CA1202073A - Process and device for eliminating the disturbances related to the fluctuations of the load in chopped power supplies - Google Patents
Process and device for eliminating the disturbances related to the fluctuations of the load in chopped power suppliesInfo
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- CA1202073A CA1202073A CA000431750A CA431750A CA1202073A CA 1202073 A CA1202073 A CA 1202073A CA 000431750 A CA000431750 A CA 000431750A CA 431750 A CA431750 A CA 431750A CA 1202073 A CA1202073 A CA 1202073A
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Abstract
ABSTRACT OF THE DISCLOSURE
A process for eliminating the disturbances related to fluctuations of the load in chopped power supplies. A magnetic circuit with a primary inductance (Lp) is coupled to a secondary inductance (Ls). The value of the secondary inductance (Ls) is automatically adapted as a function of the voltage (Us) at the terminals of the load (X). This ensures total transfer of the magnetic energy for each period of the chopping frequency. Complete demagnetisation of the circuit is obtained at each period of the chopping frequency. This eliminates certain disad-vantages in the prior art notably saturation of the circuit material which, in the prior art, results in incapacity to translate linear flux variation, causing a large increase in current in the chopping equipment, usually transistors, and thus the possibility of damage.
A process for eliminating the disturbances related to fluctuations of the load in chopped power supplies. A magnetic circuit with a primary inductance (Lp) is coupled to a secondary inductance (Ls). The value of the secondary inductance (Ls) is automatically adapted as a function of the voltage (Us) at the terminals of the load (X). This ensures total transfer of the magnetic energy for each period of the chopping frequency. Complete demagnetisation of the circuit is obtained at each period of the chopping frequency. This eliminates certain disad-vantages in the prior art notably saturation of the circuit material which, in the prior art, results in incapacity to translate linear flux variation, causing a large increase in current in the chopping equipment, usually transistors, and thus the possibility of damage.
Description
The present invention relates to a process and device for eliminating the disturbances related to fluctuat-ions of the load in chopped power supplies comprising a mag-netic circuit with a primary inductance coupled to a second-5 ary inductance.
In energy conversion, the magnetic circuits form a type of component often neglected, which leads to saturation of the material, resulting in an incapability of translating a linear flux variation. ThiS causes an enormous increase in 10 current in the chopping means, generally ~ormed by transist-ors, when the load is variable and when the power is constant or fluctuating little. The result is disturbances in the net-work and a risk of damaging the chopping means.
The principal aim of the present invention is to 15 remedy these disadvantages and, for this, it provides a process which is essentially characterized in that it consists in automatically adapting the value of the secondary induct-ance as a function of the voltage at the terminals of the load, so as to provide a total transfer of the magnetic energy for 20 each period of the chopping frequency.
With this arrangement, complete demagnetization of the circuit is obtained at earh period of the chopping frequ-ency, which allows -the above-mentioned drawbacks to be elimin-ated.
A device for implemen-ting this process is character-ized in that it comprises a number of switching elements, connected in parallel between the load and different inter-mediate tappings on the secondary inductance, and a voltage threshold control circuit for controlling successively said 30 switching elements as a function of the voltage at the termi-nals of the load.
In a particular embodiment of the invention, the switching elements are formed by thyristors.
Preferably, the device of the invention also comp-35 rises an automatic regulation circuit for compensating theslow variations of -the voltage at the terminals of the primary inductance.
,:
~v ~ ~p This regulation circuit comprises an auxiliary low power magne-tic circuit connected in parallel across the main circuit and whose load is constant, the voltage at the term-inals of said load being used as voltage for driving the 5 chopping control, so as -to ensure a constant transfer of energy despite the fluctuations of the network.
The process of the invention may also be applied advantageously to the case where the primary inductance and the se~ondary inductance are combined in a single so-called 10 smoothing inductance. There exist in fact nUmerolJs structures in which the smoothing function is obtained by means of a cell comprising an inductor and a capacitor. Now, if the output voltage fluctuates very much, the smoothing inductor risks being saturated, which obviously reduces the smoothing 15 efficiencyO
In accordance with the invention, the value of the smoothing inductor is automatically adapted as a function of the voltage at the terminals nr the load, during the phase of restoration of the magnetic energy.
