DE102014002303A1 - Method for performing space pointer modulation for pulse width modulation controller of e.g. alternating current induction motor, involves carrying out reference pointer approximation in order to synthesize reference pointer - Google Patents

Abstract

The method involves producing and scanning a reference signal with a sampling frequency to produce multiple reference sample values. Reference pointer approximation is carried out in order to synthesize a reference pointer, which is linked with one of the reference sample values. Reference pointer approximation active pointers (160) utilize one or multiple zero-pointers and pseudo zero-pointers. A part of the reference pointer is approximated by two neighboring active pointers, and a residual part of the reference pointer is approximated by two un-neighboring active pointers. An independent claim is also included for a control system.

Description

TERRITORY

The present disclosure relates to an apparatus and method for performing space vector modulation for PWM control to form AC waveforms using pseudo-zero vectors or for performing enhanced space vector modulation or performing both in, for example, engine control applications.

BACKGROUND

Space Vector Modulation (RZM) is an algorithm for controlling pulse width modulation (PWM). It is used for the generation of AC waveforms; mostly for driving with three-phase AC or three-phase AC driven electric motors with varying speeds from DC. There are many variations of RZM that result in different quality and computational requirements.

A three-phase inverter or three-phase inverter 100 as he is in 1 is shown, must be controlled so that never both switches are turned on in the same branch at the same time, otherwise the DC power supply would be shorted. This requirement can be met by the complementary actuation of the switches within a branch. That is, if A ⁺ is on, then A ^{- is} off and vice versa. This leads to eight possible switching pointers or switching vectors for the inverter 100 V ₀ to V ₇ , where there are six active switching vectors and two null vectors, as in the diagram 110 from 2 is illustrated.

To implement a space vector modulation, a reference signal V _{ref is} sampled with a frequency f _s (T _s = 1 / f _s ). The reference signal may be generated, for example, from three separate phase references using the αβγ transformation. The reference vector is then synthesized using a combination of the two adjacent active switching hands and one or both of the null pointers. There are several strategies for selecting the order of the pointers or vectors and which null pointer (s) should be used. The strategic selection of the hands will affect harmonic content and switching power dissipation.

SUMMARY

The present disclosure is directed to a method of performing space vector modulation for PWM control to form AC waveforms. The method includes generating and sampling a reference signal to produce reference samples, and performing a reference vector approximation to synthesize a reference vector associated with at least one of the reference samples. The reference pointer approximation uses active pointers, one or more null pointers, and one or more pseudo null pointers in the formation thereof.

In one embodiment of the method, the pseudo-vector comprises a combination of two active vectors having an angular difference between them of 180 °. In another embodiment, the two active pointers, which in combination form the pseudo pointer, have a scalar amplitude that is the same.

In another embodiment of the method, the pseudo-pointer has a combination of three active hands having an angular difference between them of 120 °. In yet another embodiment, the three active pointers, which in combination form the pseudo pointer, have a scalar amplitude that is the same.

In one embodiment of the method, the active pointers in the reference pointer approximation have adjacent active pointers. In another embodiment, a portion of the reference pointer is approximated by two adjacent active pointers, and a remaining portion of the reference pointer is approximated by two non-adjacent active pointers. In accordance with an embodiment, the portion of the reference pointer driven by active pointers is represented by a variable m, where 0≤m≤1, and the remainder of the reference pointer driven by active pointers passes through 1 - m represents. If m = 1, then the entire reference pointer driven by active pointers will be approximated by two adjacent pointers, and if m = 0, then the entire reference pointer driven by active pointers will be two non-adjacent active ones Pointer approximated. In one embodiment, the non-adjacent active pointers are separated from each other by 120 °.

In accordance with another embodiment of the disclosure, a control system includes a space vector modulator configured to receive a plurality of reference signal samples and perform a reference pointer approximation to synthesize a reference pointer associated with at least one of the reference signal samples. The reference pointer approximation uses active pointers, one or more null pointers, and one or more dummy null pointers in the formation thereof, wherein the space vector modulator outputs timing signals based on the reference pointer approximation. The control system further includes a pulse width modulation unit configured to receive the clock signals from the space vector modulator and output pulse width modulation control signals based thereon, and a three-phase inverter configured to receive the pulse width modulation control signals and based thereon of generating AC waveforms therefrom.

In one embodiment of the control system, a pseudo-pointer has a combination of two active pointers having an angular difference between them of 180 °. In another embodiment, the two active pointers, which in combination form the pseudo pointer, have a scalar amplitude that is the same.

In another embodiment of the control system, a pseudo-pointer comprises a combination of three active hands having an angular difference between them of 120 °. In yet another embodiment, the three active pointers, which in combination form the pseudo pointer, have a scalar amplitude that is the same.

In one embodiment of the control system, the active pointers in the reference pointer approximation have adjacent active pointers. In another embodiment, a portion of the reference pointer is approximated by two adjacent active pointers, and a remaining portion of the reference pointer is approximated by two non-adjacent active pointers. In one embodiment, the one part of the reference pointer is represented by a variable m, where 0 ≤ m ≤ 1, where the remaining part of the reference pointer is represented by 1-m. If m = 1, then the entire reference pointer driven by active pointers is approximated by two adjacent active pointers, and if m = 0 then the entire reference pointer driven by active pointers will be two non-adjacent ones approximates active pointers. In one embodiment, the non-adjacent hands are separated from each other by 120 °.

In one embodiment of the control system, the three-phase inverter includes a first series-connected switch pair connected together at a node forming a first phase output, a second series-connected switch pair connected together at a node forming a second phase output, and a third series-connected switch pair connected together at a node forming a third phase output. The inverter further includes a shunt resistor connected to a first terminal at a lower node of each of the first, second and third series-connected switch pairs and coupled to a second terminal at a reference potential, and an amplifier has first and second inputs respectively coupled to the first and second terminals of the shunt resistor, an output of the amplifier reflecting a current level flowing through the shunt resistor.

According to one aspect, there is provided a method of performing space vector modulation (RZM) for pulse width modulation (PWM) control to generate AC waveforms, comprising the steps of: generating a reference signal and sampling the reference signal at a sampling frequency to generate a plurality of Generate reference samples; and performing a reference pointer approximation to synthesize a reference pointer associated with at least one of the reference samples, wherein the reference pointer approximation uses active pointers, one or more null pointers, and one or more dummy null pointers in the formation thereof.

Advantageously, a pseudo-pointer has a combination of two active pointers having an angular difference between them of 180 °.

Advantageously, the two active hands, which in combination form the pseudo pointer, have a scalar amplitude which is the same.

Advantageously, a pseudo pointer has a combination of three active hands having an angular difference between them of 120 °.

Advantageously, the three active hands, which in combination form the pseudo-pointer, have a scalar amplitude which is the same.

Advantageously, the active pointers in the reference pointer approximation have adjacent active pointers.

Advantageously, a portion of the reference pointer is approximated by two adjacent active pointers and a remaining portion of the reference pointer is approximated by two non-adjacent active pointers.

Advantageously, one part of the reference pointer is represented by a variable m, where 0 ≤ m ≤ 1, and where the remaining part of the reference pointer is represented by 1-m, and if m = 1 the whole reference pointer is represented by two adjacent active ones Pointer is approximated, and where m = 0, the entire reference pointer is approximated by two non-adjacent active pointers.

Advantageously, the non-adjacent hands are separated from each other by 120 °.

In one aspect, a control system is provided with:
a space vector modulator configured to receive a plurality of reference signal samples and to perform a reference pointer approximation to synthesize a reference pointer associated with at least one of the reference signal samples, the reference pointer approximation including active pointers, one or more null pointers, and one or more pseudo-pointers; Uses null pointer in the formation thereof, and wherein the space vector modulator outputs clock signals based on the reference pointer approximation;
a pulse width modulation unit configured to receive the clock signals from the space vector modulator and to output pulse width modulation control signals based thereon; and
a three-phase inverter configured to receive the pulse width modulation control signals and generate AC waveforms based thereon.

