Electromagnetic interference (EMI) mitigation in pulse width modulation (PWM) inverters using learning-based frequency modulated carriers

Abstract

A controller is provided for generating a carrier signal that controls a pulse width modulation (PWM) inverter that drives an electric actuator. The controller includes: an interface configured to connect to a sensitive device circuit via a sensor, where the sensitive device circuit includes a power system or an electric actuator, or a combination of a power system and an electric actuator, where the sensor is configured to measure an electromagnetic interference (EMI) spectrum; a memory configured to store a modulation band, measured electromagnetic interference (EMI) spectrum data for different frequency carriers, a desired EMI spectrum, and a learning-based carrier design program; a processor connected with the memory and configured to perform: generating a frequency modulated (FM) carrier signal by solving an optimization problem generated by a learned carrier design program with respect to a scan time for a predetermined frequency; and a PWM generator configured to generate a PWM signal based on the FM carrier signal.

Description

Technical Field

[0001] This invention relates to electromagnetic interference (EMI) mitigation in pulse width modulation (PWM) inverters, and more specifically to reshaping the EMI spectrum of PWM inverters by designing frequency modulation carriers using a learning method. Background Technology

[0002] Pulse-width modulation (PWM) inverters are widely used in modern motor drive systems due to their high efficiency and wide-range adjustable output frequency. However, the large dv / dt and di / dt of switching devices during their operation can cause serious electromagnetic interference (EMI) problems, such as violating EMC (electromagnetic compatibility) regulations, interfering with other nearby equipment, and even causing system malfunctions. With the development of high-power-density, high-voltage, and high-switching-frequency semiconductor devices such as wide-bandgap devices (WBG), the demand for and focus on EMI mitigation in power electronic devices is increasing in order to meet the rapidly growing markets of electric vehicles, electric aircraft, and renewable energy.

[0003] To reduce EMI levels in power electronic devices, the power electronics field has researched and validated various methods, including soft switching, EMI filters (both passive and active), and circuit layout design. All these techniques aim to reduce the time-domain amplitude of EMI, thus lowering the overall EMI spectrum level.

[0004] In recent years, frequency modulation (FM)-based methods have received considerable attention for mitigating the EMI spectrum levels of PWM inverters. PWM drive signals are typically generated by comparing a reference signal with the desired drive frequency to a periodic carrier signal, such as a sine or triangular wave. Studies have shown that the EMI spectrum of PWM inverters contains strong harmonic components of the carrier frequency, which contribute the majority of the frequency components exceeding EMC regulations. Therefore, modulating the carrier signal frequency to disperse harmonic energy over a wider frequency band is helpful. Although using an FM carrier signal does not reduce overall EMI energy, it has proven effective in mitigating harmonic peaks in the EMI spectrum to meet EMC regulatory requirements.

[0005] Based on this frequency modulation concept, many frequency modulation schemes have been proposed to reduce the EMI level of PWM inverters. For example, a randomized FM scheme has been proposed, which reduces the EMI spectrum level by randomizing the switching time so that the carrier harmonic energy can be dispersed within the corresponding frequency band. However, due to the random nature of the scheme, randomized carrier FM works well statistically, but is relatively difficult to implement in hardware. Recently, a sinusoidal frequency modulation scheme has been proposed, in which the frequency of the carrier signal varies in a sinusoidal pattern within a certain range. A more general frequency modulation method can be found in US Patent No. 11,258,357, which proposes an adaptive frequency modulation method for reducing the received carrier harmonic EMI while taking into account the EMI propagation characteristics. This adaptive frequency modulation method mainly targets the first harmonic on the order of hundreds of kHz, or only a small part of the conducted EMI band [150 kHz, 30 MHz]. Therefore, it is necessary to develop a controller and signal processor to reduce the EMI level of power electronic equipment across the entire EMI band [150 kHz, 30 MHz]. Summary of the Invention

[0006] This disclosure provides a novel controller and signal processor for generating a carrier signal used to control a pulse width modulation (PWM) inverter that drives an electric actuator.

