CN203881815U - Simple high-precision DC electronic load - Google Patents
Simple high-precision DC electronic load Download PDFInfo
- Publication number
- CN203881815U CN203881815U CN201420269818.9U CN201420269818U CN203881815U CN 203881815 U CN203881815 U CN 203881815U CN 201420269818 U CN201420269818 U CN 201420269818U CN 203881815 U CN203881815 U CN 203881815U
- Authority
- CN
- China
- Prior art keywords
- circuit
- voltage
- precision
- microprocessor
- output
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Abstract
The utility model discloses a simple high-precision DC electronic load, which comprises a microprocessor, an analog voltage output circuit, a power MOSFET load circuit, a voltage and current detection circuit, a power supply circuit and a man-machine interface circuit, wherein an input end and an output end of the analog voltage output circuit are respectively connected with the microprocessor and the power MOSFET load circuit; an input end and an output end of the power MOSFET load circuit are respectively connected with the analog voltage output circuit and an detected object; an input end and an output end of the voltage and current detection circuit are respectively connected with the detected object and the microprocessor; an output end of the power circuit is connected with the microprocessor; and an input/output end of the man-machine interface circuit is connected with the microprocessor. The simple high-precision DC electronic load is stable in operation, fast in control speed and high in precision, can effectively realize the digital control of the load current, and has the advantages of high precision, wide measuring range, high load adaptability, stable performance, simple operation, low cost and the like when compared with the commonly-used software closed-loop scheme.
Description
Technical field
The utility model relates to a kind of simple high-precision DC Electronic Loads.
Background technology
In the debugging of Switching Power Supply detects, need to the dynamic operation performance under bringing onto load condition test tested power supply, dynamically change load and make it in determining current working mode, this just requires to be necessary for test macro a kind of DC Electronic Loads that can change real-time dynamicly working current is provided.
Utility model content
The purpose of this utility model is to provide a kind of stable, control rate is fast, precision is high simple high-precision DC Electronic Loads, realizes the Digital Control of load current.
The technical scheme that realizes the utility model object is: a kind of simple high-precision DC Electronic Loads, comprises microprocessor, analog voltage output circuit, power MOSFET load circuit, voltage and current detection circuit, power circuit and man-machine interface circuit; The input end of described analog voltage output circuit and output terminal connect respectively microprocessor and power MOSFET load circuit; The input end of described power MOSFET load circuit and output terminal connect respectively analog voltage output circuit and measurand; The input end of described voltage and current detection circuit and output terminal connect respectively measurand and microprocessor; The output termination microprocessor of described power circuit; The input and output termination microprocessor of described man-machine interface circuit.
Described microprocessor adopts MSP430F149 chip.
Described power MOSFET load circuit comprises power termination module and N channel enhancement power field effect pipe IRF730; The output terminal of described power termination module is connected to the grid of N channel enhancement power field effect pipe IRF730.
The power termination module of described power MOSFET load circuit comprises D/A change-over circuit and level translation and comparator circuit; The output terminal of described D/A change-over circuit is connected to the input end of level translation and comparator circuit, the output termination N channel enhancement power field effect pipe IRF730 of level translation and comparator circuit; Described D/A change-over circuit comprises digital to analog converter DAC904; The outside reference of described DAC904 adopts REF5025; The output level of described D/A change-over circuit is-1.0～1.0V; Described level translation comprises with comparator circuit totalizer and the phase inverter being connected successively; Described totalizer and phase inverter are promoted to 0～2V by the output level of D/A change-over circuit.
Described voltage and current detection circuit comprises A/D change-over circuit, current sampling circuit and voltage sampling circuit; Described A/D change-over circuit comprises A/D conversion chip ADS1112; The serial line interface of described A/D conversion chip ADS1112 is connected to the peripheral hardware SPI interface of MSP430F149; Described current sampling circuit comprises sampling resistor; The voltage signal that described sampling resistor obtains directly accesses the passage 0 of A/D conversion chip ADS1112; Described voltage sampling circuit comprises voltage divider; The passage 1 of the voltage signal access A/D conversion chip ADS1112 that described voltage divider obtains.
