CN108196114B - Motor current sampling system and method - Google Patents
Motor current sampling system and method Download PDFInfo
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- CN108196114B CN108196114B CN201810074031.XA CN201810074031A CN108196114B CN 108196114 B CN108196114 B CN 108196114B CN 201810074031 A CN201810074031 A CN 201810074031A CN 108196114 B CN108196114 B CN 108196114B
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- 238000005070 sampling Methods 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000012795 verification Methods 0.000 claims abstract description 99
- 238000001514 detection method Methods 0.000 claims abstract description 72
- 238000004364 calculation method Methods 0.000 claims abstract description 8
- 238000006243 chemical reaction Methods 0.000 claims description 12
- 239000004020 conductor Substances 0.000 description 6
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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
- G01R19/2506—Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing
- G01R19/2509—Details concerning sampling, digitizing or waveform capturing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
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Abstract
The invention provides a motor current sampling system and a motor current sampling method, wherein the motor current sampling system comprises a compensation calculation unit, a verification unit, at least one current divider and a plurality of current detection chips; wherein: the current detection chips are respectively attached to the surface of the printed circuit board and respectively correspond to a plurality of output wires used for outputting driving current on the printed circuit board; the current divider is connected in series with a direct current part in the motor driver, and the verification unit generates a verification signal according to the current in the current divider; the compensation calculation unit is used for respectively generating compensation values of the plurality of current detection chips based on the check signals according to the states of the switching tubes in the inversion unit of the motor driver. The invention compensates the sampling value of the current detection chip according to the voltage of the current divider connected in series with the direct current part of the motor driver, and greatly reduces the cost of motor current sampling while obtaining accurate sampling current.
Description
Technical Field
The invention relates to the field of motor control, in particular to a motor current sampling system and a motor current sampling method.
Background
To achieve accurate control of the motor, all motor control class drivers must sample the motor current. At present, the current sampling of the common motor mainly adopts the following four schemes:
(1) The current of the motor U, V, W is sampled by a shunt, and the motor current is isolated and conditioned by an isolated linear optocoupler and then sent to an analog-to-digital converter for processing to obtain a sampled value. But the cost of the isolated linear optocoupler used in this approach is relatively high.
(2) And using a finished Hall element, namely, enabling a motor power cable to pass through the Hall magnetic ring, isolating by utilizing the Hall magnetic ring, and then sending the analog quantity output by the Hall magnetic ring to an analog-to-digital converter for processing to obtain a sampling value. This solution also has the problem of relatively high costs of the finished hall element.
(3) The self-made Hall device is used, namely a Hall chip is stuck to the surface of a printed circuit board printed with a current copper sheet wire, the Hall chip detects current by detecting a magnetic field generated when the current flows through a conductor, and the detection quantity of the Hall chip is sent to an analog-to-digital converter for processing to obtain a sampling value. The Hall chip is used for replacing a finished Hall element, so that the cost can be reduced to a certain extent. However, the detection accuracy of the hall chip is relatively low and is easily affected by the accuracy of the mounting position.
(4) The non-isolation scheme is adopted, namely a shunt is used for sampling the lower bridge current or bus current of a U, V, W three-phase bridge arm, and a sampled circuit is sent to an analog-to-digital converter for processing to obtain a sampled value. The scheme can only detect when current flows through the lower bridge or the bus, so that certain requirements are imposed on a detection algorithm (namely, the current detection point is required to be fixed), and a comprehensive overcurrent protection function cannot be completed.
Disclosure of Invention
The invention aims to solve the technical problem that the motor current sampling cost is high or the accuracy is poor, and provides a novel motor current sampling system and a novel motor current sampling method.
The technical scheme of the invention for solving the technical problems is that a motor current sampling system is provided for sampling driving current output to a motor by a motor driver, and the motor current sampling system comprises a compensation calculating unit, a checking unit, at least one shunt and a plurality of current detection chips; wherein: the current detection chips are respectively attached to the surface of the printed circuit board and respectively correspond to a plurality of output wires used for outputting driving current on the printed circuit board; the current divider is connected in series with a direct current part in the motor driver, and the verification unit generates a verification signal according to the current in the current divider; the compensation calculation unit is used for respectively generating compensation values of the plurality of current detection chips based on the check signals according to the states of the switching tubes in the inversion unit of the motor driver.
