Controller

Abstract

A controller for a switched mode power supply includes a primary winding configured to receive an input voltage at a first end of the primary winding. A first capacitor is coupled in series between a second end of the primary winding and a reference end configured to be coupled to a reference voltage. A secondary winding is configured to provide an output voltage of the SMPS based on the input voltage, and an auxiliary winding is inductively coupled to one or both of the primary winding and the secondary winding and is configured to provide an auxiliary voltage based at least on a voltage of the first capacitor. The controller is configured to output an overvoltage signal indicative of an overvoltage across the first capacitor based on a comparison of the auxiliary voltage during a primary stroke of the SMPS to a threshold indicative of a predetermined maximum first capacitor voltage.

Description

Technical Field

[0001] This disclosure relates to a controller for a switch-mode power supply and a switch-mode power supply including said controller. This disclosure also relates to a method of operating said controller. Background Technology

[0002] Switch-mode power supplies (SMPS) are known to be used in power adapters to convert mains voltage to a lower voltage suitable for a given application. Well-known examples include power adapters for mobile phones, laptops, or tablets.

[0003] During the operation of the SMPS, the primary capacitor is charged. The output voltage can be based on the voltage across the primary capacitor. Like most electronic components (e.g., semiconductor-based components), the primary capacitor has a maximum rated voltage. It is important to ensure that the primary capacitor does not experience overvoltages exceeding the expected maximum voltage or its maximum rated voltage. However, determining when the voltage across the primary capacitor is in an overvoltage condition can be challenging. Summary of the Invention

[0004] According to a first aspect of this disclosure, a controller for a switch-mode power supply (SMPS) is provided, the SMPS comprising: a primary winding configured to receive an input voltage (Vin) at a first terminal of the primary winding; a first capacitor coupled in series between a second terminal of the primary winding and a reference terminal configured to be coupled to a reference voltage; a secondary winding configured to provide an output voltage of the SMPS based on the input voltage; and an auxiliary winding inductively coupled to one or both of the primary and secondary windings and configured to be based at least on the voltage (Vin) of the first capacitor. CR Provides auxiliary voltage (Vaux);

[0005] The controller is configured to adjust the auxiliary voltage during the primary stroke of the SMPS based on the predetermined maximum first capacitor voltage (V). CR_max The threshold of the first capacitor is compared to output an overvoltage signal indicating the overvoltage across the first capacitor.

[0006] In one or more embodiments, the comparison includes a comparison between a threshold and the difference between the input voltage and the auxiliary voltage.

[0007] In one or more examples, the voltage (V) of the first capacitor CR It is related to the input voltage (Vin) minus the auxiliary voltage (Vaux).

[0008] In one or more examples, when the polarity of the auxiliary winding is reversed, the voltage (V) of the first capacitor... CRIt is related to the auxiliary voltage (Vaux) minus the input voltage (Vin).

[0009] In one or more examples, the predetermined maximum first capacitor voltage (V) CR_max () can be an analog signal that includes a predetermined maximum capacitor voltage, a signal representing a predetermined maximum capacitor voltage, or a digital signal representing a predetermined maximum capacitor voltage.

[0010] In one or more embodiments, the controller is configured to control the SMPS to stop charging the first capacitor in response to an overvoltage signal.

[0011] In one or more embodiments, the controller is thus configured to control the duration of charging the first capacitor during each primary stroke based at least in part on an overvoltage signal.

[0012] In one or more examples, the controller is configured to continue providing the output voltage of the SMPS in response to an overvoltage signal.

[0013] In one or more embodiments, the controller includes:

[0014] A first input terminal is configured to receive a first voltage indicating the input voltage;

[0015] The second input terminal is configured to receive a second voltage indicating the auxiliary voltage; and

[0016] A comparator configured to receive a first signal indicating a first voltage and a second signal indicating a second voltage, wherein the comparator is further configured to compare the second signal and the first signal during the primary stroke of the SMPS with an indication of a predetermined maximum first capacitor voltage (V). CR_max The difference between the threshold values ​​is used to output an overvoltage signal indicating the overvoltage across the first capacitor.

[0017] In one or more embodiments, the first signal is based on a first voltage and an indication of a predetermined maximum first capacitor voltage (V). CR_max The difference between the thresholds.

[0018] In one or more examples, the first signal may be derived from the first voltage, and one or more arithmetic operations may be performed on the first voltage before it is provided to the first input of the comparator.

[0019] In one or more examples, the second signal can be derived from the second voltage, and one or more arithmetic operations can be performed on the second voltage before it is provided to the second input of the comparator.

[0020] In one or more examples, the first signal and the second signal can be derived from the first voltage and the second voltage, respectively, and one or more arithmetic operations can be performed on the first voltage and the second voltage before they are respectively provided to the first input and the second input of the comparator.

[0021] In one or more embodiments, the comparator is configured to output an overvoltage signal when the second signal exceeds the first signal. In some embodiments, an overvoltage signal may be generated when the second signal is greater than the first signal, depending on the polarity of the auxiliary winding; and in other embodiments, an overvoltage signal may be generated when the second signal is less than the first signal.

[0022] In one or more examples, the first signal and the second signal are in the digital domain such that the first signal is a digital representation of the first voltage and the second signal is a digital representation of the second voltage.

[0023] In one or more embodiments, the controller is configured to shorten the duration of the primary stroke in response to the output of an overvoltage signal, thereby limiting the voltage to which the first capacitor is charged during one or more subsequent primary strokes of the SMPS.

