EP0506178B1 - Power supply apparatus - Google Patents
Power supply apparatus Download PDFInfo
- Publication number
- EP0506178B1 EP0506178B1 EP19920200760 EP92200760A EP0506178B1 EP 0506178 B1 EP0506178 B1 EP 0506178B1 EP 19920200760 EP19920200760 EP 19920200760 EP 92200760 A EP92200760 A EP 92200760A EP 0506178 B1 EP0506178 B1 EP 0506178B1
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- EP
- European Patent Office
- Prior art keywords
- power supply
- supply apparatus
- test
- laser
- input
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
- G05F1/569—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/575—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices characterised by the feedback circuit
Definitions
- the invention relates to a power supply apparatus for supplying a device with electric energy, comprising at least one test input for receiving a test signal which is dependent on a variable which itself is dependent on the power applied to the device, which test input is connected to a first input of a comparator circuit, a second input of which is connected to a generator which generates a reference signal which is a measure of a desired value of said variable, an output of the comparator circuit being connected to a control member which controls the power applied to the device by the power supply apparatus so that said variable is essentially equal to the desired value.
- the known power supply apparatus is intended to power a semiconductor laser, a photodiode which is accommodated in the same envelope as the laser generating a photocurrent which is proportional to the light flux of the laser and which constitutes the test signal.
- the power applied to the laser in the known power supply apparatus can be controlled so that the current produced by the photodiode (monitor) remains constant at a desired value.
- the control of only one variable involves the risk that the value of another laser variable is no longer within the desired range or, even worse, no longer within the safe range.
- the power supply apparatus in accordance with the invention is characterized in that the power supply apparatus comprises at least two test inputs with associated comparator circuits, the generator generating a number of reference signals which corresponds to the number of test inputs, the control member controlling the power applied to the device by the power supply apparatus so that at least one of the variables corresponding to the test signals is essentially equal to the value desired for the relevant variable, the other variables corresponding to the test signals deviating from the associated desired values in a predetermined sense only.
- a variable which can in principle be chosen at random can be maintained at the desired value, the other variables, for example all remaining below the desired value so that exceeding of said value and of a higher, dangerous value is precluded. If a deviation of a variable to a value below a given value is deemed risky, the control member should, of course, be adapted so that the relevant variable always remains above an adjusted value which is higher than the "risky" value.
- the control member may comprise, for example a suitably programmed microprocessor which decides which variable is to be maintained at the desired value in order to keep the other variables below (or above) the desired value.
- This microprocessor can also control the adjustment of the chosen variable and the monitoring of the other variables.
- control member can be constructed without including a microprocessor
- the control member comprises a number of semiconductor diodes which corresponds to the number of test inputs, each semiconductor diode comprising a first and a second connection, the first connections being connected to one another and to a current source circuit, each second connection being connected to the output of one of the comparator circuits.
- a control member thus constructed satisfies the requirements imposed without requiring further control.
- the first connection of each of the semiconductor diodes must be an anode connection.
- test signals include an electric voltage applied to the device and an electric current taken up by the device.
- An embodiment which is particularly suitable for supplying a semiconductor laser with electric energy is also characterized in that the variables represented by the test signals also include the radiant power of the laser and a signal produced by a monitor connected to the laser.
- the power supply apparatus shown in the form of a block diagram in Fig. 1 serves to supply a device 1 with electric energy.
- the device 1 may be, for example a semiconductor laser.
- the power supply apparatus comprises a test circuit 3 which, in the present embodiment, comprises four test inputs 5a, 5b, 5c, 5d, which can receive test signals from the device 1. The value of each test signal is dependent on a variable which itself is dependent on the power applied to the device 1.
- the test circuit 3 consists of four sections 3a to 3d, each of which is connected to one of the four test inputs 5a to 5d. The output of each section 3a ... 3d is connected to a first input 7a ... 7d of a comparator circuit 9a ... 9d, a second input 11a ...
