Inverter Control Stabilizing Output Voltage Against DC Input Variations
Solution Overview
Problem
Existing inverter control systems face instability in AC output voltage when DC input voltage varies, leading to issues such as insufficient start torque and overcurrent trips, requiring frequent re-setting of boost voltage values.
Innovation Solution
An inverter control apparatus with an input voltage detector, output voltage ratio computing unit, reference voltage generator, and compensation voltage computing unit that automatically adjusts the output voltage by calculating a difference between the reference voltage and input voltage, allowing for stable AC output voltage delivery to motors regardless of DC input voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed boost voltage value is set to compensate for input voltage variations, then the inverter can operate under certain voltage conditions, but the output voltage becomes unstable when input voltage changes significantly, requiring frequent re-setting of boost voltage
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed boost voltage setting to a dynamic compensation mechanism. The compensation voltage computing unit continuously calculates the required boost voltage based on real-time detection of input voltage variations and the predetermined voltage ratio, allowing the system to adapt to changing operating conditions without manual intervention.
Solution Approach 2:
The patent implements feedback by using the input voltage detector to monitor actual input voltage conditions and feeding this information back to the compensation voltage computing unit. This closed-loop approach enables the system to automatically adjust the compensation voltage based on detected deviations from expected operating conditions.
2Stability of the object's composition
If manual re-setting of boost voltage is performed to adapt to changing input voltage conditions, then output voltage stability can be maintained, but system complexity and operation time increase
Solution Approach 1:
The patent applies self-service by enabling the inverter control system to automatically compensate for input voltage variations without requiring manual intervention. The compensation voltage computing unit autonomously calculates and applies the necessary boost voltage based on detected input conditions and the predetermined voltage ratio, eliminating the need for operators to manually re-set parameters.
Solution Approach 2:
The patent implements preliminary action by pre-storing the voltage ratio between input and output voltages in the compensation voltage computing unit. This predetermined parameter is prepared in advance to enable rapid automatic compensation when input voltage variations occur, eliminating the need for manual calculation and adjustment during operation.
3Device complexity
If the inverter uses a simple fixed voltage compensation method, then device complexity is reduced, but the system cannot adapt to significant input voltage variations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the compensation voltage parameter based on detected input voltage conditions. Rather than using a fixed compensation value, the system modifies the compensation voltage in real-time according to the actual input voltage and the predetermined voltage ratio, enabling adaptation to a wide range of input conditions.
Data Source
AI summary
An apparatus and method for controlling an inverter are disclosed to allow an inverter to provide a stable output voltage to a motor regardless of a change in a DC input voltage. A difference value between a reference voltage according to a predetermined rated voltage of a motor and a DC voltage of the inverter is obtained, a ratio of an output command frequency to a predetermined reference frequency is applied to the difference value to obtain a compensation output voltage value, a final compensation output voltage value is obtained by compensating the detected DC input voltage value with the compensation output voltage, and an output voltage of the final compensation output voltage value to the motor by the inverter. Thus, the stable output voltage of the inverter can be provided to the motor regardless of the change in the input voltage.