[0024] In one or more embodiments, the controller includes a differential element configured to generate a first signal based on a third signal indicating a first voltage minus a predetermined maximum first capacitor voltage.

[0025] In one or more examples, the comparison is based on an auxiliary voltage present on the auxiliary winding only during the primary stroke. In other examples, the comparison is based on an auxiliary voltage present on the auxiliary winding only during the primary stroke and only during the initial portion of the secondary stroke.

[0026] In one or more examples, the controller is configured not to output an overvoltage signal during the secondary stroke of the SMPS.

[0027] In one or more embodiments, the controller is configured to receive a second voltage from a first voltage divider coupled in parallel across an auxiliary winding, wherein the first voltage divider includes a first resistor having a resistance R1 and a second resistor having a resistance R2, wherein a first end of the first resistor is coupled to a first end of the auxiliary winding and a second end of the first resistor is coupled to a first node, and a first end of the second resistor is coupled to the first node, wherein a second end of the second resistor is coupled to a reference terminal, and wherein the first node provides the second voltage on which the second signal is based.

[0028] In one or more embodiments, the controller is configured to receive a first voltage from a second voltage divider, the second voltage divider comprising:

[0029] A third resistor and a fourth resistor, wherein a first end of the third resistor is configured to receive the input voltage and a second end of the third resistor is coupled to a second node, and a first end of the fourth resistor is coupled to the second node, wherein a second end of the fourth resistor is coupled to the reference terminal, and wherein the second node provides the first voltage on which the first signal is based.

[0030] In one or more examples, the third resistor has a resistance of R3, and the fourth resistor has a resistance of R4, and the input voltage has a voltage V. IN The first voltage V first include:

[0031]

[0032] In one or more examples, the primary winding has a first number of turns (n) p ), and the auxiliary winding has a second number of turns (n) a ), making the second voltage V second Provided through the following equation:

[0033] It equals:

[0034]

[0035] This allows the comparator to determine the second voltage V. second When does the predetermined maximum first capacitor voltage (V) exceed? CR_max In some examples, the comparator can be configured to determine the second voltage V. second When will the voltage drop fall below the predetermined maximum first capacitor voltage (V)? CR_max ).

[0036] In one or more examples, the maximum value of the second voltage is 10V.

[0037] In one or more examples, an overvoltage across the first capacitor is determined when the value of the second voltage exceeds a predetermined threshold, wherein the second voltage indicating the overvoltage condition is given by the following formula:

[0038]

[0039] In one or more examples, for the input voltage (Vin) and the voltage of the first capacitor (V) CR The maximum difference between the two voltages provides the maximum value of the second voltage.

[0040] In one or more examples, the maximum value of the second voltage is provided by the following formula:

[0041]

[0042] In one or more examples, the maximum input voltage is 400V, and the minimum first capacitor voltage is 0V, and thus the maximum second voltage is:

[0043]

[0044] In one or more embodiments, the controller is configured to: provide a first switching signal to control the primary stroke of the SMPS, during which the first capacitor is charged; and provide a second switching signal to control the secondary stroke of the SMPS, during which the first capacitor is discharged.

[0045] According to a second aspect of this disclosure, a switch-mode power supply (SMPS) is provided, comprising a controller according to any of the preceding claims, the SMPS comprising:

[0046] The primary winding is configured to receive an input voltage at its first terminal; and

[0047] The first capacitor is coupled in series between the second end of the primary winding and the reference end;

[0048] The secondary winding is configured to provide the output voltage of the SMPS based on the input voltage; and

[0049] The auxiliary winding is configured to be based at least on the voltage of the first capacitor (V CR It provides auxiliary voltage.

[0050] In one or more embodiments, the auxiliary winding is inductively coupled to one or both of the primary and secondary windings, such that during the primary stroke of the SMPS, the auxiliary voltage is based on the input voltage (Vin) minus the voltage across the first capacitor (V). CR ).

[0051] In one or more examples, SMPS includes an asymmetric half-bridge AHB topology.

[0052] According to a third aspect of this disclosure, a method for controlling a switch-mode power supply (SMPS) is provided, the SMPS comprising: a primary winding configured to receive an input voltage (Vin) at a first end of the primary winding; a first capacitor coupled in series between a second end of the primary winding and a reference terminal configured to be coupled to a reference voltage; a secondary winding configured to provide an output voltage of the SMPS based on the input voltage; and an auxiliary winding inductively coupled to one or both of the primary and secondary windings and configured to at least based on the voltage (Vin) of the first capacitor. CRProvides auxiliary voltage (Vaux);

[0053] The method includes:

[0054] The SMPS controller compares the auxiliary voltage during the primary stroke of the SMPS with the predetermined maximum first capacitor voltage (V). CR_max The threshold of ) and

[0055] The controller of the SMPS outputs an overvoltage signal indicating an overvoltage across the first capacitor based on the comparison.

[0056] While this disclosure allows for various modifications and alternatives, its details have been illustrated by way of example in the accompanying drawings and will be described in detail. However, it should be understood that other embodiments besides the specific embodiments described may also exist. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also covered.