Advantageously, a pseudo-pointer has a combination of two active pointers having an angular difference between them of 180 °.

Advantageously, the two active hands, which in combination form the pseudo pointer, have a scalar amplitude which is the same.

Advantageously, a pseudo pointer has a combination of three active hands having an angular difference between them of 120 °.

Advantageously, the three active hands, which in combination form the pseudo pointer, have a scalar amplitude which is the same.

Advantageously, the active pointers in the reference pointer approximation have adjacent active pointers.

Advantageously, a portion of the reference pointer is approximated by two adjacent active pointers and a remaining portion of the reference pointer is approximated by two non-adjacent active pointers.

Advantageously, one part of the reference pointer is represented by a variable m, where 0 ≤ m ≤ 1, and where the remaining part of the reference pointer is represented by 1-m, and if m = 1 the whole reference pointer is represented by two adjacent active ones Pointer is approximated, and where m = 0, the entire reference pointer is approximated by two non-adjacent active pointers.

Advantageously, the non-adjacent hands are separated from each other by 120 °.

Advantageously, the three-phase inverter has the following:
a first series-connected switch pair connected together at a node forming a first phase output;
a second series connected switch pair connected together at a node forming a second phase output;
a third series-connected switch pair connected together at a node forming a third phase output;
a shunt resistor connected to a first terminal at a lower node of each of the first, second, and third series-connected switch pairs and coupled to a second terminal at a reference potential; and
an amplifier having first and second inputs respectively coupled to the first and second terminals of the shunt resistor, an output of the amplifier reflecting a current level flowing through the shunt resistor.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments in accordance with the disclosure will be described in more detail in the following text with reference to the attached figures, in which:

1 Fig. 12 is a schematic diagram of a three-phase inverter for generating AC waveforms;

2 is a diagram showing various vectors for switching the switches of the three-phase inverter of 1 illustrated;

3 is a hex diagram illustrating the basic voltage space vectors from the graph of FIG 2 illustrated;

4 Fig. 16 is a hex diagram illustrating a reference pointer approximation in accordance with conventional techniques;

5 Figure 12 is a graph illustrating the normalized time versus a reference vector angle for a conventional space vector modulation (RZM) and space vector modulation, respectively;

6A - 6E Hexagrams are illustrative of a basic pseudo zero vector, where 6A - 6C show a combination of two active pointers and 6D - 6E show a combination of three active hands;

7A - 7B Approximations of a reference pointer using a single pseudo-zero pointer, such as those in FIG 6A - 6C in accordance with an embodiment are shown;

8th an approximation of a reference pointer using two pseudo-null pointers, such as those shown in FIG 6A - 6C in accordance with an embodiment;

9 FIG. 12 is a graph showing maximum inverter DC link voltage utilization versus λ for a reference pointer in accordance with the embodiment of FIG 7A - 7B illustrated;

10 is a plot showing a normalized time relative to a reference vector angle for a conventional Space Vector Modulation (RZM) with the use of pseudo-null pointers, such as those shown in FIG 7A - 7B in accordance with an embodiment;

11 is a graph showing a maximum inverter DC link voltage utilization in relation to λ for a reference pointer in accordance with the embodiment of FIG 8th illustrated;

12 is a plot showing a normalized time relative to a reference pointer angle for a conventional space vector modulation (RZM) with the use of pseudo-null pointers, such as those shown in FIG 8th in accordance with an embodiment;

13A - 13B Are block diagrams illustrating a control system, such as an engine control system using a space vector modulator that uses pseudo-null pointers in approximating reference pointers in accordance with an embodiment of the disclosure;

14 a space vector hexagon showing a reference vector in polar coordinates and in Cartesian coordinates, respectively;

15 FIG. 4 is a block diagram illustrating a three-phase inverter in a control system such as that shown in FIG 13A - 13B and illustrates using a current measurement using a single shunt in accordance with one embodiment;

16A - 16B Examples of 5-segment switching sequences for the example of 7A - 7B illustrate;

17A - 17B Examples of 5-segment switching sequences for the example of 8th illustrate;

18A - 18B Examples of 6-segment switching sequences for the example of 8th illustrate;

19A - 19B Examples of 7-segment switching sequences for the example of 8th illustrate;

20 illustrates the DC link current (DC link current), which corresponds to the switching sequences which in 18A are shown;

21 is a space pointer hexagon illustrating an alternative reference pointer approximation with a single pseudo-null pointer in accordance with one embodiment;

22A - 22B Space pointer hexagons illustrating a reference pointer approximation using an improved RZM using three adjacent active pointers in accordance with an embodiment of the disclosure;

23A - 23B Space pointer hexagons illustrating a reference pointer approximation that uses an improved RZM under the condition that m = 0, such that the reference pointer is approximated only by non-adjacent active pointers in accordance with one embodiment;

24 FIG. 12 is a graph illustrating maximum inverter DC link voltage utilization in relation to m for an improved DCM in accordance with one embodiment of the disclosure; FIG.

25A - 25B are plots illustrating a normalized time versus reference angle diagrams for improved RZM, each m = 0.8 and m = 0.2, in accordance with one embodiment;

26 3 is a graph illustrating a normalized time versus a reference angle diagram for an improved RZM with m = 0 in accordance with one embodiment;

27A - 27B Are block diagrams illustrating a control system, such as a motor control system, that utilizes an improved RZM that may include non-adjacent active pointers in approximating reference pointers in accordance with an embodiment of the disclosure;

28 a space pointer hexagon showing a reference pointer in an improved RZM in polar coordinates and in Cartesian coordinates, respectively;

29 FIG. 3 is a block diagram illustrating a three-phase inverter in a control system such as that shown in FIG 27A - 27B which uses a current measurement using a single shunt in accordance with an embodiment;

30A - 30B Illustrate examples of 4-segment switching sequences for improved RZM in accordance with one embodiment;

31A - 31B Illustrate examples of 6-segment switching sequences for improved RZM in accordance with one embodiment;

32A - 32B Illustrate examples of 3-segment switching sequences for improved RZM with m = 0 in accordance with one embodiment;

33A - 33B Illustrate examples of 5-segment switching sequences for an improved RZM with m = 0 in accordance with one embodiment;

34 illustrates the DC link current, the in 31A corresponds to switching sequences shown;

35A - 35B Space-vector hexagons which illustrate specific cases of improved RZM wherein 35A illustrates the case of m ≥ 1 and 35B illustrates the case of m ≤ 0, where four active pointers are used to approximate the reference pointer, where 35A shows adjacent active pointers and 35B non-adjacent active pointers.

DETAILED DESCRIPTION

In some cases, the same reference numerals will be used in the following text for objects and functional units having the same or similar functional characteristics. Further, optional features of the various exemplary embodiments may be combined with each other or they may be interchanged.

For industrial and automotive (electric) motor control and regulation applications, ubiquitous RZM is used in sinusoidal commutation control (such as V / f or -U / f operation, FOC (Field Oriented Control), and field-oriented control) DTC (Direct Torque Control)) of a PMSM (Permanent Magnet Synchronous Motor) and an ACIM (Alternating Current Induction Motor) used to generate sine waveforms from three-phase inverters. The sinusoidal commutation motor controller with a current sense resistor using a single shunt inserted in the inverter DC link is a desirable solution in comparison because of its important advantages such as low cost, simplicity, and so on on current measurement techniques using two shunts or three shunts. However, two current samples within a single pulse width modulation (PWM) cycle are needed for proper electric motor phase current reconstruction with current measurement using a single shunt. However, with conventional RZM techniques, accurate current design is difficult in the following situations: (1): the reference voltage space vector is just over a sector boundary, therefore only a single current sample can be measured (this is often the case). And (2): If the modulation index is low and the sampling intervals are too short, then none of the samples can be sampled (this usually happens with an extremely low speed motor control).

