US3546441A - Locomotive engine performance system including the multiplication of analog and digital signals - Google Patents

Description

Umted States Patent [1113546,441.

[72] Inventor ThomasA.Brendle 3,192,371 6/1965 Brahm 235/150.51X

llamburg,NewY0rk 3,309,508 3/1967 Witt 235/150.52 [21] A ppl.No. 792,667 3,444,360 5/1969 Swan 235/150.52X [22] Wed Jan'211969 Pn'mary ExaminerEugene G. Botz [45] Patented Dee.8, 1970 A sslstant Examiner-Joseph F. Ruggiero [73] Asslgnee a i g g k Attorney-Bean and Bean am urg, ew or [54] LOCOMOTIVE ENGINE PERFORMANCE SYSTEM INCLUDING THE MULTIPLICATION OF ANALOG l50.$l, l50.52, 150.53, 150.3, 150.31, 150. 4, l83; 3l8/(lnquired); 324/140, 141, 142

ABSTRACT: Signals indicative of voltage and ampere input to an electric motor as well as power input and the time integral of power input which may vary over wide ranges are developed for display and/or recording and/or transmission. Isolation of the high voltage input as well as linearization of the voltage input signalare achieved by cyclically charging a capacitor to a predetermined value very much less than the voltage input and returning it to a reference-potential by means of a trigger driving a pulse output transformer, in which the pulse output transformer also controls an auxiliary switch to assure returning the capacitor to the reference potential. The digital voltage input signal and an analog current input signal are multiplied by a circuit assuring linearization to analog form and this signal, in turn, is converted to a digital signal for obtaining the time integral of power input.

as 74 f [56] References Cited UNITED STATES PATENTS 3,119,928 l/l964 Skramstad 235/l50.52X

E 0+ l rf y v ref I 56 52 5 rum 5 m WITCH a 4s VHIGH 52 g -vo 32 PATENTED DEC 8 mm SHEET u (If 4 INVENTOR. THONfiS A. BRE/VDL @wflm ATTORNEYS Nu wow INCLUDING THE MULTIPLICATION F ANALOG AND DIGITAL SIGNALS BACKGROUND OF THE INVENTION Diesel-electric locomotives employ a plurality of electric motors, typically fromfour to six electric motors, which may be of various standard types. In scheduling maintenance work, determining rental costs, in general to determine the efficiency of any locomotive while operating alone or in conjunction with one or more other locomotives, it would be desirable to display and/or record various salient data such as the voltage applied to a motor or motors, motor current, power input and the time integral of power input.

Systems of the prior art which are directed in general to this area are relatively inflexible and are of inconvenient nature inasmuch as the infon'nation which is directly displayed either is lacking in accuracyor is not of the type which is particularly useful to the operator.

1' BRIEF SUMMARY or THE INvsNIIoN Accordingly, the presentinvention is directed to a system which accurately displays and/or records motor voltage, motor current, power input and horsepower-hours of input or other time integral of power input information. The system develops electrical signals'which may be used to display,

record and transmit motor input voltage, motor input amperage, powerinput and the time integral of power input.

The system is used advantageously to determine voltage and current inputs as well as power input and the time integral of power input to electrical loads such as motors wherein these quantities may vary over wide ranges.

One of the signals indicativ'eof voltage'or current input is converted to digital form and this digital signal and an analoguesignal indicative of the other input are multiplied to produce an analogue signal in accord with the principles set forth in my copending applicationSer; No. 786,723, filed Dec. 24, 1968. To effect isolation of the high voltage input and to assure a linear relation between voltage inputand digital signal frequency, the voltage input may be chosen for digital conversion by continuously charging a capacitor to a fixed voltage level very much less than the voltage input value and then returning the capacitor to some predetermined reference potential. The circuit for doing this involves a trigger operated at the fixed voltage level and which is coupled to a pulse output transformer. The transformer assures isolation and is also used to control an auxiliary switch device to assure that the capacitor is returned to the reference potential. The pulse output signal is processed to produce a digital signal whose pulses are of significant time duration so that accurate multiplication in a pump diode circuit is obtained to produce an analogue signal indicative of power input. I

This power input analoguesi'gnal is converted toa digital signal to obtain the time integral of power input, and to accommodate for a wide range of values, an integrating capacitor of large value is used in conjunction with a trigger circuit and a bistable circuit having two usable outputs, in which one state of the bistable circuit is held by a time delay circuit, again to accommodate for the wide range of values which may be encountered. A monostable circuit is used between the bistable device and a counter which displays the time integral of power input.