[0057] The foregoing discussion is not intended to present every example embodiment or every implementation within the scope of the present or future claims. The accompanying drawings and detailed description also illustrate various example embodiments. A more comprehensive understanding of these various example embodiments can be obtained by considering the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0058] One or more embodiments will now be described with reference to the accompanying drawings, by way of example only, in which:

[0059] Figure 1 An example embodiment of a controller for SMPS is shown;

[0060] Figure 2 A representative waveform indicating the operation of SMPS is shown;

[0061] Figure 3 An example configuration of components within the controller of the SMPS according to the first embodiment is shown;

[0062] Figure 4 A first configuration of components within a controller is shown according to a first example embodiment of the controller;

[0063] Figure 5 A second configuration of components within a controller is shown according to a second example embodiment of the controller;

[0064] Figure 6 A third configuration of components within a controller according to a first example embodiment of the controller is shown;

[0065] Figure 7 Alternative embodiments of the controller for SMPS are shown; and

[0066] Figure 8 The operation is summarized. Figures 1 to 7 The controller's methods. Detailed Implementation

[0067] One or more embodiments disclosed herein relate to a controller for a switch-mode power supply. During the primary stroke of the power supply, a first capacitor, also referred to as a resonant or primary capacitor, is charged. The energy stored in the primary capacitor is then converted into an output voltage via the secondary side of the power supply during the secondary stroke.

[0068] The controller disclosed herein can be configured to prevent serious damage to the SMPS by preventing the voltage on the first capacitor from exceeding its maximum rated voltage or other desired maximum value—referred to herein as the predetermined maximum capacitor voltage. In some examples, the controller can be configured to limit the output power of the SMPS while maintaining the required voltage regulation in the event of exceeding the predetermined maximum capacitor voltage. This ensures the continued operation of the device coupled to the SMPS without the risk of damaging the SMPS.

[0069] During the secondary stroke, the output voltage is related to the voltage across the primary capacitor. The proposed controller provides a way to identify overvoltage conditions on the primary capacitor during the primary stroke. One or more embodiments of the controller disclosed herein are advantageous because the controller can be applied to any type of switch-mode power supply, such as a flyback converter or a buck-boost converter. Furthermore, one or more embodiments of the disclosed controller can achieve the desired control without requiring any additional components and without adding dedicated pins to the integrated circuit (IC) embodying the controller.

[0070] Figure 1 and Figure 2 An example of SMPS100 is shown, along with a series of waveforms 200 summarizing the operation of SMPS. Figure 1 The main components of the SMPS are also outlined, including the input terminal 101 of the SMPS100 configured to receive an input voltage. Figure 1 The diagram also shows the output 112 of the SMPS, as well as various components within the SMPS. In one or more examples, the SMPS 100 may include a primary winding 104, a first capacitor 106, a reference terminal 108 configured to be coupled to a reference voltage, a secondary winding 110, and an auxiliary winding 114. This basic layout of the SMPS will be familiar to those skilled in the art. It should be understood that, as those skilled in the art will recognize, additional components are also included in the SMPS, and for the sake of brevity, these components will not be described here. Figure 1 The controller 102, which is the focus of this disclosure, is also shown. Figure 1Other components, such as high-side switching component 118 and low-side switching component 120, which are typically implemented by MOSFETs, are also shown, but are not described in detail herein because their operation is known to those skilled in the art.

[0071] Returning to the configuration of windings 104, 110, and 114, as follows: Figure 1 As shown, in one or more examples, the primary winding 104 can be configured to receive an input voltage (Vin) at a first terminal of the primary winding 104, and a first capacitor 106 can be series-coupled between a second terminal of the primary winding 104 and a reference terminal 108. In some examples, the secondary winding 110 can be configured to provide an output voltage 112 of the SMPS based on an input voltage received at an input terminal 101 of the SMPS 100. In some examples, the output voltage can be based on the turns ratio between the primary winding 104 and the secondary winding 110. In some examples, the auxiliary winding 114 can be configured to be based at least on the voltage (Vin) of the first capacitor. CR Auxiliary voltage (Vaux) is provided by auxiliary winding 114. In some examples, auxiliary winding 114 can provide a voltage based on the inductive coupling between auxiliary winding 114 and one or both of primary winding 104 and secondary winding 110. During secondary stroke 206, the voltage on auxiliary winding 114 represents the voltage on first capacitor 106. However, during primary stroke 204, the voltage on auxiliary winding can be related to the input voltage (Vin) minus the voltage on first capacitor 106.

[0072] It should be understood that the polarity of the voltage on the auxiliary winding can be reversed by reversing the polarity of the auxiliary winding 114. In this case, the voltage on the polarity-reversed auxiliary winding can be given by subtracting the input voltage (Vin) from the voltage on the first capacitor 106.

[0073] Figure 2 Waveform 200 shows the voltage (V) of the first capacitor 106. CR 202. The primary stroke 204 and secondary stroke 206 of SMPS100 are also identified, and the primary stroke and secondary stroke are implemented by control signal 212 of control switch assemblies 118 and 120. Figure 2 Magnetizing current 208 and resonant current 210 are also shown. The magnetizing current is the current in the primary winding, and the resonant current is the current through the first capacitor 106. Outside the secondary stroke 206, the magnetizing current 208 and the resonant current 210 are the same.

[0074] In one or more examples, during the primary stroke 204, the high-side MOSFET 118 is turned on, and the first capacitor 106 is charged. During the primary stroke 204, the low-side MOSFET 120 is turned off. During the secondary stroke 206, the high-side MOSFET 110 is turned off, and the low-side MOSFET 120 is turned on. In this case, the energy in the first capacitor 106 is transferred to the secondary side of the SMPS 100. Therefore, it is important to monitor the voltage across the first capacitor 106 during the primary stroke 204 to prevent the first capacitor 106 from being charged to a level higher than a predetermined maximum capacitor voltage 214.

