CN116526920A - Maximum efficiency torque ratio control method for embedded permanent magnet synchronous motor based on direct current injection - Google Patents
Maximum efficiency torque ratio control method for embedded permanent magnet synchronous motor based on direct current injection Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/22—Current control, e.g. using a current control loop
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/13—Observer control, e.g. using Luenberger observers or Kalman filters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
- H02P21/20—Estimation of torque
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
- H02P25/022—Synchronous motors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/085—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/12—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation pulsing by guiding the flux vector, current vector or voltage vector on a circle or a closed curve, e.g. for direct torque control
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2207/00—Indexing scheme relating to controlling arrangements characterised by the type of motor
- H02P2207/05—Synchronous machines, e.g. with permanent magnets or DC excitation
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Abstract
The invention discloses a direct current injection-based maximum efficiency torque ratio control method for an embedded permanent magnet synchronous motor. Firstly, a torque observer based on direct current signal injection and direct current reactive power is provided, the method solves the problem of precision error caused by magnetic saturation and iron loss change, and improves the accuracy of torque observation; secondly, according to the designed torque observer, a maximum efficiency torque ratio (maximum efficiency per torque, MEPT) control method with an online search function is provided, and the motor can be operated with optimal efficiency under constant torque output. The method is suitable for the field of optimization control application of the embedded permanent magnet synchronous motor.
Description
Technical Field
The invention relates to an optimization control method for an embedded permanent magnet synchronous motor, and belongs to the fields of electrical engineering, motor modeling and motor control.
Background
The embedded permanent magnet synchronous motor has the advantages of high torque density, wide speed regulation range, quick dynamic response, high constant power ratio and the like, and is widely applied to various fields of rail transit, aerospace, household motors, wind power generation and the like. In the application process, the electrical parameters of the permanent magnet synchronous motor may be changed due to the change of the operating environment such as temperature or the influence of the operating conditions such as current change and speed change, which results in difficulty in realizing the maximum efficiency operating point of the motor under specific torque. Therefore, in order to realize high-performance operation and energy saving and efficiency improvement of the permanent magnet synchronous motor, accurate online optimal efficiency control needs to be realized.
The existing optimal efficiency control method can be divided into two types of calculation based on a model and online searching. The method based on the model calculates the maximum efficiency working point through the model parameters calibrated through experiments in advance, and has the advantage of high response speed. However, the model-based method requires a numerical method to perform the calculation, which increases the calculation load greatly. Also, when some unexpected motor characteristic shift conditions occur, such as irreversible demagnetization of the permanent magnet, the model-based method cannot be adjusted. Correspondingly, the online searching method adjusts the current step by step based on the measured motor signal to find the maximum power point, so that the maximum efficiency point can be found even if some unexpected characteristics deviate. In addition, the online searching method does not need to solve a complex model formula, so that the operation burden is small and the application is convenient.
However, if the maximum efficiency torque ratio control is to be realized by using an online searching mode, an important link is to accurately observe the change of the torque of the motor in the running process, so that the underrank characteristic of an inherent equation of the motor is needed to be overcome, and the influence of the magnetic saturation phenomenon and the iron loss of the motor is also needed to be considered.
Disclosure of Invention
In order to realize that the embedded permanent magnet synchronous motor operates with optimal efficiency under specific torque, the invention provides a control method of the maximum efficiency torque ratio (maximum efficiency per torque, MEPT) of the embedded permanent magnet synchronous motor based on direct current injection, which improves the problem of poor accuracy of the maximum efficiency working point caused by motor parameter change and model calculation error, further ensures that the operation of the permanent magnet synchronous motor is more efficient, and can avoid the loss of precision and the speed reduction of online searching.
In order to solve the problems, the invention adopts the following technical scheme:
a maximum efficiency torque ratio control method of an embedded permanent magnet synchronous motor based on direct current injection comprises the following steps: a torque observer based on direct current signal injection and direct current reactive power is proposed; based on the torque observer, a maximum efficiency torque ratio control method with an online searching function is provided;
firstly, designing a steady-state current time sequence under direct current signal injection, which comprises the following specific steps:
(1) At group 0 current operating point [ I ] d0 ,I q0 ]Before, 4 groups of currents are constructed through direct current signal injection, and the serial numbers are respectively 1 group, 2 group, 3 group and 4 group; i d0 And I q0 The current base value of the d-axis motor and the current base value of the q-axis motor are respectively;
(2) The output sequence of each current group is as follows: group 4, group 3, group 2, group 1, group 0;
(3) Define group 1 current operating point as [ I ] d1 ,I q1 ]Define group 2 current operating points as [ I ] d2 ,I q2 ]Define the 3 rd group current operating point as [ I ] d3 ,I q3 ]Definition of group 4 current operationPoint is [ I ] d4 ,I q4 ]；
(4) The relation between the current operating points satisfies:
in the above equation, ΔI d1 、ΔI d2 The current increment is respectively a set d-axis current increment 1 and a set d-axis current increment 2; ΔI q1 、ΔI q2 The set q-axis current increment 1 and the set q-axis current increment 2 are respectively.
