CA2207795C - Method and device for supplying an electric consumer with a regulated electric voltage or current - Google Patents

Abstract

Electromagnetic radiation (R) of a transmitted (3) is converted by a receiver (4) to an electric power supply voltage (U) for an electric consumer (2). The power supply voltage (U) is controlled at a reference value (REF) by controlling the transmitting power of the transmitter (3). Thus aging phenomena in transmitter (3) and receiver (4) and changes in attenuation in the transmission link can be compensated. The radiation (R) is preferably light from a wavelength range between 400 nm and 1400 nm.

Description

Description Method and Device for Supplying an Electric Consumer with a Regulated Electric Voltage or_ Current The invention concerns a method and an arrangement for ~~upplying an electric consumer with an electric power supply voltage or current.
Electric consumers are generally supplied with an electric power supply voltage or current from a power supply source over electric lines. Potential differences between the consumer and source can cause a problem with such a power supply over electric lines.
There are known potential-free (electrically isolated) power supply systems for electric sensors operating as electric consumers, where the power for the sensor is transmitted optically. In a known embodiment, the :Light of: a laser diode is transmitted over an optical fiber to a photoelement array which converts the light to electric power fox- the sensor.
The measurement data from the sensor are also transmitted optically over an optical fiber "Optical Power Supply for Fiber-optic Hybrid Sensors", W. Gross, 1991, Sensors and Actuators A, Vol. 25-27 (1991), pages 475-480.
One problem with such optical power transmission systems is fluctuations in intensity of the light source, due in particular to aging phenomena or changes in ambient temperature. Such fluctuations in intensity of the light source can be compensated by a constant-current regulator for the light source or by using a monitor photodiode or a monitor photoelement to measure the 06i12i97 17:05 KENYOtJ 8~ KEt~IYON ~ 613232840 N0.1~6 P003i029 optical power emitted by the light source and adjusting the power supply current for the light source. Effects of disturbances on the transmission link between light .so~ro~e and photoelectric converter and changes in con~rersion efficiency of the photoelectric converter cannot be compensated with these known types of control.
Therefore, the object ox this invention is to provide a method and an arrangement fat' supplying an electric consumer 'with an electric power supply voltage or current without the disadvantages described above.
This object is achieved according to this invention with the features of Claim 1 and Claim 6. The powar needed by at least one consumer is transmitted in the foam of eiectro:teagnetic radiation by at least one transmitter tc~ at least one rece~.ver.
The receiver is electrically connected to the consumer and converts the electroc~agnetic radiation received froze the transmitter to an electric power supply voltage or current fQr the consumer. To equalize fluctuations in intensity in the electromagnetic radiation or changes in conversion efficiency of the transmitter or receiver, the power supply voltage or current is regulated at a predefined,reference value by regulating the transmitting power of the tran$mitter. Regu~.atinc~ the power supply voltage or cuxxrent as a controlled variable means that the power supply voltage or current is measured, the measured prevailing value (actual va.7.ue) of the power supply voltage or current is compared with the predefined reference value (setpoint), and the transmitting power of the transmitter :~s adjusted (regulated, Controlled) so that the control difference (control deviation) between the measured power supply voltage at

2 the measured power supply current and the reference value comes to lie within a predefined tolerance interval that at least includes the zero point. This control makes it possible to equalize unwanted changes in power supply voltage or current due to interfering factors such as temperature, aging of the transmitter and receiver or attenuation in the transmission link between the transmitter and receiver. Therefore, in particular, the power consumption by the transmitter can be reduced and the lifetime of the transmitter can be increased because the transmitting power emitted by the transmitter can be adapted to the actual demand by the consumer, and excess power need not be supplied to compensate for interference.
This object is also achieved with the features characterized in claim 21.
Advantageous embodiments of and refinements on the method and arrangement according to this invention are derived from the dependent claims.
In accordance with one aspect of this invention, there is provided a method of supplying an electric consumer (2) with an electric power supply voltage (U) or an electric power supply current, wherein a) electromagnetic radiation (R) of a transmitter (3) and of a wavelength range between approximately 400 nm and approximately 1400 nm or in form of radio waves is transmitted to a receiver (4) comprising a photoelectric converter or a radio receiver and is converted by the photoelectric converter or the radio receiver to the electric power supply voltage (U) or the electric power supply current for the consumer (2), b) the power supply voltage (U) or the electric power supply

