Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
  • G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
  • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
  • G01R19/2513—Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M1/00—Details of apparatus for conversion
  • H02M1/0003—Details of control, feedback or regulation circuits
  • H02M1/0009—Devices or circuits for detecting current in a converter
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
  • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
  • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
  • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
  • H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
  • H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation

Definitions

• the invention relates to a method for determining at least one phase current in an electrical machine, in particular for a motor vehicle, according to the preamble of claim 1, and to a corresponding device according to the preamble of claim 9.
• phase current In the operation of electrical machines, it is often desirable or necessary to determine at least one phase current. This applies in particular for applications in motor vehicle technology in which an electrical machine is controlled in a clocked manner, preferably by means of a pulse width modulated (PWM) voltage.
• PWM pulse width modulated
• the information about the at least one phase current serves as an input parameter in control or regulation circuits which serve, for example, for monitoring or shutdown when a limit value is exceeded.
• shunt low-impedance current shunt
• the voltage drop across the shunt is proportional to the phase current and is tapped via corresponding contacts.
• the signal of this voltage drop is further processed (for example amplified or digitized) and evaluated.
• a method for determining at least one phase current in an electrical machine having a machine control device, in particular for a motor vehicle, having a plurality of switching devices each assigned to one phase, each having at least one switching element, wherein the machine control device switches the switching arrangements by means of operating switching operations such that at least at least temporarily a phase current is passed to the machine to effect the operation of the machine it is proposed according to the invention that in addition to the operating switching operations causing the operation of the machine, at least one further measuring switching operation serving to determine the phase current is carried out by means of at least one of the switching arrangements.
• the machine control device thus switches a voltage source assigned to the machine by means of the switching arrangements to the individual phases of the machine such that the operation of the machine is effected.
• phase current measurement In order to carry out the phase current measurement, a switching operation is carried out by means of at least one switching arrangement. This means that not only the known operating switching operations and switching states are available for phase current measurement, but an additional measuring switching process is also generated. This creates a special flexibility with regard to the temporal positioning of the phase current measurement.
• the measurement switching operation is performed when the switching states of the switching devices are the same.
• the switching state of each individual switching arrangement is considered at a certain time. If the individual switching states of the individual switching arrangements match, this is to be understood as meaning that the switching states of the switching arrangements are the same. If the switching arrangements have a plurality of switching elements, the switching state with regard to the entirety of the switching states of the individual switching elements must be taken into account. For the example of a switching arrangement with two binary switching elements, this means that the switching arrangement can have a total of four possible switching states: 00, 01, 10 and 11.
• the equality of the switching states of the switching arrangements means that the motor is not energized
• the term "de-energized” is understood to mean that while current can flow within the motor but no current flows to or from the voltage source, the duration of a switching state in which the machine is not energized is typically longer than It should be noted that the measuring switching operation can be carried out each time the switching states of the switching arrangements are the same, but that not every point in time of the same switching states must be used.
• the measuring switching operation is carried out in the middle of the period of the switching state. This can ensure that the measuring switching process does not affect or as little as possible on the operating switching operations.
• the measurement switching operation is carried out during a switching period having a maximum time duration of all switching arrangements.
• the measuring switching operation is carried out during a switching period of all switching arrangements having a minimum time duration. This leaves time enough room to carry out possible compensation steps. These compensation steps will be explained in more detail below.
• the measurement switching process only lasts for the measurement duration used to determine the phase current. Since the measuring switching process causes a change in the switching operations, there is also a certain change in the operating behavior of the electric machine. Therefore, the change effected to perform the metering operation should only last as long as required to determine the phase current.
