A data acquisition card and test device for electric water pump performance test

Abstract

The present invention discloses a data acquisition card and a test device for electric water pump performance test, comprising: an amplification and shaping interface circuit, whose input end is connected to a perforated current sensor signal, the perforated current sensor is configured to pass any phase line of the electric water pump through its perforation, the perforated current sensor collects the phase current frequency signal of the electric water pump, the amplification and shaping interface circuit converts the AC voltage signal output by the perforated current sensor into a square wave pulse signal with a stable amplitude; a microcontroller, whose ICAP input is connected to the amplification and shaping interface circuit signal to receive the square wave pulse signal, and the microcontroller calculates the mechanical speed of the electric water pump based on the square wave pulse signal. A board card is realized to integrate multiple data acquisition functions, the board card is small in size and easy to install, the floor space of the electric water pump performance test bench is greatly reduced, and the uploaded test data is accurate and reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of electric water pump testing, and in particular relates to a data acquisition card and a testing device for electric water pump performance testing. Background Art

[0002] An electric water pump is an electric device that uses electrical energy to pump liquid from a low place to a high place or transport liquid from one place to another. It is widely used in various fields, such as industry, agriculture, construction, and family life.

[0003] Electric water pumps, especially automotive electric water pumps, need to test the comprehensive performance of the water pumps, such as flow rate, pressure difference, efficiency, power, current and other parameters, in all stages of R&D and production. However, the complete sets of equipment in the prior art are often based on commonly used components in the automation industry, such as NI data acquisition cards and industrial computers, and are integrated and designed, occupying a large area and being expensive. Since the complete sets of fully automatic testing equipment for water pump performance in the prior art are expensive and take up a lot of space, they are not suitable for popular use in R&D and production. In reality, manual recording and data sorting are often used, which is inefficient and prone to errors. Summary of the invention

[0004] To solve the above problems, the purpose of the present invention is to provide a data acquisition card and a test device for electric water pump performance testing. A board integrates multiple data acquisition functions, and the board is small in size for easy installation, which greatly reduces the footprint of the electric water pump performance test bench; and the entire board components are conventional materials. Compared with the NI standard data acquisition card, the cost is greatly reduced. Since one-button start-up of fully automatic testing and data acquisition is realized, work efficiency is greatly improved, the workload of relevant personnel is reduced, and compared with manual data recording, the uploaded test data is accurate and reliable.

[0005] To achieve the above object, the technical solution of the present invention is: a data acquisition card for electric water pump performance testing, comprising: an amplifying and shaping interface circuit, wherein an input end of the amplifying and shaping interface circuit is connected to a perforated current sensor signal, wherein the perforated current sensor is configured to pass any phase line of the electric water pump through its perforation, wherein the perforated current sensor collects a phase current frequency signal of the electric water pump, and wherein the amplifying and shaping interface circuit converts the AC voltage signal output by the perforated current sensor into a square wave pulse signal with a stable amplitude; A microcontroller, whose ICAP input is connected to the amplifying and shaping interface circuit signal to receive the square wave pulse signal, and the microcontroller calculates the mechanical rotation speed of the electric water pump based on the square wave pulse signal.

[0006] Preferably, the amplification and shaping interface circuit includes a clamping circuit, an amplification circuit, and a hysteresis comparator circuit connected in sequence, the clamping circuit is connected to the output end of the perforated current sensor to convert the sinusoidal wave voltage signal output by the perforated current sensor into a half-wave voltage signal, the amplification circuit amplifies the half-wave voltage signal, and the hysteresis comparator circuit shapes the amplified half-wave voltage signal into a square wave signal to send to the microcontroller.

[0007] Preferably, the amplifying and shaping interface circuit also includes a low-pass filtering circuit, the input of the low-pass filtering circuit is connected to the output of the amplifying circuit, the output of the low-pass filtering circuit is connected to the input of the hysteresis comparator circuit, the low-pass filtering circuit includes a tenth resistor and a sixth capacitor connected in series, the first end of the sixth capacitor is connected to the input of the hysteresis comparator circuit, and the second end of the sixth capacitor is grounded.