The present disclosure proposes a new concept of a pseudo-zero pointer (alternatively, it may be called a quasi zero vector or null vector) for an RZM to address the above-mentioned problems. The new RZM, which uses pseudo-null hands, is able to provide cost effective, high quality, more reliable and unique motor control solutions or solutions for electric motor control (eg, sensorless FCC with current measurement using a single shunt). The new RZM with pseudo-null hands can also be used in a three-phase inverter control system for uninterruptible power supplies, renewable energies and so on.

The space vector diagram or space vector diagram (a regular hexagon) 120 and the reference pointer approximation 130 The existing conventional RZM are each in 3 and in 4 shown. V → ₁ to V → ₆ are active pointers or vectors. V → ₀ and V → ₇ do not produce any voltage difference in the inverter outputs and are the only two null vectors (or passive vectors / vectors) in an existing RZM. The rotation reference pointer or rotation reference vector V → _ref = | V _ref | - e ^jθ is represented by two adjacent active pointers (e.g. V → ₁ , V → ₂ in sector A) and one or both of the existing null pointers (eg only V → ₀ ) approximates. The plane of the space vector hexagon is broken down into six sectors from A to F, and the angle θ of V → _ref is transformed into the relative angle θ _rel in each sector. Using the reference pointer in sector A as an example, the following section shows the calculations of an existing or conventional RZM.

A volt-second balancing is used:

By solving equations (1) and (2) one obtains: T ₁ = Ksin (60 ° -θ _rel ) · T _S (3) T ₂ = Ksin (θ _rel ) * T _S (4)

Adding equations (3) and (4) gives: T ₁ + T ₂ = Ksin (60 ° + θ _rel ) · T _S (5)

die Amplitude von V →_ref ist und V_DC die Wechselrichter-Zwischenkreisspannung ist,
T_S – die Abtastperiode ist, z. B. T_S = 50 μsThus, the zero pointer time or zero vector time is: T ₀ = T _S - (T ₁ + T ₂ ) = [1-Ksin (60 ° + θ _rel )] * T _S (6) where: T ₀ - the time of the null pointer is applied. The / the null pointers can or can V → ₀ [000] or V → ₇ [111] or both.
T ₁ - the time of the first active pointer (eg. V → ₁ in sector A) within a single sampling period,
T ₂ - the time of the second active pointer (eg. V → ₂ in sector A) within a single sampling period,

the amplitude of V → _ref and V _{DC is} the inverter _DC link voltage,
T _S - the sampling period is, for. B. T _S = 50 μs

Since T ₀ ≥ 0 (or T ₁ + T ₂ ≤ T _S ) all the time, K ≤ 1. We have inverter DC link voltage utilization without overmodulation:

Charts of normalized time T ₁ 140 and T ₂ 150 equations (3) and (4) are in 5 shown. It is obvious that either T ₁ or T ₂ at the boundary of each sector is close to or equal to zero (eg near θ = 0 ° or 60 ° in sector A), which is the real reason for the above-mentioned problem (1 ) for a motor controller having an RZM and a current measurement using a single shunt. There have been numerous previous attempts to solve this problem, but each solution has its drawbacks.

For example, an electric motor phase current design is performed from a DC link current through a resistor using a single shunt by having T ₁ and T ₂ for a time T _min (which is the PWM dead time + the drive delay + ADW sampling time) for the ADW be limited to sample the correct current values. But limiting T ₁ and T ₂ will produce a distorted voltage vector and therefore result in high torque ripple, heavy vibration noise and noise, and even unstable engine control with high dynamic loads. A very fast ADW is needed to optimize system performance in such cases.

Another conventional approach is to modify the RZM switching pattern to a minimum measurement time window to allow two current samples to be measured. This pattern modification could produce some current ripple; moreover, due to the modification of patterns and the correction of the same modifications, more CPU resources are needed to implement the algorithm.

Another conventional approach uses asymmetric PWM pulses (with two PWM pulses offset to give enough time for current sampling while maintaining duty cycles for all PWM pulses) and only partially solves the problem. It can be seen that both T ₁ and T _{2 are} close to zero or equal to zero when K is very small or K = 0, causing the above-mentioned problem (2). The use of the asymmetric PWM pulses just mentioned above can only partially solve this problem.

The present disclosure proposes a new concept of a pseudo-null pointer for an RZM, which makes the approximation of the reference pointer with more than two active pointers relatively easy and straightforward. (In contrast, the existing RZM uses only two adjacent active pointers for the approximation of the reference pointer). The pseudo-null pointers that are in 6A - 6E show the existing two null pointers and extend the RZM theory by giving more choices of null pointers in the approximation of the reference pointer.

A base pseudo-null pointer is either a combination of two active pointers 160 . 170 or 180 , as in 6A . 6B and 6C shown, or a combination of three active pointers 190 or 200 like this in 6D and 6E is shown. The pseudo-zero time T _Z , which in 6A - 6E can be time-varying, θ-angle dependent or constant, depending on the different application requirements. These pseudo null pointers have similar effects to existing null pointers (ie, they do not produce a voltage difference in the inverter outputs). Any combination of the pseudo-null pointers will also produce the same effects. The pseudo-null pointers can be used in a similar manner as the existing null pointers (ie, one, two or a combination of null pointer (s) can be used in the approximation of a reference pointer).

The advantages of the new pseudo zero pointer concept in accordance with the present disclosure are that there are many more choices of "null pointers" in the RZM approximation. The approximation of the reference pointer with more than two active hands becomes very easy and practical. In addition, the corresponding calculations are similar to those of the existing RZM and are thus relatively simple and fast.

Two RZM examples in accordance with the present disclosure are provided below with selective use of the pseudo null pointers. Both of the new RZM examples have non-zero time intervals for two current samples using a single shunt within a PWM cycle, and thus they can easily solve the above-mentioned problem (1). Furthermore, and advantageously, the new RZM example # 2 can completely solve the above-mentioned problem (2).

In the new RZM examples, engineers can adjust the pseudo-zero time T _z to obtain different current sampling intervals based on different system requirements and hardware designs, to achieve the best performance of the motor controller with current measurement using a single shunt , In particular, because the long ADW sampling intervals can be easily obtained by selecting a longer pseudo-zero time T _z , it is also possible to use (if appropriate) a slow, common and inexpensive operational amplifier for the DC link signal amplification to further reduce system costs.

Table 1 summarizes the basic stress space pointers for the RZM with the new concept of a pseudo-zero pointer.

Table 1. RZM base voltage space pointer with the new pseudo-zero pointer concept

One element of the disclosure is the introduction of the new concept of a pseudo-zero pointer into the RZM. With the new pseudo-null pointers, there are many more choices of null pointers compared to the only two in the existing or conventional RZM, giving greater flexibility for the approximation of the reference pointer as well as for planning the RZM switching sequences. The approximation of a reference pointer with more than two active hands becomes relatively easy and convenient. In addition, the corresponding calculations are similar to those of the existing RZM, and thus are relatively simple and fast.