BRIEF DESCRIPTION OF THE DRAWING FIGURES FIG. Us a schematic-view illustrating certain principles of the present invention;

FIG. 2 is an enlargement of the schematic diagram of FIG. 1- expanding the system showntherein;

FIG. 3 is a view showing the waveform of the capacitor FIG. 6 is a circuit diagram showing the remainder of the system. I

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 schematically illustrates the general principles concerned with the present invention and, as shown, processing means 10 and 12 are provided to produce a pair of output signals at 14 and 16 which are respectively proportional to motor volts E and motor amperes I which are the power input parameters to an associated electric motor or motors. FIG. 1 also schematically indicates that the system employs a pair of meters 18 and 20 respectively for displaying the motor volts and motor amperes and which may or not be incorporated into the system, as desired. As will hereinafter appear, one of the two signals at 14 or 16 is of digital form whereas the other is of analogue form and these two signals are applied to a multiplying circuit indicated by the reference character 22 having an output at 24 of the form KEI wherein the constant K may be a conversion factor to convert watts to horsepower and, as shown, a suitable meter 26 may be employed in the system to provide an instantaneous indication of the power input to associated motor or motors. The power input signal is converted to a digital signal in the circuitry 28 and this digital signal is then applied to an integrating mechanism indicated generally by the reference character 30 which reads. out the time integral of the power input and may conveniently be calibrated in horsepower hours, for example. The mechanism 30 may simply take the form of a counter driven by the digital input signal thereto. In addition to the above general systemic arrangement, anyone ora combination of the signals at l4, 16, 24 and 32 may be used, in addition to the direct indicating functions shown, for control purposes directly to the locomotive to which the system" is attached, or alternatively, these signals may be transmitted to a remote control station whereat they may be processed so as to provide control data for a large number of locomotives operating in a given area.

As above stated, one or the other of the signals at 14 or 16 may be of digital form whereas the other is analogue form. In FIG. 2, a preferred system is shown wherein the motor volts signal is converted to digital form whereas the motor amperage is of analogue form. The preferred embodiment has certain advantages, namely, that conversion of the motor volts signal to digital form allows this high voltage system to be easily isolated from the remainder of the system as will be evident hereinafter. FIG. 2 isalso somewhat schematic in form but does illustrate certain principles according to the present invention. Thus, FIG. 2 illustrates the fact that the processing of the motor volts involves the utilization of an analog-to-digital converter 34 having, as an input thereto, the motor voltage impressed across an RC circuit comprising essentially the relatively large value of resistance 38 and. the capacitor 40. As will be described hereinafter, the circuit 34 is such as to allow the voltage across the capacitor 40 to build up to some predetermined value whereafter the capacitor is discharged or returned to some reference potential with the voltage to which the capacitor 40 is allowed to build being maintained at a relatively low value as compared to the voltage compressed across the RC circuit 38,40 whereby, as is shown in FIG. 3, the voltage build up across the capacitor 40 is essentially linear and thus is a very accurate indication of the voltage impressed across the RC circuit 38,40. Thus, as is shown in FIG. 3, the voltage v which is periodically impressed across the capacitor 40 is very very much less than the voltage to which the capacitor could otherwise charge were'it allowed to do so. Thus, the portion 42 of the voltage curve 44 is essentially linear, so that the waveform of the input to the circuit 34 is of sawtooth form as is indicated in FIG. 3, the capacitor always being returned to the same reference potential.

