Bus capacitance online identification method and device of motor driving system, and electrical equipment

Abstract

The invention discloses an on-line identification method and device for a bus capacitor of a motor driving system and electrical equipment, the motor driving system comprises a PFC circuit, a bus capacitor and an inverter circuit which are connected in sequence, and the method comprises the following steps: in the process of controlling the PFC circuit to work, applying an alternating current signal to a modulation signal of the PFC circuit, an AC voltage is generated on the bus capacitor; acquiring bus voltage and bus current; and determining the capacitance value of the bus capacitor according to the bus voltage and the bus current. According to the method, online identification of the capacitance value of the bus capacitor can be achieved in a simple mode, the requirement for the identification environment is not high, and the method has high robustness.

Description

Technical Field

[0001] The present invention relates to the field of motor drive, and in particular to a method and device for online identification of bus capacitance of a motor drive system, and electrical equipment. Background Art

[0002] In the motor drive system, the mains power needs to be converted into direct current through a rectifier, and then multi-phase alternating current is generated through an inverter to drive the motor. At the same time, in order to achieve decoupling between the AC input side and the inverter output side, a large-capacity electrolytic capacitor is usually required as the bus capacitor to maintain the stability of the bus voltage. However, since the capacitance of the electrolytic capacitor is greatly affected by the stability of the ambient temperature, during the operation of the motor drive system, there is a risk that the electrolytic capacitor will fail due to the influence of the ambient temperature, thereby causing the drive system to fail. Therefore, how to monitor the capacitance of the bus capacitor online is worthy of attention and is urgently needed. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the first purpose of the present invention is to propose a bus capacitor online identification method for a motor drive system, by applying an AC signal to a modulation signal of a PFC circuit in the process of controlling the operation of a PFC circuit to generate an AC voltage on the bus capacitor, then obtaining the bus voltage and bus current, and then determining the capacitance of the bus capacitor according to the bus voltage and bus current, thereby realizing the online identification of the bus capacitor capacitance in a simple manner, and the requirements for the identification environment are not high, so that the method has high robustness.

[0004] A second objective of the present invention is to provide a motor controller.

[0005] The third objective of the present invention is to provide an online identification device for bus capacitance of a motor drive system.

[0006] A fourth objective of the present invention is to provide an electrical device.

[0007] To achieve the above-mentioned purpose, an embodiment of the first aspect of the present invention proposes an online identification method for a bus capacitor of a motor drive system, wherein the motor drive system includes a PFC circuit, a bus capacitor and an inverter circuit connected in sequence, and the method includes: in the process of controlling the operation of the PFC circuit, applying an AC signal to a modulation signal of the PFC circuit to generate an AC voltage on the bus capacitor; obtaining the bus voltage and the bus current; and determining the capacitance of the bus capacitor according to the bus voltage and the bus current.

[0008] According to the method for online identification of the bus capacitance of the motor drive system of the embodiment of the present invention, an AC signal is applied to the modulation signal of the PFC circuit during the operation of the PFC circuit to generate an AC voltage on the bus capacitance, and then the bus voltage and the bus current are obtained, and the capacitance of the bus capacitance is determined according to the bus voltage and the bus current, thereby realizing online identification of the capacitance of the bus capacitance in a simple manner, and the requirements for the identification environment are not high, so that the method has high robustness.

[0009] According to an embodiment of the present invention, obtaining the bus current includes: obtaining the output current of the PFC circuit and the input current of the inverter circuit; and obtaining a first current difference between the output current and the input current to obtain the bus current.

[0010] According to one embodiment of the present invention, obtaining the input current of the inverter circuit includes: obtaining the phase current of the motor; performing coordinate transformation on the phase current to obtain the d-axis current and q-axis current of the motor; and calculating the input current based on the d-axis current and the q-axis current.

[0011] According to an embodiment of the present invention, calculating the input current based on the d-axis current and the q-axis current includes: taking the square root of the sum of the squares of the d-axis current and the q-axis current to obtain the input current.

[0012] According to one embodiment of the present invention, the method also includes: performing bandpass filtering on the output current, input current and bus voltage respectively; obtaining a first current difference between the output current and the input current after bandpass filtering to obtain the bus current after bandpass filtering; and determining the capacitance of the bus capacitor based on the bus voltage and bus current after bandpass filtering.

