Magnetic gear system and method

Abstract

The present application discloses a system comprising: a stator having a plurality of windings configured to generate a rotating magnetic field; a first rotor having a plurality of permanent magnets having an associated second magnetic field; a second rotor through which the rotating magnetic field and the second magnetic field are coupled, wherein rotation of the first rotor is magnetically coupled to rotation of the second rotor; a first rotation sensor associated with the first rotor; a second rotation sensor associated with the second rotor; and a controller configured to control current supplied to the windings based on signals from the first sensor and signals from the second sensor, wherein one of the first rotor and the second rotor is a drive rotor configured to be attached to an external load, and the other of the first rotor and the second rotor is a passive rotor.

Description

[Technical Field]

[0001] The present disclosure relates to magnetic gear systems and corresponding methods. [Background technology]

[0002] A magnetic-geared system 100 operable as a motor is shown in FIGS. 1A and 1B. The magnetic-geared system 100 includes an outer stator 102, a first (inner) rotor 104, and a second (middle) rotor 106 radially disposed between the stator 102 and the first rotor 104. The stator 102 includes a plurality of circumferentially arranged conductive windings 108 and a plurality of first permanent magnets 120. The first rotor 104 includes a plurality of circumferentially arranged second permanent magnets 110. The second rotor 106 includes a plurality of circumferentially arranged unmagnetized magnetizable (typically ferromagnetic, e.g., steel) pole pieces 112. One of the first rotor 104 and the second rotor 106 can be connected to an external load (e.g., vehicle wheels). The other of the first rotor and the second rotor is passive in that it is not connected to a load. In the illustrated example, the second rotor is configured to connect to a load and the first rotor is passive, i.e., the second rotor 106 has a shaft 118 coupled thereto, and the first rotor 104 does not have a shaft coupled thereto.

[0003] A plurality of first permanent magnets 120 generate a first magnetic field, and a plurality of second permanent magnets 110 generate a second magnetic field. Pole pieces 112 regulate the interaction between the first and second magnetic fields, coupling the magnetic fields to generate a gear interaction between the first rotor 104 and the second rotor 106. In the illustrated example, the first rotor 104 has three pole pairs, and the second rotor 106 has 21 pole pieces. Thus, the second rotor rotates at a gear speed that is 1 / 7 the gear ratio of the first rotor (lower).

[0004] Additionally, by supplying the stator windings 108 with three-phase currents displaced by 120 degrees, a rotating magnetic field is set up within the system 100. This rotating magnetic field may have the same number of pole pairs as the first magnetic field generated by the first permanent magnets 110.

[0005] The rotating magnetic field therefore applies an electromagnetic torque to the first rotor, thereby driving the rotation of the first rotor 104. Furthermore, due to the magnetic coupling as described above, this in turn drives the rotation of the second rotor 106 at a lower gear speed than the first rotor 104.

[0006] 1A and 1B, the drive shaft 118 is attached to the second rotor 106. Thus, the rotating magnetic field drives the rotation of the drive shaft 118 at a lower gear speed. Therefore, the example of FIGS. 1A and 1B is particularly well suited for high torque applications where a large load is connected to the drive shaft (by virtue of the 1 / 7 gear ratio). However, as will be understood from reading this specification, in some examples, the drive shaft 118 may be attached to the first rotor.

[0007] Bearing B1 allows the first rotor 104 to rotate relative to the drive shaft 118. Similarly, bearing B2 allows the drive shaft and second rotor 106 to rotate relative to the stator 102.

[0008] A challenge with systems such as those shown in FIGS. 1A and 1B is that under high load torque, the rotating magnetic field can become disconnected from the rotor driving the drive shaft 118, at which point the electrical drive input to the windings 108 of the system 100 will not drive the rotation of the drive shaft 118, and instead vibrations will be observed in the system 100. Summary of the Invention

[0009] The present disclosure has been developed to overcome the above-mentioned problems.

[0010] In a first aspect, there is provided a system comprising: a stator including a plurality of windings configured to generate a rotating magnetic field; a first rotor including a plurality of permanent magnets having associated second magnetic fields; a second rotor through which the rotating magnetic field and a second magnetic field are coupled, such that rotation of the first rotor is magnetically coupled to rotation of the second rotor; a first rotation sensor associated with the first rotor; a second rotation sensor associated with the second rotor; a controller configured to control a current supplied to the winding based on a signal from the first sensor and a signal from the second sensor; Equipped with A system is provided in which one of the first rotor and the second rotor is a drive rotor configured to be attached to an external load, and the other of the first rotor and the second rotor is a passive rotor.

[0011] In particular, the fact that the rotating magnetic field couples with the second magnetic field through the second rotor then causes a magnetic coupling between the first rotor and the second rotor, which then causes a gear interaction between the first rotor and the second rotor.

[0012] The inventors have discovered that by determining the rotational dynamics of both rotors, even though one of the rotors is a passive rotor, it is possible to accurately determine when the rotating magnetic field is about to decouple from the drive rotor, and therefore to effectively prevent such decoupling by controlling the current supplied to the windings. In particular, the inventors have discovered that the relative rotational dynamics of the two rotors indicate the risk of decoupling between the rotating magnetic field and the drive rotor. This technical principle will be explained in more detail in the specific description below. In short, the first aspect utilizes the dynamics of the passive rotor to improve operation, even when the passive rotor is not connected to an external load.

[0013] For purposes of this specification, a passive rotor may be defined as one that is not connected to a load external to the system. A passive rotor may be driven solely by a rotating magnetic field. A drive rotor may be connected to a drive shaft to drive an external load.

[0014] Optional features are described.

[0015] The second rotor may be located between the first rotor and the stator. The second rotor may be a drive rotor. The first rotor may be a passive rotor.

[0016] The system may be a motor, the stator may further include a plurality of permanent magnets having associated first magnetic fields, and the second rotor may be positioned to couple the magnetic fields of the stator (i.e., the first magnetic field and the rotating magnetic field) with the second magnetic field.

[0017] The second rotor may include a plurality of pole pieces through which the stator magnetic field(s) couple with the second magnetic field, and each pole piece may include an unmagnetized magnetizable material (e.g., an unmagnetized ferromagnetic material such as unmagnetized steel).