As is shown in FIG. 2, the circuit 34 produces a square wave output as indicated by the reference character 46 whose frequency is linearly related to the voltage impressed across the electric motor. The conventional motor shunt 48 is util- 3 ized to provide an input V to the circuitry which is, essentially',-a milivolt amplifying system to produce a useably high analogue voltage output at the conductor 52 for processing by the multiplying circuitry. The multiplying circuitry is essentially constructed in accord with my copending Pat. application Ser. No. 786,723 filed Dec. 24, 1968 and, as schematically illustrated, includes a switching mechanism 54 to which the digital signal 46 is applied through the lead 56 and which controls the output from the switching mechanism 54 to produce the waveform 58 whose frequency is that of the waveform 46 but whose amplitude is that of the analogue signal at 52 and this digital signal 58 is applied by means of the conductor 62 to the digital-to-analog circuitry 64, which signal is applied by means of the conductor 66 to the amplifier. The amplifier 68 has associated therewith a feedback circuit'including the resistor 70 which tends to maintain the junction 72 at zero or some predetermined reference potential so that the output at the conductor 74 is proportional to the product of E and I, as shown.

FIG. 4 illustrates an operative embodiment of the circuitry 34 of FIG. 2 and will be seen to incorporate a trigger circuit 76 connected across the capacitor 40, the variable resistor 78 being provided to adjust the voltage level at which the capacitor '40 actuates the trigger circuit 76. The output of the trigger circuit 76 is across the primary winding 80 of a pulse output transformer 82 and one of the secondaries 84 of this transformer is utilized to operate the transistor switch 86 which is provided to assure that the capacitor 40 is returned to reference potential and thereby produces the waveform as indicated by the reference character 88. The transistor 90 is provided to assure that the trigger mechanism 76 resets and the other secondary 92 of the pulse output transformer 82 which produces the pulse output waveform 94 is coupled through a suitable capacitor 96 to a pulse amplifier 98 and the output of this amplifier is taken across its load resistor 100 and applied through conductor 102 to the scale of two circuit 104. The output of the scale of two circuit 104, at the lead 56, is a square wave as indicated by the reference character 106 having a frequency half that of the waveform 94 with each pulse of the waveformtrain 106 being of predetermined time duration, the purpose of which will be presently apparent.

Since the waveform 88 is linearly related to'the input voltage, the frequency of'the waveform 106 will be linearly related to the input voltage and, as described hereinabove, the utilization of the output transformer 82 effectively isolates the high voltage circuit from the remainder of the system and, for this purpose, the voltage supply for the system of FIG. 4 should be provided separate from the voltage supply for the remainder ofthe system.

FIG. 5 shows an operative embodiment of the various circuits 50, 54, 64 and 68 described in conjunction with FIG. 2. Whereas the motor voltage will vary between zero and some large maximum, say 1,000 volts, it will usually remain much higher than 100 volts for a typical locomotive, and the motor amperage may vary between zero and some maximum, say in the 'order of 1,500 amperes. Correspondingly, the voltage measured across the shunt 48 which is a standard portion of the electric motor circuit will vary typically between say zero and 100 milivolts and in order to linearize this portion of the system, the differential amplifier 110 has its input leads 112 and 114 connected across the shunt 48 and operates to null its input. The output of this amplifier across the leads 116 and 118 is applied to a milivolt amplifier 120 which comprises the complementary pair of transistors 122 and 124. The output of this amplifier at 126 is applied to a buffer amplifier 128 whose output is applied, through the zero circuit 130, to the lead 132 connected to the multiplying circuit. The zero circuit 130 is provided simply'for the purpose of assuring that the output at the conductor 132 will be zero when the output across the shunt 48 is zero and, to this end, may conveniently take the form of a small DC offset voltage circuit or its equivalent to counteract the offset voltages of the diodes or other non linear devices in the pump-diode circuit.

