Angle adaptation circuit and control system
By introducing an angle adaptation circuit into the motor control system, using torque and speed information to output angle offsets and adapt the motor angle, the problem of low efficiency in the existing technology at low torque and medium and low speeds is solved, and more efficient operation point optimization is achieved.
Patent Information
- Application Number
- CN202380075927.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-21
- Filing Date
- 2023-12-19
- Publication Date
- 2025-05-30
AI Technical Summary
The existing motor control systems are less efficient at low torque and medium-low speeds, making it difficult to achieve effective operating point optimization.
An angle adaptation circuit is designed to output angle offset by receiving torque information and motor speed information, and thereby adapting to the angle of the motor, thereby actively shifting the operating point and optimizing the voltage set point.
Through angle offset adaptation, the motor efficiency at low torque and medium speed is improved, the computing power is reduced, and the online angle adaptation process is simplified.
Smart Images
Figure CN120077566A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an angle adaptation circuit for shifting an angle offset used by a control system of an electric motor. Furthermore, the present invention relates to a control system for an electric motor. Background Art
[0002] In the prior art, control systems for electric motors are known, which include a control system for outputting a voltage setpoint based on an operating point of the electric motor. The control system typically includes a current setpoint determination module, a current controller, and a voltage modulation module. These components of the control system are used to control the duty cycle of the (power) switches of an inverter coupled to the electric motor.
[0003] These control systems also include an angle evaluation module configured to determine the actual angle of the electric motor, and the control system determines the voltage setpoint accordingly based on this actual angle.
[0004] Typically, the operating point based on which the voltage setpoint is determined is optimized based on maximum torque per ampere (MTPA) and maximum torque per flux (MTPF), also known as maximum torque per voltage (MTPV). However, it turns out that these known operating point optimizations have disadvantages for low torque and low speed values.
[0005] Therefore, an optimized system for use at low torque and medium - low speed values is needed. Summary of the Invention
[0006] The present invention provides an angle adaptation circuit for shifting an angle used by a control system of an electric motor. The angle adaptation circuit includes at least one input for receiving torque information and / or speed information of the electric motor. The angle adaptation circuit includes an adaptation module connected to the at least one input. The adaptation module is configured to process the information received via the at least one input and output an angle offset to be applied to the angle value of the electric motor.
[0007] The angle offset is used to deviate the angle used to determine the voltage setpoint of the electric motor from the actual position of the electric motor rotor.
[0008] Then, a shifted angle value corresponding to the sum of the angle offset output from the angle adaptation circuit and the angle value of the electric motor is used to determine an operating point for calculating the voltage setpoint of the electric motor.
[0009] Preferably, the angle value corresponds to a position sensor measurement corrected for mechanical and electrical misalignment.
[0010] Furthermore, the present invention provides a control system for an electric motor. The control system includes a controller, for example, for outputting a voltage setpoint based on an operating point of the electric motor. The control system also includes an angle evaluation module configured to determine the angle value of the electric motor and the angle adaptation circuit as described above.
[0011] Accordingly, the angle evaluation module determines the angle value of the motor adapted by the applied angle offset, thereby obtaining the shifted angle value. In fact, the shifted angle value can be obtained by adding the angle offset to the angle value. The shifted angle value is forwarded to the controller, which in particular processes the shifted angle value in order to determine the voltage setpoint for the motor.
[0012] The angle evaluation module determines the angle value based on the position information from the motor rotor. For example, the angle value is determined by measuring the rotor position with a position sensor, and a correction value is added to the angle value. Due to the correction value, the angle value is determined more precisely and better corresponds to the actual position of the rotor, which enables more precise control of the motor. The main idea of the present invention is to actively adapt the angle by adding an angle offset, thereby manipulating the current setpoint. The voltage setpoint can be determined based on the current setpoint. Thus, the current setpoint is actively manipulated by the angle offset adaptation, which is processed by the (current) controller of the control system for controlling the motor. In fact, the controller can determine the voltage setpoint based on the manipulated current setpoint.
[0013] In other words, the controller receives the shifted angle (value) and the current setpoint. The controller processes the shifted angle as well as the current setpoint in order to determine the voltage setpoint, which is in particular used to control the inverter, especially the power switches. Thus, the angle offset adaptation results in an optimization of the operating point, since the operating point is actively shifted due to the angle offset applied to the determined angle value.