This section shows two examples of selective use of pseudo-null pointers in the RZM to easily solve the problems encountered with a single-shunt motor controller that the existing RZM has difficulty coping with.

in 7A) wird V →_ref eigentlich durch drei aktive Zeiger approximiert (z. B. V →₁, V →₂ und V →₄ in 7B und V →₁, V →₂ und V →₅ in 7A). Dieses neue RZM-Beispiel #1 wird unten noch ausführlicher erläutert.New RZM Example # 1: Considering sector A, as in 7A and in 7B is shown as an example, then the reference pointer V → _ref 210 . 220 is approximated by two adjacent active pointers, a single pseudo-null pointer, and one or both of the existing null pointers. By combining the time of the same active pointers (eg:

in 7A ) becomes V → _ref actually approximated by three active hands (eg V → ₁ , V → ₂ and V → ₄ in 7B and V → ₁ , V → ₂ and V → ₅ in 7A ). This new RZM example # 1 will be explained in more detail below.

wird V →_ref eigentlich durch vier aktive Zeiger approximiert. Das neue RZM-Beispiel #2 wird ebenfalls unten noch ausführlicher erläutert. New RZM Example # 2: Considering sector A, as in 8th is shown as an example, then the reference pointer V → _ref 230 is approximated by two adjacent active pointers, two pseudo-null pointers and one or both of the existing null pointers. By combining the time of the same active pointer

becomes V → _ref actually approximated by four active hands. The new RZM example # 2 will also be explained in more detail below.

Anm. 1: Die 3. und 4. aktiven Zeiger (falls vorhanden) kommen von den Pseudo-Nullzeigern, die verwendet werden.
Anm. 2: Θ_Tr ist ein Übergangswinkel für neue Sektoren (z. B.: A1, A2, B1, B2 und so weiter), und 0° < Θ_Tr < 60°.
Anm. 3: Pseudo-Nullzeigerzeit bzw. Pseudo-Nullvektorzeit T_z = λT_S ≥ T_min wobei T_min die PWM-Totzeit + die Treiberverzögerung + die ADW-Abtastzeit ist.Table 2 compares the existing RZM and the new RZM examples with pseudo null pointers and summarizes them. Table 2. Comparison of existing RZM and new RZM examples using pseudo-null pointers

Note 1: The 3rd and 4th active pointers (if any) come from the pseudo-null pointers that are used.
Note 2: Θ _Tr is a transition angle for new sectors (eg: A1, A2, B1, B2 and so on), and 0 ° <Θ _Tr <60 °.
Note 3:. Pseudo-zero vector time or pseudo-zero vector time T _z = λT _S ≥ T _min where T _min is the PWM dead time + the driver delay + the ADC sampling time.

New RZM example # 1 - RZM with a single pseudo-null pointer

As in 7A and 7B 2, the reference pointer in each existing sector (ie, A, B, C, D, E, and F) may be approximated by two different sets of active pointers. A transition angle Θ _Tr (0 ° <Θ _Tr <60 °) is introduced to obtain new sectors A1, A2, B1, B2, and so on, as shown in Table 2. That is why it is located in 7A the reference pointer 210 in the sector A1 and is the reference pointer 220 in 7B in sector A2. At the transition angles, the reference pointer approximation transitions from one set of active pointers to another set of active pointers for the new space vector modulations. Θ _Tr can be different in different existing sectors. For the sake of simplicity we can use the same value, e.g. Eg Θ _Tr = 30 °, for all sectors.

Calculations when 0 ° ≤ θ _rel <Θ _Tr

When looking at the reference pointer 210 in sector A, as in 7A is shown as an example, the following shows the calculations when 0 ° ≦ θ _rel <Θ _Tr . A volt-second compensation is used:

ausgewählt, wobei: λ – eine Konstante ist und

(0 ≤ λ < 1); wenn z. B. T_S = 50 μs und T_min = 2 μs, dann können wir λ = 1 / 25 auswählen.T _z should be chosen to be greater than or equal to T _min (which is the PWM dead time + the drive delay + ADW sampling time). For simplicity's sake

wherein: λ - is a constant and

(0≤λ <1); if z. For example, if T _S = 50 μs and T _min = 2 μs, then we can use λ = 1/25 choose.

By solving equations (8) to (10), one obtains T ₁ = Ksin (60 ° -θ _rel ) · T _S (11) T ₂ = T '/ 2 + T _z = [Ksin (θ _rel ) + λ] * T _S (12) T ₁ + T ₂ + T ₃ = [Ksin (60 ° + θ _rel ) + 2λ] · T _S (13)

die Amplitude von V →_ref ist und V_DC die Wechselrichter-Zwischenkreisspannung ist
T_S – die Abtastperiode istThus, the zero pointer time T ₀ = T _S - (T ₁ + T ₂ + T ₃ ) = [(1 - 2λ) - Ksin (60 ° + θ _rel )] · T _S (14) where: T ₀ - the time of the existing null pointer (s) is applied. The / the null pointers can / can

V → ₀ [000] or V → ₇ [111] or both.

T _z - the time of the pseudo-zero pointer is applied
T ₁ - the time of the first active pointer is applied within a single sampling period
T ₂ - the time of the second active pointer is applied within a single sampling period
T ₃ - the time of the third active pointer, which is a part of the pseudo-zero pointer used, applied within a single sampling period

the amplitude of V → _ref and V _{DC is} the inverter _DC bus voltage
T _S - the sampling period is

ist.

Berechnungen, wenn Θ_Tr ≤ θ_rel < 60°Since T ₀ ≥ 0 all the time, K ≤ 1 - 2λ results from the equation (14), so that the inverter DC link voltage utilization without overmodulation

is.

Calculations when Θ _Tr ≤ θ _rel <60 °

If the reference pointer 220 in sector A, as in 7B is shown as an example, the following shows the calculations when Θ _Tr ≦ θ _rel <60 °. A volt-second compensation is used:

Similarly, T _z = λT _{S is} selected, ie

By solving equations (16) and (17) one obtains T ₁ = T '/ 1 + T _z = [Ksin (60 ° -θ _rel ) + λ] * T _S (19) T ₂ = Ksin (θ _rel ) · T _S (20) T ₁ + T ₂ + T ₃ = [Ksin (60 ° + θ _rel ) + 2λ] · T _S (21)

Thus, the zero pointer time T ₀ = T _S - (T ₁ + T ₂ + T ₃ ) = [(1 - 2λ) - Ksin (60 ° + θ _rel )] · T _S (22)

ist.Similarly, it can be seen that the inverter DC link voltage utilization without overmodulation is the same as equation (15). Thus, the new RZM example # 1 has a single maximum inverter DC link voltage utilization without overmodulation, the

is.

A diagram of equation (23) is in 9 shown the maximum utilization of the inverter DC bus voltage 240 in relation to λ for Example 1. If λ = 0, then the new RZM becomes the existing RZM and

Charts of normalized time T ₁ 250 , T ₂ 260 and T ₃ 270 for the new RZM example # 1 are in 10 where Θ _Tr = 30 ° for all sectors. It can be seen that T ₁ , T ₂ and T _{3 are} all nonzero (except when K is very small or K = 0). Thus, the new RZM example # 1 can easily solve the aforementioned problem (1). The use of a current measurement using a single shunt is always a good choice for measuring the inverter DC link current during two time intervals T ₁ and T ₂ .

New RZM example # 2 - RZM with two pseudo-null pointers

If the reference pointer 230 in sector A, as in 8th is shown as an example, the following shows the calculations. A volt-second compensation is used:

Similarly, T _z = λT _{S is} selected, ie

By solving equations (24) to (26) one obtains T ₁ = T '/ 1 + T _z = [Ksin (60 ° -θ _rel ) + λ] * T _S (27) T ₂ = T '/ 2 + T _z = [Ksin (θ _rel ) + λ] * T _S (28) T ₁ + T ₂ + T ₃ + T ₄ = [Ksin (60 ° + θ _rel ) + 4λ] · T _S (29)

die Amplitude von V →_ref ist und V_DC die Wechselrichter-Zwischenkreisspannung ist
T_S – die Abtastperiode istThus, the zero pointer time T ₀ = T _S - [λ ₁ + T ₂ + T ₃ + T ₄ ) = [(1 - 4λ) - Ksin (60 ° + θ _rel )] · T _S (30) where: T ₀ - the time of the existing null pointer (s) is applied. The / the null pointers can / can

V → ₀ [000] or V → ₇ [111] or both.

