DESC:PROTECTION CIRCUIT FOR MOTOR DRIVE
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202221056421 filed on 30/09/2022, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to a powertrain unit of an electric vehicle. The present disclosure particularly relates to a powertrain unit of an electric vehicle with a protection unit to protect motor drive.
BACKGROUND
Recently, there has been a rapid development in electric vehicles because of their ability to resolve pollution-related problems and serve as a clean mode of transportation. Generally, electric vehicles include a battery pack, power pack, and/or combination of electric cells for storing electricity required for the propulsion of the vehicles. The electrical power stored in the battery pack of the electric vehicle is supplied to the traction motor for moving the electric vehicle forming the powertrain of the electric vehicle.
The powertrain includes a pre-charging circuit that serves to prevent an over-current generated by an inrush current inputted to an inverter of the vehicle and also prevent dielectric breakdown of elements. Pre-charge circuits are often used in electric vehicles (EVs) such as battery management systems, onboard chargers, and in industrial applications such as power supplies and power distribution units. In the electric vehicles, controllers with high capacitive loads regulate traction motors. The high voltage positive and negative contactors are used in this system to act as an emergency disconnect when the motor regulator fails. Without a pre-charge circuit, welding can occur within the contactor as it closes and there could be a brief arc resulting in pitting.
In a high voltage system of the electrical vehicle, a pre-charge circuit and a DC link capacitor in parallel with a load (for example, traction inverter) is present. In a pre-charge state, the pre-charge circuit charges the DC link capacitor nearly the same voltage as the voltage source. This charging of the DC link capacitor allows the system to operate normally by eliminating high inrush current.
At present, a regenerative energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. The power pack stores the regenerative energy generated by a regenerative energy recovery mechanism. However, when the regenerative energy is high, the regenerative energy is not supplied to the power pack, thus, the electrical vehicle has to rely on mechanical braking to reduce speed rather than regenerative braking. Such situation is highly energy inefficient as the lot of energy is wasted
Thus, there exists a need for a system to efficiently capture and divide regenerative energy during the regenerative braking and overcomes one or more problems associated as set forth above.
SUMMARY
An object of the present disclosure is to provide a powertrain unit of an electric vehicle with a protection unit.
Another object of the present disclosure is to provide a protection unit for a powertrain unit of an electric vehicle.
In accordance with an embodiment of the present disclosure, there is provided powertrain unit of an electric vehicle. The powertrain unit comprises a motor drive, a power pack, and a protection unit. The motor drive comprises a motor and an inverter. The protection unit is configured to allow a forward flow of current in a driving mode and a selective reverse flow of current in a regenerative mode.
The present disclosure provides the powertrain unit of an electric vehicle. The powertrain unit of the electric vehicle, as disclosed in the present disclosure, is advantageous in terms of protecting a motor drive and the power pack from a high back emf generated during the regenerative braking. Moreover, the powertrain unit, as disclosed by the present disclosure is advantageous in terms of preventing motor drive failure and power pack failure by controlling excessive current generated during the regenerative mode. Moreover, the powertrain unit, as disclosed by the present disclosure is advantageous in terms of efficiently utilizing regenerative braking energy for efficient regenerative braking of the vehicle without relying on the mechanical braking.
In accordance with another embodiment of the present disclosure, there is provided a protection unit for a powertrain unit of an electric vehicle. The protection unit comprises a pre-charge circuit comprising a plurality of pre-charge switches and a pre-charge resistor, a bypass circuit comprising a bypass resistor and a bypass switch, and a microcontroller configured to control flow of current through the pre-charge circuit and the bypass circuit.
Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
Figure 1 illustrates a block diagram of a powertrain unit of an electric vehicle, in accordance with an aspect of the present disclosure.
