A motor and a method, system and program product for power integration calculation of a controller thereof

Abstract

The application provides a motor and a motor controller power integration calculation method, system and program product, including power integration and reset functions, containing several integrators with different integration times, containing weighted calculation of the integrators, and containing an algorithm for saving integrator data storage stack space. The determination of the number of integrators, the selection of integration time, the selection of integration interval, the selection of integrator weight, and the space saving of integration data stack, etc. The integrator integration time and the weight of each integrator can be adjusted arbitrarily according to the performance requirements. The RAM resource demand can be greatly reduced by adjusting the integration interval time. The integration result can be used for cooling strategy formulation or redundancy capability evaluation.

Description

Technical Field

[0001] This invention belongs to the field of motor drive technology, specifically relating to a method for calculating the power integral of a motor and its controller. Background Technology

[0002] Within specific hardware constraints, the electric drive system should achieve optimal power output. To maximize power output and extend the lifespan of the electric drive system, it's necessary to assess the total heat generated over a certain period during operation and then match appropriate cooling strategies in real time. Furthermore, for new energy vehicles, the drive motor needs to maintain a certain level of redundancy during operation to handle sudden acceleration, engine starting, and regenerative braking. Typically, the motor controller assesses its historical load and submits the maximum power capacity the system can support for a future period to the vehicle controller, allowing the vehicle controller to take proactive measures to prevent performance limitations or even dangerous situations.

[0003] The power integral of a motor and its controller refers to the calculation of the cumulative values ​​of the motor's torque, speed, and mechanical power over a period of time; and the calculation of the cumulative values ​​of the bus current, phase current, active power, and DC power over a period of time. By evaluating the cumulative values ​​of these parameters or the cumulative values ​​of their equivalent thermal effects, the total thermal load of the motor or its controller over the aforementioned integral time period can be measured. This is a prerequisite for formulating cooling strategies and estimating redundancy capabilities for the scenarios described above.

[0004] In power integration, the selection of the integration time is crucial. Different functional requirements and different system modes have varying integration time requirements. In some scenarios, both short and long integration times have their drawbacks and cannot meet the requirements of strategy formulation. Furthermore, power integration involves the stack storage of the key parameters mentioned earlier, which places high demands on the controller's RAM. How to conserve RAM resources while ensuring sufficient integration information is a problem that needs to be considered. Summary of the Invention In response to the problems and needs of existing technologies, this invention provides a method, system, and program product for calculating the power integral of motors and motor controllers, which can be used in new energy power motors to reduce the demand for RAM resources and provide accurate and efficient integral results for the formulation of cooling strategies or the assessment of redundancy capabilities of motors and motor controllers.

[0005] The technical solution adopted in this invention is as follows: In a first aspect, this invention provides a method for calculating the power integral of a motor and a motor controller, used in new energy power motors, comprising the following steps: S1: Data Preprocessing The input signal is preprocessed, including but not limited to the following methods or combinations thereof: 1. Amplitude limiting: The input signal is limited to a reasonable range of physical values ​​for integration, avoiding input values ​​exceeding limits due to malfunctions in preceding stages, which would affect the integration results. 2. Absolute value taking: Some physical quantities, such as torque, are represented as signed scalars in digital control systems, with positive and negative signs indicating different directions. However, in practical applications, power is generally the primary consideration. Therefore, the absolute value is taken to prevent data with different signs from canceling each other out after entering the integrator, thus affecting the integration evaluation results. 3. Square taking: Some physical quantities, such as current, are generally considered primarily for their thermal effect in practical applications, therefore the square is taken.

[0006] S2: Memory Design Since microcontrollers generally use a fixed-step discrete computing method, discretization is required before integration, which involves storing the processed data. In this patent, the variables defined in the software to store the antiderivative of integration are referred to as memory, and these variables are declared before the calculation begins.

