Method for determining rotation parameters of rotation angle and electric motor

Abstract

The present invention is a method (16) for determining at least one variable rotation angle (γ) of a rotor (14) of an electric motor (10) rotatable with respect to a stator (12), wherein said angle depends on a rotational speed (ω), and said method comprises the following steps: for the d - direction of a dq coordinate system fixed to the rotor, each of a first phase voltage (u d ) and a first phase current (i d ), and for the q - direction, each of a second phase voltage (u q ) and a second phase current (i q ) are determined in a step (20); a rotational speed (ω) is set as a calculated rotational speed (ω i ), and a rotation angle (γ) is set as a calculated rotation angle (γ i ), and a calculation algorithm (24) having an iterative calculation (27) is applied in a step (22); the calculated rotation angle (γ i ) is output as an output calculated rotation angle (γ r ) in a step (28); the rotational speed (ω) is calculated as an output calculated rotational speed (ω i ) from the output calculated rotation angle (γ r ) without directly calculating the calculated rotational speed (ω r ) in a step (30). The present invention also relates to an electric motor (10).

Description

Technical Field

[0001] The present invention relates to a method for determining a rotation parameter according to claim 1. The present invention further relates to an electric motor.

Background Art

[0002] When the rotor of an electric motor rotates and sufficient back electromotive voltage is thereby available, in the case of a permanent magnet synchronous motor, a method based on a voltage model according to the voltage equation of the electrical phase voltage is used to determine the rotation parameter. The phase voltage is first measured and then calculated as the modeled phase voltage using the voltage model. This voltage model also includes the electrical phase current and the electric motor parameters. The voltage error in the dq coordinate system is calculated from the difference between the measured phase voltage and the modeled phase voltage. The rotation angle and the rotation speed are calculated by reducing the voltage error.

[0003] In M.Brodatzki, J.Richter, J.Kolb and M.Braun, “Position and Speed Estimation Algorithm for Permanent Magnet Synchronous Machines Considering Nonlinear Magnetic Effects,” 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia), 2019, pp.1 - 8, an iterative calculation is described in which, in one calculation step, starting from the solutions of the rotation angle and the rotation speed from the previous calculation step, four voltage errors in the d direction and the q direction are calculated by changing the rotation angle and the rotation speed. By applying the two-dimensional secant method, the calculated rotation angle and the calculated rotation speed are calculated as the solutions of the non-linear simultaneous equations of the voltage model.

[0004] If the motor parameters used in the voltage model are incorrectly estimated, for example due to the influence of temperature, this can lead to errors and / or delays in the calculation of the calculated rotation angle and calculated rotation speed.

[0005] In Electrical Engineering in Japan, vol.146, 2004, No.3, 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 [especially]: Sensorless controls of salient-pole permanent magnet synchronous motors using extended electromotive force models describes a mathematical model for synchronous motors that enables determination of rotor position without approximation, and a sensorless control method based thereon. [Overview of the project] [Problems that the invention aims to solve]

[0006] The objective of this invention is to determine the rotation parameters of an electric motor more accurately, easily, and quickly. [Means for solving the problem]

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

[0008] An electric motor can be installed inside a vehicle. The vehicle can be an automobile. The electric motor can provide the driving force to move the vehicle and / or to operate vehicle components. Vehicle components can be auxiliary units, in particular a fluid pump. The fluid pump can be a hydraulic pump.

[0009] An electric motor can be operated in encoderless mode. This method can be implemented while the electric motor is in encoderless mode. An electric motor can be operated exclusively in sensorless mode. Sensorless mode is understood to mean a mode that does not incorporate the rotation angle measured by a sensor, such as a position sensor.

[0010] An electric motor can be controlled via 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 output calculation rotational speed can be calculated as the change in the output calculation rotational angle over time.

[0012] The modeled first phase voltage and the modeled second phase voltage can be calculated using a voltage model. d,m The first phase current i is as follows: d and the second phase current i q It can be calculated accordingly:

number

[0013] Modeled second phase voltage u q,m This can be calculated using a voltage model as follows:

number

[0014] The first and second phase voltages in the dq coordinate system can be calculated from 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 three phase voltages.

[0015] The output as the calculated rotation angle can be the output from the calculation algorithm.

