CN107437943B - Analog-to-digital converter sampling system and analog-to-digital converter sampling method - Google Patents
Analog-to-digital converter sampling system and analog-to-digital converter sampling method Download PDFInfo
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- CN107437943B CN107437943B CN201610370824.7A CN201610370824A CN107437943B CN 107437943 B CN107437943 B CN 107437943B CN 201610370824 A CN201610370824 A CN 201610370824A CN 107437943 B CN107437943 B CN 107437943B
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- 238000005070 sampling Methods 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims description 12
- 238000006243 chemical reaction Methods 0.000 claims abstract description 9
- 230000000630 rising effect Effects 0.000 claims description 6
- 230000001960 triggered effect Effects 0.000 claims description 6
- 238000010586 diagram Methods 0.000 description 3
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/12—Analogue/digital converters
- H03M1/124—Sampling or signal conditioning arrangements specially adapted for A/D converters
- H03M1/1245—Details of sampling arrangements or methods
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K7/00—Modulating pulses with a continuously-variable modulating signal
- H03K7/08—Duration or width modulation ; Duty cycle modulation
Abstract
An analog-to-digital converter sampling system comprising: a switching tube; an analog-to-digital converter; the microprocessor comprises a first PWM module and a second PWM module, the first PWM module is connected with the switch tube, the first PWM module is used for generating a first PWM signal to drive the switch tube, the second PWM module is connected with the analog-to-digital converter, and the second PWM module is used for generating a second PWM signal which has a phase difference with the first PWM signal to trigger the analog-to-digital converter to perform analog-to-digital conversion, so that the sampling time of the analog-to-digital converter corresponds to a certain fixed point in the period of the first PWM signal, and fixed-point sampling of the analog-to-digital converter is realized.
Description
Technical Field
The invention relates to an analog-to-digital converter sampling system and an analog-to-digital converter sampling method.
Background
In the application field of Digital DC/DC converters, an ADC (Analog Digital converter) is a necessary module of each system, at present, most of MCU of an embedded system is embedded with high-speed ADC peripherals, and the high-speed ADC peripherals are matched with a high-speed and high-resolution PWM module of the MCU, so that a Digital power supply is rapidly developed in the fields of communication and industrial control. However, these high-speed ADC peripherals are affected by the high-speed switch of the PWM (Pulse Width Modulation) module, so that the ADC sampling values will largely jitter, and the jitter of these sampling values will cause instability of the whole digital feedback loop, which increases the output ripple of the whole ADC, and degrades the system stability.
Disclosure of Invention
In view of the above, it is desirable to provide an analog-to-digital converter sampling system and an analog-to-digital converter sampling method for performing fixed-point sampling on an analog-to-digital converter.
The invention provides an analog-to-digital converter sampling system, comprising:
a switching tube;
an analog-to-digital converter;
the microprocessor comprises a first PWM module and a second PWM module, the first PWM module is connected with the switching tube, the first PWM module is used for generating a first PWM signal to drive the switching tube, the second PWM module is connected with the analog-to-digital converter, and the second PWM module is used for generating a second PWM signal which has a phase difference with the first PWM signal to trigger the analog-to-digital converter to perform analog-to-digital conversion, so that the sampling time of the analog-to-digital converter corresponds to a certain fixed point in the period of the first PWM signal.
Preferably, the second PWM signal has the same period and the same duty ratio as the first PWM signal.
Preferably, the second PWM signal is an integer multiple of a period of the first PWM signal or the period of the first PWM signal is an integer multiple of a period of the second PWM signal.
Preferably, the phase difference is 90 degrees.
Preferably, the analog-to-digital converter is built in the microprocessor or externally arranged on the microprocessor.
Preferably, the analog-to-digital converter is triggered to sample at the rising edge of the second PWM signal.
The invention provides a sampling method of an analog-digital converter, which comprises the following steps:
generating a first PWM signal to drive a switching tube; and
and generating a second PWM signal with a phase difference with the first PWM signal to trigger the analog-to-digital converter to perform analog-to-digital conversion, so that the sampling moment of the analog-to-digital converter corresponds to a certain fixed point in the period of the first PWM signal.
