阅读说明：本技术 位置传感器系统和检测位置传感器系统中的误差的方法 (Position sensor system and method of detecting error in position sensor system ) 是由 A·卡拉乔马科夫 J·杰尼施 M·奥古斯蒂尼克 于 2020-02-18 设计创作，主要内容包括：本发明涉及位置传感器系统和检测位置传感器系统中的误差的方法。位置传感器系统包括：位置传感器,具有第一和第二传感器输出；第一信号处理单元,用于处理第一或第二传感器输出的信号；第二信号处理单元,用于处理第二或第一传感器输出的信号；第一系统输出,提供第一或第二信号处理单元的输出；以及第二系统输出,提供第二或第一信号处理单元的输出,其特征在于,位置传感器系统还包括：交换单元,用于将第一信号处理单元从第一传感器输出和第一系统输出交换到第二传感器输出和第二系统输出,并且用于同时将第二信号处理单元从第二传感器输出和第二系统输出交换到第一传感器输出和第一系统输出,反之亦然。(The invention relates to a position sensor system and a method of detecting errors in a position sensor system. The position sensor system includes: a position sensor having first and second sensor outputs; a first signal processing unit for processing a signal output from the first or second sensor; a second signal processing unit for processing the signal output by the second or first sensor; a first system output providing an output of the first or second signal processing unit; and a second system output providing an output of the second or first signal processing unit, characterized in that the position sensor system further comprises: a switching unit for switching the first signal processing unit from the first sensor output and the first system output to the second sensor output and the second system output and for simultaneously switching the second signal processing unit from the second sensor output and the second system output to the first sensor output and the first system output and vice versa.)

1. A position sensor system (1), the position sensor system (1) being particularly for detecting rotational movements, the position sensor system (1) comprising:

a position sensor (2), the position sensor (2) being used in particular for detecting a rotational movement, the position sensor (2) having a first sensor output (3) and a second sensor output (4),

a first signal processing unit (5), the first signal processing unit (5) being used for processing the signal of the first sensor output (3) or the second sensor output (4), in particular for amplifying and filtering the signal of the first sensor output (3) or the second sensor output (4),

a second signal processing unit (6), the second signal processing unit (6) being used for processing the signal of the second sensor output (4) or the first sensor output (3), in particular for amplifying and filtering the signal of the second sensor output (4) or the first sensor output (3),

a first system output (7), the first system output (7) providing an output of the first signal processing unit (5) or the second signal processing unit (6), and

a second system output (8), the second system output (8) providing an output of the second signal processing unit (6) or the first signal processing unit (5),

it is characterized in that

The position sensor system (1) further comprises a switching unit (9), the switching unit (9) being adapted to switch the first signal processing unit (5) from the first sensor output (3) and the first system output (7) to the second sensor output (4) and the second system output (8) and to simultaneously switch the second signal processing unit (6) from the second sensor output (4) and the second system output (8) to the first sensor output (3) and the first system output (7) and vice versa.

2. Position sensor system (1) according to claim 1,

further comprising a control unit (10), the control unit (10) being adapted to process the first system output (7) and the second system output (8).

3. Position sensor system (1) according to claim 2,

wherein the control unit includes: a first analog-to-digital converter (13) for the first system output (7), a second analog-to-digital converter (14) for the second system output (8), and a digital signal processing unit (15) for processing signals of the first analog-to-digital converter (13) and the second analog-to-digital converter (14).

4. Position sensor system (1) according to claim 2,

wherein the control unit (10) comprises: -a multiplexer (16) for multiplexing between the first system output (7) and the second system output (8), -a common analog-to-digital converter (17) connected to an output of the multiplexer (16), and-a digital signal processing unit (15) for processing signals of the common analog-to-digital converter (17).

5. Position sensor system (1) according to one of claims 2 to 4,

wherein the control unit (10) detects fluctuations (18) in the first system output (7) and/or the second system output (8) caused by exchanging the first signal processing unit (5) and the second signal processing unit (6).

6. Position sensor system (1) according to one of the claims 2 to 5,

wherein the control unit (10) further determines the magnitude of fluctuations (18) in the first system output (7) and the second system output (8).

7. Position sensor system (1) according to one of the claims 2 to 6,

wherein the control unit (10) determines second order derivatives of the first system output (7) and the second system output (8) and detects a peak (19) in the calculated second order derivatives, which peak (19) represents an error in the first signal processing unit (5) and in the second signal processing unit (6), respectively.

8. Position sensor system (1) according to claim 7,

wherein the control unit (10) calculates an average of the first system output (7) and the second system output (8) accordingly.

9. A method for detecting errors in a position sensor system (1), in particular for detecting rotational movements, the method comprising:

a first operating condition in which a first sensor output (3) is processed by a first signal processing unit (5) and provided to a first system output (7), and in which a second sensor output (4) is processed by a second signal processing unit (6) and provided to a second system output (8), and

a second operating condition, wherein the first sensor output (3) is processed by the second signal processing unit (6) and provided to the first system output (7), and wherein the second sensor output (4) is processed by the first signal processing unit (5) and provided to the second system output (8),

and further comprising the step of alternating between said first operating condition and said second operating condition.

10. The method of claim 9, wherein the first and second light sources are selected from the group consisting of,

wherein the first system output (3) and the second system output (4) are processed by a control unit (10).

11. The method of claim 10, wherein the first and second light sources are selected from the group consisting of,

wherein the first system output (7) is converted by a first analog-to-digital converter (13) and the second system output (8) is converted by a second analog-to-digital converter (14) of the control unit (10), or wherein the control unit (10) multiplexes between the first system output (7) and the second system output (8) and converts the multiplexed signals by a common analog-to-digital converter (17).

