Position sensor system and method of detecting errors in a position sensor system

Abstract

The present invention relates to a position sensor system and a method for detecting an error in a position sensor system. The position sensor system comprises: a position sensor having a first and a second sensor output; a first signal processing unit for processing a signal of the first or second sensor output; a second signal processing unit for processing a signal of the second or first sensor output; 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.

Description

Technical Field

[0001] The present invention relates to a position sensor system, in particular to a position sensor system for detecting a rotational movement. The present invention also relates to a method for detecting an error in a position sensor system, in particular to a method for detecting a rotational movement. Background Art

[0002] A position sensor system, in particular for detecting a rotational movement, comprises a position sensor, in particular for detecting a rotational movement of an object to be measured. The object to be measured is, for example, a rotor in an electric motor.

[0003] Position sensors provide raw sensor data in the form of sinusoidal signals, where one period of the sensor signal represents a full revolution or a portion of a full revolution of the measured object.

[0004] To improve signal quality and allow for unambiguous position calculations 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.

[0005] The first sensor signal is provided by the first sensor output and the second sensor signal is provided by the second sensor output.

[0006] 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 signals are amplified and filtered by the signal processing unit. In practice, such a signal path of the position sensor system may contain errors, which can be categorized as offset errors, gain mismatch errors, and phase errors.

[0007] Offset error is a shift of one or both sensor signals in the voltage domain in the positive or negative direction. Gain mismatch error is the different gains of the sine and cosine signal paths, while phase error is a phase shift between the two sensor signals that is below or above the nominal 90°.

[0008] 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, for example comprising 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.

[0009] 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.11The sine signal and cosine signal of the position sensor are processed in sequence by the signal processing unit, that is, amplified and filtered, and then transmitted to the electronic control unit.

[0010] The electronic control unit must provide a control signal to the multiplexer of the signal processing unit in order to distinguish which signal is being selected by the multiplexer. The advantage of this variant is that both position sensor signals, namely the sine signal and the cosine signal, are processed (amplified and filtered) by the same signal processing unit. Therefore, there is no gain mismatch because both are processed by the same signal processing unit, i.e. by the same amplifier. Likewise, any parasitic phase shift will be the same for the two position sensor signals, except for the inherent 90° phase shift between the sine signal and the cosine signal introduced by the signal processing unit. The offset error cannot be eliminated by this variant, however, the two 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 the two signals. The 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, because 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 because the error increases with the rotation speed. Another disadvantage of this variant is the need for a feedback of the multiplexer from the electronic control unit to the signal processing unit, which requires an additional signal line, which is why this variant is usually used for position sensor systems in which the electronic control unit is on the same chip as the position sensor system.

[0011] According to another variant of the prior art, the sine and cosine signals of the position sensor 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 output of a signal processing unit.

[0012] The electronic control unit can process the two position sensor outputs in parallel by two analog-to-digital converters, which forward the digital signals to a common digital signal processing unit. However, there will be nonlinear differences in the two analog-to-digital converters.

[0013] Alternatively, the outputs of the two position sensor systems can be processed by a control unit with a multiplexed analog-to-digital converter. The multiplexer is part of the control unit, which has full control of the multiplexer and is usually located on the same chip. The limiting factor of this variant is the processing speed of the control unit, in particular the processing speed 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 the non-linear differences are eliminated by using only one analog-to-digital converter. Summary of the invention

[0014] The object of the present invention is to detect any gain, offset and phase mismatch of a position sensor system comprising two signal processing units for parallel processing of sine and cosine signals of the position sensor, in particular for high-speed position sensor systems.

[0015] According to the invention, this object is solved by a position sensor system, in particular for detecting rotational movements, comprising:

[0016] a position sensor, in particular for detecting a rotational movement, the position sensor having a first sensor output and a second sensor output,

[0017] a first signal processing unit, configured to process a signal output by the first sensor or the second sensor, and in particular to amplify and filter the signal output by the first sensor or the second sensor,

[0018] a second signal processing unit, for processing the signal output by the second sensor or the first sensor, in particular for amplifying and filtering the signal output by the second sensor or the first sensor,

[0019] a first system output providing an output of the first signal processing unit or the second signal processing unit, and

[0020] The second system output provides the output of the second signal processing unit or the first signal processing unit,

[0021] Features

[0022] The position sensor system also includes a switching unit, which is used 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, and vice versa.

