SIMO Converter PWM Peak Voltage Control for Load Stability
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Solution Overview
Problem
Single-inductor multiple-output (SIMO) switching power converter circuits face instability under heavy load due to varying gain bandwidth with load current, which affects the regulation of output voltages.
Innovation Solution
The implementation of a common control loop circuit and multiple output control loop circuits that use pulse width modulation (PWM) to regulate output voltages, with the peak voltage of the PWM signal adjusted proportionally to the inductor current to stabilize the gain bandwidth, reducing sensitivity to load current variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single-inductor multiple-output (SIMO) switching power converter circuit is used to reduce circuit area, then the circuit area is reduced, but the gain bandwidth varies with load current causing instability under heavy load
Solution Approach 1:
The patent applies dynamics by making the PWM control signal peak voltage adjustable based on inductor current. The peak voltage is set proportional to the inductor current (V_peak = k * I_L), creating a dynamic control mechanism that adapts to varying load conditions. This dynamic adjustment stabilizes the gain bandwidth across different load currents, resolving the instability issue while maintaining the SIMO topology's area efficiency.
2Reliability
If the peak voltage of the PWM control signal is increased to improve regulation under heavy load, then the regulation performance is improved, but the sensitivity to load current variations increases
Solution Approach 1:
The patent implements feedback by using current sensing circuitry to detect inductor current and using this information to adjust the peak voltage of the PWM control signal. The feedback loop ensures that the peak voltage is proportional to the inductor current, which stabilizes the gain bandwidth and reduces sensitivity to load current variations while maintaining good regulation performance across the full load range.
3Adaptability or versatility
If multiple output control loop circuits are used to generate multiple output voltages, then the functionality is improved, but the device complexity increases
Solution Approach 1:
The patent applies merging by combining multiple output control loop circuits around a single inductor and using a unified PWM control approach. The peak voltage adjustment mechanism is applied across all output control loops, creating a coordinated control system that manages multiple outputs with reduced overall complexity compared to completely independent control circuits.
Data Source
AI summary
A switching power converter circuit comprises a single inductive circuit element; a common control loop circuit coupled to a circuit input and the inductive circuit element and including switching circuit elements to charge the inductive circuit element using energy provided at the circuit input; at least one current sensing circuit configured to sense inductor current of the inductive circuit element; one or more output control loop circuits that each include switching circuit elements activated to generate an output voltage; and one or more pulse width modulation (PWM) circuits configured to generate a PWM control signal to activate the switching circuit elements of the output control loop circuits and to change a peak voltage of the PWM control signal of the one or more PWM circuits according to the inductor current.