CN117240164A - Control method for motor, electronic device and vehicle - Google Patents

Abstract

Embodiments of the present disclosure provide a control method for a motor, an electronic device, a computer-readable storage medium, and a vehicle. The control method comprises the following steps: converting a measured rotational speed of the motor based on a measured bus voltage of an inverter, the inverter configured to drive the motor; determining a direct-axis current value satisfying a maximum torque-to-current ratio based on the torque command and the converted rotational speed; adjusting the direct-axis current value based on the modulation ratio command and the real-time modulation ratio; and generating a control signal for the inverter based on the adjusted direct-axis current value. The scheme of the present disclosure can improve the dynamic performance of the system without increasing the occupation of the storage space, and improve the stability and reliability of the system.

Description

Control method for motor, electronic device and vehicle

Technical Field

Embodiments of the present disclosure relate to the field of motor control, and more particularly, to a control method for a motor, an electronic apparatus, a readable storage medium, and a vehicle including the electronic apparatus.

Background

Drive motors such as permanent magnet synchronous motors are widely used in the fields of transportation, home appliances, industrial manufacturing, and the like. For example, an electric motor, such as an in-line permanent magnet synchronous motor, may be employed in an electric vehicle to drive the vehicle. Such motors typically encounter various operating conditions. In some conditions, such as when the motor is running at high speed or the bus voltage is reduced, the stator terminal voltage will not provide the back emf required in the current conditions due to bus voltage limitations. In this case, the motor speed may be continuously increased by weakening the equivalent rotor flux so that the motor operates in a constant power region. When the motor is switched from a constant torque zone to a constant power zone, the motor is operated in a weak magnetic zone. At this time, especially under the deep field weakening operation condition, a corresponding field weakening control method or algorithm is needed to adapt to the requirement of the high-speed field weakening region.

The current flux weakening control strategy has more problems and disadvantages. For example, it takes up a lot of memory space and calibration effort is enormous; alternatively, the convergence rate is too slow, resulting in insufficient dynamic performance of the system, and poor reliability and stability.

Disclosure of Invention

Based on the above-described problems, according to example embodiments of the present disclosure, there are provided a control method for a motor, an electronic apparatus, a computer-readable storage medium, and a vehicle.

In a first aspect of the present disclosure, there is provided a control method for an electric motor, the control method comprising: converting a measured rotational speed of the motor based on a measured bus voltage of an inverter, the inverter configured to drive the motor; determining a direct-axis current value satisfying a maximum torque-to-current ratio based on the torque command and the converted rotational speed; adjusting the direct-axis current value based on the modulation ratio command and the real-time modulation ratio; and generating a control signal for the inverter based on the adjusted direct-axis current value.

In a second aspect of the present disclosure, there is provided an electronic device comprising: a processor; and a memory coupled to the processor, the memory having instructions stored therein that, when executed by the processor, cause the electronic device to perform actions comprising: converting a measured rotational speed of the motor based on a measured bus voltage of an inverter, the inverter configured to drive the motor; determining a direct-axis current value satisfying a maximum torque-to-current ratio based on the torque command and the converted rotational speed; adjusting the direct-axis current value based on the modulation ratio command and the real-time modulation ratio; and generating a control signal for the inverter based on the adjusted direct-axis current value.

In a third aspect of the present disclosure, there is provided a vehicle comprising: a motor for driving the vehicle to move; and an electronic device according to the second aspect.

In a fourth aspect of the present disclosure, there is provided a computer readable medium having computer readable instructions stored thereon, which when executed by a processing unit, cause the processing unit to perform the control method according to the first aspect.

It should be understood that what is described in this summary is not intended to limit the critical or essential features of the embodiments of the disclosure nor is it intended to limit the scope of the disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

The above and other features, advantages and aspects of embodiments of the present disclosure will become more apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, wherein like or similar reference numerals denote like or similar elements, in which:

fig. 1 shows a schematic diagram of an electric motor system in which embodiments of the present disclosure may be implemented.

Fig. 2 illustrates a vector diagram of a motor under steady state operating conditions according to an embodiment of the present disclosure.

Fig. 3 illustrates a transition of the motor from maximum torque to field control to field weakening control in accordance with an embodiment of the present disclosure.

Fig. 4 shows a schematic block diagram of a control device according to an embodiment of the present disclosure.

Fig. 5 shows a schematic block diagram of control modules in a control device according to an embodiment of the disclosure.

Fig. 6 shows a schematic flow chart of a control method for an electric machine according to an embodiment of the disclosure.

FIG. 7 shows a schematic block diagram of an example device that may be used to implement embodiments of the present disclosure.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure have been shown in the accompanying drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustration purposes only and are not intended to limit the scope of the present disclosure.

In describing embodiments of the present disclosure, the term "comprising" and its like should be taken to be open-ended, i.e., including, but not limited to. The term "based on" should be understood as "based at least in part on". The term "one embodiment/implementation" or "this embodiment/implementation" should be understood as "at least one embodiment/implementation". The terms "first," "second," and the like, may refer to different or the same object. Other explicit and implicit definitions are also possible below.

Fig. 1 illustrates a schematic diagram of an electric machine system 1000 in which embodiments of the present disclosure may be implemented. As shown in fig. 1, the motor system 1000 includes a motor 100 and an inverter 200. As an example, the motor 100 may be a permanent magnet synchronous motor, such as an in-line permanent magnet synchronous motor. It will be appreciated that the type of motor 100 is not limited thereto and may be other types of motors that enable field weakening control. The inverter 200 is connected to a bus capacitor and a direct current power source such as an in-vehicle battery on its direct current side to receive a direct current voltage, and is connected to stator windings of the motor 100 on its alternating current side to supply stator currents to the stator windings and thus generate a stator magnetic field that drives the motor rotor to rotate.

