Method and device for heating a component

Abstract

Method (400) for heating a component (10), wherein the component (10) is connected to a common cooling circuit (80) with an electric drive (20) for cooling; with a controller (30) for controlling power electronics (40) of the electric drive (20) to set a positive or negative target torque (50); with the steps: Determining (420) a temperature (T); Comparing (430) the temperature (T) with a temperature threshold (TS); Operating (440) the power electronics (40) while maintaining the target torque (50) with increased power loss of the electric drive (20) if the determined temperature (T) is lower than the temperature threshold value (TS), characterized in that the electric drive comprises a separately excited machine with an excitation coil which is supplied with an excitation current by means of a switching bridge, and that the operation (440) of the power electronics (40) while maintaining the target torque (50) with increased power loss of the electric drive (20) comprises an increase (446) of the losses of the excitation coil, wherein in order to increase the losses in the excitation coil, a switching frequency of the switching bridge is reduced or the excitation current is increased.

Description

[0001] The invention relates to a method and a device for heating a component, wherein the component is connected to a common cooling circuit with power electronics or an electric drive. Furthermore, the invention relates to a drive train with a corresponding device and a vehicle with a drive train, as well as a computer program and a machine-readable storage medium. State of the art

[0002] Electric vehicles for road traffic are well known in the art. They place high demands on the available continuous and peak power, as well as on the efficiency of the electric drive. It is common practice to operate the electric drive in torque control mode. This means that the vehicle control system specifies a target value for the torque provided by the electric motor. This target torque can be either motor-driven (i.e., driving) or generator-driven (i.e., braking). Current control determines the current required to set the required torque depending on the operating point.

[0003] It is well known that a battery, especially a high-voltage battery, is used as an energy source for electric drive. A widely used battery technology is based on lithium-ion. The maximum drawable current from the battery depends on the battery temperature. At low temperatures, the maximum drawable current is lower than at operating temperature. Therefore, rapid warming of the battery to operating temperature is desired. Various methods for heating the battery are known.

[0004] For example, the batteries are heated using an electric heater, in particular a PTC heater. The heating output of such a heater is limited due to installation space, costs, and limited heat transfer to the battery. Therefore, there is a need for alternative methods and devices for heating components in a vehicle. German Patent Application DE 10 2011 115 823 A1 relates to a method for operating an electrical component of a motor vehicle that is thermally coupled to a coolant circuit of the motor vehicle for temperature control. The electrical component is operated in a first operating mode if its temperature falls below a predetermined limit, and in a second operating mode if its temperature falls below the predetermined limit.In the second operating mode, the electrical component is operated in such a way that it generates a higher power loss than in the first operating mode. The document DE 10 2011 012 723 A1 describes a cooling system for a mobile work machine for regulating the temperature of an electrical energy storage device and at least one power electronics unit of the mobile work machine. A controller is provided which activates the power electronics unit in such a way that the power electronics unit generates an increased power loss. The patent document DE 102 30 941 B4 discloses a method for regulating the operating temperature of an internal combustion engine. In this process, lost heat is transferred to a coolant in a coolant circuit of the internal combustion engine. The document DE 10 2011 115 279 A1 relates to a drive arrangement for a motor vehicle, having at least one electric motor, wherein the electric motor has a cooling circuit with a cooling medium.The idea is to operate the electric motor with higher power loss in certain operating situations. Document EP 2 556 989 A1 discloses increasing the power loss within an electric motor by reducing the switching frequency of the electric machine's converter. Disclosure of the invention

[0005] A method is provided for heating a component, wherein the component is connected or linked to a common cooling circuit with an electric drive for cooling. Furthermore, a controller is provided for controlling the power electronics of the electric drive to set a positive or negative target torque. The method comprises the steps of: determining a temperature; comparing the temperature with a temperature threshold; and operating the power electronics while maintaining the target torque with increased power loss of the electric drive if the determined temperature is lower than the temperature threshold.

