A parallel sampling current loop architecture and a motor control method

Abstract

The present invention provides a parallel sampling current loop architecture and a motor control method; the architecture includes: an input signal unit, configured to perform a first processing based on the difference between the current loop command and the estimated feedback signal to form an input signal; an inverter current unit, configured to perform an inversion processing on the input signal to obtain an inverter current; a current feedback unit, configured to perform N times of sampling on the inverter current in sequence within a control period under the control of a sampling control module, and perform analog-to-digital conversion and a second processing on the result of each current sampling to obtain and output a feedback current signal corresponding to each sampled current; a current estimation unit, configured to convert the input signal into an estimated feedback signal according to a preset corresponding rule between voltage and current; and further configured to correct the preset corresponding rule between voltage and current based on each received feedback current signal; wherein: the inverter current is output to the motor at the middle moment and the end moment of the control period to control the rotation speed of the motor.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular, to a parallel sampling current loop architecture and a motor control method Background Art

[0002] In a motor control scheme, the current loop needs to obtain the current sampling result of the current feedback link, and then combine the current sampling result with the current loop command to update the voltage command and transmit it to the subsequent link to complete the control of the motor

[0003] Please refer to Figure 1 , in the existing motor control scheme, the current is sampled twice and the PWM duty cycle is controlled twice within a control period. The sampling time is generally at the beginning and the middle of the control period, and the duty cycle is updated at the next middle or the beginning of the control period. Among them, the sampling accuracy is determined by the length of the sampling period. The longer the sampling period, the higher the sampling accuracy. Because the duty cycle is updated twice in one control period in the prior art, the longest time of each sampling period is one control period, which limits the sampling accuracy. Secondly, in the prior art, it takes 1.5 control periods from the start of current sampling to the change of the PWM duty cycle, and the response speed of the system is not ideal Summary of the Invention

[0004] The present invention provides a parallel sampling current loop architecture and a motor control method to achieve high-precision and high-response-speed control of the motor

[0005] According to a first aspect of the present invention, there is provided a parallel sampling current loop architecture for outputting a control current to control a motor. The architecture includes:

[0006] A forward motor control branch, which includes an input signal unit and an inverter current unit connected in series; the input signal unit is configured to perform a first process according to the difference between a current loop command and an estimated feedback signal to form an input signal; the output end of the inverter current unit is coupled to the motor; the inverter current unit is configured to receive the input signal and perform an inversion process on the input signal to obtain an inverter current; wherein, the current loop command is used to represent the d-axis current command and the q-axis current command; the inverter current is used to represent three-phase current

[0007] A current feedback unit, coupled to the output terminal of the inverter current unit; the current feedback unit is configured to sample the inverter current N times in a control period under the control of a sampling control module, and wait for a sampling period for each sampling to output a sampled current, and perform analog-to-digital conversion and a second process on each of the sampled currents to obtain and output a feedback current signal corresponding to each of the sampled currents; wherein, the feedback current signal is used to represent the actual feedback current signal of the d-axis and the actual feedback current signal of the q-axis; wherein, N is a positive integer, and 2≤N;

[0008] A current estimation unit, respectively coupled to the output terminal and the input terminal of the input signal unit, and the output terminal of the current feedback unit; the current estimation unit is configured to receive the input signal, and convert the input signal into an estimated feedback signal according to a preset correspondence rule between voltage and current; and the current estimation unit is further configured to receive the feedback current signal, and correct the preset correspondence rule between voltage and current according to the received feedback current signal each time; wherein, the estimated feedback signal is used to represent the estimated value of the feedback current signal corresponding to the input signal;

[0009] Wherein: the inverter current unit outputs the inverter current to the motor at the middle moment and the end moment of the control period respectively to control the rotation speed of the motor.

