DE102013221939A1 - Method and device for operating an electronically commutated actuator - Google Patents

Abstract

The invention relates to a method for operating an electronically commutated actuator (2) by specifying a setpoint torque (Msetpoint) by applying phase voltages (Ua, Ub, Uc), wherein the setpoint torque (Msetpoint) depends on a supply voltage (Uvers) from which the Phase voltages (Ua, Ub, Uc) are generated is limited.

Description

Technical area

The invention relates to electronically commutated actuators, in particular method for operating such actuators. Furthermore, the present invention relates to methods for operating electronically commutated actuators with a control, in particular with a position control.

State of the art

In an engine system with an internal combustion engine can be used as positioners, such as throttle position sensor, actuators with electronically commutated electric machines. These have the advantage of lower manufacturing costs compared to actuators with brush-commutated DC motors and a higher temperature resistance due to the fixed arrangement of the motor windings in the stator.

In general, such an actuator is connected via a gear to the actuator. For many positioner applications, the position or position of the actuator must be adjusted using a position control. For this purpose, the current position of the actuator is determined in a suitable manner via a position sensor and fed to a position control.

Disclosure of the invention

According to the invention a method for operating an electronically commutated actuator according to claim 1 and a device, an actuator system and a computer program product according to the independent claims are provided.

Further embodiments are specified in the dependent claims. According to a first aspect, a method for operating an electronically commutated actuator by applying phase voltages according to a predetermined target torque is provided, wherein the target torque is limited depending on a supply voltage from which the phase voltages are generated.

The control or commutation of a multi-phase actuator can be done via the dq model using a classical field-oriented control by measuring the phase currents or by measuring the induced reverse voltage or model-based. In this case, a two-dimensional rotor-related coordinate system is defined with respect to which a position of a voltage vector in a stator of the actuator can be described. The direction of the voltage vector corresponds to the direction of the stator magnetic field caused by the phase currents resulting from the application of the phase voltages. The component of the voltage vector running perpendicular to the rotor magnetic field essentially determines the output motor torque, while the rotor magnet field-parallel component of the voltage vector influences the magnetic rotor flux and can thus be used to optimize the torque development and the efficiency.

As a rule, the components of the voltage vector are matched in terms of amount as a function of the current engine speed and the required torque in order to achieve the optimum efficiency. This can be achieved either by current regulation or by using offline calculated commutation maps. In the latter case, the commutation maps then determine the components of the voltage vector of the rotor-fixed coordinate system. To control the electronically commutated actuator these components are then converted into phase voltages.

When commutation maps are used to commutate the actuator, its rating is tailored to the motor of the actuator whose parameters need to be known. In addition, requirements for maximum current, commutation for efficiency or moment optimum, field weakening operation and robustness to parameter variation and commutation errors can be taken into account.

When using the map commutation, the allowable range is constrained in terms of engine torque within the two commutation maps. Thus, from certain setpoint torques, a violation of predetermined current limits can result, which is determined by additional limiting characteristic curves for the maximum and minimum setpoint torque in the respective operating point could be. As a result, the target torque is limited depending on the current speed to the permissible range, thereby preventing access to impermissible areas in the Kommutierungskennfeldern is prevented.

Since both the commutation maps and the current limiting characteristics are determined based on a constant supply voltage, supply voltage variations, which are common in practice, can not be taken into account when using the limiting characteristics as well as when using the commutation maps. Thus, if the supply voltage actually available for the commutation of the actuator is below the supply voltage considered for the limiting characteristics or the commutation characteristics, maximum and minimum torques, for example, which can not be achieved by the actuator, can be predetermined by the limiting characteristics. Thus, inadmissible areas in the commutation maps are accessed, although this leads to a deviation from an optimal commutation as well as a possible violation of current limits.

Therefore, it is provided according to the above method, continue to make the limitation of the target torque depending on the currently applied supply voltage. In the case of a characteristic map solution, therefore, the previously used limiting characteristic is extended to a limiting characteristic which now also takes into account the current supply voltage. As a result, an independence of the limitation of the setpoint torque is achieved by the current supply voltage. In this way, the requested target torque is limited so that the commutation maps can control the actuator only in terms of allowable torques. In particular, access to impermissible areas within the commutation maps is prevented, thus always guaranteeing optimal commutation or compliance with the defined limits. In addition, the provision of boundary maps for taking into account a varying supply voltage has the advantage that adjustments can be made in a simple manner and without changing the driving method in the case of changing engine parameters or an altered commutation strategy.

It can further be provided that the desired torque can be specified by a control, such as a position control. By providing the boundary map, the availability of the operating point-dependent extreme torques can be explicitly taken into account by the limits of the target torque and realized in the control strategy. This means that the setting limits can already be taken into account when calculating the setpoint torque as the manipulated variable of the control.