[0075] During the primary stroke 204, the high-side switch 118 of the SMPS100 is turned on, and current flows from the input 101 of the SMPS100 to the first capacitor 106. During the primary stroke 204, the first capacitor 106 is charged and its voltage increases. As is known to those skilled in the art, during the secondary stroke 206, the first capacitor is no longer charged and discharged through the primary winding 104, thereby providing an output voltage at the output 112 of the SMPS100 through inductive coupling between the primary winding 104 and the secondary winding 110. The output 112 of the SMPS100 can be coupled to a load 116, such as a mobile phone, laptop computer, tablet computer, or any other electronic device requiring regulated voltage.

[0076] It should be understood that SMPS can typically be configured such that the first capacitor 106 charges when the high-side switch is turned on and discharges when the low-side switch is turned on. However, as Figure 7 As shown, SMPS 100 can be configured such that the first capacitor 106 is charged when the low-side switch 702 is turned on and discharged when the high-side switch 704 is turned on. In this example, with Figure 1 Compared to the functions shown, the high-side switch 118 and the low-side switch 120 are functionally interchangeable.

[0077] Return to Figure 2 It should be understood that the difference between the magnetizing current 208 and the resonant current 210 is equal to the reflected output current. Therefore, it is obvious that during the secondary stroke 206, energy is only delivered to the secondary side of the SMPS100.

[0078] The voltage at the first capacitor 106 is equal to the output voltage multiplied by the transformation ratio (which is typically based on the turns ratio between the primary winding 104 and the secondary winding 110) plus some additional ripple voltage. In some examples, if the output voltage is 48V and the transformation ratio is 4, the voltage at the first capacitor can be almost 200V. However, this is just one example, and the output voltage and transformation ratio can be defined for the specific application of SMPS.

[0079] To minimize cost and cover a wide range of applications, the first capacitor 106 is selected to have a maximum rated voltage 214 that is higher than the output voltage multiplied by the transformation ratio. In the example above, the first capacitor 106 can therefore be selected to have a maximum rated voltage of 250V.

[0080] In the event of an error or other malfunction in the SMPS, or if the circuit is not designed for this purpose, or alternatively, due to aging of components within the SMPS, the voltage on the first capacitor 106 may begin to approach or even exceed its maximum rated voltage (e.g., >250V). In this case, the output voltage may damage the devices coupled to the SMPS. Therefore, it is desirable to have a built-in mechanism that can prevent the voltage on the first capacitor 106 from approaching and / or exceeding its maximum rated voltage 214. A major problem is the difficulty in measuring the voltage on the first capacitor 106 in known SMPS designs.

[0081] To address the aforementioned issues, one option is to include dedicated pins on the integrated circuit (IC) of the controller 202. However, this introduces manufacturing costs and cannot be applied to existing devices. The method described herein provides a way to monitor the voltage across the first capacitor 106 and thereby prevent the voltage of the first capacitor from exceeding a predetermined maximum first capacitor voltage during the primary stroke 204, said predetermined maximum first capacitor voltage being a maximum rated voltage 214.

[0082] Furthermore, one or more examples of the controller 102 described herein can determine the first capacitor voltage without any additional components and without requiring a dedicated pin on the IC of the controller 102.

[0083] exist Figure 1 In an example embodiment, controller 102 is configured to output an overvoltage signal (in Figure 3 (As shown in Figure 302), the overvoltage signal indicates an overvoltage across the first capacitor 106. The overvoltage signal may be based on an auxiliary voltage compared to a predetermined maximum first capacitor voltage (V) during the primary stroke 204 of the SMPS 100. CR_maxThe threshold 214 is compared. In some examples, the predetermined maximum first capacitor voltage may be the maximum rated voltage to which the first capacitor can be charged, for example, set by the manufacturer. In other examples, the predetermined maximum first capacitor voltage may be defined based on operational requirements and may be set to limit the output voltage 112 of the SMPS and based on the intended use of the SMPS 100. In this example, the predetermined maximum first capacitor voltage may not be the inherent maximum voltage of the first capacitor and may be any value up to, for example, the maximum rated voltage set by the capacitor manufacturer. It should be understood that since the controller 102 can operate in the digital or analog domain, the threshold may be a digital value or voltage representing the desired predetermined maximum first capacitor voltage.

[0084] Figure 3 A more detailed view of the controller 102 of the SMPS100 is provided. As mentioned, the controller 102 may be a digital controller, and therefore the components shown herein may be implemented digitally, or in other examples, it may be an analog controller with discrete components as shown. In some examples, the controller 102 further includes a comparator 306. The comparator 306 has an inverting input 306A and a non-inverting input 306B, each configured to receive signals to be compared. In one or more examples, the comparison of these signals indicates whether the voltage across the first capacitor 106 has exceeded a predetermined maximum first capacitor voltage 214.

[0085] It should be understood that during the initial stroke 204, the voltage of the first capacitor 106 is related to the input voltage (Vin) minus the auxiliary voltage (Vaux). Therefore, a threshold can be compared with the difference between the input voltage and the auxiliary voltage to determine whether the predetermined maximum first capacitor voltage 214 has been reached. The predetermined maximum first capacitor voltage (Vin) CR_max This can be represented as an analog signal including a predetermined maximum capacitor voltage, a signal representing a predetermined maximum capacitor voltage, or a digital signal representing a predetermined maximum capacitor voltage. In some examples, when the input voltage is fixed, the threshold indicating the predetermined maximum capacitor voltage can take the input voltage into account, such that the threshold can be compared with an auxiliary voltage, rather than comparing the threshold with the difference between the input voltage and the auxiliary voltage.

