CN113541551B - Three-phase current sampling method, three-phase current sampling device, robot and computer readable storage medium - Google Patents
Three-phase current sampling method, three-phase current sampling device, robot and computer readable storage medium Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/0003—Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control
- H02P21/0017—Model reference adaptation, e.g. MRAS or MRAC, useful for control or parameter estimation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/22—Current control, e.g. using a current control loop
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/12—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation pulsing by guiding the flux vector, current vector or voltage vector on a circle or a closed curve, e.g. for direct torque control
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Abstract
The application belongs to the technical field of current detection, and provides a three-phase current sampling method, a three-phase current sampling device, a robot and a computer readable storage medium, wherein effective conduction time of a first-phase bridge arm, a second-phase bridge arm and a third-phase bridge arm is firstly obtained; then determining effective sampling current in the three-phase inverter circuit according to the space vector angle, the effective conduction time and the shortest effective sampling time of the motor; establishing a current reconstruction model according to a motor d-axis current and a current space transformation formula; and determining the two-phase current of a stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current, so that the two-phase current of the motor at a higher rotating speed and a larger effective PWM pulse width is calculated by the current reconstruction model through three-phase alternate sampling, and accurate acquisition of current information is realized.
Description
Technical Field
The invention belongs to the technical field of current sampling, and particularly relates to a three-phase current sampling method, a three-phase current sampling device, a three-phase current sampling robot and a computer readable storage medium.
Background
In order to realize high-performance control of the servo motor, three-phase current information of the motor must be accurately acquired, and the current common practice is to use a current sensor and a phase sampling resistor sampling scheme, but the two schemes have the problems of high cost, relatively complex hardware design and large occupied volume, and particularly in the robot servo application industry with higher and higher integration level, the two schemes have certain limitations and limit the application of integration. Therefore, in the field of robot servo, the three-phase lower bridge sampling resistor current sampling scheme is widely applied due to the simple hardware design, low cost and small volume.
However, in the three-phase down-bridge sampling resistor current sampling scheme, if three-phase current needs to be correctly collected, the phase current must be required to flow through the sampling resistor, and sampling is usually performed at the zero point of the PWM and at the conduction time of the lower bridge arm.
Disclosure of Invention
In view of the above, embodiments of the present invention provide a three-phase current sampling method, apparatus, robot, and computer readable storage medium, which can solve the problem that in a three-phase lower bridge sampling resistor current sampling scheme, when a motor operates at high speed, a lower bridge arm with a very large PWM effective pulse width can effectively sample current information with a very narrow pulse width, which is insufficient for accurate current information acquisition.
The first aspect of the embodiment of the invention provides a three-phase current sampling method, which respectively performs current sampling on a first phase bridge arm, a second phase bridge arm and a third phase bridge arm of a three-phase inverter circuit through a first sampling resistor, a second sampling resistor and a third sampling resistor, and comprises the following steps:
acquiring effective conduction time of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm;
determining effective sampling current in the three-phase inverter circuit according to a space vector angle of the motor, the effective conduction time and the shortest effective sampling time;
establishing a current reconstruction model according to a motor d-axis current and a current space transformation formula, wherein the motor d-axis current is set as a preset reference current;
and determining the two-phase current of a motor stationary two-phase coordinate system according to the current reconstruction model and the effective sampling current.
In one embodiment, the determining the effective sampling current in the three-phase inverter circuit according to the space vector angle of the motor, the effective conduction time and the shortest effective sampling time includes:
and if the effective conduction time of the first phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the second phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the current flowing through the third phase bridge arm.
In one embodiment, the determining the two-phase current of the stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current includes:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the first current reconstruction model and the current flowing through the third phase bridge arm; the current flowing through the third phase bridge arm is the current of the W axis of the stationary three-phase coordinate system of the motor;
the first current reconstruction model is:
cos(θ)*i α +sin(θ)*i β ＝i d ＝0；
i α ＝i u ＝-i v -i w ；
the two-phase current of the static two-phase coordinate system of the motor is as follows:
wherein ,iα For motor stationary two-phase coordinate system alpha-axis current, i β Beta-axis current, i of motor static two-phase coordinate system μ U-axis current, i of motor static three-phase coordinate system ν For motor stationary three-phase coordinate system V-axis current, i ω For motor stationary three-phase coordinate system W-axis current, i d D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
In one embodiment, the determining the effective sampling current in the three-phase inverter circuit according to the space vector angle of the motor, the effective conduction time and the shortest effective sampling time includes:
and if the effective conduction time of the first phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the third phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the effective sampling current of the second phase bridge arm.
