Inverter Modulation Switching for Resolver Noise Reduction
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Solution Overview
Problem
The rotation detection signal of a resolver in rotating electrical machines is often disturbed by electric noise, particularly in three-phase modulation mode due to high-frequency noise and electromagnetic interference, leading to inaccurate control of the electric motor.
Innovation Solution
A control device that switches the modulation mode from three-phase to two-phase when electric noise is high, using a target torque, rotational speed, and rotation angle to manage the inverter control, thereby reducing noise interference and maintaining accurate drive control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If three-phase modulation mode is used to control the inverter, then the torque output and power efficiency are improved, but the electric noise generated by the rotating electrical machine increases and disturbs the rotation detection signal of the resolver
Solution Approach 1:
The patent applies dynamics by making the modulation mode adjustable and switchable between three-phase and two-phase modes based on operating conditions. The control device dynamically selects the appropriate modulation mode according to the rotational speed and torque requirements, allowing the system to adapt to different operating regions and minimize resolver signal disturbance while maintaining torque output efficiency.
Solution Approach 2:
The patent changes the modulation parameter from three-phase to two-phase modulation to reduce electric noise. By switching the modulation mode parameter, the system reduces the high-frequency switching noise that disturbs the resolver rotation detection signal, particularly in high-speed operating regions where the disturbance becomes significant.
2Reliability
If the modulation mode is switched from three-phase to two-phase to reduce electric noise, then the rotation detection signal stability is improved, but the power efficiency and torque output capability deteriorate
Solution Approach 1:
The patent applies local quality by applying different modulation modes to different operating regions. Two-phase modulation is used in high-speed regions where resolver signal stability is critical, while three-phase modulation is used in low-speed regions where torque output capability is more important. This localized application of different modulation qualities optimizes both signal stability and power efficiency in their respective operating ranges.
Solution Approach 2:
The system dynamically switches between modulation modes based on real-time operating conditions (rotational speed and torque requirements). The control device monitors the operating state and transitions between three-phase and two-phase modulation modes to maintain both signal stability and power efficiency according to the specific operational context.
3Measurement precision
If three-phase PWM switching is performed to achieve precise torque control, then the torque precision is improved, but the switching loss in electric power increases
Solution Approach 1:
The patent changes the modulation parameter from three-phase PWM to two-phase modulation to reduce switching losses. By reducing the number of switching operations from six (three phases × two switches per phase) to fewer transitions, the system decreases the cumulative switching losses while maintaining adequate torque control precision through appropriate control strategies.
Solution Approach 2:
The patent applies partial action by using two-phase modulation instead of full three-phase modulation in certain operating regions. This partial modulation approach reduces the switching frequency and switching loss while providing sufficient torque control precision for the given operating conditions, particularly in high-speed regions where maximum torque precision is less critical.
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 reduces the disturbance of the rotation detection signal, enhancing the reliability of the drive control of rotating electrical machines by minimizing noise interference and maintaining accurate torque output.
Implementation Method 1
In the resolver, a rotor having a winding that is excited by a high frequency current is driven to rotate by the electric motor, and a voltage induced in a stator winding and having an excited current frequency is increased/decreased (modulated) by the rotation of the rotor.
Implementation Method 2
This is passed through a high-pass filter (demodulated) to output a sine wave (or a cosine wave) showing the rotation of the rotor as a rotation detection signal showing the rotation angle and the rotational speed of the electric motor.
Data Source
AI summary
A rotating electrical machine control device includes an inverter; a resolver; a unit; a three-phase/two-phase modulation switching unit; and a motor control unit that switches to a two-phase modulation in a specific region where an electric noise given to the resolver by a rotating electrical machine is large, even in a region where the modulation ratio is smaller than the three-phase/two-phase modulation switching boundary.