H-Bridge Motor Controller Phase Delay for Reverse Current Control
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Solution Overview
Problem
Conventional motor controllers face issues with reverse flow of coil current due to inductor effects and inertia, leading to overvoltage and noise during phase switching, especially when transitioning between driving modes.
Innovation Solution
A motor controller with an H-bridge circuit and a phase delay mechanism that controls the switching of transistors to prevent reverse current flow by utilizing a counting unit to determine the duration of the phase delay, which can be either fixed or proportional to the previous phase duration, ensuring the coil current is fully released before phase changing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phase switching is performed quickly to improve response speed, then productivity is improved, but reverse current flow occurs causing overvoltage and noise
Solution Approach 1:
The patent applies preliminary action by introducing a phase delay mechanism that activates before the actual phase switching occurs. The counting unit counts clock cycles to determine when to delay the phase switching signal, ensuring that the coil current has time to release completely before the next phase begins. This preliminary timing control prevents reverse current flow and overvoltage while maintaining efficient operation.
2Object-affected harmful factors
If phase switching is delayed to prevent reverse current flow, then overvoltage and noise are reduced, but response time increases
Solution Approach 1:
The patent applies periodic action by using a clock signal to drive the counting unit, which creates a periodic timing mechanism. The phase delay is determined by counting a specific number of clock cycles, providing a precise and repeatable delay period. This ensures consistent current release timing while maintaining predictable phase switching intervals, balancing noise reduction with response time efficiency.
3Ease of operation
If enough energy is provided to overcome static friction for smooth motor start, then ease of operation is improved, but remaining coil current increases causing reverse flow risk
Solution Approach 1:
The patent applies feedback by using the Hall sensor to detect the rotor position and generate Hall signals that feed back to the control unit. The control unit uses this feedback information to determine when phase switching should occur and when to activate the phase delay mechanism. This closed-loop feedback ensures that phase switching is synchronized with the actual motor state, preventing reverse current flow while maintaining smooth operation.
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
The solution effectively reduces the risk of reverse coil current flow, preventing overvoltage and noise, and allows for smooth operation by transitioning through multiple driving modes to manage the coil current effectively.
Implementation Method 1
the current flows sequentially from the terminal VCC to the transistor 101, the motor coil L, and the transistor 104 for supplying the electric energy to the motor
Implementation Method 2
The Hall sensor 120 generates a Hall signal Vh to the control unit 110 for informing the control unit 110 to switch phases
Implementation Method 3
Since the coil current IL is still greater than 0 when changing modes, the inductor effect or the inertia motion will result that the coil current IL keeps flowing at the same direction
Data Source
AI summary
A motor controller is used for driving a motor, where the motor has a motor coil. The motor controller comprises a switch circuit, a control unit, and a phase detecting unit. The switch circuit is configured to supply a coil current to the motor coil. The control unit generates a plurality of control signals to control the switch circuit. The phase detecting unit generates a phase signal to the control unit. When the phase signal is changed from a first level to a second level, the motor controller starts a phase delay mechanism to reduce the risk of reverse flow of the coil current. The phase delay mechanism lasts a time. The motor controller may utilize the phase delay mechanism in a start mode or a normal operation mode.