[0010] Optionally, the input signal unit includes a first adder, a difference adjustment unit, and a second adder;

[0011] The first adder is respectively coupled to the input terminal of the difference adjustment unit and the output terminal of the current estimation unit; the first adder is configured to receive the current loop command and the estimated feedback signal, calculate the difference between the current loop command and the estimated feedback signal, and output it;

[0012] The difference adjustment unit is coupled to the input terminal of the second adder; the difference adjustment unit is configured to output a control signal according to the input difference;

[0013] The second adder is coupled to the input terminal of the inverter current unit; the second adder is configured to receive a feedforward signal and the control signal, and combine the feedforward signal and the control signal to output the input signal; wherein, the feedforward signal is used to represent the mapped value of the current loop command mapped by a first mapping relationship.

[0014] Optionally, the difference adjustment unit includes a PID controller.

[0015] Optionally, the inverter current unit includes a voltage conversion unit;

[0016] The input terminal and the output terminal of the voltage conversion unit are respectively coupled to the output terminal of the second adder and the input terminal of the inverter; the voltage conversion unit is configured to receive the input signal, perform space vector conversion on the input signal, and output a duty cycle signal.

[0017] The output terminal of the inverter serves as the output terminal of the inverter current unit; the inverter is configured to output the inverter current according to the input duty cycle signal.

[0018] Optionally, the voltage conversion unit includes SVPWM.

[0019] Optionally, the sampling control module includes FPGA.

[0020] Optionally, the sampling control module is coupled to the current feedback unit; the sampling control module is configured to detect whether the sampling of the inverter current by the current feedback unit is affected by the PWM switch. If so, the sampling control module controls the current feedback unit not to output the corresponding feedback current signal; if not, the sampling control module controls the current feedback unit to output the corresponding feedback current signal.

[0021] Optionally, the sampling control module is configured to detect whether the sampling of the inverter current by the current feedback unit is affected by the PWM switch. Specifically, the sampling control module is configured to detect whether the difference between the middle moment of the sampling of the inverter current by the current feedback unit and the PWM switch moment is within the first threshold range. If so, the sampling of the inverter current by the current feedback unit is affected by the PWM switch; if not, the sampling of the inverter current by the current feedback unit is not affected by the PWM switch. Wherein, the PWM switch moment is used to represent the intersection moment of the triangular carrier wave and the PWM modulation wave during the motor control process.

[0022] According to a second aspect of the present invention, there is provided a motor control method, which utilizes the parallel sampling current loop architecture provided by the first aspect and optional solutions of the present invention. The method includes:

[0023] Performing a first processing on the difference between a current loop command and an estimated feedback signal to form an input signal; wherein, the current loop command is used to represent the d-axis current command and the q-axis current command.

[0024] Performing an inversion process on the input signal to output an inverter current; wherein, the inverter current is used to represent three-phase current.

[0025] The inverter current is sampled N times in sequence within a control period, and each sampling waits for a sampling period to output a sampled current. Each of the sampled currents is subjected to analog-to-digital conversion and a second process to obtain and output a feedback current signal corresponding to each of the sampled currents;

[0026] According to a preset correspondence rule between voltage and current, the feedback current signal corresponding to the input signal is estimated to obtain the estimated feedback signal, and the preset correspondence rule between voltage and current is corrected based on the actual feedback current signal; wherein, the feedback current signal is used to represent the actual d-axis feedback current signal and the actual q-axis feedback current signal; the estimated feedback signal is used to represent the estimated value of the feedback current signal corresponding to the input signal; wherein, N is a positive integer, and 2 ≤ N;

[0027] The inverter current is output to the motor at the middle moment and the end moment of the control period to control the rotational speed of the motor.

[0028] Optionally, the method further includes:

[0029] Detect whether the sampling of the inverter current is affected by the PWM switch. If so, the corresponding feedback current signal is not output; if not, the corresponding feedback current signal is output.

[0030] Optionally, detecting whether the sampling of the inverter current is affected by the PWM switch specifically includes: detecting whether the difference between the middle moment of sampling the inverter current and the PWM switch moment is within a first threshold range; if so, the sampling of the inverter current is affected by the PWM switch; if not, the sampling of the inverter current is not affected by the PWM switch; wherein, the PWM switch moment is used to represent the intersection moment of the triangular carrier wave and the PWM modulation wave during the motor control process.