Secondly, establishing a full rank parameter observation equation based on direct current reactive power, wherein the method comprises the following specific steps:
(1) Operating at current point [ I ] d0 ,I q0 ]The working point of the current after the direct current signal is injected is defined as [ I ] as a reference d ,I q ]Satisfy I d ＝I d0 +ΔI d 、I q ＝I q0 +ΔI q The method comprises the steps of carrying out a first treatment on the surface of the Wherein DeltaI d And DeltaI q The d-axis current signal amplitude and the q-axis current signal amplitude are respectively injected; at this time, at the current operation point [ I ] d ,I q ]The following direct current reactive power Q expression is:
Q＝1.5ω[(ψ ad +L id ΔI d )I d +(ψ aq +L iq ΔI q )I q ]
＝1.5ω[I d ψ ad +I q ψ aq +I d ΔI d L id +I q ΔI q L iq ]
in the above equation, I d And I q Respectively a d-axis motor current and a q-axis motor current, ψ ad Sum phi aq The apparent flux linkages of the d-axis motor and the q-axis motor are respectively, L id And L iq Delta inductance of d-axis motor and delta inductance of q-axis motor respectively, delta I d And DeltaI q The method comprises the steps of injecting a d-axis current small signal and a Q-axis current small signal respectively, wherein Q is direct current reactive power, and omega is the electric angular speed of a motor;
(2) Select the firstThe current working points of group 1, group 2, group 3 and group 4 are defined as the direct current reactive power Q in turn 1 、Q 2 、Q 3 、Q 4 The method comprises the steps of carrying out a first treatment on the surface of the Also with current operating point [ I ] d0 ,I q0 ]Based on the simultaneous equations of the direct current reactive power expressions of four groups, the parameter observation equation can be obtained:
Q＝1.5ωAX
in the equation, Q is a reactive power matrix, which satisfies the following conditions: q= [ Q ] 1 ,Q 2 ,Q 3 ,Q 4 ] T The method comprises the steps of carrying out a first treatment on the surface of the X is a torque observation parameter matrix, and meets the following conditions: x= [ ψ ] ad ,ψ aq ,L id ,L iq ] T The method comprises the steps of carrying out a first treatment on the surface of the A is a coefficient matrix, which satisfies the following conditions:
(3) In order to make the parameter observation equation full rank, it is necessary to ensure that the determinant of the coefficient matrix a is not 0, that is:
detA＝I q1 I q2 ΔI d1 ΔI d2 (ΔI q2 -ΔI q1 )(ΔI d2 -ΔI d1 )≠0
in the above equation, det is a determinant operation symbol.
Then, carrying out iterative solution on the full rank parameter observation equation based on the direct current reactive power based on a gradient descent method to obtain a torque observer parameter, wherein the method comprises the following specific steps of:
(1) For the direct current reactive power corresponding to the current working points of the 1 st group, the 2 nd group, the 3 rd group and the 4 th group, taking the mean square value of the error of the estimated value and the measured value as a loss function J:
in the above equation, Q i ' is the estimated DC reactive power value of the i-th group current working point, and the d-axis apparent flux linkage psi is estimated ad ' estimating q-axis apparent flux linkage ψ aq ′、Estimating d-axis increment inductance L id ' q-axis incremental inductance L is estimated iq ' substituting the direct current reactive power Q expression to calculate; q (Q) i Is the reactive power actual measurement value of the i-th group current working point, and meets the following conditions:
Q i ＝1.5(U qi I di -U di I qi )
in the above equation, U di 、U qi D-axis motor voltage and q-axis motor voltage of the ith group of current working points respectively; i di 、I qi D-axis motor current and q-axis motor current of the i-th group current working point respectively;
(2) Based on the direct current reactive power Q expression, calculating the gradient of the loss function J on each motor parameter:
in the above equation, ψ ad g 、ψ aq g 、L id g 、L iq g The loss function J is respectively relative to the coefficient psi ad 、ψ aq 、L id 、L iq Is a gradient of (2); ΔI gdi 、ΔI gqi D-axis current increment and q-axis current increment of the i-th group current working point respectively meet the following conditions: ΔI gdi ＝I di -I d0 、ΔI gqi ＝I qi -I q0 ；
(3) Based on the gradient of the loss function J to each motor parameter, establishing a torque observer parameter based on a gradient descent method
The number iteration solving process comprises the following specific steps:
(3.1) defining an iteration error threshold epsilon; defining a count coefficient k=0;
(3.2) defining a gradient matrix G, satisfying: g= [ ψ ] ad g ,ψ aq g ,L id g ,L iq g ] T The method comprises the steps of carrying out a first treatment on the surface of the Establishing an estimated parameter matrix X', and meeting the following conditions: x' = [ ψ ] ad ′,ψ aq ′,L id ′,L iq ′] T The method comprises the steps of carrying out a first treatment on the surface of the Defining an estimated parameter matrix of the kth iteration as X '(k), and assigning an initial value to X' (k);
(3.3) calculating direct current reactive power estimated values Q corresponding to the current working points respectively based on X' (k) and direct current reactive power Q expressions 1 ′、Q 2 ′、Q 3 ′、Q 4 ′；
