CN205484401U - Low -cost speed measurement circuit of high accuracy for brush DC motor - Google Patents
Low -cost speed measurement circuit of high accuracy for brush DC motor Download PDFInfo
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- CN205484401U CN205484401U CN201620059257.9U CN201620059257U CN205484401U CN 205484401 U CN205484401 U CN 205484401U CN 201620059257 U CN201620059257 U CN 201620059257U CN 205484401 U CN205484401 U CN 205484401U
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Abstract
The utility model relates to a low -cost speed measurement circuit of high accuracy for brush DC motor, according to the utility model provides a technical scheme, low -cost speed measurement circuit of high accuracy for brush DC motor, including the current sampling circuit that is used for acquireing brush DC motor operating current signal, the output of current sampling circuit is connected with being used for the one -level signal amplification circuit who carries out the signal amplification, one -level signal amplification circuit's output is connected with being used for the DC signal buffer circuit with DC signal keeps apart, DC signal buffer circuit's output and second grade signal amplification circuit are connected, second grade signal amplification circuit's output with be used for confirming according to signal frequency the signal frequency operation circuit connection of brush DC motor rotational speed. The utility model discloses compact structure, the ability accuracy obtains brush DC motor's velocity amplitude, reduces the cost of brush DC motor speed measurement, and accommodation is wide, safe and reliable.
Description
Technical field
This utility model relates to a kind of Kind of Speed Measuring Circuit, especially a kind of brushed DC motor high-precision low cost Kind of Speed Measuring Circuit, belongs to the technical field that brushed DC motor speed is measured.
Background technology
Brush direct current motor controls simple, cheap, is the most still widely used.In the closed-loop control system of brush direct current motor, need the rotating speed of brush direct current motor does accurate measurement.By using environment, the restriction of the factor such as cost budgeting, actual application often cannot install external velocity sensor so that control effect and have a greatly reduced quality.
Brush direct current motor, by the on and off of carbon brush switching armature winding, that is to say commutation.In commutation process, the electric current flowing through carbon brush all can experience the process increased afterwards that first reduces, and produces pulsation of current.Often the pulsation of generation primary current means that and completes a commutation process, and the interval of commutation correspond to the rotating speed of brushed DC motor, and the time interval measuring twice speed ripple has just become to measure the basis of brushed DC motor speed.
When calculating brush direct current motor operating, pulsation of current is the basis obtaining current signal complete, accurate, according to Ohm's law, electric current can produce voltage drop after flowing through resistive load, by concatenation high accuracy low resistance sampling resistor in current loop, current signal can be converted to small voltage signal.In prior art, become equiphase amplitude after being amplified by amplified for this voltage signal device to increase and the most identified voltage signal, voltage signal carries out bandpass filtering by signal filtering device, select the fluctuating signal of commutator commutator pulse, pulsewidth or frequency measurement is carried out by pulse duration frequency measurement apparatus, and convert according to motor commutator number of pole-pairs, obtain final motor speed.
In the case of constant load constant rotational speed, the work process of brush direct current motor can be divided into two processes: is operated in non-commutation state and is operated in commutation process；Wherein, when being operated in non-commutation state, the electric current flowing through brushed DC motor is approximately steady state value；When being operated in commutation process, there is the pulsation of current that commutation causes.Therefore flowing through the superposition that electric current is DC component and AC compounent of brushed DC motor, the amplitude of DC component depends on the load of brush direct current motor；The amplitude of AC compounent depends on the size of rotating speed.
Prior art scheme, use single amplifying device that voltage signal is amplified, but the amplification of amplifying device but cannot cover all of operating mode, as during unloaded low cruise, current amplitude is the least, need great amplification just can obtain discernible voltage signal, the most also can introduce substantial amounts of noise jamming；During heavy service due to the DC component in brushed DC current of electric greatly, may result in amplifying device output saturated.
In actual application, the duty of motor cannot be predicted, and prior art cannot meet the measurement of the rotating speed under particular job scene, causes controlling inefficacy the most accidents caused.
Summary of the invention
The purpose of this utility model is to overcome the deficiencies in the prior art, a kind of brushed DC motor high-precision low cost Kind of Speed Measuring Circuit is provided, its compact conformation, can accurately obtain the velocity amplitude of brushed DC motor, reduce the cost that brushed DC motor speed is measured, wide accommodation, safe and reliable.
