Claims:1. A circuit system for analog output for LV drives in bipolar configuration, comprising:
an analog circuit configured to receive a digital input (X0), wherein the analog circuit comprising:
a buffer stage (A0) configured to convert the digital input (X0) into current amplified signal (X1), wherein the buffer stage includes a op-amp with bipolar supply;
a summing amplifier (A1) configured to receive the X1 so as to provide a summing amplifier output (X2) in accordance with a pre-set offset associated therewith; and
an error amplifier (A2) configured, based on negative feedback of the X2, to provide an error amplifier output X3 that is interfaced to an outer system;
wherein a switching means (SW1) selectively switch between either a current configuration or a voltage configuration depending upon type of the analog output of the desired bipolar configuration.
2. The circuit system as claimed in claim 1, wherein selection of the current configuration, by the SW1 for current as the type of the analog output, effectuates the X3 as negative feedback again to the A2 through a difference amplifier (A3), which provides zero error input for the A2.
3. The circuit system as claimed in claim 2, wherein gain of the A3 is adjusted in order to maintain constant current.
4. The circuit system as claimed in claim 1, wherein selection of the voltage configuration, by the SW1 for voltage as the type of the analog output, effectuates voltage feedback circuit that acts as a positive gain amplifier for the A2.
5. The circuit system as claimed in claim 1, wherein the circuit system further comprises a digital signal processor (DSP) for motor control so as to provide the X0.
6. The circuit system as claimed in claim 5, wherein the DSP output range is 0 to 3.3V, and the X0 are PWM pulses.
7. The circuit system as claimed in claim 5, wherein the pre-set offset of the A1 is (-) 1.65 V in order to map the analog output within the acceptable output range of the DSP.
8. The circuit system as claimed in claim 1, wherein the current and voltage configuration provides a current and voltage range in bipolar mode from (-) 20 mA to (+) 20 mA and (-) 10 to (+) 10 V.
9. The circuit system as claimed in claim 1, wherein the analog output for the LV drives for measurement of the analog signal is selected from the group consisting of frequency, current, and voltage.
10. The circuit system as claimed in claim 1, wherein the outer system for the X3 of the LV drives is programming logic controller (PLC).
, Description:TECHNICAL FIELD
[0001] The present disclosure generally relates to the field of electrical drive systems. In particular, the present disclosure pertains to a simple, switchable and economical circuit system with bipolar analog outputs for LV drives that maximizes operational gains among other benefits.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] LV drives for motor control find various applications such as in textiles, agriculture, elevator and the like. But they have faced severe limitations, inherently, but need not necessarily, due to demerits of unipolar analog output. Furthermore, the case of conventional LV drives wherein analogue outputs are limited to unipolar voltages or currents such as 0 to 20 mA and 0 to 10 VDC makes a case for substantial improvements in operational gains along with other enhancements.
[0004] There have also been efforts in the past to provide the analog output interface of drives for motion control with external world e.g. PLCs, actuators etc. so as to gain other sequential control along with motor control. Similarly, certain applications such as, but not limited to, analog speed, voltage, current etc. or any other digital quantity, based upon user preference among other factors, make a call for display or drive so as to simplify further procedural considerations. Moreover, industrial applications desire means to generate analog output for drives (i.e. LV drives) in bipolar configuration.
[0005] There is, therefore, a need in the art to provide a simple and efficient circuit system for bipolar analog output for LV drives so as to obviate shortcomings encountered in the pertinent art.
[0006] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0007] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0008] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0009] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0010] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

OBJECTS OF THE INVENTION
[0011] A general object of the present disclosure is to provide for a simple, switchable and economical circuit system with bipolar analog outputs for LV drives that maximizes operational gains.
[0012] An object of the present disclosure is to provide a single circuit system for both current and voltage analog output configuration by action of an integrated switching means.
[0013] Another object of the present disclosure is to provide analog output interface of drives for motion control among other functionalities.
[0014] Another object of the present disclosure is to provide bipolar configuration for LV drives that is easy to implement without compromising with industrial safety standards.
[0015] Yet another object of the present disclosure is to provide alternative to conventional LV drives with limited applications due to constraints of unipolar analog outputs.

