A method and system for dynamically limiting the maximum duty cycle of a digital power supply

Abstract

The present invention relates to the field of digital power supply control technology and discloses a method and system for dynamically limiting the maximum duty cycle of a digital power supply. The method comprises: determining an input voltage feedforward value Vin_Feed based on an input voltage filter value Vin_Filter and an input voltage instantaneous value Vin_Im of a target digital power supply; determining an output voltage maximum value Vout_Max based on an output voltage reference given value Vout_Ref of the target digital power supply; calculating a maximum duty cycle Duty_Max based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max, and limiting the output drive duty cycle Duty_set using the maximum duty cycle Duty_Max. The present invention can effectively resolve unnecessary overvoltage shutdowns caused by rapid changes in input voltage, effectively avoiding the risk of device damage due to untimely overvoltage protection.

Description

Technical Field

[0001] The present invention relates to the technical field of digital power supply control, and in particular to a method and system for dynamically limiting the maximum duty cycle of a digital power supply. Background Art

[0002] As power supplies continue to develop towards high power density, high integration and high flexibility, complex circuit topologies have been used more and more. Analog power chips can no longer meet the needs of power supplies with higher complexity, and the use of digital power supplies has received more and more attention and use.

[0003] In digital power supply control, average voltage control is generally adopted, that is, the given voltage and feedback voltage are closed-loop controlled, and the output voltage is stabilized by controlling the duty cycle of the power device.

[0004] Currently, a common control method involves outputting duty cycle information from the loop compensation function and applying a maximum limit to this duty cycle information. This means limiting the maximum duty cycle by limiting the maximum value of the control loop output. This is often achieved by using a fixed value or fine-tuning around a fixed value based on experimental results. Another method involves adding a voltage increment to the actual output voltage to achieve maximum duty cycle limitation. However, this method has the disadvantage that the higher the actual output voltage, the greater the maximum duty cycle. However, when the input voltage changes rapidly, the loop has little time to react. In such cases, when the output duty cycle remains virtually unchanged, excessive input voltage can cause a rapid rise in the output voltage. In such cases, neither a fixed value limit nor the addition of a voltage increment to the actual output voltage can effectively suppress this rapid rise in output voltage. This situation can easily lead to unnecessary output overvoltage shutdown of the power supply, impacting practical use. There is even a risk of component damage if output overvoltage protection is not implemented in a timely manner. Furthermore, in some special applications, output overvoltage can damage downstream loads, resulting in severe consequences. Summary of the Invention

[0005] To address the aforementioned issues, the present invention proposes a method and system for dynamically limiting the maximum duty cycle of a digital power supply. This method effectively addresses unnecessary overvoltage shutdowns caused by untimely loop response when the input voltage changes rapidly, effectively avoiding the risk of device damage caused by untimely overvoltage protection and effectively protecting downstream loads in specialized applications. Furthermore, the system can adjust the maximum duty cycle in real time when the output voltage setpoint changes, keeping it within a reasonable range and ensuring reliable operation.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A method for dynamically limiting the maximum duty cycle of a digital power supply, comprising:

[0008] Determine an input voltage feedforward value Vin_Feed based on an input voltage filter value Vin_Filter and an input voltage instantaneous value Vin_Im of a target digital power supply;

[0009] Determine the maximum output voltage Vout_Max based on the output voltage reference given value Vout_Ref of the target digital power supply;

[0010] Based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max, the maximum duty cycle Duty_Max is calculated, and the output drive duty cycle Duty_set is limited by the maximum duty cycle Duty_Max.

[0011] Furthermore, the calculation method of the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im of the target digital power supply includes:

[0012]

[0013] Where K is the filter coefficient, K ≥ 1 and is an integer. By adjusting the K value, the cutoff frequency of the filter can be adjusted. Vin is the input voltage. Vin_Im represents the instantaneous condition of the input voltage and can show the change of the input voltage in real time when the input voltage changes rapidly.

[0014] Furthermore, the step of determining the input voltage feedforward value Vin_Feed based on the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im of the target digital power supply includes:

[0015] Calculate the input voltage error value based on the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im ;

[0016] According to the input voltage error value and the maximum input voltage error , determine the input voltage feedforward value Vin_Feed.

[0017] Furthermore, the input voltage error value is calculated based on the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im. ,include:

[0018]

[0019] Where, is a symbolic function, It is the difference between the input voltage filtered value Vin_Filter and the input voltage instantaneous value Vin_Im.