[0018] Each rotation sensor may comprise a rotary encoder or a rotary resolver, and in some examples, at least one of the rotor positions may be calculated.

[0019] Each sensor may output a signal indicative of the angular position of the respective rotor. determining a load angle of the system based on the angular position of the first rotor and the angular position of the second rotor; adjusting the current supplied to the winding based on the determined load angle; It can be configured as follows.

[0020] As used herein, the angular position of a rotor may refer to the angle of rotation of the rotor relative to, for example, a fixed point on the stator (or its orientation). The fixed point or orientation may be any arbitrary fixed point on the stator (or the direction of its orientation). The angular positions of both rotors may be measured relative to the same fixed point or fixed orientation on the stator.

[0021] The load angle may be a measure of the angular displacement (e.g., phase difference) between the second magnetic field and the magnetic field induced in the pole pieces of the second rotor. As will be appreciated by those skilled in the art, for a given system (having a given number of permanent magnets and a given number of pole pieces), the load angle may be defined by the angular position of the first rotor and the angular position of the second rotor. As used herein, the load angle θ e can be defined as follows:

number

[0022] In the formula, θ R1 is the rotation angle of the first rotor, N R1 is the number of pole pairs on the first rotor (which may be equal to the number of permanent magnets), θ R2 is the rotation angle of the second rotor, N R2 is the number of pole pieces of the second rotor. For a given system, N R1 and N R1 is known and fixed.

[0023] As the load angle approaches 90°, there is a risk of pole slip (where the poles of the constituent magnetic fields in the system "slip" past each other), preventing the transmission of the electromagnetic torque of the rotating magnetic field to the first rotor and, in turn, to the external load. Because the relative angular positions (i.e., relative rotation angles) of the drive rotor and passive rotor are directly related to the load angle in the system, the load angle can be determined based on the relative angular positions of the drive rotor and passive rotor.

[0024] Adjusting the current supplied to the winding may include adjusting the magnitude of the current supplied to the winding. For example, the controller may be configured to change (e.g., reduce) the magnitude of the current supplied to the winding when the load angle increases above a predetermined threshold. For example, the controller may be configured to change (e.g., reduce) the magnitude of the current supplied to the winding in proportion to the amount by which the load angle exceeds the predetermined threshold.

[0025] Alternatively, the controller may be configured to vary (e.g., reduce) the magnitude of the current supplied to the winding in proportion to the rate at which the load angle increases above a predetermined threshold. As will be understood from reading this specification, this approach may enable predictive control.

[0026] In another example, the controller may be configured to modify (e.g., reduce) the magnitude of the current supplied to the winding when it is determined that the speed at which the load angle is increasing is predicted to cause the load angle to increase above a predetermined threshold.

[0027] The predetermined threshold may be at least 60 degrees, such as at least 70 degrees, for example at least 80 degrees. The predetermined threshold is at most 90 degrees, for example at most 85 degrees.

[0028] Each sensor may alternatively output a signal indicative of the rotational speed of the respective rotor, or the angular difference between successive position signals with a known time difference may be used to calculate the speed. determining a gear ratio (e.g., an instantaneous gear ratio) between the first rotor and the second rotor based on the rotational speed (e.g., the current rotational speed) of the rotor; adjusting the current supplied to the winding based on the determined gear ratio; It can be configured as follows.

[0029] The gear ratio may be determined as the ratio of the rotational speed of the first rotor to the rotational speed of the second rotor.

[0030] The adjustment may be an adjustment of the magnitude of the current supplied to the winding.

[0031] The controller determining an actual gear ratio between the first rotor and the second rotor based on the rotational speed of the rotors; Detecting when the actual gear ratio differs from the target gear ratio by a predetermined amount; adjusting the magnitude of the current supplied to the winding when the actual gear ratio differs from the target gear ratio by a predetermined amount; Adjusting the current supplied to the winding may include varying the magnitude of the current supplied to the winding, for example, reducing the magnitude of the current supplied to the winding.

[0032] The actual gear ratio can be defined as:

number

[0033] The target gear ratio may be defined as:

number

[0034] In a second aspect, there is provided a method of operating a system (e.g., a system according to the first aspect), the system comprising: a stator including a plurality of windings configured to generate a rotating magnetic field; a first rotor comprising a plurality of permanent magnets having associated second magnetic fields; a second rotor through which the rotating magnetic field and a second magnetic field are coupled, such that rotation of the first rotor is magnetically coupled to rotation of the second rotor; Equipped with one of the first rotor and the second rotor is a drive rotor configured to be attached to an external load, and the other of the first rotor and the second rotor is a passive rotor; The method comprises: determining one of an angular position and a rotational speed of the first rotor; determining one of an angular position and a rotational speed of a second rotor; controlling current supplied to the windings based on the determined angular position or rotational speed of the first rotor and based on the determined angular position or rotational speed of the second rotor; A method is provided, comprising:

[0035] The optional features are described below: As will be understood from reading this specification, the optional features of the first aspect are also applicable to the second aspect.

[0036] Determining the second rotor position may include detecting the second rotor position. Determining the first rotor position may include detecting or calculating the first rotor position. In an example embodiment, determining the first rotor position includes detecting the first rotor position.

[0037] An angular position of the first rotor and an angular position of the second rotor may be determined. determining a load angle of the system based on the angular position of the first rotor and the angular position of the second rotor; adjusting the current supplied to the winding based on the determined load angle; It may further include:

[0038] The magnitude of the current supplied to the winding may be reduced as the load angle increases above a predetermined threshold. For example, the magnitude of the current supplied to the winding may be reduced in proportion to the amount by which the load angle exceeds the predetermined threshold. For example, the magnitude of the current in the winding may be reduced toward zero as the amount by which the load angle exceeds the predetermined threshold increases. For example, the magnitude of the current in the winding may be gradually reduced such that the current in the winding becomes zero when the load angle reaches a second predetermined threshold that is greater than the first predetermined threshold. Alternatively, or in addition, the magnitude of the current supplied to the winding may be reduced in proportion to the rate at which the load angle increases above the predetermined threshold.