In one embodiment, the determining the two-phase current of the stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current includes:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the second current reconstruction model and the current flowing through the second phase bridge arm; the current flowing through the second-phase bridge arm is the current of a U-axis of a stationary three-phase coordinate system of the motor;
the second current reconstruction model is:
cos(θ)*i α +sin(θ)*i β ＝i d ＝0；
i α ＝i u ；
the two-phase current of the static two-phase coordinate system of the motor is as follows:
i α ＝i u ；
wherein ,iα For motor stationary two-phase coordinate system alpha-axis current, i β Beta-axis current, i of motor static two-phase coordinate system μ U-axis current, i of motor static three-phase coordinate system ν For motor stationary three-phase coordinate system V-axis current, i ω For motor stationary three-phase coordinate system W-axis current, i d D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
In one embodiment, the determining the effective sampling current in the three-phase inverter circuit according to the space vector angle of the motor, the effective conduction time and the shortest effective sampling time includes:
and if the effective conduction time of the second phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the third phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the effective sampling current of the first phase bridge arm.
In one embodiment, the determining the two-phase current of the stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current includes:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the third current reconstruction model and the current flowing through the first phase bridge arm; the current flowing through the second-phase bridge arm is the current of a motor stationary three-phase coordinate system V-axis;
the third current reconstruction model is:
cos(θ)*i α +sin(θ)*i β ＝i d ＝0；
i α ＝i u ；
the two-phase current of the static two-phase coordinate system of the motor is as follows:
wherein ,iα For motor stationary two-phase coordinate system alpha-axis current, i β Beta-axis current, i of motor static two-phase coordinate system μ U-axis current, i of motor static three-phase coordinate system ν For motor stationary three-phase coordinate system V-axis current, i ω For motor stationary three-phase coordinate system W-axis current, i d D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
The second aspect of the present application also provides a three-phase current sampling apparatus, including: the first sampling resistor, the second sampling resistor, the third sampling resistor and the three-phase inverter circuit; the first sampling resistor, the second sampling resistor and the third sampling resistor are respectively used for sampling currents of a first phase bridge arm, a second phase bridge arm and a third phase bridge arm of the three-phase inverter circuit;
the three-phase current sampling apparatus further includes:
the conduction time acquisition unit is used for acquiring the effective conduction time of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm;
the sampling current determining unit is used for determining effective sampling current in the three-phase inverter circuit according to the space vector angle of the motor, the effective conduction time and the shortest effective sampling time;
the current model setting unit is used for establishing a current reconstruction model according to the d-axis current of the motor and a current space transformation formula, wherein the d-axis current of the motor is set as a preset reference current;
and the two-phase current calculation unit is used for determining the two-phase current of the motor stationary two-phase coordinate system according to the current reconstruction model and the effective sampling current.
The third aspect of the present application also provides a robot comprising: a motor; and a control unit that samples three-phase currents of the motor using the three-phase current sampling method according to any one of the above, and drives the motor according to the sampling result.
A fourth aspect of the present application also provides a computer readable storage medium storing a computer program which, when executed by a processor, performs the steps of the method as claimed in any one of the preceding claims.
