A motor controller bus current estimation method, system, device, and medium

Abstract

This application discloses a method, system, device, and medium for estimating the bus current of a motor controller, belonging to the field of current estimation technology. The method for estimating the bus current of a motor controller includes the following steps: calculating the average phase current within one switching cycle; obtaining the actual dead time and converting the actual dead time into a proportion of one switching cycle; calculating the bus current based on the sector of the voltage vector, the average phase current, the duty cycle of the three-phase upper bridge, and the ratio of the dead time to the switching cycle; and smoothing the calculated bus current to obtain the estimated bus current. This disclosure uses three-phase current and three-phase upper bridge duty cycle to calculate the bus current, considers the average current of one switching cycle, considers the dead time, and different modulation methods such as DPWM and SVPWM, which can improve the estimation accuracy of the bus current.

Description

Technical Field

[0001] This application belongs to the field of current estimation technology, and in particular relates to a method, system, device and medium for estimating bus current of a motor controller. Background Technology

[0002] For automotive motor controllers, bus current is a quantity that needs to be collected or calculated. Currently, there are solutions that directly collect bus current using Hall effect sensors, solutions that estimate bus current using three-phase current and duty cycle, and solutions that calculate bus current using AC side power.

[0003] The scheme of directly acquiring bus current using Hall sensors not only increases cost and layout difficulty, but also increases system failure rate; the scheme of estimating bus current using three-phase current is not accurate and real-time enough for calculating the average phase current over a switching cycle, and some schemes require too many calibrations; the scheme of calculating bus current using AC side power has poor bus current estimation accuracy under low-speed conditions.

[0004] Therefore, it is necessary to provide a new method, system, device, and medium for estimating the bus current of a motor controller to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method, system, device, and medium for estimating the bus current of a motor controller in order to solve the above-mentioned problems.

[0006] This disclosure achieves the above objectives through the following technical solutions: A method for estimating the bus current of a motor controller includes the following steps: Calculate the average phase current over one switching cycle; Obtain the actual dead time and convert the actual dead time into a proportion of a switching cycle; The bus current is calculated based on the sector where the voltage vector is located, the average phase current, the duty cycle of the three-phase bridge, and the ratio of the dead zone to the operating cycle. The calculated bus current is smoothed to obtain the estimated bus current.

[0007] As a further optimization of this disclosure, the average phase current over one switching cycle is calculated using trigonometric functions and angle formulas, as follows:

[0008] in, IU_avr is the average phase current output of phase U; IV_avr is the average phase current of the V-phase output; IW_avr is the average phase current output of phase W; IU_sample is the actual sampled instantaneous current value of phase U; IV_sample is the actual sampled instantaneous current value of phase V; IW_sample is the actual sampled instantaneous current value of phase W; It is a current vector; The value represents the direction of rotation; it is 1 for clockwise rotation and -1 for counterclockwise rotation. For symbolic functions, To compensate for the angle.

[0009] As a further optimization of this disclosure, the actual dead time is converted into a proportion of one switching cycle, as shown in the following formula: ; Among them, T d This represents the actual dead time, which can be replaced by setting a dead time or obtained through offline calibration; T s This represents one switching cycle.

[0010] As a further optimization of this disclosure, the bus current is calculated based on the sector where the voltage vector is located, the average phase current, the duty cycle of the three-phase bridge, and the ratio of the dead zone to the switching cycle, as shown in the following formula: ; The signal of the sector where the voltage vector is located can be obtained through the motor control module; , , These are the upper bridge duty cycles for the longest, middle, and shortest operating phases of the sector, respectively. They can be duty cycle commands from the motor control module or the actual three-phase upper bridge duty cycles collected by the inverter. , , These are the phase currents of the sector's maximum active phase, intermediate active phase, and shortest active phase, respectively. This represents the proportion of the actual dead time relative to a switching cycle; the longest operating phase, the middle operating phase, and the shortest operating phase refer to the phases with the largest, middle, and smallest duty cycles of the upper bridge in a switching cycle, respectively.

