Half-Bridge Power Supply Current Sensing at High Switching Frequency
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Solution Overview
Problem
Existing switched mode electrical power supply devices face inaccuracies in load current measurements due to limited bandwidth of high-side and low-side feedback loops, particularly at higher switching frequencies, leading to instability and reduced accuracy.
Innovation Solution
Implementing a load current sensing device with low-side and high-side sensing transistors and regulators, along with current adding devices to refine sensing signals using decaying exponential functions, maintaining loop stability and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher switching frequencies are used to improve productivity, then the measurement accuracy deteriorates due to limited bandwidth of feedback loops
Solution Approach 1:
The patent applies preliminary action by pre-shaping the sensing signals using exponential functions before they enter the feedback loops. This preprocessing compensates for the bandwidth limitations in advance, allowing accurate measurements even at higher switching frequencies without requiring the feedback loops to respond faster.
2Device complexity
If conventional sensing methods are used to maintain device complexity at acceptable levels, then measurement accuracy deteriorates
Solution Approach 1:
The patent changes the temporal parameters of the sensing signals by applying exponential shaping functions. This transforms the signal characteristics without requiring additional hardware complexity, thereby improving measurement accuracy while maintaining acceptable device complexity.
3Measurement precision
If feedback loop bandwidth is increased to improve measurement accuracy, then loop stability deteriorates
Solution Approach 1:
By pre-shaping the sensing signals with exponential functions, the patent eliminates the need to increase feedback loop bandwidth. The accuracy improvement is achieved through signal preprocessing rather than loop modification, thereby maintaining loop stability while improving measurement precision.
4Ease of operation
If conventional current sensing is used to keep ease of operation simple, then measurement accuracy deteriorates at high switching frequencies
Solution Approach 1:
The patent modifies the temporal parameters of the sensing signals using exponential shaping. This approach maintains operational simplicity while significantly improving measurement accuracy at high switching frequencies, as the shaping is implemented through standard circuit elements rather than complex control procedures.
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 provides accurate load current measurements across both switching modes without loop instability, improving system performance by shaping sensing signals to match ideal profiles.
Implementation Method 1
a low-side sensing transistor which acts as a current mirror for the portion of the load current during the second switch mode
Implementation Method 2
a high-side sensing transistor which acts as a current mirror for the portion of the load current during the first switch mode
Implementation Method 3
an output of the low-side regulator is connected to the second input of the low-side regulator in order to form a low-side feedback loop
Implementation Method 4
an output of the high-side regulator is connected to the second input of the high-side regulator in order to form a high-side feedback loop
Implementation Method 5
current adding devices to refine sensing signals using decaying exponential functions
Data Source
AI summary
An electrical power supply device configured for providing a load current, the electrical power supply device comprising: a half bridge circuit comprising a high-side power transistor and a low side power transistor; a gate driver circuit configured to drive the high-side power transistor and the low-side power transistor alternatively in a first switching mode; a load current sensing device, wherein the load current sensing device comprises for sensing a portion of the load current in the second switching mode a low-side sensing transistor and a low-side regulator; a load current sensing refining device, wherein the load current sensing refining device comprises a low-side current adding device configured for adding a low-side refining current to a low-side feedback loop during the second switching mode in order to refine a low-side sensing signal for the portion of the load current in the second switching mode at the output of the low-side regulator.