阅读说明：本技术 用于运行同步电机的方法 (Method for operating a synchronous machine ) 是由 A.耶格尔 M.贝克 U.沃尔默 于 2018-12-17 设计创作，主要内容包括：用于运行同步电机的方法,具有如下步骤：-针对半桥的开关元件(T1...T6)生成居中的经脉冲宽度调制的切换信号,其中所述开关元件(T1...T6)中的分别两个开关元件接线成分别一个半桥,其中每个半桥的第二开关元件(T4...T6)与每个半桥的第一开关元件(T1...T3)互补地被操控,只要由此提供足够的最小测量时长(T<Sub>M</Sub>),在所述最小测量时长期间,两个半桥的开关元件(T1...T6)的切换信号处在不同的电位上；-否则：-针对所述半桥的开关元件(T1...T6)生成如下经脉冲宽度调制的切换信号,所述经脉冲宽度调制的切换信号与居中至少偏差得大得使得提供足够的最小测量时长(T<Sub>M</Sub>),其中-所述开关元件(T1...T6)的切换信号被构造为使得避免了在所述开关元件(T1...T6)的切换信号中与所述最小测量时长(T<Sub>M</Sub>)相对应的时间突变；而且-在所提供的最小测量时长(T<Sub>M</Sub>)之内执行1-分流器-电流测量。(Method for operating a synchronous machine, comprising the following steps: -generating a centered pulse-width-modulated switching signal for the switching elements (T1.. T6) of the half-bridges, wherein in each case two of the switching elements (T1.. T6) are connected in a respective half-bridge, wherein the second switching element (T4.. T6) of each half-bridge is operated complementary to the first switching element (T1.. T3) of each half-bridge, as long as a sufficient minimum measuring time (T1.. T3) is thereby provided M ) During the minimum measurement period, the switching signals of the switching elements (T1.. T6) of the two half-bridges are at different potentials; -otherwise: -generating a pulse-width-modulated switching signal for the switching elements (T1.. T6) of the half bridge, which pulse-width-modulated switching signal deviates from centering at least so much that a sufficient minimum measuring time duration (T) is provided M ) Wherein the switching signal of the switching element (T1.. T6) is designed in such a way that a switching signal of the switching element (T1.. T6) which is equal to the minimum measurement time (T) is avoided M ) Corresponding time mutation; and-at the provided minimum measurement duration (T) M ) Within which a 1-shunt-current measurement is performed.)

1. Method for operating a synchronous machine, comprising the following steps:

-generating a centered pulse-width-modulated switching signal for the switching elements (T1.. T6) of the half-bridges, wherein in each case two of the switching elements (T1.. T6) are connected in a respective half-bridge, wherein the second switching element (T4.. T6) of each half-bridge is operated complementary to the first switching element (T1.. T3) of each half-bridge, as long as a sufficient minimum measuring time (T1.. T3) is thereby provided_M) During the minimum measurement period, the switching signals of the switching elements (T1.. T6) of the two half-bridges are at different potentials;

-otherwise:

-generating a pulse-width-modulated switching signal for the switching elements (T1.. T6) of the half bridge, which pulse-width-modulated switching signal deviates from centering at least so much that a sufficient minimum measuring time duration (T) is provided_M) Wherein

-the switching signal of the switching element (T1.. T6) is configured such that a switching signal of the switching element (T1.. T6) with the minimum measuring duration (T) is avoided_M) Corresponding time mutation; and is

-at the provided minimum measurement duration (T)_M) Within which a 1-shunt-current measurement is performed.

2. Method according to claim 1, wherein in case the switching signals of a first switching element (T1, T3, T5) have a defined similar duty cycle, the first switching element (T1, T3, T5)Wherein the rising edges of the three switching signals of the 1-shunt-current measurement are fixed with respect to their time sequence with respect to one another and are designed such that a minimum measurement time (T) between the switching signals of the first switching element (T1, T3, T5) is obtained_M) Is provided, wherein the 1-shunt-current measurement is performed in the first half of a PWM cycle with a rising edge of the switching signal of the first switching element (T1, T3, T5).

