Low-power-consumption excitation circuit and electromagnetic flowmeter
By introducing a combination of PWM pulse width modulation and integrated excitation switch module into the electromagnetic flowmeter, the excitation voltage and current are adjusted, and the problem of high power consumption of the excitation circuit is solved, achieving low power consumption and high precision measurement effects.
Patent Information
- Application Number
- CN202421696898.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-17
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-07-17
AI Technical Summary
The excitation circuit of existing electromagnetic flowmeters has high power consumption, resulting in short battery life and reduced measurement accuracy, which is particularly prominent in the absence of market electricity.
The combination of PWM pulse width modulation module, digital-to-analog conversion module, integrated excitation switch module, excitation voltage detection module and power supply battery is adopted to adjust the excitation voltage and current, and the integrated excitation switch module replaces discrete switching elements to achieve low power consumption control of the excitation circuit.
It effectively reduces the power consumption of the excitation circuit, improves the measurement accuracy of the electromagnetic flowmeter and the battery life, and avoids the inaccurate measurement caused by overheating of components.
Smart Images
Figure CN223179591U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of flow detection, in particular to a low-power excitation circuit and an electromagnetic flowmeter. Background Art
[0002] An electromagnetic flowmeter is an instrument that applies the principle of electromagnetic induction to measure the flow rate of a conductive fluid based on the induced electromotive force generated when the conductive fluid passes through an externally applied magnetic field.
[0003] An electromagnetic flowmeter is composed of an electromagnetic flow sensor and an electromagnetic flow converter. The electromagnetic flow converter provides an excitation current for the electromagnetic flow sensor to establish a magnetic field required for measurement through an excitation coil in the electromagnetic flow sensor. The electromagnetic flow sensor converts the actual flow rate of the fluid into a potential difference between electrodes, and the electromagnetic flow converter converts the potential difference between electrodes into flow information for real-time display.
[0004] An electromagnetic flowmeter usually uses mains power supply. However, for some special scenarios without mains power (such as remote outdoors), it can only use battery power supply. In order to improve the service life of the battery and thus reduce the battery replacement frequency of the battery-powered electromagnetic flowmeter, it is necessary to minimize the power consumption of the electromagnetic flowmeter as much as possible.
[0005] The part with the largest power consumption in an electromagnetic flowmeter is the excitation circuit that provides the excitation current for the excitation coil, accounting for about 60%-70% of the total power consumption of the circuit system of the electromagnetic flowmeter. Since the DC resistance range of the excitation coil is relatively wide, in the existing excitation circuit, the excitation voltage cannot be adjusted. The smaller the excitation resistance, the greater the power loss on other components (such as transistors). Moreover, when implementing the switching control of the excitation voltage (current), a large number of discrete switching elements (such as triodes, Darlington tubes, field effect tubes, etc.) are used, which also increases the power consumption of the excitation circuit to a certain extent and easily leads to high temperature of the circuit, affecting the measurement accuracy of the electromagnetic flowmeter.
[0006] Therefore, how to minimize the power consumption of the excitation circuit of the electromagnetic flowmeter as much as possible is an urgent problem to be solved at present. Summary of the Utility Model
[0007] Aiming at the defects in the prior art, the utility model aims to provide a low-power excitation circuit and an electromagnetic flowmeter that can effectively reduce the power consumption of the excitation circuit of the electromagnetic flowmeter and improve the measurement accuracy of the electromagnetic flowmeter.
[0008] To achieve the above purpose, the utility model adopts the following technical solutions:
[0009] According to the first aspect of the present utility model, the present utility model provides a low-power excitation circuit, which includes an excitation coil disposed on an electromagnetic flow sensor, and further includes an excitation control module, a PWM pulse width modulation module, a digital-to-analog conversion module, an integrated excitation switch module, an excitation voltage detection module, and a power supply battery.
[0010] The signal output end of the PWM pulse width modulation module is connected to the signal input end of the digital-to-analog conversion module, and the signal output end of the digital-to-analog conversion module is connected to the signal input end of the integrated excitation switch module.