- 3 -current is regulated by controlling the transmitting power of the transmitter (3) at a predefined reference value (REF), c) the transmitting power of the transmitter (3) is adjusted according to a control difference between the power. supply voltage (U) or the electric power supply current and the reference value (REF).
In accordance with another aspect of this invention, there is provided an arrangement of supplying an electric consumer (2) with an electric power supply voltage (U) or an electric power supply current, having a) a transmitter (3) for transmitting electromagnetic radiation (R) of a wavelength range between approximately 400 nm and approximately 1400 nm or in form of radio waves, b) a receiver (4) for converting the electromagnetic radiation (R) received from the transmitter (3) to the electric power supply voltage (U) or the electric power supply current for the consumer (2) by the means of a photoelectric converter or a radio receiver, c) a regulator (6) that regulates the power supply voltage (U) or the electric power supply current by controlling the transmitting power of the transmitter (3) at a predefined reference value (REF), d) a power controller (7) that adjusts the transmitting power of the transmitter (3) according to a control difference between the power supply voltage (U) or the electric power supply current and the reference value (REF).
In accordance with a further aspect of this invention, there is provided an arrangement for supplying an electric consumer (2) with an electric power supply voltage (US), having a) a transmitter (3) for transmitting electromagnetic radiation (R), b) a receiver (4) for converting the electromagnetic radiation (R) received from - 3a -the transmitter (3) to the electric power supply voltage (US) for the consumer (2), and c) a regulator (6) that measures the power supply voltage (US) and compares the measured value with a predefined reference value (URef) and generates a control signal (S) for controlling the transmitting power of the transmitter (3) in accordance with [the result of] this comparison, wherein the regulator (6) contains a voltage divider (11), a comparing element (12) and a PWM
modulator (14), wherein the input of the voltage divider (11) is connected to the output of the receiver (4) and its output is connected to the negative input of the comparing element (12) whose positive input is connected to the output of the reference value generator (61) and whose output is connected to the input of the PWM modulator (14), and the output of the PWM modulator (14) is connected to [one input of] a digital mixing device (15) whose other input is connected to the consumer and whose output delivers a mixed signal (SpWMD) .
The method and arrangement are essentially suitable for supplying any electric consumer but they are especially suitable for supplying electronic circuits and electric sensors or actuators.
The electromagnetic radiation for transmitting the power for the consumer can be selected from each wavelength range for which there are suitable transmitters for transmitting the electromagnetic radiation and receivers for converting this radiation to electric power. In a first advantageous embodiment, visible light or infrared light from a wavelength range between -~ 3 b -~6~12~97 17:05 KE~~I'~'ON ~ KEhJ'r'Ohd -~ 6132328440 hJ0.146 P005/029 about 400 nrn and about 140 nm is used, Then lasers laser diodes, beds or other light sources rnay be used as the transmitter. Suitable receivers include, for example photoelectric converters such as phatodiades, photaelements and preferably array's of photoelements. The light can be transmittea from the transmitter to the receiver over optical. fibers or as a free beam. In a second embodiment, radio waves from the radio frequency or microwave spectrum tradio or directional radio) and corresponding radio transmitters and radio receivers are used to transmit and receive these radio waves.
In another advantageous embodiment of this control system, successive short control pulses are generated as long as the control difference between the measured power supply voltage or the measured power supply current and the reference value xs less than zero and is thus too small. Then the transmitting power of the transmitter is increased by a power controller via a control current as a function of the integral over time of the control pulses within a predefined time window in order to ' increase the power supply voltage or power supply current that has dropped too much.
To generate the control pulses, first a binary comparator signal containing information about the [plus or minus sign of the control difference is preferably generated by a comparator circuit. The cornparator signal assumes its first logic state when the control difference between the measured value of the power supply voltage or current and the reference value supplied by a reference value generator is less than zero, arad it assumes its second logic state when the control difference is greater than or equal to zero. This binary camparator signal is sent to

