阅读说明：本技术 用于机动车的旋转场电机的电流调节的调节设备、用于电流调节的方法、驱动单元以及机动车 (Control device for current control of a rotating field motor of a motor vehicle, method for current control, drive unit and motor vehicle ) 是由 D·格罗泽 于 2019-03-12 设计创作，主要内容包括：本发明涉及一种用于机动车的旋转场电机(2)的电流调节的调节设备(3),所述调节设备包括：电流调节器(4),所述电流调节器用于针对相应的工作点确定输出电压的基本振荡(u1、u2、u3)；控制装置(6),所述控制装置用于基于预定的脉冲模式(P)通过操控调节设备(3)的变流器(5)来调制输出电压,所述预定的脉冲模式针对相应的工作点在最小电流谐波含量方面是经离线优化的；和电流传感器(8),所述电流传感器用于对变流器(5)的由使用的脉冲模式(P)得到的含有谐波的输出电流(ir1、ir2、ir3)采样并且反馈给电流调节器(4),其中,用于采样输出电流(ir1、ir2、ir3)的采样时间点是经离线优化的,并且所述采样时间点被预定为如下时间点,在所述时间点在含有谐波的输出电流(ir1、ir2、ir3)与输出电流的基本振荡(i1)之间的偏差小于预定的阈值。此外,本发明涉及一种方法、驱动单元(1)以及机动车。(The invention relates to a control device (3) for current control of a rotating field motor (2) of a motor vehicle, comprising: a current regulator (4) for determining a basic oscillation (u1, u2, u3) of the output voltage for the respective operating point; a control device (6) for modulating the output voltage by actuating a converter (5) of the regulating device (3) on the basis of a predetermined pulse pattern (P) which is optimized offline with respect to a minimum current harmonic content for the respective operating point; and a current sensor (8) for sampling and feeding back harmonic-containing output currents (ir1, ir2, ir3) of the current transformer (5) resulting from the used pulse pattern (P) to the current regulator (4), wherein sampling points in time for sampling the output currents (ir1, ir2, ir3) are optimized offline and are predetermined as points in time at which a deviation between the harmonic-containing output currents (ir1, ir2, ir3) and a fundamental oscillation (i1) of the output currents is smaller than a predetermined threshold value. The invention further relates to a method, a drive unit (1) and a motor vehicle.)

1. Adjusting device (3) for current adjustment of a rotating field motor (2) of a motor vehicle, comprising:

a current regulator (4) which is designed to determine a basic oscillation (u1, u2, u3) of the output voltage for the respective operating point;

a control device (6) which is designed to modulate the output voltage by actuating a converter (5) of the regulating device (3) on the basis of a predetermined pulse pattern (P) which is optimized off-line with respect to a minimum current harmonic content for the respective operating point; and

a current sensor (8) which is designed to sample and feed back harmonic-containing output currents (ir1, ir2, ir3) of the current transformer (5) resulting from the pulse pattern (P) used to the current regulator (4),

characterized in that sampling time points (A1, A2, A3, A4, A5, A6) for sampling the output currents (ir1, ir2, ir3) containing harmonics are optimized offline in terms of the pulse pattern (P) used, and are predetermined as time points at which the deviation between the output currents (ir1, ir2, ir3) containing harmonics and the fundamental oscillation (i1) of the output current is smaller than a predetermined threshold value.

2. The regulating device (3) according to claim 1, characterized in that the predetermined pulse pattern (P) is an offline optimized pulse pattern with quarter-oscillation symmetry and the control means (6) are designed for operating the switches of the converter (5) on the basis of the offline optimized pulse pattern with quarter-oscillation symmetry.

3. The regulating device (3) according to claim 1 or 2, characterized in that an assignment between the operating point and the offline optimized pulse pattern (P) is predetermined and stored in the storage means (7), and the control means (6) are designed to select from the assignment that offline optimized pulse pattern (P) corresponds to the respective operating point for operating the switch.

4. Adjusting device (3) according to one of the preceding claims, characterized in that the allocation relations between the offline optimized pulse patterns (P) and the sampling time points (a1, a2, A3, a4, a5, A6) are predetermined and stored in a memory means (7), and in that the control means (6) are designed to select from the allocation relations which sampling time point (a1, a2, A3, a4, a5, A6) corresponds to the currently used pulse pattern (P) and to supply to the current sensor (8) for sampling the output current (ir1, ir2, ir 3).