[0039] A rotational speed of the first rotor and a rotational speed of the second rotor may be determined. determining a gear ratio between the first rotor and the second rotor based on the rotational speed of the rotors; Varying the magnitude of the current supplied to the winding based on the determined gear ratio; It may further include:

[0040] The method comprises: determining an actual gear ratio between the first rotor and the second rotor based on the rotational speeds of the rotors; Detecting when the actual gear ratio differs from the target gear ratio by a predetermined amount; reducing the magnitude of current supplied to the winding when the actual gear ratio differs from the target gear ratio by a predetermined amount; may include:

[0041] In a third aspect, there is provided a system comprising: a stator including a plurality of windings configured to generate a rotating magnetic field; a first rotor including a plurality of permanent magnets having associated second magnetic fields; a second rotor through which the rotating magnetic field and a second magnetic field are coupled, such that rotation of the first rotor is magnetically coupled to rotation of the second rotor; a rotation sensor associated with the second rotor and configured to detect a rotational position of the second rotor; a controller, Calculating the electromagnetic torque in the system based on the magnitude of the current supplied to the windings (e.g., according to Equation 14 of the present disclosure or a look-up table); Calculating an estimated load angle for the system based on the electromagnetic torque and the known maximum torque capacity of the system (e.g., according to equation 12 of the present disclosure); calculating a theoretical first rotor position based on the detected second rotor position and the known gear ratio of the system (e.g., according to equation 15 of the present disclosure); a controller configured to control the phase of current supplied to the windings such that the rotating magnetic field is offset from the electrical angle associated with the theoretical first rotor position by an estimated load angle (e.g., according to equation 16 of the present disclosure); A system is provided, comprising:

[0042] One of the first rotor and the second rotor may be a drive rotor configured to be attached to an external load, and the other of the first rotor and the second rotor may be a passive rotor. The second rotor may be located between the first rotor and the stator. The second rotor may be a drive rotor. The first rotor may be a passive rotor.

[0043] The system may be a motor, the stator may further include a plurality of permanent magnets having associated first magnetic fields, and the second rotor may be positioned to couple the magnetic fields of the stator (i.e., the first magnetic field and the rotating magnetic field) with the second magnetic field.

[0044] The second rotor may include a plurality of pole pieces through which the stator magnetic field(s) couple with the second magnetic field, and each pole piece may include an unmagnetized magnetizable material (e.g., an unmagnetized ferromagnetic material such as unmagnetized steel).

[0045] The rotation sensor may comprise a rotary encoder or a rotary resolver.

[0046] In a fourth aspect, there is provided a method of operating a system (e.g., a system according to the third aspect), the system comprising: a stator including a plurality of windings configured to generate a rotating magnetic field; a first rotor including a plurality of permanent magnets having associated second magnetic fields; a second rotor through which the rotating magnetic field and a second magnetic field are coupled, such that rotation of the first rotor is magnetically coupled to rotation of the second rotor; a rotation sensor associated with the second rotor and configured to detect a rotational position of the second rotor; Equipped with The method comprises: Calculating the electromagnetic torque in the system based on the magnitude of the current supplied to the windings (e.g., according to Equation 14 of the present disclosure or a look-up table); Calculating an estimated load angle for the system based on the electromagnetic torque and the known maximum torque capacity of the system (e.g., according to equation 12 of the present disclosure); Calculating a theoretical first rotor position based on the detected second rotor position and a known gear ratio of the system (e.g., according to equation 15 of the present disclosure); controlling the phase of the current supplied to the windings such that the rotating magnetic field is offset by the estimated load angle from the electrical angle associated with the theoretical first rotor position (e.g., according to equation 16 of the present disclosure); A method is provided, comprising:

[0047] Finally, disclosed herein is a computer-readable medium (such as a non-transitory computer-readable medium) that stores instructions that, when executed by a processor, perform any one of the methods described or claimed herein.

[0048] The present disclosure is further described below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0049] [Figure 1A] 1 shows a cross-sectional view of a known magnetic gear system. [Figure 1B] 1B shows an axial view of the magnetic gear system of FIG. 1A. [Figure 2] 1B shows a cross-sectional view of a magnetic gear system according to the present disclosure, which is a modification of the magnetic gear system of FIG. 1A. [Figure 3] 3 shows a controller for controlling the magnetic gear system of FIG. 2. [Figure 4] 3 illustrates a first method of controlling the system according to FIG. 2 according to the present disclosure. [Figure 5] 3 illustrates a second method of controlling the system according to FIG. 2 according to the present disclosure. [Figure 6] 3 illustrates a third method of controlling the system according to FIG. 2 according to the present disclosure. [Figure 7] 4 illustrates a fourth method of controlling the system according to FIG. 2 according to the present disclosure. [Figure 8] 10 illustrates a fifth method of controlling a system according to FIG. 1 or FIG. 2 according to the present disclosure. [Figure 9] 1 illustrates a load angle diagram for a system according to the present disclosure. [Figure 10] 1 shows a simplified schematic representation of a computing device that can be used to implement the methods described herein. DETAILED DESCRIPTION OF THE INVENTION

[0050] Throughout the drawings, like reference numbers are used for like elements.

[0051] 2 illustrates a magnetic gear system 200 according to an example of the present disclosure. The magnetic gear system 200 includes the same components as the magnetic gear system 100 shown in FIGS. 1A and 1B. However, the magnetic gear system 200 further includes a first rotary encoder 202 for measuring the rotational dynamics of the first rotor 104 and a second rotary encoder 204 for measuring the rotational dynamics of the second rotor 106. The basic operating principle of the magnetic gear system 200 will be described first.

[0052] The frequency of the current(s) supplied to the windings 108 is controlled so that the rotating magnetic field created by the stator current(s) rotates at the same speed as the second magnetic field generated by the plurality of second permanent magnets 110, i.e., as the first rotor 104 rotates. Furthermore, the phase of the current(s) is typically maintained so that the rotating magnetic field created by the stator windings 108 remains synchronized (i.e., continues to rotate at the same speed as the first rotor) with the second magnetic field associated with the first rotor 104 at a constant angular difference (phase angle) of 90 degrees. By maintaining a 90-degree phase angle, maximum torque per ampere is achieved by the current supplied to the windings.