- each comparator circuit 9a ... 9d is connected to an input 15a ... 15d of a control member 17 which controls, via an output stage 19, the power applied to the device 1 so that at least one of the variables corresponding to the test signals is essentially equal to the value desired for the relevant variable, the other variables corresponding to the test signals not being greater than the relevant desired value.
- Fig. 2 shows an elementary circuit diagram of an embodiment of the control member 17.
- "Hard" voltages U 1 ... U 4 are applied to the inputs 15a ... 15d, i.e . voltages originating from voltage sources without internal impedance. This is symbolically represented by unit amplifiers 21a ... 21d preceding the inputs 15a ... 15d.
- a unit amplifier 25 is also shown to be connected to the output 23 of the control member 17 so as to indicate that the circuit is not loaded by the impedance at the output.
- the control member 17 comprises four semiconductor diodes 27a ... 27d, each of which comprises a first and a second connection.
- the first connection is the anode connection and the second connection is the cathode connection.
- the first connections are connected to one another and to a current source circuit 29.
- Each of the second connections is connected to one of the inputs 15a ... 15d.
- the restriction is imposed that there are only two input voltages U 1 and U 2 .
- the current source 29 applies a constant current I cc to the diodes 27a and 27b.
- the current will be distributed between the two diodes so that a current I 1 flows through the diode 27a and a current I 2 flows through the diode 27b.
- the output voltage U o is thus defined.
- I 1 I sat [exp ( q kT ( U o - U 1 ))-1]
- I 2 I sat [exp ( q kT ( U o - U 2 ))-1]
- I cc I 1 + I 2
- I sat represents the saturation current of the diodes
- q is the charge of the electron
- k is Boltzmann's constant
- T is the absolute temperature.
- Fig. 3 graphically shows the transfer of the control member.
- the other input voltage U 2 is maintained constant at an arbitrary value.
- three regions can be distinguished in the transfer function. 1.U 1 ⁇ U 2
- the exponential term with U 1 can be ignored relative to that with U 2 .
- the constant term with I cc very well approximates the voltage across the diode U D if the diode carries the full current I cc. This is because for silicon diodes the extra term with I sat in the numerator can be completely ignored relative to the term with I cc .
- the output voltage U o varies linearly as a function of the input voltage U 1 and is independent of the input voltage U 2 :
- U o U 1 + U D 2.U 1 ⁇ U 2
- This voltage region constitutes a transition region.
- the equation (4) cannot be simplified and the value for the output voltage must be determined by calculation. All individual terms are continuous and can be differentiated, so that the transition is smooth:
- U O U 1 + U 2 - kT q ln [exp ( q kT U 1 )+exp ( q kT U 2 )]+ U D
- the output voltage U o will follow the lowest input voltage at a voltage distance equal to U D .
- the described variation of the output voltage U o as a function of the input voltages is graphically shown in Fig. 3. It will be evident that the output voltage is substantially always equal to the smaller one of the two input voltages, except for the diode voltage U D which, however, is constant and known and for which, therefore, correction can be readily made. It is only in the transition region that the output voltage is not exactly equal to one of the two input voltages, but it is never greater than the smaller one of these input voltages. Thus, the device 1 is not endangered and a major advantage of the transition region consists in that no voltage peaks occur upon transition, as would be the case in response to abrupt switching over.
- the effect of the constant term U D can be eliminated by reducing, for example the input voltages by an amount U D before presentation to the inputs of the control member. Another possibility consists in the reduction of the output voltage U 0 by this amount. However, because the control member 17 itself forms part of a closed feedback loop (see Fig. 1), the effect of U D will be reduced by division by the loop gain of the feedback loop.
- Fig. 4 shows a circuit diagram of an embodiment of the reference signal generator 13.
- a stabilized reference voltage U REF is formed from a supply voltage U B .
- Four reference signals I s , U s , M s and L s can be formed from U REF by means of four accurate potentiometers 35a, 35b, 35c and 35d. If the device 1 is a semiconductor laser, I s and U s may represent desired values of the current I through and the voltage U across the laser, respectively.
- M s and L s then represent desired values of the output signals M and L of a photodiode which serves as a monitor and which is accommodated within the envelope of the laser, and a sensor measuring the light current of the laser, respectively.
