DE102011075789A1 - Method for operating induction machine e.g. permanent magnet synchronous machine of pulse inverter for motor car, involves adjusting voltage vector and setting pulse width modulation command value constant for defective power switch - Google Patents

Abstract

The method involves determining pulse width modulation (PWM) default values for each phase (U,V,W) corresponding to power switches (T1-T6) of an inverter (1) to adjust a voltage vector of an induction machine (4). A PWM command value for operation of the induction machine is set constant for defective power switch due to recognition of an error in a short circuit (5). The constant PWM preset value is output for repeatedly optimizing PWM target values. An independent claim is included for propulsion system for induction machine.

Description

The present invention relates to a method for operating a rotating field machine according to the preamble of claim 1.

In an inverter, in particular a voltage source inverter, the desired voltages for a rotary field machine to be operated by means of the inverter can be adjusted by a PWM or undershoot modulation method. Normally, the field-oriented control (FOR) is used to control a permanent-magnet synchronous machine (PMSM).

In the event of a fault in the inverter, in particular in the event of a short circuit of a circuit breaker, eg a MOSFET, the induction machine can not be properly controlled because the desired voltage vector can not be set because of the short circuit. As measures, either the machine is short-circuited in such cases of error, eg according to the document DE 198 04 967 A1 , or all other MOSFETs open to disconnect the induction motor from the power supply and bring them to a standstill. In both cases arise braking torques, which are risky for driving safety when used in driving, such as a motor vehicle.

If you want to achieve a safe shutdown of the machine, so phase separator or star point relay for a PMSM machine are necessary to cause in the event of a fault, the immediate separation of the induction motor from the inverter and the power supply. Through these components additional costs and space, which also causes permanent losses, since phase separators have a switching resistance.

Proceeding from this, the present invention seeks to overcome the above-described disadvantages of the prior art and to propose a method for operating a rotating field machine in which the induction machine is operable in the event of a circuit breaker failure, in particular reliable.

This object is achieved by the features of claim 1. Advantageous embodiments and further developments are the subject of the dependent claims.

The invention proposes a method for operating an induction machine, in particular a permanent-magnet synchronous machine (PMSM), on an inverter, wherein the inverter is preferably a voltage source inverter, in particular a pulse inverter. The inverter may preferably be formed by means of a B6 bridge, i. have three half-bridges, each with two circuit breakers. Each phase of the induction machine can be supplied with energy via each half bridge or its center tap. The power switches are preferably IGBTs or MOSFETs, which are connected to a freewheeling diode.

For the operation of the induction machine PWM default values are determined for each phase thereof, for example, in the context of the inventive method. calculated corresponding to which circuit breaker of the inverter set a voltage vector on the induction machine, ie. via its driver level. The PWM default values express duty cycles for selected switches of the half-bridges, i.e.. each phase. The PWM default values may be generated by a controller structure to adjust the desired currents and voltages, i. a voltage vector on the induction machine. The PWM default values are values that are suitable as default values for the normal operation of the induction machine and can be determined as such.

Due to a fault, in particular a short circuit of a circuit breaker in a phase or half-bridge, the PWM value can not be set in this phase. The additional circuit breaker in the same phase or half-bridge must remain permanently open, so that no short-circuit occurs on the DC link. Otherwise, a DC link capacitor could be destroyed.

In order to continue to operate the induction machine when such an error occurs, in particular reliable and without excessive distortion of the phase currents, in the method in a first step, an error, in particular a short circuit, a circuit breaker detected. For this purpose, a monitoring device can be used, which is part of a controller and / or control structure for the operation of the induction machine.

According to the method, a second step is provided below in which a PWM default value for further operation of the induction machine for the phase of the induction machine to be supplied by means of the defective circuit breaker is set constant. That is, a constant PWM default value takes the place of a PWM default value respectively generated for the normal operation case for the phase to be supplied by means of the half-bridge having the defective power switch. This is subsequently output for the further operation of the induction machine, in particular for all voltage vectors to be set, and furthermore in particular as the exclusive PWM default value for this phase.

It is envisaged in this case to set the constant PWM default value, in particular as a function of the position of the defective circuit breaker in its half-bridge, to 100% or 0%. For example, In the case of a short-circuited low-side circuit breaker, typically the bottom switch, the constant PWM default value for a short-circuited high-side power switch, typically the top switch, is set to 100%, set to 0%.