[0007] Some embodiments of this disclosure are based on the understanding that learning-based methods can provide customized FM carrier signals for generating PWM drive signals, thereby achieving the desired EMI spectral envelope. Considering the EMI spectral data of a PWM inverter, or a type of PWM inverter operating under different periodic carrier signals at different frequencies, the carrier design problem is formulated as a constrained optimization problem, where the objective function is formed based on the desired EMI spectrum, and constraints are imposed on the weights of different frequency components such that the total EMI energy remains constant. Once the weights are determined, an FM carrier signal is designed whose frequency modulation time is proportional to the corresponding weight. The desired EMI spectrum is represented as a linear combination of the EMI spectra under different periodic carrier signals at different frequencies corresponding to the weights. Compared to other empirical frequency modulation carrier designs, our method is more customizable and optimized for different devices. Simulation and experimental results show that the desired spectral envelope can be achieved using the designed FM carrier.

[0008] According to some embodiments of this disclosure, a controller is provided for generating a carrier signal that controls a pulse-width modulation (PWM) inverter driving an electric actuator. The controller includes: an interface configured to connect via a sensor to sensitive device circuitry, wherein the sensitive device circuitry includes a power system or an electric actuator or a combination of a power system and an electric actuator, wherein the sensor is configured to measure an electromagnetic interference (EMI) spectrum; a memory configured to store a modulation band, measured EMI spectrum data of different frequency carriers, a desired EMI spectrum, and a learning-based carrier design program; a processor connected to the memory and configured to perform the following steps: generating a frequency modulation (FM) carrier signal by solving an optimization problem, wherein the optimization problem is generated by the learning-based carrier design program with respect to a scan time for a predetermined frequency; and a PWM generator configured to generate a PWM signal based on the FM carrier signal.

[0009] Furthermore, some embodiments of this disclosure are based on the understanding that a signal processor is provided for generating modulation parameters used by a pulse width modulation (PWM) modulator, which generates a carrier signal for controlling an inverter driving an electric actuator. The signal processor includes: an interface configured to connect to the PWM modulator and a sensor configured to measure an electromagnetic interference (EMI) spectrum; a memory configured to store a modulation band, measured EMI spectrum data of different frequency carriers, a desired EMI spectrum, and a learning-based carrier design program; and a processor connected to the memory and configured to perform the following steps: generating a frequency modulation (FM) carrier signal by solving an optimization problem, wherein the optimization problem is generated by the learning-based carrier design program with respect to a scan time for a predetermined frequency; and transmitting the generated FM carrier signal to a signal modulator configured to generate a PWM signal based on the generated FM carrier signal. Attached Figure Description

[0011] The embodiments of this disclosure will now be further described with reference to the accompanying drawings. The drawings are not drawn to scale, but rather focus on illustrating the principles of the embodiments of this disclosure.

[0012] Figure 1 A schematic diagram indicating a PWM inverter drive system according to some embodiments of the present disclosure is shown;

[0013] Figure 2 A schematic diagram is shown indicating a PWM inverter drive system using a learning-based frequency modulation carrier according to some embodiments of the present disclosure;

[0014] Figure 3 A flowchart of a learning-based frequency modulation carrier design method according to some embodiments of the present disclosure is shown;

[0015] Figure 4 An EMI spectrum data diagram of A obtained using periodic triangular wave carriers with different frequencies from 50 kHz to 150 kHz and a step size of 1 kHz, according to some embodiments of the present disclosure, is shown.

[0016] Figure 5 Different frequency modulation functions of carrier signals using different existing methods and learning-based design methods are shown according to some embodiments of the present disclosure;

[0017] Figure 6A The EMI spectra of various carrier signals, including periodic carrier signals, random FM carriers, linear FM carriers, adaptive FM carriers, and learning-based carriers using the proposed method, are shown according to some embodiments of this disclosure.