- the time constant of the combination formed by the capacitor 32 and the resistor 34 enables the reference voltage U REF and the reference signals derived therefrom, to be controlled at a predetermined rate from the value zero to the working point.
- the parallel connection of the zener diode 31 and the capacitor 32 is connected to the positive input of the operational amplifier 33. When an external signal is superposed on this positive input, the reference signals can be modulated, if desired.
- the reference signals may in principle have any arbitrary shape; they may also be alternating voltages.
- Figs. 5A and B show a circuit diagram of an embodiment of a test circuit 3 for obtaining test signals I m , U m , M m and L m which represent the variables I, U, M and L.
- This test circuit comprises four sections 3a ... 3d.
- the sections 3a and 3b are shown, together with the semiconductor laser, in Fig. 5A, the sections 3c and 3d being shown in Fig. 5B, together with the semiconductor laser.
- the semiconductor laser is denoted by the reference numeral 37 in both Figures.
- the first section 3a comprises a measuring resistor 39 which is connected in series with the laser 37.
- the voltage across this resistor being proportional to the laser current I, is converted into the test signal U m by means of an operational amplifier 41.
- the second section 3b comprises two connections 43 and 45 which are connected to the anode and to the cathode, respectively, of the laser 37.
- the laser voltage U can thus be measured in a currentless manner, so that the voltage drop across the supply leads of the laser is eliminated (four-point measurement).
- the diode voltage U is converted into the test signal U m .
- the semiconductor laser 37 is accommodated, together with a photodiode 49 serving as a monitor, in a common envelope 51 (see Fig. 5B).
- This photodiode forms part of the third section 3c and detects a light current M emerging at the rear of the laser 37.
- the current thus delivered by the photodiode 49 is converted into the test signal M m by means of an operational amplifier 53.
- the fourth section 3d of the test circuit 3 comprises a photodiode 55 which is arranged outside the envelope 51 and which detects the light current L produced by the laser 37.
- the current generated by the photodiode 55 is converted into the test signal L m by means of an operational amplifier 57.
- Fig. 6 shows a circuit diagram of an embodiment of one of the comparator circuits 9a ... 9d. Only the first comparator circuit 9a is shown, because the other comparator circuits 9b ... 9d are identical thereto.
- the comparator circuit 9a shown comprises two inputs 11a and 7a which receive the current reference signal I s and the current test signal I m , respectively. These inputs are connected to the positive and the negative input, respectively, of a differential amplifier 59 whose output produces an error signal U 1 which represents the difference I s -I m .
- the other comparator circuits 9b ... 9d produce output signals U 2 ...
- the output signals U 1 ... U 4 form the input signals for the control member 17 which supplies the control voltage U o for the semiconductor laser 37.
- the output signals U 1 ... U 4 of the differential amplifiers 59 are "hard" voltages, so that the unit amplifiers 21a ... 21d shown in Fig. 2 can actually be dispensed with.
- the control voltage U o is applied to the input of the output stage 19, a circuit diagram of an embodiment of which is shown in Fig. 7.
- the output stage 19 is necessary to ensure that the control memory 17 (Fig. 2) is not loaded by the current to be applied to the semiconductor laser 37. Therefore, the output stage 19 comprises an output transistor 61 which is capable of supplying adequate current so that the unit amplifier 25 shown in Fig. 2 actually can also be dispensed with.
- the output transistor 61 is controlled by an operational amplifier 63 where to the control voltage U 0 is applied and which does not load the output 23 of the control member 17.
- the output transistor 61 and the measuring resistor 39 see also Fig.
- Fig. 8 shows an example of the characteristics of a semiconductor laser diode.
- the curves 65, 67 and 69 represent the variation of the laser voltage U, the radiant power L and the monitor signal M, respectively, as a function of the laser current I.
- the reference values I s , U s , L s and M s are also shown.
- M m M s .
- L the transition region L as well as M is approximately equal to the associated reference value and in any case none of the four variables exceeds the reference value.