The motor system 1000 includes a control device 300. The control device 300 may receive various measurement signals in the system, such as packetsIncluding a position sensing signal of the motor rotor and a voltage u input to the stator winding by the inverter 200 _a 、u _b 、u _c And current i _a 、i _b 、i _c Measurement signal related to bus voltage U of inverter 200 _dc Related measurement signals, and other necessary measurement signals. Further, the control device 300 may output a control signal CTR to the inverter 200 to control on and off of switching devices in the inverter 200, thereby controlling an amount of electricity (e.g., power, voltage, and/or current) applied to the stator windings of the motor 100 by the inverter 200 to achieve driving of the motor 100.

Although the motor system 1000 shown in fig. 1 is a three-phase system, other phase number systems are also possible, and the present disclosure is not limited thereto. The operation of the motor system 1000 will be described below using a three-phase permanent magnet synchronous motor as an example.

The phase voltage equation of the motor 100 as a three-phase permanent magnet synchronous motor can be expressed as follows:

u _d ＝(R _s +L _d p)i _d -ωL _q i _q (1)

u _q ＝(R _s +L _q p)i _q +ω(ψ _f +L _d i _d ) (2)

wherein u is _d And u _q The direct (i.e., d-axis) and quadrature (i.e., q-axis) voltages, i, respectively, of motor 100 _d And i _q Respectively d-axis current and q-axis current, R _s Is the stator resistance, L _d And L _q Respectively d-axis inductance and q-axis inductance, ω being rotor speed, ψ _f Is a permanent magnet flux linkage and p is a differential operator.

When the motor 100 is in the high-speed steady-state condition, the transformer electromotive force L _d pi _d And L _q pi _q Both zero, equations (1) and (2) can be simplified as follows:

u _d ＝R _s i _d -ωL _q i _q (3)

u _q ＝R _s i _q +ω(ψ _f +L _d i _d ) (4)

when the motor is operated in a high-speed region, the stator resistance R is increased due to the large rotor speed omega _s Relatively small, and thus can reduce the resistance drop R _s i _d And R is _s i _q Neglecting, and considering only the terminal voltages generated by the transformer electromotive force and the rotating electromotive force, equations (3) and (4) can be further simplified as follows:

u _d ≈-ωL _q i _q (5)

u _q ≈ω(ψ _f +L _d i _d ) (6)

the output voltage of inverter 200 is subjected to bus voltage U _dc Therefore the stator phase voltage amplitude u _s Should not be greater than the phase voltage amplitude limit value u _slimit . That is, the phase voltage amplitude u _s The following equation needs to be satisfied:

wherein, when the motor 100 is controlled in a space vector pulse width modulation (Space Vector Pulse Width Modulation, SVPWM) mode,taking into account the influence of the dead-zone voltage and leaving a certain margin for the system, it is possible to make +.>Wherein DeltaU _L Can be designed to a nominal amount and is typically set to 5-10V.

In addition to the phase voltage amplitude u _s The stator phase current amplitude i is outside the limits of the bus voltage _s Is also limited by the current capability that both the switching devices (e.g., insulated gate bipolar transistor IGBTs) of inverter 200 and motor 100 can withstand, and should not be greater than phase current magnitude limit i _slimit That is, the stator phase current i _s The following equation needs to be satisfied:

equation (8) may also be referred to as the current limit circle equation.

When equation (5) and equation (6) are substituted into equation (7), the following equation can be obtained:

equation (9) may be further sorted to obtain the voltage limit elliptic equation as follows:

wherein the radius of the transverse axis of the ellipse isThe radius of the longitudinal axis is +.>And the transverse axis radius is greater than the longitudinal axis radius.

In addition, the stator phase current amplitude i is constrained by a voltage limit ellipse _s The following equation also needs to be satisfied:

as can be seen from the combination of equations (8) and (11), the stator phase current i _s Constrained by both the current limit circle and the voltage limit ellipse, and the smaller of the two can be taken as the maximum limit value for the stator phase current, namely:

under medium and low speed conditions, motor 100 may be controlled using a maximum torque to current ratio (Maximum Torque Per Ampere, MTPA). The MTPA control can minimize stator current under conditions that meet motor output torque, thereby providing the advantage of reduced system losses. However, when the motor speed is high, the back emf of the motor will rise. Due to the bus voltage U _dc The actual torque will not be able to maintain too high a torque request to enter the constant power zone from the constant torque zone, which results in that the MTPA control will no longer be applicable to the rotational speed range after the inflection point of the transition from the constant torque zone to the constant power zone. In this case, the d-axis current i can be adjusted _d To weaken the action of the permanent magnet flux linkage of the rotor to meet the constant power. In other words, an increase in the rotational speed range can be achieved by a field weakening control strategy.

As an example, the voltage vector equation of the in-line permanent magnet synchronous motor for a vehicle under steady-state operation can be expressed as:

Fig. 2 shows a vector diagram of the motor under steady state conditions plotted according to equation (13), and fig. 3 shows the transition of the motor from MTPA control to field weakening control. As shown in FIG. 2, when entering the field weakening region, the motor speed is high and ωL _d i _d Larger and vector synthesized phase voltage vectorIs>The phase ratio becomes smaller. It can be seen that the stator terminal voltage will be smaller in the field weakening region. As shown in FIG. 3, motor 100 will eventually transition from MTPA control mode to maximum torque to voltage ratio (Maximum Torque Per Volt, MTPV) control mode along the path of O-A-B-C-D-E as the rotational speed increases, where O-A-B-C belongs to MTPA control, C-D-E belongs to field weakening control, and D-E belongs to field weakening controlMTPV control in control.

