Motor Control Device Charge Pump Safety Circuit
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Solution Overview
Problem
Electronically commutated DC motors can experience uncontrolled current rise and heat generation due to microcontroller malfunctions, leading to potential fires, despite existing error protection methods like software watchdogs and independent clock sources, which may fail to ensure proper reset functionality in cost-sensitive devices.
Innovation Solution
A device with a control device generating periodic first control signals and a second control signal derived from these, using an electronic charge pump as a triggering device to disconnect the switching device from the supply voltage if the first control signals are absent, ensuring correct winding current supply and increased operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cost-effective error protection methods (software watchdog and independent clock sources) are used in the microcontroller, then device cost is reduced, but reliability deteriorates because the microcontroller may fail to perform reset functionality under unfavorable operating conditions
Solution Approach 1:
The patent introduces a second switching device as an intermediary component between the control device and the first switching device. This mediator monitors the control signals and can disconnect the power supply to the first switching device when control signals are absent, providing an additional layer of protection without requiring complex redundant systems in the microcontroller itself.
Solution Approach 2:
The patent divides the switching control function into two separate switching devices: a first switching device controlled by PWM signals for normal motor control, and a second switching device controlled by a separate logic circuit for safety monitoring. This segmentation allows independent monitoring of control signal presence, enhancing reliability while keeping the microcontroller simple and cost-effective.
2Ease of operation
If the microcontroller generates PWM signals for controlling the output stage, then motor control functionality is achieved, but safety deteriorates because the microcontroller may malfunction without generating proper PWM signals, leading to uncontrolled current rise and heat generation
Solution Approach 1:
The patent implements preliminary safety action by having the second switching device continuously monitor for the presence of control signals before allowing power to reach the first switching device. The logic circuit prepares to disconnect power in advance if control signals are absent, preventing uncontrolled current rise and heat generation before they can occur.
Solution Approach 2:
The patent establishes a feedback mechanism where the second switching device monitors the control signals generated by the microcontroller and provides feedback by either maintaining or disconnecting power supply. This closed-loop monitoring ensures that if the microcontroller fails to generate proper PWM signals, the system automatically detects and responds by preventing harmful current flow.
3Reliability
If a second switching device with functional coupling to control signals is added to monitor control signal presence, then safety is improved by preventing uncontrolled operation, but device complexity increases
Solution Approach 1:
The patent designs the second switching device to serve multiple functions: it monitors control signal presence, controls power supply to the first switching device, and provides safety protection. By making this single component multi-functional, the patent avoids the need for additional separate monitoring circuits, logic gates, or protection devices that would increase system complexity.
Solution Approach 2:
The patent combines the safety monitoring function and the power control function into a single second switching device. Rather than using separate components for monitoring control signals and for controlling power supply, the invention merges these functions into one integrated switching element, thereby improving safety without proportionally increasing device complexity.
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 configuration ensures the electric motor is only supplied with current when control signals are properly generated, preventing uncontrolled operation and reducing the risk of overheating or fires, thereby enhancing the reliability and safety of the motor control system.
Implementation Method 1
An electronic charge pump can be used to drive the high-side switch of the named output stage circuit
Implementation Method 2
The triggering device is designed as an electronic charge pump which is controlled by a second control signal S2
Data Source
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Figure 2
AI summary
The invention relates to a device for actuating an electronically commutated electric motor, said device comprising a control unit. The control unit can be used to emit first control signals to a first switchgear by means of which the electric motor can be actuated. The device further comprises a second switchgear for switching the first switchgear to an electrical supply voltage, the first control signals being functionally coupled to a second control signal for a trigger unit of the second switchgear.