12. The method according to any one of claims 9 to 11,

the method comprises the following steps: detecting fluctuations (18) in the first system output (7) and/or the second system output (8), the fluctuations (18) being caused by alternating between the first operating condition and the second operating condition, preferably in time for a static position sensor, and/or in position of the sensor.

13. The method of claim 12, wherein the first and second light sources are selected from the group consisting of,

the method comprises the following steps: determining the magnitude of the fluctuation (18) in the first system output (7) and the second system output (8).

14. The method of any one of claims 9 to 13,

the method comprises the following steps: second order derivatives of the first system output (7) and the second system output (8) are calculated, and peaks (19) in the calculated second order derivatives are detected, which peaks represent errors in the first signal processing unit (5) and in the second signal processing unit (6), respectively.

15. The method of any one of claims 9 to 14,

the method comprises the following steps: determining an average of the first system output (7) and the second system output (8).

Technical Field

The present invention relates to a position sensor system, in particular to a position sensor system for detecting rotational movements. The invention also relates to a method for detecting errors in a position sensor system, in particular for detecting rotational movements.

Background

The position sensor system, in particular for detecting a rotational movement, comprises a position sensor, in particular for detecting a rotational movement of an item being measured. The object to be measured is for example a rotor in an electric motor.

The position sensor provides raw sensor data in the form of a sinusoidal signal, wherein one period of the sensor signal represents a full revolution or a fraction of a full revolution of the measured item.

In order to improve the signal quality and allow unambiguous position calculation at full phase, a second sensor signal is introduced, which is also sinusoidal, but phase-shifted by a quarter phase or 90 electrical degrees. Typically, the first sensor signal is designated as a sine signal and the second sensor signal is designated as a cosine signal.

The first sensor signal is provided by the first sensor output and the second sensor signal is provided by the second sensor output.

The position sensor system further comprises at least one signal processing unit for processing the sine and cosine signals of the position sensor. Typically, the sensor signal is amplified and filtered by a signal processing unit. In practice, such signal paths of the position sensor system may contain errors, which can be classified as offset errors, gain mismatch errors, and phase errors.

Offset error refers to a shift of one or both sensor signals in the voltage domain to the positive or negative direction. Gain mismatch error refers to the different gains of the sine and cosine signal paths, while phase error refers to a phase shift between the two sensor signals that is lower or higher than the nominal 90 °.

The output of the at least one signal processing unit corresponding to the output of the position sensor system is thereafter processed by an electronic control unit, which for example comprises an analog-to-digital converter and a digital signal processing unit. The electronic control unit may be internal or external to the position sensor system.

According to a variant of the prior art, the signal processing unit comprises a multiplexer at the input of the signal processing unit. A block diagram of such a position sensor system is shown in fig. 11. The sine and cosine signals of the position sensor are processed in sequence, i.e. amplified and filtered, by the signal processing unit and then passed to the electronic control unit.

The electronic control unit has to provide control signals to the multiplexers of the signal processing unit in order to distinguish which signal is being selected by the multiplexers. The advantage of this variant is that both position sensor signals, i.e. the sine signal and the cosine signal, are processed (amplified and filtered) by the same signal processing unit. Thus, there is no gain mismatch, since both are processed by the same signal processing unit, i.e. by the same amplifier. Also, for both position sensor signals, any parasitic phase shift will be the same except for the inherent 90 ° phase shift between the sine and cosine signals introduced by the signal processing unit. Offset errors cannot be eliminated by this variant, however both signals will have the same additional offset (if any) introduced by the signal processing unit. Another advantage of this variant is that the signal processing unit is only needed once for both signals. A disadvantage of this variant is that in a rotary position sensor system, due to the sequential processing of the two signals, the two position sensor signals are not measured at the same position, since the object to be measured will have moved a certain amount between the measurements of the two position sensor signals, which is particularly disadvantageous for high speed systems, since the error increases with the rotational speed. Another disadvantage of this variant is the need for feedback from the electronic control unit to the multiplexer of the signal processing unit, which requires additional signal lines, which is why this variant is usually used for position sensor systems where the electronic control unit is on the same chip as the position sensor system.

According to another variant of the prior art, the sine and cosine signals of the position sensors are processed in parallel by two signal processing units, i.e. each position sensor signal is amplified and filtered by a separate signal processing unit. This provides the fastest possible signal processing, but requires two signal processing units, i.e. two amplifiers and two filters. There will always be some residual gain, offset and/or phase mismatch between these amplifiers. Since the position sensor signals are processed in parallel, the position sensor system has two outputs, one for each signal processing unit.

The electronic control unit may process the two position sensor outputs in parallel by means of two analog-to-digital converters which forward the digital signals to a common digital signal processing unit. However, there will be a non-linear difference in the two analog to digital converters.

Alternatively, the outputs of the two position sensor systems may be processed by a control unit with multiplexed analog to digital converters. The multiplexer is part of a control unit that has full control over the multiplexer and is typically located on the same chip. The limiting factor of this variant is the processing speed of the control unit, in particular of the analog-to-digital converter. This variant also has the same problems with offset, gain and phase mismatch of the two signal processing units of the position sensor system, but eliminates the non-linear difference due to the use of only one analog-to-digital converter.

Disclosure of Invention

It is an object of the present invention to detect any gain, offset and phase mismatch of a position sensor system comprising two signal processing units for processing in parallel a sine signal and a cosine signal of a position sensor, especially for high speed position sensor systems.