SUMMARY
[0016] Aspects of the present disclosure generally relate to the field of electrical drive systems. In particular, the present disclosure pertains to a simple, switchable and economical circuit system with bipolar analog outputs for LV drives that maximizes operational gains among other benefits.
[0017] In an aspect, the present disclosure provides a circuit system for analog output for LV drives in bipolar configuration that includes an analog circuit configured to receive a digital input (X0), wherein the analog circuit includes (i) a buffer stage (A0) that can be configured to convert the digital input (X0) into current amplified signal (X1), wherein the buffer stage can include a op-amp with bipolar supply; (ii) a summing amplifier (A1) that can be configured to receive the X1 so as to provide a summing amplifier output (X2) in accordance with a pre-set offset associated therewith; (iii) an error amplifier (A2) that can be configured, based on negative feedback of the X2, to provide an error amplifier output X3 that is interfaced to an outer system; wherein a switching means (SW1) selectively switch between either current configuration or voltage configuration depending upon type of the analog output of the desired bipolar configuration.
[0018] In an aspect of the present disclosure, selection of current configuration, by SW1 for current as type of analog output, can effectuate X3 as negative feedback again to A2 through difference amplifier (A3), which provides zero error input for the A2, wherein gain of the A3 is adjusted in order to maintain constant current.
[0019] In an alternate aspect of the present disclosure, selection of voltage configuration, by SW1 for voltage as type of analog output, can effectuate voltage feedback circuit that can act as a positive gain amplifier for A2.
[0020] In an aspect, circuit system of the present disclosure can further comprise a digital signal processor (DSP) for motor control so as to provide X0, wherein the DSP output range can be 0 to 3.3V, and the X0 are PWM pulses. Further, pre-set offset of A1 can be (-) 1.65 V in order to map the analog output within the acceptable output range of the DSP.
[0021] In an embodiment, current and voltage configuration, in accordance with implementation of the present disclosure, can provide a current and voltage range in bipolar mode from (-) 20 mA to (+) 20 mA and (-) 10 to (+) 10 V respectively.
[0022] In an aspect, analog output for LV drives for measurement of the analog signal can be selected from the group consisting of frequency, current, and voltage.
[0023] In an embodiment, outer system for X3 of LV drives is programming logic controller (PLC).
[0024] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components

BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0026] FIG.1 illustrates an exemplary layout of circuits system for LV drive with analog output in accordance to an embodiment of the present disclosure.
[0027] FIG.2 illustrates an exemplary layout of an analog circuit in accordance to an embodiment of the present disclosure.
[0028] FIG.3 illustrates exemplary waveform for current configuration of LV drive with analog output in accordance to an embodiment of the present disclosure.
[0029] FIG.4 illustrates exemplary waveform for voltage configuration of LV drive with analog output in accordance to an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0030] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0031] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0032] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0033] Embodiments of the present disclosure generally relate to the field of electrical drive systems. In particular, the present disclosure pertains to a simple, switchable and economical circuit system with bipolar analog outputs for LV drives that maximizes operational gains among other benefits.
[0034] FIG.1 illustrates an exemplary layout of circuit system 100 for LV drive with analog output in accordance to an embodiment of the present disclosure. As illustrated, input grid 170 can be the three phase grid with R, S, and T as the 3 lines, which is rectified and the DC voltage is feed to three-phase inverter 110 so as to provide power to induction motor 180 (generally, induction motor load).
[0035] In a preferred implementation, DSP 130 can be configured to input digital pulse to analog circuit 140 while the DSP 130 can be operatively connected with inverter 110. The digital pulse, from the DSP 130 can be converted by the analog circuit 140 into an analog output (of bipolar configuration) in accordance with working of a switching means SW1 (illustrated in FIG. 2), depending upon nature of the desired analog output, whether voltage or current type.
[0036] In an aspect, DSP 130 and analog circuit 140, along with other components/parts/modules such as, but not limited to, three-phase rectifier 120 and three-phase inverter 110 of the present disclosure, can be housed within an drive system 160 that can further interconnections, of internal as well as external nature, depending upon design and/or space considerations, among others.
[0037] FIG.2 illustrates an exemplary layout of an analog circuit 140 in accordance to an embodiment of the present disclosure. In an aspect, the present disclosure provides a circuit system 100 for analog output for LV drives in bipolar configuration that can include an analog circuit 140 configured to receive a digital input (X0), which is received from DSP 130.
[0038] In a preferred aspect, analog circuit 140 (best shown with details in FIG. 2) can include (i) a buffer stage (A0) 142 that can be configured to convert the digital input (X0) into current amplified signal (X1), wherein the buffer stage can include a op-amp with bipolar supply; (ii) a summing amplifier (A1) 144 that can be configured to receive the X1 so as to provide a summing amplifier output (X2) in accordance with a pre-set offset associated therewith; (iii) an error amplifier (A2) 146 that can be configured, based on negative feedback of the X2, to provide an error amplifier output X3 that is interfaced to a outer system; wherein a switching means (SW1) selectively switch between either current configuration or voltage configuration depending upon type of the analog output of the desired bipolar configuration.