The embodiment of the invention provides a three-phase current sampling method, a three-phase current sampling device, a robot and a computer readable storage medium, wherein the effective conduction time of a first-phase bridge arm, a second-phase bridge arm and a third-phase bridge arm is firstly obtained; then determining effective sampling current in the three-phase inverter circuit according to the space vector angle, the effective conduction time and the shortest effective sampling time of the motor; establishing a current reconstruction model according to the d-axis current of the motor and a current space transformation formula, wherein the d-axis current of the motor is set to be 0; and determining the two-phase current of a stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current, so that the two-phase current of the motor at a higher rotating speed and a larger effective PWM pulse width is calculated by the current reconstruction model through three-phase alternate sampling, and accurate acquisition of current information is realized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a motor driving circuit according to an embodiment of the present application;
fig. 2 is a schematic waveform diagram of PWM according to an embodiment of the present application;
FIG. 3 is a space vector diagram provided in an embodiment of the present application;
fig. 4 is a schematic flow chart of a three-phase current sampling method according to an embodiment of the present application;
fig. 5 is a schematic flow chart of another three-phase current sampling method according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a three-phase current sampling device according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of a robot according to an embodiment of the present application.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved by the present application more clear, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the present application and simplify description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be configured and operated in a particular orientation, and therefore should not be construed as limiting the present application.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In order to illustrate the technical scheme of the invention, the following description is made by specific examples.
A schematic diagram of the motor drive circuit is shown in fig. 1, wherein the pulse width modulated signal UH, UL, VH, VL, WH, WL is the 3-way complementary PWM output by the servo driver to control the motor operation. RU, RV, RW are three-phase lower bridge current sampling resistors, and when the lower bridge arm is on, i.e. UL, VL, WL is high, current flows through the corresponding sampling resistor. In the sampling process, as shown in fig. 2, the phase current can be correctly collected by triggering the AD conversion at the point P2, but the PWM pulse width of the motor can be continuously changed in the space operation process, as shown in the space vector diagram of fig. 3, the motor magnetic poles are operated to different space positions, and the corresponding PWM pulse width can be different. Along with the rising of the motor rotating speed, the width of the effective PWM pulse width becomes wider and wider, the time for the effective sampling of the lower bridge arm becomes narrower and narrower, so that the accurate sampling of the three-phase current cannot be met, and after the sampling time window reaches the limit, the effective PWM pulse width cannot be continuously increased, so that the motor rotating speed cannot be continuously increased, the voltage utilization rate is low, and the whole performance of the servo motor cannot be exerted.
Because the servo motor control only needs to correctly acquire two-phase current, the current sampling is performed in a three-phase alternating sampling mode, and the motor control is performed by judging and switching the effectively acquired two-phase current in real time through a three-phase pulse width modulation signal (PWM). When the space vector is 60 degrees, 180 degrees and 300 degrees, the running rotating speed of the motor is higher, and when the effective PWM pulse width is larger, the current which can be effectively collected is only one phase, and at the moment, the current is calculated by adopting the current reconstruction model in the application, so that the motor is controlled; and compensating for the delay of current sampling by triggering an AD sampling and converting method by corresponding time delay of a PWM zero crossing point.
The embodiment of the invention provides a three-phase current sampling method, which is used for respectively sampling currents of a first phase bridge arm, a second phase bridge arm and a third phase bridge arm of a three-phase inverter circuit through a first sampling resistor RU, a second sampling resistor RV and a third sampling resistor RW.
Referring to fig. 4, the three-phase current sampling method includes steps S10, S20, S30, and S40.
In step S10, effective conduction times of the first phase leg, the second phase leg, and the third phase leg are obtained.
In this embodiment, the effective conduction time of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm is related to the motor rotation speed, for example, when the space vector is 60 °, 180 °, 300 °, and the motor operation rotation speed is higher, the smaller the effective conduction time is when the effective PWM pulse width is larger.
In step S20, an effective sampling current in the three-phase inverter circuit is determined according to a space vector angle of the motor, the effective conduction time, and a shortest effective sampling time.
In this embodiment, as can be seen from fig. 2, 3 and 5, when the space vector is 60 °, 180 ° and 300 °, and the running speed of the motor is higher, and the effective PWM pulse width is larger, the current that can be effectively collected has only one phase, for example, when the running speed of the motor is higher, the effective conduction time of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm, where the effective conduction time of only one phase of the lower bridge arm is greater than the shortest effective sampling time, and at this time, the phase current whose effective conduction time is greater than the most effective sampling time is the effective sampling current, and the shortest effective sampling time is determined by the devices, the manufacturing process, and the like adopted by the inverter circuit.
