WO2021221680A1

WO2021221680A1 - Dynamically altering capacitance value of capacitors

Info

Publication number: WO2021221680A1
Application number: PCT/US2020/030879
Authority: WO
Inventors: Bartley Mark Hirst; David M. VITTOE
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2021-11-04

Abstract

Example implementations relate to a snubber capacitor. An example apparatus can include a portion of an electric circuit, a first capacitor, and a second capacitor placed in parallel with the first capacitor. The second capacitor can be switched off from the electric circuit, via a transistor, in response to determining an input voltage is at or below a threshold value and a capacitance value of the apparatus is dynamically altered relative to the input voltage.

Description

DYNAMICALLY ALTERING CAPACITANCE VALUE OF CAPACITORS

Background

[0001] Electronic devices include central processing units (CPUs) and other voltage transformation circuits. These transformation circuits can be electric components that protect switching elements of the circuits during activation and/or deactivation of the circuits.

Brief Description of the Drawings

[0002] Figure 1 A illustrates an example of an apparatus including a first capacitor placed in parallel with a second capacitor in accordance with the present disclosure.

[0003] Figure 1 B illustrates an example of an apparatus including a first capacitor placed in series with a second capacitor in accordance with the present disclosure.

[0004] Figure 2A illustrates an example diagram of a system including a controller and a transformer isolated DC to DC converter with a series dynamic snubber capacitor in accordance with the present disclosure.

[0005] Figure 2B illustrates an example diagram of a system including a transformer isolated DC to DC converter with a parallel dynamic snubber capacitor in accordance with the present disclosure.

[0006] Figure 3 illustrates a block diagram of an example method in accordance with the present disclosure. Detailed Description

[0007] Electronic devices can include electric components comprising electric circuits for transmitting electric current. In some examples, a capacitor (e.g., a snubber capacitor) may be used as part of an electric circuit for power conversion. Such electronic devices include CPUs and other voltage transformation circuits (alternating current (AC) to direct current(DC), DC to DC (Buck converters, etc.). These circuits can include snubbing components that protect various switching elements during activation and/or deactivation. As used herein, the term “snubber capacitor” refers to a device used to suppress or “snub” voltage transients in an electrical system.

[0008] Snubber capacitors can be used in electric circuits for reducing or eliminating voltage or current spikes, reducing electromagnetic interference (EMI), reducing losses caused by switching operations, shaping load lines, and/or transferring power dissipation to resistors. Further, snubber capacitors can be used in switch mode power supplies to reduce energy losses in the switching power transistors as they transition through a linear region of operation. Snubber capacitors while useful for reducing electromagnetic interference (EMI) can result in a loss of energy. In some examples, regular capacitors can be used to alter the characteristics of an electric circuit due to parasitic inductive or capacitive elements so as to reduce radiated or conducted electromagnetic emissions. As used herein, the term “regular capacitor” refers to capacitors other than snubber capacitors used in an electric circuit.

[0009] In some instances, snubber capacitors can cause excessive energy loss as the snubbed energy in the snubber capacitor dissipates when the snubber capacitor is reset. The excessive energy losses can impact a products ability to meet Eco-label requirements (e.g., Environmental Protection Agency and U.S. Department of Energy’s Energy Star program). This can cause manufacturers to receive penalties and drive up cost.

[0010] In some other approaches, the energy use of a product may be reduced through CPU commands to place subsystems into sleep modes such as the control panel, or by altering the operating voltage of the AC to DC power supply. However, such approaches may still cause energy loss,

[0011] In contrast, examples of the present disclosure allow for dynamic component switching to reduce energy loss and/or consumption in desired operating modes. Altering the capacitance value of the snubber capacitor dynamically, responsive to a determination that a system is in a low power mode or sleep mode, can reduce energy losses and help meet regulatory requirements. As described herein, the term “dynamically" refers to variable and or constant changing in response to a particular influence. For instance, the capacitance value of the capacitor may variably and/or constantly change based on system/firmware power status (e.g., changes in system/firmware power statuses).

