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
  • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
  • H02P21/12—Stator flux based control involving the use of rotor position or rotor speed sensors
• • 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
  • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
  • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
  • H02P21/141—Flux estimation
• • 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

Definitions

• the invention relates to a method for sensorless, electrical rotor position measurement of a permanently excited synchronous machine, which is fed via converters, by means of measurement signals which are fed to an evaluation device which calculates the electrical rotor position from the angle dependence of the current space vector with an impressed stator flow pattern, the magnitude curve of the differential current space vector being approximately sinusoidal fluctuates twice the value of the sought electrical rotor position angle, and a circuit arrangement for performing the method.
• Another feature of the method according to the invention is that a star-shaped stator flow pattern running through the zero point is embossed, which on average over time generates almost no torque in the synchronous machine. This measure ensures that devices coupled to the synchronous machine, for example an electromechanical vehicle brake which can be actuated by the synchronous machine, are not loaded.
• Another feature of the invention provides that certain frequency components in the power density spectrum are reduced. Even if the inertia of the rotor prevents the synchronous machine from shaking during energization - the mean value of the torque over time is zero - the magnetostriction in the stator plate nevertheless ensures an audible noise. How much of this can be perceived externally largely depends on the resonance frequencies of the housing. Skillful energization of the synchronous machine with a frequency-optimized flow pattern can, however, be avoided to excite the resonance frequencies.
• the rotor position is determined by cross-correlating the measured amount curve with a tabularly stored amount curve. If only the maximum in the course of the amount is used for evaluation, this is inaccurate since only one measured value is used by many. The disturbance of only one measured value could render the result unusable.
• the correlation with a given course processes all measured values and in this way achieves much better accuracy: and immunity to interference.
• the angle of rotation sought corresponds to the index of the maximum value in the cross-correlated.
• a particularly simple evaluation is achieved in that the rotor position is determined by zeros and extreme values of the measured amount curve.
• an exact evaluation by means of arithmetic transformation of at least two sampled phase currents in the magnitude curve and phase curve is achieved in that the magnitude curve is calculated from the phase currents by inverse Clarcke and Park transformation (ICPT).
• ICPT inverse Clarcke and Park transformation
• a simplified evaluation, in which the amount curves can even be determined completely without the use of processors, can be achieved in that an estimate of the amount curve is determined from the total current of the converter with the aid of a suitable flow pattern.
• the converter transforms its supply current into the estimated value of the magnitude component by applying special base vectors at the sampling times.
• the resolution remains limited to 60 ° el. Rotor position angle when using a three-phase motor.
• Another advantageous further development of the invention provides that instead of the temporal change of the current space pointer, differences of current space pointers at different times of the flow pattern or differences of current time areas can be used to determine the course of the amount. Differences of current space pointers and differences of current time areas enable a higher resolution of the sought electrical rotor position angle than the evaluation of the temporal change of the current space pointer.
• Stator voltage space vector by vector modulation and pulse width modulation is composed of several base vectors.
• the vector modulation assembles the stator flow direction from the base vectors that can be represented by the converter, the pulse width modulation stipulating the duration for which these base vectors must be present.
• a circuit arrangement for sensorless, electrical rotor position measurement of a permanently excited synchronous machine, with a control signal generating device, a converter for feeding the synchronous machine and an evaluation device for evaluating the measurement signals generated by the current measuring device, is characterized in that the control signal generating device has a pattern generator for generating a flow pattern and contains a scanning signal generator, which provides control signals for the evaluation device, that the converter contains a flow model of the synchronous machine and a current measuring device, the flow model from the Flow pattern generates a voltage pattern, which is impressed into the synchronous machine and the current measuring device determines the current flow pattern that occurs and the evaluation device calculates the course of the amount of the differential current space pointer from the current flow pattern and from this derives the sought-after electrical rotor position angle to 360 °.