[0006] A method for heating a component is provided. For this purpose, the component is connected or linked to a common cooling circuit. This means that a common cooling circuit is present, the coolant of which is passed past both the component and an electric drive for cooling. In particular, the power electronics are designed as an inverter, power converter or pulse-controlled inverter. In particular, the electric drive is designed as an electric machine, a synchronous or asynchronous machine. A cooling circuit with a coolant is provided, which serves to cool the connected parts or components and enhances heat exchange between the connected parts or components. Furthermore, a controller is provided for carrying out the method, which controller also serves to actuate the power electronics of the electric drive to set a positive or negative target torque.To carry out the method for heating a component, a temperature is first determined and this temperature is compared with a temperature threshold. In particular, a temperature is determined that correlates with the temperature of the component. If the determined temperature falls below the temperature threshold or the determined temperature is lower than the temperature threshold, and thus the component in particular presumably has a temperature that is below a desired operating temperature, the power electronics are controlled in such a way that the electric drive is operated with increased power loss. During operation with increased power loss, the requested target torque is still set and maintained. The increased power loss of the electric drive is introduced into the cooling circuit as heat via the coolant and is at least partially absorbed by the still cooler component.Thus, the component to be heated is heated by the coolant of the cooling circuit. This advantageously provides an alternative method for heating a component. This eliminates the need for an additional heating element, thus saving installation space.

[0007] By heating the coolant, the component to be heated reaches its ideal temperature more quickly and is therefore ready for use and available more quickly.

[0008] In another embodiment of the invention, determining the temperature comprises reading a temperature sensor. This temperature sensor directly or indirectly detects the coolant temperature of the cooling circuit or, in particular, of the component to be heated.

[0009] The method for heating a component includes determining a temperature. For this purpose, a signal from a temperature sensor is detected and read by the controller. The temperature sensor is arranged on or near the cooling circuit in such a way that this sensor directly or indirectly detects the coolant temperature or the temperature of the component to be heated. Advantageously, a temperature is determined that correlates with the temperature of the component to be heated, which is connected to the cooling circuit, in particular thermally.

[0010] In another embodiment of the invention, the component comprises an energy source, for example a battery, high-voltage battery, fuel cell, or capacitor. This energy source is particularly configured to supply the electric drive with electrical energy.

[0011] The component to be heated comprises or is an energy source. This energy source is, for example, a battery or a fuel cell, and serves in particular to supply the electric drive with electrical energy. Advantageously, a method for heating an energy source is thus provided that, due to the heating after commissioning, reaches its maximum performance or can deliver the maximum current more quickly.

[0012] In a configuration not according to the invention, operating the power electronics while maintaining the target torque with increased power loss of the power electronics involves shifting the operating point of the power electronics. In particular, this shift in the operating point involves an Id / Iq shift, which causes an increase in the currents in the electric machine.

[0013] Operation of the power electronics with increased power loss while simultaneously maintaining the target torque is achieved by shifting the operating point of the power electronics. For this purpose, a shift of the Id / Iq vectors of the pulse-width modulated control of the power electronics can be used while maintaining the target torque. Control using Id / Iq vectors is known from space vector modulation (SVPWM) or vector control of synchronous or asynchronous machines. A shift of the Id / Iq components is selected such that an increase in the currents in the electrical machine results while the target torque is maintained. This also increases the currents in the power electronics and leads to increased line losses in the power electronics. Methods are advantageously provided for operating the power electronics with increased power loss while maintaining the target torque.

[0014] In an embodiment of the invention not according to the invention, the operation of the power electronics while maintaining the target torque with increased power loss of the power electronics comprises a modified control of the power electronics.

[0015] Operation of the power electronics with increased power loss while simultaneously maintaining the target torque is achieved by means of a modified control system. To increase switching losses in the power electronics, for example, the switching frequency of the inverter's switching elements is increased. For this purpose, a modified control system of the power electronics is used accordingly, for example, an increase in the switching frequency from, for example, the typical 10 kHz to, for example, 15 or 20 kHz and / or a change in the control system to a comparatively lossy modulation method, such as space vector pulse width modulation (SVPWM). Due to the increased switching frequency, these modified control systems of the power electronics exhibit higher switching losses than the otherwise preferred low-loss control methods or modulation methods.Typically, control methods for power electronics are used to operate a vehicle, which minimize electrical losses in the power electronics and / or the electric drive, thus achieving the greatest possible range with limited energy consumption. Methods with low switching losses include flat-top or block commutation. Advantageously, methods are provided that allow the power electronics to operate with increased power loss while maintaining the target torque.

[0016] In another embodiment of the invention, the operation of the power electronics while maintaining the target torque with increased power loss of the electric drive comprises an increase in the magnetic losses of the electric drive or an increase in the currents through the electric drive, in particular an increase in the currents through the stator of an electrical machine of the electric drive.