According to the invention, this object is solved by a position sensor system, in particular for detecting rotational movements, comprising:

a position sensor, in particular for detecting a rotational movement, the position sensor having a first sensor output and a second sensor output,

a first signal processing unit for processing the signal of the first sensor output or the second sensor output, in particular for amplifying and filtering the signal of the first sensor output or the second sensor output,

a second signal processing unit for processing the second sensor output or the signal of the first sensor output, in particular for amplifying and filtering the second sensor output or the signal of the first sensor output,

a first system output providing an output of the first signal processing unit or the second signal processing unit, an

A second system output providing an output of the second signal processing unit or the first signal processing unit,

it is characterized in that

The position sensor system further comprises a switching unit for switching the first signal processing unit from the first sensor output and the first system output to the second sensor output and the second system output and for simultaneously switching the second signal processing unit from the second sensor output and the second system output to the first sensor output and the first system output and vice versa.

The position sensor system according to the invention has a first operating condition in which the first sensor output is connected to the first signal processing unit and the output of the first signal processing unit is connected to the first system output, and in which the second sensor output is connected to the second signal processing unit and the output of the second signal processing unit is connected to the second system output. The switching unit switches the position sensor system to a second operating condition, wherein the switching unit is configured to switch the first signal processing unit from the first sensor output and the first system output to the second sensor output and the second system output, and to simultaneously switch the second signal processing unit from the second sensor output and the second system output to the first sensor output and the first system output. In a second operating condition, the first sensor output is connected to the second signal processing unit and the output of the second signal processing unit is connected to the first system output, and the second sensor output is connected to the first signal processing unit and the output of the first signal processing unit is connected to the second system output. Thus, the switching unit switches the position sensor system from the first operating condition to the second operating condition, then back to the first operating condition again, and so on.

By exchanging the first signal processing unit and the second signal processing unit between the first sensor output and the first system output and the second sensor output and the second system output, the position sensor signal is alternately processed by the first signal processing unit and the second signal processing unit. By detecting any difference between the processing by the first signal processing unit and the processing by the second signal processing unit, any gain, offset and phase mismatch of the position sensor system can be detected. Any mismatch between the first signal processing unit and the second processing unit is measurable as a fluctuation on the output of the first signal processing unit and the second processing unit. Furthermore, the position sensor system allows for fast error detection at low rotational speeds or static positions of the position sensor.

In addition, gain mismatch can be compensated for by averaging the swapped and unswitched signals, i.e. averaging the signal for a particular position sensor processed by the first signal processing unit and the signal processed by the second processing unit.

Preferably, the switching unit switches the first signal processing unit and the second processing unit, i.e. between the first operating condition and the second operating condition regularly, preferably at equal intervals.

In a preferred variant of the invention, the first sensor output provides a sine signal and the second sensor output provides a cosine signal, which is phase shifted by a quarter phase or 90 electrical degrees. Such first and second sensor signals are referred to as sine and cosine signals, respectively. However, the present invention is not limited to sinusoidal sensor signals and/or quarter-phase or 90 electrical degree phase shifts.

According to a variant of the invention, the first signal processing unit and the second signal processing unit each comprise an amplifier and a filter for amplifying and filtering the first sensor output and the second sensor output.

According to a particularly preferred variant of the invention, the position sensor system further comprises a control unit for processing the first system output and the second system output. The control unit may be internal or external and in particular on the same chip or on a different chip than the position sensor system.

According to a variant of the invention, the control unit comprises a first analog-to-digital converter for the output of the first system, a second analog-to-digital converter for the output of the second system and a digital signal processing unit for processing the signals of the first analog-to-digital converter and the second analog-to-digital converter. Thus, the signals of the first system output and the second system output are processed in parallel by the first analog-to-digital converter and the second analog-to-digital converter of the control unit, respectively. This provides the fastest possible signal processing, but may add some non-linear difference due to the two analog to digital converters.

In an alternative variant of the invention the control unit comprises a multiplexer for multiplexing between the first system output and the second system output, and a common analog-to-digital converter connected to an output of the multiplexer, and a digital signal processing unit for processing signals of the common analog-to-digital converter. This variant is limited by the processing speed of the analog-to-digital converter. Since the multiplexers and the control units controlling the multiplexers are typically on the same chip, this does not unduly limit the processing speed. Since only one analog-to-digital converter is used in this variant, possible non-linear differences due to two analog-to-digital converters are avoided.

In either alternative, the digital signal processing unit typically does not limit the processing speed due to the current processing speed and available multi-core processors.

The control unit is in particular designed to detect fluctuations in the first system output and/or the second system output caused by an exchange of the first signal processing unit and the second signal processing unit, i.e. caused by an alternation between the first operating condition and the second operating condition. The first system output and the second system output will be changed at the same time as the exchange of the signal processing units if there is any gain, offset and/or phase mismatch. This change in the first system output and the second system output, referred to as a fluctuation, is detected by the control unit. If the exchange occurs at regular intervals, the fluctuations will also change at these intervals.

According to the invention, the position sensor is mounted on a non-moving part of the item to be measured.

According to a variant of the invention, the control unit also determines the magnitude of the fluctuation in the first system output and/or the second system output. This helps to measure and distinguish between any offset error, gain mismatch error and phase error.

According to a preferred variant of the invention, the control unit determines the second derivatives of the first system output and the second system output and detects a peak in the calculated second derivatives, which peak is accordingly representative of the error in the first signal processing unit and in the second signal processing unit. The wave determination is adversely affected by signal noise in the case where the article to be measured is rotating during the wave determination and/or in the first signal processing unit, the second signal processing unit. Improved results may be obtained by determining the second derivative of the first system output and the second system output representative of their respective accelerations. Since the rate of change in the exchange step, i.e. the rate of change of the switching between the first and the second operating condition, is much faster than the typical rotational movement of the item to be measured, these situations can be easily distinguished. Also, the switching step can be easily distinguished from the noise that typically occurs in analog signal processing.

