A control method for preventing power loss of electric drive system

Abstract

The present invention relates to a control method for preventing power loss of an electric drive system, comprising a motor housing, a stator, a rotor and a resolver, wherein a rotor bracket is arranged between the motor housing and the motor shaft, the outer ring of the rotor bracket is fixed to the motor housing, and a gap is left between the inner ring of the rotor bracket and the shaft. The present invention processes the resolver signal in real time when the motor is running, and finally obtains a difference signal of large and small waves, and compares the difference signal with the resolver stator-rotor gap, the motor stator-rotor gap, the maximum eccentric gap of the rotor shaft system, and the difference between the large and small waves of the resolver output corresponding to when the gap between the rotor bracket and the shaft is zero, so that the eccentricity of the motor rotor during operation can be conveniently and accurately determined, and then a corresponding normal signal or alarm signal can be given; at the same time, after the bearing fails, the rotor bracket can replace the bearing to constrain the rotor, so that the electric drive system can continue to operate for at least 24 hours, greatly reducing the risk of sudden power loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric drive systems for electric vehicles, and more specifically, relates to a control method for preventing power loss in an electric drive system. Background Art

[0002] As a low-carbon economy becomes mainstream, electric vehicles are becoming the primary direction of automotive development. The motor, the primary power source for electric vehicles, consists of components such as the stator, shaft, end caps, and bearings. The motor bearings primarily provide static and dynamic support for the motor shaft and are a key component in ensuring efficient and stable operation. To effectively extend the motor's operating life, the bearings are typically configured with a fixed drive-end bearing and a free-floating non-drive-end bearing.

[0003] When installing tools directly on the rotating shaft or connecting the transmission through a coupling, it is easy to generate an eccentric reaction force on the rotating shaft due to the working state of the equipment. When the rotating shaft rotates at high speed, it is easy to cause damage to the bearing supporting the rotating shaft. In particular, the retaining frame in the bearing is easy to burn out under the combined effects of electrical corrosion, eccentricity, impact, and rapid acceleration and deceleration, causing all the bearing rollers to deviate to one side, so that the rotor is seriously eccentric, and the stator and rotor of the resolver and the stator and rotor of the motor will be swept; the resolver signal is lost and the insulation of the stator and rotor of the motor fails; ultimately, the electric vehicle loses power, causing a major safety hazard. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a control method for preventing power loss of an electric drive system, which can give an alarm signal in time when a motor bearing fails and keep the motor running to reduce risks.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] A control method for preventing power loss in an electric drive system includes a motor housing, a stator, a rotor, and a resolver. A rotor bracket is provided between the motor housing and the motor shaft, the outer ring of the rotor bracket is fixed to the motor housing, a gap is left between the inner ring of the rotor bracket and the shaft, and the gap between the resolver stator and rotor is set to δ1. When δ1 is 0, the corresponding value of the difference between the large and small waves output by the resolver is A1; the gap between the motor stator and rotor is set to δ2. When δ2 is 0, the corresponding value of the difference between the large and small waves output by the resolver is A2; the maximum eccentric gap of the rotor shaft system is set to δ3. When δ3 is 0, the corresponding value of the difference between the large and small waves output by the resolver is A3; the gap between the rotor bracket and the shaft is set to δ4. When δ4 is 0, the corresponding value of the difference between the large and small waves output by the resolver is A4; when the resolver is driving the motor normally, the motor controller collects the waveform signal of the resolver in real time. When the rotor is eccentric, the sin signal and cos signal of the resolver will show large and small waves; the motor controller processes the sin signal and cos signal respectively, and finally obtains the difference signal A0 of the large and small waves. When the value of A0 is in the range of 0 to A3, the motor controller sends a normal motor operation signal; when the value of A0 is between A3 and A4, the motor controller sends a warning signal: maintenance is required as soon as possible; when the value of A0 is greater than or equal to A4, the motor controller sends an alarm signal: maintenance is required and the operation can continue for a maximum of 24 hours.

[0007] As a preferred solution: the motor controller processes the sin signal and cos signal of the resolver respectively through a single-phase full-bridge rectifier circuit, an operational amplifier maximum and minimum value circuit, and an operational amplifier difference calculation circuit.

[0008] As a preferred solution: the operational amplifier maximum and minimum value circuit includes multiple unit modules, and each unit module includes an operational amplifier, a resistor and a diode.

[0009] As a preferred solution, the motor controller processes the sin signal and cos signal separately as follows: the sine and cosine waveform signals fed back by the resolver first pass through a single-phase full-bridge rectifier circuit to obtain waveform signals with all positive values; then, the two sine and cosine signals after taking the absolute values ​​pass through an operational amplifier maximum and minimum value circuit to obtain the overall maximum and minimum values ​​of the sine and cosine signals; finally, the operational amplifier difference calculation circuit is input to obtain the final resolver difference, which is output to a subsequent control unit.

[0010] As a preferred solution: the gap δ1 between the resolver stator and rotor is greater than the gap δ4 between the rotor bracket and the rotating shaft; the gap δ2 between the motor stator and rotor is greater than the gap δ4 between the rotor bracket and the rotating shaft; the maximum eccentric gap δ3 of the rotor shaft system is less than the gap δ4 between the rotor bracket and the rotating shaft.