[0013] According to one embodiment of the present invention, in the process of controlling the operation of the PFC circuit, an AC signal is applied to a modulation signal of the PFC circuit to generate an AC voltage on a bus capacitor, including: obtaining a voltage difference between a reference bus voltage and the bus voltage; performing PI adjustment on the voltage difference to obtain a reference output current of the PFC circuit; obtaining a second current difference between the reference output current and the output current of the PFC circuit; performing PI adjustment on the second current difference to obtain a duty cycle of the PFC circuit; and generating a control signal of the PFC circuit based on the duty cycle, the modulation signal, the AC signal and the carrier signal to control the PFC circuit to generate an AC voltage on the bus capacitor.

[0014] According to an embodiment of the present invention, the AC signal is a sine wave signal, and the frequency of the AC signal is greater than the frequency of the modulation signal.

[0015] To achieve the above-mentioned purpose, the second aspect of the present invention proposes a motor controller, including: a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the online identification method of the bus capacitance of the motor drive system mentioned above is implemented.

[0016] The motor controller according to the embodiment of the present invention can realize online identification of the bus capacitance value in a simple and reliable manner through the aforementioned bus capacitance online identification method of the motor drive system, so that the motor controller can adjust the working state of the motor according to the bus capacitance value to ensure stable operation of the motor, thereby improving the reliability of the motor.

[0017] To achieve the above-mentioned purpose, the third aspect of the present invention proposes an online identification device for the bus capacitor of a motor drive system. The motor drive system includes a PFC circuit, a bus capacitor and an inverter circuit connected in sequence. The device includes: a control module, which is used to apply an AC signal to the modulation signal of the PFC circuit in the process of controlling the operation of the PFC circuit to generate an AC voltage on the bus capacitor; an acquisition module, which is used to obtain the bus voltage and the bus current; and an identification module, which is used to determine the capacitance of the bus capacitor according to the bus voltage and the bus current.

[0018] According to the bus capacitor online identification device of the motor drive system of the embodiment of the present invention, an AC signal is applied to the modulation signal of the PFC circuit while controlling the operation of the PFC circuit through the control module to generate an AC voltage on the bus capacitor, and then the bus voltage and bus current are obtained through the acquisition module, and the capacitance of the bus capacitor is determined according to the bus voltage and the bus current through the identification module, thereby realizing the online identification of the bus capacitor capacitance in a simple manner, and the requirements for the identification environment are not high, so that the device has high robustness.

[0019] To achieve the above-mentioned purpose, a fourth aspect of the present invention provides an electrical device, including the aforementioned motor controller, or the aforementioned bus capacitance online identification device of the motor drive system.

[0020] According to the electrical equipment of the embodiment of the present invention, through the aforementioned motor controller or the aforementioned bus capacitance online identification device of the motor drive system, the online identification of the bus capacitance value can be realized in a simple and reliable manner, so that the electrical equipment can adjust its own working state according to the bus capacitance value, ensure the stable operation of the electrical equipment, and then improve the reliability of the electrical equipment.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1is a schematic structural diagram of a motor drive system according to an embodiment of the present invention;

[0023] Figure 2 is a flow chart of a method for online identification of bus capacitance of a motor drive system according to an embodiment of the present invention;

[0024] Figure 3 A control block diagram of a method for applying an AC signal to a modulation signal according to an embodiment of the present invention;

[0025] Figure 4 A control block diagram of a bus capacitance online identification method of a motor drive system according to an embodiment of the present invention;

[0026] Figure 5 is a schematic structural diagram of a motor controller according to an embodiment of the present invention;

[0027] Figure 6 It is a structural schematic diagram of a busbar capacitance online identification device according to an embodiment of the present invention;

[0028] Figure 7a-7b FIG. 1 is a schematic diagram of the structure of an electrical device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0030] The following describes, with reference to the accompanying drawings, an online bus capacitance identification method and identification device, a motor controller, and electrical equipment of a motor drive system provided in an embodiment of the present invention.

[0031] It should be noted that the bus capacitor online identification method of the embodiment of the present invention can be applied to a motor drive system including a PFC circuit, a bus capacitor and an inverter circuit. Figure 1 The schematic diagram of the motor drive system shown in Figure 1 is for reference. Figure 1As shown, the motor drive system 100 includes a PFC circuit 110, a bus capacitor C and an inverter circuit 120 connected in sequence, wherein the PFC circuit 110 can be connected to the grid-side power supply Ug through the rectifier circuit 130, and the output end of the inverter circuit 120 can be connected to the motor M. The PFC circuit 110 may include a first switch tube Q1, a first inductor L1 and a first diode D1, wherein one end of the first inductor L1 is connected to the first output end of the rectifier circuit 130, and the other end of the first inductor L1 is respectively connected to the anode of the first diode D1 and the first end of the first switch tube Q1; the cathode of the first diode D1 is respectively connected to one end of the bus capacitor C and the first input end of the inverter circuit 120; the second end of the first switch tube Q1 is respectively connected to the second output end of the rectifier circuit 130 and the other end of the bus capacitor C, and the other end of the bus capacitor C is also connected to the second input end of the inverter circuit 120.