Figure 2 illustrates a circuit diagram of a powertrain unit of an electric vehicle, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of powertrain unit of an electric vehicle and is not intended to represent the only forms that may be developed or utilized. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, or system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings which are shown by way of illustration-specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms ‘electric vehicle’, ‘EV’, and ‘EVs’ are used interchangeably and refer to any vehicle having stored electrical energy, including the vehicle capable of being charged from an external electrical power source. This may include vehicles having batteries that are exclusively charged from an external power source, as well as hybrid vehicles which may include batteries capable of being at least partially recharged via an external power source. Additionally, it is to be understood that the ‘electric vehicle’ as used herein includes electric two-wheelers, electric three-wheelers, electric four-wheelers, electric pickup trucks, electric trucks, and so forth.
As used herein, the terms “power source” “battery pack”, “battery”, and “power pack” are used interchangeably and refer to multiple individual battery cells connected to provide a higher combined voltage or capacity than what a single battery can offer. The power pack is designed to store electrical energy and supply it as needed to various devices or systems. Power packs, as referred herein may be used for various purposes such as power electric vehicles and other energy storage applications. Furthermore, the power pack may include additional circuitry, such as a battery management system (BMS), to ensure the safe and efficient charging and discharging of the battery cells. The power pack comprises a plurality of cell arrays which in turn comprises a plurality of battery cells.
As used herein, the term “powertrain unit” refers to a system that converts the electrical energy from the power pack into mechanical energy that drives the wheels of the electric vehicle.
As used herein, the term “inverter”, “drive-train unit” and “DTU” are used interchangeably and refer to a component of the powertrain of an electric vehicle that is responsible for converting direct current (DC) from the battery pack of the electric vehicle into alternating current (AC) to power the electric motor that drives the wheels of the electric vehicle. It is to be understood that the traction inverter is utilized in power conversion, motor control, and regenerative braking of the electric vehicle. The traction inverter comprises advanced power electronics to ensure the smooth and efficient operation of the electric vehicle.
As used herein, the terms “traction motor”, “electric motor”, and “motor” are used interchangeably and refer to a motor specifically designed and employed for the purpose of propelling a vehicle, such as an electric vehicle. It is to be understood that the traction motors rely on electric power to generate motion and provide the necessary torque to drive the wheels of the electric vehicle.
As used herein, the term “motor drive” refers to a system that controls the speed and torque of the electric motor. The motor drive does this by converting the high-voltage DC power from the battery to a low-voltage AC power that is suitable for the electric motor. The motor drive also controls the amount of current that flows to the motor, which determines the motor's speed and torque.
As used herein, the term “gate drivers” refers to electronic components responsible for controlling the switching of Metal Oxide Semiconductor Field Effect Transistor (MOSFET) which forms switches in the traction inverter. It is to be understood that the gate drivers convert the control signal into precise voltage and current pulses required to turn the power electronics switches on and off rapidly. These switches control the flow of electrical current to the electric motor, ultimately determining its speed, torque, and direction of rotation.
As used herein, the term “MOSFET” refers to the Metal-Oxide-Semiconductor Field-Effect Transistor. It is a type of transistor that uses an electric field to control the flow of current through the device. MOSFETs have three terminals: source, gate, and drain. The source and drain terminals are connected to the circuit that the MOSFET is controlling, while the gate terminal is used to control the flow of current through the device. When a voltage is applied to the gate terminal, it creates an electric field that attracts or repels charge carriers in the semiconductor material. This electric field can be used to create a conductive channel between the source and drain terminals, which allows current to flow through the device.
As used herein, the term “forward flow” of current refers to the flow of current from the power pack to the traction motor. This current causes the traction motor to rotate its rotor, which in turn drives the wheels of the electric vehicle.
As used herein, the term “reverse flow” of current refers to the flow of current from the traction motor to the power pack. This current causes the power pack to recharge and extend the range of the electric vehicle.
As used herein, the term “protection unit” refers to a safety circuit that protects the electrical and electronic components of the electric vehicle from different forms of electrical damages such as overcharging, overcurrent, overvoltage and so forth.