- the power supply apparatus in accordance with the invention is particularly suitable for the supply of energy to a semiconductor laser, notably in measuring and life test set-ups.
- the apparatus can be used whenever two or more process variables are to be measured and controlled.
- the invention is not restricted to the adjustment of a component, apparatus or process to a smallest value, given the values of a number of variables.
- the function of the control member 17 is transformed to the highest setting, given the value of a number of variables, simply by reversing the polarity of the diodes 27a ... 27d (Fig. 2) and the direction of the current I cc .
- a suitable field of application is the field of electric supply equipment in which generally the electric voltage and current are variables.
- a four-quadrant power supply is a power supply capable of delivering as well as dissipating power.
- capacitive, inductive or negative impedances can be driven without giving rise to stability problems, because the invention utilizes real, non-complex measured values of current and voltage.
- the power supply apparatus can thus also be used as an adjustable load for other power supplies or other equipment.
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Description
- The invention relates to a power supply apparatus for supplying a device with electric energy, comprising at least one test input for receiving a test signal which is dependent on a variable which itself is dependent on the power applied to the device, which test input is connected to a first input of a comparator circuit, a second input of which is connected to a generator which generates a reference signal which is a measure of a desired value of said variable, an output of the comparator circuit being connected to a control member which controls the power applied to the device by the power supply apparatus so that said variable is essentially equal to the desired value.
- An example of such a power supply apparatus is described in Philips Tecnical Review 39 (1980), No. 2, pp. 37-47, notably with reference to Fig. 14. The known power supply apparatus is intended to power a semiconductor laser, a photodiode which is accommodated in the same envelope as the laser generating a photocurrent which is proportional to the light flux of the laser and which constitutes the test signal. The power applied to the laser in the known power supply apparatus can be controlled so that the current produced by the photodiode (monitor) remains constant at a desired value. The control of only one variable, however, involves the risk that the value of another laser variable is no longer within the desired range or, even worse, no longer within the safe range. Driving a semiconductor laser diode beyond the safe working range can readily damage the laser. For safe operation of a laser, therefore, it would be desirable to control the power applied to the laser so that more than one of the laser variables is maintained at or near a desired value. In addition to said monitor current, such variables are, for example the laser current and the laser voltage and the radiant power of the laser. However, in practice this is not very well possible because the various variables are interrelated in a rather complex manner.
- It is an object of the invention to provide a power supply apparatus of the kind set forth which enables one variable to be maintained at a desired value while maintaining the other variables at least within limits which are considered to be safe.
- To achieve this, the power supply apparatus in accordance with the invention is characterized in that the power supply apparatus comprises at least two test inputs with associated comparator circuits, the generator generating a number of reference signals which corresponds to the number of test inputs, the control member controlling the power applied to the device by the power supply apparatus so that at least one of the variables corresponding to the test signals is essentially equal to the value desired for the relevant variable, the other variables corresponding to the test signals deviating from the associated desired values in a predetermined sense only.
- Using the power supply apparatus in accordance with the invention, a variable which can in principle be chosen at random can be maintained at the desired value, the other variables, for example all remaining below the desired value so that exceeding of said value and of a higher, dangerous value is precluded. If a deviation of a variable to a value below a given value is deemed risky, the control member should, of course, be adapted so that the relevant variable always remains above an adjusted value which is higher than the "risky" value.
- The control member may comprise, for example a suitably programmed microprocessor which decides which variable is to be maintained at the desired value in order to keep the other variables below (or above) the desired value. This microprocessor can also control the adjustment of the chosen variable and the monitoring of the other variables.
- An embodiment in which the control member can be constructed without including a microprocessor is characterized in that the control member comprises a number of semiconductor diodes which corresponds to the number of test inputs, each semiconductor diode comprising a first and a second connection, the first connections being connected to one another and to a current source circuit, each second connection being connected to the output of one of the comparator circuits. A control member thus constructed satisfies the requirements imposed without requiring further control. When it is specified that the variables which are not maintained at the desired value should remain below the desired value, the first connection of each of the semiconductor diodes must be an anode connection.