In one conventional approach, to achieve a smooth transition from MTPA control to MTPV control, a one-dimensional table conforming to the MTPA control strategy may be searched for a direct axis current reference value corresponding to the target torque, i.e., the MTPA direct axis current value is searched for using only the torque command. And then, the direct-axis current reference value is regulated to a direct-axis current reference value meeting the maximum torque-voltage ratio under the current rotating speed, torque and voltage working conditions by using a loop regulator according to the maximum phase voltage output capacity control strategy, so that the field weakening control is realized. In this manner, a loop is required to converge from the MTPA direct current reference to the direct current reference conforming to the field weakening control or MTPV. In some cases, the direct-axis current value given by the one-dimensional table is far from the direct-axis current required by the field weakening control or the MTPV, so that it may take a long time to achieve such convergence, which slows down the tracking performance of the subsequent current loop, leads to poor dynamic performance of the system, and affects the convergence speed and stability of the system as a whole.

In another conventional approach, bus voltage, speed and torque may be used to construct a three-dimensional table of field weakening control. In the three-dimensional table, a torque is an x-axis coordinate, a rotational speed is a y-axis coordinate, a busbar voltage is a z-axis coordinate, and a direct current value is a search target. In this way, a large number of two-dimensional tables having the x-axis coordinates of torque and the y-axis coordinates of rotation speed are created for each voltage class, and then the search current target values for each voltage class are subjected to a difference operation. It can be seen that this requires a large amount of computer memory, the calibration effort is enormous, and the existence of the difference error seriously affects the accuracy and stability of the control system.

Embodiments of the present disclosure provide an improved motor control scheme. In this development, the direct-axis current value satisfying the maximum torque-to-current ratio is determined using the rotational speed converted from the current bus voltage, so that the determined direct-axis current value satisfying the maximum torque-to-current ratio is correlated with the current bus voltage and thus more closely approximates the MTPA direct-axis current value under the current bus voltage operating condition. Thus, the modulation ratio feedback loop can be made to converge quickly to the direct-axis current value required for the field weakening control, which improves the dynamic response characteristics of the system and improves the stability and reliability of the system.

Fig. 4 shows a schematic block diagram of a control device 300 according to an embodiment of the present disclosure, and fig. 5 shows a schematic block diagram of a control module 310 in the control device 300. The control device 300 may be used to implement control for the motor 100. It should be noted that the internal configuration of the control device 300 shown in fig. 4 and 5 is merely exemplary, and the internal configuration thereof may be appropriately adjusted as needed, for example, some modules and sub-modules may be added, removed, or replaced. Furthermore, it is understood that the control device 300 may be implemented in software, for example, each module and sub-module may be implemented in program code executable by a computing device, so that they may be stored in a storage device to be executed by the computing device, or they may be fabricated separately into each integrated circuit module, or a plurality of modules may be implemented as a single integrated circuit module. Furthermore, the control device 300 may be implemented in any other suitable way, for example in hardware circuitry, such as analog circuitry or digital circuitry, or in a combination of software and hardware. The control process will be described in detail further below with reference to fig. 4 and 5.

According to an embodiment of the present disclosure, the control module 310 may include a calculation sub-module 311, and the calculation sub-module 311 may be based on the measured bus voltage U of the inverter 200 _dc To convert the measured rotational speed ω of the motor 100. As an example, the control device 300 may receive a measurement signal representing the current bus voltage magnitude of the inverter 200 to determine the measured bus voltage U _dc . The control device 300 may also acquire position sensing information or signals of the motor rotor to determine the measured rotational speed ω and rotational angle θ of the motor rotor. The position information of the rotor may be acquired in an appropriate manner, for example, by providing a position sensor, or by no position sensor. The control device 300 can measureBus voltage U _dc And a calculation sub-module 311 for providing the measured rotational speed ω to the control module 310 such that the calculation sub-module 311 converts the rotational speed ω of the motor according to the current bus voltage. In this way, there is a correlation of the converted rotational speed ω with the current bus voltage, i.e. the converted rotational speed will contain not only information of the current motor rotational speed but also information of the current bus voltage.

In some embodiments of the present disclosure, the calculation sub-module 311 is based on a predetermined bus voltage U _{dc_Pre} And measuring bus voltage U _dc To convert the measured rotational speed ω. As an example, the measured rotational speed ω may be converted according to the following equation:

thereby, the measured rotational speed ω is converted into rotational speed ω _conv . In this way, the measured bus voltage U can be measured _dc The current rotation speed omega is converted into the preset busbar voltage U _{dc_Pre} At equivalent rotational speed omega _conv . The principle of such rotation speed conversion will be briefly described below.

When the bus voltage is the preset bus voltage U _{dc_Pre} In the time-course of which the first and second contact surfaces,substituting it into equation (10) representing a voltage limiting ellipse can obtain the following equation:

in addition, when the bus voltage is the measurement voltage U _dc In the time-course of which the first and second contact surfaces,substituting it into equation (10) representing a voltage limiting ellipse can obtain the following equation:

if set upEquation (16) can be transformed into:

the following equation can be obtained by the arrangement of equation (17):

if set according to equation (14)Equation (18) may be further transformed into the following equation similar to equation (15):

it can be seen that the current bus voltage U can be determined by introducing equation (14) _dc The current rotation speed omega is corrected to the preset bus voltage U _{dc_Pre} At equivalent rotational speed omega _conv . In this way, when the bus voltage fluctuates and is at a voltage other than the predetermined bus voltage, the predetermined bus voltage U can still be utilized by simple rotational speed conversion _{dc_Pre} And determining the MTPA straight shaft current under the current bus voltage working condition by the relation between the rotating speed under the working condition and the MTPA straight shaft current.

