DE202010018107U1 - Self-balancing stator antenna for optimized contactless energy transmission in near field telemetry systems - Google Patents

Abstract

Self-aligning stator antenna (1) for use for optimized contactless energy transfer in near-field telemetry systems from the stator to the rotor (30) - consisting of - a supply line (15) - an induction coil (2) - a matching network (4) - a power supply unit (10) characterized by the following features: a) a self-aligning stator antenna (1) b) with a compact and extremely acceleration-resistant digitally electronically adjustable adaptation network (4) c) with an additional adaptation detector (11) d) with an additional processor (7) e) the processor (7) the digital adjustable adaptation network (4) according to an algorithm based on the evaluation of the adaptation detector output signal (12) controls f) and micro-program that sets the adaptation network (4) so that the maximum available energy on the supply line (15) in the induction coil (2 ) possible optimally in a max. Magnetic field amplitude (20) is converted.

Description

Non-contact transmission systems in near field telemetry for the contactless transmission of sensor data from rotating shafts are already being used with great success today, as in the patent DE3922556 described. These systems consist of rotor electronics ( 28 ) (Sensor signal amplifier with integrated telemetry transmitter), a rotor antenna ( 29 ) and a stator antenna ( 1 ) and a receiver unit. Rotor electronics ( 28 ) and rotor antenna ( 29 ) are mounted on the moving or rotating shaft and require energy. The necessary energy for the rotor is usually contactless inductively from stator to rotor ( 30 ) transfer. The waveform is usually sinusoidal.

Many of these systems are used essentially for stress analysis, monitoring and qualification of moving mechanical components in confined spaces. For this purpose, suitable transmission elements, such as a stator antenna ( 1 ) and a rotor antenna ( 29 ) are each adapted to the respective installation conditions.

An essential feature of these maintenance-free systems is the non-contact energy transfer from the stator to the rotor ( 30 ) to ensure absolute freedom from maintenance and unrestricted availability. A battery supply to the rotor electronics does not meet this requirement. The efficiency of the contactless energy transfer depends on the optimal balancing of the stator antenna ( 1 ) and the rotor antenna ( 29 ). This also determines the available distance between the stator and rotor antenna, which can be bridged without contact. Although it is possible to achieve long distances in the meter range with battery operation with radio systems, here the contactless energy transfer to the rotor is missing. Furthermore, battery operated systems have great limitations in ambient temperature range, acceleration resistance and immunity to interference. For maintenance-free and reliable systems, contactless energy transfer is essential.

While the rotor antenna ( 29 ) is hardly influenced by ambient conditions - such as changing distances to metal walls - due to its enclosing character and short distance to the shaft, the adjustment of the stator antenna ( 1 ) is very much dependent on changing geometry ratios and changing component values over temperature and manufacturing dispersion. This occurs especially in side-output shaft and cardan shaft applications in vehicles. Here are the installation conditions very cramped and very different from vehicle to vehicle. Furthermore, especially the side shafts of automobiles due to the compression travel have a large range of motion in all three axes. The distances between a compact stator antenna ( 1 ) and the rotor antenna can reach up to 100 mm. These transmission distances are not technically feasible with a compact pickup with reasonable effort.

Such transmission distances are only with resonant circuits tuned to electrical resonance, ie a balanced loop antenna (induction coil (induction coil)). 2 )) according to 1 realizable. Unfortunately, the optimal matching point ( 24 ) of these loop antennas a high sensitivity to the installation situation. In fact, every stator antenna ( 1 ) on a loop basis after each installation effortlessly manually adjusted. This is annoying, time consuming and unwanted by the user.

Furthermore, especially in the case of loop antennas, the resonance is very sharp and extremely sensitive to changes in geometry. An automatic tracking of the optimum balance when changing the geometry conditions or changing the component values would be an enormous improvement over the prior art.

The tracking of the antenna balance for radio systems for RF signal transmission for optimization of ranges is known. This is realized today in receiving mode in the receiver with electronically continuously tunable capacitance diodes with great success. In transmission mode, these components are unfortunately not applicable due to the large voltages or power. Here mechanically continuously tunable components such as capacitors and coils are used. These are mechanical solutions that are very clunky and sensitive to static accelerations, vibrations, dirt, moisture and large temperature changes. Unfortunately, there is no semiconductor solution today for great performances.

