Electric motor with combination winding connection for traction of electric vehicle

Abstract

The present invention relates to an electric motor with combination winding connection for traction of electric vehicle. The electric motor comprises a stator having a plurality of phase windings, a rotor and a control device. The present invention also relates to a method for operating an electric motor in an electric vehicle. The windings are configured to selectively operate in a star connection and in a delta-connection based on speed of the vehicle.

Description

ELECTRIC MOTOR WITH COMBINATION WINDING CONNECTION FOR TRACTION OF ELECTRIC VEHICLEFIELD OF INVENTION

[0001] The present disclosure generally relates to the automobile industry, and specifically relates to improving traction application of an electric motor having a star and delta combination winding connection in an electric vehicle.BACKGROUND OF INVENTION

[0002] The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.

[0003] Electric vehicles have gained widespread popularity in recent years, with electric two- wheelers playing a significant role in the rapid growth of this segment within the automobile industry. The numerous advantages associated with electric two-wheelers have made them a preferred choice for many consumers. These benefits include low running costs, ease of maintenance, compact storage space, and reduced noise levels. Furthermore, electric two- wheelers are environmentally friendly as they produce no carbon emissions during operation, aligning with global efforts to reduce environmental impact and combat climate change.

[0004] The increasing adoption of electric wheelers has driven the demand for advancements that enhance the performance, efficiency, and user experience of these vehicles. One of the critical areas requiring improvement is the design and construction of the electric motor, which is the primary power source for these vehicles. The performance of the motor significantly affects the overall efficiency of the vehicle, including torque generation, power output, and energy consumption, thereby, influencing both the range of the vehicle and its ability to provide adequate traction for various driving conditions.

[0005] In electric two-wheelers, the winding connection of the electric motor plays a crucial role in determining the overall efficiency and power delivery. The winding configurationimpacts the torque generation, thermal performance, and energy conversion efficiency. The efficiency of the motor directly influences the overall efficiency of the electric two -wheeler, including factors such as power consumption, range per charge, and ride comfort.

[0006] However, the winding connection in the electric motor of electric two-wheelers has been a challenging aspect, as it needs to balance multiple performance parameters such as high- power density, optimized controllability, and efficient torque generation. Current motor winding designs often fall short of achieving optimal performance, limiting the potential efficiency and controllability of the electric vehicle.

[0007] Therefore, there exists a clear need for the development of an innovative winding configuration for electric motors used in electric vehicles. Such a configuration would enhance the overall performance of the vehicle, improving efficiency, power density, and controllability. An optimized winding connection would provide better torque output, increased range, and superior handling, ensuring that electric two-wheelers can meet the demands of modem consumers seeking higher performance and longer-lasting, environmentally conscious transportation options.OBJECTIVE OF INVENTION

[0008] An object of the invention is to provide an electric motor with a Star-Delta combination winding connection for electric vehicles, which effectively increases the performance efficiency by reducing motor losses, thereby, improving the overall efficiency of the vehicle.

[0009] Another objective of the invention is to optimize the range of controllability achieved by electric vehicles, based on the enhanced torque performance and smooth speed transition provided by the electric motor, which operates efficiently across a broad range of speeds.

[0010] Yet another objective of the invention is to increase the power density of the electric vehicle by incorporating the innovative winding connection of the electric motor, which minimizes copper losses and improves overall efficiency, thereby enabling higher power output with reduced energy consumption.

[0011] Still another objective of the invention is to enable smooth and seamless transition between the star and delta winding configurations, eliminating the need for complex controlsystems by utilizing semiconductor devices as switches, thereby ensuring a smooth operation across varying speed ranges.SUMMARY OF INVENTION

[0012] The summary is provided to introduce aspects related to an electric motor for an electric vehicle and a method for operating an electric motor in an electric vehicle, and the aspects are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[0013] In one aspect, the present invention relates to an electric motor for an electric vehicle, comprising a stator having a plurality of phase windings, a rotor, a control device configured to regulate the supply of electrical current to the windings. The windings are configured to selectively operate in a star connection at low speeds and in a delta connection at high speeds.

