阅读说明：本技术 一种采样与取电复用电路 (Sampling and power-taking multiplexing circuit ) 是由 吴志祥 彭颖 许清泉 黄文生 史建平 蔡纪鹤 鞠金涛 许泽刚 朱益利 方晓毅 于 2019-11-05 设计创作，主要内容包括：本发明公开的一种采样与取电复用电路,包括一个主要的限流电阻器,限流电阻器一端连接于直流母线电压或交流电整流之后的脉动直流电压端,另一端连接于MCU电路的A/D输出端,连接于取样电阻器的一端,还连接于一个导向二极管阳极。取样电阻器的另一端连接于MCU电路的一个I/O端口。导向二极管的阴极与MCU电路的电源端连接,与电容器的一端连接,与限幅稳压管的阴极连接。滤波电容器的另一端接地,限幅稳压管的阳极接地。本发明将采样电路与MCU电路所需的电源电路合二为一,充分简化电路结构,降低生产成本,特别适合线路板面积极小、最求产品成本低廉和低功耗等场合。(The invention discloses a sampling and power-taking multiplexing circuit which comprises a main current-limiting resistor, wherein one end of the current-limiting resistor is connected to a pulsating direct-current voltage end after direct-current bus voltage or alternating current rectification, and the other end of the current-limiting resistor is connected to an A/D output end of an MCU circuit, is connected to one end of a sampling resistor and is also connected to the anode of a guide diode. The other end of the sampling resistor is connected to one I/O port of the MCU circuit. The cathode of the guide diode is connected with the power supply end of the MCU circuit, connected with one end of the capacitor and connected with the cathode of the amplitude limiting voltage-stabilizing tube. The other end of the filter capacitor is grounded, and the anode of the amplitude limiting voltage regulator tube is grounded. The invention combines the power supply circuit required by the sampling circuit and the MCU circuit into a whole, fully simplifies the circuit structure, reduces the production cost, and is particularly suitable for occasions with extremely small circuit board area, low product cost, low power consumption and the like.)

1. A sampling and electricity-taking multiplexing circuit comprises a main current-limiting resistor, wherein one end of the current-limiting resistor is connected with a direct-current bus voltage or a pulsating direct-current voltage end after alternating current rectification, and the other end of the current-limiting resistor is connected with an A/D output end of an MCU circuit, connected with one end of a sampling resistor and connected with the anode of a guide diode; the other end of the sampling resistor is connected with an I/O port of the MCU circuit; the cathode of the guide diode is connected with the power supply end of the MCU circuit, connected with one end of the filter capacitor and connected with the cathode of the amplitude limiting voltage-stabilizing tube; the other end of the filter capacitor is grounded, and the anode of the amplitude limiting voltage regulator tube is grounded;

at the moment of power-on, each port of the MCU circuit is in a high-impedance state due to no working voltage, the direct current bus voltage or pulsating direct current voltage VP after alternating current rectification is limited by a current limiting resistor and is guided by a diode to charge a capacitor until the working voltage required by the MCU circuit is established, and the MCU is reset and started to work; then, the I/O port of the MCU circuit is converted into an output low level, one end of the sampling resistor is equivalent to the ground, the voltage value SA at the two ends of the sampling resistor is in direct proportion to the voltage value of the VP, and the MCU circuit converts the voltage value SA into a digital value through the A/D port for further processing of an internal program; and after the processing is finished, the I/O port of the MCU circuit is converted into a high-resistance state, the VP is guided by the diode through the current-limiting resistor to continuously charge the capacitor, and the steps are repeated to realize the multiplexing function of sampling and power taking by one resistor.

2. The sampling and power taking multiplexing circuit of claim 1, wherein: one end of a current limiting resistor is connected with the direct current bus voltage or the pulsating direct current voltage VP after alternating current rectification, and the other end of the current limiting resistor is connected with the A/D output end of the MCU circuit, one end of the sampling resistor and the anode of a guide diode.

3. The sampling and power taking multiplexing circuit of claim 1, wherein: the other end of the sampling resistor is connected with an I/O port of the MCU circuit; the voltage signal at the two terminals of the sampling resistor represents the magnitude of VP.

4. The sampling and power taking multiplexing circuit of claim 1, wherein: the cathode of the guide diode is connected with the power supply end of the MCU circuit, connected with one end of the capacitor and connected with the cathode of the amplitude limiting voltage-stabilizing tube; the other end of the capacitor is grounded with the anode of the amplitude limiting voltage-stabilizing tube; the capacitor stores additional voltage to provide working power supply for the MCU circuit, and the amplitude limiting voltage regulator tube connected in parallel with the capacitor limits the charging voltage value of the capacitor to a certain voltage amplitude.

5. The sampling and power taking multiplexing circuit of claim 1, wherein: the power end of the MCU circuit is connected with the cathode of the guide diode, and the negative end of the MCU circuit is grounded; the MCU circuit comprises main elements and necessary peripheral elements, wherein the main elements are a singlechip, or a system on a chip, or a CPLD, or an FPGA, or an ARM and a DSP.

