Motor demagnetization detection method and motor demagnetization detection device

Abstract

A motor demagnetization detection method and device, the method comprising the following steps: measuring the rotation angle of a motor device using an encoder; measuring the three-phase current values of the motor device using a current sensing device; calculating the rotation speed of the motor device based on the rotation angle; receiving the three-phase current values to obtain and store first steady-state data when the motor device is determined to be in a first steady-state based on the rotation speed; receiving the three-phase current values to obtain and store second steady-state data when the motor device is determined to be in a second steady-state based on the rotation speed; calculating and storing an equivalent magnetic flux based on the first steady-state data and the second steady-state data; repeatedly driving the motor device to maintain the first steady-state and the second steady-state, updating the first steady-state data and the second steady-state data based on the three-phase current values, and recalculating and storing the equivalent magnetic flux to generate a plurality of equivalent magnetic fluxes; calculating a magnetic flux change based on the plurality of equivalent magnetic fluxes; and issuing a demagnetization warning based on a comparison result of the magnetic flux change and a demagnetization warning value.

Description

Technical Field

[0001] The present invention relates to a motor detection method and a motor detection device, and more particularly to a motor demagnetization detection method and a motor demagnetization detection device for detecting a change in magnetic flux. Background Art

[0002] Generally speaking, permanent magnet synchronous motors (PMSMs) require no additional excitation current to generate a rotor magnetic field and offer advantages such as high efficiency, low inertia, and high power density. In recent years, they have been widely used in industrial applications such as electric vehicles, robotic arms, and elevators.

[0003] On the other hand, field weakening control is commonly incorporated into the control of permanent magnet synchronous motors. This involves applying a demagnetizing current to the motor's direct axis (or d-axis) to extend the operating speed range. However, excessive d-axis current can permanently demagnetize the rotor magnets, thereby reducing motor performance. Furthermore, as rotor temperature increases, the d-axis current required to permanently demagnetize the magnets decreases, making permanent magnet synchronous motors more susceptible to permanent demagnetization. Therefore, effectively detecting demagnetization in electric motors is a critical issue. Summary of the Invention

[0004] The present invention provides a motor demagnetization detection method and a motor demagnetization detection device, thereby effectively estimating magnetic flux and reducing magnetic flux estimation error, thereby increasing the accuracy of demagnetization phenomenon detection.

[0005] The present invention provides a motor demagnetization detection method for detecting a motor device, and the motor demagnetization detection method includes the following steps: measuring the rotation angle of the motor device using an encoder; measuring the three-phase current values of the motor device using a current sensing device; calculating the rotation speed of the motor device based on the rotation angle; receiving the three-phase current values to obtain and store first steady-state data when the motor device is determined to be in a first steady-state based on the rotation speed; receiving the three-phase current values to obtain and store second steady-state data when the motor device is determined to be in a second steady-state based on the rotation speed; calculating and storing an equivalent magnetic flux based on the first steady-state data and the second steady-state data; repeatedly driving the motor device to maintain the first steady-state and the second steady-state, updating the first steady-state data and the second steady-state data based on the three-phase current values, and recalculating and storing the equivalent magnetic flux to generate a plurality of equivalent magnetic fluxes; calculating a magnetic flux change based on the equivalent magnetic flux; and issuing a demagnetization warning based on a comparison result of the magnetic flux change and a demagnetization warning value.

[0006] The present invention provides a motor demagnetization detection device for detecting a motor device. The motor demagnetization detection device includes an encoder, a current sensing device, and a controller. The encoder measures the rotation angle of the motor device. The current sensing device measures the three-phase current values of the motor device. The controller is coupled to the encoder and the current sensing device. The controller calculates the rotation speed of the motor device based on the rotation angle. When the controller determines that the motor device is maintaining a first steady state based on the rotation speed, the controller receives the three-phase current values to obtain and store first steady-state data. When the controller determines that the motor device is maintaining a second steady state based on the rotation speed, the controller receives the three-phase current values to obtain and store second steady-state data. The controller calculates and stores an equivalent magnetic flux based on the first and second steady-state data. The motor device is repeatedly driven to maintain the first and second steady states, and the controller updates the first and second steady-state data based on the three-phase current values and recalculates and stores the equivalent magnetic flux to generate a plurality of equivalent magnetic fluxes. The controller calculates a magnetic flux change based on the equivalent magnetic flux and issues a demagnetization warning based on a comparison of the magnetic flux change with a demagnetization warning value.

