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
  • H02P6/16—Circuit arrangements for detecting position
  • H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
  • H02P6/185—Circuit arrangements for detecting position without separate position detecting elements using inductance sensing, e.g. pulse excitation
• • 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
  • H02P6/20—Arrangements for starting
  • H02P6/22—Arrangements for starting in a selected direction of rotation

Definitions

• the invention is based on a method for starting a brushless DC motor according to the preamble of claim 1.
• Brushless DC motors so-called BLDC motors
• BLDC motors are electronically commutated, the semiconductor switches of the switching device arranged in a bridge circuit being switched on (closed) by a control device as a function of the rotary position of the rotor according to a predetermined commutation pattern for the consequent energization of the individual winding phases or phases of the stator winding. or locked (opened).
• the commutation ensures that the angular relationship of 90 ° is electrically maintained between a stator flux vector generated by the stator winding and the rotor flux vector, and thus the rotor of that revolving stator field or stator flux vector is driven.
• BLDC motors are also known in which voltages induced by rotation are evaluated to determine the rotor position (DE 37 09 168 AI).
• the disadvantage here is that no voltage is induced when the motor is at a standstill, the rotor position is therefore not known, and the motor start-up is therefore difficult, in particular in the case of highly variable or high loads.
• the current rise time i.e. the time that elapses until the current flowing in the winding phase reaches a current threshold
• the from the m Current time rise times are read into an energization table for the stator winding, which contains the energization pattern of the m winding phases required for commutation, in order to let the rotor rotate in the desired direction of rotation.
• the combination of the phase energization associated with the time vector is implemented by corresponding control signals which are applied to the control inputs of the semiconductor switches of the switching device. The control signals are then varied in the manner predetermined by the commutation pattern, so that a corresponding torque is exerted on the rotor and the rotor turns up.
• the method according to the invention with the features of claim 1 has the advantage of more precise determination of the rotor position in the engine idle state with less control engineering effort.
• the available signal swing is better used, so that the test or
• Test currents in the winding phases or strands can be made smaller or shorter, which enables a higher drive torque due to the longer current supply times for the torque generation. If the rotor position is determined, then according to further embodiments of the method according to the invention, the possible drive torque can be increased further, both with an active and a passive load, with a smaller number of further test current pulses.
• a current pulse is applied to the stator winding, which generates a torque-generating stator flux vector, the phase position of which is electrically offset by 90 ° in a rotor direction of rotation selected as the direction of force compared to the determined rotor position.
• a smaller number of further test current pulses are applied to the stator winding to check the rotor position. If the rotor position is unchanged, the torque-generating stator flux vector is generated again by applying a current pulse.
• a torque-generating stator flux vector is generated by means of a current pulse, the phase position of which is in turn electrically offset by 90 ° from the newly determined rotor position. This process continues until a sufficient rotor speed is recognized, after which a switch is made to another known method for sensorless determination of the rotor position. This eliminates the cyclical test current impulses, and the motor can be used to its full extent.
• connection of the further test current pulses can be carried out in different ways. If the direction of rotation of the motor is known, then according to a preferred embodiment of the invention the test current pulses are applied in such a way that a first further test current pulse unites one generates the first stator flux vector, the phase position of which corresponds to the determined rotor position, and a second further test current pulse generates a second stator flux vector, the phase position of which is an electrical angular step in the direction of force with respect to the first
• Stator flow vector is offset.
• the direction of force is the known direction of rotation of the rotor.
• the omancurrent rise times associated with the two stator flux vectors are measured and compared with one another, and the phase position of the stator flux vector with the smallest current rise time is determined as the new rotor position. Then a current pulse is again applied to the stator winding, which generates a torque-generating stator flux vector, the phase position of which is electrically offset by 90 ° from the new rotor position in the direction of force.
• the further test current pulses are applied in such a way that a first further test current pulse generates a first stator flow vector which is 90 ° electrically plus an electrical angular step against the direction of force opposite the phase position of the previously generated torque-generating stator flow vector is offset, and a second further and a third further test current pulse each generate a second and third stator flux vector which is offset by one electrical angular step in the direction of force relative to the first and second stator flux vector, respectively.
• the current rise times associated with the stator flow vectors are again measured and compared with one another, and the phase position of the stator flow vector with the smallest The current rise time is determined as the new rotor position.
• a current pulse is then applied to the stator winding, which generates a torque-generating stator flux vector, the phase position of which is electrically offset by 90 ° in relation to the new rotor position in the direction of force.