In a variant of the invention, the control unit calculates an average of the respective first and second system outputs. By determining the average value of the system output signal, any gain mismatch error between the two signal processing units can be compensated. Furthermore, by determining the average value, any phase error can be reduced to a constant level throughout the signal period, and any offset error can be reduced.

Preferably, the position sensor is a magnetic sensor, an inductive sensor or an eddy current sensor, in particular a hall sensor, an anisotropic magnetoresistive sensor, a tunnel magnetoresistive sensor or a giant magnetoresistive sensor.

The position sensor system may include more than one position sensor. Preferably, the position sensor system comprises two separate signal processing units and a corresponding switching unit for each position sensor. By providing more than one, further preferably at least three position sensors, the data of the position sensors can be compared with each other to detect errors in the data of the position sensors. By having two or more position sensors, a position sensor to which an erroneous signal is supplied can be detected more easily.

According to the invention, the object is also solved by a method for detecting errors in a position sensor system, in particular for detecting rotational movements, comprising:

a first operating condition in which the first sensor output is processed by the first signal processing unit and provided to the first system output, and in which the second sensor output is processed by the second signal processing unit and provided to the second system output, an

A second operating condition in which the first sensor output is processed by the second signal processing unit and provided to the first system output, and in which the second sensor output is processed by the first signal processing unit and provided to the second system output,

and further comprising the step of alternating between the first operating condition and the second operating condition.

In a first operating condition of the position sensor, the first sensor signal is processed by the first signal processing unit and provided to the first system output, and the second system sensor output is processed by the second signal processing unit and provided to the second system output. By swapping the signal processing units, the position sensor system is in a second operating condition, wherein the first sensor output is processed by the second signal processing unit and provided to the first system output, and wherein the second sensor output is processed by the first signal processing unit and provided to the second system output. According to the method of the invention, the first operating conditions and the second operating conditions are alternated.

By detecting any difference between the processing by the first signal processing unit and the processing by the second signal processing unit, any gain, offset and phase mismatch can be detected. Any mismatch between the first signal processing unit and the second processing unit is measurable as a fluctuation on the output of the first signal processing unit and the second processing unit. Furthermore, the position sensor system allows for fast error detection at low rotational speeds or at static positions of the position sensor.

In a preferred variant of the invention, the first sensor output provides a sine signal and the second sensor output provides a cosine signal, which are phase shifted by a quarter phase or 90 electrical degrees. Such first and second sensor signals are referred to as sine and cosine signals, respectively. However, the present invention is not limited to sinusoidal sensor signals and/or quarter-phase or 90 electrical degree phase shifts.

According to a variant of the invention, the first signal processing unit and the second signal processing unit each amplify and filter the first sensor output or the second sensor output depending on the current operating conditions. Thus, the first signal processing unit and the second signal processing unit each comprise an amplifier and a filter.

According to a particularly preferred variant of the invention, the first system output and the second system output are processed by the control unit. The control unit may be internal or external and in particular on the same chip or on a different chip with the position sensor system.

In a variant of the invention, the first system output is converted by a first analog-to-digital converter of the control unit, and the second system output is converted by a second analog-to-digital converter. Thus, the signals of the first system output and the second system output are processed in parallel by the first analog-to-digital converter and the second analog-to-digital converter of the control unit, respectively. This provides the fastest possible signal processing, but may add some non-linear difference due to the two analog to digital converters.

Alternatively, the control unit multiplexes between the first system output and the second system output, and converts the multiplexed signal by the common analog-to-digital converter. This variant is limited by the processing speed of the analog-to-digital converter. Since the multiplexers and the control units controlling the multiplexers are typically on the same chip, this does not unduly limit the processing speed. Since only one analog-to-digital converter is used in this variant, possible non-linear differences due to two analog-to-digital converters are avoided.

Advantageously, the signals of the first and second analog-to-digital converters or the signal of the common analog-to-digital converter are processed by a digital signal processing unit. Digital signal processing units typically do not limit processing speed due to current processing speeds and available multi-core processors.

According to a variant of the invention, the method comprises the step of determining fluctuations in the first system output and/or the second system output for a static position sensor over time and/or over the position of the sensor.

In a preferred variant of the invention, the method comprises the step of determining the magnitude of the fluctuations in the first system output and the second system output. This helps to measure and distinguish between any offset error, gain mismatch error and phase error.

According to a particularly preferred variant of the invention, the method comprises the steps of: second order derivatives of the first system output and the second system output are calculated, and peaks in the calculated second order derivatives, which peaks represent errors in the respective first signal processing unit and in the second signal processing unit, are detected. Improved results may be obtained by determining the second derivative of the first system output and the second system output representative of their respective accelerations. Since the rate of change in the exchange step, i.e. the rate of change of the switching between the first and the second operating condition, is much faster than the typical rotational movement of the item to be measured, these situations can be easily distinguished. Also, the switching step can be easily distinguished from the noise that typically occurs in analog signal processing.

According to a variant of the invention, the method comprises the step of determining an average of the first system output and the second system output. By determining the average value of the system output signal, any gain mismatch error between the two signal processing units can be compensated. Furthermore, by determining the average value, any phase error can be reduced to a constant level throughout the signal period, and any offset error can be reduced.

Preferably, the steps of alternating between the first operating condition and the second operating condition are performed regularly, preferably at equal intervals.

