Control device for power supply harmonic waves of alternating current motor driven by multiple inverters

Abstract

To provide a control device for power supply harmonic waves of an alternating current motor driven by multiple inverters.SOLUTION: A control device comprises a main driver, a signal processor and at least one active filter; the signal processor comprises a signal acquisition unit, a filtering unit, a control unit and a modulation unit; the signal acquisition unit is used for acquiring a current signal; the filtering unit is used for filtering out interference signals in the current signals and acquiring waveforms of the current signals or generating feedback signals according to the current signals; the control unit carries out data processing on waveforms of the current signals before and after the current signals are input into the filtering unit, fundamental current frequency and phase of the current signals are obtained, and a given value required by target harmonic waves is determined according to adjustment requirements of the target harmonic waves; the modulation unit is used for outputting a voltage switching signal to the active filter.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to the field of power electronics current conversion, and more particularly to a harmonic control device for power supply of a multi-inverter-driven AC motor.

Background Art

[0002] As industrial electrification continues to progress, more motors that meet high-performance control requirements such as higher power and higher frequencies are needed. Under such circumstances, the power capacity of conventional inverters and the conventional single-inverter drive method are increasingly reaching their limits.

[0003] In motors that require high-performance current control, for example, when a high current content, a high current frequency, or a low carrier ratio due to high-performance control is required, the inverter is required to have high hardware requirements.

[0004] Taking a high-speed motor as an example, due to its high-frequency current characteristics, a high-speed motor needs to be controlled by a high-frequency switchable device. Under the circumstances of conventional single-inverter drive control, this causes a very large voltage modulation pressure on the inverter. On the other hand, in a large-power traction drive system such as a compressor or a turbine system, the maximum switching frequency of the inverter is not only affected by the switching frequency of the power electronics device, but is usually also limited by factors such as heat dissipation conditions and cannot increase with the rotational speed of the motor. Under such circumstances, as the rotational speed of the motor continues to increase, the angular frequency of the motor gradually approaches the switching frequency of the inverter power device, and the waveform of the control voltage output from the inverter is modulated to have a low carrier ratio. Therefore, a large amount of low-order harmonics are included in the armature winding current of the motor.

[0005] In the related art, the mainstream improvement direction is basically an improvement based on a single inverter. Such improvements include attaching a passive filtering device to the three-phase bus of the motor, designing an inverter using multilevel technology, or replacing devices in the inverter with those having a higher turn-off speed and better heat dissipation performance.

[0006] However, in the above solutions, the filtering effect is not sufficiently obvious, and only the harmonic current in the system can be suppressed to a certain extent. Or, it is necessary to use more power electronics devices, which have high reliability requirements, high costs, and are difficult to operate and maintain. Currently, there is still no harmonic customization mode that can achieve both low cost and excellent filtering effect.

Summary of the Invention

Problems to be Solved by the Invention

[0007] In order to solve the drawbacks of the prior art, an object of the present invention is to provide a harmonic control device for the power supply of a multi-inverter-driven AC motor that has a low hardware cost and an excellent filtering effect.

Means for Solving the Problems

[0008] This application is a harmonic control device for the power supply of a multi-inverter-driven AC motor, and the control device includes: A main driver for supplying a power current to drive the motor to operate, which is connected in parallel to the AC bus and electrically connected to the motor via the AC bus; At least one active filter, the active filter is connected in parallel to the AC bus, and an armature current for driving the motor is formed by both the active filter and the main driver. The active filter is for outputting a harmonic customization current so that the harmonic content in the armature current of the motor is adjusted and the armature current of the motor is improved to a desired waveform. including a signal processor The signal processor a signal collection unit for acquiring a current signal including at least the power current of the main driver, the harmonic customization current of the active filter, and the armature current for driving the motor a filtering unit for filtering out interference signals in the current signal, acquiring the waveform of the current signal, or generating a feedback signal for controlling the active filter according to the current signal a control unit for performing data processing on the waveforms of the current signal before and after input to the filtering unit to obtain the frequency and phase of the fundamental wave current of the current signal, and determining a given value required for the target harmonic according to the adjustment needs of the target harmonic, outputting the given value to the active filter, and controlling the active filter to execute corresponding current control according to the given value and the feedback signal including a modulation unit for modulating the pulse width of the voltage switching signal output to the active filter according to the output result of the current control A control device is provided, characterized in that