For the further operation of the induction machine after the occurrence of a switch error condition optimized PWM default values are further determined and output in the second step for the other phases of the induction machine. Specifically, the optimized PWM default values are determined based on the PWM default values for the further phases, i. based on the pre-determined PWM default values for the further phases. Through these measures, the originally desired voltage vector can be restored.

By means of the constant as well as the optimized PWM default values, a voltage vector can then advantageously be set on the induction machine which, on average, leads to no braking torque and / or no excessive phase current. Otherwise, braking torques arising at high rotational speeds can advantageously be reduced within the scope of the present invention. The achievement of a positive torque is advantageously possible, especially at low speeds.

The determination of an optimized PWM default value for each of the further phases can preferably be carried out by means of the equation 1) PWM _{i, n} = (PWM _{d, n} - PWM _d ) + PWM _i respectively. Here, PWM _{i, n} denotes an optimized PWM default value for the respective further phase - which can be controlled via intact power switches and can be referred to as the intact phase - and PWM _i a PWM default value for the same phase. Further, PWM _{d, n} denotes the PWM set constant value for the erroneously controllable phase - which may be referred to as a defective phase - and PWM _d a PWM default value for the same phase. In this case, PWM _i and PWM _d are in particular PWM default values which would be suitable for a normal mode of operation for controlling the induction machine.

In the proposed method of PWM modulation, the two PWM default values of the error-free controllable phases are advantageously modified such that an originally intended voltage vector sets in again.

The optimized or corrected PWM default values for the further phases determined by means of equation 1) are effective as long as the newly determined PWM default values do not fall below or exceed the threshold values 0% and 100%. In the event that the determined PWM default values are outside these thresholds, they are limited to this threshold and output as limited PWM default values. It should be noted that in particular PWM duty ratios are expressed for each phase by means of the PWM default values, the constant set PWM default value, the optimized PWM default values and the limited PWM default values

It is also provided according to the invention, in an intermediate step between the first and the second step, to switch from a controlled operation of the induction machine to a controlled operation of the induction machine, alternatively preferably to a controlled operation with current estimation. This makes it possible to provide a PWM default value for the further phases even if current sensors of a controller structure are no longer available due to a circuit breaker short-circuit or the current measurement becomes unusable.

For a controlled operation of the induction machine is preferably switched from a field-oriented control to a field-oriented control, in particular a field-oriented control with adjustable dynamics. Alternatively, for example, a current model can be used to estimate the phase currents or machine currents in the d, q coordinate system to compensate for current sensors. The PWM default values can be determined in this case after switching to the control operating mode in the control operating mode or alternatively after switching to a control operating mode with current estimation, in particular with field-oriented control and current estimation.

The control structure for a controlled operation can be advantageously realized by means of a controller structure used for the normal operation of the induction machine. In the course of switching, the current sensors of the controller structure, which is provided for the operation of the induction machine, may also be switched off and thus, e.g. be protected from damage. Alternatively, in the event of a fault, a regulator structure with current estimation, i. a FOR with current estimator, are formed by means of the controller structure used in normal operation, wherein the current sensor can also be turned off.

In the context of the present invention, a drive system for a rotary field machine, in particular a permanent-magnet synchronous machine (PMSM), for carrying out the method according to the invention is also proposed. The drive system has a controller structure and an inverter included in the controller structure for operating the induction machine. The controller structure is preferably switchable to a control structure for field-oriented control of the induction machine, in particular for field-oriented control with adjustable dynamics, alternatively preferably to a controller structure for particular field-oriented control with current estimation.

On the part of the control or regulator structure, the inverter, or its power unit, can be controlled by means of the PWM default values, in particular via the inverter driver stage, ie in the event of an error using the constant, optimized or limited PWM default values. In this case, the controller structure or the drive system is preferably designed in such a way that it is possible to switch over between control and control operation as a function of an error detected at a circuit breaker, in particular switching to a field-oriented controller with adjustable dynamics. In a preferred embodiment, the drive system has a rotary field machine which can be operated by means of the inverter. The induction machine is designed, for example, as a full-pole machine with a rotationally symmetrical rotor or as a salient-pole machine with pronounced poles.