4 N0.146 P006r029 06r12r97 17:06 KENYON & KENYON -~ 6132328440 means for generating the control pulses; these means generate electric Gantrol pulses when the comparator s~.gnal is in its first logic state. In one embodiment, these meanv for generating the control pulses include an astable multivibrator whose input receives the comparator signal and wh4se output delivers a train of control pulses as long as the comparator signal is in its first logic state. In another embodiment the means for generating the control pulses include means for modulating the radiation of the transmitter with regular pulses, a. filter unit connected electrically to the receiver to filter oat these pulses, and a logic circuit such as an ANB gate whose first input receives the comparator signal and whose second input receives pulses from the filter unit. The logic cirGUit switches the pulses as control pulses to its output when the comparator signal is in its fixst logic state.
Because of the electrical isolation, the electx~.c control pulses are preferably transmitted as light signals or radio signals from a signal transmitter to a signal recei~rer and then converted back to electric pulses. The amplitude and duration of these electric pulses are preferably normalized, e.g., with the help of a manostable multivibre~tnx, and then sent to an integrator that ~.ntegrates the pulses over time. 'Ihe output current of the integrator, which corresponds to the ~.ntegral of the pulses aver time within a time window defined by the time constant of the integrator. is provided as a variable control current far regulating the transmitting power of t~~e transmitter.
In an especially advantageous ernbadiment of the control system, a pulse width-modulated signal (PWM signal) is used to transmit 06!12197 17:06 KEMYOhJ 8~ KEPJYOhJ ~ E1323284.~0 hJ0.146 F007!029 the control difference between the power supply voltage or power supply current and the reference value. The value of the control difference is then coded in the ~raxxabl.e pulse width of the PWM
signal. The transmitting power of the transmitter is regulated with this PWM signal. 1n this embodiment, r_he regulator also contains a PWM modulator for Gpnverti.ng the control difference into a PWM signal in addition to containing a reference value generator for supplying the reference value and a eumparing element for determining the control difference.
By using a PWM modulator that receives the control diffexeloce determined between the measured power supply voltage or measured power supply current and the predefined reference value, the control difference thus determined is converted to a PWM signal in the regulator and transmitted to the transmitter, preferably as an isolated signal. Gne bit is sufficient for this transmission. Good stability properties of the control circuit are achieved due to the transmission of the PWM signal thus generated, and limit cycles are prevented from occurring from the beginning. Since a t5.mewcoded analog signal is transmitted by means of the PWMf signal, a PI controller can be used to as an output regulator fox the transmitter. This yields an especially advantageous linear control of the power suppJ.y voltage of the consumer.
In an advantageous embodiment, the PWM modulator- is composed of a modulation generator, a comparing element, and a comparator.
The positive input of the comparing element forms the input of the PWM modulator. The negative input of the comparing element is connected to the output of the modulation generator, The comparator is connected downstream from the comparing element.
s 06112.'97 17:07 KEhdYON & KENYON j 6132328440 N0.14E F008~029 The output of the comparator forms the output of the PWM
modulator. The modulation. generator may be in particular a delta generator, a saw-tooth voltage generator or a generator whose modulation Signal is asymmetrical and delta~like and comprises exponential functions.
In an especially advantageous embodiment of the regulator. the PWM modulator is designed to convert the control difference to a PWM signal only in a range around the reference value. This yields a higher resolution, so a better control quality is achieved.
In another advantageous embodiment of this arrangement, the output of the receiver is buffered. The reliability and stability of the load is increased by this buffering of the receiver.
To further illustrate this invention, reference is made to the figures. which schematically show:
Figure 1: a schematic diagram of an arrangement for supplying an electric consumer with an electric power supply voltage, Figures 2 and 3 each show one embodiment of a regulator for such an arrangement, Figure 4: one embodiment of a power controller for such an arrangement, Figure 5: one embodiment of an arrangement with PWM control signals, and Figure 6: one embodiment of a P~1M modulator, each figure in the form of schematic diagrams. Corresponding 06~'12i97 1":07 '~:ENYQN & kEr~1'ON j 6132328440 N0.146 P009i029 parts are labeled with the same notation.
Figure 1 shows an electric consumer 2, a transmitter 3 for transmitting electromagnetic radiation R, a receiver ~ far receiving radiation R, two electric term~.nals 4A arid ~B of the receiver, a regulator 6 and a power controller 7.
Receiver 4 converts electromagnetic radiation R received by transmitter 3 to an electric power supply voltage US car an electric power supply current foz~ consumer 2. This po~.~er supply voltage U$ is available across the two terminals 4A and ~~ of receiver 9 between which consumer 2 is canneated.
The transmitting power of transmitter 3, i.e., the power of the electromafnetic radiation R output, can be controlled by power controller 7. For this purpose, power controller ~ supplies transmitter 3 with aE~ electric control currert T or~ ~ahich the transmitting power of transmitter 3 depends.
Regulator ~ measures power supply voltage U far consumer 2.
Power supply voltage t~ is preferably measured directly at consumer 2 by a four~pole measurement, as illustrated here, to prevent a voltage drop in the feeder lines from recez~rer 4 tc~
consumer 2 in the measurement. Howe~rer, power supply voltage U
can also be picked off at any two points in the power supply circu?t between which consumer 2 is connected. rn particular, the maximum power supply voltage Us available across the two terminals 4A and 48 of receiver 4 ran also be measured.
Regulator 6 compares the measured value (actual value) of power supply voltage U with a predefined reference value (setpaintl 06~12i9? 1?:0? KENYON & KENYOhI ~ 613232640 N0.146 P010i029 RE F. If the actual value of power supply voltage U differs too greatly from its setpoint REF, xegulatvr 6 instructs power controller 7 via control signal S to adjust the transmitting power of transmitter 3 as a function of control difference ~U =
U - REF between actual value U and setpoint REF. If control difference GU = U - REF is below a predefined non-positive tolerance value x1 s 0, i.e., if the prevailing power supply voltage U is too law, power controller 7 increases the transmitting power of transmitter 3 via control current However, if control difference bU = GT - REF exceeds a predefined nor.-negative tolerance value x~ a 0, i.e., i~ the measured power supply voltage U is too high, power controller 7 preferabiy reduces the transmitting powez of transmitter 3. It control difference ~U = U - REF is within the predefined tolerance interval ;x1, x2) between the ~wo tolerance values x1 and x2, power controller 7 keeps control current ~ constant and thus also keeps the transmitting power of transmitter 3 constant.
This arrangement thus yields a control circuit whose controlled variable is the power supply voltage U and whose controlled system consists of transmitter 3, receiver 4 and the transmission link between transmitter 3 and receiver 4. All influencing quantities that affect this contzalled system, such as changes in attenuation of the transmission link for electromagnetic radiation R or changes in efficiency of transmitter 3 and/or receiver 4 due to aging or ohanges in temperature, for example, can be compensated by regulating the power supply voltage U for consumer 2. The manipulated variable of the control circuit is control current T of power controller 7 or control signal S of regulator &, 06~12i97 17: p7 KEhJYON & KENYDN ~ 6132328440 hJ0.146 P~11'029 Regulator 6 may be impwemented in various designs and, to control the transmitting power of transmitter 3, it may be operatively connected to transmitter 3 over various controlled systems.
Figure 2 illustrates a first embodiment of regulator 6.
Regulator 6 contains a reference value generator 61 and a comparator circuit with two resistors 62 and 63 and an operational amplifier 64 in addition to an astable multivibrator 55. Reference value generator 61 is electrically connected to receiver 4 and generates a predefined reference voltage, which is negative in the embodiment illustrated here, as reference value REF which is available at output 61A of reference value generator ~1. This output 61A of reference value generator 61 is electrically connected to a first input 64A of operational amplifier 54 via the first resistor 62. This first input 69A of operational amplifier 64 is electrically connected to the second terminal 9B of receiver 4 via the second resistor 53. The other input ~4B of operational amplifier 64 is electrically connected to the other terminal 4A of receiver 4. In the embodiment illustrated here the second terminal 9B of receiver 9 is at a positive potential with respect to a constant potential, e.g., zero potential (ground), at the first terminal 9A. With a suitable choice of resistors 6~ and 6~ and operational amplifier 64, a binary comparator signal CS is obtainsd at output 54C of the operational amplifiers the first logic state of this binary comparator signal CS corresponds to the case when power supply voltage U is below its setpoint REF t~U c ~), and its second logic state corresponds to the Apposite case, namely when power supply voltage U is greater than or equal to reference value REF
(~U ~ 0). Binary comparator signal CS is sent to astable 06i12.~9'7 17:08 KEhJ~'~JN & KEN'~ON ~ 613232844~ h~0.146 P~12~~29 multivibrator 65. Astable multivibrator 65 generates electric pulses P of a predefined duratzon at given intervals when co:nparator signal CS that is applied to its input is in its first logic state, i.e., when control difference DU = ~' - RAF is less than zero.
In the second embodiment of a regulator according to figure 3, the comparator cixcuit of regulator 6 comprises four resistors 62, 62A, 63 and 63A and again an operational amplifier 64. The first input 64A of operational amplifier 64 is connected to the second terminal 4B of receiver 4 via resistor 63 and to the first terminal 4A of receiver 9 via resistor 63A. The second input 548 of operational amplifier 64 is electrically connected to output G1A of reference value generatoz ~1 via xesistor 62 and to the first terminal 4A of receiver 9 via resistor 62A. In this embodiment, reference value generator 67. supp:~ies a positive reference voltage as rexerence value REF. Furthermore, digital pulses, preferably square-wane pulses, are also transmitted to receiver 9 with electromagnetic radiation R. To do so, radiation R of transmitter 3 is modulated accordingly.
