Rotor position determination of electric machine

Abstract

There is described a method of determining a rotor position indicator (166, theta), in particular a rotor electrical angle, of an electrical machine (100) having a stator (102) and a rotor (103), in particular of a wind turbine (160), in particular of a permanent magnet synchronous generator, the method comprising: receiving encoder measurement data (168) regarding a rotor position from an incremental mechanical encoder (127), the incremental mechanical encoder is mounted so as to sense a relative rotor position; receiving Hall effect sensor measurement data (169) from at least one, in particular at least three, Hall effect sensors (120), in particular binary sensors, which are mounted at the stator (102) in order to sense magnetic field variations; the rotor position indicator (166) is determined based on the encoder measurement data (168) and the Hall effect sensor measurement data (169).

Description

Technical Field

[0001] This invention relates to a method for determining a rotor position indication of an electric motor and a corresponding apparatus for determining the rotor position indication of an electric motor. Furthermore, this invention relates to a method for controlling an electric motor and a corresponding controller for controlling the electric motor, and also to an electric motor and a wind turbine. Background Technology

[0002] The electric drive system that directly drives the wind turbine is required to enable various modes / functions beyond power generation. Most notably, this is rotor positioning, where the electric drive system must be able to slowly (at fractions of an rpm) rotate the wind turbine generator's rotor and hold it stationary at a target position (0 rpm or as close as possible). This can include a horizontal, single-blade mount with an electric drive system (eHSBM). The eHSBM may require very precise position and torque control up to the maximum permissible torque.

[0003] In wind turbine applications at zero and low speeds, such as horizontal single-blade installations, a technique has been developed in which an incremental encoder is mounted to contact the rotor via a rubber wheel and used for generator control. Since the incremental encoder is unaware of the generator's electrical angle, and the rubber wheel diameter may vary slightly with operating conditions, a sensorless HFI (High Frequency Injection) observer is employed to provide the initial angle and correct the gear ratio (which is the ratio between the rotor diameter and the rubber wheel diameter).

[0004] This technology worked well in field testing; however, some improvements may be needed, such as:

[0005] 1) HFI observers may not work reliably for some other types of generators (e.g., fractional-slot concentrated-winding motors). High saliency is desirable for HFI observer applications, and concentrated-winding motors have much lower values, especially under low loads. In some applications, such as eHSBM (electric horizontal single-blade mount), it is necessary for HFI to function well in order to define the initial angle of the incremental encoder.

[0006] 2) HFI has relatively low dynamics, which can affect the achievable control performance when the encoder is used for position or speed control. In particular, stiffness in position control may not be as high as desired.

[0007] 3) HFI may be affected by harmonics present in the generator.

[0008] 4) HFI may be risky due to instability, especially when the rotor speed becomes relatively high.

[0009] 5) Gear ratio correction requires closed-loop PI control. This can cause problems due to the integral term at very low rotor speeds. Therefore, this operation should only be initiated when the speed is above a threshold.

[0010] Therefore, a method for determining a rotor position indication and a corresponding device for determining the rotor position indication may be required, as well as appropriate control methods and controllers. Furthermore, generators and wind turbines may also be needed, whereby one or more of the aforementioned problems are mitigated or even resolved, reduced, or avoided. In particular, it may be desirable to provide a corresponding accurate rotor position method, which can be specifically applied at low or zero rotational speeds of the motor rotor. Summary of the Invention

[0011] This need can be met by the subject matter of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

[0012] According to embodiments of the present invention, a method is provided for determining a rotor position indication, particularly a rotor angle, of an electric motor having a stator and a rotor, particularly a wind turbine motor, particularly a permanent magnet synchronous generator. The method includes: receiving encoder measurement data regarding the rotor electrical position from an incremental mechanical encoder, the incremental mechanical encoder being mounted to sense the relative rotor position; receiving Hall effect sensor measurement data from at least one, particularly at least three, Hall effect sensors, particularly binary sensors, the Hall effect sensors being mounted at the stator (at a known location) to sense a magnetic field (and / or changes in the magnetic field); and determining the rotor electrical position indication based on the encoder measurement data and the Hall effect sensor measurement data.

[0013] This method can be implemented in software and / or hardware. It can be executed, for example, by a controller of the motor, particularly a control module or control block of a wind turbine controller.

[0014] The rotor position indication may, for example, relate to, or be, correspond to a rotor angle, particularly an electric rotor angle. The electric rotor angle can be related to a mechanical rotor angle by a simple proportionality constant, which includes or depends on the number of pole pairs, as is known in the art. The rotor position indication can be any quantity from which the electric rotor position can be derived. The rotor position indication can thus be encoded for the electric rotor angle.

[0015] Wind turbines can be directly driven, or a gearbox can be connected between the hub of the wind turbine and the rotor of the motor.

[0016] The encoder may include an encoder wheel that contacts an outer or inner (but outer exposed) annular (particularly circular) rotor surface and is also driven by friction between the annular rotor surface and the outer surface of the encoder wheel (particularly comprising rubber or other elastic materials). The outer encoder surface of the encoder wheel may be pressed against the inner circular surface of the rotor by, for example, spring force, particularly against the surface of a reinforcing ring, which is in particular the rotor's brake disc.

[0017] Measurement data from Hall effect sensors and / or encoders can be received as electrical and / or optical and / or wireless signals. Signals can include analog and / or binary signals. Encoder measurement data can specifically include encoder count data relating to the number of steps the encoder has taken since the last measurement sampling. Each Hall effect sensor measurement data can specifically include binary data encoding two distinct Hall effect sensor states: a state where a magnetic field is detected or a state where no magnetic field is detected.

