WO2021253634A1

WO2021253634A1 - Method for detecting temperature of braking resistor in driver

Info

Publication number: WO2021253634A1
Application number: PCT/CN2020/111732
Authority: WO
Inventors: 李锋源; 欧新木; 黄继波; 江庚炜
Original assignee: 福州富昌维控电子科技有限公司
Priority date: 2020-06-18
Filing date: 2020-08-27
Publication date: 2021-12-23
Also published as: CN111711402A; CN111711402B

Abstract

The present invention relates to the technical field of servo motor drivers, and specifically relates to a method for detecting the temperature of a braking resistor in a driver. Real-time power parameters of a braking resistor are obtained by means of calculations after a driver powers on, and normalization processing is performed to form a corresponding temperature rise curve function; corresponding power parameters can be obtained at any subsequent moment by means of the temperature rise curve function, and temperature parameters corresponding to said moment are calculated to implement the detection of the temperature of the braking resistor. The entire detection method does not require the addition of hardware equipment, i.e., devices are conserved, while the method also has the advantages of being highly reliable, being simple and convenient to use, etc.

Description

A method for detecting the temperature of the braking resistor in the driver

Technical field

The invention relates to the technical field of servo motor drives, in particular to a method for detecting the temperature of a braking resistor in a drive.

Background technique

The servo motor drive will feed back energy to the servo drive after the motor is stopped by high-speed operation. In order to prevent the bus voltage from rising too fast, when the voltage rises to a certain value, it is necessary to start the braking resistor to discharge the excess; The energy is converted into heat and released. At present, with the development of servo drives in the direction of miniaturization and compactness, more and more applications need to find resistors with large power and small installation dimensions. The resistors are installed on the radiator with other power devices. During the resistance work, the resistance will emit heat to increase the ambient temperature near the resistance, which not only affects the working efficiency of the semiconductor device, but also affects the service life of the resistance because of the degree of temperature change. Therefore, it is required to be able to sense the temperature of the resistor, so that power can be applied to the resistor reasonably without causing the surface temperature to rise beyond the design requirements.

The commonly used method is to add an NTC temperature sensor to the housing of the resistor, convert it to a voltage value through the circuit, and then obtain the current temperature value through the analog-to-digital conversion (ADC) calculation. The advantage of this method is that the temperature can be sampled intuitively. value. But the disadvantage is that additional temperature sensors and other electronic components need to be added, which increases the hardware cost; during production and installation, an additional temperature sensor installation process is required, which requires higher assembly and increases labor costs; in addition, in actual use During the process, the device has a certain probability of failure.

technical problem

The technical problem to be solved by the present invention is to provide a method for detecting the temperature of the braking resistor in the driver, which can realize the temperature detection of the braking resistor without adding hardware equipment.

Technical solutions

In order to solve the above technical problems, the technical solutions adopted by the present invention are:

A method for detecting the temperature of a braking resistor in a driver includes the following steps:

S1. After the driver is powered on, obtain the bus voltage value connected to the braking resistor and the resistance value of the braking resistor in real time, and calculate the real-time power parameters of the braking resistor;

S2. Normalize the real-time power parameter to obtain the temperature rise curve function corresponding to the braking resistor;

S3. Obtain the first power parameter corresponding to the braking resistor at the first moment, combine the first power parameter with a temperature rise curve function, and calculate the temperature parameter corresponding to the braking resistor at the first moment.

Beneficial effect

The beneficial effects of the present invention are:

The present invention provides a method for detecting the temperature of a braking resistor in a drive. After the drive is powered on, the real-time power parameters of the braking resistor are calculated and normalized to form a corresponding temperature rise curve function. The corresponding power parameters can be obtained at any time through the temperature rise curve function, and the temperature parameters corresponding to the time can be calculated to realize the detection of the brake resistor temperature. The whole detection method does not need to add hardware equipment, that is, it saves components, and it also has the advantages of high reliability and easy use.

Description of the drawings

Figure 1 is a flow chart of the steps of a method for detecting the temperature of a braking resistor in a drive of the present invention;

Figure 2 is a schematic diagram of the temperature rise curve of the braking resistor of the present invention.