3. Method according to claim 1, wherein in the case of switching signals of a first switching element (T1, T3, T5) having a defined similar duty cycle, the falling edges of the three switching signals of the first switching element (T1, T3, T5) in which a 1-shunt-current measurement is carried out are fixed in terms of their chronological order with respect to one another and are configured such that a minimum measurement time duration (T1, T3, T5) between the switching signals of the first switching element (T1, T3, T5) is the smallest_M) Is provided, wherein the 1-shunt-current measurement is performed in the latter half of a PWM cycle with a falling edge of the switching signal of the first switching element (T1, T3, T5).

4. Method according to claim 2 or 3, wherein the duty cycles of the three switching signals of the switching elements (T1, T3, T5) are similar and the difference in the duty cycles of the three switching signals is preferably less than about 20% to about 30%.

5. Method according to claim 1, wherein in the case of at least two switching signals of a first switching element (T1, T3, T5) having a different duty cycle which is of a defined magnitude, wherein the duty cycles differ by more than approximately 25% to approximately 100%, in the case of a change in the magnitude ratio of the switching signals on transition from one switching cycle to the next, the switching signals are constructed such that the 1-shunt-current measurement is carried out in each case on edge transitions of the switching signals.

6. Method according to one of the preceding claims, wherein the method is performed for a permanent magnet synchronous machine or for an externally excited synchronous machine.

7. Device (200) for operating a synchronous machine, comprising:

a generating device (210) for generating a centered pulse-width-modulated switching signal for the switching elements (T1.. T6) of the half bridges, wherein in each case two of the switching elements (T1.. T6) are connected in each case one half bridge, wherein the second switching element (T4.. T6) of each half bridge is operated complementary to the first switching element (T1.. T3) of each half bridge, as long as a sufficient minimum measuring duration (T1.. T3) is thereby provided_M) During the minimum measurement period, the switching signals of the switching elements (T1.. T6) of the two half-bridges are at different potentials,

-otherwise: for generating a pulse-width-modulated switching signal for the switching elements (T1.. T6) of the half bridge, which is at least offset from centering by such an amount that a sufficient minimum measuring time (T) is provided_M）；

-wherein by means of the generating device (21), the switching signal of the switching element (T1.. T6) can be configured such that a time jump in the switching signal of the switching element (T1.. T6) corresponding to the minimum measuring time duration is avoided; and

-a measuring device (220) for performing a 1-shunt-current measurement, wherein a defined minimum measuring duration (T) is provided by means of a switching signal of the switching element (T1.. T6)_M) During the minimum measurement period, the two switching signals of the half-bridge are at different potentials.

8. Computer program product for carrying out the method according to one of claims 1 to 6, when the computer program product is run on a device (100) for operating a synchronous machine (200) or is stored on a computer-readable storage medium.

Technical Field

The invention relates to a method for operating a synchronous machine. The invention also relates to a device for operating a synchronous machine. The invention also relates to a computer program product.

Background

It is known to use permanent magnet synchronous machines as drives for fans, for example radiator fans in the motor vehicle sector. Sensorless regulation of synchronous machines, that is to say regulation without the use of a rotor orientation (Rotorlage) sensor, is also known. Then, the rotor orientation is determined from the induced voltage (BEMF, back electromotive force, electromotive force EMK) of the synchronous motor.

In order to control or regulate a synchronous machine, the phase currents of the synchronous machine need to be known in many cases. For example, phase currents are required as input variables for the sensorless rotor angle estimation method or for the control method.

In a cost-optimized solution, the phase currents are determined by means of only one shunt ("1-shunt-current measurement") in the common ground or supply path of the half-bridge.

DE 102015202693 a1 discloses a method for determining a branch current in an electrical polyphase system.

Disclosure of Invention

The task of the invention is that: a method for improved operation of a synchronous machine is provided.

