Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
  • H02P6/14—Electronic commutators
  • H02P6/15—Controlling commutation time
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
  • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
  • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
  • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
  • H02P23/14—Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/60—Other road transportation technologies with climate change mitigation effect
  • Y02T10/64—Electric machine technologies in electromobility

Definitions

• the present invention relates to a method for operating an electrical machine with a converter and a control unit and a computer program for its implementation.
• Electrical machines can be operated as a motor on a power converter, in particular an inverter or inverter, which is fed by a DC voltage circuit.
• a power converter in particular an inverter or inverter, which is fed by a DC voltage circuit.
• inverters also referred to as traction inverters
• switching elements in particular semiconductor switches such as MOSFETs or IGBTs, for example by way of block commutation.
• BRM boost recuperation machines
• the absence of electrical isolation means that switching operations, ie the opening and closing of switching elements, can result in potential jumps in the logic supply.
• switching operations ie the opening and closing of switching elements
• the measurement of the phase current and / or the measurement of the rotor position of the rotor of the electrical machine can be disrupted in this way.
• This can be remedied by calculating the measurement time depending on the switching processes and adapting it variably.
• the search for undisturbed measurement times is time-consuming.
• negative aspects for the regulation due to non-equidistant measurements as well as additional effort for plausibility checks due to safety aspects according to ISO 26262 can arise.
• the ISO 26262 standard is generally used, in which the so-called “Automotive Safety Integrity Level” (ASIL) - these are safety levels in vehicles - are defined .
• ASIL Automotive Safety Integrity Level
• the generated torque is usually assigned a safety load, i.e. the generated torque must have a specified accuracy.
• the torque of an electrical machine can be determined using measured phase currents and corresponding machine equations; a torque sensor is then not necessary.
• the phase currents are usually included in the current control, by means of which a target torque can be achieved. Inaccurately recorded phase currents therefore lead to an inaccurately set torque, which in turn can result in the violation of safety goals according to ISO 26262.
• the specific switching times are adapted to the specific measurement times in such a way that the semiconductor switches are not closed and opened in a specific interval around a specific measurement time.
• the interval can in particular be a time interval or a rotation angle interval (of the rotor).
• the interval is chosen to be as long as possible so that the time for the measurement is sufficient, but on the other hand it is chosen as short as possible so that the measurement does not unnecessarily delay the opening or closing of the semiconductor switch.
• a time interval of 10 ps, in particular 5 ps, is preferably used.
• the specific switchover time is shifted outside the specific interval. This is advantageous because it prevents the measurement from being influenced or disturbed by the switching of the semiconductors.
• the specific switchover time can be shifted in such a way that the specific switchover time is shifted to the last possible time before the interval or to the earliest possible time after the interval. This can also depend on the position of the switching point in the interval, i.e. it is closer to the beginning or the end.
• a switching time of a first semiconductor switch (in particular high side) of a branch of the converter is shifted before the time interval and a switching time of a second semiconductor switch (in particular lowside) of the branch of the converter is shifted after the time interval.
• the shift preferably takes place symmetrically to the actual switching time. On in this way, the occurrence of torque fluctuations (ripples) can be avoided.
• the determined measurement times are advantageously equidistant in time.
• the measurements are therefore carried out at regular time intervals. This means that measured values that are equidistant over time can be obtained in order, for example, to meet the requirements mentioned at the beginning.
• the sensor is advantageously used to measure a phase current flowing through one of the stator windings or a rotor position of the rotor.
• the phase current can be measured, for example, using so-called shunts.
• shunts are not installed directly in the phases of the stator windings, but rather, for example, in a low-side path and / or in the high-side path of the converter.
• the phase current can only be measured when the lowside path is switched on. The same applies to the highside path.
• the stator winding is advantageously operated in block commutation. From a certain speed, the so-called corner speed, the electrical machine reaches the so-called voltage limit. In this case, the generated pole wheel voltage is greater than the voltage applied to the phases. So that the machine can generate a motor torque above this speed, it is operated in so-called field weakening mode. Since this operating mode has a lower efficiency, the corner speed should be as high as possible, which can be achieved, for example, by a higher phase voltage. Corresponding machines in the field weakening range are therefore controlled in block mode, since a greater effective voltage can be generated on the stator winding in this area than with PWM control.
• block commutation With block commutation, no fixed control frequency (i.e. no PWM commutation) is used, but the semiconductor switches are synchronized with the electrical angular speed of the electrical machine. shaped on and off. Different block widths can be implemented depending on the number of phases.
