Motor Controller Flyback Pulse Management
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Solution Overview
Problem
Existing motor controllers face challenges in reducing power dissipation during flyback pulses in stepping motors, leading to heat generation and operational limitations due to parasitic transistor effects, and existing solutions increase manufacturing costs and complexity.
Innovation Solution
A motor controller with an H-bridge circuit, current detector, and zero-cross detector that operates in charge, high-dissipation, low-dissipation, and free modes to manage flyback pulses, allowing current to return to the power source and minimizing energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If all switching elements are turned off when the motor is rotated, then the flyback pulse is induced to return current to power source, but power dissipation occurs due to parasitic transistor effect in CMOS process
Solution Approach 1:
The patent extracts the harmful parasitic transistor effect from the CMOS process by using a BIPOR process for the ASIC. This process substitution eliminates the parasitic transistors that cause power dissipation and heat generation during flyback pulse induction, while maintaining the desired energy return to power source function.
Solution Approach 2:
The patent changes the manufacturing process parameter from CMOS to BIPOR for the ASIC. This parameter change fundamentally alters the electrical characteristics of the circuit, eliminating the parasitic transistor effect that causes power dissipation during switching operations, particularly when inducing flyback pulses.
2Loss of energy
If communication control time is extended to capture full flyback pulse, then power dissipation is reduced, but motor speed control precision deteriorates due to inductive load short-circuiting
Solution Approach 1:
The patent implements dynamic switching element control where the timing and state of switching elements are continuously adjusted based on real-time detection of flyback pulse characteristics. This dynamic control allows the system to optimize the balance between capturing flyback energy and maintaining motor speed control precision by adapting to varying operating conditions.
Solution Approach 2:
The patent employs feedback mechanisms to detect flyback pulse characteristics and adjust switching element operations accordingly. This feedback control enables precise timing of switching element turn-off, ensuring that communication control captures sufficient flyback energy while preventing excessive duration that would short-circuit the inductive load and degrade speed control precision.
3Manufacturing precision
If communication control time is shortened, then motor speed control precision is maintained, but power dissipation increases due to current discharge through fly-wheel diode
Solution Approach 1:
The patent uses dynamic control of switching element timing to optimize the communication control duration. By continuously adjusting the switch-off timing based on detected flyback pulse characteristics, the system achieves the minimum necessary control time to maintain speed precision while maximizing energy capture, preventing excessive power dissipation through the fly-wheel diode.
Solution Approach 2:
The feedback detection of flyback pulse characteristics enables the system to determine the optimal communication control duration. This feedback mechanism ensures that switching elements are turned off at the precise moment that captures sufficient flyback energy while maintaining motor speed control precision, thereby minimizing power dissipation through the fly-wheel diode.
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 power dissipation, prevents heat generation, and maintains motor control precision without increasing manufacturing costs or complexity.
Implementation Method 1
If switching elements provided on opposite sides of the coils, namely, a motor supply voltage side (high side) and a ground side (low side) are simultaneously turned off when the motor is rotated, a high voltage of flyback pulse (kick back) is induced by energy reserved in the coils.
Implementation Method 2
a current detector that detects motor current flowing in the motor coil
Implementation Method 3
a zero-cross detector that detects a zero-cross of a back electromotive force voltage of each of the motor coils
Data Source
AI summary
A controller of a motor controller operates to perform a process including: controlling the H bridge circuit to switch to the charge mode; controlling the H bridge circuit to switch to the high-dissipation mode when the zero-cross detector detects that the back electromotive force voltage of the motor coil connected to a phase of the H bridge circuit shortly before the H bridge circuit is zero-crossed; controlling the H bridge circuit to switch to the low-dissipation mode after a predetermined time has elapsed; and controlling the H bridge circuit to switch to the free mode when the motor current detector detects that the motor current flowing in the motor coil connected to the H bridge circuit flows in a direction opposite to that in the charge mode.