[0018] The embodiments may support the installation of three, six, or even more Hall effect sensors at the stator, and the determination of the rotor position indication by considering some or all of the measurement data from the respective Hall effect sensors. The more Hall effect sensors installed at the stator, the higher the accuracy of the determined rotor position indication is likely to be, especially at very low or even zero rotor speeds. As is known in the art, Hall effect sensors can utilize the Hall effect, which has been observed when the magnetic field changes, to induce current and / or voltage in a conductor circuit. In particular, three Hall effect sensors can be installed at known locations on the stator such that the relative electrical angle between spatially adjacent Hall effect sensors is, for example, 60°, 30°, or 120°. The Hall effect sensors can be previously calibrated such that, for example, the Hall effect sensors accurately indicate the true rotor position at the point in time when a state change occurs (i.e.,, for example, a high state transitions to a low state or vice versa in the sensor signal). The Hall effect sensors can thus detect when the magnetic field is, for example, above or below a threshold, thereby indicating a high state and a low state, but can also detect changes in the magnetic field.

[0019] This method primarily uses encoder measurement data to determine the rotor position. Hall effect sensor measurement data can be preferably or particularly used to determine the initial angle or offset angle and / or to determine the transmission ratio associated with the mechanical encoder. Thus, accurate rotor position data can be determined. The determined rotor position indication can be used, particularly, for motor control, as will be described in further detail below.

[0020] According to an embodiment of the present invention, determining a rotor position indication based on encoder measurement data and Hall effect sensor measurement data includes: using Hall effect sensor measurement data to: define an initial angle or offset angle of the encoder; and / or determine and / or correct the transmission ratio of the encoder; wherein the rotor position indication is calculated based on the encoder measurement data, the initial angle, and the transmission ratio, wherein the encoder measurement data is in particular the encoder count increment between two samples.

[0021] An incremental encoder can be configured to detect only the increment of the rotor position angle, but it does not need to be configured to determine the absolute rotor position or absolute rotor angle by itself. Therefore, for initialization, data from Hall effect sensors can be used, which can be applied during standstill, zero rotation speed, or even more precisely during rotor motion or rotation. The encoder used can initially use a previous gear ratio or a gear ratio determined from design or dimensional information regarding the encoder wheel diameter and / or the rotor inner surface diameter. However, during a particular application or while performing, for example, a specific control method, this previous or predetermined gear ratio may not accurately reflect the true gear ratio. Therefore, for example, for precise positioning, the gear ratio may need to be more accurate than a previously determined gear ratio. The gear ratio can be determined and / or corrected, in particular, by acquiring and processing two state changes from at least one Hall effect sensor. The corresponding rotor position indication can then be calculated, for example, according to a mathematical equation that includes, for example, the gear ratio and the encoder count increment between two samples. Thus, the rotor position indication can be calculated in a simple, reliable, and particularly accurate manner.

[0022] According to an embodiment of the invention, determining the transmission ratio includes: determining a first position difference between a first encoder-based position and a first Hall effect sensor-based position relating to a first time point when a state change exists in the Hall effect sensor, thereby particularly using a prior (or default, previously used, determined, or corrected) transmission ratio (e.g., prior processing of Hall effect measurement data encoder data is previously determined); determining a second position difference between a second encoder-based position and a second Hall effect sensor-based position relating to a second time point when a state change exists in the Hall effect sensor, thereby particularly using the prior transmission ratio; and correcting the prior transmission ratio if the first position difference differs from the second position difference.

[0023] The method for determining / correcting the transmission ratio can be performed recursively.

[0024] The first position difference can be compared with the second position difference. If the two differences are different or have different values, this may indicate that the previously used gear ratio was incorrect and did not reflect the true gear ratio. If the first position difference is substantially equal to the second position difference, the previous gear ratio can be considered the true gear ratio, and correction may not be necessary.

[0025] According to an embodiment of the present invention, determining the transmission ratio further includes: calculating the position difference change between the second position difference and the first position difference; determining a transmission ratio correction term based on the position difference change, wherein the transmission ratio correction term is specifically determined as the quotient between the position difference change and the expected angular step size of the Hall effect sensor position during the Hall effect sensor state change; calculating a corrected transmission ratio based on a previous transmission ratio and the transmission ratio correction term, wherein the previous transmission ratio is specifically used to determine the first position difference and the second position difference, wherein the corrected transmission ratio is specifically calculated as a (parameterized) default transmission ratio multiplied by a product of the sum of the transmission ratio correction terms.

[0026] If the position difference change is not zero, it may indicate that the previously used gear ratio does not reflect the true gear ratio and may require correction. The gear ratio correction term can then correct the previous gear ratio to obtain the true or more accurate gear ratio. Thus, using the corrected or true gear ratio, the rotor position indication can be calculated with greater accuracy based on encoder measurement data.

[0027] According to an embodiment of the invention, at a first and / or second time point, a state change occurs in the Hall effect sensor, wherein, in particular, the state change is associated with or occurs at a known rotor position.

[0028] When a state change occurs in the Hall effect sensor, the Hall effect sensor can thus indicate the true position of the electric rotor with very high accuracy. Therefore, the first and / or second time points of the state change can be advantageously used to read the true rotor position from the Hall effect sensor. These position values ​​can be used to correct and / or determine the gear ratio of the mechanical encoder, and, if necessary, to initialize the encoder angle.