T _z - the time the pseudo-null pointer is applied
T ₁ - the time of the first active pointer is applied within a single sampling period T ₂ - the time of the second active pointer is applied within a single sampling period
T ₃ , T ₄ - the times of the 3rd and 4th active pointers, which are part of the pseudo-null pointers used, are applied within a single sampling period

the amplitude of V → _ref and V _{DC is} the inverter _DC bus voltage
T _S - the sampling period is

ist.Since T ₀ ≥ 0 all the time, K ≤ 1 - 4λ results from the equation (30), so that the inverter DC link voltage utilization without overmodulation

is.

Thus, the maximum inverter DC link voltage utilization is without overmodulation

A diagram of equation (32) is in 11 at 280 showing the maximum inverter DC link voltage utilization in relation to λ for the new example 2. If λ = 0, then the new RZM becomes the existing RZM and

Charts of normalized time T ₁ 290 , T ₂ 300 , T ₃ and T ₄ 310 for the new RZM example # 2 are in 12 shown. It can be seen that both T ₁ and T ₂ are longer than T _min under all conditions (as long as λT _S ≥ T _min ), even if K = 0 (ie: | V _ref | = 0). Thus, the new RZM example # 2 not only can solve the problem (1), but also completely solve the above-mentioned problem (2). The use of a current measurement using a single shunt is always a good choice for measuring the inverter DC link current during two time intervals T ₁ and T ₂ .

The use of the new RZM in the engine control: The connections of the RZM in a motor control or electric motor control are in 13A and 13B shown. The input to the new RZM may be the polar coordinates (ie, the radial coordinate | V _ref | and the angle coordinate θ) of the reference pointer V → _ref be like this in 13A shown what has been discussed above. The inputs to the RZM can also be the Cartesian coordinates (V _α , V _β ) of the reference pointer V → _ref be in the Cartesian α-β coordinate system, as in 13B is shown. The coordinate systems in the RZM space pointer hex are in 14 shown. The transformation of polar coordinates into Cartesian coordinates is: Vα = | V _ref | cos (θ) (33) V _β = | V _ref | sin (θ) (34)

With equations (33) and (34), all of the formulas listed in Table 2 can be transmitted to be formatted with inputs of V _α and V _β . For example, the time calculations of the new RZM example # 1 in sector A1 will be added

13A shows a control system 320 , For example, an engine control system or electric motor control system. The tax system 320 has a space vector modulator (RZM) or space vector modulator 330 in accordance with the present disclosure using pseudo-null pointers. The RZM 330 receives a reference signal or samples and synthesizes one or more reference pointers based thereon, wherein at least one of the reference pointers uses one or more pseudo-null pointers as described herein. Based on the synthesized reference pointer, the RZM modulator outputs 330 clock signals 340 to a PWM unit 350 off that the clock signals 340 receives and PWM control signals 360 generated. The PWM control signals 360 become a three-phase inverter circuit 370 supplied, the output signals u, v and w generated to a load 380 , such as a three-phase motor to drive. 13B is, as highlighted above, similar to 13A however, illustrates receiving an input reference signal in Cartesian coordinates rather than polar coordinates but generally operates in the same manner as described above.

An inverter with a current measurement using a single shunt: The connection of a three-phase two-phase voltage source inverter and an electric motor is in 15 at 400 shown. The six switching devices of the inverter 400 , which may be a MOSFET, IGBT or similar parts, are controlled by microcontroller PWM signals. As illustrated, the inverter includes a first pair of switches connected in series 410 , a second pair of switches in series 420 and a third pair of switches connected in series 430 on. Each in series switched couples 410 . 420 and 430 is connected to a node which forms an output u, v, w associated with a respective phase of the load 440 connected is. Each of the pairs connected in series 410 . 420 . 430 is also together at one connection 450 coupled with a first terminal of a shunt resistor 460 is coupled, which has a second terminal which is connected to a reference potential 470 connected is. An amplifier 480 has input terminals, each with the first and second terminals of the shunt resistor 460 coupled, wherein an output of the amplifier 480 reflects a current through the shunt resistor 460 flows.

The motor windings may be wired in a star configuration (as shown) or in a triangular configuration. The RZM is used to control the PWM to produce three-phase sinusoidal waveforms for the motor windings. The shunt resistor R _shunt 460 is inserted in the inverter DC link (inverter DC link or inverter DC link) to measure the DC link current. If necessary, the amplifier 480 used to amplify the resistance voltage drop, which is proportional to the DC link current. It should be noted that a Hall sensor, a current transformer or other current sensors can replace the shunt resistor to measure the DC link current.

• 1) Eine Kostenreduktion als Folge davon, dass nur ein einziger Stromsensor, (gegebenenfalls) ein einziger Verstärker und ein einziger ADW-Kanal verwendet werden. Im Gegensatz dazu benötigen die zwei Shunts verwendende Strommessung und die drei Shunts verwendende Strommessung mehrere Stromsensoren, (gegebenenfalls) mehrere Verstärker und mehrere ADW-Kanäle.
• 2) Die Verstärkungsfaktoren und Offsets bzw. Versätze (die durch die Bauteiltoleranz, schwankende Temperaturen, Alterung und so weiter bedingt sein können) müssen nicht kalibriert werden, da die gleiche Strommessschaltung und der gleiche ADW-Kanal für alle Strommessungen der Motorphasen verwendet werden.
• 3) Schlichtere und einfachere elektronische Schaltpläne und ein schlichteres und einfacheres Leiterplattendesign.

Compared to current measurements using two or three shunts, the current measurement using a single shunt has the following important advantages:

• 1) A cost reduction as a result of using only a single current sensor, (if applicable) a single amplifier and a single ADW channel. In contrast, the current measurement using two shunts and the current measurement using three shunts require multiple current sensors, (if necessary) multiple amplifiers, and multiple ADW channels.
• 2) The gain factors and offsets (which may be due to component tolerance, fluctuating temperatures, aging and so on) need not be calibrated because the same current sense circuit and the same ADW channel are used for all current measurements of the motor phases.
• 3) Simpler and simpler electronic schematics and a simpler and simpler circuit board design.

Design of the Switching Sequence: There are many switching sequence combinations for the new space vector modulations, ranging from different order of active pointers / zeros, splitting of the duty cycles of the pointers and the selection of existing null pointers (ie the selection of the null pointer V → ₀ [000] or V → ₇ [111] or both). It is difficult to list all switching sequences here. This section provides only a few examples of the switching sequences that can be easily implemented using Infineon microcontrollers or other types of microcontrollers. 16A and 16B show examples of 5-segment switching sequences 500 . 510 for the new RZM example # 1. 17A and 17B show examples of 5-segment switching sequences 520 . 530 for the new RZM example # 2, 18A and 18B show examples of 6-segment switching sequences 540 . 550 , and 19A and 19B show examples of 7-segment switching sequences 560 . 570 ,

Anm. 1: I_U, I_V und I_W sind jeweils die Ströme der Motorphasen U, V und W.Current Reconstruction: Two / three motor phase currents can be reconstructed using current measurement using a single shunt. In each PWM cycle, the inverter DC link current is measured at least twice during two different active vector segments to obtain two motor phase currents. The ADW samples are normally triggered near the middle of the active pointer segments to prevent current transients. Table 3 shows the inverter DC link current of various PWM segments. As an example shows 20 the DC link current _DClink 580 , the switching sequences 540 corresponds to that previously in 18A have been shown. Two phase currents can be measured on two PWM segments of active hands that are greater than or equal to T _min , e.g. B ..: I _DClink = -I _W during T ₂ and I _DClink = I _U during T ₁ in 20 because T2 ≥ T _min and T ₁ ≥ T _min . With two phase currents, the third motor phase current can be easily calculated because I _U + I _V + I _W = 0. Table 3. Inverter DC link current of various PWM elements

Note 1: I _U , I _V and I _W are the currents of the motor phases U, V and W.