According to a first aspect, the object is achieved by a method for operating a synchronous machine, having the following steps:

generating centered pulse-width-modulated switching signals for the switching elements of the half-bridges, wherein in each case two of the switching elements are connected to in each case one half-bridge, wherein the second switching element of each half-bridge is operated complementary to the first switching element of each half-bridge, as long as a sufficient minimum measuring period is provided thereby, during which the switching signals of the switching elements of the two half-bridges are at different potentials;

-otherwise:

generating pulse-width-modulated switching signals for the switching elements of the half-bridges, which are at least greatly offset from centering in such a way that a sufficient minimum measuring duration is provided, wherein

The switching signals of the switching elements are designed such that time jumps in the switching signals of the switching elements corresponding to the minimum measuring time duration are avoided; and also

-performing a 1-shunt-current measurement within the provided minimum measurement duration.

In this way, a noise-optimized operation of the sensorless synchronous machine can be achieved with a specifically non-centered control signal, since time jumps are avoided which vary the measurement duration in the phase signal.

According to a second aspect, the object is achieved by an apparatus for operating a synchronous machine, having:

generating means for generating centered pulse-width-modulated switching signals for the switching elements of the half-bridges, wherein in each case two of the switching elements are connected to in each case one half-bridge, wherein the second switching element of each half-bridge is operated complementary to the first switching element of each half-bridge, as long as a sufficient minimum measuring period is provided thereby, during which the switching signals of the switching elements of the two half-bridges are at different potentials,

-otherwise: for generating pulse-width-modulated switching signals for the switching elements of the half-bridges, which deviate from centering at least so much that a sufficient minimum measuring duration is provided,

wherein by means of the generating device, the switching signals of the switching elements can be constructed such that time jumps in the switching signals of the switching elements corresponding to the minimum measuring duration are avoided; and

a measuring device for carrying out a 1-shunt current measurement, wherein a defined minimum measuring time period is provided by means of the switching signals of the switching elements, during which minimum measuring time period the two switching signals of the half bridge are at different potentials.

Preferred embodiments of the method for operating a synchronous machine are the subject matter of the dependent claims.

A preferred embodiment of the method provides for: in the case of switching signals of the first switching elements having a defined, similar duty cycle, the rising edges of the three switching signals of the first switching elements, in which the 1-shunt-current measurement is performed, are fixed in terms of their chronological order with respect to one another and are configured such that a minimum measurement time duration between the switching signals of the first switching elements is provided, wherein the 1-shunt-current measurement is performed in the first half of the PWM cycle in the case of the rising edges of the switching signals of the first switching elements. In this way, a scenario is considered during operation of the synchronous machine, which enables a low motor power or rotational speed due to the small difference in the duty cycle.

A further preferred embodiment of the method is characterized in that: in the case of switching signals of the first switching elements having a defined, similar duty cycle, the falling edges of the three switching signals of the first switching elements, in which the 1-shunt-current measurement is performed, are fixed in terms of their chronological order with respect to one another and are configured such that a minimum measurement time duration between the switching signals of the first switching elements is provided, wherein the 1-shunt-current measurement is performed in the latter half of the PWM period in the case of the falling edges of the switching signals of the first switching elements. In this way, a similar scenario as described before is provided for the synchronous machine, wherein in this case the 1-shunt-current measurement is performed in the case of a falling edge of the switching signal.

Another preferred embodiment of the method is characterized in that: the duty cycles of the three switching signals of the switching elements are similar and the difference in the duty cycles of the three switching signals is preferably less than about 20% to about 30%. In this way, the method can be applied to a plurality of different construction schemes of the switching signal. Preferably, the difference in the duty cycles of the three switching signals is therefore small (that is to say the difference in the duty cycles is up to approximately 20-30%) or the motor voltage amplitude ("total duty cycle") is approximately 20-30% at the maximum. The absolute values of the duty cycles of the three switching signals are advantageously uncorrelated, for example the three duty cycles may be 60% or 70% or 80%, and the method may advantageously also function in these cases, since the maximum difference in duty cycles is only 20%.