Preferably, the second PWM signal has the same period and the same duty ratio as the first PWM signal.
Preferably, the second PWM signal is an integer multiple of a period of the first PWM signal or the period of the first PWM signal is an integer multiple of a period of the second PWM signal.
Preferably, the phase difference is 90 degrees.
According to the invention, the phase difference exists between the second PWM signal triggering the analog-to-digital converter to perform analog-to-digital conversion and the first PWM signal driving the switching tube, so that the sampling time of the analog-to-digital converter corresponds to a certain fixed point in the period of the first PWM signal, and the fixed-point sampling of the analog-to-digital converter is realized.
Drawings
Fig. 1 is a schematic block diagram of an analog-to-digital converter sampling system according to an embodiment of the present invention.
Fig. 2 is a timing diagram of a first PWM signal and a second PWM signal according to an embodiment of the invention.
Fig. 3 is a flowchart of a sampling method of an analog-to-digital converter according to an embodiment of the invention.
Description of the main elements
| Analog-to-digital converter sampling system | 1 |
| |
10 |
| First PWM |
11 |
| Second PWM |
12 |
| Switch tube | 20 |
| Analog-to-digital converter | 30 |
The following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
The technical solution and other advantages of the present invention will become apparent from the following detailed description of specific embodiments of the present invention, which is to be read in connection with the accompanying drawings. It is to be understood that the drawings are provided solely for the purposes of reference and illustration and are not intended as a definition of the limits of the invention. The dimensions shown in the figures are for clarity of description only and are not to be taken in a limiting sense.
Referring to fig. 1, a schematic block diagram of an analog-to-digital converter sampling system 1 according to an embodiment of the present invention is shown. The analog-to-digital converter sampling system 1 comprises a microprocessor 10, a switching tube 20 and an analog-to-digital converter 30. The microprocessor 10 includes at least a first PWM (Pulse Width Modulation) module 11 and a second PWM (Pulse Width Modulation) module 12. In this embodiment, the number of the first PWM modules 11 is one. The first PWM module 11 is connected to the switching tube 20. The first PWM module 11 is configured to generate a first PWM signal to drive the switching tube 20, so as to control a time ratio of the switching tube 20 to be turned on and off, and maintain a stable output voltage.
The second PWM module 12 is connected to the analog-to-digital converter 30. The second PWM module 12 is configured to generate a second PWM signal to trigger the analog-to-digital converter 30 to perform analog-to-digital conversion, where the second PWM signal is out of phase with the first PWM signal, so that a sampling time of the analog-to-digital converter 30 corresponds to a fixed point in a period of the first PWM signal.
In this embodiment, the analog-to-digital converter 30 is an independent ADC conversion chip, and in other embodiments, the analog-to-digital converter 30 may be an ADC module built in the microprocessor 10. In this embodiment, the analog-to-digital converter 30 is triggered to sample at the rising edge of the second PWM signal. In other embodiments, the analog-to-digital converter 30 is triggered to sample at the falling edge of the second PWM signal or at both the rising edge of the second PWM signal and the falling edge of the second PWM signal.
In this embodiment, the second PWM signal has the same period and the same duty ratio as the first PWM signal (see fig. 2). In the present embodiment, the phase difference is 90 degrees. In this way, the sampling time of the analog-to-digital converter 30 always corresponds to the middle time in the first PWM signal period. For example, when the analog-to-digital converter 30 samples the current flowing through the inductor in the DC/DC converter, it can be ensured that the sampling point occurs at the center point of the PWM signal driving the switching tube 20, and the sampling at the highest point and the sampling at the lowest point are prevented from occurring, thereby ensuring the stability of the whole system. In other embodiments, the phase difference may be changed to other values, such as 15 degrees, 20 degrees, 45 degrees, etc., according to design requirements. In other embodiments, the second PWM signal has a different period from the first PWM signal, and the second PWM signal is an integer multiple of the period of the first PWM signal or the period of the first PWM signal is an integer multiple of the period of the second PWM signal.