[0020] Furthermore, the input voltage error value and the maximum input voltage error , determine the input voltage feedforward value Vin_Feed, including:

[0021]

[0022] In the formula, when the input voltage error value The fluctuation range of the input voltage error is the maximum value If the input voltage is within the range of 0.001, it means that the input voltage does not change much. At this time, the input voltage feedforward value Vin_Feed is assigned to the input voltage filter value Vin_Filter. When the input voltage error value is The fluctuation range exceeds the maximum input voltage error When , it indicates that the input voltage changes rapidly. At this time, the input voltage feedforward value Vin_Feed is assigned the input voltage instantaneous value Vin_Im.

[0023] Furthermore, in order to prevent calculation overflow, the input voltage feedforward value Vin_Feed is limited to a minimum value:

[0024]

[0025] Where, The minimum input voltage required for the system to operate.

[0026] Furthermore, the step of determining the maximum output voltage Vout_Max based on the output voltage reference given value Vout_Ref of the target digital power supply includes:

[0027]

[0028] Where p is a preset coefficient and satisfies p>1.

[0029] Furthermore, the calculation of the maximum duty cycle Duty_Max based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max includes:

[0030]

[0031] Wherein, the maximum duty cycle Vout_Max is proportional to the maximum output voltage Vout_Max, and inversely proportional to the input voltage feedforward value Vin_Feed.

[0032] Furthermore, limiting the output drive duty cycle Duty_set by the maximum duty cycle Duty_Max includes:

[0033]

[0034] Where Duty_Loop is the output value of the loop compensation network function. When Duty_Loop is greater than or equal to the maximum duty cycle Duty_Max, the driving duty cycle Duty_set is limited to the maximum duty cycle Duty_Max. Otherwise, the driving duty cycle Duty_set uses Duty_Loop.

[0035] A maximum duty cycle dynamic limiting system for a digital power supply, comprising:

[0036] An input voltage feedforward value calculation module is configured to determine an input voltage feedforward value Vin_Feed based on an input voltage filter value Vin_Filter and an input voltage instantaneous value Vin_Im of a target digital power supply;

[0037] an output voltage maximum value calculation module, configured to determine an output voltage maximum value Vout_Max based on an output voltage reference given value Vout_Ref of a target digital power supply;

[0038] The maximum duty cycle calculation module is configured to calculate the maximum duty cycle Duty_Max based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max, and limit the output drive duty cycle Duty_set by the maximum duty cycle Duty_Max.

[0039] The beneficial effects of the present invention are:

[0040] 1. The present invention limits the maximum output voltage by setting a given output voltage value, introduces an input voltage feedforward value, and dynamically calculates the maximum duty cycle, thereby achieving dynamic limitation of the duty cycle of the loop output.

[0041] 2. The present invention can effectively solve the problem of unnecessary overvoltage shutdown of the output voltage caused by untimely loop response when the input voltage changes rapidly, effectively avoid the risk of device damage due to untimely overvoltage protection, and effectively protect the safety of subsequent loads in special applications.

[0042] 3. When the output voltage given value of the present invention changes, the maximum output voltage thereof also changes accordingly, thereby limiting the calculated maximum duty cycle to a reasonable range, thereby ensuring stable and reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1This is a flow chart of a method for dynamically limiting the maximum duty cycle of a digital power supply according to embodiment 1 of the present invention.

[0044] Figure 2 This is a flow chart of a method for dynamically limiting the maximum duty cycle of a digital power supply according to embodiment 2 of the present invention. DETAILED DESCRIPTION

[0045] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] like Figure 1 As shown, this embodiment provides a method for dynamically limiting the maximum duty cycle of a digital power supply, including:

[0048] Determine an input voltage feedforward value Vin_Feed based on an input voltage filter value Vin_Filter and an input voltage instantaneous value Vin_Im of a target digital power supply;

[0049] Determine the maximum output voltage Vout_Max based on the output voltage reference given value Vout_Ref of the target digital power supply;

[0050] Based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max, the maximum duty cycle Duty_Max is calculated, and the output drive duty cycle Duty_set is limited by the maximum duty cycle Duty_Max.

[0051] It should be noted that the above method can be used to address unnecessary output voltage overvoltage shutdowns caused by untimely loop response when the input voltage changes rapidly. This effectively avoids the risk of device damage caused by untimely overvoltage protection and effectively protects downstream loads in special applications. Furthermore, when the output voltage setpoint changes, the maximum duty cycle can be adjusted in real time to keep it within a reasonable range, ensuring reliable operation.