[0031] According to the third aspect of the present invention, a control system is provided. The control system includes the parallel sampling current loop architecture provided by the first aspect and optional solutions of the present invention.

[0032] The parallel sampling current loop architecture provided by the present invention controls the current feedback unit to sample the inverter current N times in sequence within a control period through a sampling control module to improve the sampling accuracy; the current estimation unit quickly estimates the feedback current signal corresponding to the input signal according to a preset correspondence rule between voltage and current to reduce the feedback delay and improve the dynamic response performance of the system. At the same time, the current estimation unit also corrects the preset correspondence rule between voltage and current based on each received feedback current signal to improve the estimation accuracy of the feedback current signal. Description of the Drawings

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0034] Figure 1 It is the module structure of the parallel sampling current loop architecture provided by the embodiment of the present invention Figure 1 ;

[0035] Figure 2 It is the module structure of the parallel sampling current loop architecture provided by the embodiment of the present invention Figure 2 ;

[0036] Figure 3 It is the flow of the motor control method provided by the embodiment of the present invention Figure 1 ;

[0037] Figure 4 It is the flow of the motor control method provided by the embodiment of the present invention Figure 2 ;

[0038] Figure 5 It is the flow of the motor control method provided by the embodiment of the present invention Figure 3 . Description of the drawings:

[0040] 10 - Forward motor control branch;

[0041] 11 - Input signal unit;

[0042] 111 - Difference adjustment unit;

[0043] 12 - Inverter current unit;

[0044] 121 - Voltage conversion unit;

[0045] 122 - Inverter;

[0046] 20 - Current feedback unit;

[0047] 30 - Current estimation unit;

[0048] 40 - Sampling control module;

[0049] a1 - First adder;

[0050] a2 - Second adder;

[0051] b1 - Control signal;

[0052] b2 - duty cycle signal;

[0053] c1 - current loop command;

[0054] c2 - input signal;

[0055] c3 - inverter current;

[0056] c4 - feedback current signal;

[0057] c5 - estimated feedback signal. Detailed implementation manners

[0058] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0059] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned accompanying drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0060] Before elaborating on the embodiments of the present invention, a brief introduction to the design concept of the present invention is given first: In order to improve the sampling accuracy, it is necessary to extend the sampling period. However, extending the sampling period will increase the delay of current feedback and reduce the dynamic response of the system. To solve the problem of current feedback delay caused by extending the sampling period, the present invention estimates the current sampling result corresponding to the input signal c2 of the current SVPWM through a preset correspondence rule between voltage and current. In this way, the current sampling result can be estimated without waiting for a sampling period. However, the preset correspondence rule between voltage and current needs to continuously iterate the internal parameters through the actual current sampling result to make the estimated value continuously approach the true current sampling result. To solve the iteration problem of the internal parameters of the preset correspondence rule between voltage and current, the present invention performs N parallel samplings in sequence within one control period; in this way, when the current loop architecture operates stably, the preset correspondence rule between voltage and current can be iterated N times within one control period to ensure the estimation accuracy.

[0061] An embodiment of the present invention provides a parallel sampling current loop architecture. The parallel sampling current loop architecture includes:

[0062] A forward motor control branch 10, which includes an input signal c2 unit 11 and an inverter current unit 12 connected in series; the input signal c2 unit 11 is configured to perform a first process based on the difference between a current loop command c1 and an estimated feedback signal c5 to form an input signal c2; the output end of the inverter current unit 12 is coupled to the motor; the inverter current unit 12 is configured to receive the input signal c2 and perform an inversion process on the input signal c2 to obtain an inverter current c3; wherein, the current loop command c1 is used to represent the d-axis current command and the q-axis current command, wherein the d-axis current command is zero, and the motor speed is controlled by the q-axis current command; the inverter current c3 is used to represent three-phase current;

