Patent Application
20230294522
The invention relates to a control system for an electric vehicle, the vehicle having a chassis which is connectable to two, four, six or eight in-wheel motors. The invention also relates to an electric vehicle comprising such a control system and to a method of manufacture of an electric vehicle.
From US 2014/025716 an electric vehicle is known having two independent electric motors, each with different torque characteristics. A torque and traction controller receives driver signals generated by a steering sensor, an acceleration sensor, brake sensor and gear selection sensor and in coupled to two power control modules for determining the power that each power control module supplies to its respective motor.
U.S. Pat. No. 5,973,463 describes a vehicle having two in-wheel motors. The right and the left rear in-wheel motors are each operated via a separate inverter and individual motor controller that is connected to the central vehicle controller that also receives individual wheel speed data.
It is an object of the present invention to provide a controller for an electric vehicle with at least two in-wheel motors which can be used on vehicles having different numbers of motors. It is a further object to provide a controller that provides redundant operation and which provides stable and safe driving conditions in case of interruption of the data exchange with or power supply to a specific wheel, or failure or malfunctioning of one of the in-wheel motors.
It is again an object of the invention to provide electric vehicles that can be easily provided with different sets of in-wheels motors that can be accurately and reliably serviced and controlled via the control system of the invention.
Hereto a control system according to the invention comprises:
in case of two in-wheel motors can each be connected to a respective motor and
in case of four, six or eight in-wheel motors, can each be connected to a group of in-wheel motors, each group comprising at least one pair of motors situated on the same transverse axis,
in case of two in-wheel motors, to a respective motor, and in case of four, six or eight in-wheel motors, to a respective group of motors, for supplying power to each group,
wherein the control unit comprises a memory with a look-up table in which:
when two motors are used on the vehicle, each motor is assigned to a respective signal terminal and to a respective power line, and
when four motors are used on the vehicle,
a first group of two motors is assigned to the first signal terminal and to the first power line and a second group of two motors is assigned to the second signal terminal and to the second power line.
By connecting each group of motors to a respective signal line, failure on one signal line resulting in loss of communication, will result in loss of drive and brake power of the same amount of in-wheel motors on the left side and the right side of the vehicle. This improves the dynamic stability of the vehicle as no imbalance in torque occurs. The same redundancy is achieved with the power lines. If a high voltage related problem would occur in a single DC power line causing a high voltage fuse to open and to cause loss of drive and brake torque of the connected in-wheel motors, this would have an effect on the same number of in-wheel motors on the left and on the right side of the vehicle keeping a balanced torque distribution and control.
For the power lines, a hard-wired connection of the in-wheel motors to the power distribution unit is provided. The control unit can interact with the power distribution unit for each motor configuration comprising 2, 4, 6 or 8 wheels using the same hardwired connection. The control unit utilizes a single set of control signals for each group of in-wheel motors. Therefore, connecting one or more additional in-wheel motors to the same group does not require an increase in the number of control signals. The design remains similar for different configurations of groups of in-wheel motors. No additional wires are needed between the control unit and the power distribution unit. This simplifies the design of the system across different configurations.
The-control unit knows, based on the configuration, where the in-wheel motor communication is expected through the fixed look up table. Feedback data from each in-wheel motor to the control unit during the pre-charge cycle, is communicated through a CANbus and is managed with software.
In a control system that controls six motors on the vehicle, a first group of two motors is assigned to the first signal terminal and to the first power line and a second group of four motors is assigned to the second signal terminal and to the second power line. Alternatively, the first group may comprise four motors, and the second group two. For eight motors, a first group of four motors is assigned to the first signal terminal and to the first power line and a second group of four motors is assigned to the second signal terminal and to the second power line. Alternatively, the first group may comprise two motors, and the second group six, or the first group may comprise 6 motors and the second group 2.
In an embodiment of a control system according to the invention, to each wheel position on the vehicle, a unique wheel identifier is assigned, the control unit being adapted to exchange data with a predetermined wheel by sending and receiving information using the corresponding wheel identifier. The wheel identifiers may for each wheel on the same side of the vehicle comprise an even or an odd number, the identifier numbers increasing counting up from a front or from a rear chassis position.
The unique assignment of wheel numbers over the complete system will ensure that operational mistakes, such as connecting an in-wheel motor to the incorrect signal terminal, will cause an inactivated in-wheel motor.
In an embodiment of a control system according to the invention, in a pre-charge procedure of a predetermined wheel, the control unit controls the power supply from the Power distribution unit (PDU) to the predetermined wheel or group of wheels, and receives feedback data relating to the pre-charging procedure from the wheel(s). In the pre-charging procedure, a feedback value is sent from the in-wheel motor or group of motors to the power control unit to check if the process has been executed successfully. Due to the similar layout of the data lines and the power lines, it is ensured that the redundancy between the power lines and data lines is optimal.
