Method for operating drive of electric bicycle by ascertaining overheating protection of electric drive

Abstract

The invention relates to a method for operating a drive (2) of an electric bicycle (1) by ascertaining overheating protection of the electric drive (2), comprising the following steps: receiving and / or reading status data, the status data comprising a temperature of the electric drive (2) and a temperature gradient of the electric drive (2); receiving an overheat protection characteristic curve field (5) and / or reading the overheat protection characteristic curve field (5) from a memory, the overheat protection characteristic curve field (5) indicating an allowable maximum power of the electric drive (2) according to the state data; determining a permissible maximum power from the overheating protection characteristic curve field (5) by means of the state data; and an output power, the maximum power being the allowable maximum power of the electric drive (2).

Description

Technical Field

[0001] The invention relates to a method for operating a drive of an electric bicycle by ascertaining overheating protection of the electric drive, and to an electric bicycle. Background Art

[0002] The sales success of electric bicycles depends crucially on the interaction between the properties of the electric motor and the rider of the electric bicycle. During the driving of the electric bicycle by the rider, the electric motor plays a supporting role and provides a torque that supports the rider in driving the electric bicycle. When operating the electric motor, critical temperatures must be avoided. If critical temperatures are exceeded, the electric motor can be damaged, which can lead to motor failure, shortened motor service life or fire in the motor. Therefore, reaching such critical temperatures must be avoided under all circumstances.

[0003] In order to protect the electric motor, a characteristic curve field is therefore stored in the control device of the electric motor, which switches off the electric motor from a switch-off temperature below the critical temperature. However, the rider of the electric bicycle finds the sudden switching off of the electric motor without prior notice or warning unpleasant. The current characteristic curve field for controlling the electric motor takes this into account, in which the power of the electric motor is already limited from a temperature below the switch-off temperature. This control of the electric motor thus indicates to the rider that this switch-off temperature and a corresponding power interruption of the electric motor can be expected in the event of a further increase in temperature. This enables the rider to reduce the power required by the electric motor in good time and avoid interruptions in support due to overheating of the electric motor. Summary of the invention

[0004] The method according to the invention for operating a drive of an electric bicycle by determining the overheating protection of the electric drive comprises a plurality of steps. One step comprises receiving and / or reading status data, wherein the status data comprises the temperature of the electric drive and the temperature gradient of the electric drive. By receiving and / or calling the temperature gradient of the electric drive, in addition to the current temperature of the electric drive, the time rate of change of the temperature of the electric drive can also be taken into account.

[0005] Another step includes receiving an overheat protection characteristic curve field and / or reading the overheat protection characteristic curve field from a memory, wherein the overheat protection characteristic curve field indicates the maximum permissible power of the electric drive as a function of the status data. The maximum permissible power protects the electric drive of the electric bicycle from possible damage due to overheating. This enables lower maintenance costs, a longer service life and higher performance over the entire service life of the electric drive.

[0006] Another step of the method according to the invention comprises determining the maximum permissible power from the overheat protection characteristic curve field with the aid of the state data. The maximum permissible power is thus determined at least with the aid of the temperature and the temperature gradient of the electric drive. By taking into account the temperature gradient, it is possible to predict at what time rate the temperature of the electric drive increases at the same temperature and accordingly determine from the overheat protection characteristic curve field a limitation on the maximum power that can be output by the electric drive.

[0007] In another step, the electric drive outputs a power that is at most the maximum power allowed by the electric drive. Accordingly, the electric drive can be operated at the same temperature but with different temperature gradients, and different temperature gradients have different maximum powers allowed.

[0008] The dependent claims reveal preferred developments of the invention.

[0009] Preferably, in the overheat protection characteristic curve field, the maximum power allowed decreases as the temperature of the electric drive increases and / or the temperature gradient increases. The gradually decreasing maximum power allowed of the electric drive indicates to the rider that the electric drive has a high temperature and that the electric drive is expected to be shut down due to overheat protection.

[0010] Preferably, in the overheat protection characteristic curve field, the maximum power allowed decreases from the starting temperature and when it exceeds the starting temperature. This means that when the temperature of the electric drive is greater than or equal to the starting temperature, the maximum power allowed of the electric drive is less than the maximum maximum power allowed of the electric drive. In the overheat protection characteristic curve field, the maximum power allowed no longer continues to decrease from the final temperature, wherein the final temperature is greater than the starting temperature. By setting the starting temperature, the decrease in the maximum power allowed is limited to a temperature range above the starting temperature and exceeding the starting temperature. Therefore, in a temperature range below the starting temperature, the rider will not feel that the maximum power allowed of the electric drive is limited. The limited temperature range between the starting temperature and the final temperature is sufficient to promptly indicate to the rider that the maximum power allowed of the electric drive must be limited due to the high temperature.