(3.4) calculating a direct current reactive power actual measurement value Q based on the voltage and the current sampled at the steady state of the current working point 1 、Q 2 、Q 3 、Q 4 ；
(3.5) calculating a loss function J (k) of the kth iteration based on the direct current reactive power estimated value obtained in the step (3.3) and the direct current reactive power actual measurement value obtained in the step (3.4); if the loss function J (k) > epsilon, performing the step (3.6); if the loss function J (k) is less than or equal to epsilon, carrying out the step (3.9);
(3.6) calculating a gradient matrix G (k) of the kth iteration based on the direct current reactive power estimated value obtained in the step (3.3) and the direct current reactive power actual measurement value obtained in the step (3.4);
(3.7) based on G (k), X '(k), an estimated parameter matrix X' (k+1) for the k+1th iteration can be obtained:
X′(k+1)＝X′(k)-ηG(k)
in the equation, eta is the update step length of gradient descent;
(3.8) k=k+1, and step (3.3) is performed;
(3.9) when the loss function J (k) is smaller than or equal to the iteration error threshold epsilon, and the corresponding estimated parameter matrix X' (k) is the torque observer parameter obtained by final iteration solution;
(4) Based on the torque observer parameters obtained by iterative solution, the torque observer based on direct current signal injection and direct current reactive power is designed as follows:
in the above equation, T is the motor torque, n p Is the pole pair number of the motor.
Then, calculating the increment of the alternating-direct axis current with the increasing motor efficiency under constant torque, wherein the method comprises the following specific steps of:
(1) For the current operating points of the 0 th group, the 1 st group, the 2 nd group, the 3 rd group and the 4 th group, the 0 th group current operating point [ I ] is calculated d0 ,I q0 ]Active power P of (2) 0 ：
P 0 ＝1.5(U d0 I d0 +U q0 I q0 )
In the above equation, U d0 For corresponding to the 0 th group of direct-axis current working points I d0 Voltage of U q0 For corresponding to the 0 th group of quadrature axis current working point I q0 Is a voltage of (2);
(2) Calculate group 2 current operating points [ I ] d2 ,I q2 ]Active power P of (2) 2 ：
P 2 ＝1.5(U d2 I d2 +U q2 I q2 )
In the above equation, U d2 For corresponding to the 2 nd group of direct-axis current working points I d2 Voltage of U q2 For corresponding to the 2 nd group of quadrature axis current working points I q2 Is a voltage of (2);
(3) Based on the calculated P 0 、P 2 Calculating the direct current increment delta I according to the difference value dME ：
ΔI dME ＝-λ(P 2 -P 0 )/(I d2 -I d0 )
In the equation, lambda is the update step length of current disturbance observation;
(4) Finally, based on the stackCalculating the torque observer parameters obtained by solving the generation, and meeting the constant torque T ref Delta I of quadrature current of (a) qME ：
ΔI qME ＝[T ref /1.5n p -(ψ ad I q0 -ψ aq I d0 )+(ψ aq -L id I q0 )ΔI dME ]/(ψ ad -L iq I d0 )
In the above equation, T ref Is a constant torque reference value.
Finally, based on the calculated AC-DC axis current increment, realizing current update time sequence control, specifically comprising the following steps:
(1) According to the current increment delta I of the straight shaft dME And quadrature axis current increment Δi qME Updating the direct and quadrature reference currents I of the current controller dref And I qref ：
In the above equation, I dref ' and I qref ' is the updated direct-axis, quadrature-axis reference current;
(2) Calculate the corresponding I dref ' and I qref Active power P 'output by the motor in the' state:
in the above equation, U d ' and U q ' is the updated direct-axis, quadrature-axis voltage;
(3) Comparing the updated active power P' with the active power P before updating; if the active power is not equal before and after updating, the direct-axis current increment delta I is calculated again dME And quadrature axis current increment Δi qME Updating the orthogonal axis current reference value according to the formula in the step (1), and gradually reducing and approaching zero the increment of the orthogonal axis current and the increment of the orthogonal axis current;
(4) Through continuous online searching and updating iteration, the active power is maintained at the maximum power output working point, and the motor operates with optimal efficiency.
The invention principle is as follows:
in order to realize accurate observation of the torque, a torque observer model constructed by direct current signal injection and direct current reactive power is established. If a permanent magnet synchronous motor intrinsic voltage equation considering the change of the magnetic saturation iron loss is adopted, 4 unknown electrical parameters existing in a torque observer model are solved, and the underrank problem inevitably exists. In this regard, by injecting a dc bias signal into the dq axis, and according to the relationship between the dc reactive power and the apparent flux linkage and the incremental inductance, a full-order matrix for model parameter identification is constructed through the time sequence design of steady-state current, and the model parameter of the torque observer is accurately identified on line by adopting a gradient descent method for iterative solution.
