Switching Power Supply Jitter Control for AM Radio Interference
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Solution Overview
Problem
Switching power supply devices generate high-frequency noise that interferes with AM radio broadcasts, despite existing jitter control technologies, as the noise spectrum spreads and overlaps with AM radio frequencies, causing reception impedance.
Innovation Solution
A switching power supply device with a reception frequency detection unit, harmonic detection unit, and frequency determination unit determines the jitter width for the power supply frequency to avoid interference by controlling the jitter of the semiconductor switching element, ensuring the power supply frequency does not overlap with the AM radio frequency bandwidth, using a jitter control unit to pulse width modulate the power supply frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If switching frequency jitter control is applied to reduce power supply noise, then power supply noise level is reduced, but the noise spectrum spreads and overlaps with AM radio frequencies, causing reception impedance
Solution Approach 1:
The patent applies dynamics by making the switching frequency adjustable and variable. The control unit dynamically changes the switching frequency based on detected AM radio broadcast frequencies, avoiding fixed frequency operation. This allows the system to adapt to different radio frequency environments and prevent noise overlap with AM broadcast bands.
Solution Approach 2:
The patent changes the frequency parameter of the switching power supply to avoid interference with AM radio broadcasts. By detecting AM broadcast frequencies and adjusting the switching frequency accordingly (including using non-integer multiples), the system modifies its operating parameters to eliminate harmful frequency overlaps while maintaining effective power conversion.
2Power
If switching operation is performed to supply power, then power supply function is achieved, but high frequency power supply noise is generated that interferes with AM radio broadcasts
Solution Approach 1:
The patent changes the switching frequency parameter to non-integer multiple relationships with AM broadcast frequencies. By setting the switching frequency such that it is not an integer multiple of AM broadcast frequencies, the harmonic noise spectrum is shifted away from AM radio bands, reducing interference while maintaining power supply functionality.
Solution Approach 2:
The system dynamically adjusts the switching frequency based on detected AM broadcast frequencies. The control unit monitors radio frequency environment and modifies the switching frequency in real-time to avoid generating noise at frequencies that would interfere with AM radio reception, thereby maintaining both power supply capability and radio reception quality.
3Device complexity
If fixed switching frequency is used for simple control, then control simplicity is maintained, but noise frequency consistently overlaps with AM radio frequencies causing reception impedance
Solution Approach 1:
The patent implements feedback by detecting AM radio broadcast frequencies and using this information to adjust the switching frequency. The control unit continuously monitors the radio frequency environment and modifies the power supply switching frequency accordingly, creating a closed-loop system that automatically avoids interference while maintaining operational simplicity.
Solution Approach 2:
The system transitions from fixed to dynamic frequency control. The switching frequency is no longer static but is continuously adjusted based on detected AM broadcast frequencies. This dynamic adaptation allows the system to maintain simple control architecture while effectively avoiding noise interference through automated frequency adjustment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces power supply noise interference with AM radio broadcasts by spreading the noise spectrum, avoiding impedance and ensuring clear reception, even when the vehicle moves through varying radio frequency environments.
Implementation Method 1
high frequency power supply noise (electromagnetic interference noise; EMI noise) is generated accompanying a switching operation in a semiconductor switching element
Implementation Method 2
a jitter control unit that controls the jitter of the power supply frequency fs in accordance with the determined jitter width Δf, thereby switching the semiconductor switching element at a frequency of [fs±Δf/2]
Data Source
AI summary
A switching power supply device that can reduce power supply noise includes a switching power supply device main body that switches a semiconductor switching element at a power supply frequency fs, and supplies power to an electronic instrument such as an AM radio receiver. The switching power supply device detects an AM radio reception frequency fc and a power supply harmonic component that interferes with the AM radio reception frequency fc. Further, the switching power supply device determines, in a sideband of the AM radio reception frequency fc on a side that does not include the power supply harmonic component, a jitter width Δf for the power supply frequency fs, avoiding a bandwidth BW of the AM radio reception frequency fc, controlling the jitter of the power supply frequency fs in the jitter width Δf, and switching the semiconductor switching element at a frequency of [fs±Δf/2].