In the motor current sampling system of the present invention, the verification unit includes a voltage conversion circuit and an analog-to-digital conversion circuit, wherein: the voltage conversion circuit is used for boosting the voltages at two ends of the shunt; the analog-to-digital conversion circuit is used for converting the voltage after the boosting processing into the check signal.
In the motor current sampling system, the inversion unit of the motor driver comprises three bridge arms, and the three bridge arms respectively output U-phase driving current, V-phase driving current and W-phase driving current to the motor; the motor current sampling system comprises three current detection chips, and the three current detection chips are respectively and correspondingly arranged with a U-phase output lead, a V-phase output lead and a W-phase output lead of an inversion unit on the printed circuit board.
In the motor current sampling system of the present invention, the motor current sampling system includes one of the shunts, and the shunts are connected in series on a negative dc bus of the motor driver; the compensation calculating unit generates a compensation value of a current detection chip corresponding to the U-phase output lead based on a verification signal generated by the verification unit when an upper bridge switching tube of a bridge arm connected with the U-phase output lead is conducted and lower bridge switching tubes of two other bridge arms are conducted, or when a lower bridge switching tube of a bridge arm connected with the U-phase output lead is conducted and upper bridge switching tubes of two other bridge arms are conducted; the compensation calculating unit generates a compensation value of a current detection chip corresponding to the V-phase output lead based on a verification signal generated by the verification unit when an upper bridge switching tube of a bridge arm connected with the V-phase output lead is conducted and a lower bridge switching tube of the other two bridge arms is conducted, or when a lower bridge switching tube of a bridge arm connected with the V-phase output lead is conducted and an upper bridge switching tube of the other two bridge arms is conducted; and the compensation calculation unit generates a compensation value of the current detection chip corresponding to the W-phase output lead based on the verification signal generated by the verification unit when the upper bridge switching tube of the bridge arm connected with the W-phase output lead is conducted and the lower bridge switching tubes of the other two bridge arms are conducted, or when the lower bridge switching tube of the bridge arm connected with the W-phase output lead is conducted and the upper bridge switching tubes of the other two bridge arms are conducted.
In the motor current sampling system of the present invention, the motor current sampling system includes one of the shunts, and the shunts are connected in series on a positive dc bus of the motor driver; the compensation calculating unit generates a compensation value of a current detection chip corresponding to the U-phase output lead based on a verification signal generated by the verification unit when an upper bridge switching tube of a bridge arm connected with the U-phase output lead is conducted and lower bridge switching tubes of two other bridge arms are conducted, or when a lower bridge switching tube of a bridge arm connected with the U-phase output lead is conducted and upper bridge switching tubes of two other bridge arms are conducted; the compensation calculating unit generates a compensation value of a current detection chip corresponding to the V-phase output lead based on a verification signal generated by the verification unit when an upper bridge switching tube of a bridge arm connected with the V-phase output lead is conducted and a lower bridge switching tube of the other two bridge arms is conducted, or when a lower bridge switching tube of a bridge arm connected with the V-phase output lead is conducted and an upper bridge switching tube of the other two bridge arms is conducted; and the compensation calculation unit generates a compensation value of the current detection chip corresponding to the W-phase output lead based on the verification signal generated by the verification unit when the upper bridge switching tube of the bridge arm connected with the W-phase output lead is conducted and the lower bridge switching tubes of the other two bridge arms are conducted, or when the lower bridge switching tube of the bridge arm connected with the W-phase output lead is disconnected and the upper bridge switching tubes of the other two bridge arms are conducted. .
In the motor current sampling system, the motor current sampling system comprises three current splitters, wherein the three current splitters are respectively connected in series between lower bridge switching tubes of three bridge arms and a negative direct current bus; the verification unit comprises a U-phase verification branch, a V-phase verification branch and a W-phase verification branch, and the U-phase verification branch, the V-phase verification branch and the W-phase verification branch generate verification signals according to currents in the three current splitters respectively; the compensation calculating unit generates a compensation value of a current detection chip corresponding to the U-phase output lead based on a verification signal of a U-phase verification branch when a lower bridge switching tube of a bridge arm connected with the U-phase output lead is conducted; the compensation calculating unit generates a compensation value of a current detection chip corresponding to the V-phase output lead based on a verification signal of a V-phase verification branch when a lower bridge switching tube of a bridge arm connected with the V-phase output lead is conducted; and when the lower bridge switching tube of the bridge arm connected with the W-phase output lead is conducted, the compensation calculating unit generates a compensation value of the current detection chip corresponding to the W-phase output lead based on the verification signal of the W-phase verification branch.
