Arrangement and method for generating an amplification signal for measuring amplifiers

Abstract

Arrangement (1) for generating an amplification signal (7) for measuring amplifiers (2a, 2b, 2c), which has a central control unit (5) with an output for outputting the amplification signal (7), characterized in that the central control unit (5) is arranged in an electrical system (14) with an analog-to-digital converter, that the central control unit (5) is connected on the input side via associated measuring amplifiers (2a, 2b, 2c) with at least one current-measuring resistor or via associated measuring amplifiers (2a, 2b, 2c) with a resistor in a voltage divider (27a, 27b, 27c) or with an arrangement (24) for generating a sum voltage (23) and on the output side with at least two measuring amplifiers (2a, 2b, 2c) functionally assigned to half-bridges (15a, 15b, 15c) of the electrical system (14) with an analog-to-digital converter and with a first input of a phase voltage V ph1 , V ph2 and V ph3 and / or phase currents i ph1 , iph2 , i ph3 is connected to the calculating and output evaluation circuit (9) and that a second input of the evaluation circuit (9) is at least indirectly connected to the outputs of the measuring amplifiers (2a, 2b, 2c) which each output a measurement signal (4a, 4b, 4c).

Description

[0001] The invention relates to an arrangement for generating an amplification signal for measuring amplifiers, which arrangement has a central control unit with an output for outputting the amplification signal.

[0002] The invention also relates to a method for generating an amplification signal for measuring amplifiers, in which a demand-adapted amplification signal is generated by means of a central control unit.

[0003] Such an amplification signal is used to control the gain or gain factor (also known as a proportionality factor) of a gain-controllable measuring amplifier, thus adapting the measurement signal generated by the measuring amplifier to the measuring range of a downstream analog-to-digital converter. Such an amplification factor describes the ratio of a measurement signal value at the output of the measuring amplifier to a measured value at the input of the measuring amplifier.

[0004] In this description, such measured quantities are usually specified as voltages. However, the measured quantities can, in principle, also be currents.

[0005] Analog-to-digital converters, for example, have an input voltage range or measuring range within which they function optimally and achieve their maximum resolution during analog-to-digital conversion. If the measured value to be measured, i.e., a voltage or current, exceeds this input measuring range of the analog-to-digital converter or does not optimally utilize it, adjustable measuring amplifiers are used to adjust the signal level.

[0006] This can occur, on the one hand, if the measured variable is too large for the input measuring range of the analog-to-digital converter. This can also be the case if the measured variable is much too small for the input measuring range of the analog-to-digital converter. The gain value can therefore assume values ​​greater than one, zero, or less than one.

[0007] A measuring amplifier whose gain can be controlled or regulated by means of an amplification signal thus converts the measured variable at its input into a measuring signal adapted to the measuring range of the analog-to-digital converter.

[0008] The present invention is suitable for power electronic assemblies for forming a three- or multi-phase system, such as is the case for motor or power grid applications. In these applications, measurements of quantities of equal or similar amplitudes are necessary. The present invention is effectively employed if these are so-called groupable quantities, i.e., if the maximum values ​​at a specific operating point reach a comparable level or amplitude. Such groupable quantities include, for example, the phase voltages V ph1 , V ph2 and V ph3in a three-phase system. Such groupable quantities can also include the phase currents i ph1 , i ph2 and i ph3 in a three-phase system.

[0009] This makes the invention particularly suitable for the industrial sector, where substantial advantages can be gained from the resulting savings in a context of intense competition and high production volumes. With regard to space-limited products, such as electrically operated refrigerant compressors in the automotive sector, further advantages arise in the form of potential space savings on the associated circuit board, on which the components required for an electrical system with an analog-to-digital converter, such as an inverter, for controlling the electric refrigerant compressor are arranged.

[0010] The present description refers, by way of example, to inverters in which several so-called half-bridges are arranged. As is known from the prior art, such half-bridges each have a high-side power switch and a low-side power switch. Between these power switches, a tap for the respective phase of the half-bridge is arranged, which is connected to the corresponding coils in the electric motor to be driven. Using a three-phase system as an example, three half-bridges are usually arranged with taps for phases ph1, ph2, and ph3.

[0011] In various state-of-the-art applications, centralized units are used to control or regulate actuators and measuring amplifiers.

[0012] In these controlled and regulated systems, feedback is realized through sensor-based measurement of relevant parameters. To obtain a sufficiently accurate system response over a wide operating range, the sensors must meet corresponding accuracy requirements. For example, in power electronic converter systems or inverters, phase currents and phase voltages must be precisely measured from idle to the maximum power of an electric motor, taking positive and negative control into account.