The technical scheme provided according to this utility model, described brushed DC motor high-precision low cost Kind of Speed Measuring Circuit, including the current sampling circuit for obtaining brushed DC motor working current signal；The outfan of described current sampling circuit is connected with the one stage signal amplifying circuit being used for carrying out signal amplification, the outfan of described one stage signal amplifying circuit is connected with the direct current signal isolation circuit for being isolated by direct current signal, described direct current signal isolation circuit outfan be connected with second signal amplifying circuit, the outfan of second signal amplifying circuit be used for determine that the signal frequency computing circuit of described brushed DC motor speed is connected according to signal frequency.
Described second signal amplifying circuit is connected with signal frequency computing circuit by signal bandwidth filter circuit.
Described current sampling circuit includes the full-bridge circuit being connected with brushed DC motor, described full-bridge circuit includes power tube Q1, power tube Q2, power tube Q3 and power tube Q4, the drain electrode end of power tube Q1, the drain electrode end of power tube Q2 is connected with voltage VCC, the source terminal of power tube Q1 is connected with the drain electrode end of power tube Q3 and one end of brushed DC motor, the drain electrode end of power tube Q2 is connected with the drain electrode end of power tube Q4 and the other end of brushed DC motor, the source terminal of power tube Q3, the source terminal of power tube Q4 all one end with sampling resistor R16 are connected, the other end ground connection of sampling resistor R16.
Described one stage signal amplifying circuit includes operational amplifier 1A, the end of oppisite phase of described operational amplifier 1A and one end of resistance R1, one end of resistance R2 and one end of electric capacity C1 connect, the in-phase end of operational amplifier 1A and one end of resistance R4, one end of resistance R5 and one end of electric capacity C3 connect, the other end ground connection of resistance R1, the other end of electric capacity C1 and the other end of resistance R2 all outfans with operational amplifier 1A are connected, the other end of resistance R4 is connected with the outfan of current sampling circuit, the other end of resistance R5 is connected with power supply VCC, the other end ground connection of electric capacity C3；The outfan of operational amplifier 1A is connected with one end of resistance R3, and the input that the other end of described resistance R3 isolates circuit with one end of electric capacity C2 and direct current signal is connected, the other end ground connection of electric capacity C2.
Advantage of the present utility model: use the structure that two-stage is amplified when the voltage signal on sampling resistor is amplified, and utilizing direct current signal isolation circuit to remove the DC component after one stage signal amplifying circuit 2 amplifies so that second signal amplifying circuit only amplifies useful AC signal.During unloaded low cruise, voltage signal has enough amplifications that small-signal is identified after two-stage is amplified, and also reduces the interference of noise simultaneously；During heavy service, due to the existence of direct current signal isolation circuit so that final amplification output will not be fully saturated, thus signal frequency computing circuit can export the tachometer value of accurate brushed DC motor, the cost that reduction brushed DC motor speed is measured, wide accommodation, safe and reliable.
Accompanying drawing explanation
Fig. 1 is structured flowchart of the present utility model.
Fig. 2 is the schematic diagram of this utility model one stage signal amplifying circuit.
Fig. 3 is the schematic diagram of this utility model current sampling circuit.
Description of reference numerals: 1-current sampling circuit, 2-one stage signal amplifying circuit, 3-direct current signal isolation circuit, 4-second signal amplifying circuit, 5-signal bandwidth filter circuit and 6-signal frequency computing circuit.
Detailed description of the invention
Below in conjunction with concrete drawings and Examples, the utility model is described in further detail.
As shown in Figure 1: in order to enable accurately to obtain the velocity amplitude of brushed DC motor, reducing the cost that brushed DC motor speed is measured, this utility model includes the current sampling circuit 1 for obtaining brushed DC motor working current signal；The outfan of described current sampling circuit 1 is connected with the one stage signal amplifying circuit 2 being used for carrying out signal amplification, the outfan of described one stage signal amplifying circuit 2 is connected with the direct current signal isolation circuit 3 for being isolated by direct current signal, described direct current signal isolation circuit 3 outfan be connected with second signal amplifying circuit 4, the outfan of second signal amplifying circuit 4 be used for determine that the signal frequency computing circuit 6 of described brushed DC motor speed is connected according to signal frequency.