[0063] A current feedback unit 20 is coupled to the output terminal of the inverter current unit 12; the current feedback unit 20 is configured to sample the inverter current c3 N times in sequence within a control period under the control of a sampling control module 40, and for each sampling, wait for a sampling period and then output a sampled current, and perform analog-to-digital conversion and a second processing on each of the sampled currents to obtain and output a feedback current signal c4 corresponding to each of the sampled currents; wherein, the feedback current signal c4 is used to represent the actual feedback current signal of the d-axis and the actual feedback current signal of the q-axis; wherein, N is a positive integer and 2 ≤ N; specifically: the current feedback unit 20 includes an ADC, and the sampling control module 40 is specifically an FPGA. The FPGA controls the ADC to sample once every certain period of time, sample N times within a control period, and each sampling is independent of each other without affecting each other; among them, the current sampling scheme is divided into current mutual induction and resistor sampling, and resistor sampling can be further divided into bottom sampling, bus sampling, and high-end sampling. The specific sampling scheme to be adopted can be selected according to requirements and is not limited herein. In order to minimize the impact on the normal operation of the circuit as much as possible, the resistance value of the sampling resistor usually selected is generally very small (in the milliohm range), so the voltage across the resistor is often relatively small. For example, for a 10-milliohm resistor with a 10-ampere current flowing through it, the voltage across its two ends is only 100 millivolts. Therefore, an operational amplifier is required to amplify this voltage signal, and the amplified voltage signal is sent to the ADC of the MCU for analog-to-digital conversion, and then the result of the analog-to-digital conversion is subjected to a second processing to output the feedback current signal c4; wherein, the second processing is specifically Clarke transformation and Park transformation. Of course, within a control period, the number of parallel samplings can be adjusted according to actual requirements and is not limited herein.

[0064] The current estimation unit 30 is respectively coupled to the output end and the input end of the input signal c2 unit 11 and the output end of the current feedback unit 20; the current estimation unit 30 is configured to receive the input signal c2, and convert the input signal c2 into an estimated feedback signal c5 according to a preset corresponding rule between voltage and current; and the current estimation unit 30 is further configured to receive the feedback current signal c4, and correct the preset corresponding rule between voltage and current according to each received feedback current signal c4; wherein, the estimated feedback signal c5 is used to represent the estimated value of the feedback current signal c4 corresponding to the input signal c2. Specifically: the preset corresponding rule between voltage and current is specifically: within a plurality of control cycles, data fitting is performed on all the input signals c2 and the corresponding actual feedback current signals c4 to obtain a relationship model between the input signal c2 and the feedback current signal c4, so that the feedback current signal c4 corresponding to the current input signal c2 can be estimated to output the estimated feedback signal c5, and the parameters of the relationship model are continuously iterated through the actual feedback current signal c4, so that the estimated feedback signal c5 estimated through the relationship model continuously approaches the actual feedback current signal c4. The beneficial effect of the current estimation unit 30 is: when the sampling period is extended to improve the sampling accuracy, the current estimation unit 30 can estimate the feedback current signal c4 corresponding to the currently sampled but unoutput result, and then use the estimated value as the calculation basis for the current deviation to obtain a current feedback with lower delay. Among them, the whole process of performing data fitting on all the input signals c2 and the corresponding actual feedback current signals c4 to obtain a relationship model between the input signal c2 and the feedback current signal c4 is completed by a computer or an MCU or other processors, which is not limited herein.

[0065] Wherein: the inverter current unit 12 outputs the inverter current c3 to the motor at the middle moment and the end moment of the control cycle respectively to control the rotation speed of the motor.

[0066] As a specific implementation manner, the input signal c2 unit 11 includes a first adder a1, a difference adjustment unit 111, and a second adder a2;

[0067] The first adder a1 is respectively coupled to the input end of the difference adjustment unit 111 and the output end of the current estimation unit 30; the first adder a1 is configured to receive the current loop command c1 and the estimated feedback signal c5, calculate the difference between the current loop command c1 and the estimated feedback signal c5 and output it;

[0068] The difference adjustment unit 111 is coupled to the input end of the second adder a2; the difference adjustment unit 111 is configured to output a control signal b1 according to the input difference; the difference adjustment unit 111 is specifically a PID controller, which is configured to receive the difference between the current loop command c1 and the estimated feedback signal c5, and output the corresponding control signal b1 according to the difference to adjust subsequent links, so that the estimated feedback signal c5 approaches the current loop command c1.

