Electric motor drive system for vehicle

Abstract

An electric drive system for a vehicle is disclosed. The system includes a plurality of electric propulsion motors and a plurality of corresponding inverter circuits. The system also includes an assist motor for driving an assist device located in the vehicle. An auxiliary motor is connected to the propulsion motor and driven by the inverter circuit. The system does not include a separate inverter for driving the auxiliary motor.

Description

Electric motor drive system for vehicles

[0001] This application is a divisional application of the invention patent application filed on March 24, 2021, with application number 202180023486.9 and invention title "Electric Motor Drive System for Vehicles". Technical Field

[0002] This disclosure relates to a method of using at least one main inverter to partially or completely replace the function of an auxiliary inverter, thereby reducing the hardware requirements of a motor drive system. Background Technology

[0003] Electric vehicles employ auxiliary power systems (i.e., auxiliary drives) to power auxiliary loads. These auxiliary power systems differ from vehicle propulsion systems that typically employ traction drive inverters with higher rated power. The rated power of auxiliary loads is typically less than 10 kW. These auxiliary loads may include air compressors, cooling system oil / water pumps, and electric power steering systems. Figure 1 illustrates a conventional auxiliary motor drive system 200 including an inverter. The inverter includes six power switches 220 and DC bus capacitors 210. The system may also include a gate drive board and a controller. In most cases, the inverter may require active cooling, and the hardware associated with the inverter increases the system's weight / volume / cost. The inverter provides power to auxiliary loads, such as an electric motor 230.

[0004] The goal is to find a way to meet the power requirements of the auxiliary system without using additional hardware. Summary of the Invention

[0005] This paper discloses a method for partially or completely replacing the function of an auxiliary motor inverter using at least one main inverter or traction motor inverter, thereby reducing the hardware requirements of the motor drive system.

[0006] The disclosed system provides different auxiliary drive circuits to eliminate all or part of the auxiliary inverter hardware requirements, and includes unique control algorithms for all affected circuits.

[0007] According to one disclosed embodiment, an electric drive system for a vehicle is disclosed. The system includes first, second, and third electric propulsion motors for driving the vehicle, wherein each propulsion motor includes three main phase lines, and wherein each propulsion motor includes a neutral point among the three main phase lines. The system also includes first, second, and third inverter circuits, wherein each inverter circuit is controlled by a controller and paired with one of the electric propulsion motors, such that each inverter circuit provides multiple phase voltages across multiple main phase lines to one of the electric propulsion motors to drive the propulsion motor. The system also includes a three-phase auxiliary motor for driving auxiliary devices located in the vehicle, wherein the auxiliary motor includes three auxiliary phase lines. One of the three auxiliary phase lines is connected to the neutral point of the first propulsion motor, and the second of the three auxiliary phase lines is connected to the neutral point of the second propulsion motor, and the third of the three auxiliary phase lines is connected to the neutral point of the third propulsion motor. A controller for each inverter circuit is configured to generate a zero-sequence voltage in the neutral point and the connected auxiliary phase lines, thereby generating the phase voltage required to drive the auxiliary motor in the auxiliary phase lines.

[0008] According to another disclosed embodiment, an electric drive system for a vehicle is disclosed. The system includes first, second, and third electric propulsion motors for driving the vehicle, wherein each propulsion motor includes three main phase lines, and wherein each propulsion motor includes a neutral point among the three main phase lines. The system also includes first, second, and third inverter circuits, wherein each inverter circuit is controlled by a controller and paired with one of the electric propulsion motors such that each inverter circuit provides multiple phase voltages to one of the propulsion motors across multiple main phase lines to drive the propulsion motor. A two-phase auxiliary motor for driving auxiliary devices is located in the vehicle. The auxiliary motor includes three auxiliary phase lines. One of the two auxiliary phase lines is connected to the neutral point of the first propulsion motor, and the second of the two auxiliary phase lines is connected to the neutral point of the second propulsion motor. The neutral point of the auxiliary motor is connected to the neutral point of the third propulsion motor. The controller for each inverter circuit of the first and second propulsion motors is configured to generate a zero-sequence voltage in the neutral point and the connected auxiliary phase lines, thereby generating the phase voltages required to drive the two-phase auxiliary motor in the auxiliary phase lines.