[0007] The motor demagnetization detection method and device disclosed herein receive three-phase current values to obtain and store first steady-state data when the motor device is determined to be in a first steady-state based on the motor speed. When the motor device is determined to be in a second steady-state based on the motor speed, receive three-phase current values to obtain and store second steady-state data. Equivalent magnetic flux is calculated and stored based on the first and second steady-state data. The motor device is repeatedly driven to maintain the first and second steady-states, and the first and second steady-state data are updated based on the three-phase current values. The equivalent magnetic flux is recalculated and stored to generate multiple equivalent magnetic fluxes. A magnetic flux change is calculated based on the equivalent magnetic flux. A demagnetization warning is then issued based on a comparison of the magnetic flux change with a demagnetization warning value. This method effectively estimates magnetic flux and reduces flux estimation errors caused by nonlinear characteristics of integrated circuits, thereby increasing the accuracy of demagnetization detection. Furthermore, motor parameters related to the motor (such as direct-axis inductance) are not used, thereby increasing detection convenience and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 FIG. 4 is a schematic diagram of a motor demagnetization detection device according to an embodiment of the present invention.

[0009] Figure 2 FIG. 1 is a schematic diagram of a current sensing device according to an embodiment of the present invention.

[0010] Figure 3 FIG. 4 is a schematic diagram of a current sensing device according to another embodiment of the present invention.

[0011] Figure 4 FIG. 4 is a flow chart of a motor demagnetization detection method according to an embodiment of the present invention.

[0012] Figure 5 FIG. 1 is a waveform diagram of the motor speed and quadrature-axis current when the motor is driven by a motor demagnetization detection device according to an embodiment of the present invention.

[0013] Description of reference numerals:

[0014] 100: Motor demagnetization detection device

[0015] 110: Encoder

[0016] 120: Current sensing device

[0017] 130: Controller

[0018] 131: Speed Controller

[0019] 132: Current Controller

[0020] 133: Modulation unit

[0021] 134: Speed Calculator

[0022] 135: Three-phase to two-phase converter

[0023] 136: Estimation Unit

[0024] 150: Motor unit

[0025] 151: Inverter

[0026] 152: Motor

[0027] 153: Rectifier

[0028] 210, 220, 310, 320, 330: Current sensors

[0029] ω m * : Speed command

[0030] i a ,i b ,i c : Three-phase current value

[0031] i′ a ,i′ b ,i′ c : Current detection value

[0032] v q1 : First quadrature-axis voltage

[0033] v q2 : Second quadrature-axis voltage

[0034] v d1 : First straight axis voltage

[0035] v d2 : Second direct-axis voltage

[0036] i q1 : First quadrature-axis current

[0037] i q2 : Second quadrature-axis current

[0038] i d1 : First straight axis current

[0039] i d2 : Second direct-axis current

[0040] S1: Motor speed

[0041] S2: quadrature axis current

[0042] Speed1: First rated speed

[0043] Speed2: Second rated speed

[0044] T1~T5: Time

[0045] S402~S418: Steps DETAILED DESCRIPTION

[0046] In the various embodiments listed below, the same reference numerals will be used to represent the same or similar elements or components.

[0047] Figure 1 FIG1 is a schematic diagram of a motor demagnetization detection device according to an embodiment of the present invention. The motor demagnetization detection device 100 of this embodiment is used to detect a motor device 150, wherein the motor device 150 may include an inverter 151 and a motor 152. The inverter 151 may output a three-phase current value i according to a control command. a 、i b 、i c, to drive the motor 152, so that the motor 152 is in operation. In this embodiment, the motor demagnetization detection device 100 can first receive a speed command (speed command), and generate a control command to the inverter 151 according to the speed command. In some embodiments, the motor 152 is, for example, a permanent magnet synchronous motor, and the motor 152 can be applied to elevators, electric vehicles, robotic arms, etc., but the embodiments of the present invention are not limited thereto. Furthermore, the motor device 150 may further include a rectifier 153. The rectifier 153 is coupled to the inverter 151 to provide a rectified voltage to the inverter 151. In addition, the rectifier 153 is, for example, a full-bridge rectifier, but the embodiments of the present invention are not limited thereto.

[0048] Please refer to Figure 1 The motor demagnetization detection device 100 may include an encoder 110 , a current sensing device 120 and a controller 130 .

[0049] The encoder 110 measures the rotation angle of the motor device 150 (eg, the motor 151 ) to output a motor position signal. In this embodiment, the encoder 110 may be a position sensor.

[0050] The current sensing device 120 is used to measure the three-phase current value of the motor device 150. Specifically, the current sensing device 120 is coupled to the output terminal of the inverter 151 and measures the three-phase current value i output by the inverter 151. a 、i b 、i c , to generate three-phase current values i a 、i b 、i c Current detection value (e.g. i′ a , i′ b , i′ c ).