[0011] As a preferred solution, the gap δ1 between the stator and rotor of the resolver is 0.5-0.8 mm; the gap δ2 between the stator and rotor of the motor is 0.8-1 mm; and the maximum eccentric gap δ3 of the rotor shaft system is 0.06-0.13 mm.

[0012] As a preferred solution: the rotor bracket is made of metal, and includes an inner limit ring, a support plate and an outer limit ring. The outer limit ring is interference fit with the inner wall of the motor casing. One end of the support plate is fixed to the inner wall of the outer limit ring, and the other end is fixed to the outer wall of the inner limit ring. The inner limit ring is sleeved outside the rotating shaft and leaves a gap with the outer wall of the rotating shaft.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention processes the resolver signal when the motor is running, and finally obtains a difference signal between the large and small waves. The difference signal is compared with the resolver stator-rotor gap, the motor stator-rotor gap, the maximum eccentric gap of the rotor shaft system, and the difference between the large and small waves of the resolver output corresponding to when the gap between the rotor bracket and the rotating shaft is zero. This can conveniently and accurately determine the eccentricity of the motor rotor during operation, and then give a corresponding normal signal or alarm signal. At the same time, after the bearing fails, the rotor bracket can replace the bearing to constrain the rotor, so that the electric drive system can continue to operate for at least 24 hours, greatly reducing the risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation on this application.

[0016] Figure 1 Schematic diagram of resolver signal processing according to the present invention. DETAILED DESCRIPTION

[0017] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0018] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0019] In addition, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise explicitly specified.

[0021] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0022] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0024] like Figure 1The control method for preventing power loss of an electric drive system is shown, including a motor housing, a stator, a rotor and a resolver, wherein both ends of the rotor are rotatably connected to the motor housing through bearings. Under normal operation, the radial clearance of the bearings is small, which can support the stable operation of the rotor. When the bearings fail, the entire rotor will be severely eccentric; a rotor bracket is arranged between the motor housing and the motor shaft, the outer ring of the rotor bracket is fixed to the motor housing, and a gap is left between the inner ring of the rotor bracket and the rotating shaft. The rotor bracket is made of metal, and includes an inner limit ring, a support plate and an outer limit ring. The outer limit ring is interference fit with the inner wall of the motor housing, one end of the support plate is fixed to the inner wall of the outer limit ring, and the other end is fixed to the outer wall of the inner limit ring. The inner limit ring is sleeved outside the rotating shaft and a gap is left with the outer wall of the rotating shaft.

[0025] The gap between the stator and rotor of the resolver is set to δ1. When δ1 is 0, the corresponding value of the difference between the large and small waves of the resolver output is A1. The gap between the stator and rotor of the motor is set to δ2. When δ2 is 0, the corresponding value of the difference between the large and small waves of the resolver output is A2. The gap between the stator and rotor of the motor is the designed air gap reserved in the design of the drive motor. The maximum eccentric gap of the rotor shaft system is set to δ3. When δ3 is 0, the corresponding value of the difference between the large and small waves of the resolver output is A3. The maximum eccentric gap of the rotor shaft system is due to the machining error of each part, which causes a deviation between the actual rotor position and the theoretical position during operation. This deviation is calculated based on the radial dimension chain to obtain the maximum eccentricity within the design range. The gap between the rotor bracket and the rotating shaft is set to δ4. When δ4 is 0, the corresponding value of the difference between the large and small waves of the resolver output is A4.

[0026] During the normal operation of the drive motor, the resolver obtains the position and speed of the motor rotor based on the sinusoidal voltage signal. When the rotor is eccentric, the sin signal and cos signal of the resolver will show large and small waves. The machine controller collects the waveform signal of the resolver in real time, and processes the sin signal and cos signal respectively, and finally obtains the difference signal A0 between the large and small waves. When the value of A0 is in the range of 0 to A3, the motor controller sends a normal motor operation signal; when the value of A0 is between A3 and A4, the motor controller sends a warning signal: maintenance is required as soon as possible; when the value of A0 is greater than or equal to A4, the motor controller sends an alarm signal: maintenance is required and the operation can continue for a maximum of 24 hours.

[0027] The motor controller processes the resolver's sin and cos signals through a single-phase full-bridge rectifier circuit, an op amp maximum and minimum value circuit, and an op amp difference circuit. The op amp maximum and minimum value circuit includes multiple unit modules, each of which includes an op amp, a resistor, and a diode.

[0028] The motor controller processes the sin signal and cos signal respectively as follows: the sine and cosine waveform signals fed back by the resolver first pass through a single-phase full-bridge rectifier circuit to obtain waveform signals with all positive values; then, the two sine and cosine signals after taking the absolute values ​​are passed through an operational amplifier maximum and minimum value circuit to obtain the overall maximum and minimum values ​​of the sine and cosine signals; finally, the operational amplifier difference calculation circuit is input to obtain the final resolver difference, which is output to the subsequent control unit.

