Echo signal receiving channel switching circuit and method for multi-channel ultrasonic flow meter

Abstract

The application provides an echo signal receiving channel switching circuit and method of a multi-channel ultrasonic flowmeter, comprising: input ends of multiple groups of signal limiting circuits are connected to ultrasonic transducers; multiple input ends of a two-way multi-channel data selector are connected to output ends of the multiple groups of signal limiting circuits; each address end of the two-way multi-channel data selector is connected to a GPIO of an MCU controller; two-way common ends of the two-way multi-channel data selector are connected to A-channel common ends and B-channel common ends of a two-channel multiplexer; normally closed ends of A, B and C paths of the two-channel multiplexer are connected to a power supply ground, and normally open ends are connected; each address end of the two-channel multiplexer is connected to a GPIO of the MCU controller; and the C-channel common end of the two-channel multiplexer is connected to a voltage bias circuit. The application provides a low-power-consumption and low-cost echo signal receiving and channel switching circuit of a multi-channel ultrasonic flowmeter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic circuit, in particular to echo signal receiving channel switching circuit and method of multi-channel ultrasonic flowmeter. BACKGROUND

[0002] Due to the ultrasonic flowmeter has zero pressure loss, large range ratio, low initial flow, maintenance-free and many advantages, in recent years, in the domestic market has been rapid popularization and application. The measurement accuracy and reliability of ultrasonic flowmeter can be improved by increasing the measurement channel, so in most high-precision and high-reliability applications, multi-channel ultrasonic flowmeter is required. The current domestic ultrasonic flowmeter mainstream products are mainly single / dual channel configuration, and the use of multi-channel configuration involves circuit power consumption, hardware cost, complexity of controlling measurement channel, mutual coupling interference between channels, computing power of processing unit and many other factors.

[0003] As known to all, the measurement channel of ultrasonic flowmeter is composed of a pair of ultrasonic transducers installed on the measurement pipeline, transducer drive circuit and echo signal conditioning circuit, and multiple channels require multiple pairs of transducers, transducer drive circuit and echo signal conditioning circuit. At the same time, the ultrasonic transducer is a receiving and transmitting integrated sensor, which is used for transmitting ultrasonic signals and receiving ultrasonic signals at the same time. Therefore, the drive circuit of the transducer and the echo signal receiving circuit are connected to one end of the ultrasonic transducer at the same time. When the ultrasonic transducer transmits ultrasonic signals, the excitation pulse signal applied to the end of the ultrasonic transducer will also enter the echo signal conditioning circuit, causing great interference in the circuit, noise interference on the ultrasonic echo signal, and further affecting the measurement accuracy.

[0004] The current multi-channel ultrasonic flowmeter products in the industry have multiple measurement channel solutions, which refer to single-channel ultrasonic flowmeter, copy the single-channel circuit, that is, multiple independent transducer drive circuits and echo signal conditioning channels are configured for multiple channels. Some use analog switches to switch the transducer pair to a pair of transducer drive circuit and echo signal conditioning channel to achieve the purpose of reducing power consumption and cost.

[0005] For the method of directly copying channels, it is obvious that the hardware circuit cost and power consumption will increase exponentially with the increase of the number of channels, and at the same time, it will also cause the increase of the circuit board area and many other problems. For the method of using analog switches, the analog switch itself will cause circuit interference when switching, and at the same time, because the original echo signal is based on a zero-biased class of positive wave signal, in order to make the signal not distorted, the analog switch needs to be powered by dual power supply, which additionally increases the circuit cost and power consumption. SUMMARY

[0006] To solve the above problems, the present application provides echo signal receiving channel switching circuit and method of multi-channel ultrasonic flowmeter.

[0007] To achieve the above object, the application provides the technical scheme as follows.

[0008] The echo signal receiving channel switching circuit of the multi-channel ultrasonic flowmeter comprises:

[0009] The voltage bias circuit, the receiving channel switching circuit and the multiple sets of signal limiting circuits;

[0010] The input ends of the multiple sets of signal limiting circuits are respectively connected to the multiple ultrasonic transducers of the multi-channel ultrasonic flowmeter;

[0011] The receiving channel switching circuit comprises an MCU controller, a two-way multi-channel data selector and a two-channel multiplexer;

[0012] The multiple input ends of the two-way multi-channel data selector are respectively connected to the output ends of the multiple sets of signal limiting circuits; each address end of the two-way multi-channel data selector is connected to a GPIO of the MCU controller; and the two-way common ends of the two-way multi-channel data selector are respectively connected to the A-channel common end and the B-channel common end of the two-channel multiplexer.

[0013] The normally closed ends of the A, B and C channels of the two-channel multiplexer are connected to the power supply ground, and the normally open ends are connected to each other; each address end of the two-channel multiplexer is connected to a GPIO of the MCU controller; and the C-channel common end of the two-channel multiplexer is connected to the voltage bias circuit.