Furthermore, the limitation can be carried out depending on a rotor speed of the actuator.

In particular, the limitation of the setpoint torque can be performed by specifying a minimum and / or maximum setpoint torque.

It can be provided that the minimum and / or maximum target torque are predetermined by means of a limiting characteristic map. This represents a simple way to use a corresponding engine system, individually with little effort.

According to one embodiment, the setpoint torque can be specified as a manipulated variable of a control, in particular a position control, wherein the limitation of the setpoint torque is taken into account in the control. In this way, e.g. Windup effects and similar stability-impairing effects are avoided.

In particular, integration in the integrator component of the control can be prevented if the setpoint torque is actively limited.

Furthermore, the limitation of the setpoint torque by means of an anti-windup for an integrator component of the control can be taken into account.

The phase voltages may be generated depending on a rotor position of the actuator, depending on the supply voltage and depending on the limited target torque.

• – einen Begrenzungsblock, der ausgebildet ist, um das vorgegebene Solldrehmoment auf ein minimales und/oder maximales Solldrehmoment zu begrenzen; und
• – einen Begrenzungskennfeldblock, um das minimale und/oder maximale Solldrehmoment abhängig von einer Versorgungsspannung, aus der die Phasenspannungen generiert werden, vorzugeben.

According to a further aspect, an apparatus for operating an electronically commutated actuator is provided by providing phase voltages corresponding to a predetermined target torque, comprising:

• A limit block configured to limit the predetermined target torque to a minimum and / or maximum target torque; and
• - A boundary map block to specify the minimum and / or maximum target torque depending on a supply voltage from which the phase voltages are generated.

Furthermore, the boundary map block may be configured to provide the minimum and / or maximum target torque depending on the rotor speed.

• – einen Stellantrieb,
• – einen Kommutierungsblock zur Vorgabe eines Spannungszeigers entsprechend einem begrenzten Solldrehmoment, wobei aus dem Spannungszeiger Phasenspannungen generierbar sind; und
• – die obige Vorrichtung.

In another aspect, an actuator system is provided, comprising:

• An actuator,
• A commutation block for specifying a voltage vector corresponding to a limited nominal torque, wherein phase voltages can be generated from the voltage vector; and
• - The above device.

Furthermore, the actuator system with a control, in particular a position control, be designed to generate the desired torque as a control variable, the control takes into account a limitation of the target torque.

Brief description of the drawings

Embodiments are explained below with reference to the accompanying drawings. Show it:

1 an actuator system with a map-based commutation and a limitation of a provided target torque by specifying a maximum or minimum target torque by a boundary map;

2a and 2 B Commutation maps for the components of the voltage vector to be applied, which is generated from the limited target torque; and

3 a control with consideration of a manipulated variable limitation by means of an anti-windup.

Description of embodiments

1 schematically shows the representation of an engine system 1 for driving an electronically commutated actuator 2 with an electric machine. In the present embodiment, the actuator 2 formed three-phase and is controlled by specifying three phase voltages U _a , U _b , U _c .

The phase voltages U _a , U _b , U _c form a voltage vector which indicates the direction of a stator magnetic field caused by the phase voltages U _a , U _b , U _c or the phase currents caused by the phase voltages U _a , U _b , U _c . The stator magnetic field interacts with the exciter magnetic field caused by the rotor, which is often provided by permanent magnets. The phase voltages U _a , U _b , U _c are from a transformation block 3 determined from the specification of components U _d , U _{q of} a voltage vector in a rotor-fixed coordinate system. The rotor-fixed coordinate system always refers to the current position φ of the rotor of the actuator 2 , In this case, the component U _{d is} a longitudinal voltage component, which extends in the direction of the exciting magnetic field, and the component U _{q is} a transverse stress component, which is perpendicular to the direction of the exciting magnetic field, in particular 90 ° leading with respect to the direction of movement of the rotor.

To perform the transformation in the transformation block 3 a knowledge of the rotor rotor position φ is necessary. The rotor position φ can be measured by means of a sensor on a shaft of the actuator 2 be determined. Alternatively, the rotor position φ can also be evaluated by evaluating voltage or current curves in the actuator 2 be determined, for example, using the so-called back-EMF method.