[0051] In some embodiments, the current sensing device 120 may include two current sensors 210, 220, such as Figure 2 The current sensors 210 and 220 are used to measure the three-phase current values i output by the inverter 151. a 、i b 、i c The first phase current (e.g. i a ) and the second phase current (e.g. i b ) to generate the corresponding current detection value (e.g. i′ a , i′ b ) and the controller 130 can be based on the first phase current (eg i a ) corresponding to the current detection value (e.g. i′ a) and the second phase current (e.g. i b ) corresponding to the current detection value (e.g. i′ b ) calculate the third phase current of the three-phase current value (for example, i c ) corresponding to the current detection value (e.g. i′ c ).

[0052] In some embodiments, the current sensing device 120 may include three current sensors 310, 320, and 330. The current sensors 310, 320, and 330 respectively measure the three-phase current values i output by the inverter 151. a 、i b 、i c The first phase current (e.g. i a ), the second phase current (for example, i b ) and the third phase current (e.g. i c ), so that the current sensing device 120 can generate three-phase current values i a 、i b 、i c Current detection value (e.g. i′ a , i′ b , i′ c It is particularly noted that the current sensors 210 , 220 , 310 , 320 , and 330 may be Hall sensors or current sensing resistors, but the present invention is not limited thereto.

[0053] Controller 130 is coupled to inverter 151, encoder 110, and current sensing device 120. Controller 130 can provide control commands to inverter 151. Controller 130 can receive the motor position signal output by encoder 110 and the current detection value generated by current sensing device 120. Controller 130 can calculate the rotational speed of motor 152 (motor device 150) based on the motor position signal (e.g., rotational angle). Typically, controller 130 determines the rotational angle of motor 152 based on the motor position signal and differentiates the rotational angle of motor 152 to obtain the rotational speed of motor 152.

[0054] Next, the controller 130 can determine whether the motor device 150 is maintained in a first steady state based on the obtained rotational speed of the motor 152 (e.g., whether the rotational speed of the motor 152 has been maintained at a first rated rotational speed for longer than a first predetermined time and within a first error range). In this embodiment, the first rated rotational speed is, for example, 1000 rpm, and the first error range is, for example, 5%. In other words, the controller 130 determines whether the rotational speed of the motor 152 is maintained within 5% of the first rated rotational speed, for example, between 950 rpm and 1050 rpm. However, the first rated rotational speed of 1000 rpm and the first error range of 5% are merely exemplary embodiments of the present invention and are not intended to limit the present invention. In other embodiments, the user may set the first rated rotational speed to 800 rpm, 900 rpm, 1100 rpm, 1200 rpm, etc., and the first error range to 2%, 8%, 10%, 15%, etc., as desired.

[0055] When the controller 130 determines that the motor device 150 is not maintained in the first steady state (for example, the rotational speed of the motor 152 is not maintained at the first rated rotational speed for more than a first predetermined time and within a first error range), the controller 130 will continue to calculate the rotational speed of the motor 152 based on the motor position signal output by the encoder 110 to again determine whether the motor device 150 is maintained in the first steady state.

[0056] When the controller 130 determines that the motor device 150 is maintained in the first steady state (for example, the speed of the motor 152 is maintained at the first rated speed for more than the first predetermined time and within the first error range), the controller 130 receives the three-phase current value i a 、i b 、i c The corresponding current detection value (e.g. i′ a , i′ b , i′ c ) to obtain and store the first steady-state data. In this embodiment, the first steady-state data may include the first straight-axis current (eg, i d1 ), the first straight axis voltage (for example, v d1 ), the first quadrature-axis current (e.g., i q1 ) and the first quadrature axis voltage (e.g. v q1 ).

[0057] Next, the controller 130 can determine whether the motor device 150 is maintained in the second steady state based on the obtained rotational speed of the motor 152 (for example, determining whether the rotational speed of the motor 152 is maintained at the second rated rotational speed for more than a second preset time and within a second error range). In this embodiment, the second rated rotational speed is, for example, 50 rpm, and the second error range is, for example, 10%. In other words, the controller 130 will determine whether the rotational speed of the motor 152 is maintained within 10% of the second rated rotational speed, for example: the rotational speed is maintained between 45 rpm and 55 rpm. However, the second predetermined rated rotational speed of 50 rpm and the second error range of 10% are only an example of an embodiment of the present invention and are not used to limit the embodiments of the present invention. In other embodiments, the user can also set the second predetermined rated rotational speed to 30 rpm, 40 rpm, 60 rpm, 80 rpm, etc. according to their needs, and the second error range is 5%, 8%, 15%, etc.