[0017] Operating the power electronics while maintaining the target torque with increased power loss of the electric drive is achieved by increasing the magnetic losses within the electric drive, particularly within the electric machine. The goal of pulse-width modulated control of the power electronics is to generate phase voltages that are as sinusoidal as possible to supply the electric drive from a DC voltage. Depending on the control of the power electronics, this generates a control-specific frequency spectrum of the currents or phase currents. The fundamental wave of the generated current determines the target torque to be delivered by the electric drive. The parasitic harmonics lead to magnetic losses and, at low speeds, can cause uncomfortable, uneven rotation of the electric machine.By reducing the switching frequency and thus the switching frequency during pulse width modulation, increased harmonics arise when the sinusoidal current is generated. The currents exhibit increased ripple compared to an ideal sinusoidal oscillation and lead to increased magnetic losses in the electrical machine. The switching frequency can be reduced by reducing the switching frequency or by changing the control method, for example, switching from space vector pulse width modulation to flat-top or block commutation. Reducing the switching frequency is particularly useful at high electrical machine speeds, since reducing the switching frequency at low electrical machine speeds can lead to uncomfortable, uneven rotation of the electrical machine.

[0018] Alternatively or additionally, the currents supplying the electric machine of the electric drive, the currents through the electric machine, or the currents through the stator can be increased while simultaneously maintaining the target torque by shifting the Id / Iq components of the space vector modulation (SVPWM). Due to the higher currents, greater conduction losses occur in the windings of the electric drive. Shifting the Id / Iq components of the space vector modulation leads to increased losses in the electric machine across the entire speed range of the electric machine. In particular, shifting the Id / Iq components of the space vector modulation has no effect on the smooth running of the electric machine.

[0019] In separately excited electrical machines, the power electronics can be operated while maintaining the target torque with increased power loss of the electric drive by increasing the currents through the stator of an electrical machine of the electric drive by reducing the excitation current and the magnetic flux. To maintain the target torque, the power electronics are operated in such a way that the current through the stator increases. The increase in current leads to increased conduction losses in the coils of the stator of the electrical machine. The stator is usually integrated into the cooling circuit so that the increased heat input can be transferred to the component to be heated.

[0020] According to the invention, losses of an excitation coil of a separately excited electrical machine and its control are deliberately increased while maintaining the target torque. An excitation coil is supplied with an excitation current via a switching bridge. To increase the control losses, for example, the switching frequency is also increased, in particular by increasing the switching frequency. To increase the magnetic losses of the excitation coil in the electrical machine, the switching frequency is reduced according to the invention to generate harmonics. Alternatively, the excitation current is also increased according to the invention to generate higher line losses in the excitation coil. While maintaining the target torque, a control of the power electronics adapted to the changed control of the excitation coil also leads to increased losses.

[0021] Advantageously, methods are provided to operate the power electronics with increased power loss of the electric drive while maintaining the target torque.

[0022] In another embodiment of the invention, the method comprises a further step: operating the power electronics while maintaining the target torque with reduced power loss of the power electronics or the electric drive if the determined temperature is greater than the temperature threshold.

[0023] The power electronics are operated with reduced power loss of the power electronics or the electric drive if the detected temperature exceeds the temperature threshold or if the detected temperature is greater than the temperature threshold. This occurs while maintaining the target torque, in particular by changing the control of the power electronics so that the losses in the power electronics and / or the electric drive are minimized. Advantageously, a method for heating a component is provided in which further active heating of the component to be heated is avoided after a temperature threshold or operating temperature has been reached.

[0024] Furthermore, the invention relates to a computer program which is designed to carry out the methods described so far.

[0025] Furthermore, the invention relates to a machine-readable storage medium on which the described computer program is stored.

[0026] The invention further relates to a device for heating a component, wherein the component is connected to a common cooling circuit with an electric drive for cooling. The device further comprises a controller for controlling the power electronics of the electric drive to set a positive or negative target torque. The controller is configured to determine a temperature, compare the temperature with a temperature threshold, and operate the power electronics while maintaining the target torque with increased power loss of the electric drive if the determined temperature is lower than the temperature threshold.