[0053] The second magnetic field of the plurality of second permanent magnets 110 is modulated by the pole pieces 112, thereby generating a resultant first magnetic field associated with the second rotor. The resultant first magnetic field has 18 pole pairs (21 pole pairs from the pole pieces 112, excluding 3 pole pairs from the second permanent magnets 110). As will be appreciated by those skilled in the art, the pole pieces 112 (each comprising unmagnetized magnetizable material, such as unmagnetized steel) act only as magnetic poles due to being externally magnetized. The resultant first magnetic field interacts with the plurality of first permanent magnets 120 because the plurality of first permanent magnets 120 have the same number of pole pairs. The resultant magnetic field of the 18 first pole pairs is determined by their angular position (θ) relative to the stationary stator 102, as determined by Equation 1: C1 )

number

[0054] In the formula, θ R1 is the rotation angle of the first rotor 104, and N R1 is the number of pole pairs on the first rotor 104 (which may be equal to the number of second permanent magnets 110 if each pole pair is provided by a single permanent magnet), and θ R2 is the rotation angle of the second rotor 106, and N R2 is the number of pole pieces 112 on the second rotor 106, and N stator is the number of magnetic pole pairs on the stator 102 (which may be equal to the number of first permanent magnets 120 on the stator 102 if each pole pair is provided by a single permanent magnet). C1 is sometimes defined as a mechanical angle because it is expressed in mechanical degrees, i.e., it maps in a 1:1 ratio to the angle on the stationary stator component. This, θ C1 The time derivative of gives the rotational speed of the stator relative to the reference frame.

[0055] By considering the relationship between the angular positions, the stator 102 (ω c1 ) can be determined from the time derivative of the rotor position given by Equation 2:

number

[0056] In the formula, ω R2 is the angular velocity of the second rotor, i.e., the time derivative of the second rotor position, and ω R1 is the angular velocity of the first rotor, i.e., the time derivative of the first rotor position.

[0057] For the system to remain synchronized, the resulting first magnetic field must be stationary relative to the plurality of first permanent magnets 120. Therefore, ω C1must be zero. Furthermore, the numerator of the above equation must be zero, which is given by Equation 3.

number

[0058] Therefore, the speed of the second rotor is adjusted as follows: In the example system 200 of the example of FIG.

number

number

[0059] It can therefore be seen that the effective gear ratio of the system is defined by the number of pole pieces 112 and the number of second permanent magnets 110 on the first rotor 104.

[0060] The relative electrical angular displacement (θ) between the rotors, also referred to herein as the load angle of the system, e ) can be written as Equation 6.

number

[0061] Load angle (θ e ) is zero when the system is at rest (no torque is applied). This corresponds to position A in Figure 9. In this state, the poles of the system are perfectly aligned. This is a stable state.

[0062] As the load is applied to the system, the load angle (θ e) increases, and the load angle increases until the total applied torque reaches a maximum value for the system 200, which corresponds to point B in FIG. 9, where the load angle is 90°. This represents the maximum static torque the magnetic system can respond to. If the torque increases above the system's maximum torque, the load angle increases further and the load capacity of the magnetic gear decreases, thereby increasing the load angle above 90°. At point C, the load angle increases to 180°, the total torque being transmitted is zero, and the system is highly unstable because the poles of the system are fully opposed. Moving to point D (load angle 270°), the torque becomes negative, causing this pole slip to become even higher. Thus, the load angle returns to 0° (360°), and at this point the same pole slip phenomenon continues until the total applied torque is reduced below the system's maximum torque. Once the total applied torque is reduced below the system's maximum torque, the pole slip will cease the next time the system approaches or reaches a load angle of 90° (point B). In essence, to maximize the torque capacity of the system, it is desirable to maintain the load angle close to but less than 90° (point B). At the same time, the load angle must be limited from increasing above 90° to avoid pole slip.

[0063] The gear torque can be controlled by the torque applied to the first rotor 104 from the rotating magnetic field from the windings. Under steady-state load conditions, the load angle remains constant and pole slip is avoided. In the case of a motor, a sudden increase in load torque (e.g., a sudden increase in torque or load on the shaft 118) causes a sudden deceleration of the output shaft 118 and, correspondingly, a sudden deceleration of the second rotor 106. The inertia of the first rotor 104 prevents this rotor's speed from decreasing too quickly, and, correspondingly, the load angle increases, thereby increasing the risk of pole slip. In this case, if pole slip is to be avoided, the second rotor 104 must also be decelerated by reducing the torque applied to it via the current in the stator windings.

[0064] Techniques according to the present disclosure for detecting impending pole slip and thereby enabling corrections to prevent pole slip as described above are described below.

[0065] The total torque (T) applied to the output rotor 118 of the magnetic gear system 200 as shown in FIG. 2 is the electromagnetic torque applied to the first rotor 104 multiplied by the gear ratio (T int ) and external load torque (T ext ) and the external torque (T ext ) can be negative in some situations. The total torque applied is given by Equation 7:

[0066] The magnitude of the current supplied to winding 108 has increased (thereby increasing the electromagnetic torque T int ) increases, the total torque T applied then increases. Furthermore, in the example of an electric drive vehicle, if a wheel driven by drive shaft 118 becomes stuck, the load torque T on drive shaft 118 ext The total applied torque T spikes due to the increase in

number

[0067] Pole slip is a phenomenon in which the rotating magnetic field of the magnetic gear system 200 becomes decoupled from the rotation of the drive shaft 118, causing the magnetic poles of the rotating magnetic field generated by the current in the windings 108 to "slip" past the magnetic poles associated with the plurality of second permanent magnets 110. This, in turn, causes a loss of drive and vibrations on the drive shaft 118 as the poles of the rotating magnetic field and the poles of the second magnetic field continue to misalign and realign. As shown in Equation 8, increasing the total torque applied to the magnetic gear system 200 increases the load angle (θ) of the system. e ) (defined herein as the angular displacement between the rotating magnetic field and the second magnetic field) is the maximum torque (T max) the load angle increases to a maximum of 90 degrees.

number

[0068] The total applied torque T is the maximum torque T of the system. max If exceeded, the maximum torque capacity of the system will be exceeded at all load angles at which point Equation 8 holds true such that a pole slip condition occurs, causing the rotating magnetic field to rotate relative to the second magnetic field, i.e., no rotation of the first rotor 104.

