DC-DC Converter Switch Timing Control for Noise Reduction
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Solution Overview
Problem
Existing DC-DC converters face challenges in maintaining a constant output voltage while minimizing the increase in noise frequency band during mode transitions.
Innovation Solution
The DC-DC converter employs a control unit that adjusts the on-state and off-state times of voltage decreasing and increasing switches to maintain a constant output voltage, using a coil and switches with specific control mechanisms to inhibit overshooting and undershooting, thereby reducing noise frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of switchings of voltage decreasing switch or voltage increasing switch is gradually reduced or increased during mode changeover, then the output voltage is kept constant, but the frequency band of noise generated by switching increases
Solution Approach 1:
The control unit determines ahead of time whether to execute a voltage increasing operation or voltage decreasing operation based on the relationship between input voltage and output voltage. By pre-determining the operation type and setting appropriate switching frequencies before mode changeover begins, the system avoids the need to gradually adjust switching counts, thus preventing noise frequency band expansion while maintaining output voltage stability.
Solution Approach 2:
The control unit changes the switching frequency parameter based on the operation type. During voltage increasing operation, a first switching frequency is set; during voltage decreasing operation, a second switching frequency is set. This parameter change approach allows the system to maintain constant output voltage without gradually adjusting switching counts, thereby preventing noise frequency band expansion.
2Reliability
If the switching frequency is changed during mode changeover, then the output voltage remains constant, but the noise frequency band expands
Solution Approach 1:
The control unit pre-determines the appropriate switching frequency based on whether voltage increase or decrease operation is needed. By setting the switching frequency before mode changeover begins rather than adjusting it during transition, the system maintains output voltage constant without expanding the noise frequency band.
Solution Approach 2:
Instead of gradually adjusting switching frequency during mode changeover (conventional approach), the invention inverts the approach by pre-determining and setting the appropriate switching frequency based on the operation type before transition begins. This inversion eliminates the need for gradual frequency adjustment and prevents noise frequency band expansion.
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 keeps the output voltage constant and reduces noise frequency by adjusting switch times during mode transitions, improving stability and efficiency.
Implementation Method 1
a coil; a voltage decreasing switch that is disposed between the input power source and one end of the coil
Data Source
AI summary
A DC-DC converter includes a control unit. When switching from an increasing operation to a first operation, the control unit increases an on time in the increasing switch at a beginning of the first operation longer than an end of the increasing operation. When switching from the first operation to the increasing operation, the control unit decreases the on time in the increasing switch at a beginning of the increasing operation shorter than an end of the first operation. When switching from the second operation to the decreasing operation, the control unit decreases an off time in the decreasing switch at a beginning of the decreasing operation shorter than an end of the second operation. When switching from the decreasing operation to the second operation, the control unit increases the off time in the decreasing switch at a beginning of the second operation longer than an end of the decreasing operation.