Based on accurate identification of the model parameters of the torque observer, the motor current is gradually adjusted under constant torque by utilizing an online searching mode so as to find the maximum efficiency point. Taking the change direction of the active power and the change direction of the current as the basis, when the current is increased, if the active power is increased, the current is continuously increased, otherwise, the current is reduced; when the current decreases, if the active power increases, the current continues to decrease, otherwise the current increases. And finally, the motor is operated with optimal efficiency by continuously searching and iteratively updating on line.
The invention has the beneficial effects that:
1. the full-order matrix for online identification of the apparent flux linkage and the incremental inductance is constructed by using reactive power in 4 different current vector states by adopting a direct current signal injection mode, and the method considers the magnetic saturation phenomenon of the motor, avoids the influence of iron loss, reduces the complexity of identification and improves the accuracy of observation;
2. by adopting an online search MEPT control method, under the condition of accurate parameter identification, a constructed torque observer is used for gradually adjusting current to search an actual maximum power point. Under the constant torque load operation working condition, the error caused by parameter change or model-based calculation can be reduced, and the energy-saving performance of the permanent magnet synchronous motor is effectively improved.
Drawings
FIG. 1 is a MEPT control block diagram with an online lookup function;
FIG. 2 is a timing diagram of steady-state current injection for DC signals.
Detailed Description
The invention is further described below with reference to the drawings and specific examples.
The invention provides a direct current injection-based maximum efficiency torque ratio control method for an embedded permanent magnet synchronous motor, which comprises the following steps: a torque observer based on direct current signal injection and direct current reactive power is proposed; based on the torque observer, a maximum efficiency torque ratio control method with an online searching function is provided.
As shown in fig. 1, in the MEPT control block diagram for realizing the online searching function of the embedded permanent magnet synchronous motor based on direct current injection, through calculating the direct and quadrature axis currents and reactive power of the embedded permanent magnet synchronous motor, a torque observer is input, and through the obtained torque observer parameters, the quadrature and direct axis current increment with increasing motor efficiency under constant torque is calculated, and through online searching and iterative updating of current reference values, the maximum efficiency torque ratio control of the embedded permanent magnet synchronous motor is realized.
Firstly, designing a steady-state current time sequence under direct current signal injection, as shown in fig. 2, specifically comprising the following steps:
(1) At group 0 current operating point [ I ] d0 ,I q0 ]Before, 4 groups of currents are constructed through direct current signal injection, and the serial numbers are respectively 1 group, 2 group, 3 group and 4 group; i d0 And I q0 The current base value of the d-axis motor and the current base value of the q-axis motor are respectively;
(2) The output sequence of each current group is as follows: group 4, group 3, group 2, group 1, group 0;
(3) Define group 1 current operating point as [ I ] d1 ,I q1 ]Define group 2 current operating points as [ I ] d2 ,I q2 ]Define the 3 rd group current operating point as [ I ] d3 ,I q3 ]Define group 4 current operating points as [ I ] d4 ,I q4 ]；
(4) The relation between the current operating points satisfies:
in the above equation, ΔI d1 、ΔI d2 The current increment is respectively a set d-axis current increment 1 and a set d-axis current increment 2; ΔI q1 、ΔI q2 The set q-axis current increment 1 and the set q-axis current increment 2 are respectively.
Secondly, establishing a full rank parameter observation equation based on direct current reactive power, wherein the method comprises the following specific steps:
(1) Operating at current point [ I ] d0 ,I q0 ]The working point of the current after the direct current signal is injected is defined as [ I ] as a reference d ,I q ]Satisfy I d ＝I d0 +ΔI d 、I q ＝I q0 +ΔI q The method comprises the steps of carrying out a first treatment on the surface of the Wherein DeltaI d And DeltaI q The d-axis current signal amplitude and the q-axis current signal amplitude are respectively injected; at this time, at the current operation point [ I ] d ,I q ]The following direct current reactive power Q expression is:
Q＝1.5ω[(ψ ad +L id ΔI d )I d +(ψ aq +L iq ΔI q )I q ]
＝1.5ω[I d ψ ad +I q ψ aq +I d ΔI d L id +I q ΔI q L iq ]
in the above equation, I d And I q Respectively a d-axis motor current and a q-axis motor current, ψ ad Sum phi aq The apparent flux linkages of the d-axis motor and the q-axis motor are respectively, L id And L iq Delta inductance of d-axis motor and delta inductance of q-axis motor respectively, delta I d And DeltaI q The method comprises the steps of injecting a d-axis current small signal and a Q-axis current small signal respectively, wherein Q is direct current reactive power, and omega is the electric angular speed of a motor;
(2) Selecting group 1, group 2, group 3, group 4 current workersThe operating points are defined as the direct current reactive power Q in turn 1 、Q 2 、Q 3 、Q 4 The method comprises the steps of carrying out a first treatment on the surface of the Also with current operating point [ I ] d0 ,I q0 ]Based on the simultaneous equations of the direct current reactive power expressions of four groups, the parameter observation equation can be obtained:
Q＝1.5ωAX
in the equation, Q is a reactive power matrix, which satisfies the following conditions: q= [ Q ] 1 ,Q 2 ,Q 3 ,Q 4 ] T The method comprises the steps of carrying out a first treatment on the surface of the X is a torque observation parameter matrix, and meets the following conditions: x= [ ψ ] ad ,ψ aq ,L id ,L iq ] T The method comprises the steps of carrying out a first treatment on the surface of the A is a coefficient matrix, which satisfies the following conditions:
(3) In order to make the parameter observation equation full rank, it is necessary to ensure that the determinant of the coefficient matrix a is not 0, that is:
detA＝I q1 I q2 ΔI d1 ΔI d2 (ΔI q2 -ΔI q1 )(ΔI d2 -ΔI d1 )≠0
in the above equation, det is a determinant operation symbol.
