Transformer Auxiliary Winding Driver for LED Power Supply
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Solution Overview
Problem
Existing LED drivers using self-supply AC to DC or DC to DC converters face challenges in providing sufficient power to devices when the load device is off or infrequently operated, leading to potential communication failures in wireless controllers and undesirable flickering in dimmable LEDs due to output current offsets.
Innovation Solution
A driver configuration that selectively energizes a primary winding of a transformer to operate a voltage supply using an auxiliary winding, ensuring sufficient power to devices even during light-off operations, and adjusts the duty cycle of a PWM signal based on current or power levels to maintain accurate control of current output to the load device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a separate transformer or non-isolated topology is used to power devices, then device power supply is simplified, but electrical isolation and safety are compromised
Solution Approach 1:
The auxiliary winding serves dual purposes: providing electrical isolation through the transformer structure while simultaneously powering the driver and controller devices. This multi-functional approach eliminates the need for separate power supply circuits while maintaining safety isolation.
Solution Approach 2:
The transformer's auxiliary winding self-generates the power needed to operate the driver and controller, eliminating external power requirements. The system powers itself through the isolation transformer without needing separate power supply circuits.
2Loss of energy
If the load device is off or infrequently operated, then energy consumption is reduced, but power supply to devices becomes insufficient leading to communication failures
Solution Approach 1:
The driver employs periodic pulse signaling to energize the auxiliary winding and recharge the output capacitor during intervals when the load is off. This periodic activation maintains sufficient voltage levels to support controller operation and wireless communication even during light-off periods.
Solution Approach 2:
The output capacitor is pre-charged during periods when the load is operating, storing energy in advance. This preliminary energy storage ensures that the controller and communication modules have sufficient power available even when the load is subsequently turned off.
3Adaptability or versatility
If PWM duty cycle is adjusted to control current output, then power control flexibility is improved, but output current accuracy may be affected by variable current consumption
Solution Approach 1:
The driver incorporates feedback mechanisms that monitor the actual current consumption of the auxiliary winding and adjust the PWM duty cycle accordingly. This feedback loop compensates for variable current consumption, maintaining accurate current control despite changes in power supply conditions.
Solution Approach 2:
The driver dynamically adjusts the PWM duty cycle in real-time based on the actual power consumption of the auxiliary winding and output capacitor charge state. This dynamic adaptation ensures accurate current control while maintaining flexibility in power delivery.
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
Ensures consistent power supply to devices, preventing communication failures and flickering issues in LEDs by using the auxiliary winding to power the driver and controller, and compensating for variable current consumption, thereby maintaining accurate control of current output.
Implementation Method 1
The transformer includes at least a primary winding and an auxiliary winding. The voltage supply is configured to receive an electrical current having a constant average current over time from the auxiliary winding
Implementation Method 2
The voltage supply includes a capacitor for storing energy
Data Source
AI summary
In one example, a system includes a controller, a transformer including at least a primary winding and an auxiliary winding, a voltage supply, and a driver. The controller is configured to output an indication of a target current or a target power. The voltage supply is configured to receive an electrical current having a constant average current over time from the auxiliary winding and to output variable electrical current for supplying the controller. The voltage supply includes a capacitor for storing energy and a current sink for consuming a current. The driver is configured to selectively energize the primary winding for supplying one or more load devices based on the target current or the target power and selectively energize the primary winding for operating the voltage supply based on an indication of a voltage at the voltage supply.