The nulling feedback circuit from the buffer amplifier 128 is connected by means of a manual switch 134 across a plurality of different resistance elements 136 and 138 which are provided to accommodate for different types of shunts 48 which, being standard, can be accommodated for by a plurality of resistance elements of predetermined-values.-

As shown in FIG. 5, the multiplying circuit takes the form of a pump diode circuit indicated generally" by the reference character 140 and which includes thetrahsistor charge and dump switch 142 controlled by the output-signal 106 c o nnected thereto by the conductor 56, as shown,'the purpose of the transistor switch 142 being, when off, to allow the pump diode capacitor 144 to charge through the diode 146 and the resistor 148 to the corrected value of the output of the buffer amplifier 128 and, when on, to discharge through the diode 150 to transfer its charge to the pump diode capacitor 152.

The outputof'the pump diode circuit is applied to the differentialfamplifier 110, the complementary pair amplifier 120' and. the buffer amplifier 128 corresponding to the respective amplifiers 110, 120 and 128 previously described and having the feedback path 154 as described in conjunction with my aforementioned copending application, which path includes a manually actuated switch 156 for varying the feedback resistance in accord with and to account for different standard numbers of motors employed on diesel-electric locomotives. The output of the feedback amplifier system is at the conductor 160, as shown.

The two differential amplifiers 110 and 110' are shown merely: schematically but will be understood to represent standard solid state differential amplifiers.

FIG.' 6 illustrates the converter circuitry 28 and the integrator 30 as shown in FIG. 2. In order to accommodate for the fact that the power consumption signal at the conductor 160 will vary between wide extremes of frequency, a capacitor 162 I is required to accuratelyaccommodate for this fact and, cor-' respondingly, the value of the resistor 164 is also large. The

transistor 166 is provided to determine the threshold at the conductor 160 at which the capacitor 160 commences to charge and, for this purpose, its base is connected through lead 168 to a movable tap of the resistance 170. The value to which the capacitor 162 is'allowed to charge is controlled by the trigger circuit 172, the resistor 174 and movable tap 176 1 this bistable circuit being applied to the conductor 186. The

pulse output waveform 188 of the trigger circuit 172 is applied through the pulse amplifier transistor and isolating diode 192 to the bistable circuit 184 so'that for every pulse of the output waveform 188, the bistable circuit 184 is switched from an on state at the conductor 186 to an on state at the conductor 182.

Since the value of the capacitor 162 is necessarily large as set forth hereinabove, provision is made for assuring that the transistor switch 178 is on sufficiently long as to completely dump this capacitor and return it to the reference potential and, for this purpose, a time delay circuit including the resistance 188 and capacitor 190 is utilized. Thus, a negativegoing pulse at the junction 194 produced by a positive-going pulse of the waveform 188 and causing the bistable circuit 184 to produce an output at the conductor 182 will be maintained at negative potential for a predetermined period of time by virtue of the correspondingly conductive states of the transistors 196, 198 and 200 as determined by the RC circuit 188, 190 by virtue of the voltage drop across the resistor 202' which is connected by means of the conductor 204 to the junction 194, substantially as is shown.

In view of the fact that the frequency of the signal. at the conductor 160 may be relatively high at periods of high power input, the time delay of the circuit 188, 190 is in the order of a few'miliseconds only so as not to interfere with the operation of the system during high'frequency input at the conductor 160 but still sufficiently long as to maintain the transistor switch 178 on sufficiently long to completely dump the capacitor 162. As a consequence, the waveform 206 produced at the output conductor 1860f the bistable circuit 184 will be of the form shown and since the counter or other integrating mechanism 30 for producing an indication of the power consumption may not easily utilize this type of waveform, the monostable circuit 208 is provided to convert the waveform to a more usable type as indicated by the reference character 210 and so that the integrating, device 30 may properly respond to the input thereto.

lclaim: I I l. A system for determining the power input to electric devices comprising, in combination:

first and second means for respectively producing first and second output signals in response to. the input parameters of voltage and current respectively applied to an electric device, one of which output signals is of analogue form having its amplitude proportional to the input parameter to which it is related, and the other output signal being of digital fonn' having its frequency proportional to the input parameter to whichit is related; multiplier means connected to said first and second output signals for producing acomposite analogue output signal whose amplitude is proportional to the product of said input parameters; and" readout means actuated by said composite analogue output signal for determining the instantaneous power input to the electric devicef 2. The system according to claim! wherein said first means includes an RC circuit connected across the voltage input to the electric device, and triggermeans connected across the capacitance of said RC circuit toproduce an output pulse and discharge said capacitanceat a voltage level very much less than the'input across said RC circuit,

, 3. The system according to claim 2 wherein said first means i also includes a pulse output transformer connected to the outa put of said trigger means isolated.

whereby the input voltage circuit is train of pulses each of which'is of significant time duration.