Adopted technique scheme, the utlity model has following beneficial effect: (1) the utility model is simple in structure, test result shows that the utility model is stable, control rate is fast, precision is high, can effectively realize the Digital Control of load current, compare with conventional software closed loop policy, have that precision is high, broad quantum, workload-adaptability be strong, stable performance, the advantage such as easy and simple to handle, with low cost.
(2) microprocessor of the present utility model adopts MSP430F149 chip, MSP430F149 chip is the super low-power consumption microprocessor that American TI Company is released, execution speed is fast, supply voltage is low, operating voltage range is wide, there is clock system, powerful interrupt function, good Universal and scalability flexibly, be suitable for industrial environment.
(3) that in power MOSFET load circuit of the present utility model, use is N channel enhancement power field effect pipe IRF730, and maximum can withstand voltage 400V, and under normal temperature, maximum operating currenbt is 5.5A.
(4) in D/A change-over circuit of the present utility model, select the digital to analog converter DAC904 of 14, it has conversion accuracy height and fireballing advantage.
(5) that in A/D change-over circuit of the present utility model, use is special A/D conversion chip ADS1112, and it is the gradual approaching A/D converter of 16 of a kind of multiranges, low-power consumption, and precision is higher, and switching rate is very fast, and reliability is high.
Accompanying drawing explanation
For content of the present utility model is more easily expressly understood, according to specific embodiment also by reference to the accompanying drawings, the utility model is described in further detail, wherein below
Fig. 1 is structured flowchart of the present utility model.
Fig. 2 is the circuit diagram of the digital to analog converter DAC904 in power MOSFET load circuit of the present utility model.
Fig. 3 is level translation in power MOSFET load circuit of the present utility model and the circuit diagram of comparator circuit.
Fig. 4 is the circuit diagram of voltage and current detection circuit of the present utility model.
The bent composes curve of 83.6～322.9mA section sampled value-electric current when Fig. 5 is the utility model measurement.
Label in accompanying drawing is:
Microprocessor 1, analog voltage output circuit 2, power MOSFET load circuit 3, voltage and current detection circuit 4, power circuit 5, man-machine interface circuit 6, measurand 7.
Embodiment
(embodiment 1)
See Fig. 1, the simple high-precision DC Electronic Loads of the present embodiment, comprises microprocessor 1, analog voltage output circuit 2, power MOSFET load circuit 3, voltage and current detection circuit 4, power circuit 5 and man-machine interface circuit 6.
The input end of analog voltage output circuit 2 and output terminal connect respectively microprocessor 1 and power MOSFET load circuit 3.The input end of power MOSFET load circuit 3 and output terminal connect respectively analog voltage output circuit 2 and measurand 7.The input end of voltage and current detection circuit 4 and output terminal connect respectively measurand 7 and microprocessor 1.The output termination microprocessor 1 of power circuit 5.The input and output termination microprocessor 1 of man-machine interface circuit 6.Microprocessor 1 adopts MSP430F149 chip.
Power MOSFET load circuit 3 comprises power termination module and N channel enhancement power field effect pipe IRF730.The output terminal of power termination module is connected to the grid of N channel enhancement power field effect pipe IRF730.The power termination module of power MOSFET load circuit 3 comprises D/A change-over circuit and level translation and comparator circuit.The output terminal of D/A change-over circuit is connected to the input end of level translation and comparator circuit, the output termination N channel enhancement power field effect pipe IRF730 of level translation and comparator circuit.D/A change-over circuit comprises digital to analog converter DAC904.The circuit diagram of digital to analog converter DAC904 as shown in Figure 2.The outside reference of DAC904 adopts REF5025.The output level of D/A change-over circuit is-1.0～1.0V.The circuit diagram of level translation and comparator circuit as shown in Figure 3.Level translation comprises with comparator circuit totalizer and the phase inverter being connected successively.Totalizer and phase inverter are promoted to 0～2V by the output level of D/A change-over circuit.
As shown in Figure 4, voltage and current detection circuit 4 comprises A/D change-over circuit, current sampling circuit and voltage sampling circuit to the circuit diagram of voltage and current detection circuit 4.A/D change-over circuit comprises A/D conversion chip ADS1112.The serial line interface of A/D conversion chip ADS1112 is connected to the peripheral hardware SPI interface of MSP430F149.Current sampling circuit comprises sampling resistor.The voltage signal that sampling resistor obtains directly accesses the passage 0 of A/D conversion chip ADS1112.Voltage sampling circuit comprises voltage divider.The passage 1 of the voltage signal access A/D conversion chip ADS1112 that voltage divider obtains.