[0011] As a further optimization of this disclosure, if we consider light load, over-modulation, or the use of DPWM modulation, there may be situations where the duty cycle of the upper bridge of a certain phase is 1 or close to 1, or 0 or close to 0. In such cases, the bus current formula can be modified, and the modified formula is as follows: ; in, hour, =0, otherwise =1; hour, =0, otherwise =1; As a default value, it can usually be set to... .

[0012] As a further optimization of this disclosure, the formula for calculating the bus current can also be adopted in the following form: Without considering light load, overmodulation, or the use of DPWM modulation, the calculation formula is as follows: ; Considering light load, overmodulation, or the use of DPWM modulation, the calculation formula is as follows: ; in, This is the electric mode indicator; the system is in electric mode when... ,otherwise .

[0013] As a further optimization of this disclosure, the smoothing process can be performed using a low-pass filter.

[0014] A motor controller bus current estimation system, comprising: The phase current correction module is used to calculate the average phase current over one switching cycle. The dead time calculation module is used to obtain the actual dead time and convert the actual dead time into a proportion of a switching cycle; The bus current calculation module is used to calculate the bus current based on the sector where the voltage vector is located, the average phase current, the duty cycle of the three-phase bridge, and the ratio of the dead zone to the duty cycle of the switch. The post-processing module is used to smooth the calculated bus current to obtain an estimated bus current.

[0015] An electronic device includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; The processor is used to execute the program stored in the memory to implement the motor controller bus current estimation method.

[0016] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the motor controller bus current estimation method.

[0017] The beneficial effects of this disclosure are as follows: The average phase current of one switching cycle is calculated using trigonometric functions and angle formulas, and corrections to the average phase current are considered based on motor operating conditions. Compared with the method of proportionally allocating phase current values ​​from the previous and current cycles, this method improves real-time performance and estimation accuracy. The bus current is calculated based on the sector where the voltage vector is located, and a unified calculation formula for bus current in different sectors is given. The influence of dead zone on bus current is also considered, which can improve the estimation accuracy. The impact of dead time on bus current estimation under operating conditions such as DPWM, SVPWM, and overmodulation is considered, and a unified calculation formula is given when considering DPWM and other operating conditions, which can improve the estimation accuracy. The calculated bus current is processed by filtering, and the final value of the bus current is determined according to whether the system is in ASC or SPO state, which effectively improves the estimation accuracy and real-time performance of the bus current and reduces calibration work. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a method in an embodiment of this disclosure; Figure 2 This is a system structure block diagram of an embodiment of this disclosure; Figure 3 This is a block diagram of the device structure in an embodiment of this disclosure. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] like Figure 1As shown, a method for estimating the bus current of a motor controller includes the following steps: S1. Calculate the average phase current over one switching cycle. When the motor speed is high, the motor rotates a large angle within one switching cycle. Calculating the average phase current over the switching cycle can reduce the error in bus current calculation. The phase current correction module uses trigonometric functions and angle formulas to calculate the average phase current over one switching cycle:

[0022] in, IU_avr is the average phase current output of phase U; IV_avr is the average phase current of the V-phase output; IW_avr is the average phase current output of phase W; IU_sample is the actual sampled instantaneous current value of phase U; IV_sample is the actual sampled instantaneous current value of phase V; IW_sample is the actual sampled instantaneous current value of phase W; It is a current vector; The value represents the direction of rotation; it is 1 for clockwise rotation and -1 for counterclockwise rotation. For symbolic functions, To compensate for the angle, . It is the electric angular frequency; For switching cycles; It depends on the phase current sampling position, and the range is 0~1. For PWM edge sampling, =0.5, for PWM center sampling =0; It is related to sampling delay, current ripple, motor parameters, motor operating conditions, etc., and can be obtained through calibration.

[0023] S2. Calculate the actual dead time and convert it into a proportion of one switching cycle, as shown in the following formula: The actual dead time can be obtained by setting a fixed dead time or through offline calibration.