In the motor current sampling system, the motor current sampling system comprises three current splitters, wherein the three current splitters are respectively connected in series between upper bridge switching tubes of three bridge arms and a positive direct current bus; the verification unit comprises a U-phase verification branch, a V-phase verification branch and a W-phase verification branch, and the U-phase verification branch, the V-phase verification branch and the W-phase verification branch generate verification signals according to currents in the three current splitters respectively; when an upper bridge switching tube of a bridge arm connected with the U-phase output lead is conducted, the compensation calculating unit generates a compensation value of a current detection chip corresponding to the U-phase output lead based on a verification signal of a U-phase verification branch; the compensation calculating unit generates a compensation value of a current detection chip corresponding to the V-phase output lead based on a verification signal of a V-phase verification branch when an upper bridge switching tube of a bridge arm connected with the V-phase output lead is conducted; and when the upper bridge switching tube of the bridge arm connected with the W-phase output lead is conducted, the compensation calculating unit generates a compensation value of the current detection chip corresponding to the W-phase output lead based on the verification signal of the W-phase verification branch.
In the motor current sampling system of the present invention, the compensation calculating unit generates the compensation values of the plurality of current detecting chips respectively at a preset period.
The invention also provides a motor current sampling method for sampling the driving current output to the motor by the motor driver, which is characterized by comprising the following steps:
sampling multiphase driving currents output by the motor driver through a plurality of current detection chips respectively, wherein the current detection chips are respectively attached to the surface of the printed circuit board and respectively correspond to a plurality of output wires for outputting the driving currents;
generating a verification signal according to a current flowing through a shunt, the shunt being connected in series with a direct current portion in the motor driver;
and respectively generating compensation values of the current detection chips based on the check signal and the multiphase driving current according to the state of a switching tube in an inversion unit of the motor driver.
In the motor current sampling method of the present invention, the compensation values of the plurality of current detection chips are respectively generated in a preset period.
According to the motor current sampling system and the motor current sampling method, the sampling value of the current detection chip is compensated according to the voltage of the current divider connected in series with the direct current part of the motor driver, so that accurate sampling current is obtained, and meanwhile, the cost of motor current sampling is greatly reduced.
Drawings
FIG. 1 is a schematic diagram of a first embodiment of a motor current sampling system of the present invention;
FIG. 2 is a schematic diagram of a current detection chip arrangement in the motor current sampling system of the present invention;
FIG. 3 is a schematic diagram of a second embodiment of the motor current sampling system of the present invention;
FIG. 4 is a schematic diagram of a third embodiment of the motor current sampling system of the present invention;
FIG. 5 is a schematic diagram of a fourth embodiment of the motor current sampling system of the present invention;
fig. 6 is a flow chart of an embodiment of the motor current sampling method of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1, a schematic diagram of a first embodiment of a motor current sampling system according to the present invention may be integrated into a motor driver and sample a driving current output from the motor driver to a motor, thereby implementing motor control. The motor driver includes an inverter unit 11, in this embodiment, the inverter unit 11 employs a three-phase full-bridge inverter circuit, that is, the inverter unit 11 includes three bridge arms (each bridge arm includes an upper bridge switching tube and a lower bridge switching tube connected in series between a positive dc bus and a negative dc bus) and outputs a U-phase driving current, a V-phase driving current, and a W-phase driving current to the motor, respectively, by the three bridge arms. The input end of the inverter unit 11 is connected to the positive dc bus and the negative dc bus, and the output end is connected to a load (i.e., a motor).
The motor current sampling system of the present embodiment includes a compensation calculating unit 12, a verifying unit 13, one shunt 14, and three current detecting chips 15. The compensation calculating unit 12 may be constituted by a microcontroller (Microcontroller Unit, MCU) and program codes in the running microcontroller.