[0069] The second adder a2 is coupled to the input end of the inverter current unit 12; the second adder a2 is configured to receive a feedforward signal and the control signal b1, and combine the feedforward signal and the control signal b1 to output the input signal c2; wherein, the feedforward signal is used to represent the mapped value of the current loop command c1 through the first mapping relationship. Among them, combining the current loop command c1 into the feedforward signal and the control signal b1 through the first mapping relationship is specifically current feedforward, and its purpose is to improve the response speed of motor control; wherein, the first mapping relationship is specifically an analog-to-digital conversion.

[0070] As a specific implementation manner, the inverter current unit 12 includes an inverter 122 and a voltage conversion unit 121;

[0071] The input end and the output end of the voltage conversion unit 121 are respectively coupled to the output end of the second adder a2 and the input end of the inverter 122; the voltage conversion unit 121 is configured to receive the input signal c2, perform space vector conversion on the input signal c2, and output a duty cycle signal b2; wherein, the voltage conversion unit 121 is specifically SVPWM, and its full name is Space Vector Pulse Width Modulation; the duty cycle signal b2 is specifically a switching signal, which is used to control the conduction time of each phase switch in the subsequent inverter 122.

[0072] The output end of the inverter 122 serves as the output end of the inverter current unit 12; the inverter 122 is configured to output the inverter current c3 according to the input duty cycle signal b2. Among them, the inverter current c3 is specifically the a-phase current, the b-phase current, and the c-phase current, and the output torque of the motor is controlled through the inverter current c3, that is, the speed of the motor is controlled.

[0073] As a specific implementation manner, the sampling control module 40 is further configured to detect whether the sampling of the inverter current c3 by the current feedback unit 20 is affected by the PWM switch. If so, the current feedback unit 20 is controlled not to output the corresponding feedback current signal c4; if not, the current feedback unit 20 is controlled to output the corresponding feedback current signal c4. Wherein, the switching moment of the PWM will interfere with the current sampling of the current feedback unit 20. Therefore, when the current sampling of the current feedback unit 20 is interfered by the PWM switching moment, the feedback current signal c4 corresponding to this sampling needs to be discarded.

[0074] As a specific implementation manner, the sampling control module 40 is configured to detect whether the sampling of the inverter current c3 by the current feedback unit 20 is affected by the PWM switch. Specifically: the sampling control module 40 is configured to detect whether the difference between the middle moment of the sampling of the inverter current c3 by the current feedback unit 20 and the PWM switching moment is within the first threshold range; if so, the sampling of the inverter current c3 by the current feedback unit 20 is affected by the PWM switch; if not, the sampling of the inverter current c3 by the current feedback unit 20 is not affected by the PWM switch; wherein, the PWM switching moment is used to represent the intersection moment of the triangular carrier wave and the PWM modulation wave during the motor control process. Among them, during the sampling process of the ADC, the sampling weights are not the same at different moments of the sampling period. Generally, the sampling weight is higher at the middle moment of the sampling period. Therefore, when the middle moment of a certain sampling is less than the first threshold range from the PWM switching moment, this sampling is affected by the PWM switching moment. Wherein, the first threshold range can be adjusted according to the actual degree of sampling interference and is not limited herein.

[0075] The embodiment of the present invention further provides a motor control method, which uses the parallel sampling current loop architecture provided by the embodiment of the present invention to control the motor. The method includes:

[0076] S1: Perform a first processing on the difference between a current loop command c1 and an estimated feedback signal c5 to form an input signal c2; wherein, the current loop command c1 is used to represent the d-axis current command and the q-axis current command.

[0077] S2: Perform an inversion process on the input signal c2 to output an inverter current c3; wherein, the inverter current c3 is used to represent three-phase current.

[0078] S3: Perform N samplings on the inverter current c3 in a control period in sequence, and wait for a sampling period for each sampling to output a sampling current.