I 6. The system-according to claim 5 wherein said multiplier means comprisesa pump diode circuit having, as its input, pulses whose amplitudes are equal to the amplitude of the output signal from said second means and whose durations are equal to said predetermined time duration of each pulse of said train. a r

7. The system according to claim 6 including converter means for converting said composite analogue output signal to a composite digital output signal whose frequency is linearly related to the'amplitude of such composite analogue output signal and means for integrating-said composite digital output signal to indicate the time integral of the power input to the electric device.

- 8. The system according to claim 7 wherein said converter means includes an integrating capacitor having a large value of capacitance to accommodate for a wide range of frequency inputs thereto, trigger means actuated by said integrating capacitor, a bistable circuit having one output to said means for integrating, a time delay circuitfor prolonging the-time in 10. The system according to claim 1 wherein said converter means includes an integrating capacitor having a large value of capacitance to accommodate for a wide range of frequency inputs thereto, trigger means actuated by said integrating capacitor, a bistable circuit having one-output to said means for integrating, a time delay circuit for prolonging the time in which said bistable circuit remains in that other state to energize its other output, and switch means actuated by said bistable circuit when in its other state to discharge said integrating capacitor. i

11. The system according to claim 10 including a monostable circuit interposed between said bistable circuit and said means for integrating.

12. A system including an electrical load and means for supplying said load with electrical energy whose volt-ampere product may vary whereby the instantaneous power provided by the load may also vary:

multiplier means having an analogue output; means for supplying said multiplier means with a pair of input signals proportional, respectively, to the voltage and amperage being-supplied to said load, the output of said multiplier means being proportional to said volt-ampere product being supplied to said load; means for indicating the instantaneous power provided by said load from said means; and Y means for converting said output of the multiplier means to a digital signal whose frequency is,proportional to said product.

13. In the system as defined'in claim 12, including an integrator connected to the digital signal produced by the last means for producing an output proportional to the time inwhich said bist'ablecircuit remains in that other state to energize its other output, and switch means actuated by said bistable circuit when in its other state to discharge'said integrating capacitor. I v v 9. The system according to claim 8" including a rnonostable for integrating.

tegral of said product. i

14. in the system as defined inclaim 13, wherein one of said input signals supplied to said multiplier means is of analogue form while the other of said input signals is of digital form.

15. In the system as defined in claim 12, wherein one of said input signals supplied to saidmultiplier means is of analogue form while the other of said input signals is of digital form.

16. In a system including an electric motor and means for supplying said motor with electrical energy whose voltage and the voltage or amperage to which it is related, the other input signal being of analogue form; and means for converting said analogue output of the multiplier means to a digital output signal whose frequency is pro portional to said product. 17. In the system as defined in claim 16, including means connected to said digital output signal of the last means for providing an output proportional to the time'integ ral of said product.

18. A system for providingboth analogue and digital signals related to the instantaneous power delivered to a DC motor, comprising, in combination:

a DC motor; a

means for supplying a pair of analogue signals proportional, respectively, to the voltage and to the amperage supplied to said DC motor;

means for converting one of said analogue signals to a digital signal whose frequency is proportional to the amplitude of said one analoguesignal;

multiplier means having said digital signal and the other analogue signal as inputs for providing an analogue signal output proportional to the instantaneous power delivered to said DC motor; and i analogue output of the multiplier instantaneous power delivered to said DC motor; and

means connected to said digital output signal of saidconverter means for reading the time integral of said instantaneous power delivered to said DC motor.

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