Sine wave oscillator and inductive sensors

Abstract

A sine wave oscillator for an inductive sensor system is disclosed. The sine wave oscillator comprises a decoupler and a low-pass filter, wherein the decoupler is configured to provide a pulse width modulated signal as a decoupled signal at one output of the decoupler. One input of the low-pass filter is connected to the output of the decoupler. The low-pass filter is configured to provide a sinusoidal signal for the inductive sensor system by using the inverted signal at an output of the low-pass filter. The sine wave oscillator further comprises a microcontroller that is designed to provide the pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at one pin of the microcontroller.

Claims

1. A sine wave oscillator for an inductive sensor system, the sine wave oscillator comprising: a decoupler and a low-pass filter, wherein the decoupler is configured to provide a pulse width modulated signal as a decoupled signal at one output of the decoupler, wherein one input of the low-pass filter is connected to the output of the decoupler, and wherein the low-pass filter is configured to provide a sinusoidal signal for the inductive sensor system by using the decoupled signal at one output of the low-pass filter, wherein a microcontroller is designed to provide the pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at one pin of the microcontroller.

2. The sine wave oscillator according to claim 1, wherein the low-pass filter is configured as an analog low-pass filter of the third order.

3. The sine wave oscillator according to claim 2, wherein the low-pass filter comprises at least one resistor, one inductive element, and at least two capacitances.

4. The sine wave oscillator according to claim 3, wherein the inductive element is a coil.

5. The sine wave oscillator according to claim 1, wherein a resistor is arranged between the pin of the microcontroller and the input of the decoupler.

6. The sine wave oscillator according to claim 1, wherein the decoupler is a buffer.

7. The sine wave oscillator according to claim 1, wherein the decoupler is an inverter.

8. The sine wave oscillator according to claim 1, wherein an input of the decoupler is connected to the pin of the microcontroller.

9. The sine wave oscillator according to claim 1, wherein the sine wave oscillator does not include a gate oscillator.

10. An inductive sensor system comprising: a plurality of coils that are arranged in series, at least one damping element which is moveable over the coils, a control unit, which is adapted to control the coils by using a sinusoidal signal and to determine a position of the damping element in relation to the coils, and a sine wave oscillator configured to provide the sinusoidal signal, the sine wave oscillator comprising: a decoupler and a low-pass filter, wherein the decoupler is configured to provide a pulse width modulated signal as a decoupled signal at one output of the decoupler, wherein one input of the low-pass filter is connected to the output of the decoupler, and wherein the low-pass filter is configured to provide a sinusoidal signal for the inductive sensor system by using the decoupled signal at one output of the low-pass filter, wherein a microcontroller is designed to provide the pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at one pin of the microcontroller.

11. The inductive sensor system according to claim 10, wherein the microcontroller of the sine wave oscillator comprises the control unit.

12. The inductive sensor system according to claim 10, wherein the damping element can be moved over the coils in a straight way.

13. The inductive sensor system according to claim 10, wherein the microcontroller of the sine wave oscillator is configured to provide at least one digital signal for controlling the coils.

14. The inductive sensor system according to claim 10, wherein the microcontroller of the sine wave oscillator comprises an analog-digital converter, which is designed to digitize a converted current of the sine wave oscillator.

15. The inductive sensor system according to claim 10, wherein the microcontroller of the sine wave oscillator comprises an analog-digital converter, which is designed to digitize a rectified current of the sine wave oscillator.

16. The inductive sensor system according to claim 10, wherein the microcontroller of the sine wave oscillator comprises an analog-digital converter, which is designed to digitize a converted voltage of the sine wave oscillator.

17. The inductive sensor system according to claim 10, wherein the microcontroller of the sine wave oscillator comprises an analog-digital converter, which is designed to digitize a rectified voltage of the sine wave oscillator.

18. The inductive sensor system according to claim 10, wherein the damping element can be moved over the coils in an arc-shaped way.