Referring to fig. 5, when the effective on time TUL of the first phase bridge arm is greater than the shortest effective sampling time Ti and the effective on time TVL of the second phase bridge arm is greater than the shortest effective sampling time Ti, the sampling current of the first phase (U-phase) and the sampling current of the second phase (V-phase) are both effective sampling currents, and at this time, according to the three-phase current calculation formula iv+iv+iu=0, iw= -IU-IV, IU is the actual current of the U-phase, IV is the actual current of the V-phase, and IW is the actual current of the W-phase.
Referring to fig. 5, when the effective on time TUL of the first phase bridge arm is greater than the shortest effective sampling time Ti and the effective on time TWL of the third phase bridge arm is greater than the shortest effective sampling time Ti, the sampling currents of the first phase (U-phase) and the third phase (W-phase) are both effective sampling currents, and at this time, according to the three-phase current calculation formula iv+iv+iu=0, iv= -IU-IW is obtained, IU is the actual current of the U-phase, IV is the actual current of the V-phase, and IW is the actual current of the W-phase.
Referring to fig. 5, when the effective on time TVL of the second phase leg is greater than the shortest effective sampling time Ti, and the effective on time TWL of the third phase leg is greater than the shortest effective sampling time Ti, the sampling current of the second phase (V-phase) and the sampling current of the third phase (W-phase) are both effective sampling currents, and at this time, iu= -IW-IV can be obtained according to the three-phase current calculation formula iv+iv+iu=0, IU is the actual current of the U-phase, IV is the actual current of the V-phase, and IW is the actual current of the W-phase.
In step S30, a current reconstruction model is established according to a motor d-axis current and a current space transformation formula, wherein the motor d-axis current is set as a preset reference current.
In this embodiment, the preset reference current may be set to 0.
In step S40, two-phase currents of a stationary two-phase coordinate system of the motor are determined according to the current reconstruction model and the effective sampling current.
When the space vector angle is 60 degrees, 180 degrees and 300 degrees or is close to the angle, only one phase of effective current can be acquired at the moment, the servo motor adopts a vector control method with d-axis equal to 0, and when the motor runs at high speed, only one phase of effective current can be acquired at the moment, so that the d-axis current output by the motor at the moment can be considered to be 0 based on the moment.
In this embodiment, through the current reconstruction model preset in the present application, the stationary two-phase current of the motor can be obtained according to the one-phase effective sampling current, and since the servo motor control only needs to correctly collect the two-phase current, in this embodiment, the current sampling is performed by adopting a three-phase alternate sampling mode, and the effective two-phase current is obtained through the three-phase PWM pulse width and the current reconstruction model, so that the motor current closed-loop control can be realized.
In one embodiment, in step S20, the determining the effective sampling current in the three-phase inverter circuit according to the space vector angle of the motor, the effective on-time, and the shortest effective sampling time includes:
and if the effective conduction time of the first phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the second phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the current flowing through the third phase bridge arm.
In one embodiment, in step S40, the determining the two-phase current of the stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current includes:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the first current reconstruction model and the current flowing through the third phase bridge arm; the current flowing through the third phase bridge arm is the current of the W axis of the stationary three-phase coordinate system of the motor;
the first current reconstruction model is:
cos(θ)*i α +sin(θ)*i β ＝i d ＝0；
i α ＝i u ＝-i v -i w ；
the two-phase current of the static two-phase coordinate system of the motor is as follows:
wherein ,iα For motor stationary two-phase coordinate system alpha-axis current, i β Beta-axis current, i of motor static two-phase coordinate system μ U-axis current, i of motor static three-phase coordinate system ν For motor stationary three-phase coordinate system V-axis current, i ω For motor stationary three-phase coordinate system W-axis current, i d D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
In this embodiment, since the effective on time tur of the first phase bridge arm and the effective on time TVL of the second phase bridge arm are both smaller than the shortest effective sampling time Ti, when the space vector angle is 60 ° or close to this angle, the current that can be effectively collected at this time is the third phase (W-phase), the first current reconstruction model can be obtained according to the setting that the d-axis current is zero and the current space transformation formula, and the stationary two-phase current of the motor can be calculated based on the three calculation formulas in the first current reconstruction model.
