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
  • H02P21/24—Vector control not involving the use of rotor position or rotor speed sensors
  • H02P21/26—Rotor flux based control

Definitions

• the invention relates to the technical field control of electrical machines, and in particular, the control of asynchronous electrical machines.
• the asynchronous electric machine by its construction, is the most robust and cheapest electric machine on the market. Advances in the control of such machines and considerable technological advances, both in the field of power electronics and in microelectronics, have made it possible to install powerful controls for this machine, making it daunting competitor in the areas of variable speed and rapid torque control. However, many problems remain. The influence of variations in the parameters of the machine and the presence of mechanical sensors are all difficulties that have sharpened the curiosity of researchers and engineers.
• the asynchronous cage machine whose rotor does not rotate at the speed of the rotating field and whose only electrical input is to the stator poses difficult problems for its control.
• DSP Digital Signal Processor
• Document FR 2800935 describes a robust control strategy with rotor flux orientation for an asynchronous machine.
• the robustness of this strategy lies in taking into account the drop in the stator voltage.
• the document FR 2779017 describes a method of control with the orientation of the rotor flux for an asynchronous motor.
• the originality of this technique lies in the way in which the rotor flux is reconstituted and in the comparison of this reconstituted flow with flow mapping in nominal mode in order to obtain a fast action on the electric machine. Such an approach is different from that of the present invention.
• EP 0884835 discloses a speed control method in which the rotor flux is also oriented for an asynchronous machine. Based on the characteristics of the machine, the electromotive forces and then the stator frequency ⁇ s are first calculated. This method has a major disadvantage because it depends on the physical parameters of the machine. It is well known that these are likely to evolve.
• EP0840441 discloses control strategies with conventional rotor flux orientation for asynchronous machines. Their goal is not the command itself but rather the management of the saturation of these commands. As a result, the control method is triggered when the commands U d and U q reach predefined thresholds.
• EP088351 1 discloses control instructions generated in the three-phase sinusoidal reference frame (a, b, c).
• the setpoint block contains the rotor frequency and the amplitude of the currents as a function of the setpoint value of the desired torque. It is by imposing a rotor frequency, also called sliding frequency, that the frequency of the current instructions is imposed.
• the invention relates to a method for controlling an asynchronous electric machine of a power unit of a motor vehicle with electric or hybrid traction.
• the method comprises the following steps:
• an operating point comprising a request for pulsation of the rotor and a request for the flow of the rotor as a function of the torque request of the driver,
• stator current values are calculated in the reference frame of
• stator voltages values are determined in the Park coordinate system as a function of the computed value of the rotor flux and of the computed value of the stator pulsation, the stator currents in the Park reference, of the request for pulsation of the rotor and the rotor flow request, and
• the electric machine can be controlled by orienting the rotor flux by canceling the quadratic component of the flux in the Park mark.
• the electric machine can be controlled by direct vector control by calculating the Park angle directly from the measured or estimated quantities.
• the angle of Park can be determined through an observer.
• the invention also relates to a control system of an electric machine asynchronous powertrain of a motor vehicle with electric or hybrid traction.
• the system includes:
• a means for determining the driver's will capable of determining a torque request from the driver
• an operating point determining means capable of determining an operating point comprising a request for pulsation of the rotor and a request for flow of the rotor as a function of the torque request of the driver
• calculation means capable of determining the mechanical rotation speed, and the instantaneous values of the stator supply currents in the three-phase reference
• the calculation means may be able to calculate the Park angle directly from the measured or estimated quantities.
• the calculation means may be able to apply an observer to the instantaneous values of the stator currents in the two-phase reference, to the instantaneous values of the stator voltages in the two-phase reference, and to the mechanical rotation speed in order to determine the angle of Park. , a calculated value of the rotor flux and a calculated value of the stator pulsation.
• FIG. 1 illustrates the references of the three-phase quantities and the two-phase quantities
• FIG. 2 illustrates the remarkable angles, a fixed reference with respect to the stator, a fixed reference with respect to the rotor and the Park mark,
• FIG. 3 illustrates the main elements of a control system according to the invention
