Switching Element Driver Circuit Using Pulse Frequency Encoding
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Solution Overview
Problem
Existing power electronic devices face challenges in efficiently controlling switching elements due to high voltage and large current, which requires electrical isolation and often results in increased costs and delays, especially when using optic fibers for medium voltage isolation.
Innovation Solution
A driving and controlling method that uses a primary controller and secondary controller coupled via an isolation communication unit, sending specific pulse sequences to control switching elements, allowing for rapid switching and reduced handover time between latching and starting modes, thereby reducing the need for multiple optic fibers and minimizing delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If encoding and decoding is employed to transmit switching signals and protecting signal via optic fiber, then the protecting optic fiber can be eliminated and cost is reduced, but high delay is introduced which creates difficulty in fulfilling high-frequency switching and rapid latching
Solution Approach 1:
The patent uses periodic pulse sequences with different frequencies to encode both normal driving signals and latching signals through a single optic fiber. Normal operation uses one pulse frequency while latching operation uses a different pulse frequency, eliminating the need for separate protecting optic fibers while maintaining rapid response through direct frequency-based signal differentiation without complex encoding/decoding delays
2Reliability
If a protecting optic fiber is added to transfer protecting signals in addition to driving optic fiber, then rapid latching control can be achieved, but the cost increases
Solution Approach 1:
The single optic fiber is designed to perform multiple functions: it transmits both normal driving signals and latching signals by varying the pulse frequency. The same fiber that drives the switching elements during normal operation also carries the latching control signals when needed, eliminating the need for a separate protecting optic fiber while maintaining reliable latching control
Solution Approach 2:
Different pulse frequencies in the periodic signal sequence indicate different operational modes: one frequency range represents normal driving signals while another frequency range represents latching signals. This frequency-division multiplexing allows the single optic fiber to reliably transmit both types of signals without confusion or interference
3Reliability
If dead zone is added to switching signals to control complementary switches, then proper switching control can be achieved, but switching frequency and response speed are reduced
Solution Approach 1:
The patent dynamically adjusts the pulse width and frequency of driving signals based on operational requirements. During normal switching operation, the signals are optimized for high-frequency switching with minimal dead zones. When latching is required, the pulse characteristics change to ensure reliable turn-off. This dynamic adaptation allows the system to achieve both high switching frequency during normal operation and reliable latching when needed
Data Source
AI summary
A driving and controlling method and a circuit thereof are provided. The method includes: sending, by a primary controller, a first signal that includes a first type of pulse sequence and a second type of pulse sequence; receiving the first signal, by a secondary controller, and identifying a pulse type of the first signal; when a first type of pulse is detected, the secondary controller outputs multiple switching signals to respectively control multiple switching elements to turn off; when a second type of pulse is detected, the secondary controller outputs multiple switching signals to respectively control multiple switching elements to work as normal. A level of the first signal is maintained constant between the first type of pulse sequence and the second type of pulse sequence. The disclosure features cost-efficiency and low driving delay.