19. A method for producing a sine wave oscillator, the method comprises the following steps: providing of a microcontroller, a decoupler and a low-pass filter; and arranging the microcontroller, the decoupler and the low-pass filter as a sine wave oscillator wherein the decoupler is configured to provide a pulse width modulated signal as a decoupled signal at one output of the decoupler, wherein one input of the low-pass filter is connected to the output of the decoupler, wherein the low-pass filter is configured to provide a sinusoidal signal for the inductive sensor system by using the decoupled signal at one output of the low-pass filter, and wherein the microcontroller is designed to provide the pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at one pin of the microcontroller.

20. A method for controlling an inductive sensor system, the inductive sensor system comprising a plurality of coils that are arranged in series, at least one damping element which is moveable over the coils, a control unit, which is adapted to control the coils by using a sinusoidal signal and to determine a position of the damping element in relation to the coils, and a sine wave oscillator configured to provide the sinusoidal signal, the sine wave oscillator comprising a decoupler and a low-pass filter, wherein the decoupler is configured to provide a pulse width modulated signal as a decoupled signal at one output of the decoupler, wherein one input of the low-pass filter is connected to the output of the decoupler, and wherein the low-pass filter is configured to provide a sinusoidal signal for the inductive sensor system by using the decoupled signal at one output of the low-pass filter, wherein a microcontroller is designed to provide the pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at one pin of the microcontroller, the method comprises the following steps: providing a pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at one pin of the microcontroller of the sine wave oscillator; processing the pulse width modulated signal to a regulated sinusoidal signal as a HF current; determining the damping of the plurality of coils of the inductive sensor system by using the regulated sinusoidal signal; and evaluating the damping of the plurality of coils in order to determine a position of the damping element.

Description

(1) The disclosure will be explained in more detail by way of the exemplified drawings that are attached. It is depicted:

(2) FIG. 1 a block diagram of a sine wave oscillator in accordance with one embodiment of the present disclosure;

(3) FIG. 2 an equivalent circuit diagram of a sine wave oscillator in accordance with one embodiment of the present disclosure;

(4) FIG. 3 a schematic depiction of an inductive sensor system in accordance with one embodiment of the present disclosure;

(5) FIG. 4 a schematic depiction of an inductive sensor system in accordance with one embodiment of the present disclosure;

(6) FIG. 5 a flow chart of a method for producing a sine wave oscillator in accordance with one embodiment of the present disclosure; and

(7) FIG. 6 a flow chart of a method for operating an inductive sensor system in accordance with one embodiment of the present disclosure.

(8) In the following description of preferred embodiments of the present disclosure, the same or similar reference signs are used for similarly functioning components that are depicted in the different figures, whereby a repeated description of these components is omitted.

(9) FIG. 1 depicts a block diagram of a sine wave oscillator 100 in accordance with one embodiment of the present disclosure. The sine wave oscillator 100 is designed to provide a regulated sinusoidal signal for an inductive sensor system. The sine wave oscillator 100 comprises a microcontroller 110, a decoupler 120, as well as a low-pass filter 130. The microcontroller is designed to provide a pulse width modulated signal 140 with a predetermined frequency and a predetermined duty cycle at one pin of the microcontroller. The decoupler 120 is designed as an inverter. A signal 140 at one input of the decoupler 120 will be provided as inverted signal 150 at an output of the decoupler 120. The input of the decoupler 120 is connected to the pin of the microcontroller 110. The output of decoupler 120 is connected to the low-pass filter 130. A sinusoidal signal 160 for an inductive sensor system is provided at an output of low-pass filter 130.

(10) In one embodiment, low-pass filter 130 is configured as an analogue low-pass filter of the third order.

(11) In one embodiment, decoupler 120 is designed as a buffer, in particular as an inverter.

(12) One aspect of the present disclosure is a simplification of an electronic circuit. In comparison to the prior art, components can be reduced, which leads to a significant cost reduction.