[0011] The integrated excitation switch module has two excitation driving ends. The two excitation driving ends of the integrated excitation switch module are respectively connected to both ends of the excitation coil, and the power input end of the integrated excitation switch module is connected to the power supply battery.
[0012] The signal input end of the excitation voltage detection module is connected to the excitation coil, the signal output end of the excitation voltage detection module is connected to the signal input / output end of the excitation control module, and the signal output end of the excitation control module is connected to the signal input end of the PWM pulse width modulation module.
[0013] Wherein, the PWM pulse width modulation module is used to output a digitally encoded pulse width modulation signal, the digital-to-analog conversion module is used to convert the pulse width modulation signal into an analog level signal, the integrated excitation switch module is used to control the excitation voltage at both ends of the excitation coil according to the analog level signal, the excitation voltage detection module is used to detect the excitation voltage value of the excitation coil, and the excitation control module is used to control the PWM pulse width modulation module to adjust the duty cycle of the pulse width modulation signal according to the excitation voltage value.
[0014] Preferably, the integrated excitation switch module has two signal input ends, the excitation control module has two signal output ends, the PWM pulse width modulation module includes a first PWM pulse width modulator and a second PWM pulse width modulator, and the digital-to-analog conversion module includes a first digital-to-analog converter and a second digital-to-analog converter. Among them,
[0015] One signal output end of the excitation control module, the first PWM pulse width modulator, the first digital-to-analog converter, and one signal input end of the integrated excitation switch module are connected in sequence;
[0016] The other signal output end of the excitation control module, the second PWM pulse width modulator, the second digital-to-analog converter, and the other signal input end of the integrated excitation switch module are connected in sequence.
[0017] Preferably, the integrated excitation switch module adopts an integrated bridge chip with the model number ZXMHC3A01 N8.
[0018] Preferably, the P1S / P2S terminals of the integrated bridge chip are connected to the power supply battery, the P1D / N1D terminals and the P2D / N2D terminals are respectively connected to both ends of the exciting coil, the P1G terminal is connected to the N2G terminal and then connected to the signal output terminal of the first digital-to-analog converter, the P2G terminal is connected to the N1G terminal and then connected to the signal output terminal of the second digital-to-analog converter, and the N1S / N2S terminals are grounded.
[0019] Preferably, the exciting control module uses a single-chip microcomputer of model MSP430F5418A, the first PWM pulse width modulator and the second PWM pulse width modulator both use PWM control chips of model SG3525, and the first digital-to-analog converter and the second digital-to-analog converter both use digital-to-analog conversion chips of model DAC7724.
[0020] Preferably, the exciting voltage detection module includes a sampling resistor. The sampling resistor and the exciting coil are connected in series between the two exciting drive terminals of the integrated exciting switch module. The exciting control module has two signal input terminals. One end of the sampling resistor is connected to one signal input terminal of the exciting control module, and the other end of the sampling resistor is connected to the other signal input terminal of the exciting control module.
[0021] Preferably, the low-power exciting circuit further includes an opto-isolation module. The signal input terminal of the opto-isolation module is connected to the signal output terminal of the exciting voltage detection module, and the signal output terminal of the opto-isolation module is connected to the signal input terminal of the exciting control module.
[0022] Preferably, the opto-isolation module includes a first opto-coupler and a second opto-coupler. One end of the sampling resistor is connected to one signal input terminal of the exciting control module through the first opto-coupler, and the other end of the sampling resistor is connected to the other signal input terminal of the exciting control module through the second opto-coupler.
[0023] Preferably, the sampling resistor uses a milliohm-level resistor.
[0024] According to the second aspect of the present invention, the present application provides an electromagnetic flowmeter, including the low-power exciting circuit according to any one of the above first aspects.