Specifically, current sampling circuit 1 is connected with brushed DC motor, and current signal when brushed DC motor is worked is sampled and is converted to synchronous voltage signal.The voltage signal that current sampling circuit 1 is transmitted by one stage signal amplifying circuit 2 is amplified with less amplification, so that direct current signal, AC signal in voltage signal are the most exaggerated.Direct current signal isolation circuit 3 carries out isolation to the DC component in the voltage signal after one stage signal amplifying circuit 2 amplification and removes, and only retains AC compounent, and direct current signal isolation circuit 3 exports the AC signal of triangular wave.Second signal amplifying circuit 4 is by being amplified the triangular wave of direct current signal isolation circuit 3 output so that the amplitude of signal reaches the purpose identified；Additionally, due to direct current signal isolation 3 output AC signals of circuit, then second signal amplifying circuit 4 the most only exports triangular wave or trapezoidal wave.The frequency of second signal amplifying circuit 4 output signal can be calculated by signal frequency computing circuit 6, to obtain the rotating speed of brush direct current motor.
Described second signal amplifying circuit 4 is connected with signal frequency computing circuit 6 by signal bandwidth filter circuit 5.In this utility model embodiment, the signal that second signal amplifying circuit 4 is exported by signal bandwidth filter circuit 5 is filtered, to obtain required frequency signal, it is simple to signal frequency computing circuit 6 obtains the rotating speed of brushed DC motor according to frequency signal computing.The process that signal frequency computing circuit 6 obtains brushed DC motor speed according to frequency signal is that known to those skilled in the art, here is omitted.
As shown in Figure 3, described current sampling circuit 1 includes the full-bridge circuit being connected with brushed DC motor, described full-bridge circuit includes power tube Q1, power tube Q2, power tube Q3 and power tube Q4, the drain electrode end of power tube Q1, the drain electrode end of power tube Q2 is connected with voltage VCC, the source terminal of power tube Q1 is connected with the drain electrode end of power tube Q3 and one end of brushed DC motor, the drain electrode end of power tube Q2 is connected with the drain electrode end of power tube Q4 and the other end of brushed DC motor, the source terminal of power tube Q3, the source terminal of power tube Q4 all one end with sampling resistor R16 are connected, the other end ground connection of sampling resistor R16.
In this utility model embodiment, sample circuit R16 can be conventional precision resister, and one end that the source terminal of sampling resistor R16 and power tube Q3, power tube Q4 source terminal are connected is as the outfan of galvanic areas circuit 1.
As shown in Figure 2, described one stage signal amplifying circuit 2 includes operational amplifier 1A, the end of oppisite phase of described operational amplifier 1A and one end of resistance R1, one end of resistance R2 and one end of electric capacity C1 connect, the in-phase end of operational amplifier 1A and one end of resistance R4, one end of resistance R5 and one end of electric capacity C3 connect, the other end ground connection of resistance R1, the other end of electric capacity C1 and the other end of resistance R2 all outfans with operational amplifier 1A are connected, the other end of resistance R4 is connected with the outfan of current sampling circuit 1, the other end of resistance R5 is connected with power supply VCC, the other end ground connection of electric capacity C3；The outfan of operational amplifier 1A is connected with one end of resistance R3, and the input that the other end of described resistance R3 isolates circuit 3 with one end of electric capacity C2 and direct current signal is connected, the other end ground connection of electric capacity C2.
In this utility model embodiment, second signal amplifying circuit 4 can be to use the form identical with described one stage signal amplifying circuit 2.
The structure that two-stage is amplified is used when voltage signal on sampling resistor R16 is amplified by this utility model, and utilizing direct current signal isolation circuit 3 to remove the DC component after one stage signal amplifying circuit 2 amplifies so that second signal amplifying circuit 4 amplifies useful AC signal.During unloaded low cruise, voltage signal has enough amplifications that small-signal is identified after two-stage is amplified, and also reduces the interference of noise simultaneously；During heavy service, due to the existence of direct current signal isolation circuit 3 so that final amplification output will not be fully saturated, thus signal frequency computing circuit 6 can export the tachometer value of accurate brushed DC motor, the cost that reduction brushed DC motor speed is measured, wide accommodation, safe and reliable.
