BLDC Rotor Position Detection via Exciter Voltage Interruption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the rotor position of BLDC motors require operating exciter coils without power for a substantial period, leading to adverse effects on motor power and limited accuracy or frequency of position determination.
Innovation Solution
A method that interrupts and then restores the exciter voltage in a BLDC motor, allowing for the measurement of induced voltage to determine rotor position without prolonged power loss, enabling simultaneous position determination and motor acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the exciter voltage is interrupted for a substantial period to determine rotor position, then the rotor position can be determined, but the motor power is adversely affected
Solution Approach 1:
The patent applies periodic action by interrupting the exciter voltage only during specific commutation phases when the coil is naturally de-energized, rather than continuously interrupting power. This periodic measurement approach allows rotor position determination without sustained power loss, resolving the contradiction between measurement accuracy and motor power maintenance.
2Measurement precision
If the exciter voltage is interrupted for rotor position determination, then position information can be obtained, but the acceleration process is adversely affected
Solution Approach 1:
The patent uses preliminary action by utilizing the commutation process itself to prepare the coil for measurement. The coil is naturally de-energized as part of the commutation sequence before measurement begins, eliminating the need for separate power interruption that would affect acceleration. This allows position determination without disrupting the acceleration process.
3Measurement precision
If the exciter voltage is interrupted for measurement, then rotor position can be determined, but the determination frequency is limited
Solution Approach 1:
The patent applies universality by using the same commutation process for both motor control and position measurement purposes. The exciter coil serves dual functions: driving the motor during acceleration and enabling position determination during commutation phases. This multi-functionality increases determination frequency without requiring separate measurement mechanisms that would limit productivity.
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 allows for more precise and frequent rotor position determination without disrupting motor acceleration, improving the start phase and reducing power adverse effects, thereby enhancing the accuracy and efficiency of BLDC motor operation.
Implementation Method 1
capturing a voltage which is induced in the at least one exciter coil
Data Source
AI summary
A method for determining a rotor position of a BLDC motor with a magnetic rotor and stator having at least one exciter coil to which an exciter voltage is applied in accordance with a commutation process, comprises: interrupting the exciter voltage applied to the exciter coil, wherein the exciter voltage has a profile with at least one first section in which the profile of the exciter voltage has a non-vanishing finite gradient, wherein the exciter voltage in the first section is interrupted, and wherein at the time of interruption the exciter voltage has a value different from zero; capturing a voltage induced in the exciter coil by the magnetic rotor; restoring the exciter voltage to a value different from zero; and determining a rotor position of the rotor with respect to the exciter coil on the basis of the captured induced voltage.