[0032] Specifically, refer to Figure 1 As shown, the input end of the rectifier circuit 130 is connected to the grid-side power supply Ug. The rectifier circuit 130 can be a full-wave rectifier circuit composed of four diodes (D2-D5) to rectify the AC input from the grid-side power supply Ug into DC, which is input into the inverter circuit 120 through the PFC circuit 110. The inverter circuit 120 can be a full-bridge controlled rectifier circuit composed of six controllable switch tubes (S1-S6) to invert the DC into three-phase AC to drive the three-phase motor M to operate, wherein the motor can also be a compressor, etc., which is not limited here. In the above current conversion process, the PFC function can be realized by controlling the on and off of the first switch tube Q1 in the PFC circuit 110 to improve the power factor of the motor drive system 100. The specific principles of the rectifier circuit 130, the PFC circuit 110 and the inverter circuit 120 are not expanded here.

[0033] Figure 2 FIG. 1 is a flowchart of a method for online identification of bus capacitance of a motor drive system according to an embodiment of the present invention. Figure 2 As shown, the method includes:

[0034] S11, in the process of controlling the operation of the PFC circuit, applying an AC signal to a modulation signal of the PFC circuit to generate an AC voltage on the bus capacitor.

[0035] Specifically, when the PFC function of the PFC circuit needs to be turned on, the motor drive system needs to generate a modulation signal according to the duty cycle, and generate a PWM square wave as a control signal according to the modulation signal and the carrier signal to control the on and off of the first switch tube in the PFC circuit to achieve the PFC function, wherein the modulation signal is usually a sine wave, and the carrier signal is usually a triangle wave. The specific generation principle of the PWM square wave is not described here. In the process of generating the modulation signal, an AC signal can be injected into the modulation signal to generate an AC voltage on the bus capacitor. At this time, the capacitance of the bus capacitor can be determined by observing the AC voltage and bus current on the bus capacitor, thereby realizing the detection function of the bus capacitor.

[0036] In some embodiments, in the process of controlling the operation of the PFC circuit, an AC signal is applied to a modulation signal of the PFC circuit to generate an AC voltage on a bus capacitor, including: obtaining a voltage difference between a reference bus voltage and the bus voltage; performing PI adjustment on the voltage difference to obtain a reference output current of the PFC circuit; obtaining a second current difference between the reference output current and the output current of the PFC circuit; performing PI adjustment on the second current difference to obtain a duty cycle of the PFC circuit; and generating a control signal of the PFC circuit based on the duty cycle, the modulation signal, the AC signal and the carrier signal to control the PFC circuit to generate an AC voltage on the bus capacitor.

[0037] Specifically, PI regulation refers to a proportional-integral regulation method. Using the PI regulation method to obtain the duty cycle of the PFC circuit can enable the PFC circuit to obtain a higher response speed and steady-state performance. The specific principle of PI regulation is not expanded here. The reference bus voltage refers to the target voltage on the bus capacitor when the PFC circuit is running. The embodiment of the present invention can achieve closed-loop control of the voltage loop and current loop of the PFC circuit through PI regulation, thereby realizing the PFC function. The specific method is as follows: Reference Figure 3 As shown, the difference between the reference bus voltage Udcref and the bus power supply Udc can be obtained, and the voltage difference can be PI-regulated to obtain the reference output current Igref of the PFC circuit; then, the second current difference between the reference output current Igref and the real-time output current Ig of the PFC circuit is obtained, and the second current difference can be PI-regulated to obtain the duty cycle of the PFC circuit; finally, a modulation signal can be generated according to the obtained duty cycle, and then a control signal can be generated by the modulation signal and the carrier signal to control the on and off of the first switch tube, thereby realizing the PFC function.

[0038] At the same time, in the above-mentioned PWM control signal generation process, after the modulation signal is generated according to the obtained duty cycle, an AC signal can be applied to the modulation signal to superimpose the two signals, and a control signal is generated based on the superimposed modulation signal and carrier signal. When the control signal at this time is used to control the first switch tube, the function of generating an AC voltage on the bus capacitor can be realized.

