## 3 Results and Discussion  
The extensive adoption of silicon carbide (SiC) devices and other wide-bandgap devices has led to a continual rise in the switching frequency of power converters. This trend towards higher frequencies exacerbates EMI challenges encountered by conventional PWM power converters. Research suggests that employing uniformly distributed chaotic signals for frequency modulation of conventional PWM converters can effectively enhance the electromagnetic compatibility performance of high-frequency converters [21; 37; 38].  
This section emphasizes the outstanding performance achieved by employing uniformly distributed chaotic signals to suppress common-mode conducted EMI in an active clamp flyback converter, thus underscoring the strategy's significant potential application value.  
The utilization of [PERSON]'s chaotic signals for EMI suppression is highly favored [39]. This section conducts comparative experiments using one component of [PERSON]'s chaotic signals as the control group and analyzes the mechanism of employing uniformly distributed chaotic signals to suppress EMI.  
Construction of Experimental Prototype and Implementation Scheme of Chaotic Spread Spectrum Modulation PWM  
The flyback converter is a widely used topology. Active clamp technology can enhance its performance. This section uses Texas Instruments' (TI) active clamp voltage mode PWM controller LM5025A (Texas Instruments, Dallas, TX, USA) as an example to illustrate the implementation of chaotic spread spectrum PWM control technology in an analog control system. Based on the schematic diagram shown in Figure 10, an active clamp flyback converter based on LM5025A was constructed, and the prototype is shown in Figure 11. The main parameters of the prototype are shown in Table 1.  
Figure 9: Autocorrelation function (ACF) and power spectral density (PSD) of \(x\) and \(y\): (**a**) ACF of \(x\); (**b**) PSD of \(x\); (**c**) ACF of \(y\); (**d**) PSD of \(y\).  
Figure 11: Prototype of an active clamp flyback converter based on LM5025A.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Specification or Value** \\ \hline Controller & LM5025A \\ Optocoupler & TLP250H \\ Precision Programmable Reference IC & TLA31C \\ MOSFET \(S_{1}\) & CS9N90 \\ MOSFET \(S_{2}\) & SMF5N60 \\ Diode \(D_{0}\) & AIDW10S65C5 \\ Input voltage \(u_{\text{in}}\) & 180 V–235 V alternating current \\ Output voltage \(U_{\text{o}}\) & 15 V direct current \\ Rated power \(P_{\text{o}}\) & 45 W \\ \hline \hline \end{tabular}
\end{table}
Table 1: The main parameters of the prototype.  
Figure 10: Schematic diagram of an active clamp flyback converter based on LM5025A.  
The controller LM5025A has two methods for implementing spread spectrum modulation, as shown in Figure 12. Among them, the digital spread spectrum implementation has better anti-interference capability, and this implementation scheme is chosen in this paper.  
Using a uniform distribution chaotic signal \(\mathbf{y}\) to modulate the frequency of the test prototype based on LM5025A, the sync pulse and OUTA waveform are shown in Figure 13, in which, the spreading range is [80 kHz, 120 kHz], Channel 2 is the chaotic spread spectrum modulated synchronization pulse, and Channel 1 is the output waveform of OUTA under the fixed conduction time mode.