[0014] According to an embodiment of the present invention, the stator windings are configured in multiple phases to form at least a star connection and a delta connection, each of which is selectively operated based on the speed of the electric vehicle.

[0015] In yet another embodiment of the present invention, the electric motor further comprises a switching mechanism configured to switch the stator windings between the star and delta connections.

[0016] According to an embodiment of the present invention, the switching mechanism comprises one or more semiconductor switches positioned in the stator winding circuit, wherein the switches are configured to change the connection from star to delta and vice-versa.

[0017] In yet another embodiment of the present invention, the semiconductor switches are configured to handle the current requirements for both star and delta winding operations.

[0018] According to an embodiment of the present invention, the control device comprises microprocessors configured to control the operation of the switching mechanism and to regulate the star and delta connection transitions based on the speed of the vehicle.

[0019] In yet another embodiment of the present invention, the stator windings are wound in a manner to form a wye-delta hybrid configuration for dynamic switching between star and delta connections.

[0020] According to an embodiment of the present invention, the star connection operates with a phase voltage 1.73 times the line voltage, and the delta connection operates with a phase voltage equal to the line voltage.

[0021] In another embodiment, the present invention relates to method for operating an electric motor in an electric vehicle, wherein the electric motor comprises a stator having a plurality of phase windings, a rotor, and a control device. The method comprises controlling flow of electrical current to the windings by the control device, operating the windings in a star connection at low speeds, and operating the windings in a delta connection at high speeds.

[0022] According to an embodiment of the present invention, the stator windings are configured in multiple phases to form at least a star connection and a delta connection, each of which is selectively operated based on the speed of the electric vehicle.

[0023] In yet another embodiment of the present invention, a switching mechanism is configured to switch the stator windings between the star and delta connections.

[0024] According to an embodiment of the present invention, the switching mechanism comprises one or more semiconductor switches positioned in the stator winding circuit, wherein the switches are configured to change the connection from star to delta and vice-versa.

[0025] In yet another embodiment of the present invention, the semiconductor switches are configured to handle the current requirements for both star and delta winding operations.

[0026] According to an embodiment of the present invention, the control device comprises microprocessors configured to control the operation of the switching mechanism and to regulate the star and delta connection transitions based on the speed of the vehicle.

[0027] In yet another embodiment of the present invention, the stator windings are wound in a manner to form a wye-delta hybrid configuration for dynamic switching between star and delta connections.

[0028] According to an embodiment of the present invention, the star connection operates with a phase voltage 1.73 times the line voltage, and the delta connection operates with a phase voltage equal to the line voltage.

[0029] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example, the principles of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings constitute a part of the description and are used to provide further understanding of the present invention. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0031] Fig. 1 illustrates different state of the art winding configurations in an electric motors;

[0032] Fig. 2 illustrates a graphical representation of the efficiency zone of star and delta winding configuration in the electric motor;

[0033] Fig. 3 illustrates a circuit diagram of a winding connections of the electric motor of the electric vehicle, in accordance with an embodiment of the present invention;

[0034] Fig. 4 illustrates a graphical representation of performance of the winding connection of the electric motor of the electric vehicle, in accordance with an embodiment of the present invention; and

[0035] Fig. 5 illustrates another graphical representation of performance of the winding connection of the electric motor of the electric vehicle, in accordance with an embodiment of the present invention.DESCRIPTION OF THE INVENTION

[0036] The description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. Each embodiment described in this invention is provided merely as an example or illustration of the present invention, and should not necessarily be construed as preferred or advantageous overother embodiments. The description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

[0037] The present invention relates to an electric motor with an innovative winding connection configuration for electric vehicles. In an embodiment, the electrical vehicle is any one of two-wheeler electric vehicle or four-wheeler electric vehicles. The invention aims to optimize the performance of electric motors by providing high torque at low speeds, expanded speed range, reduced motor losses, and improved energy efficiency. This is achieved through the use of a combination of star and delta winding connections that can dynamically switch based on the speed range of the vehicle.