Furthermore, the knowledge of the supply voltage U _{verse is} required for the determination of the phase voltages U _a , U _b , U _c from the longitudinal and transverse voltage components U _d , U _{q of} the voltage vector. In particular, the transformation block uses 3 for converting the longitudinal and transverse voltage components U _d , U _{q of} the voltage vector into the phase voltages U _a , U _b , U _c, the following formula:

In principle, there are several possibilities for converting a setpoint torque M _soll , which is to be provided by the electrical machine, to a resulting voltage vector for actuating the actuator 2 pretend. The longitudinal and transverse stress components U _d , U _q can be carried out either by means of a current control, for example a conventional field-oriented control, or by means of a motor model taking into account the motor parameters. Alternatively, commutation characteristics can be used in a commutation block to determine the voltage vector 4 are deposited in a suitable manner. Commutation maps, for example, in a suitable manner in a map memory 41 in the commutation block 4 be stored in the form of a lookup table or in the form of a suitable functional model.

Furthermore, the commutation block 4 in addition to the setpoint torque M _is also an indication of the rotor speed ω _{L of} the actuator 2 provided, for example, in a differentiation block 6 from temporal changes in position of the rotor layers φ _L can be determined. The commutation maps 41 can offline using simulation tools are calculated and determined depending on the rotor speed ω _L and the predetermined desired torque M _to the longitudinal and transverse voltage component U _d, U _q of the actuator 2 to be applied voltage vector.

The 2a and 2 B show exemplary commutation maps 41 for generating the longitudinal and transverse components U _d , U _{q of} the voltage vector.

For controlling the actuator 2 is defined as a control variable, a target torque M _soll. This target torque M _soll depends on the performance of the actuator 2 and is usually on the in the actuator 2 adjustable rated power matched. The rated output of the actuator 2 is usually a size when applying a rated voltage as supply voltage U _vers of the actuator 2 can be provided as a continuous service. However, the supply voltage U _vers can fall below the nominal voltage due to voltage fluctuations of the supply system, especially when used in the motor vehicle, so that a required target torque M _will not be provided.

To avoid violating current limits is a limit block 7 provided that a predetermined target torque M _soll limited to a predetermined maximum target torque M _{soll, max} and a predetermined minimum target torque M _{soll, min} and as limited set torque M _{soll, lim} provides. For the current limitation, it is necessary that the maximum and minimum target torque M _{soll, max} , M _{soll, min} speed-dependent generated, so that this operating point can be provided depending.

Due to the fluctuations in the supply voltage U _vers , it is further provided to provide the maximum and minimum setpoint torque M _{soll, max} , M _{soll, min} depending on the currently applied supply voltage U _vers . The maximum and minimum target torque M _{soll, max} , M _{soll, min} is from a boundary map block 8th provided, which receives as inputs the rotor speed ω _L and the supply voltage U _vers and, for example, by means of one or more boundary maps, for example, in a boundary map memory 81 may be stored, or suitable limiting functions operating point-dependent, the limiting values of the maximum and / or minimum desired torque M _{soll, max} , M _{soll, min} to the limiting block 7 provides. The bounding block 7 now limits the provided target torque M _soll and provides the commutation block 4 the limited target torque M _{soll, lim} ready.

By determining the maximum and minimum desired torque M _{soll, max} , M _{soll, min} depending on the current supply voltage U _vers the limited target torque M _{soll, lim can be provided} independently of the current operating setpoint voltage, so that for each operating point with respect to the rotor speed ω _L of the actuator 2 and the current supply voltage U _vers the actually realizable minimum and maximum target torque M _{soll, max} , M _{soll, min of} the actuator 2 can be calculated. Thus, access is made to inadmissible areas within the commutation maps 41 , the commutation in the commutation block 4 be based on prevented and an optimum commutation or compliance with the limits set for the target torque M _soll guaranteed. The boundary maps for the maximum and minimum target torque M _{soll, max} , M _{soll, min} can also be calculated offline, in particular by simulation of a physical engine model in conjunction with the previously determined commutation maps 41 ,

In a further embodiment, the specification of the desired torque M _{soll can be performed} by a suitable position control. In 3 an example of a position controller is shown, in which the limitation of the manipulated variable, namely the target torque M _soll , is taken into account in the position control. By providing the maximum and minimum setpoint torques M _{soll, max} , M _{soll, min} , these control limits can thus be taken into account in the control strategy. That is, already in the calculation of the target torque M _nom by the position control can the respective maximum and minimum target torque M _{soll, max,} M _should be noted _min. Depending on the intended control, disregarding the maximum and minimum setpoint torques M _{soll, max} , M _{soll, min} can lead to a deterioration of the control quality up to the instability of the entire control loop.

3 shows an example of a position control using a PI controller 10 with a proportional component 11 and an integrator component 12 , The proportional component 11 and the integrator component 12 In each case, a positional difference Δφ is provided which corresponds to a first differential element 13 is determined as the difference between a predetermined desired position φ _soll and the current rotor position φ _L. The position difference Δφ is in a first amplifier 18 the proportional component 11 multiplied by a predetermined proportional factor K and a summation element 14 fed.

