A method for operating a drive system for an at least in part electrically operatedmotor vehicle, a computer program product, a non-transitory computer-read

Abstract

A drive system 12 for an at least partly electrically-operated motor vehicle 10 comprises: first and second motors 32,34, first and second electric drive units 14,16, and a communication link 22. The first motor is connected to the first electric drive unit and an axle 26, which is connected to a first communication device 18. The second motor is connected to the second electric drive unit and the axle, which is connected to a second communication device 20. A method for operating the drive system comprises detecting at least one of: a period for a sensor input signal 28,30; a timing of the pulse-width modulation signal; or a frequency of the sensor input signal. An adjustment for the sensor input signal is determined for the first or second communication device. The adjustment for the sensor input signal is transmitted from the first communication device to the second communication device, and the adjustment for the sensor input signal is executed. The adjustment for the sensor input signal may comprise: a timing of the period for, or a frequency of, the sensor input signal; a first duty cycle for the first sensor input signal of the first communication device; and / or a second duty cycle for the second sensor input signal of the second communication device.

Description

[0001] The present invention relates to the field of automobiles. More specifically, the present invention relates to a method for operating a drive system for an at least in part electrically operated motor vehicle according to independent claim 1. Furthermore, the present invention relates to a corresponding computer program product, a corresponding non-transitory computer-readable storage medium, as well as to a corresponding drive system. BACKGROUND INFORMATION

[0002] High performance electric vehicles may include two motors per axle. With two motors per axle, the drive system may increase output torque / power and implement electric torque vectoring. However, uncontrolled electric torque vectoring may involve a high risk and may cause a motor vehicle accident. Therefore, a high level in high-speed diagnostics is required. Furthermore, because of high power operation, high current operation, and variable frequency, a high voltage DC may have a high ripple voltage. The lifetime of a DC capacitor may be reduced by the high ripple voltage. High ripple voltage may cause malfunction of components which are connected to the same voltage powernet. Therefore, there is a need in the art to synchronize the motors of a drive system in order to reduce the ripple voltage. SUMMARY OF THE INVENTION

[0003] It is an object of the present invention to provide a method, a corresponding computer program product, a corresponding non-transitory computer-readable storage medium, as well as a corresponding drive system, by which a robust operating of the drive system is realized.

[0004] This object is solved by a method, a corresponding computer program product, a corresponding non-transitory computer-readable storage medium, as well as a corresponding drive system according to the independent claims. Advantageous embodiments are presented in the dependent claims.

[0005] One aspect of the invention relates to a method for operating a drive system for an at least in part electrically operated motor vehicle. At least one of a pulse-width modulation output signal, a period for a sensor input signal, the start time of a period for the sensor input signal, a timing of the sensor input signal, or a frequency of the sensor input signal is detected. An adjustment for the sensor input signal or for the pulse-width modulation output signal for a first communication device or a second communication device is determined, wherein the first communication device is connected to a first electric drive unit and the second communication device is connected to a second electric drive unit. The adjustment for the sensor input signal is transmitted from the first communication device to the second communication device. The adjustment for the pulse-width modulation output signal is executed based on the sensor input signal.

[0006] Therefore, the pulse-width modulation output signals of the two electric drive units may be synchronized, assigned high-speed communication BUS such as for example SPI (serial peripheral interface) to monitor the other electric drive unit. Therefore, this may provide a high-level diagnostic and high-speed diagnostic for the synchronized pulse-width modulation. Each electric drive unit provides the start time of the period for the sensor input signal, frequency information for the sensor input signal or digital signal, and other comparable information to produce a pulse-width modulation output signal. Each electric drive unit may adjust / shift the start time of the period and frequency information for the sensor input signal.

[0007] According to an embodiment the adjustment for the sensor input signal comprises at least a timing of the period for the sensor input signal or a timing of the period for a pulse-width modulation output signal.

[0008] In another embodiment the adjustment for the sensor input signal comprises at least a frequency of the sensor input signal, the pulse-width modulation output signal, or another comparable pulse-width modulation signal.

[0009] In another embodiment the adjustment for the sensor input signal comprises a first duty cycle for the sensor input signal or pulse-width modulation output signal of the first communication device.