By a drive system, which is operable by the method according to the invention, even positive torques can be achieved - especially at low speeds, the phase currents are sufficiently low to prevent destruction of the circuit breaker and the permanent magnets of the machine are not demagnetized. Expensive devices, such as Star point relays and phase separators, which would otherwise be necessary, can be saved.

The proposed method or the proposed drive system is preferably used for operation of a rotating field machine of a motor vehicle, since the motor vehicle can often not be stopped immediately in a sudden failure of the induction machine driving circuit and therefore the induction machine in this case must be at least limited weiterbetreibbar , In particular, the proposed method or the proposed drive system is therefore suitable for the operation of a motor vehicle system, which must be absolutely insensitive to such failures, such as an actuator for steering power assistance of a vehicle steering or actuators for switching ratio stages of a multi-stage vehicle transmission or an actuator for adjusting a vehicle chassis. Alternatively, the method or drive system is for operating a traction drive of the motor vehicle, i. a traction drive.

Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures of the drawings, which show details essential to the invention, and from the claims. The individual features can be realized individually for themselves or for several in any combination in a variant of the invention.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. Show it:

1 an example of an inverter with a faulty circuit breaker;

2 an example of a representation of remaining sectors for the setting of a voltage vector;

3 exemplary and schematically a controller structure for a field-oriented control according to a possible embodiment of the invention;

4 exemplary and schematically one by means of the controller structure according to 3 formed control structure for a field-oriented control according to a possible embodiment of the invention.

In the following description of the figures, the same elements or functions are provided with the same reference numerals.

The 1 shows an example and schematically a pulse inverter 1 with a voltage intermediate circuit 2 , which by means of an intermediate circuit capacitor 3 is formed. The inverter 1 is formed in B6 bridge circuit with three half-bridges, each having two power switches T1, T2 and T3, T4, and T5, T6 in the form of MOSFETs. Three circuit breakers T1, T3, T5 of the inverter 1 are arranged as a high-side circuit breaker, three switches T2, T4, T6 as a low-side circuit breaker. The center taps of the half bridges are each with a phase U or V or W of a rotary field machine 4 in the form of a permanent-magnet synchronous machine (PMSM) 4 electrically connected.

The induction machine 4 is intended in particular for use in a motor vehicle, eg for use in a power steering system. The induction machine 4 has a stator with a stator winding, in particular with the three winding strands U, V, W, which are preferably symmetrically wound and arranged offset by 120 degrees, and further in particular a rotor equipped with permanent magnets.

The in 1 shown inverters 1 exemplifies a fault condition of a circuit breaker T1 in the form of a short circuit 5 of the switch, ie the switching path is permanently electrically conductive. The effects of such an error for the control of the induction machine 4 are described below on the basis of 2 closer illuminated.

In normal operation, a voltage vector u * passes through all six sectors within one electrical period, 2 , As a result, not all eight discrete voltage vectors v ₀ ... v _{7 of} the space vector of the inverter 1 because of the short circuit 5 of the power switch T1, the intended voltage vector u * can be set only in a reduced range within one electrical period. In this case, only three discrete voltage vectors v ₆ , v ₁ , v ₂ and a zero voltage vector v ₀ or v _{7 can be} set so that only two sectors are covered. For the short circuit shown as an example 5 of the MOSFET T1 in phase U, for example, only the sectors 1 and 6 are covered. Outside these two sectors 1 and 6, the desired voltage vector u * can not be set.

To a further operation of the induction machine 4 , which is not associated with excessive phase currents and on average does not lead to a braking torque to allow in such a fault, has a drive system 6 for the induction machine 4 a controller structure 7 according to 3 on, which in particular enters a control operating mode upon the occurrence of an error as described above. In the present case is the controller structure 7 according to 3 , which regulates the error-free or normal operation, advantageously for a fault on a control structure according to 4 switchable.

For normal operation, the controller structure 7 designed for field-oriented control, wherein PWM default values PWM1, PWM2, PWM3 for the inverter 1 by means of a PWM generator 8th Based on target current values Isd *, Isq *, which are specified in the d, q-Zweigrößensystem, taking into account actual measured phase currents Is1, Is2, Is3 are determined. To determine the phase currents Is1, Is2, Is3 are current sensors 9 used to allow the most accurate possible regulation. By means of the obtained PWM default values PWM1, PWM2, PWM3 becomes the inverter 1 triggered or via the Brückenabgriffe the phases U, V, W of the induction machine 4 , Further features of the controller structure 7 are related to 4 described in more detail.

