Self-adaptive current-limiting protection strategy of motor main drive controller

Abstract

The invention discloses a self-adaptive current-limiting protection strategy of a motor main drive controller, and belongs to the technical field of motor control. The method specifically comprises the steps that five temperature intervals are divided by four temperature points under different working conditions; according to a self-adaptive algorithm, ideal current-limiting thresholds at respective temperatures are calculated; calculating and obtaining a current-limiting piecewise function based on the four ideal current-limiting thresholds; when the temperature of the main drive controller is measured, the temperature interval where the main drive controller is located is judged according to the temperature value, and then the obtained temperature interval is subjected to current limiting value setting according to the corresponding calculation function in the current limiting piecewise function. According to the method, the optimal current limiting value can be adaptively predicted and found according to the working conditions, so that accurate and efficient current limiting under different working conditions is effectively realized by adopting a linear segmentation strategy, the requirement of a protection function of the controller is ensured, the power output of the controller can be ensured not to be limited, and the performance of the controller is greatly ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and more specifically to an adaptive current limiting protection strategy for a motor main drive controller. Background Art

[0002] At present, most of the main drive controllers for vehicles use a fixed current limit value to implement the current limit strategy. This current limit strategy is too single and cannot adapt to all working conditions of the controller. It will cause the current limit value to be too large under certain working conditions, causing the MOS / IGBT to burn out, and it may also cause the current limit value to be too small under certain working conditions, making the controller power unable to be fully utilized. Therefore, the control strategy of a single fixed current limit value cannot meet the full performance of the motor controller under complex and changeable working conditions.

[0003] A Chinese patent with publication number CN 115276483A discloses a motor control system and method based on three-stage current limiting, including: a motor and a controller, the motor including a temperature sensor; the temperature sensor is used to detect the current temperature of the motor and send the current temperature to the controller; the controller is used to receive the current temperature sent by the temperature sensor; if the current temperature is less than a first set threshold, a first current limiting value is output; if the current temperature is greater than the first set threshold and less than a second set threshold, the first current limiting value is adjusted to a second current limiting value; if the current temperature is greater than the second set threshold, the second current limiting value is adjusted to a third current limiting value.

[0004] Although the patent sets two set thresholds to divide the temperature into three intervals, each temperature interval corresponds to a current limit value, and the current limit value is adjusted by the controller, so that the electric vehicle can quickly pass through the low-efficiency area to achieve the purpose of energy saving; and within the range allowed by the motor temperature, the performance of the motor is fully utilized to improve the user experience. However, under some different working conditions, even in the same temperature range, the current limit value of the motor will be different. Therefore, the accuracy of the current limit using a fixed current limit value in the same temperature range is not high enough, and the performance of the controller cannot be guaranteed. Summary of the invention

[0005] The present invention provides an adaptive current limiting protection strategy for a motor main drive controller to solve the shortcomings of the existing motor current limiting control that the current limiting accuracy is not high enough in the same temperature range using a fixed current limiting value and the controller performance cannot be guaranteed.

[0006] The present invention adopts the following technical solution: An adaptive current limiting protection strategy for a motor main drive controller includes the following steps: Step 1: Under different working conditions, five temperature intervals are divided by four temperature points, where the four temperature points are , , and ,but ; Step 2: Calculate the , , and The ideal current limiting thresholds at different temperatures are , , and ; Step 3: Calculate the current limiting piecewise function based on the four current limiting ideal thresholds in step 2. The current limiting piecewise function is as follows: ; Step 4: When the temperature of the main drive controller is measured, first determine the temperature range it is in based on the temperature value, and then set the current limiting value for the obtained temperature range according to the corresponding calculation function in the current limiting piecewise function in step 3.

[0007] In step 2 above Ideal current limit threshold at temperature The adaptive algorithm is as follows: ①Assume that in the 0th generation setting, the initial current limit value is set to , the convergence region parameter is , and calculate the impact factor as and : , , η 1+ η 2=1; ②If there is an ideal current limit value , assuming that the deviation from the ideal current limit value of the first generation is called the "1st generation offset ”, set to ; ③ Based on the above ① and ② conditions, calculate the ideal current limiting threshold in the first generation and the offset from the first generation , that is: ; ④ Similarly, the ideal current limiting threshold of the second generation can be calculated and the offset from the first generation , where the ideal current limiting threshold will gradually converge iteratively until the first The ideal current limit threshold If satisfied , then the ideal current limiting threshold Set to the temperature The ideal current limit threshold , that is, .

[0008] Above , .

[0009] Above , and Ideal current limit threshold at temperature , and The adaptive algorithm and Ideal current limit threshold at temperature The adaptive algorithm is the same.

[0010] The current limiting piecewise function in step 3 above is obtained by the following method: ①When NTC measures the temperature of the controller Less than or equal to When the current limiting threshold is ; ②When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of current limiting in this section as ; ③When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of this current limit as ; ④When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of this current limit as .

[0011] ⑤When NTC measures the temperature of the controller Greater than When the current limiting threshold is .

[0012] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages: 1. The present invention can adaptively predict and find the optimal current limiting value according to the working conditions, thereby adopting a linear segmented strategy to effectively achieve accurate and efficient current limiting under different working conditions, which not only ensures the protection function requirements of the controller, but also ensures that the output power of the controller is not restricted, greatly ensuring the performance of the controller.