[0014] Preferably, each set of signal limiting circuit comprises a direct-current isolation capacitor, a current-limiting resistor and a clamping diode.

[0015] One end of the direct-current isolation capacitor is connected to the ultrasonic transducer, and the other end is connected to one end of the current-limiting resistor; the other end of the current-limiting resistor is connected to the clamping end of the clamping diode; the anode of the clamping diode is connected to the power supply ground, and the cathode is connected to the power supply.

[0016] The other end of the current-limiting resistor is connected to the input end of the two-way multi-channel data selector.

[0017] Preferably, the voltage bias circuit comprises a voltage reference, a filtering capacitor and a current-limiting resistor.

[0018] The input end of the voltage reference is connected to the positive electrode of the power supply, and the output end is connected to one end of the filtering capacitor; the other end of the filtering capacitor is connected to the power supply ground.

[0019] One end of the current-limiting resistor is connected to the output end of the voltage reference, and the other end is connected to the C-channel common end of the two-channel multiplexer of the receiving channel switching circuit.

[0020] A method for switching echo signal receiving channels of a multi-channel ultrasonic flowmeter, comprising the following steps:

[0021] Configuring multiple GPIOs of the MCU controller to be powered on as output mode;

[0022] According to the preset output level state of each channel GPIO, the uplink and downlink ultrasonic transducer signals of each channel of the ultrasonic flowmeter are sequentially received in order:

[0023] The MCU controller outputs multiple GPIO output level states, and determines the corresponding channel to be received according to the level state of each GPIO;

[0024] The second channel of the two channels of the dual-channel multi-channel data selector is selected with the common end;

[0025] When receiving the uplink transducer echo signal, the MCU controller GPIO controls the A channel, the C channel common end and the normally open end of the dual-channel multiplexer to be connected, and the B channel common end and the normally closed end to be connected; when receiving the downlink transducer echo signal, the MCU controller GPIO controls the B channel, the C channel common end and the normally open end of the dual-channel multiplexer to be connected; and the A channel common end and the normally closed end to be connected;

[0026] The echo signal reception of each channel is completed in order.

[0027] The present application provides a multi-channel ultrasonic flowmeter echo signal receiving channel switching circuit and method, which has the following advantages:

[0028] The multi-channel ultrasonic flowmeter echo signal receiving circuit controls the dual-channel multi-channel data selector and the dual-channel multiplexer to connect different ultrasonic transducers with the rear signal conditioning circuit in time through multiple GPIO ports in the MCU controller, so as to realize the reception of all ultrasonic transducer signals of the multi-channel ultrasonic flowmeter; the limiting amplifier circuit and the dual-channel multiplexer completely isolate the interference of the excitation pulse output by the ultrasonic transducer transmitting circuit on the receiving circuit; the limiting amplifier circuit and the dual-channel multi-channel data selector increase the isolation degree between channels; the combination switching method of the dual-channel multi-channel data selector and the dual-channel multiplexer is adopted, only one rear echo signal conditioning circuit is reserved, the echo signals of different transducers are conditioned in time by using the multiplexing mode, which reduces the hardware circuit cost and the circuit board area, and also reduces the overall power consumption of the circuit. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The present application provides a multi-channel ultrasonic flowmeter receiving channel switching circuit structure diagram;

[0030] Figure 2The structure schematic diagram of the limiting circuit of the receiving sound channel switching circuit of the multi-sound channel ultrasonic flowmeter provided by the application is shown in the figure.

[0031] Figure 3 The structure schematic diagram of the sound channel switching circuit of the receiving sound channel switching circuit of the multi-sound channel ultrasonic flowmeter provided by the application is shown in the figure.

[0032] Figure 4 The structure schematic diagram of the reference circuit of the receiving sound channel switching circuit of the multi-sound channel ultrasonic flowmeter provided by the application is shown in the figure.

[0033] Figure 5 The internal structure diagram of the dual-path multi-channel data selector in the receiving sound channel switching circuit of the multi-sound channel ultrasonic flowmeter provided by the application is shown in the figure.

[0034] Figure 6 The internal structure diagram of the dual-channel multiplexer in the receiving sound channel switching circuit of the multi-sound channel ultrasonic flowmeter provided by the application is shown in the figure. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and do not limit the application.

[0036] Example 1

[0037] The echo signal receiving channel switching circuit and method of the multi-sound channel ultrasonic flowmeter of the application, as shown in the figure, wherein the number of sound channels is n / 2 (n is the number of transducers, which must be an even number). Specifically, it includes: Figures 1-6

[0038] Each ultrasonic transducer of the multi-sound channel ultrasonic flowmeter is connected to one end of the direct current blocking capacitor C of the input limiting circuit; the other end of the direct current blocking capacitor C of the input limiting circuit is connected to one end of the current limiting resistor R, and the other end of the current limiting resistor R is connected to the clamping end of the clamping diode; the cathode of the clamping diode of the input limiting circuit is connected to the power supply, and the anode of the clamping diode is connected to the power supply ground.