5. A regulating device (3) according to claim 4, characterized in that the sampling rate is predefined and the control means (6) are designed to select from said distribution relation a number of sampling time points (A1, A2, A3, A4, A5, A6) to be used, each basic oscillation interval corresponding to a sampling rate, said sampling time points corresponding to a currently used pulse pattern (P).

6. Regulating device (3) according to one of the preceding claims, characterized in that the operating point is determined by the degree of modulation (M) which is dependent on the basic oscillation amplitude (U1) of the output voltage and by the switching frequency (f) which is predetermined for the switches (S) of the current transformer (5)_s) And the fundamental oscillation frequency (f) of the output voltage₀) The pulse ratio (p) is determined, wherein the control device (6) is designed to provide pulse-mode modulation if the modulation (M) is greater than a predetermined modulation threshold and/or the pulse ratio (p) is less than a predetermined pulse ratio threshold, and otherwise to provide space vector modulation for the converter (5).

7. A method for current regulation of a rotating field motor (2) of a motor vehicle,

determining a basic oscillation (u1, u2, u3) of the output voltage for the respective operating point by means of the current regulator (4),

-modulating the output voltage by means of the converter (5) on the basis of a predetermined pulse pattern (P) which is optimized off-line in respect of minimum current harmonic content in the respective operating point and which is optimized off-line

-the harmonic-containing output currents (ir1, ir2, ir3) of the current transformer (5) resulting from the used pulse pattern (P) are sampled by a current sensor (8) and fed back to the current regulator (4), characterized in that,

sampling time points (A1, A2, A3, A4, A5, A6) for sampling the output currents (ir1, ir2, ir3) are optimized offline with respect to the pulse pattern (P) used and are provided for current regulation in the operation of the rotating field motor (2), and the sampling time points are predetermined as time points at which the deviation between the harmonic-containing output currents (ir1, ir2, ir3) and the fundamental oscillation (i1) of the output currents is less than a predetermined threshold value.

8. Drive unit (1) for a motor vehicle with a rotating field motor (2) and an adjusting device (3) according to one of claims 1 to 6.

9. Motor vehicle with a drive unit (1) according to claim 8.

Technical Field

The invention relates to a control device for current control of a rotating field motor of a motor vehicle. The control device has a current regulator which is designed to determine a fundamental oscillation of the output voltage for a respective operating point. The control device also has a control device which is designed to modulate the output voltage by actuating a converter of the control device on the basis of a predefined pulse pattern which is optimized offline with respect to a minimum current harmonic content for the respective operating point. Furthermore, the control device has a current sensor which is designed to sample the output current of the current transformer, which output current is derived from the pulse pattern used and contains harmonics, and to feed it back to the current controller. The invention further relates to a method for current regulation, a drive unit and a motor vehicle.

Background

Rotary field motors or ac motors with variable rotational speeds are currently of interest, which can be used, for example, as drive motors for electrically drivable motor vehicles. Such a rotating field motor may be, for example, a three-phase rotating field motor, the three phases of which are supplied with a defined setpoint current by means of a current transformer for providing a defined rotational speed. For this purpose, the converter has a number of converter half-bridges corresponding to the number of phases with controllable switches. For the rotational speed-variable operation of the rotating field motor, the switches can be actuated, for example, on the basis of space vector modulation. By means of space vector modulation, the output voltage of the converter half-bridge is generated with a fundamental oscillation, which is specified by the current regulator for the respective operating point. However, space vector modulation is not suitable for certain operating points, since it leads to output currents containing harmonics or to current distortions. Such operating points are characterized by a high modulation degree and a low switching frequency of the switches of the converter.

For this purpose, DE19626447a1 discloses: the output voltage is modulated based on the optimized pulse pattern. This optimized pulse pattern is predetermined in relation to the operating point to be provided and results in an output current of the converter with a lower current harmonic content. If the output current is now sampled at the point in time at which current harmonics or current ripples occur and these poorly sampled output currents are fed back to the current regulator, the current regulator thus attempts to compensate for the deviation between the theoretical current and the sampled output current by adjusting the output voltage. This is not possible, however, because deviations caused by current harmonics cannot be influenced by the current regulators. Furthermore, DE19626447a1 therefore also suggests: the output current is first synchronously sampled by means of a pulse pattern. In order to correct the output current, the current ripple contribution associated with the optimized pulse pattern is subtracted from the sampled output current and the output current thus corrected is supplied to the current regulation. For this purpose, the current ripple contribution must be evaluated and parameterized, which leads to inaccurate results.