[0079] S4: Perform analog-to-digital conversion and second processing on each of the sampled currents to obtain and output a feedback current signal c4 corresponding to each of the sampled currents.

[0080] S5: Estimate the feedback current signal c4 corresponding to the input signal c2 according to a preset correspondence rule between voltage and current to obtain the estimated feedback signal c5; wherein, the feedback current signal c4 is used to represent the actual feedback current signal of the d-axis and the actual feedback current signal of the q-axis; the estimated feedback signal c5 is used to represent the estimated value of the feedback current signal c4 corresponding to the input signal c2; wherein, N is a positive integer, and 2 ≤ N.

[0081] S6: Correct the preset correspondence rule between voltage and current according to the actual feedback current signal c4.

[0082] S7: Output the inverter current c3 to the motor at the middle moment and the end moment of the control period to control the speed of the motor.

[0083] As a specific implementation manner, the first processing of the difference between a current loop command c1 and an estimated feedback signal c5 in S1 to form an input signal c2 specifically includes:

[0084] S11: Calculate the difference between the current loop command c1 and the estimated feedback signal c5.

[0085] S12: Perform integral processing on the difference to obtain a control signal b1.

[0086] S13: Combine the control signal b1 with a feedforward signal to obtain the input signal c2; wherein, the feedforward signal is used to represent the mapped value of the current loop command c1 mapped by a first mapping relationship.

[0087] As a specific implementation manner, the inverter processing of the input signal c2 in S2 to output an inverter current c3 specifically includes:

[0088] S21: Perform space vector conversion on the input signal c2 to obtain a duty ratio signal b2.

[0089] S22: Control the on and off of each phase circuit switch of the inverter 122 according to the duty ratio signal b2 to output the inverter current c3.

[0090] As a preferred implementation manner, the motor control method further includes:

[0091] Detect whether the sampling of the inverter current c3 is affected by the PWM switch. If so, do not output the corresponding feedback current signal c4; if not, output the corresponding feedback current signal c4.

[0092] As a specific implementation, detecting whether the sampling of the inverter current c3 is affected by the PWM switch specifically includes: detecting whether the difference between the middle moment of sampling the inverter current c3 and the PWM switch moment is within the first threshold range; if so, the sampling of the inverter current c3 is affected by the PWM switch; if not, the sampling of the inverter current c3 is not affected by the PWM switch; wherein, the PWM switch moment is used to represent the intersection moment of the triangular carrier wave and the PWM modulation wave during the motor control process; of course, there are other judgment criteria for determining whether the sampling is affected by the PWM switch moment, such as observing whether there is serious envelope interference in the sampled feedback current signal c4 output, etc., which are not limited herein.

[0093] Taking eight parallel samplings in one control period as an example, the working process of the parallel sampling current loop architecture provided by the embodiment of the present invention is introduced as follows:

[0094] 1: Both the current loop command c1 and the estimated feedback signal c5 output by the current estimation unit 30 are input to the first adder a1 for subtraction; wherein, at this time, the estimated feedback signal c5 is the estimated value of the feedback current signal c4 corresponding to the input signal c2 of the previous control period.

[0095] 2: The obtained difference is input to the difference adjustment unit 111 for integral processing and the control signal b1 is output.

[0096] 3: The current loop command c1 is mapped through the first mapping relationship to obtain the feedforward signal, and the feedforward signal and the control signal b1 are both input to the second adder a2 for combination, and the input signal c2 is output to the voltage conversion unit 121 and the current estimation unit 30.

[0097] 4: The voltage conversion unit performs space vector on the input signal c2 and outputs the duty cycle signal b2 to the inverter 122.

[0098] 5: The inverter 122 outputs the inverter current c3 according to the duty cycle signal b2.

[0099] 6: The current feedback unit 20 performs the first sampling on the inverter current c3, and at the same time outputs the feedback current signal c4 corresponding to the first sampling of the previous control period to the current estimation unit 30 to correct the corresponding rule of voltage and current preset inside the current estimation unit 30.

[0100] 7: Based on the calibration result, the current estimation unit 30 outputs the calibrated estimated feedback signal c5 to perform a difference operation with the first adder a1 and the current loop command c1.