[0013] Microcontrollers are widely used in modern systems. These offer analog-to-digital converters (ADCs) that can process the measured variables related to a proportionality factor within a limited measuring range. Values ​​within this measuring range are converted into integers according to the measurement resolution of the analog-to-digital converter used. For example, for an analog-to-digital converter operating with an 8-bit resolution, a current range of -50 A to +50 A is represented by a digital equivalent in a number range from 0 to (2 8) = 256. This measurement is carried out in steps, specifically quantized. In this example, one step corresponds to 2*50 A / 256 steps = 0.4 A / step. Instantaneous values ​​between two quantization levels are rounded, as usual. In addition, there are interferences and inaccuracies that make the measurement even more difficult and generally reduce the actually usable measurement resolution of the analog-to-digital converter. However, this leads to inaccuracies at certain operating points because, for example, when an electric motor is started with very low currents, these currents are not represented or are represented only insufficiently accurately. In order to meet the requirements of the control and regulation systems, the requirement for the measurement resolution generally increases.

[0014] Therefore, current technology requires analog-to-digital converters with a resolution of more than 8 bits. However, the use of 12-bit, 16-bit, or 24-bit analog-to-digital converters leads to higher production costs.

[0015] Examples of this state of the art are disclosed in "Applied Electrical Measurement Technology" by Albert Haug and Franz Haug; Vieweg Teubner Verlag; ISBN 978-3-528-04567-8; particularly on page 65 ff., as well as in "Digital Signal Processing with MATLAB" by Prof. Dr. Martin Werner; Springer Fachmedien Wiesbaden; ISBN: 978-3-658-18647-0; particularly on page 305 ff.

[0016] DE 32 02 497 A1 discloses an analog / digital converter arrangement, particularly for scale construction, comprising a measuring amplifier for amplifying a measurement signal and an analog / digital converter for converting the amplified measurement signal into a digital measurement output signal. The measuring amplifier has at least one adjustable amplifier, the gain of which can be adjusted during a calibration process and for a measured value specified with respect to a certain measuring range end value, such that a fixed, predetermined value of the amplified measurement signal is obtained.In addition, a digital / analog converter serving as a multiplying amplifier with digitally adjustable amplification is provided as an adjustable amplifier, the digital inputs of which can be supplied with a digital control signal derived from the digitized, amplified measuring signal, by means of which, during an adjustment process, the measuring output signal can be adjusted to a fixed predetermined value at a value of the measured variable predetermined with respect to a certain measuring range end value.

[0017] However, these known systems do not allow for the central generation of an amplification signal based on groupable measured variables. Nor is the continuous generation of such an analog amplification signal for an electrical system with an analog-to-digital converter, such as an inverter, provided.

[0018] Thus, there is a need for an improved arrangement and method for generating a gain signal for a measuring amplifier.

[0019] The object of the invention is to provide a solution that enables simple and cost-effective generation of an amplification signal for multiple measuring amplifiers in an electrical system with an analog-to-digital converter. Furthermore, the amplification signal generated by each measuring amplifier should optimally adapt a measured variable to the existing measuring range of an analog-to-digital converter.

[0020] The problem is solved by an object having the features according to claim 1 of the independent patent claims. Further developments are specified in the dependent patent claims.

[0021] The problem is also solved by methods having the features according to independent patent claims 7, 8, and 9. Further developments are specified in the dependent patent claims.

[0022] The subject of the invention is a simple and advantageous adaptation of the amplitude of the measured variable to be recorded, such as a voltage U or a current I, to a measuring range of an analog-to-digital converter.

[0023] For this purpose, in a first variant, at least two corresponding measurement signals are generated from at least two measured variables, such as voltages, each of which is recorded by a measuring amplifier. These measurement signals are recorded and evaluated by a central control unit. Depending on this evaluation of the measurement signals, the central control unit generates an amplification signal with which the amplification factor of the measuring amplifier, whose gain is controllable, is regulated. This control is carried out in such a way that the measurement signal is adapted to the measuring range of the analog-to-digital converter in order to achieve the highest possible resolution or accuracy in the analog-to-digital conversion of the measurement signal representing the measured variable, in particular voltage or current. The relationship between the measurement signal at the output of the measuring amplifier, whose gain is controllable, and the measured variable at the input of the measuring amplifier is described by the amplification factor.

[0024] To determine the value of the measured variable, in particular voltage or current, a processing unit is provided, which receives both the result of the analog-to-digital conversion and the amplification signal with the value of the gain factor. Using these input variables, the processing unit can determine or calculate the actual measured variables, in particular voltage or current. Such a processing unit can be a microprocessor, for example.

[0025] In a second variant, a sum voltage formed from at least two voltages can be detected and evaluated by the central control unit. The at least two voltages are tapped at potential points in two different half-bridges of an inverter. The central control unit generates the amplification signal based on the evaluation of the sum voltage.

[0026] In a third variant, at least two measured variables, such as phase currents, are recorded by two measuring amplifiers with adjustable gain, each converted into a measurement signal, and evaluated by the central control unit. These at least two phase currents can, for example, be recorded using a shunt resistor arranged in each branch of a half-bridge. As usual, each measuring amplifier with adjustable gain can determine a voltage across the corresponding shunt resistor, and from the known value of the shunt resistor, the phase current through the shunt resistor can be deduced. For this purpose, the measuring amplifier contains appropriate logic or circuitry with which the current value is determined.