[0058] In one embodiment, the first rated speed, the second rated speed, the first error range, and the second error range are program settings in controller 130. Typically, the second rated speed is lower than the first rated speed, but the present invention is not limited thereto. In other embodiments, the second rated speed is typically zero, for example, in the case of an elevator system motor. When an elevator car reaches a designated floor, the speed of the elevator system motor is zero.

[0059] When the controller 130 determines that the motor device 150 is not maintained in the second steady state (for example, the rotational speed of the motor 152 is not maintained at the second rated rotational speed for more than the second predetermined time and within the second error range), the controller 130 continues to obtain the rotational speed of the motor 152 based on the motor position signal output by the encoder 110 to again determine whether the motor device 150 is maintained in the second steady state.

[0060] When the controller 130 determines that the motor device 150 is maintained in the second steady state (for example, the speed of the motor 152 is maintained at the second rated speed for more than the second predetermined time and within the second error range), the controller 130 receives the three-phase current value i a 、i b 、i c The corresponding current detection value (e.g. i′ a , i′ b , i′ c ) to obtain and store the second steady-state data. In this embodiment, the second steady-state data may include the second direct-axis current (eg, i d2 ), the second direct axis voltage (for example, v d2 ), the second quadrature-axis current (e.g., i q2 ) and the second quadrature axis voltage (e.g. v q2 ).

[0061] After the controller 130 obtains the first steady-state data and the second steady-state data, the controller 130 may obtain and store the equivalent magnetic flux according to the first steady-state data and the second steady-state data.

[0062] In this embodiment, the direct-axis-quadrature-axis (dq-axis) voltage equation of the motor 152 can be expressed as equation (1):

[0063]

[0064] Among them, v d is the direct axis (d axis) voltage, v q is the quadrature axis (q axis) voltage, r s is the stator resistance, i d is the direct axis current, i q is the quadrature axis current, L d is the direct-axis inductance, L q is the quadrature-axis inductance, is the differential operator, ω e is the motor angular velocity of the motor 152, λ' m is the equivalent magnetic flux.

[0065] When the motor 152 runs to a steady state (for example, the speed of the motor 152 maintains the rated speed within the error range), equation (1) can be rewritten as equation (2) as follows:

[0066]

[0067] Furthermore, by sampling the quadrature-axis voltage (e.g., the first quadrature-axis voltage of the first steady-state data and the second quadrature-axis voltage of the second steady-state data) at different speed operating points (e.g., the first rated speed and the second rated speed) under a fixed load, equations (3a) and (3b) can be obtained from equation (2), as shown below:

[0068] v q1 =r s i q1 +ω e1 (L d i d1 +λ' m ) (3a)

[0069] v q2 =r s i q2 +ω e2 (L d i d2 +λ' m ) (3b)

[0070] Among them, v q1 is the first quadrature axis voltage, iq1 is the first quadrature-axis current, ω e1 is the first rated speed, i d1 is the first straight axis current, v q2 is the second quadrature axis voltage, i q2 is the second quadrature-axis current, ω e2 is the second rated speed, i d2 is the second direct-axis current.

[0071] Then, the first quadrature axis voltage v obtained at the two speed operating points is q1 and the second quadrature axis voltage v q1 Subtract, that is, subtract equation (3a) from equation (3b) to obtain equation (4), as shown below:

[0072] v q1 -v q2 =r s (i q1 -i q2 )+ω e1 (L d i d1 +λ' m )-ω e2 (L d i d2 +λ' m ) (4)

[0073] When the first quadrature-axis current i q1 ≈ the second quadrature-axis current i q2 and the first straight-axis current i d1 ≈ the second direct axis current i d2 , Equation (4) can be simplified to Equation (5) as shown below:

[0074] v q1 -v q2 =(ω e1 -ω e2 )(L d i d1 +λ' m ) (5)

[0075] Then, equation (5) can be rewritten as equation (6) to estimate the equivalent magnetic flux.

[0076]

[0077] in, That is, the controller 130 can estimate the equivalent magnetic flux according to formula (6) and store the equivalent magnetic flux.

[0078] Furthermore, if the direct-axis current (for example, the first direct-axis current id1 ) is controlled to zero, equation (6) can be simplified to equation (7), as shown below:

[0079]

[0080] That is to say, the controller 130 can also estimate the equivalent magnetic flux according to formula (7). It can be seen from formula (7) that the equivalent magnetic flux It can be calculated from different rated speeds (such as the first rated speed and the second rated speed) and their corresponding quadrature-axis voltages (the first quadrature-axis voltage and the second quadrature-axis voltage), without using the motor parameters related to the motor 152 (such as the direct-axis inductance L d ) to increase the convenience and accuracy of detection.

