Three-phase current reconstruction method, device and computer-readable storage medium

Abstract

The present invention discloses a three-phase current reconstruction method, device and computer-readable storage medium. The three-phase current reconstruction method includes: obtaining a current phase current sampling signal, and converting the current phase current sampling signal into a target phase current effective value; setting a target current stabilization time according to the target phase current effective value; calculating a target holding time of a sampling area according to the target current stabilization time, and configuring a target voltage vector of the sampling area according to the target holding time. The present invention sets a corresponding current stabilization time by using the phase current effective value, so that the current stabilization time is determined according to the phase current effective value, and then controls the minimum holding current to be determined according to the phase current effective value, effectively avoiding the situation where the minimum holding time is too large or too small, and ensuring the accuracy of the sampling result.

Description

Technical Field

[0001] The present invention relates to the field of motor control technology, and in particular to a three-phase current reconstruction method, device and computer-readable storage medium. Background Art

[0002] The existing compressor current single resistor sampling has two methods: phase shift and injection. Regardless of the phase shift and injection methods, the minimum holding time must be guaranteed. If the minimum holding time is set too large, it will affect the current waveform under low load. If the minimum holding time is set too small, it will affect the current sampling under high load. Specifically, the existing PWM sampling method is a 7-segment mode. The schematic diagram of a PWM signal cycle is as follows: Figure 1 As shown, during sampling, the PWM signal is sampled once in areas ② and ③ respectively. However, in the actual sampling process, if the minimum holding time of area ② or area ③ is set too large, it will cause current deformation and bring high-frequency noise. If the minimum holding time of area ② or area ③ is set too small, it is easy to sample interference signals, which will ultimately affect the accuracy of the sampling results.

[0003] Therefore the prior art still needs to be improved and enhanced. Summary of the invention

[0004] The object of the present invention is to provide a three-phase current reconstruction method, device and computer-readable storage medium, which can effectively solve the problem that the accuracy of the sampling result is affected by setting the minimum holding time too large or too small.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A three-phase current reconstruction method, comprising:

[0007] Obtaining a current phase current sampling signal, and converting the current phase current sampling signal into a target phase current effective value;

[0008] Set the target current stabilization time according to the target phase current effective value;

[0009] A target holding time of the sampling region is calculated according to the target current stabilization time, and a target voltage vector of the sampling region is configured according to the target holding time.

[0010] A three-phase current reconstruction device comprises a memory, a processor and a three-phase current reconstruction program stored in the memory and executable on the processor. When the processor executes the three-phase current reconstruction program, the three-phase current reconstruction method is implemented.

[0011] A computer-readable storage medium stores a three-phase current reconstruction program, which implements the steps of the above-mentioned three-phase current reconstruction method when executed by a processor.

[0012] Compared with the prior art, the present invention provides a three-phase current reconstruction method, device and computer-readable storage medium, which obtains the current phase current sampling signal and converts the current phase current sampling signal into a target phase current effective value, sets a target current stabilization time according to the target phase current effective value, calculates the target holding time of the sampling area according to the target current stabilization time, and configures the target voltage vector of the sampling area according to the target holding time; the present invention sets the corresponding current stabilization time according to the phase current effective value, so that the current stabilization time is determined according to the phase current effective value, and then controls the minimum holding current to be determined according to the phase current effective value, effectively avoiding the situation where the minimum holding time is too large or too small, and ensuring the accuracy of the sampling result. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the existing PWM state diagram;

[0014] Figure 2 A flowchart of the steps of the three-phase current reconstruction method provided by the present invention;

[0015] Figure 3 A flowchart of step S11 in the second embodiment of the three-phase current reconstruction method provided by the present invention;

[0016] Figure 4 A comparison diagram of phase current effective values ​​and current stabilization time in the second embodiment of the three-phase current reconstruction method provided by the present invention;

[0017] Figure 5 A flow chart of step S100 of the three-phase current reconstruction method provided by the present invention;

[0018] Figure 6 A schematic diagram of a motor control circuit provided by the present invention;

[0019] Figure 7 A current comparison table corresponding to each state of the PWM control switch provided by the present invention;

[0020] Figure 8 This is a flow chart of the software processing steps in the three-phase current reconstruction method provided by the present invention. DETAILED DESCRIPTION

[0021] The object of the present invention is to provide a three-phase current reconstruction method, device and computer-readable storage medium, which can effectively solve the problem that the accuracy of the sampling result is affected by setting the minimum holding time too large or too small.

