Motor Control Circuit Braking to Prevent Voltage Rise
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Solution Overview
Problem
The existing motor drive control apparatuses face issues with abnormal states and potential circuit damage when using the free-run stop method, as the motor can act as a power generator during unintended rotations, leading to increased power supply voltage and potential breakdowns.
Innovation Solution
A motor control circuit that includes a speed control circuit, a drive signal generation circuit, and a drive stop control circuit, which outputs specific control signals for braking or free-run stop based on rotational speed and command information, allowing for controlled deceleration and transition to a stable stop state, preventing power generation and regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the free-run stop method is used to stop the motor, then the motor can be stopped by turning off all phases, but the motor functions as a power generator when the rotor rotates due to external factors, causing the power supply voltage to rise and potentially damaging circuit parts
Solution Approach 1:
The control circuit detects when the motor is in a free-run stop state and the rotational speed exceeds a threshold, then actively applies braking control to counteract the unintended rotation. This preliminary anti-action prevents the power generation effect before it can damage circuit parts, resolving the contradiction between easy stop operation and circuit reliability.
Solution Approach 2:
The system continuously monitors the rotational speed of the motor during free-run stop and provides feedback to the control circuit. When the speed exceeds a predetermined threshold, the feedback triggers braking control to prevent power supply voltage rise, thus protecting circuit parts while maintaining the simplicity of the stop operation.
2Device complexity
If the motor is stopped using the free-run stop method with all phases turned off, then the stop operation is simple, but when the rotor is rotating, a regenerating state occurs where current flows to the motor drive control apparatus side, causing the power supply voltage to rise
Solution Approach 1:
The control circuit is configured to detect the free-run stop state and monitor rotational speed in advance. When the rotor speed exceeds a threshold, the system proactively switches from free-run stop to braking control, preventing the regenerating state and associated power supply voltage rise before they occur, thus eliminating harmful effects while keeping the control structure simple.
Solution Approach 2:
The system dynamically switches between free-run stop mode and braking control mode based on real-time rotational speed conditions. This dynamic adaptation allows the motor to use the simpler free-run stop method when appropriate while automatically applying braking when needed to prevent power supply voltage rise, resolving the contradiction between device complexity and harmful factor generation.
3Use of energy by moving object
If the motor functions as a power generator during unintended rotation, then the inductive voltage is generated, but this causes the power supply voltage to rise which may cause abnormal operation or breakage of circuit parts
Solution Approach 1:
The system detects when the motor inadvertently functions as a power generator during free-run stop and converts this potentially harmful situation into a controlled braking operation. By detecting the rotational speed and switching to braking control, the system prevents the harmful power supply voltage rise while utilizing the motor's electromagnetic characteristics in a controlled manner, thus eliminating circuit part abnormalities.
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 effectively prevents abnormal states and circuit damage by ensuring controlled braking and deceleration, maintaining a stable power supply voltage and preventing rotor rotation due to external forces, thus ensuring reliable motor stoppage without vibration or backlash.
Implementation Method 1
When a motor is stopped by a free-run stop method (when a rotor of the motor is in a rotation stop state), the motor functions as a power generator if the rotor is rotated. That is, if the rotor rotates, an inductive voltage is generated, and a power supply voltage of the motor drive control apparatus rises.
Data Source
AI summary
A motor control circuit comprising a speed control circuit configured to output speed command information relating to the rotational speed of a motor based on target information relating to a target rotational speed and rotational speed detection information of the rotational speed of the motor, a drive stop control circuit configured to output a first drive stop control signal for performing braking control of the motor or a second drive stop control signal for performing free-run stop control of the motor based on the rotational speed detection information and the speed command information when input of the target information is stopped, and a drive signal generation circuit configured to generate a drive control signal for driving the motor based on the first drive stop control signal or the second drive stop control signal when the first drive stop control signal or the second drive stop control signal is output.