Furthermore, the position difference Δφ becomes a second differential element 15 fed, whose output with an integrator 16 is coupled to an integrator value to the summation element 14 provide. The in the summation member 14 The sum formed corresponds to a setpoint torque M _soll , which then follows a limitation block 7 is supplied. To take into account the limitation in the bounding block 7 in the regulation of the PI controller 10 are the limited setpoint torque M _{soll, lim} and that of the summation block 14 provided target torque M _is a third differential element 17 supplied in which a difference between the limited target torque M _{soll, lim} and that of the PI controller 10 provided target torque M _{should be} formed and the result amplified via a second amplifier 19 with a fixed gain to an inverting input of the second difference block 15 is created.

In the second difference block 15 is thus subtracted from the difference between the limited target torque M _{soll, lim} and the target torque M _soll dependent correction variable of the position difference Δφ, so that the integration in the integrator component 12 is reduced as soon as a limit by the boundary block 7 takes place. Using this anti-windup strategy, a limit can be imposed by the bounding block 7 already in the regulation of the actuator 2 be taken into account.

In a simplified approach, integrating in the integrator component 12 instead of the reduction of the integration are completely inhibited, as soon as the target torque _is actively limited by the limiting values of the maximum and minimum target torque M _{soll, max} , M _{soll, min} .

While other control strategies, such as model predictive control, or sliding mode schemes require no anti-windup, but also provided information on a carried limiting the desired torque M _to the calculation of a permissible target torque as a control variable.

Regardless of the selected control strategy, it is crucial for a high control quality that the voltage depends on the supply voltage U _vers and the rotor speed ω _{L of} the actuator 2 determined maximum and minimum set torques M _{soll, max} , M _{soll, min} at any time the actual realizable torque of the actuator 2 correspond, which depends on the applied supply voltage U _vers . This information requires the control to calculate a single full manipulated variable (target torque M _soll ).

Claims (12)

Method for operating an electronically commutated actuator ( 2 ) by specifying a setpoint torque (M _soll ) by applying phase voltages (U _a , U _b , U _c ), wherein the setpoint torque (M _soll ) is limited depending on a supply voltage (U _vers ) from which the phase voltages (U _a , U _b , U _c ) are generated. The method of claim 1, wherein the limit is further dependent on a rotor speed (ω _L ) of the actuator ( 2 ) is carried out. The method of claim 1 or 2, wherein the limitation of the target torque (M _soll ) is performed by specifying a minimum and / or maximum target torque. The method of claim 3, wherein the minimum and / or maximum target torque is predetermined by means of a boundary map. Method according to one of claims 1 to 4, wherein the target torque (M _soll ) as a control variable of a control, in particular a position control, is specified, wherein the limitation of the target torque (M _soll ) is taken into account in the scheme. Method according to claim 5, wherein the limitation of the setpoint torque (M _soll ) in an anti-windup of an integrator component ( 12 ) of the scheme. The method of claim 6, wherein integrating in the integrator component ( 12 ) is suppressed the control when the target torque (M _soll ) is actively limited. Method according to one of claims 1 to 7, wherein the phase voltages (U _a , U _b , U _c ) depending on a rotor position (φ) of the actuator ( 2 ), depending on the supply voltage (U _vers ) and depending on the limited target torque (M _{soll, lim} ) are generated. Device for operating an electronically commutated actuator ( 2 ) by providing a setpoint torque (M _soll ) by providing phase voltages (U _a , U _b , U _c ), comprising: - a limiting block ( 7 ) configured to limit the target torque (M _soll ) to a minimum and / or maximum target torque (M _{soll, max} , M _{soll, min} ); and - a boundary map block ( 8th ), in order to specify the minimum and / or maximum setpoint torque (M _{soll, max} , M _{soll, min} ) depending on a supply voltage (U _vers ), from which the phase voltages (U _a , U _b , U _c ) are generated. Apparatus according to claim 9, wherein the boundary map block ( 8th ) is configured to provide the minimum and / or maximum target torque (M _{soll, max} , M _{soll, min} ) depending on the rotor speed (ω _L ). An actuator system comprising: - an actuator ( 2 ); A commutation block ( 4 ) for specifying a voltage vector, from the phase voltages (U _a , U _b , U _c ) can be generated; and - an apparatus according to claim 9 or 10. Actuator system according to claim 11, wherein a control, in particular a position control, is designed to generate the setpoint torque (M _soll ) as a manipulated variable, the control taking into account a limitation of the setpoint torque (M _soll ).

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