PMIC Energy Harvesting Multi-Mode Power Control
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Solution Overview
Problem
Power Management Integrated Circuits (PMICs) for energy harvesting face inefficiencies when operating across a wide input and output power range due to their design in discontinuous current mode, which is not suitable for varying power conditions from energy harvesters like photovoltaic cells or thermoelectric generators.
Innovation Solution
A PMIC with a power control circuit that monitors input power and adjusts operational modes by generating configuration signals for the discontinuous current mode voltage converter, allowing it to efficiently manage charging and de-charging periods based on actual input and output voltages, thereby maintaining efficiency across varying power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a discontinuous current mode voltage converter is used in PMIC for energy harvesting, then the device complexity and PCB footprint are reduced, but the converter efficiency deteriorates when operating across wide power ranges
Solution Approach 1:
The patent implements dynamic operation mode switching between discontinuous current mode (DCM) and continuous current mode (CCM) based on real-time power level detection. When input power is low, the system operates in DCM for compact design; when input power exceeds a threshold, it switches to CCM for efficient high-power conversion, thus adapting the converter characteristics to match operating conditions
Solution Approach 2:
The patent changes the operational parameters of the voltage converter by adjusting the inductor current characteristics. It monitors the inductor current waveform and switches between DCM (where current reaches zero) and CCM (where current remains continuous), thereby changing the converter's electrical parameters to optimize efficiency across different power levels while maintaining the same physical hardware
2Power
If continuous current mode voltage converter is used to handle higher power ranges, then the power handling capability is improved, but the device complexity and PCB footprint increase due to larger inductor requirements
Solution Approach 1:
The system dynamically switches between DCM and CCM based on power level. For low-power applications, DCM is used with smaller inductors, reducing PCB footprint. When high power is available, the system transitions to CCM which can handle higher power with the same inductor, thus providing scalable power handling without proportionally increasing footprint
Solution Approach 2:
The voltage converter is designed to perform multiple functions by operating in two different modes (DCM and CCM) with the same hardware components. This multi-functionality allows a single inductor and converter circuit to handle both low-power and high-power scenarios, eliminating the need for separate converter designs for different power levels
3Stability of the object's composition
If switching frequency is increased to reduce inductor current ripple, then the current ripple is reduced, but the converter efficiency deteriorates due to increased driver consumption
Solution Approach 1:
The patent implements dynamic switching between DCM and CCM based on power levels. In DCM operation, the system accepts higher current ripple as a trade-off for lower switching frequency and reduced driver consumption. In CCM operation at higher power levels, the continuous current naturally provides smoother output, and the increased power level makes the driver consumption acceptable relative to the total power being processed
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
The solution ensures the PMIC operates efficiently regardless of the energy harvester's power output, maintaining optimal performance by dynamically adjusting the charging and de-charging periods in response to changing input conditions.
Implementation Method 1
a DCM voltage converter is outputting the output power by generating current pulses wherein each current pulse comprises a charging period T1 wherein an inducing current in the inductor is increasing until a maximum peak current Imax and a subsequent de-charging period T2 wherein the inducing current in the inductor is decreasing back to zero
Data Source
AI summary
A power management integrated circuit (PMIC) for managing energy from an energy harvester is provided. The PMIC includes a discontinuous mode (DCM) voltage converter for outputting current pulses wherein the input and output voltages are sensed and digitized. The PMIC includes a power control circuit configured for selecting a power operational mode based on a monitoring of a parameter indicative of the input power Pin and based on a comparison of this parameter with one or more parameter reference values. The PMIC further includes a controller configured for defining a maximum peak current of the current pulses based on the input and output voltages of the voltage converter and based on the power mode selected.