To this end, a number of switching elements are used, formed advantageously by thyristors, which are connected in parallel between the load and different intermediate tap-pings of the smoothing inductor in the magnetic energy restoration phase, and a voltage threshold control device 25 for controlling successively said switching elements as a function of the voltage at the terminals of the load.
Several embodiments of the invention are described hereafter by way of examples, with reference to the accompany-ing drawings in which :
Figure 1 is a diagram of a chopped power supply in accordance with the invention, for supplying an arc lamp of the flash type;
Figures 2a to 2c show respectively the trend of the primary current, the trend of the secondary current and the 35 trend of the control voltage of the thyristor, for one period of the chopping frequency ;
Figure 3 shows the trend of the primary current with ~2~ 3 a sinusoidal supply voltage;
Figure 4 shows the trend of the charging voltage of the energy storage capacitor;
Figure 4 is the diagram of the regulation circuit for compensating the slow variations of the supply voltage;
and Figure 6 is the diagram of another application of the invention to the smoothir.g Eunction.
The chopped power-supply shown in Figure 1 comprises first of all a magnetic circuit with a primary winding which provides an inductance Lp coupled to a secon-dary winding which provides an inductance Ls. In a way known per se, a chopping transistor Tr, controlled by a chopper K, is inserted in the primary circuit. This cir-cuit is fed from the Ac network through a diode rectifyingbridge, but without any smoothing.
The control pulses generated by chopper K on the base of the chopping transistor Tr are at a high frequency, for example 25 kHz, so as to limit the dimensions of the coils of the magnetic circuit.
When the transistor is conducting, the primary current Ip has the trend shown in the diagram of Figure 2a.
It is a current pulse of duration Y , r being the duration of conduction of the transistor. When the transistor is no longer conducting, a current pulse of duration T- Y is restored at the secondary, T being the period of the chopping frequency. The secondary current Is thus has the trend shown in the diagram of Figure 2b.
In the application envisaged here, the chopped power supply is designed to supply a xenon arc lamp X of the Elash type, i.e~ a high-speed discharge lamp under recurrent operating conditions. This type of lamp requires, for its operation, a capacitor C of high value to be previously charged during the time interval between each ionization caused on the lamp. Triggering of the lamp is ensured here by a low frequency source BF.
The process of the invention consists in automa-tically adapting the value of the secondary inductance Ls as a function of the voltage Us at the terminals oE the load, which voltage is obviously extremely variable in the case of a flash type lamp, so as to ensure total transfer of the magnetic energy for each period of the chopping frequency and thus to obtain complete demagnetization of the circuit.
The energy transfer per period of the chopping fre-quency is expressed by:
W = 1 Lp Ip2 or W = ~ Ls Is2 When the energy is restored at the secondary, the voltage across this latter is imposed during the duration T - ~ by the high time constant oE the load. The demagnetiza-tion time is then defined by LENZ's law, namely Us = Ls Is, whence Ls = Us (T- r T -Y Is From the energy transfer relationshipr it is deduced that Is = ~ , whence Ls = Us2 (T-2~ )2 .
If we now assume ~ constant, we may assume (T- r )2 = k = constant, so that finally the 2w following relationship is obtained : Ls = k Us.
The implementation of the process of the invention consists then in switching the value of the secondary inductance Ls by means of a control device comprising several voltage thresholds staggered with respect to the secondary voltage Us, each threshold causing the control of the value of an inductance capable of satisfying the relationship Ls = k Us2. Of course, since it is a question of an inductance jump control, this rela-tionship will be maintained at a limit value, so as to obtain complete demagnetization of the circuit.
To this end, a certain number oE taps are provided on the windings which provides the secondary inductance Ls. Such taps are connected to the load through unidirectional power switching elements only able to admit current when the chopping transistor Tr is no longer conducting, i.e. during the magnetic energy restoration phase.
