Switching arrangement with a switching element, and method for controlling a switching element

Abstract

A switching arrangement for an electric drive system of a vehicle is described, wherein the switching arrangement comprises a semiconductor-based switching element with a control port. The switching element is configured to be switched to the open or closed state by a control current flowing into or out of the control port via a line. The switching arrangement further comprises a control resistor arranged on the line, wherein the control resistor has a temperature-dependent resistance value.

Description

[0001] The invention relates to a method designed to control a semiconductor-based switching element, in particular a switching element of an electric drive of a vehicle. Furthermore, the invention relates to a switching arrangement with a semiconductor-based switching element.

[0002] An electrically powered vehicle has at least one electric drive motor, e.g., a current-excited synchronous machine. The multiphase alternating current required to operate the electric drive motor can be generated from the direct current supplied by the vehicle's electrical energy storage system using an inverter. The inverter typically has several semiconductor-based switching elements, especially MOSFETs.

[0003] This document addresses the technical challenge of enabling efficient and EMC (electromagnetic compatibility) compliant control of a semiconductor-based switching element.

[0004] The problem is solved by each of the independent claims. Advantageous embodiments are described, inter alia, in the dependent claims. It should be noted that additional features of a claim dependent on an independent claim, without the features of the independent claim itself or only in combination with a subset of the features of the independent claim, can constitute a separate invention independent of the combination of all features of the independent claim, which can be made the subject of an independent claim, a divisional application, or a subsequent application. This applies equally to technical teachings described in the description, which can constitute an invention independent of the features of the independent claims.

[0005] According to one aspect, a switching arrangement for an electric drive system of a (motor) vehicle is described. The drive system may include an inverter configured to generate the phase voltages and / or phase currents for an electric drive motor of the drive system based on a DC voltage. The inverter may comprise one or more of the switching arrangements described in this document.

[0006] The switching arrangement comprises a semiconductor-based switching element with a control port. The switching element can be a MOSFET, in particular a silicon carbide MOSFET. The control port can be a gate of the switching element. The switching element is configured to be switched to the open or closed state by a drive current flowing into or out of the control port via a line. For example, a drive current into the control port can cause the switching element to be switched to the closed state. Conversely, a drive current out of the control port can cause the switching element to be switched to the open state. Optionally, the mapping between the polarity of the drive current and the state of the switching element can be exactly reversed.

[0007] The switching arrangement further comprises a control resistor, in particular a gate resistor, arranged on the line. The control resistor has a temperature-dependent resistance value. In particular, the control resistor is preferably designed such that its resistance value decreases with increasing temperature. The control resistor can, in particular, be a negative temperature coefficient (NTC) resistor.

[0008] By using a temperature-dependent control resistor, energy-efficient and EMC-compliant operation of the switching element can be reliably achieved.

[0009] The control resistor can have a (predefined and known) temperature characteristic curve that specifies the resistance value as a function of temperature (generally as a function of the temperature specified by the temperature information). The temperature characteristic curve can have a gradient that, within a predefined temperature range, particularly between -40°C and 200°C, is always greater than 1% / degree, and in particular greater than 2% / degree. Alternatively or additionally, the resistance value of the control resistor can change with temperature, particularly on average or always (within the predefined temperature range), by at least 1% / degree, and in particular by at least 2% / degree, and in particular decrease with increasing temperature.

[0010] This allows for particularly energy-efficient and EMC-compliant operation of the switching element.

[0011] The switching element and the control resistor can form a single power module. For example, the switching element and the control resistor can be arranged on a common circuit board and / or in a common housing. The switching element and the control resistor can be arranged, for example, such that the temperature of the switching element and the temperature of the control resistor always differ from each other by no more than 20%, and in particular by no more than 10%. This ensures particularly reliable operation of the switching element.