[0022] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] See also Figure 2 The present invention provides a three-phase current reconstruction method, which is applied to a three-phase current reconstruction device. The method includes:

[0024] S100, obtaining a current phase current sampling signal, and converting the current phase current sampling signal into a target phase current effective value;

[0025] S200, setting a target current stabilization time according to a target phase current effective value;

[0026] S300 , calculating a target holding time of a sampling region according to a target current stabilization time, and configuring a target voltage vector of the sampling region according to the target holding time.

[0027] In this embodiment, the target holding time includes dead time, current stabilization time and sampling time, that is, the target holding time is the sum of dead time, current stabilization time and sampling time, wherein the dead time and sampling time are both fixed values, and the current stabilization time changes with the change of the effective value of the phase current, thereby controlling the target holding time to be a dynamically changing value. When the effective value of the phase current changes, the corresponding control target holding time changes accordingly, and the corresponding current stabilization time is set according to the effective value of the phase current, and then the target voltage vector of the sampling area in the next PWM cycle is configured according to the latest target holding time, thereby avoiding the situation where the target holding time is too large or too small, and ensuring the accuracy of the sampling result.

[0028] Furthermore, before obtaining the current phase current sampling signal, the method further includes:

[0029] S10. Preset a mapping relationship between the effective value of the phase current and the current stabilization time.

[0030] In this embodiment, a mapping relationship between the effective value of the phase current and the current stabilization time is pre-set, and the mapping relationship is stored so that the corresponding current stabilization time can be selected according to the current effective value of the phase current when current sampling is performed later; then, the target holding time is calculated based on the selected current stabilization time and the fixed sampling time and the fixed dead time to ensure the accuracy of the target holding time setting, so as to ensure the accuracy of the sampling result.

[0031] Furthermore, in the first embodiment of the present invention, the mapping relationship between the effective value of the phase current and the current stabilization time is pre-set, including:

[0032] S11. Establish in advance a comparison table of phase current effective values ​​and current stabilization time.

[0033] In this embodiment, when establishing a mapping relationship between the effective value of the phase current and the current stabilization time, a comparison table of the effective value of the phase current and the current stabilization time can be selected; the comparison table is provided with phase current effective value partitions, each phase current effective value partition corresponds to a current stabilization time, and correspondingly also corresponds to a target holding time. Among them, the number of phase current effective value partitions in the comparison table can be adjusted according to time, and the current stabilization time of different phase current effective value partitions can be set in the debugging stage and fixed later, so as to determine the target holding time in the actual current sampling process.

[0034] Furthermore, in this embodiment, setting the target current stabilization time according to the target phase current effective value includes:

[0035] S210. Search the target current stabilization time corresponding to the target phase current effective value according to the comparison table.

[0036] In this embodiment, after establishing a comparison table of phase current effective values ​​and current stabilization times, the comparison table is stored; when actually sampling current, the current phase current sampling signal is obtained, and the current phase current effective value is obtained based on the current phase current sampling signal, and the table is checked to confirm in which phase current effective value partition the phase current effective value is located, and the corresponding current stabilization time is selected based on the phase current effective value partition; after selecting the current stabilization time, the target holding time is calculated, thereby realizing the selection of the target holding time based on the current phase current effective value.

[0037] For further information, see Figure 3 In the second embodiment of the present invention, the mapping relationship between the effective value of the phase current and the current stabilization time is pre-set, including:

[0038] S11, pre-setting a linear relationship between the effective value of the phase current and the current stabilization time, so that the current stabilization time = K*effective value of the phase current, K is a proportional gain coefficient;

[0039] S12. Preset the maximum and minimum values ​​of the current stabilization time.

[0040] The mapping relationship between the effective value of the phase current (Irms in this embodiment) and the current stabilization time (Ttsd in this embodiment) in the second embodiment of the present invention can also be achieved by constructing a linear relationship, such as Figure 4As shown, a formula is used to relate the effective value of the phase current to the current stabilization time, that is, the current stabilization time = K*effective value of the phase current, wherein K is the proportional gain coefficient; then, the range of K values ​​is selected to set the maximum value of the current stabilization time (Ttsdmax in this embodiment) and the minimum value of the current stabilization time (Ttsdmin in this embodiment), so as to subsequently determine the minimum value holding time according to the current effective value of the phase current.