In one embodiment, the determining the effective sampling current in the three-phase inverter circuit according to the space vector angle of the motor, the effective conduction time and the shortest effective sampling time includes:
and if the effective conduction time of the first phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the third phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the effective sampling current of the second phase bridge arm.
In one embodiment, the determining the two-phase current of the stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current includes:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the second current reconstruction model and the current flowing through the second phase bridge arm; the current flowing through the second-phase bridge arm is the current of a U-axis of a stationary three-phase coordinate system of the motor;
the second current reconstruction model is:
cos(θ)*i α +sin(θ)*i β ＝i d ＝0；
i α ＝i u ；
the two-phase current of the static two-phase coordinate system of the motor is as follows:
i α ＝i u ；
wherein ,iα For motor stationary two-phase coordinate system alpha-axis current, i β Beta-axis current, i of motor static two-phase coordinate system μ U-axis current, i of motor static three-phase coordinate system ν For motor stationary three-phase coordinate system V-axis current, i ω For motor stationary three-phase coordinate system W-axis current, i d D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
In this embodiment, since the effective on time tur of the first phase bridge arm and the effective on time TWL of the third phase bridge arm are both smaller than the shortest effective sampling time Ti, when the space vector angle is 180 ° or close to this angle, the current that can be effectively collected at this time is the second phase (V-phase), the second current reconstruction model can be obtained according to the setting that the d-axis current is zero and the current space transformation formula, and the stationary two-phase current of the motor can be calculated based on the three calculation formulas in the second current reconstruction model.
In one embodiment, the determining the effective sampling current in the three-phase inverter circuit according to the space vector angle of the motor, the effective conduction time and the shortest effective sampling time includes:
and if the effective conduction time of the second phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the third phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the effective sampling current of the first phase bridge arm.
In one embodiment, the determining the two-phase current of the stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current includes:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the third current reconstruction model and the current flowing through the first phase bridge arm; the current flowing through the second-phase bridge arm is the current of a motor stationary three-phase coordinate system V-axis;
the third current reconstruction model is:
cos(θ)*i α +sin(θ)*i β ＝i d ＝0；
i α ＝i u ；
the two-phase current of the static two-phase coordinate system of the motor is as follows:
wherein ,iα For motor stationary two-phase coordinate system alpha-axis current, i β Beta-axis current, i of motor static two-phase coordinate system μ U-axis current, i of motor static three-phase coordinate system ν For motor stationary three-phase coordinate system V-axis current, i ω For motor stationary three-phase coordinate system W-axis current, i d D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
In this embodiment, since the effective on time TVL of the second phase leg and the effective on time TWL of the third phase leg are both smaller than the shortest effective sampling time Ti, when the space vector angle is 300 ° or is close to this angle, the current that can be effectively collected at this time is the first phase (U-phase), the third current reconstruction model can be obtained according to the setting that the d-axis current is zero and the current space transformation formula, and the stationary two-phase current of the motor can be calculated based on the three calculation formulas in the third current reconstruction model.
The embodiment of the application also provides a three-phase current sampling device, which comprises: the circuit comprises a first sampling resistor RU, a second sampling resistor RV, a third sampling resistor RW and a three-phase inverter circuit; the first sampling resistor RU, the second sampling resistor RV and the third sampling resistor RW are respectively used for sampling currents of a first phase bridge arm, a second phase bridge arm and a third phase bridge arm of the three-phase inverter circuit.
In the present embodiment, referring to fig. 6, the three-phase current sampling apparatus 50 further includes: an on-time acquisition unit 501, a sampling current determination unit 502, a current model setting unit 503, a two-phase current calculation unit 504; the on-time obtaining unit 501 is configured to obtain effective on-times of the first phase leg, the second phase leg, and the third phase leg; the sampling current determining unit 502 is configured to determine an effective sampling current in the three-phase inverter circuit according to a space vector angle of the motor, the effective conduction time, and a shortest effective sampling time; the current model setting unit 503 is configured to establish a current reconstruction model according to a motor d-axis current and a current space transformation formula, where the motor d-axis current is set as a preset reference current; the two-phase current calculation unit 504 is configured to determine two-phase currents of a stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current.