[0011] Particularly preferably, in the overheat protection characteristic curve field, the maximum power allowed has a zero value starting from the final temperature and above the final temperature. Therefore, the electric drive is switched off starting from the final temperature and above the final temperature. This prevents the electric drive from reaching harmful temperature gradients.

[0012] Preferably, in the overheat protection characteristic curve field, the starting temperature decreases as the temperature gradient increases, and the starting temperature increases as the temperature gradient decreases. Under the same temperature and different temperature gradients, the temperature reached in the same time under the condition of a higher temperature gradient is higher than that under the same time under the condition of a lower temperature gradient. If in both cases, the maximum power allowed is limited from the same starting temperature, then under the condition of a higher temperature gradient, a higher temperature can be reached in a shorter time, and the corresponding limitation of the maximum power allowed is performed. Under the condition of the same temperature but different temperature gradients, the rider feels that the limitation of the maximum power allowed under the condition of a higher temperature gradient is more sudden than that under the condition of a lower temperature gradient. If the starting temperature for limiting the maximum power allowed under the condition of a higher temperature gradient is already at a lower temperature than that under the condition of a lower temperature gradient, the limitation of the maximum power allowed is divided in a larger temperature range and thus in a larger duration. Under the condition of considering a higher temperature gradient, the rider feels that this limitation of the maximum power allowed of the electric drive is comparable to the limitation under the condition of a lower temperature gradient and a higher starting temperature.

[0013] In a particularly preferred case, the starting temperature is selected according to the temperature gradient so that, at a constant temperature gradient, the maximum permissible power is limited for the same duration until the final temperature is reached. Thus, the user does not perceive differences in limiting the maximum permissible power at different temperature gradients.

[0014] Preferably, in the overheat protection characteristic curve field, the starting temperature is between a first starting temperature limit value and a second starting temperature limit value, wherein the first starting temperature limit value is not equal to the second starting temperature limit value. If a limitation is already performed at very low temperatures due to a very high temperature gradient, the rider perceives this situation as a negative effect. From a certain temperature gradient, the rider perceives that the duration until the final temperature is reached at a constant temperature gradient is shorter. In addition, very high temperature gradients are performed by the rider for short-term acceleration, such as in overtaking maneuvers. In particular, in such overtaking maneuvers, the rider perceives that the maximum power allowed is limited in advance at low temperatures as inappropriate. In addition, it should be prevented that the temperature range between the starting temperature and the final temperature becomes too low at very low temperature gradients. The rider perceives this situation as very uncomfortable, because the rider has not yet received an indication of the limitation and thus has not received an indication of the final temperature being reached at a temperature that is about to reach the final temperature. When the temperature gradient changes in the high temperature range, the rider will again experience a sudden limitation of the maximum permissible power of the electric drive, without this being indicated to him by limiting the maximum electric power of the electric drive. In order to take both cases into account, the starting temperature is limited to a temperature range between a first starting temperature limit value and a second starting temperature limit value.

[0015] Particularly preferably, the status data include the battery charge state of the electric energy storage device of the electric bicycle. This makes it possible to make the maximum permissible power also correlated with the battery charge state in addition to the temperature and the temperature gradient in the overheat protection characteristic curve field. Therefore, the overheat protection characteristic curve field can have a lower starting temperature in the case of a high battery charge state than in the case of a lower battery charge state. In addition, the permissible starting temperature can be reduced as the battery charge state gradually decreases. This allows the unlimited maximum power to be called up from the electric drive in a charged electric energy storage device until a higher starting temperature is reached. In addition, by reducing the starting temperature in the case of a low battery charge state of the electric energy storage device, a critical state of the electric energy storage device is avoided.

[0016] Preferably, the status data include the slope of the path on which the electric bicycle is located and / or the GPS position of the electric bicycle. This makes it possible to make the maximum allowable power additionally related to the slope of the path on which the electric bicycle is located in addition to the temperature and the temperature gradient in the overheat protection characteristic curve field. Therefore, the overheat protection characteristic curve field can have a higher starting temperature when the slope of the path is low than when the path slope is large. In addition, the allowable starting temperature can be reduced as the path slope gradually decreases. This allows the unlimited maximum power to be called from the electric drive in a path section without a slope until a higher starting temperature is reached. In addition, by reducing the starting temperature as the path slope gradually increases, a critical state of the energy storage device is avoided.