- An embodiment of the power supply apparatus in accordance with the invention which is suitable for a variety of applications is characterized in that the variables represented by the test signals include an electric voltage applied to the device and an electric current taken up by the device.
- An embodiment which is particularly suitable for supplying a semiconductor laser with electric energy is also characterized in that the variables represented by the test signals also include the radiant power of the laser and a signal produced by a monitor connected to the laser.
- The invention will be described in detail hereinafter with reference to the drawing.
- Fig. 1 shows a block diagram of an embodiment of a power supply apparatus in accordance with the invention,
- Fig. 2 shows a circuit diagram of a control member for the power supply apparatus shown in Fig. 1,
- Fig. 3 shows a graph illustrating the operation of the control member shown in Fig. 2,
- Fig. 4 shows a circuit diagram of a reference signal generator for use in the power supply apparatus shown in Fig. 1,
- Fig. 5 shows a circuit diagram of a test circuit for use in the power supply apparatus shown in Fig. 1,
- Fig. 6 shows a circuit diagram of a comparator circuit for use in the power supply apparatus shown in Fig. 1,
- Fig. 7 shows a circuit diagram of an output stage for use in the power supply apparatus shown in Fig. 1, and
- Fig. 8 shows a graph with characteristics of a semiconductor laser in order to illustrate the operation of the power supply apparatus in accordance with the invention.
- The power supply apparatus shown in the form of a block diagram in Fig. 1 serves to supply a
device 1 with electric energy. Thedevice 1 may be, for example a semiconductor laser. The power supply apparatus comprises atest circuit 3 which, in the present embodiment, comprises fourtest inputs device 1. The value of each test signal is dependent on a variable which itself is dependent on the power applied to thedevice 1. Thetest circuit 3 consists of four sections 3a to 3d, each of which is connected to one of the fourtest inputs 5a to 5d. The output of each section 3a ... 3d is connected to afirst input 7a ... 7d of acomparator circuit 9a ... 9d, a second input 11a ... 11d of which is connected to agenerator 13 which is adapted to generate a reference signal which is a measure of a desired value of the relevant variable. The output of eachcomparator circuit 9a ... 9d is connected to aninput 15a ... 15d of acontrol member 17 which controls, via anoutput stage 19, the power applied to thedevice 1 so that at least one of the variables corresponding to the test signals is essentially equal to the value desired for the relevant variable, the other variables corresponding to the test signals not being greater than the relevant desired value. - Fig. 2 shows an elementary circuit diagram of an embodiment of the
control member 17. "Hard" voltages U1 ... U4 are applied to theinputs 15a ... 15d, i.e. voltages originating from voltage sources without internal impedance. This is symbolically represented by unit amplifiers 21a ... 21d preceding theinputs 15a ... 15d. Aunit amplifier 25 is also shown to be connected to theoutput 23 of thecontrol member 17 so as to indicate that the circuit is not loaded by the impedance at the output. - The
control member 17 comprises foursemiconductor diodes 27a ... 27d, each of which comprises a first and a second connection. In the embodiment shown, the first connection is the anode connection and the second connection is the cathode connection. The first connections are connected to one another and to acurrent source circuit 29. Each of the second connections is connected to one of theinputs 15a ... 15d. - In order to simplify the explanation of the operation of the circuit, in first instance the restriction is imposed that there are only two input voltages U1 and U2. The
current source 29 applies a constant current Icc to thediodes diode 27a and a current I2 flows through thediode 27b. The output voltage Uo is thus defined. When thediodes - Fig. 3 graphically shows the transfer of the control member. For the sake of clarity, only one input voltage, being the input voltage U1 in the present case, is varied. The other input voltage U2 is maintained constant at an arbitrary value. Depending on the relative position of the input voltages, three regions can be distinguished in the transfer function.
- If the transition region is defined as the region in which the diode currents do not deviate by more than a factor one hundred, the total transition region for silicon diodes amounts to approximately 2(kT/q)ln0.01 ≈ 230 mV.