[0081] In this way, by estimating the equivalent magnetic flux corresponding to motor 152, controller 130 can effectively determine the operating status of motor 152, namely, whether the temperature of the rotor of motor 152 is too high or whether motor 152 has experienced demagnetization. For example, when the equivalent magnetic flux is lower than a predetermined threshold, it indicates that the temperature of the rotor of motor 152 is too high or that motor 152 has experienced demagnetization. Conversely, when the first magnetic flux is higher than the predetermined threshold, it indicates that the temperature of the rotor of motor 152 is not too high or that motor 152 has not experienced demagnetization.

[0082] In some embodiments, the controller 130 can adjust the control command to the inverter 151 according to the motor position signal, the first steady-state data and the second steady-state data, so that the inverter 151 changes the three-phase current value to drive the motor 152. Figure 1 As shown, the controller 130 may include a speed controller 131 , a current controller 132 , a modulation unit 133 , a speed calculator 134 , a three-phase to two-phase converter 135 and an estimation unit 136 , but the embodiment of the present invention is not limited thereto.

[0083] The speed controller 131 can receive the speed command ω m * and the speed of the motor 152, and according to the speed command ω m * The current controller 132 is coupled to the speed controller 131 and receives the current command generated by the speed controller 131, the direct axis current (eg, the first direct axis current i d1 Or the second direct current i d2 ) and the quadrature axis current (for example, the first quadrature axis current i q1 Or the second quadrature axis q1 ), to generate a direct axis voltage (eg, a first direct axis voltage v d1Or the second direct axis voltage v d2 ) and the quadrature axis voltage (for example, the first quadrature axis voltage v q1 Or the second quadrature axis voltage v q2 ). In addition, when the current sensing device 120 senses the three-phase current value i a 、i b 、i c When the current sensing device 120 outputs the three-phase current value i a 、i b 、i c Current detection value (e.g. i′ a , i′ b , i′ c ) is given to the three-phase to two-phase converter 135, and the three-phase to two-phase converter 135 converts the three-phase current value i a 、i b 、i c Current detection value (e.g. i′ a , i′ b , i′ c ) is converted into a direct-axis current (for example, the first direct-axis current i d1 Or the second direct current i d2 ) and the quadrature axis current (for example, the first quadrature axis current i q1 Or the second quadrature axis q1 ).

[0084] The modulation unit 133 is coupled to the current controller 132 and receives the direct-axis voltage (eg, the first direct-axis voltage v d1 Or the second direct axis voltage v d2 ) and the quadrature axis voltage (for example, the first quadrature axis voltage v q1 Or the second quadrature axis voltage v q2 ), and performs three-phase to two-phase conversion and pulse width modulation on the direct-axis voltage and the quadrature-axis voltage to generate a control command, and provides the control command to the inverter 151. Then, the inverter 151 can output the three-phase current value i according to the control command generated by the modulation unit 133. a 、i b 、 i c , to drive the motor 152 to operate.

[0085] The speed calculator 134 is coupled to the encoder 110, receives the motor position signal output by the encoder 110, and calculates the motor position signal to generate the corresponding rotational speed of the motor 152. The three-phase to two-phase converter 135 is coupled to the current sensing device 120, receives the three-phase current value i generated by the current sensing device 120, and generates the three-phase current value i a 、i b 、i c Current detection value (e.g. i′a , i′ b , i′ c ), and the three-phase current value i a 、i b 、 i c Current detection value (e.g. i′ a , i′ b , i′ c ) is converted into a two-phase direct-axis current (for example, the first direct-axis current i d1 Or the second direct current i d2 ) and the quadrature axis current (for example, the first quadrature axis current i q1 Or the second quadrature axis q1 ).

[0086] The estimation unit 136 is coupled to the current controller 132, the three-phase to two-phase converter 135, and the speed calculator 134. The estimation unit 136 can receive the rotational speed of the motor 152 provided by the speed calculator 134, the first direct-axis voltage, the first quadrature-axis voltage, the second direct-axis voltage, and the second quadrature-axis voltage provided by the current controller 132, and the first direct-axis current, the first quadrature-axis current, the second direct-axis current, and the second quadrature-axis current provided by the three-phase to two-phase converter 135.

