Adaptive Two-Phase Short-Circuit Brake for Brushless Motor
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Solution Overview
Problem
Variations in detection signal intervals from a rotation sensor in three-phase brushless motors can lead to improper execution of two-phase short-circuit brake control, causing failures in electric working machines due to uneven delay times set in the timer.
Innovation Solution
An electric working machine configuration that includes a three-phase brushless motor, switching elements, and a brake controller, which generates detection signals every specific angle and adjusts switching times based on these signals to ensure proper two-phase short-circuit brake execution, even with variations in signal intervals, by using a timer to set and adjust delay times dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotation sensor with Hall elements arranged at 120-degree intervals is used for two-phase short-circuit brake control, then the brake control can be executed based on detection signals, but variations in detection signal intervals occur due to Hall element position deviations, leading to improper brake control execution
Solution Approach 1:
The patent applies dynamics by making the delay time adjustable and adaptive rather than fixed. The brake control device dynamically adjusts the delay time based on the actual interval between detection signals, allowing the system to adapt to variations in signal timing caused by Hall element position deviations. This dynamic adjustment ensures reliable brake control execution despite measurement variations.
Solution Approach 2:
The patent changes the parameter of delay time from a fixed value to a variable that can be adjusted based on detection signal intervals. By monitoring the actual interval between detection signals and adjusting the delay time accordingly, the system compensates for variations in signal timing. This parameter change allows the brake control to maintain proper timing accuracy despite Hall element position deviations.
2Ease of operation
If a fixed delay time is set in the timer based on nominal detection signal intervals, then the brake control timing can be determined, but variations in actual detection signal intervals cause the delay time to be inaccurate, resulting in failure to execute brake control properly
Solution Approach 1:
The patent implements feedback by measuring the actual interval between detection signals and using this measured value to adjust the delay time. The brake control device continuously monitors the timing of detection signals and adjusts the delay time parameter based on this feedback. This closed-loop approach ensures that the brake control timing remains accurate despite variations in detection signal intervals caused by Hall element position deviations.
Solution Approach 2:
The patent applies preliminary action by adjusting the delay time parameter before executing the brake control based on the measured detection signal interval. By pre-calculating and setting the appropriate delay time according to the actual signal timing, the system ensures that the brake control will be executed at the correct moment. This preliminary adjustment prevents timing errors from affecting the brake control execution.
3Manufacturing precision
If Hall elements are positioned at exact 120-degree intervals, then detection signals change at regular intervals, but manufacturing tolerances cause position deviations, leading to variations in detection signal change time periods
Solution Approach 1:
The patent applies self-service by having the brake control device automatically measure and adjust the delay time based on the actual detection signal intervals without requiring external calibration or manual intervention. The system uses its own detection signals to determine the appropriate timing parameters, compensating for manufacturing variations in Hall element positions. This self-adjusting mechanism eliminates the need for high manufacturing precision while maintaining control accuracy.
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 configuration effectively inhibits failures in two-phase short-circuit brake control by ensuring that switching elements are activated or deactivated at the correct times, maintaining consistent braking force despite variations in detection signal intervals, thus ensuring reliable operation of the three-phase brushless motor.
Implementation Method 1
a three-phase brushless motor (5) serving as a driving source
Implementation Method 2
a rotation sensor that provides detection signals (Hall signals shown in FIG. 7)
Data Source
AI summary
In one aspect of the present disclosure, an electric working machine includes a three-phase brushless motor, a first switching element, a second switching element, a third switching element, a fourth switching element, a fifth switching element, a sixth switching element, a rotation detector, a brake controller. The brake controller executes a two-phase short-circuit brake. The two-phase short-circuit brake is executed so as to switch any of the fourth switching element, the fifth switching element, and the sixth switching element to a corresponding ON-state or an OFF-state in response a detection signal from the rotation detector that occurs prior to a switching time.