In the particular embodiment described here, the switching elements are three in number. The first two are .~.,.~.,~
formed by thyristors Thl and Th2, whereas the third one is formed by a simple diode D. The gates of the two thyristors are connected to a voltage threshold control device COM3 responsive to the output voltage Us at the terminals of the 5 lamp X.
.
For a low value of the output uoltage Us, only the diode D is operative and ensures demangetization of the circuit in the time (T- r). Thenl for a higher value of the voltage Us, thyristor Thl is triggered by means of a voltage 10 pulse generated on its gate by the threshold device COM. This pulse has the trend shown in the diagram of figure 2c and it is synchronized with the chopping frequency, through a synch-ronizing cunnection S provided between the chopper K and the threshold device COM. lt will be noted that when thyristor 15 Thl is conducting, diode D is automatically subjected to a reverse potential which no longer allows it to conduct.
For a still higher value of the voltage Us, thyr-istor Th2 is triggered by the threshold device COM. The diode ~ and thyristor Thl are then reversely biassed and can no 20 longer conduct, even if the gate control is maintained on Thi, this being the direct consequence of the distribution of the potentials at the terminals of the secondary inductance.
The strict application of demagnetization process of the invention allows the primary inductance Lp to take 25 energy, at each pulse, proportional to the voltage of the net-work, without a main control loop. It is a question of instant aneous energy self-modulation related to the sinusoidal volt-age of the supply network, and this despite the very large variation of the voltage at the terminals of the load, which 30 may be easily a ratio of ten.
Consequently, the energy distribution network is not damaged, the current being taken from this latter according to a sinusoidal law and in phase with the voltage of the network, as illustrated by the diagram oF figur0 3.
Similarly, the power taken from the network i9 con-stant, the load on capacitor C responding to this condition since it is of the form Uc = ~, as illustrated by the diagram of figure 4. The envelope of the sinusoidal current is then constant.
~ lowever, it often happens that the network is not perfec-t. In this case, and so as to overcome the slow variat-5 ions of the mains, a regulation circuit REG may be providedfor obtaining information proportional to the energy trans-ferred across the load.
This circuit REG is shown in detail in figure 5 and is formed essentially of a low power maynetic circuit 10 comprising a primary inductance Ll coupled to a secondary inductance L2. The inductance Ll is connected in parallel across the primary inductance Lp of the main magnetic circuit through a diode Dl, whereas the inductance L2 is connected across a constant load formed of two resistors Rl and R2, 15 through a diode D2 and a capacitor Cl.
Thus, the same chopping transistor Tr controls the two magnetic circuits, the purpose of diode Dl being to make the restoration of energy of the auxiliary magnetic circuit Ll/L2 independentof the charge state of capacitor C intended 20 to supply the flash-lamp X with power.
Inductance L2 restores its energy accumulated during the time (T- ~) through diode D2 and the integrator Cl,Rl+R2.
Since the load Rl+R2 is constant, the voItage at the terminals of R2 is the image of the mean voltage Ur from the main rectif-25 ication for ~ cons-tant. This voltage at the terminals of R2 is then applied to the feedback circuit of chopper K so as to modify the time 1~as a functior, of the fluctuations of the mains and thus to ensure a constant energy transfer to capacitor ~. Consequently, this latter will always be charged 30 to the same value at the time preceding the discharge. The demagnetization process of the invention may alsa be applied advantageously to the smoothing function. There exist in fact numerous structures in which the smoothing function is obtained by means of a cell comprising an inductanceL and a capacitor C, 35 as in the example shown in figure 6.
In this application, the function of the smoothing inductance L is dual. The same winding serves for limiting ~Z~Z~3 the current in the conducting phase of the chopping trans-istor Tr, controlled by chopper Kl, then restores its energy when this latter is disabled.
Now, for the applications where the output voltage at the terminals of load P is very fluctuating and may more especially be substantially less than the nominal voltage, -the smoothing inductance requires a relatively long demagnet-ization time, which leads it to saturation.