Another possibility is the adaptation of the transmission frequency to the environmental change of the inductance value according to the resulting resonance frequency from the current loop inductance and a fixed parallel capacitor. This procedure is already in practical use today. As a rule, this method can only be used for a very narrow frequency range and thus allows only a change in the loop geometry within narrow limits. If the change is too great, there is a risk of instability of the oscillator.

Furthermore, it is advantageous for digital sensor telemetry to use the frequency of the supply voltage as a reference for the clock processing in the rotor electronics. This eliminates the clock generation in the rotor, which saves components that Size optimized and extremely advantageous even at high ambient temperatures and accelerations. The necessary frequency stable oscillators for ambient temperatures up to 180 ° C and for extreme accelerations up to 100 000 g are still not available.

Another point is the EMC approval regulations. As is known, there are certain fixed frequencies at which higher transmission energy values such. B. at the frequency 13.56 MHz are allowed. A changing frequency would not make use of this advantage.

These problems lead to the search for an electronic solution for the required adaptive matching network ( 4 ) for optimized energy transfer to the rotor ( 30 ).

Desirable is an arrangement which avoids the disadvantages mentioned.

The object of the invention is, in the arrangement according to the preamble of claim 1 for Nahfeldtelemetrieanlagen the contactless energy transfer from the stator to the rotor ( 30 ) to optimize.

The main task is the optimized supply of the sensor and the rotor electronics ( 28 ) with energy on a moving or rotating shaft by means of the adaptive transmission unit ( 25 ). The adaptive transmission unit ( 25 ) should each adapt to the environmental conditions and ensure the highest possible efficiency of energy transfer. In addition, the telemetry data from rotor ( 30 ) are transmitted to the stator.

The self-balancing stator antenna ( 1 ) essential part.

The object is solved by the features of claim 1.

Contactless maintenance-free transmission systems of moving or rotating shafts with qualitatively high signal transmission quality are of great interest. An essential feature is the reliable contactless and inductive power supply of the rotor ( 30 ) even under changing environmental conditions with the greatest possible distance between the rotor antenna ( 29 ) and stator antenna ( 1 ). This guarantees a high degree of user-friendliness and the elimination of the usual stator antenna alignment.

Basically, there are stator antennas ( 1 ) from an induction coil ( 2 ), an adaptation network ( 4 ) and the supply line ( 15 ). The adaptation network ( 4 ) is used for optimized energy conversion in the induction coil ( 2 ). The adjusted state is reached when the supply line ( 15 ) maximum available energy without reflection completely in the induction coil ( 2 ) is implemented. Here, the adaptation network ( 4 ) with the induction coil ( 2 ) and a maximum sinusoidal magnetic field amplitude ( 20 ). The larger the magnetic field amplitude ( 20 ), the higher the induced voltage in the rotor antenna ( 29 ) and the greater a maximum possible distance between the rotor antenna ( 29 ) and the induction coil ( 2 ).

The adaptation network ( 4 ) is usually a parallel branch ( 17 ) parallel to the induction coil ( 2 ) and a serial branch ( 16 ). The circuit elements in the branches are usually fixed capacitors. By suitable choice of the capacitor values, the state of the optimal adaptation can be generated. Although adaptation can also be made by transformers, the capacitor solution is technically much simpler and less expensive.

The state of the art is the manual determination of the capacitor values. This is usually done with rotary capacitors in the parallel branch ( 17 ) and serial branch ( 16 ) and reciprocal tuning iteratively determines the optimal fit empirically. The corresponding variable capacitor values are then determined with a precise capacitance meter and then fixed values are used instead of the variable capacitor values. Unfortunately, the fixed values are only available in a 20% gradation. This requires the interconnection of several fixed values to achieve the exact desired Drehkondensatorwert.

This process is complicated, time-consuming and unreasonable for the user in the field.