[0018] Figure 6B The EMI spectra of various carrier signals, including periodic carrier signals, random FM carriers, linear FM carriers, adaptive FM carriers, and learning-based carriers using the proposed method, are shown according to some embodiments of this disclosure.

[0019] Figure 6C The EMI spectra of various carrier signals, including periodic carrier signals, random FM carriers, linear FM carriers, adaptive FM carriers, and learning-based carriers using the proposed method, are shown according to some embodiments of this disclosure.

[0020] Figure 6D The EMI spectra of various carrier signals, including periodic carrier signals, random FM carriers, linear FM carriers, adaptive FM carriers, and learning-based carriers using the proposed method, are shown according to some embodiments of this disclosure.

[0021] Figure 6E The EMI spectra of various carrier signals, including periodic carrier signals, random FM carriers, linear FM carriers, adaptive FM carriers, and learning-based carriers using the proposed method, are shown according to some embodiments of this disclosure.

[0022] Figure 7A Example results are shown of minimizing the overall conducted EMI level using a learned carrier (#2) according to some embodiments of this disclosure;

[0023] Figure 7B Example results of minimizing EMI levels in different frequency bands according to EMC regulations are shown, based on some embodiments of this disclosure;

[0024] Figure 8 Example results of summarizing EMI levels across different frequency bands according to some embodiments of this disclosure are shown; and

[0025] Figure 9 A schematic diagram of an example configuration of a controller for generating carrier signals for controlling an inverter that drives an electric actuator, according to some embodiments of the present disclosure, is shown. Detailed Implementation

[0026] The following description provides exemplary embodiments only and is not intended to limit the scope, applicability, or configuration of this disclosure. Rather, the following description of exemplary embodiments will provide those skilled in the art with an illustration of the feasibility of implementing one or more exemplary embodiments. Various modifications to the function and arrangement of the elements may be considered without departing from the spirit and scope of the subject matter of this disclosure as set forth in the appended claims.

[0027] To provide a full understanding of the embodiments, specific details are set forth in the following description. However, it will be understood by those skilled in the art that embodiments may be practiced without relying on these specific details. For example, systems, processes, and other elements in the disclosed subject matter may be shown in block diagram form to avoid obscuring the embodiments with unnecessary details. In other instances, unnecessary details of well-known processes, structures, and techniques may not be shown to avoid obscuring the embodiments. Furthermore, the same reference numerals and labels in the views denote the same elements.

[0028] Additionally, a single embodiment can be described as a process shown in a flowchart, schematic diagram, data flow diagram, structural diagram, or block diagram. Although a flowchart can describe operations as a sequential process, many operations can be performed in parallel or simultaneously. Furthermore, the order of operations can be rearranged. A process can terminate after its operations are completed, but may include additional steps not discussed or included in the diagram. Moreover, not all operations in a process specifically described occur in all embodiments. A process can correspond to a method, function, program, subroutine, secondary program, etc. When a process corresponds to a function, the termination of that function can correspond to a function call or the return of the main function.

[0029] Furthermore, embodiments of the subject matter of this disclosure can be implemented, at least in part, manually or automatically. Manual or automatic implementation can be performed or at least assisted by using machines, hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented using software, firmware, middleware, or microcode, program code or code segments for performing the necessary tasks can be stored in a machine-readable medium. The processor can then perform the necessary tasks.

[0030] In a PWM inverter, the PWM control signal is generated by comparing a sinusoidal reference signal of the desired frequency with a high-frequency carrier signal (such as a sine wave or a triangular wave), thereby generating a series of rectangular pulses of varying widths to control the operation of the switching devices. Let... The reference signal frequency is also the desired output frequency of the inverter. In the following sections, we analyze different carrier signals from an EMI perspective, while ignoring other side effects such as total harmonic distortion, heat loss, and vibration.

