Hybrid Motor Controller Rectangular Wave Noise Reduction
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Solution Overview
Problem
High-frequency noise occurs during vehicle operation when a motor is driven in rectangular wave control mode due to higher-order harmonic components, making it difficult to achieve quiet running despite selecting a motor running mode with a boost limit applied to the converter in hybrid vehicles.
Innovation Solution
A motor controller that switches the control mode from rectangular wave or overmodulation PWM to sinusoidal PWM by raising the output voltage of the converter above the boost limit value, thereby reducing current ripples and noise, especially during low-speed vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a motor is driven in rectangular wave control mode to improve fuel efficiency, then fuel efficiency is improved, but high-frequency noise increases due to higher-order harmonic components
Solution Approach 1:
The control unit dynamically changes the voltage parameter by raising the converter output voltage above the boost limit value when rectangular wave control is detected, thereby switching the motor control mode to sinusoidal PWM control. This parameter change eliminates higher-order harmonic components and current ripples, reducing high-frequency noise while maintaining fuel efficiency through controlled voltage adjustment.
2Use of energy by moving object
If a boost limit is applied to the converter output voltage to improve fuel efficiency, then fuel efficiency is improved, but the ability to restrict noise is compromised
Solution Approach 1:
The system dynamically adjusts the converter output voltage based on real-time detection of motor control modes. When rectangular wave control or overmodulation PWM control is detected, the control unit raises the voltage above the boost limit to switch to sinusoidal PWM control. This dynamic adjustment allows the system to adapt between fuel efficiency mode and noise restriction mode, resolving the contradiction between the two objectives.
Solution Approach 2:
The control unit continuously monitors the motor control mode and provides feedback to adjust the converter output voltage. When high-frequency noise-prone modes (rectangular wave or overmodulation PWM) are detected, the system responds by raising the voltage to switch to sinusoidal PWM control. This feedback mechanism ensures that noise restriction is automatically activated when needed, while maintaining fuel efficiency during normal operation.
3Object-affected harmful factors
If the converter output voltage is raised above the boost limit value to switch to sinusoidal PWM control, then high-frequency noise is reduced, but converter boost loss increases
Solution Approach 1:
Instead of permanently raising the converter output voltage above the boost limit, the system applies partial action by temporarily exceeding the limit only when rectangular wave control is detected. This selective voltage adjustment raises the voltage just enough to switch to sinusoidal PWM control, minimizing converter boost loss while achieving noise reduction. The action is excessive only when necessary, not continuously.
Data Source
AI summary
In a hybrid vehicle, noise occurrence caused in a rectangular wave control of a motor is restricted when a motor running mode is selected with a converter boosting limit applied. A motor controller for a hybrid vehicle mounted with an internal combustion engine and a motor as power sources is provided. The motor controller includes a converter capable of boosting a voltage supplied from a power supply device; an inverter which converts an output voltage of the converter to an AC voltage and applies the AC voltage to the motor; and a control unit which controls the inverter to drive the motor by switching between two or more control modes. When a running mode to drive the vehicle by a motor power alone is selected with a boost limit applied to the output voltage of the converter and when the motor is driven in a rectangular wave control mode or an overmodulation PWM control mode, the control unit raises the output voltage of the converter higher than a boost limit value and controls the inverter such that the control mode is switched to drive the motor in a sinusoidal PWM control mode.