Judgment method and device for adjusting fitting current of upper tube

Abstract

The invention relates to a judgment method and device for adjusting the fitting current of an upper tube, and the method comprises the steps: obtaining PWM information for controlling the connection and disconnection of the upper tube and a lower tube in a previous period, and calculating the half value of the connection time of the upper tube and the half value of the connection time of the lower tube; in the current period, when the upper tube reaches half conduction time, sampling the upper tube fitting current; sampling the real-time current of the lower tube when the lower tube reaches half conduction time; comparing the upper tube current sampling signal with the lower tube current sampling signal, and obtaining an adjustment strategy including the upper tube fitting current simulation slope of the next period according to a comparison result; and according to the adjustment strategy, generating an adjusted upper tube fitting current. According to the invention, potential faults caused by switching noise can be avoided, the current detection precision of the system is ensured, and the stability of the system is improved.

Description

Technical Field

[0001] This invention belongs to the field of buck converter circuit technology, specifically relating to a method and apparatus for determining the magnitude of the fitting current of the upper transistor. Background Technology

[0002] Current sensing technology is a crucial component of modern buck converter design. Directly sensing the MOSFET current is a common practice to reduce component count and achieve more accurate designs. However, with increasing switching frequencies, the on-time of the upper MOSFET becomes extremely short, thus amplifying the impact of switching noise. Because the excessively short on-time leads to sensing distortion, the current information from the upper MOSFET becomes unreliable, increasing the risk of control loop failure.

[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a method and apparatus for determining the magnitude of the fitting current of the upper tube.

[0005] The technical solutions adopted in the embodiments of the present invention are as follows: A method for determining the magnitude of the fitting current of the upper transistor, comprising the following steps: S1. Obtain the PWM information controlling the on and off states of the upper and lower transistors in the previous cycle, and calculate the on-time of the upper transistor based on the PWM information. and the conduction time of the lower tube Half of the value, i.e. and ; S2. During the current cycle, when the upper tube is on for a duration of [duration missing], [details missing]. At that time, the fitted current of the upper tube is sampled to obtain the upper tube current sampling signal. The current pipe conduction time is as long as At that time, the real-time current of the lower diode is sampled to obtain the lower diode current sampling signal. ; S3, Sample the upper tube current signal With the sampling signal of the lower tube current The comparison is performed, and based on the comparison results, an adjustment strategy is derived, including the adjustment of the slope of the upper tube fitting current simulation for the next cycle. like > This reduces the slope of the upper tube fitting current simulation in the next cycle; like This increases the slope of the upper tube fitting current simulation in the next cycle; like = If the current fitting current slope of the upper tube in the current cycle is used as the current simulation slope of the upper tube in the next cycle; S4. Generate the upper tube fitting current based on the simulated slope of the upper tube fitting current determined in step S3.

[0006] A further technical solution is that, in step S3, the upper tube current sampling signal is acquired. With the sampling signal of the lower tube current The results of multiple samplings are used, and the optimized simulated slope of the upper tube fitting current is calculated and output based on the corresponding comparison results.

[0007] A further technical solution is that, in step S3, the slope of the upper tube fitting current simulation is adjusted according to the following formula: in, Indicates the current position (number). The slope of the fitted current of the upper tube during the period; Indicates resolution; Indicates the first The slope of the fitted current of the upper tube within +1 cycle.

[0008] A discrimination device for adjusting the magnitude of the fitting current of the upper tube, comprising: The conduction time calculation circuit is used to obtain the PWM information controlling the on and off of the upper and lower transistors in the previous cycle, and to calculate the conduction time of the upper transistor based on the PWM information. and the conduction time of the lower tube Half of the value, i.e. and ; A sample-and-hold circuit is used to hold the signal for a specified duration during the current cycle when the upper transistor is on. At that time, the fitted current of the upper tube is sampled to obtain the upper tube current sampling signal. The current pipe conduction time is as long as At that time, the real-time current of the lower diode is sampled to obtain the lower diode current sampling signal. ; Comparison and tracking circuitry is used to sample the current signal of the upper transistor. With the sampling signal of the lower tube current The comparison is made, and based on the comparison results, an adjustment strategy is obtained, including the slope of the upper tube fitting current simulation for the next cycle. A waveform generator is used to generate an upper tube fitting current based on the simulated slope of the upper tube fitting current determined by the comparison and tracking circuit.

[0009] A further technical solution is that, in the comparison and tracking circuit, the upper transistor current sampling signal is... With the sampling signal of the lower tube current The multiple sampling results are compared, and the optimized upper tube fitting current simulation slope is calculated and output based on the corresponding comparison results.