[0014] Generally, the angle offset applied to the determined angle can lead to an adapted / shifted angle offset. In other words, the determined angle is used to identify the angle offset, which is manipulated by the angle offset determined by the angle adaptation circuit.
[0015] The angle offset is determined based on the received information, i.e., torque information and / or speed information of the motor is added to the previously determined and / or measured motor angle value.
[0016] In particular, the optimization based on the angle offset adaptation is used for low torques and medium - low speed values, for example in the range of + / - 500 Nm and / or 0 - 600 rpm, especially + / - 300 Nm and / or 0 - 400 rpm or 100 - 400 rpm. It should be understood that these range examples are only for illustrative purposes, since the range is highly dependent on the motor design. These ranges typically relate to rolling vehicles with friction compensation or slight acceleration / braking, where the motor still operates with the maximum torque per ampere (MTPA) strategy. In other words, the angle adaptation can be restricted to low absolute speeds and / or low absolute torque values. In fact, within this specific range, the angle offset is less sensitive to torque accuracy.
[0017] Once the requested torque or the estimated torque leaves the associated operating range, the angle offset adaptation is tilted to zero. Thus, sudden shocks due to the greater torque resulting from switching back to the MTPA trajectory are prevented. Additionally, if the torque suddenly approaches the unit modulation index, it also prevents shocks when switching back to MTPV.
[0018] Due to the shifted angle, the resulting torque is reduced. However, this reduced torque is not significant at the desired operating points, because the torque accuracy margin at these low torque operating points is absolute and large compared to other operating points, especially higher torque operating points. Additionally, the inaccurate or reduced torque will be compensated for by the driver.
[0019] Typically, the angle adaptation, i.e., the applied angle offset, shifts the operating point of the current from MTPA closer to the maximum torque of the MTPL trajectory per loss, thereby increasing efficiency.
[0020] Compared to MTPL implementation, the dependency is reduced, thereby lowering the overall computational power required.
[0021] In fact, the angle adaptation circuit as well as the control system are suitable for implementation in automotive embedded systems.
[0022] Thus, a simplified online angle adaptation is obtained, which is used to manipulate the setpoint of the controller in order to maximize the efficiency of the entire system. In particular, the angle adaptation circuit as well as the control system overcome the efficiency gap in the low speed / torque operating points frequently used during a standard driving cycle.
[0023] At least one input can relate to an interface, such as a data interface, via which the corresponding data / information is obtained and processed.
[0024] Typically, the inverter operates based on a current setpoint and a voltage setpoint, which define the control of the inverter.
[0025] One aspect provides that at least one input is also configured to receive information about the DC link voltage and / or information about the temperature of the motor. For example, the temperature of the permanent magnets of the motor is received via at least one input. The corresponding temperature can be measured or estimated, for example, by an observer.
[0026] Thus, the angle offset is determined based on different kinds of information, namely torque information, motor speed information, DC voltage information, and / or motor temperature information. These different kinds of information are processed by the angle adaptation circuit in order to determine the angle offset to be applied. Thus, the angle offset to be applied can be determined more precisely, because different types of information are processed and considered accordingly. For example, since the iron losses (eddy current and hysteresis losses) depend on the temperature of the motor, temperature-related adaptation is performed by also considering the temperature information of the motor.
[0027] Typically, angle offset adaptation, i.e., applying an angle offset, results in manipulation of the current setpoint processed by the controller, which leads to a reduction in iron losses.
[0028] On the other hand, torque information corresponding to the estimated actual torque and / or the input torque setpoint is provided. In other words, the information on torque can relate to the requested torque (torque setpoint) or the actual torque estimated by a torque observer. The angle adaptation circuit can receive the estimated actual torque and the input torque setpoint.
[0029] On the other hand, it is provided that the adaptation module includes a look-up table (LUT) that associates the information received via at least one input with an angle offset. Thus, the look-up table ensures that the angle offset can be determined in an easy and simple manner, since the received information is checked against the entries of the look-up table in order to determine the corresponding angle offset to be applied. In other words, the look-up table includes information related to the operating point, such as torque and / or speed, and the corresponding angle offsets.