[0029] According to an embodiment of the invention, an incremental encoder is mounted on the stator and has an encoder wheel outer surface that contacts and is driven by the circular inner surface of the rotor. The encoder wheel outer surface specifically contacts and is driven by the rotor's reinforcing ring, which is specifically a brake disc.

[0030] The outer surface of the encoder wheel can be, for example, provided with a material that is at least partially elastic or resilient, such as rubber, which can also provide appropriate friction between or relative to the circular inner surfaces of the rotor. Therefore, when the rotor rotates, there can be substantially no slippage between the movement of the rotor and the encoder wheel. The outer surface of the encoder wheel can be pressed against the inner surface of the rotor by, for example, spring force.

[0031] The reinforcing ring can be mounted, for example, at the axial end of the rotor housing. The rotor housing can be configured substantially as the wall of a cylinder. The reinforcing ring can function as a brake disc, thereby providing the ability to decelerate the rotor when necessary. In other embodiments, the reinforcing ring does not necessarily function as a brake disc. In yet another embodiment, the outer surface of the encoder wheel may not contact the reinforcing ring, but may instead contact directly with the rotor housing, for example, which is configured substantially as a cylinder wall.

[0032] However, according to embodiments of the invention, the reinforcing ring provides the rotor with rigidity and stability, and also provides a substantially accurate circular shape. This improves the method.

[0033] According to an embodiment of the invention, the transmission ratio indicates the ratio between the circumference of the outer surface of the encoder wheel and the circumference of the annular surface of the rotor, particularly the circumference of the rotor's reinforcing ring, the outer surface of the encoder wheel being in contact with the annular surface of the rotor.

[0034] The transmission ratio can also indicate the ratio between the corresponding radius of the encoder wheel's outer surface and the radius of the rotor's annular surface. Based on the continuous execution of the method indicated or described above regarding the determination / correction of the transmission ratio, this method can dynamically determine and / or correct the transmission ratio. Therefore, any changes that may occur at the encoder wheel's outer surface (e.g., due to wear) can be addressed or corrected.

[0035] According to an embodiment of the present invention, a plurality of axially spaced radially extending cooling channels are disposed between axially spaced laminations of the stator.

[0036] The stator can be configured or composed of multiple axially spaced laminations, each lamination having a yoke and multiple teeth. The laminations may include layers of ferromagnetic, highly permeable material. The multiple layers can be electrically isolated from each other. The stator can be configured as a complete circumference, or it can be composed of multiple stator segments, each segment spanning, for example, a specific angular range, such as 30°, 45°, 60°, or different degrees. Multiple stator segments assembled together can form a complete circumference.

[0037] Between the axially spaced laminations, radially extending cooling channels can be formed. These channels can be used to guide cooling fluid or a medium (e.g., air) through them during operation and to cool the stator. Advantageously, one or more Hall effect sensors can be mounted in some of the cooling channels using specific mounting devices (e.g., retainers partially inserted into the cooling channels). Furthermore, cooling can be achieved thereby.

[0038] According to an embodiment of the invention, the Hall effect sensor data includes binary data that is switched at each state change of the Hall effect sensor, and / or three or more Hall effect sensors are at least partially mounted in or at the stator cooling duct to have a phase shift of 30, 60 or 120 electrical angles, and / or wherein at least one Hall effect sensor is mounted using a retainer or bracket that is at least partially inserted into a radial cooling duct within the stator.

[0039] For example, a Hall effect sensor can be substantially positioned at the end portion of a retainer or bracket. The retainer or bracket can be inserted radially outward (e.g., from the inside of the stator) through and into one or a portion of a radial cooling duct. Thus, the Hall effect sensor positioned at the end portion of the retainer or bracket can then be arranged close to the air gap between the stator and rotor to sense the magnetic field of a permanent magnet, for example, mounted on the inside of an outer rotor. The installed Hall effect sensors may only slightly interfere with cooling performance, as they may only block a very small portion of the cooling duct.

[0040] According to an embodiment of the invention, the method is performed under the following conditions: during position control; or during speed control; or during torque control; and / or at low speeds, particularly between 0 and 1 rpm, especially involving blade installation and / or removal.

[0041] During position control, the target position can be compared with the actual position, and the corresponding position error can be supplied to the control module, which can output a setting signal to reduce the position error. Torque control can be applied or executed in a similar manner. Thus, in particular, this method can advantageously support methods for mounting and / or dismounting rotor blades, or methods for preparing for mounting and / or dismounting rotor blades.

[0042] According to embodiments of the present invention, a method for controlling an electric motor having a stator and a rotor is provided, the electric motor being particularly a wind turbine motor, particularly a permanent magnet synchronous generator, the method comprising: performing a method for determining a rotor position indication according to any of the foregoing embodiments; and controlling the electric motor based on the determined rotor position indication, particularly performing rotor positioning with applied position, speed and / or torque control.

[0043] The improved rotational position also allows for improved motor control.

[0044] It should be understood that, according to embodiments of the present invention, features of a method for determining a rotor position indication quantity disclosed, described, applied, or provided individually or in any combination may also be applied or provided individually or in any combination as means for determining a rotor position indication quantity, and vice versa.

