Method for operating a power converter circuit, power converter control unit and power converter arrangement

Abstract

Method for operating a power converter circuit (1, 1') with - a low side having several first controllable semiconductor switching elements (1a) connected in parallel to each other between a first DC voltage terminal (3a) and a center terminal (3c) of the converter circuit (1, 1'), - a high side having several second controllable semiconductor switching elements (1b) connected in parallel to each other between a second DC voltage terminal (3b) and the center terminal (3c) of the converter circuit (1, 1'), - a first temperature sensor (4a) arranged on one of the several first controllable semiconductor switching elements (1a) and configured to measure a first temperature, - a second temperature sensor (4b) arranged on one of the several second controllable semiconductor switching elements (1b) and configured to measure a second temperature, the procedure includes: Acquiring (S100) the first temperature measured by the first temperature sensor (4a) and the second temperature measured by the second temperature sensor (4b), and Determine (S110) that a fault exists in the converter circuit (1, 1') if the first temperature and / or the second temperature deviates from a temperature expectation value by more than a temperature deviation threshold value, characterized by the fact that The expected temperature value is determined depending on the first and / or the second temperature.

Description

[0001] The present invention relates to a method for operating a power converter circuit, a power converter control unit and a power converter arrangement. Background of the invention

[0002] Power converter circuits are electrical circuits used to convert one type of electrical current into another, for example, from direct current (DC) to alternating current (AC) or vice versa. For this purpose, power converter circuits can use, for example, one or more half-bridges connected in parallel, where each half-bridge has a high side and a low side, each with one or more semiconductor switching elements connected in parallel.

[0003] However, in parallel-connected semiconductor devices, an open-circuit fault (i.e., permanently non-conducting) occurring in one of the parallel semiconductor devices cannot be detected by a gate driver that switches the semiconductor devices, because the individual semiconductor devices on either the high or low side are driven by the same gate driver output. If one or more of the parallel semiconductor devices on the high or low side exhibit an open-circuit fault, meaning they are permanently open, the other semiconductor devices on that side can become thermally overloaded, which can ultimately cause the failure of all parallel semiconductor devices.

[0004] US 2019 / 0288678A1 discloses a driver circuit. A high- or low-side switch that is driven to the on state by a primary driver is called the target-side switch. The other high- or low-side switch that is driven to an off state by the primary driver is called the opposite-side switch. An intrinsic diode connected antiparallel to the opposite-side switch is called the opposite-side diode. The driver circuit includes a protection driver configured to detect whether a fault has occurred in the target-side switch. The protection driver is configured to change the target-side switch from the on state to the off state and the opposite-side switch from the off state to the on state when a fault is detected in the target-side switch. Disclosure of the invention

[0005] According to the invention, a method for operating a power converter circuit, a power converter control unit, and a power converter arrangement with the features of the independent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

[0006] The invention relates to a power converter circuit with a low-side comprising several first controllable semiconductor switching elements connected in parallel between a first DC voltage terminal and a center terminal of the power converter circuit, and a high-side comprising several second controllable semiconductor switching elements connected in parallel between a second DC voltage terminal and the center terminal. The power converter circuit is specifically designed to supply a load, such as phase windings of an electric machine, with an output current via the center terminal.

[0007] The number of first controllable semiconductor switching elements on the low side and the second controllable semiconductor switching elements on the high side depends in particular on the maximum current conductivity and the heat resistance of the power converter circuit.

[0008] The invention takes advantage of the fact that, under normal operating conditions, the parallel-connected semiconductor switching elements function normally and overheating of individual semiconductor switching elements does not occur. By determining the temperature of one or more, in particular all, semiconductor switching elements on the high and low sides, an open-circuit fault can be detected if the temperature of one or more of the semiconductor switching elements deviates from an expected temperature value by more than a temperature deviation threshold. When such an open-circuit fault is detected, the power converter circuit can be brought into a safe state. This prevents further semiconductor switching elements from being damaged in the event of an open-circuit fault.

