Inverter Controller With Independent Voltage And Frequency Control
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Solution Overview
Problem
Existing inverter control modes, such as V/Hz and vector control, are not well-suited for driving non-motor loads that require variable voltage at fixed frequency or variable frequency at fixed voltage, limiting their applicability in applications like linear motors, induction heaters, and resistive loads.
Innovation Solution
An adjustable voltage/adjustable frequency inverter controller that independently controls output voltage and frequency, allowing for optimized AC waveforms to be generated and delivered to specific loads, with a single drive configuration capable of operating in various modes, including V/Hz, vector control, and adjustable voltage/adjustable frequency modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If V/Hz or vector control modes are used, then motor control performance is improved, but applicability to non-motor loads is limited
Solution Approach 1:
The inverter controller is designed to support multiple control modes (V/Hz, vector control, and independent voltage/frequency control) within a single device, enabling it to serve both motor loads and non-motor loads effectively. The controller includes separate voltage controller and frequency controller modules that can be configured for different operating modes based on load requirements.
2Manufacturing precision
If constant voltage/frequency ratio is maintained, then V/Hz linearity is improved, but independent voltage and frequency control is lost
Solution Approach 1:
The controller dynamically adjusts the relationship between voltage and frequency control based on operating mode. During normal operation, it maintains the traditional coupled V/Hz relationship for motor applications. During overmodulation conditions, it dynamically decouples the control to allow independent voltage and frequency adjustment, enabling adaptation to non-motor loads while preserving motor control performance when needed.
Data Source
AI summary
An apparatus and method for controlling an inverter, the apparatus including an adjustable frequency controller receiving a reference frequency value and generating a command frequency value as a function thereof, an adjustable voltage controller receiving a reference voltage value and generating a command voltage value as a function thereof and independent of the command frequency and a modulator receiving the command frequency value and the command voltage value and generating pulse width modulated (PWM) inverter control signals as a function thereof.