[0087] The estimation unit 136 can determine whether the motor device 150 is maintained in the first steady state (for example, whether the speed of the motor 152 is maintained at the first rated speed for more than the first preset time and within the first error range), and if the estimation unit 136 determines that the motor device 150 is maintained in the first steady state (for example, the speed of the motor 152 is maintained at the first rated speed for more than the first preset time and within the first error range), the estimation unit 136 can store the first steady-state data corresponding to the first steady state (for example, the speed of the motor 152 is maintained at the first rated speed).

[0088] Furthermore, the estimation unit 136 may also determine whether the motor device 150 is maintained in the second steady-state (e.g., whether the speed of the motor 152 is maintained at the second rated speed for longer than a second predetermined time and within a second error range). If the estimation unit 136 determines that the motor device 150 is maintained in the second steady-state (e.g., the speed of the motor 152 is maintained at the second rated speed for longer than a second predetermined time and within a second error range), the estimation unit 136 may store second steady-state data corresponding to the second steady-state (e.g., the speed of the motor 152 is maintained at the second rated speed). Subsequently, the estimation unit 136 may obtain and store the equivalent magnetic flux based on the first steady-state data and the second steady-state data.

[0089] In some embodiments, the controller 130 may also repeatedly generate control commands to the inverter 151 to repeatedly drive the motor 152 to maintain the first steady state and the second steady state. The controller 130 may then generate control commands to the inverter 151 according to the three-phase current value i a 、i b 、i c The corresponding current detection value (e.g. i′ a , i′ b , i′ c ), update the first steady-state data and the second steady-state data, and recalculate and store the equivalent magnetic flux to generate multiple equivalent magnetic fluxes. In this embodiment, the calculation method of the above multiple equivalent magnetic fluxes can also be calculated using formula (6) or formula (7).

[0090] Next, the controller 130 calculates the magnetic flux variation based on the multiple equivalent magnetic fluxes. In some embodiments, the controller 130 may obtain the minimum and maximum values from the multiple equivalent magnetic fluxes. In other words, the controller 130 may compare the multiple equivalent magnetic fluxes to obtain the minimum and maximum values. The controller 130 may then calculate the magnetic flux variation based on the minimum and maximum values of the multiple equivalent magnetic fluxes.

[0091] In addition, in some embodiments, the controller 130 can obtain the initial value and the final value from the multiple equivalent magnetic fluxes. In other words, the controller 130 can sort the multiple equivalent magnetic fluxes to obtain the initial value and the final value. Thereafter, the controller 130 can calculate the flux change based on the initial value and the final value of the multiple equivalent magnetic fluxes. In this embodiment, the flux change can be calculated using formula (8), as shown below:

[0092]

[0093] in, is the magnetic flux change, is the initial value, is the final value.

[0094] After the controller 130 calculates the magnetic flux variation, it can issue a demagnetization warning based on the comparison between the magnetic flux variation and the demagnetization warning value to determine whether the motor 152 is demagnetized. In this embodiment, the demagnetization warning value can be adjusted by the user, for example, to 5% or 10%, but the present invention is not limited thereto.

[0095] For example, the controller 130 can compare the magnetic flux variation with a demagnetization warning value to determine whether the magnetic flux variation is greater than or equal to the demagnetization warning value (e.g., whether the magnetic flux variation is greater than 5% or 10%) and generate a comparison result. If the comparison result shows that the magnetic flux variation is less than the demagnetization warning value, the controller 130 does not issue a demagnetization warning. This determines that the motor 152 has not demagnetized, and the controller 130 can continue detecting the magnetic flux variation or terminate the detection operation. If the comparison result shows that the magnetic flux variation is greater than or equal to the demagnetization warning value, the controller 130 issues a demagnetization warning. The controller 130 can then determine that the motor 152 has demagnetized, perform a load reduction operation, and issue a demagnetization warning signal. This allows the user to be informed of the demagnetization of the motor 152 through the demagnetization warning signal, allowing them to repair or replace the motor 152.

[0096] In some other embodiments, the controller 130 includes a storage unit (not shown), so the controller 130 can store the calculated equivalent magnetic flux in the storage unit. The storage unit can be a memory, an electronically erasable read-only memory (EEPROM), etc.

[0097] As described in the above embodiments, an embodiment of the present invention provides a motor demagnetization detection method. Figure 4 FIG4 is a flow chart of a motor demagnetization detection method according to an embodiment of the present invention. The motor demagnetization detection method of this embodiment is used to detect a motor device. In step S402, the rotation angle of the motor device is measured by an encoder.

[0098] In step S404, the three-phase current values of the motor device are measured using a current sensing device. In step S406, the rotational speed of the motor device is calculated based on the rotation angle. In step S408, if the rotational speed determines that the motor device is maintaining a first steady state, the three-phase current values are received to obtain and store the first steady-state data.