Referring to fig. 2, three current detecting chips 15 are respectively attached to the surface of the printed circuit board 2 (the printed circuit board 2 may be a current output board of a motor driver), and respectively correspond to three output wires 21. The three output wires 21 are a U-phase output wire, a V-phase output wire, and a W-phase output wire, respectively, and are used for outputting a U-phase drive current, a V-phase drive current, and a W-phase drive current, respectively. The U-phase output wire, the V-phase output wire and the W-phase output wire are respectively located in the printed circuit board 2, that is, three current detection chips 15 are respectively located right above the wiring planes of the U-phase output wire, the V-phase output wire and the W-phase output wire, so that the U-phase driving current, the V-phase driving current and the W-phase driving current which are output to the motor can be respectively detected.
In particular, the above-mentioned current detection chip 15 may employ a self-made hall element, i.e., a low-cost detection chip (low-cost means that the detection performance is poor, and no additional function is provided), so that the motor current sampling system of the present embodiment has a remarkable cost advantage.
The shunt 14 is connected in series with the dc part in the motor drive. In this embodiment, the shunt 14 is a shunt resistor and is connected in series to the negative dc bus of the motor drive. Since the voltage on the shunt 14 connected in series on the negative dc bus is referenced to the negative dc bus voltage, a non-isolated sampling scheme can be used, i.e., a linear isolated optocoupler is not required, and the cost is greatly reduced.
The verification unit 13 is used for generating a verification signal based on the current in the shunt 14. Specifically, the verification unit 13 may include a voltage conversion circuit and an analog-to-digital conversion circuit, where the voltage conversion circuit may boost the voltage across the shunt 14; the analog-to-digital conversion circuit is used for converting the voltage after the boosting process into a check signal (digital signal).
The compensation calculating unit 12 is configured to generate compensation values of the three current detecting chips 15 in a time-sharing manner according to states of the six switching tubes U11, U21, U12, U22, U13, U23 in the inverter unit 11 of the motor driver, and based on the verification signal generated by the verification unit 13. The compensation value may be a compensation coefficient, and may be used to compensate the current sampled by the current detection chip 15 in real time (i.e., correct the current sampled by the current detection chip 15 by the compensation value) when the state of the switching tube in the inverter unit 11 changes, so that a phase current value with higher accuracy may be obtained, and thus, the motor may be accurately controlled in a closed loop according to the phase current value.
Specifically, when the upper bridge switching tube U11 is turned on and the upper bridge switching tubes U12, U13 of the other two bridge arms are turned off, or when the upper bridge switching tube U11 is turned off and the upper bridge switching tubes U12, U13 of the other two bridge arms are turned on (the upper bridge switching tube and the lower bridge switching tube of the same bridge arm cannot be both turned on), the compensation calculating unit 12 may calculate the compensation value, that is, the U-phase compensation value, by comparing the sampling current of the current detecting chip 15 above the U-phase output wire with the sampling signal of the verifying unit 13. The U-phase compensation value can compensate the U-phase driving current sampled by the current detecting chip 15, thereby improving the accuracy of the U-phase driving current sampling value.
Similarly, the compensation calculating unit 12 may generate the compensation value (i.e., V-phase compensation value) of the current detecting chip 15 above the V-phase output conductor based on the verification signal generated by the verification unit 13 when the upper bridge switching tube U12, the lower bridge switching tubes U21, U23 are turned on simultaneously, or when the upper bridge switching tubes U11, U13, and the lower bridge switching tube U22 are turned on simultaneously; the compensation calculating unit 12 may also generate the compensation value (i.e., the W-phase compensation value) of the current detecting chip 15 above the W-phase output conductor based on the verification signal generated by the verification unit 13 when the upper bridge switching tube U13, the lower bridge switching tube U21, and U22 are turned on simultaneously, or when the upper bridge switching tube U11, U12, and the lower bridge switching tube U23 are turned on simultaneously.
In practical application, the compensation calculating unit 12 may calculate the compensation value of any two phases (i.e., the compensation values of any two current detecting chips 15), and the compensation value of the other phase may be calculated according to each phase relationship of the three-phase currents.