If you have a reference pointer or reference vector V → _ref in the sector A takes as an example, then shows 21 an alternative approximation of the reference pointer 590 with a single pseudo-null pointer in accordance with another embodiment of the disclosure. Clearly, the calculations for T ₁ and T _{2 are} the same as those for the existing RZM, and the reference pointer 590 is actually approximated by four active pointers or vectors. This is another example of selective use of a pseudo null pointer to easily solve the above-mentioned problems.

As pointed out above, the RZM is regularly used for industrial and vehicle engine control applications, and is used in sine commutation control (such as V / f operation, FOC (Field Oriented Control); field-oriented control) and a Direct Torque Control (DTC) of a permanent magnet synchronous motor (PMSM) and alternating current induction motor (ACIM) are used to generate sinusoidal waveforms from three-phase inverters. The sinusoidal commutation motor controller with a current sense resistor employing a single shunt inserted in the inverter link is a desirable solution because of important advantages such as low cost, simplicity, and so on, as compared to current measuring techniques involving two shunts or three Use shunts. However, two current samples within a single pulse width modulation (PWM) cycle are needed for proper electric motor phase current reconstruction with current measurement using a single shunt. However, with the existing RZM, the exact current design is difficult when the reference voltage space vector is just beyond a sector boundary, since in this situation only a single current sample can be measured. This is a problem for most of the normal speed motor control with an RZM and current measurement using a single shunt.

The improved RZM proposed in accordance with an embodiment of the disclosure can solve the above-mentioned problem. With the new RZM technology, it is able to offer cost effective, high quality, more reliable and unique electric motor control solutions (eg sensorless FOC with current measurement using a single shunt) to customers. The improved RZM can also be used in a three-phase inverter control system for uninterruptible power supplies, renewable energies and so on.

In order to solve the problems highlighted above and associated with the conventional RZM, the present disclosure results in accordance with the present invention Embodiment innovative approximations of the reference pointer with other active pointers instead of the two adjacent active pointers in the existing RZM. New approximations of the improved RZM are in 22A - 22B shown. One part (ie mV → _ref with 0 ≤ m ≤ 1 ) of the reference pointer 600 . 610 is approximated by two adjacent active pointers, just like the existing RZM, and the remainder (1 - m) V → _ref is approximated by two non-adjacent and 120 ° separated active hands. The improved RZM will be explained below. A special case of the improved RZM is when m = 1, because then the entire reference vector is approximated by two adjacent active pointers in each sector, and the improved RZM becomes the existing RZM, as in FIG 4 is shown. Another special case of the improved RZM is when m = 0, because then the entire reference pointer is approximated 1% by two non-contiguous and 120 ° separated active pointers in each sector. Thus the approximations become 600 . 610 in 22A and 22b each to the approximations 620 . 630 in 23A and 23B , The improved RZM will become another new RZM (which will be called "improved RZM with m = 0" in this disclosure), which will be explained in more detail below.

Anm. 1: Θ_Tr ist ein Übergangswinkel für neue Sektoren (d. h., AB, BC, CD, DE, EF und FA), und 0° < Θ_Tr < 60°.
Anm. 2:

wobei k eine ganze Zahl ist. Man wähle k so aus, dass 60° ≤ θ₁ ≤ 120° für 0 ≤ m ≤ 1.
Anm. 3:

wobei k eine ganze Zahl ist. Man wähle k so aus, dass 0° ≤ θ₂ ≤ 60° für 0 ≤ m ≤ 1.Table 4 compares and summarizes the existing space vector modulation and proposed new space vector modulations. Table 4. Comparison of existing RZM and proposed new space vector modulations

Note 1: Θ _Tr is a transition angle for new sectors (ie, AB, BC, CD, DE, EF and FA), and 0 ° <Θ _Tr <60 °.
Note 2:

where k is an integer. Choose k such that 60 ° ≤ θ ₁ ≤ 120 ° for 0 ≤ m ≤ 1.
Note 3:

where k is an integer. Let k be such that 0 ° ≦ θ ₂ ≦ 60 ° for 0 ≦ m ≦ 1.

As previously highlighted, the improved RZM has advantages over conventional RZM techniques. For example, the improved RZM is well suited for three-phase motor control with current measurement using a single shunt, so that it can fully exploit the advantages of a single-shunt current sensing technique, as will be explained in greater detail below. A further benefit of the improved RZM is that customers can adjust the factor m based on different system requirements and hardware designs to obtain different current sampling intervals so as to achieve the best performance of the motor controller with current measurement using a single shunt. Since three adjacent active pointers are used for approximation in the enhanced RZM if necessary, it is possible to measure three ADC samples of the inverter DC link current in a single PWM cycle to directly obtain three motor phase currents (discussed in more detail below) will be). This will be useful for those applications where the sum of three motor winding currents is not zero, but still using a current measurement using a single shunt. It is also possible to measure only two ADW samples of the motor phase current of interest (eg, I _U and I _V ) directly within any PWM cycle.

The improved RZM with m = 0 is also well suited for motor control with current measurement using a single shunt. It has long current sampling time intervals in each PWM cycle, so it is possible to use a slow, common and inexpensive operational amplifier for current signal amplification to further reduce system costs. The improved RZM with m = 0 has lower DC link bus voltage utilization. For applications with a high DC link voltage, eg. For example, for a low cost PMSM ceiling fan drive with a very high DC link voltage (up to 400 V DC due to the use of power factor correction) this is not a problem.

Improved RZM: If the reference pointer in sector A, as in 22A and 22B As an example, the reference pointer in each existing sector (ie, A, B, C, D, E or F) may be approximated by two different sets of active pointers. A transition angle Θ _Tr (0 ° <Θ _Tr <60 °) is introduced to obtain new combined sectors AB, BC, CD, DE, EF and FA, such as this is shown in Table 1. At the transition angles, the reference pointer approximation changes from one set of active pointers to another set of active pointers for the new space vector modulations. Θ _Tr can be different in different existing sectors. For the sake of simplicity we can use the same value, e.g. Eg Θ _Tr = 30 °, for all sectors.

Calculations, if Θ _Tr ≤ θ _rel <60 °: If the reference pointer in sector A, as shown in 22A is shown as an example, the following shows the calculations when Θ _Tr ≦ θ _rel <60 °. A volt-second compensation is used:

Add both sides of equations (39) and (40),

die Amplitude von V →_ref ist und V_DC die Wechselrichter-Zwischenkreisspannung ist
T_S – die Abtastperiode istBy solving equations (39) and (40) one obtains T '/ 1 = mKsin (60 ° -θ _rel ) * T _S (43) T _↓ 1 '= (1-m) Ksin (120 ° -θ _rel ) * T _S (44) T ₂ = mKsin (θ _rel ) * T _S (45) T ₃ = (1-m) Ksin (θ _rel ) * T _S (46) where: T ₀ - the time of the null pointer is applied. The / the null pointers can or can V → ₀ [000] or V → ₇ [111] or both.
T ₁ - the time of the first active pointer is applied within a single sampling period
T ₂ - the time of the second active pointer is applied within a single sampling period
T ₃ - the time of the third active pointer is applied within a single sampling period

the amplitude of V → _ref and V _{DC is} the inverter _DC bus voltage
T _S - the sampling period is

wobei Θ₁ ein Winkel ist, der nur von dem Faktor m abhängt, und

wobei k eine ganze Zahl ist und k = 0, ±1, ±2, ±3, oder ···. Man wähle k so aus, dass 60° ≤ Θ₁ ≤ 120° für 0 ≤ m 1, z. B.: Θ₁ = 120°, wenn m = 0 ist.If you add both sides of equations (43) and (44), then you can see that

where Θ _{1 is} an angle that depends only on the factor m, and

where k is an integer and k = 0, ± 1, ± 2, ± 3, or ···. Choose k such that 60 ° ≤ Θ ₁ ≤ 120 ° for 0 ≤ m 1, z. B: Θ ₁ = 120 ° when m = 0.