[0069] When a pole slip condition occurs and the rotating magnetic field is decoupled from the second magnetic field, the rotation of the first rotor 104 will also be decoupled from the rotation of the second rotor 106. Additionally, the load angle of the system is intrinsically related to the angular positions of the first and second rotors, as shown in Equation 6:

[0070] Thus, even though only the second rotor 106 is connected to an external load (via the drive shaft 118), the positions of both rotors can be used to estimate the load angle between the rotating field and the first rotor so that the risk of pole slip can be identified (i.e., when the load angle approaches 90°). Thus, the first rotary encoder 202 and the second rotary encoder 204 can be used to detect the occurrence of a pole slip condition and to prevent the occurrence of a pole slip condition.

[0071] By detecting the load angle using the rotor dynamics of the first rotor 104 and the second rotor 106, the rotary encoders 202, 204 can be used as described above to control the current supplied to the windings 108 to prevent pole slip. In particular, the electromagnetic torque T intAssuming that ρ is proportional to the amplitude of the current supplied to the winding 108, a controller can be used to reduce the current supplied to the winding 108 when a pole slip condition or risk of a pole slip condition is detected.

[0072] As will be understood from reading this specification, the load angle can be positive or negative (depending on the direction of rotation of the system 200), where the load angle can therefore be the magnitude of the load angle (i.e., agnostic of the direction of rotation).

[0073] Figure 3 illustrates a controller 300 for controlling the system 200 of Figure 2 to prevent pole slip. As shown, the controller receives a signal from the first rotary encoder 202, a signal from the second rotary encoder 204, and a signal from the drive unit 302 indicating that current is being supplied to the windings 108. The controller includes a temporary memory unit (RAM) 304 for storing the signals received from the first rotary encoder 202, the second rotary encoder 204, and the drive unit 302. The controller also includes a processor 306 and a memory unit 308. The memory unit 308 stores instructions that cause the processor 306 to process the signals stored in the temporary memory unit 304 and then generate a control signal for adjusting the current supplied to the windings 108. The control signal is output to the drive unit 302 as shown.

[0074] 4-8 illustrate several methods of controlling the magnetic gear system 200 according to the determined rotational dynamics of the first rotor 104 and the second rotor 106. Accordingly, the instructions stored in the storage unit 308 may be configured to implement the method outlined in any of FIGS.

[0075] Figure 4 illustrates a first method 400 according to the present disclosure for controlling the current supplied to the winding 108 of the system 200 of Figure 2. According to the first method, a threshold load angle is applied above which an adjustment (reduction) of the current to the winding is applied.

[0076] In step 402 , the angular position of the first rotor 104 is determined based on the signal from the first rotary encoder 202 , and the angular position of the second rotor 106 is determined based on the signal from the second rotary encoder 204 .

[0077] In step 404, the load angle (θ e ) is calculated.

[0078] In step 406, the calculated load angle θ e (Actual load angle) to the threshold load angle (θ th ) The threshold load angle may be 90°. In some examples, the threshold angle may be less than 90°, for example, 80°. Using a threshold angle less than 90° can help reduce the buffer, which can help improve pole slip prevention.

[0079] Threshold angle θ th The actual load angle θ e If exceeded, the method 400 proceeds to step 408. In step 408, a control signal is generated to reduce the magnitude of the current supplied to the winding. The control signal may be sent to the drive unit 302.

[0080] If the threshold angle is not exceeded, the method 400 may return to step 402 to continue monitoring the load angle for the system 200 .

[0081] 5 illustrates a second method 500 for controlling the current supplied to the winding 108 of the system 200 of FIG. 2 according to the present disclosure. According to the second method, multiple thresholds are used, and the amount by which the current is adjusted (reduced) depends on which threshold is exceeded. If a first (lower) threshold is exceeded, a first (smaller) amount of correction is applied. If a second (higher) threshold is exceeded, a second (larger) amount of correction is applied.

[0082] In step 502, the angular position of the first rotor 104 is determined based on the signal from the first rotary encoder 202, and the angular position of the second rotor 106 is determined based on the signal from the second rotary encoder 204.

[0083] In step 504, the load angle (θ) of the system is calculated using Equation 6 above. e ) is calculated.

[0084] In step 506, the calculated load angle θ e (actual load angle) to the first threshold load angle (θ th1 ) compared to

[0085] First Threshold Load Angle θ th1 If so, the method 500 proceeds to step 508. In step 508, a first correction signal is generated to reduce the current supplied to the winding 108.

[0086] First Threshold Load Angle θ th1 If not, the method 500 proceeds to step 510. In step 510, the calculated load angle θ e (actual load angle) to the second threshold load angle (θ th2 ) compared to

[0087] Second Threshold Load Angle θ th2 If so, the method 500 proceeds to step 512. In step 512, a second correction signal is generated to reduce the current supplied to the winding 108.

[0088] Second Threshold Load Angle θ th2 If not, the method 500 returns to step 502 to continue monitoring the load angle for the system 200 .

[0089] The first threshold angle may be less than the second threshold angle. For example, the first threshold angle may be 70° and the second threshold angle may be 80°. The first correction signal may command a greater reduction in the magnitude of the current than the second correction signal. For example, the first correction signal may command a 20% reduction in the magnitude of the current and the second correction signal may command a 10% reduction in the magnitude of the current.

[0090] In some examples, the size of the correction may be proportional to the amount by which the threshold is exceeded. For example, the size of the correction may be proportional to the amount by which the threshold is exceeded. th1 ) and a second threshold (θ th2 ) and the load angle (θ e ), it is defined by the following equation 9:

number

[0091] In the formula, C max is a predetermined maximum correction percentage, such as 20%. th2 can be, for example, 80°. th1 may be, for example, 70°. As will be understood from reading this specification, C max , θ th2 and θ th1 can be selected as needed.

