Motor control device and motor control method

Abstract

The present disclosure relates to a motor control method, comprising the following steps: receiving a frequency command and an excitation current set value as a motor speed command; operating a flux operation program to generate a flux voltage command; generating a synchronous coordinate voltage command, and providing a three-phase current to the motor; calculating a synchronous coordinate feedback current according to the three-phase current, and further calculating a current effective value of the three-phase current; calculating a virtual power feedback value according to the synchronous coordinate voltage command and the synchronous coordinate feedback current; operating a steady-state operation program according to the frequency command and the current effective value to calculate a virtual power command; calculating a virtual power error value between the virtual power command and the virtual power feedback value; and superimposing the flux voltage command and the virtual power error value to adjust the synchronous coordinate voltage command, and further changing the three-phase current. The present disclosure also relates to a motor control device.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a motor control device and a motor control method for driving a sensorless motor. BACKGROUND

[0002] With the change of energy policy in the world, the requirement of motor operation efficiency is increasing. The synchronous reluctance motor (SynRM) has the advantages of high operation efficiency, low manufacturing cost, strong mechanical structure, etc. In addition, the synchronous reluctance motor also has the advantages of permanent magnet motor and induction motor. Therefore, in order to meet the demand of energy policy, the research of synchronous reluctance motor is also paid more and more attention.

[0003] At present, the control of synchronous reluctance motor mostly needs to be matched with a position sensor or an encoder for motor control. However, the use of position sensor or encoder often significantly increases the manufacturing cost. In addition, in the miniaturized motor product, the limited space is not easy to accommodate the position sensor or the encoder.

[0004] In addition, many researches on sensorless motor need to use estimators, such as flux observer and position and speed estimator, to perform algorithm operation to obtain the position, speed and other information of the motor. However, the use of estimator needs a large number of correct motor parameters to establish the motor model, so as to accurately calculate the position, speed and other information of the motor. SUMMARY

[0005] The present disclosure relates to a motor control method for sensorless motor, comprising the following steps: receiving a frequency command and an excitation current setting value as a motor speed command; running a flux calculation program according to the motor speed command to generate a flux voltage command; converting the flux voltage command into a synchronous coordinate voltage command, and further generating a three-phase current for the motor; calculating a synchronous coordinate feedback current according to the three-phase current, and further calculating a current effective value of the three-phase current; calculating a virtual power feedback value according to the synchronous coordinate voltage command and the synchronous coordinate feedback current; running a steady-state calculation program according to the frequency command and the current effective value to calculate a virtual power command; calculating a virtual power error value between the virtual power command and the virtual power feedback value; and superimposing the flux voltage command and the virtual power error value to adjust the synchronous coordinate voltage command, and further changing the three-phase current.

[0006] The present disclosure also relates to a motor control method for sensorless motor, comprising the following steps: receiving a frequency command and an excitation current setting value as a motor speed command; operating a flux calculation program according to the motor speed command to generate a flux voltage command; converting the flux voltage command into a synchronous coordinate voltage command, and further generating a three-phase current to the sensorless motor; calculating a synchronous coordinate feedback current according to the three-phase current, and further calculating a current effective value of the three-phase current; calculating a real power feedback value according to the synchronous coordinate voltage command and the synchronous coordinate feedback current; calculating a gap power variation according to the real power feedback value and the current effective value; and adjusting the synchronous coordinate voltage command according to the gap power variation, and further changing the three-phase current to the sensorless motor.

[0007] The present disclosure also relates to a motor control device for sensorless motor. The motor control device comprises a flux calculation unit, a drive calculation unit, a feedback calculation unit and a compensation calculation unit. The flux calculation unit is configured to receive a frequency command and an excitation current setting value to calculate a flux voltage command. The drive calculation unit is configured to convert the flux voltage command into a synchronous coordinate voltage command, and further generate a three-phase current to the motor. The feedback calculation unit is configured to calculate a synchronous coordinate feedback current according to the three-phase current, and further calculate a current effective value of the three-phase current. The feedback calculation unit is configured to calculate a reactive power feedback value according to the synchronous coordinate voltage command and the synchronous coordinate feedback current. The compensation calculation unit is configured to calculate a reactive power command according to the frequency command and the current effective value. The compensation calculation unit is configured to calculate a reactive power error value between the reactive power command and the reactive power feedback value. The drive calculation unit is further configured to superimpose the flux voltage command and the reactive power error value to adjust the synchronous coordinate voltage command, and further change the three-phase current.