[0099] In step S410, when the motor device is determined to be in the second steady state according to the rotation speed, the three-phase current values are received to obtain and store the second steady state data. In step S412, the equivalent magnetic flux is calculated and stored according to the first steady state data and the second steady state data.

[0100] In step S414, the motor device is repeatedly driven to maintain the first and second steady states, and the first and second steady-state data are updated based on the three-phase current values. The equivalent magnetic flux is recalculated and stored to generate a plurality of equivalent magnetic fluxes. In step S416, a magnetic flux change is calculated based on the plurality of equivalent magnetic fluxes. In step S418, a demagnetization warning is issued based on a comparison between the magnetic flux change and the demagnetization warning value.

[0101] In this embodiment, the first steady-state data may include a first direct-axis current, a first direct-axis voltage, a first quadrature-axis current, and a first quadrature-axis voltage, and the second steady-state data may include a second direct-axis current, a second direct-axis voltage, a second quadrature-axis current, and a second quadrature-axis voltage.

[0102] Furthermore, in some embodiments, step S416 may include obtaining a plurality of minimum and maximum values of equivalent magnetic fluxes, and calculating a magnetic flux variation based on the minimum and maximum values. In some embodiments, step S416 may include obtaining a plurality of initial and final values of equivalent magnetic fluxes, and calculating a magnetic flux variation based on the initial and final values. In some embodiments, step S418 may include issuing a demagnetization warning when the comparison result shows that the magnetic flux variation is greater than or equal to a demagnetization warning value, and not issuing a demagnetization warning when the comparison result shows that the magnetic flux variation is less than the demagnetization warning value.

[0103] It is worth noting that Figure 4 The order of the steps is for illustrative purposes only and is not intended to limit the order of the steps of the embodiments of the present invention. The order of the steps may be changed by the user as needed. Furthermore, additional steps may be added or fewer steps may be used without departing from the spirit and scope of the present invention.

[0104] Figure 5 The figure is a waveform diagram of the motor speed and quadrature axis current when the motor is driven by the motor demagnetization detection device according to one embodiment of the present invention. Figure 5 In the figure, curve S1 represents the speed of motor 152, curve S2 represents the quadrature-axis current, Speed1 represents the first rated speed, Speed2 represents the second rated speed, and T1-T5 represent time. In this embodiment, motor 152 is exemplified by the motor of an elevator system, and the elevator car is ascending from the first floor to the fifth floor, for example.

[0105] At time T1, when the elevator car begins moving from the 1st floor, the motor brake releases motor 152, causing the quadrature-axis current S1 to increase, causing motor 152 to begin rotating and accelerate. Then, at time T2, when the elevator car reaches the 2nd-3rd floor, the speed of motor 152 reaches and remains at the first rated speed, Speed 1. In other words, motor device 150 remains in the first steady-state. At this point, the controller 130 of the motor demagnetization detection device 100 can obtain and store the first steady-state data. Then, at time T3, after the elevator car reaches the 3rd floor, the current value of quadrature-axis current S1 decreases, causing motor 152 to begin decelerating. Then, at time T4, the speed of motor 152 reaches and remains at the second rated speed, Speed 2. In other words, motor device 150 remains in the second steady-state. At this point, the controller 130 of the motor demagnetization detection device 100 can obtain and store the second steady-state data. Finally, at time T5, when the elevator car reaches the 5th floor, the motor brake device will clamp the motor 152, causing the motor 152 to stop running and the speed of the motor 152 to drop to zero, so that the elevator car remains on the 5th floor.

[0106] In summary, the motor demagnetization detection method and device disclosed in the present invention receive three-phase current values to obtain and store first steady-state data when the motor device is determined to be maintained in a first steady-state based on the motor device's rotational speed. When the motor device is determined to be maintained in a second steady-state based on the motor device's rotational speed, receive three-phase current values to obtain and store second steady-state data. Equivalent magnetic flux is calculated and stored based on the first and second steady-state data. The motor device is repeatedly driven to maintain the first and second steady-states, and the first and second steady-state data are updated based on the three-phase current values. The equivalent magnetic flux is recalculated and stored to generate a plurality of equivalent magnetic fluxes. A magnetic flux change is calculated based on the equivalent magnetic flux. A demagnetization warning is then issued based on a comparison result of the magnetic flux change with a demagnetization warning value. In this way, the magnetic flux can be effectively estimated and the flux estimation error caused by the nonlinear characteristics of the integrated circuit can be reduced, thereby increasing the accuracy of detecting demagnetization phenomena. Motor parameters related to the motor (such as d-axis inductance) can be eliminated, thereby increasing the convenience and accuracy of detection.