Fig. 3 is a flowchart illustrating a sampling method of an analog-to-digital converter according to an embodiment of the invention.
In step S301, the first PWM module 11 generates a first PWM signal to drive the switching tube 20.
In step S302, the second PWM module 12 generates a second PWM signal to trigger the analog-to-digital converter 30 to perform analog-to-digital conversion, where the second PWM signal has a phase difference with the first PWM signal, so that a sampling time of the analog-to-digital converter 30 corresponds to a fixed point in a period of the first PWM signal.
In the present embodiment, the analog-to-digital converter 30 is triggered to sample at the rising edge of the second PWM signal. In other embodiments, the analog-to-digital converter 30 is triggered to sample at the falling edge of the second PWM signal or at both the rising edge of the second PWM signal and the falling edge of the second PWM signal. In this embodiment, the second PWM signal has the same period and the same duty ratio as the first PWM signal. In the present embodiment, the phase difference is 90 degrees. In other embodiments, the phase difference is 15 degrees, 20 degrees, 45 degrees, etc. In other embodiments, the second PWM signal has a different period from the first PWM signal, and the second PWM signal is an integer multiple of the period of the first PWM signal or the period of the first PWM signal is an integer multiple of the period of the second PWM signal.
Thus, the present invention makes the sampling point of the analog-to-digital converter 30 a fixed point relative to the signal driving the switch tube 20, and by this method, the ADC fixed point sampling according to the present invention is realized. The fixed-point sampling of the ADC is particularly important for a control algorithm based on a current loop, when the current flowing through an inductor is sampled, a sampling point can be ensured to be at a fixed point of a PWM signal, the situation that the sampling is at the highest point sometimes and at the lowest point sometimes is prevented, and the stability of the whole system is ensured.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. An analog-to-digital converter sampling system comprising:
a switching tube;
an analog-to-digital converter;
the microprocessor comprises a first PWM module and a second PWM module, the first PWM module is connected with the switching tube, the first PWM module is used for generating a first PWM signal to drive the switching tube, the second PWM module is connected with the analog-to-digital converter, and the second PWM module is used for generating a second PWM signal which has a phase difference with the first PWM signal to trigger the analog-to-digital converter to perform analog-to-digital conversion, so that the sampling time of the analog-to-digital converter corresponds to a certain fixed point in the period of the first PWM signal.
2. The analog-to-digital converter sampling system of claim 1, wherein:
the second PWM signal has the same period and the same duty ratio as the first PWM signal.
3. The analog-to-digital converter sampling system of claim 1, wherein:
the second PWM signal is an integer multiple of a period of the first PWM signal or the period of the first PWM signal is an integer multiple of a period of the second PWM signal.
4. The analog-to-digital converter sampling system of claim 1, wherein:
the phase difference is 90 degrees.
5. The analog-to-digital converter sampling system of claim 1, wherein:
the analog-to-digital converter is arranged in the microprocessor or is externally arranged on the microprocessor.
6. The analog-to-digital converter sampling system of claim 1, wherein:
the analog-to-digital converter is triggered to sample at the rising edge of the second PWM signal.
7. An analog-to-digital converter sampling method comprising:
generating a first PWM signal to drive a switching tube; and
and generating a second PWM signal with a phase difference with the first PWM signal to trigger the analog-to-digital converter to perform analog-to-digital conversion, so that the sampling moment of the analog-to-digital converter corresponds to a certain fixed point in the period of the first PWM signal.
8. The method for sampling an analog-to-digital converter of claim 7, wherein:
the second PWM signal has the same period and the same duty ratio as the first PWM signal.
9. The method for sampling an analog-to-digital converter of claim 7, wherein:
the second PWM signal is an integer multiple of a period of the first PWM signal or the period of the first PWM signal is an integer multiple of a period of the second PWM signal.
10. The method for sampling an analog-to-digital converter of claim 7, wherein:
the phase difference is 90 degrees.
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| CN101889396A (en) * | 2007-10-22 | 2010-11-17 | 大动力公司 | Self tracking ADC for digital power supply control systems |
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