[0052] In order to avoid the influence of noise and interference signals, this embodiment uses a digital filter to filter the input voltage Vin. Preferably, in order to facilitate engineering use and reduce computational complexity, the following method is used to complete the filtering process and obtain the input voltage filtered value Vin_Filter:

[0053]

[0054] Where K is the filter coefficient, K ≥ 1 and is an integer. The cutoff frequency of the filter can be adjusted by adjusting the K value. The specific value can be obtained based on experiments and actual application conditions.

[0055] Preferably, the calculation method of the instantaneous value of the input voltage Vin_Im includes:

[0056] Vin_Im=Vin

[0057] Where Vin_Im represents the instantaneous condition of the input voltage and can show the change of the input voltage in real time when the input voltage changes rapidly.

[0058] Preferably, determining the input voltage feedforward value Vin_Feed based on the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im of the target digital power supply includes:

[0059] Calculate the input voltage error value based on the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im ;

[0060] According to the input voltage error value and the maximum input voltage error , determine the input voltage feedforward value Vin_Feed.

[0061] More preferably, the input voltage error value is calculated based on the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im. ,include:

[0062]

[0063] Where, is a symbolic function, It is the difference between the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im. This value is an absolute value and is a quantitative representation of the rapid change of the input voltage.

[0064] More preferably, according to the input voltage error value and the maximum input voltage error , determine the input voltage feedforward value Vin_Feed, including:

[0065]

[0066] In the formula, when the input voltage error value The fluctuation range of the input voltage error is the maximum value If the input voltage is within the range of 0.001, it means that the input voltage does not change much. In order to avoid the influence of small fluctuations, the input voltage feedforward value Vin_Feed is assigned to the input voltage filter value Vin_Filter. When the input voltage error value is The fluctuation range exceeds the maximum input voltage error When , it means that the input voltage changes rapidly. At this time, the input voltage feedforward value Vin_Feed is assigned the input voltage instantaneous value Vin_Im. In addition, the maximum input voltage error The specific parameters are determined according to the actual input voltage range and test conditions.

[0067] More preferably, in order to prevent calculation overflow, a minimum limit is imposed on the input voltage feedforward value Vin_Feed:

[0068]

[0069] Where, The minimum input voltage required for the system to operate.

[0070] Preferably, determining the maximum output voltage Vout_Max based on the output voltage reference given value Vout_Ref of the target digital power supply includes:

[0071]

[0072] Where p is a preset coefficient, determined based on actual operating conditions, and satisfies p > 1. As can be seen from the above formula, once the coefficient p is determined, the maximum output voltage Vout_Max will change as Vout_Ref changes.

[0073] Preferably, the maximum duty cycle Duty_Max is calculated based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max, including:

[0074]

[0075] In the formula, the maximum duty cycle Vout_Max is directly proportional to the maximum output voltage Vout_Max and inversely proportional to the input voltage feedforward value Vin_Feed. The specific formula is determined by the specific circuit topology. For more complex topologies or nonlinear calculation formulas, data can be obtained through experiments, and then a polynomial fit can be used to obtain a fitting formula for calculating the maximum duty cycle.

[0076] Preferably, the output drive duty cycle Duty_set is limited by the maximum duty cycle Duty_Max, including:

[0077]

[0078] In the formula, Duty_Loop is the output value of the loop compensation network function. When Duty_Loop is greater than or equal to the maximum duty cycle Duty_Max, the driving duty cycle Duty_set is limited to the maximum duty cycle Duty_Max. Otherwise, the driving duty cycle Duty_set uses Duty_Loop. Specifically, when the loop compensation output value is greater than the maximum duty cycle, in order to prevent the integrator in the loop compensation function from entering deep saturation, the integrator in the loop compensation function needs to be processed and reassigned to the maximum duty cycle. .

[0079] In summary, the method of this embodiment limits the maximum output voltage by using a given output voltage value, and introduces an input voltage feedforward value to dynamically calculate the maximum duty cycle, thereby dynamically limiting the duty cycle of the loop output. This effectively addresses the issue of output voltage overvoltage shutdown caused by untimely loop response when the input voltage changes rapidly, and effectively avoids the risk of overvoltage damage to downstream loads. This method of this embodiment is widely applicable to power supply systems using digital control.