[0039] Furthermore, the AC signal is a sinusoidal wave signal, and the frequency of the AC signal is greater than the frequency of the modulation signal.

[0040] Specifically, setting the AC signal to a sine wave signal can effectively reduce the harmonics generated by the PFC circuit on the AC side and improve the harmonic performance of the motor drive system. At the same time, the frequency of the AC signal can be set to be greater than the modulation signal frequency. For example, if the operating frequency of the mains is 50HZ, the frequency of the AC signal can be set to 300HZ~500HZ, thereby reducing the interference of the AC signal on the PFC circuit, so that the online identification of the bus capacitor will not affect the normal operation of the motor drive system.

[0041] S12, obtaining bus voltage and bus current.

[0042] Specifically, from the characteristics of the capacitor, it can be seen that after obtaining the bus current and bus voltage on the bus capacitor, the capacitance of the bus capacitor can be calculated. Therefore, when an AC voltage is generated on the bus capacitor, the bus voltage and bus current containing the AC component can be obtained to complete the identification of the capacitance of the bus capacitor.

[0043] In some embodiments, obtaining the bus current includes: obtaining an output current of the PFC circuit and an input current of the inverter circuit; and obtaining a first current difference between the output current and the input current to obtain the bus current.

[0044] Furthermore, the input current of the inverter circuit is obtained, including: obtaining the phase current of the motor; performing coordinate transformation on the phase current to obtain the d-axis current and q-axis current of the motor; and calculating the input current based on the d-axis current and the q-axis current.

[0045] Further, the input current is calculated based on the d-axis current and the q-axis current, including: taking the square root of the sum of the squares of the d-axis current and the q-axis current to obtain the input current.

[0046] Specifically, refer to Figure 1 As shown, according to Kirchhoff's law, the output current of the PFC circuit is equal to the sum of the input current of the inverter circuit and the bus current. Therefore, the output current of the PFC circuit and the input current of the inverter circuit can be obtained, and then the first current difference between the output current and the input current can be obtained to obtain the bus current, wherein the output current of the PFC circuit can be obtained by real-time detection. At the same time, refer to Figure 1As shown, the input current of the inverter circuit has been inverted into the three-phase current of the motor, so the real-time detection method cannot obtain the accurate input current value. At this time, the input current can be obtained by obtaining the three-phase current modulus value, that is, first obtain the phase current of the motor, and perform dq axis decomposition on the phase current to obtain the d-axis current and q-axis current of the motor, and then obtain the input current of the inverter circuit through the following formula (1):

[0047]

[0048] Among them, In is the input current of the inverter circuit, Id is the d-axis current of the motor, and Iq is the q-axis current of the motor.

[0049] S13, determining the capacitance of the bus capacitor according to the bus voltage and the bus current.

[0050] Specifically, the busbar capacitance value can be determined according to the following formula (2):

[0051] Idc=C*(dUdc / dt) (2)

[0052] Where Idc is the bus current, C is the bus capacitor value, and Udc is the bus voltage. After obtaining the bus voltage and bus current, the bus voltage can be derived, and then the bus capacitor value at the current moment can be obtained according to the above formula (2). In this way, the online identification function of the bus capacitor is realized.

[0053] In the motor drive system of the related art, due to the lack of online identification function of the bus capacitor, during the operation of the system, it is easy for the bus capacitor to fail due to excessive drop in capacitance, which in turn leads to the problem of drive system operation failure. In the embodiment of the present invention, by injecting an AC signal into the PFC circuit during the operation of the PFC circuit, an AC voltage is generated on the bus capacitor, and the bus current and bus voltage are obtained by real-time detection and calculation, and finally the real-time bus capacitor capacitance is obtained according to the bus current and bus voltage, thereby realizing the online identification of the bus capacitor. At this time, the motor drive system can adjust the power range of the motor operation in real time based on the bus capacitor capacitance, thereby ensuring that the motor drive system can operate stably, thereby effectively improving the reliability of the motor drive system. In addition, the capacitance value identification method of the embodiment of the present invention is relatively simple to implement, and has low requirements on the identification environment, and has high robustness.

[0054] In some embodiments, the method also includes: performing bandpass filtering on the output current, input current and bus voltage respectively; obtaining a first current difference between the output current and the input current after bandpass filtering to obtain the bus current after bandpass filtering; and determining the capacitance of the bus capacitor based on the bus voltage and bus current after bandpass filtering.