[0039] The clamping end of the clamping diode of the input limiting circuit is connected to the data end Xi, Yi (i=0, 1, 2,...) of the dual-path multi-channel data selector in the input sound channel switching circuit, and the clamping end of the clamping diode of the input limiting circuit of the two transducers connected to the same sound channel must be connected to a pair of Xi, Yi data ends of the dual-path multi-channel data selector of the receiving channel switching circuit.

[0040] ​The two-way common data end (X_COM, Y_COM) of the two-way multi-channel data selector of the receiving channel switching circuit is connected to the two-way common data end (a_com, b_com) of the two-channel multiplexer; the normally open end ax, bx, cx of the two-channel multiplexer of the receiving channel switching circuit is connected together, and the normally closed end ay, by, cy is grounded; the GPIO1, GPIO2, GPIO3 of the MCU controller of the receiving channel switching circuit is connected to the address end A, B, C of the two-way multi-channel data selector, respectively (the embodiment selects a two-way 8-channel data selector, which has 3 address lines), and the GPIO4, GPIO5, GPIO6 is connected to the address end D1, D2, D3 of the two-channel multiplexer.

[0041] The power supply end of the voltage reference of the voltage biasing circuit is connected to the power supply, the ground end of the voltage reference is connected to the power supply ground, the output end of the voltage reference is connected to one end of the filtering capacitor C, and the other end of the filtering capacitor is connected to the power supply ground. The output end of the voltage reference of the voltage biasing circuit is connected to one end of the current limiting resistor R, and the other end of the current limiting resistor R is connected to the other common end C_COM of the two-channel multiplexer in the receiving channel switching circuit.

[0042] A control method of a multi-channel ultrasonic flowmeter signal receiving channel switching circuit, specifically comprising the following steps:

[0043] Step one, the MCU configures GPIO1-GPIO6 as output mode.

[0044] Step two, when starting the first ultrasonic channel measurement, the MCU controller GPIO1, GPIO2, GPIO3 outputs low level; the data end of the two-way multi-channel data selector X0 and Y0 is connected with the X_COM and Y_COM end, GPIO4, GPIO5, GPIO6 outputs high, low, high level respectively, the a_com end of the two-channel multiplexer is connected with the ax end, the cx end is connected with the c_com end, and the b_com end is connected with the by end.

[0045] Step three, the bias voltage circuit is connected to the cx end through the c_com end, connected to the ax end, connected to the a_com end, connected to the X_COM end, and connected to the X0 end, providing bias voltage for the ultrasonic transducer connected to the X0 end through the input limiting circuit.

[0046] Step four, the ultrasonic transducer connected to the X0 end through the limiting circuit in the receiving state receives the ultrasonic signal, which is connected to the X_COM end, the a_com end, the ax end, the cx end, the c_com end and the signal conditioning circuit through the limiting circuit connected to the X0 end of the receiving channel switching circuit.

[0047] Step five, the ultrasonic transducer connected to Y0 end through the limiting circuit in the transmitting state transmits ultrasonic signal, the driving pulse of the transducer stimulates the transducer at the same time, through the input limiting circuit, connected to the Y0 end of the receiving channel switching circuit, connected to the Y_COM end, connected to the b_com end, connected to the by end, connected to the power supply ground.

[0048] Step six, the above measuring sound channel ultrasonic transducer transmits and receives state conversion, MCU controller GPIO1, GPIO2, GPIO3 output low level; the X0 and Y0 data end of the double channel multi-channel data selector and the X_COM and Y_COM end are communicated, GPIO4, GPIO5, GPIO6 output low level, high level, high level respectively, the b_com end and the bx end of the double channel multiplexer are communicated, the cx end and the c_com end are communicated, the a_com end and the ay end are communicated.

[0049] Step seven, the bias voltage circuit is connected to the cx end through the c_com end, connected to the bx end, connected to the b_com end, connected to the Y_COM end, connected to the Y0 end, providing bias voltage for the ultrasonic transducer connected to the Y0 end through the input limiting circuit.

[0050] Step eight, the ultrasonic transducer connected to Y0 end through the limiting circuit in the receiving state receives ultrasonic signal, the signal is communicated to Y_COM end through the limiting circuit connected to receiving channel switching circuit Y0 end, connected to b_com end, connected to bx end, connected to cx end, connected to c_com end, connected to signal conditioning circuit.

