Synchronous Motor Drive Phase Control for Noise Reduction
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Solution Overview
Problem
Conventional synchronous motor drive apparatuses suffer from mechanical noise and inefficiency due to non-optimal voltage amplitude and phase determination, which is influenced by motor parameters, leading to fluctuating motor speed and reduced efficiency.
Innovation Solution
A synchronous motor drive apparatus that determines voltage amplitudes and phases based on q-axis and d-axis current command values, independent of motor parameters, using a microcomputer-controlled system with Hall ICs for position sensing and current polarity detection, allowing for efficient speed and phase control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If voltage amplitudes are determined based on current from power source and torque command, then motor speed can be controlled, but mechanical noise increases due to non-optimal voltage determination
Solution Approach 1:
The patent applies feedback by detecting the actual phase currents, calculating phase differences between position sensor signals and current phase signals, and using this feedback to correct the sinusoidal signal phase. This closed-loop control ensures optimal voltage phase determination that reduces mechanical noise while maintaining speed control.
Solution Approach 2:
The patent changes the control parameters from using only power source current and torque command to using detected phase currents and phase differences. By dynamically adjusting voltage amplitudes and phases based on actual motor operating conditions rather than fixed calculations, the system achieves optimal performance with reduced noise.
2Ease of operation
If voltage amplitudes are determined based on current from power source and torque command, then motor can be driven, but structure becomes complex due to additional current detection circuit
Solution Approach 1:
The patent makes the current detection circuit multi-functional by using it for both torque calculation (via current amplitude detection) and phase control (via phase difference detection). This single circuit serves multiple purposes, eliminating the need for separate detection systems and reducing overall device complexity.
Solution Approach 2:
The patent merges the functions of torque command processing and phase control into a unified system. The same current detection circuit and processing unit that handle torque calculations also perform phase difference detection and correction, combining multiple functions into integrated operations.
3Device complexity
If voltage phases coincide with phase currents, then control is simplified, but efficiency decreases in salient pole machines due to reluctance torque
Solution Approach 1:
The patent changes the phase relationship parameter from coincidence (0 phase difference) to an optimized phase difference based on detected signals. For salient pole machines, this allows the system to account for reluctance torque effects and maintain optimal efficiency by adjusting the voltage phase relative to the current phase based on actual operating conditions.
Solution Approach 2:
The patent uses feedback from phase difference detection to dynamically adjust the voltage phase. Rather than using a fixed phase relationship, the system continuously monitors the actual phase difference between position sensor signals and current signals, and corrects the voltage phase accordingly to maintain optimal efficiency.
4Loss of energy
If phase difference correction is applied, then efficiency increases, but device complexity increases due to additional detection and correction circuits
Solution Approach 1:
The patent makes the control circuit multi-functional by having it perform both torque calculation and phase difference correction using the same hardware resources. The microcomputer or control unit that processes torque commands also detects phase differences and generates corrected sinusoidal signals, eliminating the need for separate dedicated correction circuits.
Solution Approach 2:
The patent merges the phase difference detection and correction functions with the existing torque control processing. The same control unit that generates torque commands also performs phase difference measurement and correction, combining multiple control functions into a unified processing system.
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
The solution enables high-efficiency operation with reduced mechanical noise and cost-effective design, capable of driving synchronous motors with stable speed and wide application versatility without relying on motor parameters.
Implementation Method 1
The Hall IC detects the positions of the magnetic poles of the synchronous motor
Implementation Method 2
a three-phase inverter for supplying three-phase AC power, the voltage and frequency of which are variable
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The synchronous motor driving apparatus (2) including position sensors (9) provided in the synchronous motor, a current polarity detection circuit (13) for detecting the polarities of the currents in the respective phase windings (8) of the synchronous motor, an inverter (3) driving the synchronous motor, a motor speed calculation unit (48) calculating the rotational speed (ωr) of the synchronous motor depending on the output signals from the position sensors (9), a speed control unit (47) outputting a first voltage adjusting component (q-axis current command value Iq*) to cause the rotational speed of the synchronous motor to approach a speed command value (ω*) and a phase control unit (45) outputting a second voltage adjusting component (d-axis current command value Id*) to cause the phase differences between the phases of the position sensor signals and of the currents in the respective phase windings of the synchronous motor to become a predetermined value.