[0012] Figure 1A illustrates an example of an apparatus 100 including a a first capacitor 106 placed in parallel with a second capacitor 108 in accordance with the present disclosure. The apparatus 100 can include a snubber capacitor circuit 104-1 of an electric circuit 104. The snubber capacitor circuit 104-1 can be an energy-absorbing circuit portion of the electric circuit used to suppress voltage spikes caused by the electric circuit's inductance when an electrical transistor (e.g., switch) opens (e.g., turns off).

[0013] In some examples, the apparatus 100 can include a first transistor 132. As used herein, the term “transistor” refers to an electronic switch that can be used to turn electric current on and off. The first transistor 132 of the apparatus 100 can dynamically change the effective capacitance value of the apparatus 100 based on changes in either input voltage at 110, the output voltage at 109, and/or both, as further described herein. As used herein, the term “effective capacitance” refers to a capacitance value of a snubber capacitor that can be altered based on desired output voltage of an electric circuit. As illustrated in Figure 1A, the electric circuit 104 can include a second transistor 134, a third transistor 136.Additionally, the electric circuit 104 can include an inductor 114.

[0014] The electric circuit 104 illustrated in Figure 1A can be positioned within a computing device that can be coupled to a plurality of components of the computing device (e.g., CPU, control panels, etc.) and/or peripheral devices utilizing ports (e.g., communication ports, electrical ports, universal serial bus (USB) ports, etc,). In some examples, the electric circuit 104 can be communicatively coupled to data inputs of a particular port to receive data inputs from peripheral devices coupled to the particular port. As used herein, the term “communicatively coupled” refers to various wired and/or wireless connections between devices such that data can be transferred in various directions between the devices. In some examples, data can include a power status of a peripheral device. The electric circuit 104 can be one of a DC to DC converter, an AC to AC converter, a DC to AC converter or an AC to DC converter. [0015] In some examples, the electric circuit 104 illustrated in Figures 1A and

1 B can be an example of a DC to DC converter. The circuit 104 can have current in the inductor 114 and can be controlled by the second transistor 134 and the third transistor 136. In some examples, the second transistor 134 and the third transistor 136 can have a near zero voltage drop when the transistors are turned on. As used herein, the term “near zero” refers to a voltage that is close to the numerical value zero. In some instances, the second transistor 134 and the third transistor 136 can have a zero current flow when the transistors are off, and the inductor 114 can have a near zero series resistance. In some examples, the apparatus 100 can be used in switch mode power supplies to reduce the energy losses.

[0016] In some examples of the present disclosure, the apparatus 100 can be a power converter with a snubber capacitor. The apparatus 100 can include the first capacitor 106 and the second capacitor 108. As illustrated in Figure 1A, the first capacitor 106 and the second capacitor 108 can be placed in parallel. The first capacitor 106 can be, for example, a 100 nanoFarad (nF) capacitor. The second capacitor 108 can be, for example, a 100 nF capacitor. However, examples of the disclosure are not so limited. For example, the first capacitor 106 can be greater than a 100 nF capacitor or less than a 100 nF capacitor. Additionally, the second capacitor 108 can be greater than a 100 nF capacitor or less than a 100 nF capacitor.

Moreover, although at some time points the capacitance of the first capacitor 106 and second capacitor 108 can be the same capacitance, examples of the disclosure are not so limited. For example, the first capacitor 106 and the second capacitor 108 can include different capacitance values. [0017] In some examples, the second capacitor 108 is placed in parallel with the first capacitor 106 by turning on transistor 132. The second capacitor 108 can be removed by switching off the first transistor 132 of the apparatus 100. in some examples, the first transistor 132 can be switched off electrically in response to determining an input voltage of the apparatus 100 being at or below a threshold value. As used herein, the term “threshold value” refers to a value at or below which the current mode of an electric system is said to be at a low current mode, in some examples, the threshold value is a predetermined value that determines a low current mode of the apparatus.