[0027] In another variant, a total current is recorded as the measured variable using an additional measuring amplifier, a corresponding measurement signal is generated, and evaluated by the control unit. Depending on the evaluation of this measurement signal, the central control unit generates the amplification signal.

[0028] Regardless of the respective variant, the central control unit uses the generated amplification signal to adjust the proportionality factor, i.e. the amplification of the measuring amplifiers, depending on the operating point, thereby achieving improved utilization of the measuring range of the analog-to-digital converter.

[0029] Generating a demand-adapted gain signal therefore means that the measuring range of the analog-to-digital converter is utilized to its fullest potential by adapting the measurement signal supplied to the analog-to-digital converter to the measuring range. This adaptation is achieved by the gain signal, which controls the gain of the adjustable measuring amplifiers during the generation of the measurement signal.

[0030] It is intended that the amplification signal generated by the central control unit is an analog signal.

[0031] By using such a gain signal, the gain of the measuring amplifier can be adjusted, for example, to step sizes of 0.04 A / step instead of 0.4 A / step. At the same time, the signal-to-noise ratio is improved, which improves signal quality. Such an adjustment is achieved with a gain signal that corresponds to a tenfold gain.

[0032] The generation of such an amplification signal for measuring range adjustment requires a central control unit, which represents a separate arrangement or circuit.

[0033] Alternatively, the central control unit can be implemented using a microprocessor and appropriate interfaces.

[0034] In any case, groupable signals are recorded and evaluated by the central control unit, and the amplification signal generated is used to adjust the amplification of two or more measuring amplifiers.

[0035] For this purpose, groups of sensors are formed that are physically linked or related to each other. For example, the phase currents i ph1 , i ph2 and i ph3 In an electrical system with an analog-to-digital converter, which can be an inverter, groupable signals are used, since these are considered comparable in amplitude under symmetrical load conditions despite phase shifts. This grouping of signals enables the control of multiple measuring amplifiers with a single gain signal and thus with the same gain factor.

[0036] Such a gain signal thus serves as an analog control signal for the gain-controllable measuring amplifiers, which achieves a quasi-continuous measurement resolution adjustment. In other words, a continuous, simultaneous adjustment of multiple measurement signals—indirectly the measured quantities to be measured—to the measuring ranges of multiple analog-to-digital converters is achieved.

[0037] To improve the signal quality of the analog amplification signal, the use of appropriate filters is provided, which, for example, remove noise from the amplification signal.

[0038] The technical and economic advantages of the arrangement and method for generating an amplification signal for measuring amplifiers include a reduction in the installation space required for a configuration controlling multiple measuring amplifiers and improved utilization of the available measuring range of the analog-to-digital converters. Furthermore, the signal-to-noise ratio during measurements with the analog-to-digital converters is improved, and manufacturing costs are reduced by using a single central control unit to control multiple measuring amplifiers.

[0039] Further details, features, and advantages of embodiments of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. They show: Fig. 1a to 1c: Examples of state-of-the-art analog-to-digital conversion, Fig. 2: a schematic diagram of the arrangement according to the invention with three measuring amplifiers, Fig. 3: a quasi-continuous measurement resolution adjustment with two groupable signals, Fig. 4: an embodiment of the arrangement according to the invention with a separate control unit, Fig. 5: an alternative embodiment of the arrangement according to the invention, Fig. 6: another alternative in the implementation of the arrangement according to the invention, Fig. 7: an embodiment of the arrangement according to the invention, in which voltages are used to form the amplification signal and Fig. 8: another embodiment in which voltages are used to form the amplification signal.

[0040] In the Fig. 1a, Fig. 1 b and Fig. Figure 1c shows several examples of analog-to-digital conversion from the state of the art. Fig. Figure 1a shows an analog-to-digital conversion with a low resolution of, for example, only six quantization levels or voltage levels. As usual, instantaneous values ​​between two quantization levels are rounded accordingly. With such a low resolution, the accuracy of a current or voltage measurement based on such an analog-to-digital conversion is very low.

[0041] Many applications require higher accuracy when measuring currents or voltages. This can be achieved by increasing the number of quantization levels of the analog-to-digital converter. An example of this is the Fig. 1b, which shows an analog-to-digital conversion with a resolution of nine quantization levels.

[0042] In the Fig. 1a and Fig. 1b, the distances between the quantization levels are equal and constant. In the Fig. Figure 1c shows an example of an analog-to-digital conversion in which the spacing of the quantization levels can be changed. Using a corresponding control signal, the spacing between the quantization levels is changed during operation. In the example shown, the spacing between the quantization levels is adapted to the amplitude of the signal to be measured. As shown in the Fig. As can be seen in Figure 1c, the analog-to-digital conversion is performed with smaller quantization steps in low-amplitude ranges, both in the positive and negative half-waves of the signal, and with larger quantization steps in higher-amplitude ranges. This enables significantly better measurement accuracy in the lower-amplitude ranges or at the maximum values. This type of quasi-continuous measurement resolution adjustment, known as quasi-continuous measurement resolution adjustment, offers the possibility of improving the measurement result without increasing the resolution of the analog-to-digital converter in applications where, in particular, the maximum values ​​need to be recorded with greater accuracy.