[0007] In this step, the preprocessed data is stored. This process involves several pre-defined discrete data memories, denoted as n. Typically, n=3, but can be simplified to two or more memories can be added as needed. The storage duration of each memory is different, denoted as t1, t2, ..., tn. The memory's calculation process is uniformly discrete, with each calculation interval being Δt1, Δt2, ..., Δtn. The memories store data in a stack according to data category, initially set to 0. After data enters, before the storage duration is full, the 0 values ​​in the storage space are replaced sequentially. After the storage duration is full, the last data to enter pushes out the first data to enter. The memories can be reset by an external trigger signal.

[0008] Here, the storage time tn is primarily determined based on performance requirements and the physical meaning of the data. The interval time Δtn is primarily determined based on the storage capacity of the system's hardware RAM and the physical meaning of the data. At a specific solution time t... s In a digital control system, Δt n It needs to be set to t s When the value is an integer multiple of the original value, the RAM storage space consumed is reduced to t times the original value after adopting this strategy. s / Δt n The data updated in the storage can be c n The integrand data during reset can also be the data in Δt. n The average value of the data integrated over a time period. The latter requires matching with c during implementation. n The accumulator is reset at the same time.

[0009] S3: Data Integration The data in each memory is accumulated and converted into data per second. After processing, the unit of the output data is consistent with the unit of the input data.

[0010] S4: Weighted Average of Data The data in each memory location is weighted and averaged. The weights are arbitrarily selected based on performance requirements and calibration results. In practical applications, the weights need to be selected according to system characteristics and performance requirements to enhance system robustness.

[0011] S5: Data Post-processing Post-processing of the integrator output data includes, but is not limited to: 1. Limiting, to avoid invalid output data due to logic execution or hardware failure; 2. Square root, for current data that has been squared during preprocessing, the result after integration is the current thermal effect, and the effective current can be obtained by taking the square root of it.

[0012] In a second aspect, the present invention also provides a power integral calculation system for a motor and a motor controller, comprising: The data preprocessing module is used to preprocess the input signal, including but not limited to amplitude limiting, absolute value taking, square taking, biasing, gain adjustment, or table lookup.

[0013] The memory design module includes: n preset discrete data memories, the storage duration of different memories is denoted as t1, t2, ..., tn, and the interval time of each calculation step of the memory is Δt1, Δt2, ..., Δtn; the memory stores data in the form of a stack according to data category, with the initial value set to 0. After data enters, before the storage duration is full, the 0 values ​​in the storage space are replaced in turn. After the storage duration is full, the last data to enter pushes out the first data to enter; the memory can be reset by an external trigger signal.

[0014] The data integration module is used to accumulate the data in each memory and convert it into data per second.

[0015] The integral weighted average module is used to perform weighted averaging on the data in each memory, with the weights selected based on performance requirements and calibration results.

[0016] The data post-processing module is used to post-process the data output by the integrator, including but not limited to limiting, square rooting, biasing, gaining, or table lookup.

[0017] In a third aspect, the present invention also provides a computer program product comprising a software code portion, wherein when the computer program product is run on a computer, the software code portion is used to execute the steps of the power integral calculation method for the motor and motor controller described in the first aspect above.

[0018] The motor controller employing this method needs to have one or more of the following: phase current sensor, speed sensor, and bus voltage sensor. Alternatively, it can acquire these signals or their functional equivalents via communication protocols such as CAN communication or hardwired connections. This invention can be applied to common microcontroller platforms and implemented using common programming languages, requiring no special software or hardware development environment.

[0019] In summary, this invention, based on a digital controller, establishes a method for discrete integration calculation of data such as motor torque, speed, mechanical power, and motor controller bus current, bus power, three-phase current, active power, and DC power. This calculation method includes power integration and reset functions; it includes several integrators with different integration times; it includes weighted calculations of the aforementioned integrators; and it includes algorithms for saving integrator data storage stack space. Sub-strategies include determining the number of integrators, selecting integration time, selecting integration interval, selecting integrator weights, and saving space in the integration data stack.