Disclosure of Invention

The object of the present invention is to provide an alternative solution for providing a reliable current regulation for a rotating field motor of a motor vehicle.

According to the invention, the object is achieved by an adjusting device, a method, a drive unit and a motor vehicle having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject matter of the dependent claims, the description and the drawings.

The control device according to the invention is used for current control of a rotating field motor of a motor vehicle. The regulating device comprises a current regulator which is designed to determine a fundamental oscillation of the output voltage for the respective operating point. The control device also comprises a control device which is designed to modulate the output voltage by actuating a converter of the control device on the basis of a predefined pulse pattern which is optimized offline with respect to a minimum current harmonic content for the respective operating point. The current sensor of the control device is designed to sample the harmonic-containing output current of the converter, which is obtained from the pulse pattern used, and to feed it back to the current controller. Furthermore, the sampling time points for sampling the output current are optimized offline with respect to the pulse pattern used, and are predetermined as time points at which the deviation between the output current containing harmonics and the fundamental oscillation of the output current is less than a predetermined threshold value.

The invention further relates to a method for current regulation of a rotating field motor of a motor vehicle. In the method, a basic oscillation of the output voltage is determined for the respective operating point by means of a current regulator. The output voltage is modulated by means of a converter on the basis of a predetermined pulse pattern, which is optimized offline with respect to a minimum current harmonic content for the respective operating point. Furthermore, the harmonic-containing output current of the current transformer, which is obtained from the pulse pattern used, is sampled by a current sensor and fed back to the current regulator. Furthermore, the sampling time points for sampling the output current are optimized offline with respect to the pulse pattern used and are provided for current regulation during operation of the rotating field motor. The sampling time is predetermined as a time at which a deviation between the output current containing harmonics and a fundamental oscillation of the output current is less than a predetermined threshold value.

The rotating field motor and the control device with the converter form a control loop. Rotating field motors are, in particular, variable-speed, multiphase rotating field motors, which are designed as drives for electrically drivable motor vehicles. For energizing the phases of the electric machine, a converter is provided, which has a number of converter half-bridges with controllable switches corresponding to the number of phases. These switches are in particular semiconductor switches in the form of power MOSFETs or IGBTs. The rotating field motor and the converter of the control device form a controlled system of the control loop.

In order to provide a defined operating point, at which the rotating field machine has a defined rotational speed, the individual phases are supplied with a defined setpoint current, which is provided as an output current of the converter. In order to provide this setpoint current, a setpoint value for the fundamental oscillation of the output voltage is determined and specified by the current regulator. These theoretical values are in particular the theoretical values for the fundamental oscillation amplitude and the fundamental oscillation frequency of the output voltage. The output voltage is modulated by the converter and is provided at the output of the converter half bridge.

So-called pulse mode modulation is implemented for modulating or generating the output voltage. For this purpose, an operating point-specific pulse pattern is determined off-line, i.e., for example in a manufacturer-side test run of the rotating field motor. The pulse mode is characterized or described by the switching angle for the converter switches and is determined in such a way that the output current resulting from the pulse mode has reduced harmonics or distortions. The operating point can be described, for example, by a defined modulation factor and pulse ratio of the rotating field motor. The modulation or modulation ratio is the ratio between the fundamental oscillation amplitude of the converter output voltage to be provided for the speed regulation and the physically largest possible fundamental oscillation amplitude of the converter output voltage. The pulse ratio is the ratio between the switching frequency of the converter switches and the fundamental oscillation frequency of the converter output voltage to be supplied for speed regulation. The pulse ratio specifies, for example, the number of possible switching angles within one quarter oscillation of the pulse pattern.