In the event of an error, ie as a result of detecting an error, the controller structure becomes 7 - As mentioned above - on the control structure 10 according to 4 switched, which is designed for field-oriented control (FOS), in particular with adjustable dynamics. In the course of switching, which by a circuit breaker monitoring device, arrow A in 3 and 4 , the regulator structure 7 (not shown) is triggered, among other things, the current sensors 9 the controller structure 7 switched off, so that a feedback of actual values Is1, Is2, Is3 is omitted at an input. By means of the tax structure now provided 10 , whose functionality is to be explained in more detail below, can nevertheless be determined suitable desired variables for the rotary field machine operation.

The tax structure 10 of the drive system 6 according to 4 uses a position sensor 11 or position sensor of the controller structure 7 , eg in the form of an incremental encoder or a resolver, which determines the mechanical angular velocity of the rotor or pole wheel of the induction machine 4 serves. The position transmitter 11 For example, provides a position signal in the form of an angle signal, for example, the mechanical angle θ _mech , which the rotor, for example, with a reference point on the stator of the induction machine 4 includes.

The tax structure 10 also has a first functional unit 12 , which by means of a microcontroller or a microcomputer of the controller structure 7 can be formed on, with the first functional unit 12 is provided, in particular taking into account an actual, determined electrical angular velocity ω _{el of} the rotor and predetermined d, q current components voltage specifications or nominal voltage values for a (stator) longitudinal voltage component or d-voltage component and a (stator) transverse stress component or q Voltage component each in the d, q-two-size system using respective FOS algorithms to determine and provide. The d, q two-size system denotes a coordinate system which rotates in a known manner with the rotor.

The first functional unit 12 has an entrance 13 to which the target current components Sollquerstrom I _sq and Solllängsstrom I _{sd of} the respective current sampling step, characterized characterized by the indexing _{_k} , in the d, q-Zweigrößensystem, as input quantities or specifications can be fed to a desired for normal operation torque on the induction machine 4 depending on their speed via the desired transverse current I _{sd_k} and the desired longitudinal current I _{sq_k} in the respective sampling step of the duration T set. The set current specifications I _{sd_k} , I _{sq_k} are _specified , for example, on the basis of a user input. It should be noted that the indexing _s the stator reference, ie a size regarding the stator of the induction machine 4 expresses.

i.e. basierend auf der Winkelinformation des Positionsgebers 11, als auch in Abhängigkeit der Polpaarzahl Zp auf bekannte Weise ermittelt. Eine dazu entsprechend ausgebildete zweite Funktionseinheit 15 kann z.B. Teil des Positionssensors 11 oder alternativ getrennt davon gebildet sein, z.B. integral mit der ersten Funktionseinheit 12. Der Eingang 14 ist z.B. mit einem Ausgang der zweiten Funktionseinheit 15 verbunden, z.B. mittels einer elektrischen Verbindungsleitung 16. Furthermore, the first functional unit 12 an entrance 14 on, on which as an additional input the actual electrical angular velocity ω _{el of} the rotor is provided. The electrical angular velocity ω _el is based on the determined mechanical angle θ _mech, for example, by considering the temporal change of the mechanical angle θ _mech accordingly

ie based on the angle information of the position sensor 11 , as well as determined in dependence on the number of pole pairs Zp in a known manner. A correspondingly trained second functional unit 15 can eg be part of the position sensor 11 or alternatively be formed separately therefrom, eg integrally with the first functional unit 12 , The entrance 14 is eg with an output of the second functional unit 15 connected, for example by means of an electrical connection line 16 ,

The first functional unit 12 is _according to the invention for determining _setpoint voltage _components U _{sd_k} , U _{sq_k} in the d, q two-size system in a current sampling step based on setpoint voltage _components U _{sd_k-1} , U _{sq_k-1} and / or setpoint current components I _{sd_k-1} , I _{sq_k-1 of} the d, q Trained in the previous sampling step, wherein the determined _setpoint voltage _components U _{sd_k} , U _{sq_k} , in particular a Solllängsspannungs- and a desired transverse stress component U _{sd_k} , U _{sq_k} , for controlling the _{induction machine} 4 be provided, for example at an exit 17 the first functional unit 12 , In other words, by means of the first functional unit 12 d, q- _target voltage _values U _{sd_k} , U _{sq_k} , in particular a desired longitudinal stress component U _{sd_k} and a desired lateral stress component U _{sq_k of} the current sampling step in dependence on d, q _target voltage _values U _{sd_k-1} , U _{sq_k-1} and / or d, q-set current values or defaults I _{sd_k-1} , I _{sq_k-1 of} the previous sampling step, ie according to an iterative method.