Another preferred embodiment of the method is characterized in that: in the case of at least two switching signals of the first switching element having a defined, large, different duty cycle, wherein the difference in duty cycle is greater than approximately 25% to approximately 100%, in the case of a change in the size ratio of the switching signals at the transition from one switching cycle to the next, the switching signals are designed such that the 1-shunt-current measurements are carried out in each case at the transition of the edges of the switching signals. In this case, a scenario is covered during the operation of the synchronous machine, in which a high machine voltage occurs due to the large difference in the duty cycle of the control signal. In this case, a very quiet operation of the synchronous machine can also be supported.

Another preferred embodiment of the method provides for: the method is performed for a permanent magnet synchronous machine or for an externally excited synchronous machine. In this way, the method can advantageously be used for structurally different synchronous machines.

The invention is described in detail below with additional features and advantages in accordance with the following figures. In which elements that are identical or functionally identical have the same reference numerals. These drawings are particularly intended to clarify the principles that reflect the essence of the invention.

The disclosed device features are analogously derived from corresponding disclosed method features, and vice versa. This means in particular that: the features, technical advantages and embodiments with regard to the method aspect for operating a synchronous machine derive from corresponding embodiments, features and advantages with regard to the device aspect for operating a synchronous machine and vice versa.

Drawings

In the drawings:

fig. 1 and 2 show a schematic diagram for explaining the operating principle of a conventional 1-shunt current measurement of a synchronous machine;

fig. 3 to 5 show signal diagrams for illustrating the operating principle of the operation of the synchronous machine;

fig. 6 shows a diagram for explaining the sector changes when the synchronous machine is operating;

fig. 7 to 8 show time diagrams with control signals according to a conventional method for operating a synchronous machine;

9-10 show a schematic diagram of a first embodiment of a method for operating a synchronous machine;

FIGS. 11-12 show schematic diagrams of another embodiment of a method for operating a synchronous machine;

fig. 13 shows a flow chart of the proposed method for operating a synchronous machine; and is

Fig. 14 shows a schematic block diagram of the proposed device for operating a synchronous machine.

Detailed Description

Fig. 1 shows a schematic block diagram of a conventional device for operating a synchronous machine, which is actuated by means of a pulse-width-modulated electrical control signal. Preferably, the device comprises three half bridges with switching elements T1.. T6 which generate the mentioned control signals for the phase windings of the synchronous machine.

Exemplarily, this is shown below for a 3-phase system with three phase connection terminals U, V, W and a B6 bridge configuration with three half-bridges T1-T2, T3-T4, T5-T6 or shunts R in the ground path of the half-bridges.

To enable current I from the shunt_RIt is concluded that three phase currents, six electronic switching elements T1.. T6 of the B6 bridge must have a defined switching pattern. For example, in switching mode 1 of FIG. 1, the shunt current I_RCorresponding to phase current U. In switching mode 2 of fig. 2, the shunt current I_RCorresponding to a negative phase current W.

Typically, the three phase voltages U, V and W are generated by means of Pulse Width Modulation (PWM), wherein a centered PWM steering signal is preferably, but not exclusively, used for this purpose.

Fig. 3 shows an example of a switching pattern of three high-side switches T1, T3, T5 during a PWM period with centered PWM generation and resulting shunt current I_R. In order to be able to determine the three phase currents during a PWM period, the shunt current I has to be detected in two different switching positions (one of the three high-side switches is closed or two of the three high-side switches are closed)_R. In the example of fig. 3, this would be possible in regions II and III or in regions V and VI. In this way, two of the three phase currents can be passed through the current divider I_RIs determined directly, wherein then the third phase current can be calculated by means of the electrical node rule.

To detect in a measurement-technical mannerCurrent of current divider I_RThere must be a minimum length of time for two switching modes (one of the three high side switches T1, T3, T5 closed or two of the three high side switches T1, T3, T5 closed). Thus, if the duty cycles at least two of the three phases are similar, a 1-shunt-current measurement is not possible without further measures. In the following example, a 1-shunt-current measurement would not be possible, since the duty cycles at the switching elements T3 and T5 are too similar, as can be seen in fig. 4.

