Inverter Control Device Segmentation for Cost Reduction
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Solution Overview
Problem
The existing inverter control devices require high-performance microcomputers for high-speed calculations, leading to increased manufacturing costs due to the need for frequent updates of voltage command values at ¼ period of the carrier frequency.
Innovation Solution
An inverter control device with a current control unit that calculates voltage commands at predetermined calculation periods and a sampling period conversion unit that outputs voltage command signals at different update periods, allowing for gate signal generation without the need for high-speed microcomputer capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the voltage command value is updated at 1/4 period of the carrier frequency to improve control characteristics, then the control precision is improved, but the manufacturing cost increases due to the need for high-performance microcomputers
Solution Approach 1:
The patent divides the voltage command value update process into two distinct functional units: a current control unit that calculates voltage command values at a lower frequency, and a sampling period conversion unit that converts these values to the higher update frequency required for precise control. This segmentation allows the system to achieve high-precision control characteristics without requiring the entire control system to operate at high speed, thereby reducing the performance requirements and cost of the microcomputer.
Solution Approach 2:
The sampling period conversion unit acts as an intermediary between the current control unit and the gate signal generation unit. It receives voltage command values calculated at a lower frequency from the current control unit and converts them to the higher update frequency needed by the gate signal generation unit. This intermediary component enables the system to achieve high-frequency control output without requiring the main control processor to operate at high frequency, thus reducing manufacturing costs while maintaining control precision.
2Speed
If high-speed calculation is implemented to update voltage command values frequently, then the control response speed is improved, but the device complexity increases due to the need for high-performance microcomputers
Solution Approach 1:
The control system is segmented into two functional units with different operating frequencies: the current control unit operates at a lower frequency for calculation, while the sampling period conversion unit converts these results to the higher frequency required for rapid control response. This segmentation enables fast control response without requiring the entire control device to be complex and high-performance.
Solution Approach 2:
The sampling period conversion unit effectively creates multiple copies of the voltage command value at different time instances by interpolating between calculated values. This copying approach allows the system to generate high-frequency control signals from lower-frequency calculations, improving response speed without increasing the computational complexity of the main control unit.
Data Source
AI summary
To improve control characteristics of an inverter while suppressing manufacturing cost. An inverter control device 10 is a device for controlling an inverter device 1 having a plurality of switching elements. The inverter control device 10 includes a current control unit 13 that calculates three phase voltage command signals Vu*, Vv*, and Vw* based on a d-axis current command signal id* and a q-axis current command signal iq* at each predetermined calculation period T0, a sampling period conversion unit 14 that outputs three phase voltage command signals Vu**, Vv**, and Vw** after update at each predetermined update period T1 different from the calculation period T0 based on a calculation result of the three phase voltage command signals Vu*, Vv*, and Vw* by the current control unit 13, and a gate signal generation unit 15 that generates a gate signal for switching-driving a plurality of the switching elements based on the three phase voltage command signals Vu**, Vv**, and Vw** after update output from the sampling period conversion unit 14.