Three-Phase Motor Drive Control With Two Magnetic Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high cost of magnetic sensors and the need for a waterproof structure increase costs when multiple sensors are used, necessitating a reduction in their number for three-phase rotating electric machines.
Innovation Solution
A drive device for a three-phase rotating electric machine that uses four energization patterns controlled by a control part, with two magnetic sensors to determine the energization timing of the U-phase, V-phase, and W-phase windings, allowing for reduced sensor usage by estimating the energization timing of the W-phase based on the outputs of the U-phase and V-phase sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three magnetic sensors are used to determine three-phase energization timing, then the accuracy of energization timing detection is improved, but the cost of magnetic sensors and filler increases
Solution Approach 1:
The patent extracts the W-phase sensor from the three-sensor system and replaces it with estimation based on the relationship between phase currents and back-EMF. The control unit calculates the W-phase back-EMF using the measured U-phase and V-phase currents, thereby eliminating the need for the third physical sensor while maintaining detection accuracy
Solution Approach 2:
The patent creates a virtual copy of the W-phase sensor output by calculating the back-EMF from the measured phase currents. The control unit generates an estimated W-phase signal that replicates what a physical sensor would detect, allowing the system to function with only two physical sensors
2Reliability
If three magnetic sensors are used for accurate phase detection, then the reliability of motor control is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces the mechanical/sensor-based detection system with a computational approach. Instead of using three physical magnetic sensors to detect phase positions, the system uses mathematical calculations based on measured currents and known motor parameters to determine energization timing, thereby reducing hardware complexity while maintaining control reliability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the number of magnetic sensors required, minimizing costs while maintaining effective operation of the three-phase rotating electric machine by accurately determining energization timings using fewer sensors.
Implementation Method 1
two magnetic sensors to detecting magnetic flux of a plurality of magnets having N poles and S poles
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention reduces the number of magnetic sensors. This drive device for a three-phase rotating electric machine is mounted on a vehicle and provided with: a plurality of switching elements for energizing the three-phase windings of the three-phase rotating electric machine by performing switching operations; and a control unit for controlling the switching operations of the plurality of switching elements. The control unit performs a first control for controlling the switching operations using four energization patterns indicating the ON-state or the OFF-state of the plurality of switching elements, thereby driving the three-phase rotating electric machine.