[0051] Step nine, the ultrasonic transducer connected to X0 end through the limiting circuit in the transmitting state transmits ultrasonic signal, the driving pulse of the transducer stimulates the transducer at the same time, through the input limiting circuit, connected to the X0 end of the receiving channel switching circuit, connected to the X_COM end, connected to the a_com end, connected to the ay end, connected to the power supply ground.

[0052] Step 10, according to step one to step nine, the 6 GPIO of MCU output state according to table 1, polling receiving ultrasonic transducer signal of each sound channel of ultrasonic flowmeter in order.

[0053] Table 1 ultrasonic transducer signal polling receiving MCU GPIO control state

[0054]

[0055] In summary, the multi-channel ultrasonic flowmeter receives the sound channel switching circuit, solves the problems of high hardware cost, large circuit power consumption, large circuit board area occupation, and interference of transmitting transducer excitation pulse to receiving channel receiving signal of existing multi-channel ultrasonic flowmeter, and the bias circuit solves the problem of double power supply required by analog switch.

[0056] Embodiment 2

[0057] Suppose an eight-channel ultrasonic flowmeter:

[0058] An eight-channel ultrasonic flowmeter has 16 ultrasonic transducers, according to the previous technology, one ultrasonic transducer is configured with one ultrasonic signal conditioning circuit, so 16 ultrasonic transducers need 16 echo signal conditioning circuits, the circuit cost, hardware power consumption, and circuit board area will be 16 times of the cost, power consumption, and circuit board area of one signal conditioning circuit. And the multi-channel ultrasonic signal receiving channel switching circuit and the control method thereof are adopted, 16 ultrasonic transducers are connected to 16 input limiting circuits, the input limiting circuits are connected to 16 data ends of the dual-channel multi-channel data selector of the receiving sound channel switching circuit, each ultrasonic transducer is switched to the bias voltage circuit by the MCU controller, and then input to the echo signal conditioning circuit. Therefore, the signal receiving channel switching circuit and the control method of the multi-channel ultrasonic flowmeter circuit of the application can be used for any channel number of ultrasonic flowmeter, only one echo signal conditioning circuit is required. The hardware cost is reduced by N times, the hardware power consumption is reduced by N times, and the circuit board area is reduced by N times (N is the number of measurement channels).

[0059] The above is only a preferred embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An echo signal receiving channel switching circuit for a multi-channel ultrasonic flow meter, characterized by The application relates to an echo signal receiving channel switching circuit. The echo signal receiving channel switching circuit comprises a voltage bias circuit, a receiving channel switching circuit and multiple groups of signal limiting circuits. The input ends of the multiple groups of signal limiting circuits are connected to multiple ultrasonic transducers of a multi-channel ultrasonic flowmeter. The receiving channel switching circuit comprises an MCU controller, a two-way multi-channel data selector and a two-channel multiplexer. The multiple input ends of the two-way multi-channel data selector are connected to the output ends of the multiple groups of signal limiting circuits. The two-way multi-channel data selector is connected to the A-channel common end and the B-channel common end of the two-channel multiplexer. The normally closed ends of the A, B and C channels of the two-channel multiplexer are connected to a power supply ground, and the normally open ends are connected to each other. The multiple GPIOs of the MCU controller are configured as output modes. The uplink and downlink ultrasonic transducer signals of each channel of the ultrasonic flowmeter are received in sequence according to the preset output level state of each channel GPIO. The output level state of the multiple GPIOs of the MCU controller is outputted, and the corresponding channel is determined according to the level state of each GPIO. The second channel of the two channels of the two-way multi-channel data selector is selected by the common end. When the uplink transducer echo signal is received, the A-channel and C-channel common ends of the two-channel multiplexer are connected to the normally open end, and the B-channel common end is connected to the normally closed end. The echo signal receiving of each channel is completed in sequence.

2. The echo signal receiving path switching circuit of a multi-channel ultrasonic flow meter according to claim 1, characterized by, Each group of signal limiting circuits comprises a direct-current isolation capacitor, a current limiting resistor and a clamping diode. One end of the direct-current isolation capacitor is connected to the ultrasonic transducer, and the other end is connected to one end of the current limiting resistor. The other end of the current limiting resistor is connected to the clamping end of the clamping diode.

3. The echo signal receiving path switching circuit of a multi-channel ultrasonic flow meter according to claim 1, wherein The anode of the clamping diode is connected to the power supply ground, and the cathode is connected to the power supply. The other end of the current limiting resistor is connected to the input end of the two-way multi-channel data selector. The voltage bias circuit comprises a voltage reference, a filter capacitor and a current limiting resistor. The input end of the voltage reference is connected to the positive electrode of the power supply, and the output end is connected to one end of the filter capacitor. The other end of the current limiting resistor is connected to the C-channel common end of the two-channel multiplexer of the receiving channel switching circuit.

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