[0020] Using the technical solution of this invention, the integration time and weights of each integrator can be arbitrarily adjusted according to performance requirements, and RAM resource requirements can be significantly reduced by adjusting the integration interval. The integration results can be used for cooling strategy formulation or redundancy capability assessment.

[0021] This invention can be applied to pure electric vehicles, hybrid electric vehicles, or other road vehicles or construction machinery that use electric motors. The applicant has modeled and simulated the above method in Simulink, and the function is effective and the execution is efficient. Attached Figure Description Figure 1 This is a flowchart of the integral calculation method of the present invention; Figure 2 This is an example of the counter trigger signal of the present invention; Figure 3 Examples of calculation results from integrators with different integration times according to the present invention; Figure 4 This is an example of the calculation results when the integrators of this invention are assigned different weights. Detailed Implementation Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, parameter values ​​can be reasonably adjusted according to the actual situation of the vehicle and should not be limited to the embodiments described herein.

[0022] Example 1: Reference Figure 1 In one embodiment of the invention, a specific method for integral calculation is provided, the specific steps of which are as follows: S1: Data Preprocessing This step involves preprocessing the input signal, including but not limited to the following methods or combinations thereof: 1. Limiting: This function restricts the input signal to a reasonable range of physical values ​​for integration calculation, preventing input values ​​from exceeding limits due to malfunctions in preceding stages, which could affect the integration results. For example, if the peak torque of an electric drive system is 330 Nm, the limiting circuit would be set to an upper limit of 330 Nm and a lower limit of -330 Nm.

[0023] 2. Taking the absolute value: Some physical quantities, such as torque, are represented as signed scalars in digital control systems, with positive and negative signs indicating different directions. However, in practical applications, power is generally the primary consideration. Therefore, taking the absolute value avoids the cancellation of data with different signs entering the integrator sequentially, which would affect the integral evaluation result. In this embodiment, the torque is limited and then its absolute value is calculated.

[0024] 3. Taking the square: For some physical quantities, such as electric current, in practical applications, we generally mainly consider their thermal effect, so we take the square.

[0025] 4. Based on the actual meaning of the physical quantity, other mapping operations can also be performed, such as bias, gain, or table lookup.

[0026] According to an embodiment of the present invention, the signal may be a physical signal obtained from a phase current sensor, speed sensor and / or bus voltage sensor of the motor, or a digital signal or any functionally equivalent signal obtained through a communication protocol such as CAN communication.

[0027] If the signal originates from a motor or electric motor controller, it is acquired by the sensor, sampled by the ADC, and directly uploaded to the main controller for calculation. If the signal originates from another controller, it is transmitted via the CAN communication protocol, parsed by the CAN communication chip, and uploaded to the main controller for calculation. Besides the difference in the signal-emitting controller, the difference lies in the fact that the signal acquired from the sensor is a voltage physical signal directly mapped to the measured physical quantity; while the signal from CAN communication is a digital signal from serial communication. Both signal types can be calculated using this method.

[0028] S2: Memory Design The data after clipping is stored. This process includes: S21. Determine the number of memory units: Determine a certain number of preset discrete data memory units, denoted as n, typically n=3, but can be simplified to two or more memory units as needed.

[0029] S22. Storage duration selection: Select different storage durations for different memories, denoted as t1, t2, ..., tn.

[0030] S23. Selection of the calculation interval time: The calculation process of the memory is uniformly discrete. It is necessary to confirm the interval time for each step of calculation, denoted as Δt1, Δt2, …, Δtn.

[0031] S24. Definition and initialization of each memory: The memory stores data in the form of a stack according to the data category and needs to be initialized with an initial value of 0. After the data enters, before the storage duration is full, it will replace the 0 value in the storage space in turn. After the storage duration is full, the last entered data will push out the first entered data. Taking the integrator with integration time t1 as an example, what it stores is all the data within the t1 period before the current moment. When the actual running time t < t1, the data before t1 is recorded as 0.