[0009] Furthermore, the active filter includes at least one current controller, and the active filter controls the harmonic customization current of the corresponding order through the current controller. The current controller is for compensating for the reactive or harmful current harmonics output from the main driver or injecting effective current harmonics that the main driver cannot output

[0010] Furthermore, the current controller is a proportional resonance controller, and the current controller can be optimized as a second-order band-pass filter. According to the frequency of the target harmonic, the passband of the second-order band-pass filter is determined, and the open-loop transfer function of the current controller satisfies the following relational expression JPEG2025077946000002.jpg10170Here, K ikrepresents the resonance coefficient of the current controller for the k-th harmonic, and K pk represents the proportional coefficient of the current controller for the k-th harmonic, and ω e represents the angular frequency of the fundamental current.

[0011] Furthermore, when zero-pole cancellation is satisfied, the closed-loop transfer function of the current controller can be optimized as a second-order band-pass filter. According to the transfer function of the second-order band-pass filter, it is guaranteed that the frequency of the target harmonic falls within the passband of the second-order band-pass filter. The transfer function of the second-order band-pass filter satisfies the following relational expression: JPEG2025077946000003.jpg10170JPEG2025077946000004.jpg5170 is the given value of the k-th harmonic current applied to the current controller, and L is the inductance value of the three-phase inductance in the active filter controlled by the current controller.

[0012] Furthermore, when the active filter compensates for the corresponding harmonics through different current controllers, the different current controllers are mutually superimposed, and the passbands after zero-pole cancellation of each current controller do not overlap with each other. The mutual superposition of the current controllers satisfies the following relational expression: JPEG2025077946000005.jpg12170 Here, ω hn represents the frequency of the harmonic.

[0013] Furthermore, the bus voltage on the DC side of the active filter is greater than or equal to the bus voltage on the DC side of the main driver and less than or equal to twice the bus voltage on the DC side of the main driver.

[0014] Furthermore, different active filters have the same hardware connection topology.

[0015] Furthermore, the main driver includes a three-phase full-control bridge inverter. The DC side of the three-phase full-control bridge inverter is connected to a DC power supply. The AC side of the three-phase full-control bridge inverter is connected in parallel to an AC bus via a three-phase bus inductance. A large-capacity DC filtering capacitor is provided on the DC side of the three-phase full-control bridge inverter.

[0016] Furthermore, the control unit determines the waveform of the fundamental current of the current signal according to the difference in the waveforms of the current signals before and after input to the filtering unit. The control unit determines the frequency and phase of the fundamental current according to the waveform of the fundamental current. The control unit determines a given waveform according to the requirements of the target harmonics. Specifically, the control unit is for obtaining a first deviation value by differentiating the given waveform from the harmonic current in the power current of the main driver. The control unit obtains a second deviation value by differentiating the given waveform from the harmonic current in the armature current of the motor, and is also for determining a given value according to the sum of the first deviation value and the second deviation value.

[0017] Furthermore, the modulation unit modulates the output result of the current control by the SVPWM method to form a voltage PWM switching signal, and sends the PWM switching signal to the active filter.

Advantages of the Invention

[0018] The main driver of the control device is connected in parallel to at least one active filter. The armature current for driving the motor is formed by both the power current output from the main driver and the harmonic customization current output from the active filter. According to the given value determined by the signal processor, the target harmonics output from the active filter are adjusted, so as to realize the customization of the target harmonics, reduce the harmonic content in the current signal, or intentionally enhance the current harmonics of a specific order, having an excellent filtering effect and low cost.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0020] In order for those skilled in the art to better understand the aspects of the present invention, the technical aspects in the specific embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

[0021] In the description of the present application, it should be understood that terms such as "first" and "second" are used only for the purpose of description and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited by "first" or "second" may include at least one of the said features explicitly or implicitly.

[0022] The present application provides a harmonic control device 100 in the power supply of a multi-inverter-driven AC motor as shown in Figure 1. The control device 100 includes a main driver 11 and at least one active filter 12. The main driver 11 is connected in parallel to the AC bus 13, and the main driver 11 is connected to the motor 14 via the AC bus 13. Specifically, the main driver 11 is for supplying a driving current to drive the motor 14 to operate.