• the determination of the sequence of applying the further test current pulses described above has the following advantages: Before applying a test current pulse, it is necessary that the phase currents generated in the winding phases have decayed from the previous test current pulse. This ensures that the measurement results obtained with the individual test current pulses are not falsified by an existing phase current. After the last test current pulse has been applied and the current rotor position is known, the current pulse for generating the torque-generating stator flux vector can be applied directly. A decay of the phase currents in the stator winding is no longer necessary in this case.
• the stator flow vector generated by the last test current pulse is always 30 ° electrical - if the rotor position has been confirmed - and 90 ° electrical - if a new rotor position has been recognized - next to the stator flow vector which is used for the subsequent one Torque generation is required to move the rotor. If the stator flux vector generated by the last test current pulse is only 30 ° electrically adjacent to the torque-generating stator flux vector, only one of those energized by the last test current pulse is required to generate the torque-generating stator flux vector Winding phases of the stator winding can no longer be horrd.
• one of the winding phases energized by the last test current pulse for the generation of the torque-generating stator flux vector can at least remain energized to generate the torque-generating stator flux vector.
• Test current pulses and the times for torque generation is improved without the time for the torque generation has been extended.
• the phase positions and the associated current rise times of successive stator flux vectors are stored, and the stored values of the previous stator flux vector are compared with those of the following one
• Stator flux vector overwritten if the current rise time associated with the subsequent stator flux vector is shorter than the current rise time associated with the previous stator flux sector.
• This method variant not all current rise times and assigned phase positions of the stator flux vectors have to be stored. It is sufficient if the current rise times and the phase positions of the generated stator flux vectors are stored for two immediately successive test current pulses, so that the memory requirement is limited to only two memories.
• the current memory is always stored in the first memory
• Current rise time and the current phase position of the stator flow vector just generated are written in and a comparison logic operating in the manner described above ensures that the phase position of the stator flow vector to which the smallest current rise time is associated is always stored in the second memory.
• Fig. 1 is a block diagram of a device for operating a brushless
• FIG. 2 shows a circuit diagram of the switching device in the device according to FIG. 1,
• FIG. 3 shows a commutation pattern stored in the control device of the device according to FIG. 1,
• FIG. 1 shows a block diagram of a device for operating a brushless DC motor 10 on a DC voltage network with the DC network voltage U B.
• the DC motor 10 has, in a known manner, a stator 11 with a three-phase stator winding 12 in the exemplary embodiment (FIG. 2) and a rotor 13 excited by permanent magnets. Alternatively, the rotor can also be excited by direct current.
• a switching device 14 which is controlled by a control device 15
• the three winding phases or strands 121, 122, 123 of the three-phase stator winding 12 are consequently energized in such a way that a stator field rotates in the stator, which is 90 ° electrical to the flow vector of the rotor 13 leads ahead in the direction of rotation.
• the instantaneous rotor rotation position is determined with the aid of the rotationally induced voltage in the winding phases 121-123 of the stator winding 12, which is indicated by the voltage measuring line 27 shown in broken lines in FIG. 1.
• the switching device 14 comprises a plurality of semiconductor switches, which in the exemplary embodiment are designed as MOS-FETs and are combined in a two-way bridge circuit.
• six semiconductor switches T1-T6 are present in the switching device 14, the control inputs of which are connected to the control device 15.
• Control signals are generated (in the left part of the table in FIG. 3) which are applied to the individual semiconductor switches T1-T6 and thereby energize the winding phases 121-123 of the stator winding 12, as shown in the right part of the table in FIG. 3.
• the plus sign means positive energization in the direction of arrow 16 in FIG. 2, a minus sign means opposite energization.
• a box that has not been filled in represents a currentless winding phase. If, for example, the semiconductor switches T1, T4 and T6 are activated, they switch through and a current flows in the winding phase 121 in the direction of arrow 16 and in the winding phases 122 and 123 in the opposite direction of the arrow.
• a controlled sensorless start-up When the motor is at a standstill, the problem is that no voltage is induced in the stator winding 12 at zero speed, so that the sensorless method for determining the rotor position cannot be used by evaluating the phase or phase voltages of the motor 10.
• further components are provided for a controlled sensorless start-up. These include a measuring shunt 17 through which the total current of the stator winding 12 flows, an amplifier 18, a comparator 19, at one input of which there is a reference voltage Uref, a timer 20 .
• test current pulses are applied to the three-phase stator winding 12, which generate stator flux vectors in the stator which are electrically offset from one another by 60 °.
• the semiconductor switches T1-T6 of the switching device 14 are activated in succession with the switching signals indicated in the left part of the table in accordance with FIG. 3.
• the required control signals of the semiconductor switches T1-T6 are shown in the left part of the table.