[0009] Specifically, the power converter circuit includes a first temperature sensor, which is arranged on one of the several first controllable semiconductor switching elements and is configured to measure a first temperature, and a second temperature sensor, which is arranged on one of the several second controllable semiconductor switching elements and is configured to measure a second temperature.

[0010] The temperature sensor can be in direct contact with the semiconductor switching element, or it can be positioned at a certain distance that still allows sufficient heat conduction; for example, this distance can be no more than 1 cm. Due to the placement of the temperature sensors on a semiconductor switching element, the measured temperature is related to, or depends on, the temperature of the semiconductor switching element and thus serves as an indicator of it. The closer the temperature sensor is to the semiconductor switching element, the closer the measured temperature is to the actual temperature.

[0011] In the procedure, the first temperature measured by the first temperature sensor and the second temperature measured by the second temperature sensor are recorded, and their deviation from the expected temperature value is compared with a temperature deviation threshold.

[0012] According to the invention, the expected temperature value is determined as a function of the first temperature and / or the second temperature.

[0013] In embodiments of the invention where several first temperature sensors and several second temperature sensors are used, and accordingly several first temperatures and / or several second temperatures are measured, the expected temperature value is expediently determined as a function of all detected first temperatures and / or as a function of all detected second temperatures, in particular as an average value; or it is determined as a function of all other detected first temperatures and / or as a function of all other detected second temperatures, in particular as an average value. "As a function of all others" means that the temperature value currently being compared is not used to determine the expected temperature value.

[0014] The temperature deviation threshold can be adjusted, for example, to the region in which the power converter circuit is used or to the ambient temperature of the power converter circuit.

[0015] It is then determined that a fault exists in the power converter circuit if the first temperature and / or the second temperature deviates from the expected temperature value by more than a temperature deviation threshold. The temperature deviation threshold can, in particular, be 20 K. If the first or second temperature exceeds the expected temperature value by more than the temperature deviation threshold, this indicates an open-circuit fault, especially on the side from which the elevated temperature reading originates.

[0016] If it is determined that a fault exists in the power converter arrangement, the power converter circuit can in particular be brought into a safe state.

[0017] The invention further relates to a power converter control unit which, in particular in terms of programming, is configured to carry out all process steps of a method according to the invention.

[0018] The invention further relates to a power converter arrangement comprising a power converter control unit according to the invention, and a power converter circuit, as set out.

[0019] This proposes a power converter arrangement in which an open-circuit fault can be determined in a simple and cost-effective manner, and with which the advantages previously outlined in connection with the method can be achieved.

[0020] In embodiments of the invention, to transition to a safe state, all first controllable semiconductor switching elements can be closed (conducting) and all second controllable semiconductor switching elements can be opened (non-conducting) if the deviation of the second temperature from the expected temperature value exceeds the temperature deviation threshold. Conversely, if the deviation of the first temperature from the expected temperature value exceeds the temperature deviation threshold, in embodiments of the invention all second controllable semiconductor switching elements are closed and all first controllable semiconductor switching elements are opened. In particular, the side on which the open-circuit fault is suspected is always opened, and the other side is closed.

[0021] This prevents damage to non-defective semiconductor switching elements, making the repair of the power converter assembly simpler and more cost-effective. Furthermore, the procedure can be carried out cost-effectively with only one temperature sensor per side of the power converter circuit.