[0017] Preferably, the status data include weather information, in particular the ambient temperature. From the ambient temperature, possible cooling properties of the motor due to convection can be taken into account, as well as possible temporal changes in temperature and temperature gradients. Taking the ambient temperature into account makes it possible to additionally relate the maximum allowable power to the ambient temperature in the overheating protection characteristic curve field in addition to the temperature and temperature gradient. Therefore, the overheating protection characteristic curve field can have a lower starting temperature in the case of high ambient temperature than in the case of lower ambient temperature. In addition, the allowable starting temperature will decrease as the ambient temperature decreases. This allows the electric drive to call up an unlimited and reliable maximum power at low ambient temperatures until a higher starting temperature is reached. In addition, critical states of the energy storage device can be avoided by lowering the starting temperature in the case of high ambient temperatures.

[0018] Furthermore, the invention comprises an electric bicycle. The electric bicycle comprises a sensor, an electrical energy storage device, an electric drive and a control unit. The sensor is designed to measure at least one temperature of the electric drive and a temperature gradient of the electric drive. The control unit is connected to the sensor and the electric drive for exchanging data. The control unit is configured to carry out a method according to one of the aforementioned embodiments. This enables the control unit to control the electric drive of the electric bicycle as a function of the temperature and the temperature gradient. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the accompanying drawings:

[0020] Figure 1 A schematic diagram showing an electric bicycle according to an embodiment of the present invention, and

[0021] Figure 2 A schematic diagram of an overheat protection characteristic curve field according to one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0022] Figure 1A schematic diagram of an electric bicycle 1 according to an embodiment of the invention is shown. The electric bicycle 1 comprises an electric energy storage 3, an electric drive 2, a sensor 4 and a control unit. The electric drive 2 comprises an electric motor. The sensor 4 is set up to measure at least one temperature of the electric drive 2 and a temperature gradient of the electric drive 2. Thus, not only the current temperature of the electric drive 2 but also the time rate of change of the temperature of the electric drive 2 can be taken into account.

[0023] The control unit is connected to at least the sensor 4 and the electric drive 2 for exchanging data. Therefore, the variables measured by the sensor 4, such as the temperature of the electric drive 2 and the temperature gradient of the electric drive 2, can be transmitted to the control unit and / or called up by the control unit in the sensor 4. In addition, the control unit can transmit signals to the electric drive 2 and thereby control the electric drive 2.

[0024] Preferably, the sensor 4 is designed to detect the battery charge state of the electric energy storage device 3. Preferably, the sensor 4 can be designed to determine the slope of the path on which the electric bicycle 1 is located. Preferably, the sensor 4 is designed to determine the ambient temperature of the electric bicycle 1. Particularly preferably, the control unit is designed to receive and / or retrieve the GPS position of the electric bicycle 1. Particularly preferably, the control unit is designed to receive and / or retrieve weather information at the current location of the electric bicycle 1. Therefore, in addition to the temperature and the temperature gradient, important variables such as the characteristics and changes of the thermal load of the electric drive 2 can also be taken into account by the control unit when controlling the electric drive 2.

[0025] The electrical energy store 3 and the electric drive 2 are connected to one another via electrical connections, so that electrical energy can be exchanged between the electrical energy store 2 and the electric drive 3 .

[0026] Preferably, the control unit is configured to execute the method according to one of the above-described embodiments. Thus, the control unit can receive and / or call the temperature and the temperature gradient of the electric drive 2 measured by the sensor 4, and receive and / or read the overheat protection characteristic curve field 5 from the memory. The control unit is configured to determine the maximum permissible power at the electric drive 2 by means of the overheat protection characteristic curve field 5, the temperature and the temperature gradient of the electric drive 2, and transmit the maximum permissible power to the electric drive 2. Due to the temperature gradient, the time rate of change of the temperature of the electric drive 2 can be taken into account when determining the maximum permissible power.

[0027] Particularly preferably, the control unit is configured to receive the variables measured by the sensor 4 as described above and additionally receive weather information at the resting place of the electric bicycle 1 and the GPS position of the electric bicycle. The control unit is configured to receive and / or read out the overheat protection characteristic curve field 5 from a memory. Preferably, the control unit is configured to determine the maximum permissible power of the electric drive 2 with the aid of the overheat protection characteristic curve field and the variables previously read out from the sensor and / or the GPS position of the electric bicycle 1 and the weather information at the resting place of the electric bicycle 1. The control unit sends the maximum permissible power to the electric drive 2. Therefore, other variables that have an influence on the temperature change of the electric drive 2 can be taken into account.

