Bistable Permanent Magnet Coil Circuit for Reversible PWM Current
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Solution Overview
Problem
Existing control circuits for bistable permanent magnet mechanisms are complex and costly, and they struggle to provide adjustable positive and negative currents without load breaking and Pulse Width Modulation (PWM) control.
Innovation Solution
A control circuit using a combination of switches and a diode, allowing for simple adjustment of current direction by turning off switches sequentially, and optionally using an electronic switch for PWM control, thereby avoiding load breaking and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a complex driving circuit design is used to provide adjustable positive and negative currents, then the current control capability is improved, but the device complexity and cost increase
Solution Approach 1:
The driving circuit is segmented into multiple independent switches (first switch, second switch, third switch, fourth switch, fifth switch) that can be independently controlled. Each switch is positioned at specific nodes in the circuit to enable independent control of current paths, allowing the coil to receive positive or reverse current by controlling which switches are on or off, thereby achieving current direction adjustment without a complex unified driving circuit
Solution Approach 2:
A diode is introduced as an intermediary component in the circuit. The diode is connected between specific nodes and enables unidirectional current flow in certain paths, facilitating the separation of positive and reverse current paths. This intermediary component simplifies the overall circuit design by using passive diode characteristics rather than active switching for every current path
2Speed
If switches are turned off simultaneously to stop current, then the current stopping response is improved, but load breaking occurs causing harmful effects
Solution Approach 1:
The fifth switch is turned off in advance before turning off the main current-carrying switches (first and fourth switches for positive current, or third and second switches for reverse current). This preliminary action allows the current to naturally decay through the diode path or resistive paths before the main switches open, preventing abrupt load breaking and associated harmful effects like voltage spikes or arcing
Solution Approach 2:
The circuit design inherently provides a current decay path through the diode and resistor combinations that cushion the current interruption. When the fifth switch opens first, it initiates a controlled current decay process that prevents sudden current interruption, thereby cushioning against load breaking effects before the main switches are turned off
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
Enables adjustable current direction without load breaking, reduces costs, and supports PWM control for a wide range of current values and mechanisms.
Implementation Method 1
when a coil is energized, the coil through which the current flows generates a magnetic field that allows a movable iron core to move rapidly from, for example, position A to position B
Implementation Method 2
the magnetic field force generated by the permanent magnets keeps the movable iron core in position B
Data Source
AI summary
The present disclosure provides a control circuit and a control method of a bistable permanent magnet mechanism. The control circuit includes five switches, a diode and a control unit for controlling the five switches to be turned on and turned off. The control circuit enables the positive and the negative of the current passing through the coil to be adjustable at any time and avoids load breaking, without a complicated design of a driving circuit, thereby reducing the cost. It can also realize PWM control, adapt to a larger current range and different bistable permanent magnet mechanisms, and has a wide range of application scenarios.