[0041] Furthermore, in this embodiment, the target current stabilization time is set according to the target phase current effective value, including:

[0042] S210. Calculate the target current stabilization time according to the target phase current effective value and the linear relationship.

[0043] In this embodiment, when actually sampling the current, the current phase current sampling signal is obtained, and the current phase current effective value is obtained based on the current phase current sampling signal. Combined with the pre-set linear relationship, the current stabilization time corresponding to the phase current effective value is inferred, thereby realizing the selection of the target holding time based on the current phase current effective value.

[0044] Furthermore, before calculating the target holding time of the sampling area according to the target current stabilization time, the method further includes:

[0045] S20, obtaining a periodic target voltage vector of the next PWM period.

[0046] In this embodiment, after obtaining the current phase current effective value, the current stabilization time is looked up in a table or calculated according to the current phase current effective value, and then the periodic target voltage vector of the next PWM period is calculated; for details, please continue to refer to Figure 1 Each PWM cycle is divided into 7 regions. The period target voltage vector of each PWM cycle is the sum of the voltage vectors applied to the motor in these seven regions. For example, the voltage vectors applied to the motor in the seven regions are Vt1-Vt7 respectively. Then the period target voltage vector (denoted as Vo in this embodiment) is the sum of the voltage vectors from Vt1 to Vt7. The period target voltage vector is obtained to facilitate the subsequent configuration of the target voltage vectors of each region of the PWM cycle according to the target holding time.

[0047] For further information, see Figure 5 , converting the current phase current sampling signal into the target phase current effective value, including:

[0048] S110, searching the switch state current comparison table of the previous PWM cycle according to the current phase current sampling signal to obtain the corresponding phase current sampling value;

[0049] S120 , after integrating the corresponding phase current sampling values, obtain the target phase current effective value.

[0050] The three-phase current reconstruction method in this embodiment is based on the existing motor control circuit, such as Figure 6 As shown, the motor control circuit includes PWM control switches Q1-Q6, a sampling resistor R1, a sampling module and a motor; the state of the switch is controlled by a PWM signal to control the state of the motor, and accordingly, the current flowing through the sampling resistor R1 in each switch state corresponds to a different phase current combination; wherein, switches Q1 and Q4 are in a complementary state, Q2 and Q5 are in a complementary state, Q3 and Q6 are in a complementary state, and six switches constitute three half-bridges, such as Figure 7 As shown, these six switch devices are combined into a total of 8 safe switch states. Among them, 000 and 111 (here representing the switch states of the three lower bridge arms) will not generate effective current in the motor drive, so they become zero vectors, and the other 6 switch states are six effective vectors, V0 to V7 respectively correspond to the voltage vectors in the 8 switch states; then the present invention determines the state of the PWM control switch according to the current phase current sampling signal after obtaining the current phase current sampling signal, and thus searches for the corresponding phase current sampling value according to the state of the PWM control switch, and then integrates the phase current sampling value to obtain the phase current effective value, so as to obtain the corresponding target holding time later.

[0051] For a better understanding of the present invention, the following Figure 8 , the software processing process of the three-phase current reconstruction method provided by the present invention is described in detail by taking a specific application embodiment, that is, the steps of the software processing of the three-phase current reconstruction method are as follows:

[0052] S1. Obtain phase current sampling signals and convert the phase current sampling signals into phase current sampling values;

[0053] S2, integrating the phase current sampling value to obtain the phase current effective value;

[0054] S3, calculating and obtaining the period target voltage vector of the next PWM period;

[0055] S4. Look up the table or calculate to obtain the current stabilization time;

[0056] S5. Calculate the target holding time according to the formula;

[0057] S6. Reconfigure the voltage vector and sampling point of the PWM cycle.

[0058] After current sampling in this embodiment, the current phase current sampling signal is obtained, and the phase current sampling value is obtained by looking up the table according to the phase current sampling signal. The phase current effective value is obtained after integration processing of the current sampling value, and then the period target voltage vector of the next PWM cycle is calculated. After the calculation is completed, the current stabilization time is obtained by looking up the table or calculating according to the phase current effective value, and then the target holding time is calculated according to the current stabilization time. Because the size of the voltage vector applied to the motor in each area of ​​the PMM is related to time, the larger the voltage vector applied to the motor in this area, the longer the time corresponding to this area, so the target voltage vector of the sampling area can be set according to the target holding time. In this embodiment, sampling is performed once in each of the second and third areas, and then the target voltage vectors of the second and third areas are set according to the target holding time of the second and third areas. After the setting is completed, the target voltage vectors of the fifth and sixth areas are set according to the unchanged period target voltage vector within one cycle, thereby completing the reconfiguration of the voltage vectors of each area in the PWM cycle, and correspondingly updating the value of the sampling register, setting a new sampling point, ensuring that the target holding time of the sampling area is neither too small nor too large, and thus ensuring the accuracy of the sampling result.