The direct use of variable capacitors is ruled out because of the lack of temperature and acceleration resistance.

For this reason, a finely graduated digitally adjustable matching network ( 4 ) developed. The fine gradation is intended to reflect the analog character of the variable capacitor.

This network consists of electronically controllable capacity decades for the parallel branch ( 17 ) and the serial branch ( 16 ). The individual capacities in the capacity decade are switched on via an electronically controlled switch. By suitable choice of the individual capacitance values, with n switchable capacitances 2 ⁿ (2 high n) different total capacitance values can be achieved be generated. Usually, in order to achieve the greatest possible step size between the setting possibilities, the individual capacitance values always increase by a factor of 2 with an increasing index i (0 <i <n). The larger the number n, the finer the total desired capacity can be set.

The switches ( 18 ) for connecting the individual capacitance values can be either mechanical relays or semiconductor switches or bipolar or FET transistors. Mechanical relays are large, sensitive to vibration and require a lot of power and are only partially suitable for use in mechanical engineering or in vehicles. Commercially available semiconductor relays, on the other hand, are only suitable for low frequencies because of the high residual capacitance between the terminals. Although transistors are small, low in capacitance and insensitive to vibration, they can not switch ac voltage directly.

A possible solution to the problem is the switching of the AC voltage by means of a diode network ( 21 ). It is via the diode network ( 21 ) (Greatz circuit), the RF voltage full wave rectified. The rectified rf voltage can be controlled via a simple transistor as a switch ( 18 ), which depends on a logic ( 7 ) is driven. In the switched state, current flows in both directions through the two series-connected capacitors Cip in 10 and activates the connection of the capacitors Cip in the matching network ( 4 ). This version is particularly interesting for symmetrical applications. However, the number of necessary components is large.

Another solution is in 9 shown. Here the diode network only consists of a double diode. The one diode is switched to ground and ensures a clamping of the AC voltage by means of the capacitors Cip to be switched. The second diode in series with the collector of the transistor (switch 18 ) is used for rectification. In the switched state, the voltage drop across the double diode is limited to 0.7 volts. This will in effect make the capacitor Cip in the matching network ( 4 ). The necessary number of components is already cheaper here.

A particularly advantageous embodiment is the solution according to 7 , Here, a MOS-FET transistor is used as a switch. MOSFET transistors can switch extremely high frequencies. This eliminates the serial diode to the drain. Furthermore, it is characteristic of MOSFET transistors that they have already integrated a cross-diode between the drain and the source due to the technology. In contrast to bipolar transistors, MOSFET transistors without current limiting resistor can be switched directly from the processor output. This reduces the arrangement per switchable capacitance branch to the capacitance to be switched and the MOSFET transistor (switch 18 ). This considerably reduces the necessary number of components and allows very compact digitally controllable matching networks ( 4 ).

This is an essential point for solving the problem "self-balancing stator antenna ( 1 )" solved.

Another important point is the optimal / optimized setting of the adaptation network ( 4 ).

For this, the adaptation state of the stator antenna ( 1 ). To this serves the adaptation detector ( 11 ). It provides an analog or digital signal which is used as a command value of the logic ( 7 ) is supplied for automatic adjustment. As a basis for the determination of the adjustment state, the voltage amplitude at the induction coil ( 2 ) are drawn. The better the balance, the higher the voltage. Due to the fact that the output resistance of the RF energy source in the receiver does not always correspond to the supply line resistance (line resistance), when using the voltage maximum criterion at the induction coil ( 2 ) still leads to a certain mismatch in auto-matching from the serial branch ( 16 ) and the parallel branch ( 17 ) come. Nevertheless, in practice, the method is according to the variant with fixed Cs 5 in the serial branch ( 16 ) usually sufficient.

A better criterion for the adjustment is the evaluation of the signal of a directional coupler ( 14 ) in the supply line ( 15 ). The directional coupler ( 14 ) is a well-known component of high frequency technology. It allows the detection of the amplitudes of the forward and backward waves on a line. Optimal adaptation is given when the reflected power at the stator antenna is equal to zero. The signal for the amplitude of the return wave of the directional coupler ( 14 ) is sent to the adjustment detector ( 11 ). The adaptation detector obtains therefrom the analog or digital drive signal for the logic ( 7 ), which serves as a reference variable for the adjustment.