[0022] In one embodiment, several, in particular all, first controllable semiconductor switching elements have a first temperature sensor and / or several, in particular all, second controllable semiconductor switching elements have a second temperature sensor. During the acquisition process, the first temperature measured by each of the first temperature sensors and the second temperature measured by each of the second temperature sensors are acquired, and the deviation of each of the first and second temperatures from the expected temperature value is compared with the temperature deviation threshold to determine whether it is above the temperature deviation threshold. When using several first temperature sensors and / or several second temperature sensors, the expected temperature value is, in particular, calculated as the average of all (or all other, i.e.,The temperature expectation value can be determined by measuring the deviation of each of the first temperatures (except the one being compared to the expected temperature value), the deviation of each of the first temperatures (or all other second temperatures), or the deviation of each of the second temperatures (or all other first temperatures and all of the second temperatures). For example, if the power converter circuit has three first and three second controllable semiconductor switching elements, each equipped with a first or second temperature sensor, the deviation of each of the first temperatures from the average of all three or only the other two first temperatures can be determined as the expected temperature value, and analogously, each of the second temperatures can be determined from the average of all three or only the other two second temperatures as the expected temperature value.It is also conceivable that the deviation of each of the first temperatures from the average of all second temperatures, or from the average of all (or all other) first temperatures and all second temperatures, is determined as the expected temperature value in order to compare this with the temperature deviation threshold and determine whether a fault exists in the converter circuit. The same applies to the deviation of each of the second temperatures.

[0023] By using multiple temperature sensors, especially one temperature sensor on each semiconductor switching element, the location of an open-circuit fault can be determined quickly and reliably, allowing the procedure to be carried out in an optimized manner and simplifying repair even further.

[0024] In one embodiment, for first controllable semiconductor switching elements that do not have a first temperature sensor, a first estimated temperature of the first controllable semiconductor switching element is determined as a function of the first temperature measured by the one first temperature sensor or, if several first temperature sensors are installed in the power converter circuit, by the several first temperature sensors. Furthermore, for second controllable semiconductor switching elements that do not have a second temperature sensor, a second estimated temperature of the second controllable semiconductor switching element is determined as a function of the second temperature measured by the one second temperature sensor or, if several second temperature sensors are installed in the power converter circuit, by the several second temperature sensors.The first estimated temperature and / or the second estimated temperature are determined in particular by analytical equations obtained from thermal models, for example based on a current flowing through the controllable semiconductor switching elements.

[0025] In embodiments of the invention, the deviations of the first estimated temperature and / or the second estimated temperature from the expected temperature value are also compared with the temperature deviation threshold in order to detect a fault. This makes it possible to determine a temperature even for semiconductor switching elements that do not have a temperature sensor and thus also to infer a fault, thereby allowing the method to be carried out in an optimized manner.

[0026] The expected temperature value can be determined, in particular, as the average of all first temperatures and all (or all other) first estimated temperatures, all second temperatures and all (or all other) second estimated temperatures, or all first temperatures and all (or all other) first estimated temperatures and all second temperatures and all (or all other) second estimated temperatures. The procedure for determining the deviation is analogous to that described for the embodiment with multiple first temperature sensors and / or multiple second temperature sensors.

[0027] In one embodiment, the first controllable semiconductor switching elements and / or the second controllable semiconductor switching elements of the power converter circuit are transistors, in particular metal-oxide-semiconductor field-effect transistors or insulated-gate bipolar transistors (IGB transistors).

[0028] In one embodiment, several, in particular all, first controllable semiconductor switching elements have a first temperature sensor and / or several, in particular all, second controllable semiconductor switching elements have a second temperature sensor.

[0029] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0030] The invention is schematically illustrated in the drawing using exemplary embodiments and is described below with reference to the drawing. Brief description of the drawings Fig. Figure 1 shows a block diagram of an embodiment of a power converter arrangement set up to carry out the method according to the invention, Fig. 2 shows a flowchart of an embodiment of the method according to the invention, and Fig. Figure 3 shows a block diagram of a further embodiment of a power converter arrangement that is set up to carry out the method according to the invention. Embodiments of the invention

[0031] Fig. Figure 1 shows a block diagram of a power converter arrangement 100, which is set up to carry out the method according to the invention. Fig. Figure 2 shows a flowchart of an embodiment of the method according to the invention. Both figures will be described together in the following.