[0086] It should be understood that if the polarity of the auxiliary winding 114 is reversed, the voltage on the auxiliary winding 114 will be given by the voltage on the first capacitor 106 minus the input voltage (Vin). In this case, compared to Figures 3 to 6 In the embodiment shown, the inputs to each of the inverting input 306A and the non-inverting input 306B of the comparator 306 will need to be inverted.

[0087] To ensure that SMPS 100 is protected, and also to ensure that the load 116 coupled to the output of SMPS is protected, controller 102 can be configured to control SMPS 100 to stop charging the first capacitor 106 in response to overvoltage signal 302. This prevents the voltage of the first capacitor 106 from rising above a predetermined maximum capacitor voltage (V). CR_max Another advantage of preventing the voltage of the first capacitor 106 from exceeding the threshold is that it ensures that the SMPS continues to operate, albeit at lower power.

[0088] If controller 102 does detect that a threshold has been reached, the controller can be configured to adjust control signal 212, thereby controlling the duration of the primary stroke 204, so that during subsequent primary strokes, the first capacitor 106 is charged for a shorter duration, thereby reducing the likelihood of exceeding a predetermined maximum capacitor voltage. This can improve the lifespan of the first capacitor and allow for more reliable control of the output voltage 112.

[0089] In some examples, controller 102 may be configured to provide a first switching signal to control the primary stroke of the SMPS, during which the first capacitor 106 is charged, and may also be configured to provide a second switching signal to control the secondary stroke of the SMPS, during which the first capacitor is discharged. It should be understood that the first and second switching signals can be used to control the operation of the switching components 118, 120 of the SMPS 102, as will be understood by those skilled in the art.

[0090] Figure 3 Components 308, 310 for providing a first voltage and a second voltage to controller 102 are also shown. In some examples, the first voltage and the second voltage may be provided by voltage dividers 308, 310 and may be configured to provide the voltage on which the first signal and the second signal are based via a comparator 306.

[0091] Figure 3 The controller 102 is further shown to include a first input terminal 314 configured to receive a first voltage. The first voltage may be a voltage indicating an input voltage. Figure 3 In the example, the first voltage can be the SNSBOOST voltage. Figure 3 The controller 102 is further shown to include a second input terminal 312 configured to receive a second voltage. This second voltage indicates an auxiliary voltage. Figure 3 In this example, the second voltage can be the SNSOUT voltage. It should be understood that the SNSBOOST and SNSOUT voltage signals are widely used in power supply design and can be generated in various ways. The first and second voltages can be provided by the second voltage divider 308 and the first voltage divider 310, respectively.

[0092] exist Figure 3 In this configuration, comparator 306 is configured to receive a first signal indicating a first voltage (e.g., digital SNSBOOST) and a second signal indicating a second voltage (e.g., digital SNSOUT). It should be understood that the digital SNSBOOST signal and the digital SNSOUT signal are digital representations of the SNSBOOST voltage and the SNSOUT voltage, respectively. Figure 3 The comparator 306 is further configured to output an overvoltage signal 302, which indicates an overvoltage across the first capacitor 106. The overvoltage signal 302 may be based on a comparison of a second signal and a first signal during the primary stroke 204 of the SMPS 100 with an indication of a predetermined maximum first capacitor voltage (V). CR_max The difference between the threshold 214.

[0093] Figure 3 Further illustration shows an additional component 304 (or digital processing function), which may be included in the controller 102 to generate a first signal and a second signal. In some examples, the first and second signals can be generated by modifying the first and second voltages. [The remaining text appears to be unrelated and likely refers to further details about the diagram.] Figures 4 to 6 Describe these additional components.

[0094] exist Figure 4 In this configuration, a second voltage (i.e., SNSOUT) is provided to the controller 102 from a first voltage divider 310 coupled in parallel across the auxiliary winding 114. The first voltage divider 310 includes a first resistor 402 with resistance R1 and a second resistor 404 with resistance R2. A first end of the first resistor 402 is coupled to a first end 406 of the auxiliary winding 114, and a second end of the first resistor is coupled to a first node 408. A first end of the second resistor 404 is coupled to the first node 408, and a second end of the second resistor 404 is coupled to a reference terminal 108. The first node 408 can provide the second voltage upon which the second signal is based.

[0095] exist Figure 4 In this configuration, a first voltage (i.e., SNSBOOST) is provided to the controller 102 from a second voltage divider 308, wherein the second voltage is based on the input voltage. The second voltage divider 308 includes a third resistor 410 with resistor R3 and a fourth resistor 412 with resistor R4. A first end of the third resistor 410 is coupled to the input terminal, a second end of the first resistor is coupled to a second node 414, and a first end of the fourth resistor 412 is coupled to the second node 414, while a second end of the fourth resistor 412 is coupled to a reference terminal 108. The second node 414 can provide the first voltage upon which the first signal is based.

[0096] Figure 4It is also shown that in some examples, controller 102 may include a differential element 418 configured to generate a first signal (digital SNSBOOST) based on a third signal (multiplied SNSBOOST), the third signal indicating a first voltage (SNSBOOST) minus a predetermined maximum first capacitor voltage. In some examples, the third signal may be the first voltage modified by multiplier 416. In some examples, multiplier 416 may be based on a voltage drop provided by a second voltage divider 308, which provides the first voltage to controller 102. It should be understood that the value of additional component 304 may be selected based on the values ​​of the resistors of the first and second voltage dividers, and more precisely, based on the voltage drop provided by the first and second voltage dividers. This ensures that the first and second signals compared by comparator 306 indicate the input voltage and auxiliary voltage, respectively. This ensures that the compared first and second signals represent the voltage across the first capacitor 106.