• the type of control that generates the greatest effective phase voltage is the so-called 180 ° block commutation, in which the high-side and low-side semiconductor switches are switched on for an electrical angle of 180 ° per phase within one electrical revolution.
• the specific switching times and the specific measuring times are advantageously determined by a control unit.
• the control unit initially calculates or determines, for example, the measurement times.
• the control unit then calculates or determines the switching times of the semiconductor switches and compares the determined measurement times with the determined switching times. If a specific switchover point in time lies in an interval around a specific measurement point in time, the control unit determines whether the switchover point in time is shifted to a point in time before or to a point in time after the interval.
• control unit according to the invention for example a control unit of a motor vehicle, is set up to carry out a method according to the invention.
• Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, such as hard drives, flash memories, EEPROMs, DVDs, etc.
• a program can also be downloaded via computer networks (Internet, intranet, etc.).
• FIG. 1 shows schematically an electrical machine with a converter in which a method according to the invention can be carried out.
• FIG. 2 schematically shows a sequence of a method according to the invention in a preferred embodiment.
• FIG. 1 an electrical machine 100 with a converter 110 is shown schematically, in which a method according to the invention can be carried out.
• the electrical machine has (in a stator, not shown) six phases (windings) that form two three-phase groups as subsystems and are denoted by U 1, V1 and W1 and U2, V2 and W2.
• U 1, V1 and W1 and U2, V2 and W2 For example, an electrical phase offset of 30 ° applies between the two three-phase subsystems U 1, V1, W1 and U2, V2, W2.
• a three-phase group is characterized by an electrical connection of the phase windings in the stator, here for example a common star point, but is not electrically connected to phases of other three-phase groups in the stator and can therefore have its own control scheme, which in principle is different from control schemes of other three-phase groups can.
• the converter 110 has two parts 111 and 112, each designed as a conventional bridge rectifier, and six (unspecified) switching elements, e.g. semiconductor switches such as MOSFETS, and each for controlling (ie for connecting to the DC voltage connections of the converter) one of the three-phase subsystems U1, V1, W1 or U2, V2, W2 are used.
• the converter 110 with a positive and a negative connection, for example in an on-board network, is connected via two (unspecified) capacitors integrated into a vehicle as DC voltage connections.
• a control and / or regulating unit 150 is shown as an example, which is used to control the converter 110, in particular to open and close the switching elements. It goes without saying that such a device can also be integrated into the converter 110.
• phase currents can be measured or recorded, for example, by means of a phase current sensor or a current measuring device - such a device is schematically and exemplarily denoted by 120.
• switching processes i.e. the opening and closing of switching elements, can result in potential jumps in the logic supply.
• the measurement of the phase current of the electrical machine 100 can be disrupted in this way.
• FIG. 2 a sequence of a method according to the invention is shown schematically in a preferred embodiment.
• the electrical machine 100 with converter 110 as shown in FIG. 1 can be used.
• the two three-phase subsystems U1, V1, W1 is shown, which is operated here with 180 ° block commutation.
• FIG. 2a of FIG. 2 certain time intervals around certain measuring times of the measurement of the phase current are shown. Measurements take place here by way of example at the times 50 ps, 150 ps, 250 ps, 350 ps and 450 ps. A total of five measurements are therefore carried out (for the present speed) during one complete revolution of the rotor. There is an equidistant distance of 100 ps between the specific measurement times.
• the time interval around a specific measurement time is 10 ps, with the time interval starting 5 ps before a specific measurement time and ending 5 ps after a specific measurement time (see arrow).
• the time interval around the The correct measurement time 250 ps thus begins at time 245 ps and ends at time 255 ps.
• the high-side FET is already switched off at time 245 ps, which represents the last possible time before the time interval around the specific measurement time at 250 ps.
• the low-side FET is not switched on at time 250 ps, but only at time 255 ps, which is the earliest possible time after the time interval around the specific measurement time at 250 ps.
• this reduces the length of the available voltage pointer.
• the switching times can also be shifted depending on the angle, i.e. e.g. at 175 ° and 185 °. It goes without saying, however, that both the high-side FET and the low-side FET can also be switched together before or after the interval. However, this changes the control angle, which leads to a torque ripple.
• the calculation of the specific measurement times and the specific switchover times is carried out by the control unit 150 (see FIG. 1). To- The control unit 150 then determines whether a specific switchover point in time lies in the specific interval around a specific measurement point in time and shifts the switchover point in time if necessary.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)
• Control Of Ac Motors In General (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=73476116

Family Applications (1)

Country Status (5)

Family Cites Families (4)

• 2019
  • 2019-12-06 DE DE102019219034.0A patent/DE102019219034A1/de active Pending
• 2020
  • 2020-11-17 WO PCT/EP2020/082333 patent/WO2021110404A1/de unknown
  • 2020-11-17 US US17/782,690 patent/US20230009497A1/en active Pending
  • 2020-11-17 EP EP20808344.4A patent/EP4070447A1/de active Pending
  • 2020-11-17 CN CN202080083703.9A patent/CN114788163A/zh active Pending

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