[0032] The converter arrangement 100 comprises a converter circuit 1 having a high and a low side, as well as a center terminal 3c between the high and low sides. A load, for example a phase winding of an electric machine 2, can be connected to the center terminal 3c. The present converter circuit 1 is designed as a half-bridge circuit, and several such converter circuits 1 can be part of the converter arrangement 100 to connect a multiphase AC load, e.g., a multiphase electric machine 2, to a DC power supply.

[0033] The low side here has two first controllable semiconductor switching elements 1a, which are connected in parallel to each other between a first DC voltage terminal 3a and the center terminal 3c of the converter circuit 1. The first DC voltage terminal 3a can, in particular, be a ground terminal. The high side here also has two second controllable semiconductor switching elements 1b, which are connected in parallel to each other between a second DC voltage terminal 3b and the center terminal 3c. The second DC voltage terminal 3b can, in particular, be connected to a DC voltage potential.

[0034] The first and second controllable semiconductor switching elements 1a, 1b are connected to a converter control unit 10 of the converter arrangement 100. The converter control unit 10 is configured to control the first and second controllable semiconductor switching elements 1a, 1b. It is understood that the high and / or low side can also have more than two controllable semiconductor switching elements connected in parallel, the number depending in particular on the maximum current conductivity.

[0035] The low side of the converter circuit 1 further includes in one branch (here the left branch) of the parallel circuit a first temperature sensor 4a, which is arranged on the left first controllable semiconductor switching element 1a and is configured to measure a temperature of the first controllable semiconductor switching element 1a as the first temperature.

[0036] Furthermore, the high side of the power converter circuit 1 in one branch (here the left branch) of the parallel circuit has a second temperature sensor 4b, which is arranged on the left second controllable semiconductor switching element 1b and is configured to measure a temperature of the second controllable semiconductor switching element 1b as a second temperature.

[0037] In the procedure, in step S100, the first temperature measured by the first temperature sensor 4a and the second temperature measured by the second temperature sensor 4b are recorded.

[0038] In an optional step S101, a first estimated temperature is determined for the other (shown here on the right) first controllable semiconductor switching element 1a on the low side, which does not have a first temperature sensor 4a, depending on the first temperature measured. Furthermore, a second estimated temperature is determined for the other (shown here on the right) second controllable semiconductor switching element 1b on the high side, depending on the second temperature measured. To determine the estimated temperature, analytical equations based on a thermal model that estimates the temperatures, for example, using measured currents flowing through the controllable semiconductor switching elements, can be used.

[0039] Subsequently, in step S110, a fault is determined in the power converter circuit 1 if the first temperature of one or more of the several first addressable semiconductor switching elements 1a and / or the second temperature of one or more of the several second addressable semiconductor switching elements 1b exceeds a temperature deviation threshold by more than one expected temperature value. For example, in this case, the expected temperature value could be the average of the other measured temperatures (i.e., all except the one being compared to the expected temperature value) and all estimated temperatures. Alternatively, the estimated temperature of the same side could also be used as the expected temperature value.

[0040] Similarly, in step S111, a fault is determined in the converter circuit 1 if the first estimated temperature of one or more of the several first controllable semiconductor switching elements 1a and / or the second estimated temperature of one or more of the several second controllable semiconductor switching elements 1b exceeds the expected temperature value by more than a temperature deviation threshold, which may be, for example, 20 K. For example, in this case, the expected temperature value could be an average of the other estimated temperature and all measured temperatures. Alternatively, the measured temperature of the same side could be used as the expected temperature value.

[0041] If a fault is determined to exist in converter circuit 1, this indicates that an open-circuit fault exists on the low side or the high side, and converter circuit 1 is transferred to a safe state in block S120.

[0042] In addition, if one or more of the first controllable semiconductor switching elements 1a exhibit a deviation of the first temperature or estimated temperature from the expected temperature value that is greater than the temperature deviation threshold, in step S121a all first controllable semiconductor switching elements 1a are opened and in step S122a all second controllable semiconductor switching elements 1b are closed.