The method of the simple high-precision DC Electronic Loads matching sampled value-current curve of the present embodiment is:
With MSP430F149, driving D/A change-over circuit power ratio control to load on to set under electric current works, drives A/D change-over circuit to obtain sampled data simultaneously.Under same electric current, continuous sampling is 10 times, obtains sampled result as one group of data recording.Measured after raw data, again surveyed data are carried out to digital filtering processing, maximal value in 10 data of each sampled point and minimum value are rejected, then got the mean value of 8 remaining data as the final sampled value of this this electric current, thereby obtain one group of data.The partial data that table 1 is 83.6～322.9mA section of measuring.
The partial data of table 1:83.6～322.9mA section
| Actual current (mA) | 83.6 | 94.7 | 105.7 | 117.1 | 127.9 | 201.0 | 220.8 | 251.6 | 312.7 | 322.9 |
| Sampled value (bit) | 1490 | 1680 | 1870 | 2065 | 2251 | 3509 | 3850 | 4380 | 5431 | 5605 |
For approaching to reality curve more, in processing, whole current/voltage scope has been adopted the method for polynomial fitting curve.The polynomial expression of institute's matching is: y=a
0+ a
1x
1+ ... a
mx
m, a in formula
0, a
1, a
2, a
mfor coefficient to be asked.Because sampled value and actual current are once linear relationship, so Data processing adopts an order polynomial to carry out matching sampled value-current relationship curve.According to the data fitting function of 83.6～322.9mA section, be y=0.5813x-29.393, its corresponding matched curve as shown in Figure 4.
The method of the simple high-precision DC Electronic Loads matching sampled value-voltage curve of the present embodiment is:
Voltage curve approximating method and current methods are basically identical, but due under different operating electric current, the pressure drop producing in line impedance, sampling resistor and field effect transistor is different, therefore in order to obtain more accurate magnitude of voltage, need to carry out piecewise fitting to different working currents.
First when electric current input value is 0A, read sampled value and actual voltage value, the rest may be inferred, respectively electric current increased progressively to relation with 100mA and draw sampled value and actual voltage value.Table 2 is the part sampled data under different electric currents.
Table 2: the part sampled data under different electric currents
Adopt the method for polynomial fitting curve successively different electric currents to be carried out to piecewise fitting, fitting result is as shown in table 3.From table 3, in the situation of different electric currents, the slope of sampled value and voltage matched curve is basically identical, but because PCB layout impedance is under different operating current conditions, on line, pressure drop produces irregular variation, thereby affect intercept, changes also irregular.Therefore,, in order to obtain the measurement result of degree of precision, program adopts different fit equation according to different operating electric current.
Table 3: the voltage fitting data of different electric currents
| Electric current mA | 0 | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 |
| Slope | 0.6847 | 0.6847 | 0.6847 | 0.6847 | 0.6843 | 0.6846 | 0.6847 | 0.6846 | 0.6846 | 0.6848 |
| Intercept | -34.05 | -32.81 | -31.88 | -30.33 | -30.09 | -31.28 | -30.18 | -28.67 | -29.44 | -26.51 |
The method of the output current of the simple high-precision DC Electronic Loads of control the present embodiment is:
The load current sampling resistor R11 that flows through in the circuit of the simple high-precision DC Electronic Loads of the present embodiment, produces sampled voltage, be input to the reverse input end of operational amplifier OP07, and the analog voltage of D/A outputs to the input end in the same way of OP07.When D/A input is greater than reverse input, OP07 output+12V, now CMOS pipe conducting, on the contrary turn-off.Due to turn-off and conducting speed very fast, formed direct FEEDBACK CONTROL, therefore export, present linearity.Thereby can with the output of D/A, control the voltage of sampling resistor, reach the object of controlling output current.Therefore can make a constant current closed loop controller being connected successively by PI controller, D/A converter, power termination and sampling resistor.