[0009] According to yet another disclosed embodiment, an electric drive system for a vehicle is disclosed. The system includes first and second electric propulsion motors for driving the vehicle, wherein each propulsion motor includes three main phase lines, and wherein each propulsion motor includes a neutral point among the three main phase lines. The system also includes first and second inverter circuits, wherein each inverter circuit is controlled by a controller and paired with one of the electric propulsion motors such that each inverter circuit provides multiple phase voltages to one of the propulsion motors across the multiple main phase lines to drive the propulsion motor. The first inverter circuit includes an additional inverter branch comprising a pair of switches, wherein the additional inverter branch is not connected to any of the multiple main phase lines. The system includes a three-phase auxiliary motor for driving auxiliary devices located in the vehicle, wherein the auxiliary motor includes three auxiliary phase lines. One of the three auxiliary phase lines is connected to the neutral point of the first propulsion motor. A second of the three auxiliary phase lines is connected to the neutral point of a second propulsion motor. A third of the three auxiliary phase lines is connected to the additional inverter branch of the first inverter circuit. The controller for each of the two inverter circuits is configured to generate a zero-sequence voltage in the neutral point and the connected auxiliary phase line, thereby generating the phase voltage required to drive the auxiliary motor in the auxiliary phase line, wherein the controller for the first inverter circuit is configured to generate a voltage for driving the auxiliary motor in one of the additional inverter branch and the auxiliary phase line.

[0010] According to another disclosed embodiment, an electric drive system for a vehicle is disclosed. The system includes first and second electric propulsion motors for driving the vehicle, wherein each propulsion motor includes three main phase lines. Each propulsion motor includes a neutral point between the three main phase lines. The system also includes first and second inverter circuits, wherein each inverter circuit is controlled by a controller and paired with one of the electric propulsion motors such that each inverter circuit provides multiple phase voltages to one of the propulsion motors across the multiple phase lines to drive the propulsion motor. The first inverter circuit includes an auxiliary inverter branch comprising a pair of switches, wherein the auxiliary inverter branch is not connected to any of the multiple main phase lines. A two-phase auxiliary motor is provided for driving auxiliary devices located in the vehicle, wherein the auxiliary motor includes three auxiliary phase lines. One of the two auxiliary phase lines is connected to the neutral point of the first propulsion motor, and the second of the two auxiliary phase lines is connected to the auxiliary inverter branch of the first inverter circuit. The neutral point of the auxiliary motor is connected to the neutral point of the second propulsion motor. The controller for the first inverter circuit is configured to generate a zero-sequence voltage at the neutral point and in the connected auxiliary phase lines, thereby generating the phase voltage required to drive the auxiliary motor in the connected auxiliary phase lines. The controller for the first inverter circuit is also configured to generate voltages in the additional inverter branch and in the connected auxiliary phase lines to drive the auxiliary motor.

[0011] Other aspects, features, and techniques will be apparent to those skilled in the art from the following detailed description of the embodiments. Attached Figure Description

[0012] The features, objects, and advantages of the disclosed embodiments will become more apparent when the following detailed description is taken in conjunction with the accompanying drawings, in which the same reference numerals are correspondingly identified throughout, and wherein: FIG1 is a circuit diagram of an exemplary embodiment of a prior art inverter for controlling an auxiliary motor.

[0013] Figure 2 is a circuit diagram of an exemplary embodiment of a multi-inverter drive system, wherein multiple main inverters provide power to auxiliary motors by using the zero-sequence voltage of multiple main motors powered by the main inverters.

[0014] Figure 3 is a circuit diagram of an exemplary embodiment of a multi-inverter drive system, wherein multiple main inverters provide power to auxiliary motors by using the zero-sequence voltage of multiple main motors powered by the main inverters.

[0015] Figure 4 is a circuit diagram of an exemplary embodiment of a multi-inverter drive system, wherein multiple main inverters provide power to auxiliary motors by using the zero-sequence voltage of multiple main motors powered by the main inverters in combination with dedicated inverter branches.

[0016] Figure 5 is a circuit diagram of an exemplary embodiment of a multi-inverter drive system, wherein multiple main inverters provide power to auxiliary motors by using the zero-sequence voltage of multiple main motors powered by the main inverters in combination with dedicated inverter branches. Detailed Implementation

[0017] One aspect of this disclosure relates to a method of using at least one main motor inverter to partially or completely replace the function of an auxiliary motor inverter, thereby reducing the hardware requirements of the motor drive system.

[0018] Throughout this document, references to "an embodiment," "some embodiments," "an embodiment," or similar terms mean that a specific feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Therefore, such phrases appearing in various places throughout this application do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments without limitation. For example, two or more innovative methods described herein can be combined in a single method, but this application is not limited to the specific exemplary combinations of the methods described herein.

