Totem-Pole PFC Current Detection Without Transformers
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Solution Overview
Problem
Existing power converters with totem-pole power factor correction circuits face complexity and increased cost due to the need for current detection signal insulation and the use of current transformers, which complicate control IC operations and are expensive.
Innovation Solution
A power converter configuration that includes a series connection of first and second current detectors and a control circuit performing pulse width control for half-wave switches, using wide bandgap semiconductors and insulating transformers to simplify the circuit and reduce costs, while maintaining high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current transformer is used to detect AC current, then current detection is achieved, but the circuit becomes complicated and cost increases
Solution Approach 1:
The patent extracts the current detection function from the complex current transformer and insulation circuitry, implementing it instead through simple voltage detection across known impedances (switches and diodes). This eliminates the need for current transformers and complex insulation circuits while maintaining detection capability.
Solution Approach 2:
The patent uses voltage measurement as a substitute (copy) for direct current measurement. By measuring voltage across known elements and calculating current from these voltage readings, the system achieves current detection without requiring complex current sensing hardware.
2Ease of operation
If signal insulation is implemented for control IC operation, then control compatibility is achieved, but circuit complexity increases
Solution Approach 1:
The patent removes the signal insulation requirement entirely by redesigning the detection approach. Instead of insulating current transformer outputs, the system directly measures voltages that are already referenced to the control IC's ground, eliminating insulation circuits while maintaining control compatibility.
Solution Approach 2:
The patent uses voltage measurements across switches and diodes as intermediaries to indirectly obtain current information. These voltage measurements serve as mediators that bridge the power stage and control IC without requiring insulation, as they are naturally referenced to the control ground.
3Measurement precision
If current transformer is used for detection, then accurate current measurement is achieved, but cost increases
Solution Approach 1:
The patent replaces expensive current transformers with inexpensive voltage measurement circuits. By using simple voltage dividers and ADC measurements across known low-value impedances, the system achieves sufficient measurement accuracy at a fraction of the cost of current transformers.
Solution Approach 2:
The patent changes the measurement parameter from direct current measurement to voltage measurement. This parameter change allows the use of inexpensive voltage sensing circuits instead of expensive current transformers, while maintaining adequate measurement precision through mathematical conversion.
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 achieves high efficiency power conversion with a simple configuration by directly utilizing the detection signals from the current detectors for control, reducing recovery losses and operational complexity, and lowering overall costs.
Implementation Method 1
a series connection of a first current detector and a second current detector... based on a detection result of current by the first current detector or a detection result of current by the second current detector
Data Source
AI summary
According to one embodiment, there is provided a power converter including a totem-pole power factor correction circuit that can achieve reduction in recovery loss with a simple structure. A power converter according to an embodiment includes a totem-pole power factor correction circuit, a series connection of a first current detector and a second current detector, and a control circuit.