• At least one switching time of at least one of the switching operations is adjusted to compensate for the measurement switching operation. This means, in particular, that when an additional current has flowed through the machine through the metering operation, this current is compensated by a previous shutdown or later switching on of this current at a different time. This can be the Reduce or eliminate the effects of the metering operation on the operation of the machine.
• the period of the switching operations (for example the clock period) remains unchanged during the compensation. This reduces the complexity of a compensation, in particular with a PWM control of the machine.
• the measuring switching operation is preferably carried out as a temporary inversion of the switching state of at least one of the switching arrangements.
• the invention relates to a device for determining at least one phase current in an electric machine with a machine control device, in particular for a motor vehicle, having a plurality of each associated with one phase switching arrangements each having at least one switching element, wherein the machine control device by means of switching operations switching the switching arrangements such that at least temporarily At least one phase current is conducted to the machine in order to effect the operation of the machine, wherein the device has a measuring device and at least one measuring switching device carrying out the measurement process determining the phase current is provided in addition to the operating switching operations which effect the operation of the machine.
• a measuring element of the measuring device is arranged in a combination of all phases. It is therefore no longer necessary to provide measuring elements for each phase.
• the measuring device has a measuring resistor, in particular a shunt.
• the switching arrangements each have two switching elements. These switching elements are preferably formed as semiconductor switching elements, in particular transistors. In this case, the switching elements are arranged in particular in series, wherein a branch is arranged in a phase of the electric machine between the switching elements. In conjunction with at least one further switching arrangement, one or more bridge circuits can thus be realized, by means of which the desired energization of the machine is effected.
• the switching elements change their switching states in opposite directions to each other. This can ensure that the supplied current always flows through the windings of the machine, and does not cause a short circuit due to a switched-through switching arrangement.
• so-called dead times can be provided, which prevent switching of the switching state when one switching element is switched on, in particular as a transistor, before the other switching element opens, in particular as a transistor. This prevents short-circuit current from occurring for a short time.
• the electric machine is an AC motor.
• An advantageous embodiment of the invention provides that the AC motor is formed in star connection.
• 1 shows a device for determining at least one
• FIG. 2 shows a detailed view of the device according to FIG. 1,
• FIG. 3 shows the timing of the switching processes for a method for determining at least one phase current
• Figure 4 shows a first variant for generating the required switching signals
• Figure 5 shows a second variant for generating the required switching signals.
• FIG. 1 shows a device 1 for determining at least one phase current U, I B , IC in an electrical machine 10 with a machine control device 12 having a plurality of respective phase associated switching assemblies 14 each having two switching elements 16.
• the electric machine 10 is here as an AC electric motor 11 trained in star connection.
• a switching element 16 as a high-side switching element 18 is associated with a positive voltage potential of a voltage source 20 and the other switching element 16 as a low-side switching element 22 is associated with a negative potential of the voltage source 20.
• Parallel to the voltage source 20, an electrolytic capacitor 24 is connected.
• a branch 26 is arranged in each case, to each of which a motor winding 28 is connected.
• the switching arrangements 14 are switched by the machine control device 12 by means of operating switching operations such that at least at times at least one phase current I A , I B , IC is conducted to the machine 10 in order to effect the operation of the machine 10.
• the switching elements 16 of each switching arrangement 14 are thereby switched in opposite directions, that is, it is always one of Switching elements 16 are opened to prevent the occurrence of a short-circuit current through a switching arrangement 14.
• a measuring element 32 of a measuring device 34 is arranged in the merge line 30, a measuring element 32 of a measuring device 34 is arranged.
• the measuring element 32 is designed here as a measuring resistor (shunt) 36.
• the measuring device 34 picks up the voltage drop across the shunt 36 and determines therefrom the current flowing through the merging line 30.