[0023] The position sensor system according to the invention has a first operating condition, wherein 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 wherein 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 used 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 is used 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 the 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 and then back to the first operating condition, and so on.

[0024] The position sensor signals are processed alternately by the first signal processing unit and the second signal processing unit 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. By detecting any difference between the processing performed by the first signal processing unit and the processing performed 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 fluctuations on the outputs of the first signal processing unit and the second processing unit. In addition, the position sensor system allows for fast error detection at low rotational speeds or at a static position of the position sensor.

[0025] Furthermore, gain mismatches may be compensated by averaging the swapped and unswapped signals, ie averaging the signal for a specific position sensor processed by the first signal processing unit and the signal processed by the second processing unit.

[0026] Preferably, the switching unit switches the first signal processing unit and the second processing unit, ie switches regularly, preferably at equal intervals, between the first operating condition and the second operating condition.

[0027] 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 a first sensor signal and a second sensor signal are referred to as a sine signal and a cosine signal, respectively. However, the invention is not limited to sinusoidal sensor signals and / or a phase shift of a quarter phase or 90 electrical degrees.

[0028] According to a variation of the present invention, the first signal processing unit and the second signal processing unit each include an amplifier and a filter for amplifying and filtering the first sensor output and the second sensor output.

[0029] 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 be on the same chip or on a different chip than the position sensor system.

[0030] According to a variant of the invention, the control unit comprises a first analog-to-digital converter for the first system output, a second analog-to-digital converter for the second system output 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 some non-linear differences may be added due to the two analog-to-digital converters.

[0031] 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 the output of the multiplexer, and a digital signal processing unit for processing the signals of the common analog-to-digital converter. This variant is limited by the processing speed of the analog-to-digital converter. Since the multiplexer and the control unit controlling the multiplexer are usually 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.

[0032] In either alternative, due to current processing speeds and available multi-core processors, the digital signal processing unit is generally not processing speed limited.

[0033] The control unit is particularly designed to detect fluctuations in the first system output and / or the second system output caused by the exchange of the first signal processing unit and the second signal processing unit, i.e. caused by the alternation between the first operating condition and the second operating condition. If there is any gain, offset and / or phase mismatch, the first system output and the second system output will change at the same time as the exchange of the signal processing units. Such changes in the first system output and the second system output are called fluctuations, which are detected by the control unit. If the exchange occurs at regular intervals, the fluctuations will also change at these intervals.

[0034] According to the invention, the position sensor is mounted on a non-moving part of the object to be measured.

[0035] According to a variant of the invention, the control unit also determines the magnitude of fluctuations in the first system output and / or the second system output. This helps to measure and differentiate any offset errors, gain mismatch errors and phase errors.

[0036] 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 represents an error in the first signal processing unit and in the second signal processing unit, respectively. The fluctuation determination is adversely affected by the case where the object to be measured is rotating during the fluctuation determination and / or by signal noise in the first signal processing unit, the second signal processing unit. By determining the second derivatives of the first system output and the second system output representing their respective accelerations, improved results can be obtained. Since the rate of change in the exchange step, i.e. the rate of change of the switch between the first operating condition and the second operating condition, is much faster than a typical rotational movement of the object to be measured, these situations can be easily distinguished. Likewise, the exchange step can be easily distinguished from the noise that usually occurs in analog signal processing.

[0037] In a variant of the invention, the control unit calculates an average value of the respective first system output and second system output. By determining the average value of the system output signals, any gain mismatch errors 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 over the entire signal period and any offset error can be reduced.

[0038] 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.

[0039] The position sensor system may comprise 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 more than two position sensors, position sensors providing signals with errors can be more easily detected.

[0040] 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, the method comprising:

[0041] a first operating condition, wherein the first sensor output is processed by a first signal processing unit and provided to a first system output, and wherein the second sensor output is processed by a second signal processing unit and provided to a second system output, and

[0042] 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,

[0043] And also includes the step of alternating between the first operating condition and the second operating condition.

[0044] 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 exchanging 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 condition and the second operating condition are alternated.

[0045] By detecting any differences between the processing performed by the first signal processing unit and the processing performed 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 fluctuations on the outputs 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 a static position of the position sensor.