[0031] Figure 1 A schematic diagram of a PWM inverter drive system 100 according to some embodiments of the present disclosure is shown. The PWM inverter drive system 100 includes a power / EMI sensitive device 110, a PWM inverter / EMI source 120, a controller 130, and a load 140. The controller 130 uses one or more sensors to acquire one or more sensor information of position, speed, and motor current, and uses this information to control the frequency of a modulation signal to a desired operating frequency 132. The modulation signal 132 is compared with a carrier signal 133a at a given carrier frequency 150 to generate a PWM signal (multiple signals) 134 for controlling the switching operation of the PWM inverter.

[0032] periodic carrier

[0033] In traditional PWM inverters, a high-frequency periodic carrier wave, such as a sine wave, triangular wave, or sawtooth wave, is used to generate the PWM signal. For simplicity, we will use a sine wave carrier signal as an example. Let... Let be the carrier frequency, and assume... A sinusoidal carrier signal can be represented as...

[0034] (1),

[0035] Where A is the amplitude. The phase of the sinusoidal carrier signal. This is the initial phase. Further Fourier analysis of the PWM inverter output reveals that it contains a large number of phases of order 1. The harmonic frequency components, among which and It is a non-negative integer.

[0036] Figure 2A schematic diagram of a PWM inverter drive system 100 using a learning-based frequency-modulated carrier wave according to some embodiments of the present disclosure is shown. The PWM inverter drive system 100 includes a power supply / EMI sensitive device 110, a PWM inverter / EMI source 120, a controller 130, and a load (sensitive device circuitry) 140. The controller 130 uses one or more sensors to acquire one or more sensor information for position, speed, and motor current, and uses this information to control the modulation signal frequency 132. EMI spectra 210 generated by the PWM inverter / EMI source 120 using carrier signals 133a of different frequencies within a carrier band 150b are used as a learning dataset for measurement. Considering EMI regulations for the EMI spectrum 220, a learning-based FM carrier design procedure (algorithm) 230 is executed to generate / design the frequency-modulated carrier signal 133b. The modulation signal 132 is compared with the frequency-modulated carrier signal 133b via a PWM generator 134 to generate a PWM signal. The PWM generator 134 is configured to control the switching operation of the PWM inverter using the generated PWM signal.

[0037] Figure 3 A flowchart of a learning-based frequency modulation carrier design procedure (method) according to some embodiments of this disclosure is shown. Taking into account the measured EMI spectrum A 210 and the EMI regulations (desired EMI spectrum shape) 220, a solver 231 included in the learning-based carrier design procedure 230 is used to solve an optimization problem, namely, minimizing the maximum EMI level across the entire conducted EMI band [150 kHz, 30 MHz] according to EMC regulation e, which defines the maximum permissible EMI level at different frequencies within the conducted frequency EMI range [150 kHz, 30 MHz] using unknown scan time weights at different frequencies. Then, in 232, the frequency is determined according to the EMI regulations and based on the solved weights and the total scan time T. Scan time (duration) Then, in 233, the scanning time is based on the frequency. Generate (compute) a frequency modulation (FM) carrier signal and output a frequency modulation carrier signal 133b for the PWM generator 134.

[0038] B. Random FM carrier

[0039] Random carrier frequency modulation (RCFM) has proven to be an effective method for dispersing harmonic energy in the frequency domain, thereby reducing EMI levels. Let... For frequency The duration of the scan This represents the total scan duration across all frequencies. Therefore, we have...

[0040]

[0041] in, The score is randomly drawn from [0, 1]. Due to its randomness, RCFM provides improved performance only statistically, not deterministically. Because the carrier frequency is randomly modulated, the performance of the PWM inverter may vary when different random modulations are used.

[0042] C. Linear FM carrier

[0043] Linear frequency modulation (LFM) distributes the scan time evenly within the frequency band.

[0044] (3).

[0045] Let the time-domain LFM carrier signal be

[0046] (4),

[0047] in, and Here, are the minimum and maximum sweep frequencies, respectively. u(t) is a sawtooth wave signal with an amplitude range of [-1, 1] and a period of T, which can be represented as...