The logic ( 7 ) controls the digitally controllable matching network via a parallel port ( 4 ) at. The logic ( 7 ) can be realized by means of a digital circuit with integrated memory.

Advantageously, a micro-processor or an FPGA with parallel output port and an integrated analog-digital converter for digitizing the Output signal of the adaptation detector ( 11 ) are used. With a suitable algorithm in logic ( 7 ) different drive states for the matching network ( 4 ) and the respective korresspondierende adjustment quality from the output signal of the adaptation detector ( 12 ). The best drive state (optimal match) is stored and output by the processor at the parallel port upon completion of the algorithm. The optimal control state (optimal adaptation) can be determined in the simplest case by sequential connection of all possible control states. By means of iterative methods, the time required for the determination of the optimal activation state (optimal adaptation) can be significantly reduced.

2 and 3 show the typical arrangements of the functional elements.

Advantageous developments are given in the dependent claims.

The invention will be described with reference to the following figures.

It shows 1 shows a typical arrangement for non-contact detection of sensor signals on rotating shafts. The adaptive transmission unit ( 26 ) with adaptation network ( 4 ) according to the invention is a shaft ( 30 ) (Rotor) mounted. On the wave 30 is the rotor antenna ( 29 ) and rotor electronics ( 28 ) assembled. The rotor ( 30 ) can move freely within the induction loop ( 2 ) without the sufficient supply of the rotor ( 30 ) leaves.

2 shows the block diagram for the stator antenna ( 1 ). via the supply line ( 15 ), the matching network ( 4 ) and the power supply to power the logic ( 7 ) provided. The adaptation network ( 4 ) is connected to the induction coil ( 2 ) and is via the logic ( 7 ). The drive detector ( 11 ) uses the RF amplitude ( 22 ) on the induction coil ( 2 ) to obtain the matching criterion for the logic ( 7 ).

3 shows the block diagram for the stator antenna ( 1 ). Via the supply line ( 15 ), both the adaptation network ( 4 ) and the power supply to power the logic ( 7 ) provided. The adaptation network ( 4 ) is connected to the induction coil ( 2 ) and is via the logic ( 7 ). The drive detector ( 11 ) uses the output signal of the directional coupler ( 14 ) to obtain the matching criterion for the logic ( 7 ).

4 shows the customization network ( 4 ) with the serial branch ( 16 ) and the parallel branch ( 17 ).

The logic ( 7 ) controls the serial branch ( 16 ) and the parallel branch ( 17 ) at. The induction coil ( 2 ) is parallel to the parallel branch ( 17 ).

5 shows the customization network ( 4 ) with the serial branch ( 16 ) and the parallel branch ( 17 ).

The serial branch ( 16 ) is constructed as a suitable fixed capacity. The logic ( 7 ) controls only the parallel branch ( 17 ) at. The induction coil ( 2 ) is parallel to the parallel branch ( 17 ).

6 shows the parallel branch ( 16 ) or the serial branch ( 17 ). Both branches are fundamentally identical in structure. Each branch consists of a switchable capacitance decade consisting of the capacitors C1p to Cnp and the switches ( 18 ) from S1 to Sn. The switches are connected via the outputs of the logic ( 7 ) digitally controlled.

7 shows the switch ( 18 ) based on a MOSFET transistor with the serial connecting capacitor Cip.

8th shows the switch ( 18 ) based on a 2-way diode network ( 21 ) and a DC switch

9 shows the switch ( 18 ) based on a 2-way diode network ( 21 ) and a bipolar transistor as a switch in series with the switching capacitor Cip

10 shows the switch ( 18 ) based on a Greatz diode network ( 21 ) and a bipolar transistor as a switch in series with the switching capacitors 2 · Cip for symmetrical application.