[0008] Preferably, the hysteresis comparator circuit includes a comparator, an eighth resistor, a ninth resistor and a VREF power supply, the non-inverting input of the comparator is connected to the VREF power supply through the eighth resistor, the non-inverting input of the comparator is also connected to the output of the comparator through the ninth resistor, the inverting input of the comparator is connected to the output of the amplifier circuit, and the output of the comparator is connected to the ICAP input of the microcontroller.

[0009] Preferably, the data acquisition card also includes a 4~20mA interface circuit, which includes a clamp protection circuit, a single op amp and a low-pass filter circuit. The input end of the clamp protection circuit is connected to the flow meter or differential pressure meter signal and converts the received current signal into a voltage signal. The output end of the clamp protection circuit is connected to the in-phase input end of the single op amp, the inverting input end of the single op amp is connected to the output end of the single op amp, the output end of the single op amp is connected to the low-pass filter circuit, and the low-pass filter circuit is connected to the ADC input end of the microcontroller.

[0010] Preferably, the data acquisition card also includes a CAN communication interface, the microcontroller is connected to the host computer via the CAN communication interface, the data acquisition card receives a CAN message instruction for starting the test sent by the host computer via the CAN communication interface, and after the test is completed, the data acquisition card sends all test data under different working conditions to the host computer.

[0011] Preferably, the CAN communication interface is also used to connect to an electric two-way valve installed on a water pump performance test bench. After starting the test, the data acquisition card automatically controls the electric two-way valve to rotate to different opening positions through the CAN bus, and completes corresponding data acquisition at each opening position.

[0012] Preferably, the data acquisition card also includes an RS-232 interface, through which the program-controlled power supply is connected, and is used to set the output voltage of the program-controlled power supply and read the actual input voltage and input current of the electric water pump.

[0013] Preferably, the formula for the microcontroller to calculate the mechanical speed of the electric water pump based on the square wave pulse signal is: RPM = fo * 60 / p, where fo represents the electrical frequency at which the electric water pump currently operates, and p represents the number of rotor pole pairs of the three-phase BLDC motor inside the electric water pump.

[0014] Based on the same concept, the present invention also provides a testing device, comprising any one of the above-mentioned data acquisition cards for electric water pump performance testing.

[0015] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: The technical solution of the present invention only uses the current frequency signal collected by the perforated current sensor and then converts it into a square wave pulse signal, so as to obtain the current frequency of the water pump motor, and then calculates the actual mechanical speed of the electric water pump in combination with the number of rotor poles of the water pump motor. The data acquisition card of this embodiment is small in size and easy to install, which greatly reduces the footprint of the electric water pump performance test bench. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of a data acquisition card used for electric water pump performance testing; Figure 2 This is a schematic diagram of the 4-20mA interface circuit; Figure 3 It is an amplifying and shaping interface circuit. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0018] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0019] See also Figure 1The technical solution of this embodiment is: a data acquisition card for electric water pump performance testing, comprising: an amplifying and shaping interface circuit, wherein an input end of the amplifying and shaping interface circuit is connected to a perforated current sensor signal, wherein the perforated current sensor is configured to pass any phase line of the electric water pump through its perforation, wherein the perforated current sensor collects a phase current frequency signal of the electric water pump, and wherein the amplifying and shaping interface circuit converts the AC voltage signal output by the perforated current sensor into a square wave pulse signal with a stable amplitude; A microcontroller, whose ICAP input is connected to the amplifying and shaping interface circuit signal to receive the square wave pulse signal, and the microcontroller calculates the mechanical rotation speed of the electric water pump based on the square wave pulse signal.

[0020] In actual testing, the electrical frequency of the electric water pump is consistent with the phase current frequency of the water pump motor. Any phase line of the electric water pump is passed through the central small hole of the perforated current sensor, corresponding to the AC change of the phase current. The output signal of the perforated current sensor varies from -5V to 5V. The perforated current sensor is actually only used to collect the phase current frequency signal. Since the load of the electric water pump is different under each test condition, the phase current is not fixed, so the output signal of the sensor is an AC voltage signal with an amplitude varying from -5V to 5V. The technical solution of this embodiment only uses the current frequency signal collected by the perforated current sensor and then converts it into a square wave pulse signal, so that the current frequency of the water pump motor can be obtained, and then combined with the number of pole pairs of the water pump motor rotor to calculate the actual mechanical speed of the electric water pump. The data acquisition card of this embodiment is small in size and easy to install, which greatly reduces the floor space of the electric water pump performance test bench.