[0008] The present disclosure mainly proposes a driving technology for sensorless synchronous reluctance motor. The present disclosure only uses basic motor parameters and does not need to consider nonlinear parameters, and is combined with a compensation method for improving efficiency and stability. Therefore, the present disclosure has high efficiency and good operation performance, and has the advantages of low motor parameter amount and simple calculation method compared with the existing method. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1A A schematic diagram of a motor control device according to some embodiments of the present disclosure.

[0010] Figure 1B A schematic diagram of a flux calculation unit according to some embodiments of the present disclosure.

[0011] Figure 1C A schematic diagram of a steady-state compensation loop according to some embodiments of the present disclosure.

[0012] Figure 1DA schematic diagram of a low-speed compensation loop according to some embodiments of the present disclosure.

[0013] Figure 1E A schematic diagram of a stability computation unit according to some embodiments of the present disclosure.

[0014] Figure 2A and Figure 2B A flowchart of a motor control method according to some embodiments of the present disclosure.

[0015] Figure 3 A flowchart of a flux computation routine according to some embodiments of the present disclosure.

[0016] Figure 4 A flowchart of a steady-state computation routine according to some embodiments of the present disclosure.

[0017] BRIEF DESCRIPTION OF DRAWINGS

[0018] 100: motor control device

[0019] 110: flux computation unit

[0020] 110a: predetermined flux curve

[0021] 110b flux computation routine

[0022] 120: compensation computation unit

[0023] 121: steady-state compensation loop

[0024] 121a: virtual work controller

[0025] 121b: error controller

[0026] 122: low-speed compensation loop

[0027] 122a: error controller

[0028] 123: low-pass filter

[0029] 130: stability computation unit

[0030] 130a: stability controller

[0031] 130b: high-pass filter

[0032] 130c: error controller

[0033] 140: drive computation unit

[0034] 141: first coordinate conversion loop

[0035] 142: second coordinate conversion loop

[0036] 143: modulation circuit

[0037] 150: feedback operation unit

[0038] 151: third coordinate conversion circuit

[0039] 152: current operation circuit

[0040] 153: power operation circuit

[0041] 160: current sensing device

[0042] 200: motor

[0043] ω e : frequency command

[0044] V a : synchronous coordinate voltage command

[0045] V vf : flux voltage command

[0046] V s : drive voltage signal

[0047] V γ : quadrature axis voltage command

[0048] V δ : direct axis voltage command

[0049] V abc : three-phase voltage signal

[0050] V tor : excitation error value

[0051] V com : reactive power error value

[0052] i a : synchronous coordinate feedback current

[0053] I abc : three-phase current

[0054] Io: excitation current set value

[0055] i γ : quadrature axis feedback current

[0056] i δ : direct axis feedback current

[0057] i err : error value

[0058] Is: current effective value

[0059] Pin: real power feedback value

[0060] Qin: virtual work feedback value

[0061] Qref: virtual work command

[0062] Θ h : voltage compensation angle

[0063] Θ e : drive angle

[0064] P AG : air gap power value

[0065] ΔP AG : air gap power change amount

[0066] 300: motor control method

[0067] S201-S211: steps

[0068] S301-S304: steps

[0069] 500: steady state operation program

[0070] S501-S503: steps

[0071] 1 / S: operation sub

[0072]

Biological material registration

[0073] Domestic registration information (Please note in the order of registration agency, date, number)

[0074] None

[0075] Foreign registration information (Please note in the order of registration country, agency, date, number)

[0076] None DETAILED DESCRIPTION

[0077] A number of embodiments of the present application will be disclosed below with reference to the accompanying drawings. For the purpose of clear illustration, many practical details will be described in the following description. However, it should be understood that these practical details should not be used to limit the present application. That is, in some embodiments of the present application, these practical details are not necessary. In addition, for the purpose of simplifying the drawings, some conventional structures and elements will be shown in the drawings in a simple schematic manner. It should be particularly noted that the so-called sensorless motor below generally refers to a motor without a position sensor (e.g., an encoder).