[0019] As used herein, the term “a” or “an” should mean one or more. The term “multiple” should mean two or more. The term “another” is defined as a second or more. The terms “comprising” and / or “having” are open-ended (e.g., including). As used herein, the term “or” should be interpreted as including or meaning any one or any combination thereof. Thus, “A, B, or C” means “any of the following: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition only occur when a combination of elements, functions, steps, or actions is inherently mutually exclusive to some extent.

[0020] The character "N" in this text refers to the last member of the set or the total number of members in the set. The character "X" in this text refers to a variable member of the set. The characters "A", "B", "C", etc., refer to specific but undefined members of the set.

[0021] Detailed implementations of various embodiments are provided; however, it should be understood that the disclosed embodiments are merely exemplary and can be implemented in various alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein are not to be construed as limiting, but merely as a representative basis for teaching those skilled in the art to adopt the disclosed embodiments in various ways.

[0022] Figure 2 illustrates a powertrain system for an electric vehicle. The system includes circuitry 300. A Among them, three inverters 320 A1-A3 330 is used to drive three star-connected motors in electric vehicles. A1-A3 Each inverter is connected to the same or a different DC bus (Vdc). The DC bus is powered by a battery, generator, or other electrical power source. Circuit 300 A This can be used in electric vehicles that include three inverters 320 in their powertrain to power two or more traction motors 330. A1-A3 Each of these is driven by three phase voltages, each of which is carried across a phase line. In one embodiment, each phase line corresponds to a pair of inverter switches, the operation of which provides a voltage signal / phase voltage to the phase line, and the phase voltage in turn drives the operation of the motor.

[0023] In the main motor 330, power is transferred via magnetic flux passing through the air gap, which has very low permeability, limiting motor performance. The configuration shown in Figure 2 allows the phase line voltage of the auxiliary motor 335 to be driven by the zero-sequence voltage of the main motor. This configuration avoids the use of an additional inverter branch, thus saving cost / weight / volume of the auxiliary inverter.

[0024] In one embodiment, as shown in FIG2, the auxiliary motor 335 A At least one phase line is supplied by the main (e.g., traction) motor 330 A The vehicle is driven by zero-sequence voltage, rather than by a pair of inverter switches. As used in this application, the term "auxiliary motor" refers to a motor not used for direct propulsion of the vehicle. The auxiliary motor is used to drive auxiliary devices located in the vehicle. The auxiliary devices or loads typically have a rated power of less than 10 kW. These devices may include air compressors, cooling system oil / water pumps, and electric power steering systems, each of which may include one or more auxiliary motors.

[0025] The zero-sequence voltage of a motor is the voltage between its neutral point and ground. Motor 330 A The neutral point is motor 330 A The point where the three phase lines intersect. In one embodiment, as shown in Figure 2, motors 1, 2, and 3 (330) A1-A3 The neutral point of each is connected to the auxiliary motor 335. A The phase lines R, S, and T are connected. Each motor is controlled by a controller. The controller for motor 1 is configured to generate a zero-sequence voltage V. R The controller for motor 2 is configured to generate a zero-sequence voltage Vs. The controller for motor 3 is configured to generate a zero-sequence voltage V. T Each motor can have a dedicated controller, or a single controller can control one or more motors.

[0026] Provide three phase voltages V R V S V T To drive auxiliary motor 335 A The current in phase R of the auxiliary motor is 1330 rpm. A1 The three phase lines U, V, and W are shared equally among them because the motor 1330 A1 The voltage and zero-sequence impedance are the same. This configuration will not be used in motor 1330. A1 This will not generate any air gap flux and therefore will not affect the motor 1330. A1 The torque is generated. This is in accordance with the above for the auxiliary motor 335. A In the same manner as the R phase, the auxiliary motor S phase current is in motor 2 330 A2The three phase lines A, B, and C are shared equally because the voltage and zero-sequence impedance of motor 2330A2 are the same. This configuration will not affect motor 2330. A2 This will not generate any air gap flux and therefore will not affect the motor 2 330. A2 The torque is generated. Similarly, the current in phase T of the auxiliary motor is in motor 3330. A3 The three phase lines X, Y, and Z are shared equally because the motor 3330 A3 The voltage and zero-sequence impedance are the same. This configuration will not be used in motor 3330. A3 This will not generate any air gap flux and therefore will not affect the motor 3330. A3 The torque is generated.