• a “1” here means a closed semiconductor switch, that is to say a switched-through MOS-FET, a "0" stands for a blocked MOS-FET, that is to say an open semiconductor switch T1-T6.
• the test current pulses are of such a short duration that the torques generated in the motor are so small that the rotor 13 does not move due to its moment of inertia and the friction.
• the winding phases 121, 122 and 123 of the stator winding 12 are energized in the manner indicated in the right part of the table in FIG. 3, a stator flux vector being generated in the stator, the phase position ⁇ of which in the middle column of the table in FIG 3 is entered.
• the semiconductor switches T1, T4 and T6 are activated.
• a time-increasing phase current flows in the direction of arrow 16, via the
• the total current flowing through the measuring shunt 17 results in a measuring voltage which is fed to the comparator 19 via the amplifier 18. If the voltage tapped and amplified at the measuring shunt 17 exceeds the reference voltage U ref , the comparator 16 switches on
• the time ti measured by the timer 20 is stored together with the phase position ⁇ i of the stator flux vector generated by the test current pulse Ii. The same process is repeated when the second test current pulse I 2 is applied by actuating the
• Stator flux vectors 25 have been generated and for each stator flux vector 25 the current rise time t n and the phase position ⁇ n have been stored. Now the current rise times are compared with each other, and the phase position of the stator flux vector, which is the smallest
• This rotor position electrically defines a sector 26 of 60 °, the axis of symmetry of which is determined by the phase position ⁇ n of the current flow vector 25. 4, the six current flow vectors 25 and the associated sectors 26 are shown.
• a total of 2 m test current pulses generate 2 m stator flux vectors 25 which are electrically offset from one another by 180 ° / m and electrically define 2 m sectors 26 with an angular width of 180 ° / m.
• the current time t n measured by the timer 20 is always in the memory 21 written and assigned to the phase position ⁇ n of the current stator flux vector.
• the current rise time ti stored in the first memory 21 and the associated phase position ⁇ i of the stator flux vector generated by the test pulse Ii are written into the second memory 22.
• the comparison logic 23 When the second test current pulse I 2 is applied, the current rise time t 2 is measured in the total current of the stator winding 12 and this is written into the memory 21 together with the associated phase position ⁇ 2 of the stator flux vector 25.
• the comparison logic 23 now compares the current rise time ti contained in the second memory 22 with the current rise time t 2 written into the first memory 21. If the current rise time t 2 is less than the current rise time ti, the comparison logic 23 opens the gate circuit 24, and the memory content of the second memory 22 is changed from that Memory content of the first memory 21 overwritten.
• the gate circuit 24 remains closed and at the next test pulse I 3 the memory content of the memory 21 is overwritten with the current rise time t 3 and the phase position ⁇ 3 of the stator flux vector generated by the third test current pulse I 3 .
• the comparison logic 23 compares the current rise times t n + ⁇ and t n stored in the two memories 21, 22 and, as described above, opens the gate circuit 24 or not.
• Test current pulses I n have been applied to the stator winding 12, the smallest current rise time and the phase position of the associated stator flux vector are stored in the second memory 22. This phase position determines the sector 26 in which the maximum chain between the rotor flux and
• Stator flux occurs, and thus defines the sector 26 in which the rotor 13 is currently located. It should be noted that the time period between successive test current pulses is selected such that the phase currents generated by a test current pulse in the stator winding 12 have decayed before the next test current pulse is applied. This ensures that the current rise times when the individual test current pulses are switched on are not falsified by an existing phase or phase current.
• Phase angle 90 ° electrically in a direction of force selected rotor direction of rotation is offset from the specific rotor position.
• the rotor position is checked by applying further test current pulses to the stator winding 12, that is to say it is checked whether the rotor 13 maintains its predetermined position due to the applied current pulse for torque formation or changed to maintain the drive torque.
• the current rise time is measured.
• a second further test current pulse is applied to the stator winding 12, which generates a second stator flux vector 252, the phase angle ⁇ of which is an electrical angle step, ie 60 ° in the exemplary embodiment electrically, is offset relative to the first stator flux vector 251 against the direction of force.
• the current rise time associated with this stator flow vector 252 is also measured.
• the two current rise times are again compared with one another and the phase position ⁇ of the stator flux vector 251 or 252 with the smallest current rise time is determined as the new rotor position.
• the phase positions ⁇ of the stator flux vectors 251, 252 generated by the test current pulses and the associated rise times t are written back into the memories 21, 22 and compared with one another by the comparison logic 23.