Then, carrying out iterative solution on the full rank parameter observation equation based on the direct current reactive power based on a gradient descent method to obtain a torque observer parameter, wherein the method comprises the following specific steps of:
(1) For the direct current reactive power corresponding to the current working points of the 1 st group, the 2 nd group, the 3 rd group and the 4 th group, taking the mean square value of the error of the estimated value and the measured value as a loss function J:
in the above equation, Q i ' is the estimated DC reactive power value of the i-th group current working point, and the d-axis apparent flux linkage psi is estimated ad ' estimating q-axis apparent flux linkage ψ aq ' and d-axis incremental inductance L id ′、Estimating q-axis delta inductance L iq ' substituting the direct current reactive power Q expression to calculate; q (Q) i Is the reactive power actual measurement value of the i-th group current working point, and meets the following conditions:
Q i ＝1.5(U qi I di -U di I qi )
in the above equation, U di 、U qi D-axis motor voltage and q-axis motor voltage of the ith group of current working points respectively; i di 、I qi D-axis motor current and q-axis motor current of the i-th group current working point respectively;
(2) Based on the direct current reactive power Q expression, calculating the gradient of the loss function J on each motor parameter:
in the above equation, ψ ad g 、ψ aq g 、L id g 、L iq g The loss function J is respectively relative to the coefficient psi ad 、ψ aq 、L id 、L iq Is a gradient of (2); ΔI gdi 、ΔI gqi D-axis current increment and q-axis current increment of the i-th group current working point respectively meet the following conditions: ΔI gdi ＝I di -I d0 、ΔI gqi ＝I qi -I q0 ；
(3) Based on the gradient of the loss function J to each motor parameter, a torque observer parameter iteration solving process based on a gradient descent method is established, and the method specifically comprises the following steps:
(3.1) defining an iteration error threshold epsilon; defining a count coefficient k=0;
(3.2) defining a gradient matrix G, satisfying: g= [ ψ ] ad g ,ψ aq g ,L id g ,L iq g ] T The method comprises the steps of carrying out a first treatment on the surface of the Establishing an estimated parameter matrix X', and meeting the following conditions: x' = [ ψ ] ad ′,ψ aq ′,L id ′,L iq ′] T The method comprises the steps of carrying out a first treatment on the surface of the Defining an estimated parameter matrix of the kth iteration as X '(k), and assigning an initial value to X' (k);
(3.3) calculating direct current reactive power estimated values Q corresponding to the current working points respectively based on X' (k) and direct current reactive power Q expressions 1 ′、Q 2 ′、Q 3 ′、Q 4 ′；
(3.4) calculating a direct current reactive power actual measurement value Q based on the voltage and the current sampled at the steady state of the current working point 1 、Q 2 、Q 3 、Q 4 ；
(3.5) calculating a loss function J (k) of the kth iteration based on the direct current reactive power estimated value obtained in the step (3.3) and the direct current reactive power actual measurement value obtained in the step (3.4); if the loss function J (k) > epsilon, performing the step (3.6); if the loss function J (k) is less than or equal to epsilon, carrying out the step (3.9);
(3.6) calculating a gradient matrix G (k) of the kth iteration based on the direct current reactive power estimated value obtained in the step (3.3) and the direct current reactive power actual measurement value obtained in the step (3.4);
(3.7) based on G (k), X '(k), an estimated parameter matrix X' (k+1) for the k+1th iteration can be obtained:
X′(k+1)＝X′(k)-ηG(k)
in the equation, eta is the update step length of gradient descent;
(3.8) k=k+1, and step (3.3) is performed;
(3.9) when the loss function J (k) is smaller than or equal to the iteration error threshold epsilon, and the corresponding estimated parameter matrix X' (k) is the torque observer parameter obtained by final iteration solution;
(4) Based on the torque observer parameters obtained by iterative solution, the torque observer based on direct current signal injection and direct current reactive power is designed as follows:
T＝1.5n p (ψ ad I q -ψ aq I d )
in the above equation, T is the motor torque, n p Is the pole pair number of the motor.