[0028] Figure 2 A schematic diagram of an overheating protection characteristic curve field 5 is shown. The Z-axis of the overheating protection characteristic curve field 5 indicates the maximum power allowed of the electric drive 2 as a percentage of the maximum allowed maximum power. The Z-axis is listed in the range of 0% to 100% of the maximum allowed maximum power. The X-axis of the overheating protection characteristic curve field 5 represents a temperature scale, wherein the temperature scale indicates the temperature of the electric drive 2. The final temperature 6 is listed at the left end of the X-axis, and the temperature located to the right of the final temperature 6 on the X-axis decreases relative to the final temperature 6. In addition, a first starting temperature 7 and a second starting temperature 8 are listed on the X-axis, wherein the second starting temperature 8 is less than the first starting temperature 7. The Y-axis of the overheating protection characteristic curve field 5 describes the temperature gradient.

[0029] In the case of a constant temperature gradient, at a temperature below the starting temperatures 7, 8 belonging to the constant temperature gradient, the overheat protection characteristic curve field 5 does not have a reduction in the maximum permissible maximum power. As the starting temperatures 7, 8 belonging to the constant temperature gradient are exceeded, the maximum permissible power decreases with the temperature. If the temperature reaches the final temperature 6 under the constant temperature gradient, the maximum permissible power is assigned a zero value. The electric drive 2 is shut down when the maximum permissible value is zero. This design of the overheat protection characteristic curve field 5 allows the rider to call the maximum permissible maximum power of the electric drive 2 below the starting temperatures 7, 8. In addition, before reaching the final temperature 6, the rider is indicated by the gradually decreasing maximum permissible power as the starting temperatures 7, 8 are exceeded, that the electric drive 2 is about to reach the final temperature 6 and is about to shut down the electric drive 2 in relation to this.

[0030] In the overheat protection characteristic curve field 5, the maximum power allowed under a constant temperature gradient is reduced in a continuous variation process until the final temperature 6. In an alternative embodiment, the variation process of the maximum power allowed between the starting temperature 7, 8 and the final temperature 6 can be arbitrary. This variation process of the maximum power allowed can be a linear variation process, a concave variation process, a convex variation process, a logarithmic variation process or a step function variation process. In one embodiment, the variation process of the maximum power allowed between the corresponding starting temperature 7, 8 and the corresponding final temperature 6 under a constant temperature gradient can be changed according to the temperature gradient.

[0031] In another embodiment, in the overheat protection characteristic curve field 5, the negative temperature gradient is assigned the same starting temperature 7, 8 as the positive temperature gradient with the same magnitude of the negative temperature gradient. A negative temperature gradient occurs when the electric drive 2 cools and the temperature of the electric drive 2 decreases. The overheat protection characteristic curve field also covers the following situation: the temperature of the electric drive 2 previously exceeded the final temperature and the temperature of the electric drive dropped and fell below the final temperature after the electric drive was turned off. In an alternative embodiment, in the overheat protection characteristic curve field 5, the negative temperature gradient is assigned a different starting temperature 7, 8 compared to the starting temperature 7, 8 of the positive temperature gradient with the same magnitude of the negative temperature gradient. In another embodiment, in the overheat protection characteristic curve field 5, the negative temperature gradient is assigned the same change process between the final temperature 6 and the corresponding starting temperature 7, 8 as the positive temperature gradient with the same magnitude of the negative temperature gradient. In an alternative embodiment, in the overheat protection characteristic curve field 5, a different course of change of the permissible maximum power between the final temperature 6 and the associated starting temperatures 7, 8 is assigned to the negative temperature gradient compared to the course of change of the permissible maximum power between the final temperature 6 and the associated starting temperatures 7, 8 for a positive temperature gradient of the same magnitude with the negative temperature gradient. In an alternative embodiment, in the overheat protection characteristic curve field 5, within the range of the negative temperature gradient, the starting temperatures 7, 8 correspond to the final temperature 6, so that as the final temperature 6 is exceeded in the case of a negative temperature gradient, the permissible maximum power corresponds to the maximum permissible maximum power. In another embodiment of the overheat protection characteristic curve field 5, a different final temperature 6 is assigned to the negative temperature gradient than to a positive temperature gradient of the same magnitude with the negative temperature gradient.