[0043] The one among the Fig. 1a, Fig. 1b and Fig. The “bar” shown in Figure 1c, which widens to the right, shows the increase in measurement accuracy from Fig. 1a after Fig. 1c.

[0044] The Fig. Figure 2 shows a schematic diagram of the arrangement 1 according to the invention with three measuring amplifiers 2a, 2b, 2c. These measuring amplifiers 2a, 2b, 2c can be used, for example, in an electrical system with an analog-to-digital converter, such as a three-phase inverter, for measuring the currents i ph1 , i ph2 , i ph3 in the three phases Ph1, Ph2 and Ph3 in the Fig. 2 half-bridges not shown. Alternatively, the three measuring amplifiers 2a, 2b, 2c can measure the phase voltages V ph1 , V ph2 , V ph3 measure completely or partially, for example via a voltage divider.

[0045] The currents i ph1 , i ph2 , i ph3 or the phase voltages V ph1 , V ph2 , V ph3 represent the measured quantities 3a, 3b, 3c to be recorded in arrangement 1.

[0046] The three gain-controlled measuring amplifiers 2a, 2b, 2c generate three corresponding measurement signals 4a, 4b, 4c, which are transmitted to a central control unit 5 for evaluation. The measurement signals 4a, 4b, 4c are also transmitted to the inputs of the analog-to-digital converters 6a, 6b, 6c. The measurement signals 4a, 4b, 4c have a known relationship to the measured variables 3a, 3b, 3c, which is described by an amplification factor of the gain-controlled measuring amplifiers 2a, 2b, 2c.

[0047] Depending on the evaluation of the transmitted measuring signals 4a, 4b, 4c, the central control unit 5 generates an amplification signal 7, which is transmitted to the measuring amplifiers 2a, 2b, 2c for the joint control of the amplification or the amplification factor.

[0048] Each analog-to-digital converter 6a, 6b, 6c has an input-side measuring range 8a, 8b, 8c, which is indicated by the curly brackets shown at the inputs of the analog-to-digital converters 6a, 6b, 6c. Fig. Figure 2 only illustrates the general operating principle. In the practical implementation of arrangement 1, the outputs of the measuring amplifiers 2a, 2b, 2c are electrically connected to the inputs of the analog-to-digital converters 6a, 6b, 6c.

[0049] According to the present method, the central control unit 5 generates the amplification signal 7 in such a way that the measurement signals 4a, 4b, 4c are optimally adapted or utilized to the input-side measurement ranges 8a, 8b, 8c. Since this adaptation is achieved by controlling the gain or gain factor of the measurement amplifiers 2a, 2b, 2c, the amplification signal 7 is also transmitted to an evaluation circuit 9. The results 10a, 10b, 10c generated during the analog-to-digital conversions by the analog-to-digital converters 6a, 6b, 6c are also made available to the evaluation circuit 9 on the input side.

[0050] The evaluation circuit 9 can calculate the measured variables 3a, 3b, 3c using the results 10a, 10b, 10c of the analog-to-digital conversions, which correspond to the measured signals 4a, 4b, 4c, and the amplification signal 7, which describes the ratio of the measured signals 4a, 4b, 4c to the measured variables 3a, 3b, 3c. Thus, the currents i are determined by the evaluation circuit 9. ph1 , i ph2 , i ph3 or the phase voltages V ph1 , V ph2 , V ph3 calculated and for further processing in a Fig. 2 arrangement not shown at output 11, for example in digital form.

[0051] In an alternative implementation of the arrangement 1, it is provided that the central control unit 5 is supplied not with the measurement signals 4a, 4b, 4c but with the results of the analog-digital conversion 10a, 10b, 10c and that the amplification signal 7, with which the amplification factor of the amplification-controllable measuring amplifiers 2a, 2b, 2c is regulated, is formed as a function of the evaluation of the results of the analog-digital conversion 10a, 10b, 10c.

[0052] The Fig. Figure 3 shows a quasi-continuous measurement resolution adjustment with two groupable signals. In the upper illustration of the Fig. 3 shows a first signal 12 with its temporal course, while in the middle illustration the Fig. 3 a second signal 13 is shown with its temporal course.

[0053] Since the magnitude of the amplitudes of the first signal 12 and the second signal 13 are comparable, the signals 12, 13 can be grouped despite a phase shift. This means that the measurement resolution adjustment for this group of these signals 12, 13 can be performed using a common amplification signal 7, wherein the amplification signal 7, for example, controls both the measurement amplifier 2a associated with the first signal 12 and the measurement amplifier 2b associated with the second signal 13.

[0054] The amplification signal 7 generated to control the amplification is shown as an example in the lower illustration of the Fig. 3 shown.

[0055] In an example, the first signal 12 of the measured quantity 3a from the Fig. 2 and the second signal 13 of the measured quantity 3b from the Fig. 2 correspond to each other.