Then, calculating the increment of the alternating-direct axis current with the increasing motor efficiency under constant torque, wherein the method comprises the following specific steps of:
(1) For the current operating points of the 0 th group, the 1 st group, the 2 nd group, the 3 rd group and the 4 th group, the 0 th group current operating point [ I ] is calculated d0 ,I q0 ]Active power P of (2) 0 ：
P 0 ＝1.5(U d0 I d0 +U q0 I q0 )
In the above equation, U d0 For corresponding to the 0 th group of direct-axis current working points I d0 Voltage of U q0 For corresponding to the 0 th group of quadrature axis current working point I q0 Is a voltage of (2);
(2) Calculate group 2 current operating points [ I ] d2 ,I q2 ]Active power P of (2) 2 ：
P 2 ＝1.5(U d2 I d2 +U q2 I q2 )
In the above equation, U d2 For corresponding to the 2 nd group of direct-axis current working points I d2 Voltage of U q2 For corresponding to the 2 nd group of quadrature axis current working points I q2 Is a voltage of (2);
(3) Based on the calculated P 0 、P 2 Calculating the direct current increment delta I according to the difference value dME ：
ΔI dME ＝-λ(P 2 -P 0 )/(I d2 -I d0 )
In the equation, lambda is the update step length of current disturbance observation;
(4) Finally, calculating the torque observer parameters based on the iterative solution to meet the constant torque T ref Delta I of quadrature current of (a) qME ：
ΔI qME ＝[T ref /1.5n p -(ψ ad I q0 -ψ aq I d0 )+(ψ aq -L id I q0 )ΔI dME ]/(ψ ad -L iq I d0 )
In the above equation, T ref Is a constant torque reference value.
Finally, based on the calculated AC-DC axis current increment, realizing current update time sequence control, specifically comprising the following steps:
(1) According to the current increment delta I of the straight shaft dME And quadrature axis current increment Δi qME Updating the direct and quadrature reference currents I of the current controller dref And I qref ：
In the above equation, I dref ' and I qref ' is the updated direct-axis, quadrature-axis reference current;
(2) Calculate the corresponding I dref ' and I qref Active power P 'output by the motor in the' state:
in the above equation, U d ' and U q ' is the updated direct-axis, quadrature-axis voltage;
(3) Comparing the updated active power P' with the active power P before updating; if the active power is not equal before and after updating, the direct-axis current increment delta I is calculated again dME And quadrature axis current increment Δi qME Updating the orthogonal axis current reference value according to the formula in the step (1), and gradually reducing and approaching zero the increment of the orthogonal axis current and the increment of the orthogonal axis current;
(4) Through continuous online searching and updating iteration, the active power is maintained at the maximum power output working point, and the motor operates with optimal efficiency.
Claims (6)
1. The control method of the maximum efficiency torque ratio of the embedded permanent magnet synchronous motor based on direct current injection is characterized in that firstly, a torque observer based on direct current signal injection and direct current reactive power is provided; then, a maximum efficiency torque ratio control method with an online searching function is provided based on the torque observer;
the torque observer based on direct current signal injection and direct current reactive power is provided, and the specific method comprises the following steps: designing a steady-state current time sequence under direct-current signal injection, and establishing a full-rank parameter observation equation based on direct-current reactive power; carrying out iterative solution on the full rank parameter observation equation based on the direct current reactive power based on a gradient descent method to obtain a torque observer parameter;
the maximum efficiency torque ratio control method with the online searching function specifically comprises the following steps:
calculating the increment of alternating-direct axis current of the increment of motor efficiency under constant torque;
and based on the alternating-direct axis current increment, realizing current update time sequence control.
2. The method for controlling the maximum efficiency torque ratio of the embedded permanent magnet synchronous motor based on direct current injection according to claim 1, wherein the steady-state current sequence under direct current signal injection is designed, and the method comprises the following specific steps:
(1) At group 0 current operating point [ I ] d0 ,I q0 ]Before, 4 groups of currents are constructed through direct current signal injection, and the serial numbers are respectively 1 group, 2 group, 3 group and 4 group; i d0 And I q0 The current base value of the d-axis motor and the current base value of the q-axis motor are respectively;
(2) The output sequence of each current group is as follows: group 4, group 3, group 2, group 1, group 0;
(3) Define group 1 current operating point as [ I ] d1 ,I q1 ]Define group 2 current operating points as [ I ] d2 ,I q2 ]Define the 3 rd group current operating point as [ I ] d3 ,I q3 ]Define group 4 current operating points as [ I ] d4 ,I q4 ]；
(4) The relation between the current operating points satisfies:
wherein DeltaI d1 、ΔI d2 The current increment is respectively a set d-axis current increment 1 and a set d-axis current increment 2; ΔI q1 、ΔI q2 The set q-axis current increment 1 and the set q-axis current increment 2 are respectively.
