Curvature slope compensation circuit and converter

Abstract

The invention provides a curvature slope compensation circuit and a converter, and relates to the technical field of converters, and a selection module determines whether the circuit works in a fixed compensation mode or a curvature slope compensation mode according to the magnitude relationship between an input voltage and a switch node voltage. The curvature slope current module generates curvature slope current; the current output module generates and outputs a first slope compensation current by taking the curvature slope current as input when the circuit works in the curvature slope compensation mode, and generates and outputs a second slope compensation current by taking the fixed current as input when the circuit works in the fixed compensation mode. When slope compensation is needed, the slope current which has the high-order curvature and fits the minimum value of the required slope current slope corresponding to different duty ratios is generated, the fit degree of slope compensation is improved, and the problems of overcompensation and insufficient compensation are effectively reduced. When the slope compensation is not needed, the slope current with a fixed slope is generated, and the stability under a low duty ratio is improved.

Description

Technical Field

[0001] This application relates to the field of converter technology, and in particular to a curvature ramp compensation circuit and converter. Background Technology

[0002] A typical current-mode DC-DC converter (referring to a DC-DC converter, a device in a DC circuit that converts electrical energy from one voltage value to another) operates with a duty cycle greater than... Slope compensation is required to prevent potential subharmonic oscillations.

[0003] Currently, the slope of traditional slope compensation current is generally a fixed value or segmented form. However, in actual applications, the slope of the required slope current varies under different duty cycles. Both of these methods can lead to overcompensation or undercompensation of the slope current, with the fixed value slope compensation method being particularly serious.

[0004] Overcompensation of the ramp current will reduce the gain of the DC-DC converter, while insufficient compensation may lead to subharmonic oscillations. Summary of the Invention

[0005] In view of the above problems, this application proposes a curvature slope compensation circuit and converter to overcome the shortcomings of the prior art.

[0006] In a first aspect, embodiments of this application provide a curvature ramp compensation circuit, which includes: a selection module, a curvature ramp current module, and a current output module; The selection module is used to determine whether the curvature slope compensation circuit operates in fixed compensation mode or curvature slope compensation mode based on the relationship between the input voltage and the switching node voltage. The curvature ramp current module is used to generate curvature ramp current when the curvature ramp compensation circuit is operating in the curvature ramp compensation mode. The current output module is used to generate and output a first slope compensation current with the curvature slope current as input when the curvature slope compensation circuit is working in the curvature slope compensation mode, and to generate and output a second slope compensation current with a fixed current as input when the curvature slope compensation circuit is working in the fixed compensation mode. Wherein, the first slope compensation current is a slope current with high-order curvature and different duty cycles that fits the minimum slope value of the required slope current corresponding to each duty cycle. The second slope compensation current is a slope current with a fixed slope.

[0007] Optionally, the selection module is specifically used to: determine whether the curvature ramp compensation circuit operates in the fixed compensation mode or the curvature ramp compensation mode based on the comparison result between the voltage division value of the input voltage and the target voltage value, wherein the target voltage value refers to the voltage value obtained after the switching node voltage is low-pass filtered; Wherein, when the voltage divider value is not less than the target voltage value, it indicates that the real-time duty cycle is not greater than the preset duty cycle, and the curvature ramp compensation circuit operates in the fixed compensation mode. When the voltage divider value is less than the target voltage value, it indicates that the real-time duty cycle is greater than the preset duty cycle, and the curvature slope compensation circuit operates in the curvature slope compensation mode.

[0008] Optionally, the selection module includes: a low-pass filter unit, a voltage divider unit, and a comparison unit; The first terminal of the low-pass filter unit receives the voltage of the switching node, and the second terminal is connected to the first input terminal of the comparator unit. The first terminal of the voltage divider unit receives the input voltage, and the second terminal is connected to the second input terminal of the comparator unit. The output terminal of the comparison unit outputs a mode selection signal, which is used to determine whether the curvature ramp compensation circuit operates in the fixed compensation mode or the curvature ramp compensation mode.