(13) FIG. 2 depicts an equivalent circuit diagram of a sine wave oscillator in accordance with one embodiment of the present disclosure. The sine wave oscillator 100 can be an embodiment of the sine wave oscillator 100 which was depicted in FIG. 1. In the depicted embodiment, low-pass filter 130 is made up of at least one resistor R1, one inductive element L1, in particular a coil L1, as well as at least two capacitances C1, C2. The input of low-pass filter 130 is connected to resistor R1. Resistor R1 is connected to inductive element L1. Inductive element L1 is connected to the output of the low-pass filter. Capacitance C1 is connected to the ground and to the connection between resistor R1 and inductive element L1. Capacitance C2 is connected to the ground and to the connection between inductive element L1 and the output of the low-pass filter 130.

(14) In the embodiment, a resistor R is arranged between pin 200 of microcontroller 110 and the input of decoupler 120. Decoupler 120 is designed as an inverter.

(15) In comparison to existing concepts for a sine wave oscillator 100, one embodiment of the present disclosure can function without a gate oscillator with inverter for generating a square wave signal 140 (oscillator resonator) with a high and stable amplitude. Decoupler 120 serves as an additional inverter for decoupling. Low-pass filter 130 filters out the sine waves 160 (carrier) and suppresses harmonics. Thus, a high amplitude stability can be achieved, since variations of the resonator are not carried over into the signal of the measuring coil. An amplitude-stable signal is provided at the output of the gate oscillator (5V square wave signal). The coupled-out sinusoidal signal is independent of the amplitude on the resonator, since decoupler 120 relieves the square wave generator.

(16) Due to the ever increasing speeds of microcontrollers (C) 110 and clock generators by means of an internal PLL or phase control loop, it is no problem to output frequencies in the megahertz range in form of a pulse width modulated signal 140 or PWM at the port pins. Since each inductive sensor system uses a microcontroller 110 for the evaluation of the signals, an embodiment uses the clock of the microcontroller 110. The pulse width modulated signal (PWM) 140 that was produced by the microcontroller 110 is supplied before the decoupler 120 for decoupling. As a result, costs are reduced significantly.

(17) FIG. 3 shows a schematic depiction of an inductive sensor system 300 in accordance with one embodiment of the present disclosure. The inductive sensor system 300 features a sine wave oscillator 100. The sine wave oscillator 100 can be an embodiment of one of the sine wave oscillators 100 that was depicted in FIG. 1 and FIG. 2. The inductive sensor system 100 comprises a plurality of coils 310 that are arranged in series, at least one damping element 320, which is arranged in such a way that it can be moved over the coils 310, a control unit 330, which is adapted to control the coils 310 and to determine a position of the damping element 320 in relation to the coils 310 as well as the sine wave oscillator 100.

(18) Depending on the embodiment, the coils 310 are arranged along a straight line or along a circular arc-shape. The damping element 320 can be moved over the coils 310 along a trajectory which is determined by the coil centers, whereby the inductive sensor system 300 is adapted to determine the position of the damping element 320 in relation to the coils 310.

(19) In one embodiment, damping element 320 has a diamond shape.

(20) In one embodiment, the coils 310 are arranged along a straight line. Damping element 320 can be moved over the coils 310 in a straight path. In another embodiment, the coils 310 are arranged along a circular arc and damping element 320 can be moved over the coils 310 in an arc-shaped path.

(21) In one embodiment, a microcontroller 110 assumes tasks to control the inductive sensor system 300 such as providing the pulse width modulated signal of the sine wave oscillator 100. Thus, in one embodiment, microcontroller 110 of the sine wave oscillator provides at least one digital signal for a controlling or evaluating of the coils. In one embodiment, microcontroller 110 of the sine wave oscillator consists of an analog-digital converter which digitizes a converted or rectified current or voltage of the sine wave oscillator 100. In an undisclosed embodiment, control unit 330 includes the microcontroller 110 of the sine wave oscillator 100. In this case, control unit 330 provides the pulse width modulated signal for the sine wave oscillator 100.