According to an embodiment of the present disclosure, the control module 310 may include an MTPA sub-module 312, the MTPA sub-module 312 being based on torque commandsAnd the converted rotational speed omega _conv To determine a direct-axis current value satisfying the maximum torque current ratio +.>

Specifically, the rotational speed ω _conv Comprising measuring rotational speed omega and measuring bus voltage U _dc Information of both, which can greatly promote the determinationIs a function of the accuracy of the (c). Specifically, the direct axis current value +.>Is affected by the current bus voltage level. If there is a large fluctuation in the bus voltage and the +.>Then determined->Will be much more different from the MTPA direct current at the actual bus voltage. The present disclosure utilizes the converted rotational speed omega _conv Instead of the measured actual rotational speed ω, a +.>The determined +.>More closely approximates the actual required MTPA direct axis current.

In some embodiments of the present disclosure, the MTPA submodule 312 utilizes torque instructions in a lookup tableAnd the converted rotational speed omega _conv To determine the value of the direct current satisfying the maximum torque current ratio MTPA +.>The values in the lookup table are set at a predetermined bus voltage U _{dc_Pre} Is obtained under the condition of (1). In one embodiment, the lookup table is a two-dimensional table with a torque command on the horizontal axis and a motor speed on the vertical axis, or a motor speed on the horizontal axis and a torque command on the vertical axis.

As an example, the bus voltage may be a predetermined bus voltage U _{dc_Pre} The method adopts a bench calibration mode to obtain a direct-axis current two-dimensional table meeting MTPA, wherein the two-dimensional table takes torque and rotating speed as a transverse axis and a vertical axis as variables and takes direct-axis current as a search target. When the actual bus voltage is the measured bus voltage U _dc When the bus voltage U can be determined by equation (14) _dc The measured rotation speed is converted into the preset bus voltage U _{dc_Pre} At equivalent rotational speed omega _conv Then utilizing the torque command and the converted equivalent rotation speed omega _conv The direct axis current values satisfying the MTPA are determined in a two-dimensional table. Since the equivalent rotation speed omega is used _conv The thus determined direct-axis current value will be close to the actually required MTPA direct-axis current value and need only be at the predetermined bus voltage U _{dc_Pre} A direct axis current two-dimensional meter is prepared without preparing a plurality of two-dimensional meters for various bus voltages.

In some embodiments of the present disclosure, the predetermined bus voltage U _{dc_Pre} Including nominal bus voltage U _{dc_B} . When the predetermined bus voltage is the rated bus voltage U _{dc_B} When equation (14) can be transformed into the following equation:

the following table shows exemplary values when the bus voltage U is predetermined _{dc_Pre} For rated bus voltage U _{dc_B} At rated bus voltage U _{dc_B} And a direct-axis current two-dimensional table meeting MTPA is obtained by adopting a bench calibration mode.

