Method for determining rotation parameter of rotation angle and electric motor

Abstract

The invention relates to a method (16) for determining a rotational parameter of at least one variable rotational angle (gamma) of a rotor (14) of an electric motor (10), which rotor is rotatable relative to a stator (12), said angle depending on a rotational speed (omega), the method comprises the following steps: determining (20) a first phase voltage (vd) and a first phase current (id) in each d-direction in a dq coordinate system fixed with respect to the rotor and a second phase voltage (uq) and a second phase current (iq) in each q-direction in a coordinate system fixed with respect to the rotor; applying (22) a calculation algorithm (24) to iteratively calculate (27) the rotational speed (omega) as a calculated rotational speed (omega i) and iteratively calculate (27) the rotational angle (y) as a calculated rotational angle (y); outputting (28) the calculated rotation angle (yi) as the output calculated rotation angle (yr); and calculating (30) the rotational speed (omega) as the output calculated rotational speed (omega r) from the output calculated rotational angle (yr) without calculating directly from the calculated rotational speed (omega i). The invention also relates to an electric motor (10).

Description

Technical Field

[0001] This invention relates to a method for determining rotational parameters according to claim 1. The invention also relates to electric motors. Background Technology

[0002] When the rotor of an electric motor rotates and therefore has sufficient back-induced voltage available, in the case of a permanent magnet synchronous motor, it is known to determine rotational parameters using a voltage model based on voltage equations that depend on the phase voltages. First, the phase voltages are measured, and then the voltage model is used to calculate the modeled phase voltages. This voltage model also includes phase currents and electric motor parameters. The voltage error in the dq coordinate system is calculated based on the difference between the measured phase voltage and the modeled phase voltage. The rotation angle and rotational speed are calculated by reducing the voltage error.

[0003] The iterative calculation described in "Position and Speed ​​Estimation Algorithm for Permanent Magnet Synchronous Machines Considering Nonlinear Magnetic Effects" presented by M. Brodatzki, J. Richter, J. Kolb, and M. Braun at the 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019—ECCEAsia), 2019, pp. 1-8, is a computational step that begins with the solution for rotation angle and rotation speed from the previous step and calculates the four voltage errors in the d and q directions by changing the rotation angle and rotation speed. The calculated rotation angle and rotation speed are used as solutions to the nonlinear equations of the voltage model by applying the two-dimensional secant method.

[0004] If the motor parameters used in the voltage model are incorrectly assumed, for example due to temperature effects, incorrect and / or delayed calculations of the calculated rotation angle and rotation speed may occur.

[0005] In: *Electrical Engineering*, Vol. 146, No. 3, 2004, pp. 55-64, ISSN 0424-7760(P); 1520-6416(E), DOI: 10.1002 / eej,10257, URL: https: / / onlinelibrary.wiley.com / doi / epdf / 10.1002 / eej.10257 [accessed 2024-02-07], ICHIKAWA, Shinji et al.: Sensorless controls of salient-pole permanent magnet synchronous motors using extended electromotive force models describes a mathematical model for synchronous motors and a sensorless control method based on this mathematical model, which enables rotor position determination without approximation. Summary of the Invention

[0006] The purpose of this invention is to determine the rotational parameters of an electric motor more accurately, easily, and quickly.

[0007] At least one of these objectives is achieved by a method for determining rotational parameters having the features of claim 1. This allows for more accurate and faster determination of the rotation angle. Model inaccuracies in the voltage model can be better compensated for. Calculations of the rotation angle and / or rotational speed can be more unaffected by temperature.

[0008] An electric motor can be installed in a vehicle. The vehicle can be a motor vehicle. The electric motor can provide driving force for moving the vehicle and / or for operating vehicle components. Vehicle components can be auxiliary units, particularly fluid pumps. The fluid pump can be a hydraulic pump.

[0009] The electric motor can operate in encoder-free mode. The method can be performed during encoder-free mode of the electric motor. The electric motor can operate only in encoder-free mode. Encoder-free mode is understood to mean a mode in which rotation angles are not incorporated by sensors such as position sensors.

[0010] An electric motor can be controlled by at least three motor phases. The electric motor can be a brushless DC motor. The electric motor can also be an AC synchronous motor with permanent magnets.

[0011] The calculated rotational speed output can be used as the time-dependent change of the calculated rotational angle output for calculation.

[0012] A voltage model can be used to calculate the modeled first-phase voltage and the modeled second-phase voltage. The modeled first-phase voltage u... d,m It can be determined as follows based on the first phase current i d Second phase current i q calculate:

[0013]

[0014] Among them, directional inductance L d L q and the resistance R of the stator s P is the parameter of the electric motor.