[0045] According to embodiments of the present invention, an apparatus is provided for determining a rotor position indication, particularly a rotor angle, of an electric motor having a stator and a rotor, particularly a wind turbine motor, particularly a permanent magnet synchronous generator. The apparatus comprises: an incremental mechanical encoder mounted to sense relative rotor position; at least one, particularly at least three, Hall effect sensors, particularly binary sensors, mounted at the stator to sense magnetic fields (and / or changes in magnetic fields); an input port adapted to: receive encoder measurement data regarding rotor position from the incremental mechanical encoder; receive Hall effect sensor measurement data from the Hall effect sensors; and a processor adapted to determine the rotor position indication based on the encoder measurement data and the Hall effect sensor measurement data.

[0046] The device can be configured to perform the method according to one of the above embodiments.

[0047] According to an embodiment of the present invention, a controller is provided for controlling an electric motor having a stator and a rotor, particularly a wind turbine motor or a permanent magnet synchronous generator, the controller comprising: means for determining a rotor position indication according to a previous embodiment; and a control module adapted to control the motor based on the determined rotor position indication, particularly performing rotor positioning with applied position and / or speed and / or torque control.

[0048] According to an embodiment of the present invention, an electric motor is provided, particularly a wind turbine motor, particularly a permanent magnet synchronous generator, the motor comprising: a stator; a rotor; and a controller according to the preceding embodiment.

[0049] According to an embodiment of the present invention, a wind turbine is provided, comprising: a hub having a plurality of rotor blades mounted thereon; and a motor according to a previous embodiment, wherein the rotors are coupled to the hub.

[0050] The above and other aspects of the invention will become apparent from the examples of the embodiments described below, and will be explained with reference to these examples. The invention will now be described in more detail with reference to examples of embodiments, but the invention is not limited to these embodiments. Attached Figure Description

[0051] Embodiments of the invention will now be described with reference to the accompanying drawings. The invention is not limited to the embodiments shown or described.

[0052] Figure 1 A portion of a motor according to an embodiment of the present invention is schematically shown in a cross-sectional view along the axial direction;

[0053] Figure 2 An outer rotor and encoder wheel are shown according to an exemplary embodiment;

[0054] Figure 3 An encoder component according to an exemplary embodiment is shown;

[0055] Figure 4 A wind turbine according to an embodiment of the present invention is shown, which includes a motor and a control device according to an embodiment of the present invention;

[0056] Figure 5 A correction method for correcting the transmission ratio of a mechanical encoder according to an embodiment of the present invention is shown; and

[0057] Figure 6 A method for controlling a motor according to an embodiment of the present invention is illustrated schematically. Detailed Implementation

[0058] The illustrations in the accompanying drawings are schematic. Note that in different drawings, elements with similar or identical structures and / or functions are given the same reference numerals or reference numerals that differ only in the first digit. Description of an element not described in one embodiment may be obtained from the description of that element in another embodiment.

[0059] Embodiments of the present invention relate to a control method for position and / or torque control of a wind turbine employing a permanent magnet synchronous generator at low and zero speeds, particularly for applications involving single-blade installations on wind turbines, comprising an incremental encoder mounted on a brake disc and a set of digital Hall effect sensors. This solution provides significantly higher resolution in motor electrical angle measurements compared to conventional shaft-mounted encoders, thus meeting the aforementioned requirements.

[0060] Embodiments of the present invention provide an alternative and improved method for determining rotor position using a set of low-cost digital Hall effect sensors, which may be mounted near the generator air gap (or magnet).

[0061] Figure 1 A motor 100 according to an embodiment of the present invention is schematically shown in a partial view, in a cross-sectional view perpendicular to the axial direction 101. Figure 1In the diagram, radial direction 107 and circumferential direction 108 are indicated, both perpendicular to axial direction 101. Motor 100 includes a stator 102 and an outer rotor 103, the outer rotor being rotatably supported relative to the stator 102. Rotor 103 includes a rotor housing 112 on which radially inwardly projecting permanent magnets 113 are mounted, the permanent magnets being inserted into retaining rails 114 extending in the axial direction 101. An air gap 115 exists between the stator 102 and rotor 103, typically having an extension range between 5 mm and 8 mm.

[0062] The stator 102 of the motor 100 includes a stator yoke 104 having a plurality of radially outwardly projecting teeth 105 and slots 106 between the teeth. The teeth 105 consist of axial tooth segments ( Figure 1 The axial tooth segments are spaced apart in the axial direction 101, forming multiple cooling channels or openings between adjacent tooth segments (which are obstructed in the middle). Figure 1 One of the cooling conduits 109a is shown. The motor or, more specifically, the stator 102 also includes stator windings 111 partially arranged in slots 106.

[0063] Figure 1 The motor 100 shown also includes at least one Hall effect sensor system 120 (particularly three Hall effect sensor systems 120 spaced apart in the circumferential direction 108) according to an embodiment of the invention, the Hall effect sensor system being inserted into one of the cooling openings, for example, into the cooling opening 109a.

[0064] Each Hall effect sensor system 120 of the motor 100 includes a body 121 comprising an insertion portion 122 extending in a longitudinal direction (collinear with the radial direction 107), wherein the insertion portion 122 is configured to be reversibly mounted within a cooling opening 109a of the stator 102. A Hall effect sensor 123 is substantially disposed at the longitudinal end 124 of the insertion portion. The insertion portion 122 has an end surface 125 at the longitudinal end 124. When the insertion portion 122 is mounted within the cooling conduit 109a, the longitudinal direction of the insertion portion 122 or the body 121 corresponds to the radial direction 107.