The control unit according to the invention is connectable to a service terminal for exchange of data with a predetermined wheel. The service terminal may comprise a laptop or hand held terminal with software to interact with the wheels for diagnostic purposes. This diagnostic service application may be used by different disciplines, such as engineering, production, testing or service and interacts with the control unit and with the in-wheel motors. Actions that are carried out may be software updates, calibration of parameters, execution of test procedures or the extraction of diagnostic information. This software interfaces with the system for instance through a USB to CANbus interface.
The control unit may comprise CANbus gateway functionality allowing CANbus access to an individual in-wheel motor by means of the vehicle CANbus. The CANbus traffic from the diagnostic service terminal is routed from the vehicle CANbus towards the correct local CANbus where the desired in-wheel motor is located. This provides easy access for the service engineer, since there is only a single access point for diagnostics on the control system module. The distribution of the in-wheel motors is known to the gateway function for performing the correct routing through the use of the look-up table that is set by the wheel configuration and that hence determines where the information should be routed towards.
An embodiment of a control system according to the invention will, by way of non-limiting example, be explained in detail with reference to the accompanying drawings. In the drawings:
The motors are arranged in pairs M1,M2; M3,M4 and M5, M6, wherein the motors in a pair are aligned along the axes 12,13,14. The motors M1,M2 near the front 17 are connected to the power line 3 and to the data line 5. The motors M3-M6 are connected to the power line 4 and to the data line 6. The chassis 2 is provided with two wheel connect positions 15, 16, with connectors vc7,dc7 and vc8, dc8 for optionally connecting to a further pair of in-wheel motors. The chassis 2 may be formed of a rigid body in a single piece or can be formed of multiple segments that may for instance be interconnected via an articulation joint.
In the embodiment shown in
The control system formed by the PDU 7 and PCM 9 can be connected to 2, 4, 6, or 8 in-wheel motors on a vehicle. The use of groups of in-wheel motors offers redundancy to the vehicle since a single failure of an in-wheel motor allows the vehicle to continue operation with limited performance. This redundancy is further extended by the physically separated communication lines (CANbus) SL1, SL2 of the in-wheel motors towards the central control module PCM 9, and the physically separated DC-Link PL1, PL2 of the in-wheel motor towards the power distribution unit PDU 7.
The PDU 7 comprises high voltage fuses, main contactors and pre-charge circuits.
For the configurations using 4, 6 or 8 motors as shown in
To identify the in-wheel motors M1-M8, each one is assigned a number with the following conventions:
Because the in-wheel motors are distributed as illustrated in
and brake torque of the connected in-wheel motors, this would have an effect on the same number of in-wheel motors on the left and right side of the vehicle. This improves the dynamic stability of the vehicle.
The in-wheel motor number of motors M1-M8 is directly linked to the identification of the communication messages that are exchanged between the in-wheel motor and the PCM 9. The strict unique assignment of wheel numbers over the complete system will ensure that operational mistakes, e.g. connecting an in-wheel motor to the incorrect communication channel, will cause an inactivated in-wheel motor. The assignment of in-wheel motors M1-M8 to the rechargeable energy storage system 10 is organized by the two physically separated DC-Link channels PL1, PL2, as shown in
The advantage of the similarity in distribution of in-wheel motors towards the DC-Links PL1,PL2 is threefold:
Firstly, if high voltage related problem would occur on a single DC-Link channel, hence causing the high voltage fuse to open and therefore loss of drive and brake torque of the connected in-wheel motors, this has an effect on the same number of in-wheel motors on the left and right side of the vehicle. This improves the dynamic stability of the vehicle.
Secondly, there is a relation between the communication from the PCM 9 towards the in-wheel motor and the DC-Link PL1, PL2 of that in-wheel motor trough the pre-charge procedure. The pre-charge procedure requires a feedback value to be sent from the in-wheel motor to the PCM 9 to check if the process has been executed successfully. Due to the similar distribution of the motors with respect to the communication channels SL1, SL2 and with respect to the DC-Link PL1, PL2, it is ensured that the redundancy between both communication and power channels is optimal.
Thirdly, The PCM 9 comprises CANbus gateway functionality that is used to allow CANbus access to an individual in-wheel motor by means of the vehicle CANbus. The CANbus traffic from the diagnostic service application is routed from the vehicle CANbus towards the correct private CANbus where the pre-determined in-wheel motor is located. This will ease the accessibility for the service engineer, since there is one single access point for diagnostics of the control system.
The distribution of in-wheel motors M1-M8 over the communication channels SL1-SL2 needs to be known by the gateway function in order to perform the correct routing, that is carried out on the basis of the look-up table, an example of which is given below.
From a central control perspective there is a hardwired connection 8 from the PCM 9 to the PDU 7 for control of the high voltage contactors. The PCM 9 can control the PDU for each configuration (2, 4, 6 and 8 wheels) using the same hardwired connection carrying multiple signals. This simplifies the design of the system across different configurations.
The PCM 9 will need to know based on the configuration according to
In the table below, a mapping is given that is stored in the memory of the PCM 9.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2026182 | Jul 2020 | NL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NL2021/050477 | 7/26/2021 | WO |