[0092] Figure 6 illustrates a third method 600 of controlling the current supplied to the winding 108 of the system 200 of Figure 2 according to the present disclosure. According to the third method, the current supplied to the winding is adjusted (reduced) by an amount that depends on (e.g., proportional to) the rate at which the load angle is increasing above a threshold.

[0093] In step 602, a first angular position of the first rotor 104 is determined based on signals from the first rotary encoder 202, and a first angular position of the second rotor 106 is determined based on signals from the second rotary encoder 204.

[0094] In step 604, the first load angle (θ) of the system is calculated using Equation 6 above. e1 ) is calculated.

[0095] In step 605, the first load angle θ e1 The threshold angle (θ th ) compared to

[0096] First load angle θ e1 is the threshold load angle θ th If so, the method 600 returns to step 602 .

[0097] First load angle θ e1 is the threshold load angle θ th If so, method 600 proceeds to step 606. In step 606, for a predetermined time period after step 604, determine a second angular position of the first rotor 104 based on signals from the first rotary encoder 202 and determine a second angular position of the second rotor 106 based on signals from the second rotary encoder 204.

[0098] In step 608, the second load angle θ of the system is calculated using Equation 6 above. e2 where the second load angle indicates the load angle after a predetermined period of time after step 604.

[0099] In step 610, the second load angle θ e2 and the first load angle θ e1 The difference between the two is calculated and the difference is the threshold difference θ d Compare with.

[0100] The difference is the threshold difference θ d If so, the method 600 proceeds to step 612. In step 612, a first control signal is generated to reduce the magnitude of the current supplied to the winding. The first control signal may be sent to the drive unit 302.

[0101] The difference is the threshold difference θ dIf not, the method proceeds to step 614. In step 614, a second control signal is generated to reduce the magnitude of the current supplied to the winding. The second control signal may be sent to the drive unit 302.

[0102] The first control signal may command a reduction in the magnitude of the current supplied to the winding by a first amount greater than a second amount. For example, the first control signal may command a 20% reduction in the magnitude of the current, and the second control signal may command a 10% reduction in the magnitude of the current. As will be understood from reading this specification, these are merely examples and other values ​​may be used.

[0103] In some examples, the size of the correction may be proportional to the rate at which the load angle is increasing relative to the first load angle. e1 The rate of increase may be proportional to the rate at which the

[0104] Figure 7 illustrates a fourth method 700 according to the present disclosure for controlling the current supplied to the windings 108 of the system 200 of Figure 2. According to the fourth method, the actual gear ratio is calculated based on the rotational speeds of the two rotors, and a correction is applied when the actual gear ratio differs from the target gear ratio by a predetermined amount.

[0105] In step 702 , the rotational speed of the first rotor 104 is determined based on the signal from the first rotary encoder 202 , and the rotational speed of the second rotor 106 is determined based on the signal from the second rotary encoder 204 .

[0106] In step 704, the actual gear ratio of the system 200 is calculated according to equation 10 below:

number

[0107] In step 706, the actual gear ratio of the system 200 is compared to the target gear ratio of the system, which is given by Equation 11 and is predefined as will be understood from reading this specification.

number

[0108] In step 708, a control signal is generated based on the difference between the actual gear ratio and the target gear ratio. For example, the greater the difference, the greater the correction (i.e., the greater the reduction in the magnitude of the current). In some examples, the correction (e.g., reduction) may be applied when the difference exceeds a predetermined threshold. Similar to the second method of FIG. 5, multiple thresholds may be used. That is, if a first (lower) threshold is exceeded, a first (lower) correction may be applied, and if a second (higher) threshold is exceeded, a second (higher) correction may be applied. In some examples, the controller may begin adjusting the current only when the difference exceeds a minimum threshold.

[0109] Figure 8 shows a fifth method for controlling the current supplied to the windings 108 of a system 200 similar to Figure 2. However, the fifth method does not require any position sensors on the first rotor 104, as will become apparent below.

[0110] Transient load torque T on the system ext Assuming there is no (i.e., T ext = 0), equations 7 and 8 can be rearranged to find the theoretical load angle for the system:

number

[0111] Therefore, any transient load torque T on the system ext The theoretical load angle, ignoring the applied electromagnetic torque T int (which is proportional to the magnitude of the current supplied to winding 118) and the maximum torque of the system (which is itself a known parameter of the system).

[0112] Transient load torque Text When a load angle is applied to the system, the above estimate of the load angle will not accurately reflect the actual load angle on the system. There will be a phase error between the two. As a result, an additional phase shift is introduced into the system by supplying current to the windings based on the estimated load angle. A small phase error will result in only a small reduction in the effective electromagnetic torque to the system. However, a large phase error (i.e., a phase error that occurs when the actual load angle of the system approaches 90° (i.e., approaches a pole slip condition)) will result in a significant reduction in the effective electromagnetic torque and, therefore, a significant reduction in the total applied torque. This is shown in Equation 13 below:

number

[0113] In essence, the phase error between the estimated load angle and the actual load angle can be advantageously used to reduce torque to the system as the actual load angle approaches a pole slip condition.

[0114] In particular, if the estimated load angle is calculated based on the electromagnetic torque and the known maximum torque of the system (only), by continuing to drive the system according to the estimated load angle, the system can self-regulate the applied transient torque and reduce the total applied torque if the transient torque is high, thereby preventing pole slip from occurring.

[0115] Thus, according to the fifth method 800, in step 802, the controller determines the electromagnetic torque (T) applied to the system based on the magnitude of the current (I) supplied to the windings according to Equation 14: int ) is determined.

number

[0116] where k is a known system-specific torque constant and I is the magnitude of the current supplied to the winding. In some examples, T int The relationship between and I can be found by a lookup table.

[0117] In step 804, the controller calculates the estimated load angle according to Equation 12: max is a known property of the system.

[0118] In step 805, the rotational position (θ R2 ) to detect.