In this embodiment, the effective conduction time of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm is obtained through the conduction time obtaining unit 501, and then the sampling current determining unit 502 determines the effective sampling current in the three-phase inverter circuit according to the space vector angle, the effective conduction time and the shortest effective sampling time of the motor; the current model setting unit 503 establishes a current reconstruction model according to the motor d-axis current and the current space transformation formula, and the motor d-axis current is set as a preset reference current, and the preset reference current may be 0; the two-phase current calculation unit 504 determines the two-phase current of the stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current, so that the two-phase current of the motor at a high rotating speed and a high effective PWM pulse width is calculated by the current reconstruction model through three-phase alternate sampling, and accurate collection of current information is realized.
The embodiment of the application also provides a robot, which comprises: a motor; and a control unit that samples three-phase currents of the motor using the three-phase current sampling method according to any one of the above, and drives the motor according to the sampling result.
Embodiments of the present application also provide a computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of the method according to any one of the preceding claims.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment can be integrated in one control unit, or each unit can exist alone physically, or two or more units are integrated in one unit, and the integrated units can be realized in a form of hardware or a form of a software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the embodiments provided in the present application, it should be understood that the disclosed robot and method may be implemented in other ways. For example, the robotic embodiments described above are merely illustrative. For example, the division of a module or unit is merely a logical function division, and there may be another division manner when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one control unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated modules/units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present application may implement all or part of the flow of the method of the above embodiment, or may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, where the computer program, when executed by a processor, may implement the steps of each of the method embodiments described above. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, executable files or in some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth. It should be noted that the content of the computer readable medium can be appropriately increased or decreased according to the requirements of the jurisdiction's jurisdiction and the patent practice, for example, in some jurisdictions, the computer readable medium does not include electrical carrier signals and telecommunication signals according to the jurisdiction and the patent practice.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (8)
1. The three-phase current sampling method is characterized by comprising the steps of respectively carrying out current sampling on a first phase bridge arm, a second phase bridge arm and a third phase bridge arm of a three-phase inverter circuit through a first sampling resistor, a second sampling resistor and a third sampling resistor, and comprising the following steps:
acquiring effective conduction time of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm;
determining the effective sampling current in the three-phase inverter circuit according to the space vector angle of the motor, the effective conduction time and the shortest effective sampling time comprises: if the effective conduction time of the first phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the second phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the current flowing through the third phase bridge arm;
establishing a current reconstruction model according to a motor d-axis current and a current space transformation formula, wherein the motor d-axis current is set as a preset reference current;
determining two-phase currents of a stationary two-phase coordinate system of the motor according to the current reconstruction model and the effective sampling current;
the determining the two-phase current of the motor stationary two-phase coordinate system according to the current reconstruction model and the effective sampling current comprises the following steps:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the first current reconstruction model and the current flowing through the third phase bridge arm; the current flowing through the third phase bridge arm is the current of the W axis of the stationary three-phase coordinate system of the motor;
the first current reconstruction model is:
the two-phase current of the static two-phase coordinate system of the motor is as follows:
wherein ,
for motor stationary two-phase coordinate system alpha-axis current, < >>
β -axis current for stationary two-phase coordinate system of motor, +.>
U-axis current of motor static three-phase coordinate system, < >>
For motor stationary three-phase coordinate system V-axis current, +.>
W-axis current of motor static three-phase coordinate system, < >>
D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
2. The method of claim 1, wherein determining the effective sampling current in the three-phase inverter circuit based on the spatial vector angle of the motor, the effective on-time, and the shortest effective sampling time comprises:
and if the effective conduction time of the first phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the third phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the effective sampling current of the second phase bridge arm.
