Patent Application
20190389274
This application claims priority to German Patent Application No. DE 10 2018 210 034.9, filed on Jun. 20, 2018, the contents of which is hereby incorporated by reference in its entirety.
The invention relates to a method for digitally controlling a heating arrangement. The invention also relates to a heating arrangement for carrying out the method.
In modern fully-electric vehicles, ever more powerful electric heaters are employed. Accordingly, PTC heaters with a heating output of up to 8 kW can be used for example for heating the vehicle cabin, the battery or the electric motor. For controlling the electric heater, a communication signal with an 8-bit resolution is usually employed in modern vehicle electrical systems, which makes possible controlling the heating output in a maximum of 256 heating stages. Because of usually required further information—such as for example diagnosis—however, the 256 stages of an 8-bit signal cannot be entirely used for controlling the heating output. For this reason, few heating stages—typically 100 to 200—are often available for controlling the heating output. The respective heating stages differ by a fixed amount of the heating output. The more powerful the electric heater is, the greater is the amount of the heating output by which two consecutive heating stages differ. In the case of a powerful electric heater, the 8-bit resolution is often no longer sufficient in order to make possible a finer control of the electric heater. This can be disadvantageous in particular in the case of higher outside temperatures. Increasing the resolution of the communication signal to 16-bit or 32-bit is often out of the question because of standardised protocols in the vehicle electrical system.
The object of the invention therefore is to state a method and a heating arrangement with which the described disadvantages are overcome.
According to the invention, this object is solved through the subject of the independent claim(s). Advantageous embodiments are subject of the dependent claim(s).
A method according to the invention is provided for digitally controlling a heating arrangement, in particular a PTC heating arrangement, for a hybrid or an electric vehicle. There, a control device of the heating arrangement receives a temperature value reflecting a current outside temperature. Dependent on the received temperature value, the control device determines a limit output of the heating arrangement which is smaller than a maximum output of the heating arrangement. The control device then divides the determined limit output into output stages, the number of which corresponds to a digital resolution of the control device. Following this, the control device controls the heating arrangement between a minimum output and the limit output to one of the output stages.
The minimum output and the maximum output of the heating arrangement are defined by their physical characteristics and cannot be changed. Accordingly, the maximum output of the heating arrangement can be between 3 kW and 8 kW. The minimum output usually corresponds to zero. In the method according to the invention, the limit output of the heating arrangement is determined dependent on the received temperature value. The limit output can be smaller by a multiple than the maximum output of the heating arrangement. The control device then divides the determined limit output into the output stages, wherein because of the output being smaller compared with the maximum output the output stages consecutively following one another differ by a comparatively smaller value. Because of this, the heating arrangement can be more accurately controlled without the digital resolution of the heating arrangement having to be changed. Advantageously, the control device can divide the determined limit output of the heating arrangement into a maximum of 256 output stages corresponding to a digital resolution of 8-bit.
In the following, the method is explained by way of an example. All values mentioned here are exemplary and do not restrict the solution according to the invention. With a digital resolution of 8-bit, a heating arrangement with a maximum output equal to 8 kW can be controlled in 256 output stages. The consecutive output stages then differ by a value of approximately 31 W with 256 output stages. When fewer output stages are available for controlling the heating output, the consecutive output stages differ by a greater value. The heating arrangement can then be controlled in steps to the heating output equal to 0 W, 31 W, 62 W, 93 W and so forth up to 8 kW. When the limit output of the heating arrangement is set to 4 kW and the heating arrangement is controlled with a digital resolution of 8-bit, the consecutive output stages differ by a value of approximately 15.5 W. The heating arrangement can then be controlled in steps to the heating output equal to 0 W, 15.5 W, 31 W, 46.5 W and so forth up to 4 kW. In this advantageous manner, the heating output can be controlled more finely and accurately which can be advantageous in particular with higher outside temperatures.