[0065] In the above Figure 1 The diagram illustrates the installation of one or more Hall effect sensors in a generator. The Hall effect sensors can be mounted on a non-magnetic bracket that can be inserted from the inside of the stator towards the outside (air gap or near the magnet on the rotor). This allows for sensor insulation or replacement without direct access to the motor windings or magnets. Three or more Hall effect sensors can be installed in designed or predetermined locations such that they have a phase shift of 30, 60, or 120 electrical degrees.

[0066] Figure 1 The motor 100 shown also includes a controller 150 according to an embodiment of the invention, which includes means for determining the rotor position according to an embodiment of the invention, which will be described in more detail below.

[0067] Figure 2 The rotor 103 is shown as viewed in the axial direction. The rotor 103 has an inner surface 126, which, in the illustrated embodiment, is part of the rotor brake disc. Figure 2 The motor 100, shown in the middle portion, also includes an incremental mechanical encoder 127, which is mounted on the stator (not shown) and includes an encoder wheel 128. The outer surface of the encoder wheel 128 of the encoder 127 is pressed against and in contact with the inner surface 126 of the rotor 103 in order to sense the rotation of the rotor.

[0068] Figure 3 An encoder 127 according to an exemplary embodiment is shown. The encoder 127 includes an encoder wheel 128 having a circumferential surface 129 for contacting an opposing surface, such as a... Figure 2 The inner surface 126 of the rotor 103 is shown. The circumferential surface 129 preferably comprises rubber or a similar elastic material. The encoder wheel 128 is rotatably mounted on the encoder arm 131, which is pivotally connected to the encoder mounting bracket 132 via a joint 133. The encoder 127 also includes a spring device 134, which is configured to bias the circumferential surface 129 of the encoder wheel 128 against an opposing surface (e.g., the inner surface 126 of the brake disc of the rotor 103).

[0069] The encoder mounting bracket 132 is configured to be (permanently or temporarily) mounted to a non-rotating component, such as the stator of a motor, near an opposing surface. The encoder 127 includes suitable sensors, such as magnetic, mechanical, and / or optical sensors, for detecting rotation of the encoder wheel 128 and accordingly causing a counter to increment / decrement, as known in the art.

[0070] The encoder housing can be mounted on the stator of a wind turbine generator with an external rotor. The outer surface of the encoder shaft or encoder wheel can contact the circular surface of the generator rotor (e.g., a brake disc), or be a wheel mounted on the encoder shaft. The encoder can continuously detect the rotation of the rotor, thereby detecting the relative rotor position. The encoder output can be connected to a turbine / converter controller.

[0071] A specific transmission ratio can exist between the encoder wheel and the circular surface of the generator rotor. This transmission ratio can be determined / corrected according to embodiments of the invention. The encoder can be temporarily installed during wind turbine installation and can be temporarily mechanically and signal-connected to the turbine control system.

[0072] The installation of a rotary incremental encoder mounted on a brake disc may include:

[0073] 1. Mount the encoder housing onto the stator of the WTG generator with the rotor.

[0074] 2. The encoder shaft contacts the circular surface on the generator rotor via a wheel mounted on the encoder shaft.

[0075] 3. The encoder continuously detects the rotation of the WTG rotor. The encoder output is connected to the turbine / converter controller.

[0076] 4. The solution is characterized by the transmission ratio between the encoder wheel and the circular surface on the generator rotor. The transmission is provided by utilizing the mounting method of the rubber wheel.

[0077] 5. The encoder can be temporarily installed during WTG installation and temporarily connected to the turbine control system mechanically and signal-wise.

[0078] Figure 4 A wind turbine 160 according to an embodiment of the present invention is schematically shown. The wind turbine 160 includes a hub 161 on which a plurality of rotor blades 162 are mounted. The wind turbine 160 also includes a motor 100 according to an embodiment of the present invention, for example in… Figure 1 , 2 Some components of the motor are shown in Figure 3. Hub 161 is connected to rotor 103 of motor 100. The motor includes rotor 103 and as shown in the reference above. Figure 1 Stator 102 is described in part.

[0079] The motor 100 also includes a controller 150 according to an embodiment of the invention. The controller 150 for controlling the motor 100 includes means 130 for determining a rotor position indication amount according to an embodiment of the invention. The controller 150 also includes a control module 165 adapted to control the motor 100 based on the determined rotor position indication amount, which is indicated by a signal 166 representing the value of the rotor position indication amount.

[0080] The device 130 for determining the rotor position indication 166 includes at least one incremental mechanical encoder 127 (e.g., such as...). Figure 3 As shown in the diagram, it is mounted at the stator 102. The device 130 also includes at least one Hall effect sensor 120, which is mounted at the stator 102 to sense magnetic fields (and / or field changes) (e.g., as shown in the diagram). Figure 2 (as shown in the image).

[0081] The device 130 also includes an input port 167 adapted to receive encoder measurement data 168 regarding rotor position from an incremental mechanical encoder 127, and is also adapted to receive Hall effect sensor measurement data 169 from a Hall effect sensor 120. The device also includes a processor (e.g., including processing units 170 and 171) adapted to determine a rotor position indication quantity 166 based on the encoder measurement data 168 and the Hall effect sensor measurement data 169. The processing unit 171 uses the gear ratio to determine a preliminary encoder-based rotor position 172. From the Hall effect sensor measurement data 169, a Hall effect sensor-based rotor position value 173 is determined.

[0082] The position processing module 170 receives both an initial rotor position 172 based on the encoder and a rotor position 173 based on the Hall effect sensor, and then determines a final rotor position indication 166 based on the at least two input quantities.