As used herein, the terms ‘microcontroller’ and ‘processor’ are used interchangeably and refer to a computational element that is operable to respond to and process instructions that control the system. Optionally, the microcontroller may comprise a complex instruction set computing (CISC) microprocessor, a reduced instruction set (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a digital signal processor, or any other type of processing unit or microcontroller. Furthermore, the term “microcontroller” may refer to one or more individual processors, processing devices, and various elements associated with a processing device that may be shared by other processing devices. Furthermore, the microcontroller may be designed to handle real-time tasks with high performance and low power consumption. Furthermore, the microcontroller may comprise custom and/or proprietary processors.
As used herein, the terms “DC link capacitor”, “DC bus capacitor”, and “capacitor” are used interchangeably and refer to a capacitor that is used to smooth out the fluctuating DC voltage between the power pack and the inverter. The DC link capacitor functions to smooth out the power between the two components, stabilize the DC bus voltage, and act as energy storage for transient loads.
As used herein, the term “pre-charge circuit” refers to circuit that is used to limit the inrush current to a load when it is first powered up. It is to be understood that the term “pre-charge switches” refers to switching elements installed in the pre-charge circuit. Furthermore, the term “pre-charge resistor” refers to resistor installed in the pre-charge circuit.
As used herein, the term “bypass circuit” refers to electrical circuit used in the electric vehicles to dump regenerative current when the power pack is in high state of charge and cannot accept further regenerative energy.
As used herein, the term “switch” and “plurality of switch” are used interchangeably and refers to an electronic or mechanical device that controls the flow of electrical current.
As used herein, the term ‘communicably coupled’ refers to a bi-directional connection between the various components of the system. The bi-directional connection between the various components of the system enables the exchange of data between two or more components of the system. Similarly, the bi-directional connection between the system and other elements/modules enables the exchange of data between the system and the other elements/modules.
Figure 1, in accordance with an embodiment, describes a powertrain unit 100 of an electric vehicle. The powertrain unit 100 comprises a motor drive 102, a power pack 104, and a protection unit 106. The motor drive 102 comprises a motor 102a and an inverter 102b. The protection unit 106 is configured to allow a forward flow of current in a driving mode and a selective reverse flow of current in a regenerative mode.
The powertrain unit 100 of an electric vehicle is disclosed. The powertrain unit 100 of the electric vehicle, as disclosed in the present disclosure, is advantageous in terms of protecting the motor drive 102 and the power pack 104 from a high back emf generated during the regenerative braking. Moreover, the powertrain unit 100, as disclosed by the present disclosure, is advantageous in terms of preventing failure of the motor drive 102 and failure of the power pack 104 by controlling excessive current generated during the regenerative mode. Furthermore, the powertrain unit 100, as disclosed by the present disclosure, is advantageous in terms of preventing failure of the motor drive 102 and failure of the power pack 104 by controlling excessive voltage generated during the regenerative mode. Moreover, the powertrain unit 100, as disclosed by the present disclosure, is advantageous in terms of preventing failure of the motor drive 102 and failure of the power pack 104 by preventing excessive heat generation during the regenerative mode. Furthermore, the powertrain unit 100, as disclosed by the present disclosure, is advantageous in terms of simultaneously providing regenerative energy to the power pack 104 and the bypass circuit 106b, for efficient regenerative braking of the electric vehicle, eliminating the use of energy inefficient mechanical braking.
In an embodiment, the driving mode corresponds to normal operating condition of the electric vehicle in which power is delivered from the power pack 104 to the motor 102a via the protection unit 106. It is to be understood that the driving mode may comprise different dynamics and levels of power delivery from the power pack 104 to the motor 102a. In an example, the driving mode may comprise economy mode, city mode, sport mode, and so forth with different levels of power delivery from the power pack 104 to the motor 102a.
In an embodiment, the regenerative mode corresponds to regenerative braking condition of the electric vehicle in which power is delivered from the motor 102a to the power pack 104 via the protection unit 106. It is to be understood that the power generated at the motor 102a in the regenerative mode corresponds to speed of the motor 102a. Beneficially, the power is delivered from the motor 102a to the power pack 104 recharges the power pack 104 extending the range of the electric vehicle.