[0009] Optionally, the curvature ramp current module includes: multiple unit structures; Multiple of the aforementioned unit structures are cascaded together when the curvature slope compensation circuit operates in the curvature slope compensation mode. m The series, the m Each series contains a different number of unit structures; In each series, the first unit structure uses a preset current as input, and the second unit structure... n The unit structure is based on the first n If the output current of the -1 unit structure is used as the input, then the... n The output current of each unit structure is proportional to the real-time duty cycle. n The power; the output currents of the last unit structure in each cascaded structure in each series are added together to form the curvature ramp current; The m The number of terms is determined by the number of terms in the chosen functional relation; the number of unit structures contained in each series is determined by the target value in the corresponding term.

[0010] Optionally, the unit structure includes: a first accumulation capacitor, a sampling capacitor, a first grounding switch, a transmission gate, a sampling structure, and a first conversion structure; The first terminal of the first accumulation capacitor is connected to the first terminal of the first grounding switch and the first terminal of the transmission gate, respectively, and receives the preset current or the output current of the preceding unit structure cascaded with it; the second terminal of the first accumulation capacitor is grounded. The second terminal of the first grounding switch is grounded, and the first grounding switch is controlled by the opening and closing status of the low-side switch; The second end of each transmission gate is connected to the first end of the sampling capacitor and the first end of the sampling structure. The transmission gate is controlled by the opening and closing of the high-side switch and the low-side switch. The second terminal of the sampling capacitor is grounded; The second end of the sampling structure is connected to the first end of the first conversion structure; The second terminal of the first conversion structure outputs the output current of the unit structure.

[0011] Optionally, during the one switching cycle, the preset current or the output current of the previous unit structure cascaded with the target unit structure accumulates on the first terminal of the first accumulation capacitor in the target unit structure to form a first voltage; If the high-side switch is turned on, the first grounding switch is turned off, and the first voltage is transmitted to the first terminal of the sampling capacitor in the target unit structure to form a second voltage. The sampling structure in the target unit structure does not sample, and the sampling result of the second voltage in the previous switching cycle is maintained. If the low-side switch is turned on, the first grounding switch is closed, the preset current or the output current of the previous unit structure cascaded with the target unit structure is directly grounded, and the sampling structure samples the second voltage in the current switching cycle. In the target unit structure, the first conversion structure receives a third voltage from the output of the sampling structure and uses the current converted from the third voltage as the output current of the target unit. The voltage value of the third voltage is the maximum voltage value accumulated by the first voltage during one switching cycle.

[0012] Optionally, the current output module includes: a second accumulation capacitor, a second grounding switch, and a second conversion structure; The first terminal of the second accumulation capacitor is connected to the first terminal of the second grounding switch and the first terminal of the second conversion structure, respectively, and receives the curvature ramp current or the fixed current. The second terminal of the second grounding switch is grounded. The second grounding switch is closed when the low-side switch in the target unit structure is turned on, and is opened when the low-side switch is turned off. When the high-side switch is turned on and the low-side switch is turned off in the target unit structure, the second conversion structure outputs the first slope compensation current or the second slope compensation current. When the high-side switch is turned off and the low-side switch is turned on, the output current is zero.

[0013] Optionally, the functional relationship y as follows:

[0014] In the above formula, a , b , c … z They represent the conventional coefficients, x Indicates the real-time duty cycle. n This represents the target value. a , , … Each term of the functional relationship is represented separately. When the number of terms in the selected functional relation is 3, m =3, the selected functional relationship is the functional relationship. y Any three items in the list; The larger the target value, the closer the first slope compensation current is to the minimum slope of the required slope current under different duty cycles.

[0015] Optionally, the value of the preset duty cycle is controlled by the voltage division ratio of the input voltage; The preset duty cycle value is set to 0.5 or slightly less than 0.5.

[0016] This application provides a converter that includes a curvature ramp compensation circuit as described above.

[0017] The curvature slope compensation circuit provided in this application uses a selection module to determine whether the circuit operates in a fixed compensation mode or a curvature slope compensation mode based on the relationship between the input voltage and the switching node voltage. The curvature slope current module generates a curvature slope current when the circuit operates in curvature slope compensation mode. The current output module uses the curvature slope current as input to generate and output a first slope compensation current when the circuit operates in curvature slope compensation mode, and uses a fixed current as input to generate and output a second slope compensation current when the circuit operates in fixed compensation mode. The first slope compensation current is a slope current with a high-order curvature that matches the minimum slope value of the corresponding required slope current under different duty cycles; the second slope compensation current is a slope current with a fixed slope.