[0018] In some examples, the second capacitor 108 can be removed from the snubber capacitor electric circuit 104-1 by switching off the first transistor 132 of the apparatus 100. The low current mode of the circuit 104 can reduce energy loss by the apparatus 100 by altering the effective snubber capacitance by removing the second capacitor 108 from the circuit by tuning off transistor 132. When a system (e.g., computing device, etc.) enters a sleep mode, the power used by the system can be reduced by 70 percent of nominal consumption, for example. The 70 percent capacity can be determined as the threshold capacity. Based on the reduced capacity, the electric circuit 104 can alter the capacitance value of the apparatus 100 by removing one of the capacitors (e.g. the second capacitor 108) using the first transistor 136, as further described herein

[0019] As described herein, the electric circuit 104 can include an inductor 114. As used herein the term "inductor” refers to a device that stores energy in its magnetic field and returns energy to the electric circuit. The inductor 114, for instance, can be formed by a cylindrical core with turns of conducting wire, in some examples, the inductor 114 can provide energy to the capacitor 116 and to the load when transistor 132 is turned on. As used herein, the term “load” refers to a component or portion of a circuit that consumes electric power.

[0020] In some examples, the transistor 136 is turned off, the transistor 134 is turned on to provide a path for the current that can flow from the reference ground 118 as the magnetic field in inductor 114 decays. This current can split between the load and the bulk capacitor 116. In some examples, the current flow can collapse to zero. When the current flow collapses to zero, the capacitor 116 can provide energy (e.g., all the energy) to the load until the next switching interval. As used herein, the term switching interval refers to an intervening time period between a first switching event and a second switching event. During the waiting time of the next switching interval, the transistor 136 can be turned back on. The transistor 134 can turn off before the transistor 13© turns back on and supply energy to the load,

[0021] In some examples, a controller can be used to apply an input voltage at 110 to the-third transistor 136, This can result in an input voltage being applied to a terminal 105. In some examples, the average output voltage at 109 can be equivalent to the input voltage at 110 multiplied by the duty ratio, in some examples, a duty ratio of the apparatus 100 is determined. The duty ratio of the apparatus 100 can be the ratio of the time that the third transistor 136 is turned on divided by the sum of the time that the third transistor 136 and the second transistor 134 are turned on during a switching cycie. In some examples, the average output voltage at 109 can be equivalent to the input voltage at 110 multiplied by the duty ratio.

[0022] As described herein, the apparatus 100 can include a first transistor 132. Using the first transistor 132, the effective capacitance value of the apparatus 100 can be changed based on changes in either the input voltage at 110, the output voltage at 109, and/ or both. For example, if the first capacitor 106 is a 3 nF capacitor, and the second capacitor 108 is a 7 nF capacitor. When the first transistor 132 is turned on the effective capacitance value of the apparatus 100 can be 10 nF by placing the first capacitor 106 in parallel with the second capacitor 108 capacitor. Contrarily, when the first transistor 132 is turned off the second capacitor 108 (7 nF capacitor) can be removed electrically, and the value of apparatus 100 can change to the lower value of the first capacitor 106 (3 nF capacitor). This 70 percent change capacitance in the apparatus 100 can reduce the energy losses by the electric circuit 104 by 70 percent.

[0023] In some examples, the energy losses can be further reduced by adjusting the value of the apparatus 100 and by adjusting the input voltage. For example, if the input voltage at 110 is decreased from 28V to 8V, a power loss when the apparatus 100 is at 10 nF capacitor, the power loss can be reduced from 2,88 watts (W) to 320 milliwatts (mW), Further, if the value of the apparatus 100 is reduced from 10 nF to 3,3 nF, the power loss can be reduced to 106 mW, Thus, in a power saving mode 214 mW of energy can be saved by dynamically changing the value of the apparatus 100.

