MEASURING ASSEMBLY FOR AN INVERTER AND INVERTER ASSEMBLY

Abstract

Measuring arrangement for determining the bridge currents of a switched electrical converter unit (2), in which, in a modulation process, at least two electronic half bridges (3, 3′) are switched with temporally offset actuation signals by a control unit (4), comprising a measuring unit (1) that is connected to current sensors (6, 6′), wherein the current sensors (6, 6′) are arranged in the output or input lines of the half bridges (3, 3′) in order to measure the bridge currents, and the measuring unit (1) is connected to the control unit (4) for temporal synchronisation, wherein the measuring unit (1) is designed to define measurement times (8, 8′) of the current sensors (6, 6′) which are temporally synchronised with the actuation signals of the half bridges (3, 3′), as well as an inverter arrangement having such a measuring arrangement.

Claims

1. Measuring arrangement for determining the electrical power of a switched electrical converter unit (2), in which, in a modulation process, at least two electronic half bridges (3, 3′) are switched with temporally offset actuation signals by a control unit (4), comprising a measuring unit (1) that is connected to current sensors (6, 6′), characterised in that a. the current sensors (6, 6′) are arranged in the output or input lines of the half bridges (3, 3′) of the converter unit (2) in order to measure the bridge currents, and b. the measuring unit (1) is connected to the control unit (4) for temporal synchronisation, wherein c. the measuring unit (1) is designed to define measurement times (8, 8′) of the current sensors (6, 6′) which are temporally synchronised with the actuation signals of the half bridges (3, 3′).

2. Measuring arrangement according to claim 1, characterised in that the measuring unit (1) is designed to query the current sensors (6, 6′) with a measuring frequency which corresponds approximately to the frequency of the actuation signals and to define in advance measurement times (8, 8′) which lie substantially in the middle of the duty cycle ton of the actuation signals.

3. Measuring arrangement according to claim 1, characterised in that the measuring unit (1) is designed to query the current sensors (6, 6′) with a measuring frequency which is higher than the frequency of the actuation signals, and to select retrospectively those measurement times (8, 8′) which lie substantially in the middle of the duty cycle ton of the actuation signals.

4. Measuring arrangement according to claim 2, characterised in that the measuring unit (1) is designed to query the current sensors (6, 6′) during the duty cycle ton of the actuation signals at a plurality of measurement times (8, 8′), and to average the resulting measured values.

5. Measuring arrangement according to claim 1, characterised in that the measuring unit (1) a. is connected to at least one DC voltage sensor (10) arranged on the DC voltage side of the converter unit (2), and b. is designed to calculate the switched electrical power of the converter unit (2) or individual phases of the converter unit (2) from the measured bridge currents and the measured DC voltage.

6. Measuring arrangement according to claim 5, characterised in that the measuring unit (1) is designed to take into account the electrical internal resistances of the semiconductor switches and other electronic components of the half bridges (3, 3′) when calculating the electrical power of the converter unit (2).

7. Measuring arrangement according to claim 1, characterised in that the measuring unit (1) a. is connected to at least one DC sensor (5) arranged on the DC voltage side of the converter unit (2), and b. is designed to calculate the electrical power on the DC voltage side of the converter unit (2), and c. is designed to calculate the electrical efficiency of the converter unit (2).

8. Inverter arrangement, comprising a measuring arrangement according to claim 1 and a converter unit (2), in which, in a modulation process, at least two electronic half bridges (3, 3′) are switched with temporally offset actuation signals by a control unit (4), characterised in that the converter unit (2) is a switched inverter arrangement for converting a DC voltage V.sub.dc into an AC voltage V.sub.ac.

9. Inverter arrangement, comprising a measuring arrangement according to claim 1 and a converter unit (2), in which, in a modulation process, at least two electronic half bridges (3, 3′) are switched with temporally offset actuation signals by a control unit (4), characterised in that the converter unit (2) is a switched rectifier arrangement for converting an AC voltage V.sub.ac into a DC voltage V.sub.dc.