[0048] (5),

[0049] in, It is a floor function that outputs the largest integer less than the input real number; and

[0050] (6).

[0051] Considering a constant total EMI energy, a wider scanning band generally results in a lower EMI level. However, in practice, frequency bands are subject to various limitations. The lowest carrier frequency... Typically limited by the total harmonic distortion (THD) of the output voltage. If the carrier frequency is too low, the output THD may become unacceptably high. Maximum carrier frequency. It is usually limited by the switching speed or switching losses of the device.

[0052] D. Adaptive FM carrier

[0053] The purpose of the aforementioned carrier design is to mitigate the EMI characteristics of PWM signals or EMI sources. In reality, EMI received by sensitive devices becomes distorted after propagation. The adaptive carrier signal design considers the propagation effects of EMI and pre-distorts the EMI source spectrum to ensure good compensation for the EMI spectrum received by sensitive devices. For adaptive FM carriers, discrete uniform frequency sampling is taken into account. When using a linear FM carrier, the frequency scan duration Adaptively determined, and correlated with the corresponding EMI spectrum. Inversely proportional. Frequency The scan duration can be expressed as

[0054] (7).

[0055] Then, the frequency is adaptively modulated according to the following formula:

[0056] (8),

[0057] Among them, time It is determined by formula (7).

[0058] In adaptive FM carrier, the scan time depends on the first harmonic, i.e. The amplitude, rather than higher-order harmonics, is considered. Furthermore, higher-order harmonics may overlap. For example, 120kHz could be a 20kHz sixth harmonic or a 30kHz fourth harmonic. To generalize the frequency modulation carrier method, we consider a learning-based approach for carrier design.

[0059] Learning-based PWM carrier design method (program)

[0060] As we can see from Part II, the performance of EMI mitigation using different FM carriers depends on the frequency modulation scheme. The scan time of each carrier frequency determines the contribution of the corresponding EMI spectrum to the overall EMI spectrum. The longer the scan time of a frequency, the greater the fractional weight of that frequency carrier in the EMI spectrum. Since different devices exhibit different EMI propagation characteristics, it is ideal to optimize the FM carrier so that the overall EMI spectrum can meet EMC regulations with maximum margin; in other words, to achieve the lowest possible EMI level within EMC constraints.

[0061] set up Let be a nonnegative matrix of the learning data, where Let be the i-th column, which represents the frequency of use. The EMI spectrum amplitude when a periodic carrier generates a PWM signal. Note that A varies depending on the device.

[0062] Figure 4 This diagram shows EMI spectrum data using periodic triangular wave carriers with frequencies ranging from 50 kHz to 150 kHz and a step size of 1 kHz for A. Each column represents the EMI spectrum using the corresponding frequency carrier, and different gray levels represent different amplitudes at dB scales, as shown by the gray scale bar on the right.

[0063] Similarly, frequency The scan duration can be expressed as

[0064] (9),

[0065] in, It is a weight vector The i-th element, with frequency The EMI spectrum is related to the carrier scan duration. Assuming the overall EMI spectrum is the superposition of EMI spectra using different single-frequency carriers, the expected EMI under the designed FM carrier can be expressed as...

[0066] (10).

[0067] EMC standards specify the EMI levels for electronic products. However, EMC regulations vary for different types of products and across different countries or regions. Our learning-based carrier algorithm offers some flexibility in EMI mitigation. Consider an EMC regulation where the maximum EMI level is constrained by a certain level. In this case, the weights of different frequencies can be determined by solving an optimization problem:

[0068] (11).

[0069] Once we obtain the weight w, we can directly obtain the sweep frequency as a function of time, i.e.

[0070] ,at this time, (12).

[0071] The carrier signal based on learning can be calculated as follows:

[0072] (13),

[0073] Wherein, phase is

[0074] (14).