[0024] The following model can be an example of reduction in power loss when the input voltage is altered and the effective value of the snubbing capacitance of the apparatus 100 is dynamically changed. V_in= 24 V C _snub = 10 nF

P _snub = C _snubV_in ² f = 10 x10^-9X 24² x 5x10⁵ = 2.22 W V_in = input voltage

C _snub = Effective Capacitance value of the snubber capacitor P_snub = is the instantaneous power dissipated in the snubbing circuit F= frequency

When V =8 V,

P_snub = C_snubV_in ² f = 10 x10^-9x 8² x 5x10⁵ = 320 mW But when C_snub is reduced from 10 nF to 3.3 nF in a sleep mode,

P_snub = C_snubV_in ² f = 3.3 x0^-9 x 24² x 5x10⁵ = 106 mW [0025] Figure 1 B illustrates an example of an apparatus 100 including a first capacitor 106 placed in series with a second capacitor 108 in accordance with the present disclosure. Similar to Figure 1A, the apparatus 100 can be part of an electric circuit 104. A portion of the electric circuit 104-1 can be a snubber capacitor circuit of the apparatus 100. The circuit 104 can include a first transistor 132, a second transistor 134, a third transistor 136, and a first resistor 130, a second resister 140 a third resister 150, and an inductor 114.

[0026] The apparatus 100 can include a 10 nF first capacitor 106 and a 3.3 nF second capacitor 108. in some examples. The first transistor 132 of the apparatus 100, as illustrated in Figure 1 B, can dynamically alter the value of the apparatus 100 by presenting either a 10 nF capacitor or a 2.5 nF capacitor created by the series combination of the first capacitor 106 an the second capacitor 108, For example, when the first transistor 132 is turned off, a value of the apparatus 100 can be reduced from 10nF to less than 2.5 nF due to the effect of having a 3.3 nF second capacitor 108 in series with the 1GnF first capacitor 106. Contrarily, when the first transistor 132 is turned on, the 3.3 nF second 108 capacitor can be shorted to the ground. As a result, the effective capacitance becomes equal to the value of the first capacitor 106, 10 nF,

[0027] Figure 2A illustrates an example diagram of a system 222 including a controller 202 and a transformer Isolated DC to DC converter with a series dynamic snubber capacitor 201 in accordance with the present disclosure. The system 222 can include an electric circuit 204 coupled to the snubber capacitor 201 and can include a plurality of capacitors such as a capacitor 207, a bulk capacitor 216. The controller 202 can be coupled to the electric circuit 204 and the snubber capacitor 201

[0028] The electric circuit 204 can dynamically alter the value of the snubber capacitor circuit 201 by changing an effective capacitance of a particular capacitor of the snubber capacitor circuit 201. The particular snubber capacitor, for example, can be a capacitor 208 as described herein. In some examples, the particular snubber can be the capacitor 206. The value of the snubber capacitor circuit 201 can be altered relative to voltage received by the electric circuit as described herein. In some examples, altering the effective value of the snubber capacitors can be independent of the voltage received by the electric circuit.

[0029] The electric circuit 204 can include a first snubber capacitor circuit 204-

1 having a first snubber capacitor 201-1 comprising a first capacitor 206-1 , a second capacitor 208-1 , and a first transistor 232-1. The electric circuit 204 can have a second snubber capacitor circuit 204-2 having a second snubber capacitor 201 -2 comprising a first capacitor 206-2, a second capacitor 208-2, and a second transistor 232-2. The electric circuit 204 can also include a third transistor 234 and a fourth transistor 236, In some examples, the first snubber capacitor 201-1 and second 201-

2 can be collectively referenced as snubber capacitor 201. Additionally or alternatively, the electric circuit 204 can include a series capacitor 207, an isolation transformer 224 a first resistor 230, a second resistor 240, and a bulk capacitor 216. [0030] The controller 202 of the system 222 can be part of a computer hardware. For example, the controller 202 can be a chip (e.g., a microcontroller, etc.), an expansion card, and/or a stand-alone device that interfaces with a more peripheral device. In some examples, the controller 202 can be a processing resource, such as a microprocessor, microcontroller, application specific instruction set processor, coprocessor, network processor, or similar hardware circuitry that may cause machine-readable instructions to be executed. The controller 202 can consume electric power provided by a power source, in some examples, a power source can provide energy to the electric circuit 204 in current/eiectric form via the controller 202 which can dynamically alter the effective capacitance values of the snubber capacitors based on the received input voltage.