[0016] The output calculation rotation speed can be directly calculated as the change in the output calculation rotation angle over time.

[0017] The calculated output rotation angle and / or calculated output rotation speed can be used to control the rotational motion of an electric motor, particularly in current control systems.

[0018] In a preferred embodiment of the present invention, it is advantageous to omit the output of the calculated rotational speed for calculating the output calculated rotational speed. The calculated rotational speed can be used only for the internal calculations of the calculation algorithm. The output of the calculated rotational speed may, in particular, refer to the output from the calculation algorithm after the completion of the iterative calculations.

[0019] In a preferred embodiment of the present invention, the first phase voltage and / or the second phase voltage are determined by estimation of the first phase current and the second phase current from a current control system. As a result, the method can be implemented more cost-effectively. The first phase voltage and / or the second phase voltage can also be determined by measuring the corresponding phase voltages, either alternatively or additionally.

[0020] The first phase voltage and / or the second phase voltage can be measured directly or indirectly.

[0021] According to the present invention, the calculation algorithm uses a first relationship that identifies a first voltage difference between the determined first phase voltage and the modeled first phase voltage. The first relationship, as follows, determines the first voltage difference Δu d in accordance with the determined first phase voltage u d,m and the modeled first phase voltage u d and can identify it. Δu d = u d - u d,m

[0022] According to the present invention, the rotation angle is calculated iteratively using the first relationship in such a way that the rotation angle γ i-1 previously calculated in a previous calculation step is used, and the rotation angle is changed by the rotation angle difference Δγ in the calculation step so that the first voltage difference is reduced. The iterative calculation of the rotation angle to reduce the first voltage difference Δu d can be implemented by iteratively adjusting the rotation angle using the following dependencies. Δu d = f(ω i-1 , γ i-1 ±Δγ)

[0023] In a particular embodiment of the present invention, it is advantageous if the reduction of the first voltage difference is achieved exclusively by iterative adjustment of the rotation angle. In particular, the iterative adjustment of the rotational speed by introducing a rotational speed difference can be omitted.

[0024] In a particular embodiment of the present invention, it is advantageous if the calculation algorithm uses a second relationship that identifies a second voltage difference between the determined second phase voltage and the modeled second phase voltage. The second relationship, as follows, determines the second voltage difference Δu q in accordance with the determined second phase voltage u q,m and the modeled second phase voltage u q and can identify it. Δu q = u q - u q,m

[0025] In a particular embodiment of the present invention, the preceding calculation step ω i-1 In the previously calculated rotation speed, the second voltage difference Δu q It is advantageous when the iterative calculation of rotational speed is performed using the second relation, in that the rotational speed difference Δω is changed in the calculation step so that the reduction is achieved. The iterative calculation of rotational speed can be implemented by iteratively adjusting the rotational speed using the following dependency. Δu q =f(ω i-1 ±Δω,γ i-1 )

[0026] Modeled second phase voltage u q,m If the additional motor parameter P' used is temperature-dependent and not precisely known or unknown during the rotor's rotational operation, the calculated rotational speed ω i Iterative calculations using the second relationship, achieved by iteratively adjusting the first relationship, can lead to a reduction in the second voltage difference, and the resulting calculated rotation speed ω in the first relationship i This can be used to calculate the rotation angle.

[0027] This allows the calculated rotational speed to be used internally as the calculated rotational speed to compensate for the uncertainty of the additional motor parameter P'. The calculation algorithm can compensate for the uncertainty of the model that may be caused by unknown changes in motor parameters, such as the additional engine parameter P'.

[0028] For example, if the additional engine parameter P' is inaccurate, the iterative calculation can still find equilibrium with the second relationship if the rotational speed is adjusted in the opposite direction to the change in the additional motor parameter by the iterative calculation. For example, if the additional motor parameter P' is smaller, the iterative calculation will calculate a larger rotational speed. This property of finding equilibrium with the second relationship can be used when feeding back the rotational speed for the next calculation step of the iterative calculation.

[0029] In an advantageous embodiment of the present invention, the reduction of the second voltage difference is achieved solely by iterative adjustment of the rotational speed. In particular, iterative adjustment of the rotational angle by introducing a rotational angle difference can be omitted.