[0056] Since the amplitudes of signals 12, 13 change only relatively slowly, the central control unit 5 can easily generate an amplification signal 7 that varies with the magnitude of the amplitudes of signals 12, 13. Filtering of the amplification signal 7 is also provided to eliminate interfering noise.

[0057] In the Fig. 4 shows an embodiment of the arrangement 1 according to the invention. Fig. Figure 4 shows an example of an electrical system 14 with an analog-to-digital converter, an inverter in which three half-bridges 15a, 15b, 15c are arranged between the potentials HV+ and HV-. The example shows a three-phase inverter, but the invention is not limited to an inverter with three phases.

[0058] In each half-bridge 15a, 15b, 15c, a high-side power switch 16 and a low-side power switch 17 are arranged, as usual, which is only indicated for the half-bridge 15c by way of example. Between the high-side power switches 16 and the low-side power switches 17, a tap 18 is arranged for the respective phase Ph1, Ph2, and Ph3 of the half-bridge, which tap is connected, for example, to the corresponding coils in an electric motor to be driven. In the example of the Fig. 4, the tap 18 for the third phase Ph3 is shown in the half bridge 15a, 15b, 15c.

[0059] To measure the phase currents, phase current measuring resistors 19a, 19b, and 19c are arranged in series with the half-bridges 15a, 15b, and 15c. The first phase current measuring resistor 19a is assigned to the first half-bridge 15a, while the second phase current measuring resistor 19b is assigned to the second half-bridge 15b, and the third phase current measuring resistor 19c is assigned to the third half-bridge 15c.

[0060] As is known from the state of the art, the currents i ph1 the first half-bridge 15a, i ph2 the second half-bridge 15b and i ph3of the third half-bridge 15c is determined by means of the voltage drop across the respective phase current measuring resistor 19a, 19b, 19c. For this purpose, the measuring amplifiers 2a, 2b, 2c are arranged to record the voltages across the phase current measuring resistor 19a, 19b, 19c. Based on the voltages thus determined and the known size of the respective phase current measuring resistor 19a, 19b, 19c, Ohm's law is used and the respective phase current i ph1 , i ph2 and i ph3 This calculation can already be performed in the measuring amplifiers 2a, 2b, 2c if they are equipped with the appropriate logic. Thus, the measuring amplifiers 2a, 2b, 2c provide values ​​for the phase currents i ph1 , i ph2 , i ph3 at the respective output of the measuring amplifiers 2a, 2b, 2c, as shown in the Fig. 4 is shown.

[0061] In case the calculation of the phase currents i ph1 , i ph2 , iph3 Based on the measured voltages and the known values ​​of the phase current measuring resistors 19a, 19b, 19c, the measurement is performed not in the measuring amplifiers 2a, 2b, 2c, but later in a central processing unit. The measuring amplifiers 2a, 2b, 2c output corresponding values ​​representing the currents. This can be, for example, an analog or digital value or a corresponding voltage.

[0062] In the examples shown here, the measuring signal 4a, 4b, 4c output by the measuring amplifiers 2a, 2b, 2c is the respective phase current i ph1 , i ph2 , i ph3 be.

[0063] These phase currents i ph1 , i ph2 , i ph3and thus the measurement signals 4a, 4b, 4c are transmitted to a central control unit 5. This central control unit 5 evaluates the transmitted measurement signals 4a, 4b, 4c and, depending on this evaluation, forms the amplification signal 7. Such an evaluation can, for example, be carried out in such a way that the amplification signal 7 has a large value for large amplitudes of the measurement signals 4a, 4b, 4c and a smaller value for smaller amplitudes of the measurement signals 4a, 4b, 4c, or vice versa.

[0064] The amplification signal 7 generated by the central control unit 5 is transmitted to the gain-controllable measuring amplifiers 2a, 2b, 2c, thus controlling the gain of the measuring amplifiers 2a, 2b, 2c. This control is performed in such a way that the measuring signals 4a, 4b, 4c are always optimally adapted to the measuring range 8a, 8b, 8c of the respective analog-to-digital converter 6a, 6b, 6c, thus significantly improving the accuracy of the phase current measurement in certain ranges without requiring analog-to-digital converters 6a, 6b, 6c with multiple quantization levels. The label “xG” visible in the measuring amplifiers 2a, 2b, 2c means that the measured variables 3a, 3b, 3c present at the input of the measuring amplifiers 2a, 2b, 2c are amplified with a gain determined by the amplification signal 7 and thus form the measuring signals 4a, 4b, 4c.

[0065] An arrangement of the analog-digital converters 6a, 6b, 6c can be arranged at the Fig. 4 by means of dashed lines in the arrangement 1. Alternatively, the analog-to-digital converters 6a, 6b, 6c can be arranged at other positions, such as within the measuring amplifiers 2a, 2b, 2c.