- If both input voltages vary, the output voltage Uo will follow the lowest input voltage at a voltage distance equal to UD. The described variation of the output voltage Uo as a function of the input voltages is graphically shown in Fig. 3. It will be evident that the output voltage is substantially always equal to the smaller one of the two input voltages, except for the diode voltage UD which, however, is constant and known and for which, therefore, correction can be readily made. It is only in the transition region that the output voltage is not exactly equal to one of the two input voltages, but it is never greater than the smaller one of these input voltages. Thus, the
device 1 is not endangered and a major advantage of the transition region consists in that no voltage peaks occur upon transition, as would be the case in response to abrupt switching over. -
-
- The effect of the constant term UD can be eliminated by reducing, for example the input voltages by an amount UD before presentation to the inputs of the control member. Another possibility consists in the reduction of the output voltage U0 by this amount. However, because the
control member 17 itself forms part of a closed feedback loop (see Fig. 1), the effect of UD will be reduced by division by the loop gain of the feedback loop. - Fig. 4 shows a circuit diagram of an embodiment of the
reference signal generator 13. Using azener diode 31 and anoperational amplifier 33, a stabilized reference voltage UREF is formed from a supply voltage UB. Four reference signals Is, Us, Ms and Ls can be formed from UREF by means of fouraccurate potentiometers device 1 is a semiconductor laser, Is and Us may represent desired values of the current I through and the voltage U across the laser, respectively. Ms and Ls then represent desired values of the output signals M and L of a photodiode which serves as a monitor and which is accommodated within the envelope of the laser, and a sensor measuring the light current of the laser, respectively. Parallel to thezener diode 31 there is connected acapacitor 32 and a resistor 34 is connected between the supply voltage UB and said parallel connection. The time constant of the combination formed by thecapacitor 32 and the resistor 34 enables the reference voltage UREF and the reference signals derived therefrom, to be controlled at a predetermined rate from the value zero to the working point. The parallel connection of thezener diode 31 and thecapacitor 32 is connected to the positive input of theoperational amplifier 33. When an external signal is superposed on this positive input, the reference signals can be modulated, if desired. The reference signals may in principle have any arbitrary shape; they may also be alternating voltages. - Figs. 5A and B show a circuit diagram of an embodiment of a
test circuit 3 for obtaining test signals Im, Um, Mm and Lm which represent the variables I, U, M and L. This test circuit comprises four sections 3a ... 3d. For the sake of clarity, thesections 3a and 3b are shown, together with the semiconductor laser, in Fig. 5A, thesections reference numeral 37 in both Figures. - The first section 3a comprises a measuring
resistor 39 which is connected in series with thelaser 37. The voltage across this resistor, being proportional to the laser current I, is converted into the test signal Um by means of anoperational amplifier 41. - The
second section 3b comprises twoconnections laser 37. The laser voltage U can thus be measured in a currentless manner, so that the voltage drop across the supply leads of the laser is eliminated (four-point measurement). Using anoperational amplifier 47, the diode voltage U is converted into the test signal Um. - As has already been described in the cited article in Philips Technical Review 39 (1980), No. 2, pp.37-47, the
semiconductor laser 37 is accommodated, together with aphotodiode 49 serving as a monitor, in a common envelope 51 (see Fig. 5B). This photodiode forms part of thethird section 3c and detects a light current M emerging at the rear of thelaser 37. The current thus delivered by thephotodiode 49 is converted into the test signal Mm by means of anoperational amplifier 53. - The
fourth section 3d of thetest circuit 3 comprises aphotodiode 55 which is arranged outside theenvelope 51 and which detects the light current L produced by thelaser 37. The current generated by thephotodiode 55 is converted into the test signal Lm by means of anoperational amplifier 57. - Fig. 6 shows a circuit diagram of an embodiment of one of the
comparator circuits 9a ... 9d. Only thefirst comparator circuit 9a is shown, because theother comparator circuits 9b ... 9d are identical thereto. Thecomparator circuit 9a shown comprises twoinputs 11a and 7a which receive the current reference signal Is and the current test signal Im, respectively. These inputs are connected to the positive and the negative input, respectively, of adifferential amplifier 59 whose output produces an error signal U1 which represents the difference Is-Im. Theother comparator circuits 9b ... 9d produce output signals U2 ... U4 which represent the differences Us-Um, Ms-Mm and Ls-Lm, respectively. The output signals U1 ... U4 form the input signals for thecontrol member 17 which supplies the control voltage Uo for thesemiconductor laser 37. The output signals U1 ... U4 of thedifferential amplifiers 59 are "hard" voltages, so that the unit amplifiers 21a ... 21d shown in Fig. 2 can actually be dispensed with. - The control voltage Uo is applied to the input of the