[0078] Please refer to the following drawings Figure 1A , Figure 1B , Figure 1C , Figure 1D , Figure 1E ,Figure 2A and Figure 2B to illustrate the following embodiments. As shown in Figure 1A , the motor control device 100 comprises a flux operation unit 110, a compensation operation unit 120, a stability operation unit 130, a drive operation unit 140, a feedback operation unit 150 and a current sensing device 160. The motor control device 100 is used to drive a sensorless motor 200. The motor 200 can be a synchronous reluctance motor, but the present disclosure is not limited thereto.

[0079] As shown in Figure 2A and Figure 2B , the present disclosure proposes a motor control method 300, and the motor control method 300 is applied to the sensorless motor 200. The motor control method 300 comprises steps S201-S211, and the motor control method 300 is performed by the motor control device 100 (as shown in Figure 1A ).

[0080] As shown in Figure 1A , Figure 1B and Figure 2A , in step S201, the flux operation unit 110 of the motor control device 100 receives the frequency command ω e and the excitation current setting value Io as the motor speed command. In some embodiments, as shown in Figure 1B , the flux operation unit 110 comprises a predetermined flux curve 110a and a flux operation program 110b. The predetermined flux curve 110a is a curve obtained according to the ratio (for example: Io / ω e ) of the excitation current setting value Io and the frequency command ω e , and is used to record the characteristics of the motor 200. Through the predetermined flux curve 110a, the flux operation unit 110 can obtain the excitation current setting value Io only by receiving the frequency command ω e , or obtain the frequency command ω e only by receiving the excitation current setting value Io. Alternatively, without the predetermined flux curve 110a, the flux operation unit 110 receives the excitation current setting value Io and the frequency command ω e at the same time. In addition, the frequency command ω e can generate the drive angle Θ e through a 1 / S operation. The 1 / S operation is the Laplace Transform or the Fourier transform commonly used by those skilled in the art, and since those skilled in the art can understand its meaning and operation, and the present disclosure is not limited thereto, it will not be described here.

[0081] As shown in Figure 1A , Figure 1Band Figure 2A In step S202, the flux operation unit 110 generates the flux voltage command V e by executing the flux operation program 110b in accordance with the motor speed command (including the excitation current set value I0and the frequency command ω vf . The operation principle of the flux operation program 110b will be described with reference to Figure 1A , Figure 1B and Figure 3 .

[0082] The flux operation program 110b includes steps S301 to S304. In step S301, the flux operation unit 110 establishes a first direct-axis equation and a first quadrature-axis equation in accordance with the motor speed command. The first direct-axis equation is shown in equation (1), and the first quadrature-axis equation is shown in equation (2).

[0083] v d = R s i d + L d pi d - ω γ L q i q (1)

[0084] v q = R s i q + L q pi q + ω γ L d i d (2)

[0085] where v d : direct-axis voltage of the motor stator, v q : quadrature-axis voltage of the motor stator, R s : resistance of the motor stator, L d : direct-axis self-inductance of the motor, L q : quadrature-axis self-inductance of the motor, i d : direct-axis current of the motor stator, i q : quadrature-axis current of the motor stator, ω γ : rotational speed of the motor rotor, p: differentiation factor. Note that equation (1) and equation (2) represent two-axis voltage equations of the motor 200. R s , L d , and L q in equation (1) and equation (2) are linear parameters of the motor, and these linear parameters are preset in the program of the motor control device 100 (or the flux operation unit 110). In addition, i d and i qis from the excitation current setting value Io, and ω γ is from the frequency command ω e .

[0086] In step S302, the flux operation unit 110 removes the differential term parameters (e.g., L d pi d , L q pi q ) of the first direct-axis equation and the first quadrature-axis equation, respectively, to establish a second direct-axis equation (as shown in equation (3)) and a second quadrature-axis equation (as shown in equation (4)), respectively.