[0055] Specifically, refer to Figure 4 As shown, when determining the bus current, when obtaining the output current and the input current, firstly perform bandpass filtering and then calculate the first current difference to obtain the bus current Icap after bandpass filtering. The bus current obtained in this way can filter out harmonics, thereby achieving higher accuracy. In addition, when obtaining the bus voltage by real-time detection, the obtained bus voltage can also be bandpass filtered and then subsequently calculated to determine the bus capacitance value. The advantage of the embodiment of the present invention is that by performing bandpass filtering on the obtained output current, input current and bus voltage, the capacitance value of the determined bus capacitance is more accurate, thereby improving the accuracy of the method.

[0056] In summary, according to the method for online identification of the bus capacitance of the motor drive system of an embodiment of the present invention, during the operation of the PFC circuit, an AC signal is applied to the modulation signal of the PFC circuit to generate an AC voltage on the bus capacitance, and then the bus voltage and the bus current are obtained, and the capacitance of the bus capacitance is determined according to the bus voltage and the bus current, thereby realizing online identification of the capacitance of the bus capacitance in a simple and reliable manner, and effectively improving the convenience and robustness of the method.

[0057] Corresponding to the above embodiment, the embodiment of the present invention further provides a motor controller, referring to Figure 5 As shown, the motor controller 200 includes: a memory 210, a processor 220, and a program stored in the memory 210 and executable on the processor 220. When the processor 220 executes the program, the above-mentioned bus capacitance online identification method of the motor drive system is implemented.

[0058] The motor controller according to the embodiment of the present invention can realize online identification of the bus capacitance value in a simple and reliable manner through the aforementioned bus capacitance online identification method of the motor drive system, so that the motor controller can adjust the working state of the motor according to the bus capacitance value to ensure stable operation of the motor, thereby improving the reliability of the motor.

[0059] Corresponding to the above embodiment, the embodiment of the present invention further provides a bus capacitance online identification device for a motor drive system, referring to Figure 1 As shown, the motor drive system 100 includes a PFC circuit 110, a bus capacitor C and an inverter circuit 120 connected in sequence, referring to Figure 6 As shown, the device 300 includes: a control module 310 , an acquisition module 320 and an identification module 330 .

[0060] Among them, the control module 310 is used to apply an AC signal to the modulation signal of the PFC circuit 110 in the process of controlling the operation of the PFC circuit 110 to generate an AC voltage on the bus capacitor C; the acquisition module 320 is used to obtain the bus voltage and the bus current; and the identification module 330 is used to determine the capacitance of the bus capacitor C according to the bus voltage and the bus current.

[0061] According to an embodiment of the present invention, the acquisition module 320 is further used to: acquire the output current of the PFC circuit 110 and the input current of the inverter circuit 120; acquire a first current difference between the output current and the input current to obtain the bus current.

[0062] According to an embodiment of the present invention, the acquisition module 320 is further used to: acquire the phase current of the motor; perform coordinate transformation on the phase current to obtain the d-axis current and q-axis current of the motor; and calculate the input current based on the d-axis current and the q-axis current.

[0063] According to an embodiment of the present invention, the acquisition module 320 is further configured to: obtain the input current by taking the square root of the sum of the squares of the d-axis current and the q-axis current.

[0064] According to one embodiment of the present invention, the device 300 also includes: a filtering module, which is used to perform bandpass filtering on the output current, the input current and the bus voltage respectively; the acquisition module 320 is also used to obtain the first current difference between the output current and the input current after the bandpass filtering process, and obtain the bus current after the bandpass filtering process; the identification module 330 is also used to determine the capacitance of the bus capacitor based on the bus voltage and the bus current after the bandpass filtering process.

[0065] According to one embodiment of the present invention, the control module 310 is further used to: obtain a voltage difference between a reference bus voltage and a bus voltage; perform PI regulation on the voltage difference to obtain a reference output current of the PFC circuit 110; obtain a second current difference between the reference output current and the output current of the PFC circuit; perform PI regulation on the second current difference to obtain a duty cycle of the PFC circuit 110; and generate a control signal of the PFC circuit based on the duty cycle, the modulation signal, the AC signal and the carrier signal to control the PFC circuit 110 so as to generate an AC voltage on the bus capacitor.

[0066] According to an embodiment of the present invention, the AC signal is a sine wave signal, and the frequency of the AC signal is greater than the frequency of the modulation signal.

[0067] It should be noted that for the relevant description of the online identification device for the bus capacitance of the motor drive system in the present application, please refer to the aforementioned relevant description of the online identification method for the bus capacitance of the motor drive system, which will not be repeated here.