[0023] Among them, the aforementioned motor 14 is applied to the following application scenarios. As an example, in the case of the motor 14 having a high armature current, the switching frequency of the semiconductor device (for example, MOS switch) that controls the motor 14 is lowered, so that the motor 14 is likely to be in a modulation environment with a low carrier ratio during driving.

[0024] As another example, in the case of the motor 14 having a high current frequency, the current frequency is made close to the switching frequency of the semiconductor device, so that the motor 14 is likely to be in a modulation environment with a low carrier ratio during driving.

[0025] As yet another example, in the case of the motor 14 that satisfies high-performance control, in order to avoid the carrier ratio in the modulation environment from becoming insufficient when the precise control of the motor 14 is realized, a modulation environment with a high carrier ratio is required.

[0026] Exemplarily, the main driver 11 includes a three-phase full-control bridge inverter (hereinafter abbreviated as inverter). The DC side of the inverter of the main driver 11 is connected to a DC power supply, and the AC side of the inverter of the main driver 11 is connected in parallel to the AC bus 13 via a three-phase bus inductance (hereinafter abbreviated as inductance). Referring to FIG. 1, the inductance of the main driver 11 is denoted as L0 and has a resistance value of R0.

[0027] Optionally, according to actual needs, a large-capacity DC filtering capacitor can also be attached to the DC side of the inverter of the main driver 11.

[0028] Furthermore, the active filter 12 is connected in parallel to the AC bus 13, and armature current for driving the motor 14 is formed by both the active filter 12 and the main driver 11. Specifically, the active filter 12 is for outputting a customized harmonic current of a target order so that the harmonic content in the armature current is adjusted and the armature current is improved to a desired waveform.

[0029] It should be noted that since the active filter 12 is only responsible for improving the harmonic content in the armature current of the motor 14, the frequency of the current output from the active filter 12 is high, and for the main driver 11, the power of the active filter 12 is low. Specifically, the structure of the active filter 12 is substantially the same as that of the main driver 11, and the active filter 12 includes an inverter and an inductance having the same structure as those in the main driver 11. Referring to FIG. 1, the inductance of the active filter 12 is denoted as Ln, and the resistance value is Rn (n = 1, 2, 3...).

[0030] Since the active filter 12 hardware design is related to the parameter design of the algorithm, when there are multiple harmonics of the target order that need to be adjusted, a plurality of active filters 12 that handle different frequencies respectively are connected in parallel to the AC bus 13, and some of the active filters 12 may be made to have exactly the same hardware connection topology.

[0031] Exemplarily, referring to FIG. 1, the control device 100 includes active filter 1, active filter 2,..., active filter n. The active filter 1 customizes the reactive or harmful current harmonics output from the main driver 11 according to a given value required for the harmonics of the target order, and the active filter 2 injects the effective current harmonics that the main driver 11 cannot output according to a given value required for the harmonics of the target order. Thereby, the effect of customizing the current is realized. As a result, the harmonic content in the armature current is adjusted, and the armature current is improved to a desired waveform. The above configuration has low hardware requirements for power electronics devices and is easy to maintain.

[0032] To solve the problem of the DC-side voltage in the main driver 11 and the active filter 12, the voltage of the DC bus of the main driver 11 is selected according to the designed voltage level of the motor 14, while for the active filter 12, in order to ensure that current can be injected into the armature of the motor 14 at any time, it is required that the voltage of the DC bus of the active filter 12 is greater than or equal to the voltage of the DC bus of the main driver 11 and less than or equal to twice the voltage of the DC bus of the main driver 11.

[0033] As shown in FIG. 1, further, the control device 100 also includes a signal processor 15. The signal processor 15 is connected to the AC bus 13 via the motor 14, and the signal processor 15 is connected in parallel to the main driver 11 and the active filter 12 respectively. The signal processor 15 determines a given value required for the target harmonics according to the armature current of the motor 14 and the power current of the main driver 11, and can output the given value to the active filter 12 so that a harmonic customization current for adjusting the target harmonics is generated according to the given value by the active filter.

