BLDC Motor Driver Using Terminal Voltage Pulse Width for Phase Detection
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Solution Overview
Problem
180-degree conduction driving in brushless DC motors, which offers better silent and vibration properties, is difficult to control and results in noise and vibration when a longer detection period is set for rotor position detection, compromising its efficiency.
Innovation Solution
A driving device for brushless DC motors that generates pulse-modulated control signals with specific idle times and uses terminal voltage pulse widths to detect coil current phases without inserting non-conduction periods, allowing for low noise and vibration operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If 180-degree conduction driving is used, then silent property and vibration property are improved, but control complexity increases and detection becomes more difficult
Solution Approach 1:
The patent uses terminal voltage as an intermediary signal to detect coil current phase. By measuring the terminal voltage pulse width during the idle period, the system can determine current direction without directly measuring current, simplifying the detection mechanism while maintaining 180-degree conduction driving benefits
Solution Approach 2:
The patent replaces complex current sensing mechanisms with a voltage-based detection method. Instead of using current sensors or complex detection circuits, the system substitutes mechanical/electrical current measurement with electrical voltage measurement, reducing device complexity while maintaining detection accuracy
2Measurement precision
If detection period is extended for rotor position detection, then measurement precision is improved, but silent property deteriorates and vibration occurs
Solution Approach 1:
The patent performs detection during the idle period that is already built into the 180-degree conduction driving waveform. By utilizing this pre-existing idle time for detection purposes, the system achieves accurate rotor position detection without extending the overall detection period, thereby maintaining silent operation
Solution Approach 2:
The idle period in the 180-degree conduction driving waveform serves multiple functions: it allows for current reversal and simultaneously provides the detection window for rotor position detection. This multi-functionality eliminates the need for separate detection periods, preventing noise and vibration
3Ease of operation
If 120-degree conduction driving is used, then control ease is improved, but noise and vibration increase
Solution Approach 1:
The patent changes the conduction angle parameter from 120 degrees to 180 degrees, which fundamentally alters the driving waveform characteristics. This parameter change reduces noise and vibration while the patent compensates for the increased control complexity by implementing simplified voltage-based detection and utilizing the idle period effectively
4Measurement precision
If non-conduction period is inserted for current detection, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent utilizes the periodic idle period inherent in the 180-degree conduction driving waveform for detection purposes. By synchronizing detection with this regular idle period, the system achieves precise current phase detection without inserting additional non-conduction periods, thereby maintaining motor efficiency and 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
Enables low noise and vibration operation in brushless DC motors by determining coil current phases using terminal voltage pulse widths, maintaining efficiency and silent properties.
Implementation Method 1
a driving voltage with duty cycle corresponding to the control pulse signal
Implementation Method 2
the terminal voltage is approximately a ground voltage, and when the coil current flows toward the driver from the coil
Implementation Method 3
a current phase detection portion for generating a current phase detection signal indicating a phase of current flowing in a coil
Data Source
AI summary
The present disclosure provides a device and a method for driving a motor that demonstrates low noise and/or low vibration. A pulse-modulated control pulse signal S2 is generated by a driving signal generation portion 310 at each phase. A driving voltage VU˜VW, with duty cycle corresponding to the control pulse signal S2 and being inserted with specific idle time is applied to coils LU˜LW at each phase. A current phase detection signal S3 indicating a phase of the current IL flowing through the coil LU is generated by the current phase detection portion 330 at a specific phase (the phase U) corresponding to the control pulse signal S2 according to a pulse width of a terminal voltage VU at one end of the coil LU of the phase U.