CN112086936B - Motor overheating protection method - Google Patents

Abstract

The motor overheat protection method comprises the steps of obtaining the power-on time length of an ECU; acquiring motor adjustment time; acquiring motor locked-rotor time; estimating real-time temperatures of important positions of a plurality of motors according to the ECU power-on time, the motor adjusting time and the motor locked-rotor time; and comparing and calculating to obtain the real-time estimated temperature of the motor and the highest bearing temperature of the motor, and if the real-time estimated temperature of the motor at any important position is greater than the corresponding highest bearing temperature, performing motor overheat protection. The method has the advantages of low cost and simple algorithm, and can ensure that the whole components of the motor work in an allowable temperature range.

Description

Motor overheating protection method

technical field

The invention relates to the field of motors, in particular to a motor overheat protection method.

Background technique

The application of electric motors in the field of automobile steering mainly involves two aspects. On the one hand, it is used for chassis steering, and the electric motor is used to provide steering assistance. On the other hand, it is used for steering wheel steering, and the motor is used to adjust the height of the steering column and the angle of the steering column.

Since the electric adjustment of the steering column involves the field of automobile safety, if the adjustment of the steering column fails, it may lead to serious consequences, especially in the case of motor overheating, which may cause a fire. In view of this, the industry generally uses motor overheat protection when developing electrically adjustable steering columns.

The motor overheating protection is a protection measure implemented to prevent the motor from being blocked or burnt out due to long-term continuous operation. In the field of steering, there are three main means of motor overheat protection: 1. Collect data through sensors (such as current sensors, temperature sensors, angle sensors, etc.) to estimate the motor temperature; 2. Protect the motor from overheating through an overheat protector involving thermal components Protection; 3. Estimate the motor temperature through the algorithm model.

However, collecting data through sensors and performing overheating protection through overheating protectors both need to increase design cost and system complexity. Moreover, the thermal element needs to be calibrated, and its turn-off and turn-off time can only be related to the temperature of a certain part of the motor, and multi-point temperature detection cannot be realized. The motor assembly is composed of multiple components, and the temperature rise rate of each point, The temperature resistance value is different. Under different working conditions, overheating may occur at different points. Therefore, the scheme of using the overheat protector for overheat protection cannot fully protect the motor. However, the existing schemes using software to realize motor overheating protection usually have complex algorithms, such as current integration or complex multiplication and division, which cannot be realized by a simple single-chip microcomputer, or require a large amount of software computing resources.

The foregoing description is provided to provide general background information and does not necessarily constitute prior art.

Contents of the invention

In view of this, the present invention provides a motor overheat protection method, which has low cost, simple algorithm, and can ensure that the whole parts of the motor work within the allowable temperature range.

The motor overheat protection method provided by the present invention includes the following steps: obtaining the power-on time of the ECU; obtaining the motor adjustment time; obtaining the motor stall time; estimating the important positions of multiple motors according to the ECU power-on time, the motor adjustment time, and the motor stall time The real-time temperature of the motor; compare and calculate the real-time estimated temperature of the motor and the maximum withstand temperature of the motor. If the real-time estimated temperature of the motor at any important position is greater than its corresponding maximum withstand temperature, the motor will be overheated.

Furthermore, the formula adopted for estimating the real-time temperatures of important positions of multiple motors based on the ECU power-on time, motor adjustment time, and motor stall time is: T=T ₀ -KL*(ta-tb-tc)+KT*tb +KD*tc, where T represents the real-time estimated temperature of the motor, T ₀ represents the initial temperature of the motor, which is read from the memory when the ECU is powered on, KL represents the cooling coefficient of the motor, which is obtained by pre-calibration, and KT represents the normal adjustment temperature rise coefficient , obtained by pre-calibration, KD represents the stall temperature rise coefficient, obtained by pre-calibration, ta represents the duration of ECU power-on, tb represents the duration of motor adjustment, and tc represents the duration of motor stall.

Further, important positions of the motor include motor rotor, brush holder and tail bearing.

Further, the method further includes: after the motor is overheated, continue to estimate the real-time temperature of the important position of the motor according to the ECU power-on time, the motor adjustment time, and the motor stall time until the real-time estimated temperature of the motor at the important position is lower than the corresponding The maximum withstand temperature is a certain value, and the motor overheating protection is exited.

Further, the step of obtaining the power-on duration of the ECU includes: powering on the car and sending a power-on signal to the ECU; the ECU receiving the power-on signal and sending a timing start signal to the timer; the timer receiving the timing start signal and starting the ECU power-on timing , and send the timing result to the ECU at the first set frequency.

Further, the obtained motor adjustment duration is the total duration of motor adjustment after the ECU is powered on.