[0030] Furthermore, within the scope of the present invention, an electric motor having the features described in claim 10 is proposed to achieve at least one of the objectives mentioned above. This makes it possible to operate the electric motor more conveniently and efficiently.

[0031] Further advantages and advantageous embodiments of the present invention are evident from the description and drawings.

[0032] The present invention will be described in detail below with reference to the drawings. [Brief explanation of the drawing]

[0033] [Figure 1] This shows an electric motor in a specific embodiment of the present invention. [Figure 2] This invention provides a method for determining rotation parameters in a specific embodiment of the present invention. [Modes for carrying out the invention]

[0034] Figure 1 shows an electric motor in a specific embodiment of the present invention. The electric motor 10 comprises a stator 12 and a rotor 14 that is rotatable relative to the stator by changing the rotation angle γ. During rotational operation, the rotor 14 has a rotational speed ω that changes the rotation angle γ. Electrical variables such as phase voltage or phase current can be specified in a rotor-fixed dq coordinate system.

[0035] Figure 2 shows a method for determining rotational parameters in a particular embodiment of the present invention. Method 16 for determining rotational parameters is used, for example, during the rotational operation of an electric motor as shown in Figure 1, and rotates the rotor relative to the stator by changing the rotation angle γ according to the rotational speed ω of the rotor. Method 16 consists of the following steps: The first phase voltage u in each example with respect to the d direction in a rotor-fixed dq coordinate system. d and the first phase current i d , and the second phase voltage u in each example with respect to the q direction q and the second phase current i q Step 20 determines each of the following, at least the first phase current i d and the second phase current i q Depending on at least one electric motor parameter P, rotational speed ω, and rotational angle γ, the first phase voltage u d The first phase voltage u is modeled d,m as, and the second phase voltage u q The second phase voltage u is modeled q,m Step 22 involves using a computation algorithm 24 which has a calculation 26 as, Modeled first phase voltage u d,m and the second phase voltage u q,m Depending on the result, the rotational speed ω is calculated as follows: i As, and the rotation angle γ, calculate the rotation angle γ i Step 27 involves iteratively calculating as follows: Calculated rotation angle γ i The output calculation rotation angle γ r Step 28 outputs as follows: The rotation speed ω is calculated as the rotation speed ω i Without directly calculating from it, the output rotation speed ω r For example, the output calculation rotation angle γ r This includes step 30, which is calculated from the above.

[0036] Therefore, the calculated rotation speed ω i This is primarily used for calculating the rotation angle γ i Used internally to calculate the output rotation speed ω.r Calculate rotational speed ω for 30 i The output is therefore omitted.

[0037] First phase voltage and second phase voltage u d u q This is the first phase current i d and the second phase current i q This can be estimated from the current control system.

[0038] In the calculation algorithm 24, the first phase voltage u that was determined d The first phase voltage u is modeled as follows: d,m The first voltage difference Δu between d The first relation 32 that identifies the second phase voltage u is used and determined q The second phase voltage u is modeled as follows: q,m The second voltage difference Δu between q A second relation 34 is used to identify it.

[0039] The iterative calculation of rotation angle γ 27 is performed by performing the rotation angle γ previously in the preceding calculation step. i-1 However, it is used, and the first voltage difference Δu d The first relation 32 is used in the current calculation step, in which the rotation angle difference Δγ is changed so that the first voltage difference Δu d The reduction of is particularly due to the rotation angle γ i This is achieved by iteratively adjusting the rotation speed ω. i The iterative adjustments are omitted in this process.

[0040] The iterative calculation of rotational speed ω 27 is performed by first calculating the rotational speed ω in the preceding calculation step. i-1 However, the second voltage difference Δu is used. q The second relation 34 is used in the current calculation step, in which the rotational speed difference Δω is changed so that the second voltage difference Δu q The reduction is particularly due to the rotational speed ω i This is achieved by iteratively adjusting the rotation angle γ iIterative adjustment is omitted in this process.

[0041] Output calculated rotational speed ω r and output calculated rotation angle γ r can be calculated from the calculated rotation angle γ i using the filter 32.