[0101] 8: Repeat the above steps 2 and 3 to obtain a new input voltage, and estimate the feedback current signal c4 corresponding to the new input voltage through the current estimation unit.

[0102] 9: Repeat the above steps 4 and 5. According to the new input voltage, obtain a new inverter current c3. The current feedback unit 20 performs a second sampling on the new inverter current c3, and at the same time outputs the feedback current signal c4 corresponding to the second sampling in the previous control cycle to the current estimation unit 30 to calibrate the corresponding rule of the preset voltage and current inside the current estimation unit 30.

[0103] 10: Repeat the above steps 7 to 9 until the current feedback unit 20 performs the fourth sampling and the eighth sampling, and outputs the inverter currents c3 corresponding to these two samplings to the motor to control the rotation speed of the motor; wherein, the start and end of each sampling are controlled by the FPGA, and the feedback current signal c4 corresponding to the sampling affected by the PWM switching moment is discarded by the FPGA.

[0104] The parallel sampling current loop architecture provided by the embodiment of the present invention has the following beneficial effects:

[0105] 1. High precision and low feedback delay. By extending the sampling period, the sampling precision is improved, and without waiting for one sampling period, the current estimation unit 30 can quickly estimate the feedback current signal c4 corresponding to the input voltage, reducing the feedback delay, and through N parallel samplings within one control cycle, the corresponding rule of the preset voltage and current in the current estimation unit 30 for the subsequent actual feedback current signal c4 is continuously iteratively corrected.

[0106] 2. Avoid being affected by the PWM switching moment. If a certain sampling is affected by the PWM switching moment, the feedback current signal c4 corresponding to this sampling is discarded by the FPGA.

[0107] The embodiment of the present invention also provides a control system, and the control system includes the parallel sampling current loop architecture provided by the embodiment of the present invention.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A parallel sampling current loop architecture for outputting a control current to control a motor, characterized in that The architecture includes: A forward motor control branch, which includes an input signal unit and an inverter current unit connected in series; the input signal unit is used to perform a first process based on the difference between a current loop command and an estimated feedback signal to form an input signal; the output end of the inverter current unit is coupled to the motor; the inverter current unit is used to receive the input signal and perform an inversion process on the input signal to obtain an inverter current; wherein, the current loop command is used to represent the d-axis current command and the q-axis current command; the inverter current is used to represent three-phase currents; A current feedback unit, coupled to the output end of the inverter current unit; the current feedback unit is used to perform N samplings on the inverter current in a control period under the control of a sampling control module, and each sampling waits for a sampling period to output a sampled current, and perform analog-to-digital conversion and a second process on each sampled current to obtain and output a feedback current signal corresponding to each sampled current; wherein, the feedback current signal is used to represent the d-axis actual feedback current signal and the q-axis actual feedback current signal; wherein, N is a positive integer, and 2≤N; A current estimation unit, respectively coupled to the output end and the input end of the input signal unit, and the output end of the current feedback unit; the current estimation unit is used to receive the input signal and convert the input signal into an estimated feedback signal according to a preset corresponding rule of voltage and current; and the current estimation unit is also used to receive the feedback current signal and correct the preset corresponding rule of voltage and current according to each received feedback current signal; wherein, the estimated feedback signal is used to represent the estimated value of the feedback current signal corresponding to the input signal; Wherein: The inverter current unit outputs the inverter current to the motor at the middle moment and the end moment of the control period respectively to control the rotation speed of the motor.

2. The parallel sampling current loop architecture according to claim 1, wherein The input signal unit includes a first adder, a difference adjustment unit, and a second adder; The first adder is respectively coupled to the input end of the difference adjustment unit and the output end of the current estimation unit; The first adder is used to receive the current loop command and the estimated feedback signal, calculate the difference between the current loop command and the estimated feedback signal and output it; The difference adjustment unit is coupled to the input end of the second adder; the difference adjustment unit is used to output a control signal according to the input difference; The second adder is coupled to the input end of the inverter current unit; the second adder is used to receive a feedforward signal and the control signal, and combine the feedforward signal and the control signal to output the input signal; wherein, the feedforward signal is used to represent the mapped value of the current loop command mapped by a first mapping relationship.