These pulses are filtered out by a filter unit 67 connected across the two terminals 4A and 9~ of receiver 9 and sent as electric pulses P' to one input 668 of a logic circuit 66.
Comparator signal CS of operational amplifier 64 is applied to another input 66A of logic circuit 66. T~ogic circuit 66 switches pulses P' through to its output 56 as pulses P only when compa.rator signal CS is in its first logic state, i.e., when the measured power supply voltage U is below reference value R.EF.
For example, an AN'D gate may be used as logic ditcuit 66.
In the advantageous embodiments illustrated here in Figures 2 06r12i97 17:08 KEN'YON ~ KENYaN ~ 613232844P N0.146 P013i029 and 3, electric pulses P generated by multivibrator ~5 or logic circuit 6~ are sent to a signal transmitter 60 and converted to electromagnetic pulses as control signals S, ir' particular optical signals or radio signals. These electromagnetic control signals S can be transmitted in such a way that they are electrically isolated (potential-free).
Resistors 62. 63, 62A and 63A of the camparator circuit may be fixed 4r adjustable, variable resistors or a combination of the two. Instead of the Camparator circuit illustrated in Figures 2 and ~. other comparator circuits are also possible for comparing the prevailing power supply voltage U with its reference value REF: those skilled in the art will be familiar with such options.
F~trtherrnare, in all embodiments, the power supply current for consumer 2 can be regulated instead of the power supply voltage.
Regulator 6 is then connected in series with consumer 2 to measure the power supply current and it comprises a reFerence current generator and a corresponding cam.parator circuit for comparing the power supply current and the reference current, Figure 4 shows one embodiment of power controller 7 that can be combined to advantage with an embodiment of regulator 5 illustrated in Figures 2 and 3. A signal receiver ~o receives electrarnagnetic control signals S from signal transmitter 60 (not shown in Figure 9) and converts them to electric pulse signals S'. These eleCtrie pulse signals 5' are sent to a monostable multivibratar 71 that forms normalized pulses S'° from pulse signals S' by normalizing them with regard to amplitude and duration and synchronising them with one edge of pulse 06r12.'9~ 1:08 K,ENYON & KENYON ~ 6132328440 N0.146 P014i029 signals S'. These normalized pulses 5" are then sent to an integrator 7~. Integrator '72 then integrates normalized pulses S" over a predefined interval and supplies at its output an integrator current r2, the intensity of which corresponds to the computed integral over time. Furthermore, a current source 73 is provided to generate a constant basic current Il. Total current I1 + I2 resulting from basic current I1 and integrator current I2 is sent to a control unit 79. Control unit 74 supplies control current T for transmitter 3 (not Shawn .in Figure 4). The higher the total current rl + I2 at the input of control unit 74, the higher is control current T.
A control arrangement according to Figure 1 with a regulator 6 according to Figure 2 ox Figure 3 and a power controller 7 according to Figure 4 is preferably operated as follows. Control unit 79 at first receives only basic current Il of current source 73. Control unit 74 supplies transmitter 3 with a corresponding control current T. The corresponding basic transmitting power of transmitter 3 is transmitted with eleCtxomagnetic radiation R to receiver 4 where it is converted to a basic power supply voltage US = U~. Hasic current I1 is set so that control difference Uo - REF between this basic power supply voltage Uo and reference value REF is Less than zero, i.e., Ua - REF < Q. The two tolerance values xl and x2 of regulator 6 are preferably set to be equal to zero, i.e., xl x2 = 0, so the tolerance intereal consists only of the zero point 0 as the single tolerance value. Since it holds that ~U
U a REF < xl = 0 because U s US = TJa, regulator 6 generates control pulses 5 that are transmitted to power controller 7.
Integrator 72 in power controller 7 generates an integrator current T2 that is different from hero> Cgntrol unit 74 then 06i12i97 17:05 KENYON & KENYOhJ ~ 6132328446 N0.1~6 P015i~29 ~.ncreases the transmitting power t~f transz~itter 3 through control current T. This resuJ.ts in an increase in power suppler voltage U at consumer 2. Regulator 6 transmits control signals S
as long as control difference aU is less than zero i.e_, DU = U
- FIEF ~ 0. Regulator 6 no lange~' transmits control signals S
when power supply voltage U is equal to or greater than reference value REF, i.e., nU = U ~ REF ~ ~. rntegratar current I2 of integrator '7z decreases according to the predefined time constant of integrator ~2. 'Then power supply voltage U drops again. As soon as power supply voltage U is again lower than reference value REF, l . a . , AU = U -~ REF < ~, regulator 6 begins again to increase the transmitting power of transmitter through new control signals S. ' In an embodiment not illustrated here far regulating the pawe~c supply vo~.tage ar current far the electric consumer, the measured value factual value) c~f the power supply voltage or current far the consumer', which is measured by a measurement device, can be digitized and transmitted as a digital measurement signal to a digital compar.~ng element. The actual digital value of the power supply voltage ox current can preferably be transmitted in the form of electromagnetic waves from a signal transmitter that is electrically connected to the measurement device to a signal receiver that is electrically connected to the comparing ele~.ent. The cigital comparing element compares the received actual digital value of the power supply voltage or current with a stared digital reference value.
Then control current T for transmitter 3 is adjusted by a power controllez according to the result of this comparison. Far example, control current T is increased when the control difference between the digital value of the: power supply voltage 06f12i97 17:9 KEh~YON & KENYON ~ 6132328440 N0.146 P016~0~9 or current and the digital reference value is less than a first predefined tolerance value which is non-positive, x1 s 0, and it is reduced when this control difference is greater than a second predefined tolerance value which is non-negative, xZ a 0.
However, if the control dzf~erence is within the tolerance interval (x1, x2], control current T and thus the transmitting power of transmitter 3 axe kept constant. A suitable controllable current source can be provided in this case as the power controller for regulating the control current T.
The measured actual value of the power supply voltage or current can of course also be transmitted as an analog value in the farm of electromagnetic radiation to a comparing element, e.g., a comparator circuit or an analog-digital converter with a downstream digital comparing element.
To prevent the transmitting powex of transmitter 3 from assuming excessively high levels during the regulation, a protective device may also be provided to interrupt the power supply to transmitter 3 at a predefined maximum transmitting power of transmitter 3 or maximum control current T. To do so, the transmitting power of transmitter 3 may be monitored, e.g., by a monitoring photodiode~ or control current T may be monitored.
To transmit the power for consumer 2, optical transmission systems or radio transmission systems may be provided. A laser, a laser diode, an LED or some other light source may be provided as optical transmitter 3. For example, a photoel2ment or a photodiode or preferably an array of such photoelectric Converters may be provided as optical receiver 4. bight can be transmitted as electromagnetic radiation R from transmitter 3 to 06~12~97 17:09 KENYON & KENYON 3 6132328440 N0.146 P017i029 receiver ~ over optical Fibers ox by a free beam arrangement. rf the power is transmitted as electromagnetic radiation R by radio waves, any suitable radio transmitter can be used as transmitter 3 and any suitable radio receiver can be used as receiver 4.
Control Signals S can also be transmitted via light waves or radio waves. Signal transmitter 60 and signal receiver 70 are then appropriate optical components or radio companents.
In all era.bodiments, a pluraixty of consumers 2 can also be supplied with power by one or more transmitters 3. Each consumer 2 is then provided with a receiver 4 that converts electromagnetic radiation R from the minimum of one transmitter 3 to a power supply voltage U9 or a power supply current for an electric consumer Z. In this case, synchranizatian signals for Syncrironous Control of consumers 2 can also be transmitted with electromagnetic radiation R. To do so, control current T of the minimum of one transmitter 3 can be modulated accordingly.
In a special embodiment of the arrangement, an electric sensor, e.g., a current transformer or voltage transformers is provided as consumer 2. The measurement signals of the sensor, preferably digitized. are preferably transmitted over the same transmission link as control signals S of regulator 6. In this case, a logic circuit may be provided to carry control signals S of the regulator, the digital measurement signals and corresponding data control pulses an the transmission link between signal transmitter 60 and signal receiver 70.
In addition, the transmission link between transmitter 3 and receiver 4 may also be designed to be bidirectional, by 06r12r97 17:09 KENYON & KENYON j 613232844E N0.1~6 F018r029 transmitting the power and the measurement signals of the sensor and/or control signals S of regulator 6 with a time offset or in different wavelength ranges by a time multiplex method or a wavelength multiplex method.
Reference value REF for regulating the power supply voltage U or the power supply current can be adjusted or controlled during regulation if power consumption by the consumer varies. Then, in the terminology of control technology, REF is th.e reference variable of the Control circuit.
Figure 5 shows a schematic diagram of a measurement system, wherein currents and voltages are measured at a high potential for example. However, the measured values thus obtained must be reliably isolated when transmitted to electronic analyzer 5. As this diagram shows, electronic sensor 9 and electronic analyzer ~ are spatially isolated from each other. The electric isolation is accomplished by means of two separate optical xibers 9 and 10. then uslrig different wavelengths. it is also possible to transmit power and data over a single optical fiber. A
fiberglass ox plastic optical fiber may be used as optical fiber 9 or 10. The type of optical fiber used will depend an the wavelength of the light used, because the wavelength det6rmines the attenuation. Power to supply the electronic sensor is transmitted over optical fiber 9. For this purpose, transmitter 3 delivers to electronic analyzer ~ an electromagnetic radiation R that is converted back to electricity in a receiver 4, which is also referred to as an energy converter. Such an energy converter 4 is a photoelement by design. As a rule, a plurality of photocells, e.g., GaAs photocells, are connected electrically in series to achieve a higher output voltage. Transmitter 3 may 1?