[0097] Figure 4 , 5 Figures 6 and 7 illustrate three different arrangements, in which either the first voltage or the second voltage, or both the first voltage and the second voltage, are modified by an additional component 304. Figure 4 As can be seen from this, the first signal can be derived from the first voltage, and one or more arithmetic operations can be performed on the first voltage before it is provided to the first input terminal 306A of the comparator 306. Figure 4 In the first voltage, the first voltage is coupled from the second node 414 to the first input terminal 314 of the controller 102, and the second voltage is coupled from the first node 408 to the second input terminal 312 of the controller 102.

[0098] In one or more examples, the first voltage may be a portion of the input voltage provided by the second voltage divider 308, and the second voltage may be a portion of the auxiliary voltage provided by the first voltage divider 310.

[0099] exist Figure 4 In this process, the first voltage can be multiplied by multiplier 416 to provide a third signal. In some examples, the value of multiplier 416 is related to the value of the second voltage divider 308 to which it is coupled. Then, differential element 418 reduces the third signal to reduce it by a predetermined maximum first capacitor voltage (V). CR_maxThe fourth signal is then modified by divider 420 to provide the first signal to the first terminal 306A of comparator 306. The fourth signal is divided by a factor corresponding to the ratio of the input voltage to the maximum value set for the second voltage to provide the first signal provided to comparator 306. In some examples, the maximum input voltage can be 400V, and the maximum value of the second voltage can be set to 10V. However, due to circuit limitations, other values ​​can be used for the input voltage and the maximum value of the second voltage. In the above non-limiting example, divider 420 can divide the fourth signal by 40. Although, as previously mentioned, other values ​​can be used, and these values ​​are based on the input voltage and the maximum value set for the second voltage.

[0100] Figure 5 It shows Figure 4 Alternative embodiments of the arrangement shown. Figure 5 The additional component 304 used in the execution and Figure 4 The operation performed in the example is the opposite of the previous one. Specifically, the second voltage is first multiplied by a factor corresponding to the ratio of the input voltage to the maximum value set for the second voltage (i.e., 40) to provide the fifth signal. Then, the differential element 418 increases the fifth signal by a predetermined maximum first capacitor voltage (V). CR_max This provides a sixth signal. The sixth signal is then divided by multiplier 416 to provide a second signal, which is then provided to the non-inverting input 306B of the comparator. Figure 5 In the example, the value of multiplier 416 is related to the value of second voltage divider 308 so that the first signal and the second signal can be compared by comparator 306.

[0101] exist Figure 6 As can be seen from the diagram, the first signal and the second signal can be derived from the first voltage and the second voltage, respectively, and each can perform one or more arithmetic operations before being provided to the first input terminal 306A and the second input terminal 306B of the comparator, respectively.

[0102] exist Figure 6 In the middle, the second voltage is multiplied by multiplier 416 to provide according to Figure 4 The third signal in the example. Specifically, the second voltage is multiplied by the factor by which the second voltage divider 308 reduces the input voltage. Figure 6 In this process, the second voltage is first multiplied by a factor corresponding to the ratio of the input voltage to the maximum value set for the second voltage (i.e., 40) to provide the seventh signal. Then, the differential element 418 adds a predetermined maximum first capacitor voltage (V) to the seventh signal. CR_max To provide the eighth signal. Figure 6In the example, the signal provided to the non-inverting input terminal 306A of comparator 306 is the eighth signal, and the signal provided to the inverting input terminal 306B of comparator 306 is the third signal as defined above.

[0103] In the example shown, additional component 304 applies arithmetic operations to the first and second voltages. However, additional component 304 may also include other operations that modify the first and second voltages to allow the comparator to perform reliable comparisons between the signals in order to determine an overvoltage condition on the first capacitor 106. It should also be understood that the above arrangement of additional component 304 is provided to represent the algebraic equations shown below.

[0104] In such Figures 3 to 6 In the example shown, it should be understood that since the first resistor has resistance R1 and the second resistor has resistance R2 and the auxiliary voltage is V Aux Therefore, the second voltage V second It can be represented as follows:

[0105]

[0106] The auxiliary voltage (Vaux) indicates the voltage across the first capacitor 106, and specifically includes the input voltage (V). IN ) and the voltage across the first capacitor (V CR The difference between the two windings is multiplied by the turns ratio of the auxiliary winding 114 to the primary winding 104. Therefore, equation (1) can be expressed as follows:

[0107]

[0108] It should be understood that the turns ratio can also be called the transformer ratio. This is the turns ratio between any two windings, depending on the configuration of the SMPS. The transformer ratio determines the voltage ratio between the primary winding and the auxiliary winding.

[0109] exist Figures 3 to 6 In the example, it should be understood that the third resistor has a resistance of R3 and the fourth resistor has a resistance of R4, and the input voltage has a voltage V. IN Considering the above, the first voltage V first It can be represented as follows:

[0110]

[0111] Replace V with Equation 2 and the rearrangement form of Equation 3 above. IN Conclusion:

[0112]

[0113] In some examples, an overvoltage across the first capacitor 106 is determined when the value of the second voltage exceeds a predetermined threshold, wherein the second voltage indicating the overvoltage condition is given by the following formula:

[0114]

[0115] In equation 5, V CR Set to a predetermined maximum first capacitor voltage (i.e., V) CR_max Considering the above, the first signal can be based on a first voltage and an indication of a predetermined maximum first capacitor voltage (V). CR_max The difference between the thresholds.

[0116] When the second voltage exceeds the value determined by the above expression, an overvoltage across the first capacitor 106 can be detected.

