Inverter Control Offset for Motor Efficiency Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The efficiency of inverters used in motor control systems declines significantly when switching to a second control line due to high current amplitude settings, which are necessary to maintain voltage sufficiency, leading to instability and reduced performance.
Innovation Solution
A motor controlling apparatus comprising an inverter, voltage detector, rotational speed detector, command value calculator, inverter controller, state detector, and offset component, which calculates and adjusts current command values based on detected voltage and rotational speed to stabilize the inverter operation, thereby mitigating efficiency decline by offsetting voltage or rotational speed according to the control state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amplitude of current is set high in the second control line to maintain adequate margin with respect to voltage insufficiency, then the stability of inverter control is improved, but the efficiency of the inverter greatly declines
Solution Approach 1:
The patent applies dynamics by making the control line selection dynamic rather than static. The controller automatically switches between the first control line (optimized for efficiency) and the second control line (optimized for stability) based on real-time detection of inverter control stability and voltage conditions. This dynamic adaptation allows the system to achieve both stability and efficiency under different operating conditions without permanently sacrificing inverter efficiency through high current amplitude settings.
Solution Approach 2:
The patent changes the control parameters by introducing an offset component that adjusts voltage or rotational speed parameters based on the detected control state. When switching to the second control line, the offset component modifies the command values to reduce the excessive current amplitude, thereby mitigating the efficiency decline while maintaining adequate voltage margin through parameter adjustment rather than relying solely on high current settings.
2Reliability
If the amplitude of current is set high to maintain voltage sufficiency margin, then the margin with respect to voltage insufficiency is improved, but the efficiency of the inverter greatly declines
Solution Approach 1:
The system dynamically adjusts the current amplitude based on actual voltage conditions and control state rather than maintaining a permanently high current setting. The controller detects whether voltage insufficiency is actually occurring and only activates the second control line with higher current amplitude when necessary, otherwise operating with the more efficient first control line.
Solution Approach 2:
The offset component modifies voltage or rotational speed parameters to achieve adequate voltage margin without requiring excessively high current amplitude. By adjusting these parameters, the system maintains the necessary voltage sufficiency margin while operating at lower, more efficient current levels.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A motor controlling apparatus including an inverter (6), a voltage detector (14), a rotational speed detector (11), a command value calculating component (1), an inverter controller (4), a state detector (131, 132, 133, 134) and an offsetting component (135). The inverter (6) converts direct-current power to alternating-current power supplied to a motor (8). The voltage detector (14) detects a direct-current voltage, and the rotational speed detector (11) detects a rotational speed of the motor (8). The calculating component (1) calculates current and torque command values, and motor rotational speed. The controller (4) provides a control signal to control the inverter (6) based on the current command value. The state detector (131, 132, 133, 134) detects a control state of the inverter (6), and the offsetting component (135) offsets the detected voltage or rotational speed by an offset amount. The calculating component (1) modifies the current command value based on the offset detected voltage or rotational speed to increase on a negative side a d-axis current command value included in the current command value.