Brushless Motor Current Phase Control for Compressor Vibration
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Solution Overview
Problem
Existing motor controllers for brushless motors in compressors, such as those used in air conditioners and refrigerators, face challenges in reducing noise and vibration caused by load torque fluctuations without compromising the power factor, especially when the capacity of inductors or smoothing capacitors is reduced for resource saving and cost reduction.
Innovation Solution
A motor controller that controls the phase of the motor current to restrict rotational speed fluctuations, allowing for vibration mitigation without a drop in the power factor, even when high-capacity inductors or smoothing capacitors are not used, by employing a control unit that detects and adjusts the rotational speed and phase of the motor current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the capacity of inductor or smoothing capacitor is reduced for resource saving and cost reduction, then device complexity and cost are reduced, but the power factor drops
Solution Approach 1:
The invention changes the control parameters of the brushless motor, specifically controlling the motor current phase to lead the voltage phase by a specific angle (beta) that is greater than the normal motor current phase difference. This parameter change enables the system to maintain a high power factor even with reduced inductor or capacitor capacity by altering the current waveform characteristics and timing.
Solution Approach 2:
The control unit continuously monitors the motor operation and dynamically adjusts the motor current phase angle to maintain optimal power factor. The system uses feedback from the motor's operational state to modulate the inverter circuit's switching timing, ensuring the current phase leads the voltage phase by the required angle under varying load conditions.
2Object-affected harmful factors
If motor current control is adjusted to reduce vibration and noise, then noise and vibration are reduced, but the power factor drops
Solution Approach 1:
The invention simultaneously optimizes two critical parameters: the motor current phase angle (set to lead voltage by angle beta) and the current amplitude modulation waveform. By carefully designing the amplitude modulation to match the load torque variation pattern while maintaining the leading phase angle, the system reduces torque pulsations and associated vibration/noise while preserving power factor.
Solution Approach 2:
The control system dynamically adjusts both the phase angle and amplitude of the motor current in real-time based on the motor's rotational speed and load conditions. This dynamic control allows the system to maintain optimal vibration reduction across varying operating conditions while keeping the power factor stable through continuous phase angle compensation.
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
Effectively reduces vibration caused by load torque fluctuations while maintaining a stable power factor, even during high-load operations, and allows for a more compact and lightweight compressor design.
Implementation Method 1
a rectifier circuit for rectifying an a.c. power output from an a.c. power source (1) to output to the inverter circuit
Implementation Method 2
an inverter circuit (3) for converting a d.c. power obtained by the rectifier circuit (2) into an a.c. power to supply to a brushless motor (4)
Data Source
AI summary
A motor controller (101) according to the invention comprises an inverter circuit (3) for driving a brushless motor (4) and a control unit for controlling the rotational speed of the brushless motor (4) by controlling the phase of the motor current of the brushless motor (4) through the inverter circuit (3).