In order to now achieve a specific operating point, an offline optimized pulse pattern corresponding to this operating point is provided by: the switches of the converter are actuated according to the offline optimized switching angle of the pulse pattern. The pulsed output voltage provided by the inverter half-bridge at the output of the inverter results in a substantially sinusoidal output current on the basis of the phase windings of the rotating field machine, which may, however, always contain harmonics. This harmonic-containing output current is now sampled so that the sampled output current can be fed back to the current regulator. The sampling is carried out here at the output of the converter by means of a current sensor. If the sampling is now carried out at the time at which the harmonic occurs, the current regulator identifies a harmonic-related deviation between the output current and the setpoint current. Although the current regulator cannot affect the harmonics, the current regulator adjusts the fundamental oscillation of the output voltage for current regulation.

Thus, in addition to the offline optimized pulse pattern, also pulse pattern specific sampling time points are predetermined and provided as offline optimized sampling time points for sampling. For this purpose, a time point is determined at which the deviation between the output current containing the harmonics and the fundamental oscillation of the output current is minimal. Such a point in time is in particular determined at the intersection between the output current containing harmonics and the fundamental oscillation of the output current. At this point in time, the current distortion is minimal. The threshold value is therefore approximately zero. In the case of a rotating-field motor operation, firstly an offline optimized pulse pattern is provided which is required for the operating point to be provided, and the converter is operated on the basis of this pulse pattern. Then, a sampling time point at which the harmonic corresponding to the pulse pattern to be used is minimum is provided. The output current containing harmonics is sampled at the sampling time point and fed back to the current regulator for comparison with the theoretical current.

The regulating device or the method enables a combination of an optimized pulse pattern and the best possible sampling point in time. By predetermining the sampling time at which the distortion is minimal, complex and inaccurate parameterization of the current ripple can furthermore be dispensed with. Current ripple can thus be minimized in a simple manner and reliable current regulation can be provided.

Preferably, the predetermined pulse pattern is an offline optimized pulse pattern with quarter-oscillation symmetry. The control device is designed to control the switches of the converter on the basis of the offline optimized pulse pattern with quarter-oscillation symmetry. Furthermore, the pulse pattern may additionally have a one-half pulse pattern. Harmonics or even harmonics are reduced or eliminated by this pulse pattern. In addition to the predefined quarter-wave symmetry, the number of switching angles per quarter-wave is predefined by the pulse ratio, so that the pulse pattern is completely defined by the switching angle intervals [0, π/2 ].

It was verified as advantageous: the assignment between the operating point and the offline optimized pulse pattern is predetermined and stored in the memory device, and the control device is designed to select from the assignment that offline optimized pulse pattern corresponds to the respective operating point for actuating the switch. Furthermore, it is verified as advantageous: the assignment between the offline optimized pulse pattern and the sampling time point at which the harmonic is minimal is predetermined and stored in a memory means, and the control means are designed to select from the assignment that sampling time point which corresponds to the pulse pattern currently used and to supply it to the current sensor for sampling the output current containing the harmonic.

The regulating device may have, for example, a memory device in which the assignment in the form of a conversion table or a look-up table is stored. For this purpose, the operating points of the different operating points in the form of different combinations of modulation and pulse ratio are assigned a predetermined offline optimized pulse pattern or the switching angle thereof. These offline optimized pulse patterns or offline optimized switching angles may in turn be assigned to predetermined offline optimized sampling time points at which distortion is minimal. The conversion table stored in the memory device is then read by the control device during operation of the rotating field machine, which can then actuate the converter switches and the current sensors. A particularly simple and cost-effective current regulation of the rotating field motor can thus be provided.

It can also be provided that: the sampling rate is predefined and the control device is designed to select from the assignment a number of pulse-pattern-specific sampling points of time for each basic oscillation to be used, which sampling points of time correspond to the sampling rate. The number of sampling points in time can thus be freely selected and can be varied during operation of the rotating field motor.

In a further development of the invention, the operating point is determined by a modulation degree dependent on the basic oscillation amplitude of the output voltage and by a pulse ratio formed by a predetermined switching frequency for the converter switches and the basic oscillation frequency of the output voltage, wherein the control device is designed to provide pulse-mode modulation if the modulation degree is greater than a predetermined modulation degree threshold value and/or the pulse ratio is less than a predetermined pulse ratio threshold value, and otherwise to provide space vector modulation for the converter. The control device can thus operate the converter on the basis of space vector modulation and on the basis of pulse mode modulation. The modulation degree threshold may be, for example, 0.91. The pulse ratio threshold may be, for example, 20. At low modulation levels and large pulse ratios, space vector modulation is used in particular. This is particularly advantageous because space vector modulation can be performed simply and has a linear characteristic. At high modulation and small pulse ratio, pulse mode modulation is used. At high modulation and low pulse ratio, space vector modulation provides non-linear characteristics and high current distortion. In this case, switching is made to pulse mode modulation which eliminates these disadvantages.