[0034] According to the above configuration, the harmonic current in the armature current can be effectively customized, and / or the effective current harmonics that cannot be output by the main driver 11 can be injected. When the switching frequency of the semiconductor device of the main driver 11 is low, by turning on the active filter 12, the harmonic content in the armature current can be significantly reduced, and the control device 100 is considered to be low-cost and highly reliable.

[0035] As shown in FIG. 2, in one implementation form, the signal processor 15 includes a signal collection unit 151, a filtering unit 152, a control unit 153, and a modulation unit 154.

[0036] Specifically, the signal collection unit 151 is for acquiring a current signal that at least includes the power current output from the main driver 11, the harmonic customization current output from the active filter 12, and the armature current of the drive motor 14. The signal collection unit 151 converts the power current i of the main driver 11 sabc and the armature current i mabc into the synchronous coordinate system to obtain the converted power current i of the main driver 11 sdq and the converted armature current i mdq and transmits the converted power current i of the main driver 11 sdq and the armature current i mdq to the filtering unit 152.

[0037] Furthermore, the filtering unit 152 is for filtering out the interference signal in the current signal and obtaining the waveform of the current signal. Optionally, the filtering unit 152 generates a feedback signal for controlling the active filter 12 according to the current signal. Here, the filtering unit 152 is a second-order filter.

[0038] In this embodiment, the control unit 153 performs data processing on the waveforms of the current signal before and after input to the filtering unit 152 to obtain the frequency and phase of the fundamental wave current of the current signal, and determines a given value required for the target harmonic according to the adjustment needs of the target harmonic.

[0039] Exemplarily, the control unit 153 determines the waveform of the fundamental wave current of the current signal according to the difference in the waveforms of the current signal before and after input to the filtering unit 152. The control unit 153 determines the frequency and phase of the fundamental wave current according to the waveform of the fundamental wave current, and determines a given waveform according to the needs of the target harmonic.

[0040] Furthermore, the control unit 153 differentiates the harmonic current in the given waveform and the power current i of the converted main driver 11 sabc to obtain a first deviation value Δi s and the control unit 153 also differentiates the harmonic current in the given waveform and the armature current i of the converted mdq to obtain a second deviation value Δi m and sums the first deviation value Δi s and the second deviation value Δi m to obtain a given value Δi required for the adjustment of the target harmonic.

[0041] More specifically, the control unit 153 acquires the output current of the active filter 12 via the signal acquisition unit 151, performs data processing on the output current of the active filter 12 and the given value Δi according to a preset tuning frequency, and limits the data processing result so that the corresponding harmonic customized current is output from the active filter 12.

[0042] Exemplarily, the control unit 153 acquires the output current i of the active filter 12 fabc and converts the output current i of the active filter 12 by coordinate transformation fabc into the synchronous coordinate system to obtain the harmonic customized current i in the synchronous coordinate system fdq and further the given value Δi and the harmonic customized current i in the synchronous coordinate system fdqA deviation value from that is obtained. The current controller incorporated in the active filter 12 performs data processing on the deviation value according to a preset tuning frequency, and after the data processing result is limited, it is input to the modulation unit 154. Here, the tuning frequency is the frequency of the target harmonic, and the frequency of the target harmonic can be obtained by detecting the electrical frequency of the motor 14 or the rotational frequency of the motor 14 and multiplying by the corresponding multiple.

[0043] Furthermore, the modulation unit 154 modulates the output result of the current control by the SVPWM method to form a voltage PWM switching signal, and sends the PWM switching signal to the active filter. Thereby, the output of the harmonic-customized current is realized.

[0044] In the related art, the direct reason for deteriorating the operation performance of the motor 14 is the hardware limitation of the main driver 11 and the excessive harmonic content in the armature current of the motor 14, and the fundamental reason is that the power electronics device of the main driver 11 cannot adapt to the large torque (large armature current) and high frequency (high electrical frequency) of the motor 14.

[0045] This application provides simulation experiment results as shown in FIG. 5. When the harmonics of the armature current of the motor 14 are reduced, the torque ripple of the motor 14 is reduced accordingly, the heat generation is reduced, the noise is reduced, which is more beneficial for the long-term efficient operation of the motor 14.

