Stepper Motor Controller With Individual And Common PWM Drivers
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Solution Overview
Problem
Stepper motor controllers face challenges in reducing the number of power transistors and external terminals while maintaining resolution requirements for incremental armature rotation, as current designs often require multiple drivers and a common driver, leading to increased size and complexity.
Innovation Solution
The implementation of a stepper motor controller with individual and common driver pulse width modulation circuitry, where individual drivers and a common driver supply pulse width modulated currents to stepper motor field coils, allowing for reduced transistor and terminal count through the use of H-bridge configurations and selective duty cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple individual drivers and a common driver are used to control stepper motor field coils, then the resolution requirements for incremental armature rotation (full steps, partial steps, micro steps) are maintained, but the number of power transistors and external terminals increases, leading to larger semiconductor package size
Solution Approach 1:
The patent combines multiple individual drivers with a common driver into a single semiconductor package, merging their functions to control multiple field coils simultaneously. This integration reduces the overall number of discrete components and external terminals while maintaining the resolution requirements for incremental armature rotation through coordinated pulse width modulation of all drivers
Solution Approach 2:
The common driver serves multiple field coils simultaneously, performing a universal function that replaces what would otherwise require separate individual drivers for each coil. This multi-functionality reduces the total number of drivers needed while maintaining full control capability for resolution requirements across all field coils
2Area of stationary object
If the number of power transistors and external terminals is reduced to decrease semiconductor package size, then the package becomes more compact, but the capability to maintain resolution requirements for incremental armature rotation may be compromised
Solution Approach 1:
The control system is segmented into individual drivers for precise control of specific field coils and a common driver for shared control functions. This segmentation allows the system to reduce overall component count while maintaining resolution requirements through coordinated operation of the segmented driver components
Solution Approach 2:
The patent employs pulse width modulation with selective duty cycles applied periodically to the drivers. This periodic action allows efficient control of the field coils with reduced transistor and terminal count, as the time-multiplexed control signals maintain resolution requirements without requiring continuous activation of all drivers at full power
Data Source
AI summary
A stepper motor controller includes control circuitry with control outputs and individual driver pulse width modulation (PWM) circuitry with individual driver PWM outputs and modulation control inputs coupled to the control outputs. There is a group of individual drivers, each one having an input coupled to one of the PWM outputs, and an output coupled to an individual driver terminal of the controller. There is common driver PWM circuitry having a common driver PWM output. A common driver having a common driver input is coupled to the common driver PWM output and a common driver output is coupled to a common driver terminal of the controller. When a coil is connected between respective driver terminals and the common driver terminal, individual PWM driver currents are supplied to the coils from the individual driver terminals and a common PWM driver current is supplied to the coils from the common driver terminal.