Motor Control Device Using Small Capacitor for Electric Brake
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Solution Overview
Problem
Conventional motor control devices face challenges in miniaturization and cost reduction due to the need for large capacitance capacitors to accumulate power for applying an electric brake when the power supply is stopped, which complicates the design and increases costs.
Innovation Solution
A motor control device with a switch group, a capacitor of small capacitance, and a connection switch that connects the capacitor to part of the switch group when power is stopped, allowing the capacitor to power the switches to short-circuit the motor coils and apply a brake, reducing the required capacitance and enabling miniaturization and cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large capacitance capacitor is used to accumulate power for operating the starting device and drive device, then the power accumulation is sufficient, but the device size and cost increase
Solution Approach 1:
The patent divides the switch group into two functional subsets: switches for motor control during normal operation, and switches for brake application during power failure. The capacitor only needs to power the brake switches, segmenting the power requirement and enabling a smaller capacitor.
Solution Approach 2:
The capacitor accumulates power during normal operation when the power supply is active, preparing energy in advance for the emergency brake function. This preliminary energy storage during normal operation eliminates the need for a large capacitor designed for worst-case scenarios.
2Reliability
If a large capacitance capacitor is used to accumulate power for operating the starting device and drive device, then the power accumulation is sufficient, but the manufacturing cost increases
Solution Approach 1:
The patent segments the power requirement into operational power (from main supply) and emergency brake power (from capacitor). This segmentation reduces the capacitor's power burden, allowing the use of a smaller, less expensive capacitor component.
Solution Approach 2:
The capacitor is designed as a small, inexpensive component that provides temporary power only during power failure for brake application. By accepting limited duration and reduced capacity, a cheaper capacitor can be used instead of an expensive large-capacity unit.
3Adaptability or versatility
If the capacitor accumulates power for operating both the starting device and drive device, then all functions are supported, but the device complexity increases
Solution Approach 1:
The patent segments the switch group into control switches and brake switches, with the capacitor dedicated only to brake operation. This functional segmentation simplifies the power management architecture compared to a single large capacitor supporting all functions.
Solution Approach 2:
The connection switch acts as an intermediary that connects the capacitor to the brake switches only during power failure. This intermediary control simplifies the overall system by providing a clear, conditional power path rather than a complex multi-function power distribution network.
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 allows for a compact and cost-effective motor control device that can apply an electric brake efficiently by using a small capacitance capacitor to power the switches, facilitating quick motor stoppage and reducing the overall size and expense of the device.
Implementation Method 1
a capacitor of small capacitance, which accumulates power supplied from a voltage regulator circuit
Implementation Method 2
power supplied from a voltage regulator circuit connected through a diode to the electric power source
Implementation Method 3
a switch group which connects each coil included in a motor to an electric power source
Implementation Method 4
each coil is short-circuited by an operation of the part of switches to apply a brake to the motor
Data Source
Figure 1
Figure 2
AI summary
To provide a motor control device which can apply an electric brake to a motor when power supply is stopped, and achieve a miniaturization and a cost reduction. A first switch 11 through a sixth switch 16 connects respective coils L1, L2 and L3 included in a motor to an electric power source 20. The capacitor C accumulates the power supplied from the electric power source 20. A seventh switch 17 connects the capacitor C to a fourth switch 14 through the sixth switch 16, when the power supply from the electric power source 20 is stopped. The operation of the seventh switch 17 causes the fourth switch 14 through the sixth switch 16 to operate by the power accumulated in the capacitor C, and respective coils L1 to L3 are short-circuited to apply the brake to the motor.