[0087] v d = R s i d - ω γ L q i q (3)

[0088] v q = R s i q + ω γ L d i d (4)

[0089] The differential term parameters of the first direct-axis equation and the first quadrature-axis equation are removed in order to assume that the motor 200 is maintained in a steady state (i.e., the rotational speed of the motor 200 is maintained constant). Therefore, equation (3) is also regarded as a direct-axis steady-state equation, and equation (4) is also regarded as a quadrature-axis steady-state equation. At this time, i d may also be regarded as a direct-axis current steady-state value, and i q may also be regarded as a quadrature-axis current steady-state value.

[0090] In step S303, the flux operation unit 110 sets the quadrature-axis parameters (e.g., i q ) of the second direct-axis equation and the second quadrature-axis equation to zero, respectively, to establish a third direct-axis equation (as shown in equation (5)) and a third quadrature-axis equation (as shown in equation (6)), respectively.

[0091] v d = R s i d (5)

[0092] v q = ω γ L d i d (6)

[0093] Setting the quadrature axis parameter of the second direct-axis equation and the second quadrature axis equation to zero is to assume that motor 200 is not connected to any load (i.e., no-load). It is particularly important to note that, in order to improve the control efficiency of motor 200, the magnetic flux voltage command V is calculated... vf At this time, it is necessary to assume that the motor 200 maintains an ideal state, and that the ideal state is that the motor 200 maintains a steady state and is unloaded.

[0094] In step S304, the flux calculation unit 110 calculates the flux voltage command V based on the third direct-axis equation and the third quadrature-axis equation. vf Among them, the magnetic flux voltage command V vf The calculation method is shown in equation (7):

[0095]

[0096] like Figure 1A and Figure 2A As shown, in step S203, the drive arithmetic unit 140 receives the magnetic flux voltage command V. vf The driving voltage signal Vs is used as the driving voltage signal, and the driving operation unit 140 includes: a first coordinate transformation circuit 141, a second coordinate transformation circuit 142, and a modulation circuit 143. The first coordinate transformation circuit 141 is based on the voltage compensation angle Θ. h Command the magnetic flux voltage V vf Convert to synchronous coordinate voltage command V a And the second coordinate transformation loop 142 is based on the driving angle Θ e and synchronous coordinate voltage command V a Generate three-phase voltage V abc Furthermore, the modulation circuit 143 switches the three-phase voltage V abc This generates a three-phase current I. abc Give the motor 200. Voltage compensation angle Θ h The generation method will be introduced in later paragraphs. Among them, the synchronous coordinate voltage command V... a Includes: Direct-axis voltage command V δ and quadrature axis voltage command V γ It is particularly important to note that when the motor control device 100 is run for the first time, since no feedback signal is generated, the magnetic flux voltage command V... vf Equal to the driving voltage signal V s Furthermore, since the operating principle of the drive operation unit 140 is conventional technology in the art, it will not be described in detail here. Next, the motor control device 100 also includes a current sensing device 160, which is used to detect the three-phase current I. abc and transmit three-phase current I abcThe measured value is fed back to the processing unit 150. In some other embodiments, the current sensing device 160 detects the three-phase current I. abc The current of any two phases is fed to the feedback calculation unit 150. The feedback calculation unit 150 calculates the unmeasured third phase current based on the received current of any two phases.

[0097] like Figure 1A and Figure 2A As shown, in step S204, the third coordinate transformation circuit 151 of the feedback calculation unit 150 calculates the coordinates based on the three-phase current I. abc Measurement values ​​and drive angle Θ e Calculate the synchronous coordinate feedback current I a And synchronous coordinate feedback current i a Including direct-axis feedback current i δ and quadrature axis feedback current i γ Next, the current calculation loop 152 of the feedback calculation unit 150 calculates the current based on the direct-axis feedback current i. δ and quadrature axis feedback current i γ Equation (8) is used to calculate the three-phase current I. abc The effective value of the current Is. Equation (8) is shown below:

[0098]