Embodiments of the present invention

In order to describe in detail the technical content, the achieved objectives and effects of the present invention, the following description will be given in conjunction with the embodiments and the accompanying drawings.

Please refer to Fig. 1, a method for detecting the temperature of a braking resistor in a drive provided by the present invention includes the following steps:

It can be seen from the above description that the beneficial effects of the present invention are:

Further, step S1 is specifically:

Acquire the voltage value of the busbar connected to the braking resistor and the resistance value of the braking resistor in real time, and calculate the real-time power parameters of the braking resistor; at the same time, collect the corresponding temperature parameters;

The normalization processing in step S2 is specifically:

Divide the temperature parameter corresponding to the braking resistor at each moment after the drive is powered on by the corresponding power parameter to obtain the corresponding value.

It can be seen from the above description that through the above specific steps, the normalization process is realized. Since the actual temperature parameters and actual power parameters of the braking resistor are both variables during the use process, the temperature rise curve cannot be formed, so the temperature parameters are divided by the corresponding The power parameter can obtain the temperature parameter corresponding to each unit power at each moment, that is, the temperature corresponding to the power of 1W, and then the corresponding temperature rise curve can be formed.

Further, after step S3, it also includes:

S4. Determine whether the temperature parameter corresponding to the braking resistor at the first moment reaches the maximum value of the temperature rise curve function; if not, query the temperature rise curve function to obtain the second temperature rise curve function. The temperature parameter corresponding to the time; the second time is the time next to the first time.

It can be seen from the above description that if the temperature parameter corresponding to the braking resistor at the first moment does not reach the maximum value of the temperature rise curve function, the temperature rise curve function is queried to obtain the second temperature rise curve function. The temperature parameter corresponding to the time (that is, the next time of the first time) is equivalent to the temperature at the next time can be calculated, so as to adjust the output power of the drive subsequently.

Further, between step S3 and step S4, the method further includes:

S31. Determine whether the first power parameter is greater than zero, and if so, perform step S4.

From the above description, this step is used to determine whether the drive is operating normally. If it is operating normally, there will be a power value on the braking resistor. This ensures that the temperature parameter of the braking resistor is detected under the normal operation of the drive, and the obtained temperature parameter is reliable.

Further, step S31 also includes:

If the first power parameter is less than or equal to zero, it is determined whether the first power parameter corresponding to the braking resistor at the first time is less than the power parameter corresponding to the braking resistor at the third time, and the third time is the first time. The last moment of the moment

If yes, record the first power parameter corresponding to the first moment as the power point of the braking resistor before cooling down, and perform the normalization process again to obtain the normalized temperature point;

Use the normalized temperature point to query the preset temperature drop curve function to obtain the normalized temperature value at the next moment;

Convert the normalized temperature value at the next moment into the corresponding actual temperature to obtain the actual temperature value at the next moment.

It can be seen from the above description that the first power parameter is less than or equal to zero, indicating that the drive has been powered down and stopped supplying electrical energy to the braking resistor. At this time, it enters the cooling stage, so it needs to be re-normalized to realize that the braking resistor is in the cooling stage. The temperature detection at a certain moment or the next moment.

Further, step S4 also includes:

If the temperature parameter corresponding to the braking resistor at the first moment reaches the maximum value of the temperature rise curve function, it is determined whether the first power parameter corresponding to the braking resistor at the first moment is less than that of the braking resistor at the first moment. The power parameter corresponding to the third time, where the third time is the previous time of the first time;

It can be seen from the above description that when the temperature parameter corresponding to the braking resistor at the first moment reaches the maximum value of the temperature rise curve function, continue to determine whether the first power parameter corresponding to the braking resistor at the first moment is less than the maximum value of the temperature rise curve function. The power parameter corresponding to the braking resistor at the third moment, if it is, indicates that it has entered the cooling stage, so it is necessary to re-normalize to realize the temperature detection of the braking resistor at a certain moment or the next moment in the cooling stage.

Further, it also includes:

Determine whether the actual temperature value at the next moment is greater than the preset threshold, and if so, trigger the protection mechanism of the drive.