[0025] The utility model is provided with an excitation control module, a PWM pulse width modulation module, a digital-to-analog conversion module, an integrated excitation switch module, an excitation voltage detection module and a power supply battery. The PWM pulse width modulation module outputs a pulse width modulation signal after digital coding. The digital-to-analog conversion module converts the pulse width modulation signal into an analog level signal. The integrated excitation switch module controls the excitation voltage at both ends of the excitation coil according to the analog level signal, so that the excitation coil generates a variable excitation magnetic field. The excitation voltage detection module detects the excitation voltage value of the excitation coil. The excitation control module controls the PWM pulse width modulation module to adjust the duty cycle of the pulse width modulation signal in real time according to the excitation voltage value, so that the excitation voltage can be adjusted correspondingly for excitation coils with different impedances, and then the excitation current passing through the excitation coil can be adjusted to realize the adjustment of a suitable excitation current value, avoiding excessive power consumption of other components caused by different excitation currents generated by excitation coils with different impedances, thereby ensuring that other components work under conditions of lower power loss. In addition, in terms of the on-off control of excitation, the utility model adopts an integrated excitation switch module to replace the existing discrete switch components, further reducing the power consumption of the excitation circuit and better avoiding the adverse impact on the measurement accuracy of the electromagnetic flowmeter due to excessive temperature of the components in the excitation circuit.
[0026] Additional aspects and advantages of the utility model will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the utility model. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the specific embodiments of the utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally denoted by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.
[0028] Figure 1 is a circuit principle block diagram of a low-power excitation circuit in an embodiment of the utility model;
[0029] Figure 2 is a circuit principle block diagram of a low-power excitation circuit in another embodiment of the utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0030] The following will describe in detail the embodiments of the technical solutions of the utility model with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the utility model, so they are only examples and cannot be used to limit the protection scope of the utility model.
[0031] It should be noted that unless otherwise specified, the technical terms or scientific terms used in this application should have the ordinary meanings understood by those skilled in the art to which the utility model belongs.
[0032] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model.
[0033] In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. In the description of the present utility model, the meaning of "a plurality of" is two or more unless otherwise specifically defined.
[0034] In the present application, unless otherwise clearly specified and defined, the terms such as "install", "connect", "connection", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.
[0035] In the present application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.
[0036] As Figure 1-2 shown, an embodiment of the present utility model provides a low-power excitation circuit, including an excitation coil 1, an excitation control module 2, a PWM pulse width modulation module 3, a digital-to-analog conversion module 4, an integrated excitation switch module 5, an excitation voltage detection module 6, and a power supply battery 7.
[0037] The signal output end of the PWM pulse width modulation module 3 is connected to the signal input end of the digital-to-analog conversion module 4, and the signal output end of the digital-to-analog conversion module 4 is connected to the signal input end of the integrated excitation switch module 5.
[0038] The integrated excitation switch module 5 has two excitation drive ends. The two excitation drive ends of the integrated excitation switch module 5 are respectively connected to both ends of the excitation coil 1, and the power input end of the integrated excitation switch module 5 is connected to the power supply battery 7.
[0039] The signal input end of the excitation voltage detection module 6 is connected to the excitation coil 1, the signal output end of the excitation voltage detection module 6 is connected to the signal input and output end of the excitation control module 2, and the signal output end of the excitation control module 2 is connected to the signal input end of the PWM pulse width modulation module 3.
[0040] Among them, the PWM pulse width modulation module 3 is used to output a digitally encoded pulse width modulation signal, the digital-to-analog conversion module 4 is used to convert the pulse width modulation signal into an analog level signal, the integrated excitation switch module 5 is used to control the excitation voltage at both ends of the excitation coil 1 according to the analog level signal, the excitation voltage detection module 6 is used to detect the excitation voltage value of the excitation coil 1, and the excitation control module 2 is used to control the PWM pulse width modulation module 3 to adjust the duty cycle of the pulse width modulation signal according to the excitation voltage value.
[0041] The working principle of the low-power excitation circuit in this embodiment is as follows:
[0042] After the circuit is started, the PWM pulse width modulation module 3 outputs a digitally encoded pulse width modulation signal according to the preset initial duty cycle value. The digital-to-analog conversion module 4 converts the pulse width modulation signal into an analog level signal. The integrated excitation switch module 5 controls the on-off state and on-off duration of each switch component in the integrated excitation switch module 5 according to the high and low levels of the analog level signal, so as to control the excitation voltage at both ends of the excitation coil 1, so that the excitation coil 1 generates a changing excitation magnetic field. During the working process of the circuit, the excitation voltage detection module 6 detects the excitation voltage value of the excitation coil 1, and the excitation control module 2 controls the PWM pulse width modulation module 3 to adjust the duty cycle of the pulse width modulation signal in real time according to the excitation voltage value.