[0012] The switching arrangement can include a control device (e.g., a gate driver) configured to control the drive current via the power supply to the control resistor. The control device can be configured to detect temperature information relating to the temperature of the switching element, the temperature of the control resistor, the temperature of the coolant used to cool the switching element, and / or the temperature of the stator of the electric machine in the vehicle's electric drive system. The drive current, and in particular the slew rate of the drive current and / or the switching element, for switching the switching element can then be controlled based on this temperature information.Alternatively or additionally, the control device can be configured to adjust the control current, in particular the slew rate of the control current and / or the switching element, to switch the switching element depending on the predefined temperature characteristic of the control resistor. This allows for particularly energy-efficient, EMC-compliant operation of the switching element.

[0013] The temperature characteristic of the control resistor can specify its resistance value as a function of the temperature indicated by the temperature information. The control device can be configured to determine the current resistance value of the control resistor based on this temperature information. Furthermore, the control device can be configured to determine the drive current (in particular, the slew rate of the drive current and / or the switching element) for a switching operation of the switching element, depending on the determined resistance value of the control resistor. By considering the temperature characteristic of the control resistor when determining the drive current (in particular, the slew rate of the drive current and / or the switching element), particularly efficient and EMC-compliant operation of the switching element can be achieved.

[0014] According to another aspect, an inverter for an electric drive system of a (motor) vehicle is described. The inverter can include at least one switching arrangement configured as described in this document. The switching arrangement can be used (e.g., as part of a half-bridge) to generate an alternating voltage from a direct current for the operation of an electric machine of the vehicle's drive system.

[0015] According to another aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described that includes the switching arrangement and / or the inverter described in this document.

[0016] According to one aspect, a method for controlling a semiconductor-based switching element of an electric drive system of a (motor) vehicle is described, wherein the switching element has a control port, and wherein the switching element is configured to be switched to the open state or to the closed state by a control current flowing into or out of the control port via a line with a control resistor.

[0017] The method involves determining temperature information related to the temperature of the switching element and / or the control resistor. Furthermore, the method includes generating the control current to switch the switching element based on this temperature information.

[0018] It should be noted that the aspects described in connection with the device, in particular the claims described in connection with the device, are also applicable to the method as corresponding process features.

[0019] Another aspect described is a software (SW) program. The SW program can be configured to run on a processor (e.g., on a vehicle's control unit) and thereby execute the procedure described in this document.

[0020] Another aspect describes a storage medium. This storage medium can include a software program configured to run on a processor and thereby execute the procedure described in this document.

[0021] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspect of the methods, devices, and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways. Features listed in parentheses are to be understood as optional features.

[0022] The invention will now be described in more detail using exemplary embodiments. Fig. 1a Exemplary components of a vehicle with an electric drive motor; Fig. 1b an exemplary inverter with an electric machine; Fig. 2a an exemplary switching arrangement with a switching element and with a control resistor; Fig. 2b an exemplary temperature characteristic curve of a control resistor; and Fig. 3 a flowchart of an exemplary procedure for controlling a semiconductor-based switching element.

[0023] As stated at the beginning, this document deals with the efficient and EMC-compliant control of a semiconductor-based switching element. In this context, it shows Fig. 1a Exemplary components of a vehicle 140, which includes an electric machine 103 for propelling the vehicle 140. The electric machine 103 is coupled to one or more wheels 141 of the vehicle 140 to drive the one or more wheels 141 and thus the vehicle 140. The electric machine 103 is operated with electrical energy from an electrical, in particular an electrochemical, energy storage device 130. The energy storage device 130 can be configured to provide a direct current with a specific direct voltage (e.g., of 300 V or more).

[0024] The vehicle 140 has an inverter 100, which is configured to generate phase currents for the different phases of the electric machine 103 based on the direct current from the energy storage device 130. The inverter 100 can be operated by a (control) device 101. The (control) device 101 can be integrated into the inverter 100. The inverter 100 and the electric machine can be part of the electric drive or the electric drive system of the vehicle 140.