Further, the step of obtaining the motor adjustment duration includes: the motor adjustment button is pressed, and the motor adjustment instruction or the relay closing instruction is sent to the ECU; the ECU receives the motor adjustment instruction or the relay closing instruction, and sends a timing start signal to the timer; the timer receives the timing Start signal, start timing of motor adjustment time, and continue timing until receiving the adjustment end command or the relay disconnection command, and send the timing result to the ECU at the second set frequency; if the timer receives the ECU power off during the timing process signal, the timing result will automatically reset to zero. If the timer does not receive the ECU power-off signal, the timing result will remain unchanged until the next timing starts, and the timing will be accumulated next time.

Further, the obtained motor stall duration is the total duration of the motor stall after the ECU is powered on.

Further, the step of obtaining the motor stall duration includes: sending the motor output speed signal or the current signal passing through the motor to the ECU during the motor running; the ECU receiving the motor output speed signal or current signal to determine whether the motor is stalled; If the output speed is zero or the current suddenly increases during the process, the ECU will determine that the motor is locked, and at the same time send a timing start signal to the timer; When the current is zero or the current remains unchanged, the timing is continued, and the timing result is sent to the ECU at the third set frequency; if the timer receives the ECU power-off signal during the timing, the timing result is automatically reset to zero, When the ECU power-off signal is received, the timing result remains unchanged until the next timing starts, and the timing will be accumulated next time.

Further, the method further includes: comparing and calculating the real-time estimated temperature of the motor with the ambient temperature, and if the real-time estimated temperature of the motor at an important position is lower than the ambient temperature, then setting the ambient temperature as the real-time estimated temperature of the motor at this position , if the real-time estimated temperature of the motor at an important position is greater than the ambient temperature, then further comparison and calculation is performed to obtain the real-time estimated temperature of the motor and the maximum temperature of the motor at this position.

In summary, the present invention has at least one of the following beneficial effects:

1. The present invention estimates the temperature values of several important positions of the motor and judges whether overheating protection is required. Compared with the method of judging whether overheating protection is required for only one position, it can ensure that the whole parts of the motor work within the allowable temperature range. More comprehensive protection;

2. The present invention realizes overheating protection through software algorithm, which reduces system cost;

3. The algorithm of the present invention is simple, avoids integration and complex multiplication and division operations, etc., and will not increase the calculation burden of the ECU too much.

Description of drawings

FIG. 1 is a schematic flow chart of the motor overheat protection method of the present invention.

Fig. 2 is a parameter table of an overheating protection function of an embodiment of the motor.

Fig. 3 shows the temperature rise and temperature drop coefficients of an embodiment of the steering column length and angle adjustment motor.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

It should be noted that the motor overheat protection method provided by the embodiment of the present invention can not only perform overheat protection on the motor installed on the steering column for adjusting the height or angle of the steering column, but also can protect the steering motor installed on the chassis and Other types of motors are protected against overheating. The following takes the overheating protection of the steering column motor as an example to illustrate.

As shown in Figure 1, the motor overheat protection method provided by the embodiment of the present invention includes:

Step S10: Obtain the power-on duration of the ECU;

In step S10, the scheme that can be adopted when obtaining the power-on time of the ECU is: the car is powered on and sends a power-on signal to the ECU; the ECU receives the power-on signal and sends a timing start signal to the timer; the timer receives the timing start signal and starts Carry out the power-on timing of the ECU, and send the timing result to the ECU at the first set frequency f1.

Step S20: Obtain the motor adjustment time;

In step S20, the acquired motor adjustment duration is the total motor adjustment duration after the ECU is powered on. After the ECU is powered on, the motor may intermittently adjust the height or angle of the steering column. In this case, the motor adjustment time obtained is the total time for multiple motor adjustments after the ECU is powered on.

In step S20, the scheme for obtaining the motor adjustment duration may include: the motor adjustment button is pressed, and the motor adjustment command or the relay closing command is sent to the ECU; the ECU receives the motor adjustment command or the relay closing command, and sends a timing start signal to the timer; timing The timer receives the timing start signal, starts the timing of the motor adjustment time, and continues timing until it receives the adjustment end command or the relay disconnection command, and sends the timing result to the ECU at the second set frequency f2; if the timer is closed during the timing process When the ECU power-off signal is received, the timing result will be automatically reset to zero. If the timer does not receive the ECU power-off signal, the timing result will remain unchanged until the next timing starts, and the timing will be accumulated next time.

Step S30: Obtain the duration of motor stalling;

In step S30, the acquired motor stall duration is the total duration of the motor stall after the ECU is powered on. After the ECU is powered on, the motor may be locked for many times. In this case, the obtained motor locked-rotor duration is the total duration of the motor's multiple times of locked-rotor after the ECU is powered on.

