DC Bus Voltage Sensing via High-Side Switch Standby Isolation
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Solution Overview
Problem
Existing LED power supply systems consume significant power during standby mode due to voltage sensors detecting the DC bus voltage, which is a major portion of the overall power consumption during this state.
Innovation Solution
Positioning the voltage sensor in series with the output of a high-side transistor of a DC-DC converter, such that the sensor is disconnected from the DC bus when the transistor is OFF, allowing it to detect the voltage without consuming power during standby.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage sensors are used to detect DC bus voltage during standby mode, then voltage detection is maintained, but power consumption increases significantly
Solution Approach 1:
The voltage sensor is extracted from the continuous operation state and removed from the active circuit during standby mode. By positioning the sensor in series with the high-side transistor output, the sensor is automatically disconnected when the transistor is OFF, eliminating unnecessary power consumption while preserving voltage detection capability when needed.
Solution Approach 2:
The voltage sensor's connection state is made dynamic rather than static. The sensor is connected to the DC bus when the high-side transistor is ON and disconnected when the transistor is OFF. This dynamic connection state allows the system to adapt power consumption based on operational requirements, maintaining voltage detection only when the converter is actively operating.
2Use of energy by moving object
If additional high-voltage FET is added to disconnect voltage sensors during standby, then power consumption is reduced, but device complexity and cost increase
Solution Approach 1:
The high-side transistor's existing function of switching the converter is extended to also control the voltage sensor connection. By leveraging the transistor's natural ON/OFF states, the same switching action that controls power conversion also controls sensor operation, eliminating the need for dedicated standby control circuitry and additional components.
Solution Approach 2:
The voltage sensor connection control is merged with the converter switching control. Instead of having separate control mechanisms for the sensor and the converter, both functions share the same high-side transistor switching signal. This consolidation reduces component count and simplifies the control architecture while achieving both power reduction and voltage detection goals.
Data Source
AI summary
An LED power supply, comprising: a power factor correction circuit configured to receive an input signal and provide a DC bus voltage across a DC bus; a converter configured to receive the DC bus voltage and to output a DC output voltage for powering at least one LED, wherein the converter comprises a high-side transistor, wherein the high-side transistor is OFF when the LED power supply is in standby; a voltage sensor being configured to output a voltage sensor output; and a controller configured to receive the voltage sensor output and to output a control signal according to the voltage sensor output, wherein the voltage sensor is positioned in series with the output of the high-side transistor, such that, when the high-side transistor is ON, the voltage sensor output is proportional to the DC bus voltage, and when the transistor is OFF, the voltage sensor is disconnected from the DC bus.