06~12i97 17:10 KENYOhJ ~ KENYON j 6132328440 N0.14E~ P019i029 be, far example, a laser diode that emits light at a wavelength of approx. 85~ nrn. Voltage US (praduGed] by energy converter serves to power electronic sensor 8 directly, i.e " W shout any additional local voltage regulation. To guarantee a more reliable power supply to consumer 2, it is advisable to buffer the output of energy converter 4 with a capacitor. Then the power supply voltage USp is available at this buffered output In order for power supply voltage UsP to nevertheless remain constant, a regulator 6, having a voltage divider 11, a cornpaxing element 12, a PWM modulator 19 and a reference value generator 61 is provided to regulate power supply voltage USp.
First, power supply voltage Usp is measured and compared with a reference voltage U~f used as reference value REF. Because output voltage Usp of energy converter ~ forms power supply voltage USP of the entire electronic sensor circuit 8, and thus the value of reference voltage URIC is smaller than the value of power supply voltage Usp, so output voltage Usp that has been stepped down by voltage divider 11 is used for the comparison in the embodiment illustrated hexe. Reference voltage U~~ is generated according to referencz value generator ~1 and sent both to a positive input of comparing element 12 and to consumer 2, which comprises a signal amplifier and an AjD converter, for example, arid is linked to a sensor 13. Output voltage Usp Of voltage divider 11 is available at the negative input of this comparing element 12. Differential voltage 0L', also referred to as control difference aU, which is obtained at the output of comparing element 32, fs sent to PWM modulator 14. The design of PWt~ modulator 1Q is shown in more detail as a block schematic in Figure 6. The output of this PW'M modulator 14 is connected to a digital mixing device 15, such as a multiplexer. The other input 06/12/97 27:1~ KENYON & KENYDN j 61~23~8440 ND.146 P020/0~9 of this digital mixing device 15 is connected to the output of consumer 2, in particular to its AlD converter. By means of this digital mixing device 15, the resulting PWM signal Spy of PWM
modulator 14 together with data signal S~ of consumer 2 is transmitted as mixed signal S~ to electronic analyzer 5 over optical fiber 10.
Mixed Signal 5~,,,p is separated in the electronic analyzer back into data signal SQ and rWM signal SAM. Although data signal So is sent on to a processor, PWM signal S~~ is applied as an input signal to a power controller 7 that adjusts the power of transmitter 3 so that voltage Us or USp produced by energy c4nverter 4 is kept constant. A demodulator 16 is used to isolate data signal So of consumer 2 from PWM signal Spy of PWM
modulator 19 and is connected at its output to an interface 17.
A processor can be provided at interface 17 for further processing of data signal So of consumer 2. In addition, power controller 7 is also connected to interface 17. A PI controller, for examFle, is provided as power controller 7, because a tirne-coded analog signal is transmitted as ~WNi signal 5~~. Regulation with especially good properties can be achieved by transmitting a quasi~analog control difference aU for power supply voltage Usp.
Due to the use of PWM modulator 14, so that control difference ~U is transmitted by means of a PWM signal 5pw," no limit Cycles occur in voltage regulation, so the load on laser diode 3 is reduced. Furthermore, the stability properties 4f the control circuit are improved. Finally, more sudden disturbances, such as a difference in power consumption by consumer 2 or a disturbance in the laser current, can be controlled with this embodiment.
1~