[0025] Fig. Figure 1b shows an exemplary inverter 100 configured to generate phase voltages 111 (i.e., alternating voltages) for the inductors of the electric machine 103 based on an intermediate circuit voltage 110 (i.e., a DC voltage). The drive may further include an intermediate circuit 105 with an intermediate circuit capacitor to which the intermediate circuit voltage 110 is applied.

[0026] The inverter 100 comprises several switching elements 102, 104, which in the illustrated example are arranged in a half-bridge for each phase 121, 122, 123. The switching elements 102, 104 are controlled by the (control) device 101 to generate the phase voltages 111 for the electric machine 103. The individual phase currents 112 and / or phase voltages 111 can be supplied to the electric machine 103 via corresponding phase lines. Fig. Figure 1b shows an example of a 2-level inverter. It should be noted that the measures described in this document are generally applicable to an N-level inverter, with N ≥ 2.

[0027] Fig. Figure 2a shows an exemplary switching arrangement 200 with a (semiconductor-based) switching element 203, 102, 104 (of the inverter 100). The switching element 203 has a control port G (in particular a gate) via which the switching element 203 can be controlled to switch it to the open or closed state. In the open state, the two switching ports D, S (in particular drain and source) are separated from each other, so that no current can flow between the switching ports. The open state can also be referred to as the non-conductive state of the switching element 203. Conversely, in the closed state, the two switching ports D, S are connected to each other, so that a current can flow between the switching ports. The closed state can also be referred to as the conductive state of the switching element 203.

[0028] The switching arrangement 200 comprises a control device 201 (in particular a gate driver) which is configured to effect a turn-on current (generally a drive current) into the control port G, by which the switching element 203 is transferred from the open state to the closed state.

[0029] Furthermore, a switching current (generally a control current) can be applied from the control port G, which changes the switching element 203 from the closed state to the open state. It should be noted that the relationship between the polarity of the control current and the state of the switching element 203 brought about by the control current can be exactly reversed.

[0030] The slew rate of the switch-on and switch-off current, and thus the switching speed of the switching element 203, typically depends on the resistance value of the control resistor 202 (in particular the gate resistor), which is located on the line between the control device 201 and the control port G. Typically, a decreasing resistance value of the control resistor 202 increases the slew rate and thus the switching speed of the control resistor 202, and / or an increasing resistance value of the control resistor 202 typically decreases the slew rate and thus the switching speed.

[0031] The switching losses of the switching element 203 typically decrease with increasing switching speed, so it is advantageous with regard to switching losses to use a control resistor 202 with the smallest possible resistance value. On the other hand, the use of an inrush or switch-off current with a relatively high slew rate typically leads to relatively strong electromagnetic emissions, which can impair the EMC compliance of the switching element 203.

[0032] It has been shown that (with a constant slope of the switching current and / or the switching element) the electromagnetic emissions decrease with increasing temperature of the switching element 203. Efficient and EMC-compliant operation of the switching element 203 can therefore be achieved by reducing the resistance of the control resistor 202 as the temperature of the switching element 203 increases. This can be achieved efficiently and reliably by using a control resistor 202 with a temperature-dependent resistance value, in particular a negative temperature coefficient (NTC) resistor.

[0033] The temperature-dependent control resistor 202 can be directly integrated into a common power module 205 with the switching element 203. The power module 205 can, for example, have a common housing that encloses the switching element 203 and the control resistor 203. Integration into a common power module 205 ensures that the temperature of the control resistor 202 essentially corresponds to the temperature of the switching element 203.

[0034] Fig. Figure 2b shows an example temperature characteristic curve 210 of the control resistor 202. The temperature characteristic curve 210 specifies the resistance value 212 of the control resistor 202 as a function of the temperature 211 of the control resistor 202. The temperature characteristic curve 210 can exhibit a specific (negative) temperature gradient, which indicates how much the resistance value 212 changes per unit of temperature (e.g., per degree Celsius). The temperature gradient can be, for example, 1% / degree or more, or 2% / degree or more, or 5% / degree or more.