[0107] Although the present invention is disclosed above with reference to the embodiments, they are not intended to limit the scope of the invention. Any person skilled in the art may make slight changes and modifications without departing from the concept and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A motor demagnetization detection method for detecting a motor device, wherein the motor demagnetization detection method comprises: Measuring a rotation angle of the motor device by an encoder; Measuring the three-phase current value of the motor device by a current sensing device; calculating a rotation speed of the motor device according to the rotation angle; When it is determined that the motor device maintains a first steady state according to the rotation speed, receiving the three-phase current value to obtain and store a first steady state data; When it is determined that the motor device maintains a second steady state according to the rotation speed, receiving the three-phase current value to obtain and store a second steady state data; Calculating and storing an equivalent magnetic flux according to the first steady-state data and the second steady-state data; repeatedly driving the motor device to maintain the first steady state and the second steady state, updating the first steady state data and the second steady state data according to the three-phase current value, and recalculating and storing the equivalent magnetic flux to generate a plurality of equivalent magnetic fluxes; Calculating a magnetic flux variation according to the multiple equivalent magnetic fluxes; and A demagnetization warning is issued according to a comparison result of the magnetic flux variation and a demagnetization warning value. 2 . The motor demagnetization detection method according to claim 1 , wherein a minimum value and a maximum value of the plurality of equivalent magnetic fluxes are obtained, and the magnetic flux variation is calculated according to the minimum value and the maximum value. 3 . The motor demagnetization detection method according to claim 1 , wherein an initial value and a final value of the plurality of equivalent magnetic fluxes are obtained, and the magnetic flux variation is calculated according to the initial value and the final value. 4 . The motor demagnetization detection method as claimed in claim 1 , wherein when the comparison result is that the magnetic flux variation is greater than or equal to the demagnetization warning value, the demagnetization warning is issued. 5 . The motor demagnetization detection method as claimed in claim 4 , wherein when the comparison result is that the magnetic flux variation is smaller than the demagnetization warning value, the demagnetization warning is not issued.

6. A motor demagnetization detection device for detecting a motor device, wherein the motor demagnetization detection device comprises: an encoder for measuring a rotation angle of the motor device; a current sensing device for measuring the three-phase current value of the motor device; a controller coupled to the encoder and the current sensing device; The controller calculates a rotation speed of the motor device according to the rotation angle; When the controller determines that the motor device is maintained in a first steady state according to the rotational speed, the controller receives the three-phase current value to obtain and store a first steady state data; When the controller determines that the motor device is maintained in a second steady state according to the rotational speed, the controller receives the three-phase current value to obtain and store a second steady state data; The controller calculates and stores an equivalent magnetic flux according to the first steady-state data and the second steady-state data; The motor device is repeatedly driven to maintain the first steady state and the second steady state, the controller updates the first steady state data and the second steady state data according to the three-phase current value, and recalculates and stores the equivalent magnetic flux to generate a plurality of equivalent magnetic fluxes; The controller calculates a magnetic flux variation according to the multiple equivalent magnetic fluxes, and issues a demagnetization warning according to a comparison result between the magnetic flux variation and a demagnetization warning value. 7 . The motor demagnetization detection device as claimed in claim 6 , wherein the controller obtains a minimum value and a maximum value of the plurality of equivalent magnetic fluxes, and the controller calculates the magnetic flux variation according to the minimum value and the maximum value. 8 . The motor demagnetization detection device as claimed in claim 6 , wherein the controller obtains an initial value and a final value of the plurality of equivalent magnetic fluxes, and the controller calculates the magnetic flux variation according to the initial value and the final value. 9 . The motor demagnetization detection device as claimed in claim 6 , wherein when the comparison result shows that the magnetic flux variation is greater than or equal to the demagnetization warning value, the controller issues the demagnetization warning. 10 . The motor demagnetization detection device as claimed in claim 9 , wherein when the comparison result shows that the magnetic flux variation is smaller than the demagnetization warning value, the controller does not issue the demagnetization warning.

11. The motor demagnetization detection device as described in claim 6, wherein the current sensing device includes two current sensors, and the two current sensors are respectively used to measure a first phase current and a second phase current of the three-phase current value, wherein the controller calculates a third phase current of the three-phase current value based on the first phase current and the second phase current. 12 . The motor demagnetization detection device as claimed in claim 6 , wherein the current sensing device comprises three current sensors, and the three current sensors respectively measure a first phase current, a second phase current, and a third phase current of the three-phase current.

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