[0117] In some examples, for the input voltage (V) IN ) and the voltage of the first capacitor (V CR The maximum difference between the two voltages provides the maximum value of the second voltage (i.e., SNSOUTMAX). In this case, the maximum value of the second voltage can be provided by the following expression:

[0118]

[0119] The values ​​of various additional components 304 can be determined for specific examples, as will be summarized below. It should be understood that the value of additional components 304 can vary in different configurations to provide a comparable signal to comparator 306.

[0120] In typical applications, V in With V first There is a fixed relationship between them. In most power supplies, power factor correction (PFC) is required before the SMPS converter. The PFC regulates the initial voltage to approximately 2.5V to obtain an input voltage of approximately 400V. Considering these example values ​​(which are not intended to limit the application range, but only to provide a feasible example), Equation 3 above can be rearranged to derive:

[0121]

[0122] The maximum input voltage equals the maximum PFC voltage, which in some cases can be 400V. The voltage across the first capacitor is 106V. CR It can have a minimum value of 0V. Therefore, it is possible to target V. in With V CR The maximum difference between them achieves the maximum value of the second voltage (i.e., V). second max (This can be clearly seen in Equation 2), which leads to:

[0123]

[0124] Typically, the maximum value of the second voltage (i.e., V) second_max Limited by circuit constraints, and in a typical example, this could be 10V, but other values ​​can also be used. In this example, using the values ​​described above, we obtain:

[0125]

[0126] The rearranged formula yields:

[0127]

[0128] Therefore, in order to detect overvoltage conditions, Equation 1 can ultimately be written as:

[0129]

[0130] Considering the above, when the second voltage exceeds the value determined by the above expression, it can be interpreted as an overvoltage occurring on the first capacitor 106. CR_max Next is the maximum permissible voltage across the first capacitor 106. It should be understood that V CR_max It can be set to any desired voltage, and does not have to be the maximum rated voltage.

[0131] It should be understood that the above expression can be rearranged while still allowing the same comparisons. Three alternatives are shown below:

[0132] Its like Figure 4 The examples described in the text.

[0133] 40.V Second =(160·V) first -V CR_max ), its form is as Figure 5 The examples described in the text.

[0134] 40.V Second +V CR_max =160·V first , its is like Figure 6 The examples described in the text.

[0135] It should be understood that other configurations may also be used, and fewer operations may be performed on the first and second voltages before they are provided to comparator 306, and the above are only a few non-limiting examples.

[0136] In some examples, comparator 306 can be configured to compare a second voltage (or a signal based on the second voltage) with a first voltage (or a signal based on the first voltage) to determine when the second voltage exceeds a predetermined maximum first capacitor voltage (V). CR_max (or when the second voltage exceeds the value determined by the above expression.)

[0137] In some cases, comparator 306 can be configured to output an overvoltage signal 302 when a second signal (based on the input voltage) is greater than a first signal (based on an auxiliary voltage), wherein one of the second and first signals is further based on a predetermined maximum first capacitor voltage (V). CR_max ).

[0138] Generally, it should be understood that the circuit system determines the difference between a signal based on the input voltage and a signal based on an auxiliary voltage, which indicates the voltage across the first capacitor 106. This auxiliary voltage can be compared with an indication of a predetermined maximum capacitor voltage (V). CR_max The threshold of the first capacitor (V) is compared. In the example above, a first signal and a second signal are derived such that when the second voltage exceeds a predetermined maximum first capacitor voltage (V), the voltage difference is equal to the voltage difference between the first and second capacitors. CR_max When the second voltage drops below a predetermined maximum first capacitor voltage (V), an overvoltage signal 302 is generated. However, in other embodiments, the polarity of the auxiliary winding can be different, and therefore, when the second voltage drops below a predetermined maximum first capacitor voltage (V), an overvoltage signal 302 is generated. CR_max When an overvoltage occurs, an overvoltage signal 302 is generated. However, in any embodiment, the overvoltage signal 302 indicates an overvoltage condition on the first capacitor 106.

[0139] It should be understood that the first signal and the second signal can be in different domains, such as the digital domain. In this case, the first signal can be a digital representation of a first voltage, and the second signal can be a digital representation of a second voltage. This allows the controller to operate in a lower voltage domain while controlling the output voltage in a different (typically higher) voltage domain.

[0140] The comparator can be configured such that the comparison is based on an auxiliary voltage present on the auxiliary winding only during the primary stroke. In other examples, the comparison may be based on an auxiliary voltage present on the auxiliary winding only during the primary stroke and only during the initial portion of the secondary stroke.

[0141] It should be understood that the controller 102 can be configured not to output an overvoltage signal 302 during the secondary stroke 206 of the SMPS 100.

[0142] While the above description focuses on controller 102, SMPS including controller 102 are also disclosed, such as Figure 1 and 2 As shown in Figure 7.

[0143] It should be understood that various types of power supply architectures can be used. Figure 1 In the example shown, SMPS102 includes an asymmetric half-bridge (AHB) topology.

[0144] Figure 8 An example method for controlling an SMPS100 is outlined. The method includes comparing, 802, the auxiliary voltage during the primary stroke of the SMPS with a threshold indicating a predetermined maximum first capacitor voltage (Vcrmax) via the SMPS controller. The method further includes outputting an overvoltage signal, 804, indicating an overvoltage across the first capacitor, based on the comparison via the SMPS controller.