• the phase position of the stator flux vectors 251, 252 generated by the test current pulses and the associated rise times t are written back into the memories 21, 22 and compared with one another by the comparison logic 23.
• a known direction of rotation can be assumed if the possible load torque is not greater than the available motor torque, ie that the motor does not necessarily have to rotate when the torque-forming current pulses are applied, but is also not moved by the load in the opposite direction of rotation. Is the direction of rotation unknown, so - as shown in FIGS. 9 and 10 - in addition to the two further test current pulses, a third further test current pulse is applied to the stator winding 12, which generates a stator flux vector, the phase angle ⁇ of which is electrical
• Angular step that is to say electrically in the exemplary embodiment by 60 °, is offset against the direction of force with respect to the stator flux vector 252 generated by the second test current pulse.
• the current rise time is again measured here, and the phase position ⁇ of the stator flux vector with the smallest current rise time determines the new rotor position.
• a current pulse is again applied to the stator winding 12 in the same way, which generates a torque-generating stator flux vector 25 'with a phase position that is 90 ° ahead of the newly determined rotor position in the direction of the force (FIG. 10).
• the current pulse for generating a torque-generating stator flux vector can immediately follow the last test current pulse. A decay of the phase or phase currents is not necessary in this case.
• the further test current pulses are used to check the rotor position and to increase the drive torque for the rotor in the above-described connection 13 proceeded in a modified manner: If the direction of rotation of the rotor is known (FIGS. 7 and 8), the further test current pulses are applied in such a way that a first further test current pulse generates a first stator flux vector 251a, the phase position of which ⁇ coincides with the rotor position, as created by applying the first six
• Test current pulses were determined. Subsequently, a second further test current pulse is applied to the stator winding 12, which generates a second stator flux vector 252a, the phase position of which is offset from the first stator flux vector 251a by an electrical angular step, i.e. 60 ° electrically, in the direction of force, which in turn coincides with the direction of rotation.
• the reference numerals for these two stator flux vectors are shown in parentheses in FIG. 7.
• the current rise times of both test current pulses are measured and the phase position of the stator flux vector to which the smallest current rise time belongs is determined as the new rotor position. Then a current pulse is again applied to the stator winding 12 for generating torque.
• the current flow vector 25 generated with the test current pulse last applied is 90 ° electrically adjacent to the stator flow vector 25 required for torque generation '(shown in dashed lines in Fig. 8) and to apply the torque-forming stator flux vector 25' leading 90 ° in the phase position, a winding phase can remain energized.
• the phase position ⁇ 180 ° electrical
• a total of three further test current pulses are applied to the stator winding 12 in such a way that - as shown in FIG. 9 - a first further test current pulse 251b generates a stator flux vector 251b. which is offset from the direction of force in relation to the phase position of the torque-forming stator flux vector 25 'by 90 ° electrically plus a half electrical angular step, that is to say 30 ° electrically.
• the associated current rise time is measured and stored, in the assumed example of FIGS.
• a second further test current pulse is then applied, which generates a stator flow vector 252b, which is offset in the direction of force by an electrical angular step, ie 60 ° electrical, with respect to the first stator flow vector 251b.
• the associated current rise time is also measured here.
• a third further test current pulse is applied, which generates a third stator flux vector 253b, the phase position of which is in turn offset by an electrical angular step, that is to say by 60 ° electrically, with respect to the second stator flux vector 252b.
• stator flux vector 213b which was generated by the test current pulse last applied to the stator winding 12, is 30 ° electrically adjacent to the stator flux vector 25 'required for torque generation if the same rotor position is recognized as before, and 90 ° electrically adjacent to the stator flux vector 25 ', which is required for the subsequent torque generation when the rotor position has changed.
• the comparison of the current rise times of the three test current pulses is again carried out here by the comparison logic 23, and the phase position ⁇ of the stator flux vector last written into the second memory 22, which determines the sector 26 in which the rotor 13 is located, is fed to the control device 15.
• the three test current pulses and the current pulse for torque generation are repeatedly applied after a certain time and the same procedure is carried out until the control device 15 detects a sufficient speed of the rotor 13.

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

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• 2001
  • 2001-12-19 DE DE10162380A patent/DE10162380A1/de not_active Withdrawn
• 2002
  • 2002-12-16 EP EP02794997A patent/EP1459436A2/de not_active Withdrawn
  • 2002-12-16 JP JP2003553701A patent/JP4673553B2/ja not_active Expired - Fee Related
  • 2002-12-16 US US10/472,750 patent/US6885163B2/en not_active Expired - Fee Related
  • 2002-12-16 WO PCT/DE2002/004582 patent/WO2003052919A2/de active Application Filing

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