Measuring accuracy and the error analysis of the simple high-precision DC Electronic Loads of the present embodiment are:
Under constant current (CC) mode of operation, different current values are set, measure actual current value.According to precision=(settings-measured value)/settings are set, system arranges precision and is less than 9/1000ths; Under constant current (CC) mode of operation, fixed current value is set, while changing load both end voltage 10V, test changes the current value of front and back respectively.According to current changing rate=(current value-variation after-current value before changing)/current value before changing, system power rate of change is less than 9/1000ths; Manually input current value, by closed-loop control, changes the output of D/A, to reach the control of manual electric current input and constant current source working current, completes the measurement of current precision, and test result is as shown in table 4.According to current measurement precision=(actual measurement current value-measured value)/actual measurement current value, measurement result shows, system power measuring accuracy is better than 5/10000ths.
Table 4: partial test result
| Input current value (mA) | Measured current value (mA) | Current measurement precision % |
| 200 | 200.1 | 0.05 |
| 400 | 400.0 | 0 |
| 800 | 800.1 | 0.01 |
Although test result shows to meet needed requirement, also there are some errors, cause the main cause of error to have: 1. the resistance of metalfilmresistor is accurate not; 2. the error that sampling resistor self-heating effect causes, because resistance resistance when temperature rises can change, therefore can cause temperature drift, brings the error of measurement to system; 3. A/D, D/A transformed error is subject to the restriction of A/D converter precision and reference source degree of stability, inevitably brings certain error, for more accurate output constant current power supply, must select more A/D, the D/A chip of long number; 4. the stochastic error or the gross error that because of extraneous bursty interference or instrument displayed value etc., cause.
Above-described specific embodiment; the purpose of this utility model, technical scheme and beneficial effect are further described; institute is understood that; the foregoing is only specific embodiment of the utility model; be not limited to the utility model; all within spirit of the present utility model and principle, any modification of making, be equal to replacement, improvement etc., within all should being included in protection domain of the present utility model.
Claims (5)
1. a simple high-precision DC Electronic Loads, is characterized in that: comprise microprocessor (1), analog voltage output circuit (2), power MOSFET load circuit (3), voltage and current detection circuit (4), power circuit (5) and man-machine interface circuit (6); The input end of described analog voltage output circuit (2) and output terminal connect respectively microprocessor (1) and power MOSFET load circuit (3); The input end of described power MOSFET load circuit (3) and output terminal connect respectively analog voltage output circuit (2) and measurand (7); The input end of described voltage and current detection circuit (4) and output terminal connect respectively measurand (7) and microprocessor (1); The output termination microprocessor (1) of described power circuit (5); The input and output termination microprocessor (1) of described man-machine interface circuit (6).
2. a kind of simple high-precision DC Electronic Loads according to claim 1, is characterized in that: described microprocessor (1) adopts MSP430F149 chip.
3. a kind of simple high-precision DC Electronic Loads according to claim 1, is characterized in that: described power MOSFET load circuit (3) comprises power termination module and N channel enhancement power field effect pipe IRF730; The output terminal of described power termination module is connected to the grid of N channel enhancement power field effect pipe IRF730.
4. a kind of simple high-precision DC Electronic Loads according to claim 3, is characterized in that: the power termination module of described power MOSFET load circuit (3) comprises D/A change-over circuit and level translation and comparator circuit; The output terminal of described D/A change-over circuit is connected to the input end of level translation and comparator circuit, the output termination N channel enhancement power field effect pipe IRF730 of level translation and comparator circuit; Described D/A change-over circuit comprises digital to analog converter DAC904; The outside reference of described DAC904 adopts REF5025; The output level of described D/A change-over circuit is-1.0～1.0V; Described level translation comprises with comparator circuit totalizer and the phase inverter being connected successively; Described totalizer and phase inverter are promoted to 0～2V by the output level of D/A change-over circuit.