[0024] S3. Based on the sector where the voltage vector is located, the average phase current... , , U, V, and W phases on the bridge are open for operation with duty cycles , , The ratio of dead zone to switching cycle The bus current is calculated in real time using the following formula: ; The sector signals can come from the motor control module; , , These are the upper bridge duty cycles of the longest, middle, and shortest operating phases in a certain sector, respectively. They can be duty cycle commands from the motor control module or the actual three-phase upper bridge duty cycles collected by the inverter. If they are duty cycle commands from the motor control module, they can be used after a one-cycle delay. It is a symbolic function; , , These represent the phase currents of the maximum, intermediate, and shortest active phases within a given sector, respectively. Here, m, n, and z may correspond to U, V, and W, depending on the modulation scheme (DPWM, SVPWM) and the sector range. According to the sector definition of SVPWM (usually rotated counterclockwise), the magnitude relationship of U, V, and W in each sector is shown in the table below:

[0025] This represents the ratio of the actual dead time to the switching cycle. The longest operating phase, the middle operating phase, and the shortest operating phase refer to the phases with the largest, middle, and smallest duty cycles on the upper bridge within a single switching cycle, respectively.

[0026] If we consider situations such as light load, over-modulation, or the use of DPWM modulation, where the duty cycle of the upper bridge in a certain phase might be 1, close to 1, 0, or close to 0, then the bus current formula can be modified. The modified formula is as follows: ; in, hour, =0, otherwise =1; hour, =0, otherwise =1. It can be adjusted as needed, and can usually be set to .

[0027] The formula for calculating bus current can also be expressed as follows: Without considering light load, overmodulation, or the use of DPWM modulation: ; Considering light load, overmodulation, or the use of DPWM modulation, etc.: ; in: This is the electric mode indicator; the system is in electric mode when... ,otherwise .

[0028] S4. Smooth the calculated bus current. Generally, low-pass filtering can be used for smoothing. Additionally, depending on the actual system state, determine whether the calculated bus current is valid. If the system is in ASC or SPO state, output 0 directly.

[0029] like Figure 2 As shown, an embodiment of this disclosure provides a motor controller bus current estimation system, including: The phase current correction module is used to calculate the average phase current over one switching cycle. The dead time calculation module is used to obtain the actual dead time and convert the actual dead time into a proportion of a switching cycle; The bus current calculation module is used to calculate the bus current based on the sector where the voltage vector is located, the average phase current, the duty cycle of the three-phase bridge, and the ratio of the dead zone to the duty cycle of the switch. The post-processing module is used to smooth the calculated bus current to obtain an estimated bus current.

[0030] The implementation process of the functions and roles of each module in the above system is detailed in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0031] For the system embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The system embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this disclosure according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0032] See Figure 3 The electronic device provided in the embodiments of this disclosure includes a processor 1110, a communication interface 1120, a memory 1130 and a communication bus 1140, wherein the processor 1110, the communication interface 1120 and the memory 1130 communicate with each other through the communication bus 1140. Memory 1130 is used to store computer programs; The processor 1110, when executing the program stored in the memory 1130, implements the above-described method for estimating the bus current of the motor controller.

[0033] The aforementioned communication bus 1140 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus 1140 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, it is represented by only one thick line in the figure, but this does not indicate that there is only one bus or one type of bus.

[0034] The communication interface 1120 is used for communication between the above-mentioned electronic device and other devices.

[0035] The memory 1130 may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory 1130 may also be at least one storage device located remotely from the aforementioned processor 1110.

[0036] Embodiments of this disclosure also provide a computer-readable storage medium. The computer-readable storage medium stores a computer program that, when executed by a processor, implements the motor controller bus current estimation method as described above.

[0037] The embodiments described above are merely examples of several implementations of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent disclosure. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this disclosure, and these modifications and improvements all fall within the protection scope of this disclosure.