[0145] Unless a specific order is explicitly stated, the instructions and / or flowchart steps in the above diagrams may be performed in any order. Furthermore, those skilled in the art will recognize that while one example set of instructions / methods has been discussed, the material in this specification can be combined in various ways to produce other examples, and should be understood within the context of the detailed description provided herein.

[0146] In some example embodiments, the instruction set / method steps described above are implemented as functional and software instructions embodied in an executable instruction set, which is implemented on a computer or a machine programmed and controlled by the executable instructions. Such instructions are loaded to execute on a processor (e.g., one or more CPUs). The term processor includes a microprocessor, microcontroller, processor module or subsystem (containing one or more microprocessors or microcontrollers), or other control or computing device. A processor may refer to a single component or multiple components.

[0147] In other examples, the instruction sets / methods illustrated herein, along with their associated data and instructions, are stored in appropriate storage devices, which are implemented as one or more non-transitory machine- or computer-readable or computer-usable storage media. Such computer-readable or computer-usable storage media are considered part of an article (or article of manufacture). An article or article of manufacture can refer to any single or multiple manufactured components. Non-transitory machine- or computer-usable media as defined herein do not contain signals, but such media may be capable of receiving and processing information from signals and / or other transient media.

[0148] Example embodiments of the materials discussed in this specification may be implemented, in whole or in part, via networks, computers, or data-based devices and / or services. These may include cloud, internet, intranet, mobile devices, desktop computers, processors, lookup tables, microcontrollers, consumer devices, infrastructure, or other enabling devices and services. As may be used herein and in the claims, the following non-exclusive definitions are provided.

[0149] In one example, one or more instructions or steps discussed herein are automated. The terms automated or automatic (and similar variations) mean the use of computers and / or mechanical / electrical devices to control the operation of equipment, systems, and / or processes without human intervention, observation, effort, and / or decision-making.

[0150] It should be understood that any components that are allegedly to be coupled can be coupled or connected directly or indirectly. In the case of indirect coupling, an additional component may be placed between the two allegedly coupled components.

[0151] In this specification, exemplary embodiments have been presented according to a selected set of details. However, those skilled in the art will understand that many other exemplary embodiments, including different selected sets of details, can be practiced. It is intended that the appended claims cover all possible exemplary embodiments.

Claims

1. A controller for a switch mode power supply (SMPS), characterized in that: The SMPS includes: a primary winding configured to receive an input voltage at a first end of the primary winding; a first capacitor coupled in series between a second end of the primary winding and a reference end configured to be coupled to a reference voltage; and a secondary winding configured to provide an output voltage of the SMPS based on the input voltage; and an auxiliary winding inductively coupled to one or both of the primary winding and the secondary winding and configured to provide an auxiliary voltage based on at least a voltage of the first capacitor; Wherein the controller is configured to output an overvoltage signal indicative of an overvoltage across the first capacitor based on a comparison of the auxiliary voltage during a primary stroke of the SMPS with a threshold indicative of a predetermined maximum first capacitor voltage.

2. The controller according to claim 1, characterized in that: The comparison comprises a comparison between the threshold and a difference between the input voltage and the auxiliary voltage.

3. A controller according to any preceding claim, characterised in that The controller is configured to control the SMPS to stop charging the first capacitor in response to the overvoltage signal.

4. The controller according to claim 3, characterized in that: The controller is thereby configured to control a duration for charging the first capacitor during each primary stroke based at least in part on the overvoltage signal.

5. A controller according to any preceding claim, characterised in that The controller comprises: a first input terminal configured to receive a first voltage indicative of the input voltage; a second input terminal configured to receive a second voltage indicative of the auxiliary voltage; and a comparator configured to receive a first signal indicative of the first voltage, and a second signal indicative of the second voltage, wherein the comparator is further configured to output the overvoltage signal indicative of an overvoltage across the first capacitor based on the second signal and the first signal during the primary stroke of the SMPS and the threshold indicative of the predetermined maximum first capacitor voltage.

6. The controller according to claim 5, characterized in that: The first signal is based on a difference between the first voltage and the threshold value indicative of the predetermined maximum first capacitor voltage.

7. The controller according to claim 5 or 6, characterized in that: The comparator is configured to output the overvoltage signal when the second signal exceeds the first signal.

8. A controller according to any preceding claim, characterised in that The controller is configured to shorten the duration of the primary stroke in response to output of the overvoltage signal, thereby limiting the voltage to which the first capacitor is charged during one or more subsequent primary strokes of the SMPS.

9. A switch mode power supply SMPS, characterized in that: Comprising a controller according to any preceding claim, the SMPS comprising: the primary winding configured to receive an input voltage at the first end of the primary winding; and the first capacitor coupled in series between the second end of the primary winding and the reference end; the secondary winding configured to provide an output voltage of the SMPS based on the input voltage; and The auxiliary winding is configured to provide an auxiliary voltage based on at least the first capacitor voltage.

10. A method for controlling a switch mode power supply (SMPS), characterized in that: The SMPS includes: a primary winding configured to receive an input voltage at a first end of the primary winding; a first capacitor coupled in series between a second end of the primary winding and a reference end configured to be coupled to a reference voltage; and a secondary winding configured to provide an output voltage of the SMPS based on the input voltage; and an auxiliary winding inductively coupled to one or both of the primary winding and the secondary winding and configured to provide an auxiliary voltage based on at least a voltage of the first capacitor; The method comprises: comparing, by a controller of the SMPS, the auxiliary voltage during a primary stroke of the SMPS with a threshold value indicative of a predetermined maximum first capacitor voltage; and An overvoltage signal indicative of an overvoltage across the first capacitor is output by the controller of the SMPS based on the comparison.

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