[0046] In a preferred variation of the invention, the first sensor output provides a sine signal and the second sensor output provides a cosine signal, which is phase-shifted to a quarter phase or 90 electrical degrees. Such a first sensor signal and a second sensor signal are referred to as a sine signal and a cosine signal, respectively. However, the invention is not limited to sinusoidal sensor signals and / or a phase shift of a quarter phase or 90 electrical degrees.

[0047] According to a variation of the invention, the first signal processing unit and the second signal processing unit both amplify and filter the first sensor output or the second sensor output depending on the current operating conditions. Therefore, the first signal processing unit and the second signal processing unit both comprise an amplifier and a filter.

[0048] According to a particularly preferred variant of the invention, the first system output and the second system output are processed by a control unit.The control unit may be internal or external and in particular on the same chip as the position sensor system or on a different chip.

[0049] In a variant of the invention, the first system output is converted by a first analog-to-digital converter of the control unit, while 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 some nonlinear differences may be added due to the two analog-to-digital converters.

[0050] Alternatively, the control unit multiplexes between the first system output and the second system output and converts the multiplexed signal by a common analog-to-digital converter. This variant is limited by the processing speed of the analog-to-digital converter. Since the multiplexer and the control unit controlling the multiplexer are usually 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.

[0051] Advantageously, the signals of the first analog-to-digital converter and the second analog-to-digital converter or the signal of the common analog-to-digital converter are processed by a digital signal processing unit.Due to current processing speeds and available multi-core processors, the digital signal processing unit is usually not limited in processing speed.

[0052] According to a variant of the invention, the method comprises the step of determining, for a static position sensor, fluctuations in the first system output and / or in the second system output over time and / or over the position of the sensor.

[0053] 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 differentiate any offset errors, gain mismatch errors and phase errors.

[0054] According to a particularly preferred variant of the invention, the method comprises the steps of calculating second-order derivatives of the first system output and the second system output and detecting 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. By determining the second-order derivatives of the first system output and the second system output representing their respective accelerations, improved results can be obtained. Since the rate of change in the exchange step, i.e. the rate of change of the switch between the first operating condition and the second operating condition, is much faster than a typical rotational movement of the object to be measured, these conditions can be easily distinguished. Likewise, the exchange step can be easily distinguished from noise that usually occurs in analog signal processing.

[0055] According to a variant of the invention, the method comprises the step of determining an average value of the first system output and the second system output. By determining the average value of the system output signals, any gain mismatch errors 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 over the entire signal period and any offset error can be reduced.

[0056] Preferably, the step of alternating between the first operating condition and the second operating condition is performed regularly, preferably at equal intervals. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In the following, the invention will be further explained with reference to the embodiments shown in the accompanying drawings. The accompanying drawings show:

[0058] Figure 1a is a block diagram of a position sensor system according to a first embodiment of the present invention under a first operating condition,

[0059] Figure 1b Under the second operating condition Figure 1a Block diagram of the position sensor system,

[0060] Figure 2a Block diagram of a position sensor system according to a second embodiment of the present invention under a first operating condition,

[0061] Figure 2b Under the second operating condition Figure 2a Block diagram of the position sensor system,

[0062] Figure 3 Block diagram of a position sensor system according to a third embodiment of the present invention under a first operating condition,

[0063] Figure 4 is a diagram showing the output signal of a position sensor system with no error in the exchange of the signal path,

[0064] Figure 5a is a diagram showing the output signal of an exchanged position sensor system with an offset error,

[0065] Figure 5b It shows that the time Figure 5a A plot of the offset error of the static position sensor output,

[0066] Figure 5c It is shown Figure 5a A graph of the signal offset error at position and the magnitude of the offset error at position,

[0067] Figure 5d It is shown Figure 5a A graph of the total error and total average error of the signal in position,

[0068] Figure 6a is a diagram showing an output signal of a position sensor system with an exchange of amplitude errors,

[0069] Figure 6b It shows that the time Figure 6a A plot of the amplitude error of the static position sensor output,

[0070] Figure 6c It is shown Figure 6a A graph of the amplitude error of the signal at the location and the magnitude of the amplitude error at the location,

[0071] Figure 6d It is shown Figure 6a A graph of the total error in position and the total average error in position of the signal,

[0072] Figure 7a is a diagram showing the output signal of a position sensor system with an exchange of phase errors,

