Motor Driving Device Voltage Zero Crossing Detection
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Solution Overview
Problem
Existing motor driving technologies for brushless DC motors are costly and complex, particularly in achieving optimal leading angle control for maximizing torque, as they often require expensive current detectors or individual motor settings.
Innovation Solution
A motor driving device with a voltage zero crossing detection unit, detection period setting unit, coil voltage detection comparator, current phase detecting unit, and driving signal synthesis unit, which determines the phase of the coil current relative to the induced voltage by analyzing terminal voltage levels during specific detection periods, allowing for precise phase switch control without expensive current detectors or complex individual motor settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive current detectors are used to detect the phase of coil current, then measurement precision of current phase is improved, but device cost increases
Solution Approach 1:
The patent uses terminal voltage as an intermediary parameter to indirectly detect the phase of coil current. Instead of directly measuring current phase with expensive detectors, the system measures terminal voltage during detection periods when the coil is in high-resistance state, and infers current phase from voltage level comparisons. This intermediary approach achieves accurate phase detection without requiring costly current detectors.
Solution Approach 2:
The patent replaces the electrical measurement system (current detectors) with a voltage-based detection system. By substituting current measurement with voltage measurement during specific detection periods, the system achieves the same functional goal of phase detection while using simpler, less expensive components.
2Manufacturing precision
If individual motor settings are performed to optimize leading angle control, then manufacturing precision of motor control is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent enables the motor control system to automatically determine its own operating parameters through self-diagnosis. The detection unit automatically identifies the phase relationship between induced voltage and coil current, and the control unit automatically adjusts the leading angle accordingly. This self-service mechanism eliminates the need for manual individual motor settings while maintaining high control precision.
Solution Approach 2:
The system incorporates automatic feedback mechanisms where the detected terminal voltage levels during detection periods provide information about the actual phase relationship, which is then used to adjust the driving voltage phase. This closed-loop feedback enables precise leading angle control without requiring manual calibration for each motor.
3Power
If the phase of driving voltage is instantaneously varied according to turning number to maximize torque, then power output is improved, but device complexity increases
Solution Approach 1:
The patent implements periodic detection periods during which the coil is placed in high-resistance state and terminal voltage is measured. These periodic measurements provide the necessary information about phase relationships at different operating points, enabling the control system to adjust the leading angle appropriately without requiring continuous complex measurements and calculations.
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 solution enables low-cost, precise leading angle control, increasing control speed and precision in motor driving, thereby optimizing torque without the need for expensive detectors or complex settings, making it suitable for various motor types.
Implementation Method 1
a voltage zero crossing detection unit for detecting a voltage zero crossing point at which an induced voltage is generated by a coil under a predetermined phase
Implementation Method 2
a coil voltage detection comparator for comparing a terminal voltage generated at one end of the coil under a predetermined phase and a threshold voltage, and generating a coil voltage detection signal indicating a comparison result
Data Source
AI summary
The present disclosure provides a driving device with a low cost and/or a simple advance angle control for a motor. A voltage zero crossing detecting unit 314 is configured to detect an induced voltage generated from a coil with a specific phase of a fan motor 202 being zero of a voltage zero crossing point. A detection period setting unit 316 is configured to set at least one detection period synchronously with the voltage zero crossing point. A coil voltage detection comparator 302 is configured to compare a terminal voltage generated from one end of the coil with the specific phase with a threshold voltage, and generate a coil voltage detection signal S3 indicating a comparison result. A current phase detecting unit 318 is configured to generate a phase detection signal S8 indicating a relationship between the coil current flowing through the coil with the specific phase and a phase of an induced voltage based on a level of the coil voltage detection signal S3 in the detection period. A driving signal synthesis unit 308 is configured to generate a driving control signal S5 based on the phase detection signal S8.