In the determination of the d, q-set voltage _components U _{sd_k} , U _{sq_k} in the respective current sampling step, in particular the desired longitudinal stress component U _{sd_k} in the d, q two-gram system are dependent on a desired longitudinal component I _{sd_k-1} and / or a nominal longitudinal component U _{sd_k-1} and / or the desired transverse stress component U _{sq_k} in the d, q two-gram system as a function of a desired transverse current component I _{sq_k-1} and / or a desired transverse stress component U _{sq_k-1} respectively of the preceding sampling step, in particular by the first functional unit 12 , By taking into account target specifications or components of the respective preceding scanning step in the current scanning step, advantageously a highly dynamic control can be realized.

The determination of the nominal longitudinal stress component U _{sd_k} by, in particular, the first functional unit 12 in the current sampling step, based on the determination of the solution of a relation, in particular an equation A), in which the setpoint longitudinal voltage U _{sd_k of} the current sampling step is a function of the setpoint longitudinal voltage U _{sd_k-1 of} the preceding sampling step and / or a function of the nominal longitudinal current I _{sd_k-1} of the preceding sampling step and / or a function of the desired _transverse current I _{sq_k of} the current sampling step.

In the same way, the determination of the nominal transverse stress component U _{sq_k is carried out} by, in particular, the first functional unit 12 in the current sampling step based on the determination of the solution of a relation, in particular an equation B), in which the desired transverse voltage U _{sq_k of} the current sampling step is a function of the desired lateral voltage U _{sq_k-1 of} the preceding sampling step and / or a function of the nominal transverse current I _{sq_k-1 of} the preceding sampling step and / or a function of the setpoint _longitudinal current I _{sd_k of} the current sampling step.

und Gleichung B) für die (Stator-)Sollquerspannungskomponente

gelöst. In the respective current or to be performed sampling step are relations, in particular equation A) for the (stator) Solllängsspannungskomponente:

and equation B) for the (stator) desired lateral stress component

solved.

The determined _{setpoint voltages} U _{sd_k} , U _{sq_k} or corresponding signals are at the output 17 the first functional unit 12 provided. The equations A) and B) are, for example, in a read-only memory of the first functional unit 12 deposited or are loaded, for example, depending on demand in a volatile memory, on which the first functional unit 12 accesses.

In the, particularly discrete, equations A) and B), the indexing _{_k} , as already mentioned, also the sizes of the current and _{_k-1} the sizes of the previous sampling step of duration T and _s the stator reference, ie a size related to the stator of induction machine 4 , U _{sd_k} or U _{sd_k-1} designate the nominal longitudinal stress component, U _{sq_k} or U _{sq_k-1} , respectively, the nominal transverse stress component, ie in each case specifications for, for example, further functional units of the drive system 6 or for controlling the induction machine 4 ,

T _Ed denotes a time constant resulting from L _sd / R and L _{sd is} the longitudinal component of the inductance of the stator winding, T _Eq a time constant resulting from L _sq / R and L _sq the _{transverse component of} the inductance of the stator winding, I _{sd_k} or I _{sd_k-1} the predetermined nominal longitudinal current component, I _{sq_k} or I _{sq_k-1} the predetermined target transverse current component, R the ohmic winding resistance of the stator winding, ω _el the electrical angular velocity and Ψω _el as the assumed pole wheel or rotor voltage for a particular very small or short sampling step of duration T, where Ψ represents the Polradflussfluss. The pole wheel voltage is determined, for example, by means of stored characteristic curves.

The winding resistance R is for example stored or in individual cases corresponding to the respective induction machine 4 given, for example, also in a memory for the first functional unit 12 deposited. The Polradspannung Ψω _el is assumed to be constant, since normally the mechanical time constant of the induction machine 4 is greater than the electrical time constant. The speed can be considered constant during the rapid change of the current.