TABLE 1

50

100

200

500

1000

1500

2000

3000

4000

5000

6000

8000

10000

12000

14000

16000

5

Id00

Id01

Id02

Id03

Id04

Id05

Id06

Id07

Id08

Id09

Id0A

Id0B

Id0C

Id0D

Id0E

Id0F

10

Id10

Id11

Id12

Id13

Id14

Id15

Id16

Id17

Id18

Id19

Id1A

Id1B

Id1C

Id1D

Id1E

Id1F

20

Id20

Id21

Id22

Id23

Id24

Id25

Id26

Id27

Id28

Id29

Id2A

Id2B

Id2C

Id2D

Id2E

Id2F

50

Id30

Id31

Id32

Id33

Id34

Id35

Id36

Id37

Id38

Id39

Id3A

Id3B

Id3C

Id3D

Id3E

Id3F

80

Id40

Id41

Id42

Id43

Id44

Id45

Id46

Id47

Id48

Id49

Id4A

Id4B

Id4C

Id4D

Id4E

Id4F

100

Id50

Id51

Id52

Id53

Id54

Id55

Id56

Id57

Id58

Id59

Id5A

Id5B

Id5C

Id5D

Id5E

Id5F

120

Id60

Id61

Id62

Id63

Id64

Id65

Id66

Id67

Id68

Id69

Id6A

Id6B

Id6C

Id6D

Id6E

Id6F

150

Id70

Id71

Id72

Id73

Id74

Id75

Id76

Id77

Id78

Id79

Id7A

Id7B

Id7C

Id7D

Id7E

Id7F

180

Id80

Id81

Id82

Id83

Id84

Id85

Id86

Id87

Id88

Id89

Id8A

Id8B

Id8C

Id8D

Id8E

Id8F

200

Id90

Id91

Id92

Id93

Id94

Id95

Id96

Id97

Id98

Id99

Id9A

Id9B

Id9C

Id9D

Id9E

Id9F

220

IdA0

IdA1

IdA2

IdA3

IdA4

IdA5

IdA6

IdA7

IdA8

IdA9

IdAA

IdAB

IdAC

IdAD

IdAE

IdAF

250

IdB0

IdB1

IdB2

IdB3

IdB4

IdB5

IdB6

IdB7

IdB8

IdB9

IdBA

IdBB

IdBC

IdBD

IdBE

IdBF

280

IdC0

IdC1

IdC2

IdC3

IdC4

IdC5

IdC6

IdC7

IdC8

IdC9

IdCA

IdCB

IdCC

IdCD

IdCE

IdCF

300

IdD0

IdD1

IdD2

IdD3

IdD4

IdD5

IdD6

IdD7

IdD8

IdD9

IdDA

IdDB

IdDC

IdDD

IdDE

IdDF

320

IdE0

IdE1

IdE2

IdE3

IdE4

IdE5

IdE6

IdE7

IdE8

IdE9

IdEA

IdEB

IdEC

IdED

IdEE

IdEF

350

IdF0

IdF1

IdF2

IdF3

IdF4

IdF5

IdF6

IdF7

IdF8

IdF9

IdFA

IdFB

IdFC

IdFD

IdFE

IdFF

In table 1, the first row lists rotational speed values as vertical axis variables and the first column lists torque values as horizontal axis variables. For example, when the measured rotational speed value is 2000, the torque command value is 150, and the rated bus voltage U _{dc_B} With the current measured busbar voltage U _dc Ratio of (2)At 1.5, the converted rotational speed ω can be derived from equation (20) _conv =2000·1.5=3000. That is, the converted rotational speed value 3000 should be used instead of the measured rotational speed value 2000 in table lookup. Then, the lookup and search table 1 can determine that the direct axis current value satisfying MTPA is "Id77". "Id77" is closer to the current measured bus voltage U than "Id76" found using a measured speed value of 2000 _dc MTPA direct axis current required under operating conditions.

In some embodiments of the present disclosure, the predetermined bus voltage U _{dc_Pre} Including minimum bus voltage U _{dc_Min} . Similar to equation (20), when the predetermined bus voltage is the minimum bus voltage U _{dc_Min} When equation (14) can be transformed into the following equation:

can be at the minimum bus voltage U _{dc_B} The direct axis current two-dimensional table meeting MTPA is obtained in a bench calibration mode, and the rotating speed is converted in a similar mode and the direct axis current value meeting MTPA is searched.

Compared with rated bus voltage U _{dc_B} By minimum bus voltage U _{dc_Min} As a predetermined bus voltage U _{dc_Pre} More preferably. When the rated bus voltage U is adopted _{dc_B} As a predetermined bus voltage U _{dc_Pre} If the current measured bus voltage is lower than the rated bus voltage, the rated bus voltage U _{dc_B} With the current measured busbar voltage U _dc Ratio of (2)Will be greater than 1 and thus the converted rotational speed for the look-up table will be greater than the current measured rotational speed. In this case, the converted rotational speed for the look-up table may exceed the rotational speed range of the calibrated table under the rated bus voltage condition, resulting in a table search error. However, if adoptedWith minimum bus voltage U _{dc_Min} As a predetermined bus voltage U _{dc_Pre} Minimum bus voltage U _{dc_Min} With the current measured busbar voltage U _dc Ratio of->Will always be less than 1 so that the converted speed for the look-up table is always lower than the current measured speed. Therefore, the method only needs to be scaled down to the corrected rotating speed according to a calibrated table under the working condition of the minimum bus voltage. The corrected rotating speed for table lookup is always within the rotating speed range of the two-dimensional table, so that the condition of searching errors is avoided. Therefore, the minimum bus voltage U is adopted _{dc_Min} As a predetermined bus voltage U _{dc_Pre} A more accurate MTPA direct axis current value can be obtained.

According to embodiments of the present disclosure, the m may be based on the modulation ratio instruction ^* And real-time modulation ratio m to adjust the direct current value at the differencing submodule 318 of the control module 310As an example, the control module 310 provides a feedback loop for the modulation ratio m. The modulation ratio m can be expressed as +.>Wherein i is _slimit Is the phase voltage amplitude limit mentioned in the foregoing. When the motor speed is medium-low or the bus voltage is high enough, the MTPA control mode can be adopted to control the motor to run, and the modulation ratio command m ^* The difference between the real-time modulation ratio m is zero, so that the direct-axis current value is not practically affected +.>However, when the motor speed is high or the bus voltage is too low, the control module 310 will enter the field weakening control mode and thus command m according to the modulation ratio ^* And a real-time modulation ratio m (e.g. modulation ratio command m ^* And the difference between the real-time modulation ratio m) to satisfy the direct-axis current value of MTPA +.>And (5) adjusting. Due to the presence of the feedback loop of the modulation ratio, the direct current value may be continuously adjusted at the differencing submodule 318 according to the feedback result of the modulation ratio to converge the direct current value to the direct current value required to satisfy the field weakening control. As described above, the determined direct current value +.>The system of the present disclosure can converge to the direct-axis current value required for field weakening control faster because it is closer to the direct-axis current value required for the current measured bus voltage condition.

In some embodiments of the present disclosure, the control module 310 includes a differencing sub-module 313 and a processing sub-module 314, wherein the differencing sub-module 313 calculates the modulation ratio instruction m ^* The difference from the real-time modulation ratio m, and processing submodule 314 pairs the modulation ratio instruction m ^* The difference from the real-time modulation ratio m is processed to generate an offset value. The processing of the processing sub-module 314 may include at least one of proportional, integral, and derivative operations. As an example, the processing sub-module 314 may be a proportional-integral control module, which has the advantage of being fast and small in dead space.