[0010] The beneficial effects of the embodiments of the present invention are as follows: This invention proposes a method for determining the magnitude of the fitting current of the upper transistor. The calibration signal is sampled at half the conduction time of the upper transistor. With the help of circuit calculation, the sampled signal can be compared with the current signal at half the conduction time of the lower transistor. This can avoid potential faults caused by switching noise. The current detection circuit can ensure both accuracy and good stability. Attached Figure Description

[0011] Figure 1 This is a flowchart of a method for determining the magnitude of the fitting current of the upper tube according to Embodiment 1 of the present invention.

[0012] Figure 2 This is a schematic diagram of a waveform sampled using the method of Embodiment 1 of the present invention.

[0013] Figure 3 This is a schematic diagram of the structure of a discrimination device for adjusting the magnitude of the fitting current of the upper tube according to Embodiment 2 of the present invention. Detailed Implementation

[0014] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the device proposed by this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, only for the purpose of conveniently and clearly illustrating the embodiments of this invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0016] Example 1 Figure 1 This is a flowchart of a method for determining the magnitude of the fitting current of the upper tube according to Embodiment 1 of the present invention. Figure 2This is a schematic diagram illustrating the waveform sampling method used in Embodiment 1 of the present invention. Figure 1 , Figure 2 As shown, the method for determining the magnitude of the fitting current of the upper tube in this embodiment includes the following steps: Step 1: Calculate the half-cycle time of the upper and lower transistors based on the pulse width modulation (PWM) information of the previous cycle. Step 2: At half the conduction time of the upper tube, sample the simulated signal of the upper tube, i.e., the fitted current of the upper tube. Step 3: Compare the sampled signal with the low-side current signal at half the conduction time of the lower transistor: 1) If the sampled signal is greater than the current signal of the lower transistor, then reduce the analog slope of the next cycle; 2) If the sampled signal is less than the current signal of the lower tube, then increase the analog slope of the next cycle.

[0017] Step 4: Repeat steps 1 to 3 to obtain the optimized slope.

[0018] In the method for determining the magnitude of the fitting current of the upper tube proposed in this embodiment, one cycle is defined as the interval between two openings of the upper tube. Generally, the system will experience one upper tube switch and one lower tube switch within one cycle.

[0019] Furthermore, in Step 3 of this embodiment, the slope of the next cycle can be determined, and the simulated slope of the upper tube fitting current can be adjusted according to the following formula: in, Indicates the current position (number). The slope of the fitted current of the upper tube during the period; Indicates resolution; Indicates the first The slope of the upper tube fitted current simulation within +1 cycle. The resolution essentially determines the dynamic range and minimum controllable step size of the slope.

[0020] In the actual calculation process of Step 3, two set values ​​are involved: the initial slope. and resolution The simulated slope of the first cycle. Based on the initial slope and resolution The calculation yielded: In subsequent cycles, the sampling information of the fitted current of the upper tube is compared with the current information when the lower tube is turned on to determine whether to increase or decrease the simulation slope of the next cycle. That is, the simulation slope of the current cycle plus or minus the resolution is used to obtain the simulation slope of the next cycle.

[0021] In steps 3 and 4, after each comparison and judgment, only a small amount of the simulated slope is adjusted. The number of repetitions depends on the resolution, such as approximately 100 cycles, to find the optimal simulated slope. After several switching cycles in step 4, the correct current rise slope can be found, and an accurate fitted current waveform of the upper transistor can be obtained. Finally, the target value + or- It jumps on the slope.

[0022] Furthermore, the fitted current of the upper tube and the actual current of the lower tube obtained in this embodiment are added together to obtain a complete current waveform of one cycle. This current waveform is provided to components in the system that require current information, such as the current information required by the controller, for loop control.

[0023] This invention samples the fitted current signal of the upper transistor used for discrimination at half the conduction time of the upper transistor. Using circuit calculations, the sampled current signal of the upper transistor is compared with the sampled current signal of the lower transistor at half the conduction time. This method avoids the region of maximum switching noise during sampling and comparison, resulting in more accurate current detection results and resolving control loop errors caused by distorted current detection results. This invention employs a sampling and comparison method in the middle of the switching time, overcoming the problem of inconsistent current detection methods due to differences in the duration of switching noise across different systems. It allows different systems to use the section with the least noise impact for current detection correction. Therefore, by adopting this invention, potential faults caused by switching noise can be avoided, and the current detection circuit can guarantee both accuracy and good stability.