[0046] In the experiment, the high-load operation scenario of the motor 14 is simulated, and the three-phase six-state BLDC drive method is used. At this time, within one electrical cycle, the switching frequency of the power electronics device is the lowest and the carrier ratio is the lowest. The main inverter can achieve a compensation rate of more than 75% for the target harmonics by using the active filter 12 to compensate only the 5th and 7th harmonics under the worst condition where the carrier ratio is 1. The 5th harmonic is reduced from 20.3% to 4.43%, and the 7th harmonic is reduced from 15.8% to 4.39%.

[0047] In one embodiment, the active filter 12 includes at least one current controller, and the active filter 12 controls the harmonic current of the corresponding order through the current controller. The current controller is for compensating the reactive or harmful current harmonics output from the main driver 11 or injecting the effective current harmonics that the main driver 11 cannot output.

[0048] Exemplarily, if any of at least two active filters 12 can control the same harmonic pair, at least two active filters 12 are required because the harmonic current content to be adjusted may be too large or other special situations may occur, and each active filter 12 includes a current controller for the harmonic pair, so that any active filter 12 can achieve the control of the same harmonic pair.

[0049] Specifically, determine the order of the target harmonics and the number of active filters 12 that need to be used, allocate current controllers to each active filter 12, and confirm the chopping frequency used in the inverter of the active filter 12.

[0050] After the hardware construction is completed, complete the parameter design of the current controller. On the premise that the current controller can be optimized as a second-order band-pass filter, confirm the passband of the current controller according to the frequency of the target harmonics. The open-loop transfer function of the current controller satisfies the following relational expression: JPEG2025077946000006.jpg11170Here, K ik / K pk =R / L needs to be satisfied, where R and L represent the electrical resistance value and inductance value of the active filter 12 respectively, and K ik、 K pk are the resonance coefficient and proportional coefficient of the current controller for the k-th harmonic respectively, and ω erepresents the angular frequency of the fundamental current.

[0051] When the zero-pole cancellation condition is satisfied, the closed-loop transfer function of the current controller can be optimized as a second-order band-pass filter. According to the transfer function of the second-order band-pass filter, it is guaranteed that the frequency of the target harmonic falls within the passband of the second-order band-pass filter. The transfer function of the second-order band-pass filter satisfies the following relational expression: JPEG2025077946000007.jpg11170JPEG2025077946000008.jpg5170 is the given value of the k-th harmonic current applied to the current controller, and L is the inductance value of the three-phase inductance in the active filter controlled by the current controller.

[0052] As shown in FIG. 4, after the harmonic current controller for the k-th harmonic is designed according to the above formula, if different harmonic current customizations by the same active filter 12 are required, the current controllers can be superimposed according to the following formula, and the passbands after zero-pole cancellation of each current controller should not overlap with each other. JPEG2025077946000009.jpg12170Here, ω hn represents the frequency of the harmonic.

[0053] Exemplarily, according to the above technical solution, harmonic customization of the armature current can be realized, including an increase (injection) or decrease (compensation) in the content of the target harmonic current in the armature current. On the other hand, if the active filter 12 needs to switch between the above two different operating states, only the given value required for the adjustment of the target harmonic needs to be adjusted, and no hardware adjustment is required.

[0054] As can be seen from the above, the control effect of the target harmonic by the active filter 12 is determined only by a given value, and the injection and compensation can be realized by using the same active filter 12, and thus the same current controller. Therefore, it is only necessary to reasonably set the given value of the target harmonic to facilitate the maintenance and adjustment of the control device 100 by the operator.

[0055] As shown in FIG. 3, for example, when it is desired to compensate for harmonic current to remove harmonics in the armature current, after setting a given part to 0, if the difference is taken between the given 0 and the actual harmonic content of the harmonic detection part, in fact, it corresponds to injecting a reverse-phase compensation current of the same magnitude. The harmonics of the armature current are usually 6n±1 order harmonics such as 5, 7, 11, 13,... in the case of a three-phase Y connection, but become ±6n order harmonics in the synchronous coordinate system. Moreover, since the above proportional resonance controller can control positive and negative harmonic pairs simultaneously, in the compensation operation state, the transfer function of the control part should be synchronized with 6nω e and that is, the transfer function becomes as follows: When it is desired to inject harmonic current to intentionally increase harmonics of a specific order in the armature current, it is necessary to confirm the phase and amplitude of the target harmonic in the synchronous coordinate system and the phase and amplitude of the harmonic that is of the same frequency in the synchronous coordinate system but has a reverse phase, and generate it as a given waveform after synthesizing in the synchronous coordinate system. The control unit 153 is synchronized with the frequency of the harmonic pair of the target order, and since the remaining flow is the same, it will not be repeated here.