In accordance with the invantion, and as in the example described earilier, a diode D and two thyristors Th and Th2 controlled by a voltage threshold device COM are connected to intermediate tappings of the smoothing inductance L. The threshold dsvice COM, in relation with the output voltage, adapts the value of the inductance in the restoration phase, so as to maintain a constant demagne-tization time.
Thus, the inductance does not have to withstand the passage of an excessive DC current component, which risks saturating it, thus allowing the efficiency of the smoothing filter to be maintained despite high current variations.
In energy conversion, the magnetic circuits form a type of component often neglected, which leads to saturation of the material, resulting in an incapability of translating a linear flux variation. ThiS causes an enormous increase in 10 current in the chopping means, generally ~ormed by transist-ors, when the load is variable and when the power is constant or fluctuating little. The result is disturbances in the net-work and a risk of damaging the chopping means.
The principal aim of the present invention is to 15 remedy these disadvantages and, for this, it provides a process which is essentially characterized in that it consists in automatically adapting the value of the secondary induct-ance as a function of the voltage at the terminals of the load, so as to provide a total transfer of the magnetic energy for 20 each period of the chopping frequency.
With this arrangement, complete demagnetization of the circuit is obtained at earh period of the chopping frequ-ency, which allows -the above-mentioned drawbacks to be elimin-ated.
A device for implemen-ting this process is character-ized in that it comprises a number of switching elements, connected in parallel between the load and different inter-mediate tappings on the secondary inductance, and a voltage threshold control circuit for controlling successively said 30 switching elements as a function of the voltage at the termi-nals of the load.
In a particular embodiment of the invention, the switching elements are formed by thyristors.
Preferably, the device of the invention also comp-35 rises an automatic regulation circuit for compensating theslow variations of -the voltage at the terminals of the primary inductance.
,:
~v ~ ~p This regulation circuit comprises an auxiliary low power magne-tic circuit connected in parallel across the main circuit and whose load is constant, the voltage at the term-inals of said load being used as voltage for driving the 5 chopping control, so as -to ensure a constant transfer of energy despite the fluctuations of the network.
The process of the invention may also be applied advantageously to the case where the primary inductance and the se~ondary inductance are combined in a single so-called 10 smoothing inductance. There exist in fact nUmerolJs structures in which the smoothing function is obtained by means of a cell comprising an inductor and a capacitor. Now, if the output voltage fluctuates very much, the smoothing inductor risks being saturated, which obviously reduces the smoothing 15 efficiencyO
In accordance with the invention, the value of the smoothing inductor is automatically adapted as a function of the voltage at the terminals nr the load, during the phase of restoration of the magnetic energy.
To this end, a number of switching elements are used, formed advantageously by thyristors, which are connected in parallel between the load and different intermediate tap-pings of the smoothing inductor in the magnetic energy restoration phase, and a voltage threshold control device 25 for controlling successively said switching elements as a function of the voltage at the terminals of the load.
Several embodiments of the invention are described hereafter by way of examples, with reference to the accompany-ing drawings in which :
Figure 1 is a diagram of a chopped power supply in accordance with the invention, for supplying an arc lamp of the flash type;
Figures 2a to 2c show respectively the trend of the primary current, the trend of the secondary current and the 35 trend of the control voltage of the thyristor, for one period of the chopping frequency ;
Figure 3 shows the trend of the primary current with ~2~ 3 a sinusoidal supply voltage;
Figure 4 shows the trend of the charging voltage of the energy storage capacitor;
Figure 4 is the diagram of the regulation circuit for compensating the slow variations of the supply voltage;
and Figure 6 is the diagram of another application of the invention to the smoothir.g Eunction.
The chopped power-supply shown in Figure 1 comprises first of all a magnetic circuit with a primary winding which provides an inductance Lp coupled to a secon-dary winding which provides an inductance Ls. In a way known per se, a chopping transistor Tr, controlled by a chopper K, is inserted in the primary circuit. This cir-cuit is fed from the Ac network through a diode rectifyingbridge, but without any smoothing.