z. B.: Θ₃ 30°, wenn m = 0 ist. Die Nullzeigerzeit ist T_↓0 = T_↓0' + T_↓0'' = T_↓S – (T_↓1 + T_↓2 + T_↓3) = [1 – √3 – m(3 – m)·Ksin(Θ₂ + θ_rel)·T_S (50) By adding both sides of equations (45), (46) and (47) one obtains T ₁ + T ₂ + T ₃ = √ 3 - m (3 - m) · Ksin (Θ ₂ + θ _rel ) · T _S (49), where: Θ ₂ - is an angle that depends only on m, and

z. B: Θ ₃ 30 ° when m = 0. The zero pointer time is T _↓ 0 = T _↓ 0 '+ T _↓ 0 "= T _↓ S - (T _↓ 1 + T _↓ 2 + T _↓ 3) = [1 - √ 3 - m (3 - m) · Ksin (Θ ₂ + θ _rel ) · T _S (50)

ist.Since T ₀ ≥ 0 (or T ₁ + T ₂ + T ₃ ≤ T _S ) is the same all the time √ 3 - m (3 - m) · K ≤ 1 , so that the inverter DC link voltage utilization without overmodulation

is.

Calculations, if 60 ° ≤ θ _rel <60 ° + Θ _Tr : If one uses the reference pointer in sector A, as shown in 22B is shown as an example, the following shows the slightly different calculations when 60 ° ≦ θ _rel <60 ° + Θ _Tr . In a similar way we have

wobei: Θ₂ – ein Winkel ist, der nur von dem Faktor m abhängt, und

k ist eine ganze Zahl, und k = 0, ±1, ±2, ±3, oder ···. Man wähle k so aus, dass 0° ≤ Θ₃ ≤ 60° für 0 ≤ m ≤ 1, z. B.: Θ₃ = 0°, wenn m = 0 ist. Die Nullzeigerzeit ist T₀ = T_S – T₁ – T₂ – T_a = [1 – √3 – m(3 – m)·Ksin(Θ₄ + θ_rel)]·T_S (57) wobei: Θ₄ – ein Winkel ist, der nur von m abhängig ist, und

z. B.: Θ₄ = 30°, wenn m = 0 ist. In ähnlicher Weise lässt sich feststellen, dass die Wechselrichter-Zwischenkreisspannungs-Ausnutzung ohne Übermodulation die gleiche wie Gleichung (51) ist. Somit hat die verbesserte RZM eine maximale Wechselrichter-Zwischenkreisspannungs-Ausnutzung ohne Übermodulation, die Folgende ist:

By solving equations (52) and (53) one obtains T ₁ = (1-m) Ksin (120 ° -θ _rel ) * T _S (54) T ₂ = mKsin (120 ° -θ _rel ) · T _S (55)

where: Θ ₂ - is an angle that depends only on the factor m, and

k is an integer, and k = 0, ± 1, ± 2, ± 3, or ···. Let k be chosen such that 0 ° ≤ Θ ₃ ≤ 60 ° for 0 ≤ m ≤ 1, z. B: Θ ₃ = 0 ° when m = 0. The zero pointer time is T ₀ = T _S - T ₁ - T ₂ - T _a = [1 - √ 3 - m (3 - m) · Ksin (Θ ₄ + θ _rel )] · T _S (57) where: Θ ₄ - is an angle dependent only on m, and

z. B: Θ ₄ = 30 ° when m = 0. Similarly, it can be seen that the inverter DC link voltage utilization without overmodulation is the same as equation (51). Thus, the improved RZM has maximum inverter DC link voltage utilization without overmodulation, which is:

was in der früheren Gleichung (7) dargelegt worden ist; wenn m = 0 ist, dann wird dies zu dem speziellen Fall der verbesserten RZM mit m = 0 und 3 (was unten noch ausführlicher besprochen werden soll).A diagram of equation (58) is in 24 at 640 shown. If m = 1, then the improved RZM becomes the existing RZM and

what has been stated in the earlier equation (7); if m = 0 then this becomes the special case of the improved RZM with m = 0 and 3 (to be discussed in more detail below).

ist.Charts of normalized time T ₁ 650 , T ₂ 660 and T ₃ 670 for the improved RZM are in 25A and 25B where Θ _Tr = 30 ° for all sectors, with m = 0.8 and 0.2 respectively as examples. It is obvious that T ₁ , T ₂ and T _{3 are} all nonzero. Using a current measurement using a single shunt is always a good choice for measuring the inverter DC link current during two time intervals that are longer than the third time (eg, T ₂ and T ₃ when 0 ° ≤ θ <30) °, as in 25A is shown, T ₁ and T ₃ for all θ, as in 25B is shown). At Θ _Tr = 30 °, it can be seen that the minimum current sampling time, which is limited by T ₁ , T ₂ or T ₃ ,

is.

A user may select the value of m on the basis of the required maximum DC link voltage utilization and the minimum time that is required for the current scan (ie, it can ensure that Tminimum ≥ T _min, T _min, the PWM dead time + the Driver delay + the ADW sampling time is).

Improved RZM with m = 0: Similarly, the calculations of the improved RZM with m = 0 are shown below: T ₁ = Ksin (120 ° -θ _rel ) · T _S (61) T ₃ = Ksin (θ _rel ) · T _S (62) T ₁ + T ₃ = √3 · Ksin (30 ° + θ _rel ) · T _S (63) T ₀ = T _S - (T ₁ + T ₃ ) = [1 - √3 · Ksin (30 ° + θ _rel )] · T _S (64)

It should be noted that equations (61) to (64) apply to both 23A as well as for 23B function. The inverter DC bus voltage utilization without overmodulation becomes too

A diagram of the normalized time T ₁ 680 and T ₃ 690 with a transition angle Θ _Tr = 30 ° for all sectors is in 26 shown. It is obvious that both T ₁ and T _{3 are} nonzero. With Θ _Tr = 30 ° is the shortest time for current ADW sampling T '/ minimum = 1/2 * KT _S (66)

An advantageous element of the disclosure in accordance with the present embodiment is that instead of two adjacent active pointers used to synthesize a reference pointer as in the existing RZM, the enhanced RZM has three adjacent active pointers or two non-adjacent active pointers for the approximation of the reference pointer V → _ref used. In the new improved space vector modulations, nonzero intervals can be achieved for multiple current samples within a single PWM cycle, and reconstruction of the phase currents with current measurement using a single shunt can be easily performed without introducing distortion into the resulting motor phase current.

Use of the new RZM in the engine control: The connections of the RZM in an engine control system or electric motor control system 700 are in 27A and in 27B shown. 27A shows a section of a control system 700 , for example, an engine control system. The tax system 700 has a space pointer modulator (RZM) 710 in accordance with the present disclosure using the improved RZM that uses three adjacent active pointers or two non-adjacent active pointers to synthesize a reference pointer. The improved RZM 710 receives a reference signal or samples and synthesizes one or more reference pointers based thereon, wherein at least one of the reference pointers uses either three adjacent active pointers or two non-adjacent active pointers as described herein. Based on the synthesized reference pointer (s), the RZM modulator is output 710 clock signals 720 to a PWM unit 730 off that the clock signals 720 receives and PWM control signals 740 generated. The PWM control signals 740 become a three-phase inverter circuit 750 supplied, the output signals u, v and w generated to a load 760 , such as a three-phase motor to drive.