The compensation calculating unit 12 may generate the compensation value of each current detecting chip 15 in a preset period, so that the compensation value may be adjusted in time, so that the sampled driving current is more accurate. Of course, in practical applications, the compensation calculating unit 12 may also generate the compensation value of each current detecting chip 15 at regular time.
As shown in fig. 3, the motor current sampling system according to the second embodiment of the present invention includes a compensation calculating unit 32, a checking unit 33, a current divider 34, and three current detecting chips 35. The compensation calculating unit 32, the verifying unit 33, and the three current detecting chips 35 described above are identical in function and structure to the corresponding parts in the first embodiment.
Unlike the first embodiment, the current divider 34 is connected in series to the positive dc bus of the motor driver (in this case, since the voltage of the current divider 34 is high, the voltage withstanding process should be added between the output of the current divider 34 and the verification unit 33 in consideration of the voltage withstanding of the compensation calculation unit 32). The compensation calculating unit 32 may generate a compensation value (i.e., a U-phase compensation value) of the current detecting chip 35 above the U-phase output conductor based on the verification signal generated by the verification unit 33 when the lower bridge switching tube U21, the upper bridge switching tubes U12, U13 are turned on simultaneously, or when the upper bridge switching tube U11, the lower bridge switching tubes U22, U23 are turned on simultaneously; the compensation calculating unit 32 may generate a compensation value (i.e., a V-phase compensation value) of the current detecting chip 35 above the V-phase output conductor based on the verification signal generated by the verification unit 33 when the lower bridge switching tube U22, the upper bridge switching tubes U11, U13 are turned on simultaneously, or when the upper bridge switching tube U12, the lower bridge switching tubes U21, U23 are turned on simultaneously; the compensation calculating unit 32 may generate the compensation value (i.e., the W-phase compensation value) of the current detecting chip 35 above the W-phase output conductor based on the verification signal generated by the verification unit 33 when the lower bridge switching tube U23, the upper bridge switching tubes U11, U12 are turned on simultaneously, or when the upper bridge switching tube U13, the lower bridge switching tubes U21, U22 are turned on simultaneously.
As shown in fig. 4, the motor current sampling system according to the third embodiment of the present invention includes a compensation calculating unit 42, a checking unit, three current splitters 44, and three current detecting chips 45, wherein the checking unit includes a U-phase checking branch 431, a V-phase checking branch 432, and a W-phase checking branch 433. The compensation calculating unit 42 and the three current detecting chips 45 described above are the same as those of the first embodiment in function and structure. The U-phase checking leg 431, the V-phase checking leg 432, and the W-phase checking leg 433 are respectively identical in function and structure to the checking unit 23 in the first embodiment. In the present embodiment, three shunts 44 are connected in series between the lower bridge switching tubes U21, U22, U23 of the three bridge arms and the negative dc bus, respectively; the U-phase calibration leg 431, V-phase calibration leg 432, and W-phase calibration leg 433 generate calibration signals based on the currents in the three shunts 44, respectively.
The compensation calculating unit 42 may generate a compensation value (i.e., a U-phase compensation value) of the current detection chip 45 above the U-phase output lead based on the check signal of the U-phase check branch 431 when the lower bridge switching tube U21 is turned on; the compensation calculating unit 42 may generate a compensation value (i.e., a V-phase compensation value) of the current detection chip 45 above the V-phase output wire based on the check signal of the V-phase check branch 432 when the lower bridge switching tube U22 is turned on; the compensation calculating unit 42 may also generate a compensation value (i.e., a W-phase compensation value) of the current detecting chip 45 above the W-phase output wire based on the check signal of the W-phase check branch 433 when the lower bridge switching tube U23 is turned on.
In addition, as shown in fig. 5, three shunts 54 may be connected in series between the upper bridge switching tubes U11, U12, U13 of the three bridge arms of the inverter unit 11 and the positive dc bus, and the U-phase calibration branch 531, the V-phase calibration branch 532, and the W-phase calibration branch 533 may generate calibration signals according to the currents in the three shunts 54, respectively. At this time, the compensation calculating unit 52 may generate a compensation value (i.e., a U-phase compensation value) of the current detecting chip 55 above the U-phase output wire based on the check signal of the U-phase check branch 531 when the upper bridge switching tube U11 is turned on; the compensation calculating unit 52 may generate a compensation value (i.e., a V-phase compensation value) of the current detection chip 55 above the V-phase output wire based on the check signal of the V-phase check branch 532 when the upper bridge switching tube U12 is turned on; the compensation calculating unit 52 may also generate a compensation value (i.e., a W-phase compensation value) of the current detecting chip 55 above the W-phase output wire based on the check signal of the W-phase check branch 533 when the upper bridge switching tube U123 is turned on.