86i12~97 17:1~ KEh~YOhJ & KEhaYON 3 E132328~4~ hJ0.146 P021i~29 Figure 6 shows the block schematic of one embodiment of ~WM
modulator 14 of electronic sensor 8 from Figure 5. T:nis PWI~i modulator 19 contains a comparing el.ernent 16, a camparator 19 and a modulation generator 20. The positive input of comparing element 18 forms the input of modulator 14, and the output of comparator 19 forms the output of modulator 14. The negative input of comparing element 18 is connected to the output of modulation generator 20, and the output of this comparing element 18 is connected to the input of comparator 19. A saw-tooth voltage generator is provided as the modulation generatof 20. Instead of the saw-tooth voltage] same other periodic modulation voltage U~,~ such as a delta voltage may also be used as modulation voLt~age U,~d. furthermore, the modulation generator may also generate an asymmetrical and delta-like modulation signal comprising exponential functions ("e" functions). PWM
modulator 14 is preferably designed to convert the voltage difference to a PWM signal SQ,,~ only in a range around the desired voltage U~ ~ UR,~. fihis yields a highex resolution and thus better control quality-. The above-mentioned modulation range fox the contxol difference aU that is determined can be adjusted by means of the amplitude of the modulation voltage U,~ .
Good stability properties of the control circuit are achieved in regulating the powex supply voltage USp of consumer 2 due to the design of regulator 6 of electronic sensor 8 aGCarding to Figures 5 and 6, whereby the control difference bU is trapsmitted with the help of a PWM signal SQ~,,,~, One b~.t alone is sufficient for this type of transmission. Since a time~coded analog signal is transmitted with PWM signal Sue" a pI
controller can be used as power controller '7 to regulate the L6~12~97 17:18 KENYON & KENYON -~ 613232844E h-d0.146 P022.'029 power of transmitter 3 of electronic analyzer 5, thus yielding linear contra:.
In addition. aging of the power transmission system can be determined Qn the basis of the current flowing through laser diode 3 because the power supply voltage of electronic sensor B
is regulated. To do so, the prevailing current must be based only on the current flowing at the time of start-up of the sensor system. However, it is assumed here that the aging of transmitter 3 is a measure of the aging of the sensor system as a whole.
Maintenance information can thus be generated by monitoring the laser diode current.
Destruction of one of the two optical fibers 9 and 10 is one source of defects that must always be expected. This always interrupts the data stream transmitted from consumer 2 to electronic analyzer 5, because either the power supply in electronic sensor 8 collapses or the information is simply no longer transmitted. However, such a data strea,z~ failure can also be detected easily in electronic analyzer 5.
Then in such a case, transmitter 3 must be switched off because otherwise high-energy invisible light will escape at the break point and can cause eye damage. The corresponding switch-off signal is obtained by monitoring the continuity of the data stream.