Technical Field

The invention relates to the technical field of power supply technology and measurement and control, in particular to a sampling and power taking multiplexing circuit.

Background

In the increasingly miniaturized process of electronic products, how to simplify the circuit structure is an important problem; in a portable measurement and control instrument, how to reduce the power consumption of the whole circuit is directly related to the service life of a battery; the method is characterized in that a preset function design is completed in a limited circuit board area, the problem of reducing the number of elements must be considered, the number of the elements is reduced, a circuit structure is optimized, and not only is the product cost reduced, but also necessary measures for improving the overall reliability of the product are taken.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the defects that an independent power supply circuit and an independent sampling circuit coexist, the number of elements is large, the circuit structure is complex and the like in the conventional measurement and control scheme are overcome, and the composite function of sampling and electricity-taking multiplexing is realized by using as few components as possible.

In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows: the invention discloses a sampling and power-taking multiplexing circuit which comprises a main current-limiting resistor, wherein one end of the current-limiting resistor is connected to a pulsating direct-current voltage end after direct-current bus voltage or alternating current rectification, and the other end of the current-limiting resistor is connected to an A/D output end of an MCU circuit, is connected to one end of a sampling resistor and is also connected to the anode of a guide diode. The other end of the sampling resistor is connected to one I/O port of the MCU circuit. The cathode of the guide diode is connected with the power supply end of the MCU circuit, connected with one end of the capacitor and connected with the cathode of the amplitude limiting voltage-stabilizing tube. The other end of the filter capacitor is grounded, and the anode of the amplitude limiting voltage regulator tube is grounded.

In the invention, at the moment of electrifying, each port of the MCU circuit is in a high-impedance state because of no working voltage, the direct current bus voltage or pulsating direct current voltage VP after alternating current rectification is limited by a current limiting resistor and is guided by a diode to charge a capacitor until the working voltage required by the MCU circuit is established, and the MCU resets and starts working. And then, the I/O port of the MCU circuit is converted into an output low level, one end of the sampling resistor is equivalent to the ground, the voltage value SA at the two ends of the sampling resistor is in direct proportion to the voltage value VP, and the MCU circuit converts the voltage value SA into a digital value through the A/D port for processing by an internal program. After the conversion is finished, the I/O port of the MCU circuit is converted into a high-resistance state (no current is input, which is equivalent to a disconnection state), and the VP is guided by the diode through the current-limiting resistor to continuously charge the capacitor, so that the steps are repeated, and the multiplexing function of sampling and power taking by one resistor is realized.

Furthermore, one end of a current limiting resistor is connected with the direct current bus voltage or the pulsating direct current voltage VP after alternating current rectification, and the other end is connected with the A/D output end of the MCU circuit, one end of the sampling resistor and the anode of a guide diode.

Furthermore, the other end of the sampling resistor is connected to an I/O port of the MCU circuit; the voltage signal at the two terminals of the sampling resistor represents the magnitude of VP.

Furthermore, the cathode of the guide diode is connected with the power supply end of the MCU circuit, connected with one end of the capacitor and connected with the cathode of the amplitude limiting voltage-stabilizing tube; the other end of the capacitor is grounded with the anode of the amplitude limiting voltage-stabilizing tube; the capacitor stores additional voltage to provide working power supply for the MCU circuit, and the amplitude limiting voltage regulator tube connected in parallel with the capacitor limits the charging voltage value of the capacitor to a certain voltage amplitude.

Further, a power supply terminal of the MCU circuit is connected to a cathode of the steering diode, and a negative terminal of the MCU circuit is Grounded (GND). The MCU circuit comprises main elements and necessary peripheral elements, wherein the main elements can be a Single Chip Microcomputer (SCM), a system on chip (SoC), a CPLD, an FPGA or an ARM, a DSP and the like. The invention has the beneficial effects that the problems of mutual independence of a power supply circuit and a sampling circuit, large overall power consumption, complex circuit structure, more elements, high cost and the like in the existing measurement and control scheme are solved, and the sampling and power-taking multiplexing circuit scheme which is simple in circuit, less in element number, low in cost, extremely low in power consumption and easy to realize is provided.

Drawings

Fig. 1 is a schematic diagram of a sampling and power-taking multiplexing circuit according to the present invention.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.

In the invention, the current-limiting resistor is multiplexed in a time-sharing manner, and the energy-storage capacitor is charged through the guide diode at a certain moment, wherein the charging voltage is the working power supply of the MCU circuit; and the other moment and the sampling resistor form a voltage division circuit, and the divided voltage value SA represents the bus voltage.

In the invention, the MCU circuit controls the state of the I/O port, when the bus voltage needs to be sampled, the I/O port is set to be in an output low level state, and the voltage flowing through two ends of the sampling resistor is converted into a digital value through A/D (analog/digital) for further processing by a program. After the conversion is finished, the MCU circuit sets the I/O port to be in a high-impedance state, and the current flowing through the current-limiting resistor is charged to the capacitor by the isolating diode.