(22) FIG. 4 shows a schematic depiction of an inductive sensor system in accordance with one embodiment of the present disclosure. The inductive sensor system can be an embodiment of the inductive sensor system that was depicted in FIG. 3. Four coils 310, which are individually marked with the reference signs L1, L2, L3, L4, are arranged along a straight line. A diamond-shaped damping element 320 extends over the coils L1 and L2. Damping element 320 is designed in such a way that it can be moved over the coils 320 which are arranged in a straight line. A regulated sine wave oscillator 100 provides a sinusoidal signal 160. In the embodiment for example, sinusoidal signal 160 has a frequency of 12 MHz and can also be described as an HF current. Sinusoidal signal 160 is supplied to an amplifier and current-voltage converter 410, which directs the HF current or the sinusoidal signal 160 to the coils 310. At an output of the amplifier and the current-voltage converter 410, an HF output voltage 420 is produced and supplied to an HF rectifier 430. The HF rectifier 430 outputs the converted HF voltage 420 as a DC signal 440 with a level in the range from 0 to 5 V, which will be supplied to an analog-digital converter input of microcontroller 110.

(23) At one digital output of microcontroller 110, a corresponding digital signal 450 is supplied to a multiplexer 460 which is connected to the coils 310. The switchboards of multiplexer 460 are connected to ground 470. If a switching point of multiplexer 460 is closed, the corresponding coil 310 is connected to ground. The switchboard can also be arranged between current-voltage converter 410 and the coils 310.

(24) In an undisclosed embodiment, microcontroller 110 is connected to sine wave oscillator 100 and thus a functional part of sine wave oscillator 100 as well. Microcontroller 110 can thus provide a pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at one pin.

(25) FIG. 5 depicts a flow chart of a method 500 for producing a sine wave oscillator in accordance with one embodiment of the present disclosure. The sine wave oscillator can be an embodiment of the sine wave oscillator that was described in FIG. 1 or in FIG. 2. Method 500 comprises a step 510 for providing a microcontroller, a decoupler and a low-pass filter as well as a step 520 for arranging the microcontroller, the decoupler and the low-pass filter to an inductive sensor system.

(26) FIG. 6 depicts a flow chart of a method 600 for operating an inductive sensor system in accordance with one embodiment of the present disclosure. The inductive sensor system can be an embodiment of the inductive sensor system that was depicted in FIG. 3 or FIG. 4. Method 600 comprises a step 610 for providing a pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at a pin of a microcontroller of a sine wave oscillator, a step 620 for processing the pulse width modulated signal to a regulated sinusoidal signal as an HF current, a step 630 for determining the damping of the plurality of coils of the inductive sensor systems by using the regulated sinusoidal signal, as well as a step 640 for evaluating the damping of the plurality of coils in order to determine a position of the damping element.

(27) The embodiments described and shown in the figures are chosen only by way of example. Different embodiments may be combined in whole or in terms of individual features. It is also possible that an embodiment may be supplemented by features of another embodiment.

(28) Individual steps of the methods according to the disclosure may be repeated or also performed in a different sequence than in the described order.

(29) If an embodiment includes an and/or link between a first characteristic and a second characteristic, this can be understood in a way that the embodiment according to one version features both the first characteristic as well as the second characteristic and according to a further version, either only the first characteristic or only the second characteristic.

REFERENCE SIGN

(30) 100 Sine wave oscillator

(31) 110 Microcontroller

(32) 120 Decoupler

(33) 130 Low-pass filter

(34) 140 Pulse width modulated signal

(35) 150 Inverted signal

(36) 160 Sinusoidal signal

(37) R, R1 Resistor

(38) L1 Inductive element, coil

(39) C1, C2 Capacitance

(40) 300 Inductive sensor system

(41) 310 Coil

(42) 320 Damping element

(43) 330 Control unit

(44) 410 Amplifier and current-voltage converter

(45) 420 HF voltage

(46) 430 HF rectifier

(47) 440 DC voltage

(48) 450 Digital signal

(49) 460 Multiplexer

(50) 470 Ground

(51) 500 A method for producing

(52) 510 Step for providing

(53) 520 Step for arranging

(54) 600 Method for operating

(55) 610 Step for providing

(56) 620 Step for processing

(57) 630 Step for determining

(58) 640 Step for evaluating