[0010] In another embodiment the adjustment for the sensor input signal comprises a second duty cycle for the sensor input signal or pulse-width modulation output signal of the second communication device.

[0011] In another embodiment transmitting the adjustment for the sensor input signal for the first communication device or the second communication device is at a high speed.

[0012] In another embodiment depending on the detected sensor input signals or the detected pulse-width modulation output signals and the determined adjustment for the sensor input signals or for the pulse-width modulation output signals, the first electric drive unit and the second electric drive unit are synchronized.

[0013] In particular, the method is a computer-implemented method. Therefore, another aspect of the present invention relates to a computer program product comprising program code means for performing a method according to the preceding aspect.

[0014] A still further aspect of the invention relates to a non-transitory computer-readable storage medium comprising at least the computer program product according to the preceding aspect.

[0015] Furthermore, the invention relates to a drive system for an at least in part electrically operated motor vehicle, comprising at least one first electric drive unit and one second electric drive unit, wherein the drive system is configured for performing a method according to the preceding aspect. In particular, the method is performed by the drive system.

[0016] Furthermore, the invention relates to a motor vehicle comprising at least the drive system according to the preceding aspect. The motor vehicle is in particular at least in part electrically operated or fully electrically operated.

[0017] The communication device may include an electronic computing device / computing unit. The electronic computing device / unit therefore may comprise electronic means, for example, processors, circuits, in particular integrated circuits, and further electronic means for performing a method. A computing unit may in particular be understood as a data processing device, which comprises processing circuitry. The computing unit can therefore in particular process data to perform computing operations. This may also include operations to perform indexed accesses to a data structure, for example a look-up table, LUT.

[0018] In particular, the computing unit may include one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits, ASIC, one or more field-programmable gate arrays, FPGA, and / or one or more systems on a chip, SoC. The computing unit may also include one or more processors, for example one or more microprocessors, one or more central processing units, CPU, one or more graphics processing units, GPU, and / or one or more signal processors, in particular one or more digital signal processors, DSP. The computing unit may also include a physical or a virtual cluster of computers or other of said units.

[0019] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more memory units.

[0020] A memory unit may be implemented as a volatile data memory, for example a dynamic random access memory, DRAM, or a static random access memory, SRAM, or as a non-volatile data memory, for example a read-only memory, ROM, a programmable read-only memory, PROM, an erasable programmable read-only memory, EPROM, an electrically erasable programmable read-only memory, EEPROM, a flash memory or flash EEPROM, a ferroelectric random access memory, FRAM, a magnetoresistive random access memory, MRAM, or a phase-change random access memory, PCRAM.

[0021] Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and / or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The novel features and characteristic of the disclosure are set forth in the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and together with the description, serve to explain the disclosed principles. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and / or methods in accordance with embodiments of the present subject matter are now described below, by way of example only, and with reference to the accompanying figures.

[0023] The drawings show in:

[0024] Fig. 1 a schematic block diagram according to an embodiment of a motor vehicle comprising an embodiment of a drive system;

[0025] Figs. 2A and 2B a schematic diagram of period and frequency information of a pulse-width modulation input signal;

[0026] Figs. 3A and 3B another schematic diagram period and frequency information of a pulse-width modulation input signal and a pulse-width modulation output signal according to an embodiment;

[0027] Fig. 4 a schematic block diagram according to an embodiment of a communication for signaling;

[0028] Fig. 5 a schematic block diagram according to an embodiment of a drive system and communication for signaling.

[0029] In the figures the same elements or elements having the same function are indicated by the same reference signs. DETAILED DESCRIPTION

[0030] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0031] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawing 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.

[0032] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion so that a setup, device or method 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 device or method. In other words, one or more elements in a system or apparatus preceded by “comprises” or “comprise” does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or method.

[0033] In the following detailed description of the embodiment of the present disclosure, reference is made to the accompanying drawing that forms part hereof, and in which is shown by way of illustration a specific embodiment in which the disclosure may be practiced. This embodiment is 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.