Drawings

In the following, the invention will be further explained with respect to embodiments shown in the drawings. The figures show:

figure 1a is a block diagram of a position sensor system according to a first embodiment of the invention in a first operating condition,

figure 1b is a block diagram of the position sensor system of figure 1a in a second operating condition,

figure 2a is a block diagram of a position sensor system according to a second embodiment of the invention in a first operating condition,

figure 2b is a block diagram of the position sensor system of figure 2a in a second operating condition,

figure 3 is a block diagram of a position sensor system according to a third embodiment of the invention in a first operating condition,

figure 4 is a graph of the output signal of the position sensor system showing error-free exchange in the signal path,

figure 5a is a graph showing the output signal of an swapped position sensor system with offset error,

figure 5b is a graph showing the output of a static position sensor having the offset error of figure 5a over time,

figure 5c is a graph showing the offset error in position and the magnitude of the offset error in position for the signal of figure 5a,

figure 5d is a graph showing the total error and the total average error over position of the signal of figure 5a,

figure 6a is a graph showing the output signal of a position sensor system with an exchange of amplitude errors,

figure 6b is a graph showing the output of the static position sensor over time with the amplitude error of figure 6a,

figure 6c is a graph showing the amplitude error in position and the magnitude of the amplitude error in position for the signal of figure 6a,

figure 6d is a graph showing the total error in position and the total average error in position for the signal of figure 6a,

figure 7a is a graph showing the output signals of a position sensor system with an exchange of phase errors,

figure 7b is a graph showing the output of the static position sensor with the phase error of figure 7a over time,

figure 7c is a graph showing the phase error of the signal of figure 7a in position and the magnitude of the phase error in position,

figure 7d is a graph showing the total error over position and the total average error over position for the signal of figure 7a,

figure 8a is a graph showing the second derivative of the output signal for a position sensor system with an offset error in position,

figure 8b is a graph showing the magnitude of the signal of figure 8a over time,

figure 9a is a graph showing the second derivative of the output signal for a position sensor system having an amplitude error in position,

figure 9b is a graph showing the magnitude of the signal of figure 9a over time,

figure 10a is a graph showing the second derivative of the output signal for a position sensor system with a phase error in position,

FIG. 10b is a graph showing the magnitude of the signal of FIG. 10a over time, an

Fig. 11 is a block diagram of a position sensor system according to the prior art.

Detailed Description

Fig. 1a shows a block diagram of a first embodiment of a position sensor system 1, the position sensor system 1 being used in particular for detecting a rotational movement in a first operating condition. The position sensor system 1 comprises a position sensor 2, the position sensor 2 being used in particular for detecting a rotational movement and having a first sensor output 3 and a second sensor output 4. The position sensor system 1 further comprises a first signal processing unit 5 for processing, in particular amplifying and filtering, the signals of the first sensor output 3 or the second sensor output 4, and a second signal processing unit 6 for processing, in particular amplifying and filtering, the signals of the second sensor output 4 or the first sensor 3.

The first sensor output 3 and the second sensor output 4 are processed once at a time by the first signal processing unit 5 or the second signal processing unit 6. Thus, if the first sensor output 3 is processed by the first signal processing unit 5 and the second sensor output 4 is processed by the second signal processing unit 6, and if the first sensor output is processed by the second signal processing unit 6, the second sensor output 4 is processed by the first signal processing unit 5.

The position sensor system 1 further includes: a first system output 7 providing an output of the first signal processing unit 5 or the second signal processing unit 6, and a second system output 8 providing an output of the second signal processing unit 6 or the first signal processing unit 5. Also, at a given time, the output of the first signal processing unit 5 is provided by either the first system output 7 or the second system output 8, and the output of the second signal processing unit 6 is provided at that time by the other of the second system output 8 or the first system output 7. Thus, if the output of the first signal processing unit 5 is provided by the first system output 7, the output of the second signal processing unit 6 is provided by the second system output 8, and if the output of the first signal processing unit 5 is provided by the second system output 8, the output of the second signal processing unit 6 is provided by the first system output 7.

According to the invention, the position sensor system 1 further comprises a switching unit 9, the switching unit 9 being adapted to switch the first signal processing unit 5 from the first sensor output 3 and the first system output 7 to the second sensor output 4 and the second system output 8 and to switch the second signal processing unit 6 from the second sensor output 4 and the second system output 8 to the first sensor output 3 and the first system output 7 simultaneously and vice versa. In fig. 1a, the switching unit 9 is identified by two dashed circles, one between the position sensor 2 and the signal processing unit 5, 6 and the other between the signal processing unit 5, 6 and the system output 7, 8, i.e. at the two positions where the switching takes place.

In the first operating condition of fig. 1a, the first sensor output 3 is connected to the first signal processing unit 5, while the output of the first signal processing unit 5 is connected to the first system output 7. Thus, the second sensor output 4 is connected to the second signal processing unit 6, while the output of the second signal processing unit 6 is connected to the second system output 8.

The first signal processing unit 5 and the second signal processing unit 6 each include an amplifier 11 and a filter 12. The amplifier 12 is, for example, an operational amplifier (op-amp), and the filter 12 is, for example, a resistor-capacitor circuit (RC circuit). As indicated by corresponding arrows in fig. 1a, the first signal processing unit 5 and/or the second signal processing unit 6 may add some offset error, gain error and/or phase error.

The position sensor system 1 of fig. 1a further comprises a control unit 10. The control unit 10 may be integrated with the position sensor system 1, i.e. on the same chip, or may be external to the position sensor system 1 and connected to the position sensor system 1, e.g. by a cable. Fig. 1a relates to an external control unit 10, as indicated by the connecting points and lines between the position sensor system 1 and the control unit 10.

The control unit 10 in fig. 1a comprises a first analog-to-digital converter 13 for the first system output 7 and a second analog-to-digital converter 14 for the second system output 8. The outputs of the first and second analog-to-digital converters 13, 14 are processed by the same digital signal processing unit 15.

The control unit 10, in particular the digital signal processing unit 15, is designed to detect fluctuations 18 in the first system output 7 and/or the second system output 8, which fluctuations 18 are caused by the exchange of the first signal processing unit 5 and the second signal processing unit 6.