[0043] The low-power excitation circuit of this embodiment can correspondingly adjust the excitation voltage for excitation coils 1 with different impedances, and then adjust the excitation current passing through the excitation coils 1, so as to achieve the adjustment of appropriate excitation current values, so that the current value on the excitation coils 1 reaches the target current value, thereby reducing the power loss of other components except the excitation coils 1 in the excitation circuit, avoiding excessive power consumption of other components caused by different excitation currents generated by excitation coils 1 with different impedances, and ensuring that other components work under the condition of lower power loss. In addition, in terms of the on-off control of excitation, this utility model uses an integrated excitation switch module 5 to replace the existing discrete switch components, further reducing the power consumption of the excitation circuit and better avoiding the adverse impact on the measurement accuracy of the electromagnetic flowmeter caused by excessive temperature of the components in the excitation circuit.
[0044] As Figure 2 shown, in one embodiment, the integrated excitation switch module 5 has two signal input terminals, the excitation control module 2 has two signal output terminals, the PWM pulse width modulation module 3 includes a first PWM pulse width modulator 31 and a second PWM pulse width modulator 32, and the digital-to-analog conversion module 4 includes a first digital-to-analog converter 41 and a second digital-to-analog converter 42. Among them,
[0045] One signal output terminal of the excitation control module 2, the first PWM pulse width modulator 31, the first digital-to-analog converter 41, and one signal input terminal of the integrated excitation switch module 5 are connected in sequence;
[0046] The other signal output terminal of the excitation control module 2, the second PWM pulse width modulator 32, the second digital-to-analog converter 42, and the other signal input terminal of the integrated excitation switch module 5 are connected in sequence.
[0047] Specifically, in this embodiment, the integrated excitation switch module 5 uses an integrated bridge chip with the model of ZXMHC3A01 N8. The P1 S / P2S terminals of the integrated bridge chip are connected to the power supply battery 7, the P1 D / N1 D terminals and the P2D / N2D terminals are respectively connected to both ends of the excitation coil 1, the P1 G terminal is connected to the N2G terminal and then connected to the signal output terminal of the first digital-to-analog converter 41, the P2G terminal is connected to the N1 G terminal and then connected to the signal output terminal of the second digital-to-analog converter 42, and the N1 S / N2S terminals are grounded.
[0048] In this embodiment, the integrated bridge chip ZXMHC3A01 N8 is used as the component that controls the excitation current switch of the excitation coil 1 in the excitation circuit. Compared with using discrete components such as triodes and field effect transistors, it can effectively reduce the power loss of the switching element, and can effectively reduce costs and improve the reliability of the circuit. ZXMHC3A01 N8 includes two pairs of complementary N-type MOS transistors (Q3, Q4) and P-type MOS transistors (Q1, Q2). By loading the high and low levels of the signals on the G pole of Q1 (i.e., the P1 G terminal) and the G pole of Q4 (i.e., the N2G terminal), or the G pole of Q2 (i.e., the P2G terminal) and the G pole of Q3 (i.e., the N3G terminal), the on-off of the connection between the power supply battery 7 and the excitation coil 1 is controlled, thereby controlling the on-off of the current in the excitation coil 1, and further generating an alternating magnetic field in the excitation coil 1. When the P1 G terminal and the N2G terminal are conducting (at this time, the P2G terminal and the N1 G terminal are cut off), the excitation current flows from the power supply battery 7 along the A direction through the excitation coil 1 and the sampling resistor 61; when the P2G terminal and the N1 G terminal are conducting (at this time, the P1 G terminal and the N2G terminal are cut off), the excitation current flows from the power supply battery 7 along the B direction through the excitation coil 1 and the sampling resistor 61. By adjusting the duty cycle of the pulse width modulation signal, the energization duration of the two switching elements in the integrated excitation switch module 5 within one cycle can be adjusted, thereby adjusting the excitation voltage and excitation current at both ends of the excitation coil 1.