In an embodiment, the protection unit 106 comprises a pre-charge circuit 106a, a bypass circuit 106b and a microcontroller 106c. Beneficially, the protection circuit 106 prevents high inrush currents at the start of the operation of the electric vehicle and prevents the system from damages during high regenerative energy capable of damaging the components of the motor drive 102 and power pack 104.
In an embodiment, the pre-charge circuit 106a comprises a plurality of pre-charge switches G1, G2, G3 and a pre-charge resistor R1. In a specific embodiment, the pre-charge switches G1, G2 are connected in series and facilitates the forward flow and revers flow of current during the normal operation of the electric vehicle. In another specific embodiment, the pre-charge switch G3 and the pre-charge resistor R1 are connected in series with each other and connected in parallel with the pre-charge switches G1, G2.
In an embodiment, the bypass circuit 106b comprises a bypass resistor R2 and a bypass switch G4. In a specific embodiment, the bypass resistor R2 and the bypass switch G4 are connected in series with each other and provides an additional path for the regenerative energy to flow. Beneficially, the bypass resistor R2 converts the regenerative energy (which is beyond the receiving capacity of the power pack 104) to heat.
In an embodiment, the microcontroller 106c controls the forward flow of current in the driving mode and the selective reverse flow of current in a regenerative mode via the pre-charge circuit 106a, the bypass circuit 106b. In a specific embodiment, the microcontroller 106c is configured to control components of the protection unit 106. It is to be understood that the microcontroller 106c is communicably coupled to the components of the protection unit 106. In another specific embodiment, the microcontroller 106c is configured to control the gate driver of the plurality of switches G1, G2. In yet another specific embodiment, the microcontroller 106c is configured to control the switch G3 to allow the reverse flow of current through the pre-charge resistor R1 during the regenerative mode. In yet another specific embodiment, the microcontroller 106c is configured to control the switch G4 to allow the reverse flow of current through the bypass resistor R2 during the regenerative mode.
In an embodiment, the forward flow of current occurs in the driving mode through the plurality of switches G1, G2. Beneficially, the plurality of switches G1, G2 would function normally during the normal operation of the electric vehicle.
In an embodiment, the reverse flow of current occurs selectively in the regenerative mode through the plurality of switches G1, G2, pre-charge resistor R1 and bypass resistor R2, based on a state of charge of the power pack 104. Beneficially, the pre-charge resistor R1 would reduce the current reaching the power pack 104 to prevent any potential damage. Beneficially, the bypass resistor R2 would prevent any additional current reaching the power pack 104 to prevent any potential damage. Beneficially, the simultaneous flow of current through the plurality of switches G1, G2, pre-charge resistor R1 and bypass resistor R2, enhances the reception of the regenerative power by the motor drive 102 and improves the regenerative braking efficiency of the electric vehicle eliminating the requirement of mechanical braking.
Figure 2, in accordance with an embodiment, describes a circuit diagram of a powertrain unit 100 of an electric vehicle. The powertrain unit 100 comprises a motor drive 102, a power pack 104, and a protection unit 106. The motor drive 102 comprises a motor 102a and an inverter 102b. The protection unit 106 is configured to allow a forward flow of current in a driving mode and a selective reverse flow of current in a regenerative mode. Furthermore, the driving mode corresponds to normal operating condition of the electric vehicle in which power is delivered from the power pack 104 to the motor 102a via the protection unit 106. Furthermore, the regenerative mode corresponds to regenerative braking condition of the electric vehicle in which power is delivered from the motor 102a to the power pack 104 via the protection unit 106. Furthermore, the protection unit 106 comprises a pre-charge circuit 106a, a bypass circuit 106b and a microcontroller 106c. Furthermore, the pre-charge circuit 106a comprises a plurality of pre-charge switches G1, G2, G3 and a pre-charge resistor R1. Furthermore, the bypass circuit 106b comprises a bypass resistor R2 and a bypass switch G4. Furthermore, the microcontroller 106c controls the forward flow of current in the driving mode and the selective reverse flow of current in a regenerative mode via the pre-charge circuit 106a, the bypass circuit 106b. Furthermore, the forward flow of current occurs in the driving mode through the plurality of switches G1, G2. Furthermore, the reverse flow of current occurs selectively in the regenerative mode through the plurality of switches G1, G2, pre-charge resistor R1 and bypass resistor R2, based on a state of charge of the power pack 104.