[0066] In the Fig. 4 optionally shown arrangement of the analog-digital converters 6a, 6b, 6c, not the measurement signals 4a, 4b, 4c, but the results of the analog-digital conversion 10a, 10b, 10c would be transmitted to the central control unit 5 and the amplification signal 7 would be generated depending on the evaluation of the results of the analog-digital conversion 10a, 10b, 10c.

[0067] The results of the analog-to-digital conversion 10a, 10b, 10c are also transmitted to the evaluation circuit 9, which also receives the current value of the amplification signal 7. The evaluation circuit 9 can calculate the measured variables 3a, 3b, 3c using the results 10a, 10b, 10c of the analog-to-digital conversions, which correspond to the measured signals 4a, 4b, 4c, and the amplification signal 7, which describes the ratio of the measured signals 4a, 4b, 4c to the measured variables 3a, 3b, 3c. Thus, the phase currents i ph1 , i ph2 , i ph3 calculated and can be used for further processing in a Fig. 4, for example in digital form. In an alternative, the evaluation circuit 9 is a microprocessor, which carries out further processing of the phase currents i ph1 , i ph2 , i ph3Such a microprocessor can, for example, control the inverter in its function and thus a driven electric motor and for this purpose measure the current values ​​of the phase currents i ph1 , i ph2 , i ph3 Such an electric motor can be installed, for example, in an electric refrigerant compressor in a vehicle.

[0068] The Fig. Figure 5 shows an alternative embodiment of the arrangement 1 according to the invention, also using the example of an inverter as an electrical system 14 with an analog-to-digital converter. Fig. 5, a simplified representation has been chosen in which, for example, the analog-digital converters 6a, 6b, 6c are not shown separately.

[0069] In the Fig. 5 shows a number of assemblies which are already available for Fig. 4 have been described in detail, therefore please refer to the explanations on Fig. 4 and only the differences are discussed below.

[0070] In contrast to Fig. 4 is in the Fig. 5 a common module for the central control unit 5 and the evaluation circuit 9 is provided. In one example, a microprocessor can implement the functions of the central control unit 5 and the evaluation circuit 9. Thus, the microprocessor processes the measurement signals 4a, 4b, 4c or the results of the analog-digital conversion 10a, 10b, 10b, which in the Fig. 5 is not shown, and depending on this evaluation, the amplification signal 7 is formed and output to the measuring amplifiers 2a, 2b, 2c. Output of the amplification signal 7 to the evaluation circuit 9 is not explicitly necessary, since the microprocessor also maps the functionality of the evaluation circuit 9. The value of the current amplification signal 7 can be stored, for example, in a register or memory of the microprocessor. When calculating the phase currents i ph1 , i ph2 , i ph3 the value stored in the register or memory can be easily accessed.

[0071] In this version, the phase currents i are also calculated ph1 , i ph2 , i ph3by means of the formed results 10a, 10b, 10c of the analog-digital conversions, which correspond to the measurement signals 4a, 4b, 4c, and by means of the amplification signal 7, which describes the ratio of the measurement signals 4a, 4b, 4c to the measurement quantities 3a, 3b, 3c.

[0072] The Fig. Figure 6 shows a further alternative for implementing the arrangement 1 according to the invention, also using the example of an inverter as an electrical system 14 with an analog-to-digital converter. Fig. 5, only the differences will be discussed below.

[0073] In this embodiment, a total current measuring resistor 20 is arranged, via which a total current i summe which results from an addition of the phase currents i ph1 , i ph2 , i ph3 To record this total current i summeA further measuring amplifier 21 is arranged, which is only required to generate the amplification signal 7 and whose amplification is not influenced by the amplification signal 7. The output value of the further measuring amplifier 21, i.e., the measurement signal 4, is transmitted to the central control unit 5, evaluated, and based on this evaluation, the amplification signal 7 is calculated and output. In this case, the amplification signal 7 is output to the measuring amplifiers 2a, 2b, 2c and to the evaluation circuit 9.

[0074] The calculation of the phase currents i ph1 , i ph2 , Ĭ ph3In the evaluation circuit 9, the resulting results 10a, 10b, 10c of the analog-to-digital conversions, which correspond to the measurement signals 4a, 4b, 4c, or the measurement signals 4a, 4b, 4c themselves and the amplification signal 7, which describes the relationship between the measurement signals 4a, 4b, 4c and the measured variables 3a, 3b, 3c, are used. For example, a microprocessor can also be used for each of the central control unit 5 and the evaluation circuit 9.

[0075] The Fig. 7 shows an embodiment of the arrangement 1 according to the invention, in which, unlike previously in an electrical system 14 with an analog-digital converter, such as an inverter, flowing currents are used to form the amplification signal 7, but voltages are used.

[0076] In contrast to the Fig. 4, Fig. 5 and Fig. 6, no current or multiple currents are used to form the amplification signal 7. In the solution of Fig. 7, three voltages are tapped at the potential points 22a, 22b, 22c shown, and a sum voltage 23 is formed from these. For this purpose, an arrangement 24 for forming the sum voltage 23 is arranged, which is connected on the input side to the potential points 22a, 22b, 22c and on the output side to the input of the central control unit 5. Such an arrangement 24 for forming the sum voltage 23 can, as in the Fig. 7, an arrangement consisting of an operational amplifier 25 and several resistors 26.

