CN114137293A - Direct current torque motor current detection circuit with isolation function - Google Patents
Direct current torque motor current detection circuit with isolation function Download PDFInfo
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- CN114137293A CN114137293A CN202111337395.0A CN202111337395A CN114137293A CN 114137293 A CN114137293 A CN 114137293A CN 202111337395 A CN202111337395 A CN 202111337395A CN 114137293 A CN114137293 A CN 114137293A
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- 238000002955 isolation Methods 0.000 title claims abstract description 50
- 238000001514 detection method Methods 0.000 title claims abstract description 21
- 238000005070 sampling Methods 0.000 claims abstract description 55
- 102100036285 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial Human genes 0.000 claims description 3
- 101000875403 Homo sapiens 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial Proteins 0.000 claims description 3
- 230000002093 peripheral effect Effects 0.000 claims description 3
- 230000002401 inhibitory effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000009365 direct transmission Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
- 238000011897 real-time detection Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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Abstract
The invention relates to a direct current torque motor current detection circuit with an isolation function, belonging to the field of automatic control; the device comprises a microcontroller, a direct current torque motor, a current sampling resistor, a linear photoelectric isolation amplifier, an operational amplifier, an AD sampling chip and a motor driving circuit. The microcontroller applies voltage to two ends of the direct current torque motor through the motor driving circuit, the current sampling resistor is connected in series to the DCN end of the direct current torque motor, and the current of the current sampling resistor is converted into a voltage signal to be input into the linear photoelectric isolation amplifier; a pair of differential signals output by the amplifier are converted into single-ended voltage signals through the operational amplifier, then the single-ended voltage signals are converted into digital signals through the AD sampling chip, the digital signals are input into the microcontroller, the microcontroller performs current loop control on the direct current torque motor according to detected current, and the control performance of the direct current torque motor is improved. The invention can realize the high-speed and accurate sampling and detection of the current of the direct current torque motor while isolating the current disturbance of the direct current torque motor and inhibiting the common-mode interference.
Description
Technical Field
The invention belongs to the field of automatic control, and particularly relates to a direct current torque motor current detection circuit with an isolation function.
Background
The direct-current torque motor plays an important role in the field of high-speed and high-precision control. The torque motor is the best choice in the field of high-precision rotary motion due to the characteristics of direct transmission, no reverse clearance, no abrasion and the like. The essence of direct current torque motor control is current control, but the control scheme of the encoder which is widely used at present and matched with the direct current torque motor only can achieve speed loop control, and the current control on the direct current torque motor is not accurate, so that the bottleneck for restricting the improvement of the control performance of the direct current torque motor is formed.
The current loop control of the direct current torque motor can effectively improve the control performance of the direct current torque motor, but the current of the direct current torque motor needs to be accurately detected at a high speed for the feedback control of the current loop of the direct current torque motor. The invention patent CN 103344811B provides a dc motor current detection circuit, but simply proposes to detect the tube voltage drop of the MOSFET in the driving circuit part of the dc motor to realize the current detection of the dc motor, and does not completely give out how the tube voltage drop of the MOSFET is converted into a digital signal accurately and stably at high speed, and is not suitable for performing high-speed and high-precision current loop control on the dc torque motor in engineering practice.
Disclosure of Invention
The technical problem to be solved is as follows:
in order to avoid the defects of the prior art, the invention provides a direct current torque motor current detection circuit with an isolation function, which comprises a microcontroller 1, a direct current torque motor 2, a current sampling resistor 3, a linear photoelectric isolation amplifier 4, an operational amplifier 5, an AD sampling chip 6 and a motor drive circuit 7. The current disturbance of the direct current torque motor is isolated, common-mode interference is restrained, and meanwhile, the current sampling and detection of the direct current torque motor are completed at high speed and accurately. The current detection circuit provided by the invention can be directly applied to current loop control of the direct current torque motor, and the control performance of the direct current torque motor is effectively improved.
The technical scheme of the invention is as follows: a direct current torque motor current detection circuit with an isolation function is characterized in that: the device comprises a microcontroller 1, a direct current torque motor 2, a current sampling resistor 3, a linear photoelectric isolation amplifier 4, an operational amplifier 5, an AD sampling chip 6 and a motor driving circuit 7; the microcontroller 1 applies voltage to two ends of a DCP and a DCN of the direct current torque motor 2 through a motor driving circuit 7, wherein the DCP is a positive pole of the applied voltage, and the DCN is a negative pole of the applied voltage; the current sampling resistor 3 is connected in series with the DCN end of the direct current torque motor 2 and converts the current of the direct current torque motor 2 into a voltage signal; the voltage signal outputs a pair of differential voltage signals which are in direct proportion to the current of the direct current torque motor through the linear photoelectric isolation amplifier 4, the differential voltage signals are converted into single-ended voltage signals through the operational amplifier 5, and then the single-ended voltage signals are converted into digital signals through the AD sampling chip 6 and input into the microcontroller 1.