Claims

1. A method for estimating bus current in a motor controller, characterized in that, Includes the following steps: Calculate the average phase current over one switching cycle; Obtain the actual dead time and convert the actual dead time into a proportion of a switching cycle; The bus current is calculated based on the sector where the voltage vector is located, the average phase current, the duty cycle of the three-phase bridge, and the ratio of the dead zone to the operating cycle. The calculated bus current is smoothed to obtain the estimated bus current.

2. The method for estimating the bus current of a motor controller according to claim 1, characterized in that the current reconstruction uses trigonometric functions and angle formulas to calculate the average phase current within one switching cycle, as shown in the following formula: in, IU_avr is the average phase current output of phase U; IV_avr is the average phase current of phase V output; IW_avr is the average phase current output of phase W; IU_sample is the actual sampled instantaneous current value of phase U; IV_sample is the actual sampled instantaneous current value of phase V; IW_sample is the actual sampled instantaneous current value of phase W; It is a current vector; The value represents the direction of rotation; it is 1 for clockwise rotation and -1 for counterclockwise rotation. For symbolic functions, To compensate for the angle.

3. The method for estimating the bus current of a motor controller according to claim 1, characterized in that, The actual dead time is converted into a proportion of a single switching cycle, as shown in the following formula: ； in, T d This represents the actual dead time. The actual dead time can be replaced by setting the dead time, or it can be obtained through offline calibration. T s This represents one switching cycle.

4. The method for estimating the bus current of a motor controller according to claim 1, characterized in that, The bus current is calculated based on the sector where the voltage vector is located, the average phase current, the duty cycle of the three-phase bridge, and the ratio of the dead zone to the switching cycle, using the following formula: ； in, The signal of the sector where the voltage vector is located can be obtained through the motor control module; , , These are the upper bridge duty cycles for the longest, middle, and shortest operating phases of the sector, respectively. They can be duty cycle commands from the motor control module or the actual three-phase upper bridge duty cycles collected by the inverter. , , These are the phase currents of the sector's maximum active phase, intermediate active phase, and shortest active phase, respectively. This represents the proportion of the actual dead time relative to one switching cycle. The longest operating phase, the middle operating phase, and the shortest operating phase refer to the phases with the largest, middle, and smallest duty cycles of the upper bridge in a single switching cycle, respectively.

5. The method for estimating the bus current of a motor controller according to claim 4, characterized in that, If we consider light load, over-modulation, or the use of DPWM modulation, there may be situations where the duty cycle of the upper bridge in a certain phase is 1 or close to 1, or 0 or close to 0. In such cases, the bus current formula can be modified. The modified formula is as follows: ； in, hour, =0, otherwise =1; hour, =0, otherwise =1; As a default value, it can be set to .

6. The method for estimating the bus current of a motor controller according to claim 5, characterized in that, The formula for calculating bus current can also be expressed as follows: Without considering light load, overmodulation, or the use of DPWM modulation, the calculation formula is: ； Considering light load, overmodulation, or the use of DPWM modulation, the calculation formula is as follows: ； in, This is the electric mode indicator; the system is in electric mode when... ,otherwise .

7. The method for estimating the bus current of a motor controller according to claim 1, characterized in that, The smoothing process is performed using a low-pass filter.

8. A motor controller bus current estimation system, characterized in that, include: The phase current correction module is used to calculate the average phase current over one switching cycle. The dead time calculation module is used to obtain the actual dead time and convert the actual dead time into a proportion of a switching cycle; The bus current calculation module is used to calculate the bus current based on the sector where the voltage vector is located, the average phase current, the duty cycle of the three-phase bridge, and the ratio of the dead zone to the duty cycle of the switch. The post-processing module is used to smooth the calculated bus current to obtain an estimated bus current.

9. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; A processor is used to execute a program stored in a memory to implement the motor controller bus current estimation method according to any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the method for estimating the bus current of the motor controller as described in any one of claims 1-7.

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