[0018] This application creatively proposes a curvature slope compensation circuit to address the problems of overcompensation or undercompensation of slope current in traditional slope compensation methods. When slope compensation is required, it generates a slope current with high-order curvature that matches the minimum slope value corresponding to different duty cycles, improving the accuracy of slope compensation and effectively reducing overcompensation and undercompensation. When slope compensation is not required, it generates a slope current with a fixed slope, improving stability at low duty cycles and demonstrating high practicality. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a modular schematic diagram of the curvature slope compensation circuit according to an embodiment of this application; Figure 2 This is a structural diagram of a preferred selection module in an embodiment of this application; Figure 3 This is a preferred unit structure circuit diagram in the embodiments of this application; Figure 4 This is a diagram showing the voltage changes of the first voltage V1, the second voltage V2, and the third voltage V3 in the embodiments of this application; Figure 5 This application embodiment is formed by calling and cascading multiple unit structures. Structural diagrams of each series; Figure 6 This is a circuit diagram of a preferred current output module in an embodiment of this application; Figure 7 In this embodiment of the application, assuming the input current is a fixed current, the voltage V accumulated at the first terminal of the second accumulation capacitor C3 during one switching cycle is... slope Voltage diagram; Figure 8 In this embodiment of the application, simulation is used to... Within the interval, the fitting function of this application The function obtained from the original solution In comparison, using the fitted function and the original solution function For example, let's take another function representing the piecewise ramp current. (This only indicates its) The function curve is obtained by comparing the segmented parts of the graph with the segmented parts of the graph. Detailed Implementation

[0020] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] The inventors discovered that the slope of traditional slope compensation current is generally a fixed value or segmented, while the required slope of the slope current varies under different duty cycles in practical applications. Both of these methods can lead to overcompensation or undercompensation of the slope current. Overcompensation of the slope current will reduce the gain of the DC-DC converter, while undercompensation may lead to subharmonic oscillations.

[0022] To address the aforementioned problem, the inventors further investigated and found that, assuming the slope of the current provided by the slope compensation is set as... The slope of the inductor sense current during the conduction period of the HighSide Switch (indicating that the power switch is on the side with higher load potential) is set to... The slope of the inductor sense current during the conduction period of the LowSide Switch (indicating that the power switch is on the side of the load with low potential) is set to... To avoid subharmonic oscillations, the following conditions must be met: .

[0023] Based on the above conditions, x Indicates real-time duty cycle D The function can be solved as follows: , , The minimum slope required for slope compensation current. This is a constant term, determined by the specific DC-DC circuit, while hour, That's it; theoretically, slope compensation is not needed at this point.

[0024] Based on the above function, slope compensation can be effectively achieved. However, this function is difficult to implement in circuits, requiring numerous components and extremely complex structures. This is clearly detrimental to the further research and development and fabrication of DC-DC converters.

[0025] To solve this problem, the inventors creatively proposed refitting the aforementioned function within a reasonable range, taking into account circuit design and manufacturing complexity, to obtain a fitting function. Circuit design methods. Represents real-time duty cycle The highest power, The larger the value, the higher the fit, and the closer the slope compensation is to the aforementioned solution function, that is, the better its fit.

[0026] Furthermore, theoretically, although slope compensation only applies to real-time duty cycle... It is only needed when necessary, but in practical applications, in order to further improve stability at low duty cycles, At that time, a current with a fixed slope is provided, while Then, provide the normal slope compensation current. For the preset duty cycle, the recommended value is generally slightly less than 0.5, or simply 0.5.

[0027] Based on the above-mentioned creatively proposed fitting function Taking into account the complexity of circuit design and manufacturing, this application proposes a curvature slope compensation circuit, which includes: a selection module, a curvature slope current module, and a current output module.

[0028] Reference Figure 1 The diagram shows a modular design for the curvature slope compensation circuit: The selection module is used to determine whether the curvature slope compensation circuit operates in fixed compensation mode or curvature slope compensation mode based on the relationship between the input voltage and the voltage at the switching node.

[0029] The curvature ramp current module is used to generate curvature ramp current when the curvature ramp compensation circuit is operating in curvature ramp compensation mode. Naturally, it is understandable that no curvature ramp current is generated when the curvature ramp compensation circuit is not operating in curvature ramp compensation mode.