The essential basic idea of the present invention resides in the fact that the self-aligning stator antenna ( 1 ) always has an optional power condition via the adaptive matching network (without manual intervention) ( 4 ) and thus optimum ranges between the stator antenna ( 1 ) and rotor antenna ( 29 ) guaranteed. Especially with the stator antenna with flexible induction coil ( 2 ), as in 1 shown, the mood is large due to the environment. This eliminates the otherwise mandatory manual adjustment of the stator antenna ( 1 ) when installing a sensor telemetry system in vehicles or machines. For compact stator antennas ( 1 ) without external induction coil ( 2 ), the influence of external factors is low and thus an adjustment when installing in a machine superfluous. Nevertheless, these stator antennas must be part of the production time-consuming manual adjustment. The cause lies in the tolerances of the components used.

The present invention also automatically corrects the tolerances in standard matching networks built from solid capacitors because of environmental conditions. Fixed capacitors usually have a manufacturing tolerance of up to 10%. This always requires that the necessary total capacitor value must always be composed of a multiplicity of manually measured partial capacities. This is very time consuming in the manufacturing process and costly. The function of the self-balancing stator antenna is therefore an enormous production advantage.

In a particularly cost-effective design as in 5 the adaptation network can be represented in the serial branch ( 16 ) consist of a suitable fixed capacitor and only the parallel branch ( 17 ) be self-balancing executed. This allows a very cost effective solution. However, this solution can only be used with limited adaptation needs.

In a particularly advantageous embodiment, the balancing of the stator antenna ( 1 ) automatically automatically tracked at a certain detuning of the adjustment. This guarantees that with changing transmission conditions, eg. B. always be optimized when changing geometric conditions optimal transmission conditions. Also, temperature-related or aging-related component value changes can be compensated.

In a further particularly advantageous embodiment, the necessary energy for the supply of logic ( 7 ) via a power supply ( 10 ) directly by rectification of the RF voltage ( 22 ). This eliminates a necessary external supply. This is particularly advantageous in retrofits where an external supply of the stator antenna ( 1 ) was not provided.

In a further particularly advantageous embodiment, the frequency of the RF voltage ( 22 ) used as clock source for the rotor electronics.

Summary

Sensor telemetry systems are used today for transmitting sensor data from rotating shafts. The supply energy for the rotor from the stator to the rotor antenna is transmitted without contact. In order to achieve good transmission distances, both the stator antenna and rotor antenna are tuned to resonance in the realization. This is very tedious and time consuming. In changing environmental conditions, the arrangement must be retuned. The present invention relates to a self-aligning and self-adapting transmission unit consisting of a stator loop antenna and a rotor. This eliminates the usual adjustment effort when installing the telemetry system and guarantees optimal transmission conditions in every situation.

LIST OF REFERENCE NUMBERS

1

self-balancing stator antenna

2

induction coil

3

Statorantennengehäuse

4

Matching network

5

FET transistor

6

RF line

7

logic

8th

rectifier

9

FET switch

10

power adapter

11

matching detector

12

Output signal adaptation detector

13

transistor

14

directional coupler

15

supply

16

serial branch

17

parallel branch

18

switch

19

Max. energy

20

magnetic field amplitude

21

Diode network

22

RF voltage

23

supply voltage

24

optimal balance point

25

balance state

26

adaptive transmission unit

27

Frequency of power supply

28

rotor electronics

29

rotor antenna

30

rotor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3922556 [0001]

Claims (19)