[0068] According to the bus capacitance online identification device of the motor drive system of the embodiment of the present invention, an AC signal is applied to the modulation signal of the PFC circuit simultaneously during the process of controlling the operation of the PFC circuit through the control module to generate an AC voltage on the bus capacitor, and then the bus voltage and the bus current are acquired through the acquisition module, and then the capacitance of the bus capacitor is determined according to the bus voltage and the bus current through the identification module, thereby realizing the online identification of the capacitance of the bus capacitor in a simple and reliable manner, and effectively improving the convenience and robustness of the method.

[0069] Corresponding to the above embodiment, the embodiment of the present invention further provides an electrical device, referring to Figure 7a-7b As shown, the electrical device 1000 includes the aforementioned motor controller 200, or the aforementioned bus capacitance online identification device 300 of the motor drive system.

[0070] According to the electrical equipment of the embodiment of the present invention, through the aforementioned motor controller or the aforementioned bus capacitance online identification device of the motor drive system, the online identification of the bus capacitance value can be realized in a simple and reliable manner, so that the electrical equipment can adjust its own working state according to the bus capacitance value, ensure the stable operation of the electrical equipment, and then improve the reliability of the electrical equipment.

[0071] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0072] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0073] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0074] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0075] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for online identification of bus capacitance of a motor drive system. It is characterized in that The motor drive system includes a PFC circuit, a bus capacitor and an inverter circuit connected in sequence, and the method includes: In the process of controlling the operation of the PFC circuit, applying an AC signal to a modulation signal of the PFC circuit to generate an AC voltage on the bus capacitor; Obtain bus voltage and bus current; The capacitance of the bus capacitor is determined according to the bus voltage and the bus current.

2. The method according to claim 1, It is characterized in that Obtaining the bus current includes: Obtaining an output current of the PFC circuit and an input current of the inverter circuit; A first current difference between the output current and the input current is acquired to obtain the bus current.

3. The method according to claim 2, It is characterized in that Obtaining the input current of the inverter circuit, comprising: Get the phase current of the motor; Performing coordinate transformation on the phase current to obtain a d-axis current and a q-axis current of the motor; The input current is calculated based on the d-axis current and the q-axis current.

4. The method according to claim 3, It is characterized in that The calculating the input current based on the d-axis current and the q-axis current includes: The input current is obtained by taking the square root of the sum of the squares of the d-axis current and the q-axis current.

5. The method according to any one of claims 2 to 4, It is characterized in that The method further comprises: performing band-pass filtering on the output current, the input current and the bus voltage respectively; Obtaining a first current difference between the output current after bandpass filtering and the input current to obtain a bus current after bandpass filtering; The capacitance of the bus capacitor is determined according to the bus voltage and bus current after bandpass filtering.

6. The method according to claim 1, It is characterized in that In the process of controlling the operation of the PFC circuit, applying an AC signal to the modulation signal of the PFC circuit to generate an AC voltage on the bus capacitor includes: Obtaining a voltage difference between a reference bus voltage and the bus voltage; Performing PI regulation on the voltage difference to obtain a reference output current of the PFC circuit; Acquire a second current difference between the reference output current and the output current of the PFC circuit; Performing PI regulation on the second current difference to obtain a duty cycle of the PFC circuit; Based on the duty cycle, the modulation signal, the AC signal and the carrier signal, a control signal of the PFC circuit is generated to control the PFC circuit so as to generate an AC voltage on the bus capacitor.

7. The method according to claim 1 or 6, It is characterized in that The AC signal is a sine wave signal, and the frequency of the AC signal is greater than the frequency of the modulation signal.

8. A motor controller, It is characterized in that include: A memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the method for online identification of bus capacitance of a motor drive system according to any one of claims 1 to 7 is implemented.

9. An online identification device for busbar capacitance of a motor drive system, It is characterized in that The motor drive system includes a PFC circuit, a bus capacitor and an inverter circuit connected in sequence, and the device includes: A control module, used for applying an AC signal to a modulation signal of the PFC circuit to generate an AC voltage on the bus capacitor during the process of controlling the operation of the PFC circuit; An acquisition module, used for acquiring bus voltage and bus current; An identification module is used to determine the capacitance of the bus capacitor according to the bus voltage and the bus current.

10. An electrical device, It is characterized in that It comprises the motor controller according to claim 8, or the bus capacitance online identification device of the motor drive system according to claim 9.

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