The further technical scheme of the invention is as follows: the resistance value of the current sampling resistor 3 is determined according to the voltage output range of the sampling circuit and the current magnitude of the direct current torque motor, and the formula is as follows:
U＝I*R+L*di/dt
u is the voltage of the sampling resistor, I is the current of the DC torque motor, L is the inductance value of the sampling resistor, and di/dt is the differential of the current.
The further technical scheme of the invention is as follows: the linear photoelectric isolation amplifier 4 has the model of HCPL7840 and the rated gain G1The output voltage range is-1.6- +1.6V ═ 8.
The further technical scheme of the invention is as follows: the input signal voltage range of the linear photoelectric isolation amplifier 4HCPL7840 is-200 mV, and the primary supply voltage VDD1 and the secondary supply voltage VDD2 are both 4.5-5.5V.
The further technical scheme of the invention is as follows: the peripheral circuit of the operational amplifier 5 comprises resistors R2, R3, R4 and R5, wherein R2 is R3, and R4 is R5; the resistors R2 and R3 are connected between the linear photoelectric isolation amplifier 4 and the operational amplifier 5, the operational amplifier 5 is connected with the resistor R4 and then grounded, and the resistor R5 is connected in parallel with the operational amplifier 5.
The further technical scheme of the invention is as follows: the single-ended output voltage of the operational amplifier 5 is:
wherein, UadFor the output voltage of the operational amplifier, Uout+And Uout-Inputting a differential voltage signal, R, to the operational amplifier3And R5Is an operational amplifier gain resistance.
Advantageous effects
The invention has the beneficial effects that: according to the direct current torque motor current detection circuit with the isolation function, the linear photoelectric isolation amplifier 4 adopts a device model of HCPL7840, FIG. 1 is a functional schematic diagram of the HCPL7840 device, and the input end and the output end of the HCPL7840 device are isolated through a photoelectric device. Therefore, on one hand, the HCPL7840 device can isolate a strong electric signal in the direct current torque motor driving circuit from a weak electric signal in the sampling control circuit, effectively protects the safety and stability of the current sampling circuit, and cannot be easily damaged by current disturbance existing in the direct current torque motor driving circuit; on the other hand, the HCPL7840 device outputs a pair of differential voltage signals which are in direct proportion to the current of the direct-current torque motor, so that common-mode interference of a complex electromagnetic environment on a sampling circuit can be effectively inhibited, and the accuracy and reliability of current sampling are guaranteed. The concrete advantages are as follows:
1. the voltage signals at the two ends of the current sampling resistor 3 and a pair of differential signals output by the linear photoelectric isolation amplifier 4 have a photoelectric isolation function, and the safety and stability of the current sampling circuit can be protected when the current fluctuation of the direct current torque motor 2 is abnormal, the interference is serious or the fault is short-circuited.
2. The linear photoelectric isolation amplifier 4 outputs a pair of differential voltage signals which are in direct proportion to the current of the direct-current torque motor, and can effectively inhibit the common-mode interference of a complex electromagnetic environment on the current sampling circuit.
3. A pair of differential signals output by the linear photoelectric isolation amplifier 4 are converted into single-ended voltage signals through the operational amplifier 5, then are converted into digital signals through the AD sampling chip 6, and the digital signals are input into the microcontroller 1, and the microcontroller 1 performs current loop control on the direct current torque motor 2 according to detected current, so that the control performance of the direct current torque motor is improved.
The direct current torque motor current detection circuit with the isolation function provided by the invention is a complete and reliable current sampling scheme, fully considers the impact and interference conditions in engineering practice, can stably and accurately detect the current of the direct current torque motor at a high speed, can directly realize the current loop control of the direct current torque motor, and improves the control performance of the direct current torque motor.
Drawings
FIG. 1 is a functional schematic diagram of a linear opto-isolation amplifier HCPL 7840;
fig. 2 is a circuit topology diagram of a dc torque motor current detection circuit with isolation function according to the present invention.
Detailed Description
The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
Fig. 2 is a circuit topology diagram of a current detection circuit of a dc torque motor with an isolation function according to the present invention, which includes a microcontroller 1, a dc torque motor 2, a current sampling resistor 3, a linear photoelectric isolation amplifier 4, an operational amplifier 5, an AD sampling chip 6, and a motor driving circuit 7; the microcontroller 1 applies voltage to two ends of a DCP and a DCN of the direct current torque motor 2 through a motor driving circuit 7, wherein the DCP is a positive pole of the applied voltage, and the DCN is a negative pole of the applied voltage; the current sampling resistor 3 is connected in series with the DCN end of the direct current torque motor 2 and converts the current of the direct current torque motor 2 into a voltage signal; the voltage signal outputs a pair of differential voltage signals which are in direct proportion to the current of the direct current torque motor through the linear photoelectric isolation amplifier 4, the differential voltage signals are converted into single-ended voltage signals through the operational amplifier 5, and then the single-ended voltage signals are converted into digital signals through the AD sampling chip 6 and input into the microcontroller 1.