[0032] The memory can be reset by an external trigger signal. This step involves the selection of two groups of key parameters. One is the values of the storage times t1, t2, …, tn, and the other is the values of the interval times Δt1, Δt2, …, Δtn. For the storage time, the value is mainly based on the performance requirements and combined with the physical meaning of the data. For example, if the peak power running time of the motor confirmed by performance is 20s, then the shortest power storage time t1 can be selected as 20s to reflect the transient power change of the motor. Another example is that if the thermal stability time of the electric drive system measured by experiment is 600s, then the longest power storage time t3 (let n = 3 for example) can be selected as 600s to reflect the long-term power load of the motor. The intermediate storage time t2 can take the arithmetic mean or geometric mean of t1 and t3, and at this time it has both instantaneous and long-term characteristics. Generally, when n > 3, the storage duration can be set as an arithmetic or geometric sequence. For the interval time, the value is mainly based on the storage scale of the system hardware RAM and combined with the physical meaning of the data. The storage scale of each memory is: single data length * t n / Δt n , the single data length is determined in a specific task, and t n is also determined according to the above principle, then the larger Δt n , the smaller the required RAM resources, but the larger Δt n , the lower the data update frequency and the worse the calculation accuracy of the integrator. Generally, for integrators based on the application scenarios of thermal load assessment and power capacity estimation, high integration accuracy is not required. For example, for the transient memory with t1 = 20s, selecting Δt1 as 0.1 - 0.5s can meet the requirements. For the long-term memory with t3 = 600s, selecting Δt n as 1 - 5s can meet the requirements. The longer the storage time, the lower the requirement for timeliness and the higher the requirement for storage space, and it is more suitable to select a longer interval time. In a digital control system with a specific calculation time t s , Δt n needs to be set to t sWhen the value is an integer multiple of the original value, this strategy reduces the RAM storage space consumed to t times the original value. s / Δt n .

[0033] S25. Cyclic Counter Design: In practice, n accumulators c can be set. n Threshold th n =Δt n / t s; S26. c n The initial value is 0; S27. During calculation, c is solved each time. n =c n +1, and repeat; S28. Until c n ≥th n; S29. Update the memory once, and reload c. n Set to zero, return to S26, and repeat this cycle to achieve the desired result every Δt. n Update memory n once.

[0034] For example, the internal calculation time t of the program s It is 0.1s, while Δt n If we choose 1s, then th n If the value is set to 10, the data will be updated every 10 settlement cycles. The updated data can be c. n The integrand data during reset can also be the data in Δt. n The average value of the data integrated over a time period. The latter has higher accuracy and is less affected by high-frequency fluctuations in the data, but requires matching with c. n The accumulator is reset at the same time.

[0035] S3: Data Integration S31. Perform integration operations on the data in each memory.

[0036] S32. And converted to data per second.

[0037] The specific calculation method is as follows: Integration result = Σ integrand * Δt n / t n The purpose is to ensure that, after processing, the units of the output data are consistent with the units of the input data. For example, t n =600s, Δt n When the value is 5s, the actual number of data accumulations within 600s is 120. The accumulation result should be divided by the number of accumulations to obtain the average value.

[0038] S4: Weighted Average of Data A weighted average is calculated for the data in each memory location.

[0039] S41. First, list the data in each integrator; S42. Take weights ηt1, ηt2, ηt 3; S43. Multiply the integrator data by the corresponding weights respectively; S44. Finally, divide the sum of all the above products by the total weight.

[0040] The weights can be arbitrarily selected based on performance requirements and calibration results. For example, when evaluating the instantaneous power of the system, the t1 integrator can be given the highest weight, such as ηt1:ηt2:ηt3 = 5:1:1; when evaluating the overall heat load of the system, the t1, t2, and t3 integrators can be given the same weight, ηt1:ηt2:ηt3 = 1:3:1. The higher the weight of the short-time integrator, the more sensitive the overall output integral response, but it is easily affected by transient values, causing jumps in power estimation. The higher the weight of the long-time integrator, the more stable the overall output integral response, but the timeliness is poor. In practical applications, the weights need to be selected according to the system characteristics and performance requirements to enhance the system robustness.

