Rotary Electric Machine Rotation Frequency Detection
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Solution Overview
Problem
The accuracy of rotation frequency detection in rotary electric machines for vehicles decreases with fluctuations in power generation voltage, leading to erroneous frequency calculations due to shifts in the point at which the phase voltage exceeds a predetermined threshold value.
Innovation Solution
Incorporating an armature winding with a switching section and an ON-timing/OFF-timing setting mechanism, along with an energization period detector and rotation frequency calculator, which uses the cycle of the start and end timings of the energization period to calculate rotation frequency, thereby improving accuracy and simplifying synchronization control without requiring separate frequency detection components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rotation frequency detection is performed based on the time difference between points at which phase voltages exceed a predetermined threshold value, then the detection method is simple, but the accuracy of rotation frequency detection decreases when power generation voltage fluctuates
Solution Approach 1:
The patent changes the detection parameter from fixed threshold voltage comparison to measuring the energization period of the diode. By detecting the duration during which current flows through the diode connected in parallel with the switching element, the system obtains a measurement that is independent of voltage fluctuations, thereby resolving the contradiction between simple detection and accurate measurement.
2Device complexity
If the point at which phase voltage exceeds threshold value is used for frequency detection, then the detection process is straightforward, but erroneous frequency calculation occurs when power generation voltage changes
Solution Approach 1:
The patent introduces the diode energization period as an intermediary measurement parameter. Instead of directly measuring phase voltage threshold crossing points, the system measures the period during which the diode conducts current. This intermediary measurement provides a reliable basis for frequency calculation that is not affected by voltage fluctuations, maintaining both simplicity and reliability.
3Measurement precision
If separate frequency detection components are used to improve accuracy, then rotation frequency detection accuracy improves, but device complexity and processing load increase
Solution Approach 1:
The patent makes the existing switching elements and diodes serve dual functions: both power rectification and rotation frequency detection. The same diode that performs rectification also provides the energization period signal for frequency measurement. This eliminates the need for separate frequency detection components, achieving high accuracy without increasing device complexity or processing load.
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 enhances the accuracy of rotation frequency calculation and stabilizes the frequency setting even under sudden electrical load fluctuations, reducing processing load and improving power generation efficiency by using the detected energization periods for synchronization control.
Implementation Method 1
an armature winding (2, 3) having phase windings of two phases or more
Implementation Method 2
a switching section that configures a bridge circuit having a plurality of upper arms and lower arms configured by switching elements to which a diode is connected in parallel
Data Source
AI summary
In a vehicular rotary electric machine, a switching section includes a bridge circuit having plurality of upper arms and plurality of lower arms. The arms include switching elements. A diode is connected in parallel to each switching element. One end of the switching element of each of the upper arms is connected to a positive terminal of a battery and one end of the switching element of each of the lower arms is connected to a negative terminal of the battery via a vehicle body. The switching section rectifies induced phase voltage of an armature winding. A section sets ON-timing of the switching elements. A section sets OFF-timing of the switching elements. When the switching element of each lower arm is OFF, a detector detects an energization period in which current flows to the diode. A calculator calculates a rotation frequency based on the detected energization period.