[0030] Furthermore, linear interpolation can be performed between operating points, such that the angle offset can be determined even if the look-up table does not include angle offset entries for a certain constellation.
[0031] The look-up table (and the interpolation technique) ensures that the computational power can be minimized, such that the implementation of the angle adaptation circuit is simple. In fact, it requires very low processing and storage capabilities. Furthermore, the memory consumption is generally reduced.
[0032] The adaptation module can include a filter module configured to filter a pre-adapted angle offset in order to obtain an angle offset. The filter module can avoid sudden jumps within the shifted angle. In order to filter the pre-adapted angle offset, the filter module can apply a filtering function. The filtering function can take into account the previous angle offset. This ensures a smooth transition of the angle offset, thereby avoiding current peaks that may occur when the shifted angle jumps. The filtering function can also take into account the temperature of the motor and / or the DC link voltage, in particular all types of information input via at least one input.
[0033] Furthermore, the angle adaptation circuit can be an additional circuit configured to be implemented into a control system for a motor. Thus, the angle adaptation circuit has an interface that can be connected to an already existing control system, such that the already existing control system is extended by the angle adaptation circuit. Thus, the function regarding angle offset adaptation is added to the already existing control system. The functions of the already existing control system for the motor can be extended due to the additional circuit.
[0034] In one aspect, it is provided that the angle evaluation module and the angle adaptation circuit are connected to each other in a node, and the node is configured to process the angle value determined by the angle evaluation module and the angle offset output by the angle adaptation circuit, so as to determine the shifted angle. The corresponding angle (value) is adapted to obtain the shifted angle value that is forwarded to the controller. In fact, the existing offset may be changed due to the angle offset being determined and applied to the angle.
[0035] In particular, the node is connected to the controller such that the controller is configured to receive the shifted angle value, so as to shift the operating point for the motor. The operating point is actively shifted based on the angle offset determined by the angle adaptation circuit. As described above, the angle offset is determined based on different types of information.
[0036] The angle evaluation module can be an angle sensor configured to measure the actual angle of the motor or an angle observer configured to estimate the actual angle of the motor. Therefore, the corresponding angle value adapted by the angle offset output by the angle adaptation circuit can be measured or estimated. This depends on the corresponding type of the angle evaluation module.
[0037] Generally, the control system, especially the current controller and the module for setpoint determination, operates in a known method, namely MPTA, which maintains applying the minimum amount of current to generate the desired torque.
[0038] The angle adaptation circuit observes the input torque setpoint, the actual torque, and / or the motor speed. Optionally, the motor permanent magnet temperature and / or the DC link voltage are also observed by the angle adaptation circuit.
[0039] Based on the observed parameters, that is, by accessing the look-up table through the adaptation module, an angle offset is generated to be added to the determined angle value, that is, the measured or estimated angle value. Therefore, angle offset adaptation occurs.
[0040] The adaptation module can generate the angle offset by interpolating the angle offset stored in the look-up table. In fact, this depends on the operating point related to the observed parameters. Description of the Drawings
[0041] When referring to the following description in conjunction with the drawings, more aspects and advantages of the claimed subject matter will become easier to understand and will be better understood. In the drawings,
[0042] Figure 1 a general overview of the control system according to the present invention is shown, and
[0043] Figure 2 is shown in Figure 1 a general overview of the angle adaptation circuit according to the present invention implemented in the control system. Detailed Description
[0044] InFigure 1 In FIG. Figure 1 , a system 10 is shown, which includes a control system 12 for an electric motor 14, and the electric motor 14 is powered by an inverter 16 located between the electric motor 14 and the control system 12.
[0045] The control system 12 is generally configured to control the respective power switches of the inverter 16 in order to control the electric motor 14, for example, to supply power to the respective windings of the electric motor 14. This control is based on different set points, particularly a voltage set point and a current set point.
[0046] The control system 12 includes a current set point determination module 18, which has at least one input terminal 20, and the current set point determination module 18 receives torque information, speed information of the electric motor 14, temperature information of the electric motor 14, and / or DC link voltage information through this input terminal.
[0047] The current set point determination module 18 can process these different types of information in order to determine the current set point output via the output terminal 22. This processing can be based on the implementation of maximum torque per ampere (MTPA) or maximum torque per flux (MTPF).