[0077] In this variant, the amplification signal 7 is generated in the central control unit 5 by evaluating the sum voltage 23. The amplification signal 7 thus generated is output to the measuring amplifiers 2a, 2b, 2c and to the evaluation circuit 9. The evaluation circuit 9 calculates the phase currents i ph1 , i ph2 , i ph3 in the Fig. 4 and Fig. 6 already explained.

[0078] The Fig. Figure 8 shows a further embodiment, also using the example of an inverter as an electrical system 14 with an analog-to-digital converter, in which voltages are used to form the amplification signal 7. At the taps 18 of the half-bridges 15a, 15b, 15c, the voltages of the three phases Ph1, Ph2, Ph3 are fed out of the inverter and, for example, to an electric motor (not shown).

[0079] In this variant, voltage dividers 27a, 27b, 27c are arranged between three phases Ph1, Ph2 and Ph3 and, for example, a potential HV- of the inverter. In the example of the Fig. 8, the first voltage divider 27a is assigned to the first phase Ph1, the second voltage divider 27b to the second phase Ph2 and the third voltage divider 27c to the third phase Ph3.

[0080] It is intended to arrange a measuring amplifier 2a, 2b, 2c at each of the resistors or partial resistors of the voltage dividers 27a, 27b, 27c. By means of these measuring amplifiers 2a, 2b, 2c, the phase voltages V ph1 , V ph2 and V ph3For this purpose, a partial voltage is determined at the respective partial resistance of the associated voltage divider 27a, 27b, 27c, to which the respective measuring amplifier 2a, 2b, 2c is arranged. The known division ratio of the respective voltage divider 27a, 27b, 27c and the determined partial voltage allows the respective phase voltage V ph1 , V ph2 and V ph3 be calculated.

[0081] In this case, the measuring signals 4a, 4b, 4c output by the measuring amplifiers 2a, 2b, 2c are the phase voltages V ph1 , V ph2 and V ph3 or with the respective phase voltage V ph1 , V ph2 and V ph3 corresponding partial voltages. These are the input variables of the central control unit 5, which calculates the phase voltages V ph1 , V ph2 and V ph3forms or calculates the amplification signal 7. The amplification signal 7 calculated in this way is output to the measuring amplifiers 2a, 2b, 2c and to the evaluation circuit 9 and is also used in this variant for the optimal adaptation of the measuring signals 4a, 4b, 4c to the measuring ranges 8a, 8b, 8c of the analog-to-digital converters 6a, 6b, 6c (not shown). List of reference symbols 1 Arrangement for generating an amplification signal 2a, 2b, 2c measuring amplifiers 3a, 3b, 3c Measured quantities (current / voltage) 4, 4a, 4b, 4c measurement signal 5 central control unit 6a, 6b, 6c Analog-to-digital converters 7 Amplification signal 8a, 8b, 8c measuring range 9 Evaluation circuit (microprocessor) 10a, 10b, 10c Result of the analog-to-digital conversion 11 Exit 12 first signal 13 second signal 14 electrical system with an analog-to-digital converter (inverter) 15a, 15b, 15c Half bridge 16 high-side circuit breakers 17 Low-side circuit breakers 18 Tap 19a, 19b, 19c Phase current measuring resistor 20 Total current measuring resistor 21 additional measuring amplifiers 22a, 22b, 22c Potential points 23 Total voltage 24 Arrangement for forming a sum voltage 25 operational amplifiers (OPA) 26 resistors 27a, 27b, 27c voltage divider