[0073] Figure 7b It shows that the time Figure 7a A plot of the phase error of the static position sensor output,

[0074] Figure 7c It is shown Figure 7a A graph of the phase error of the signal at the position and the magnitude of the phase error at the position,

[0075] Figure 7d It is shown Figure 7a A graph of the total error in position and the total average error in position of the signal,

[0076] Figure 8a is a graph showing the second derivative of an output signal for a position sensor system having an offset error in position,

[0077] Figure 8b It is shown Figure 8a A plot of the magnitude of a signal over time,

[0078] Figure 9a is a diagram showing the second derivative of an output signal for a position sensor system having an amplitude error in position,

[0079] Figure 9b It is shown Figure 9a A plot of the magnitude of a signal over time,

[0080] Fig.10a is a diagram showing the second derivative of the output signal for a position sensor system having a phase error in position,

[0081] Fig.10b It is shown Fig.10a A plot of the magnitude of the signal over time, and

[0082] Fig.11 is a block diagram of a position sensor system according to the prior art. DETAILED DESCRIPTION

[0083] Figure 1a A block diagram of a first embodiment of a position sensor system 1 is shown, which is particularly used for detecting a rotational movement under a first operating condition. The position sensor system 1 comprises a position sensor 2, which is particularly used for detecting a rotational movement and has 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, a signal 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, a signal of the second sensor output 4 or the first sensor 3.

[0084] The first sensor output 3 and the second sensor output 4 are processed once each by the first signal processing unit 5 or the second signal processing unit 6. Therefore, 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.

[0085] 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. Likewise, at a given time, the output of the first signal processing unit 5 is provided by 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. Therefore, 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.

[0086] According to the present invention, the position sensor system 1 further comprises a switching unit 9 for switching 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 for switching 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 at the same time, and vice versa. Figure 1a In FIG. 1 , the exchange unit 9 is identified by two dotted circles, one between the position sensor 2 and the signal processing units 5 , 6 , and the other between the signal processing units 5 , 6 and the system outputs 7 , 8 , ie at the two locations where the exchange occurs.

[0087] exist Figure 1a Under the first operating condition, the first sensor output 3 is connected to the first signal processing unit 5, and the output of the first signal processing unit 5 is connected to the first system output 7. Therefore, the second sensor output 4 is connected to the second signal processing unit 6, and the output of the second signal processing unit 6 is connected to the second system output 8.

[0088] 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). Figure 1a As indicated by corresponding arrows in FIG. 5 , 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.

[0089] Figure 1a The position sensor system 1 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. As indicated by the connection points and lines between the position sensor system 1 and the control unit 10, Figure 1a This is an external control unit 10 .

[0090] Figure 1a The control unit 10 in the embodiment 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 analog-to-digital converter 13 and the second analog-to-digital converter 14 are processed by the same digital signal processing unit 15.

[0091] 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 swapping the first signal processing unit 5 and the second signal processing unit 6 .

[0092] Furthermore, the control unit 10 , in particular the digital signal processing unit 15 , is designed to determine the size of the fluctuations 18 in the first system output 7 and in the second system output 8 .

[0093] 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, can determine the second-order derivatives of the first system output 7 and the second system output 8 and detect peaks in the second-order derivatives. The peaks respectively represent errors in the first signal processing unit 5 and in the second signal processing unit 6, in particular offset, gain and / or phase errors.

[0094] 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 value of the first system output 7 and the second system output 8 accordingly.

[0095] Figure 1b shows the second operating condition Figure 1a Block diagram of a position sensor system 1. 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. In addition, the second sensor output 4 is connected to the first signal processing unit 5, while the first signal processing unit 5 is connected to the second system output 8. Therefore, 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 switching the signal processing units 5, 6, the switching unit 9 changes the operating condition of the position sensor system 1.

[0096] Since the sensor outputs 3 , 4 are processed by different signal processing units 5 , 6 in the two operating conditions and since the different signal processing units 5 , 6 may have different offset, gain and / or phase errors, the system outputs 7 , 8 may contain fluctuations 18 which are detected by the control unit 10 .

[0097] exist Figure 1b In FIG. 1 , the switching unit 9 is likewise indicated by two dashed circles. The switching of the signal processing units 5 , 6 is indicated by the intersection of the two dashed circles.

[0098] exist Figure 1a Under the first operating condition shown in , 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 .