[0043] However, if it is determined that one or more of the second controllable semiconductor switching elements 1b have a deviation of the second temperature or estimated temperature from the expected temperature value that is greater than the temperature deviation threshold, in step S121b all second controllable semiconductor switching elements 1b are opened and in step S122b all first controllable semiconductor switching elements 1a are closed.

[0044] This allows the remaining semiconductor switching elements to be protected.

[0045] Fig. Figure 3 shows a further embodiment of the power converter arrangement 100', which is set up to carry out the method according to the invention.

[0046] In contrast to the in Fig. In the converter arrangement 100 shown in 1, both the low side and the high side of the converter circuit 1' are in Fig. 3 three first and second controllable semiconductor switching elements 1a, 1b. Each of the first and second controllable semiconductor switching elements 1a, 1b is connected to and controlled by the power converter control unit 10.

[0047] Furthermore, a first and second temperature sensor 4a, 4b is arranged on each of the first and second semiconductor switching elements 1a, 1b of the converter circuit 1' of the converter arrangement 100', which measures the first and second temperature of the corresponding first and second semiconductor switching element 1a, 1b.

[0048] The procedure in the converter arrangement 100' is analogous to the one previously described with regard to the converter arrangement 100 of the Fig. The procedure described in section 1 is no longer relevant, so only the differences will be highlighted in the following.

[0049] Since a first or second temperature sensor 4a, 4b is arranged on each of the first and second controllable semiconductor switching elements 1a, 1b, a first or second temperature is detected for each of the first and second controllable semiconductor switching elements 1a, 1b in step S100. Therefore, no first or second temperatures need to be estimated in step S101.

[0050] The remainder of the procedure corresponds to the procedure as described above. Fig. 1 described. In step S110, for example, the expected temperature value can be an average of all measured temperatures on the same side, or of the other measured temperatures on the same side, or of both sides.

[0051] In the Fig. 1 and Fig.Figure 3 shows exemplary converter circuits 1, 1' with two or three controllable semiconductor switching elements per side. The application is not intended to be limited to these examples; that is, each of the high and low sides of the converter circuit 1, 1' can also have more than three semiconductor switching elements. Furthermore, even in converter circuits 1, 1' with more than three first and second semiconductor switching elements, not all semiconductor switching elements 1a, 1b need have a corresponding temperature sensor 4a, 4b, but only a subset of the semiconductor switching elements 1a, 1b. It is also possible for a different number of first and second temperature sensors 4a, 4b on the low and high sides, respectively, to have a temperature sensor.