3. The method for controlling the maximum efficiency torque ratio of the embedded permanent magnet synchronous motor based on direct current injection according to claim 2, wherein the method for establishing the full rank parameter observation equation based on direct current reactive power comprises the following specific steps:
(1) Operating at current point [ I ] d0 ,I q0 ]The working point of the current after the direct current signal is injected is defined as [ I ] as a reference d ,I q ]Satisfy I d ＝I d0 +ΔI d 、I q ＝I q0 +ΔI q The method comprises the steps of carrying out a first treatment on the surface of the Wherein DeltaI d And DeltaI q The d-axis current signal amplitude and the q-axis current signal amplitude are respectively injected; at this time, at the current operation point [ I ] d ,I q ]The following direct current reactive power Q expression is:
Q＝1.5ω[(ψ ad +L id ΔI d )I d +(ψ aq +L iq ΔI q )I q ]
＝1.5ω[I d ψ ad +I q ψ aq +I d ΔI d L id +I q ΔI q L iq ]
wherein I is d And I q Respectively a d-axis motor current and a q-axis motor current, ψ ad Sum phi aq The apparent flux linkages of the d-axis motor and the q-axis motor are respectively, L id And L iq Delta inductance of d-axis motor and delta inductance of q-axis motor respectively, delta I d And DeltaI q Respectively injecting a small d-axis current signal and injecting q-axis electricityThe small current signal, Q is the direct current reactive power, omega is the electric angular speed of the motor;
(2) Selecting the current working points of the 1 st group, the 2 nd group, the 3 rd group and the 4 th group, and sequentially defining the direct current reactive power of the current working points as Q 1 、Q 2 、Q 3 、Q 4 The method comprises the steps of carrying out a first treatment on the surface of the Also with current operating point [ I ] d0 ,I q0 ]Based on the simultaneous equations of the direct current reactive power expressions of four groups, the parameter observation equation can be obtained:
Q＝1.5ωAX
wherein, Q is a reactive power matrix, satisfying: q= [ Q ] 1 ,Q 2 ,Q 3 ,Q 4 ] T The method comprises the steps of carrying out a first treatment on the surface of the X is a torque observation parameter matrix, and meets the following conditions: x= [ ψ ] ad ,ψ aq ,L id ,L iq ] T The method comprises the steps of carrying out a first treatment on the surface of the A is a coefficient matrix, which satisfies the following conditions:
(3) In order to make the parameter observation equation full rank, it is necessary to ensure that the determinant of the coefficient matrix a is not 0, that is:
detA＝I q1 I q2 ΔI d1 ΔI d2 (ΔI q2 -ΔI q1 )(ΔI d2 -ΔI d1 )≠0
wherein det is a determinant operation symbol.
4. The method for controlling the torque ratio of maximum efficiency of the embedded permanent magnet synchronous motor based on direct current injection according to claim 3, wherein the method for iteratively solving the full rank parameter observation equation based on direct current reactive power based on gradient descent method is characterized by comprising the following specific steps of:
(1) For the direct current reactive power corresponding to the current working points of the 1 st group, the 2 nd group, the 3 rd group and the 4 th group, taking the mean square value of the error of the estimated value and the measured value as a loss function J:
wherein Q is i ' is the estimated DC reactive power value of the i-th group current working point, and the d-axis apparent flux linkage psi is estimated ad ' estimating q-axis apparent flux linkage ψ aq ' and d-axis incremental inductance L id ' q-axis incremental inductance L is estimated iq ' substituting the direct current reactive power Q expression to calculate; q (Q) i Is the reactive power actual measurement value of the i-th group current working point, and meets the following conditions:
Q i ＝1.5(U qi I di -U di I qi )
wherein U is di 、U qi D-axis motor voltage and q-axis motor voltage of the ith group of current working points respectively; i di 、I qi D-axis motor current and q-axis motor current of the i-th group current working point respectively;
(2) Based on the direct current reactive power Q expression, calculating the gradient of the loss function J on each motor parameter:
wherein, psi is ad g 、ψ aq g 、L id g 、L iq g The loss function J is respectively relative to the coefficient psi ad 、ψ aq 、L id 、L iq Ladder of (2)A degree; ΔI gdi 、ΔI gqi D-axis current increment and q-axis current increment of the i-th group current working point respectively meet the following conditions: ΔI gdi ＝I di -I d0 、ΔI gqi ＝I qi -I q0 ；
(3) Based on the gradient of the loss function J to each motor parameter, a torque observer parameter iteration solving process based on a gradient descent method is established, and the method specifically comprises the following steps:
(3.1) defining an iteration error threshold epsilon; defining a count coefficient k=0;
(3.2) defining a gradient matrix G, satisfying: g= [ ψ ] ad g ,ψ aq g ,L id g ,L iq g ] T The method comprises the steps of carrying out a first treatment on the surface of the Establishing an estimated parameter matrix X', and meeting the following conditions: x' = [ ψ ] ad ',ψ aq ',L id ',L iq '] T The method comprises the steps of carrying out a first treatment on the surface of the Defining an estimated parameter matrix of the kth iteration as X '(k), and assigning an initial value to X' (k);