[0099] exist Figure 1b Under the second operating condition shown in , 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 .

[0100] The exchange unit 8 causes an alternation between the first operating condition and the second operating condition.

[0101] The first signal processing unit 5 and the second processing unit 6 amplify and filter the first sensor output 3 and the second sensor output 4, thereby ultimately increasing an offset error, a gain error and / or a phase error.

[0102] The first system output 7 and the second system output 8 are processed by the control unit 10. The first system output 7 is converted by the first analog-to-digital converter 13 of the control unit 10, and the second system output 8 is converted by the second analog-to-digital converter 14 of the control unit 10. The digital signal processing unit 15 of the control unit 10 processes the signals of the first analog-to-digital converter 10 and the second analog-to-digital converter 14.

[0103] The control unit 10 detects fluctuations 18 in the first system output 7 and / or the second system output 8, which fluctuations 18 are caused by alternating between the first operating condition and the second operating condition, i.e. by processing the sensor output signals 3, 4 by different signal processing units 5, 6 under the two operating conditions.

[0104] By determining the magnitude of the fluctuation 18 in the first system output 7 and the second system output 8, the control unit 8 can determine the kind of error, ie, an offset error, a gain error and / or a phase error.

[0105] The accuracy of error detection can be enhanced by calculating the second derivatives of the first system output 7 and the second system output 8 and detecting the peaks in the calculated second derivatives. The peaks represent the errors in the first signal processing unit 5 and the second signal processing unit 6, respectively.

[0106] By determining an average value of the first system output 7 and the second system output 8, errors can be reduced or even compensated.

[0107] Advantageously, the exchange unit 9 exchanges the first signal processing unit 5 and the second signal processing unit 6 regularly, preferably at equal intervals.

[0108] Figure 2a and Figure 2b 1 and 2 show a block diagram of a position sensor system 1 under a first operating condition and a second operating condition, respectively, according to a second embodiment of the present invention. Figure 2a and Figure 2b The second embodiment of the position sensor system 1 shown in FIG. Figure 1a and Figure 1b The first embodiment of the position sensor system 1 shown in FIG. 1 is different in that the control unit 10 comprises only a common analog-to-digital converter 17, instead of the first analog-to-digital converter 13 and the second analog-to-digital converter 18. In order to process 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 signal currently received from the common analog-to-digital converter 17 to the first system output 7 and the second system output 8, respectively.

[0109] Figure 3 The third embodiment of a position sensor system 1 according to the invention is shown in a first operating condition. Figure 3 The third embodiment of Figure 1a and Figure 1b The difference from the first embodiment is that the control unit 10 is an internal control unit 10 . Therefore, the first system output 7 and the second system output 8 are inside the position sensor system 1 .

[0110] Since all other features correspond to Figure 1a and Figure 1b The first embodiment is not shown in the second operating condition, so the third embodiment is not shown. In addition, the internal control unit 15 can also be used accordingly. Figure 2a and Figure 2b The second embodiment of the invention.

[0111] Figure 4 Exemplary outputs of the first sensor output 3 and the second sensor output 4 in an error-free situation are shown, wherein there is no offset between the sine signal 20 and the cosine signal 21 , there is an ideal amplitude match and an ideal 90° phase shift, thereby causing no switching fluctuations. Figure 4 The horizontal axis represents the mechanical rotation, in this case 360°, and the vertical axis represents the signal level of the first sensor output 3 and the second sensor output 4. In this case, the maximum signal level is 1,0.

[0112] The first sensor output 3 provides a sinusoidal signal which starts at a signal level of 0 at 0°. The sinusoidal signal of the first sensor output 3 is referred to as the sinusoidal signal 20. The second sensor output 4 also provides a sinusoidal signal which is phase-shifted by a quarter phase of 90°. Therefore, the signal level of the second sensor output 4 is 1,0 at 0°. The sinusoidal signal of the second sensor output is referred to as the cosine signal 21.

[0113] The first sensor output is defined as:

[0114] [x is degrees], or

[0115] A*sin(X)[x is radians]

[0116] The second sensor output is defined as:

[0117] or [x is degrees], or

[0118] Or A*cos(X) [x is radians].

[0119] exist Figure 4 The corresponding peak amplitude for signal level A is 1,0.