[0031] In electric circuit 204, when the fourth transistor 236 is turned on, the first transistor 232-1 or the second transistor 232-2 can either be turned on or turned off depending on the amount of effective capacitance to be used. Similarly, when the transistor 234 is turned on, the fourth transistor 236 is turned off. When transistor 236 is turned on transistor 234 is turned off.

[0032] In the electric circuit 204, when the fourth transistor 236 is turned on current can start to flow and flow into a first winding 224-1 of the isolation transformer 224. As current flows into a first winding 224-1 a current can be induced into to the second winding 224-2 and flows through the diode 210. This can cause the bulk capacitor 216 to be charged and can provide current at point 209. When the fourth transistor 236 starts to turn off, the remaining current flowing through the fourth transistor 236 can be shunted into the snubber capacitors 201-1 . This can reduce excessive voltage generation across the fourth transistor 236. in response to the fourth transistor 236 being completely turned off, the voltage at a common point 211 of the fourth transistor 236 and the third transistor 234 can start to decrease in value. [0033] In some examples, the second diode 212 can start to conduct electricity and transfer energy into bulk capacitor 216 and at point 209 of the load. When the current passing through the third transistor 234 is close to being extinguished, the third transistor 234 can be turned off. When the third transistor 234 is turned off, any remaining current flow can be shunted into the snubber capacitor (e.g., 201-2, etc.) placed in parallel with the third transistor 234. in response, the voltage at the common point 211 of the third transistor 234 and the fourth transistor 236 can start to increase,

[0034] As the voltage of transistors 234 and 236 increase, energy loss by the system 222 can increase. The controller 202 of the system 222 can dynamically alter the value of the snubber capacitor 201 by changing the amount of effective capacitance of the particular capacitor, for example capacitor 208, of the plurality of capacitors. For example, the first snubber capacitor 201-1 and the second snubber capacitor 201-2 can reduce the energy loss via the particular second capacitor 208-1 and the 208-2. The second capacitor 208-1 and 208-2 can have the same capacitance value.

[0035] For example, if the capacitor 208-1 is 7 nF, the capacitor 208-2 can be 7 nF. In some examples, the voltage snubbed by the snubbing capacitance in parallel with the transistor 236 can be the same voltage snubbed by the capacitance in parallel with the transistor 234. For example, the voltage snubbed by snubber capacitor 201 -1 can be the same as the voltage snubbed by snubber capacitor 201 -2 when the capacitors 208-1 and 208- 2 are activated.

[0036] The controller 202 of the system 222 can turn on a transistor of the snubber capacitor responsive to the particular capacitor being added to the plurality of capacitors. For example, the snubber capacitors 201-1 and 201-2 can include additional transistors 232-1 and 232-2, respectively. The additional transistors 232-1 and 232-2 can control current flow of the first snubber capacitor circuit 204-1 and the second snubber capacitor circuit 204-2 and thus control current flow of the electric circuit 204 when the third transistor 234 and the fourth transistor 236 are turned on or off. For example, the first transistor 232-1 of the snubber capacitor 201-1 can control current flow of the first snubber capacitor circuit 204-1. The turned off position of the transistor 232-1 can piace the capacitor 208-1 in series with the capacitor 206-1. The transistors 232-1 and 232-2 can short out the series portions of the of the snubber capacitors 201. By shorting out the series portions of the snubber capacitors 201 , capacitance value of the snubber capacitors 201 can be increased, the controller 202 can turn off the transistor(s) of the snubber capacitors.

[0037] The additional transistor 232-2 of the snubber capacitor 201 -2 can be turned on. The turned on position of the additional transistor 232-2 can remove the capacitor 208-2 from the second snubber capacitor circuit 204-2. The additional transistors 232-1 and 232-2 can be activated when the snubber capacitor circuits 204-1 and 204-2 are operating loads above a particular threshold.

Turning on the snubber capacitors 201 via the additional transistors 232 can protect the third and fourth transistors 234 and 236 from excessive voltage stress. In some examples, when the load is low current mode, the additional transistors 232-1 and 232-1 can be turned off to reduce the value of the snubber capacitors 201 and decrease the amount of energy loss by the snubbing action.