10. Inverter arrangement, comprising a measuring arrangement according to claim 1 and a converter unit (2), in which, in a modulation process, at least two electronic half bridges (3, 3′) are switched with temporally offset actuation signals by a control unit (4), characterised in that the converter unit (2) is a switched DC converter for converting a first DC voltage V.sub.1 into a second DC voltage V.sub.2.

11. Inverter arrangement according to claim 8, characterised in that the converter unit (2) is connected to an electrical machine (7), for example an electric motor or an electric generator, and the measuring unit (1) is connected to the electrical machine (7).

12. Inverter arrangement according to claim 11, characterised in that the measuring unit (1) is designed to receive mechanical measured values such as speed, torque and the like and to calculate the mechanical output of the electrical machine (7).

13. Inverter arrangement according to claim 11, characterised in that the measuring unit (1) is designed to receive thermal measured values such as the temperature of a motor winding, waste heat or differential temperature of a cooling medium of the electrical machine (7).

14. Inverter arrangement according to claim 11, characterised in that the measuring unit (1) is designed to determine from the electrical or mechanical measured values parameters of the components of an electrical and/or mechanical equivalent circuit diagram of the electrical machine (7).

15. Inverter arrangement according to claim 11, characterised in that the measuring unit (1) is designed to determine from the switched electrical power of the converter unit (2) and the mechanical power of the electrical machine (7) the efficiency of the electrical machine (7).

16. Inverter arrangement according to claim 8, characterised in that the control unit (4) and the measuring unit (1) are integrated in a common unit.

Description

[0025] Further features according to the invention are disclosed in the claims, the figures and the following description of the figures. The invention is explained below on the basis of non-exclusive exemplary embodiments:

[0026] FIG. 1a shows an example of an embodiment of a measuring arrangement according to the invention as a schematic block diagram with an electrical machine;

[0027] FIG. 1b shows an example of an embodiment of a measuring arrangement according to the invention as a schematic circuit diagram;

[0028] FIG. 1c shows another example of an embodiment of a measuring arrangement according to the invention as a schematic circuit diagram;

[0029] FIG. 2a shows schematically the profile of the actuation signals and the resulting current in the output line of the half bridges in an embodiment of a measuring arrangement according to the invention;

[0030] FIG. 2b shows schematically the profile of the actuation signals and the resulting current in the output line of the half bridges in a further embodiment of a measuring arrangement according to the invention;

[0031] FIG. 3 shows an exemplary embodiment of a further embodiment of a measuring arrangement according to the invention as a schematic circuit diagram;

[0032] FIG. 4 shows an example of an embodiment of an inverter arrangement according to the invention as a schematic block diagram.

[0033] FIG. 5 shows an example of an embodiment of a measuring arrangement according to the invention as a schematic block diagram with an inverter arrangement;

[0034] FIG. 6 shows an example of an embodiment of a measuring arrangement according to the invention as a schematic block diagram with a switched DC converter.

[0035] FIG. 1a shows an example of an embodiment of a measuring arrangement according to the invention as a schematic block diagram. The measuring arrangement comprises an electronic measuring unit 1 which is connected via interfaces to current sensors 6, 6′ (not shown) in an electrical converter unit 2. The measuring unit 1 is also connected via interfaces to sensors for measuring mechanical parameters of an electrical machine 7, namely the speed, acceleration, torque and waste heat of the electrical machine.

[0036] In this exemplary embodiment, the converter unit 2 is a switched inverter arrangement which converts a DC voltage Vi supplied by a battery into an AC voltage Vac for operation of the electrical machine 7. The converter unit 2 comprises two electronic half bridges 3, 3′ which, in a modulation process, are switched with temporally offset actuation signals by an electronic control unit 4. In this exemplary embodiment, the control unit 4 and the measuring unit 1 are designed as separate units. The control unit 4 calculates trigger times for actuating the electronic half bridges 3, 3′ of the converter unit 2 and makes these available to the converter unit 2. The current sensors 6, 6′ are arranged in the output or input lines of the half bridges 3, 3′ of the converter unit 2 in order to measure the bridge currents.

[0037] The measuring unit 1 is connected to the control unit 4 for temporal synchronisation and is designed to define measurement times 8, 8′ of the current sensors 6, 6′ which are synchronised in time with the actuation signals of the half bridges 3, 3′. This allows the measuring unit 1 to detect the current values exactly when the PWM actuation signals activate the respective half bridge.