The control pulses generated by chopper K on the base of the chopping transistor Tr are at a high frequency, for example 25 kHz, so as to limit the dimensions of the coils of the magnetic circuit.
When the transistor is conducting, the primary current Ip has the trend shown in the diagram of Figure 2a.
It is a current pulse of duration Y , r being the duration of conduction of the transistor. When the transistor is no longer conducting, a current pulse of duration T- Y is restored at the secondary, T being the period of the chopping frequency. The secondary current Is thus has the trend shown in the diagram of Figure 2b.
In the application envisaged here, the chopped power supply is designed to supply a xenon arc lamp X of the Elash type, i.e~ a high-speed discharge lamp under recurrent operating conditions. This type of lamp requires, for its operation, a capacitor C of high value to be previously charged during the time interval between each ionization caused on the lamp. Triggering of the lamp is ensured here by a low frequency source BF.
The process of the invention consists in automa-tically adapting the value of the secondary inductance Ls as a function of the voltage Us at the terminals oE the load, which voltage is obviously extremely variable in the case of a flash type lamp, so as to ensure total transfer of the magnetic energy for each period of the chopping frequency and thus to obtain complete demagnetization of the circuit.
The energy transfer per period of the chopping fre-quency is expressed by:
W = 1 Lp Ip2 or W = ~ Ls Is2 When the energy is restored at the secondary, the voltage across this latter is imposed during the duration T - ~ by the high time constant oE the load. The demagnetiza-tion time is then defined by LENZ's law, namely Us = Ls Is, whence Ls = Us (T- r T -Y Is From the energy transfer relationshipr it is deduced that Is = ~ , whence Ls = Us2 (T-2~ )2 .
If we now assume ~ constant, we may assume (T- r )2 = k = constant, so that finally the 2w following relationship is obtained : Ls = k Us.
The implementation of the process of the invention consists then in switching the value of the secondary inductance Ls by means of a control device comprising several voltage thresholds staggered with respect to the secondary voltage Us, each threshold causing the control of the value of an inductance capable of satisfying the relationship Ls = k Us2. Of course, since it is a question of an inductance jump control, this rela-tionship will be maintained at a limit value, so as to obtain complete demagnetization of the circuit.
To this end, a certain number oE taps are provided on the windings which provides the secondary inductance Ls. Such taps are connected to the load through unidirectional power switching elements only able to admit current when the chopping transistor Tr is no longer conducting, i.e. during the magnetic energy restoration phase.
In the particular embodiment described here, the switching elements are three in number. The first two are .~.,.~.,~
formed by thyristors Thl and Th2, whereas the third one is formed by a simple diode D. The gates of the two thyristors are connected to a voltage threshold control device COM3 responsive to the output voltage Us at the terminals of the 5 lamp X.
.
For a low value of the output uoltage Us, only the diode D is operative and ensures demangetization of the circuit in the time (T- r). Thenl for a higher value of the voltage Us, thyristor Thl is triggered by means of a voltage 10 pulse generated on its gate by the threshold device COM. This pulse has the trend shown in the diagram of figure 2c and it is synchronized with the chopping frequency, through a synch-ronizing cunnection S provided between the chopper K and the threshold device COM. lt will be noted that when thyristor 15 Thl is conducting, diode D is automatically subjected to a reverse potential which no longer allows it to conduct.
For a still higher value of the voltage Us, thyr-istor Th2 is triggered by the threshold device COM. The diode ~ and thyristor Thl are then reversely biassed and can no 20 longer conduct, even if the gate control is maintained on Thi, this being the direct consequence of the distribution of the potentials at the terminals of the secondary inductance.
The strict application of demagnetization process of the invention allows the primary inductance Lp to take 25 energy, at each pulse, proportional to the voltage of the net-work, without a main control loop. It is a question of instant aneous energy self-modulation related to the sinusoidal volt-age of the supply network, and this despite the very large variation of the voltage at the terminals of the load, which 30 may be easily a ratio of ten.