[0075] In some cases, EMC standards specify different EMI levels based on different frequency bands. For example, , where e represents the upper limit of the EMI level. The objective function was subsequently modified according to EMC regulations.

[0076] (15),

[0077] Where e is a vector of the spectrum provided by EMC regulations. It is a diagonal matrix of elements with diagonal element e. This optimization problem can be solved directly using normalized convex programming like CVX. Through a learning-based carrier design method (procedure), the EMI spectrum can be reshaped to achieve a larger margin between the permissible EMI level and the actual EMI level according to EMC regulations.

[0078] Figure 5 Different frequency modulation functions for carrier signals using different existing methods and learning-based design approaches are illustrated according to some embodiments of this disclosure. For linear frequency modulation (FM), the modulation function is a straight line, indicating that the carrier frequency increases linearly from a minimum carrier frequency to a maximum carrier frequency over time during each scan duration. For random FM, the modulation function is an irregular curve, indicating that its carrier frequency increases randomly and gradually from a minimum carrier frequency to a maximum carrier frequency. For adaptive FM and learning-based FM, the frequency increases adaptively over time or follows a pattern learned from the measured EMI spectrum, thereby enabling the EMI spectrum to reach an ideal level.

[0079] Figures 6A to 6E The EMI spectra are shown using periodic carrier signals, random FM carriers, linear FM carriers, adaptive FM carriers, and a learning-based carrier using the proposed method. Figure 6A In the example diagram, we show a PWM spectrum diagram where we use = 200Hz and = 50kHz. We can observe that the EMI spectrum contains strong harmonics of the carrier frequency, especially the first harmonic.

[0080] For random FM carriers, adaptive FM carriers, and learning-based carriers, consider a scanning band of [50, 150] kHz. This is in contrast to the overall use of periodic triangular wave carriers (…). Figure 6A Compared to random carrier frequency modulation (RCC), Figure 6B This significantly reduces EMI levels by approximately 10 dB, but its suppression effect on first-order harmonic levels from 50 kHz to 150 kHz is poor. When using a linear frequency modulated carrier ( Figure 6C When using an adaptive FM carrier based on first harmonics, first-order harmonics and conducted EMI are further reduced by approximately 2.5 dB, but the reduction is not flat. Figure 6D When the first harmonic is reduced by approximately 2.3 dB, the maximum conducted EMI level increases simultaneously. For our objective of reducing the first harmonic, a learning-based carrier wave (#1) is used. Figure 6E The first harmonic level was reduced to a minimum of 68.78 dB, the lowest among different carriers.

[0081] Figure 7AExample results showing the minimization of overall conducted EMI levels using a learning-based carrier (#2) are presented. The overall EMI level is reduced to 76.8 dB, which is also the lowest level among different FM carriers.

[0082] Figure 7B Example results of minimizing EMI levels in different frequency bands according to EMC regulations are plotted, where the top dashed line represents the EMC regulations and the bottom dotted line represents the maximum level of a specific frequency band relative to the different conducted EMI bands of [10kHz, 1MHz] and [1MHz, 30MHz].

[0083] Figure 8 Example results summarizing EMI levels across different frequency bands are presented, where the frequency bands [50kHz, 150kHz] correspond to first harmonics and the frequency bands [10kHz-30MHz] correspond to conducted EMI.