Claims (4)
1. a brushed DC motor high-precision low cost Kind of Speed Measuring Circuit, including the current sampling circuit (1) for obtaining brushed DC motor working current signal；It is characterized in that: the outfan of described current sampling circuit (1) is connected with the one stage signal amplifying circuit (2) being used for carrying out signal amplification, the outfan of described one stage signal amplifying circuit (2) is connected with direct current signal isolation circuit (3) for being isolated by direct current signal, described direct current signal isolation circuit (3) outfan be connected with second signal amplifying circuit (4), the outfan of second signal amplifying circuit (4) be used for determine that the signal frequency computing circuit (6) of described brushed DC motor speed is connected according to signal frequency.
Brushed DC motor high-precision low cost Kind of Speed Measuring Circuit the most according to claim 1, is characterized in that: described second signal amplifying circuit (4) is connected with signal frequency computing circuit (6) by signal bandwidth filter circuit (5).
Brushed DC motor high-precision low cost Kind of Speed Measuring Circuit the most according to claim 1, it is characterized in that: described current sampling circuit (1) includes the full-bridge circuit being connected with brushed DC motor, described full-bridge circuit includes power tube Q1, power tube Q2, power tube Q3 and power tube Q4, the drain electrode end of power tube Q1, the drain electrode end of power tube Q2 is connected with voltage VCC, the source terminal of power tube Q1 is connected with the drain electrode end of power tube Q3 and one end of brushed DC motor, the drain electrode end of power tube Q2 is connected with the drain electrode end of power tube Q4 and the other end of brushed DC motor, the source terminal of power tube Q3, the source terminal of power tube Q4 all one end with sampling resistor R16 are connected, the other end ground connection of sampling resistor R16.
Brushed DC motor high-precision low cost Kind of Speed Measuring Circuit the most according to claim 1, it is characterized in that: described one stage signal amplifying circuit (2) includes operational amplifier 1A, the end of oppisite phase of described operational amplifier 1A and one end of resistance R1, one end of resistance R2 and one end of electric capacity C1 connect, the in-phase end of operational amplifier 1A and one end of resistance R4, one end of resistance R5 and one end of electric capacity C3 connect, the other end ground connection of resistance R1, the other end of electric capacity C1 and the other end of resistance R2 all outfans with operational amplifier 1A are connected, the other end of resistance R4 is connected with the outfan of current sampling circuit (1), the other end of resistance R5 is connected with power supply VCC, the other end ground connection of electric capacity C3；The outfan of operational amplifier 1A is connected with one end of resistance R3, and the input that the other end of described resistance R3 isolates circuit (3) with one end of electric capacity C2 and direct current signal is connected, the other end ground connection of electric capacity C2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620059257.9U CN205484401U (en) | 2016-01-21 | 2016-01-21 | Low -cost speed measurement circuit of high accuracy for brush DC motor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620059257.9U CN205484401U (en) | 2016-01-21 | 2016-01-21 | Low -cost speed measurement circuit of high accuracy for brush DC motor |
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| CN205484401U true CN205484401U (en) | 2016-08-17 |
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| CN201620059257.9U Active CN205484401U (en) | 2016-01-21 | 2016-01-21 | Low -cost speed measurement circuit of high accuracy for brush DC motor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111323703A (en) * | 2020-03-25 | 2020-06-23 | 常州登丰电气有限公司 | Device and method for measuring commutation times and commutation frequency of direct current brush motor |
| CN111669156A (en) * | 2020-06-17 | 2020-09-15 | 宁波双林汽车部件股份有限公司 | Universal pre-amplification large-scale current ripple wave acquisition circuit device |
| CN114397470A (en) * | 2021-11-24 | 2022-04-26 | 浙江捷昌线性驱动科技股份有限公司 | Stroke control system based on motor current characteristics |
-
2016
- 2016-01-21 CN CN201620059257.9U patent/CN205484401U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111323703A (en) * | 2020-03-25 | 2020-06-23 | 常州登丰电气有限公司 | Device and method for measuring commutation times and commutation frequency of direct current brush motor |
| CN111669156A (en) * | 2020-06-17 | 2020-09-15 | 宁波双林汽车部件股份有限公司 | Universal pre-amplification large-scale current ripple wave acquisition circuit device |
| CN114397470A (en) * | 2021-11-24 | 2022-04-26 | 浙江捷昌线性驱动科技股份有限公司 | Stroke control system based on motor current characteristics |
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