As shown in the figure, nodes DCP and DCN are two nodes to which the dc torque motor applies voltage, DCP is a positive pole to which the voltage is applied, and DCN is a negative pole to which the voltage is applied. The current of the direct current torque motor is converted into an analog voltage signal through a current sampling resistor R1 connected between a node DCN and the photoelectric isolation amplifier HCPL7840 in series. The analog voltage signal at both ends of the current sampling resistor R1 is input to the photoelectric isolation amplifier HCPL 7840. The voltage signals at the two ends of the current sampling resistor R1 and a pair of differential signals output by the linear photoelectric isolation amplifier 4 have a photoelectric isolation function, and the safety and stability of the current sampling circuit can be protected when the current fluctuation of the direct current torque motor 2 is abnormal, the interference is serious or the fault is short-circuited.
The resistance value of the sampling resistor is determined according to the voltage output range of the sampling circuit and the current of the direct current torque motor. In order to ensure the sampling precision of the current of the direct current torque motor, a non-inductive resistor is recommended to be selected.
U＝I*R+L*di/dt
U is the voltage of the sampling resistor, I is the current of the DC torque motor, L is the inductance value of the sampling resistor, and di/dt is the differential of the current.
In the invention, the voltage range of an input signal of the photoelectric isolation amplifier HCPL7840 is-200 mV, the primary supply voltage VDD1 and the secondary supply voltage VDD2 are required to be 4.5-5.5V, and the filter capacitor C1 is used for eliminating ripples and high-frequency noise in power supply and ensuring the accuracy of an output signal of the photoelectric isolation amplifier HCPL 7840. Therefore, the current sampling resistor should be selected in consideration of the voltage output by the sampling circuit within the above voltage range.
Analog voltage signals at two ends of the current sampling resistor R1 are output to a pair of differential voltage signals which are in direct proportion to the current of the direct-current torque motor through the photoelectric isolation amplifier HCPL7840, and common-mode interference of a complex electromagnetic environment on a current sampling circuit can be effectively inhibited. The photoelectric isolation device in the HCPL7840 can effectively isolate strong electric signals of the direct current torque motor driving circuit and weak electric signals in the sampling control circuit, and effectively protects the safety and stability of the current sampling circuit. In addition, due to the rated gain G of the photoelectric isolation amplifier HCPL78401Since 8, the output voltage of the photoelectric isolation amplifier HCPL7840 ranges from-1.6 to + 1.6V.
The photoelectric isolation amplifier HCPL7840 outputsA pair of differential voltage signals enter an operational amplifier and are converted into single-ended analog signals. The operational amplifier is used for amplifying the output voltage of the photoelectric isolation amplifier HCPL7840 to be within an allowable range of the input voltage of the AD chip. R2, R3, R4 and R5 are peripheral circuits of the operational amplifier, and the requirement of R is that2＝R3,R4＝R5The differential operational amplifier obtains a single-ended output of
Wherein, UadFor the output voltage of the operational amplifier, Uout+And Uout-Inputting a differential voltage signal, R, to the operational amplifier3And R5Is an operational amplifier gain resistance.
The selection of the bias voltage and the gain resistance of the operational amplifier should take the output voltage range of the photoelectric isolation amplifier HCPL7840 and the allowable range of the input voltage of the AD sampling chip into consideration.
The AD sampling chip converts the single-ended voltage signal into a digital signal and transmits the digital signal to the microcontroller, and therefore high-speed real-time detection of the current of the direct-current torque motor is achieved. Then, the microcontroller can combine the control law to carry out the accurate control of current loop according to the direct current torque motor current signal that detects.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.
Claims (6)
1. A direct current torque motor current detection circuit with an isolation function is characterized in that: the device comprises a microcontroller (1), a direct-current torque motor (2), a current sampling resistor (3), a linear photoelectric isolation amplifier (4), an operational amplifier (5), an AD sampling chip (6) and a motor driving circuit (7); the microcontroller (1) applies voltage to two ends of a DCP and a DCN of the direct current torque motor (2) through a motor driving circuit (7), wherein the DCP is the positive pole of the applied voltage, and the DCN is the negative pole of the applied voltage; the current sampling resistor (3) is connected in series with the DCN end of the direct current torque motor (2) to convert the current of the direct current torque motor (2) into a voltage signal; the voltage signal outputs a pair of differential voltage signals which are in direct proportion to the current of the direct-current torque motor through a linear photoelectric isolation amplifier (4), the differential voltage signals are converted into single-ended voltage signals through an operational amplifier (5), and then the single-ended voltage signals are converted into digital signals through an AD sampling chip (6) and input into the microcontroller (1).
