Switching Mode Power Supply Propagation Delay Compensation
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Solution Overview
Problem
Conventional switching mode power supplies (SMPS) fail to maintain maximum output power when input voltage changes due to propagation delay times, such as controller delays and switch turn-off delays, affecting the stability of the output power.
Innovation Solution
The SMPS incorporates a feedback circuit and a switching controller that compensates for propagation delays by comparing a signal fluctuating with the current through the main switch to a reference voltage, using a saw-tooth signal and resistors to adjust the duty cycle of the main switch, ensuring consistent output power independent of input voltage variations and temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SMPS control method is used, then the control circuit is simple, but the maximum output power cannot be maintained when input voltage changes due to propagation delay
Solution Approach 1:
The patent applies preliminary action by generating a delay compensation signal in advance that predicts and compensates for propagation delays before they affect the output. The control circuit generates this compensation signal based on the sawtooth wave and current signal, then adds it to the PWM signal to pre-correct for expected delays, ensuring maximum output power is maintained despite inherent propagation delays in the circuit.
2Stability of the object's composition
If propagation delay compensation is implemented, then output power stability is improved, but the control circuit complexity increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the current through the main switch and using this information to adjust the delay compensation signal. The current signal is compared with a sawtooth wave to generate a PWM signal, and the delay compensation is dynamically adjusted based on this feedback loop, ensuring output power stability while using a relatively simple circuit implementation.
Solution Approach 2:
The patent uses an intermediary approach by introducing a delay compensation signal as a mediating element between the PWM control and the actual switch operation. This compensation signal acts as an intermediary that bridges the gap caused by propagation delays, allowing the control circuit to maintain stability without requiring complete redesign of the control architecture.
3Power
If duty cycle is adjusted to compensate for propagation delay, then maximum output power is maintained, but current variation through main switch increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the duty cycle of the main switch based on the delay compensation signal. The control circuit modifies the duty cycle parameter in real-time to compensate for propagation delays, ensuring maximum output power is maintained. The circuit also incorporates current limiting mechanisms to manage current variation through the main switch, balancing power output with component safety.
Data Source
AI summary
A switching mode power supply includes a power supply, a feedback circuit, and a switching controller. The power supply includes a main switch coupled to a primary coil of a transformer and supplies power to a secondary coil of the transformer according to an operation of the main switch. The feedback circuit generates a feedback voltage corresponding to an output voltage applied to the secondary coil. The switching controller compensates a propagation delay by controlling a duty of the main switch according to a result of comparing a first signal that fluctuates according to a first voltage corresponding with a current flowing through the main switch to a reference voltage corresponding to the feedback voltage.