In some embodiments of the present disclosure, the control module 310 further includes a clipping sub-module 315, the clipping sub-module 315 limiting the offset value generated by the processing sub-module 314 to be within a first predetermined range. Thus, the direct-axis current value may be changed at the differencing module 318 based on the limited offset valueThe first predetermined range may be based on the maximum allowable current value i _smax And the determined direct-axis current value satisfying the maximum torque current ratio +.>To determine. As an example, the first predetermined range mayIs->To->Wherein i is _smax Can be determined according to equation (12), i.e., can be the maximum current i that the inverter 200 and the motor 100 are subjected to _slimit And maximum current +.>The lower of which is the lower one. Since the value of the output of the clipping sub-block 315 is limited to +.>To->Within a range of (1), it can be ensured that the output of the MTPA sub-module 312 is limited to- _smax To 0 so that the stator current does not exceed the current limit circle.

According to an embodiment of the present disclosure, the control device 300 is based on the adjusted direct-axis current value i generated by the differencing submodule 318 of the control module 310 _{d_Diff} A control signal CTR for the inverter 200 is generated. As an example, the adjusted direct axis current value i _{d_Diff} May be provided to the control signal generation module 320 as a reference value for the d-axis current or after processing to generate the control signal CTR.

In some embodiments of the present disclosure, the adjusted direct-axis current value i is at the clipping sub-module 316 of the control module 310 _{d_Diff} May be further limited to a second predetermined range to determine the direct current reference value i _{d_ref} And at a calculation sub-module 317, based on the determined direct current reference i _{d_ref} And torque commandTo determine the quadrature current reference i _{q_ref} . In determining the direct current reference value i _{d_ref} And quadrature axis current reference i _{q_ref} Thereafter, the control signal generation module 320 is based on the direct current reference value i _{d_ref} And quadrature axis current reference i _{q_ref} To generate the control signal CTR.

As an example, the adjusted direct axis current value i _{d_Diff} Can be further limited to ensure a DC reference i _{d_ref} Is limited to within the current limit circle, which may further increase the reliability of the system. In one embodiment, the second predetermined range is based on the maximum allowable current value i _smax To determine. For example, the second predetermined range may be set to _smax To 0 to further ensure that the stator current does not exceed the current limit circle.

In addition, the torque formula is givenA simple transformation may be performed to obtain the following equation for calculating the quadrature current reference i at the calculation submodule 317 _{q_ref} ：

Direct axis current reference i _{d_ref} And quadrature axis current reference i _{q_ref} May be input to the control signal generation module 320. An exemplary implementation of the control signal generation module 320 may be seen in fig. 4. The control signal generation module 320 may include, for example, a current control sub-module, an inverse PARK conversion sub-module, and a PWM sub-module to generate the control signal CTR, and may also include a CLARK conversion sub-module and a PARK conversion sub-module to provide a feedback current signal to provide closed loop control of the current. For example, the direct current reference i _{d_ref} And quadrature axis current reference i _{q_ref} May be provided to an interrupt service routine to perform closed loop control of the current loop to implement the functions of these sub-modules. The control signal CTR generated by the control signal generation module 320 is used to control the switching devices of the inverter 200 to be turned on and off, therebyMTPA control and field weakening control of the motor 100 are realized. However, it is understood that the implementation of the control signal generation module 320 is not limited thereto, and may be other suitable ways of implementing current control.

Embodiments of the present disclosure may achieve technical advantages over conventional approaches. For example, as the bus voltage of the inverter decreases, the radius of the voltage limit ellipse decreases, which causes the inflection point that transitions from the constant torque zone to the constant power zone to arrive earlier than the nominal bus voltage, resulting in easier motor operation into the flux weakening zone. Thus, for scenarios where the bus voltage is prone to fluctuations, such as in a vehicle, the flux weakening control mode or algorithm is often executed when the bus voltage is reduced. In the conventional scheme, when the busbar voltage is greatly reduced, a torque command is utilized to search in a one-dimensional table taking an MTPA direct-axis current value as a search target, and the searched MTPA direct-axis current value is larger in distance from a direct-axis current reference value required under the current busbar voltage working condition, so that auxiliary adjustment is required by a loop of a flux weakening algorithm, the direct-axis current reference value can gradually converge from a current value obtained by searching in the one-dimensional table to a current loop target value under the current busbar voltage, the convergence speed of the reference value of the current loop is easy to be slow, and the dynamic response characteristic of the system is influenced. In contrast, the scheme of the present disclosure converts the rotational speed based on the current bus voltage and determines the MTPA direct axis current using the converted rotational speed, whereby the information of both the bus voltage and the rotational speed is substantially considered in determining the MTPA direct axis current (e.g., searching the MTPA direct axis current in a way of looking up a two-dimensional table) such that the searched MTPA direct axis current is very close to the direct axis current reference value required under the bus voltage condition. Therefore, in the process of auxiliary adjustment by the modulation ratio loop of the flux weakening algorithm, the direct-axis current reference value can quickly converge from the current value obtained by searching to the current loop target value required under the current bus voltage, so that the dynamic response characteristic of the control system is accelerated, and the quick convergence and the robustness of the control system are improved.

Fig. 6 shows a schematic flow chart of a control method 6000 for a motor according to an embodiment of the present disclosure. The control method 6000 may be implemented in the motor system 1000 shown in fig. 1 and executed by the control device 300. It will be appreciated that the various aspects described above with respect to fig. 1-5 may be applied to the control method 6000.

At block 6001, the control device 300 is based on the measured bus voltage U of the inverter 200 _dc To convert the measured rotational speed ω of the motor 100, the inverter 200 being configured to drive the motor 100.