[0024] Example 2 Figure 3 This is a schematic diagram of a discrimination device for adjusting the magnitude of the fitting current of the upper tube according to Embodiment 2 of the present invention. Figure 3 As shown, the discrimination device for adjusting the fitting current of the upper tube in this embodiment executes the discrimination method in Embodiment 1. The device specifically includes: The conduction time calculation circuit is used to obtain the PWM information controlling the on and off of the upper and lower transistors in the previous cycle, and to calculate the conduction time of the upper transistor based on the PWM information. and the conduction time of the lower tube Half of the value, i.e. and ; A sample-and-hold circuit is used to hold the signal for a specified duration during the current cycle when the upper transistor is on. At that time, the fitted current of the upper tube is sampled to obtain the upper tube current sampling signal. The current pipe conduction time is as long as At that time, the real-time current of the lower diode is sampled to obtain the lower diode current sampling signal. .

[0025] Comparison and tracking circuitry is used to sample the current signal of the upper transistor. With the sampling signal of the lower tube current By comparing the results, a strategy is derived to adjust the slope of the upper tube fitting current simulation in the next cycle. A waveform generator is used to generate an upper tube fitting current based on the simulated slope of the upper tube fitting current determined by the comparison and tracking circuit.

[0026] A further technical solution is that, in the comparison and tracking circuit, the upper transistor current sampling signal is... With the sampling signal of the lower tube current The multiple sampling results are compared, and the optimized upper tube fitting current simulation slope is calculated and output based on the corresponding comparison results.

[0027] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0028] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for determining the magnitude of the on-pipe fit current, comprising: determining the magnitude of the on-pipe fit current. comprising the steps of: S1, acquiring PWM information of controlling the upper tube and the lower tube to turn on and turn off in the last period, calculating the turn-on time of the upper tube according to the PWM information and the turn-on time of the lower tube half value, that is and ; S2, in the current cycle, when the upper tube is turned on for , the upper tube current is sampled to obtain an upper tube current sampling signal ; when the lower tube is turned on for , the lower tube real-time current is sampled to obtain a lower tube current sampling signal ; S3, compare the upper tube current sampling signal with the lower tube current sampling signal and obtain an adjustment strategy including a next period upper tube fitted current analog slope according to a comparison result: If < / then decrease the upper bar fit current analog slope for the next cycle; If then increase the upper tube fitting current analog slope for the next cycle; If = 0, then use the current period's upper gate fit current analog slope as the next period's upper gate current analog slope. = 0, then use the current period's upper gate fit current analog slope as the next period's upper gate current analog slope. S4. generating the upper tube fitting current based on the upper tube fitting current analog slope determined in step S3.

2. The method of claim 1, wherein the step of determining the magnitude of the fitting current is performed by: determining a magnitude of the fitting current based on the magnitude of the fitting voltage and the magnitude of the fitting current. In the step S3, the multiple sampling results of the upper tube current sampling signal and the lower tube current sampling signal are obtained, and according to the corresponding comparison results, the optimized upper tube fitting current simulation slope is calculated and output.

3. The method of claim 1, wherein the step of determining the magnitude of the fitting current is performed by: determining a magnitude of a current flowing through the upper tube; and comparing the magnitude of the current flowing through the upper tube to a predetermined threshold value. In step S3, the upper tube fitting current analog slope is adjusted according to the following equation: wherein, represents the current period in which the fitting is performed; represents the fitting current simulation slope of the upper tube in the current period; represents the resolution; represents the fitting current simulation slope of the upper tube in the previous period; represents the fitting current simulation slope of the upper tube in the +1 period.

4. A discrimination device for regulating the magnitude of the on-pipe fit current, characterized in that comprising: The conduction time calculation circuit is used for acquiring PWM information of controlling the conduction and turn-off of the upper tube and the lower tube in the last period, and calculating the conduction time of the upper tube according to the PWM information and the conduction time of the lower tube , i.e. and ; A sample-and-hold circuit is used to hold the signal for a specified duration during the current cycle when the upper transistor is on. At that time, the fitted current of the upper tube is sampled to obtain the upper tube current sampling signal. The current pipe conduction time is as long as At that time, the real-time current of the lower diode is sampled to obtain the lower diode current sampling signal. ; a comparison and tracking circuit for comparing the upper transistor current sample signal with the lower transistor current sample signal and generating an adjustment strategy including a next period upper transistor fitted current analog slope based on a result of the comparison; a waveform generator for generating the upper tube fitting current based on the upper tube fitting current analog slope determined by the comparison and tracking circuit.

5. The device for discriminating the magnitude of the adjustment up-pipe fitting current according to claim 1, wherein The comparison and tracking circuit compares the multiple sampling results of the upper tube current sampling signal and the lower tube current sampling signal and calculates the optimized upper tube fitting current simulation slope according to the corresponding comparison results and outputs.

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