• control signal generating device contains a clock generator, the clock signal of which is fed to a counter, the counter status of which is made available to both the pattern generator and the scanning signal generator, the pattern generator specifying a stator flow pattern and the scanning signal generator timing for sampling Prescribes current profiles from which the sought electrical rotor position angle is derived.
• a constant time cycle makes it possible to simplify the known method mentioned above, according to which the inductance which is dependent on the rotor position must be determined. The reciprocal of the inductance is proportional to the change in current per unit of time. If constant time units are used, the procedure is simplified to evaluate the change in current.
• the stator flux pattern can be calculated offline and can be reproduced from a memory without change.
• the prerequisites for this are the constant timing and the stationary synchronous machine.
• the flow model preferably generates a voltage pattern from the flow pattern by a motor flow observer or a flow measuring device, which voltage pattern is fed to a vector pulse width modulator.
• the synchronous machine represents an inductance in the model and therefore builds up its flow pattern only with a delay when the voltage pattern is applied. Due to the variable inductance, the delay time itself depends on the rotor position angle. This is taken into account by a real flow measurement via the current flow pattern that occurs, or is simplified by a low-pass filter with a constant delay.
• the vector pulse width modulator generates control signals for a multiphase bridge, which impresses the current pattern in the synchronous machine, the phase currents of the multiphase bridge or a supply current of the multiphase bridge or the “high” or “low” side in the multiphase bridge occurring bridge currents are measured.
• the current profiles to be measured are selected using a switch. While the phase currents can be evaluated at any time, the "high” or “low” soapy current measurement in the multiphase bridge only delivers when the current in question is energized . Bridge branch a sensible measured value.
• the supply-side current measuring device manages with a single current measurement, but only delivers a usable estimate if a special control signal vector with the correct projection direction is applied.
• the evaluation device has a converter which transforms the current profile selected by the switch and the predetermined stator flow pattern into an absolute value profile of the current space vector. This measure enables the electrical rotor position angle to be clearly detected at 360 °.
• the evaluation device contains a scanner with difference formation, to which the magnitude curve of the current component and the times supplied by the scanning signal generator are supplied and in which the magnitude curve of the differential current space vector is formed.
• the asymmetry of the saturation, which is dependent on the rotor position, is extracted by the difference measurement.
• the evaluation device contains a current profile evaluation unit which determines the sought electrical rotor position angle from the amount profile of the differential current space pointer.
• Fig. 1 is a simplified circuit diagram of a
• FIG. 2 shows the structure of the control signal generating device shown schematically in FIG. 1;
• FIG. 3 shows the structure of the converter shown schematically in FIG. 1 with a current measuring device
• Fig. 4 is a schematic representation of a three-phase synchronous machine
• Fig. 5 shows the structure of the evaluation device shown schematically in Fig. 1.
• the circuit arrangement shown in FIG. 1 essentially consists of a control signal generating device 101 for generating input or control signals, as well as a converter 102, the phase currents for a provides permanently excited synchronous machine 103 and measurement signals for a downstream evaluation device 104, the output signals of which represent the sought electrical rotor position angle of synchronous machine 103.
• the control signals generated by the control signal generation device 101 are made available both to the converter 102 and to the evaluation device 104.
• the control signal generating device 101 has a clock generator 1, a counter 2, a pattern generator 3 and a scanning signal generator 4.
• the clock signals a generated by the clock generator 1 are fed to the counter 2, the output signals b of which are passed on both to the pattern generator 3 and to the scanning signal generator 4.
• the output signal c of the pattern generator 3 specifies a stator flow pattern for the synchronous machine 103, which consists of differential stator flow space pointers arranged in a row
• the scanning signal generator 4 generates signals which identify positive and negative sampling times tp, tn for the downstream evaluation device 104, which is shown in more detail in FIG. 5 is shown.
• the stator flux pattern c predetermined by the pattern generator 3 is of a star-shaped structure and specifies the same path for flow establishment and degradation, the zero point being repeated repeatedly, so that the area enclosed by the pattern or the moment impressed into the synchronous machine 103 is minimal is.