[0035] The gate resistor 202 can thus be replaced by a temperature-dependent resistor and can preferably be integrated into the power module 205 with the switching element 203. In this way, a higher resistance value 212 of the gate resistor 202 can be achieved when the switching element 203 is cold (to limit electromagnetic emissions) by using an NTC resistor 202. Furthermore, when the switching element 203 is warm, relatively fast and energy-efficient switching operations of the switching element 203 can be achieved (by using a gate resistor 202 with a relatively low resistance value 212). In this way, EMC emissions can be advantageously managed. The temperature-dependent change of the resistance value 212 can be achieved by a single component (i.e., by a single gate resistor 202), so that a compact power module 205 can be provided and / or so that space on the circuit board of the power module 205 can be saved.

[0036] It should be noted that the switch-on and / or switch-off current for the switching element 203 can be adjusted by the control device 201. In particular, the slew rate of the switch-on and / or switch-off current (or of the switching element) can be changed to alter the switching speed of the switching element 203. The control device 201 can be configured to take into account the temperature 211 of the switching element 203 and / or the temperature characteristic 210 of the control resistor 202 when setting the switch-on and / or switch-off current for the switching element 203. This allows for particularly efficient, EMC-compliant operation of the switching element 203.

[0037] Fig.Figure 3 shows a flowchart of a (possibly computer-implemented) method 300 for controlling a semiconductor-based switching element 203 of an electric drive system of a (motor) vehicle 140, wherein the switching element 203 has a control port G, and wherein the switching element 203 is configured to be switched to the open state or to the closed state by a control current flowing into or out of the control port G via a line with a control resistor 202. The control resistor 202 can have a temperature-dependent or (alternatively) a substantially temperature-independent resistance value 212.

[0038] Method 300 comprises determining 301 temperature information relating to the temperature 211 of the switching element 203 and / or the control resistor 202. The temperature information, in particular the temperature 211, can be determined from sensor data of a temperature sensor and / or from an operating model of the switching element 203.

[0039] Furthermore, the method 300 includes generating 302 the control current for switching the switching element 203 as a function of the temperature information. The control current can be generated such that the slew rate of the control current (or of the switching element) for inducing a switching operation of the switching element 203 increases with increasing temperature (of the switching element 203) and / or decreases with decreasing temperature (of the switching element 203).

[0040] When determining the control current (in particular the slew rate of the control current and / or the switching element) for a switching operation of the switching element 203, the (predefined and / or known) temperature characteristic 210 of the control resistor 202 (in conjunction with the temperature indicated by the temperature information) can be taken into account. This allows for particularly efficient and EMC-compliant operation of the switching element 203.

[0041] The measures described in this document can achieve a particularly efficient and EMC-compliant operation of a semiconductor-based switching element 203.

[0042] When using a control resistor 202 with a temperature-dependent resistance value, particularly an NTC resistor, the drive current (especially the slew rate) for a switching operation of the switching element 203, induced by the control device (especially the gate driver), may be independent of the temperature and / or temperature information (since the desired temperature dependence (i.e., the temperature characteristic) is already implemented in the control resistor 202). A constant and / or uniform drive current, especially with a constant and / or uniform slew rate, may be induced by the control device. The temperature-dependent change in the effective drive current (especially the slew rate of the effective drive current and / or of the switching element) at the control port of the switching element may then (if applicable)This can be achieved solely through the temperature dependence of the resistance value of the control resistor. This allows for particularly efficient control of the switching element.

[0043] On the other hand, when using a control resistor 202 with a (essentially) temperature-independent resistance value, the control current (in particular the slew rate of the control current and / or the switching element) caused by the control device can be determined depending on the temperature information.