In the invention, the A/D conversion adopts the reference voltage inside the MCU circuit, such as 3V, so that the conversion precision is not influenced by the power supply voltage of the MCU circuit.

In the invention, the MCU circuit internal low voltage (such as 4.1V) reset detection function is utilized, if low voltage reset is produced within tens of milliseconds, the time of a sampling stage is shortened as much as possible in the cyclic process of charging, sampling and charging, and conversely, if low voltage reset is not produced within hundreds of milliseconds, the sampling time is gradually prolonged. By utilizing the reset detection function and organically combining with the bus voltage value for operation, the adoption period is shortened or lengthened, and the function of automatically adjusting the capacitor charging-MCU circuit voltage is achieved.

Furthermore, in order to fully reduce the power consumption of the MCU circuit, a program in the MCU circuit can be set to run in a mode of waking up the watchdog in a clearance mode, if the timed wake-up time of the watchdog is set to be 1ms, the watchdog wakes up the CPU to execute a sampling program and perform relevant input and output control processing and the like every 1ms, and then the CPU enters a sleep mode again, and the clearance working mode can meet the real-time control requirement in most occasions and can reduce the working current of the CPU to the maximum extent, and the average working current of the CPU does not exceed 100 uA. Taking the example of detecting the voltage of the ac 220V, taking 110V as an example, taking the voltage value VP after full-wave rectification as 110 × 0.9 (rectification coefficient) as 99V, and the MCU circuit operating voltage as 5V, then R1 as (99V-5V)/100uA as 0.94M Ω, and taking the nominal value 910K Ω. Considering that the fluctuation range of the alternating current 220V voltage is +/-20%, the maximum value is 264V, the amplitude of the rectified full-wave ripple voltage is 264V × 0.9 ≈ 238V, and the A/D conversion adopts a 3V reference voltage inside a CPU, then R2 is 3 × 910/(238-3) ≈ 11.6K Ω, and the nominal value is 11.5K Ω.

A sampling and electricity-taking multiplexing circuit comprises a main current-limiting resistor, wherein one end of the current-limiting resistor is connected to the direct-current bus voltage or the pulsating direct-current voltage end after alternating current rectification, and the other end of the current-limiting resistor is connected to the A/D output end of an MCU circuit, connected to one end of a sampling resistor and connected to the anode of a guide diode. The other end of the sampling resistor is connected to one I/O port of the MCU circuit. The cathode of the guide diode is connected with the power supply end of the MCU circuit, connected with one end of the capacitor and connected with the cathode of the amplitude limiting voltage-stabilizing tube. The other end of the filter capacitor is grounded, and the anode of the amplitude limiting voltage regulator tube is grounded.

An embodiment of a main portion of a sampling and power-taking multiplexing circuit is described with reference to fig. 1 below.

In fig. 1, one end of the current limiting resistor R1 is connected to the dc bus voltage or pulsating dc voltage after ac rectification to be monitored, which is defined as VP, and the other end is connected to the a/D input of the MCU circuit, one end of the sampling resistor R2, and the anode of the isolation diode D1. The cathode of the D1 is connected with the power supply end of the MCU circuit, connected with one end of the charging energy storage capacitor C1 and connected with the cathode of the amplitude limiting voltage regulator tube Z1. The other end of C1 and the anode of Z1 are grounded. The common negative terminal of the MCU circuit is grounded. The other end of the R2 is connected with an I/O port line of the MCU circuit. At the moment of power-on, each port of the MCU circuit is in a high-impedance state due to no working voltage, the VP voltage R1 is limited, and the MCU circuit is charged to C1 after being guided by D1 until the working voltage required by the MCU circuit is established, such as 3.3V, 5V and the like, and the MCU is reset and started to work. After reset, the program in the MCU controls the I/O port to be changed into output low level, one end of the R2 connected with the I/O is equivalent to ground, the voltage value SA at the two ends of the R2 is in direct proportion to the voltage value VP, and the program in the MCU converts the voltage value SA into a digital value through the A/D port for the internal program to process. After the conversion is finished, the I/O port of the MCU circuit is converted into a high-impedance state (no current is input, which is equivalent to a disconnected state), the VP is limited by the R1, and is guided by the diode to continuously charge the C1, and the steps are repeated, so that the multiplexing function of sampling and power taking by one resistor is realized. In order to prevent the charging of the C1 from being unexpectedly overhigh, a limiting voltage regulator tube Z1 is arranged to limit the highest charging voltage of the C1.

In conclusion, the sampling circuit and the MCU circuit are integrated into a whole, so that the circuit structure is fully simplified, the production cost is reduced, and the sampling circuit is particularly suitable for occasions with extremely small circuit board area, low product cost, low power consumption and the like.

In light of the foregoing, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.