Furthermore, the control unit 10, in particular the digital signal processing unit 15, is designed to determine the magnitude of the fluctuations 18 for use in the first system output 7 and the second system output 8.

In order to further improve the accuracy of the position sensor system 1, the control unit 10, in particular the digital signal processing unit 15, may determine the second derivative of the first system output 7 and the second system output 8 and detect peaks in the second derivative. The peak value accordingly represents an error, in particular an offset, a gain and/or a phase error, in the first signal processing unit 5 and in the second signal processing unit 6.

In order to reduce or compensate for errors in the first signal processing unit 5 and/or the second signal processing unit 6, the control unit 10, in particular the digital signal processing unit 15, may calculate an average of the first system output 7 and the second system output 8 accordingly.

Fig. 1b shows a block diagram of the position sensor system 1 of fig. 1a in a second operating condition. In this second operating condition the first sensor output 3 is connected to the second signal processing unit 6, while the second signal processing unit 6 is connected to the first system output 5. Furthermore, the second sensor output 4 is connected to a first signal processing unit 5, while the first signal processing unit 5 is connected to a second system output 8. Thus, the switching unit 9 has switched the first signal processing unit 5 from the first sensor output 3 and the first system output 7 to the second sensor output 4 and the second system output 8 and simultaneously switched the second signal processing unit 6 from the second sensor output 4 and the second system output 8 to the first sensor output 3 and the first system output 7. By exchanging the signal processing units 5, 6, the exchanging unit 9 changes the operating conditions of the position sensor system 1.

Since the sensor outputs 3, 4 are processed by different signal processing units 5, 6 in both operating conditions, and since different signal processing units 5, 6 may have different offsets, gains and/or phase errors, the system outputs 7, 8 may contain fluctuations 18 detected by the control unit 10.

In fig. 1b, the switching unit 9 is likewise identified by two dashed circles. The exchange of the signal processing units 5, 6 is identified by the intersection in the two dotted circles.

In a first operating condition shown in fig. 1a, the first sensor output 3 is processed by the first signal processing unit 5 and provided to the first system output 7, and the second sensor output 4 is processed by the second signal processing unit 6 and provided to the second system output 8.

In a second operating condition shown in fig. 1b, the first sensor output 3 is processed by the second signal processing unit 6 and provided to the first system output 7, and the second sensor output 4 is processed by the first signal processing unit 5 and provided to the second system output 8.

The switching unit 8 causes an alternation between the first operating condition and the second operating condition.

The first and second signal processing units 5, 6 amplify and filter the first and second sensor outputs 3, 4 to finally add offset, gain and/or phase errors.

The first system output 7 and the second system output 8 are processed by a control unit 10. The first system output 7 is converted by a first analog-to-digital converter 13 of the control unit 10 and the second system output 8 is converted by a second analog-to-digital converter 14 of the control unit 10. The digital signal processing unit 15 of the control unit 10 processes signals of the first analog-to-digital converter 10 and the second analog-to-digital converter 14.

The control unit 10 detects fluctuations 18 in the first system output 7 and/or the second system output 8, the fluctuations 18 being caused by alternating between the first operating condition and the second operating condition, i.e. by processing the sensor output signals 3, 4 by the different signal processing units 5, 6 in both operating conditions.

By determining the magnitude of the fluctuations 18 in the first system output 7 and the second system output 8, the control unit 8 may determine the kind of error, i.e. offset error, gain error and/or phase error.

By calculating the second derivative of the first and second system outputs 7, 8 and detecting peaks in the calculated second derivative, the accuracy of error detection can be enhanced. The peaks represent accordingly errors in the first signal processing unit 5 and in the second signal processing unit 6.

By determining the average of the first system output 7 and the second system output 8, errors can be reduced or even compensated.

Advantageously, the switching unit 9 regularly, preferably at equal intervals, switches the first signal processing unit 5 and the second signal processing unit 6.

Fig. 2a and 2b show block diagrams of a position sensor system 1 according to a second embodiment of the invention in a first operating condition and a second operating condition, respectively. The second embodiment of the position sensor system 1 shown in fig. 2a and 2b differs from the first embodiment of the position sensor system 1 shown in fig. 1a and 1b in that the control unit 10 only comprises a common analog-to-digital converter 17 instead of the first and second analog-to-digital converters 13, 18. For processing the first system output 7 and the second system output 8, the control unit 10 comprises a multiplexer 16 for multiplexing between the first system output 7 and the second system output 8. The multiplexer 16 is preferably controlled by the control unit 10 and the corresponding information is used by the digital signal processing unit 15 so that the digital signal processing unit 15 can distribute the digital signals currently received from the common analog-to-digital converter 17 to the first system output 7 and the second system output 8, respectively.

Fig. 3 shows a third embodiment of the position sensor system 1 according to the invention in a first operating condition. The third embodiment of fig. 3 differs from the first embodiment of fig. 1a and 1b in that the control unit 10 is an internal control unit 10. Thus, the first system output 7 and the second system output 8 are internal to the position sensor system 1.

Since all other features correspond to the first embodiment of fig. 1a and 1b, the third embodiment is not shown in the second operating condition. Furthermore, the internal control unit 15 can also be used correspondingly for the second embodiment in fig. 2a and 2 b.

Fig. 4 shows exemplary outputs of the first sensor output 3 and the second sensor output 4 without errors, wherein there is no offset between the sine signal 20 and the cosine signal 21, an ideal amplitude match and an ideal 90 ° phase shift, resulting in no switching fluctuations. The horizontal axis of fig. 4 represents the mechanical rotation, in this case 360 °, and the vertical axis represents the signal levels of the first sensor output 3 and the second sensor output 4. In this case, the maximum signal level is 1, 0.