[0083] Controller 150 uses a Hall effect sensor to define the initial angle of the encoder and also helps to correct the gear ratio. The final encoder angle (e.g., determined by...) Figure 4 Signal 166 shown can be responsible for converter and generator control. Therefore, controller 150 includes control module 165, which includes motion control module 174. Motion control module 174 generates a reference current 175 based on position data 166 (and reference data 157, such as position or torque reference data), which is provided to vector control module 176. Vector control module 176 then calculates a reference voltage 177, which is provided to (optionally) converter 178 connected to motor 100.

[0084] The device 130 is configured to perform a method for determining a rotor position indication 166 according to an embodiment of the invention. Thereby, the device 130 receives encoder measurement data 168 regarding the rotor position from an incremental mechanical encoder 127, and also receives Hall effect sensor measurement data 168 from at least one or, in particular, at least three Hall effect sensors. Furthermore, based on at least these two input quantities or signals, the device 130 determines the rotor position indication 166.

[0085] The encoder's rotational position 172 can be processed or determined, for example, according to the following encoder angle processing:

[0086] Having in Figure 4 A simple motion control system based on encoder measurement is implemented in a wind turbine 160. A Hall effect sensor is used to define the initial angle of the encoder and also helps with its gear ratio correction. The final encoder angle is responsible for converter and generator control.

[0087] Encoder angle processing can include:

[0088] As the rotor rotates, the encoder count will change. Between two successive control samples, the encoder count change can be captured and used to calculate the change in the generator electrical angle.

[0089] ΔEncTheta0=GenPp*360 / (EncMaxCount*GR)*ΔEncInput

[0090] in,

[0091] GR - Transmission ratio, which represents the transformation from the rotation of the brake disc (or rotor) to the rotation of the encoder when the encoder contacts the circular surface of the brake disc;

[0092] GenPp - Generator pole pair;

[0093] EncMaxCount represents the maximum count of encoder inputs in 360 degrees; typically, the value is 40,000 if the encoder has 10,000 lines.

[0094] ΔEncInput - The increment of the encoder signal count between two samples.

[0095] Then, the generator electrical angle is calculated as follows:

[0096] EncTheta0=EncTheta0Last+ΔEncTheta0

[0097] in,

[0098] EncTheta0Last - The last query result (scan) from the generator electrical angle measured by the encoder, which can be initialized at the start of the calculation by, for example, a Hall effect sensor.

[0099] However, due to the uncertainty of the initial angle or position value and due to the uncertainty about the transmission ratio (GR), the initial encoder-based rotor position 172 may be incorrect and may need to be corrected.

[0100] Encoder angle initialization can be performed according to the following steps:

[0101] The encoder is incremental, and before the encoder can be used for control, the absolute angle of the encoder relative to the rotor's electrical position needs to be defined from a separate source. In this embodiment, the separate source will be a Hall effect sensor.

[0102] If three Hall effect sensors are used, the angular resolution will be 60 degrees (or ±30 degrees) (electrical angle). This means that when initializing with Hall effect sensors, the encoder may have an error within (-30, 30) degrees, or the transmitted torque may be between 87% and 100% for a given generator current. For some applications, such as single-blade mounts, where there may not be much margin in the converter / generator current capacity, this insufficient torque can be disadvantageous. Three possible solutions can be supplemented.

[0103] 1) Six sensors can be installed instead of three. In this case, the angle error will be within the range of (-15, 15) degrees, and the torque can be increased to 97%–100%.

[0104] 2) When the generator current has reached its maximum value, a slow scan between (-30, 30 degrees) can be performed as an offset of the generator control angle, starting from the encoder initialization angle, until the rotor begins to move.

[0105] 3) The rotor electrical position measured by the encoder during the previous run before stopping can be stored and used as the encoder's initial angle during the next rotor start-up. For safe operation, this stored initial angle can be checked using a Hall effect sensor angle.

[0106] The above applies to the case where the rotor is stationary, especially when the rotor is in the locked position. If the rotor is allowed to move freely, or when the rotor has already moved, the angle measured by the Hall effect sensor at the point of state change will indicate the true electrical position of the generator, and the encoder angle can be accurately initialized.

[0107] Determining the gear ratio may include considering the following: Figure 4 The initial rotor position value is derived from the encoder (value 172) or Hall effect sensor (value 173) indicated in the code.

[0108] The following will refer to Figure 5 This embodiment is described. Figure 5A curve 180 representing the signal amplitude of the encoder-based rotor position 172 is shown in a coordinate system with time on the horizontal axis and rotor angle on the vertical axis. A step curve 181 representing the rotor position 173 based on the Hall effect sensor is also shown. At a first time point t1 when a state change occurs in the Hall effect sensor, a first position difference Δθ1 is determined between the first encoder-based position e1 and the first Hall effect sensor-based position h1, both of which are related to the first time point t1. Furthermore, at a second time point t2 when another state change occurs in the Hall effect sensor, a second position difference Δθ2 is calculated between the second encoder-based position e2 and the second Hall effect sensor-based position h2, both of which are related to the second time point t2.

[0109] If the first position difference Δθ1 differs from the second position difference Δθ2, the previous transmission ratio is corrected. Specifically, the position difference change Δθ_chg between the second position difference Δθ2 and the first position difference Δθ1 is calculated. Then, a transmission ratio correction term is determined based on this position difference change, and the corrected transmission ratio is determined based on the transmission ratio correction term and the default transmission ratio. It should be noted that the state changes of the Hall effect sensor occur at the first time point t1 and / or the second time point t2. Therefore, at those time points, the rotor position is precisely defined based on the Hall effect sensor measurement data.