The motor current sampling system can be applied to motor drivers adopting three-phase full-bridge inverter circuits and motor drivers adopting other inverter circuits, and only the number of current detection chips and current splitters is required to be adjusted according to specific application scenes.
Fig. 6 is a flow chart of an embodiment of a motor current sampling method of the present invention, which can be performed by a motor driver and is used to sample the driving current output from the motor driver to the motor. The method of the present embodiment includes the steps of:
step S61: the multiphase driving current output by the motor driver is sampled by a plurality of current detection chips, and the plurality of current detection chips are respectively attached to the surface of the printed circuit board and respectively correspond to a plurality of output wires for outputting the driving current (namely, the plurality of current detection chips are respectively positioned above the plurality of output wires).
The current detection chip can adopt a self-made Hall element, namely a low-cost detection chip (low cost means poor detection performance and no additional function), thereby having outstanding cost advantages.
Step S62: a verification signal is generated based on a current flowing through a shunt connected in series to a DC portion in the motor drive.
Specifically, the current splitters may be connected in series to a negative dc bus or a positive dc bus of the motor driver, or may be connected in series between a lower bridge switching tube and the negative dc bus of the inverter unit, respectively, or between an upper bridge switching tube and the positive dc bus of the inverter unit, respectively.
Step S63: and respectively generating compensation values of a plurality of current detection chips based on the check signals and multiphase driving currents sampled by the current detection chips according to the states of switching tubes in the inversion unit of the motor driver.
The process of generating the compensation value can refer to fig. 1, 3, 4 and the corresponding descriptions, and will not be described herein.
The compensation value may be a compensation coefficient, and may be used to compensate the current sampled by the current detection chip in real time (i.e., correct the current obtained by sampling by the current detection chip by using the compensation value) when the state of the switching tube in the inversion unit changes, so as to obtain a phase current value with higher accuracy.
The inverter unit of the motor driver can comprise three bridge arms, and the three bridge arms respectively output U-phase driving current, V-phase driving current and W-phase driving current to the motor; accordingly, in step S51, three current detection chips may be used to sample the three-phase driving currents output from the motor driver. And the compensation values of the plurality of current detection chips may be generated at a preset period. Of course, in practical application, the compensation values of the current detection chips may be generated at regular time.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (8)
1. The motor current sampling system is used for sampling driving current output to a motor by a motor driver and is characterized by comprising a compensation calculation unit, a verification unit, at least one shunt and a plurality of current detection chips; wherein: the current detection chips are respectively attached to the surface of the printed circuit board and respectively correspond to a plurality of output wires used for outputting driving current on the printed circuit board; the current divider is connected in series with a direct current part in the motor driver, and the verification unit generates a verification signal according to the current in the current divider; the compensation calculation unit is used for respectively generating compensation values of the plurality of current detection chips based on the verification signals according to the state of a switching tube in an inversion unit of the motor driver; and the compensation calculating unit generates a compensation value of the current detection chip corresponding to the preset output wire based on the check signal generated by the check unit when the upper bridge switching tube of the bridge arm connected with the preset output wire is conducted and the lower bridge switching tube of the bridge arm connected with other output wires is conducted or when the lower bridge switching tube of the bridge arm connected with the preset output wire is conducted and the upper bridge switching tube of the bridge arm connected with other output wires is conducted.
2. The motor current sampling system of claim 1, wherein the verification unit comprises a voltage conversion circuit and an analog-to-digital conversion circuit, wherein: the voltage conversion circuit is used for boosting the voltages at two ends of the shunt; the analog-to-digital conversion circuit is used for converting the voltage after the boosting processing into the check signal.