[0080] Example 2

[0081] This embodiment is based on embodiment 1:

[0082] This embodiment provides a method for dynamically limiting the maximum duty cycle of a digital power supply. Taking a digitally controlled buck power supply topology as an example, the power supply has an input voltage range of 16-40V, an output voltage of 12V, and a switching frequency of 100kHz. In actual use, the output voltage must not exceed 15V.

[0083] like Figure 2 As shown, the method of this embodiment can be implemented by taking the following steps:

[0084] 1. According to the specific requirements, the reference given value of the output voltage Vout_Ref is 12V. In order to ensure that the output does not exceed 15V, the coefficient p is set to 1.2. At this time, the maximum value of the output voltage can be obtained as follows:

[0085]

[0086] 2. The input is a low voltage wide range input. According to the actual application scenario, the maximum input voltage error The values ​​are:

[0087]

[0088] 3. Sample and calculate the input voltage Vin, and obtain the input voltage filter value Vin_Filter and the input voltage instantaneous value through the following formula :

[0089]

[0090] 4. According to the filtered value Vin_Filter of the input voltage and the instantaneous value of the input voltage , the calculated input voltage error value is expressed as follows:

[0091]

[0092] The input voltage feedforward value Vin_Feed is calculated according to the following formula:

[0093]

[0094] In order to prevent calculation overflow, the input voltage feedforward value is limited to a minimum value:

[0095]

[0096] 5. Based on the topological characteristics of the BUCK circuit, the maximum duty cycle is determined using the following formula:

[0097]

[0098] From the above formula, we can know that when the input voltage is 16V, the maximum duty cycle The value is 0.9, when the input voltage is 40V, the maximum duty cycle The maximum duty cycle has a large variation range and can play a better role in dynamic limiting.

[0099] 6. In this example, the loop compensation function uses classic PID control. The loop compensation function outputs Duty_Loop. The actual drive duty cycle is controlled as follows:

[0100]

[0101] As can be seen from the above, the driving duty cycle is carried out according to the maximum duty cycle dynamic limiting method, that is, when the loop output value is greater than the maximum duty cycle , the driving duty cycle is limited to the maximum duty cycle, otherwise the driving duty cycle uses the loop output value. In order to prevent the integrator in the loop compensation function from entering deep saturation, it is necessary to process the integrator in the loop compensation function and reassign the integrator in the loop compensation network function to the maximum duty cycle. .

[0102] Assume that when the input voltage is 20V and the power supply is operating stably, the circuit topology shows that the duty cycle is stable at 0.72. If the input voltage changes rapidly to 30V, in the worst case scenario, the loop output duty cycle will not have time to change. If the existing maximum duty cycle limit method is used at this time, the loop duty cycle will not be limited, causing the current output voltage to rise to 21.6V, far exceeding 15V. If the output overvoltage protection is not timely implemented, overvoltage damage will occur to the downstream load.

[0103] If the dynamic limiting method of this embodiment is introduced, when the input voltage is detected to be 30V, the maximum duty cycle at this time is If the value is 0.48, the output voltage will be limited to 14.4V and will not trigger overvoltage. Therefore, even if the loop response is not timely, the drive duty cycle will be limited to the maximum duty cycle. The value is limited and will not exceed 15V.

[0104] Example 3

[0105] This embodiment provides a system for dynamically limiting the maximum duty cycle of a digital power supply, including:

[0106] An input voltage feedforward value calculation module is configured to determine an input voltage feedforward value Vin_Feed based on an input voltage filter value Vin_Filter and an input voltage instantaneous value Vin_Im of a target digital power supply;

[0107] an output voltage maximum value calculation module, configured to determine an output voltage maximum value Vout_Max based on an output voltage reference given value Vout_Ref of a target digital power supply;

[0108] The maximum duty cycle calculation module is configured to calculate the maximum duty cycle Duty_Max based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max, and limit the output drive duty cycle Duty_set by the maximum duty cycle Duty_Max.

[0109] Example 4

[0110] This embodiment is based on embodiment 1:

[0111] This embodiment provides a computer device including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a method for dynamically limiting the maximum duty cycle of a digital power supply according to Embodiment 1. The computer program may be in source code form, object code form, an executable file, or some intermediate form.

[0112] Example 5

[0113] This embodiment is based on embodiment 1:

[0114] This embodiment provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a method for dynamically limiting the maximum duty cycle of a digital power supply according to embodiment 1. The computer program may be in source code form, object code form, an executable file, or some intermediate form. The storage medium includes: any entity or device capable of carrying computer program code, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electric carrier signal, a telecommunication signal, and a software distribution medium. It should be noted that the content contained in the storage medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the storage medium does not include electric carrier signals and telecommunication signals.