[0038] Electric automobiles, especially two-wheeler vehicles, have been growing in popularity and demand due to the several benefits and advantages offered by such vehicles. However, optimization of performance of two-wheeler vehicles has been a persistent issue due to the traction application of the electric motor of the electric vehicles. The electric motor in the electric vehicles is the primary source that delivers torque to drive the axles of the electric vehicle and thus, provide propulsion for delivering the power needed to drive the wheels. The electric motor of the electric vehicle is required to operate at high efficiency and with high power density, and thus, it is an important element in the arrangement of the drive train of the electric vehicles.

[0039] Permanent magnet synchronous motors (PMSMs) are becoming increasingly popular in a variety of applications due to their high efficiency, power density, and controllability. Considering the advantages, the PMSMs can be incorporated in the electric vehicle to provide the necessary torque and power to drive the electric vehicle. Moreover, the winding connections in the PMSMs can be connected in either star or delta configurations, each with its own technical benefits.

[0040] Fig. 1 illustrates different winding configurations in an electric motor, in accordance with general prior art. Specifically, the figure depicts star and delta winding connections, which is known from the general prior art.

[0041] Fig. 1 depicts a star connection of the winding in the electric motor, wherein the ends of each phase winding are connected together at a neutral point. This creates a neutral line that can be used to provide a return path for the current and to suppress common-mode noise. Thestar-connected PMSMs have a lower line voltage than delta-connected PMSMs, but they have a higher phase current. This can make them more susceptible to overheating, especially at high speeds.

[0042] Star-connected PMSMs are generally more efficient than delta-connected PMSMs at low speeds, but their efficiency can drop off at higher speeds. In a star connection, the ends of each phase winding are connected together at a neutral point. This creates a neutral line that can be used to provide a return path for the current and to suppress common-mode noise.

[0043] Star-connected PMSMs have a lower line voltage than delta-connected PMSMs, but they have a higher phase current. This can make them more susceptible to overheating, especially at high speeds. Star-connected PMSMs are generally more efficient than delta- connected PMSMs at low speeds, but their efficiency can drop off at higher speeds.

[0044] Fig. 1 also depicts a delta connection of the winding in the electric motor, wherein the ends of each phase winding are connected to the beginning of the next phase winding. This creates a closed loop with no neutral point. Delta-connected PMSMs have a higher line voltage than star-connected PMSMs, but they have a lower phase current. This can make them more efficient at high speeds. Delta-connected PMSMs are generally less efficient than star- connected PMSMs at low speeds, but their efficiency can improve at higher speeds.

[0045] Fig. 2 illustrates a graphical representation of the efficiency zone of star and delta winding configuration in the electric motor. The best connection for PMSMs will depend on their specific application. If there is a need for high efficiency at low speeds, a star connection in the winding provides an optimum solution. On the contrary, if there is a requirement of high efficiency at high speeds, a delta connection in the winding is an alternative solution. While opting for a winding connection, it is essential to consider other factors as well, such as the available voltage and current, the size and weight of the motor, and the cost.

[0046] In the current embodiment, the electric motor is a Permanent Magnet Synchronous Motor (PMSM), that has become increasingly popular for electric vehicles due to its high efficiency, power density, and controllability. The PMSM is capable of operating with different winding connection configurations, specifically star and delta configurations, each offering distinct benefits depending on the operational speed of the motor.

[0047] Thus, the present invention provides an electric motor for an electric vehicle having a winding connection that is a combination of star-delta connection. In the present invention, the electric motor can be operated with star connections in low-speed areas and can be operated with delta connections in high-speed regions. The present invention provides high torques at low speeds, and the speed range also increased. Further, the present invention ensures reduction in Copper losses, as the said losses account for the largest proportion of the motor losses. Furthermore, the present invention also achieves an improvement of resistance, that leads to increase the efficiency characteristics and broadens the high efficiency area in the low and high speeds, in addition to the operating characteristics.

[0048] The electric motor of the present invention comprises a stator having a plurality of phase windings; a rotor; and a control device configured to regulate the supply of electrical current to the windings. The windings are configured to selectively operate in a star connection at low speeds and in a delta connection at high speeds.