[0110] The method for encoder transmission ratio correction is described in more detail below:

[0111] During the transition from rotor rotation to encoder rotation, errors may occur in encoder speed calculations due to tolerances in wheel diameter or compression of the rubber tires. These errors will then lead to errors in the integral angle measurement, and consequently, errors in the motor's electrical angle. Therefore, dynamic correction of the transmission ratio is necessary.

[0112] However, by using Hall effect sensors, gear ratio correction can be much simpler and faster. This is because the electrical angle of the motor is well defined as the state of these Hall effect sensors changes, even when harmonics in the magnetic flux distribution are taken into account.

[0113] At zero speed, no GR correction is required. This is actually handled automatically in this scheme because no state change occurs in the Hall effect sensor.

[0114] When in motion, the Hall effect sensor changes state. Between two successive state changes, the GR ratio can be calculated based on the angle difference between the encoder and the Hall effect sensor. For example,

[0115]

[0116] in,

[0117] Δθ chg =Δθ2-Δθ1

[0118] Δθ is the angular difference between the encoder and the HE (Hall effect sensor), measured in degrees. chg It is the change in the angle difference between the states of two successive sensors.

[0119] θ step This is the expected step size of the Hall effect sensor angle as the state changes. With three Hall effect sensors, it will be 60° (electrical angle) in forward rotation and -60° in reverse rotation (see...). Figure 5 In other cases, such as those with one, two, or six Hall effect sensors, the expected step size will be different.

[0120] GR correction can then be used to update the gear ratio (GR).

[0121] GR = GR param ·(1+GR corr )

[0122] Among them, GR param This is the parameter for the default gear ratio.

[0123] This method is more direct and can be highly dynamic because the correction will be completed within two changes in the sensor state detected (or the next state change after the first state change). In the implementation, a rate limiter can be added to prevent abrupt changes in the transmission ratio; furthermore, possible small misalignments in the sensor mounting position can be easily compensated in software, for example, by storing the sensor position data. In the case of small sensor position misalignments, θ should be calibrated accordingly. step .

[0124] Figure 6 A control method scheme according to an embodiment of the present invention is schematically illustrated. Method scheme 200 begins at block 201. In block 202, the encoder initial angle is set based on the motor electrical position of a Hall effect sensor. The encoder angle 166 determined therefrom is supplied to a controller 150, which is configured to control a motor (not shown). In decision block 204, it is determined whether a state change exists in the measurement data based on the Hall effect sensor. If a Hall effect state change exists, and if this state change is the first state change since the start of operation, the encoder initial angle is set based on the Hall effect sensor angle, and the aforementioned first and second position differences Δθ1 and Δθ2 are set to zero.

[0125] If, based on the evaluation in box 204, no first Hall state change occurs, then in the next decision box 206 (after box 205), it is checked again whether the next Hall effect sensor state change is about to occur. If so, the first position difference is set to the second position difference. Furthermore, the second position difference is set to a reduction of the encoder angle minus the Hall angle. The expected angle step size is also determined based on the detected rotation direction.

[0126] In block 208, a transmission ratio correction calculation is performed, and the corrected transmission ratio is used to calculate the encoder angle 166, which is supplied to the controller 150 for control.

[0127] Continuously, such as Figure 6 As indicated by the arrow, the aforementioned transmission ratio correction process cycles back to the second determination element 206, and the corrected transmission ratio is used to update the encoder angle.

[0128] When the rotor is stationary and the generator current is at its limit (determination element 290), the angle adjustment is controlled (optionally).

[0129] Embodiments of the present invention may provide one or more of the advantages (technical features) mentioned below:

[0130] - A solution for position and / or torque control of wind turbines employing permanent magnet synchronous generators at low and zero speeds. This solution is simple and very low in cost.

[0131] - A method for determining the absolute electrical position of a motor.

[0132] - A method of using a second position measurement source (i.e., a digital Hall effect sensor) to correct the angle measured from the encoder.

[0133] - A transmission ratio (GR) calculation technology with high dynamics, accuracy, and stability.

[0134] The technology is less limited by rotor speed.

[0135] - A control method that is easy to integrate with existing control systems.

[0136] - Solutions for permanent magnet multiphase motors.

[0137] - A solution for DD or geared wind turbines.

[0138] - A solution to make concentrated winding (CW) generators compatible with eHSBM.

[0139] It should be noted that the term "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude multiple. Furthermore, elements described in association with different embodiments may be combined. It should also be noted that reference numerals in the claims should not be construed as limiting the scope of the claims.

Claims

1. A method of determining a rotor position indication (166, Θ), in particular a rotor electrical angle, of an electrical machine (100) having a stator (102) and a rotor (103), in particular an electrical machine of a wind turbine (160), in particular a permanent magnet synchronous generator, the method comprising: receiving encoder measurement data (168) on a rotor position from an incremental mechanical encoder (127) mounted so as to sense a relative rotor position; receiving Hall effect sensor measurement data (169) from at least one, in particular at least three, Hall effect sensors (120), in particular binary sensors, mounted at the stator (102) so as to sense a magnetic field; determining the rotor position indication (166) based on the encoder measurement data (168) and the Hall effect sensor measurement data (169).

2. The method according to the preceding claim, wherein, Determining the rotor position indication (166) based on the encoder measurement data and Hall effect sensor measurement data comprises: using the Hall effect sensor measurement data (168) to: define an initial angle (EncTheta0Last) of the encoder; and / or determine and / or correct a gear ratio (GR) of the encoder; wherein the rotor position indication is calculated based on the encoder measurement data, in particular a count increment (DeltaEncTheta0) of the encoder between two samples, the initial angle and the gear ratio.