The input to the new enhanced RZM may be the polar coordinates (ie, radial coordinate | V _ref | and angular coordinate θ) of the reference pointer V → _ref be like in 27A shown what has already been discussed above. The inputs to the RZM can also be the Cartesian coordinates (V _α , V _β ) of the reference pointer V → _ref in the Cartesian α-β coordinate system, as in 27B is shown.

The coordinate systems in the RZM space pointer hex are in 28 at 770 shown. The transformation from the polar coordinates to the Cartesian coordinates is: V _α = | V _ref | cos (θ) (67) V _β = | V _ref | sin (θ) (68)

With equations (67) and (68), all of the formulas listed in Table 4 can be transmitted to be formatted with inputs of V _α and V _β . Thus, for example, the time calculations of the improved RZM with m = 0 in the sector AB to

An inverter with a current measurement using a single shunt: The connection 780 a three-phase two-phase voltage source inverter 790 and a motor or electric motor 800 are in 29 shown. As illustrated, the inverter has 790 a first pair of switches connected in series 810 , a second pair of switches in series 820 and a third pair of switches connected in series 830 on. Each of the pairs connected in series 810 . 820 and 830 is connected to a node which forms an output u, v, w, which is connected to a respective phase of the load 800 connected. Each of the pairs connected in series 810 . 820 . 830 is also together at a connection 850 coupled with a first terminal of a shunt resistor 860 is coupled, which has a second terminal which is connected to a reference potential 870 connected is. An amplifier 880 has input terminals, each with the first and second terminals of the shunt resistor 860 coupled, wherein an output of the amplifier 880 reflects a current through the shunt resistor 860 flows.

The inverter's six switching devices, which may be a MOSFET, IGBT or similar, are controlled by microcontroller PWM signals. The motor windings may be star-shaped (as shown) or triangular-shaped. The improved RZM discussed above, which uses either three adjacent active pointers or two non-adjacent active pointers to synthesize the reference pointer, is used to control the PWM to produce three-phase sinusoidal waveforms for the motor windings. The shunt resistor R _shun t 860 is inserted in the inverter DC link to measure the DC link current. If necessary, the amplifier 880 used to amplify the resistance voltage drop, which is proportional to the DC link current. It should be noted that a Hall sensor, a current transformer or other current sensors can replace the shunt resistor for the measurement of the DC link current.

There are many switching sequences for the new improved space vector modulations, ranging from different active pointer / null pointer ordering, splitting the duty cycles of the pointers, and selecting existing null pointers (ie, zero pointer selection V → ₀ [000] or V → _ref [111] or both). It is difficult to list all switching sequences here. This section gives only a few examples of the switching sequences that can be easily implemented using Infineon microcontrollers or other microcontrollers.

Design of the switching sequence for the improved RZM: 30A and 30B show examples of 4-segment switching sequences for the improved RZM 890 . 900 , and 31A and 31B show examples of 6-segment switching sequences 910 . 920 , 32A and 32B show examples of 3-segment switching sequences for the improved RZM with m = 0 930 . 940 , and 33A and 33B show examples of 5-segment switching sequences with m = 0 950 . 960 ,

Current Reconstruction: Two / three motor phase currents can be reconstructed using current measurement using a single shunt. In each PWM cycle, one inverter DC link current is measured at least twice during two different active pointer segments to get two motor phase currents. The ADW samples are normally triggered near the center of the active pointer segments to avoid current transients.

Table 5 shows the inverter DC link current of different PWM segments. As an example shows 34 the _{DC link current} I _DClink 970 , the switching sequences 910 corresponds to that previously in 31A have been shown for the improved RZM. Two phase currents can be measured on two PWM segments of active hands greater than or equal to T _min , e.g. B: I _DClink = -I _W during T _2/2 and I _DClink = I _V during T ₃ in 34 , if T _2/2 ≥ T _min and T ₃ ≥ T _min . With two phase currents, the third motor phase current can be easily calculated because I _U + I _V + I _W = 0.

Anm. 1: I_U, I_V und I_W sind jeweils die Ströme der Motorphasen U, V und W.Out 34 It can be seen that for the enhanced RZM it is possible to measure three inverter DC link current ADW samples within a single PWM cycle to directly obtain three motor phase currents if all three active vector segments are longer than T _min . This will be useful for the I _U + I _V + I _W ≠ 0 applications. It is also possible to measure only two ADW samples of the motor phase current of interest (eg: only I _U and I _V ) directly within a PWM cycle. Table 5. Inverter DC link current from various PWM elements

Note 1: I _U , I _V and I _W are the currents of the motor phases U, V and W.

In order to solve the above-mentioned problem, it is possible to use the reference pointer V → _ref to approximate in alternative ways, as in 35A and 35B is shown, where n ≥ 0. If the reference pointer in sector A, as in 35A at 980 shown is used as examples, then becomes (1 + n) V → _ref is approximated by two adjacent active pointers just as in the existing RZM, and an opposite part is approximated by two non-adjacent and 120 ° separated active pointers; in 35B at 990 becomes (1 + n) V → _ref is approximated by two non-adjacent and 120 ° separated active hands, and an opposite part V → _ref is approximated by two adjacent active pointers. The alternative solutions in 35A and in 35B 4 use active pointers to approximate the reference pointer, while the solutions previously mentioned use three or two. The approximation in 35A can be considered as a special case of the improved RZM with m ≥ 1, and the approximation given in 35B can be considered as a special case of the improved RZM with m ≤ 0.

The exemplary embodiments described above represent only an illustration of the principles of the present invention. It is obvious that modifications and variations of the arrangements and details described herein may be of interest to other specialists. The aim, therefore, is that the invention should be limited only by the scope of the following claims and not by the specific details presented herein on the basis of the description and explanation of the exemplary embodiments.

Claims (10)

A method of performing space vector modulation (RZM) for pulse width modulation (PWM) control to generate AC waveforms comprising the steps of: Generating a reference signal and sampling the reference signal at a sampling frequency to produce a plurality of reference samples; and performing a reference pointer approximation to synthesize a reference pointer associated with at least one of the reference samples, wherein the reference pointer approximation uses active pointers, one or more null pointers, and one or more dummy null pointers in the formation thereof. The method of claim 1, wherein a pseudo-pointer comprises a combination of two active pointers having an angular difference between them of 180 °. The method of claim 2, wherein the two active pointers that combine to form the pseudo pointer have a scalar amplitude that is the same. The method of claim 1, wherein a pseudo pointer comprises a combination of three active pointers having an angular difference between them of 120 °. The method of claim 4, wherein the three active pointers that combine to form the pseudo pointer have a scalar amplitude that is the same. The method of claim 1, wherein the active pointers in the reference pointer approximation have adjacent active pointers. The method of claim 6, wherein a portion of the reference pointer is approximated by two adjacent active pointers and a remaining portion of the reference pointer is approximated by two non-adjacent active pointers. Control system with: a space vector modulator configured to receive a plurality of reference signal samples and to perform a reference pointer approximation to synthesize a reference pointer associated with at least one of the reference signal samples, the reference pointer approximation including active pointers, one or more null pointers, and one or more pseudo-pointers; Uses null pointer in the formation thereof, and wherein the space vector modulator outputs clock signals based on the reference pointer approximation; a pulse width modulation unit configured to receive the clock signals from the space vector modulator and to output pulse width modulation control signals based thereon; and a three-phase inverter configured to receive the pulse width modulation control signals and generate AC waveforms based thereon. The control system of claim 8, wherein a pseudo-pointer comprises a combination of two active pointers having an angular difference between them of 180 °. The control system of claim 9, wherein the two active pointers, which in combination form the pseudo pointer, have a scalar amplitude that is the same.

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