[0027] A device for heating a component is provided. For this purpose, the component is connected or linked to a common cooling circuit. This means that a common cooling circuit is present, the coolant from which is passed both past the component and past an electric drive for cooling. A cooling circuit with a coolant is provided, which serves to cool the connected parts or components and intensifies heat exchange between the connected parts or components. Furthermore, the device comprises a controller, which also serves to control the power electronics of the electric drive to set a positive or negative target torque. To heat a component, the controller first determines a temperature and compares it with a temperature threshold. In particular, a temperature is determined that correlates with the temperature of the component.If the detected temperature falls below the temperature threshold or the detected temperature is lower than the temperature threshold, and the component is therefore presumably at a temperature below a desired operating temperature, the power electronics are activated by the controller in such a way that the electric drive is operated with increased power loss. During operation with increased power loss, the requested target torque is still set and maintained. Thus, the component to be heated is heated via the coolant in the cooling circuit. Advantageously, a device for heating a component is provided. This does not require an additional heating element, thus saving installation space. By heating the coolant, the component to be heated becomes available more quickly.

[0028] The invention further relates to a drive train comprising a component and a described device, and in particular comprising an electric drive. Such a drive train serves, for example, to drive an electric vehicle. The method and device enable safe operation of the drive train.

[0029] The invention further relates to a vehicle having a described drive train. Advantageously, a vehicle is thus provided that includes a device with which a component can be heated.

[0030] It is understood that the features, properties and advantages of the method according to the invention apply or are applicable accordingly to the device or the drive train and the vehicle and vice versa.

[0031] Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings. Short description of the drawing

[0032] In the following, the invention will be explained in more detail with reference to some figures, which show: Fig. 1 a schematic representation of a device with a control for heating a component, Fig. 2 a schematically illustrated vehicle with a drive train, Fig. 3 a schematic flow diagram for a method for heating a component. Embodiments of the invention

[0033] The Fig. 1 shows a device 100 for heating a component 10. The component 10 is connected to a common cooling circuit 80 with an electric drive 20. The coolant 70 is located within the cooling circuit and is transported, for example, by means of a pump (not shown in the drawing). In particular, it is advantageous, during a warm-up phase, to separate the cooling circuit 80 from any existing cooling circuit section with a heat exchanger or cooler (not shown in the drawing), for example by means of a valve, in order to quickly heat the coolant 70. A controller 30 is provided for controlling the power electronics 40. Depending on a positive or negative target torque 50, the controller 30 controls the power electronics 40 so that the electric drive 20 connected to it sets and delivers the desired torque.A temperature sensor 60 detects a temperature which characterizes the coolant temperature KT of the cooling circuit 80 or, for example, the temperature of the component 10 to be heated. This temperature sensor therefore advantageously does not have to be attached directly to the cooling circuit or the electrical component 10. The controller 30 determines the temperature T by reading the signal from the temperature sensor 60. The temperature T is compared with a predefinable temperature threshold value TS within the controller 30. If the determined temperature T is lower than the temperature threshold value TS, the controller 30 controls the power electronics 40 while maintaining the target torque 50 in such a way that the operation of the power electronics 40 takes place with increased power loss of the electric drive 20. Furthermore, the . Fig. 1 also shows an electric drive train 200 comprising the component 10, wherein the component 10 is in particular an energy source for the electric drive 20, and the device 100. In particular, the drive train comprises the electric drive 20.

[0034] Fig. 2 shows a schematically illustrated vehicle 300 with a drive train 200. The illustration shows, by way of example, a vehicle with four wheels 310, wherein the invention can be used equally in any vehicle with any number of wheels on land, on water and in the air.

[0035] The Fig.3 shows a schematic sequence of a method 400 for heating a component 10. The method begins with step 410. In step 420, a temperature T is determined. Subsequently, in step 430, the determined temperature T is compared with a temperature threshold value TS. If the determined temperature T is less than the temperature threshold value TS, the power electronics 40 are operated in step 440 such that, while maintaining the target torque 50, the electric drive 20 is operated with increased power loss. If the determined temperature T is greater than the temperature threshold value TS, the power electronics 40 are operated with reduced or minimal power loss of the power electronics 40 or the electric drive 20 while maintaining the target torque 50 in step 450. Operation with increased power loss in step 440 can be carried out in different ways.Steps 442, 444, and 446 are shown as examples. In step 442, the power electronics 40 are not operated with increased power loss according to the invention. This is achieved in particular by a targeted increase in the currents in the power electronics 40. An increase in the currents in the power electronics 40 can be achieved, for example, by shifting the operating point, i.e., the Id / Iq vectors of the vector control (SVPWM). Additionally or alternatively, in step 444, the power loss of the power electronics 40 is also increased by means of a modified control method. For example, instead of a control method with the lowest possible losses, in particular flat-top commutation or block commutation, a classic pulse width modulation with a comparatively high switching frequency is used.In particular, the switching frequency can be variably increased or doubled, for example from 10 to 20 kHz, for this purpose. In step 446, according to the invention, the power electronics 40 is controlled in such a way that increased power loss results in the electric drive 20, for example by increasing the harmonic component in the frequency spectrum. By means of these different measures, higher power losses result in the power electronics 40 and / or the electric drive 20, which in turn leads to heating of the coolant 70 in the cooling circuit 80. The heated coolant 70 in turn leads to faster heating of the component 10 or in particular of an energy source for the electric drive 20. The method ends with step 460.