[0034] Fig. 1 shows a schematic block diagram according to an embodiment of a motor vehicle 10. The motor vehicle 10 may be at least in part electrically operated or fully electrically operated. The motor vehicle 10 comprises at least a drive system 12. The drive system 12 may include at least 1 DC link capacitor (common capacitor), 1 EMC filter, and 1 DC current sensor with the proposed dual controllers, which are described in more detail below. Furthermore, the drive system 12 comprises at least a first electric drive unit 14 as well as a second electric drive unit 16. The first electric drive unit 14 as well as the second electric drive unit 16 may also be regarded as a power module. The first electric drive unit 14 comprises a first communication device 18 and the second electric drive unit 16 may comprise a second communication device 20. Between the first communication device 18 and the second communication device 20 a communication link 22 is established. In particular, this communication link 22 may be in the form of an SPI, indication link, in particular a so-called serial peripheral interface. Furthermore, the first communication device 18 and the second communication device 20 may share a ground connection 24.

[0035] According to an embodiment of a method detecting at least one of a period for the sensor input signal 28, 30, a period timing of the sensor input signal 28, 30, or a frequency information of sensor input signal 28, 30 is performed. This step may be performed by the first electric drive unit 14, wherein the first electric drive unit 14 is connected to the first communication device 18. An adjustment for the start time of the period for the sensor input signal 28, 30 and the frequency information for the sensor input signal 28, 30 for the first communication device 18 or the second communication device 20 is determined, wherein the first communication device 18 is connected to the first electric drive unit 14 and the second communication device 20 is connected to the second electric drive unit 16. This step may be performed by the first electric drive unit 14 or other components. The adjustment for the start time of the period for the sensor input signal 28, 30 and the frequency information for the sensor input signal 28, 30 is transmitted from the first communication device 18 to the second communication device 20. This step may be performed by the first electric drive unit 14. The adjustment for the start time of the period for the sensor input signal 28, 30 and the frequency information for the sensor input signal 28, 30 is executed for producing a pulse-width modulation output signal 36, 38. This step may be performed by the first electric drive unit 14 or the second electric drive unit 16 or other components.

[0036] In particular as shown in Fig. 1 the drive system 12 may be configured for a rear axle 26. It is further possible, that the drive system 12 may be configured for a front axle of the motor vehicle 10.

[0037] In particular, with the two drive units 14, 16 per axle 26 the motor vehicle 10 can increase the output torque / power and implement electric torque vectoring. Because of high power operation, high current operation and variable frequency, a high voltage DC may have ripple voltage. A lifetime of a DC capacitor may be reduced by high ripple voltage. High ripple voltage may cause malfunction of components which are connected to the same high voltage power net. This may be for example the electric drive units 14, 16. In particular, both communication devices 18, 20, which may also be regarded as controllers, are very close to each other and may comprise the same electric potential, in particular the ground 24. If the period of the sensor input signal 28, 30 of both electric drive units 14, 16 is synchronized one electric drive unit and one pulse-width modulation output signal 36, 38 (as shown in Fig. 3) shift is quad or half period, and the high voltage DC ripple will be reduced dramatically.

[0038] In particular, to synchronize, shift, and change the frequency of the sensor input signal 28, 30, assigned high-speed communication BUS such as the SPI to monitor the other communication devices 18, 20 is provided. This may provide high-speed diagnostic for synchronized period information for the sensor input signals 28, 30. And each electric drive unit 14, 16 provides adjustments to the pulse-width modulation timing and frequency information for the sensor input signal 28, 30 for the pulse-width modulation output signal 36, 38. Each electric drive unit 14, 16 may adjust / shift the period and / or the start time of the period for the sensor input signal 28, 30 with pulse-width modulation timing and frequency information to produce an adjusted pulse-width modulation output signal 36, 38.

[0039] Figs. 2A and 2B shows a schematic diagram according to an embodiment of the start time of the period and frequency of the period for the sensor input signal 28, 30. In particular for example, the first communication device 18 may be a so-called master and the second communication device 20 may be a so-called slave. Therefore, a so-called master-slave communication is provided. Every ti a communication between the master and the slave is provided. The master provides a time toM and the slave may provide a time tos. Therefore, at these times, they are ready for changing the pulse-width modulation frequency. In particular, a current pulse-width modulation frequency and / or a pulse-width modulation frequency in the future may be changed. Furthermore, a shift status of the sensor input signal 28, 30 or pulse-width modulation output signal 36, 38 may be provided, in particular if it is permissible or not permissible.