[0021] Preferably, see Figure 1 and Figure 3 The amplification and shaping interface circuit includes a clamping circuit, an amplification circuit, and a hysteresis comparator circuit connected in sequence. The clamping circuit is connected to the output end of the perforated current sensor to convert the sinusoidal wave voltage signal output by the perforated current sensor into a half-wave voltage signal. The amplification circuit amplifies the half-wave voltage signal. The hysteresis comparator circuit shapes the amplified half-wave voltage signal into a square wave signal to send to the microcontroller.

[0022] Since the output signal of the through-hole current sensor is an AC voltage signal with a variable amplitude, the amplifying and shaping interface circuit of this embodiment converts the AC voltage signal into a square wave pulse signal with a stable amplitude that can be read by the microcontroller. Figure 3TP1 is the output signal of the perforated current sensor, which corresponds to the sampled current. If the pump motor is driven by a sine wave, the waveform at TP1 is an AC sinusoidal voltage signal of -5V~5V, and the amplitude of the sinusoidal voltage signal is related to the magnitude of the motor phase current. After the current limiting of the fifth resistor R5 in the clamping circuit and the clamping of the fifth diode D5 and the sixth diode D6, the sinusoidal AC voltage signal presents a half-wave voltage waveform at TP2 with a positive peak value not exceeding 4.5V and a negative peak voltage not less than -0.7V; the amplifier circuit composed of the amplifier U3.2, the seventh resistor R7, and the sixth resistor R6 amplifies the half-wave voltage signal at TP2. The purpose is that when the pump is working, even if the phase current amplitude is very low, as long as the current sensor output voltage amplitude is above 300mV, it can ensure that there is enough voltage amplitude after amplification to input to the next comparator circuit for waveform shaping.

[0023] Preferably, the amplifying and shaping interface circuit also includes a low-pass filtering circuit, the input of the low-pass filtering circuit is connected to the output of the amplifying circuit, the output of the low-pass filtering circuit is connected to the input of the hysteresis comparator circuit, the low-pass filtering circuit includes a tenth resistor and a sixth capacitor connected in series, the first end of the sixth capacitor is connected to the input of the hysteresis comparator circuit, and the second end of the sixth capacitor is grounded.

[0024] See also Figure 3 Since the phase current frequency of the electric water pump is usually less than 500 Hz, in this embodiment, the tenth resistor R10 and the sixth capacitor C6 form a low-pass filter with a cut-off frequency of about 1.5 KHz, which is used to filter out the high-frequency signal on the waveform after the previous stage amplification.

[0025] Preferably, the hysteresis comparator circuit includes a comparator, an eighth resistor, a ninth resistor and a VREF power supply, the non-inverting input of the comparator is connected to the VREF power supply through the eighth resistor, the non-inverting input of the comparator is also connected to the output of the comparator through the ninth resistor, the inverting input of the comparator is connected to the output of the amplifier circuit, and the output of the comparator is connected to the ICAP input of the microcontroller.

[0026] Continue to see Figure 3, comparator U3.1, the eighth resistor R8, and the ninth resistor R9 constitute a hysteresis comparator circuit. When the VDD power supply is 5V and the VREF power supply is 2.5V, the window voltage of the hysteresis comparator circuit is about 1V. The hysteresis comparator circuit can further suppress the small disturbances superimposed on the low-frequency input signal at TP3, so that the output waveform of the hysteresis comparator circuit is more stable, and the output will not be frequently flipped due to these small disturbances; after shaping, a stable square wave signal with an amplitude of VDD is obtained. The frequency of the square wave signal is consistent with the phase current frequency of the electric water pump. The current operating electrical frequency of the electric water pump can be calculated by connecting to the ICAP input capture of the microcontroller.

[0027] Preferably, see Figure 1 and Figure 2 The data acquisition card also includes a 4~20mA interface circuit, which includes a clamp protection circuit, a single op amp and a low-pass filter circuit. The input end of the clamp protection circuit is connected to the flow meter or differential pressure meter signal and converts the received current signal into a voltage signal. The output end of the clamp protection circuit is connected to the in-phase input end of the single op amp, the inverting input end of the single op amp is connected to the output end of the single op amp, the output end of the single op amp is connected to the low-pass filter circuit, and the low-pass filter circuit is connected to the ADC input end of the microcontroller.