Consequently, the energy distribution network is not damaged, the current being taken from this latter according to a sinusoidal law and in phase with the voltage of the network, as illustrated by the diagram oF figur0 3.
Similarly, the power taken from the network i9 con-stant, the load on capacitor C responding to this condition since it is of the form Uc = ~, as illustrated by the diagram of figure 4. The envelope of the sinusoidal current is then constant.
~ lowever, it often happens that the network is not perfec-t. In this case, and so as to overcome the slow variat-5 ions of the mains, a regulation circuit REG may be providedfor obtaining information proportional to the energy trans-ferred across the load.
This circuit REG is shown in detail in figure 5 and is formed essentially of a low power maynetic circuit 10 comprising a primary inductance Ll coupled to a secondary inductance L2. The inductance Ll is connected in parallel across the primary inductance Lp of the main magnetic circuit through a diode Dl, whereas the inductance L2 is connected across a constant load formed of two resistors Rl and R2, 15 through a diode D2 and a capacitor Cl.
Thus, the same chopping transistor Tr controls the two magnetic circuits, the purpose of diode Dl being to make the restoration of energy of the auxiliary magnetic circuit Ll/L2 independentof the charge state of capacitor C intended 20 to supply the flash-lamp X with power.
Inductance L2 restores its energy accumulated during the time (T- ~) through diode D2 and the integrator Cl,Rl+R2.
Since the load Rl+R2 is constant, the voItage at the terminals of R2 is the image of the mean voltage Ur from the main rectif-25 ication for ~ cons-tant. This voltage at the terminals of R2 is then applied to the feedback circuit of chopper K so as to modify the time 1~as a functior, of the fluctuations of the mains and thus to ensure a constant energy transfer to capacitor ~. Consequently, this latter will always be charged 30 to the same value at the time preceding the discharge. The demagnetization process of the invention may alsa be applied advantageously to the smoothing function. There exist in fact numerous structures in which the smoothing function is obtained by means of a cell comprising an inductanceL and a capacitor C, 35 as in the example shown in figure 6.
In this application, the function of the smoothing inductance L is dual. The same winding serves for limiting ~Z~Z~3 the current in the conducting phase of the chopping trans-istor Tr, controlled by chopper Kl, then restores its energy when this latter is disabled.
Now, for the applications where the output voltage at the terminals of load P is very fluctuating and may more especially be substantially less than the nominal voltage, -the smoothing inductance requires a relatively long demagnet-ization time, which leads it to saturation.
In accordance with the invantion, and as in the example described earilier, a diode D and two thyristors Th and Th2 controlled by a voltage threshold device COM are connected to intermediate tappings of the smoothing inductance L. The threshold dsvice COM, in relation with the output voltage, adapts the value of the inductance in the restoration phase, so as to maintain a constant demagne-tization time.
Thus, the inductance does not have to withstand the passage of an excessive DC current component, which risks saturating it, thus allowing the efficiency of the smoothing filter to be maintained despite high current variations.
Claims (11)
1. A chopped voltage supply comprising:
a magnetic circuit, a pair of input terminals, chopping transistor means connecting said input terminals to said magnetic circuit and arranged to operate periodi-cally to build up magnetic energy in said magnetic circuit during an initial portion of each period of operation, said magnetic circuit including a tapped winding for transfer of energy to a load during the remaining portion of each period of operation, said winding having end terminals and a plurality of tap terminals, a pair of load terminals for connection to a load, a connection between one of said winding terminals and one load terminal and a plurality of switch elements connected between others of said winding terminals and the other load terminal, and a voltage threshold control circuit coupled to said load terminals and coupled to said switch elements for controlling conduc-tion of said switch elements to control the value of the inductance of said winding which is connected in series with the load and to regulate the load voltage.
a magnetic circuit, a pair of input terminals, chopping transistor means connecting said input terminals to said magnetic circuit and arranged to operate periodi-cally to build up magnetic energy in said magnetic circuit during an initial portion of each period of operation, said magnetic circuit including a tapped winding for transfer of energy to a load during the remaining portion of each period of operation, said winding having end terminals and a plurality of tap terminals, a pair of load terminals for connection to a load, a connection between one of said winding terminals and one load terminal and a plurality of switch elements connected between others of said winding terminals and the other load terminal, and a voltage threshold control circuit coupled to said load terminals and coupled to said switch elements for controlling conduc-tion of said switch elements to control the value of the inductance of said winding which is connected in series with the load and to regulate the load voltage.
