Claims:1. A system for providing a high voltage power supply to regulate an output voltage, the system comprising:
at least one primary side, preferably an auxiliary winding, adapted to generate at least an auxiliary voltage;
at least one sensing means, preferably a controller, adapted to:
sense the auxiliary voltage generated;
compare the auxiliary voltage sensed with at least a pre-defined set of reference voltage values; and
generate at least one output in a form of a current reference;
at least one comparator adapted to compare a required current with the current reference generated for the auxiliary voltage to generate at least a pulse width modulation (PWM), the required current is a current essential to operate at least one device connected to the system;
at least one Silicon Carbide (SiC) power device adapted to:
receive the pulse width modulation (PWM) generated; and
switch the pulse width modulation (PWM) received to regulate the pulse width modulation (PWM) at high frequency as required to operate the device connected to the system.

2. The system as claimed in claim 1 is adapted to provide a primary side regulation.

3. The system as claimed in claim 1, wherein if the auxiliary voltage or the current of the Silicon Carbide (SiC) power device is beyond a range of a protection threshold, the PWM generation is stopped, and the Silicon Carbide (SiC) power device stops conducting current in case of faults.

4. A system for providing a high voltage power supply to regulate an output voltage, the system comprising:
an auxiliary winding, adapted to generate at least an auxiliary voltage;
at least one converter comprising at least one silicon carbide (SiC) switching device adapted to:
receive at least a pulse width modulation (PWM) generated; and
switch the pulse width modulation (PWM) received to regulate the pulse width modulation (PWM) at high frequency as required to operate at least a device connected to the system.

5. The system as claimed in claim 4 is adapted to generate a high voltage up to 1200V input, preferably from a 230V ac input, and preferably from a 350V max DC power supplies.

6. The system as claimed in claim 1 and claim 4 is adapted to: eliminate requirement of a secondary regulation component;
achieve less losses so achieves small heat sink; and
have a compact size;

7. The system as claimed in claim 1 and claim 4 is adapted to: operate at a higher frequency and requires less size filtering components, thereby consequently have less bulky filters in secondary.
, Description:TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to high voltage power supply, and more particularly relates to primary side voltage/current regulation.

BACKGROUND

[002] Conventional power supplies, such as flyback converters, operate by regulating the output voltages through secondary feedback which involves secondary isolation through opto-coupler, secondary PI controller to regulate the voltage and bias supply, which makes the system bulky, costly and also lossy as shown in figure 1. The flyback converter is a buck-boost converter with the inductor split to form a transformer, so that the voltage ratios are multiplied with an additional advantage of isolation. Figure 1 is the prior art wherein limitation may come if one used a single device wherein controller and device are integrated has input voltage limitation which is limited to 600V-700V DC as the blocking voltage.

[003] The above-described deficiencies of today's regulating the output voltages through secondary feedback are merely intended to provide an overview of some of the problems of conventional systems, and are not intended to be exhaustive. Other problems with conventional systems and corresponding benefits of the various non-limiting embodiments described herein may become further apparent upon review of the following description.

SUMMARY OF THE INVENTION

[004] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[005] An object of the present invention is to provide a primary side regulation of the voltage to eliminate the requirement of secondary opto-coupler and regulatory circuits.

[006] Another object of the present invention is to match with requirement of high voltage up to 1200V input, usually from 230V ac input, and 350V max DC power supplies are available.

[007] Still another object of the present invention is to reduce the switching losses and also the conduction losses by using Silicon Carbide (Si-C) / (SiC) power devices in the conventional converters thereby providing a compact circuit and less requirement of the heat sink size.

[008] Accordingly, the present invention provides a system for a primary side regulation. The system comprises an auxiliary winding primary side from which a feedback is received (as primary voltage is reflection of secondary voltages by turns ratio (n), where n= n1/n2, where n1 = auxiliary and n2 = secondary winding turns; a Si-C device which reduces losses and hence heat sink requirement and hence compact system, catering to high voltages, a high frequency transformer, and a secondary circuits.

