Claim 1 further comprising means for applying a time varying signal to said switching means whereby the rotor of said synchro is positioned between said inherent sectant positions.
3. A torque repeater comprising: a synchro converter having a plurality of stator windings and a rotor said rotor inherently rotating to a null position when certain stator windings are short-circuited, each of said null positions representing a sectant of rotation, a plurality of switching means connected across said stator windings, a programmable switch control connected to said plurality of switching means for applying signals to said switching means in a predetermined sequence, and

a sectant detector comprising a plurality of comparator means for sensing the sectant of the angle of rotation of said rotor which corresponds to the shorting of selected stator windings, said sectant detector applying a signal to said programmable means for rotating said synchro to the desired positional output.
4. A torque repeater comprising: a synchro converter having a plurality of stator windings said synchro having rotation of its rotor through the application of signals on said stator windings, a plurality of switching means connected across said stator windings, a programmable switch control connected to said plurality of switch means for applying signals to said switch means in a predetermined sequence, and an analog-to-digital converter connected between said stator windings and said programmable switch control for converting the signals from said stator windings into digital inputs signals to said programmable switch control.
5. A torque repeater as claimed in Claim 4 further comprising a source of digital input signals to said programmable switch control said digital signals representing the desired rotational angle of said rotor.
6. A torque repeater substantially as hereinbefore described and as shown in the accompanying drawings.