[0030] The current output module is used to generate and output a first slope compensation current when the curvature slope compensation circuit operates in curvature slope compensation mode, using the curvature slope current as input; and to generate and output a second slope compensation current when the curvature slope compensation circuit operates in fixed compensation mode, using a fixed current as input. The first slope compensation current is a slope current with a high-order curvature that corresponds to the minimum slope of the required slope current for different duty cycles; the second slope compensation current is a slope current with a fixed slope. This achieves the aforementioned... At that time, a current with a fixed slope is provided, while At that time, based on the fitting function Its characteristics provide a slope compensation current with high-order curvature that fits the minimum slope value of the required slope current corresponding to different duty cycles.

[0031] For the selection module, the operating mode of the curvature ramp compensation circuit is determined based on the duty cycle, i.e., the ratio of the DC-DC output voltage to the input voltage. There are several ways to obtain the duty cycle (the ratio of the DC-DC output voltage to the input voltage), one of the more preferred methods being: The selection module determines the compensation mode for the curvature ramp compensation circuit based on the comparison between the input voltage's divided value and the target voltage value. The target voltage value refers to the voltage obtained after low-pass filtering the switching node voltage. The requirement for the target voltage value is to obtain a precise switching node voltage, which is essential for accurately determining the real-time duty cycle. D Compared with the preset duty cycle D The size relationship of 0.

[0032] When the voltage divider value of the input voltage is not less than the target voltage value, it represents the real-time duty cycle. D Not greater than the preset duty cycle D If the value is 0, the curvature ramp compensation circuit operates in fixed compensation mode; when the voltage division value of the input voltage is less than the target voltage value, it represents the real-time duty cycle. D Greater than the preset duty cycle D If the value is 0, the curvature slope compensation circuit operates in curvature slope compensation mode.

[0033] A better selection module structure can be referred to Figure 2 As shown, the selection module includes a low-pass filter unit, a voltage divider unit, and a comparator unit. The first terminal of the low-pass filter unit receives the switching node voltage, and the second terminal is connected to the first input terminal (usually the non-inverting terminal) of the comparator unit. After the switching node voltage is filtered by the low-pass filter unit, the target voltage value is obtained and input to the comparator unit.

[0034] The first terminal of the voltage divider unit receives the input voltage, and the second terminal is connected to the second input terminal (usually the inverting terminal) of the comparator unit. After the input voltage passes through the voltage divider unit, its corresponding voltage division value is obtained and input to the comparator unit.

[0035] The comparator unit outputs a mode selection signal, which determines whether the curvature ramp compensation circuit operates in fixed compensation mode or curvature ramp compensation mode. That is, when... When the comparator unit's output mode selection signal determines that the curvature ramp compensation circuit operates in fixed compensation mode, the curvature ramp current module does not operate; when At this time, the comparator unit's output mode selection signal determines that the curvature slope compensation circuit operates in curvature slope compensation mode, and the curvature slope current module operates. Therefore, it can also be known that the preset duty cycle... D The value of 0 can be adjusted by the voltage division ratio of the input voltage; preset duty cycle. DThe value of 0 can generally be set to 0.5 or slightly less than 0.5.

[0036] The curvature ramp current module includes: multiple unit structures; these multiple unit structures are cascaded together when the curvature ramp compensation circuit operates in curvature ramp compensation mode. m This series m Each series contains a different number of unit structures.

[0037] In this system, the first unit structure in each series uses a preset current as its input, the output current of the first unit structure serves as the input of the second unit structure cascaded with it, the output current of the second unit structure serves as the input of the third unit structure cascaded with it, and so on. n The unit structure is based on the first n If the output current of the -1 unit structure is used as the input, then the... n The output current of each unit structure is proportional to the real-time duty cycle. D of n Power of 1. m Each series contains a different number of unit structures. The output currents of the last unit structure in each series' cascaded structure are added together to form a curvature ramp current. For example: m =3, then each of the three series contains a different number of unit structures. The output current of the last unit structure in the cascaded structure of each series is added to the output current of the last unit structure in the cascaded structure of the other two series to form the curvature ramp current.