[0049] Fig. 3 illustrates a circuit diagram 300 of a winding connection of the electric motor of the electric vehicle, in accordance with an embodiment of the present invention. Specifically, Fig. 3 shows the circuit diagram of the wye-delta winding connection 302 of the electric motor. In an embodiment, the stator windings 302 are configured in multiple phases to form at least a star connection and a delta connection, each of which is selectively operated based on the speed of the electric vehicle. In other words, the stator windings 302 are wound in a manner to form a wye-delta hybrid configuration for dynamic switching between star and delta connections. Thus, the stator windings 302 are divided into two groups: one group for the star connection and another group for the delta connection.

[0050] The electric motor in this invention is incorporated with a wye-delta switching circuit that includes semiconductor devices as switches 304, 306. Specifically, the electric motor further comprises a switching mechanism configured to switch the stator windings between the star and delta connections. The switching mechanism comprises one or more semiconductor switches 304, 306 positioned in the stator winding circuit, wherein the switches are configured to change the connection from star to delta and vice-versa. The semiconductor devices as switches 304, 306 provides smooth transitions between the star and delta configurations, eliminating the need for complex control algorithms. This improves the controllability of the vehicle, ensuring a smooth and responsive driving experience.

[0051] Fig. 3 also depicts that the circuit includes two groups of switches 304, 306 on the stator winding side. The two groups are divided into switches 304 for the star connection, and switches 306 for the delta connection. The semiconductor switches 304, 306 are configured to handle the current requirements for both star and delta winding operations. These semiconductor switches 304, 306 allow for a seamless transition between the star and delta winding configurations without the need for complex control algorithms. The speed transition is smooth, ensuring continuous and optimized performance.

[0052] In an embodiment, a control device 308 may be provided comprises a plurality of microprocessors configured to control the operation of the switching mechanism and to regulate the star and delta connection transitions based on the speed of the vehicle. In an embodiment, the control device 308 may be coupled to the vehicle management system and may be configured to receive the vehicle parameters including speed, torque, acceleration etc. The control device 308 is connected with the semiconductor switches to switch the windings between the star and delta connections. Specifically, separate microprocessors are in connection with the semiconductor switches to switch the windings between the star and delta connections based on the speed of the vehicle. This enables smooth speed transition between star and delta configurations, thereby, providing seamless operation across different speed ranges.

[0053] In other embodiment, the present invention relates a method for operating the electric motor in the electric vehicle. The method comprise controlling flow of electrical current to the windings by the control device, operating the windings in a star connection at low speeds, and operating the windings in a delta connection at high speeds.

[0054] At low speeds of the electric vehicle, the electric motor operates with the star winding connection. During the Star connection, the difference between phase voltages and line voltages is 1.73 times. The electric motor switches the connection when the electric vehicle increases the speed, specifically in a high-speed range. The star configuration provides high torque and efficiency at low speeds, making it ideal for scenarios where the vehicle needs to operate at low speeds while maintaining high performance, such as during city commuting or stop-and-go traffic.

[0055] At high speeds, the motor switches to the delta connection mode. The characteristic of the delta connection is that the phase voltage and the line voltage are the same. The deltaconfiguration allows the motor to operate with a higher line voltage, providing higher speed range and efficiency at higher speeds. This transition improves the overall efficiency of the motor by reducing copper losses and optimizing the performance of the motor across a broader range of speeds.

[0056] Fig. 4 illustrates a graphical representation of performance of the winding connection of the electric motor of the electric vehicle, in accordance with an embodiment of the present invention. The graphical representation depicts the speed, torque characteristic, and voltage characteristic curve of the electric motor with star winding connection and delta winding connection.

[0057] As shown in the performance graph of Fig. 4, the electric motor with the combined star-delta winding configuration provides high torque and efficiency in the low- speed range (star configuration) and improved speed range and efficiency at high speeds (delta configuration). The ability of the electric motor to operate with different winding configurations based on the speed of the vehicle ensures that both low- speed torque and highspeed efficiency are optimized.

