Brushless DC Motor Driver Circuit Voltage Range and Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional driving devices for brushless DC motors in fans have limited efficiency, operate within a narrow voltage range, and are not environmentally friendly, making them unsuitable for applications requiring higher power or faster switching speeds.
Innovation Solution
A driving device comprising a protection circuit, storage circuit, control circuit, and bridge circuit with NMOS FETs, where the control circuit manages switching units to optimize power usage across a wider voltage range (4-20 volts), enhancing the motor's utility and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two NMOS FETs are used in the driving device, then the structure is simple and the price is low, but the efficiency is lower
Solution Approach 1:
The driving device is segmented into an upper bridge circuit and a lower bridge circuit, with each circuit using appropriate FET types (PMOS for upper, NMOS for lower) optimized for their specific functional requirements, thereby resolving the conflict between structural simplicity and efficiency
Solution Approach 2:
Different parts of the driving device use different FET types with locally optimized properties: PMOS FETs in the upper bridge circuit provide better voltage handling, while NMOS FETs in the lower bridge circuit provide faster switching, achieving overall efficiency improvement without uniform complexity
2Loss of energy
If PMOS FETs are used in the upper bridge circuit, then the efficiency is higher, but the switching speed is slower and switching loss is higher
Solution Approach 1:
The bridge circuit is segmented into upper and lower parts with different FET types, allowing the upper circuit to use PMOS for efficiency while the lower circuit uses NMOS for switching speed
Solution Approach 2:
The upper bridge circuit locally uses PMOS FETs optimized for voltage handling and efficiency, while the lower bridge circuit locally uses NMOS FETs optimized for switching speed, matching each component's properties to its functional requirements
3Speed
If an integrated driving IC is used to control the driving device, then the switching speed is improved, but the price is higher and the operation voltage range is limited to 10-20 volts
Solution Approach 1:
The driving device uses a universal full-bridge architecture that can operate with different FET types and control configurations, enabling it to function across a wide voltage range (4-20V) without requiring a specialized integrated IC, thus achieving both switching speed and voltage adaptability
Data Source
AI summary
A driving device of a brushless DC motor for a fan includes a protection circuit, a storage circuit, a control circuit and a bridge circuit. The protection circuit is electrically connected with an auxiliary power. The storage circuit electrically connected with the protection circuit receives the auxiliary power. The control circuit is electrically connected with the protection circuit and the storage circuit. The bridge circuit electrically connected with the control circuit has a first switching unit, a second switching unit, a third switching unit and a fourth switching unit. The first and second switching units are coupled with one end of a motor coil. The third switching unit and the fourth switching unit are coupled with the other end of the motor coil. The first switching unit is electrically connected with the third switching unit, and the second switching unit is electrically connected with the fourth switching unit.