[0029] The gap δ1 between the resolver stator and rotor is greater than the gap δ4 between the rotor bracket and the rotating shaft; the gap δ2 between the motor stator and rotor is greater than the gap δ4 between the rotor bracket and the rotating shaft; and the maximum eccentric gap δ3 of the rotor shaft system is less than the gap δ4 between the rotor bracket and the rotating shaft. Typically, the gap δ1 between the resolver stator and rotor is 0.5 to 0.8 mm; the gap δ2 between the motor stator and rotor is 0.8 to 1 mm; and the maximum eccentric gap δ3 of the rotor shaft system is 0.06 to 0.13 mm.

[0030] The present invention processes the resolver signal when the motor is running, and finally obtains a difference signal between the large and small waves. The difference signal is compared with the resolver stator-rotor gap, the motor stator-rotor gap, the maximum eccentric gap of the rotor shaft system, and the difference between the large and small waves of the resolver output corresponding to when the gap between the rotor bracket and the rotating shaft is zero. This can conveniently and accurately determine the eccentricity of the motor rotor during operation, and then give a corresponding normal signal or alarm signal. At the same time, after the bearing fails, the rotor bracket can replace the bearing to constrain the rotor, so that the electric drive system can continue to operate for at least 24 hours, greatly reducing the risk.

[0031] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0032] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are illustrative and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A control method for preventing power loss in an electric drive system, characterized by: The invention comprises a motor housing, a stator, a rotor and a resolver, wherein a rotor bracket is arranged between the motor housing and the motor shaft, the outer ring of the rotor bracket is fixed to the motor housing, a gap is left between the inner ring of the rotor bracket and the shaft, and the gap between the resolver stator and rotor is set to δ1, when δ1 is 0, the corresponding value of the large and small wave difference of the resolver output is A1; the gap between the motor stator and rotor is set to δ2, when δ2 is 0, the corresponding value of the large and small wave difference of the resolver output is A2; the maximum eccentric gap of the rotor shaft system is set to δ3, when δ3 is 0, the corresponding value of the large and small wave difference of the resolver output is A3; the gap between the rotor bracket and the shaft is set to δ4, when δ4 is 0, the resolver The corresponding value of the output difference between the large and small waves is A4; when the resolver is driving the motor normally, the motor controller collects the waveform signal of the resolver in real time. When the rotor is eccentric, the sin signal and cos signal of the resolver will show large and small waves; the motor controller processes the sin signal and cos signal respectively, and finally obtains the difference signal A0 between the large and small waves. When the value of A0 is in the range of 0 to A3, the motor controller sends a normal motor operation signal; when the value of A0 is between A3 and A4, the motor controller sends a warning signal: maintenance is required as soon as possible; when the value of A0 is greater than or equal to A4, the motor controller sends an alarm signal: maintenance is required and the maximum operation can be continued for 24 hours.

2. The control method for preventing power loss of an electric drive system according to claim 1, characterized in that: The motor controller processes the sin signal and cos signal of the resolver respectively through a single-phase full-bridge rectifier circuit, an operational amplifier maximum and minimum value circuit, and an operational amplifier difference calculation circuit.

3. The control method for preventing power loss of an electric drive system according to claim 2, characterized in that: The operational amplifier maximum and minimum value circuit includes a plurality of unit modules, and each unit module includes an operational amplifier, a resistor and a diode.

4. The control method for preventing power loss of an electric drive system according to claim 2, characterized in that: The motor controller processes the sin signal and cos signal respectively as follows: the sine and cosine waveform signals fed back by the resolver first pass through a single-phase full-bridge rectifier circuit to obtain waveform signals with all positive values; then, the two sine and cosine signals after taking the absolute values ​​are passed through an operational amplifier maximum and minimum value circuit to obtain the overall maximum and minimum values ​​of the sine and cosine signals; finally, the operational amplifier difference calculation circuit is input to obtain the final resolver difference, which is output to the subsequent control unit.

5. The control method for preventing power loss of an electric drive system according to claim 1, characterized in that: The gap δ1 between the stator and rotor of the resolver is greater than the gap δ4 between the rotor bracket and the rotating shaft; the gap δ2 between the stator and rotor of the motor is greater than the gap δ4 between the rotor bracket and the rotating shaft; the maximum eccentric gap δ3 of the rotor shaft system is less than the gap δ4 between the rotor bracket and the rotating shaft.

6. The control method for preventing power loss of an electric drive system according to claim 1, characterized in that: The gap δ1 between the stator and rotor of the resolver is 0.5-0.8 mm; the gap δ2 between the stator and rotor of the motor is 0.8-1 mm; The maximum eccentric clearance δ3 of the rotor shaft system is 0.06~0.13mm.

7. The control method for preventing power loss of an electric drive system according to claim 1, characterized in that: The rotor bracket is made of metal and includes an inner limit ring, a support plate and an outer limit ring. The outer limit ring is interference fit with the inner wall of the motor casing. One end of the support plate is fixed to the inner wall of the outer limit ring, and the other end is fixed to the outer wall of the inner limit ring. The inner limit ring is sleeved outside the rotating shaft and leaves a gap with the outer wall of the rotating shaft.

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