(3.3) calculating direct current reactive power estimated values Q corresponding to the current working points respectively based on X' (k) and direct current reactive power Q expressions 1 '、Q 2 '、Q 3 '、Q 4 '；
(3.4) calculating a direct current reactive power actual measurement value Q based on the voltage and the current sampled at the steady state of the current working point 1 、Q 2 、Q 3 、Q 4 ；
(3.5) calculating a loss function J (k) of the kth iteration based on the direct current reactive power estimated value obtained in the step (3.3) and the direct current reactive power actual measurement value obtained in the step (3.4); if the loss function J (k) > epsilon, performing the step (3.6); if the loss function J (k) is less than or equal to epsilon, carrying out the step (3.9);
(3.6) calculating a gradient matrix G (k) of the kth iteration based on the direct current reactive power estimated value obtained in the step (3.3) and the direct current reactive power actual measurement value obtained in the step (3.4);
(3.7) based on G (k), X '(k), an estimated parameter matrix X' (k+1) for the k+1th iteration can be obtained:
X'(k+1)＝X'(k)-ηG(k)
wherein eta is the update step length of gradient descent;
(3.8) k=k+1, and step (3.3) is performed;
(3.9) when the loss function J (k) is smaller than or equal to the iteration error threshold epsilon, and the corresponding estimated parameter matrix X' (k) is the torque observer parameter obtained by final iteration solution;
(4) The torque observer parameters obtained based on the iterative solution are obtained, and the torque observer based on the direct current signal injection and the direct current reactive power is obtained by the following steps:
T＝1.5n p (ψ ad I q -ψ aq I d )
wherein T is motor torque, n p Is the pole pair number of the motor.
5. The method for controlling the torque ratio of maximum efficiency of the embedded permanent magnet synchronous motor based on direct current injection according to claim 4, wherein the step of calculating the increment of alternating-direct current with increasing motor efficiency under constant torque is as follows:
(1) For the current operating points of the 0 th group, the 1 st group, the 2 nd group, the 3 rd group and the 4 th group, the 0 th group current operating point [ I ] is calculated d0 ,I q0 ]Active power P of (2) 0 ：
P 0 ＝1.5(U d0 I d0 +U q0 I q0 )
Wherein U is d0 For corresponding to the 0 th group of direct-axis current working points I d0 Voltage of U q0 For corresponding to the 0 th group of quadrature axis current working point I q0 Is a voltage of (2);
(2) Calculate group 2 current operating points [ I ] d2 ,I q2 ]Active power P of (2) 2 ：
P 2 ＝1.5(U d2 I d2 +U q2 I q2 )
Wherein U is d2 For corresponding to the 2 nd group of direct-axis current working points I d2 Voltage of U q2 For corresponding to the 2 nd group of quadrature axis current working points I q2 Is a voltage of (2); (3) Based on the calculated P 0 、P 2 Calculating the direct current increment delta I according to the difference value dME ：
ΔI dME ＝-λ(P 2 -P 0 )/(I d2 -I d0 )
Wherein lambda is the update step length of current disturbance observation;
(4) Finally, calculating the torque observer parameters based on the iterative solution to meet the constant torque T ref Delta I of quadrature current of (a) qME ：
ΔI qME ＝[T ref /1.5n p -(ψ ad I q0 -ψ aq I d0 )+(ψ aq -L id I q0 )ΔI dME ]/(ψ ad -L iq I d0 )
Wherein T is ref Is a constant torque reference value.
6. The method for controlling the torque ratio of maximum efficiency of the embedded permanent magnet synchronous motor based on direct current injection according to claim 5, wherein the current update timing control is realized based on the calculated ac-dc axis current increment, specifically:
(1) According to the current increment delta I of the straight shaft dME And quadrature axis current increment Δi qME Updating the direct-axis and quadrature-axis reference current I of the current controller dref And I qref ：
Wherein I is dref ' and I qref ' is the updated direct-axis, quadrature-axis reference current;
(2) Calculate the corresponding I dref ' and I qref Active power P 'output by the motor in the' state:
wherein U is d ' and U q ' is the updated direct-axis, quadrature-axis voltage;
(3) Comparing updatedThe active power P' and the magnitude of the active power P before updating; if the active power is not equal before and after updating, the direct-axis current increment delta I is calculated again dME And quadrature axis current increment Δi qME Updating the orthogonal axis current reference value according to the formula in the step (1), and gradually reducing and approaching zero the increment of the orthogonal axis current and the increment of the orthogonal axis current;
(4) Through continuous online searching and updating iteration, the active power is maintained at the maximum power output working point, and the motor operates with optimal efficiency.
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