The d, q current setpoints I _{sd_k-1} and I _{sq_k-1} of the preceding sampling step, respectively, which are required for solving the equations A) and B) in a current sampling step _{_k} are also stored in a memory for the first one, for example functional unit 12 deposited. The deposit and access to the stored values is in particular by the first functional unit 12 causes. The memory is for example a volatile or a RAM memory.

According to the equations A) and B), the dynamics of a field-oriented control (FOS), which by means of the first switchable functional unit 12 the controller structure 7 can be realized or made possible, this advantageously be set randomly over the time constants T ₁ and T ₂ , for example by additional transmission elements. The time constants T _Ed and T _{Eq of} the (control) path can thus be advantageously compensated. A feedback of actual values of the longitudinal and transverse flow components to an input for the purpose of the target / actual comparison is - in contrast to the field-oriented control (FOR) - now no longer required, so that suitable setpoints for the continued operation of the induction machine 4 in the event of a fault after switching off the current sensor 9 are still available.

The tax structure 10 also has, for example, a third functional unit 18 which is intended to that of the first functional unit 12 provided d, q-set voltage _components U _{sd_k} , U _{sq_k} in particular by means of an inverse Park and Clarke transformation, into voltages or setpoint voltage values U _s1 , U _s2 , U _s3 a multi-phase three-phase system, in particular a three-phase three-phase system to convert, for example also within the respective current sampling step.

The third functional unit 18 has an entrance 19 on, which with the exit 17 the first functional unit 12 is connected, eg via electrical connection lines. The first functional unit 12 in particular, downstream third functional unit 18 , is designed in particular as a signal converter or as a transformation unit, which, for example, in the first functional unit described above 12 for solving the equation A) and B) is integrated or alternatively, for example, by means of another, separate functional unit is formed, for example in the form of an electronic circuit, such as a microcontroller or microcomputer.

To determine the setpoint voltage values U _s1 , U _s2 , U _s3 in the multi-variable three-phase system, the third functional unit is used 18 Also provided an angle information available, ie the actual electrical angle θ _{el of} the rotor resulting from the mechanical angle as a function of the number of pole pairs Z _p communicated. This size is from another, fourth functional unit 20 Alternatively, for example, from the second functional unit 15 , eg based on the angle information of the position sensor 11 ascertained in a known manner and, for example, another input 21 the third functional unit 18 provided with an output of the fourth functional unit 20 communicates.

Based on that of the third functional unit 18 at an exit 22 output nominal voltages U _s1 , U _s2 , U _s3 are then PWM default values PWM1, PWM2, PWM3 generated, which correspond to values with which the induction machine 4 would be properly operated in normal operation.

The conversion of the nominal voltage values U _s1 , U _s2 , U _s3 to PWM default values PWM1, PWM2, PWM3 is effected, for example, by a fifth functional unit in the form of the PWM generator 8th , which is formed as a vector modulator or space vector pulse width modulator and which also has the DC voltage U _{dc of} the intermediate _circuit of the inverter 1 is supplied as a further input variable, ie to an input 23 , The nominal voltage values U _s1 , U _s2 , U _s3 are present at an input 24 the fifth functional unit 8th On, the PWM default values PWM1, PWM2, PWM3 are at an output 25 to disposal. The fifth functional unit 8th is for example in one of the functional units described above 12 . 18 , ... integrated or eg alternatively formed separately.

With the exit 25 the fifth functional unit 8th connected is the entrance 26 a sixth functional unit 27 , which in the course of switching the controller structure 7 is switched to the control operating mode and the output side of the inverter 1 controls, ie its driver stage.

The sixth functional unit 27 is designed, during the duration of an error state of a circuit breaker, eg T1, to set the PWM default value for the defective phase, eg phase U, which _is referred to as PWM _d in the context of the present invention, and subsequently exclusively to the constant PWM Default value PWM _{d, n} for the further operation of the induction motor for the defective phase output. Furthermore, the sixth functional unit 27 designed to determine and output respectively optimized PWM default values PWM _{i, n} for the further, intact phases which are modified, in particular optimized, compared with the PWM default values, which are applicable to normal operation and determined in the control operating mode, designated PWM _i ,

For this purpose, the sixth functional unit uses Equation 1) for each intact phase: PWM _{i, n} = (PWM _{d, n} - PWM _d ) + PWM _i .