[0120] Figure 5a An error situation is shown in which the second signal processing unit 6 has an offset error of 10% relative to the maximum signal amplitude 1,0. Figure 5a The corresponding sine signal 22 and cosine signal 23 of the first system output 7 and the second system output 8 are shown, respectively, with offset errors over all phases (0° to 360°).

[0121] Figure 5b shows that in the time domain Figure 5a The output of the static sensor at 120° of 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 (switched and not switched) is visible as a rectangular signal, flipping between two signal levels. This rectangular signal is called fluctuation 18. The fluctuation of the switched sine signal 22 is indicated by the number 28, while the fluctuation of the switched cosine signal 23 is indicated by the number 29. In addition, Figure 5b The average value of the fluctuation 28 of the commutated sine signal 22 and the fluctuation 29 of the commutated cosine signal 23 is shown.

[0122] Figure 5c Shows Figure 5a The offset error of the sine signal 22 and the cosine signal 23, and the magnitude of the two signals at all phases (0° to 360°) An indication of an offset error is that the errors in the sine signal 22 and the cosine signal 23 are constant and equal at any position.

[0123] Figure 5d The total error calculated from the unswitched signal 31 and the swapped signal 30 and the average total error are shown at the first system output 7 and the second system output 8. By averaging the errors of the unswitched signal 31 and the swapped signal 30, the total offset error can be reduced.

[0124] Figure 6a An error situation is shown in which the second signal processing unit has a gain error of 10% relative to the maximum signal amplitude of 1.0. Figure 6a Correspondingly, the sine signal 24 and the cosine signal 25 of the first system output 7 and the second system output 8 are shown with gain errors over all phases (0° to 360°).

[0125] Figure 6b shows the time domain at Figure 6a The output of the static sensor at 120° of 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 (switched and not switched) is visible as a rectangular signal, flipping between two signal levels. This rectangular signal is called fluctuation 18. The fluctuation of the switched sine signal 24 is indicated by the number 28, while the fluctuation of the switched cosine signal 25 is indicated by the number 29. In addition, Figure 6b The average value of the fluctuation 28 of the commutated sine signal 24 and the fluctuation 29 of the commutated cosine signal 25 is shown.

[0126] from Figure 6a and Figure 6b It can be seen that the maximum fluctuations 18 occur at the signal peaks, whereas the minimum fluctuations 18 occur at the zero crossings of each signal 28 , 29 .

[0127] Figure 6c Shows Figure 6a The gain error of the sine signal 24 and the cosine signal 25, and the magnitude of the two signals at full phase (0° to 360°) The maximum errors of the sine signal 24 and the cosine signal 25 occur at the positive and negative peaks, respectively (90°, 270° for the sine signal 24, 0°, 180° for the cosine signal 25), while the minimum errors occur at the zero crossings (0°, 180° for the sine signal 24, 90°, 270° for the cosine signal 25). An indication of the gain error is that the errors of the sine signal 24 and the cosine signal 25 are not constant over all phases, but the magnitudes of the two signals are constant.

[0128] Figure 6d The total error and the average total error calculated from the unswitched signal 31 and the switched signal 30 at the first system output 7 and the second system output 8 are shown. By averaging the errors of the unswitched signal 31 and the switched signal 30, the total amplitude error can be eliminated.

[0129] Figure 7a An error situation is shown in which the second signal processing unit has a phase shift error of 6° compared to the first signal processing unit. Figure 7aCorrespondingly, the sine signal 26 and the cosine signal 27 of the first system output 7 and the second system output 8 with phase shift errors over all phases (0° to 360°) are shown.

[0130] Figure 7b shows the time domain at Figure 7a The output of the static sensor at 120° of 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 (switched and not switched) is visible as a rectangular signal, flipping between two signal levels. This rectangular signal is called fluctuation 18. The fluctuation of the switched sine signal 26 is indicated by the number 28, while the fluctuation of the switched cosine signal 27 is indicated by the number 29. In addition, Figure 7b The average value of the fluctuation 28 of the commutated sine signal 26 and the fluctuation 29 of the commutated cosine signal 27 is shown.

[0131] from Figure 7a and Figure 7b It can be seen that the maximum fluctuation occurs at the zero crossing and the minimum fluctuation occurs at the signal peak of each signal 26 , 27 .

