Inverter Controller Compensation Voltage Stability
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Solution Overview
Problem
Conventional inverter control methods fail to stably operate when a large starting torque is required or when there is a significant change in load due to dependency on motor parameters, leading to errors in torque compensation voltage.
Innovation Solution
A controller for the inverter that includes a second conversion unit for converting voltage commands to a stationary reference frame, a modulation unit for motor rating compliance, a PWM signal generation unit, and a compensation voltage generation unit that uses slip frequency and motor capacity information to generate a stable compensation voltage, independent of motor parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage/frequency control method is used, then the inverter can operate at base frequency, but the operation fails when large starting torque is required or when there is large load change
Solution Approach 1:
The patent implements dynamic voltage compensation by continuously monitoring motor speed and calculating compensation voltage based on actual operating conditions. The compensation voltage is dynamically adjusted according to motor speed feedback, allowing the system to adapt to varying load conditions and starting torque requirements, thereby resolving the contradiction between operational stability and adaptability.
2Force
If torque boost compensation is applied, then starting torque is improved, but errors occur due to dependency on motor parameters (stator resistance, stator inductance, no-load current)
Solution Approach 1:
The patent employs feedback control by measuring actual motor speed and using it to calculate compensation voltage. The compensation voltage is determined based on the difference between commanded speed and actual speed, along with motor capacity information. This feedback mechanism eliminates dependency on inaccurate motor parameters like stator resistance and inductance, thereby improving both starting torque and compensation accuracy simultaneously.
3Ease of operation
If voltage command is generated from frequency command, then the control follows predetermined voltage/frequency ratio, but the control cannot respond to large load changes
Solution Approach 1:
The patent introduces compensation voltage as an intermediary element between the basic voltage/frequency control and the motor. This compensation voltage, calculated based on motor speed feedback and motor capacity information, acts as a mediator that enhances the system's response to load changes while maintaining the simplicity of predetermined voltage/frequency ratio control. The intermediary compensation voltage bridges the gap between simple control and adaptive response.
Data Source
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AI summary
An inverter controller is provided. The controller according to an exemplary embodiment of the present disclosure generates a compensation voltage to compensate an inverter command voltage using motor torque current and motor information, and apply the compensation voltage to the command voltage.