[0015] The modeled second phase voltage u q,m The voltage model can be used for calculation as follows:

[0016]

[0017] Among them, the magnetic flux linkage Ψ of the rotor EM As an additional motor parameter P′.

[0018] The first and second phase voltages in the dq coordinate system can be calculated based on the phase voltages in the stator-fixed coordinate system. An electric motor can have three motor phases. Therefore, the phase voltages in the stator-fixed coordinate system can form a three-phase voltage.

[0019] The calculated rotation angle output can be the output of the calculation algorithm.

[0020] The calculated rotational speed can be directly calculated as the change of the calculated rotational angle over time.

[0021] The calculated rotation angle and / or the calculated rotation speed output can be used to control the rotation operation of an electric motor, particularly in a current control system.

[0022] In a preferred embodiment of the invention, it is advantageous to omit the output of the calculated rotational speed used to calculate the calculated rotational speed. The calculated rotational speed can be used only for internal calculations within the calculation algorithm. The output of the calculated rotational speed can refer to the output from the calculation algorithm, particularly the output from the calculation algorithm after iterative calculations are completed.

[0023] In a preferred embodiment of the invention, the first phase voltage and / or the second phase voltage are determined by means of estimation of the first phase current and the second phase current from the current control system. Therefore, this method can be implemented more cost-effectively. The first phase voltage and / or the second phase voltage can alternatively or additionally be determined by measuring the corresponding phase voltage.

[0024] The voltage of the first phase and / or the voltage of the second phase can be measured directly or indirectly.

[0025] According to the present invention, the calculation algorithm uses a first relation that specifies a first voltage difference between the determined first phase voltage and the modeled first phase voltage. The first relation can be defined as follows based on the determined first phase voltage u. d and the modeled first phase voltage u d,m Specify the first voltage difference Δu d :

[0026] Δu d =u d -u d,m

[0027] According to the present invention, the rotation angle is calculated iteratively using a first relation in the following manner: using the rotation angle γ previously calculated in the previous calculation step. i-1 Furthermore, in the calculation step, the rotation angle is changed to reduce the first voltage difference Δγ. The rotation angle is iteratively calculated to reduce the first voltage difference Δu. d This can be achieved by iteratively adjusting the rotation angle using the following correlation:

[0028] Δu d =f(ω) i-1 γ i-1 ±Δγ)

[0029] In a particular embodiment of the invention, it is advantageous if the reduction of the first voltage difference is achieved solely through iterative adjustments to the rotation angle. Iterative adjustments to the rotation speed, particularly those made by introducing a difference in rotation speed, can be omitted.

[0030] In a particular embodiment of the invention, it is advantageous if the calculation algorithm uses a second relationship that specifies a second voltage difference between the determined second phase voltage and the modeled second phase voltage. The second relationship can be based on the determined second phase voltage u... q and the modeled second phase voltage u q,m Specify the second voltage difference Δu q :

[0031] Δu q =u q -u q,m

[0032] In a particular embodiment of the invention, it is advantageous to perform the iterative calculation of the rotational speed using the second relationship in the following manner: using the rotational speed ω previously calculated in the preceding calculation step. i-1And in the calculation steps, to make the second voltage difference Δu q The rotational speed is reduced by altering the rotational speed difference Δω. Iterative calculations of the rotational speed can be achieved by iteratively adjusting the rotational speed using the following correlation:

[0033] Δu q =f(ω) i-1 ±Δω, γ i-1 )

[0034] If the second phase voltage u in the modeling q,m The additional motor parameter p′ used is temperature-dependent and is not precisely known or unknown during rotor rotation. Therefore, the calculated rotational speed ω is adjusted iteratively using a second relationship. i Performing iterative calculations may cause a decrease in the second voltage difference, and the calculated rotational speed ω obtained in the first relationship... i It can be used to calculate the calculated rotation angle.

[0035] Therefore, the calculated rotational speed can be used as the internally calculated rotational speed to compensate for the uncertainty of the additional motor parameter p′. The calculation algorithm can compensate for possible model uncertainties caused by unknown variations in motor parameters, such as the additional engine parameter P′.

[0036] For example, if the additional motor parameter P′ is inaccurate, the iterative calculation can still find an equilibrium using the second relation if the rotational speed is adjusted in the opposite direction to the change in the additional motor parameter through iterative calculation. For instance, if the additional motor parameter P′ is small, the iterative calculation will calculate a larger rotational speed. This property of finding an equilibrium using the second relation can be utilized when feeding back the rotational speed for the next calculation step in the iterative calculation.

[0037] In an advantageous embodiment of the invention, the reduction of the second voltage difference is achieved solely through iterative adjustment of the rotation speed. Iterative adjustment of the rotation angle, particularly iterative adjustment introduced by a difference in rotation angle, can be omitted.