In an exemplary embodiment, when the electric vehicle is operating in the driving mode, the power is delivered from the power pack 104 to the motor 102a. When the user of the electric vehicle starts to decelerate performing regenerative braking, the microcontroller detects the same and simultaneously divides the reverse flow of current between plurality of switches G1, G2, pre-charge resistor R1 and bypass resistor R2 for efficient regenerative braking of the electric vehicle.
In accordance with another embodiment, there is described a protection unit 106 for a powertrain unit 100 of an electric vehicle. The protection unit 106 comprises a pre-charge circuit 106a comprising a plurality of pre-charge switches G1, G2, G3 and a pre-charge resistor R1, a bypass circuit 106b comprising a bypass resistor R2 and a bypass switch G4, and a microcontroller 106c configured to control flow of current through the pre-charge circuit 106a and the bypass circuit 106b.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combinations of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, and “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings, and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

,CLAIMS:WE CLAIM:
1. A powertrain unit (100) of an electric vehicle, the powertrain unit (100) comprises:
- a motor drive (102) comprising a motor (102a) and an inverter (102b);
- a power pack (104); and
- a protection unit (106);
wherein the protection unit (106) is configured to allow a forward flow of current in a driving mode and a selective reverse flow of current in a regenerative mode.
2. The powertrain unit (100) as claimed in claim 1, wherein the driving mode corresponds to normal operating condition of the electric vehicle in which power is delivered from the power pack (104) to the motor (102a) via the protection unit (106).
3. The powertrain unit (100) as claimed in claim 1, wherein the regenerative mode corresponds to regenerative braking condition of the electric vehicle in which power is delivered from the motor (102a) to the power pack (104) via the protection unit (106).
4. The powertrain unit (100) as claimed in claim 1, wherein the protection unit (106) comprises a pre-charge circuit (106a), a bypass circuit (106b) and a microcontroller (106c).
5. The powertrain unit (100) as claimed in claim 4, wherein the pre-charge circuit (106a) comprises a plurality of pre-charge switches (G1, G2, G3) and a pre-charge resistor (R1).
6. The powertrain unit (100) as claimed in claim 4, wherein the bypass circuit (106b) comprises a bypass resistor (R2) and a bypass switch (G4).
7. The powertrain unit (100) as claimed in claim 4, wherein the microcontroller (106c) controls the forward flow of current in the driving mode and the selective reverse flow of current in a regenerative mode via the pre-charge circuit (106a), the bypass circuit (106b).
8. The powertrain unit (100) as claimed in claim 1, wherein the forward flow of current occurs in the driving mode through the plurality of switches (G1, G2).
9. The powertrain unit (100) as claimed in claim 1, wherein the reverse flow of current occurs selectively in the regenerative mode through the plurality of switches (G1, G2), pre-charge resistor (R1) and bypass resistor (R2), based on a state of charge of the power pack (104).
10. A protection unit (106) for a powertrain unit (100) of an electric vehicle, the protection unit (106) comprises:
- a pre-charge circuit (106a) comprising a plurality of pre-charge switches (G1, G2, G3) and a pre-charge resistor (R1);
- a bypass circuit (106b) comprising a bypass resistor (R2) and a bypass switch (G4); and
- a microcontroller (106c) configured to control flow of current through the pre-charge circuit (106a) and the bypass circuit (106b).