[0084] Figure 9 An example configuration of a controller 900 for generating a carrier signal to control an inverter driving an electric actuator, according to some embodiments of the present disclosure, is illustrated. The controller 900 is configured to generate a PWM signal to control an inverter circuit 120 driving an electric actuator 140 (or motor). The controller 900 includes a carrier frequency modulation unit (circuit module) 133b and a PWM signal generator 134. The carrier frequency modulation unit 133b is configured to perform a process 910 including a step for generating a frequency-modulated carrier signal. The carrier frequency modulation unit 133b may include: an interface (interface controller) 920 configured to connect to a sensor 131 connected to the inverter circuit 120 to measure EMI spectrum data A 210 (measured electromagnetic interference (EMI) spectrum 210) using the sensor 131; a processor 910; and a storage unit 930 configured to store the measured EMI spectrum 210, the carrier frequency band 150b, and a desired EMI spectrum 220b according to EMC regulation 220, wherein the desired EMI spectrum 220b may be lower than the permissible EMI level according to EMC regulation 220 by a constant. The processor 910 is configured to perform calculation of a PWM reference signal. The carrier frequency modulation unit 940 is configured to calculate the scan time of each discrete frequency within each scan cycle according to 231 and using learned weights, and modulate the carrier frequency based on the scan time of each frequency. The controller 900 further includes a PWM signal generator 134 configured to generate a PWM signal based on the frequency-modulated carrier signal and the reference signal. The PWM signal generator 134 can transmit the PWM signal to the inverter circuit 120.

[0085] In some cases, the measured EMI spectrum 210 is obtained based on a linear frequency modulation (LFM) carrier, and frequency modulation can be performed by a periodic sawtooth wave signal. Furthermore, the modulation frequency can be performed as a function of EMC regulations. When a linear frequency modulation carrier signal is used to generate a PWM signal for the inverter circuit 120, the measured EMI spectrum 210 can be obtained from the frequency response of the sensitive device circuit using a LISN.

[0086] In another embodiment, processor 910 may be a signal processor 910 configured to generate modulation parameters used by a PWM signal generator 134 that generates a PWM signal controlling an inverter circuit 120 driving an electric actuator 140. Signal processor 910 is connected to interface 920 configured to connect to the PWM signal generator 134 and storage device 930 configured to store measured electromagnetic interference (EMI) spectrum 210 and desired EMI spectrum 220b. In this case, signal processor 910 is configured to calculate weights related to the duration of a scan frequency band, determined by EMC regulations for a sensitive device circuit 1000 comprising at least a power system 110 or at least an electric actuator 140 or a combination of power system 110 and electric actuator 140. Furthermore, signal processor 910 is also configured to calculate the scan time for each frequency in each scan cycle based on these weights. Signal processor 910 is configured to modulate the frequency of a carrier signal according to the sweep time of each frequency to generate a frequency-modulated carrier, and transmit the frequency-modulated carrier to PWM signal generator 134. Upon receiving the frequency-modulated carrier, PWM signal generator 134 generates a PWM signal based on the frequency-modulated carrier and a reference signal from signal processor 910, and transmits the PWM signal to inverter circuit 120, ensuring that the EMI level of sensitive device circuit 1000 complies with EMC regulations.

[0087] The above embodiments can be implemented in various ways. For example, these embodiments can be implemented using hardware, software, or a combination of both. When implemented in software, the software code can execute on any suitable processor or cluster of processors, whether provided on a single computer or distributed across multiple computers. These processors can be implemented as an integrated circuit along with one or more processors in an integrated circuit assembly. Of course, the processor can also be implemented using any suitable form of circuitry.

[0088] Furthermore, embodiments of the present invention can also be embodied as methods, an example of which has been provided above. The operations performed as part of a method can be ordered in any suitable manner. Therefore, embodiments can be constructed that perform operations in a different order than in the example, which may include performing certain operations simultaneously, even though they are shown as sequential in the example embodiment.

[0089] The use of ordinal numbers such as "first" and "second" to modify claim elements in the claims does not imply any priority, order of precedence or rank of one claim element relative to another, or any temporal order of the method operations. Rather, it serves only as a label to distinguish one claim element with a certain name from another claim element with the same name (excluding ordinal numbers).

[0090] Although the invention has been described by way of example of preferred embodiments, it should be understood that various other adaptations and modifications can be made within the concept and scope of the invention.

[0091] Therefore, the purpose of the appended claims is to cover all such variations and modifications that are consistent with the true concept and scope of the invention.