[0032] The overheat protection characteristic curve field 5 has different starting temperatures 7, 8 under different temperature gradients. Preferably, if there is no temperature gradient, the overheat protection characteristic curve field 5 has the highest starting temperature 7. The starting temperatures 7, 8 decrease as the temperature gradient increases. In the case of a higher constant temperature gradient, the temperature changes over time in a shorter time than in the case of a lower temperature gradient. If the same starting temperature 7, 8 is set for each temperature gradient in the overheat protection characteristic curve field 5, the duration between the starting temperature 7, 8 and reaching the final temperature 6 in the case of a higher constant temperature gradient is significantly shorter than in the case of a lower constant temperature gradient. The rider feels that the shortening of the duration between the starting temperature 7, 8 and the final temperature 6 in the case of a constant temperature gradient is uncomfortable. By reducing the starting temperature 7, 8 in the case of a higher temperature gradient in the direction of a lower temperature, the above effect is enhanced and the rider's feeling is improved. In a preferred embodiment, the starting temperatures 7, 8 are adapted to the temperature gradient so that the duration between the starting temperature 7, 8 and reaching the final temperature 6 in the case of a constant temperature gradient is the same for each temperature gradient.

[0033] The overheat protection characteristic curve field 5 has the same final temperature in the case of different temperature gradients. In an alternative embodiment, the final temperature 6 can vary according to the temperature gradient. Therefore, a certain inertia can be taken into account when heating the electric drive 2 and the location where the temperature of the electric drive 2 is measured. In an alternative embodiment, the final temperature 6 decreases as the temperature gradient increases.

[0034] In one embodiment, the overheat protection characteristic curve field 5 comprises further axes on which the battery charge state and / or the slope of the path on which the electric bicycle 1 is located and / or the ambient temperature of the environment of the electric bicycle 1 are plotted. In this case, the starting temperatures 7, 8 decrease with increasing ambient temperature and / or increasing slope of the path on which the electric bicycle is located and / or with increasing ambient temperature. This makes it possible to take into account other influencing factors on the temperature of the electric drive 2 and its temporal variation.

Claims

1. A method for operating a drive (2) of an electric bicycle (1) by determining an overheating protection of the electric drive (2), comprising the following steps: Receiving and / or reading status data, wherein the status data comprises the temperature of the electric drive (2) and the temperature gradient of the electric drive (2); Receiving an overheating protection characteristic curve field (5) and / or reading the overheating protection characteristic curve field (5) from a memory, wherein the overheating protection characteristic curve field (5) indicates the maximum permissible power of the electric drive (2) according to the status data; Determining the maximum permissible power from the overheat protection characteristic curve field (5) with the aid of the state data; and A power is outputted which is at most the maximum permissible maximum power of the electric drive (2).

2. The method according to claim 1, wherein: In the overheat protection characteristic curve field (5), the maximum permissible power decreases as the temperature of the electric drive (2) increases and / or as the temperature gradient increases.

3. The method according to any one of the preceding claims, wherein: In the overheat protection characteristic curve field (5), the maximum permissible power decreases from a starting temperature (7, 8) and above the starting temperature, and the maximum permissible power does not decrease further from a final temperature (6), wherein the final temperature (6) is greater than the starting temperature (7, 8).

4. The method according to claim 3, wherein: In the overheating protection characteristic curve field (5), the maximum permissible power has the value zero starting from the final temperature (6) and above the final temperature.

5. The method according to claim 3 or 4, wherein: In the overheat protection characteristic curve field (5), the starting temperature (7, 8) decreases as the temperature gradient increases, and the starting temperature (7, 8) increases as the temperature gradient decreases.

6. The method according to any one of claims 3 to 5, wherein: In the overheat protection characteristic curve field (5), the starting temperature is between a first starting temperature boundary value (7) and a second starting temperature boundary value (8), wherein the first starting temperature boundary value (7) is not equal to the second starting temperature boundary value (8).

7. The method according to any one of the preceding claims, wherein: The status data include the battery charge status of the electric energy storage device (3) of the drive (2) of the electric bicycle (1).

8. The method according to any one of the preceding claims, wherein: The status data includes the slope of the path on which the electric bicycle (1) is located and / or the GPS position of the electric bicycle (2).

9. The method according to any one of the preceding claims, wherein: The status data includes weather information, especially ambient temperature.

10. A driver for an electric bicycle (1), the driver comprising: A control unit, wherein the control unit is configured to carry out the method according to one of the preceding claims.

11. An electric bicycle (1) having a drive according to claim 10.

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