3. The motor current sampling system according to claim 1 or 2, wherein the compensation value is a compensation coefficient, and the inverter unit of the motor driver includes three bridge arms and outputs a U-phase drive current, a V-phase drive current, and a W-phase drive current to the motor, respectively, by the three bridge arms; the motor current sampling system comprises three current detection chips, and the three current detection chips are respectively and correspondingly arranged with a U-phase output lead, a V-phase output lead and a W-phase output lead of an inversion unit on the printed circuit board.
4. A motor current sampling system according to claim 3, characterized in that it comprises three of said shunts, and said three shunts are connected in series between the lower bridge switching tubes of the three bridge arms and the negative dc bus, respectively; the verification unit comprises a U-phase verification branch, a V-phase verification branch and a W-phase verification branch, and the U-phase verification branch, the V-phase verification branch and the W-phase verification branch generate verification signals according to currents in the three current splitters respectively;
when a lower bridge switching tube of a bridge arm connected with the U-phase output wire is conducted, the compensation calculating unit generates a compensation value of a current detection chip corresponding to the U-phase output wire based on a verification signal of a U-phase verification branch circuit;
when a lower bridge switching tube of a bridge arm connected with the V-phase output lead is conducted, the compensation calculating unit generates a compensation value of a current detection chip corresponding to the V-phase output lead based on a verification signal of a V-phase verification branch;
and when the lower bridge switching tube of the bridge arm connected with the W-phase output wire is conducted, the compensation calculating unit generates a compensation value of the current detection chip corresponding to the W-phase output wire based on the verification signal of the W-phase verification branch circuit.
5. A motor current sampling system according to claim 3, characterized in that it comprises three of said shunts, and said three shunts are connected in series between the upper bridge switching tubes of the three bridge arms and the positive dc bus, respectively; the verification unit comprises a U-phase verification branch, a V-phase verification branch and a W-phase verification branch, and the U-phase verification branch, the V-phase verification branch and the W-phase verification branch generate verification signals according to currents in the three current splitters respectively;
when an upper bridge switching tube of a bridge arm connected with the U-phase output lead is conducted, the compensation calculating unit generates a compensation value of a current detection chip corresponding to the U-phase output lead based on a verification signal of a U-phase verification branch;
the compensation calculating unit generates a compensation value of a current detection chip corresponding to the V-phase output lead based on a verification signal of a V-phase verification branch when an upper bridge switching tube of a bridge arm connected with the V-phase output lead is conducted;
and when the upper bridge switching tube of the bridge arm connected with the W-phase output lead is conducted, the compensation calculating unit generates a compensation value of the current detection chip corresponding to the W-phase output lead based on the verification signal of the W-phase verification branch.
6. The motor current sampling system according to claim 1, wherein the compensation calculating unit generates the compensation values of the plurality of current detecting chips at preset periods, respectively.
7. A motor current sampling method for sampling a driving current output from a motor driver to a motor, comprising the steps of:
sampling multiphase driving currents output by the motor driver through a plurality of current detection chips respectively, wherein the current detection chips are respectively attached to the surface of the printed circuit board and respectively correspond to a plurality of output wires for outputting the driving currents;
generating a verification signal according to a current flowing through a shunt, the shunt being connected in series with a direct current portion in the motor driver;
respectively generating compensation values of the plurality of current detection chips based on the check signal and the multiphase driving current according to the state of a switching tube in an inversion unit of the motor driver;
the generating the compensation values of the plurality of current detection chips includes: and generating a compensation value of a current detection chip corresponding to the preset output wire based on the verification signal when an upper bridge switching tube of a bridge arm connected with the preset output wire is conducted and a lower bridge switching tube of a bridge arm connected with other output wires is conducted or when a lower bridge switching tube of a bridge arm connected with the preset output wire is conducted and an upper bridge switching tube of a bridge arm connected with other output wires is conducted.
8. The motor current sampling method according to claim 7, wherein the compensation values of the plurality of current detection chips are generated at preset periods, respectively.
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| CN109782045A (en) * | 2018-12-27 | 2019-05-21 | 深圳市优必选科技有限公司 | The current sample method and current sampling system of motor-drive circuit |
| CN110261806B (en) * | 2019-06-14 | 2021-08-31 | 杭州优迈科技有限公司 | Driver, frequency converter, and calibration method and control method of driver |
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