Equation 1) here takes into account, as can be seen, a deviation of the PWM default value PWM _d , which would apply to the defective phase in an intact state, from the constant PWM setpoint PWM _{d, n} , the value of which, as described above, again depends on the position of the PWM defective circuit breaker in the associated half-bridge depends.

In order to obtain an optimized PWM default value PWM _{i, n} for each of two intact phases, the corresponding PWM default value for the respective phase obtained in the control operating mode is entered in equation 1) together with the default values PWM _{d, n} and PWM _{d is} inserted into Equation 1.

In the following, aspects of the method will be explained in more detail by way of example.

Assuming a short circuit at the power switch T1 above, the PWM default value PWM1 corresponds to 4 , which in the control operating mode of the controller structure 7 The position of the short-circuited circuit breaker T1 in the associated half-bridge is high-side, so that the constant PWM default value is set to 100%, the PWM preset value PWM _d according to Equation 1) for the failure-affected and defective phase U. is, ie PWM _{d, n} = 100%, corresponding to PWM1n in 4 , Only this constant PWM default value PWM _{d, n} is subsequently output for the defective phase U, at least as long as the fault continues. It should be noted that the position of the faulty switch, eg T1, detected by means of the monitoring device, arrow A, and as information of the sixth functional unit 27 is provided. For a short-circuited low-side switch, eg T2, alternatively 0% would be set and output as a constant PWM default value PWM _{d, n} .

The PWM default values PWM _i , corresponding to PWM2 and PWM3 in 4 , for the other two, controllable by means of intact circuit breakers Phases V and W are now each optimized by means of equation 1) and output as optimized PWM default values PWM _{i, n} , in the example PWM2n and PWM3n, 4 ,

For this purpose, for phase V the optimized PWM default value PWM2n, corresponding to PWM _{i, n} according to equation 1, is determined by means of equation 1 as follows: PWM2n = (PWM1n - PWM1) + PWM2

The optimized PWM default value PWM3n for the phase W, corresponding to PWM _{i, n} according to equation 1, is likewise determined by means of equation 1: PWM3n = (PWM1n - PWM1) + PWM3

The determination of the optimized PWM default values PWM2n and PWM3n takes place here in parallel, alternatively, for example, serially. The optimized PWM default values PWM2n and PWM3n are provided by the functional unit 27 eg calculated and to the inverter 1 or its driver stage for the corresponding control of the power switches T3 to T6 for the phases V, W output, wherein the equation 1 is stored in a memory, for example in a read only memory of the sixth functional unit 27 or in a memory to which the sixth functional unit 27 accesses. The constant PWM default value PWM1n is output for the phase U. The constant PWM preset value PWM _{d, n} described above is subsequently outputted for voltage vectors to be set, ie each sampling step, the optimized PWM default values PWM _{i, n} for the further phases are respectively newly determined and output as a function of the voltage vector currently to be set, ie per scanning step.

The sixth functional unit 27 is realized by means of an electronic circuit in the form of a microcontroller, but in general, for example, in one of the functional units described above 12 . 18 integrated or, for example, alternatively be formed separately, for example by means of software.

The means of the switchable controller structure 7 formed drive system 6 can be advantageous in a fault condition of a circuit breaker T1 to T6 for further operation of the induction machine 4 be used.

LIST OF REFERENCE NUMBERS

1

inverter

2

DC

3

Link capacitor

4

Induction machine

5

short circuit

6

drive system

7

controller structure

8th

PWM generator

9

current sensors

10

tax structure

11

position sensor

12

first functional unit

13

entrance 12

14

another entrance 12

15

second functional unit

16

connecting line

17

output 12

18

third functional unit

19

entrance 18

20

fourth functional unit

21

another entrance 18

22

output 18

23

entrance 8th

24

entrance 8th

25

output 8th

26

entrance 27

27

sixth functional unit

T1 ... T6

breakers

AND MANY MORE

phases

A

Circuit breaker monitoring device

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19804967 A1 [0003]

Claims (14)