[0044] In a particularly advantageous embodiment, the control current (especially the slew rate of the control current and / or the switching element) induced by the control device can be determined as a function of the temperature information and / or as a function of the temperature characteristic of the (temperature-dependent) control resistor. This allows the efficiency of the switching operations of the switching element to be significantly increased.

[0045] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and the figures are intended only to illustrate the principle of the proposed methods, devices, and systems by way of example.

Claims

[1] Switching arrangement (200) for an electric drive system of a vehicle (140); wherein the switching arrangement (200) comprises, - a semiconductor-based switching element (203) with a control port (G); wherein the switching element (203) is configured to be switched to an open state or a closed state by a control current flowing into or out of the control port (G) via a line; and - a control resistor (202) arranged on the line; wherein the control resistor (202) has a temperature-dependent resistance value (212). [2] Switching arrangement (200) according to claim 1, wherein - the switching element (203) and the control resistor (202) form a common power module (205); and / or - the switching element (203) and the control resistor (202) are arranged on a common circuit board and / or in a common housing; and / or - the switching element (203) and the control resistor (202) are arranged such that the temperature (211) of the switching element (203) and the temperature (211) of the control resistor (202) differ from each other by no more than 20%, in particular by no more than 10%. [3] Switching arrangement (200) according to one of the preceding claims, wherein - the control resistor (202) is designed such that the resistance value (212) of the control resistor (202) decreases with increasing temperature (211); and / or - the control resistor (202) is a Negative Temperature Coefficient, NTC, resistor. [4] Switching arrangement (200) according to one of the preceding claims, wherein - the control resistor (202) has a temperature characteristic curve (210) which specifies the resistance value (212) as a function of the temperature (211); and - the temperature characteristic curve (210) has a gradient which, in a predefined temperature range, in particular between -40°C and 200°C, is always greater in magnitude than 1% / degree, in particular than 2% / degree. [5] Switching arrangement (200) according to one of the preceding claims, wherein the resistance value (212) of the control resistor (202) changes, in particular on average or always, by at least 1% / degree, in particular by at least 2% / degree, with the temperature (211), in particular reducing. [6] Switching arrangement (200) according to one of the preceding claims, wherein - the switching element (203) is a MOSFET, in particular a silicon carbide MOSFET; and / or - the control port (G) is a gate of the switching element (203); and / or - the control resistor (202) is a gate resistor. [7] Switching arrangement (200) according to one of the preceding claims, wherein the switching arrangement (200) comprises a control device (201) which is configured to effect the control current via the power with the control resistor (202). [8] Switching arrangement (200) according to claim 7, wherein the control device (201) is configured, - To determine temperature information relating to a temperature (211) of the switching element (203) and / or the control resistor (202); and - to effect the control current for switching the switching element (203) depending on the temperature information. [9] Switching arrangement (200) according to one of claims 7 to 8, wherein - the control device (201) is configured to effect the control current for switching the switching element (203) depending on a predefined temperature characteristic (210) of the control resistor (202); and - the temperature characteristic curve (210) indicates the resistance value (212) of the control resistor (202) as a function of the temperature (211) of the control resistor (202). [10] Inverter (100) for an electric drive system of a vehicle (140); wherein the inverter (100) comprises at least one switching arrangement (200) configured according to one of the preceding claims and which is used to generate an alternating voltage (111) for the operation of an electric machine (103) of the drive system of the vehicle (140) on the basis of a DC voltage (110). [11] Method (300) for controlling a semiconductor-based switching element (203) of an electric drive system of a vehicle (140); wherein the switching element (203) has a control port (G); wherein the switching element (203) is configured to be switched to an open state or to a closed state by a control current flowing into or out of the control port (G) via a line with a control resistor (202); wherein the method (300) comprises, - Determining (301) temperature information relating to a temperature (211) of the switching element (203) and / or the control resistor (202) and / or a coolant for cooling the switching element (203) and / or an electric machine (103) of the vehicle's electric drive system (140); and - Causing (302) the control current to switch the switching element (203) depending on the temperature information.

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