[0056] According to the above configuration, the harmonic current in the armature current of the motor 14 can be effectively customized. When the harmonics of the armature current are reduced, the torque ripple of the motor 14 will be reduced accordingly, the heat generation will be reduced, the noise will be reduced, which is more advantageous for the long-term efficient operation of the motor 14. Moreover, the power electronics device in the above configuration has a lower cost and is easier to maintain.

[0057] Exemplarily, the fundamental frequency is ω e and the frequency after the target harmonic is converted to the synchronous coordinate system is ω h and the current controller operates in the synchronous coordinate system and can simultaneously control harmonic pairs with frequencies of ±ω h in the synchronous coordinate system. Its transfer function is as follows, JPEG2025077946000011.jpg11170K ik / K pk When the constraint of = R / L is satisfied, the principle of zero-pole cancellation can be satisfied, and as an open-loop transfer function, it is optimized as follows, JPEG2025077946000012.jpg9170As a result, the closed-loop transfer function of the system is degenerate to be a single second-order band-pass filter. Here, R and L are the resistance value and inductance value of the three-phase inductance of the active filter, respectively.

[0058] When optimizing the design so that the requirements of the above constraints are satisfied, it is necessary to improve the control responsiveness of the target harmonics of the controller by keeping the frequency of the target harmonics in the synchronous coordinate system as close as possible to the center frequency of the band-pass filter, and it is also necessary to avoid including the frequency ranges where other harmonic pairs are located within the passband of the second-order band-pass filter.

[0059] Also, considering the band-pass characteristics of the optimized current controller, if multiple target harmonics need to be adjusted and their frequencies are close, multiple current controllers are incorporated into a single active filter 12, and K ik / K pkOn the premise that the optimization condition of =R / L is satisfied, when the designed passbands of each harmonic current controller are independent of each other, it may be attempted to superimpose the current controllers of different harmonic pairs on each other and perform their control simultaneously. Referring to Figure 4, the figure shows a current controller structure that simultaneously customizes current harmonics for a plurality of harmonic pairs in an active filter and injects harmonics of a specific frequency. Assuming that it is necessary to control harmonics with frequencies ω h1 , ω h2 , ω h3 ······ in total, the transfer function of the entire current controller after superposition is as follows, JPEG2025077946000013.jpg12170 Also, for the extraction of harmonic content, the use of a second-order filter is required, and the transfer function of the second-order filter satisfies the following relational expression, JPEG2025077946000014.jpg11170 Here, ω n is the natural frequency of the second-order filter, and ξ is the attenuation coefficient. If it is found that the attenuation effect is not good when the above second-order filter is used, it is conceivable to increase the attenuation coefficient or superimpose and use an additional second-order filter on the output side of the filtering unit 152. Since the current controller has good frequency characteristics, the requirements for the harmonic detector as shown in Figure 4 are not strict.

[0060] According to the above technical solution, it is possible to realize the customization of armature current harmonics, including an increase (injection) or decrease (compensation) in the content of the target harmonic current in the armature current. On the other hand, if the active filter 12 needs to switch between the above two different operating states, it is only necessary to adjust a given setting part in the flow shown in Figure 3, and no hardware adjustment is required. Moreover, it should be noted that the control effect of the target harmonics by the active filter 12 is only determined by a given value, and injection and compensation can be realized using the same active filter 12, and thus the same current controller. For this purpose, the given value of the target harmonics only needs to be set reasonably.

[0061] It should be understood that those skilled in the art can make improvements and modifications based on the above description, and all of these improvements and modifications should be included within the scope of protection defined by the appended claims of the present invention.