[0048] The control system 12 further includes a current controller 24 connected to the current set point determination module 18. The current controller 24 receives the current set point through an input terminal 26 connected to the output terminal 22 of the current set point determination module 18.
[0049] The current controller 24 is configured to process the current set point received via the input terminal 26 in order to determine the voltage set point output via the output terminal 28. The voltage set point can be determined based on the current set point and information about the angle of the electric motor 14, which will be described in more detail later.
[0050] The voltage set point output by the current controller 24 via its output terminal 28 is forwarded to a voltage modulation module 30, which processes the voltage set point to determine the duty cycles of the different power switches of the inverter 16. Accordingly, the operation of the electric motor 14 is controlled.
[0051] The control system 12 further includes a current evaluation module 32, which is configured to measure current values, particularly the alternating current (AC) values output by the inverter 16, which are forwarded to the electric motor 14 for operating purposes, particularly the windings of the electric motor 14.
[0052] In addition, the control system 12 includes an angle evaluation module 34, which is configured to determine the angle value of the electric motor 14, particularly its rotor.
[0053] The angle evaluation module 34 can be an angle sensor that measures the actual angle of the electric motor 14. Alternatively, the angle evaluation module 34 is an angle observer that estimates the actual angle of the electric motor 14.
[0054] The angle evaluation module 34 determines an angle value based on measured or estimated position information, and a correction value 35 is added to this position information. The angle value thus better corresponds to the actual position of the rotor. The correction value 35 aligns the angle value from the position sensor with the magnetic d-axis of the motor, correcting the mechanical (and electrical) angle shift. An example of determining the angle value is described in patent EP3857704, the content of which is incorporated herein by reference.
[0055] In any case, the angle evaluation module 34 obtains an angle value corresponding to the actual angle value of the electric machine 14. Thus, the actual offset can be derived from the determined angle value.
[0056] Furthermore, the control system 12 includes an angle adaptation circuit 36 as an additional circuit. The angle adaptation circuit 36 can be used to expand an existing control system, namely a control system including the various components described above.
[0057] The angle adaptation circuit 36 has an input terminal 38 through which the angle adaptation circuit 36 receives torque information, speed information of the electric machine 14, DC link voltage information, and / or temperature information of the electric machine 14, in particular the temperature of the permanent magnets of the electric machine 14. As Figure 1 shown, the angle adaptation circuit 36 can receive information for estimating the actual torque and information on the input torque setpoint.
[0058] Generally, the angle adaptation circuit 36 is capable of processing the input information in order to determine an angle offset output via its output terminal 40, where the angle offset is applied to the angle value of the electric machine 14 output by the angle evaluation module 34.
[0059] As Figure 1 shown, the control system 12 includes a node 42 that processes the angle value output by the angle evaluation module 34 and the angle offset output by the angle adaptation circuit 36. In particular, the angle offset is added to the angle value.
[0060] Thus, the determined angle value is shifted due to the added angle offset, thereby obtaining a shifted angle (value).
[0061] The shifted angle (value) is forwarded to the current controller 24, in particular to the feedback input terminal 44.
[0062] The current controller 24 also processes the shifted angle (value) in order to determine a voltage setpoint.
[0063] Therefore, the voltage setpoint is determined by the current controller 24 based on the shifted angle (value) obtained by the angle evaluation module 34 and the angle adaptation circuit 36, and the angle adaptation circuit 36 outputs an angle offset for the angle value applied to the motor 14. Thus, due to the angle offset adaptation, the operating point of the motor 14 is actively shifted, thereby optimizing the operation of the motor 14, especially for low torque and / or medium to low speeds.
[0064] The control system 12 further includes a transformation module 45, such as a Park - Clarke transformation module, also known as a d / q transformation module.
[0065] The transformation module 45 processes the shifted angle value and the current information output by the current evaluation module 32, especially the phase current value, in order to provide the actual current values in different coordinate systems, such as a coordinate system based on two axes, namely d and q.
[0066] These current values are forwarded to the current controller 24, which also processes this information in order to determine the voltage setpoint output at its output 28.
[0067] In Figure 2 it is shown in more detail the angle adaptation circuit 36.
[0068] The angle adaptation circuit 36 includes an adaptation module 46, which processes the information received via at least one input 38 and outputs an angle offset for the angle value applied to the motor 14 via the output 40, thereby obtaining the angle adaptation.
[0069] The adaptation module 46 includes a look - up table 47, which processes torque information, especially the estimated torque, and the speed information of the motor 14.
[0070] Based on this information, the look - up table 46 outputs a pre - adapted angle offset ("gamma_angle_adaption_unfilt"), which is further processed by the filter module 48 in order to obtain the angle offset for the angle adaptation ("gamma_angle_adaption").
[0071] Therefore, the look - up table 47 associates the information received via the input 38 with the angle offset, especially the pre - adapted angle offset.
[0072] In addition, Figure 2 it is shown that the pre - adapted angle offset is obtained by processing the temperature information of the motor 14, especially the rotor temperature and / or the permanent magnet temperature, and the information of the DC - link voltage.
[0073] The angle adaptation circuit 36 includes a state determination module 50 that receives the speed information, temperature information, and DC link voltage information of the motor 14, and determines corresponding states, such as the MTPA / MTPV state, based on this information. The corresponding states can correspond to "0" or "1", thereby ensuring that angle adaptation occurs only within a certain range of operating points.
[0074] The determined state and the obtained temperature information are further processed by components 52, 54, 56, particularly multipliers.
[0075] Generally, the angle adaptation circuit 36 outputs an angle offset, which is applied to the angle value determined for the motor 14, particularly the rotor of the motor 14, in order to shift the angle accordingly and thus obtain a shifted angle (value). In particular, the offset of the corresponding angle that has been determined is shifted. The shifted angle is processed by the control system 12, i.e., the current controller 24. Therefore, the operating point of the motor 14 is actively shifted due to the angle offset adaptation in order to optimize the operation of the motor 14 for low torque and / or low to medium speeds.
Claims
1. An angle adaptation circuit (36) for changing the angle used by a control system (12) of an electric motor (14), wherein the angle adaptation circuit (36) comprises at least one input (38) for receiving torque information and / or speed information of the electric motor (14), wherein the angle adaptation circuit (36) comprises an adaptation module (46) connected to the at least one input (38), wherein the adaptation module (46) is configured to process the information received via the at least one input (38) and output an angle offset of the angle value to be applied to the electric motor (14).
2. The angle adaptation circuit (36) according to claim 1, wherein, the at least one input (38) is further configured to receive DC link voltage information and / or temperature information of the electric motor (14), in particular the temperature of the permanent magnet of the electric motor (14).
3. The angle adaptation circuit (36) according to claim 1 or 2, wherein, the torque information corresponds to an estimated actual torque and / or an input torque setpoint.
4. The angle adaptation circuit (36) according to any one of the preceding claims, wherein, the adaptation module (46) comprises a look-up table (47) that associates the information received via the at least one input (38) with the angle offset.
5. The angle adaptation circuit (36) according to any one of the preceding claims, wherein, the adaptation module (46) comprises a filter module (48) configured to filter a pre-adapted angle offset to obtain the angle offset.
6. The angle adaptation circuit (36) according to any one of the preceding claims, wherein, the angle adaptation circuit (36) is an additional circuit configured to be implemented in a control system for the electric motor (14).
7. A control system (12) for an electric motor (14), the control system (12) comprising a controller (24), an angle evaluation module (34) configured to determine an angle value of the electric motor (14), and an angle adaptation circuit (36) according to any one of the preceding claims.
8. The control system (12) according to claim 7, wherein, the angle evaluation module (34) and the angle adaptation circuit (36) are connected to each other in a node (42), the node (42) being configured to process the angle value determined by the angle evaluation module (34) and the angle offset output by the angle adaptation circuit (36) to determine a shifted angle value.
9. The control system (12) according to claim 8, wherein, the node is connected to the controller (24) such that the controller (24) is configured to receive the shifted angle value to shift the operating point for the electric motor (14).
10. The control system (12) according to any one of claims 7 to 9, wherein, the angle evaluation module (34) is an angle sensor configured to measure the actual angle of the electric motor (14), or wherein the angle evaluation module (34) is an angle observer configured to estimate the actual angle of the electric motor (14).