[0038] The above-mentioned m The number of terms is determined by the number of terms in the chosen functional relationship; the number of unit structures, n, contained in each series is determined by the target value in the corresponding term. The so-called functional relationship is the fitting function mentioned above. y This can be pre-set as a preset functional relationship. The value of m is determined according to the requirements, thus specifying the number of terms and the target value of the selected functional relationship. As mentioned earlier, the fitting function... y The expression is as follows:

[0039] In the above formula, a , b , c … z They represent the conventional coefficients, x Indicates real-time duty cycle D , n Indicates the target value. a , , … Each term of the preset functional relation is represented; that is, when the number of terms in the preset functional relation is 3... m =3, the selected preset function relationship is the fitting function relationship. y Any three items in the list, for example, can be: It can also be: And so on; naturally, it is understandable that... m When = 5, the selected preset function relationship is the fitted function relationship. y Any five items in the list, for example, can be: And so on. The other cases follow the same logic, and will not be elaborated upon one by one.

[0040] Target value n The larger the value, the closer the first slope compensation current is to the minimum slope of the required slope current under different duty cycles. In other words, the higher the goodness of fit of the curvature slope current generated by the curvature slope current module corresponding to the determined selected functional relationship, the closer the slope compensation is to the aforementioned solved function.

[0041] A preferred unit structure includes: a first accumulation capacitor, a sampling capacitor, a first grounding switch, a transmission gate, a sampling structure, and a first conversion structure. For a better understanding of this preferred unit structure, refer to... Figure 3 The diagram shown is a preferred unit structure circuit diagram of an embodiment of this application. Figure 3 The nth unit structure is used as an example for illustration: The first terminal of the first accumulation capacitor C1 is connected to the first terminal of the first grounding switch LS1, and the transmission gate ( Figure 3 The first terminals of the two control signals (HS and LS representing the transmission gate) are respectively connected to receive a preset current or the output current of the preceding unit structure (i.e., the (n-1)th unit structure) cascaded with it. Figure 3 For the sake of simplicity in the illustration, I is used as an example. ref（n-1） (This indicates that the second terminal of the first accumulation capacitor C1 is grounded).

[0042] The second terminal of the first grounding switch LS1 is grounded, and the first grounding switch LS1 is controlled by the opening and closing of the low-side switch LS; the second terminal of the transmission gate is connected to the first terminal of the sampling capacitor C2 and the first terminal of the sampling structure Sample respectively, and the transmission gate is controlled by the opening and closing of the high-side switch and the low-side switch.

[0043] The second terminal of sampling capacitor C2 is grounded; the second terminal of sampling structure Sample is connected to the first terminal of the first conversion structure V to I1; the second terminal of the first conversion structure V to I1 outputs the output current I of this unit structure. refnIn this process, the transfer function of the first transformation structure V to I1 is numerically equivalent to... The output current is:

[0044] In the above formula, Indicates the switching cycle. This indicates the on-time of the high-side switch HS within one switching cycle.

[0045] Within one switching cycle, the preset current or the output current I of the previous unit structure cascaded with the target unit structure. ref（n-1） In the target unit structure ( Figure 3 The first voltage V1 is formed by accumulating on the first terminal of the first accumulation capacitor C1 in the nth unit structure.

[0046] If the high-side switch is turned on, the first grounding switch LS1 is turned off, and the first voltage V1 is transmitted to the first terminal of the sampling capacitor C2 in the target unit structure to form the second voltage V2. The sampling structure Sample in the target unit structure does not sample, and the sampling result of the second voltage V2 in the previous switching cycle is maintained.

[0047] If the low-side switch is turned on, the first grounding switch LS1 is closed, and the preset current or the output current I of the previous unit structure cascaded with the target unit structure is applied. ref（n-1） Directly grounded, the sampling structure Sample samples the second voltage V2 in the current switching cycle.

[0048] In the target cell structure, the first conversion structure V to I1 receives the third voltage V3 output from the sampling structure Sample, and uses the current converted from the third voltage V3 as the output current I of the target cell. refn The voltage value of the third voltage V3 is the maximum voltage value accumulated by the first voltage V1 during one switching cycle.

[0049] The voltage changes of the first voltage V1, the second voltage V2, and the third voltage V3 are as follows: Figure 4 As shown, Figure 4 The horizontal axis represents the switching cycle, and the vertical axis represents the voltage value of each voltage. It can be seen that the voltage value of the third voltage V3 is always the maximum voltage value accumulated by the first voltage V1 in one switching cycle.