Current Configuration
[0039] In an aspect of the present disclosure, selection of current configuration, by SW1 for current as type of analog output, can effectuate X3 as negative feedback again to A2 146 through difference amplifier (A3) 150, which provides zero error input for the A2 146, wherein gain of the A3 150 is adjusted in order to maintain constant current.
[0040] Notably, in this configuration voltage feedback circuit 148 (also referred to as voltage gain and both these terms used interchangeably hereinafter) does not come into the picture as it gets shorted out by action of switching means SW1.
[0041] In an aspect, circuit system 100 of the present disclosure can further comprise a digital signal processor (DSP) 130 for motor control so as to provide X0, wherein the DSP 130 output range can be 0 to 3.3V, and the X0 can be PWM pulses. Further, pre-set offset of A1 144 can be (-) 1.65 V in order to map the analog output within the acceptable output range of the DSP 130 (i.e. 0-3.3V).
[0042] In an embodiment, current configuration, in accordance with implementation of the present disclosure, can provide a current range in bipolar mode from (-) 20 mA to (+) 20 mA.
[0043] FIG. 3 illustrates exemplary waveform for current configuration of LV drive with analog output in accordance to an embodiment of the present disclosure. Now, this figure illustrates the curve in the form of a straight line when digital input is plotted against analog output (for current) on the x (herein, AOI) and y (herein, AOI Output v/s X2) axes respectively.
[0044] In an aspect, analog output for LV drives for measurement of the analog signal can be selected from the group consisting of frequency, current, and voltage.
[0045] In an embodiment, outer system of X3 for LV drives can be a programming logic controller (PLC).

Voltage Configuration
[0046] In an alternate aspect of the present disclosure, selection of voltage configuration, by SW1 for voltage as type of analog output, can effectuate voltage feedback circuit 148 (or voltage gain) that can act as a positive gain amplifier for A2 146.
[0047] As evident, in implementation of the instant configuration of the present disclosure, difference amplifier 144 is shorted out in accordance with action of switching means SW1 while voltage gain 148 is moved into the picture.
[0048] In an embodiment, voltage configuration, in accordance with implementation of the present disclosure, can provide a voltage range in bipolar mode from (-) 10 to (+) 10 V.
[0049] FIG. 4 illustrates exemplary waveform for voltage configuration of LV drive with analog output in accordance to an embodiment of the present disclosure. As illustrated, relevant curve can be in the form of a straight line when digital input is plotted against analog output (for voltage) on the x (herein, AOV) and y (herein, AOV Output v/s X2) axes respectively.
[0050] Thus, the present disclosure provides circuits system that provides convenience of switching between current as well as voltage configuration of analog output that can be configured in bipolar mode with a wide range of -10 to +10V or -20mA to +20mA output, among other benefits as would be apparent by the present disclosure.
[0051] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0052] The present disclosure provides a simple, switchable and economical circuit system with bipolar analog outputs for LV drives that maximizes operational gains.
[0053] The present disclosure provides a single circuit system for both current and voltage analog output configuration by action of an integrated switching means.
[0054] The present disclosure provides an analog output interface of drives for motion control among other functionalities.
[0055] The present disclosure provides bipolar configuration for LV drives that is easy to implement without compromising with industrial safety standards.
[0056] The present disclosure provides alternative to conventional LV drives with limited applications due to constraints of unipolar analog outputs.