output stage 19, a circuit diagram of an embodiment of which is shown in Fig. 7. Theoutput stage 19 is necessary to ensure that the control memory 17 (Fig. 2) is not loaded by the current to be applied to thesemiconductor laser 37. Therefore, theoutput stage 19 comprises anoutput transistor 61 which is capable of supplying adequate current so that theunit amplifier 25 shown in Fig. 2 actually can also be dispensed with. Theoutput transistor 61 is controlled by anoperational amplifier 63 where to the control voltage U0 is applied and which does not load theoutput 23 of thecontrol member 17. Theoutput transistor 61 and the measuring resistor 39 (see also Fig. 5A), across which the laser current is measured, are included in the feedback loop of theoperational amplifier 63 so that voltage drops across these components do not affect the laser control itself. The voltage across thelaser 37 is measured by way of a four-point measurement as described, so that the voltage drop due to the resistance of the supply leads is again eliminated. - Fig. 8 shows an example of the characteristics of a semiconductor laser diode. The
curves potentiometer 35d (Fig. 4), the laser current I will increase until one of the other variables is substantially equal to the reference value, for example Mm=Ms. In the transition region L as well as M is approximately equal to the associated reference value and in any case none of the four variables exceeds the reference value. - As has already been described, the power supply apparatus in accordance with the invention is particularly suitable for the supply of energy to a semiconductor laser, notably in measuring and life test set-ups. However, it will be evident that the apparatus can be used whenever two or more process variables are to be measured and controlled. It is to be noted that the invention is not restricted to the adjustment of a component, apparatus or process to a smallest value, given the values of a number of variables. The function of the
control member 17 is transformed to the highest setting, given the value of a number of variables, simply by reversing the polarity of thediodes 27a ... 27d (Fig. 2) and the direction of the current Icc. Thus, by combination of the highest and the lowest setting within thecontrol member 17 it is even possible to control a process in a given range, given the lowest and highest setting of a number of variables. A suitable field of application is the field of electric supply equipment in which generally the electric voltage and current are variables. By a combination of the positive lowest and negative highest setting within the control member, it is thus even possible to realise a so-called four-quadrant power supply. A four-quadrant power supply is a power supply capable of delivering as well as dissipating power. The nature of the device being powered is irrelevant in this respect. Notably capacitive, inductive or negative impedances can be driven without giving rise to stability problems, because the invention utilizes real, non-complex measured values of current and voltage. The power supply apparatus can thus also be used as an adjustable load for other power supplies or other equipment.
Claims (4)
- A power supply apparatus for supplying a device (1) with electric energy, comprising at least one test input (5a, ..., 5d) for receiving a test signal which is dependent on a variable which itself is dependent on the power applied to the device (1), which test input (5a, ..., 5d) is connected to a first input (7a, ..., 7d) of a comparator circuit (9a, ..., 9d), a second input (11a, ..., 11d) of which is connected to a generator (13) which generates a reference signal which is a measure of a desired value of said variable, an output of the comparator circuit (9a, ..., 9d) being connected to a control member (17) which controls the power applied to the device (1) by the power supply apparatus so that said variable is essentially equal to the desired value, characterized in that the power supply apparatus comprises at least two test inputs (5a, ..., 5d) with associated comparator circuits (9a, ..., 9d), the generator (13) generating a number of reference signals which corresponds to the number of test inputs, the control member (17) controlling the power applied to the device (1) by the power supply apparatus so that at least one of the variables corresponding to the test signals is essentially equal to the value desired for the relevant variable, the other variables corresponding to the test signals deviating from the associated desired values in a predetermined sense only.