• FIG. 4 illustrates the main steps of the control method according to the invention.
• Clarke transformation rather than the Concordia transformation will preferably be used to pass three-phase quantities (a, b, c) to two-phase magnitudes ( ⁇ , ⁇ ).
• Figure 1 illustrates these two landmarks.
• This choice of non-standardized passage matrix makes it possible to facilitate control by processing direct quantities d or in quadrature q, for example the source currents I ds and I qs . This also makes it possible, for example, to directly estimate the modulus of the current which is absorbed by the electric machine, without having to go through a multiplying coefficient.
• the reference (a s , ⁇ s ) is fixed and linked to the stator, the reference ( ⁇ r , ⁇ r ), meanwhile, is fixed to the rotor. Finally, the reference (d, q) is related to the rotating magnetic field.
• ⁇ S the angle formed by the rotating field with respect to the reference (a s , ⁇ s ) fixed with respect to the stator
• ⁇ r the angle formed by the rotating field with respect to the reference ( ⁇ r , ⁇ r ) fixed with respect to the rotor.
• I ds the direct component d of the statoric current
• I qs the quadrature component q of the stator current
• I dr the direct component d of the rotor current
• I qr the quadrature component q of the rotor current.
• the electromagnetic torque C e is determined by applying the following equation:
• stator pulsation ⁇ s is defined by the following equation:
• V ds the direct component d of the voltage applied to the stator
• V qs the quadrature component q of the voltage applied to the stator
• R s represents the resistance of the stator of the machine
• R r represents the rotor resistance of the machine
• J the inertia of the electric machine.
• the purpose of the vector control is to control the asynchronous machine as an independent excitation DC machine which includes a decoupling between the magnitude controlling the flux, the excitation current, and that related to the torque, the armature current. This decoupling is inherent to the design of the machine with independent excitation and makes it possible to obtain a very fast response of the torque during a command.
• the vector control thus obtained is said to orient the rotor flux. It eliminates the influence of rotor and stator leakage reactances and gives better results than methods based on the orientation of the stator flux.
• Equation Eq. 14 can be transposed to the control of the electric machine by fixing
• the Park angle ⁇ S is calculated from the stator pulsation, which is itself reconstructed using the machine speed and the rotor pulsation ⁇ r .
• the Park angle is calculated directly using measured or estimated magnitudes.
• the vector control is called open loop if there is no flow control.
• the flow is imposed in this case by the current I ds -The statoric pulsation can then only be estimated by the following relation:
• f is a cartography function of the mechanical regime. The latter comes from an energy optimization of the machine
• the vector control is called closed loop, if the stator pulsation is estimated from the value of the rotor flux or the magnetizing current.
• the indirect vector control by orientation of the rotor flux essentially rests on two parameters, M and ⁇ r , which link the rotor flow and the current I ds that control it. These parameters also make it possible to calculate the angle ⁇ S that the rotating field forms with respect to the fixed reference ( ⁇ s , ⁇ s ).
• the direct order is privileged.
• the direct vector control by orientation of the rotor flux requires the reconstitution of the rotor flux, in order to be able to determine the angle ⁇ S accurately.
• the determination of this angle is carried out by a flow observer, in particular that described in the patent application FR1453935 filed on April 30, 2014.
• V ds and V qs stabilize the machine around a desired operating point. They are determined by applying the following equations:
• Direct stator current setpoint values and in quadrature in the Park coordinate system are therefore calculated dynamically in the regulator of the control system according to the invention, at the same time as the calculation of the control voltages Vds and Vqs.
• This makes it possible to have a regulation structure in cascade (to regulate the direct current it is first necessary to regulate the flow); this also allows the instantaneous taking into account possible voltage saturations (Vds and Vqs). The effect is to improve the accuracy of the control system.
• FIG. 3 illustrates the main elements of a control system 1 able to determine the voltages (V as , V bs , V cs ) of supply of an asynchronous electric machine 2 for a direct vector control by orientation of the rotor flux.
• a means for determining the will of the driver 4 such as an accelerator pedal depression sensor, issues a torque request according to the
• the torque request is received at the input of a means 5 of
• determining operating points able to determine an operating point comprising a request for pulsation of the rotor and a request for flow of the rotor
• the reference flow is given by a mapping according to the mechanical regime. The latter comes from an energy optimization of the machine.