[0013] 2. The present invention divides the temperature range into five sections, and uses linear interpolation to calculate the current limiting value under each working condition in each section. The control and strategy of the current limiting will be more accurate, and it also provides a certain reference for the current limiting protection of the motor main drive controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0015] The specific implementation of the present invention is described below with reference to the accompanying drawings. In order to fully understand the present invention, many details are described below, but for those skilled in the art, the present invention can be implemented without these details. For well-known components, methods and processes, they are not described in detail below.

[0016] This embodiment provides an adaptive current limiting protection strategy for the motor main drive controller. Figure 1 , including the following steps: Step 1: Under different working conditions, five temperature intervals are divided by four temperature points, where the four temperature points are , , and (Unit: ℃), the size relationship of the four temperature points is .

[0017] Step 2: Calculate the ideal current limiting threshold at each temperature based on the adaptive algorithm. For example, the adaptive algorithm is as follows: ① Assume that in the 0th generation (initial state) setting, the initial current limit value is set to , the convergence region parameter is . And calculate the impact factor set to and , which is calculated as follows: , which can be taken ; , which can be taken ; ②If there is an ideal current limit value , then assuming that the deviation from the ideal current limit value of the first generation is called the "1st generation offset ”, set to ; ③Then according to the above conditions ① and ②, the ideal current limiting threshold in the first generation can be calculated and the offset from the first generation , that is: ④ Similarly, the ideal current limiting threshold of the second generation can be calculated and the offset from the first generation , where the ideal current limiting threshold will gradually converge iteratively until the first The ideal current limit threshold If satisfied , then the ideal current limiting threshold Set to the temperature The ideal current limit threshold , that is, .

[0018] Step 3: After obtaining the above Ideal current limit at temperature Afterwards, we can obtain , and Ideal current limit at temperature , and .

[0019] Step 4: Based on the above ideal current limiting value, a current limiting function is obtained. This current limiting function is a linear piecewise function. The main method is as follows: ①When NTC measures the temperature of the controller Less than or equal to When the current limiting threshold is ; ②When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of current limiting in this section as ; ③When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of this current limit as ; ④When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of this current limit as ; ⑤When NTC measures the temperature of the controller Greater than When the current limiting threshold is ; ⑥ Write a piecewise function for current limiting as follows: .

[0020] The main control logic of the present invention is as follows: When the controller's NTC (or PT100, PT1000) measures the temperature of the motor controller, first determine its temperature range based on the temperature value, and then set the current limiting value based on the corresponding calculation function in the current limiting piecewise function in step 4.

[0021] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. An adaptive current limiting protection strategy for a motor main drive controller, characterized in that: The steps include: Step 1: Under different working conditions, five temperature intervals are divided by four temperature points, where the four temperature points are , , and ,but ; Step 2: Calculate the , , and The ideal current limiting thresholds at different temperatures are , , and ; Step 3: Calculate the current limiting piecewise function based on the four current limiting ideal thresholds in step 2. The current limiting piecewise function is as follows: ; Step 4: When the temperature of the main drive controller is measured, first determine the temperature range it is in based on the temperature value, and then set the current limiting value for the obtained temperature range according to the corresponding calculation function in the current limiting piecewise function in step 3.

2. The adaptive current limiting protection strategy of the motor main drive controller according to claim 1, characterized in that: In step 2 Ideal current limit threshold at temperature The adaptive algorithm is as follows: ①Assume that in the 0th generation setting, the initial current limit value is set to , the convergence region parameter is , and calculate the impact factor as and : , , η 1+ η 2=1; ②If there is an ideal current limit value , assuming that the deviation from the ideal current limit value of the first generation is called "1st generation offset ”, set to ; ③ Based on the above ① and ② conditions, calculate the ideal current limiting threshold in the first generation and the offset from the first generation , that is: ; ④ Similarly, the ideal current limiting threshold of the second generation can be calculated and the offset from the first generation , where the ideal current limiting threshold will gradually converge iteratively until the first The ideal current limit threshold If satisfied , then the ideal current limiting threshold Set to temperature The ideal current limit threshold , that is, .

3. The adaptive current limiting protection strategy of the motor main drive controller according to claim 2, characterized in that: Said , .

4. The adaptive current limiting protection strategy of the motor main drive controller according to claim 2, characterized in that: Said , and Ideal current limit threshold at temperature , and The adaptive algorithm and Ideal current limit threshold at temperature The adaptive algorithm is the same.

5. The adaptive current limiting protection strategy of the motor main drive controller according to claim 1, characterized in that: The current limiting piecewise function in step 3 is obtained by the following method: ①When NTC measures the temperature of the controller Less than or equal to When the current limiting threshold is ; ②When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of current limiting in this section as ; ③When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of this current limit as ; ④When NTC measures the temperature of the controller Greater than , less than or equal to When the function expression is calculated according to the linear relationship, the two coordinates are and , and calculate its slope as , and define the expression of this current limit as ; ⑤When NTC measures the temperature of the controller Greater than When the current limiting threshold is .

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