Method and device for extending controller PWM resolution

Abstract

A method and a device for extending controller pulse width modulation (PWM) resolution in the PWM control field are disclosed. The method includes: reading the actual value of a current analog quantity; acquiring the value of a preset analog quantity; comparing the actual value of the current analog quantity with the value of the preset analog quantity; and adjusting the extended PWM duty ratio of the software along the direction of increasing the analog quantity if the actual value of the current analog quantity is smaller than the value of the preset analog quantity; otherwise adjusting the extended PWM duty ratio of the software along the direction of decreasing the analog quantity if the actual value of the current analog quantity is larger than the value of the preset analog quantity. With such solution, it can effectively extend PWM resolution on the basis of not decreasing PWM frequency so as to satisfy the requirements of a precise control application field; and the system power consumption and cost can be decreased effectively due to not using a high main-frequency controller.

Description

technical field [0001] The invention belongs to the field of PWM control, in particular to a method and a system for a controller to expand PWM frequency and resolution. Background technique [0002] Pulse Width Modulation (Pulse Width Modulation, PWM) is a very effective technology that uses the digital output of a microprocessor to control analog circuits, and is widely used in many fields from measurement, communication to power control and conversion. [0003] PWM can greatly reduce system cost and power consumption by digitally controlling analog circuits. Additionally, many microcontrollers and DSPs already include PWM controllers on-chip. [0004] Based on the PWM control system of the single-chip microcomputer, because the main frequency of the CPU is low, it is usually lower than 20M. Take a single-chip microcomputer with a main frequency of 8M and 16M as an example. For the relationship between PWM resolution and frequency, please refer to figure 1 : [0005] ex...

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Problems solved by technology

[0005] exist figure 1 It can be seen from the figure that when the PWM resolution is 12Bit in a single-chip microcomputer control system based on 16M high main frequency, the PWM frequency is only 3.9K, which cannot meet the requirements at all in AC / DC or DC / DC conversion. When PWM Only when the resolution is 6Bit or 7Bit can the frequency requirements in the DC / DC conversion system be met

But at this time, due to the low PWM resolution, no matter what kind of digital filtering technology is used, and no matter how high the ADC resolution of the microcontroller is, the digital ripple of the PWM control system is quite obvious (see figure 2 )

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