[0036] In hybrid vehicles, for example, the internal combustion engine is started at very cold ambient temperatures. During the start-up phase, the exhaust catalyst is heated to reach the conversion temperature. This occurs through a load point shift between the electric motor and the internal combustion engine. Since a high air mass or exhaust mass is required for the catalyst heating strategy, the power of the internal combustion engine is actively increased. In order to adjust the torque required by the driver during this phase, the electric motor is operated as a generator. This phase, in which the electric motor of the electric drive 20 is operated as a generator, can be used for the Id / Iq shift and / or switching to a control method with increased power loss in order to bring the battery up to operating temperature more quickly.

Claims

[1] Method (400) for heating a component (10), wherein the component (10) is connected to a common cooling circuit (80) with an electric drive (20) for cooling; with a controller (30) for controlling power electronics (40) of the electric drive (20) to set a positive or negative target torque (50); with the steps: Determining (420) a temperature (T); Comparing (430) the temperature (T) with a temperature threshold (TS); Operating (440) the power electronics (40) while maintaining the target torque (50) with increased power loss of the electric drive (20) if the determined temperature (T) is lower than the temperature threshold value (TS), characterized by , that the electric drive comprises a separately excited machine with an excitation coil which is supplied with an excitation current by means of a switching bridge, and that the operation (440) of the power electronics (40) while maintaining the target torque (50) with increased power loss of the electric drive (20) comprises an increase (446) of the losses of the excitation coil, wherein in order to increase the losses in the excitation coil, a switching frequency of the switching bridge is reduced or the excitation current is increased. [2] Method (400) according to claim 1, wherein determining (420) the temperature (T) comprises reading a temperature sensor (60) which directly or indirectly detects a coolant temperature (KT) of the cooling circuit (80) or the temperature of the component (10) to be heated. [3] Method (400) according to one of the preceding claims, wherein the component (10) comprises an energy source and the energy source is configured to supply the electric drive (20) with electrical energy. [4] Method (400) according to one of the preceding claims characterized by that the operation (440) of the power electronics (40) while maintaining the target torque (50) with increased power loss of the electric drive (20) comprises an increase (446) of the magnetic losses of the electric drive (20) or an increase of the currents through the electric drive (20). [5] Method (400) according to one of the preceding claims, comprising the further step: Operating (450) the power electronics (40) while maintaining the target torque (50) with reduced power loss of the power electronics (40) or the electric drive (20) if the determined temperature (T) is greater than the temperature threshold value (TS). [6] Computer program arranged to carry out the method (400) according to any one of claims 1-5. [7] A machine-readable storage medium on which the computer program according to claim 6 is stored. [8] Device (100) for heating a component (10), wherein the component (10) is connected to a common cooling circuit (80) with an electric drive (20) for cooling; with a controller (30) for controlling the power electronics (40) of the electric drive (20) to set a positive or negative target torque (50); wherein the controller (30) is arranged to to determine a temperature (T), to compare the temperature (T) with a temperature threshold (TS); and to operate the power electronics (40) while maintaining the target torque (50) with increased power loss of the electric drive (20), if the determined temperature (T) is less than the temperature threshold (TS), characterized by , that the electric drive comprises a separately excited machine with an excitation coil which is supplied with an excitation current by means of a switching bridge, and that the operation (440) of the power electronics (40) while maintaining the target torque (50) with increased power loss of the electric drive (20) comprises an increase (446) of the losses of the excitation coil, wherein the controller (30) is additionally configured to reduce a switching frequency of the switching bridge or to increase the excitation current in order to increase the losses in the excitation coil. [9] Drive train (200) with a component (10) and a device (100) according to claim 8. [10] Vehicle (300) having a drive train (200) according to claim 9.

Images