2. In a chopped voltage supply as defined in claim 1, said switching elements being formed by thyristors.
3. In a chopped voltage supply as defined in claim 1, said magnetic circuit including a primary winding separate from said tapped winding and connected to said chopping transistor means, and an automatic regulation cir-cuit connected to terminals of said primary winding and to said chopping transistor means for compensating for relati-vely slow variations in the voltage at said primary winding terminals.
4. In a chopped voltage supply as defined in claim 3, said regulation circuit comprising a separate auxiliary low power magnetic circuit having a winding con-nected in parallel relation to said primary winding, auxi-liary load means connected to said auxiliary magnetic circuit to provide a substantially constant load, and means coupling said chopping transistor means to said auxiliary load means for control of said chopping transistor means in response to the voltage of said auxiliary load means.
5. In a chopped voltage supply as defined in claim 1, said chopping transistor means being connected to terminals of said winding to utilize said winding both in building up magnetic energy during said initial portion of each period of operation in transferring energy to the load during the remaining portion of each cycle of operation.
6. In a chopped voltage supply as defined in claim 5, means connecting said chopping transistor means, said tapped winding and the load in series relation to each other and to provide a series circuit between said input terminals.
7. In a chopped voltage supply as defined in claim 5, said switching elements being formed by thyristors.
8. In a chopped voltage supply as defined in claim 1, said tapped winding terminals including a first terminal connected to said one load terminal, a second terminal connected to one of said switching elements, a third terminal at a tap between said first and second ter-minals and connected to another of said switching elements, and a fourth terminal at a tap intermediate said third ter-minal and said first terminal, and a diode connected bet-ween said fourth terminal and said other load terminal and arranged to conduct during said remaining portion of a period of operation when said switching elements are so controlled as to be non-conductive.
9. In a chopped voltage supply as defined in claim 8, said magnetic circuit including a primary winding separate from said tapped winding and connected to said chopping transistor means.
10. In a chopped voltage supply as defined in claim 8, one of said input terminals being connected to said other load terminal, and said chopping transistor means being connected between the other input terminal and a winding terminal other than said first terminal thereof.
11. In a method for eliminating disturbances related to load fluctuations in a chopped voltage supply which includes a magnetic circuit with a winding for con-nection in circuit with a load, the steps of providing a plurality of taps on the winding for connection of the winding in series relation to the load, operating periodi-cally at a certain frequency to build up magnetic energy in said magnetic circuit during an initial portion of each period of operation and to transfer energy from the magne-tic circuit to the load through current flow through the winding and load during the remaining portion of each period of operation, sensing changes in the voltage applied to the load from the winding, and switching from one tap to another of the winding as required to change the inductance of the magnetic circuit in series with one load and main-tain the load voltage within certain limits and to obtain by the end of each period of operation a substantially total transfer of the magnetic energy to the load and a substantially complete demagnetization of the circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000431750A CA1202073A (en) | 1983-07-04 | 1983-07-04 | Process and device for eliminating the disturbances related to the fluctuations of the load in chopped power supplies |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000431750A CA1202073A (en) | 1983-07-04 | 1983-07-04 | Process and device for eliminating the disturbances related to the fluctuations of the load in chopped power supplies |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1202073A true CA1202073A (en) | 1986-03-18 |
Family
ID=4125609
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000431750A Expired CA1202073A (en) | 1983-07-04 | 1983-07-04 | Process and device for eliminating the disturbances related to the fluctuations of the load in chopped power supplies |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1202073A (en) |
-
1983
- 1983-07-04 CA CA000431750A patent/CA1202073A/en not_active Expired
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