[0049] Specifically, in this embodiment, the excitation control module 2 uses a single-chip microcomputer of model MSP430F5418A, the first PWM pulse width modulator 31 and the second PWM pulse width modulator 32 both use PWM control chips of model SG3525, and the first digital-to-analog converter 41 and the second digital-to-analog converter 42 both use digital-to-analog conversion chips of model DAC7724.
[0050] As Figure 2 shown, in one embodiment, the excitation voltage detection module 6 includes a sampling resistor 61. The sampling resistor 61 is connected in series with the excitation coil 1 between the two excitation drive terminals of the integrated excitation switch module 5. The excitation control module 2 has two signal input terminals. One end of the sampling resistor 61 is connected to one signal input terminal of the excitation control module 2, and the other end of the sampling resistor 61 is connected to the other signal input terminal of the excitation control module 2.
[0051] Since the voltage difference across the two ends of the excitation coil 1 determines the forward and reverse directions and magnitude of the excitation magnetic field generated by the excitation coil 1, and the voltage across the sampling resistor 61 depends on its own resistance value and the impedance of the excitation coil 1. Therefore, the excitation control module 2 can calculate the voltage across the two ends of the excitation coil 1 according to the ratio of the resistance value of the sampling resistor 61 to the impedance of the excitation coil 1 by collecting the voltage value across the two ends of the sampling resistor 61 in real time. Then, by controlling the first PWM pulse width modulator 31 and the second PWM pulse width modulator 32 in real time to change the duty cycle of the pulse width modulation signals output by each of them, the voltage value across the two ends of the excitation coil 1 is adjusted to a preset voltage difference value, so as to obtain the optimal excitation voltage value of the excitation coil 1 and ensure the lowest power loss of the entire excitation circuit.
[0052] In this embodiment, the sampling resistor 61 is a milliohm-level resistor. In this way, the sampling resistor 61 with a relatively small self-resistance value can be used to reduce the power consumption of the sampling resistor 61 itself, thereby reducing the loss of the entire excitation circuit.
[0053] As Figure 1 shown, in one embodiment, the low-power excitation circuit further includes an opto-isolation module 8. The signal input end of the opto-isolation module 8 is connected to the signal output end of the excitation voltage detection module 6, and the signal output end of the opto-isolation module 8 is connected to the signal input end of the excitation control module 2. The opto-isolation module 8 has a good isolation effect on the input and output electrical signals. Since the input and output of the opto-isolation module 8 are isolated from each other and the electrical signal transmission has characteristics such as unidirectionality, it has good electrical insulation ability and anti-interference ability, which is beneficial to further improving the accuracy of the sampling signal, thereby effectively improving the detection accuracy of the electromagnetic flowmeter.
[0054] As Figure 2 shown, in one embodiment, the opto-isolation module 8 includes a first opto-coupler 81 and a second opto-coupler 82. One end of the sampling resistor 61 is connected to a signal input end of the excitation control module 2 through the first opto-coupler 81, and the other end of the sampling resistor 61 is connected to another signal input end of the excitation control module 2 through the second opto-coupler 82.
[0055] The embodiment of the present application also provides an electromagnetic flowmeter, including the low-power excitation circuit in any of the above embodiments.
[0056] It should be noted that since the electromagnetic flowmeter includes the low-power excitation circuit in the above embodiment, the electromagnetic flowmeter has the same working principle and technical effects as the low-power excitation circuit in the above embodiment, which will not be elaborated here.
[0057] In the description of the present utility model, a large number of specific details are set forth. However, it will be understood that embodiments of the present utility model may be practiced without these specific details. In some instances, well-known methods, structures and technologies have not been shown in detail so as not to obscure the understanding of this description.
[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit them. Although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present utility model, and they should all be covered by the scope of the claims and the description of the present utility model.
