Parallel Output Channel Load Balancing With Active Current Feedback
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Solution Overview
Problem
Existing power supply apparatuses with parallel-connected output channels face challenges in achieving low-loss load balancing due to unequal current distribution among branches, which is exacerbated by temperature-dependent resistance variations and manufacturing tolerances, leading to inefficiencies and increased power loss.
Innovation Solution
A power supply apparatus with a controller that detects instantaneous output currents, determines utilization levels, and controls current regulators to form a subset of output channels with the highest and lowest utilization levels, ensuring load balancing by adjusting the current limiting mode of these channels, using field-effect transistors or bipolar transistors to minimize losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If passive load balancing methods relying on temperature-dependent resistance are used, then load distribution occurs naturally, but manufacturing tolerances and circuit design variations cause unequal current distribution and increased power loss
Solution Approach 1:
The patent implements an active feedback control system that continuously monitors current distribution among parallel output channels and dynamically adjusts switching elements to equalize current flow. Sensors detect current imbalances caused by manufacturing tolerances or thermal variations, and the control system responds by modulating the switching elements to redistribute current, thereby maintaining equal load sharing and minimizing power loss.
Solution Approach 2:
The patent dynamically changes the on-resistance parameter of switching elements through active control to compensate for manufacturing tolerances and thermal drift. By adjusting the switching element parameters in real-time based on detected current distribution, the system equalizes current flow across parallel channels, resolving the contradiction between natural passive balancing and the need for precise current distribution equality.
2Loss of energy
If MOSFETs with lower RDS,on are used to reduce power loss, then current distribution becomes more unequal due to manufacturing tolerances, but using higher resistance MOSFETs increases power loss
Solution Approach 1:
The feedback control system continuously monitors the actual current distribution and detects deviations caused by RDS,on manufacturing tolerances. When current imbalance is detected, the system adjusts the switching elements to compensate for the resistance variations, allowing the use of low-RDS,on MOSFETs while maintaining equal current distribution despite manufacturing precision variations.
Solution Approach 2:
The control system automatically detects and compensates for RDS,on variations without external intervention. The system self-adjusts the switching element parameters to equalize current distribution, allowing the power supply to maintain optimal performance despite manufacturing tolerances in the MOSFET resistance parameters.
3Power
If parallel connection of output channels is implemented to extend power capacity, then cost-effective power expansion is achieved, but unequal current distribution increases power loss
Solution Approach 1:
The feedback control system monitors current distribution across all parallel output channels and dynamically adjusts switching elements to equalize current flow. This ensures that the full power capacity of the parallel-connected channels is utilized efficiently, minimizing power loss while maintaining the cost-effective power extension benefits of the parallel architecture.
Solution Approach 2:
The active control system continuously maintains optimal current distribution across parallel channels, ensuring that all channels operate at their intended capacity throughout operation. This continuous adjustment prevents power loss from unequal distribution while maintaining the extended power capacity that motivated the parallel connection in the first place.
4Ease of operation
If dynamic switching operation is used to control current distribution, then current is determined by threshold voltage, but the MOSFET with lower threshold voltage assumes disproportionate switching losses
Solution Approach 1:
The feedback control system detects disproportionate switching losses caused by threshold voltage variations and adjusts the switching elements to equalize the switching burden. By monitoring current distribution and switching losses, the system dynamically modifies switching parameters to ensure that no single MOSFET bears excessive switching losses, maintaining ease of operation while reducing total switching losses.
Solution Approach 2:
The system dynamically changes the switching parameters of individual MOSFETs based on their threshold voltage characteristics. By adjusting switching timing, duration, or amplitude for each device, the system equalizes switching losses across parallel channels while maintaining the dynamic switching control needed for responsive current distribution.
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 low-loss load balancing across output channels by dynamically adjusting current distribution, maintaining stability and reducing power loss, even under varying operating conditions.
Implementation Method 1
In stationary mode, the respective RDS,on determines the current distribution. The MOSFET with the lower resistance assumes the greater current flow.
Implementation Method 2
the current is incorporated quadratically into the power loss of the MOSFET
Data Source
AI summary
A power supply apparatus, in particular an electronic fuse for a power supply, includes a first set of output channels and a controller for load balancing between the output channels of the first set, wherein a first number of output channels in the first set is greater than or equal to two, where the output channels of the first each have a current regulator and a switching element, the current regulators are configured to control the switching element in its respective output channel, where the output channels of the first set each have an instantaneous output current and a rated current, and where it is possible for the output channels of the first set (M1) to be connected in parallel.