In some embodiments of the present disclosure, the measured bus voltage U based on the inverter 200 _dc Converting the measured rotational speed ω of the motor 100 includes: based on a predetermined bus voltage U _{dc_Pre} And measuring bus voltage U _dc To convert the measured rotational speed ω.

In some embodiments of the present disclosure, the predetermined bus voltage includes at least one of a minimum bus voltage and a rated bus voltage.

At block 6002, the control device 300 bases the torque commandAnd the converted rotational speed omega _conv To determine the value of the direct current satisfying the maximum torque current ratio MTPA +.>

In some embodiments of the present disclosure, the torque command is based onAnd the converted rotational speed omega _conv Determining a direct axis current value that meets the maximum torque current ratio, MTPA, includes: using torque command in look-up table >And the converted rotational speed omega _conv To determine the direct current value satisfying MTPA, the values in the lookup table are the predetermined bus voltage U at the bus voltage _{dc_Pre} Is obtained under the condition of (1).

In some embodiments of the present disclosure, the lookup table is a two-dimensional table with a torque command on the horizontal axis and a motor speed on the vertical axis, or a motor speed on the horizontal axis and a torque command on the vertical axis.

At block 6003, the control device 300 bases on the modulation ratio command m ^* Adjusting the direct current value with the real-time modulation ratio m

In some embodiments of the present disclosure, the m is based on a modulation ratio instruction ^* Adjusting the direct current value with the real-time modulation ratio mComprising the following steps: to modulation ratio instruction m ^* Processing the difference from the real-time modulation ratio m to generate an offset value; limiting the offset value to be within a first predetermined range; and changing the direct-axis current value based on the offset value after being limited +.>

In some embodiments of the present disclosure, the modulation ratio is directed to instruction m ^* The processing of the difference with the real-time modulation ratio m includes at least one of a proportional operation, an integral operation, and a differential operation, and the first predetermined range is based on the allowable maximum current value i _smax And the determined value of the direct current that satisfies the maximum torque-to-current ratioTo determine.

At block 6004, the control device 300 adjusts the direct current value i based on _{d_Diff} A control signal CTR for the inverter 200 is generated.

In some embodiments of the present disclosure, the adjusted direct-axis current value i is based on _{d_Diff} Generating the control signal CTR for the inverter 200 includes: the adjusted direct axis current value i _{d_Diff} Limiting in a second predetermined range to determine a direct current reference value i _{d_ref} The method comprises the steps of carrying out a first treatment on the surface of the Based on the determined direct current reference value i _{d_ref} And torque commandTo determine the quadrature current reference i _{q_ref} The method comprises the steps of carrying out a first treatment on the surface of the Based on the direct current reference i _{d_ref} And quadrature axis current reference i _{q_ref} To generate the control signal CTR.

In some embodiments of the present disclosure, the second predetermined range is based on the maximum allowable current value i _smax To determine.

In some embodiments of the present disclosure, the maximum current value i allowed _smax Maximum current i to be received for inverter 200 and motor 100 _slimit Maximum current determined by the current bus voltageThe lower of which is the lower one.

As an example, when MTPA control and modulation ratio loop control of two-dimensional table search are implemented in a computer program, an OS task of 1ms is adopted to execute, so that the requirement of real-time performance of a control system can be met.

Fig. 7 shows a schematic block diagram of an example device 7000 that may be used to implement an embodiment of the disclosure. The device 7000 may be used to implement the control arrangement 300 in fig. 1 and 4. As shown in fig. 7, device 7000 includes a computing unit 7001, which may perform various suitable actions and processes in accordance with computer program instructions stored in Random Access Memory (RAM) and/or Read Only Memory (ROM) 7002 or loaded from a storage unit 7007 into RAM and/or ROM 7002. In RAM and/or ROM 7002, various programs and data required for operation of the device 7000 may also be stored. The computing unit 7001 and the RAM and/or ROM 7002 are connected to each other through a bus 7003. An input/output (I/O) interface 7004 is also connected to the bus 7003.

Various components in device 7000 are connected to I/O interface 7004, including: an input unit 7005 such as a keyboard, a mouse, and the like; an output unit 7006 such as various types of displays, speakers, and the like; a storage unit 7007 such as a magnetic disk, an optical disk, or the like; and a communication unit 7008 such as a network card, a modem, a wireless communication transceiver, and the like. Communication unit 7008 allows device 7000 to exchange information/data with other devices via a computer network, such as the internet, and/or various telecommunication networks.

The computing unit 7001 may be a variety of general and/or special purpose processing components having processing and computing capabilities. Some examples of computing unit 7001 include, but are not limited to, a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), various dedicated Artificial Intelligence (AI) computing chips, various computing units running machine learning model algorithms, a Digital Signal Processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 7001 performs the various methods and processes described above, such as method 6000. For example, in some embodiments, the method 6000 may be implemented as a computer software program tangibly embodied on a machine-readable medium, such as the storage unit 7007. In some embodiments, some or all of the computer program may be loaded and/or installed onto device 7000 via RAM and/or ROM and/or communications unit 7008. One or more steps of method 6000 described above may be performed when a computer program is loaded into RAM and/or ROM and executed by computing unit 7001. Alternatively, in other embodiments, computing unit 7001 may be configured to perform method 6000 in any other suitable way (e.g., by means of firmware).

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus such that the program code, when executed by the processor or controller, causes the functions/operations specified in the flowchart and/or block diagram to be implemented. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of this disclosure, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Moreover, although operations are depicted in a particular order, this should be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present disclosure. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are example forms of implementing the claims.