In step S30, the solution for obtaining the motor stall duration may include: sending the motor output speed signal or the current signal passing through the motor to the ECU during the motor running; the ECU receiving the motor output speed signal or current signal to determine whether the motor is stalled; If the output speed of the motor is zero or the current suddenly increases during the running of the motor, the ECU determines that the motor is locked, and at the same time sends a timing start signal to the timer; Continuous timing when the output speed of the motor is zero or the current remains unchanged, and the timing result is sent to the ECU at the third set frequency f3; if the timer receives a power-off signal from the ECU during the timing, the timing result is automatically reset to zero If the timer does not receive the ECU power-off signal, the timing result remains unchanged until the next timing starts, and the timing will be accumulated next time.

It should be noted that the first set frequency f1, the second set frequency f2, and the third set frequency f3 may be equal or different. In this embodiment, the first set frequency f1, the second set frequency f2 and the third set frequency f3 are equal, both are 0.4s.

Step S40: Estimating the real-time temperatures of important positions of multiple motors according to the ECU power-on time, motor adjustment time, and motor stall time;

In step S40, the important positions of the motor include the motor rotor, the brush holder and the tail bearing, and the real-time temperatures of these three positions are separately calculated by the ECU.

In step S40, the calculation formula used when estimating the real-time temperature of the important position of the motor according to the ECU power-on time, the motor adjustment time, and the motor stall time is:

T=T ₀ -KL*(ta-tb-tc)+KT*tb+KD*tc,

As shown in Figure 2, in the formula, T represents the real-time estimated temperature of the motor, T ₀ represents the initial temperature of the motor, which is the motor temperature saved when the ECU was last powered off, and will be read from the memory when the ECU is powered on again, KL Indicates the cooling coefficient of the motor, which is obtained by pre-calibration, KT represents the normal adjustment temperature rise coefficient, which is obtained by pre-calibration, KD represents the temperature rise coefficient of stalled rotor, which is obtained by pre-calibration, ta represents the power-on time of the ECU, which is detected by the ECU, and tb represents The motor adjustment time, tc represents the motor stall time, the motor cooling coefficient KL at different positions of the motor, the normal adjustment temperature rise coefficient KT, and the stall temperature rise system KD are shown in Figure 3.

Step S50: Comparing and calculating the real-time estimated temperature T of the motor and the ambient temperature T _min , if the real-time estimated temperature T of the motor at an important position is lower than the ambient temperature T _min , then set the ambient temperature T _min as the real-time temperature of the motor at this position Estimating the temperature T, if the real-time estimated temperature T of the motor at an important position is greater than the ambient temperature T _min , execute step S60;

In step S50, when the real-time estimated temperature T of the motor is lower than the ambient temperature _Tmin , the purpose of setting the ambient temperature _Tmin as the real-time estimated temperature T of the motor at this position is to prevent the motor from not turning for a long time after the ECU is powered on The real-time estimated temperature T of the motor is distorted by the height or angle adjustment of the pipe string.

Step S60: Compare and calculate the real-time estimated temperature T of the motor and the maximum temperature of the motor. If the real-time estimated temperature T of the motors at the three positions is lower than the corresponding maximum temperature of the motor, it indicates that the motor is in normal operation and no overheating measures are required. Protective measures, if the real-time estimated temperature T of the motor at any important position is greater than its corresponding maximum withstand temperature, then execute step S70;

Step S70: Carry out motor overheat protection, the ECU does not respond to the motor adjustment command, and continue to repeat the above steps S10-S60, and continue to estimate the real-time temperatures of important positions of the motors according to the ECU power-on time, motor adjustment time, and motor stall time, until Step S80;

Step S80: The real-time estimated temperatures T of the motors at important positions are all lower than the corresponding maximum withstand temperature by a certain value, the motor overheat protection is disabled, and the motor is allowed to adjust again.

In step S80, the condition for exiting the motor overheat protection is set to be that the real-time estimated temperature T of the motor is less than a certain value corresponding to the maximum withstand temperature. Exit the frequent motor operation and frequent overheating protection caused by the low setting of the overheating protection condition.

According to the data provided in Figure 2 and Figure 3, after initialization, the motor is allowed to stall continuously for 71 seconds; after initialization, the motor is allowed to adjust continuously for 166 seconds; after overheating protection, the cooling time required to exit the overheating state is 100 seconds; After exiting the overheating protection, it is allowed to adjust the time continuously for 10 seconds. After 10 seconds, the motor will enter the overheating protection state again; the time required from overheating protection to cooling to the initialization state is 3 hours. The data shown in FIG. 2 and FIG. 3 are only the calibration data of one of the angle adjustment motors and the height adjustment motors used in the steering column. It is understandable that different motors need different calibration data.