Claims

1. A controller for generating a carrier signal that controls a pulse width modulation inverter, i.e., a PWM inverter, that drives an electric actuator, wherein, The controller includes: An interface configured to connect to a sensitive device circuit via a sensor, wherein the sensitive device circuit includes a power system, or an electric actuator, or a combination of a power system and an electric actuator, wherein the sensor is configured to measure an electromagnetic interference spectrum, i.e., an EMI spectrum. The memory is configured to store the modulation frequency band, the measured electromagnetic interference spectrum (EMI spectrum), the desired EMI spectrum, and the learning-based carrier design program. A processor, connected to memory, configured to perform the following steps: generating a frequency-modulated carrier signal, i.e., an FM carrier signal, by solving an optimization problem, wherein the optimization problem is generated by a learning-based carrier design procedure with respect to a scan time for a predetermined frequency; and A PWM generator configured to generate PWM signals based on an FM carrier signal.

2. The controller according to claim 1, wherein, The PWM generator modulates the frequency of the carrier signal based on the scan time learned from EMI spectrum data.

3. The controller according to claim 1, wherein, The PWM generator monotonically increases the carrier frequency based on the learned frequency modulation carrier.

4. The controller according to claim 1, wherein, The PWM generator monotonically reduces the carrier frequency of the PWM signal based on the learned frequency modulation carrier.

5. The controller according to claim 1, wherein, The FM carrier signal is a sawtooth wave carrier.

6. The controller according to claim 1, wherein, The PWM generator modulates the FM carrier signal as a function of EMC regulations.

7. The controller according to claim 1, wherein, The measured EMI spectrum is obtained from the frequency response of the sensitive device circuit by using learned frequency modulation.

8. The controller according to claim 1, wherein, The sensitive device circuit is a power system or an electric actuator.

9. The controller according to claim 7, wherein, The learned frequency modulation is performed using a linearly modulated sine wave or triangular wave.

10. The controller according to claim 1, wherein, The PWM inverter operates in at least three-phase mode.

11. The controller according to claim 1, wherein, The PWM inverter is connected to the electric actuator, wherein the PWM signal is transmitted to the PWM inverter via an interface.

12. A signal processor for generating modulation parameters used by a pulse width modulation modulator, i.e., a PWM modulator, which generates a carrier signal for controlling an inverter driving an electric actuator, wherein, The signal processor includes: An interface configured to connect to a PWM modulator and a sensor configured to measure the electromagnetic interference spectrum, i.e., the EMI spectrum; A memory configured to store the modulation band, measured electromagnetic interference spectrum data (EMI spectrum data) of different frequency carriers, the desired EMI spectrum, and a learning-based carrier design program; and A processor, connected to memory, configured to perform the following steps: The frequency-modulated carrier signal, i.e., the FM carrier signal, is generated by solving an optimization problem, wherein the optimization problem is generated through a learned carrier design procedure with respect to the scan time for a predetermined frequency; and The generated FM carrier signal is transmitted to a signal modulator, which is configured to generate a PWM signal based on the generated FM carrier signal.

13. The signal processor according to claim 12, wherein, The PWM modulator modulates the frequency of the carrier signal based on the scan time learned from EMI spectrum data.

14. The signal processor according to claim 12, wherein, The PWM modulator monotonically increases the carrier frequency based on the learned frequency modulated carrier.

15. The signal processor according to claim 12, wherein, The PWM modulator monotonically reduces the carrier frequency of the PWM signal based on the learned frequency modulation carrier.

16. The signal processor according to claim 12, wherein, The generated FM carrier signal is a sawtooth wave carrier.

17. The signal processor according to claim 12, wherein, The PWM modulator modulates the FM carrier signal as a function of EMC regulations.

18. The signal processor according to claim 12, wherein, The measured EMI spectrum is obtained from the frequency response of the sensitive device circuit by using learned frequency modulation.

19. The signal processor according to claim 18, wherein, The sensitive device circuit is a power system or an electric actuator.

Images