[0038] Furthermore, within the scope of this invention, an electric motor having the features of claim 10 is proposed to achieve at least one of the aforementioned objectives. This makes the electric motor easier and more efficient to operate.

[0039] Further advantages and advantageous embodiments of the invention will become apparent from the illustrations and figures. Attached Figure Description

[0040] The invention will now be described in detail with reference to the accompanying drawings. In particular, in the drawings:

[0041] Figure 1 The image shows an electric motor according to a specific embodiment of the present invention.

[0042] Figure 2 The illustration shows a method for determining rotational parameters according to a specific embodiment of the present invention.

[0043] Figure 1 An electric motor according to a specific embodiment of the present invention is shown. The electric motor 10 includes a stator 12 and a rotor 14, the rotor being able to rotate relative to the stator by changing a rotation angle γ. During rotational operation, the rotor 14 has a rotational speed ω that varies with the rotation angle γ. Electrical variables, such as phase voltage or phase current, can be specified in a dq coordinate system where the rotor is fixed.

[0044] Figure 2 A method for determining rotation parameters according to a specific embodiment of the present invention is shown. For example, as... Figure 1 The illustrated electric motor uses method 16 for determining rotational parameters during rotational operation, wherein the rotor is rotated relative to the stator by changing the rotation angle γ according to the rotor's rotational speed ω. Method 16 includes the following steps:

[0045] Determine the first phase voltage u in the d-direction of the d coordinate system relative to the rotor in each case. d and the first phase current i d And in each case, the second phase voltage u in the q direction relative to the fixed dq coordinate system of the rotor. q Second phase current i q ,

[0046] Using algorithm 24, perform the following operation: at least based on the first phase current i d Second phase current i q At least one electric motor parameter P, rotational speed ω, and rotational angle γ will affect the first phase voltage u. d Calculate the first phase voltage u in the 26-bit model. d，m And the second phase voltage u q Calculate the second phase voltage u for modeling q，m ,

[0047] Based on the modeled first phase voltage u d，m and the modeled second phase voltage u q,m The rotational speed ω is calculated iteratively for 27 seconds to obtain the calculated rotational speed ω. i And iteratively calculate the rotation angle γ to obtain the calculated rotation angle γ i ,

[0048] The calculated rotation angle γ i Output 28 is the calculated rotation angle γ.r ,as well as

[0049] The calculated rotation angle γ is based on the output. r The calculated rotational speed ω is calculated to be 30, which is the output of the calculated rotational speed ω. r Instead of directly using the calculated rotational speed ω i Perform the calculation.

[0050] Therefore, the calculated rotational speed ω i Internally used only for the calculated rotation angle γ i Calculations are performed. Therefore, the calculation of the output rotational speed ω is omitted. r The calculated rotational speed ω is obtained by performing calculation 30. i The output of .

[0051] First phase voltage u d Second phase voltage u q It can be from the first phase current i d Second phase current i q The current control system estimates this.

[0052] In calculation algorithm 24, a first relation 32 and a second relation 34 are used, the first relation specifying the determined first phase voltage u. d With the modeled first phase voltage u d，m The first voltage difference Δu between d The second relationship specifies the determined second phase voltage u. q With the modeled second phase voltage u q,m The second voltage difference Δu between q .

[0053] The iterative calculation 27 of the rotation angle γ using the first relation 32 is performed as follows: using the rotation angle γ previously calculated in the previous calculation step. i-1 And in the current calculation step, the first voltage difference Δu is made so that d The reduction method changes the rotation angle by the rotation angle difference Δγ. The first voltage difference Δu d The reduction is achieved specifically by iteratively adjusting the rotation angle γ. i To achieve this. The rotational speed ω is omitted during processing. i Iterative adjustments.

[0054] The iterative calculation of the rotational velocity ω using the second relation 34 is performed as follows: using the rotational velocity ω previously calculated in the previous calculation step. i-1 And in the current calculation step, to make the second voltage difference Δu q The reduction method changes the rotational speed by a difference in rotational speed Δω. The second voltage difference Δuq The reduction is specifically achieved by iteratively adjusting the rotational speed ω. i This is achieved by omitting the rotation angle γ during processing. i Iterative adjustments.

[0055] The calculated rotational speed ω output r and the calculated rotation angle γ output r Filter 32 can be used to calculate the rotation angle γ. i calculate.