[009] In contrast to the existing prior-art, the present invention discloses introduction of a new generation device which eliminates requirement of the secondary circuits/compoents and the requirement of primary auxillary circuits for regulating the output voltages for unregulated input voltages because of primary side regulation. Further, the present invention, the new generation device, is used for high voltage SMPS/primary side regulation, -so the secondary components like isolation and compensating elements are eliminated, the PCB foot print is reduced and hence is compact in size.

[0010] In contrast with the existing convertors and available prior-art, the present invention achieves below mentioned technical advancement and benefits:
1. The present invention provides an input side regulation.
2. The present invention enables less losses and less heat dissipation.
3. The present invention, due to less utilization of components, is of compact size and hence have is cheaper as compared to the existing prior-art.
4. By the implementation of the present invention there is no requirement of the isolation between the primary and secondary circuits.
5. Use of Si-C device in the present invention helps in reducing losses and heat sink size so compact system and less heat dissipation.

[0011] In one implementation, the present invention uses a Si-C as compared to Si devices in power supply applications, where Si MOSFET has lower thermal conductivity (3 times of Si devices), high breakdown field (10 times of Si devices), and the less packaging requirement. Further, a single Si-C device, as used in the present invention, suffices the requirement to cater the full supply voltages, instead of using two Si devices of half the system ratings in convention systems. Also, the usage and properties of Si-C are well know, however, the usage of emerging device (including Si-C) in SMPS (high power SMPS) to explore the advantages of compact, better thermal conductivity SMPS working in severs environmental conditions adds technical benefits to the present invention.

[0012] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0013] Figure 1 illustrates a conventional power supply with secondary feedback.

[0014] Figure 2 illustrates a power topology for fly back SMPS with primary side regulation from auxiliary winding with multiple secondary’s, in accordance with an embodiment of the present subject matter.

[0015] Figure 3 illustrates a control technique, in accordance with an embodiment of the present subject matter.

[0016] Figure 4 illustrates a flow-chart having the system and control operation, in accordance with an embodiment of the present subject matter.

[0017] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0018] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0019] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0020] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0021] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0022] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0023] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0024] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0025] A person skilled in the art that:
i. High voltage input in case of three phase drives with 400-450V AC input/PV string inverters up to 1.5kV is required.
ii. Also the requirement where cost and size is the constraint as in this technique secondary side regulation is eliminated and hence the secondary components are removed too and the same operation is performed in primary side regulation and hence no –isolation components are required.
iii. Due to secondary side regulation also the SMPS control becomes complex and also the compensation component count goes up including isolation requirement
iv. Also the new generation SiC device helps in reducing the thermal requirement due to its fewer losses and also the system becomes compact.
v. Single SiC device is available upto 1700V can be used with fewer losses as compared to two Si devices or single Si device with very high RDSon.(on - resistance)

[0026] Thus address the above requirements and to solve the above mentioned technical problems, the present invention provides a system utilizing SiC device (new generation device), a primary side voltage regulation, and elimination of secondary side feedback components.

[0027] Referring now to figure 2 the main components of the present invention are illustrated. As shown in figure 2, the main components of the present invention comprises an auxiliary winding primary side from which a feedback is received (as primary voltage is reflection of secondary voltages by turns ratio (n), where n= n1/n2, where n1 = auxiliary and n2 = secondary winding turns; a Si-C device which reduces losses and hence heat sink requirement and hence compact system, catering to high voltages, a high frequency transformer, and a secondary circuits.

[0028] In one implementation, the working principle of the present invention may be based on fly back conversion of the input voltage with multiple secondary regulations.

[0029] The steps below explain the working of the present invention in accordance with the figure 2. However, it may be noted that the working shal not restricted to the below mentioned steps and such steps are only provided for understanding purpose.

[0030] At step 1, the high voltage input is applied across the primary of the high frequency transformer, through the device as mentioned earlier as the switching device which switches the input voltage at high frequency of 50 kHz.

[0031] At step 2, initially, the pulse width modulation (PWM) pulses are generated by the controller (Digital signal processor, DSP) and the auxiliary voltage is generated, which will be the reflection of the secondary voltage as explained earlier in the same point.