[0050] Based on the above theory and circuit structure, it can be seen that: a unit structure provides one Proportional to real-time duty cycle The transfer function. Multiple unit structures can then be called and cascaded to form... Each series, refer to Figure 5 The multiple unit structures shown are called and cascaded to form Structural diagrams of each series.

[0051] The input to the first unit structure of each series is a single fixed current. , No. The input of the unit structure is the first Output of each module Then the first Output current of each unit structure Proportional to real-time duty cycle of Power of 1. Figure 5 Examples shown in In this series, the series above has n unit structures, and its output current... One of the middle series has n-1 unit structures, and its output current... The following series has n-2 unit structures, and its output current... The same logic applies to other cases, and will not be elaborated further.

[0052] Each of the series uses a different approach. The value can be determined according to different proportions after the output current of the last unit structure is generated. The final current is obtained by mirroring the image. The final current of each series is added together to obtain the current. That is, it conforms to the form of the fitted function.

[0053] For the current output module, it can determine different input currents based on the compensation model of the circuit operation determined by the selected module, and generate a ramp current with a fixed slope or a ramp current with a slope that conforms to the above fitting function relationship.

[0054] A preferred structure for a current output module includes: a second accumulation capacitor, a second grounding switch, and a second conversion structure. (Refer to...) Figure 6 The circuit diagram shown is of a preferred current output module: The first terminal of the second accumulation capacitor C3 is connected to the first terminal of the second grounding switch LS2 and the first terminal of the second switching structure V to I2, respectively, and receives the curvature ramp current. Or a fixed current .

[0055] The second terminal of the second grounding switch LS2 is grounded. The second grounding switch LS2 is closed when the low-side switch in the target unit structure is on and open when the low-side switch is off.

[0056] When the high-side switch of the second conversion structure V to I2 is turned on and the low-side switch is turned off in the target unit structure, it outputs either the first ramp compensation current or the second ramp compensation current. ( Figure 6 For the sake of simplicity in the illustration, the example of uniformity is as follows: (Representing the first and second slope compensation currents), the output current is zero when the high-side switch is open and the low-side switch is on. The transfer function of the second conversion structure V to I2 is numerically equivalent to... .

[0057] During one switching cycle, assuming the input current is a fixed current and the voltage V accumulated at the first terminal of the second accumulation capacitor C3 is... slope like Figure 7 As shown, the output first or second ramp compensation current The slope is This is the final required slope compensation current.

[0058] The first slope compensation current obtained through the structure of the curvature slope compensation circuit described above achieves the target of the aforementioned fitting function, namely, the real-time duty cycle. At that time, a ramp current with a constant slope is provided, and the real-time duty cycle is... When, provide a slope of The slope current. In practical applications, the curvature slope compensation circuit proposed in this application can be selected based on trade-offs considering factors such as fit, area, and circuit complexity, according to actual needs. Values ​​and corresponding number of terms m The corresponding coefficients are used to minimize overcompensation and undercompensation, thereby reducing the number of components and circuit complexity, and reducing circuit area overhead.

[0059] To verify the effectiveness and accuracy of the curvature slope compensation circuit proposed in this application, simulation was used to... Within the interval, the fitting function of this application The function obtained from the original solution In comparison, using the fitted function and the original solution function For example, let's take another function representing the piecewise ramp current. (This only indicates its) By comparing the segmented parts, we obtain Figure 8 The graph shown.

[0060] Figure 8 The horizontal axis represents the real-time duty cycle. DThe vertical axis represents the compensation current value, and the dashed line formed by the points represents the curve corresponding to the piecewise slope current function. It can be seen that it is almost a current function curve with a fixed slope. The solid line represents the curve corresponding to the curvature slope compensation circuit proposed in this application, and the dashed line formed by the short horizontal lines represents the curve corresponding to the original solution function. It can be seen that the slope compensation scheme of the curvature slope compensation circuit proposed in this application is closer to the original solution function. Moreover, by adjusting the number of terms m and the target value n, it is possible to minimize overcompensation without undercompensation. Furthermore, the circuit structure is simple and has obvious advantages.