[0038] Figure 2B illustrates an example diagram of a system 222 DC to DC converter with a parallel dynamic snubber capacitor 201 in accordance with the present disclosure. As described herein, system 222 can including a controller 202 and a DC to DC converter with parallel dynamic snubber capacitors 201-1 and 201-2. The system 222 can include an electric circuit 204, a third transistor 234, and a fourth transistor 236. Additionally, the system 222 can have a first snubber capacitor circuit 204-1 , a snubber capacitor 201 -1 including a first capacitor 206-1 , a second capacitor 208-1 , and a first transistor 232-1. The system 222 can have a second snubber capacitor circuit 204-2, a second snubber capacitor 201-2 including a first capacitor 206-2, a second capacitor 208-2, and a second transistor 232-2. In some examples, the snubber capacitors 201-1 and 201-2 can be collectively referenced as snubber capacitors 201. Additionally, the system 222 can include a series capacitor 207 and isolation transformer 224.

[0039] In system 222, additional transistors 232-1 and 232-2 can be used to add or remove a snubber capacitor from the snubber capacitor circuits 204-1 and 204-1. For example, when 232-1 and 232-2 are turned on, the value of the snubbing capacitance available across the fourth and the third transistors 236 and 234 is the additive product of the capacitor 206 and the capacitor 208. For example, if the capacitance value of capacitor 206 is 7 nF and the capacitance value of the capacitor 208 is 3 nF, the capacitance available across the snubber capacitors 201 is 10 nF. [0040] In some examples, when the first and the second transistors 232-1 and 232-2 are turned off, the value of the snubbing capacitance available across the fourth and the third transistors 236 and 234 is 208. Using the previous example values, the capacitance across the fourth and the third transistors 236 and 234 is 3 nF.

[0041] As described herein, the system 222 can include an electric circuit 204 that can be utilized to turn off a particular capacitor (e.g., capacitor 206) when the system 222 is in a low current mode. By turning off the particular capacitor (e.g., capacitor 206), the electric circuit 204 can alter the values of the snubber capacitor dynamically. This can reduce energy losses of the snubber capacitor.

[0042] Figure 3 illustrates a block diagram of an example method 333 in accordance with the present disclosure. In some examples, the method 333 can include a processing resource to execute instructions to perform the elements of the method 333. The processing resource may include processing circuitry such as a hardware processing unit such as a microprocessor, microcontroller, application specific instruction set processor, coprocessor, network processor, or similar hardware circuitry that may cause machine-readable instructions to be executed. In some examples, the processing resource may include central processing units (CPUs) among other types of processing units.

[0043] At 315, the method 333 can include receiving, from a power source, an input voltage at a transistor of an electric circuit. The power source can provide energy to the electric circuit of a system and/or apparatus. The energy and/or power can be received via a controller (e.g. controller 202 described with respect to Figures 2A and 2B) which can be converted dynamically, as described herein.

[0044] At 315, the method 333 can include determining the input voltage of a capacitor in the electric circuit based on the received input voltage. In some examples, the capacitor can be a first capacitor that receives the input voltage. At 315, receiving the input voltage can be based on a switch position of the electric circuit. For example, the switch position of the transistor can be on, and the capacitor can receive the input voltage,

[0045] At 317, method 333 can include determining, in response to the input voltage being at or below a threshold value, the electric circuit is in a low current mode. When the input voltage received by the electric circuit is at or below the threshold value, an associated system/apparatus can be determined as being in a low current mode or low power mode. Based on that determination, a transistor of the electric circuit can be turned off and a value of a particular capacitor can be altered.

In some examples, the particular capacitor being altered can be a second capacitor (e.g., second capacitor 208-2 as described in relation to Figure 2A and Figure 2B). [0046] At 319, the method 333 can include switching off the transistor to dynamically alter an input value of the snubber capacitor in response to the input voltage being at the low current mode, in some examples, altering the input value can include reducing the value of the snubber capacitor. This can reduce a power loss of the electric circuit. For example, a transistor (e.g. transistor 232 described with respect to Figure 2B) can be switched off. In response, a particular capacitor (e.g., the second capacitor 208-2 described with respect to Figure 2B) can be removed and can dynamically reduce the input value of the snubber capacitor. In some examples, reducing the input value of the particular capacitor can reduce energy loss as the energy loss of the snubbing circuit is reduced. For example, if an effective capacitance value of the particular capacitor is reduced by a factor of 3, the energy loss of the snubber capacitor can be reduced by a factor of three as discussed herein.

