Bi-directional Converter Variable Resistance Gate Control
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Solution Overview
Problem
Bi-directional converters face the challenge of self turn-on phenomena during both step-up and step-down operations, leading to inefficiencies and potential short circuits, which existing solutions complicate delay management and increase power consumption, limiting switching frequency.
Innovation Solution
A bi-directional converter configuration with a controller that employs variable resistance circuits for both step-up and step-down operations, using a first and second driver to control switching elements via resistance circuits that adjust resistance values based on the operation mode, preventing unintended switching element activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a delay signal is used to control the variable resistor in the gate circuit, then the self turn-on phenomenon is suppressed, but the device complexity increases and power consumption increases
Solution Approach 1:
The patent extracts the delay function from a separate delay signal generation circuit and integrates it into the existing PWM control circuitry. The PWM controller inherently generates delayed control signals for complementary switching elements, eliminating the need for additional delay circuits and reducing overall device complexity while maintaining self turn-on prevention capability
Solution Approach 2:
The patent combines the delay function with the PWM control signal generation. The PWM controller simultaneously generates both the primary control signal and the delayed control signal for the second switching element, merging multiple functions into a single control unit and reducing the number of separate components needed
2Reliability
If a delay signal is used to control the variable resistor, then the self turn-on phenomenon is suppressed, but the power consumption increases
Solution Approach 1:
The patent employs periodic PWM control signals to switch the power MOSFETs on and off at high frequency. The variable resistor is controlled periodically through the PWM duty cycle, allowing the circuit to maintain self turn-on prevention with lower average power consumption compared to continuous activation of delay circuits
Solution Approach 2:
The PWM controller automatically generates the appropriate control signals including the delayed signal for the second switching element, eliminating the need for separate active delay circuit components that would continuously consume power. The system uses its own control signals to achieve the delay function
3Reliability
If a delay signal is used for controlling the variable resistor, then the self turn-on is prevented, but the upper limit of switching frequency is limited
Solution Approach 1:
The patent uses a variable resistor whose resistance value can be dynamically adjusted through PWM control, rather than relying on fixed delay circuits. This dynamic control allows the switching frequency to be varied without being constrained by fixed delay timing, enabling higher switching frequencies while maintaining self turn-on prevention
Solution Approach 2:
The patent changes the resistance parameter of the gate resistor dynamically using PWM control to achieve the desired delay effect. By varying the resistance value rather than using fixed delay timing, the system can operate at higher switching frequencies without being limited by predetermined delay intervals
4Device complexity
If fixed resistance circuits are used for both switching elements, then the circuit design is simplified, but self turn-on occurs during switching operations
Solution Approach 1:
The patent applies different resistance characteristics to different switching elements. The first power MOSFET uses a fixed gate resistor, while the second power MOSFET uses a variable resistor controlled by PWM. This localized differentiation addresses the specific self turn-on vulnerability of the second element without complicating the entire circuit design
Solution Approach 2:
The patent introduces a PWM-controlled variable resistor as an intermediary between the control signal and the second switching element. This intermediary component provides the necessary delay and control function to prevent self turn-on while maintaining overall circuit simplicity through integrated control
Data Source
AI summary
A controller controls a bi-directional converter which includes: a first input/output terminal and a second input/output terminal for receiving and outputting a voltage stepped up by a step-up operation and a voltage stepped down by a step-down operation; a first switching element; a second switching element; and an inductor. The controller includes: a first driver which controls the first switching element via a first resistance circuit; a second driver which controls the second switching element via a second resistance circuit; and an operation mode setter which selects one of the step-up operation and the step-down operation, wherein at least one of the first resistance circuit and the second resistance circuit is a variable resistance circuit which has a resistance value that varies for the step-up operation and the step-down operation, in accordance with selection made by the operation mode setter.