Self-balancing stator antenna ( 1 ) for application for optimized contactless energy transfer in near field telemetry systems from stator to rotor ( 30 ) - consisting - of supply line ( 15 ) - made of induction coil ( 2 ) - from adaptation network ( 4 ) - Power adapter ( 10 ) characterized by the following features: a) a self-aligning stator antenna ( 1 ) b) with a compact and extremely acceleration-resistant digitally adjustable network ( 4 ) (c) with an additional adjustment detector ( 11 ) d) with an additional processor ( 7 ) e) the processor ( 7 ) the digitally adjustable matching network ( 4 ) according to an algorithm based on the evaluation of the adaptation detector output signal ( 12 ) drives f) and micro-program that the matching network ( 4 ) so that the maximum available energy on the supply line ( 15 ) in the induction coil ( 2 ) possible optimally in a max. Magnetic field amplitude ( 20 ) is implemented. Self-balancing stator antenna ( 1 ) according to claim 1, characterized in that the digitally adjustable matching network ( 4 ) consist of a number of gradual switchable capacitors, which via digitally switchable switch ( 18 ) by means of the processor ( 7 ) to be controlled. Self-balancing stator antenna ( 1 ) according to claim 1 and 2, characterized in that the digitally adjustable matching network ( 4 ) from a serial branch ( 16 ) with fixed capacity and a parallel branch ( 17 ) with adjustable capacity. Self-balancing stator antenna ( 1 ) according to claim 1 and 2, characterized in that the digitally adjustable matching network ( 4 ) from a serial branch ( 16 ) with adjustable capacity consisting of a parallel branch ( 17 ) with adjustable capacity. Self-balancing stator antenna ( 1 ) according to claim 1 to 4, characterized in that the adaptation detector as a directional coupler ( 14 ), the directional coupler ( 14 ) into the supply line ( 15 ) and the reflectance as a criterion for the adjustment process the processor ( 7 ). Self-balancing stator antenna ( 1 ) according to claims 1 to 4, characterized in that the adaptation detector ( 11 ) is constructed as a voltage detector, which determines the voltage at the induction loop and this as a criterion for the adjustment process the processor ( 7 ). Self-balancing stator antenna ( 1 ) according to claim 1 to 6, characterized in that the n stepwise switchable capacitor values are different and can be realized by suitable choice of values 2 ⁿ (2 high n) different total capacity values with the same difference between each two consecutive total capacity values. Self-balancing stator antenna ( 1 ) according to claim 1 to 7, characterized in that the n stepwise switchable capacitor values via a relay ( 18 ) or semiconductor relay. Self-balancing stator antenna ( 1 ) according to claim 1 to 7, characterized in that the n stepwise switchable capacitor values via an FET transistor ( 5 ). Self-balancing stator antenna ( 1 ) according to claim 1 to 7, characterized in that the n stepwise switchable capacitor values via a diode network ( 21 ) and a transistor ( 13 ). Self-balancing stator antenna ( 1 ) according to claims 1 to 10, characterized in that the diode network ( 21 ) consists of a two-way circuit. Self-balancing stator antenna ( 1 ) according to claims 1 to 10, characterized in that the diode network ( 21 ) from a Greatzgleichrichterschaltung and the capacitors 2 × Cip are switched symmetrically. Self-balancing stator antenna ( 1 ) according to claim 1 to 12, characterized in that the energy for the supply of the self-balancing circuit via a power supply ( 10 ) from the RF voltage ( 22 ) is won. Self-balancing stator antenna ( 1 ) according to claim 1 to 12, characterized in that the energy for the supply of the self-balancing circuit via one of the RF voltage ( 22 ) superimposed supply voltage ( 23 ) via the power supply ( 10 ) is supplied. Self-balancing stator antenna ( 1 ) according to claim 1 to 14, characterized in that via a suitable algorithm ( 25 ) the optimal matching point ( 24 ) for the maximum magnetic field amplitude ( 20 ) is achieved. Self-balancing stator antenna ( 1 ) according to claims 1 to 15, characterized in that the algorithm ( 25 ) tests all setting options and the setting for the optimal adjustment point ( 24 ) selects. Self-balancing stator antenna ( 1 ) according to claims 1 to 16, characterized in that the algorithm ( 25 ) has iterative character and the setting for the optimal matching point ( 24 ) iteratively. Self-balancing stator antenna ( 1 ) according to any one of claims 1 to 17, characterized in that when the balancing state deteriorates ( 25 ) by a certain amount by changing the environmental condition or the component value change in the stator antenna ( 1 ) the algorithm for finding the new optimal match point ( 24 ) is started or the adjustment is tracked. Self-balancing stator antenna ( 1 ) according to claim 1 to 18, characterized in that the frequency of the power supply from clock reference for the rotor electronics ( 28 ) is being used.

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