Claims
1. A low-power excitation circuit, including an excitation coil provided on an electromagnetic flow sensor, characterized in that, It also includes an excitation control module, a PWM pulse width modulation module, a digital-to-analog conversion module, an integrated excitation switch module, an excitation voltage detection module, and a power supply battery. The signal output end of the PWM pulse width modulation module is connected to the signal input end of the digital-to-analog conversion module, and the signal output end of the digital-to-analog conversion module is connected to the signal input end of the integrated excitation switch module. The integrated excitation switch module has two excitation drive ends. The two excitation drive ends of the integrated excitation switch module are respectively connected to both ends of the excitation coil, and the power input end of the integrated excitation switch module is connected to the power supply battery. The signal input end of the excitation voltage detection module is connected to the excitation coil, the signal output end of the excitation voltage detection module is connected to the signal input / output end of the excitation control module, and the signal output end of the excitation control module is connected to the signal input end of the PWM pulse width modulation module. Among them, the PWM pulse width modulation module is used to output a digitally encoded pulse width modulation signal, the digital-to-analog conversion module is used to convert the pulse width modulation signal into an analog level signal, the integrated excitation switch module is used to control the excitation voltage at both ends of the excitation coil according to the analog level signal, the excitation voltage detection module is used to detect the excitation voltage value of the excitation coil, and the excitation control module is used to control the PWM pulse width modulation module to adjust the duty cycle of the pulse width modulation signal according to the excitation voltage value.
2. The low-power excitation circuit according to claim 1, wherein The integrated excitation switch module has two signal input ends, the excitation control module has two signal output ends, the PWM pulse width modulation module includes a first PWM pulse width modulator and a second PWM pulse width modulator, and the digital-to-analog conversion module includes a first digital-to-analog converter and a second digital-to-analog converter. Among them, One signal output end of the excitation control module, the first PWM pulse width modulator, the first digital-to-analog converter, and one signal input end of the integrated excitation switch module are connected in sequence. The other signal output end of the excitation control module, the second PWM pulse width modulator, the second digital-to-analog converter, and the other signal input end of the integrated excitation switch module are connected in sequence.
3. The low-power excitation circuit according to claim 2, wherein The integrated excitation switch module uses an integrated bridge chip with the model number ZXMHC3A01 N8.
4. The low-power excitation circuit according to claim 3, wherein The P1 S / P2S terminal of the integrated bridge chip is connected to the power supply battery, the P1 D / N1 D terminal and the P2D / N2D terminal are respectively connected to both ends of the excitation coil, the P1 G terminal and the N2G terminal are connected and then connected to the signal output end of the first digital-to-analog converter, the P2G terminal and the N1 G terminal are connected and then connected to the signal output end of the second digital-to-analog converter, and the N1 S / N2S terminal is grounded.
5. The low-power excitation circuit according to claim 2, characterized in that, The excitation control module uses a single-chip microcomputer with the model number MSP430F5418A, both the first PWM pulse width modulator and the second PWM pulse width modulator use PWM control chips with the model number SG3525, and both the first digital-to-analog converter and the second digital-to-analog converter use digital-to-analog conversion chips with the model number DAC7724.
6. The low-power excitation circuit according to any one of claims 1-5, characterized in that, The excitation voltage detection module includes a sampling resistor, which is connected in series with the excitation coil between two excitation driving ends of the integrated excitation switch module. The excitation control module has two signal input ends. One end of the sampling resistor is connected to one signal input end of the excitation control module, and the other end of the sampling resistor is connected to the other signal input end of the excitation control module.
7. The low-power excitation circuit according to claim 6, wherein It further includes an optocoupler isolation module. The signal input end of the optocoupler isolation module is connected to the signal output end of the excitation voltage detection module, and the signal output end of the optocoupler isolation module is connected to the signal input end of the excitation control module.
8. The low-power excitation circuit according to claim 7, wherein The optocoupler isolation module includes a first optocoupler and a second optocoupler. One end of the sampling resistor is connected to one signal input end of the excitation control module through the first optocoupler, and the other end of the sampling resistor is connected to the other signal input end of the excitation control module through the second optocoupler.
9. The low-power excitation circuit according to claim 6, wherein The sampling resistor uses a milliohm-level resistor.
10. An electromagnetic flowmeter, characterized in that, It includes the low-power excitation circuit according to any one of claims 1-9.