Claims

[1] Method for operating a power converter circuit (1, 1') with - a low side having several first controllable semiconductor switching elements (1a) connected in parallel to each other between a first DC voltage terminal (3a) and a center terminal (3c) of the converter circuit (1, 1'), - a high side having several second controllable semiconductor switching elements (1b) connected in parallel to each other between a second DC voltage terminal (3b) and the center terminal (3c) of the converter circuit (1, 1'), - a first temperature sensor (4a) arranged on one of the several first controllable semiconductor switching elements (1a) and configured to measure a first temperature, - a second temperature sensor (4b) arranged on one of the several second controllable semiconductor switching elements (1b) and configured to measure a second temperature, the procedure includes: Acquiring (S100) the first temperature measured by the first temperature sensor (4a) and the second temperature measured by the second temperature sensor (4b), and Determine (S110) that a fault exists in the converter circuit (1, 1') if the first temperature and / or the second temperature deviates from a temperature expectation value by more than a temperature deviation threshold value, characterized by , that The expected temperature value is determined depending on the first and / or the second temperature. [2] The method of claim 1, wherein the method further comprises: Transfer (S120) the converter circuit (1, 1') to a safe state when it is determined that a fault exists in the converter circuit (1, 1'). [3] Method according to claim 2, wherein the process (S120) of transferring the converter circuit to the safe state comprises: Closing (S121a) of all first controllable semiconductor switching elements (1a) and opening (S122a) of all second controllable semiconductor switching elements (1b), and / or closing (S121b) of all second controllable semiconductor switching elements (1b) and opening (S122b) of all first controllable semiconductor switching elements (1a). [4] Method according to one of the preceding claims, wherein several, in particular all, first controllable semiconductor switching elements (1a) have a first temperature sensor (4a) and / or several, in particular all, second controllable semiconductor switching elements (1b) have a second temperature sensor (4b), wherein during detection (S100) the first temperature measured by each of the first temperature sensors (4a) and the second temperature measured by each of the second temperature sensors (4b) is detected and compared with the temperature expectation value when determining (S110) whether there is a fault in the power converter circuit (1, 1'). [5] Method according to claim 4, wherein the temperature expectation value is determined as a function of all recorded first temperatures and / or as a function of all recorded second temperatures, in particular as an average value. [6] Method according to claim 4, wherein the temperature expectation value is determined as a function of all detected first temperatures except the one which is compared with the temperature expectation value, and / or as a function of all detected second temperatures except the one which is compared with the temperature expectation value, in particular as an average value. [7] Method according to any one of the preceding claims, further comprising: Determine (S101) for first controllable semiconductor switching elements (1a) that do not have a first temperature sensor (4a), a first estimated temperature of the first controllable semiconductor switching element (1a) as a function of the first temperature, and Determine (S101) a second estimated temperature of the second controlled semiconductor switching element (1b) as a function of the second temperature for a second controllable semiconductor switching element (1b) that does not have a second temperature sensor (4b). [8] Method according to claim 7, wherein the first estimating temperature and / or the second estimating temperature are determined by analytical equations obtained from thermal models. [9] Method according to claim 7 or 8, further comprising: Determine (S111) that a fault exists in the converter circuit (1, 1') if the first estimated temperature and / or the second estimated temperature deviate from the expected temperature value by more than the temperature deviation threshold. [10] Method according to any one of claims 7 to 9, wherein the expected temperature value is determined as an average. - all initial temperatures and estimated temperatures, - all initial temperatures and estimated temperatures except the one that is compared with the expected temperature value, - all second temperatures and estimated temperatures, - all second temperatures and estimated temperatures except the one that is compared with the expected temperature value, - all first and second temperatures and estimated temperatures, or - all first and second temperatures and estimated temperatures except the one that is compared with the expected temperature value. [11] Power converter control unit (10) configured to perform all process steps of a process according to any of the preceding claims. [12] Converter arrangement (100, 100') comprising a converter control unit (10) according to claim 11 and at least one converter circuit (1, 1') comprising at least one converter circuit (1, 1'): - a low side comprising several first controllable semiconductor switching elements (1a) connected in parallel to each other between a first DC voltage terminal (3a) and a center terminal (3c) of the converter circuit (1, 1'), - a high side having several second controllable semiconductor switching elements (1b) connected in parallel to each other between a second DC voltage terminal (3b) and the center terminal (3c) of the converter circuit (1, 1'), - a first temperature sensor (4a) arranged on one of the several first controllable semiconductor switching elements (1a) and configured to measure a first temperature, - a second temperature sensor (4b) arranged on one of the several second controllable semiconductor switching elements (1b) and configured to measure a second temperature. [13] Power converter arrangement (100, 100') according to claim 12, wherein the first controllable semiconductor switching elements (1a) and / or the second controllable semiconductor switching elements (1b) are transistors, in particular metal oxide semiconductor field-effect transistors or IGB transistors. [14] Power converter arrangement (100') according to claim 12 or 13, wherein several, in particular all, first controllable semiconductor switching elements (1a) have a first temperature sensor (4a) and / or several, in particular all, second controllable semiconductor switching elements (1b) have a second temperature sensor (4b).

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