[0059] The present invention also provides a three-phase current reconstruction device, which includes a memory, a processor, and a three-phase current reconstruction program stored in the memory and runable on the processor. When the processor executes the three-phase current reconstruction program, the above-mentioned three-phase current reconstruction method is implemented. Since the three-phase current reconstruction method is described in detail above, it will not be repeated here.

[0060] Furthermore, the present invention also provides a storage medium, on which a three-phase current reconstruction program is stored, and the three-phase current reconstruction program is executed by a processor to perform the steps of the above-mentioned three-phase current reconstruction device. Since the three-phase current reconstruction method of a single resistor has been described in detail above, it will not be described in detail here. Please refer to the embodiment corresponding to the above method for details.

[0061] In summary, the present invention provides a three-phase current reconstruction method, device and computer-readable storage medium, wherein the three-phase current reconstruction method obtains the current phase current sampling signal and converts the current phase current sampling signal into a phase current effective value, sets the current stabilization time according to the phase current effective value, calculates the target holding time of the sampling area according to the current stabilization time, and configures the target voltage vector of the sampling area according to the target holding time; the present invention sets the corresponding current stabilization time according to the phase current effective value, so that the current stabilization time is determined according to the phase current effective value, and then controls the minimum holding current to be determined according to the phase current effective value, effectively avoiding the situation where the target holding time is too large or too small, and ensuring the accuracy of the sampling result.

[0062] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A three-phase current reconstruction method, characterized in that: include: Presetting a mapping relationship between the effective value of the phase current and the current stabilization time includes: presetting a linear relationship between the effective value of the phase current and the current stabilization time, so that the current stabilization time=K*the effective value of the phase current, K is a proportional gain coefficient; presetting a maximum value and a minimum value of the current stabilization time; Acquire the current phase current sampling signal and convert the current phase current sampling signal into the target phase current effective value, including: searching the switch state current comparison table of the previous PWM cycle according to the current phase current sampling signal to obtain the corresponding phase current sampling value; integrate the corresponding phase current sampling value to obtain the target phase current effective value; Setting a target current stabilization time according to the target phase current effective value; The target holding time of the sampling area is calculated according to the target current stabilization time, the target holding time is the sum of the dead time, the current stabilization time and the sampling time, and the target voltage vector of the sampling area is configured according to the target holding time. The target voltage vector of the sampling area is set according to the target holding time. The size of the voltage vector applied to the motor by the target voltage vector of the sampling area is related to time. The larger the voltage vector applied to the motor in this area, the longer the time corresponding to this area.

2. The method according to claim 1, characterized in that The presetting of the mapping relationship between the phase current effective value and the current stabilization time includes: A comparison table of phase current effective value and current stabilization time is established in advance.

3. The method according to claim 2, characterized in that The step of setting a target current stabilization time according to the target phase current effective value comprises: The target current stabilization time corresponding to the target phase current effective value is searched according to the comparison table.

4. The method according to claim 1, characterized in that: The step of setting a target current stabilization time according to the target phase current effective value comprises: The target current stabilization time is calculated according to the target phase current effective value and the linear relationship.

5. The method according to claim 1, characterized in that Before calculating the target holding time of the sampling region according to the target current stabilization time, the method further includes: Get the cycle target voltage vector for the next PWM cycle.

6. A three-phase current reconstruction device, characterized in that: The three-phase current reconstruction device includes a memory, a processor, and a three-phase current reconstruction program stored in the memory and executable on the processor. When the processor executes the three-phase current reconstruction program, the steps of the three-phase current reconstruction method as described in any one of claims 1 to 5 are implemented.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a three-phase current reconstruction program, and when the three-phase current reconstruction program is executed by the processor, the steps of the three-phase current reconstruction method according to any one of claims 1 to 5 are implemented.

Images