[0119] In step 806, the controller calculates the theoretical zero-load first rotor position (θ1) according to Equation 15.

number

[0120] where gear ratio is a known characteristic of the system as described above.

[0121] In step 808, the controller controls the phase of the current supplied to the windings so that the rotating magnetic field is offset from the field associated with the theoretical first rotor position by the estimated load angle, for example according to Equation 16.

number

[0122] where N1θ1 is the electrical angle associated with the theoretical first rotor position.

[0123] Through this approach, the method 800 self-regulates torque transients, thereby preventing pole slip.

[0124] Finally, attention is directed to FIG. 10, which shows a schematic and simplified representation of a computing device 1000 that can be used to implement the methods described herein, either alone, in combination with other computing devices, or as part of a network or “cloud” computing configuration.

[0125] The computing device 1000 comprises various data processing resources, such as a processor 1002 (especially a hardware processor) coupled to a central bus structure. Also connected to the bus structure are further data processing resources, such as memory 1004. A display adapter 1006 connects a display device 1008 to the bus structure. One or more user input device adapters 1010 connect user input devices 1012, such as a keyboard and / or mouse, to the bus structure. One or more communications adapters 1014 are connected to the bus structure to provide connectivity to other computer systems 1000 or other networks.

[0126] In operation, processor 1002 of computer system 1000 executes a computer program made up of computer-executable instructions that may be stored in memory 1004. The computer-executable instructions, when executed, may cause computer system 1000 to perform one or more of the methods described herein. Results of the performed processing may be displayed to a user via display adapter 1006 and display device 1008. User input for controlling the operation of computer system 1000 may be received from user input device 1012 via user input device adapter 1010.

[0127] In some cases, some features of the computer system 1000 shown in Figure 10 may not be present. For example, one or more of the computer devices 1000 may not require a display adapter 1006 or a display device 1008. This may be the case, for example, for a particular server-side computer device 600 that is used solely for processing power and does not need to display information to a user. Similarly, the user input device adapter 1010 and the user input device 1012 may not be required. In its simplest form, the computer device 1000 includes a processor 1002 and a memory 1004.

[0128] It will be appreciated that the described arrangements and methods are merely exemplary and that various modifications may be made by those skilled in the art without departing from the scope of the appended claims.

[0129] More generally, it should be understood that the number of steps shown in each figure is not intended to be limiting: steps may be repeated as needed, and certain steps may be omitted.

[0130] The computer device mentioned above may be a local computer or a server.

[0131] Although various specific combinations of components and method steps have been described, these are merely examples. Components and method steps can be combined in any suitable configuration or combination. Components and method steps can be omitted so as to leave any suitable combination of components or method steps.

[0132] The described methods can be implemented using computer-executable instructions. A computer program product or computer-readable medium can comprise or store computer-executable instructions. The computer program product or computer-readable medium can comprise a hard disk drive, flash memory, read-only memory (ROM), CD, DVD, cache, random access memory (RAM), and / or any other storage medium on which information is stored for any duration (e.g., long term, permanently, momentarily, for temporary buffering, and / or for caching information). A computer program can comprise computer-executable instructions. A computer-readable medium can be a tangible computer-readable medium or a non-transitory computer-readable medium. The term "computer-readable" encompasses "machine-readable."

[0133] In one implementation, the modules, components and other features described herein may be implemented as discrete components or integrated into the functionality of a hardware component such as an ASIC, FPGA, DSP, or similar device.

[0134] The singular forms "a" and "an" should not be construed as meaning "one and only one." Rather, unless otherwise specified, they should be construed as meaning "at least one" or "one or more." The words "comprising" and derivatives thereof, including "comprises" and "comprise," include each of the stated features but do not exclude the inclusion of one or more additional features.

[0135] Also disclosed herein are several broad concepts under the following numbered clauses: As will be understood upon reading this specification, any number of the following clauses may be combined: As will be understood upon reading this specification, the following numbered clauses may apply to system 200 as described above and shown in the drawings:

[0136] Clause 1. A system for detecting external torque disturbances by monitoring the load angle between rotors.

[0137] Clause 2. A system that monitors the load angle and uses a threshold or maximum value at which a corrective torque is applied to prevent pole slip.

[0138] Clause 3. A system that uses increased correction when the load angle deviates significantly beyond a threshold value.

[0139] Clause 4. A system that uses relative rotor speed to monitor gear ratio in real time and pass that value to a controller for diagnostic purposes.

[0140] Clause 5. A system that compares gear ratios to known expected values ​​and applies corrections if the values ​​exceed a threshold.

[0141] Clause 6. A system using load angle estimation that does not correct for externally applied torque and therefore automatically reduces applied rotor torque.

[0142] Clause 7. A system that induces a phase error between the rotor position and the current waveform to prevent pole slip, reducing the torque output of the machine.

[0143] Clause 8. A system that provides an input signal to a controller using a signal proportional to the speed error between the rotors to apply a torque that prevents pole slip.

[0144] Clause 9. A system that calculates a predicted load angle from the applied torque and compares it with a measured load angle to provide diagnostic data to the drive.

[0145] Clause 10. A system in which a threshold for the allowable load angle is set around a predicted value, outside which the controller provides a corrective torque to prevent pole slip.

[0146] Clause 11. A system that detects pole slip by utilizing the relative speed of the rotors.

[0147] Clause 12. A system that detects pole slip by using a measured load angle between rotors.

[0148] Clause 13. A system that, when pole slip is detected, provides a torque demand to the HSR that attempts to change its speed to equal a speed that allows resynchronization of the rotor.

[0149] The examples described and depicted in the accompanying drawings are provided as examples of how the invention may be practiced and are not intended to limit the scope of the invention. Modifications may be made, elements may be replaced with functionally and structurally equivalent parts, and features of different embodiments may be combined, without departing from the present disclosure. In particular, features described in the above examples may be combined with each other, provided that such combinations are technically feasible.