[0027] Figure 3 shows the proposed circuit B 300. B The circuit includes three inverters 320. The inverters 320 and the motor 330 can be the same as or similar to the inverters and motors described above. In one embodiment, motor 1 330... B1 The neutral point is connected to the two-phase auxiliary motor 335 B The neutral point, and the motor 2330 B2 The neutral point is connected to phase line R and motor 3330 B3 The neutral point is connected to the phase line S.

[0028] The controller for motor 1 is configured to generate a zero-sequence voltage 0. The controller for motor 2 is configured to generate a zero-sequence voltage V. R The controller for motor 3 is configured to generate a zero-sequence voltage Vs. Voltage (Vs) R V S Drive auxiliary motor 335 B The rotation.

[0029] Figure 4 shows the proposed circuit C300. C Two of the inverters are 320 C1-C2 and its corresponding main propulsion motor 330 C1-C2 Configured to drive a three-phase auxiliary motor 335 C Inverter 320 and motor 330 may be the same as or similar to the inverter and motor described above. Inverter 320 C1 One of them may include an additional inverter branch. Additional inverter branch 325 C1, R Connected to auxiliary motor 335 C Phase line R, and motor 1 330 C1 The neutral point is connected to phase line S and motor 2 330 C2 The neutral point is connected to phase line T. The controller of motor 1 is configured to operate in auxiliary motor 335. CA zero-sequence voltage V is generated in the phase winding S. S The controller for motor 2 is configured to operate in conjunction with auxiliary motor 335. C A zero-sequence voltage V is generated in the phase winding T. T .

[0030] Figure 5 shows the proposed circuit D 300. D Among them, the two-phase auxiliary motor 335 D Driven by two inverters configured to drive the main propulsion motor. One of the inverters may include an auxiliary inverter branch. Auxiliary inverter branch 325 D1, Aux Connected to auxiliary motor 335 D Phase line R. Motor 1 330 D1 The neutral point is connected to phase line S. The controller of motor 1 is configured to generate a zero-sequence voltage V in the phase winding or phase line S. S Motor 2 330 D2 The neutral point is connected to the auxiliary motor 335 D The neutral point. The controller of motor 2 is configured to generate a zero-sequence voltage 0.

[0031] Circuit A 300 A and B 300 B The configuration allows for the replacement of a dedicated auxiliary inverter, including all the associated hardware used in Figure 1 (e.g., power switches, capacitors, gate driver board, and microcontroller board). Furthermore, circuit C300... C and D 300 D This configuration also allows a portion of the auxiliary inverter to be eliminated. Both circuits include auxiliary branches, which are integrated into one or more main inverters that drive the main propulsion motors.

[0032] The following further describes the circuit A 300. A and B 300 B The control method. The following definitions are provided for the associated voltage: To enable the auxiliary motor 335 A To achieve the desired speed and generate reference torque, the auxiliary motor needs to be supplied with a rotational voltage µ in a stationary reference frame. αA and µ βA The voltages in the auxiliary motor require the corresponding voltage µ in motor 1. α1 and µ β1 and the corresponding voltage µ in motor 2 α2 and µ β2 For motor 3, it requires µ α3 and µ β3 .

[0033] For auxiliary motor 335 AThe voltages of phases R, S, and T can be calculated using the following equation (1). In one embodiment, the power-constant alpha-beta inverse transform is used to find the necessary phase voltages to achieve the desired auxiliary motor rotation voltage and zero-sequence voltage.

[0034] Inverter 1 320 A1 The phase voltages U, V, and W can be calculated using the following equation (2). In one embodiment, the zero-sequence voltage µ R From the auxiliary motor 335 A Inverter 1320 A1 Generation. In one embodiment, inverter 1320 A1 Not only does it generate positive sequence voltage to drive motor 1330 A1 It also produces the 335 auxiliary motor. A The zero-sequence voltage of phase R, where the auxiliary motor phase R current is at motor 1330 A1 The three phase windings / lines and inverter 1320 A1 The phases U, V, and W are shared on average.

[0035] Similarly, for inverter 2320 A2 The voltages of phases A, B, and C can be calculated using the following equation (3). In one embodiment, the zero-sequence voltage u S From the auxiliary motor 335 A Inverter 2320 A2 produce.

[0036] In inverter 3320 A3 In the equation (4), the voltages of phases X, Y, and Z can be calculated. Zero-sequence voltage µ T From the auxiliary motor 335 A Inverter 3320 A3 produce.

[0037] All the above equations are indicated via inverters 1 to 3 320. A1-A3 Auxiliary motor 335 A Control. As described above, the exemplary embodiment shown in Figures 2-5 allows the elimination of a dedicated inverter for the auxiliary motor.