[0041] S5: Data Post-processing S51. Post-process the data output by the integrator, including but not limited to: 1. Limit the amplitude to prevent invalid output data due to logic execution or hardware failure.

[0042] 2. Square root: For current data that has been squared during preprocessing, the result after integration is the current-thermal effect. Taking the square root of this result yields the effective current.

[0043] 3. Based on the actual meaning of the physical quantity, other mapping operations can also be performed, such as bias, gain, or table lookup.

[0044] Example 2: This embodiment is a power integral calculation system for a motor and motor controller, which includes the following unit modules: The data preprocessing module is used to preprocess the input signal, including but not limited to amplitude limiting, absolute value taking, square taking, biasing, gain adjustment, or table lookup.

[0045] The memory design module includes: n preset discrete data memories, the storage duration of different memories is denoted as t1, t2, ..., tn, and the interval time of each calculation step of the memory is Δt1, Δt2, ..., Δtn; the memory stores data in the form of a stack according to data category, with the initial value set to 0. After data enters, before the storage duration is full, the 0 values ​​in the storage space are replaced in turn. After the storage duration is full, the last data to enter pushes out the first data to enter; the memory can be reset by an external trigger signal.

[0046] The above memory design module, at a specific calculation time t s In a digital control system, Δt n Set to t s The data updated in the memory is an integer multiple of the counter c. n The data being integrated in real time during reset, or in Δt n The average of the data integrated over a time period, the latter need to be matched with a counter c. n The accumulator is reset at the same time.

[0047] The data integration module is used to accumulate the data in each memory and convert it into data per second. The data integration calculation method used is: Integration result = Σ integrand * Δt n / t n .

[0048] The integral weighted average module is used to perform weighted averaging on the data in each memory, with the weights selected based on performance requirements and calibration results.

[0049] The data post-processing module is used to post-process the data output by the integrator, including but not limited to limiting, square rooting, biasing, gaining, or table lookup.

[0050] The following section models and simulates some key steps, and analyzes the execution results: Reference Figure 2 The image shows an example of the counter trigger signal of the present invention. In the example, t... s =0.1s, Δt n =1s, then th n =10. Each time the function is called, c... n +1, for every ten function calls, c n ≥th n When the condition is met, the trigger signal sends a high level, the memory updates the data once, and c is reset. n .

[0051] Reference Figure 3The image shows examples of integrator calculation results for different integration times according to the present invention. In the examples, t1 = 20s, t3 = 600s, and t2 is taken as the geometric mean of the two, approximately 135s. The top image shows the motor torque signal input as a test case, and the bottom image shows the output results of the three integrators at different times. It can be seen that the shorter the integration time, the better the tracking effect of the integration result on the instantaneous value, but the fluctuation is more severe; the longer the integration time, the more stable the integration result, but the timeliness is poor. Integration results with different performance can be applied in suitable application scenarios.

[0052] Reference Figure 4 The image shows examples of calculation results when different weights are applied to the integrators of this invention. In the examples, ηt1:ηt2:ηt3 = 5:1:1 and 1:3:1 are used respectively. The former exhibits more characteristics of an instantaneous integrator, while the latter shows more balanced characteristics. Regardless of the integrator type, due to the existence of long-time integration, the accumulated torque is not zeroed during the short-term motor pause—this is necessary in scenarios evaluating heat dissipation requirements, as the heat transfer process of the electric drive system cannot reach a steady state within 20 seconds. When the time constant of the physical process being evaluated is large, the weight of the integrator with the longer integration time can be appropriately increased.

[0053] Preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. While some embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are for illustrative purposes only and are not intended to limit the scope of protection of the present application.

[0054] It should be understood that the steps described in the method embodiments of this application may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this application is not limited in this respect.