[0132] Figure 7c Shows Figure 7a The phase shift error of the sine signal 26 and the cosine signal 27 and the magnitude of the two signals at all phases (0° to 360°) The maximum errors of the sine signal 26 and the cosine signal 27 occur at the zero crossings (0°, 180° for the sine signal 26, 90°, 270° for the cosine signal 27), respectively, and the minimum errors occur at the positive and negative peaks (90°, 270° for the sine signal 26, 0°, 180° for the cosine signal 27). An indication of a phase shift error is that the errors of the sine signal 26 and the cosine signal 27 are not constant over all phases, but the magnitudes of the two signals are constant.

[0133] Figure 7d The total error and the average total error calculated from the unswitched signal 31 and the swapped signal 30 at the first system output 7 and the second system output 8 are shown. By averaging the errors of the unswitched signal 31 and the swapped signal 30, the total phase shift error can be reduced to a constant level over all phases.

[0134] Figure 8a shows the reference offset error Figure 5a The second-order derivatives of the sine signal 22 and the cosine signal 23. Figure 8b Shows Figure 8a The magnitude of the second derivative of Due to the overlap of the second-order derivative of the sine signal 22 and the second-order derivative of the cosine signal 23, Figure 8ais divided into two graphs.

[0135] The vertical axis on both graphs is a relative number representing the second derivative of the signal. It depends on the time interval between the measurements of the signal fluctuations 18 on the sine signal 22 and the cosine signal 24 and represents the sampling rate of the analog-to-digital converters 13, 14, 17 analyzing the sine signal 22 and the cosine signal 23. The greater the error, the greater these signal levels will be. Figure 8a The horizontal axis represents the position of the position sensor 2 in electrical degrees, and Figure 8b The horizontal axis is a relative number representing 20 exchange cycles (10 exchange cycles).

[0136] An offset error in the first signal processing unit 5 and / or the second signal processing unit 6 is indicated by a second order derivative pulse which is constant in position. The second order derivative magnitude is also constant in position.

[0137] Figure 9a shows the reference gain error of Figure 6a The second-order derivatives of the sine signal 24 and the cosine signal 25 . Figure 9b Shows Figure 9a The magnitude of the second derivative of Since the second-order derivative of the sine signal 24 and the second-order derivative of the cosine signal 25 partially overlap, Figure 9a is divided into two graphs.

[0138] Figure 9a and Figure 9b The diagrams are also especially about the axis corresponding to Figure 8a and Figure 8b .

[0139] Gain errors in the first signal processing unit 5 and / or the second signal processing unit 6 are indicated by a non-constant second order derivative peak pulse pattern in position. The second order derivative magnitude is constant in position and time.

[0140] Fig.10a shows the reference phase shift error Figure 7a The second-order derivatives of the sine signal 26 and the cosine signal 27. Fig.10b Shows Fig.10a The magnitude of the second derivative of Due to the partial overlap of the second-order derivative of the sine signal 22 and the second-order derivative of the cosine signal 23, Fig.10a is divided into two graphs.

[0141] Fig.10a and Fig.10b The diagrams are also especially about the axis corresponding to Figure 8a and Figure 8b .

[0142] Phase shift errors in the first signal processing unit 5 and / or the second signal processing unit 6 are indicated by a second order derivative peak pulse pattern that is non-constant in position. The second order derivative magnitude is constant in position and time.

[0143] Fig.11 A block diagram of a position sensor system 1 according to the prior art is shown. 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 the signals of the first sensor output 3 and the second sensor output 4, in particular amplifying and filtering them.

[0144] The signal processing unit 32 comprises a multiplexer 34 for multiplexing 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.

[0145] The position sensor system 1 comprises a system output 33 which provides an output of the signal processing unit 32 .

[0146] Fig.11 The position sensor system 1 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. As indicated by the connection points and lines between the position sensor system 1 and the control unit 10, Fig.11 This involves an external control unit 10 .

[0147] Fig.11 The control unit 10 in the embodiment comprises an analog-to-digital converter 17 for the system output 33. The output of the analog-to-digital converter 17 is processed by a digital signal processing unit 15.

[0148] The control unit 10, in particular the digital signal processing unit 15, must know which sensor output 3, 4 is currently being processed by the signal processing unit 32. Therefore, the control unit 10, in particular the digital signal processing unit 15, 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 a rotary position sensor system 1, due to the sequential processing of the two signals, the two position sensor signals will not be measured at the same position, because 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, because this error increases with the rotation speed.