Claims (21)

CLAIMS:

1. ~A method of supplying an electric consumer (2) with an electric power supply voltage (U) or an electric power supply current, wherein a) electromagnetic radiation (R) of a transmitter (3) and of a wavelength range between approximately 400 nm and approximately 1400 nm or in form of radio waves is transmitted to a receiver (4) comprising a photoelectric converter or a radio receiver and is converted by the photoelectric converter or the radio receiver to the electric power supply voltage (U) or the electric power supply current for the consumer (2), b) the power supply voltage (U) or the electric power supply current is regulated by controlling the transmitting power of the transmitter (3) at a predefined reference value (REF), c) the transmitting power of the transmitter (3) is adjusted according to a control difference between the power supply voltage (U) or the electric power supply current and the reference value (REF).

2. Method according to claim 1, wherein successive control pulses (P, S) of a predefined duration are generated and the transmitting power of the transmitter (3) is increased as a function of the integral over time of these control pulses (P, S) within. a predefined time window when the control difference between the power supply voltage (U) or the power supply current and the reference value (REF) is less than zero.

3. Method according to claim 1, wherein a pulse-width-modulated (PWM) control signal (S PWM) containing~~

information about the control difference (.DELTA.U) is used to control the transmitting power of the transmitter (3).

4. ~Method according to one of claims 1 through 3, wherein electromagnetic radiation (R) of a wavelength range between approximately 400 nm and approximately 1400 nm is used.

5. ~Method according to one of claims 1 through 3, wherein radio waves are used as the electromagnetic radiation (R).

6. ~Arrangement of supplying an electric consumer (2) with an electric power supply voltage (U) or an electric power supply current, having a) a transmitter (3) for transmitting electromagnetic radiation (R) of a wavelength range between approximately 400 nm and approximately 1400 nm or in form of radio waves, b) a receiver (4) for converting the electromagnetic radiation (R) received from the transmitter (3) to the electric power supply voltage (U) or the electric power supply current for the consumer (2) by the means of a photoelectric converter or a radio receiver, c) a regulator (6) that regulates the power supply voltage (U) or the electric power supply current by controlling the transmitting power of the transmitter (3) at a predefined reference value (REF), d) a power controller (7) that adjusts the transmitting power of the transmitter (3) according to a control difference between the power supply voltage (U) or the electric power supply current and the reference value (REF).