[0099] like Figure 1A and Figure 2A As shown, in step S205, the power calculation circuit 153 of the feedback calculation unit 150 calculates the power according to the synchronous coordinate voltage command Va (including the direct axis voltage command V). δ and quadrature axis voltage command V γ ) and synchronous coordinate feedback current ia (including direct axis feedback current i) δ and quadrature axis feedback current i γ The virtual work feedback value Qin is calculated. The power operation loop 153 includes equation (9), and the virtual work feedback value Qin is calculated based on equation (9). Equation (9) is as follows:

[0100] Qin = 1.5 (V) γ i δ -V δ i γ (9)

[0101] like Figure 1A and Figure 2A As shown, in step S206, the power calculation circuit 153 of the feedback calculation unit 150 calculates the power according to the synchronous coordinate voltage command Va (including the direct axis voltage command V). δ and quadrature axis voltage command V γ) and synchronous coordinate feedback current ia (including direct axis feedback current i) δ and quadrature axis feedback current i γ The power calculation loop 153 includes equation (10), and calculates the actual power feedback value Pin based on equation (10). Equation (10) is as follows:

[0102] Pin = 1.5 (V) δ i δ +V γ i γ (10)

[0103] like Figure 1A , Figure 1C and Figure 2B As shown, in step S207, the steady-state compensation circuit 121 of the compensation operation unit 120 calculates the frequency command ω according to the frequency command ω. e The system calculates the virtual work command Qref by running a steady-state calculation program based on the effective current value Is. The steady-state compensation loop 121 includes a virtual work controller 121a and an error controller 121b, with the virtual work controller 121a executing the steady-state calculation program. (See also...) Figure 1C , Figure 2A and Figure 4 To illustrate the operating principle of the steady-state operation program 500:

[0104] The steady-state operation program 500 includes steps S501 to S503. In step S501, the virtual power controller 121a operates according to the frequency command ω. e Given the effective value of the current Is, establish the direct-axis steady-state equation (as shown in equation (3)) and the quadrature-axis steady-state equation (as shown in equation (4)) to calculate the steady-state value of the direct-axis current i. d and the steady-state value of quadrature-axis current i q .

[0105] In step S502, the virtual power controller 121a adjusts the steady-state value i of the direct-axis current. d and the steady-state value of cross-axis current i q The difference between them falls within the error range (ideal case: steady-state value of direct-axis current i). d Equal to the steady-state value of the quadrature-axis current i q ).

[0106] In step S503, when the virtual power controller 121a determines that the difference falls within the error range, it sets the steady-state value of the direct-axis current i. d and the steady-state value of cross-axis current i qSubstituting the direct-axis steady-state equation (Equation (3)) and the quadrature-axis steady-state equation (Equation (4)) into the equation, the virtual work command Qref is calculated. The calculation method for the virtual work command Qref is shown in Equations (11) and (12):

[0107] Qref=1.5((R S i d +ω e L d i d )i d -(R S i d -ω e L q i q )i q (11)

[0108] By rearranging equations (8) and (11), we can obtain equation (12):

[0109] Qref=1.5ω e Is 2 (L d +L q (12)

[0110] like Figure 1A , Figure 1C and Figure 2B As shown, in step S208, the steady-state compensation loop 121 of the compensation calculation unit 120 calculates the error value between the virtual work command Qref and the virtual work feedback value Qin, and uses the error value as the virtual work error value V via the error controller 121b. com The output is sent to low-pass filter 123 to filter out noise. In some embodiments, the motor control device 100 directly superimposes the magnetic flux voltage command V. vf and virtual work error value V com , to serve as the driving voltage signal V s And adjust the synchronous coordinate voltage command V via the drive calculation unit 140. a (including direct-axis voltage command V) δ and quadrature axis voltage command V γ This, in turn, changes the three-phase current I. abc To drive motor 200.