• the stator flow pattern can be run through clockwise and anti-clockwise, by averaging in the subsequent evaluation device 104 occurring delays can be compensated.
• the stator flux pattern also has a significant influence on the noise generated by magnetostriction in the synchronous machine and can advantageously be designed so that resonance points of the synchronous machine and connected housing parts are not excited. For this purpose, the power density spectrum of the stator flux pattern in the vicinity of the resonance frequencies must be minimized.
• the converter 102 shown in FIG. 3 contains a flow model 17 which consists of a motor flow observer (low-pass filter) 5, a switch 7, a subtractor 6 and a flow measuring device 8. Furthermore, the converter 102 has a vector pulse width modulator 9, a multi-phase bridge 11, a power supply 10 assigned to the multi-phase bridge 11, current measuring devices 12, 13, 14 and a changeover switch 15.
• the motor flow observer 5 receives the predetermined stator flow pattern c of the pattern generator 3 and uses it to generate an estimated stator flow pattern d.
• the flow measuring device 8 derives the measured stator flow pattern f from the measured phase currents k of the current measuring device 13.
• the measured stator flow pattern f is fed together with the estimated stator flow pattern d to the changeover switch 7, which forwards one of the two signals d, f to the subtractor 6 and thus selects between observing and measuring the stator flow pattern.
• the result of the subtraction which corresponds to the predetermined stator voltage pattern, is applied to the vector pulse width modulator 9, in which the for the Multi-phase bridge 11 required control signals h are generated.
• the vector modulation takes on the task of replacing the direction of the current stator voltage space vector in the stator voltage pattern with base vectors that can be represented by the multiphase bridge 11; the pulse width modulation determines how long these base vectors have to be applied in order to approximate the stator voltage pattern.
• the changeover switch 15 selects a measured current pattern e from the various current measuring devices 12 to 14.
• the synchronous machine 103 shown in FIG. 4 is fed with the phase currents m of the multiphase bridge 11 and, depending on the mechanical rotor position th, the number of stator teeth n and the number of pole pairs p, develops an overall flow pattern from the vectorial superposition of the stator flow pattern and the position-dependent rotor flux.
• This overall flow pattern mutually drives the synchronous machine into magnetic saturation, the current requirement in saturation being greater than without saturation. Because the occurrence of saturation depends on the electrical rotor position angle, the electrical rotor position angle can be uniquely determined from the current requirement with a known stator flow pattern.
• the evaluation device 104 shown in FIG. 5 consists of a converter 18, a scanner " with difference 19 and a current profile evaluation unit 20.
• the converter 18 generates the measured current flow pattern e and the predetermined stator flow pattern c by transformation Amount curve q of the current space vector.
• the converter 18 calculates the magnitude curve q of the current space vector from the measured current pattern e either by inverse Clarcke and Park transformation (ICPT) or approximately using the multi-phase bridge 11 by projecting the total current in the direction of the impressed stator flux component.
• ICPT inverse Clarcke and Park transformation
• the magnitude curve q is differentiated by the scanner 19 at the times tp and tn, which results in the differential magnitude curve r of the current space vector.
• the difference between current time areas can also take the place of the differential amount curve r.
• the current curve evaluation unit 20 finds the position of the larger maximum in the approximately sinusoidally fluctuating differential magnitude curve r, which has two maxima of different heights, which is directly proportional to the electrical rotor position angle thel sought. In addition, it outputs a plausibility signal pl, which assesses the quality of the calculated electrical rotor position angle thel.
• the location of the maximum can be found on the one hand by simply taking the zeros and extreme values into account, or by including all reference points by cross-correlation with a tabularly stored model amount curve.
• Zero points ⁇ and extreme values follow in an undisturbed measurement at periodic intervals. This makes use of the plausibility calculation: it generates for strong ones Irregularities in the sequence of an error in the plausibility signal pl, whereupon the measurement is repeated.
• a possible cause for deviations in the periodic intervals is an unwanted, externally impressed rotor rotation during the measurement.

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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 (5)

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• 2002
  • 2002-05-28 EP EP02774030A patent/EP1397858A1/de not_active Withdrawn
  • 2002-05-28 JP JP2003501037A patent/JP2004522398A/ja active Pending
  • 2002-05-28 WO PCT/EP2002/005860 patent/WO2002097961A1/de not_active Application Discontinuation

Non-Patent Citations (1)

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