2. The direct current torque motor current detection circuit with the isolation function according to claim 1, characterized in that: the resistance value of the current sampling resistor (3) is determined according to the voltage output range of the sampling circuit and the current of the direct current torque motor, and the formula is as follows:
U＝I*R+L*di/dt
u is the voltage of the sampling resistor, I is the current of the DC torque motor, L is the inductance value of the sampling resistor, and di/dt is the differential of the current.
3. The direct current torque motor current detection circuit with the isolation function according to claim 1, characterized in that: the model of the linear photoelectric isolation amplifier (4) is HCPL7840, and the rated gain G1The output voltage range is-1.6- +1.6V ═ 8.
4. The direct current torque motor current detection circuit with the isolation function according to claim 1, characterized in that: the input signal voltage range of the linear photoelectric isolation amplifier (4) HCPL7840 is-200 mV, and the primary supply voltage VDD1 and the secondary supply voltage VDD2 are both 4.5-5.5V.
5. The direct current torque motor current detection circuit with the isolation function according to claim 1, characterized in that: the peripheral circuit of the operational amplifier (5) comprises resistors R2, R3, R4 and R5, wherein R2 is R3, and R4 is R5; the resistors R2 and R3 are connected between the linear photoelectric isolation amplifier (4) and the operational amplifier (5), the operational amplifier (5) is connected with the resistor R4 and then grounded, and the resistor R5 is connected with the operational amplifier (5) in parallel.
6. The direct current torque motor current detection circuit with the isolation function according to claim 1, characterized in that: the single-ended output voltage of the operational amplifier (5) is:
wherein, UadFor the output voltage of the operational amplifier, Uout+And Uout-Inputting a differential voltage signal, R, to the operational amplifier3And R5Is an operational amplifier gain resistance.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111337395.0A CN114137293A (en) | 2021-11-02 | 2021-11-02 | Direct current torque motor current detection circuit with isolation function |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111337395.0A CN114137293A (en) | 2021-11-02 | 2021-11-02 | Direct current torque motor current detection circuit with isolation function |
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| CN114137293A true CN114137293A (en) | 2022-03-04 |
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| CN202111337395.0A Pending CN114137293A (en) | 2021-11-02 | 2021-11-02 | Direct current torque motor current detection circuit with isolation function |
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|---|---|---|---|---|
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| CN206878734U (en) * | 2017-04-12 | 2018-01-12 | 浙江航驱汽车科技有限公司 | For there is the direct current generator current sampling device of brush EPS controllers |
| CN108363008A (en) * | 2018-03-05 | 2018-08-03 | 耐世特汽车系统（苏州）有限公司 | A kind of online current control diagnostic circuit of brushed DC motor |
| JP2018132341A (en) * | 2017-02-14 | 2018-08-23 | キヤノン株式会社 | Highly accurate detector for motor current |
-
2021
- 2021-11-02 CN CN202111337395.0A patent/CN114137293A/en active Pending
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2836027Y (en) * | 2005-08-18 | 2006-11-08 | 方大集团股份有限公司 | Motor winding current detecting circuit for shielded door |
| JP2008005596A (en) * | 2006-06-21 | 2008-01-10 | Nsk Ltd | Current detector, motor controller, and method of current detection |
| CN1976203A (en) * | 2006-11-10 | 2007-06-06 | 陆启建 | Precision current sensor used for electric machine control |
| CN103270689A (en) * | 2010-08-20 | 2013-08-28 | Trw有限公司 | Measurement circuit |
| KR20120028429A (en) * | 2010-09-14 | 2012-03-23 | 엘지이노텍 주식회사 | Output current detection device of 3-phase motor drive using wire-wounded resistor of motor |
| CN103490699A (en) * | 2012-06-13 | 2014-01-01 | 赐福科技股份有限公司 | Current measurement circuit and motor control device with same |
| CN203011991U (en) * | 2012-12-10 | 2013-06-19 | 珠海格力电器股份有限公司 | Current sampling circuit and motor |
| CN103344811A (en) * | 2013-06-27 | 2013-10-09 | 浙江联宜电机股份有限公司 | Current detecting circuit of direct-current motor |
| JP2018132341A (en) * | 2017-02-14 | 2018-08-23 | キヤノン株式会社 | Highly accurate detector for motor current |
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