Power Converter Current Sensor Error Compensation
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Solution Overview
Problem
Current current controlled power converters face challenges in accurately detecting and compensating for amplitude, offset, and temperature drift of current sensors on the ac side, leading to increased costs due to the need for high-accuracy sensors.
Innovation Solution
The implementation of a current controlled power converter using pulse-width modulation with spatial vector modulation, where the dc side current detection components are used to correct amplitude and offset errors of ac side current sensors, allowing for the use of inexpensive sensors and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a DCCT is provided on the ac side to detect the dc component, then measurement precision is improved, but device complexity and cost increase due to requiring high-accuracy sensors with amplitude, offset and temperature drift compensation
Solution Approach 1:
The patent uses the dc side current as an intermediary to indirectly detect and compensate for ac side current sensor errors. Instead of directly measuring ac side current with a complex DCCT, the system measures dc side current which contains reflected ripple information, then uses this information to compensate for sensor amplitude, offset and temperature drift errors in the ac side current control
Solution Approach 2:
The patent creates a copy of the current detection function by using dc side current measurement to represent and compensate for ac side current sensor characteristics. The dc side current serves as a proxy that contains the necessary information to correct ac side sensor errors, eliminating the need for expensive DCCT hardware on the ac side
2Measurement precision
If a DCCT with high accuracy is employed to compensate amplitude, offset and temperature drift, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent replaces expensive, high-precision DCCT sensors with inexpensive standard current sensors on the dc side. By using affordable sensors combined with software-based compensation algorithms that utilize dc side current measurements, the system achieves high measurement precision without the high manufacturing cost of precision hardware
Solution Approach 2:
The patent changes the measurement location from ac side to dc side, where current parameters can be measured with standard sensors. The dc side current contains reflected ripple information that, when processed through coordinate transformation and compensation algorithms, provides accurate ac side current information at lower cost
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A power module 3 that converts a dc voltage into a three-phase ac voltage, current sensors 1 and 2 that detect the ac side current of the power module 3, a shunt resistor 7 and an amplifier 6 that detect a dc side current of the power module 3, and a control section 11A that controls the power module 3 by pulse-width modulation using a spatial vector modulation method on the basis of the ac side current detected by the current sensors 1 and 2 and the dc side current detected by the shunt resistor and the amplifier are provided. The control section corrects the amplitude and the offset of the ac side current detected by the current sensors on the basis of current components, corresponding to current components of prescribed phases of the ac side current, of the dc side current detected by the shunt resistor and the amplifier.