5. a kind of simple high-precision DC Electronic Loads according to claim 2, is characterized in that: described voltage and current detection circuit (4) comprises A/D change-over circuit, current sampling circuit and voltage sampling circuit; Described A/D change-over circuit comprises A/D conversion chip ADS1112; The serial line interface of described A/D conversion chip ADS1112 is connected to the peripheral hardware SPI interface of MSP430F149; Described current sampling circuit comprises sampling resistor; The voltage signal that described sampling resistor obtains directly accesses the passage 0 of A/D conversion chip ADS1112; Described voltage sampling circuit comprises voltage divider; The passage 1 of the voltage signal access A/D conversion chip ADS1112 that described voltage divider obtains.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420269818.9U CN203881815U (en) | 2014-05-23 | 2014-05-23 | Simple high-precision DC electronic load |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420269818.9U CN203881815U (en) | 2014-05-23 | 2014-05-23 | Simple high-precision DC electronic load |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203881815U true CN203881815U (en) | 2014-10-15 |
Family
ID=51682300
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420269818.9U Expired - Fee Related CN203881815U (en) | 2014-05-23 | 2014-05-23 | Simple high-precision DC electronic load |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203881815U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110707668A (en) * | 2019-10-12 | 2020-01-17 | 法泰电器（江苏）股份有限公司 | Overcurrent detection and on-off control method of solid-state circuit breaker |
| CN111077936A (en) * | 2019-12-30 | 2020-04-28 | 南京广慈医疗科技有限公司 | Programmable self-calibration positive voltage constant power output circuit and method |
| CN111124030A (en) * | 2019-12-30 | 2020-05-08 | 南京广慈医疗科技有限公司 | Programmable self-calibration negative voltage constant power output circuit and method |
| CN111273208A (en) * | 2020-03-11 | 2020-06-12 | 深圳市金锐显数码科技有限公司 | Precision automatic correction method and system based on electronic load |
-
2014
- 2014-05-23 CN CN201420269818.9U patent/CN203881815U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110707668A (en) * | 2019-10-12 | 2020-01-17 | 法泰电器（江苏）股份有限公司 | Overcurrent detection and on-off control method of solid-state circuit breaker |
| CN111077936A (en) * | 2019-12-30 | 2020-04-28 | 南京广慈医疗科技有限公司 | Programmable self-calibration positive voltage constant power output circuit and method |
| CN111124030A (en) * | 2019-12-30 | 2020-05-08 | 南京广慈医疗科技有限公司 | Programmable self-calibration negative voltage constant power output circuit and method |
| CN111077936B (en) * | 2019-12-30 | 2021-10-22 | 南京广慈医疗科技有限公司 | Programmable self-calibration positive voltage constant power output circuit and method |
| CN111273208A (en) * | 2020-03-11 | 2020-06-12 | 深圳市金锐显数码科技有限公司 | Precision automatic correction method and system based on electronic load |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN203881815U (en) | Simple high-precision DC electronic load | |
| CN104155590B (en) | Diode forward recovers parametric synthesis test analysis platform | |
| CN103969614A (en) | Calibration method for digital multimeter | |
| CN207586312U (en) | A kind of digital frequency meter based on FPGA | |
| CN112098916A (en) | System and method for superposing ripples on direct current loop in direct current electric energy detection device | |
| CN104034956B (en) | Positive/negative voltage measuring circuit | |
| CN104316892A (en) | Transformer load box calibration device | |
| CN204679622U (en) | With the three-phase intelligent electric-energy meter communication interface load capacity proving installation of communication module | |
| CN103926550A (en) | Device and method for checking electric transformer based on virtual instrument | |
| CN202757808U (en) | Constant-flow air sampler | |
| CN103472751A (en) | AD sampling circuit used for pure electric vehicle | |
| CN206740279U (en) | A kind of pressure measurement circuitry | |
| CN203479906U (en) | Four-wire system Pt100 resistor measuring circuit | |
| CN103698562B (en) | A kind of electronic load device and emulation mode thereof | |
| CN203965060U (en) | A kind of temperature sensor circuit based on reference source | |
| CN201402317Y (en) | Verifying unit for resistive current tester of zinc oxide arrester | |
| CN204461518U (en) | A kind of heating type turbine integral type flowmeter | |
| CN209625022U (en) | A kind of two-way redundancy analogue quantity output circuit | |
| CN102944717B (en) | Voltage check device and method | |
| CN103675472B (en) | A kind of node signal strength detection circuit | |
| CN207037515U (en) | A kind of adjustable Digital Control Direct Current Source | |
| CN207123777U (en) | The 1mA current source modules for carrying overcurrent protection based on operational amplifier | |
| CN203929874U (en) | Positive inverse voltage metering circuit simultaneously | |
| CN106841964B (en) | High-precision programmable voltage soft circuit | |
| CN104460496A (en) | Numerical control constant current source circuit based on PLC |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20141015 Termination date: 20170523 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |