Angle adaptation circuit and control system

Abstract

The present invention relates to an angle adaptation circuit (36) for shifting an angle used by a control system (12) of an electric machine (14). The angle adaptation circuit (36) has at least one input (38) for receiving torque information and / or speed information of the electric machine (14). The angle adaptation circuit (36) has an adaptation module (46) connected to the at least one input (38). The adaptation module (46) is configured to process the information received via the at least one input (38) and to output an angle offset to be applied to an angle value of the electric machine (14). Further, a control system (12) is described.

Description

[Technical Field]

[0001] The present invention relates to an angle adaptation circuit for shifting an angular offset used by a control system of an electric machine.Furthermore, the present invention relates to a control system for an electric machine. [Background technology]

[0002] In the state of the art, control systems for electric machines are known that include a control system for outputting a voltage set point based on an operating point for the electric machine. The control system typically includes a current set point determination module, a current controller, and a voltage modulation module. These components of the control system are used to control the duty cycle of (power) switches of an inverter coupled to the electric machine.

[0003] These control systems also include an angle estimation module configured to determine the actual angle of the electric machine based on which the control system determines the voltage set point accordingly.

[0004] Typically, the operating point, on which the voltage set point 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 has been found that these known operating point optimizations have shortcomings for low torque and low speed values. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, there is a need for an optimized system for use at low torque and low and medium speed values. [Means for solving the problem]

[0006] The present invention provides an angle adaptation circuit for shifting an angle used by a control system of an electric machine. The angle adaptation circuit has at least one input for receiving torque information and / or speed information of the electric machine. The angle adaptation circuit has 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 to output an angle offset to be applied to an angle value of the electric machine.

[0007] The angle offset is used to deviate the angle used to determine the voltage setpoint of the electric machine from the actual position of the rotor of the electric machine.

[0008] The shifted angle value, which corresponds to the sum of the angle offset output from the angle adaptation circuit and the angle value of the electric machine, is then used to determine the operating point for calculating the voltage set point of the electric machine.

[0009] The angle values ​​preferably correspond to position sensor measurements corrected for mechanical and electrical misalignments.

[0010] The present invention further provides a control system for an electric machine, the control system comprising a controller, for example for outputting a voltage set point based on an operating point for the electric machine, the control system also comprising an angle estimation module configured to determine an angle value of the electric machine, and an angle adaptation circuit as described above.

[0011] Therefore, the angle evaluation module determines the angle value of the electric machine adapted by applying the angle offset, thereby obtaining a shifted angle value. In practice, the shifted angle value can be obtained by adding the angle offset to the angle value. The shifted angle value is transferred to the controller, which processes the shifted angle value to, among other things, determine a voltage set point for the electric machine.

[0012] The angle estimation module determines an angle value based on position information from the rotor of the electric machine. For example, the angle value is determined by measuring the rotor position with a position sensor, and a correction value is added thereto. The correction value allows the angle value to be determined more precisely, corresponding better to the actual position of the rotor and enabling more precise control of the electric machine. 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, by angle offset adaptation, the current setpoint is actively manipulated and processed by a (current) controller of a control system for controlling the electric machine. 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 set point. The controller processes the shifted angle and the current set point and thereby determines the voltage set point, which is particularly used to control the inverter, particularly the power switches. Thus, the angle offset adaptation results in an optimization of the operating point, since the operating point is actively shifted by applying the angle offset to the determined angle value.

[0014] In general, applying an angular offset to the determined angle may result in an adapted / shifted angular offset. In other words, the determined angle is used to identify an angular offset manipulated by the angular offset determined by the angle adaptation circuit.

[0015] An angular offset is determined based on the received information, i.e., torque information and / or electric machine speed information, and added to a previously determined and / or measured electric machine angle value.

[0016] In particular, optimization based on angle offset adaptation is used for low torque and low and medium speed values, for example, within the range of ±500 Nm and / or 0-600 rpm, particularly ±300 Nm and / or 0-400 rpm, or even 100-400 rpm. It should be understood that this range is highly dependent on the design of the electric machine, and therefore, this example range is for illustrative purposes only. These ranges typically relate to rolling vehicles with friction compensation and light acceleration / braking, where the electric machine is still operated by a maximum torque per ampere (MTPA) strategy. In other words, angle adaptation may be limited to low absolute speeds and / or low absolute torque values. Indeed, in this particular range, the angle offset is less sensitive to torque accuracy.

[0017] When the demanded or estimated torque leaves the relevant operating range, the angle offset adaptation is changed to zero, thus preventing sudden jerks due to larger torques upon transitioning back to the MTPA trajectory. Additionally, it prevents jerks upon transitioning back to the MTPV trajectory when the torque suddenly changes close to unity modulation index.

[0018] The resulting torque is reduced by the shifted angle. However, this reduced torque is not significant at the desired operating point 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. Furthermore, the torque inaccuracy or reduced torque is compensated for by the driver.

[0019] In general, angle adaptation, i.e., application of an angle offset, shifts the current operating point from MTPA closer to the maximum torque per loss (MTPL) trajectory, thereby increasing efficiency.

[0020] Compared to an MTPL implementation, the dependencies are reduced, thereby reducing the overall computational power required.

[0021] In fact, the angle adaptation circuit and 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 controller setpoint to maximize overall system efficiency. In particular, the angle adaptation circuit and control system overcomes efficiency imbalances at the low-speed / low-torque operating points frequently used during standard drive cycles.

[0023] At least one input may be associated with an interface, for example a data interface, through which the respective data / information is obtained and processed.

[0024] Generally, inverters are operated based on current and voltage set points that define the control of the inverter.

[0025] One embodiment provides that the at least one input is further configured to receive DC link voltage information and / or electric machine temperature information. For example, the temperature of a permanent magnet of the electric machine is received via the at least one input. The respective temperatures may be measured or estimated, for example by an observer.

[0026] Therefore, the angular offset is determined based on various types of information, namely, torque information, electric machine speed information, DC voltage information, and / or electric machine temperature information. These various types of information are processed by the angle adaptation circuit to determine the applied angular offset. Therefore, the applied angular offset can be more accurately determined because the various types of information are processed and taken into account accordingly. For example, because iron losses (eddy current and hysteresis losses) depend on the temperature of the electric machine, temperature-dependent adaptation is also performed by taking into account the electric machine temperature information.

[0027] In general, angle offset adaptation, i.e. applying an angle offset, results in manipulation of the current set point processed by the controller, leading to a reduction in iron losses.

[0028] A further aspect provides that the torque information corresponds to an estimated actual torque and / or an input torque set point. In other words, the torque information can relate to a desired torque (torque set point) or an actual torque estimated by a torque observer. The angle adaptation circuit may receive both the estimated actual torque and the input torque set point.

[0029] Another aspect provides that the adaptation module includes a lookup table (LUT) that links information received via at least one input with an angular offset. The lookup table thus ensures that the angular offset can be determined in a simple and straightforward manner: the received information is matched with entries in the lookup table to determine the corresponding angular offset to be applied. In other words, the lookup table includes information associated with an operating point, e.g., torque and / or speed, and corresponding angular offsets.

[0030] Additionally, linear interpolation can be performed between operating points so that the angular offset can be determined even if the lookup table does not contain an angular offset entry for a certain constellation.

[0031] The look-up table (and interpolation techniques) ensure that the implementation of the angle adaptation circuit is simple and the computational power can be minimized. In fact, only low processing power and memory capacity are required. Furthermore, memory consumption is reduced overall.

[0032] The adaptation module may include a filter module configured to filter a previously adapted angular offset to obtain an angular offset. The filter module can avoid sudden changes in the shifted angle. To filter the previously adapted angular offset, the filter module can apply a filter function. The filter function can take into account the previous angular offset. This ensures a smooth transition of the angular offset, thereby avoiding current peaks that may occur if the shifted angle changes suddenly. The filter function can also take into account the temperature and / or DC link voltage of the electric machine, in particular any kind of information input via the at least one input.

[0033] Furthermore, the angle adaptation circuit may be an add-on circuit configured to be implemented in a control system for an electric machine. Thus, the angle adaptation circuit has an interface that can be connected to an already existing control system, and the angle adaptation circuit extends the already existing control system. Thus, functionality related to angle offset adaptation is added to the already existing control system. The functionality of the already existing control system for the electric machine can be extended by the add-on circuit.

[0034] One embodiment provides that the angle estimation module and the angle adaptation circuit are connected to each other at a node configured to process the angle value determined by the angle estimation module and the angle offset output by the angle adaptation circuit to thereby determine a shifted angle. Each angle (value) is adapted so that a shifted angle value is obtained and transferred to the controller. In fact, an already existing offset can be changed by determining and applying the angle offset 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 and thereby shift an operating point for the electric machine. The operating point is actively shifted based on the angle offset determined by the angle adaptation circuit. As discussed above, the angle offset is determined based on various types of information.

[0036] The angle estimation module may be an angle sensor configured to measure the actual angle of the electric machine, or an angle observer configured to estimate the actual angle of the electric machine. Thus, the respective angle values ​​adapted by the angle offset output by the angle adaptation circuit may be measured or estimated, depending on the respective type of angle estimation module.

[0037] Generally, the control system, and in particular the current controller and the module for set point determination, remains operating in a known manner, i.e. MPTA, which applies the minimum amount of current to generate the desired torque.

[0038] The angle adaptation circuit monitors the input torque setpoint, the actual torque, and / or the speed of the electric machine. Optionally, the temperature of the permanent magnets of the electric machine and / or the DC link voltage are also monitored by the angle adaptation circuit.

[0039] Based on the observed parameters, a lookup table is accessed, i.e., by the adaptation module, to generate an angular offset that is added to a determined, i.e., measured or estimated, angle value, thus providing angular offset adaptation.

[0040] The adaptation module may generate the angular offset by interpolating the angular offsets stored in a look-up table, which in practice depends on the operating point associated with the observed parameters.

[0041] Further aspects and advantages of the claimed subject matter will be better understood and more readily appreciated by reference to the following description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is a diagram showing an overview of a control system according to the present invention; [Figure 2] 2 shows a schematic diagram of an angle adaptation circuit according to the present invention implemented in the control system of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0043] In FIG. 1, system 10 is shown as including a control system 12 for an electric machine 14 that is powered via an inverter 16 interposed between electric machine 14 and control system 12 .

[0044] Control system 12 is generally configured to control individual power switches of inverter 16 to control the power supply to electric machine 14, e.g., individual windings of electric machine 14. Control is based on various set points, particularly a voltage set point and a current set point.

[0045] The control system 12 includes a current set point determination module 18 having at least one input 20 via which the current set point determination module 18 receives torque information, electric machine 14 speed information, electric machine 14 temperature information, and / or DC link voltage information.

[0046] The current set point determination module 18 can process these various types of information to determine a current set point, which is output via output 22. The processing can be based on a maximum torque per ampere (MTPA) or a maximum torque per flux (MTPF) implementation.

[0047] 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 via an input 26 connected to the output 22 of the current set point determination module 18.

[0048] Current controller 24 is configured to process the current set point received via input 26 to determine a voltage set point, which is output via output 28. The voltage set point may be determined based on the current set point and information regarding the angle of electric machine 14 as described in more detail below.

[0049] The voltage set point output by the current controller 24 via output 28 is transferred to a voltage modulation module 30, which processes the voltage set point and thereby determines the duty cycles for the different power switches of the inverter 16. The operation of the electric machine 14 is controlled accordingly.

[0050] The control system 12 further comprises a current evaluation module 32 configured to measure the value of the current, in particular the alternating current (AC) value, output by the inverter 16 and transferred to the electric machine 14 for operation purposes, in particular to the windings of the electric machine 14.

[0051] Furthermore, the control system 12 includes an angle estimation module 34 configured to determine the angle value of the electric machine 14, and in particular its rotor.

[0052] The angle estimation module 34 may be an angle sensor that measures the actual angle of the electric machine 14. Alternatively, the angle estimation module 34 is an angle observer that estimates the actual angle of the electric machine 14.

[0053] An angle evaluation module 34 determines an angle value based on measured or estimated position information, to which a correction value 35 is added. The angle value therefore corresponds better to the actual position of the rotor. The correction value 35 aligns the angle value from the position sensor with the magnetic d-axis from the motor, correcting for mechanical (and electrical) angle shifts. An example of angle value determination is described in patent EP3857704, the contents of which are incorporated by reference.

[0054] In either case, the angle estimation module 34 provides an angle value that corresponds to the actual angle value of the electric machine 14. Thus, the actual offset can be derived from the determined angle value.

[0055] Additionally, the control system 12 includes an additional circuit, the angle adaptation circuit 36. The angle adaptation circuit 36 ​​can be used to extend an already existing control system, i.e., a control system that includes each of the components described above.

[0056] The angle adaptation circuit 36 ​​has an input 38 via which it 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 shown in Figure 1, the angle adaptation circuit 36 ​​may receive estimated actual torque information and input torque setpoint information.

[0057] In general, the angle adaptation circuit 36 ​​is enabled to process the input information to determine an angle offset that is output via its output 40, and the angle offset is applied to the angle value of the electric machine 14 output by the angle estimation module 34.

[0058] 1, the control system 12 includes a node 42 that processes both the angle value output by the angle estimation module 34 and the angle offset output by the angle adaptation circuit 36. In particular, the angle offset is added to the angle value.

[0059] Thus, the determined angle value is shifted by adding the angle offset, thereby obtaining a shifted angle (value).

[0060] The shifted angle (value) is transferred to the current controller 24 , specifically to the feedback input 44 .

[0061] The current controller 24 also processes the shifted angle (value) to determine the voltage set point.

[0062] Thus, the voltage set point is determined by the current controller 24 based on the shifted angle obtained by the angle estimation module 34 and the angle adaptation circuit 36, which outputs an angle offset to be applied to the angle value of the electric machine 14. Thus, the angle offset adaptation actively shifts the operating point of the electric machine 14, thereby optimizing the operation of the electric machine 14, particularly for low torque and / or low and medium speeds.

[0063] The control system 12 further includes a transformation module 45, for example a Park-Clarke transformation module, also called a d / q transformation module.

[0064] The transformation module 45 processes the shifted angle values ​​and the current information, in particular the phase current values, output by the current estimation module 32 to provide actual current values ​​in a different system, for example a two-axis, i.e., d- and q-based coordinate system.

[0065] These current values ​​are forwarded to the current controller 24 which further processes this information to determine a voltage set point, which is output via output 28 .

[0066] In FIG. 2, the angle adaptation circuit 36 ​​is shown in more detail.

[0067] The angle adaptation circuit 36 ​​includes an adaptation module 46 that processes information received via at least one input 38 and outputs via an output 40 an angle offset that is applied to the angle value of the electric machine 14, thereby obtaining angle adaptation.

[0068] The adaptation module 46 includes a look-up table 47 that processes torque, particularly estimated torque, information and speed information of the electric machine 14 .

[0069] Based on this information, the lookup table 46 outputs a pre-adapted angle offset (“gamma_angle_adaption_unfilt”) that is further processed by a filter to obtain the angle offset (“gamma_angle_adaption”) used for angle adaptation.

[0070] The look-up table 47 therefore links the information received via the input 38 with the angular offsets, in particular the angular offsets that have been previously adapted.

[0071] Furthermore, FIG. 2 shows that the previously adapted angular offset is obtained by processing information on the temperature of the electric machine 14, in particular the rotor temperature and / or the permanent magnet temperature, and information on the DC link voltage.

[0072] The angle adaptation circuit 36 ​​includes a state determination module 50 that receives information on the speed of the electric machine 14, the temperature of the electric machine 14, and the DC link voltage, and determines a respective state, e.g., an MTPA / MTPV state, based on the information. Each state may correspond to a "0" or a "1," thereby ensuring that angle adaptation occurs only within a range of operating points.

[0073] The determined state and obtained temperature information are further processed by components 52, 54, 56, particularly multipliers.

[0074] In general, angle adaptation circuit 36 ​​outputs an angle offset that is applied to the determined angle value for electric machine 14, particularly the rotor of electric machine 14, to shift the angle accordingly, thereby obtaining a shifted angle. In particular, the previously determined offset for the respective angle is shifted. The shifted angle is processed by control system 12, i.e., current controller 24. Thus, angle offset adaptation actively shifts the operating point of electric machine 14 to optimize operation of electric machine 14 for low torque and / or low and medium speeds.

Claims

1. An angle adaptation circuit (36) for shifting an angle used by a control system (12) of an electric machine (14), comprising: the angle adaptation circuit (36) having at least one input (38) for receiving torque information and / or speed information of the electric machine (14); the angle adaptation circuit (36) comprises an adaptation module (46) connected to the at least one input (38); An angle adaptation circuit (36), wherein the adaptation module (46) is configured to process the information received via the at least one input (38) and output an angle offset to be applied to an angle value of the electric machine (14).

2. 2. The angle adaptation circuit (36) of claim 1, wherein the at least one input (38) is further configured to receive information on a DC link voltage and / or a temperature of the electric machine (14), in particular a temperature of a permanent magnet of the electric machine (14).

3. Angle adaptation circuit (36) according to claim 1 or 2, wherein said information of said torque corresponds to an estimated actual torque and / or an input torque set point.

4. 4. The angle adaptation circuit (36) of claim 1, wherein the adaptation module (46) includes a look-up table (47) that links the information received via the at least one input (38) with the angular offset.

5. 5. The angle adaptation circuit of claim 1, wherein the adaptation module includes a filter module configured to filter a previously adapted angular offset, thereby obtaining the angular offset.

6. The angle adaptation circuit (36) of any one of claims 1 to 5, wherein the angle adaptation circuit (36) is an additional circuit configured to be implemented in a control system for the electric machine (14).

7. A control system (12) for an electric machine (14), comprising: a controller (24); an angle evaluation module (34) configured to determine an angle value of the electric machine (14); An angle adaptation circuit (36) according to any one of claims 1 to 6; A control system (12) comprising:

8. 8. The control system of claim 7, wherein the angle estimation module and the angle adaptation circuit are connected to one another at a node configured to process the angle value determined by the angle estimation module and the angle offset output by the angle adaptation circuit to thereby determine a shifted angle value.

9. 9. The control system (12) of claim 8, wherein the node is connected to the controller (24) such that the controller (24) is configured to receive the shifted angle value and thereby shift an operating point for the electric machine (14).

10. 10. The control system (12) of claim 7, wherein the angle evaluation module (34) is an angle sensor configured to measure an actual angle of the electric machine (14), or the angle evaluation module (34) is an angle observer configured to estimate an actual angle of the electric machine (14).

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