[0149] Reference mark

[0150] 1 Position sensor system

[0151] 2 Position Sensor

[0152] 3 First sensor output

[0153] 4 Second sensor output

[0154] 5. First signal processing unit

[0155] 6 Second signal processing unit

[0156] 7 First system output

[0157] 8 Second system output

[0158] 9 Exchange Unit

[0159] 10 Control unit

[0160] 11 Amplifier

[0161] 12 Filters

[0162] 13. First analog-to-digital converter

[0163] 14 Second analog-to-digital converter

[0164] 15 Digital Signal Processing Unit

[0165] 16 Multiplexer

[0166] 17 Shared ADC

[0167] 18 Fluctuations on a sinusoidal signal

[0168] 19 Signal peaks of the second derivatives of sine and cosine signals

[0169] 20 Error-free commutated sinusoidal signal (first sensor output)

[0170] 21 Error-free exchanged cosine signal (second sensor output)

[0171] 22 Interleaved sine signal (with offset error)

[0172] 23 Swapped cosine signal (with offset error)

[0173] 24 Interleaved sine signal (with gain error)

[0174] 25 Swapped cosine signal (with gain error)

[0175] 26 Interleaved sinusoidal signals (with phase shift error)

[0176] 27 Interchangeable cosine signal (with phase shift error)

[0177] 28 Wave switching sine signal

[0178] 29 Fluctuating cosine signal

[0179] 30 Error exchange signal

[0180] 31 Error not exchanged signal

[0181] 32 Signal Processing Unit

[0182] 33 System Output

[0183] 34 Multiplexer signal processing unit

[0184] 35 Control lines for multiplexers of signal processing unit

Claims

1. A position sensor system (1), in particular for detecting a rotational movement, comprising: a position sensor (2), the position sensor (2) being particularly used 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), Features The position sensor system (1) further comprises a switching unit (9) for switching 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 for simultaneously switching 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. The position sensor system (1) further comprises a control unit (10) for processing the first system output (7) and the second system output (8), wherein the control unit (10) determines second-order derivatives of the first system output (7) and the second system output (8), and detects peak values ​​(19) in the calculated second-order derivatives, the peak values ​​(19) representing errors in the first signal processing unit (5) and in the second signal processing unit (6), respectively.

2. The position sensor system (1) according to claim 1, The control unit comprises: 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 the signals of the first analog-to-digital converter (13) and the second analog-to-digital converter (14).

3. The position sensor system (1) according to claim 1, 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 the output of the multiplexer (16), and a digital signal processing unit (15) for processing the signal of the common analog-to-digital converter (17).

4. The position sensor system (1) according to any one of claims 1 to 3, The control unit (10) detects fluctuations (18) in the first system output (7) and / or the second system output (8) caused by swapping the first signal processing unit (5) and the second signal processing unit (6).

5. The position sensor system (1) according to claim 4, The control unit (10) further determines the magnitude of fluctuations (18) in the first system output (7) and the second system output (8).

6. The position sensor system (1) according to claim 5, The control unit (10) accordingly calculates an average value of the first system output (7) and the second system output (8).

7. A method for detecting errors in a position sensor system (1), in particular for detecting rotational movements, the method comprising: a first operating condition, wherein the first sensor output (3) is processed by a first signal processing unit (5) and provided to a first system output (7), and wherein the 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, The first system output (3) and the second system output (4) are processed by a control unit (10), and the method comprises the steps of calculating second-order derivatives of the first system output (7) and the second system output (8), and detecting peak values ​​(19) in the calculated second-order derivatives, the peak values ​​correspondingly representing errors in the first signal processing unit (5) and in the second signal processing unit (6).

8. The method according to claim 7, 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 the control unit (10) multiplexes between the first system output (7) and the second system output (8), and converts the multiplexed signal by a common analog-to-digital converter (17).

9. The method according to any one of claims 7 to 8, Comprising the steps of: 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 the position of the sensor.

10. The method according to claim 9, The method comprises the steps of: determining the magnitude of the fluctuation (18) in the first system output (7) and the second system output (8).

11. The method according to claim 7, The method comprises the steps of: determining an average value of the first system output (7) and the second system output (8).

Images