[0058] The invention reduces copper losses, which constitute the largest proportion of motor losses, by optimizing the winding configuration. By switching to the delta connection at higher speeds, the motor operates more efficiently, reducing energy consumption and increasing overall performance.

[0059] Fig. 5 illustrates a graphical representation of performance of the winding connection of the electric motor of the electric vehicle, in accordance with an embodiment of the present invention. As shown in the figure, the star configuration at low speeds provides high torque, which is essential for applications requiring strong initial acceleration or climbing ability. The transition to the delta configuration at higher speeds allows the motor to operate efficiently over a broader speed range, providing higher top speeds without sacrificing performance. The combination of the star-delta configuration in the electric motor operates in high efficiency in low speed high torque by star configuration and high-speed low torque zone by delta configuration. This is particularly beneficial in applications where high torque is required at low speeds, such as in electric vehicles.

[0060] The combination of star and delta configurations in the electric motor expands the high-efficiency zone, ensuring that the motor operates efficiently at both low and high speeds.The improvement in resistance and the reduction in copper losses lead to enhanced efficiency across a broader operational speed range.

[0061] By minimizing copper losses, the motor operates more efficiently, thereby reducing energy consumption and improving the overall range of the electric vehicle. The improved resistance and efficiency characteristics ensure that the motor operates in the optimal efficiency zone, both at low and high speeds. Further, the semiconductor switches ensures a seamless transition between star and delta configurations, providing smooth and reliable operation.

[0062] The electric motor proposed in the present invention hence helps in effectively increasing the efficiency of the electric vehicle, reducing the motor losses of electric twowheeler vehicles by replacing conventional winding connection with a Star-Delta combination winding connection, which results in a high-performance efficiency, increased power density and optimized controllability of the electric vehicles.

[0063] In summary, the present invention provides an innovative approach to optimizing the performance of electric motors in two-wheeler electric vehicles. By utilizing a combined stardelta winding connection, the motor can deliver high efficiency, increased power density, and optimized controllability across a wide range of speeds. The smooth transition between star and delta configurations, facilitated by semiconductor switches, ensures that the electric motor can adapt to varying driving conditions, ultimately improving the efficiency and performance of electric vehicles.

[0064] In view of the present disclosure, which describes the present invention, all changes, modifications and, variations within the meaning and range of equivalency are considered within the scope of the invention. It is to be understood that the aspects and embodiment of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiment may be combined together to form a further embodiment of the disclosure.

Claims

AMENDED CLAIMS received by the International Bureau on 09 September 2025 (09.09.2025)We claim:

1. An electric motor for an electric vehicle, comprising: a stator having a plurality of phase windings; a rotor; a control device configured to regulate the supply of electrical current to the windings, wherein the windings are configured to selectively operate in a star connection at low speeds and in a delta connection at high speeds; and at least one switching mechanism configured to switch the stator windings between the star and delta connections, wherein the switching mechanism comprises one or more semiconductor switches positioned in stator winding circuit, wherein the switches are configured to selectively reconfigure the windings between star and delta connections, and provide smooth transitions between configurations, and wherein the control device is coupled to a vehicle management system and switches configurations based on vehicle-level parameters.

2. The electric motor as claimed in claim 1, wherein the stator windings are configured in multiple phases to form at least a star connection and a delta connection, each of which is selectively operated based on the speed of the electric vehicle.

3. The electric motor as claimed in claim 1, wherein the semiconductor switches are configured to handle the current requirements for both star and delta winding operations.

4. The electric motor as claimed in claim 1, wherein the control device comprises microprocessors configured to control the operation of the switching mechanism and to regulate the star and delta connection transitions based on speed of the vehicle.

5. The electric motor as claimed in claim 1, wherein the stator windings are wound in a manner to form a wye-delta hybrid configuration for dynamic switching between star and delta connections.

6. The electric motor as claimed in claim 1, wherein the star connection operates with a phase voltage 1.73 times the line voltage, and the delta connection operates with a phase voltage equal to the line voltage.

7. The electric motor as claimed in claim 1 , wherein the control device is configured to receive information on the speed of the vehicle.

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