Method for operating a rotating field machine ( 4 ), in particular a permanent-magnet synchronous machine (PMSM), to an inverter ( 1 ), wherein the operation of the induction machine ( 4 ) PWM default values are determined for each phase (U, V, W) thereof, corresponding to which circuit breaker (T1, ... T6) of the inverter ( 1 ) a voltage vector at the induction machine ( 4 ), characterized in that as a result of the recognition of a fault, in particular a short circuit ( 5 ), a circuit breaker (T1 ... T6) in a first step, in a second step, a PWM default value (PWM _d ) for further operation of the induction machine ( 4 ) for the means of the defective circuit breaker (T1 ... T6) to be supplied phase (U, V, W) of the induction machine ( 4 ) is set constant and output as a constant PWM default value subsequently (PWM _{d, n} ), while for the other phases (U, V, W) of the rotary field machine ( 4 ) repeatedly optimized PWM default values (PWM _{i, n} ) are determined and output. A method according to claim 1, characterized in that an optimized PWM default value for each one of the further phases (U, V, W) by means of the equation PWM _{i, n} = (PWM _{d, n} - PWM _d ) + PWM _i where PWM _{i, n} denotes an optimized PWM default value for the respective further phase and PWM _i denotes a PWM default value for the same phase, where PWM _{d, n} the constant set PWM default value for the erroneously controllable phase and PWM _d a PWM default value for the same phase. Method according to one of the preceding claims, characterized in that by means of the optimized PWM default values (PWM _{i, n} ) a voltage vector at the induction machine ( 4 ) is set, which leads on average to no braking torque and / or no excessive phase current. Method according to one of the preceding claims, characterized in that the constant PWM default value PWM _{d, n} , in particular as a function of the position of the defective circuit breaker (T1 ... T6) in its half-bridge, is set to 100% or 0%. Method according to one of the preceding claims, characterized in that the optimized PWM default values (PWM _{i, n} ) are limited as a function of exceeding a threshold value and output as limited PWM default values. Method according to one of the preceding claims, characterized in that by means of the PWM default values (PWM _i ), the constant set value (PWM _{d, n} ), the optimized PWM default values (PWM _{i, n} ) and the limited default values PWM- Duty cycles for a phase (U, V, W) are expressed. Method according to one of the preceding claims, characterized in that in an intermediate step between the first and the second step of a controlled operation of the induction machine ( 4 ) to a controlled operation of the induction machine ( 4 ) or switched to a regulated operation with current estimation. A method according to claim 7, characterized in that the operation of the induction machine ( 4 ) after a switching, in particular the controlled operation or the controlled operation with current estimation, by means of a for normal operation of the induction machine ( 4 ) used controller structure ( 7 ) he follows. Method according to one of claims 7 or 8, characterized in that the controlled operation by means of a field-oriented control, in particular with adjustable dynamics, or the controlled operation after switching by means of a field-oriented control with current estimation. Method according to one of claims 7 to 9, characterized in that the PWM default values (PWM _i ) are determined after switching to a control operating mode or to a control operating mode with current estimation in the respective operating mode. Method according to one of claims 7 to 10, characterized in that after the first step, in particular in the intermediate step, at least one current sensor ( 9 ) of the controller structure ( 7 ), which for the operation of the induction machine ( 4 ) is provided, is turned off. Drive system ( 6 ) for an induction machine ( 4 ), in particular a permanent magnet synchronous machine (PMSM), wherein the drive system ( 6 ) a controller structure ( 7 ) and one in the controller structure ( 7 ) included inverters ( 1 ) for the operation of the induction machine ( 4 ), wherein the drive system ( 6 ) for detecting a fault in a circuit breaker (T1 ... T6) of the inverter ( 1 ), characterized in that the drive system ( 6 ) is designed for carrying out the method according to one of the preceding claims. Drive system ( 6 ) according to claim 12, characterized in that the controller structure ( 7 ) for the operation of the induction machine ( 4 ) in response to a detected at a circuit breaker (T1 ... T6) error on a control structure ( 10 ) for field-oriented control of the induction machine ( 4 ) is switchable, in particular for field-oriented control with adjustable dynamics, or to a controller structure for field-oriented control with current estimation. Drive system ( 6 ) according to one of claims 12 or 13, characterized in that the drive system ( 6 ) one by means of the inverter ( 1 ) operable induction machine ( 4 ) having.

Images