• the machine control device 12 and the measuring device 34 are assigned a measuring switching device 38. While the engine control device 12 controls or regulates the operating shifts that cause the operation of the engine, the measurement switching device 38 is for performing an additional metering operation. It should be noted at this point that, although the components mentioned are shown individually, they can of course also be partially or fully integrated.
• the interaction between the machine control device 12 and the measurement switching device 38 is as follows.
• the machine control device 12 triggers switching operations in the switching arrangements 14 that bring about the desired operation of the electric machine 10.
• the desired time of the measurement is first determined by the measurement switching device 38.
• the information required for this purpose can be provided directly from the machine control device 12 in a simple manner. If the current measurement is to be performed, that is to say the measurement switching operation is carried out, the measurement switching device 38 sends a signal to the machine control device 12. On the basis of this signal, the machine control device 12 performs a switching operation in at least one of the switching arrangements 14.
• a current flows, which allows an immediate inference to one of the phase currents U, I B , IC.
• the measuring switching device 38 transmits a signal to the measuring device 34 for current measurement or queries a determined measured current value.
• the measuring switching process is then terminated by reversing the switching state change for the measuring switching operation in the at least one switching arrangement. That is, after completion of the Meßschaltvorgangs the switching states of all switching arrangements are again as immediately before the initiation of the Meßschaltvorgangs.
• the high-side elements 18 of the switching elements 14 here are the transistors T1, T3, T5 and the low-side switching elements 22 are the transistors T2, T4, T6.
• the transistors T1, T3, T5 blocking and the transistors T2, T4, T6 are turned on, that is, no current flows through the electric machine 10, the following switching sequence is provided in this embodiment, in each case the Switching states of the transistors not mentioned remain unchanged:
• FIG. 3 illustrates the time profiles of the switching states of the transistors T1 to T6 as an exemplary embodiment when both operating switching operations and measuring switching operations are carried out.
• the abscissa is a time axis, and the respective switching state is read along the ordinate.
• a low value means that the respective transistor blocks
• a high value indicates a conduction of the transistor.
• An additional thin line indicates how the course described with respect to FIG. 2 would result, that is to say without measuring switching operations.
• the phase current I A can be determined there by means of the measuring device 34.
• the current measurement is performed in the middle of the time between the time t 2 and the time t 3 , that is, in the middle of the measuring switching operation.
• the time of the current measurement is indicated by the dashed line.
• the measurement switching operation is in the middle of the time duration of the switching state S3, ie in the time center of the times ti and U.
• the duration of the measurement switching process is kept as short as possible in order to minimize the effects on the operation of the electric machine 10 and, if necessary necessary compensation as low as possible.
• the measurement switching operations are always performed at the same timing in the clock period, so that the measurement timing is synchronous with the PWM period. This simplifies the evaluation. It was thereby recognized that the effect of the meter switching operations on the pulse duty factor can be easily compensated, in particular for sinusoidal current supply, if the original duty cycle lies between the time duration of the metering operation and the difference between the cycle period duration and the time duration of the meter switching operation.
• FIGS. 4 and 5 Exemplary embodiments are shown in FIGS. 4 and 5, how the signals for the required switching operations can be generated in a simple manner, in this case using the example of the switching signals for the switching operations.
• the resulting signals for the transistors T1 and T2 are first shown, wherein the signal for the transistor T1 from the signals T1a and T1 b results and the signal for the transistor T2 T2a and T2b.
• the signal is generated by means of
• T1 T1a AND TIb
• T2 T2a OR T2b
• T1 T1 a XOR T1 b
• T2 T2a XOR T2b.
• FIG. 5 is also shown how an implementation of a dead time can be integrated.
• the effects of the measurement switching operations on the duty cycle are compensated.
• the times in which the transistors T1 and T2 are turned on the desired clock ratios, such as those calculated by a controller or a controller.
• the signals T1a, T1b and T2a, T2b can then be formed, for example, in a microprocessor or outside a microprocessor with a matching logic link.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Ac Motors In General (AREA)
• Measurement Of Current Or Voltage (AREA)

Applications Claiming Priority (2)

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• 2004
  • 2004-11-30 DE DE102004057869A patent/DE102004057869A1/de not_active Withdrawn
• 2005
  • 2005-10-14 EP EP05796964A patent/EP1820032A1/de not_active Withdrawn
  • 2005-10-14 WO PCT/EP2005/055274 patent/WO2006058808A1/de active Application Filing
  • 2005-10-14 BR BRPI0516207-6A patent/BRPI0516207A/pt not_active IP Right Cessation

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