Claims

[1] Arrangement (1) for generating an amplification signal (7) for measuring amplifiers (2a, 2b, 2c), which has a central control unit (5) with an output for outputting the amplification signal (7), characterized by that the central control unit (5) is arranged in an electrical system (14) with an analog-digital converter, that the central control unit (5) is connected on the input side via associated measuring amplifiers (2a, 2b, 2c) with at least one current measuring resistor or via associated measuring amplifiers (2a, 2b, 2c) with a resistor in a voltage divider (27a, 27b, 27c) or with an arrangement (24) for forming a sum voltage (23) and on the output side with at least two measuring amplifiers (2a, 2b, 2c) functionally assigned to half-bridges (15a, 15b, 15c) of the electrical system (14) with an analog-digital converter and with a first input of a phase voltage V ph1 , V ph2 and V ph3 and / or phase currents i ph1 , i ph2, i ph3 calculating and outputting evaluation circuit (9) and that a second input of the evaluation circuit (9) is at least indirectly connected to the outputs of the measuring amplifiers (2a, 2b, 2c) each outputting a measuring signal (4a, 4b, 4c). [2] Arrangement according to claim 1, characterized by that the central control unit (5) is a separate analogue circuit arrangement or a digital circuit arrangement or a microcontroller with corresponding interfaces. [3] Arrangement according to claim 1 or 2, characterized by that the current measuring resistor is a total current measuring resistor (20) or at least two in the half-bridges (15a, 15b, 15c) of the electrical system (14) with an analog-digital converter each arranged a phase current i ph1 , i ph2 , i ph3 in a half bridge (15a, 15b, 15c) measuring phase current measuring resistors (19a, 19b, 19c). [4] Arrangement according to one of claims 1 to 3, characterized by that the arrangement (24) for forming the sum voltage (23) is an operational amplifier (25) which is connected on the input side at least indirectly to a potential point (22a, 22b, 22c) in each of the half-bridges (15a, 15b, 15c) and on the output side to the central control unit (5). [5] Arrangement according to one of claims 1 to 4, characterized by that the voltage divider (27a, 27b, 27c) is arranged between the phases (Ph1, Ph2, Ph3) of the electrical system (14) with an analog-digital converter and a negative potential HV- or a positive potential HV+. [6] Arrangement according to one of claims 1 to 5, characterized by that the electrical system (14) with an analog-digital converter is an inverter. [7] Method for generating an amplification signal (7) for measuring amplifiers (2a, 2b, 2c), in which a demand-adapted amplification signal (7) is generated by means of a central control unit (5), characterized bythat in a first step at least two phase currents i ph1 , i ph2 , i ph3 as measured variables (3a, 3b, 3c) and converted into measuring signals (4a, 4b, 4c) by means of measuring amplifiers (2a, 2b, 2c) and transmitted at least indirectly to an evaluation circuit (9) and the central control unit (5), that in a second step, depending on these measuring signals (4a, 4b, 4c), an amplification signal (7) is formed by means of the central control unit (5), that a gain of at least two measuring amplifiers (2a, 2b, 2c), provided in at least two half-bridges (15a, 15b, 15c) of an electrical system (14) with an analog-digital converter, is regulated by means of the formed amplification signal (7), that the amplification signal (7) is simultaneously transmitted to an evaluation circuit (9) and that phase voltages V ph1 , V ph2 and V ph3 and / or phase currents i ph1 , iph2 , i ph3 calculated and output. [8] Method for generating an amplification signal (7) for measuring amplifiers (2a, 2b, 2c), in which a demand-adapted amplification signal (7) is generated by means of a central control unit (5), characterized by that in a first step a total current i summedetected and converted into a measuring signal (4) by means of a further measuring amplifier (21) and transmitted to the central control unit (5), that in a second step, depending on this measuring signal (4), an amplification signal (7) is formed by means of the central control unit (5), that an amplification of at least two measuring amplifiers (2a, 2b, 2c), provided in at least two half-bridges (15a, 15b, 15c) of an electrical system (14) with an analog-digital converter, is controlled by means of the formed amplification signal (7), that the amplification signal (7) is simultaneously transmitted to an evaluation circuit (9) and that phase voltages V ph1 , V ph2 and V ph3 and / or phase currents i ph1 , i ph2 , i ph3 calculated and output. [9] Method for generating an amplification signal (7) for measuring amplifiers (2a, 2b, 2c), in which a demand-adapted amplification signal (7) is generated by means of a central control unit (5), characterized by that in a first step a sum voltage (23) is formed from voltages at several potential points (22a, 22b, 22c) located in half-bridges (15a, 15b, 15c) of an electrical system (14) with an analog-digital converter and is transmitted to the central control unit (5) or that several partial voltages V ph1 , V ph2 , V ph3the voltages of the phases Ph1, Ph2, Ph3 are provided as measuring signals (4a, 4b, 4c) and transmitted to an evaluation circuit (9), that in a second step, depending on the sum voltage (23) or the measuring signals (4a, 4b, 4c), an amplification signal (7) is formed by means of the central control unit (5), that an amplification of at least two measuring amplifiers (2a, 2b, 2c) in the electrical system (14) with an analog-digital converter is controlled by means of the formed amplification signal (7), that the amplification signal (7) is simultaneously transmitted to an evaluation circuit (9), and that phase voltages V ph1 , V ph2 and V ph3 and / or phase currents i ph1 , i ph2 , i ph3 calculated and output. [10] Method according to one of claims 7 to 9, characterized by that the amplification signal (7) is an analog signal. [11] Method according to one of claims 7 to 10, characterized by that the analog amplification signal (7) is filtered and noise of the amplification signal (7) is reduced. [12] Method according to one of claims 7 to 9, characterized by that the amplification signal (7) is converted into a digital signal and that the digital signal is transmitted to the measuring amplifiers (2a, 2b, 2c). [13] Method according to one of claims 7 to 12, characterized by that the amplification signal (7) and results (10a, 10b, 10c) formed during an analog-to-digital conversion are provided to the evaluation circuit (9) on the input side and that the evaluation circuit (9) calculates one or more associated actual values ​​of the measured variables (3a, 3b, 3c) from these input variables. [14] Method according to one of claims 7 to 13, characterized by that the electrical system (14) is provided with an analog-digital converter as an inverter.

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