[0032] At step 3, the auxiliary voltage is sensed by the controller and it is compared with the set point (i.e. the required reference in order regulate the output voltage to the required level) and the output of the comparator will serve as current reference to the another cascaded comparator which will compare the actual current (device current) with the reference current generated from the voltage comparator and this will serve as PWM pulses for the new generation device.

[0033] At step 4, in accordance with the PWM generated for the required regulated voltage the device will switch at 50 kHz and based on the turns ration and the feedback from the auxiliary winding the output voltage will be regulated.

[0034] Referring again to figure 2, a power topology for fly back SMPS with primary side regulation from auxiliary winding with multiple secondary’s is illustrated in accordance with an embodiment of the present invention. As shown in figure 2, the primary side regulation topology for high voltage SMPS with multiple output regulation, here the input voltage is applied across the primary winding of the HF transformer in series with the element (SiC device) which switches the input voltage at high frequency of about 50 kHz during the Ton i.e. on time of the device. During OFF time the the energy stored in the core of the transformer is dumped in the secondary winding which produces the output voltage based on the turns ratio between primary and respective secondary winding, duty cycle as well as the primary side regulation from the auxiliary winding which is the reflection of the secondary winding and this auxiliary winding voltage is sensed by the processor and the output voltage is regulation by the controlling the duty cycle of the switch, This is explained in detailed in flowchart as in figure 4.

[0035] Referring now to figure 3, a control technique in accordance with an embodiment of the present invention is illustrated. The PWM generation block as shown in the figure 3, is generated from the auxillary voltage taken as feedback which is the reflection of the secondary voltage and it is sampled at the valley point where secondary current is zero and hence this will serve as actual output voltage reflection without any diode drop. Here inner current control loop is used which is faster than voltage loop is used which is used to constrain the peak current and hence accurate current control protection is obtained.

[0036] Referring now to figure 4, a flow-chart explaining the control topology as shown in figure 3 and explained therein. As shown in figure 4, if auxiliary voltage or current of the device is going out of range of the protection threshold then the PWM generation will be stopped and device will stop conducting in case of faults.

[0037] In one implementation, the present invention is adapted to eliminate requirement of a secondary regulation component; achieve less losses so achieves small heat sink; and have a compact size. Further, the present invention operate at a higher frequency and requires less size filtering components, thereby consequently have less bulky filters in secondary.

[0038] Apart from what is disclosed above, the technical benefit achieved by the present invention is that the present invention as compared to the prior-art devices is less bulky, is capable to operate at high frequency i.e., can go up to higher operating frequency of order of 200kHz and above. The present invention avoids requirement of a secondary PI compensators. Further, the present invention is achieves high voltage operation from input.

[0039] In one example, for rating of 50W or 100W, a single device with same package instead of 2 or almost half the size of heat sink is required, as compared to Si device as on-state resistance is in milliohms 2-5) as opposed to on-state resistance of ohms (5-20) for the Si device. So efficiency more than 85% can be availed.

[0040] Figure 3 is the control circuit / controller control loops responsible for generating switching signals for switching the device in order to regulate the output voltages taking primary side sensing as input. Here auxiliary winding is on primary side.

[0041] It may be clearly understood by a person skilled in the art that for the purpose of convenient and brief description, for a detailed working process of the foregoing system, devices, and unit, reference may be made to a corresponding process in the foregoing device/apparatus embodiments, and details are not described herein again.

[0042] In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and device may be implemented in other manners. For example, a plurality of units or components or mechanisms may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.

[0043] The various mechanisms described as separate parts may or may not be physically separate, and the parts displayed as mechanisms may or may not be physical units, may be located in one position, or may be distributed at various location of the device. Some or all of the units may be selected to achieve the objective of the solution of the embodiment according to actual needs.

[0044] In addition, the mechanisms in the embodiments of the present invention may be integrated into one processing unit, or each of the mechanisms may exist alone physically, or two or more mechanisms may be integrated into one mechanism.

[0045] Although high voltage power supply with input side regulation disclosed, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations of high voltage power supply with input side regulation.