Claims (22)

1. A control method for an electric machine, comprising:

Converting a measured rotational speed of the motor based on a measured bus voltage of an inverter configured to drive the motor;

determining a direct-axis current value satisfying a maximum torque-to-current ratio based on the torque command and the converted rotational speed;

adjusting the direct axis current value based on a modulation ratio command and a real-time modulation ratio; and

a control signal for the inverter is generated based on the adjusted direct axis current value.

2. The control method according to claim 1, wherein converting the measured rotational speed of the motor based on the measured bus voltage of the inverter includes:

the measured rotational speed is converted based on a ratio of a predetermined bus voltage to the measured bus voltage.

3. The control method of claim 2, wherein the predetermined bus voltage includes at least one of a minimum bus voltage and a rated bus voltage.

4. The control method according to claim 2, wherein determining a direct-axis current value that satisfies a maximum torque-to-current ratio based on the torque command and the converted rotational speed includes:

the torque command and the converted rotational speed are used in a lookup table to determine the direct current value satisfying a maximum torque to current ratio, the values in the lookup table being obtained when the bus voltage is the predetermined bus voltage.

5. The control method according to claim 4, wherein the lookup table is a two-dimensional table in which a horizontal axis is a torque command and a vertical axis is a motor rotation speed, or in which a horizontal axis is a motor rotation speed and a vertical axis is a torque command.

6. The control method of claim 1, wherein adjusting the direct axis current value based on a modulation ratio command and a real-time modulation ratio comprises:

processing a difference between the modulation ratio instruction and the real-time modulation ratio to generate an offset value;

limiting the offset value to be within a first predetermined range; and

the direct-axis current value is changed based on the offset value after being limited.

7. The control method according to claim 6, wherein the processing includes at least one of a proportional operation, an integral operation, and a derivative operation, and the first predetermined range is determined based on an allowable maximum current value and the determined direct-axis current value satisfying a maximum torque-current ratio.

8. The control method of claim 1, wherein generating a control signal for the inverter based on the adjusted direct-axis current value comprises:

limiting the adjusted direct current value to a second predetermined range to determine a direct current reference value;

Determining a quadrature axis current reference value based on the determined direct axis current reference value and the torque command; and

the control signal is generated based on the direct current reference value and the quadrature current reference value.

9. The control method according to claim 8, wherein the second predetermined range is determined based on an allowable maximum current value.

10. The control method according to claim 7 or 9, wherein the allowable maximum current value is a lower one of a maximum current that the inverter and the motor bear and a maximum current determined by a current bus voltage.

11. An electronic device, comprising:

a processor; and

a memory coupled with the processor, the memory having instructions stored therein that, when executed by the processor, cause the electronic device to perform actions comprising:

converting a measured rotational speed of the motor based on a measured bus voltage of an inverter configured to drive the motor;

determining a direct-axis current value satisfying a maximum torque-to-current ratio based on the torque command and the converted rotational speed;

adjusting the direct axis current value based on a modulation ratio command and a real-time modulation ratio; and

A control signal for the inverter is generated based on the adjusted direct axis current value.

12. The electronic device of claim 11, wherein converting the measured rotational speed of the motor based on the measured bus voltage of the inverter comprises:

the measured rotational speed is converted based on a ratio of a predetermined bus voltage to the measured bus voltage.

13. The electronic device of claim 12, wherein the predetermined bus voltage comprises at least one of a minimum bus voltage and a nominal bus voltage.

14. The electronic device of claim 12, wherein determining a direct-axis current value that meets a maximum torque-to-current ratio based on the torque command and the converted rotational speed comprises:

the torque command and the converted rotational speed are used in a lookup table to determine the direct current value satisfying a maximum torque to current ratio, the values in the lookup table being obtained when the bus voltage is the predetermined bus voltage.

15. The electronic device of claim 14, wherein the lookup table is a two-dimensional table with a torque command on a horizontal axis and a motor speed on a vertical axis, or a motor speed on a horizontal axis and a torque command on a vertical axis.

16. The electronic device of claim 11, wherein adjusting the direct axis current value based on a modulation ratio instruction and a real-time modulation ratio comprises:

processing a difference between the modulation ratio instruction and the real-time modulation ratio to generate an offset value;

limiting the offset value to be within a first predetermined range; and

the direct-axis current value is changed based on the offset value after being limited.

17. The electronic device of claim 16, wherein the processing includes at least one of a proportional operation, an integral operation, and a derivative operation, and the first predetermined range is determined based on an allowable maximum current value and the determined direct current value that meets a maximum torque current ratio.

18. The electronic device of claim 11, wherein generating a control signal for the inverter based on the adjusted direct axis current value comprises:

limiting the adjusted direct current value to a second predetermined range to determine a direct current reference value;

determining a quadrature axis current reference value based on the determined direct axis current reference value and the torque command; and

the control signal is generated based on the direct current reference value and the quadrature current reference value.

19. The electronic device of claim 18, wherein the second predetermined range is determined based on an allowable maximum current value.

20. The electronic device of claim 17 or 19, wherein the allowed maximum current value is a lower one of a maximum current that the inverter and the motor are subjected to and a maximum current determined by a current bus voltage.

21. A vehicle, comprising:

a motor for driving the vehicle to move; and

the electronic device of any of claims 11-20.

22. A computer readable medium having computer readable instructions stored thereon, which when executed by a processing unit, cause the processing unit to perform the control method according to any of claims 1-10.