Explanation of symbols

[0042] 10 Electric motor 12 Stator 14 Rotor 16 Method 20 Judgment 22 Use 24 Calculation algorithm 26 Calculation 27 Iterative calculation 28 Output 30 Calculation 32 First relationship 34 Second relationship P Electric motor parameter Δu d First voltage difference Δu q Second voltage difference Δγ Rotation angle difference Δω Rotational speed difference γ Rotation angle γ i Calculated rotation angle γ r Output calculated rotation angle γ i-1 Previously calculated rotation angle ω Rotational speed ω i Calculated rotational speed ω r Output calculated rotational speed ω i-1 Previously calculated rotational speed i d First phase current i q Second phase current u d First phase voltage u q Second phase voltage ud,m Modeled first phase voltage u q,m Modeled second phase voltage

Claims

1. A method (16) for determining a rotational parameter of at least a rotation angle (γ) of a rotor (14) of an electric motor (10) that is rotatable relative to a stator (12), wherein the rotational parameter is variable according to the rotational speed (ω), the method comprising the following steps: The first phase voltage (u) in each example with respect to the d direction in a rotor-fixed dq coordinate system. ｄ ) and the first phase current (i ｄ ), and the second phase voltage (u) in each example with respect to the q direction ｑ ) and the second phase current (i ｑ The step (20) of determining ) At least the first phase current and the second phase current (i ｄ , i ｑ ), at least one electrical motor parameter (P), the rotational speed (ω), and the rotation angle (γ), the modeled first phase voltage (u ｄ ) of the first phase voltage (u ｄ，ｍ ), and the second phase voltage (u ｑ ) as the modeled second phase voltage (u ｑ，ｍ ), the calculation (26), and the determined first phase voltage and second phase voltage (u ｄ , u ｑ ) and the modeled first phase voltage and second phase voltage (u ｄ，ｍ , u ｑ，ｍ ), the rotational speed (ω) as the calculated rotational speed (ω ｉ ), and the rotation angle (γ) as the calculated rotation angle (γ ｉ ), the iterative calculation (27), and using the calculation algorithm (24) having the above, in step (22); The calculated rotation angle (γ ｉ ) is used to calculate the rotation angle (γ ｒ Step (28) to output as, The rotational speed (ω) is the calculated rotational speed (ω) ｉ Without directly calculating from ), the output rotation speed (ω ｒ ) as the output calculation rotation angle (γ ｒ The steps include (30) which are calculated from ) and The calculation algorithm (24) determines the first phase voltage (u ｄ ) and the modeled first phase voltage (u ｄ，ｍ The first voltage difference (Δu) between ) ｄ Using the first relationship (32) to identify ), The rotation angle (γ) previously calculated in the preceding calculation step ｉ－１ ) is used, and the first voltage difference (Δu ｄ Method (16), characterized in that the iterative calculation (27) of the rotation angle (γ) using the first relationship (32) is performed such that the rotation angle difference (Δγ) is changed in the calculation step so that the ) is reduced.

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

3. The first phase voltage and / or the second phase voltage (u ｄ , u ｑ The determination (20) of the first phase current and the second phase current (i ｄ , i ｑ The method according to claim 1 or 2 (16), which is performed by estimation from a current control system of ).

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

5. The calculation algorithm (24) determines the second phase voltage (u ｑ ) and the modeled second phase voltage (u ｑ，ｍ The second voltage difference (Δu) between ) ｑ The method according to any one of claims 1 to 4 (16), characterized by using a second relationship (34) that identifies ).

6. The rotational speed (ω) previously calculated in the preceding calculation step ｉ－１ ) is used, and the second voltage difference (Δu ｑ The method according to claim 5 (16), characterized in that the iterative calculation (27) of the rotational speed (ω) is performed using the second relationship (34), in which the rotational speed difference (Δω) is changed in the calculation step so that the ) is reduced.

7. The second voltage difference (Δu ｑ The reduction of ) is primarily due to the rotational speed (ω ｉ The method according to claim 6 (16), characterized in that it is achieved by iterative adjustment of ).

8. An electric motor (10), comprising a stator (12) and a rotor (14) which is rotatable relative to the stator by changing the rotation angle (γ), and which has a rotation angle (γ) that can be determined by determining the rotation parameter according to the method (16) of any one of claims 1 to 7.

Images