The first sensor output 3 provides a sinusoidal signal which starts at signal level 0 at 0 °. The sinusoidal signal of the first sensor output 3 is referred to as sinusoidal signal 20. The second sensor output 4 also provides a sinusoidal signal which is correspondingly phase shifted by one quarter phase by 90 °. Thus, the signal level of the second sensor output 4 is 1,0 at 0 °. The sine signal output by the second sensor is referred to as the cosine signal 21.

The first sensor output is defined as:

[ x is the number of degrees]Or is or

A sin (X) (radian x)

The second sensor output is defined as:

or[ x is the number of degrees]Or is or

Or A is cos (X) x is radian]。

In fig. 4, the corresponding peak amplitude of signal level a is 1, 0.

Fig. 5a shows an error situation in which the second signal processing unit 6 has an offset error of 10% with respect to the maximum signal amplitude 1, 0. Fig. 5a shows the corresponding sine signal 22 and cosine signal 23 of the first system output 7 and second system output 8, respectively, which have an offset error over the full phase (0 ° to 360 °).

Fig. 5b shows the output of the static sensor at 120 ° of fig. 5a in the time domain. The horizontal time axis is a relative number representing 40 switching cycles (20 switching periods). The deviation between the signals of the two operating conditions (swapped and not) is visible as a rectangular signal, flipping between the two signal levels. This rectangular signal is called a wobble 18. The fluctuation of the exchanged sine signal 22 is indicated by the numeral 28 and the fluctuation of the exchanged cosine signal 23 is indicated by the numeral 29. Fig. 5b furthermore shows the average of the fluctuations 28 of the exchanged sine signal 22 and the fluctuations 29 of the exchanged cosine signal 23.

FIG. 5c shows the offset error of the sine signal 22 and the cosine signal 23 of FIG. 5a, and the magnitude of the two signals over full phase (0 to 360 °)An indication of the offset error is that the error of the sine signal 22 and the cosine signal 23 is constant and equal at any position.

Fig. 5d shows the total error calculated by means of the unswitched signal 31 and the swapped signal 30 at the first system output 7 and the second system output 8, as well as the average total error. By averaging the errors of the unswitched signal 31 and the swapped signal 30, the total offset error can be reduced.

Fig. 6a shows an error situation in which the second signal processing unit has a gain error of 10% with respect to the maximum signal amplitude 1, 0. Fig. 6a shows the sine signal 24 and the cosine signal 25 of the first system output 7 and the second system output 8 respectively with a gain error over the full phase (0 ° to 360 °).

Fig. 6b shows the output of the static sensor in the time domain at 120 ° of fig. 6 a. The horizontal time axis is a relative number representing 40 switching cycles (20 switching periods). The deviation between the signals of the two operating conditions (swapped and not) is visible as a rectangular signal, flipping between the two signal levels. This rectangular signal is called a wobble 18. The fluctuation of the exchanged sine signal 24 is indicated by the numeral 28 and the fluctuation of the exchanged cosine signal 25 is indicated by the numeral 29. Fig. 6b furthermore shows the average of the fluctuations 28 of the exchanged sine signal 24 and the fluctuations 29 of the exchanged cosine signal 25.

As can be seen from fig. 6a and 6b, the maximum fluctuation 18 occurs at the signal peaks, while the minimum fluctuation 18 occurs at the zero crossings of each signal 28, 29.

FIG. 6c shows the gain error of the sine signal 24 and the cosine signal 25 of FIG. 6a, and the magnitude of the two signals over full phase (0 to 360 °)

The largest errors of the sine signal 24 and the cosine signal 25 occur at positive and negative peaks, respectively (90 °, 270 ° for the sine signal 24, 0 °, 180 ° for the cosine signal 25), while the smallest errors occur at zero crossings (0 °, 180 ° for the sine signal 24, 90 °, 270 ° for the cosine signal 25). An indication of gain error is that the error of the sine signal 24 and the cosine signal 25 is not constant over full phase, but the magnitude of both signals is constant.

Fig. 6d shows the total error calculated from the unswitched 31 and swapped 30 signals at the first 7 and second 8 system outputs and the average total error. By averaging the errors of the not swapped signal 31 and the swapped signal 30, the total amplitude error can be eliminated.

Fig. 7a shows an error situation in which the second signal processing unit has a phase shift error of 6 ° compared to the first signal processing unit. Fig. 7a shows the sine signal 26 and the cosine signal 27 of the first system output 7 and the second system output 8 respectively with a phase shift error over the full phase (0 ° to 360 °).

Fig. 7b shows the output of the static sensor at 120 ° of fig. 7a in the time domain. The horizontal time axis is a relative number representing 40 switching cycles (20 switching periods). The deviation between the signals of the two operating conditions (swapped and not) is visible as a rectangular signal, flipping between the two signal levels. This rectangular signal is called a wobble 18. The fluctuation of the exchanged sine signal 26 is indicated by the numeral 28 and the fluctuation of the exchanged cosine signal 27 is indicated by the numeral 29. Fig. 7b furthermore shows the average of the fluctuations 28 of the exchanged sine signal 26 and the fluctuations 29 of the exchanged cosine signal 27.

As can be seen from fig. 7a and 7b, the maximum fluctuation occurs at the zero crossings and the minimum fluctuation occurs at the signal peaks of each signal 26, 27.

FIG. 7c shows the phase shift error of the sine signal 26 and the cosine signal 27 of FIG. 7a and the magnitude of the two signals over full phase (0 to 360 °)

The largest errors of the sine signal 26 and the cosine signal 27 occur at zero crossings (0 °, 180 ° for the sine signal 26, 90 °, 270 ° for the cosine signal 27), respectively, and the smallest errors occur at positive and negative peaks (90 °, 270 ° for the sine signal 26, 0 °, 180 ° for the cosine signal 27). The phase shift error is indicative in that the errors of the sine signal 26 and the cosine signal 27 are not constant over the full phase, but the magnitude of both signals is constant.