3. The method of three-phase current sampling according to claim 2, wherein said determining the two-phase current of the stationary two-phase coordinate system of the motor from the current reconstruction model and the effective sampling current comprises:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the second current reconstruction model and the current flowing through the second phase bridge arm; the current flowing through the second-phase bridge arm is the current of a U-axis of a stationary three-phase coordinate system of the motor;
the second current reconstruction model is:
the two-phase current of the static two-phase coordinate system of the motor is as follows:
wherein ,
for motor stationary two-phase coordinate system alpha-axis current, < >>
For stationary two-phase coordinates of the motorIs beta-axis current, ">
U-axis current of motor static three-phase coordinate system, < >>
D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
4. The method of claim 1, wherein determining the effective sampling current in the three-phase inverter circuit based on the spatial vector angle of the motor, the effective on-time, and the shortest effective sampling time comprises:
and if the effective conduction time of the second phase bridge arm is smaller than the shortest effective sampling time and the effective conduction time of the third phase bridge arm is smaller than the shortest effective sampling time, the effective sampling current is the effective sampling current of the first phase bridge arm.
5. The method of three-phase current sampling according to claim 4, wherein said determining two-phase currents of a stationary two-phase coordinate system of a motor from said current reconstruction model and said effective sampled currents comprises:
calculating the two-phase current of a stationary two-phase coordinate system of the motor according to a third current reconstruction model and the current flowing through the first phase bridge arm;
the third current reconstruction model is:
the two-phase current of the static two-phase coordinate system of the motor is as follows:
wherein ,
for motor stationary two-phase coordinate system alpha-axis current, < >>
β -axis current for stationary two-phase coordinate system of motor, +.>
U-axis current of motor static three-phase coordinate system, < >>
For motor stationary three-phase coordinate system V-axis current, +.>
D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
6. A three-phase current sampling apparatus, comprising: the first sampling resistor, the second sampling resistor, the third sampling resistor and the three-phase inverter circuit; the first sampling resistor, the second sampling resistor and the third sampling resistor are respectively used for sampling currents of a first phase bridge arm, a second phase bridge arm and a third phase bridge arm of the three-phase inverter circuit;
the three-phase current sampling apparatus further includes:
the conduction time acquisition unit is used for acquiring the effective conduction time of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm;
the sampling current determining unit is configured to determine an effective sampling current in the three-phase inverter circuit according to a space vector angle of the motor, the effective conduction time and a shortest effective sampling time, and includes: the effective conduction time of the first-phase bridge arm is smaller than the shortest effective sampling time, and the effective conduction time of the second-phase bridge arm is smaller than the shortest effective sampling time, so that the effective sampling current is the current flowing through the third-phase bridge arm;
the current model setting unit is used for establishing a current reconstruction model according to the d-axis current of the motor and a current space transformation formula, wherein the d-axis current of the motor is set as a preset reference current;
the two-phase current calculation unit is configured to determine, according to the current reconstruction model and the effective sampling current, two-phase currents of a stationary two-phase coordinate system of the motor, including: calculating the two-phase current of a stationary two-phase coordinate system of the motor according to the first current reconstruction model and the current flowing through the third phase bridge arm; the current flowing through the third phase bridge arm is the current of the W axis of the stationary three-phase coordinate system of the motor;
the first current reconstruction model is:
the two-phase current of the static two-phase coordinate system of the motor is as follows:
wherein ,
for motor stationary two-phase coordinate system alpha-axis current, < >>
β -axis current for stationary two-phase coordinate system of motor, +.>
U-axis current of motor static three-phase coordinate system, < >>
For motor stationary three-phase coordinate system V-axis current, +.>
W-axis current of motor static three-phase coordinate system, < >>
D-axis current of a two-phase coordinate system for motor rotation, and theta is the angle of a magnetic pole of the motor.
7. A robot, comprising: a motor; and a control unit that samples three-phase currents of the motor using the three-phase current sampling method according to any one of claims 1 to 5, and drives the motor according to the sampling result.
8. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the method according to any one of claims 1-5.
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Effective date of registration: 20231208 Address after: Room 601, 6th Floor, Building 13, No. 3 Jinghai Fifth Road, Beijing Economic and Technological Development Zone (Tongzhou), Tongzhou District, Beijing, 100176 Patentee after: Beijing Youbixuan Intelligent Robot Co.,Ltd. Address before: 518000 16th and 22nd Floors, C1 Building, Nanshan Zhiyuan, 1001 Xueyuan Avenue, Nanshan District, Shenzhen City, Guangdong Province Patentee before: Shenzhen UBTECH Technology Co.,Ltd. |