[0115] It should be noted that, for the sake of simplicity, the aforementioned method embodiments are described as a series of action combinations. However, those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily required by this application.

Claims

1. A method for dynamically limiting the maximum duty cycle of a digital power supply, characterized in that: include: Determine an input voltage feedforward value Vin_Feed based on an input voltage filter value Vin_Filter and an input voltage instantaneous value Vin_Im of a target digital power supply; Determine the maximum output voltage Vout_Max based on the output voltage reference given value Vout_Ref of the target digital power supply; Based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max, the maximum duty cycle Duty_Max is calculated, and the output drive duty cycle Duty_set is limited by the maximum duty cycle Duty_Max; The calculation method of the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im of the target digital power supply includes: Where K is the filter coefficient, K ≥ 1 and is an integer. By adjusting the K value, the cutoff frequency of the filter can be adjusted. Vin is the input voltage. The instantaneous value of the input voltage, Vin_Im, represents the instantaneous condition of the input voltage and can show the change of the input voltage in real time when the input voltage changes rapidly. The step of determining the input voltage feedforward value Vin_Feed based on the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im of the target digital power supply includes: calculating the input voltage error value according to the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im. ;According to the input voltage error value and the maximum input voltage error , determine the input voltage feedforward value Vin_Feed; According to the input voltage error value and the maximum input voltage error , determine the input voltage feedforward value Vin_Feed, including: In the formula, when the input voltage error value The fluctuation range is within the maximum input voltage error If the input voltage is within the range of 0.001, it means that the input voltage does not change much. At this time, the input voltage feedforward value Vin_Feed is assigned to the input voltage filter value Vin_Filter. When the input voltage error value is The fluctuation range exceeds the maximum input voltage error When , it indicates that the input voltage changes rapidly. At this time, the input voltage feedforward value Vin_Feed is assigned the input voltage instantaneous value Vin_Im.

2. The method for dynamically limiting the maximum duty cycle of a digital power supply according to claim 1, wherein: The input voltage error value is calculated based on the input voltage filter value Vin_Filter and the input voltage instantaneous value Vin_Im. ,include: Where, is the sign function, input voltage error value It is the difference between the input voltage filtered value Vin_Filter and the input voltage instantaneous value Vin_Im.

3. The method for dynamically limiting the maximum duty cycle of a digital power supply according to claim 1, wherein: In order to prevent calculation overflow, the input voltage feedforward value Vin_Feed is limited to a minimum value: Where, The minimum input voltage required for the system to operate.

4. The method for dynamically limiting the maximum duty cycle of a digital power supply according to claim 1, wherein: The step of determining the maximum output voltage Vout_Max based on the output voltage reference given value Vout_Ref of the target digital power supply includes: Where p is a preset coefficient and satisfies p>1.

5. The method for dynamically limiting the maximum duty cycle of a digital power supply according to claim 1, wherein: The calculation of the maximum duty cycle Duty_Max based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max includes: Wherein, the maximum duty cycle Vout_Max is proportional to the maximum output voltage Vout_Max, and inversely proportional to the input voltage feedforward value Vin_Feed.

6. The method for dynamically limiting the maximum duty cycle of a digital power supply according to claim 1, wherein: The method of limiting the output drive duty cycle Duty_set by the maximum duty cycle Duty_Max includes: Where Duty_Loop is the output value of the loop compensation network function. When Duty_Loop is greater than or equal to the maximum duty cycle Duty_Max, the driving duty cycle Duty_set is limited to the maximum duty cycle Duty_Max. Otherwise, the driving duty cycle Duty_set uses Duty_Loop.

7. A system for dynamically limiting the maximum duty cycle of a digital power supply, using the method for dynamically limiting the maximum duty cycle of a digital power supply as claimed in claim 1, characterized in that: include: An input voltage feedforward value calculation module is configured to determine an input voltage feedforward value Vin_Feed based on an input voltage filter value Vin_Filter and an input voltage instantaneous value Vin_Im of a target digital power supply; an output voltage maximum value calculation module, configured to determine an output voltage maximum value Vout_Max based on an output voltage reference given value Vout_Ref of a target digital power supply; The maximum duty cycle calculation module is configured to calculate the maximum duty cycle Duty_Max based on the input voltage feedforward value Vin_Feed and the output voltage maximum value Vout_Max, and limit the output drive duty cycle Duty_set by the maximum duty cycle Duty_Max.

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