[0038] FIG. 1b shows an example of an embodiment of a measuring arrangement according to the invention as a schematic circuit diagram. In this circuit diagram, the inner structure of the converter unit 2, which functions here as an inverter, is represented schematically. The half bridges 3, 3′ in each case comprise two electronic semiconductor switches, namely—depending on the desired voltage range and desired dynamics—SiC or GaN transistors Q.sub.1, Q.sub.2, Q.sub.1′, Q.sub.2′ with parallel-connected freewheeling diodes (not shown for reasons of clarity). These semiconductor switches are connected to the control unit 4 via control lines.

[0039] A DC voltage sensor 10 is arranged on the input side, i.e. on the side of the DC voltage V.sub.1. On the output side, i.e. on the side of the AC voltage V.sub.ac, highly dynamic current sensors 6, 6′ are arranged in the two output lines of the half bridges 3, 3′. The DC voltage sensor 10 and the current sensors 6, 6′ are connected to the measuring unit 1 via data lines. The control unit 4 provides the measuring unit 1 with a trigger signal to enable synchronisation of the current measurement with the PWM actuation signals.

[0040] FIG. 1c shows a further example of an embodiment of a measuring arrangement according to the invention as a schematic circuit diagram. This embodiment corresponds substantially to that of FIG. 1b, whereby, however, the control unit 4 comprises the measuring unit 1; in other words, in this exemplary embodiment the function of the measuring unit 1 is performed by the control unit 4.

[0041] FIG. 2a shows schematically the profile of the actuation signals of the switches Q1, Q2′ or Q2, Q1′ and of the resulting current 13 in the output line of the left-hand half bridges 3 of the circuit from FIG. 1b. The PWM actuation signals of the switches are represented with solid lines. The control unit 4 controls the semiconductor switches with PWM modulated signals in such a way that an approximately sinusoidal current curve results in the output line. The dashed lines show the measurement times 8, 8′ of the current sensors 6, 6′. In this exemplary embodiment, the measuring unit 1 queries the current sensors with a frequency that corresponds approximately to the frequency of the actuation signals, so that a current measurement takes place in each of the PWM actuation signals. The current value measured per period T is represented by a dot. The period duration of the PWM actuation signals is marked with the symbol T.

[0042] In this case, the measuring unit 1 knows the expected profile of the actuation signals and defines in advance measurement times 8.8′ which substantially lie in the middle of the duty cycle t.sub.on of the actuation signals. Consequently, in this embodiment, the current sensors 6, 6′ must be designed for a frequency corresponding to the frequency of the PWM actuation signal.

[0043] The transmitted electrical power of the output signal is calculated as the sum of the number M of half bridges and the number N of PWM pulses per period of the output signal T.sub.out from the average measured bridge current I.sub.i,j per half bridge and the DC voltage V.sub.1,j measured in the current pulse on the DC voltage side of the converter unit, wherein the DC voltage V.sub.1,j measured in the current pulse can optionally also be assumed to be constant:

[00001] $P_{out} = \frac{1}{T_{out}} \int_{0}^{Tout} u (t) .Math. i (t) d t \approx {.Math.}_{i = 1}^{M} {.Math.}_{j = 1}^{N} V_{1, j} .Math. I_{i, j} \approx V_{1} .Math. {.Math.}_{i = 1}^{M} {.Math.}_{j = 1}^{N} I_{i, j}$

[0044] The calculated transmitted electrical power can then be compared with the mechanical power calculated from the mechanical parameters of the electrical machine 7. An efficiency of the electrical machine 7 can be calculated from the ratio of mechanical power to electrical power. The mechanical power of the electrical machine 7 can also be determined from the measured waste heat.

[0045] FIG. 2b shows schematically the profile of the actuation signals and the resulting current in the output line of the half bridges in a further embodiment of a measuring arrangement according to the invention. In this exemplary embodiment, the measuring unit 1 queries the current sensors 6, 6′ with a measuring frequency that is significantly higher than the frequency of the actuation signals, as can be seen from the numerous dashed lines. Only afterwards, i.e. in a post-processing step, does the measuring unit 1 select those measurement times 8.8′ which lie substantially in the middle of the duty cycle t.sub.on of the actuation signals. Here too, the transmitted electrical power of the output signal is calculated according to the above formula. This allows the flexible adaptation of the power measurement to the PWM process; however, this requires the use of highly dynamic current sensors.