In order to be able to realize a 1-shunt-current measurement also in this case, the two switching edges at least one of the three half-bridges T1-T2, T3-T4, T5-T6 have to be moved over time. In the following example, a determination of the phase currents by means of a 1-shunt current measurement is possible after shifting the switching edge at the switching elements T3, T5, as can be seen in fig. 5.

Which direction to move the edge of the PWM switching signal is typically determined based on the magnitude ratio of the duty cycles at the three phases. Fig. 6 shows the magnitude ratio of the duty cycles at the three phases U, V, W in terms of a vector diagram. In the case of so-called "sector changes", the direction in which these switching signals are moved is usually also changed. However, this results in a minimum measurement duration T during the sector change_MIs abruptly changed in the position of the switching edge and as a result of this, an abrupt change, which is often undesirable, occurs in the phase current profile. Depending on the application, these abrupt changes in phase currents may be critical in the noise performance of applications utilizing synchronous machines.

The following example of fig. 7 shows the resulting switching pattern before and after a sector change, where the following conditions apply before the sector change:

TV_W>TV_V>TV_U

wherein:

TV_W..

TV_V..

TV_U..

And the following conditions apply after sector change:

TV_V>TV_W>TV_U。

due to the respective change in the minimum measuring duration T generated in this way_MGenerates a transformed phase current having a resulting undesirable noise level.

It is thus proposed to arrange the phases of the switching signal such that the mentioned abrupt changes no longer occur.

Fig. 9 shows a first embodiment of the proposed method in a diagram on the right, which represents the switching signal without a modification according to the invention. It can be seen that: the duty cycles of the three switching signals are similar, wherein the difference in the duty cycles of the three switching signals is preferably less than about 20% to about 30%. In this case, the rising edges of the three switching signals are fixedly positioned during the sector change, so that a minimum measuring time period T for performing the 1-shunt-current measurement is provided_M。

This is also the case in the right-hand diagram of fig. 10, in which case the edges within the respective switching signals change only insignificantly and thus a quiet operation of the synchronous machine with regard to noise is achieved as a result. The result is thus that the three switching signals in the right-hand diagrams of fig. 9 and 10 are no longer centered.

From fig. 9 to fig. 10, the same sector conversion as in the conventional method from fig. 7 to fig. 8 is realized.

The following is not shown in these figures: the mentioned fixing of the switching signals is relative to the falling edges of the signals, so that even in this case no significant, noise-caused abrupt changes occur within the individual PWM switching signals.

Fig. 11 and 12 show another embodiment of the proposed method, wherein in this case there is a large difference between the duty cycles of at least two PWM switching signals, so that the method of fig. 9 and 10 may not be applicable. In this case, at the time of sector change, that is, at the transition from fig. 11 to fig. 12, the PWM switching signal is constructed or arranged such that one measurement is performed alternately at the rising edge (right diagram of fig. 11) or at the falling edge (right diagram of fig. 12) after the sector change. In this case too it can be seen that: the switching signal according to the right-hand diagram has no significant abrupt changes and thus produces a quiet phase current profile.

The result is that the three switching signals in the right-hand diagrams of fig. 11 and 12 in this variant are also definitively different from centered.

As a result, this corresponds to an embodiment which is used in particular for average and high motor voltage amplitudes, wherein the position of the switching edge is shifted in accordance with the magnitude ratio of the duty cycles at the three half-bridges, although 1-shunt current measurement would not be possible if the original (unchanged) switching pattern was used.

In this case, the shunt current I is carried out at the positive switching edge or at the negative switching edge at each sector change_RThe measurement of (2). By doing so, the position of the switching edges remains unchanged during the sector change, whereby abrupt changes in these switching edges and thus in the phase current profile are advantageously avoided.

If the current I of the shunt at the positive switching edge is measured_RWhen two switching signals of different phases have similar duty ratios, the switching signal at the phase with the larger duty ratio is shifted to the left, and the switching signal at the phase with the smaller duty ratio is shifted to the right. If the current I of the shunt at the negative switching edge is measured_RWhen the two phases have similar duty ratios, the switching signal at the phase with the larger duty ratio is shifted to the right, and the switching signal at the phase with the smaller duty ratio is shifted to the left.