[0040] In particular Fig. 2B shows an example of the start time of the period for the pulse-width modulation signals 28, 30 with a half-period-shift shift, in particular with a quarter-period-shift. Furthermore, for example the master provides the start time of the period and frequency information for a pulse-width modulation signal 28, 30 such as a duty cycle of 50 percent for the digital output. The slave adjusts tos timer with the master signal toM. This is because the oscillator is very stable, and the slave may only need to adjust tos timer at the beginning. If the adjustment of the sensor input signals 28, 30 occurs during operation, the master or slave may adjust the period or frequency information. For example, the master may implement a minimal period adjustment such as 0.01 usee to increase or decrease the period of the sensor input signal 28, 30. The master / slave can check the pulse-width modulation shift status with the frequency of the sensor input signal 28, 30 or the pulse-width modulation output signal 36, 38. Furthermore, a time ti is provided, wherein at ti the SPI master may send and / or read the sensor input signal 28, 30 and / or the pulse-width modulation output signal 36, 38.

[0041] Figs. 3A and 3B shows another schematic diagram of the sensor input signal 28, 30 and pulse-width modulation output signal 36, 38. In particular in Fig. 3B, the master slave SPI communication with a duty cycle of 50 percent is shown based on the time shifts between ti and tn and tsand ti3- In particular, a half period shift, in particular a quarter period, is shown. Furthermore, a time ts is provided, wherein at ts the SPI master may send and / or read the sensor input signal 28, 30 and / or the pulse-width modulation output signal 36, 38.

[0042] Fig. 4 shows a schematic block diagram according to an embodiment of a communication for pulse-width modulation signaling. In particular the communication link 22 between the two communication devices 18, 20 is shown, wherein one communication device 18, 20 is configured as a master and one as a slave.

[0043] The communication link 22 may include signals such as a synchronous peripheral interface clock output, a synchronous peripheral interface clock input, a master SPI data output, a slave SPI data output, a synchronous peripheral interface master slave select output, a synchronous peripheral interface master slave select input, or other comparable signals. The signals may be used to transmit and receive data between the communication device 18, 20 for motor control.

[0044] The detected and / or adjusted data may be exchanged between the first communication device 18 such as the SPI master and the second communication device 20 such as the SPI slave. The data may include at least five values for a motor control task (ex 10Ousec) or 1 msec to produce the period or frequency information for the pulsewidth modulation output signal 36, 38. The five values may include the previous period = int ( Previous period of pulse-width modulation output signal 36, 38 / 0.01 usee ); present period = int ( Present period of pulse-width modulation output signal 36, 38 / 0.01 usee ); next period = int ( Next period of pulse-width modulation output signal 36, 38 / 0.01 usee ); start time of period; and start time of sensor input signal 28, 30.

[0045] Fig. 5 shows a schematic block diagram according to an embodiment of a drive system 12 and communication link 22 for signaling between the first communication device 18 and the second communication device 20. The first communication device 18 may be an internal or external component of the first electric drive unit 14, and the second communication device 20 may be an internal or external component of the second electric drive unit 16.

[0046] The first electric drive unit 14 may operate the first motor 32 with a control circuit board and a first gate driver 40. The second electric drive unit 16 may operate the second motor 3 with another control circuit board and a second gate driver 42. Each electric drive unit 14, 16 may include a pulse-width modulation generator to provide the sensor input signal 28, 30.

[0047] The period for the sensor input signal 28, 30, the start time of a period for the sensor input signal 28, 30, the timing of the sensor input signal 28, 30, and / or a frequency of the sensor input signal 28,30 may be detected and adjusted. In some embodiments, the period, frequency, and / or timing information of the pulse-width modulation output signals 36, 38 may also be detected and adjusted. For example, the adjustments of the sensor input signal 28, 30 and the pulse-width modulation output signals 36, 38 may be implemented in a continuous loop.

[0048] An adjustment for the sensor input signal 28, 30 may produce a pulse-width modulation output signal 36, 38 for the first communication device 18 with the first electric drive unit 14 to transmit to the first gate driver 40. Additionally, the adjustment for the sensor input signal 28, 30 may produce the pulse-width modulation output signal 36, 38 for the second communication device 20 with the second electric drive unit 16 to transmit to the second gate driver 42.