[0061] Although theoretically, if a piecewise ramp current compensation method is used, the number of pieces in the piecewise function... As it approaches infinity, the corresponding curve can also infinitely match the original solution's function curve, but in the number of pieces... When the value is large, not only is a larger silicon area sacrificed, resulting in significant area overhead, but the duty cycle corresponding to adjacent segments also increases. The difference is reduced. Traditional methods, such as using comparators to determine segmentation, are limited by the comparator's gain and offset, making it difficult to achieve precise segmentation. Furthermore, each segment has a different transfer function, placing high demands on the comparator and operational amplifier, making implementation difficult. The curvature slope compensation circuit proposed in this application, however, aims to reduce the target value... When the value is large, only more unit structures need to be called, and there will be no excessive design restrictions.

[0062] Furthermore, based on fundamental circuit theory, the first slope compensation current output by the curvature slope compensation circuit proposed in this application only needs to pass through a resistor to obtain a voltage corresponding to a higher curvature. Therefore, the higher curvature current and voltage generated by the above-mentioned technical solution can be applied to any circuit structure with higher curvature requirements for current and voltage, and is not limited to slope compensation alone, thus greatly expanding the application range of its circuit structure and exhibiting good scalability.

[0063] In this application embodiment, based on the above curvature slope compensation circuit, a converter is also proposed, the converter including any of the curvature slope compensation circuits described above.

[0064] In summary, the curvature slope compensation circuit of this application determines whether it operates in a fixed compensation mode or a curvature slope compensation mode based on the relationship between the input voltage and the switching node voltage. The curvature slope current module generates a curvature slope current when the circuit operates in curvature slope compensation mode; the current output module generates and outputs a first slope compensation current using the curvature slope current as input when the circuit operates in curvature slope compensation mode, and generates and outputs a second slope compensation current using a fixed current as input when the circuit operates in fixed compensation mode. The first slope compensation current is a slope current with a high-order curvature that corresponds to the minimum slope of the required slope current for different duty cycles; the second slope compensation current is a slope current with a fixed slope.

[0065] This application creatively proposes a curvature slope compensation circuit to address the problems of overcompensation or undercompensation of slope current in traditional slope compensation methods. When slope compensation is needed, it generates a slope current with a high-order curvature that matches the minimum slope required for different duty cycles, improving the accuracy of slope compensation and effectively reducing overcompensation and undercompensation. When slope compensation is not needed, it generates a slope current with a fixed slope, improving stability at low duty cycles and demonstrating high practicality.

[0066] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0067] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0068] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.

Claims

1. A curvature ramp compensation circuit, characterized in that, The curvature ramp compensation circuit includes: a selection module, a curvature ramp current module, and a current output module; The selection module is used to determine whether the curvature slope compensation circuit operates in fixed compensation mode or curvature slope compensation mode based on the relationship between the input voltage and the switching node voltage. The curvature ramp current module is used to generate curvature ramp current when the curvature ramp compensation circuit is operating in the curvature ramp compensation mode. The current output module is used to generate and output a first slope compensation current with the curvature slope current as input when the curvature slope compensation circuit is working in the curvature slope compensation mode, and to generate and output a second slope compensation current with a fixed current as input when the curvature slope compensation circuit is working in the fixed compensation mode. Wherein, the first slope compensation current is a slope current with high-order curvature and different duty cycles that fits the minimum slope value of the required slope current corresponding to each duty cycle. The second slope compensation current is a slope current with a fixed slope.

2. The curvature ramp compensation circuit according to claim 1, characterized in that, The selection module is specifically used to: determine whether the curvature ramp compensation circuit operates in the fixed compensation mode or the curvature ramp compensation mode based on the comparison result between the voltage division value of the input voltage and the target voltage value, wherein the target voltage value refers to the voltage value obtained after the switching node voltage is low-pass filtered; Wherein, when the voltage divider value is not less than the target voltage value, it indicates that the real-time duty cycle is not greater than the preset duty cycle, and the curvature ramp compensation circuit operates in the fixed compensation mode. When the voltage divider value is less than the target voltage value, it indicates that the real-time duty cycle is greater than the preset duty cycle, and the curvature slope compensation circuit operates in the curvature slope compensation mode.

3. The curvature ramp compensation circuit according to claim 2, characterized in that, The selection module includes: a low-pass filter unit, a voltage divider unit, and a comparison unit; The first terminal of the low-pass filter unit receives the voltage of the switching node, and the second terminal is connected to the first input terminal of the comparator unit. The first terminal of the voltage divider unit receives the input voltage, and the second terminal is connected to the second input terminal of the comparator unit. The output terminal of the comparison unit outputs a mode selection signal, which is used to determine whether the curvature ramp compensation circuit operates in the fixed compensation mode or the curvature ramp compensation mode.