Fig. 7d shows the total error calculated from the unswitched 31 and swapped 30 signals at the first 7 and second 8 system outputs and the average total error. By averaging the errors of the unswitched signal 31 and the switched signal 30, the total phase shift error can be reduced to a constant level over the full phase.

Fig. 8a shows the second derivatives of the sine signal 22 and the cosine signal 23 of fig. 5a with reference to the offset error. FIG. 8b shows the magnitude of the second derivative of FIG. 8aDue to the overlap of the second derivative of the sine signal 22 and the second derivative of the cosine signal 23, fig. 8a is divided into two graphs.

The vertical axis on both graphs represents the relative number of second derivatives of the signal. It depends on the time interval between the measurement of the signal fluctuations 18 on the sine signal 22 and the cosine signal 24, representing the sampling rate of the analog-to-digital converters 13, 14, 17 analyzing the sine signal 22 and the cosine signal 23. The larger the error, the larger these signal levels will be. The horizontal axis of fig. 8a represents the position of the position sensor 2 in electrical degrees, and the horizontal axis of fig. 8b is a relative number representing 20 exchange cycles (10 exchange cycles).

The offset error in the first signal processing unit 5 and/or the second signal processing unit 6 is indicated by a second derivative pulse which is constant in position. The second derivative magnitude is also constant in position.

Fig. 9a shows the second derivative of the sine signal 24 and the cosine signal 25 of fig. 6a with reference to the gain error. FIG. 9b shows the magnitude of the second derivative of FIG. 9a

Since the second derivative of the sine signal 24 and the second derivative of the cosine signal 25 partially overlap, fig. 9a is divided into two graphs.

The diagrams of fig. 9a and 9b correspond in particular to fig. 8a and 8b with respect to the axis.

The gain error in the first signal processing unit 5 and/or the second signal processing unit 6 is indicated by a non-constant second derivative peak pulse pattern in position. The second derivative magnitude is constant in position and time.

Fig. 10a shows the second derivatives of the sine signal 26 and the cosine signal 27 of fig. 7a with reference to the phase shift error. FIG. 10b shows the magnitude of the second derivative of FIG. 10aDue to the partial overlap of the second derivative of the sine signal 22 and the second derivative of the cosine signal 23, fig. 10a is divided into two graphs.

The diagrams of fig. 10a and 10b correspond in particular to fig. 8a and 8b with respect to the axis.

The phase shift error in the first signal processing unit 5 and/or the second signal processing unit 6 is indicated by a second derivative peak pulse pattern which is not constant in position. The second derivative magnitude is constant in position and time.

Fig. 11 shows a block diagram of a position sensor system 1 according to the prior art. The position sensor system 1 comprises a position sensor 2 having a first sensor output 3 and a second sensor output 4. The position sensor system 1 further comprises a signal processing unit 32 for processing, in particular amplifying and filtering, the signals of the first sensor output 3 and the second sensor output 4.

The signal processing unit 32 comprises a multiplexer 34 to multiplex between the first sensor output 3 and the second sensor output 4. The signal processing unit 32 further comprises an amplifier 11 and a filter 12.

The position sensor system 1 comprises a system output 33, which system output 33 provides the output of the signal processing unit 32.

The position sensor system 1 of fig. 11 further comprises a control unit 10. The control unit 10 may be integrated with the position sensor system 1, i.e. on the same chip, or may be external to the position sensor system 1 and connected to the position sensor system 1, e.g. by a cable. Fig. 11 relates to the external control unit 10, as indicated by the connecting points and lines between the position sensor system 1 and the control unit 10.

The control unit 10 in fig. 11 comprises an analog-to-digital converter 17 for the system output 33. The output of the analog-to-digital converter 17 is processed by the digital signal processing unit 15.

The control unit 10, in particular the digital signal processing unit 15, has to know which sensor output 3, 4 the signal processing unit 32 is currently processing. The control unit 10, in particular the digital signal processing unit 15, thus controls the multiplexer 34 of the signal processing unit 32 via the control line 35. This requires additional wiring between the position sensor system 1 and the external control unit 10. Another disadvantage of this variant is that in the rotary position sensor system 1, due to the sequential processing of the two signals, the two position sensor signals are not measured at the same position, since the object to be measured will move a certain amount between the measurements of the two position sensor signals, which is particularly disadvantageous for high speed systems, since this error will increase with the rotational speed.

Reference mark

1 position sensor system

2 position sensor

3 first sensor output

4 second sensor output

5 first signal processing unit

6 second signal processing unit

7 first system output

8 second system output

9 switching unit

10 control unit

11 amplifier

12 filter

13 first analog-to-digital converter

14 second analog-to-digital converter

15 digital signal processing unit

16 multiplexer

17 shared analog-to-digital converter

18 fluctuation on sinusoidal signal

19 second derivative of sine signal and cosine signal

20 exchanged sinusoidal signals (first sensor output) without errors

21 error-free exchanged cosine signal (second sensor output)

22 switched sinusoidal signals (with offset error)

23 cosine signal exchanged (with offset error)

24 switched sinusoidal signals (with gain error)

25 switched cosine signal (with gain error)

26 switched sinusoidal signals (with phase shift error)

27 switched cosine signal (with phase shift error)

28 wave exchange sinusoidal signal

29 wave switching cosine signal

30 error exchange signal

31 error not exchanged signal

32 signal processing unit

33 system output

34 multiplexer signal processing unit

35 control line for multiplexer of signal processing unit