• sensors 6 transmit different measurements such as raw measurements of currents and mechanical speed, to a calculation means 7 able to determine the mechanical rotation speed ⁇ , and the instantaneous values of the supply currents.
• the stator as I, I bs, cs the marker in three-phase (a, b, c).
• a means 8 for determining the stator currents in the two-phase reference ( ⁇ , ⁇ ) receives the instantaneous values of the power supply currents of the stator I as , I bs , 1 cs in the three-phase reference (a, b, c).
• the determining means 8 applies the equations Eq. 1 in order to change from three-phase quantities to two-phase quantities.
• a means 9 for determining the stator currents in the Park mark receives the instantaneous values of the stator currents in the two-phase reference (a, P).
• the determining means 9 applies the equation Eq. 3 to switch from two-phase variables (I have, I ⁇ s) to quantities in the landmark Park (Id s, I qs).
• a calculation means 10 applies an observer to the instantaneous values of the stator currents in the two-phase reference (a, ⁇ ), to the instantaneous values of the stator voltages in the two-phase reference ( ⁇ , ⁇ ), and to the mechanical rotation speed ⁇ in order to determine the angle ⁇ S formed by the rotating field with respect to the fixed reference (a s , ⁇ ⁇ ) relative to the stator, the calculated value of the rotor flux and the calculated value of the stator pulsation via
• a calculation means 1 1 applies the equations Eq. 19 to the values emitted at the output of the means 5 for determining operating points, the means 9 for determining the stator currents in the Park mark and the observer calculation means 10.
• the calculation means 1 1 determines values of stator voltages in the Park coordinate system (V ds , V qs ).
• a means 12 for determining the values of the stator voltages in the two-phase reference system applies the equations Eq. 4 to go from the Park marker to the two-phase marker.
• a means 13 for determining the voltage values of the stator in the three-phase reference system applies the equations Eq. 2 in order to go from the two-phase mark to the three-phase mark.
• the three-phase stator voltages values thus determined are transmitted to the control means (not shown) of the power inverter of the electric machine 2 in order to generate the corresponding voltages. Its stator thus fed, the electric machine 2 generates a motor torque C e , which is transmitted to the wheel 3 in a conventional manner.
• FIG. 4 illustrates the main steps of a control method making it possible to determine the power supply voltages (V as , V bs , V cs ) of an asynchronous electric machine 2 for direct vector control by orienting the rotor flux.
• the driver's will is determined, for example by measuring the depression of the accelerator pedal, in order to determine a torque request. according to the will of the driver.
• an operating point comprising a request for pulsation of the rotor is determined. and a request for rotor flux as a function of the torque request.
• the mechanical speed of rotation ⁇ is determined, and the instantaneous values of the stator supply currents I as , I bs , l cs in the three-phase reference (a, b, c) according to sensor measurements.
• stator currents in the two-phase reference ( ⁇ , ⁇ ) are determined as a function of the instantaneous values of the stator supply currents I as , I bs , I cs in the three-phase reference (a , b, c) by applying equations Eq. 1.
• stator currents in the Park coordinate system are determined as a function of the instantaneous stator current values in the two-phase reference ( ⁇ , ⁇ ) by applying the equation Eq. 3.
• the angle ⁇ S formed by the rotating field with respect to the reference (a s , ⁇ ⁇ ) fixed relative to the stator, the calculated value of the rotor flux and the computed value is determined.
• stator voltage values in the Park coordinate system (V ds , V qs ) are determined as a function of the operating point values, stator currents in the Park landmark and determined by observer, applying the equations Eq. 19.
• the values of the voltages of the stator in the two-phase reference mark are determined as a function of the stator voltage values in the Park coordinate system by applying equations Eq. 4.
• the values of the voltages of the stator in the three-phase reference frame are determined as a function of the values of the voltages of the stator in the two-phase reference mark by application of the equations Eq. 2.
• the three-phase stator voltages values thus determined are transmitted to the power inverter of the electric machine 2 in order to generate the corresponding voltages. Its stator thus fed, the electric machine 2 generates a motor torque C e , which is transmitted to the wheel 3 in a conventional manner.
• the present method can be applied to other types of rotating machines with the use of a suitable reference change.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Ac Motors In General (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=52358864

Family Applications (1)

Country Status (3)

Families Citing this family (2)

Family Cites Families (13)

• 2014
  • 2014-09-08 FR FR1458382A patent/FR3025672B1/fr not_active Expired - Fee Related
• 2015
  • 2015-09-08 EP EP15778360.6A patent/EP3192164A1/de not_active Withdrawn
  • 2015-09-08 WO PCT/FR2015/052385 patent/WO2016038296A1/fr not_active Ceased

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events