[0055] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. Furthermore, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for calculating the power integral of a motor and a motor controller, characterized in that, Includes the following steps: S1. Data preprocessing: Preprocess the input signal, including limiting, taking the absolute value, squaring, biasing, gaining, or looking up a table; S2. Memory Design: Includes: n preset discrete data memories, each memory having a storage duration of t1, t2, ..., t... n They are all different, and the time interval for each calculation step in the memory is Δt1, Δt2, ..., Δt. n Furthermore, the longer the storage duration of a memory, the larger its integration interval Δt, in order to reduce the amount of data stored per unit time, thereby reducing RAM resources. The memory stores data in a stack according to data category, initially set to 0. As data enters, it sequentially replaces the 0 values ​​in the storage space before the storage time is full. Once the storage time is full, the last data to enter pushes out the first data. The memory can be reset by an external trigger signal. During the calculation time t... s In a digital control system, Δt n Set to t s When the value is an integer multiple of t, the RAM storage space consumed is reduced to t times the original value. s / Δt n ; S3. Data integration: Accumulate the data in each memory and convert it into data per second; S4. Integral-weighted average: The data in each memory is weighted and averaged, with the weights selected based on performance requirements and calibration results; S5. Data post-processing: Post-process the data output by the integrator, including limiting, square root, bias, gain, or table lookup.

2. The method for calculating the power integral of a motor and motor controller according to claim 1, characterized in that, In step S2, the data updated in the memory is the counter c. n The data being integrated in real time during reset, or in Δt n The average of the data integrated over a time period, the latter need to be matched with a counter c. n The accumulator is reset at the same time.

3. The method for calculating the power integral of a motor and motor controller according to claim 1, characterized in that, The data integration calculation method for S3 is as follows: Integration result = Σ integrand data × Δt n / t n .

4. The method for calculating the power integral of a motor and motor controller according to claim 1, characterized in that, The signal is a physical signal obtained from the phase current sensor, speed sensor and / or bus voltage sensor of the motor, or a digital signal or any functionally equivalent signal obtained through the CAN communication protocol.

5. The method for calculating the power integral of a motor and motor controller according to claim 1, characterized in that, The signals include motor torque, speed, mechanical power, and motor controller bus current, bus power, three-phase current, and active power.

6. A power integral calculation system for a motor and motor controller, characterized in that, include: The data preprocessing module is used to preprocess the input signal, including limiting, taking the absolute value, taking the square, biasing, gaining, or looking up a table; The memory design module includes: n preset discrete data memories, each with a storage duration of t1, t2, ..., tt. n They are all different, and the time interval for each calculation step in the memory is Δt1, Δt2, ..., Δt. n The memory stores data in a stack according to data category, initially set to 0. As data enters, it replaces the 0 values ​​in the storage space sequentially before the storage time is full. Once the storage time is full, the last data to enter pushes out the first data to enter. The memory can be reset by an external trigger signal. During the calculation time t... s In a digital control system, Δt n Set to t s When the value is an integer multiple of t, the RAM storage space consumed is reduced to t times the original value. s / Δt n ; The data integration module is used to accumulate the data in each memory and convert it into data per second; The integral weighted average module is used to perform a weighted average of the data in each memory, with the weights selected based on performance requirements and calibration results; The data post-processing module is used to post-process the data output by the integrator, including but not limited to limiting, square rooting, biasing, gaining, or table lookup.

7. The power integral calculation system for the motor and motor controller according to claim 6, characterized in that, The memory design module updates the data in the counter c. n The data being integrated in real time during reset, or in Δt n The average of the data integrated over a time period, the latter need to be matched with a counter c. n The accumulator is reset at the same time.

8. The power integral calculation system for the motor and motor controller according to claim 6, characterized in that, The data integration module uses the following data integration calculation method: Integration result = Σ integrand data × Δt n / t n .

9. A computer program product, characterized in that, Includes a software code portion, which, when the computer program product is run on a computer, is used to perform the steps of the power integral calculation method for the motor and motor controller according to any one of claims 1 to 5.

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