[0111] like Figure 1A , Figure 1D and Figure 2B As shown, in step S209, when the low-speed compensation circuit 122 of the compensation calculation unit 120 determines the direct-axis feedback current i of the motor 200 δWhen the speed is less than the preset threshold (representing that motor 200 is operating at low speed), the low-speed compensation circuit 122 calculates the excitation current setpoint Io and the synchronous coordinate feedback current i. a Direct-axis feedback current i δ The error value i between err And the excitation error value V is generated via the error controller 122a. tor When motor 200 operates at low speed, its driving efficiency will be significantly reduced. Therefore, the excitation error value V calculated by the low-speed compensation circuit 122... tor This is used as compensation. It can effectively increase the driving efficiency of the motor 200 while maintaining low speed. In some embodiments, the excitation error value V... tor and virtual work error value V com The superimposed signal is then filtered for noise by a low-pass filter 123. The excitation error value V... tor Used to communicate with magnetic flux voltage command V vf and virtual work error value V com Superimposed to adjust the synchronous coordinate voltage command V a .

[0112] like Figure 1A , Figure 1E and Figure 2B As shown, in step S210, the stability controller 130a of the stability calculation unit 130 calculates the air gap power value P based on the actual power feedback value Pin and the effective current value Is. AG Air-gap power (P) AG P represents the power transmitted to the rotor of the motor through the air gap between the stator and rotor. The stability controller 130a includes equation (13) to calculate the air gap power value P. AG Equation (13) is shown below:

[0113] P AG =Pin-3Is 2 R S (13)

[0114] Next, the high-pass filter 130b of the stability calculation unit 130 then calculates the air gap power value P based on the real-time air gap power value P. AG Calculate the change in air gap power ΔP AG Change in air gap power ΔP AG This represents the oscillation condition of the motor 200, or the oscillation condition of the load (not shown) connected to the motor 200. Next, the error controller 130c of the stability calculation unit 130 calculates the oscillation based on the air gap power change ΔP. AG Generate voltage compensation angle Θ h Among them, the voltage compensation angle Θ hThe calculation method is shown in equation (14):

[0115] Θ h =-K p ·ΔP AG (14)

[0116] In equation (14), the voltage compensation angle Θ h This can be considered as the oscillation condition of motor 200, -K p It is a negative proportionality constant, where -K p It is a proportionality constant that is inversely proportional to the output frequency. In other words, the voltage compensation angle Θ h This represents the amount of compensation required for the motor 200 to generate a counter-torque to overcome its oscillation. Therefore, in order to reduce the aforementioned oscillation of the motor 200, the stability calculation unit 130 calculates the air gap power change ΔP. AG Provides voltage compensation angle Θ h The drive arithmetic unit 140 is given a command to adjust the synchronization coordinate voltage V. a And thus change the three-phase current I abc This causes motor 200 to generate a counter-torque.

[0117] like Figure 1A and Figure 2B As shown, in step S211, when the motor 200 is operating at a low speed, the motor control device 100 mainly superimposes the excitation error value V. tor Magnetic flux voltage command V vf and virtual work error value V com , to be used as the driving voltage signal V s This causes the drive arithmetic unit 140 to adjust the synchronous coordinate voltage command V. a And thus change the three-phase current I abc When the motor 200 is not operating at low speed, the motor control device 100 mainly superimposes the magnetic flux voltage command V. vf and virtual work error value V com , to be used as the driving voltage signal V s This causes the drive arithmetic unit 140 to adjust the synchronous coordinate voltage command V. a And thus change the three-phase current I abc .

[0118] In the aforementioned steps S201 to S211, various compensations are performed for different situations of the motor 200, but the present disclosure is not limited thereto. In one embodiment, if the probability of the motor 200 exhibiting low-speed torque is not high, the motor control device 100 can simply rely on the magnetic flux voltage command V. vf and virtual work error value V com Adjust the synchronous coordinate voltage command Va Similarly, according to different control requirements, the motor control device 100 can also adjust the synchronous coordinate voltage command V AG according to the air-gap power variation ΔP a to change the three-phase current I abc . In other words, the motor control device 100 can selectively compensate for one or more situations (i.e., the no-load situation, the load situation, the low-speed torque situation, or the air-gap power variation) according to the driving condition.

[0119] The present disclosure is to drive the motor 200 through steps S201-S203, and then calculate the synchronous coordinate feedback current i abc (quad-axis feedback current i a and cross-axis feedback current i δ ), current effective value Is, reactive power feedback value Qin, active power feedback value, etc. through steps S204-S206 according to the feedback three-phase current I γ . Finally, the reactive power error value V com , the excitation error value V tor , and the air-gap power variation (i.e., the corresponding voltage compensation angle Θ h ) are generated through steps S207-S211 to compensate for the errors that the motor 200 may generate under different situations.