3. The method according to the preceding claim, wherein, Determining the gear ratio (GR) comprises: determining a first position difference (DeltaTheta1) between a first encoder-based position (el) and a first Hall effect sensor-based position (hl) related to a first point in time (tl) when a state change in the Hall effect sensor occurs, thereby in particular using a previous gear ratio; determining a second position difference (DeltaTheta2) between a second encoder-based position (e2) and a second Hall effect sensor-based position (h2) related to a second point in time (t2) when a further state change in the Hall effect sensor occurs, thereby in particular using the previous gear ratio; correcting the previous gear ratio if the first position difference is different from the second position difference.

4. The method according to the preceding claim, wherein, Determining the gear ratio (GR) further comprises: calculating a position difference change (DeltaTheta_chg) between the second position difference (DeltaTheta2) and the first position difference (DeltaTheta1); determining a gear ratio correction term (GR_corr) based on the position difference change (DeltaTheta_chg), wherein the gear ratio correction term is in particular determined as a quotient between the position difference change and an expected step length of the Hall effect sensor position at a Hall effect sensor state change; A corrected gear ratio (GR) is calculated based on a default gear ratio (GR_param) and a gear ratio correction term (GR_corr), the default gear ratio in particular being used to determine a first position difference and a second position difference, wherein the corrected gear ratio is in particular calculated as the default gear ratio multiplied by a product of one and the sum of the gear ratio correction term.

5. The method according to any of the preceding claims 3 or 4, wherein, At the first time point (t1) and / or the second time point (t2), a state change of the Hall effect sensor (120) occurs, wherein in particular the state change is associated with or occurs at a known rotor position.

6. The method according to any of the preceding claims, wherein The incremental encoder (127) is mounted on the stator (102) and has an encoder wheel outer surface (129) which is in contact with and driven by a circular inner surface (126) of the rotor (103), The encoder wheel outer surface is in particular in contact with and driven by a reinforcement ring of the rotor, in particular a brake disc.

7. The method according to any one of the preceding claims, wherein, The gear ratio (GR) indicates a ratio between a circumference of the encoder wheel outer surface (129) and a circumference of the annular surface (126) of the rotor (103), in particular a reinforcement ring of the rotor, which the encoder wheel outer surface (129) is in contact with.

8. The method according to any of the preceding claims, wherein A plurality of axially spaced radially extending cooling ducts (109a) are provided between axially spaced laminations (104) of the stator (102); and / or wherein the Hall effect sensor data (169) comprises binary data which is switched upon each state change of the Hall effect sensor; and / or wherein three or more Hall effect sensors (120) are mounted at least partially within or at stator cooling ducts to have a phase shift of 30, 60 or 120 electrical degrees; and / or wherein the at least one, in particular three or more, Hall effect sensors (120) are mounted using a holder or bracket which is at least partially inserted into a radial cooling duct of the stator.

9. The method according to any of the preceding claims, the method being performed during: position control; or speed control; or torque control; and / or.

10. The method according to any of the preceding claims, the method being performed at low speed, in particular between 0 rpm and 1 rpm, in particular involving blade mounting and / or dismounting, in particular starting from a locked rotor at standstill, the method further comprising: using a stored rotor position to define an initial angle of the encoder; in particular checking and / or correcting the initial angle so defined by the Hall effect sensor measurement data, the stored rotor position being related to a rotor state at which rotor motion was previously stopped.

11. A method of controlling an electrical machine (100) having a stator (102) and a rotor (103), in particular a wind turbine electrical machine, in particular a permanent magnet synchronous generator, the method comprising: performing a method of determining a rotor position indication quantity (166) according to any of the preceding claims; controlling the electrical machine (100) based on the determined rotor position indication quantity (166), in particular performing rotor positioning applying position and / or speed and / or torque control.

12. An apparatus (130) for determining a rotor position indication quantity (166), in particular a rotor angle, of an electrical machine having a stator and a rotor, in particular a wind turbine electrical machine, in particular a permanent magnet synchronous generator, the apparatus comprising: an incremental mechanical encoder (127) mounted so as to sense a relative rotor position; at least one, in particular at least three, Hall effect sensors (120), in particular binary sensors, mounted at the stator so as to sense a magnetic field; an input port (167) adapted to: receive encoder measurement data (168) on a rotor position from the incremental mechanical encoder; receive Hall effect sensor measurement data (169) from the Hall effect sensors; a processor adapted to determine the rotor position indication quantity (166) based on the encoder measurement data and the Hall effect sensor measurement data.

13. A controller (150) for controlling an electrical machine (100) having a stator (102) and a rotor (103), in particular a wind turbine electrical machine, in particular a permanent magnet synchronous generator, the controller comprising: an apparatus (130) for determining a rotor position indication quantity according to the preceding claim; a control module (165) adapted to control the electrical machine based on the determined rotor position indication quantity, in particular to perform rotor positioning applying position, speed and / or torque control.

14. An electrical machine (100), in particular a wind turbine electrical machine, in particular a permanent magnet synchronous generator, the electrical machine comprising: a stator (102); a rotor (103); and a controller (150) according to the preceding claim.

15. A wind turbine (160) comprising: a hub (161) having a plurality of rotor blades (162) mounted thereon; an electrical machine (100) according to the preceding claim, wherein the rotor is coupled to the hub.

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