Motor Inverter PWM Switching for Low-Loss Torque Control
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Solution Overview
Problem
Existing motor control technologies face challenges in achieving precise control with minimized losses, as flat PWM schemes cause significant disturbances and current ripples, while normal PWM schemes result in permanent switching losses, degrading efficiency.
Innovation Solution
A motor control processing unit that dynamically switches between flat PWM and normal PWM schemes based on operating conditions, such as torque, velocity, and temperature, to optimize efficiency and precision, using duty cycle adjustments and considering inverter characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If flat PWM scheme is used, then switching losses are reduced, but current ripples and torque disturbances increase
Solution Approach 1:
The system dynamically switches between flat PWM and normal PWM schemes based on operating conditions. A switching criterion evaluates parameters such as torque demand, speed, and temperature to determine when to transition between PWM modes, allowing the system to adapt to varying operational requirements and optimize both efficiency and precision.
Solution Approach 2:
The invention modifies the PWM scheme parameters (duty cycle calculations, switching timing) based on inverter characteristics and operating conditions. By adjusting these parameters dynamically, the system can minimize current ripples and torque disturbances while maintaining the efficiency benefits of flat PWM when appropriate.
2Manufacturing precision
If normal PWM scheme is used, then torque precision is maintained, but switching losses increase permanently
Solution Approach 1:
The system transitions from static PWM scheme selection to dynamic switching between flat PWM and normal PWM based on real-time operating conditions. This allows the system to use normal PWM only when necessary for precision, rather than permanently, thereby reducing overall switching losses while maintaining torque precision when needed.
Solution Approach 2:
The control system periodically evaluates switching criteria and transitions between PWM schemes at appropriate moments in the operating cycle. This periodic assessment allows the system to optimize the balance between precision and efficiency across different phases of motor operation.
3Loss of energy
If flat PWM is applied continuously, then efficiency improves, but thermal issues arise during high precision requirements
Solution Approach 1:
The system incorporates feedback mechanisms that monitor operating conditions including temperature, torque demand, and speed. Based on this feedback, the control algorithm determines when to switch between flat PWM and normal PWM schemes, ensuring thermal management requirements are met while maintaining efficiency during appropriate operating phases.
Data Source
AI summary
The invention relates to a motor control processing unit for a motor control device which comprises a voltage source inverter unit, configured to control the voltage source inverter unit to provide a motor voltage following a pulse-width modulation, PWM, scheme, wherein the motor control processing unit is configured to control the voltage source inverter unit according to a flat PWM scheme, which comprises a flat-bottom or flat-top PWM scheme, at least at some times in order to provide a precise motor control with minimized losses. The invention also relates to a corresponding method.