Claims

1. 1. A system comprising: a stator including a plurality of windings configured to generate a rotating magnetic field; a first rotor comprising a plurality of permanent magnets having associated second magnetic fields; a second rotor through which the rotating magnetic field and the second magnetic field are coupled, such that rotation of the first rotor is magnetically coupled to rotation of the second rotor; a first rotation sensor associated with the first rotor; a second rotation sensor associated with the second rotor; a controller configured to control a current supplied to the winding based on a signal from the first sensor and a signal from the second sensor; Equipped with one of the first rotor and the second rotor is a drive rotor configured to be attached to an external load, and the other of the first rotor and the second rotor is a passive rotor; system.

2. The system of claim 1 , wherein the second rotor is the drive rotor.

3. The system of claim 1 or claim 2, wherein the stator further comprises a plurality of permanent magnets having associated first magnetic fields.

4. The system of claim 3 , wherein the second rotor is positioned to couple the magnetic field of the stator with the second magnetic field.

5. The system of any preceding claim, wherein the second rotor comprises a plurality of pole pieces through which the magnetic field(s) of the stator couple with the second magnetic field.

6. A system according to any preceding claim, wherein each rotation sensor comprises a rotary encoder or a rotary resolver.

7. each sensor outputs a signal indicative of the angular position of its respective rotor; and determining a load angle of the system based on the angular position of the first rotor and the angular position of the second rotor; adjusting the current supplied to the winding based on the determined load angle; The system according to any one of claims 1 to 6, configured as follows:

8. The system of claim 7 , wherein the controller is configured to modify the magnitude of the current supplied to the winding when the load angle increases above a predetermined threshold.

9. 9. The system of claim 8, wherein the controller is configured to vary the magnitude of the current supplied to the winding in proportion to the amount by which the load angle exceeds the predetermined threshold.

10. 9. The system of claim 8, wherein the controller is configured to vary the magnitude of the current supplied to the winding in proportion to the rate at which the load angle increases above the predetermined threshold.

11. each sensor outputs a signal indicative of the rotational speed of the respective rotor; and the controller determining a gear ratio between the first rotor and the second rotor based on the rotational speed of the rotor; adjusting the current supplied to the winding based on the determined gear ratio. The system according to any one of claims 1 to 6, configured as follows:

12. The controller: determining an actual gear ratio between the first rotor and the second rotor based on the rotational speed of the rotor; Detecting when the actual gear ratio differs from the target gear ratio by a predetermined amount; reducing the magnitude of the current supplied to the winding when the actual gear ratio differs from the target gear ratio by the predetermined amount. The system of claim 11 configured to:

13. 1. A method of operating a system, the system comprising: a stator including a plurality of windings configured to generate a rotating magnetic field; a first rotor comprising a plurality of permanent magnets having associated second magnetic fields; a second rotor through which the rotating magnetic field and the second magnetic field are coupled, such that rotation of the first rotor is magnetically coupled to rotation of the second rotor; Equipped with one of the first rotor and the second rotor is a drive rotor configured to be attached to an external load, and the other of the first rotor and the second rotor is a passive rotor; The method comprises: determining one of an angular position and a rotational speed of the first rotor; determining one of an angular position and a rotational speed of the second rotor; controlling current supplied to the windings based on the determined angular position or rotational speed of the first rotor and based on the determined angular position or rotational speed of the second rotor; A method comprising:

14. The angular position of the first rotor and the angular position of the second rotor are determined, and the method further comprises: determining a load angle of the system based on the angular position of the first rotor and the angular position of the second rotor; adjusting the current supplied to the winding based on the determined load angle; The method of claim 13 further comprising:

15. 15. The method of claim 14, wherein the magnitude of the current supplied to the winding is reduced when the load angle increases above a predetermined threshold.

16. 16. The method of claim 15, wherein the magnitude of the current supplied to the winding is reduced in proportion to the amount the load angle exceeds the predetermined threshold.

17. 16. The method of claim 15, wherein the magnitude of the current supplied to the winding is reduced in proportion to the rate at which the load angle increases above the predetermined threshold.

18. The rotational speed of the first rotor and the rotational speed of the second rotor are determined, and the method further comprises: determining a gear ratio between the first rotor and the second rotor based on the rotational speed of the rotors; Varying the magnitude of the current supplied to the winding based on the determined gear ratio; The method of claim 13 further comprising:

19. determining an actual gear ratio between the first rotor and the second rotor based on the rotational speed of the rotors; detecting when the actual gear ratio differs from the target gear ratio by a predetermined amount; reducing the magnitude of the current supplied to the winding when the actual gear ratio differs from the target gear ratio by the predetermined amount; 20. The method of claim 18, comprising:

20. 1. A system comprising: a stator including a plurality of windings configured to generate a rotating magnetic field; a first rotor comprising a plurality of permanent magnets having associated second magnetic fields; a second rotor through which the rotating magnetic field and the second magnetic field are coupled, such that rotation of the first rotor is magnetically coupled to rotation of the second rotor; a rotation sensor associated with the second rotor and configured to detect a rotational position of the second rotor; a controller, calculating an electromagnetic torque in the system based on the magnitude of the current supplied to the winding; calculating an estimated load angle of the system based on the electromagnetic torque and a known maximum torque capacity of the system; calculating a theoretical first rotor position based on the detected second rotor position and a known gear ratio of the system; controlling the phase of the current supplied to the windings so that the rotating magnetic field is offset from an electrical angle associated with a theoretical first rotor position by the estimated load angle; a controller configured to: A system comprising:

21. 1. A method of operating a system, the system comprising: a stator including a plurality of windings configured to generate a rotating magnetic field; a first rotor comprising a plurality of permanent magnets having associated second magnetic fields; a second rotor through which the rotating magnetic field and the second magnetic field are coupled, such that rotation of the first rotor is magnetically coupled to rotation of the second rotor; a rotation sensor associated with the second rotor and configured to detect a rotational position of the second rotor; Equipped with The method comprises: calculating an electromagnetic torque in the system based on the magnitude of the current supplied to the winding; calculating an estimated load angle of the system based on the electromagnetic torque and a known maximum torque capacity of the system; calculating a theoretical first rotor position based on the detected second rotor position and a known gear ratio of the system; controlling the phase of the current supplied to the windings so that the rotating magnetic field is offset from an electrical angle associated with a theoretical first rotor position by the estimated load angle; A method comprising:

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