The invention further relates to a drive unit for a motor vehicle having a rotating field motor and an adjusting device according to the invention or according to one embodiment.

The motor vehicle according to the invention comprises a drive unit according to the invention. The motor vehicle is in particular a passenger vehicle of the type designed as an electric or hybrid vehicle, which can be driven by means of the drive unit according to the invention.

The exemplary embodiments described with reference to the adjusting device according to the invention and their limited applicability apply accordingly to the method according to the invention, to the drive unit according to the invention and to the motor vehicle according to the invention.

Further features of the invention emerge from the claims, the figures and the description of the figures. The features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the figures and/or shown in the figures individually can be used not only in the respectively given combination but also in other combinations or in isolation.

Drawings

The invention will now be further elucidated on the basis of a preferred embodiment and with reference to the drawing. In the figure:

fig. 1 shows a schematic view of an embodiment of a drive unit according to the invention;

figure 2 shows a schematic diagram of a rotating field motor together with a current transformer;

fig. 3 shows a schematic diagram of the output voltage of the converter and the phase voltage of the rotating field machine; and

FIG. 4 shows a schematic diagram of different signal profiles;

in the figures identical and functionally identical elements are provided with the same reference numerals.

Detailed Description

Fig. 1 shows an embodiment of a drive unit 1 for an electrically drivable motor vehicle, not shown here. The drive unit 1 has a rotating-field motor 2 and a regulating device 3 for current-regulating the rotating-field motor 2. The rotating field motor 2 is a three-phase rotating field motor, which is designed as a drive motor for a motor vehicle. Fig. 2 shows a rotating field motor 2 with three phases U, V, W, which are connected in a common star point. The control device 3 has a current regulator 4 which can determine basic oscillations u1, u2, u3 for the output voltage for providing a determined operating point-specific setpoint current for the individual phases of the rotating field motor 2. The rotational speed of the rotating field motor 2 can be set at a specific operating point by means of the setpoint current.

The current transformer 5 of the control device 3 modulates the basic oscillations u1, u2, u3 of the output voltage, which have a corresponding operating-point-specific basic oscillation frequency and a corresponding operating-point-specific basic oscillation amplitude. For this purpose, as shown in fig. 2, the converter 5 has a converter half-bridge HB1, HB2, HB3 with controllable switches S for each phase U, V, W of the rotating field motor 2. The converter 5 is connected to an intermediate circuit ZK, in which the electrical energy is intermediately stored in intermediate circuit capacitors C1, C2. For this purpose, the intermediate circuit capacitors C1, C2 are supplied with a corresponding DC voltage + U_dc/2、-U_dc/2 charging, the converter 5 generates a modulated pulse-shaped and rectangular output voltage u1 ', u2 ', u3 ' from the direct voltage (see fig. 3). The output voltages u1 ', u2 ', u3 ' provided at the output of the converter 5 result in the phase voltages uph1, uph2, uph3 and, due to the inductive filtering effect of the windings of the phases U, V, W of the rotating-field motor 2, in output currents ir1, ir2, ir3 which are approximately sinusoidal but contain harmonics.

In order to provide a modulated output voltage u1 ', u2 ', u3 ' while the output current ir1, ir2, ir3 has a minimum harmonic content, the control device 6 of the regulating device 3 controls the switches S of the converter half-bridges HB1, HB2, HB3 of the converter 5 in accordance with an offline optimized pulse pattern P (see fig. 3) for the operating point to be provided. The pulse pattern P is optimized for the respective operating point with regard to the harmonic content of the output currents ir1, ir2, ir3 of the converter 5. For this purpose, for example, a conversion table can be stored in the memory device 7 of the control unit 3, in which the respective operating point is assigned the associated optimized pulse pattern P with the least distortion. The pulse pattern P can be determined, for example, during a test operation of the rotating field motor 2 on the manufacturer side and stored in the memory device 7 for the operation of the rotating field motor 2 on the customer side. The memory means 7 can be read by the control means 6 in order to select from the conversion table the off-line optimized pulse pattern P corresponding to the respective operating point.