[0028] The signal of flow meter or differential pressure meter is 4-20mA, see Figure 2 The 4~20mA interface circuit of this embodiment is connected in series with a flow meter or a differential pressure meter to convert a current signal into a voltage signal; a first resistor R1, a first diode D1, and a second diode D2 form a clamping protection circuit to prevent a high common-mode input voltage from damaging the input port of the single op amp U1; the single op amp U1 is powered by a single power supply VDD and is used as a buffer between the microcontroller and the external interface; the second resistor R2 and the second capacitor C2 form a low-pass filter with a cutoff frequency of about 5Hz to filter out the power frequency interference signal at the test site; the filtered signal is input to the analog sampling port of the microcontroller.

[0029] Preferably, the data acquisition card also includes a CAN communication interface, the microcontroller is connected to the host computer via the CAN communication interface, the data acquisition card receives a CAN message instruction for starting the test sent by the host computer via the CAN communication interface, and after the test is completed, the data acquisition card sends all test data under different working conditions to the host computer.

[0030] The data acquisition card of the technical solution of this embodiment is connected to the host computer through the CAN bus. The host computer sends a CAN message instruction to the data acquisition card to start the test. After the test is completed, the data acquisition card feeds back all test data under different working conditions to the host computer. The host computer generates the electric water pump performance curve and corresponding reports based on the fed-back message data.

[0031] Preferably, the CAN communication interface is also used to connect to an electric two-way valve installed on a water pump performance test bench. After starting the test, the data acquisition card automatically controls the electric two-way valve to rotate to different opening positions through the CAN bus, and completes corresponding data acquisition at each opening position.

[0032] Since the water pump performance needs to be tested under different flow conditions, the CAN communication interface of the data acquisition card is connected to the host computer as well as to the electric two-way valve installed on the water pump performance test bench. After starting the test, the data acquisition card automatically controls the electric two-way valve to rotate to different opening positions through the CAN bus, and completes corresponding data collection at each opening position, realizing a one-button test function.

[0033] Preferably, the data acquisition card also includes an RS-232 interface, through which the program-controlled power supply is connected, and is used to set the output voltage of the program-controlled power supply and read the actual input voltage and input current of the electric water pump.

[0034] It should be noted that other power conversion units are used to reduce the external 12V or 24V power supply to 5V or 3.3V required by the circuit inside the board; the CAN communication interface and RS-232 interface are both common interface circuits in the prior art, and the specific circuits are not repeated. The power supply of the electric water pump comes from the external programmable power supply. The data acquisition card is connected to the communication interface of the programmable power supply through the RS-232 interface, which is used to adjust the test voltage, set the output current and power limit, and read the input voltage and input current values ​​under the current test conditions.

[0035] Preferably, the formula for the microcontroller to calculate the mechanical speed of the electric water pump based on the square wave pulse signal is: RPM = fo * 60 / p, where fo represents the electrical frequency at which the electric water pump currently operates, and p represents the number of rotor pole pairs of the three-phase BLDC motor inside the electric water pump.

[0036] Since the frequency of the AC voltage signal is consistent with the rotational frequency fo of the three-phase BLDC motor inside the electric water pump, the mechanical speed of the electric water pump can be simply calculated based on the above formula: The data acquisition card used in the present invention integrates multiple data acquisition functions on one board, and the board is small in size and easy to install, which greatly reduces the floor space of the electric water pump performance test bench; and the entire board components are conventional materials, and the cost is greatly reduced compared with the NI standard data acquisition card. Since the one-button start of full-automatic testing and data acquisition is realized, the work efficiency is greatly improved, the workload of relevant personnel is reduced, and compared with manual data recording, the uploaded test data is accurate and reliable.

[0037] Based on the same concept, the present invention also provides a testing device, comprising any one of the above-mentioned data acquisition cards for electric water pump performance testing.