[0049] Each electric drive unit 14, 16 can detect, measure, and / or determine a beginning time difference with the other electric drive unit 14, 16. At least one electric drive unit 14, 16 may adjust the start time of the pulse-width modulation period with the pulse-width modulation generator. Each communication device 18, 20 may adjust at least five values for a motor control task (ex 10Ousec) or 1 msec to produce the period or frequency information for the pulse-width modulation output signal 36, 38: Previous period = int ( Previous period of pulse-width modulation output signal 36, 38 / 0.01 usee); Present period = int ( Present period of pulse-width modulation output signal 36, 38 / 0.01 usee); Next period = int ( Next period of pulse-width modulation output signal 36, 3810.01 usee ); Start time of period; and Start time of sensor input signal 28, 30.

[0050] With the increase of 0.01 usee or decrease of 0.01 usee of the pulse-width modulation period implemented by the pulse-width modulation generator of the electric drive unit 14, 16, the electric drive unit 14, 16 may control the pulse-width modulation output signal 36, 38. The sensor input signal 28, 30 may continue to be adjusted for improved operation of the motors 32, 34.

[0051] To synchronize, shift, and change the frequency of the sensor input signal 28, 30, assigned high-speed communication BUS such as the SPI to monitor the other communication devices 18, 20 may be provided. Reference Signs 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 toM tos tl, toi motor vehicle drive system first electric drive unit second electric drive unit first communication device second communication device communication link ground axle sensor input signal sensor input signal first motor second motor pulse-width modulation output signal pulse-width modulation output signal first gate driver second gate driver master start slave start master send / read

Claims

1. A method for operating a drive system (12) for an at least in part electrically operated motor vehicle (10), the method comprising:- detecting at least one of a period for a sensor input signal (28, 30), a timing of the sensor input signal (28, 30), or a frequency information of the sensor input signal (28, 30);- determining an adjustment for the sensor input signal (28, 30) for a first communication device (18) or a second communication device (20), wherein the first communication device (18) is connected to a first electric drive unit (14) and the second communication device (20) is connected to a second electric drive unit (16);- transmitting from the first communication device (18) to the second communication device (20) the adjustment for the sensor input signal (28, 30); and- executing the adjustment for the sensor input signal (28, 30).

2. The method according to claim 1, whereinthe adjustment for the sensor input signal (28, 30) comprises at least a timing of the period for the sensor input signal (28, 30).

3. The method according to claim 1 or 2, whereinthe adjustment for the sensor input signal (28, 30) comprises at least a frequency of the sensor input signal (28, 30).

4. The method according to any one of claims 1 to 3, whereinthe adjustment for the sensor input signal (28, 30) comprises a first duty cycle for the first sensor input signal (28) of the first communication device (18).

5. The method according to any one of claims 1 to 3, whereinthe adjustment for the sensor input signal (28, 30) comprises a second duty cycle for the second sensor input signal (30) of the second communication device (20).

6. The method according to any one of claims 1 to 4, whereintransmitting the adjustment for the sensor input signal (28, 30) for the first communication device (18) or the second communication device (20) is at a high speed.

7. The method according to any one of claims 1 to 5,whereindepending on the detected sensor input signals (28, 30) and determined adjustment for the sensor input signals (28,30), the first electric drive unit (14) and the second electric drive unit (16) are synchronized.

8. A computer program product comprising program code means for performing a method according to any one of claims 1 to 7.

9. A non-transitory computer-readable storage medium comprising at least the computer program product according to claim 8.

10. A drive system (12) for an at least in part electrically operated motor vehicle (10), comprising at least a first motor (32), a second motor (34),a first electric drive unit (14), a second electric drive unit (16), a communication link (22), wherein the first motor (32) is connected to the first electric drive unit (14) and an axle (26), which is connected to a first communication device (18), and the second motor (34) is connected to the second electric drive unit (16) and the axle (26), which is connected to a second communication device (20),wherein the drive system is configured for performing a method according to any one of claims 1 to 7.15

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