As shown in fig. 3, through the switching angle a for the switch S of the converter 5₁、a₂One such pulse pattern P is defined. Through the switch angle a₁、a₂A modulated output voltage U1' is generated, which can be the intermediate circuit voltage U of the intermediate circuit ZK connected to the converter 5_dcValue of + U_dc2 and-U_dc/2. Here, in the basic oscillation interval [ 0; 2 pi]The switching angle a is determined by the fundamental oscillation in₁、a₂So that the pulse pattern P has quarter-oscillation symmetry. That is, at quarter oscillation interval [ 0; pi/2]The pulse pattern within and within a quarter of the oscillation interval [ pi/2; pi]The inner pulse pattern P is symmetrical, etc. Further, the pulse pattern P within the half oscillation interval is point-symmetric. Thus, the pulse pattern P passes through the switching angle a₁、a₂At quarter oscillation interval [ 0; pi/2]Is fully defined. In fig. 3, a phase voltage uph1 resulting from the modulated output voltage U1' is additionally shown on the associated phase U of the rotating field motor 2.

In fig. 4, the operating point p, M is shown at a basic oscillation interval [ 0; 2 pi]The characteristic curve of the fundamental oscillation u1 of the internal output voltage, the characteristic curve of the modulated output voltage u 1', the characteristic curve of the output current ir1 containing harmonics and the fundamental characteristic curve of the output currentThe variation curve of i1 is oscillated. The operating point p, M is determined here by the pulse ratio p and by the modulation M. The pulse ratio p is the switching frequency fs of the switches of the inverter 5 and the fundamental oscillation frequency f of the fundamental oscillations u1, u2, u3 of the output voltage₀The ratio therebetween. Switching frequency f of the switch_sIs limited and may for example be up to 10 kHz. Fundamental oscillation frequency f₀In relation to the rotational speed to be supplied and increases with the rotational speed. Thereby, the pulse ratio p decreases at a high rotation speed. The modulation M is formed by the ratio between the modulation M and the physically possible basic oscillation amplitude.

The output current ir1 resulting from the pulsed, modulated output voltage u 1' is a fundamental oscillation i1 which contains harmonics and deviates from the output current. The harmonic-containing current ir1 and the harmonic-containing currents ir2, ir3 of the other converter half-bridges HB1, HB2, HB3 of the converter 5 are now sampled by means of the current sensor 8 of the control device 3. The sampled current is fed back to the current regulator 4, which current regulator 4 thus compares the sampled current with the theoretical current and adjusts the basic oscillation u1, u2, u3 of the output voltage, if possible. The current ir1 is sampled at sampling points in time a1, a2, A3, a4, a5, a6 or at sampling angles at which the deviation between the harmonic-containing current ir1 and the fundamental oscillation i1 of the output current is minimal, in particular approximately zero. The sampling points in time a1, a2, A3, a4, a5, a6 are not equidistant here in particular, but rather relate to the currently used pulse pattern P. The time points at which the deviation is minimal are predetermined in relation to the pulse pattern P and are therefore likewise optimized off-line. The pulse-pattern-specific sampling points in time a1, a2, A3, a4, a5, a6 can likewise be stored in the conversion table of the memory device 7 and read by the control device 6 as a function of the pulse pattern P used for the current operating point P, M.

List of reference numerals:

1 drive unit

2 rotating field motor

3 regulating device

4 current regulator

5 Current transformer

6 control device

7 storage device

8 Current sensor

U, V, W phase

N star shaped contact

HB1, HB2, HB3 converter half bridge

S switch

ZK intermediate circuit

C1, C2 intermediate circuit capacitance

Fundamental oscillation of the u1, u2, u3 output voltages

u1 ', u2 ', u3 ' modulated output voltages

uph1, uph2 and uph3 phase voltages

U_dcIntermediate circuit voltage

U1 fundamental oscillation amplitude

ir1, ir2, ir3 output currents containing harmonics

P pulse mode

a₁、a₂Switch angle

Degree of modulation of M

p pulse ratio

f_sSwitching frequency

f₀Fundamental oscillation frequency

A1, A2, A3, A4, A5, A6 sampling time points