[0038] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A data acquisition card for electric water pump performance testing, characterized in that: include: an amplifying and shaping interface circuit, wherein an input end of the amplifying and shaping interface circuit is connected to a perforated current sensor signal, wherein the perforated current sensor is configured to pass any phase line of the electric water pump through its perforation, wherein the perforated current sensor collects a phase current frequency signal of the electric water pump, and wherein the amplifying and shaping interface circuit converts the AC voltage signal output by the perforated current sensor into a square wave pulse signal with a stable amplitude; A microcontroller, whose ICAP input is connected to the amplifying and shaping interface circuit signal to receive the square wave pulse signal, and the microcontroller calculates the mechanical rotation speed of the electric water pump based on the square wave pulse signal.

2. The data acquisition card for electric water pump performance testing according to claim 1, characterized in that: The amplification and shaping interface circuit includes a clamping circuit, an amplification circuit, and a hysteresis comparator circuit connected in sequence. The clamping circuit is connected to the output end of the perforated current sensor to convert the sinusoidal wave voltage signal output by the perforated current sensor into a half-wave voltage signal. The amplification circuit amplifies the half-wave voltage signal. The hysteresis comparator circuit shapes the amplified half-wave voltage signal into a square wave signal to send to the microcontroller.

3. The data acquisition card for electric water pump performance testing according to claim 2, characterized in that: The amplifying and shaping interface circuit also includes a low-pass filtering circuit, the input of the low-pass filtering circuit is connected to the output of the amplifying circuit, the output of the low-pass filtering circuit is connected to the input of the hysteresis comparator circuit, the low-pass filtering circuit includes a tenth resistor and a sixth capacitor connected in series, the first end of the sixth capacitor is connected to the input of the hysteresis comparator circuit, and the second end of the sixth capacitor is grounded.

4. The data acquisition card for electric water pump performance testing according to claim 2, characterized in that: The hysteresis comparator circuit includes a comparator, an eighth resistor, a ninth resistor and a VREF power supply, wherein the non-inverting input of the comparator is connected to the VREF power supply through the eighth resistor, the non-inverting input of the comparator is also connected to the output of the comparator through the ninth resistor, the inverting input of the comparator is connected to the output of the amplifier circuit, and the output of the comparator is connected to the ICAP input of the microcontroller.

5. The data acquisition card for electric water pump performance testing according to claim 1, characterized in that: The data acquisition card also includes a 4~20mA interface circuit, which includes a clamp protection circuit, a single op amp and a low-pass filter circuit. The input end of the clamp protection circuit is connected to the flow meter or differential pressure meter signal and converts the received current signal into a voltage signal. The output end of the clamp protection circuit is connected to the in-phase input end of the single op amp, the inverting input end of the single op amp is connected to the output end of the single op amp, the output end of the single op amp is connected to the low-pass filter circuit, and the low-pass filter circuit is connected to the ADC input end of the microcontroller.

6. The data acquisition card for electric water pump performance testing according to claim 1, characterized in that: The data acquisition card also includes a CAN communication interface, the microcontroller is connected to the host computer via the CAN communication interface, the data acquisition card receives a CAN message instruction for starting a test sent by the host computer via the CAN communication interface, and after the test is completed, the data acquisition card sends all test data under different working conditions to the host computer.

7. The data acquisition card for electric water pump performance testing according to claim 6, characterized in that: The CAN communication interface is also used to connect to the electric two-way valve installed on the water pump performance test bench. After starting the test, the data acquisition card automatically controls the electric two-way valve to rotate to different opening positions through the CAN bus, and completes corresponding data acquisition at each opening position.

8. The data acquisition card for electric water pump performance testing according to claim 1, characterized in that: The data acquisition card also includes an RS-232 interface, through which the program-controlled power supply is connected, and is used to set the output voltage of the program-controlled power supply and read the actual input voltage and input current of the electric water pump.

9. The data acquisition card for electric water pump performance testing according to claim 1, characterized in that: The formula for the microcontroller to calculate the mechanical speed of the electric water pump based on the square wave pulse signal is: RPM = fo * 60 / p, where fo represents the current operating electrical frequency of the electric water pump, and p represents the number of rotor pole pairs of the three-phase BLDC motor inside the electric water pump.

10. A testing device, characterized in that: A data acquisition card for electric water pump performance testing comprising any one of claims 1 to 9.

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