3. The parallel sampling current loop architecture according to claim 2, wherein The difference adjustment unit includes a PID controller.

4. The parallel sampling current loop architecture according to claim 3, characterized in that, The inverter current unit includes an inverter and a voltage conversion unit; The input terminal and the output terminal of the voltage conversion unit are respectively coupled to the output terminal of the second adder and the input terminal of the inverter; the voltage conversion unit is configured to receive the input signal, perform space vector conversion on the input signal, and output a duty cycle signal; The output terminal of the inverter serves as the output terminal of the inverter current unit; The inverter is configured to output the inverter current according to the input duty cycle signal.

5. The parallel sampling current loop architecture according to claim 4, characterized in that, The voltage conversion unit includes SVPWM.

6. The parallel sampling current loop architecture according to claim 5, characterized in that, The sampling control module includes FPGA.

7. The parallel sampling current loop architecture according to claim 6, wherein The sampling control module is coupled to the current feedback unit; the sampling control module is configured to detect whether the sampling of the inverter current by the current feedback unit is affected by the PWM switch. If so, the sampling control module controls the current feedback unit not to output the corresponding feedback current signal; if not, the sampling control module controls the current feedback unit to output the corresponding feedback current signal.

8. The parallel sampling current loop architecture according to claim 7, wherein The sampling control module is configured to detect whether the sampling of the inverter current by the current feedback unit is affected by the PWM switch. Specifically, the sampling control module is configured to detect whether the difference between the middle moment of the sampling of the inverter current by the current feedback unit and the PWM switch moment is within the first threshold range. If so, the sampling of the inverter current by the current feedback unit is affected by the PWM switch; if not, the sampling of the inverter current by the current feedback unit is not affected by the PWM switch. Wherein, the PWM switch moment is used to represent the intersection moment of the triangular carrier wave and the PWM modulation wave during the motor control process.

9. A motor control method, characterized in that, Using the parallel sampling current loop architecture according to any one of claims 1 to 8 to control a motor, the method includes: Performing a first process on the difference between a current loop command and an estimated feedback signal to form an input signal; wherein, the current loop command is used to represent the d-axis current command and the q-axis current command; Performing an inversion process on the input signal to output an inverter current; wherein, the inverter current is used to represent three-phase currents; Performing N times of sampling on the inverter current in a control period, and waiting for a sampling period to output a sampling current each time, and performing analog-to-digital conversion and a second process on each sampling current to obtain and output a feedback current signal corresponding to each sampling current; Estimating the feedback current signal corresponding to the input signal according to a preset correspondence rule between voltage and current to obtain the estimated feedback signal, and correcting the preset correspondence rule between voltage and current according to the actual feedback current signal; wherein, the feedback current signal is used to represent the d-axis actual feedback current signal and the q-axis actual feedback current signal; the estimated feedback signal is used to represent the estimated value of the feedback current signal corresponding to the input signal; wherein, N is a positive integer and 2≤N; Outputting the inverter current to the motor at the middle moment and the end moment of the control period to control the rotation speed of the motor.

10. The motor control method according to claim 9, characterized in that, The method further includes: Detect whether the sampling of the inverter current is affected by the PWM switch. If so, do not output the corresponding feedback current signal; if not, output the corresponding feedback current signal.

11. The motor control method according to claim 10, characterized in that, Detect whether the sampling of the inverter current is affected by the PWM switch, which specifically includes: detecting whether the difference between the intermediate moment of sampling the inverter current and the PWM switch moment is within the first threshold range; if so, the sampling of the inverter current is affected by the PWM switch; if not, the sampling of the inverter current is not affected by the PWM switch; wherein, the PWM switch moment is used to represent the intersection moment of the triangular carrier wave and the PWM modulation wave during the motor control process.

12. A control system, characterized in that, The control system includes the parallel sampling current loop architecture according to any one of claims 1 to 8.

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