[0046] FIG. 3 shows an exemplary embodiment of a further embodiment of a measuring arrangement according to the invention as a schematic circuit diagram. In this exemplary embodiment, the converter unit 2 is designed as a 3-phase inverter which converts a DC voltage V.sub.1 into a 3-phase AC voltage with the phases L1, L2, L3 by means of six half bridges 3, 3′, 3a, 3a′, 3b′, arranged in parallel and controlled electronically by the control unit 4. In each case two half bridges are interconnected via current-compensated interleaving chokes 9, 9′, 9a′, 9a′, 9b′, 9b′ to enable a smooth current transfer between the half bridges. A current sensor 6, 6′, 6a, 6a′, 6b′, 6b′ is arranged in each output line of the half bridges; the input DC voltage is measured via a DC voltage sensor 10. In this exemplary embodiment, the measuring unit 1 is again integrated into the control unit 4. The measuring unit 1 is designed to calculate the electrical power of each phase L1, L2, L3 from the synchronised measured values from the current sensors 6, 6′, 6a′, 6b′, 6b′ and the DC voltage sensor 10.

[0047] FIG. 4 shows an example of an embodiment of an inverter arrangement according to the invention as a schematic block diagram. The inverter arrangement comprises a measuring arrangement and two converter units 2, 2′ which function as an inverter and downstream rectifier. In this exemplary embodiment, the measuring unit 1 is again integrated into the control unit 4. In each of the converter units 2, 2′, two electronic half bridges 3, 3′ are, in a modulation process, switched with temporally offset actuation signals by a control unit 4. Together, the two converter units 2, 2′ thus form a DC converter that converts the DC voltage V.sub.1 into the DC voltage V.sub.2.

[0048] In each of the two converter units 2, 2′, the input and output currents of the half bridges are measured synchronously with the actuation signals via current sensors 6, 6′; furthermore, the DC voltages V1 and V2 are also measured. This allows the electrical power of the two converter units 2, 2′ to be measured separately from each other, and the efficiency of each converter unit 2, 2′ can be determined. Furthermore, in this exemplary embodiment DC sensors 5.5′ are provided on the input side and output side. These can be used to calibrate the dynamic current sensors 6, 6′ arranged in the converter units 2, 2′, a predefined load being connected on the output side for this purpose.

[0049] The invention is not limited to the present exemplary embodiments, but covers all devices and methods within the scope of the following claims. In particular, the invention is not limited to the use of pulse width modulation methods with constant switching frequency, but also includes the use of pulse width modulation methods with variable switching frequency.

[0050] Terms used herein should not be interpreted too narrowly. Also, the concrete realisation of the inverter or rectifier arrangement in terms of circuit technology is not essential to the invention.

[0051] Converter units according to the invention in the form of inverter or rectifier arrangements or DC converters can always also provide an internal galvanic isolation and can be intended for medium to high electrical powers, for example powers in the range of 10 kW to 100 kW at a DC voltage of 12V, 24V, 48V, 230V or 850 V or to 300 kVA AC power.

[0052] FIG. 5 shows an example of an embodiment of a measuring arrangement according to the invention as a schematic block diagram. As already described in FIG. 1a with an exemplary electrical machine 7, in addition to the described electrical machine 7, an inverter arrangement or a switched DC converter can of course also be connected to the electrical converter unit 2. The measuring arrangement comprises an electronic measuring unit 1 which is connected via interfaces to current sensors 6, 6′ (not shown) in an electrical converter unit 2. The measuring unit 1 is also connected via interfaces to sensors for measuring electrical parameters of an inverter arrangement 11 under test, namely direct current I.sub.dc and DC voltage V.sub.dc.