[0120] The "loop" and "controller" mentioned in the present disclosure can be a digital logic circuit, a hardware circuit, or other program languages, but the present disclosure is not limited thereto.

[0121] The elements, method steps, or technical features in the foregoing embodiments can be combined with each other without being limited by the order of the textual description in the present disclosure or the order presented in the drawings.

Claims

1. A motor control method for a sensorless motor, comprising: receiving a frequency command and an excitation current set value as a motor speed command; running a flux calculation routine to generate a flux voltage command based on the motor speed command; converting the flux voltage command to a synchronous coordinate voltage command and further generating a three-phase current to the motor; calculating a synchronous coordinate feedback current based on the three-phase current and further calculating a current effective value of the three-phase current; calculating a reactive power feedback value based on the synchronous coordinate voltage command and the synchronous coordinate feedback current; running a steady state routine to calculate a reactive power command based on the frequency command and the current effective value; calculating a reactive power error value between the reactive power command and the reactive power feedback value; and superimposing the flux voltage command and the reactive power error value to adjust the synchronous coordinate voltage command and further change the three-phase current.

2. The motor control method of claim 1, further comprising: calculating a real power feedback value based on the synchronous coordinate voltage command and the synchronous coordinate feedback current; calculating a gap power variation based on the real power feedback value and the current effective value; and adjusting the synchronous coordinate voltage command based on the gap power variation and further changing the three-phase current.

3. The motor control method of claim 1, further comprising: calculating an error value between the excitation current set value and a direct axis feedback current of the synchronous coordinate feedback current to generate an excitation error value, wherein the excitation error value is used to be superimposed with the flux voltage command and the reactive power error value to adjust the synchronous coordinate voltage command.

4. The motor control method of claim 1, wherein the flux calculation routine comprises: establishing a first direct axis equation and a first quadrature axis equation based on the motor speed command; removing differential term parameters of the first direct axis equation and the first quadrature axis equation to establish a second direct axis equation and a second quadrature axis equation, respectively; setting a quadrature axis parameter of the second direct axis equation and the second quadrature axis equation to zero to establish a third direct axis equation and a third quadrature axis equation, respectively; and calculating the flux voltage command based on the third direct axis equation and the third quadrature axis equation.

5. The motor control method of claim 4, wherein the steady state routine comprises: establishing a direct axis steady state equation and a quadrature axis steady state equation based on the frequency command and the current effective value to calculate a direct axis current steady state value and a quadrature axis current steady state value; adjusting a difference between the direct axis current steady state value and the quadrature axis current steady state value to fall within an error; and when the difference falls within the error, substituting the direct axis current steady state value and the quadrature axis current steady state value into the direct axis steady state equation and the quadrature axis steady state equation to calculate the reactive power command.

6. A motor control method for a sensorless motor, comprising: receiving a frequency command and an excitation current set value as a motor speed command; running a flux calculation routine to generate a flux voltage command based on the motor speed command; ​ ​ converts the flux voltage command into a synchronous coordinate voltage command, and further generates a three-phase current to the sensorless motor; calculates a synchronous coordinate feedback current according to the three-phase current, and further calculates a current effective value of the three-phase current; calculates a real power feedback value according to the synchronous coordinate voltage command and the synchronous coordinate feedback current; calculates a gap power variation according to the real power feedback value and the current effective value; and adjusts the synchronous coordinate voltage command according to the gap power variation, and further changes the three-phase current to the sensorless motor.

7. The motor control method of claim 6, further comprising: calculates a reactive power feedback value according to the synchronous coordinate voltage command and the synchronous coordinate feedback current; operates a steady-state operation program to calculate a reactive power command according to the frequency command and the current effective value; calculates a reactive power error value between the reactive power command and the reactive power feedback value; calculates an excitation current error value between the excitation current set value and a direct-axis feedback current of the synchronous coordinate feedback current, to obtain an excitation error value; and and superimposes the flux voltage command, the excitation error value and the reactive power error value to adjust the synchronous coordinate voltage command, and further changes the three-phase current to the sensorless motor.

