Acute Triangle Voltage Wave Control for Electromagnetic Brake Noise
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Solution Overview
Problem
The non-excited operation type electromagnetic brake control devices experience vibration noise at low carrier frequencies and frequent switching at higher frequencies, leading to potential semiconductor device damage and increased current flow in the brake coil during the holding state.
Innovation Solution
A non-excited operation type electromagnetic brake control device that generates a stepped acute triangle voltage wave with alternating valley and peak parts of different angles, a comparative voltage wave based on current flow, and a switching unit that controls current supply to the brake coil based on voltage wave comparisons to reduce average current and prevent frequent switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the carrier frequency of the triangle voltage wave is increased to reduce average current through the brake coil, then the average current is reduced, but frequent switching occurs which may damage semiconductor devices
Solution Approach 1:
The patent uses periodic switching of the brake coil current through PWM control, where the switching frequency is optimized to balance between reducing average current and avoiding excessive switching frequency that would damage semiconductor devices. The control device periodically switches the current on and off to maintain the brake in a holding state with reduced power consumption.
Solution Approach 2:
The patent changes the parameter of carrier frequency from a fixed low value to an optimized higher frequency range, while simultaneously adjusting the duty cycle of the PWM signal. This parameter change allows reducing the average current through the brake coil while maintaining reliable operation of semiconductor switching devices by keeping the switching frequency within acceptable limits.
2Reliability
If the carrier frequency is set low to avoid frequent switching, then semiconductor device damage is reduced, but vibration noise occurs
Solution Approach 1:
The control device employs periodic PWM switching to drive the brake coil, where the switching frequency is set to a carrier frequency that is high enough to avoid audible vibration noise but not so high as to cause excessive switching losses or damage to semiconductor devices. This periodic control action eliminates the harmful vibration noise while maintaining device reliability.
3Device complexity
If a conventional triangle voltage wave is used for control, then the control is simple, but vibration noise occurs at low carrier frequencies and frequent switching occurs at higher frequencies
Solution Approach 1:
The patent replaces the conventional triangle voltage wave control with a periodic PWM control method that switches the brake coil current in a periodic on-off manner. This periodic control action provides a more effective way to control the brake while avoiding the vibration noise and frequent switching problems associated with conventional triangle wave control at various carrier frequencies.
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 reduces the average current through the brake coil without causing vibration noise or frequent switching, minimizing semiconductor device damage and reducing power consumption, while maintaining precise control over the braking state.
Implementation Method 1
a brake coil which generates magnetic attraction force to switch the non-excited operation type electromagnetic brake from the engaged state to the disengaged state
Implementation Method 2
in the excited state in which the brake is set to the disengaged state, the movable core is attracted to a fixed core by magnetic attraction force and thus the brake disk becomes a free state
Implementation Method 3
in the non-excited state in which the brake is set to the engaged state, a movable core is pushed by spring force, and frictional force which is generated between the movable core and a brake disk
Implementation Method 4
frictional force which is generated between the movable core and a brake disk and between the brake disk and an anti-movable core generates brake torque
Data Source
AI summary
A non-excited operation type electromagnetic brake control device and method which are free from vibration noise and frequent switching when reducing average current which flows through a brake coil in a holding state of a non-excited operation type electromagnetic brake are provided. An acute triangle voltage wave generation unit generates a stepped acute triangle voltage wave which is formed by valley parts with a first angle and peak parts with a second angle smaller than the first angle arranged alternatively. A comparative voltage wave generation unit generates a comparative voltage wave based on current which flows through the brake coil. A comparison unit compares the acute the triangle voltage wave with the comparative voltage wave when the non-excited operation type electromagnetic brake is in the holding state. A switch performs switching to supply current to the brake coil when the acute triangle voltage wave is larger than the comparative voltage wave and to cut off the supply of current to the brake coil when the acute triangle voltage wave is not larger than the comparative voltage wave.