[0053] In this exemplary embodiment, the converter unit 2 is a switched inverter arrangement 11 which converts a DC voltage V.sub.1 supplied by a battery into an AC voltage V.sub.ac for operation of the inverter arrangement 11 under test. The converter unit 2 comprises two electronic half bridges 3, 3′ which, in a modulation process, are switched with temporally offset actuation signals by an electronic control unit 4. In this exemplary embodiment, the control unit 4 and the measuring unit 1 are designed as separate units. The control unit 4 calculates trigger times for controlling the electronic half bridges 3, 3′ of the converter unit 2 and makes these available to the converter unit 2. The current sensors 6, 6′ are arranged in the output or input lines of the half bridges 3, 3′ of the converter unit 2 in order to measure the bridge currents.

[0054] The measuring unit 1 is connected to the control unit 4 for temporal synchronisation and is designed to define measurement times 8, 8′ of the current sensors 6, 6′ which are synchronised in time with the actuation signals of the half bridges 3, 3′. This allows the measuring unit 1 to detect the current values exactly when the PWM actuation signals activate the respective half bridge.

[0055] The inverter arrangement 11 under test is in particular a converter assigned to an electrical machine.

[0056] FIG. 6 shows an example of an embodiment of a measuring arrangement according to the invention as a schematic block diagram. The measuring arrangement comprises an electronic measuring unit 1 which is connected via interfaces to current sensors 6, 6′ (not shown) in an electrical converter unit 2. The measuring unit 1 is also connected via interfaces to sensors for measuring electrical parameters of a switched DC converter 12 under test, namely direct current I.sub.dc2 and DC voltage U.sub.dc2.

[0057] In this exemplary embodiment, the converter unit 2 is likewise a switched DC converter which converts a DC voltage V.sub.1 supplied by a battery into a DC voltage V.sub.dc for operation of the switched DC converter 12 under test. The converter unit 2 comprises two electronic half bridges 3, 3′ which, in a modulation process, are switched with temporally offset actuation signals by an electronic control unit 4. In this exemplary embodiment, the control unit 4 and the measuring unit 1 are designed as separate units. The control unit 4 calculates trigger times for controlling the electronic half bridges 3, 3′ of the converter unit 2 and makes these available to the converter unit 2. The current sensors 6, 6′ are arranged in the output or input lines of the half bridges 3, 3′ of the converter unit 2 in order to measure the bridge currents.

[0058] The measuring unit 1 is connected to the control unit 4 for temporal synchronisation and is designed to define measurement times 8, 8′ of the current sensors 6, 6′ which are synchronised in time with the actuation signals of the half bridges 3, 3′. This allows the measuring unit 1 to detect the current values exactly when the PWM actuation signals activate the respective half bridge.

[0059] The switched DC converter 12 under test is in particular a DC converter installed downstream of a fuel cell in the vehicle or a DC converter of a DC voltage charging infrastructure.

LIST OF REFERENCE SYMBOLS

[0060] 1 measuring unit

[0061] 2, 2′ converter unit

[0062] 3, 3′, 3a, 3a′, 3b, 3b′ half bridge

[0063] 4 control unit

[0064] 5, 5′ DC sensor

[0065] 6, 6′, 6a, 6a′, 6b, 6b′ current sensor

[0066] 7 electrical machine

[0067] 8, 8′ measurement time

[0068] 9, 9′, 9a, 9a′, 9b, 9b′ interleaving choke

[0069] 10, 10′ DC voltage sensor

[0070] 11 inverter arrangement

[0071] 12 DC converter

MEASURING ASSEMBLY FOR AN INVERTER AND INVERTER ASSEMBLY

Assignee

Inventors

Cpc classification

Classification Explorer

H02M1/0009

ELECTRICITY

Classification Explorer

H02P27/06

ELECTRICITY

Classification Explorer

H02M7/217

ELECTRICITY

Classification Explorer

H02M1/0012

ELECTRICITY

Classification Explorer

G01R21/06

PHYSICS

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H02M7/5395

ELECTRICITY

International classification

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H02M7/5395

ELECTRICITY

Classification Explorer

H02M1/00

ELECTRICITY

Classification Explorer

H02P27/06

ELECTRICITY

Classification Explorer

H02M7/217

ELECTRICITY

Abstract

Claims

Description