[0056] List of reference numerals

[0057] 10 Electric motors

[0058] 12 stators

[0059] 14 Rotors

[0060] 16 methods

[0061] 20 Confirmed

[0062] 22 Use

[0063] 24 Calculation Algorithm

[0064] 26 Calculation

[0065] 27 Iterative Calculation

[0066] 28 Output

[0067] 30 Calculation

[0068] 32 First Relationship

[0069] 34 Second Relationship

[0070] P Electric motor parameters

[0071] Δu d First voltage difference

[0072] Δu q Second voltage difference

[0073] Δγ Rotation angle difference

[0074] Δω is the difference in rotational speed.

[0075] γ rotation angle

[0076] γ i Calculated rotation angle

[0077] γ r The calculated rotation angle output

[0078] γi-1 Previously calculated rotation angle

[0079] ω Rotational speed

[0080] ω i Calculated rotational speed

[0081] ω r The calculated rotational speed output

[0082] ω i-1 Previously calculated rotational speed

[0083] i d First phase current

[0084] i q Second phase current

[0085] u d First phase voltage

[0086] u q Second phase voltage

[0087] u d,m The first phase voltage in the model

[0088] u q,m Modeling the second phase voltage

Claims

1. A method (16) for determining a rotational parameter of at least a rotational angle (γ) of a rotor (14) of an electric motor (10), the rotor being rotatable relative to a stator (12), the rotational angle varying according to a rotational speed (ω), the method comprising the steps of: Determine (20) the first phase voltage (u) in the d direction relative to the rotor-fixed dq coordinate system in each case. d ) and the first phase current (i d ) and in each case, the second phase voltage (u) in the q direction relative to the rotor-fixed dq coordinate system. q ) and second phase current (i q ), The following operation is performed using calculation algorithm (24) (22): at least based on the first phase current (i d ) and the second phase current (i q At least one electric motor parameter (P), the rotational speed (ω), and the rotational angle (γ) will affect the first phase voltage (u). d )Calculate (26) the first phase voltage (u) for modeling d，m ) and the second phase voltage (u q ) calculate the second phase voltage (u) for modeling q，m ), and based on the determined first phase voltage (u d ) and the determined second phase voltage (u q ) and the modeled first phase voltage (u d，m ) and the modeled second phase voltage (u q，m The rotational speed (ω) is iteratively calculated (27) to obtain the calculated rotational speed (ω). i ) and iteratively calculate the rotation angle (γ) to obtain the calculated rotation angle (γ). i ), The calculated rotation angle (γ) i The output (28) is the calculated rotation angle (γ) output. r ),as well as The calculated rotation angle (γ) based on the output is as follows. r The rotational speed (ω) is calculated (30) as the output calculated rotational speed (ω). r Instead of directly using the calculated rotational speed (ω) i ) to perform calculations, Its features are, The calculation algorithm (24) uses a first relation (32), which specifies the determined first phase voltage (u). d ) and the modeled first phase voltage (u d，m The first voltage difference (Δu) between ) d ),and The iterative calculation (27) of the rotation angle (γ) using the first relationship (32) is performed in the following manner: using the rotation angle (γ) previously calculated in the previous calculation step. i-1 And in the calculation step, the first voltage difference (Δu) is made so that d The rotation angle is reduced by changing the rotation angle difference (Δγ).

2. The method (16) according to claim 1, characterized in that, The calculated rotational speed (ω) used for the output is omitted. r The calculated rotational speed (ω) is used for calculation. i ) output.

3. The method (16) according to claim 1 or 2, characterized in that, Through the first phase current (i d ) and the second phase current (i q The estimation of the current control system determines (20) the first phase voltage (u). d ) and / or the second phase voltage (u q ).

4. The method (16) according to any one of claims 1 to 3, characterized in that, The first voltage difference (Δu) d The reduction of ) is achieved only by iteratively adjusting the rotation angle (γ). i To achieve this.

5. The method (16) according to any one of claims 1 to 4, characterized in that, The calculation algorithm (24) uses a second relation (34), which specifies the determined second phase voltage (u). q ) and the modeled second phase voltage (u q，m The second voltage difference (Δu) between q ).

6. The method (16) according to claim 5, characterized in that, The iterative calculation (27) of the rotational speed (ω) using the second relation (34) is performed in the following manner: using the rotational speed (ω) previously calculated in the previous calculation step. i-1 And in the calculation step, to make the second voltage difference (Δu) q The rotational speed is reduced by changing the rotational speed difference (Δω).

7. The method (16) according to claim 6, characterized in that, The second voltage difference (Δu) q The reduction of ) is achieved only by iteratively adjusting the rotational speed (ω). i To achieve this.

8. An electric motor (10) having a stator (12) and a rotor (14), the rotor being rotatable relative to the stator by changing a rotation angle (γ), the rotation angle (γ) being determined by determining rotation parameters according to the method (16) of the preceding claim.

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