[0047] The figures herein follow a numbering convention in which the first digit corresponds to the drawing figure number and the remaining digits identify an element or component in the drawing. Elements shown in the various figures herein can be added, exchanged, and/or eliminated so as to provide a number of additional examples of the present disclosure, in addition, the proportion and the relative scale of the elements provided in the figures are intended to illustrate the examples of the present disclosure and should not be taken in a limiting sense. As used herein, the designator “N”, particularly with respect to reference numerals in the drawings, indicates that a number of the particular feature so designated can be included with examples of the present disclosure. The designators can represent the same or different numbers of the particular features. Further, as used herein, "a number of” an element and/or feature can refer to one or more of such elements and/or features. [0048] In the foregoing detailed description of the present disclosure, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration how examples of the disclosure may be practiced. These examples are described in sufficient detail to enable those of ordinary skill in the art to practice the examples of this disclosure, and it is to be understood that other examples may be utilized and that process, electrical, and/or structural changes may be made without departing from the scope of the present disclosure.

Claims

What is claimed:

1. An apparatus, comprising: a portion of an electric circuit; a first capacitor; and a second capacitor placed with the first capacitor , wherein the second capacitor is switched off from the portion of the electric circuit, via a transistor, in response to determining an input voltage being at or below a threshold value; and a capacitance value of the apparatus is dynamically altered relative to the input voltage.

2. The apparatus of claim 1 , wherein the capacitance of the first capacitor is dynamically altered in response to switching off the transistor.

3. The apparatus of claim 1 , wherein a capacitance of the first capacitor is dynamically altered in response to switching on the transistor.

4. The apparatus of claim 1 , wherein the second capacitor is placed in series with the first capacitor.

5. The apparatus of claim 1 , The apparatus of claim 1 , wherein the second capacitor is placed in parallel with the first capacitor.

6. The apparatus of claim 5, wherein a low current mode of the apparatus reduces energy loss by removing capacitance of the second capacitor.

7. A system, comprising: a snubber capacitor; an electric circuit coupled to the snubber capacitor and comprising a plurality of capacitors; and a controller coupled to the electric circuit and the snubber capacitor to dynamically alter a capacitance value of the snubber capacitor by changing an amount of capacitance of a particular capacitor of the snubber capacitor.

8. The system of claim 7, wherein the controller is to dynamically alter the value of the snubber capacitor by changing the amount of capacitance of the particular capacitor of the plurality of capacitors.

9. The system of claim 7, further comprising the controller to turn on a transistor of the snubber capacitor responsive to the particular capacitor being added to the plurality of capacitors.

10. The system of claim 7, wherein the controller is to turn off the transistor of the snubber capacitor responsive to the particular capacitor being removed from the plurality of capacitors.

11. The system of claim 7 wherein the electric circuit is one of an alternating current (AC) to a direct current (DC) converter, a DC to DC converter, a DC to AC converter, and an AC to AC converter.

12. The system of claim 7 further comprising the controller to dynamically alter the value of the snubber capacitor based on a load of the system.

13. A method comprising: receiving, from a power source, an input voltage at a transistor of an electric circuit; determining capacitance of a snubber capacitor of the electric circuit based on the received input voltage; determining, in response to the input voltage being at or below a threshold value, the electric circuit is in a low current mode; and switching off the transistor to dynamically alter a capacitance value of the snubber capacitor in response to the input voltage being in the low current mode.

14, The method of claim 13, wherein reducing the value of the snubber capacitor reduces a power loss of the electric circuit.

15. The method of claim 14, further comprising reducing the value of the snubber capacitor relative to the power loss of the electric circuit.