In the following example according to fig. 12, at sector change:

TV_W>TV_V>TV_U

a transition is made from measuring the phase current at the positive switching edge to measuring the phase current at the negative switching edge. The position of the switching edge remains unchanged here.

Advantageously, the proposed method requires no additional hardware at all, but can be implemented merely by software, wherein suitable algorithms are stored in a microcontroller in a programmed manner. Thereby, a simple adaptivity or modifiability of the method is supported.

Advantageously, the proposed method can be implemented not only in the case of a permanent magnet synchronous machine but also in the case of an externally excited synchronous machine.

In the above, the proposed method is exemplarily described in terms of a three-phase synchronous machine, wherein it is however pointed out that the proposed method can also be used for single-phase, two-phase, four-phase, five-phase and more synchronous machines.

In the above, the proposed method is exemplarily described in terms of high side switches T1, T3, T5. It is however self-evident that: embodiments of the method are also possible with the aid of low-side switches T2, T4, T6.

Fig. 13 shows a principle flow of the proposed method for operating a synchronous machine.

In step 100, a generation of a centered pulse-width-modulated switching signal for the switching elements T1.. T6 of the half bridges is carried out, wherein in each case two of these switching elements T1.. T6 are wired in each case in one half bridge, wherein the second switching element T4.. T6 of each half bridge is operated in a complementary manner to the first switching element T1.. T3 of each half bridge, as long as a sufficient minimum measuring time period T is thereby provided_MDuring this minimum measurement period, the switching signals of the switching elements T1.. T6 of the two half bridges are at different potentials.

Otherwise, in step 110, switching elements T1.. T6 for the half-bridges are executed to generate pulse-width-modulated switching signals that deviate from centering at least so much that a sufficient minimum measuring time period T is provided_MWherein the switching signals of the switching elements T1.. T6 are configured such that a minimum measuring time period T in the switching signals of the switching elements T1.. T6 is avoided_MCorresponding time-wise abrupt change, ofAnd wherein the minimum measurement duration T is provided_MWithin which a 1-shunt-current measurement is performed.

Fig. 14 shows a schematic block diagram of an apparatus 200 for operating a synchronous machine. A generating device 210 can be seen for generating a centered pulse-width-modulated switching signal for the switching elements T1.. T6 (not shown) of the half bridges (not shown), wherein in each case two of these switching elements T1.. T6 are wired in each case in one half bridge, wherein the second switching element T4.. T6 of each half bridge is operated complementary to the first switching element T1.. T3 of each half bridge. The generating device is functionally connected to a measuring device 220 for carrying out a 1-shunt current measurement, wherein a defined minimum measuring time period T is provided by means of a switching signal of a switching element T1.. T6_MDuring this minimum measuring period, the two switching signals of the half bridge are at different potentials, wherein the switching signals of the switching element T1.. T6 can be designed by means of the generating device 210 such that switching signals of the switching element T1.. T6 which correspond to the minimum measuring period T are avoided_MCorresponding time mutation.

In the above, a person skilled in the art may also realize none or only part of the disclosed embodiments of the invention without deviating from the core of the invention.

There is a time break if the shift from left to right or vice versa from right to left from one PWM clock to the next. Preferably, the switching signals should change only slightly from one PWM clock to the next and should not have large abrupt, i.e. time-abrupt, changes. The shifting of these switching signals is preferably performed off-center to the right or to the left in order to obtain sufficient measurement time. In particular, a shift from a left to a right shift, or vice versa, from a right to a left shift from one PWM clock to the next PWM clock should be prevented.

The voltage vectors generated by the three half-bridges lie within a hexagon according to fig. 6. During operation of the synchronous machine, this voltage vector is usually rotated. Sector change means that: the voltage vector transitions from one sector to another sector of the hexagonal sectors.

In the known method, the PWM shift changes in both half-bridges at each sector change, one half-bridge changing from left to right and the other half-bridge changing from right to left. This causes noise, especially abrupt changes in time, and is eliminated by the present invention.