7. ~Arrangement according to claim 6, wherein the consumer (2) contains a sensor (13).

8. ~Arrangement according to claim 6 or claim 7, wherein a) the regulator (6) contains a1) a reference value generator (61) for supplying the reference value (REF), a2) a comparator circuit (62, 62A, 63, 63A, 64) that is electrically connected to the reference value generator (61) for measuring the power supply voltage (U) or the power supply current and comparing the measured value with the reference value (REF) and for deriving a binary comparator signal (CS) that assumes its first [sic] logic state when the measured value of the power supply voltage (U) or the power supply current is smaller than the reference value (REF), and it assumes its second logic state when the measured value of the power supply voltage (U) or the power supply current is greater than or equal to the reference value (REF), and a3) means that are electrically connected to the comparator circuit (62, 62A, 63, 63A, 64) for generating control pulses (P) when the comparator signal (CS) is in its first state,~
and wherein b) a power divider (7) is provided and is connected to the regulator (6) over a transmission link for transmitting the control pulses (P, S) and it supplies the transmitter (3) with a control current (T) for controlling its transmitting power, with the control current (T) depending on an integral over time of the control pulses (P, S) obtained from the regulator (6) in a predefined time window.

9. ~Arrangement according to claim 8, wherein the power controller (7) contains an integrator (72) that generates an integrator current (I2) that corresponds to the integral over time and forms at least part of the control current (T) of the power controller (7).

10. Arrangement according to claim 7 and one of claims 8 and 9, wherein a common transmission link is provided for transmitting both the control pulses (S) and measurement signals of the sensor in the form of electromagnetic signals.

11. Arrangement according to claim 6, wherein the regulator (6) comprises a reference value generator (61) that supplies a reference value (U ref) [sic; (U Ref), a comparing element (11) that determines the control difference (.DELTA.U) between the power supply voltage (U SP) or the power supply current and the reference value (U ref) [sic; (U Ref)], as well as a pulse-width-modulated (.DELTA. PWM) modulator (14) that converts the control difference (.DELTA.U) to a pulse-width-modulated signal (S PWM) for controlling the transmitting power of the transmitter (3).

12. Arrangement according to claim 11, wherein the PWM
modulator (14) contains a modulation generator (20), a comparing element (18) and a comparator (19), wherein the positive input of the comparing element (18) forms the input and the output of the comparator (19) downstream from the comparing element (18) forms the output of the PWM
modulator (14) and wherein the negative input of the comparing element (18) is connected to the output of the modulation generator (20).

13. Arrangement according to claim 12, wherein the amplitude of the generated modulation voltage (U Mod) of the modulation generator (20) can be adjusted so that the PWM
modulator (14) generates a PWM control signal (S PWM) only in a range around the predefined reference value (U Ref).

14. Arrangement according to claim 12 or claim 13, wherein a saw-tooth voltage generator is provided as the modulation generator (20).

15. Arrangement according to claim 12 or claim 13, wherein a delta voltage generator is provided as the modulation generator (20).

16. Arrangement according to claim 12 or claim 13, wherein a generator that generates a modulation signal that is asymmetrical and delta-like and consists of exponential functions is provided as the modulation generator.

17. Arrangement according to one of claims 11 through 16, wherein the regulator (6) contains a voltage divider (11) that is connected to the receiver (4) and the comparing element (12), and its output voltage (U SP) which has been stepped down in comparison with the output voltage (USP) of the receiver (4) is applied to the negative input of the comparing element (12).

18. Arrangement according to one of claims 11 through 17, wherein a digital mixing device (15) connected to one output of the PWM modulator (14) and to one output of the consumer (2), is provided, and it generates a mixed signal (S PWMD) from at least one data signal (5D) of the consumer (2) and the PWM signal (S PWM) of the PWM modulator (14).

19. Arrangement according to claim 18, wherein a multiplexes is provided as the digital mixing device (15).

20. Arrangement according to one of claims 6 through 19, wherein the output of the receiver (4) is buffered.

21. Arrangement for supplying an electric consumer (2) with an electric power supply voltage (US), having a) a transmitter (3) for transmitting electromagnetic radiation (R), b) a receiver (4) for converting the electromagnetic radiation (R) received from the transmitter (3) to the electric power supply voltage (U S) for the consumer (2), and c) a regulator (6) that measures the power supply voltage (U S) and compares the measured value with a predefined reference value (U Ref) and generates a control signal (S) for controlling the transmitting power of the transmitter (3) in accordance with [the result of] this comparison, wherein the regulator (6) contains a voltage divider (11), a comparing element (12) and a PWM modulator (14), wherein the input of the voltage divider (11) is connected to the output of the receiver (4) and its output is connected to the negative input of the comparing element (12) whose positive input is connected to the output of the reference value generator (61) and whose output is connected to the input of the PWM modulator (14), and the output of the PWM

modulator (14) is connected to [one input of] a digital mixing device (15) whose other input is connected to the consumer and whose output delivers a mixed signal (SPA).