Brake Coil PWM Control and Rapid De-excitation Circuit
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Solution Overview
Problem
Conventional drive systems with electromagnetically operable brakes lack efficient control and monitoring mechanisms for wear detection and rapid de-excitation, leading to suboptimal operation and maintenance challenges.
Innovation Solution
A drive system incorporating an electromagnetically operable brake with a three-phase motor, electronic circuit, and specific components like a rectifier, upper and lower controllable semiconductor switches, freewheeling diodes, and varistors, allowing for controlled voltage and current management through pulse-width modulation, enabling efficient operation and wear monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a direct current is used to actuate the brake coil, then the brake can be released or applied, but the brake cannot be monitored for wear under defined conditions and de-excitation is not rapid
Solution Approach 1:
The patent applies pulse-width modulated (PWM) actuation of the upper semiconductor switch to dynamically control the voltage supplied to the brake coil. This allows the system to switch between different operating modes: during energization, the coil receives controlled voltage for precise brake release; during de-excitation, the upper switch opens and the freewheeling path enables rapid current decay. The dynamic switching capability resolves the contradiction between controlled operation and rapid de-excitation.
Solution Approach 2:
The patent introduces a freewheeling diode and varistor as intermediary components to create a dedicated current decay path. When the upper semiconductor switch opens, the stored energy in the brake coil is redirected through this intermediary path, enabling rapid de-excitation without affecting the controlled energization phase. This intermediary structure allows the system to achieve both precise control during energization and rapid de-excitation.
2Productivity
If voltage is supplied to the brake without controlled conditions, then the brake operates, but wear monitoring cannot be performed and operation is not energy-efficient
Solution Approach 1:
The patent employs periodic PWM actuation of the upper semiconductor switch to supply voltage to the brake coil in controlled pulses rather than continuous DC. This periodic control allows the system to define specific measurement windows where the brake operates under known, repeatable conditions. During these controlled phases, the control electronics can accurately monitor current characteristics to detect wear, while maintaining energy efficiency by not continuously supplying full voltage.
Solution Approach 2:
The control electronics continuously monitors the current flowing through the brake coil and uses this feedback to detect changes in the magnetic circuit characteristics that indicate wear. By comparing the measured current characteristics against reference values obtained under defined operating conditions, the system can precisely determine wear state while maintaining energy-efficient operation through adaptive PWM control.
3Measurement precision
If galvanic separation is required between control electronics and shunt resistor, then measurement can be performed, but device complexity increases
Solution Approach 1:
The patent connects the shunt resistor directly to the zero potential (ground) of the control electronics, creating an equipotential connection between the measurement point and the control system. This eliminates voltage differences that would require galvanic isolation, allowing the control electronics to directly measure the voltage drop across the shunt resistor without isolation barriers. This approach maintains accurate current measurement capability while significantly reducing device complexity by removing the need for galvanic separation components.
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 precise control of brake operation, rapid de-excitation, and effective wear detection, ensuring efficient and energy-saving continuous operation without the need for galvanic separation, thereby improving the overall performance and reliability of the brake system.
Implementation Method 1
A direct voltage provided by a rectifier is able to be made available
Implementation Method 2
a component which initially exhibits high resistance at low voltages and then becomes low-resistive at a high voltages
Implementation Method 3
an electromagnetically operable brake
Data Source
AI summary
In a drive system and method for operating a drive system, in which the drive systems includes an electromagnetically operable brake, an electric motor, e.g., a three-phase motor, and an electronic circuit, the brake has an energizable coil, e.g., a brake coil, the electronic circuit has a rectifier, an upper controllable semiconductor switch, a freewheeling diode, and a varistor, a direct voltage provided by a rectifier is able to be made available by closing or by a pulse-width-modulated actuation of an upper controllable semiconductor switch of the coil, and by opening the upper controllable semiconductor switch, a current driven by the coil in the de-excitation of the coil is freewheeling and/or flowing through the freewheeling diode and the varistor or through a component connected in parallel with the varistor.