In an advantageous further development of the method according to the invention it is provided that the control device compares the received temperature value with a threshold value. When the received temperature value is higher than the threshold value, the control arrangement sets the limit output smaller than the maximum output of the heating arrangement. When the received temperature value is smaller than the threshold value, the control arrangement sets the limit output equal to the maximum output of the heating arrangement. In this way, the heating arrangement can be operated for example in lower outside temperatures with the maximum output and in higher outside temperatures with the limit output that is smaller than the maximum output. Advantageously, the control device can adapt the heating behaviour of the heating arrangement to the outside temperature and to the current heat requirement in the motor vehicle because of this.
Advantageously it can be provided that the control device assigns the received temperature value to one of the multiple predefined temperature ranges. Here, one of the multiple predefined limit outputs corresponds to the respective predefined temperature range. Advantageously, the number of the multiple predefined temperature ranges and the multiple limit outputs can be between 2 and 4. Advantageously it can be provided that the respective predefined limit outputs differ from one another by an equal or unequal value. Alternatively or additionally, the respective predefined limit outputs of the heating arrangement can each amount to a fraction of the maximum output of the heating arrangement.
In a further development of the method it is provided that the control device, with a comparatively high temperature value, determines a comparatively small limit output of the heating arrangement. Here, the comparatively higher temperature value corresponds to a higher outside temperature. In the higher outside temperature, the heating arrangement need not usually be operated with the maximum output and the limit output can be correspondingly smaller. Because of this, the heating output of the heating arrangement, with ever higher outside temperatures, can be ever more finely adjusted and the heating behaviour of the heating arrangement accordingly adapted to the current heat requirement in the motor vehicle.
The invention also relates to a heating arrangement, in particular a PTC heating arrangement, for a hybrid or an electric vehicle. Here, the heating arrangement comprises a control device which is designed for carrying out the method described above. Advantageously, the control device can be a part of the heating arrangement or a part of an air conditioning control for the hybrid or the electric vehicle. The heating arrangement can be an air-side PTC heating arrangement for the hybrid or the electric vehicle.
Further important features and advantages of the invention are obtained from the subclaims, from the drawing and from the associated FIGURE description by way of the drawing.
It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combination stated but also in other combinations or by themselves without leaving the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description.
The FIGURE shows a schematic sequence of a method for digitally controlling a heating arrangement.
The FIGURE shows a schematic sequence of a method 1 according to the invention for digitally controlling a heating arrangement 2. Here, a control device 3 of the heating arrangement 2 receives a temperature value T1 or T2 or T3, which each reflect a current outside temperature TA1, or TA2 or TA3. Dependent on the received temperature value T1 or T2 or T3, the control device 3 then determines a limit output PG1 or PG2 or PG3 of the heating arrangement 2 that is smaller than a maximum output PMAX and higher than the minimum output PMIN of the heating arrangement 2. The control device 3 then divides the determined limit output PG1 or PG2 or PG3 into output stages 4, the number of which corresponds to a digital resolution of the control device 3. In this example, the control device 3 has the digital solution equal to 8-bit. Accordingly, the number of the output stages 4 is equal to 256. Following this, the control device 3 controls the heating arrangement 2 between the minimum output PMIN and the limit output PG1 or PG2 or PG3 to one of the output stages 4. Here, the heating output of the smallest output stage 4 is equal to the minimum output PMIN and equal to zero and the heating output of the highest output stage 4 is equal to the limit output PG1 or PG2 or PG3.
The temperature value T1 is below a threshold value T0, so that the control device 3 sets the limit output PG1 equal to the maximum output PMAX. The temperature value T2 is above the threshold value T0, so that the control device 3 sets the limit output PG2 smaller than the maximum output PMAX. The output stages 4 in this case differ by a smaller value than with the limit output PG1, which is equal to the maximum output PMAX. The temperature value T3 is above the threshold value T0 and more over is greater than the temperature value T2, so that the control device 3 sets the limit output PG3 smaller than the maximum output PMAX and smaller than the limit output PG2. In this case, the output stages 4 differ by a smaller value than with the limit output PG1 and also PG2.
In the method 1 according to the invention, the heating output of the heating arrangement 2 can be more finely controlled, which can be advantageous in particular in higher outside temperatures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102018210034.9 | Jun 2018 | DE | national |