[0038] For circuit B 300 B The control algorithm can be developed as described below. For example, inverter 1320 B1The phase voltages U, V, and W can be calculated using the following equation (5). The zero-sequence voltage 0 is obtained from the voltage of the auxiliary motor 335. B Inverter 1320 B1 It is generated. However, it must take the auxiliary motor 335. B The total current of the R-phase and S-phase.

[0039] In inverter 2 320 B2 In this equation, the voltages of phases A, B, and C can be calculated using the following equation (6). In one embodiment, the zero-sequence voltage u R From the auxiliary motor 335 B Inverter 2320 B2 Generated. In one embodiment, inverter 2 320 B2 Supply of auxiliary motor 335 B The R-phase current.

[0040] In inverter 3320 B3 In the equation (7), the voltages of phases X, Y, and Z can be calculated. Zero-sequence voltage u S From the auxiliary motor 335 B Inverter 3320 B3 produce.

[0041] For circuit C 300 C and D 300 D The control rules can be developed in a similar manner.

[0042] Although exemplary embodiments are mentioned in this disclosure, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the scope of the claimed embodiments.

Claims

1. An electric drive system for a vehicle, comprising: First and second electric propulsion motors for driving the vehicle, wherein each of the propulsion motors includes three main phase lines, and wherein each of the propulsion motors includes a neutral point among the three main phase lines; first and second inverter circuits, wherein each of the inverter circuits is controlled by a controller and paired with one of the propulsion motors such that each inverter circuit provides multiple phase voltages to one of the propulsion motors through multiple main phase lines to drive the propulsion motor; wherein the first inverter circuit includes an auxiliary inverter branch, the auxiliary inverter branch including a pair of switches; a three-phase auxiliary motor for driving auxiliary devices located in the vehicle, wherein the auxiliary motor includes three auxiliary phase lines; wherein each of the three auxiliary phase lines is supplied with an auxiliary phase voltage provided by one of the inverter circuits; a controller for each of the inverter circuits is configured to generate a zero-sequence voltage at the neutral point of the propulsion motor driven by the inverter circuit and in the auxiliary phase lines required to drive the auxiliary motor.

2. The electric drive system according to claim 1, wherein, One of the three auxiliary phase lines is connected to the neutral point of the first propulsion motor, the second of the three auxiliary phase lines is connected to the neutral point of the second propulsion motor, and the third of the three auxiliary phase lines is connected to an additional inverter branch of the first inverter circuit; wherein, the controller for each of the two inverter circuits is configured to generate a zero-sequence voltage at the neutral point of the propulsion motor driven by the inverter circuit and in the connected auxiliary phase line, thereby generating the auxiliary phase voltage required to drive the auxiliary motor in the auxiliary phase line, wherein the controller for the first inverter circuit is configured to generate a voltage for driving the auxiliary motor in the additional inverter branch and in one of the auxiliary phase lines.

3. An electric drive system for a vehicle, comprising: First and second electric propulsion motors for driving a vehicle, each of the propulsion motors including three main phase lines, and each of the propulsion motors including a neutral point among the three main phase lines; first and second inverter circuits, each of the inverter circuits being controlled by a controller and paired with one of the propulsion motors such that each inverter circuit provides multiple phase voltages to one of the propulsion motors through multiple main phase lines to drive one of the propulsion motors; the first inverter circuit including an additional inverter branch including a pair of switches; a two-phase auxiliary motor for driving an auxiliary device located in the vehicle, wherein the auxiliary motor includes two auxiliary phase lines; each of the two auxiliary phase lines being supplied with an auxiliary phase voltage by one of the inverter circuits; a controller for each of the inverter circuits configured to generate a zero-sequence voltage at the neutral point and in the auxiliary phase lines required to drive the auxiliary motor.

4. The electric drive system according to claim 3, wherein, One of the two auxiliary phase lines is connected to the neutral point of the first propulsion motor, and the second of the two auxiliary phase lines is connected to an additional inverter branch of the first inverter circuit; wherein the neutral point of the auxiliary motor is connected to the neutral point of the second propulsion motor; and wherein the controller for the first inverter circuit is configured to generate a zero-sequence voltage at the neutral point and in the connected auxiliary phase line, thereby generating the auxiliary phase voltage required to drive the auxiliary motor in the connected auxiliary phase line, wherein the controller for the first inverter circuit is configured to generate a voltage for driving the auxiliary motor in the additional inverter branch and in the connected auxiliary phase line.

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