8. The motor control method of claim 7, wherein the flux operation program comprises: establishes a first direct-axis equation and a first quadrature-axis equation according to the motor speed command; removes differential term parameters of the first direct-axis equation and the first quadrature-axis equation respectively to establish a second direct-axis equation and a second quadrature-axis equation respectively; sets a quadrature-axis parameter of the second direct-axis equation and the second quadrature-axis equation to zero respectively to establish a third direct-axis equation and a third quadrature-axis equation respectively; and calculates the flux voltage command according to the third direct-axis equation and the third quadrature-axis equation.

9. The motor control method of claim 8, wherein the steady-state operation program comprises: establishes a direct-axis steady-state equation and a quadrature-axis steady-state equation according to the frequency command and the current effective value to calculate a direct-axis current steady-state value and a quadrature-axis current steady-state value; adjusts a difference between the direct-axis current steady-state value and the quadrature-axis current steady-state value to fall within an error; and when judging that the difference falls within the error, substitutes the direct-axis current steady-state value and the quadrature-axis current steady-state value into the direct-axis steady-state equation and the quadrature-axis steady-state equation to calculate the reactive power command.

10. A motor control device for a sensorless motor, comprising: a flux operation unit receiving a frequency command and an excitation current set value to calculate a flux voltage command; a drive operation unit converting the flux voltage command into a synchronous coordinate voltage command, and further generating a three-phase current to the motor; and a feedback operation unit calculating a synchronous coordinate feedback current according to the three-phase current, and further obtaining a current effective value of the three-phase current, wherein the feedback operation unit calculates a reactive power feedback value according to the synchronous coordinate voltage command and the synchronous coordinate feedback current. a compensation operation unit configured to calculate a virtual power command based on the frequency command and the current effective value; wherein the compensation operation unit is configured to calculate a virtual power error value between the virtual power command and the virtual power feedback value; wherein the drive operation unit is further configured to superimpose the flux voltage command and the virtual power error value to adjust the synchronous coordinate voltage command, and further to change the three-phase current.

11. The motor control device of claim 10, wherein the compensation operation unit is further configured to calculate an error value between the field current set value and a direct-axis feedback current of the synchronous coordinate feedback current to obtain a field error value, and to superimpose the field error value with the flux voltage command and the virtual power error value to adjust the synchronous coordinate voltage command.

12. The motor control device of claim 10, wherein the feedback operation unit is further configured to calculate a real power feedback value based on the synchronous coordinate voltage command and the synchronous coordinate feedback current.

13. The motor control device of claim 12, further comprising: a stability operation unit configured to calculate a gap power variation based on the real power feedback value and the current effective value; wherein the drive operation unit is further configured to adjust the synchronous coordinate voltage command based on the gap power variation, and further to change the three-phase current.

14. The motor control device of claim 10, wherein the flux operation unit is further configured to: establish a first direct-axis equation and a first quadrature-axis equation based on the frequency command and the field current set value; remove differential term parameters of the first direct-axis equation and the first quadrature-axis equation, respectively, to establish a second direct-axis equation and a second quadrature-axis equation, respectively; set a quadrature-axis parameter of the second direct-axis equation and the second quadrature-axis equation to zero, respectively, to establish a third direct-axis equation and a third quadrature-axis equation, respectively; and calculate the flux voltage command based on the third direct-axis equation and the third quadrature-axis equation.

15. The motor control device of claim 10, wherein the compensation operation unit is further configured to: establish a direct-axis steady-state equation and a quadrature-axis steady-state equation based on the frequency command and the current effective value to calculate a direct-axis current steady-state value and a quadrature-axis current steady-state value; adjust a difference between the direct-axis current steady-state value and the quadrature-axis current steady-state value to fall within an error; and when determining that the difference falls within the error, substitute the direct-axis current steady-state value and the quadrature-axis current steady-state value into the direct-axis steady-state equation and the quadrature-axis steady-state equation to calculate the virtual power command.

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