- A power supply apparatus as claimed in Claim 1, characterized in that the control member (17) comprises a number of semiconductor diodes (27a, ..., 27d) which corresponds to the number of test inputs (5a, ..., 5d), each semiconductor diode comprising a first and a second connection, the first connections being connected to one another and to a current source circuit (29), each second connection being connected to the output of one of the comparator circuits (9a, ..., 9d).
- A power supply apparatus as claimed in any one of the preceding Claims, characterized in that the variables represented by the test signals include an electric voltage applied to the device (1) and an electric current taken up by the device.
- A power supply apparatus as claimed in Claim 3 for supplying a semiconductor laser (37) with electric energy, characterized in that the variables represented by the test signals also include the radiant power of the laser (37) and a signal produced by a monitor (49) connected to the laser.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19920200760 EP0506178B1 (en) | 1991-03-25 | 1992-03-17 | Power supply apparatus |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP91200658 | 1991-03-25 | ||
EP91200658 | 1991-03-25 | ||
EP19920200760 EP0506178B1 (en) | 1991-03-25 | 1992-03-17 | Power supply apparatus |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0506178A2 EP0506178A2 (en) | 1992-09-30 |
EP0506178A3 EP0506178A3 (en) | 1993-06-09 |
EP0506178B1 true EP0506178B1 (en) | 1996-10-16 |
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ID=26129206
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Application Number | Title | Priority Date | Filing Date |
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EP19920200760 Expired - Lifetime EP0506178B1 (en) | 1991-03-25 | 1992-03-17 | Power supply apparatus |
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EP (1) | EP0506178B1 (en) |
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DE102007008655A1 (en) | 2007-02-20 | 2008-08-21 | Henkel Ag & Co. Kgaa | Siderophore-metal complexes as bleach catalysts |
DE102007010785A1 (en) | 2007-03-02 | 2008-09-04 | Henkel Ag & Co. Kgaa | Use of superoxide dismutases to cleave and/or remove Amadori and/or Maillard products, especially as components of detergent, cosmetic or pharmaceutical products |
DE102007017656A1 (en) | 2007-04-12 | 2008-10-16 | Henkel Ag & Co. Kgaa | Biheteroaryl metal complexes as bleaching catalysts |
DE102007017657A1 (en) | 2007-04-12 | 2008-10-16 | Henkel Ag & Co. Kgaa | Tris / heterocyclyl) metal complexes as bleach catalysts |
DE102007017654A1 (en) | 2007-04-12 | 2008-10-16 | Henkel Ag & Co. Kgaa | Bis (hydroxyquinoline) metal complexes as bleaching catalysts |
DE102007036392A1 (en) | 2007-07-31 | 2009-02-05 | Henkel Ag & Co. Kgaa | Compositions containing perhydrolases and alkylene glycol diacetates |
DE102007040326A1 (en) | 2007-08-24 | 2009-02-26 | Henkel Ag & Co. Kgaa | Laundry pre-treatment agent and method |
DE102008027375A1 (en) | 2008-06-09 | 2009-12-10 | Henkel Ag & Co. Kgaa | Bacitracin-metal complexes as bleaching catalysts |
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US4019105A (en) * | 1975-09-26 | 1977-04-19 | General Electric Company | Controlled current induction motor drive |
JPS60187074A (en) * | 1984-03-07 | 1985-09-24 | Toshiba Corp | Automatic light quantity control circuit of laser diode |
DE3726243A1 (en) * | 1987-08-07 | 1989-02-16 | Kabelmetal Electro Gmbh | Circuit arrangement for regulating the power of a laser diode |
-
1992
- 1992-03-17 EP EP19920200760 patent/EP0506178B1/en not_active Expired - Lifetime
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EP0506178A2 (en) | 1992-09-30 |
EP0506178A3 (en) | 1993-06-09 |
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