It can be seen from the above description that if it is estimated that the actual temperature value at the next moment is greater than the preset threshold, the preset threshold is set according to the critical value of the electrical performance of the braking resistor, indicating that there is a risk of damage to the braking resistor at the next moment, thus triggering The protection mechanism of the drive, such as reducing the output power of the drive, etc.

Please refer to FIG. 1 to FIG. 2. The first embodiment of the present invention is:

When the servo is working, when the brake is encountered, the bus voltage will feed back energy to the servo drive after the bus voltage stops, and the bus voltage will rise accordingly. When the voltage rises to a certain value, the resistance control logic inside the software will send a command Turn on the resistance for the resistance control circuit to discharge;

S1. After the driver is powered on, the software obtains the voltage value of the busbar connected to the braking resistor and the resistance value of the braking resistor in real time, and calculates the real-time power parameters of the braking resistor;

In this embodiment, the bus voltage value U is 310V, and the resistance value of the braking resistor R is 50Ω. According to the power calculation formula P=U ² /R of the resistor, the real-time power of the braking resistor R can be calculated as P=(310 *310)/50=1922W.

The above step S1 is specifically:

It should be noted that: the above step S1 is implemented during the design experiment stage, and the corresponding temperature parameters are collected by setting a temperature sensor. The temperature sensor is not set in the subsequent steps.

S2. Perform normalization processing on the real-time power parameters to obtain the temperature rise curve function corresponding to the braking resistor; wherein the normalization processing is specifically: the braking resistor corresponds to each moment after the drive is powered on Divide the temperature parameter by the corresponding power parameter to get the corresponding value.

Specifically, as shown in Figure 2, the figure represents the temperature rise curve corresponding to a power of 1W, where the horizontal axis represents time (unit: seconds), and the vertical axis represents temperature (unit: degrees Celsius). The final stable temperature of the curve is Tf. In the figure, t1, t2, and t3 respectively represent three consecutive times, and T1, T2, and T3 are the temperature points corresponding to t1, t2, and t3. Assuming that t2 is the current moment, T2 is the normalized temperature point at the current moment; T3 is the normalized temperature corresponding to the next moment t3.

Assuming that the current heating power is 1W and the current temperature T1 at the current time t1 is 0.49°C, the temperature T2 at the next time t2 is 0.56°C, and the temperature T3 at the next time t3 is 0.62°C; assuming the current power remains unchanged, then The sequence of temperature changes is: T1→T2→T3. Eventually it will stabilize at a temperature point Tf of 1.91°C. The temperature curve below the specified normalized temperature point described above is described in accordance with the temperature of 1W; the subsequent need to be converted back to the actual temperature value according to the actual power value.

It should be noted that in this scheme, the temperature rise curve function is measured through experiments, and of course it can also be obtained through simulation calculations. In addition, when the power is reduced or zero, it enters the cooling stage, and the temperature drop curve function is also used, which is also obtained through experiments or simulation calculations.

Further, step S31 also includes:

If the first power parameter is less than or equal to zero, it means that the drive has been powered down and stopped providing electrical energy to the braking resistor. Then it is determined whether the first power parameter corresponding to the braking resistor at the first moment is less than the braking resistor at the third time. The power parameter corresponding to the time, the third time is the previous time of the first time;

If it is, it means that the temperature is entering the cooling stage at this time, and the first power parameter corresponding to the first moment is recorded as the power point of the braking resistor before cooling, and the normalization process is performed again to obtain the normalized temperature point;

In this embodiment, it also includes:

S5. Determine whether the actual temperature value at the next moment is greater than the preset threshold, and if so, trigger the protection mechanism of the driver. If it is estimated that the actual temperature value at the next moment is greater than the preset threshold, the preset threshold is set according to the critical value of the electrical performance of the braking resistor, indicating that there is a risk of damage to the braking resistor at the next moment, thus triggering the protection mechanism of the drive. For example, reduce the output power of the driver.

