AC-DC Converter Phantom Load Control for Low Standby Power
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Solution Overview
Problem
Conventional switching power supply converters face challenges in achieving low standby power consumption, particularly due to the difficulty in safely and efficiently discharging safety capacitors, which continue to store electric charge after the AC power supply is off, and the high costs associated with high-voltage switches required for discharging.
Innovation Solution
The implementation of a control circuit that disables the phantom load during normal operating states and enables it during under voltage lockout states to utilize energy stored in a safety capacitor, allowing the power stage circuit to be disabled until the capacitor voltage reaches a predetermined threshold, thereby reducing power consumption and costs by using a low-voltage switch integrated within the chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a common capacitor is employed at the power supply input side, then energy storage capability is improved, but standby power consumption increases due to remaining electric charge
Solution Approach 1:
The patent extracts the discharge function from the main power circuit by introducing a separate discharge circuit with a discharge switch. This allows the safety capacitor to be discharged independently during standby state, removing the harmful effect of remaining electric charge while preserving the energy storage capability during normal operation.
Solution Approach 2:
The patent implements dynamic control of the discharge switch based on the operating state of the power supply. The control circuit dynamically switches the discharge circuit on during standby state and off during normal operation, adapting the system behavior to different conditions to minimize standby power consumption while maintaining safety.
2Reliability
If a safety capacitor is used instead of a common capacitor, then safety is improved, but it becomes difficult to satisfy low standby power consumption requirements
Solution Approach 1:
The patent introduces a discharge switch as an intermediary component between the safety capacitor and ground. This mediator enables controlled discharge of the safety capacitor during standby state, allowing the system to maintain safety while reducing the harmful effect of residual charge that would otherwise consume power.
Solution Approach 2:
The discharge circuit is activated periodically or conditionally based on the operating state. During standby state, the discharge switch is turned on to discharge the capacitor; during normal operation, it is turned off. This periodic/conditional action pattern allows the system to satisfy both safety requirements and low standby power consumption requirements.
3Productivity
If high-voltage switches are used to discharge the safety capacitor, then discharge capability is improved, but cost increases
Solution Approach 1:
The patent changes the voltage parameter of the discharge switch by using a low-voltage switch instead of a high-voltage switch. This is made possible by the discharge circuit topology where the switch operates at a lower potential difference, reducing cost while maintaining adequate discharge capability through the circuit design.
Solution Approach 2:
The patent employs a low-voltage discharge switch that is cheaper than a high-voltage switch. Although the switch has lower voltage ratings, it is sufficient for the discharge function and can be replaced or upgraded more easily if needed, reducing overall system cost while maintaining discharge capability.
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
This approach enables a safer, faster discharge of safety capacitors, reduces power consumption and costs, and results in a more compact circuit structure by leveraging a low-voltage switch and auxiliary winding for energy supply, effectively addressing the challenge of low standby power consumption.
Implementation Method 1
a safety capacitor configured to receive an input power supply
Implementation Method 2
a common mode filter inductor configured to process the input power supply with a rectifier bridge and a filter
Data Source
AI summary
Disclosed are AC-DC voltage converter circuits and methods for low standby power consumption. In one embodiment, a method can include: (i) detecting operating states of an input power supply, where the input power supply is received by a safety capacitor and provided to a switching power supply circuit after being rectified and filtered; (ii) removing a phantom load when the input power supply operates in a normal operating state; (iii) loading the phantom load when the input power supply operates in an under voltage lock out state; and (iv) when the input power supply operates in the under voltage lock out state, using energy stored in the safety capacitor to supply power to a load of the switching power supply circuit and the phantom load, and disabling a power stage circuit until a voltage of the safety capacitor is reduced to less than a safety threshold value.