Claims

1. A control device for controlling harmonics in power supply to a multi-inverter driven AC motor, the control device comprising: a main driver for supplying a power current for driving and operating a motor, the main driver being connected in parallel to an AC bus and electrically connected to the motor via the AC bus; At least one active filter, the active filter being connected in parallel to the AC bus, and the active filter and the main driver together forming an armature current for driving the motor, the active filter being for outputting a harmonic customized current such that a harmonic content in the armature current of the motor is adjusted to improve the armature current of the motor to a desired waveform; a signal processor; The signal processor includes: a signal acquisition unit for acquiring a current signal including at least a power current of the main driver, a harmonic customization current of the active filter, and an armature current for driving the motor; a filtering unit for filtering out interference signals in the current signal, and obtaining a waveform of the current signal, or generating a feedback signal for controlling the active filter according to the current signal; A control unit for performing data processing on the waveform of the current signal before and after input to the filtering unit to obtain the frequency and phase of the fundamental current of the current signal, and determining a given value required for the target harmonic according to the regulation needs of the target harmonic, the control unit outputs the given value to the active filter, and controls the active filter to perform corresponding current control according to the given value and the feedback signal; a modulation unit for modulating a pulse width of a voltage switching signal output to the active filter according to an output result of the current control. A control device comprising:

2. 2. The control device according to claim 1, wherein the active filter includes at least one current controller, and the active filter controls a harmonic customized current of a corresponding order through the current controller, the current controller being for compensating for reactive or harmful current harmonics output from the main driver or for injecting useful current harmonics that the main driver cannot output.

3. The current controller is a proportional resonant controller, and the current controller can be optimized as a second-order band-pass filter, and the passband of the second-order band-pass filter is determined according to the frequency of the target harmonic, and the open-loop transfer function of the current controller satisfies the following relationship: Here, K ik represents the resonance coefficient of the current controller for the kth harmonic, and K pk represents the proportionality factor of the current controller for the kth harmonic, and ω e 3. The control device according to claim 2, wherein: represents the angular frequency of the fundamental current.

4. When zero pole cancellation is satisfied, the closed loop transfer function of the current controller can be optimized as a second order band pass filter, and the frequency of the target harmonic is guaranteed to be within the pass band of the second order band pass filter according to the transfer function of the second order band pass filter, and the transfer function of the second order band pass filter satisfies the following relationship:

4. The control device of claim 3, wherein k is the given value of k-th harmonic current provided to the current controller, and L is an inductance value of a three-phase inductance in the active filter controlled by the current controller.

5. When the active filter compensates for corresponding harmonics through different current controllers, the different current controllers are mutually overlapped, and the passbands of the current controllers after zero pole cancellation do not overlap each other, and the mutual overlap of the current controllers satisfies the following relationship: where i hn 5. The control device of claim 4, wherein: represents a frequency of a harmonic.

6. 2. The control device according to claim 1, wherein a bus voltage on the DC side of the active filter is equal to or higher than a bus voltage on the DC side of the main driver and is equal to or lower than twice the bus voltage on the DC side of the main driver.

7. The control device according to claim 1 , wherein the different active filters have matching hardware connection topologies.

8. 2. The control device according to claim 1, wherein the main driver includes a three-phase fully-controlled bridge inverter, a DC side of the three-phase fully-controlled bridge inverter is connected to a DC power source, an AC side of the three-phase fully-controlled bridge inverter is connected in parallel to the AC bus via a three-phase bus inductance, and a large-capacity DC filtering capacitor is provided on the DC side of the three-phase fully-controlled bridge inverter.

9. The control unit determines a waveform of the fundamental current of the current signal according to a difference between the waveforms of the current signal before and after input to the filtering unit; the control unit determines a frequency and a phase of the fundamental current according to the waveform of the fundamental current, and determines a given waveform according to the needs of the target harmonic; 2. The control device as claimed in claim 1, wherein the control unit is specifically for obtaining a first deviation value by subtracting the given waveform from a harmonic current in a power current of the main driver, and the control unit is also for obtaining a second deviation value by subtracting the given waveform from a harmonic current in an armature current of the motor, and determining the given value according to a sum of the first deviation value and the second deviation value.

10. 2. The control device as claimed in claim 1, wherein the modulation unit modulates the output result of the current control in an SVPWM manner to form a voltage PWM switching signal, and sends the PWM switching signal to the active filter.

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