In summary, the present invention provides a method for detecting the temperature of the braking resistor in the drive. The real-time power parameters of the braking resistor are calculated after the drive is powered on, and normalized processing is performed to form the corresponding temperature rise. Curve function, the corresponding power parameter can be obtained at any subsequent time, and the temperature rise curve function can be used to calculate the temperature parameter corresponding to that time, so as to realize the detection of the brake resistor temperature. The whole detection method does not need to add hardware equipment, that is, it saves components, and it also has the advantages of high reliability and easy use. During production and installation, the temperature sensor installation process is not required, which reduces the requirements for assembly and improves production efficiency; in addition, in the actual use process, functional failures caused by device failures are also avoided, and reliability is improved.

The above are only the embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent transformations made using the content of the description and drawings of the present invention, or directly or indirectly applied in related technical fields, are included in the same reasoning. Within the scope of patent protection of the present invention.

Claims

A method for detecting the temperature of a braking resistor in a drive is characterized in that it comprises the following steps:

S1. After the driver is powered on, obtain the bus voltage value connected to the braking resistor and the resistance value of the braking resistor in real time, and calculate the real-time power parameters of the braking resistor;

S2. Normalize the real-time power parameter to obtain the temperature rise curve function corresponding to the braking resistor;

S3. Obtain the first power parameter corresponding to the braking resistor at the first moment, combine the first power parameter with a temperature rise curve function, and calculate the temperature parameter corresponding to the braking resistor at the first moment.
The method for detecting the temperature of the braking resistor in the drive according to claim 1, wherein step S1 is specifically:

Acquire the voltage value of the busbar connected to the braking resistor and the resistance value of the braking resistor in real time, and calculate the real-time power parameters of the braking resistor; at the same time, collect the corresponding temperature parameters;

The normalization processing in step S2 is specifically:

Divide the temperature parameter corresponding to the braking resistor at each moment after the drive is powered on by the corresponding power parameter to obtain the corresponding value.
The method for detecting the temperature of the braking resistor in the drive according to claim 1, wherein after step S3, the method further comprises:

S4. Determine whether the temperature parameter corresponding to the braking resistor at the first moment reaches the maximum value of the temperature rise curve function; if not, query the temperature rise curve function to obtain the second temperature rise curve function. The temperature parameter corresponding to the time; the second time is the time next to the first time.
The method for detecting the temperature of the braking resistor in the drive according to claim 3, characterized in that, between step S3 and step S4, the method further comprises:

S31. Determine whether the first power parameter is greater than zero, and if so, execute step S4.
The method for detecting the temperature of the braking resistor in the drive according to claim 4, wherein step S31 further comprises:

If the first power parameter is less than or equal to zero, it is determined whether the first power parameter corresponding to the braking resistor at the first time is less than the power parameter corresponding to the braking resistor at the third time, and the third time is the first time. The last moment of the moment

If yes, record the first power parameter corresponding to the first moment as the power point of the braking resistor before cooling down, and perform the normalization process again to obtain the normalized temperature point;

Use the normalized temperature point to query the preset temperature drop curve function to obtain the normalized temperature value at the next moment;

Convert the normalized temperature value at the next moment into the corresponding actual temperature to get the actual temperature value at the next moment.
The method for detecting the temperature of the braking resistor in the drive according to claim 3, wherein step S4 further comprises:

If the temperature parameter corresponding to the braking resistor at the first moment reaches the maximum value of the temperature rise curve function, it is determined whether the first power parameter corresponding to the braking resistor at the first moment is less than that of the braking resistor at the first moment. The power parameter corresponding to the third time, where the third time is the previous time of the first time;

If yes, record the first power parameter corresponding to the first moment as the power point of the braking resistor before cooling down, and perform the normalization process again to obtain the normalized temperature point;

Use the normalized temperature point to query the preset temperature drop curve function to obtain the normalized temperature value at the next moment;

Convert the normalized temperature value at the next moment into the corresponding actual temperature to get the actual temperature value at the next moment.
The method for detecting the temperature of the braking resistor in the drive according to claim 5 or 6, characterized in that it further comprises:

Determine whether the actual temperature value at the next moment is greater than the preset threshold, and if so, trigger the protection mechanism of the drive.