In summary, the present invention has at least one of the following beneficial effects:

1. The present invention estimates the temperature values of several important positions of the motor, and judges whether overheating protection is required. Compared with the method of only judging whether overheating protection is required for one position, the protection is more comprehensive;

2. The present invention realizes overheating protection through software algorithm, which reduces system cost;

3. The algorithm of the present invention is simple, and will not increase the computing burden of the ECU too much.

As used herein, the terms "comprises", "comprises" or any other variation thereof are intended to cover a non-exclusive inclusion of elements other than those listed and also other elements not expressly listed.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (8)

1. A motor overheating protection method, is characterized in that, comprises the steps: Obtain the power-on time of the ECU; Obtain the motor adjustment time; Obtain the motor stall duration; Estimate the real-time temperature of important positions of multiple motors according to the ECU power-on time, motor adjustment time, and motor stall time; Comparing and calculating the real-time estimated temperature of the motor and the maximum temperature of the motor, if the real-time estimated temperature of the motor at any important position is greater than its corresponding maximum temperature, the motor will be overheated; The formula used to estimate the real-time temperature of important positions of multiple motors based on the ECU power-on time, motor adjustment time, and motor stall time is: T=T ₀ -KL*(ta-tb-tc)+KT*tb+KD*tc, Among them, T represents the real-time estimated temperature of the motor, T ₀ represents the initial temperature of the motor, which is read from the memory when the ECU is powered on, KL represents the cooling coefficient of the motor, which is obtained by pre-calibration, and KT represents the normal adjustment temperature rise coefficient, which is obtained by pre-calibration , KD is the locked-rotor temperature rise coefficient, which is pre-calibrated, ta indicates the ECU power-on time, tb indicates the motor adjustment time, tc indicates the motor locked-rotor time, and the important positions of the motor include the motor rotor, brush holder and tail bearing. 2. The motor overheat protection method according to claim 1, characterized in that the method further comprises: After the motor is overheated, continue to estimate the real-time temperature of the important position of the motor according to the ECU power-on time, motor adjustment time, and motor stall time until the real-time estimated temperature of the motor at the important position is lower than the corresponding maximum temperature. Exit the motor Overheating protection. 3. The motor overheating protection method as claimed in claim 1, wherein the step of obtaining the ECU power-on duration comprises: The car is powered on and sends a power-on signal to the ECU; The ECU receives the power-on signal and sends a timing start signal to the timer; The timer receives the timing start signal, starts timing when the ECU is powered on, and sends timing results to the ECU at a first set frequency. 4 . The motor overheat protection method according to claim 1 , wherein the acquired motor adjustment duration is the total duration of motor adjustment after the ECU is powered on. 5. The motor overheat protection method according to claim 4, wherein the step of obtaining the motor adjustment duration comprises: The motor adjustment button is pressed, and a motor adjustment command or a relay closing command is sent to the ECU; The ECU receives the motor adjustment command or the relay closing command, and sends a timing start signal to the timer; The timer receives the timing start signal, starts the timing of the motor adjustment time, and continues timing until it receives the adjustment end command or the relay disconnection command, and sends the timing result to the ECU at the second set frequency; If the timer receives the ECU power-off signal during the timing process, the timing result will automatically reset to zero. If the timer does not receive the ECU power-off signal, the timing result will remain unchanged until the next timing starts, and the cumulative timing will be accumulated next time. . 6 . The motor overheat protection method according to claim 1 , wherein the acquired motor stall duration is the total duration of the motor stall after the ECU is powered on. 7 . 7. The motor overheat protection method according to claim 6, wherein the step of obtaining the motor stall duration comprises: Send the motor output speed signal or the current signal through the motor to the ECU during the motor running; The ECU receives the output speed signal or current signal of the motor, and judges whether the motor is locked; If the output speed of the motor is zero or the current suddenly increases during the operation of the motor, the ECU will determine that the motor is locked, and at the same time send a timing start signal to the timer; The timer receives the timing start signal, starts the timing of the motor stall time, and continues timing when the motor output speed is zero or the current remains unchanged, and sends the timing result to the ECU at the third set frequency; If the timer receives the ECU power-off signal during the timing process, the timing result will automatically reset to zero. If the timer does not receive the ECU power-off signal, the timing result will remain unchanged until the next timing starts, and the cumulative timing will be accumulated next time. . 8. The motor overheat protection method according to claim 1, characterized in that the method further comprises: Compare the calculated real-time estimated temperature of the motor with the ambient temperature. If the real-time estimated temperature of the motor at an important position is lower than the ambient temperature, set the ambient temperature as the real-time estimated temperature of the motor at this position. If the real-time estimated temperature of the motor at an important position If the real-time estimated temperature is greater than the ambient temperature, then further comparison and calculation is performed to obtain the real-time estimated temperature of the motor and the maximum temperature that the motor can withstand at this position.

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