4. The curvature ramp compensation circuit according to claim 1, characterized in that, The curvature ramp current module includes: multiple unit structures; Multiple of the aforementioned unit structures are cascaded together when the curvature slope compensation circuit operates in the curvature slope compensation mode. m The series, the m Each series contains a different number of unit structures; In each series, the first unit structure uses a preset current as input, and the second unit structure... n The unit structure is based on the first n If the output current of the -1 unit structure is used as the input, then the... n The output current of each unit structure is proportional to the real-time duty cycle. n The power; the output currents of the last unit structure in each cascaded structure in each series are added together to form the curvature ramp current; The m The number of terms is determined by the number of terms in the chosen functional relation; the number of unit structures contained in each series is determined by the target value in the corresponding term.

5. The curvature ramp compensation circuit according to claim 4, characterized in that, The unit structure includes: a first accumulation capacitor, a sampling capacitor, a first grounding switch, a transmission gate, a sampling structure, and a first conversion structure; The first terminal of the first accumulation capacitor is connected to the first terminal of the first grounding switch and the first terminal of the transmission gate, respectively, and receives the preset current or the output current of the preceding unit structure cascaded with it; the second terminal of the first accumulation capacitor is grounded. The second terminal of the first grounding switch is grounded, and the first grounding switch is controlled by the opening and closing status of the low-side switch; The second end of each transmission gate is connected to the first end of the sampling capacitor and the first end of the sampling structure. The transmission gate is controlled by the opening and closing of the high-side switch and the low-side switch. The second terminal of the sampling capacitor is grounded; The second end of the sampling structure is connected to the first end of the first conversion structure; The second terminal of the first conversion structure outputs the output current of the unit structure.

6. The curvature ramp compensation circuit according to claim 5, characterized in that, During the one switching cycle, the preset current or the output current of the previous unit structure cascaded with the target unit structure accumulates on the first terminal of the first accumulation capacitor in the target unit structure to form a first voltage; If the high-side switch is turned on, the first grounding switch is turned off, and the first voltage is transmitted to the first terminal of the sampling capacitor in the target unit structure to form a second voltage. The sampling structure in the target unit structure does not sample, and the sampling result of the second voltage in the previous switching cycle is maintained. If the low-side switch is turned on, the first grounding switch is closed, the preset current or the output current of the previous unit structure cascaded with the target unit structure is directly grounded, and the sampling structure samples the second voltage in the current switching cycle. In the target unit structure, the first conversion structure receives a third voltage from the output of the sampling structure and uses the current converted from the third voltage as the output current of the target unit. The voltage value of the third voltage is the maximum voltage value accumulated by the first voltage during one switching cycle.

7. The curvature ramp compensation circuit according to claim 1, characterized in that, The current output module includes: a second accumulation capacitor, a second grounding switch, and a second conversion structure; The first terminal of the second accumulation capacitor is connected to the first terminal of the second grounding switch and the first terminal of the second conversion structure, respectively, and receives the curvature ramp current or the fixed current. The second terminal of the second grounding switch is grounded. The second grounding switch is closed when the low-side switch in the target unit structure is turned on, and is opened when the low-side switch is turned off. When the high-side switch is turned on and the low-side switch is turned off in the target unit structure, the second conversion structure outputs the first slope compensation current or the second slope compensation current. When the high-side switch is turned off and the low-side switch is turned on, the output current is zero.

8. The curvature slope compensation circuit according to claim 4, characterized in that, The functional relationship y as follows: In the above formula, a , b , c … z They represent the conventional coefficients, x Indicates the real-time duty cycle. n This represents the target value. a , , … Each term of the functional relationship is represented separately. When the number of terms in the selected functional relation is 3, m =3, the selected functional relationship is the functional relationship. y Any three items in the list; The larger the target value, the closer the first slope compensation current is to the minimum slope of the required slope current under different duty cycles.

9. The curvature slope compensation circuit according to claim 2, characterized in that, The value of the preset duty cycle is controlled by the voltage division ratio of the input voltage; The preset duty cycle value is set to 0.5 or slightly less than 0.

5.

10. A converter, characterized in that, The converter includes the curvature ramp compensation circuit as described in any one of claims 1-9.

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