Brushless DC Motor with External Converter Unit
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Solution Overview
Problem
Brushless DC motors that can be driven by AC power and have adjustable rotation speed using digital signals face size and cost issues due to the need for an AC/DC converter and a microcomputer, which increases the motor's size and complexity when DC power is supplied.
Innovation Solution
A motor device configuration with a separate converter unit housing the AC/DC converter and microcomputer, allowing the motor unit to receive DC voltage and control signals, reducing the motor's size by relocating the microcomputer and AC/DC converter outside the motor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the microcomputer and AC/DC converter are installed inside the motor unit, then the motor can be driven by AC power and have adjustable rotation speed, but the size of the motor increases
Solution Approach 1:
The motor device is divided into two separate units: a motor unit and a converter unit. The motor unit contains only the brushless DC motor, inverter circuit, and inverter drive circuit, while the converter unit contains the AC/DC converter and microcomputer. This segmentation allows the motor to maintain a compact size while the converter unit provides AC power conversion and control functions externally.
Solution Approach 2:
The AC/DC converter and microcomputer are extracted from the motor unit and placed in a separate converter unit. This extraction removes the bulky power conversion and control components from the motor, enabling the motor to be smaller while still maintaining the capability to be driven by AC power with adjustable speed through the external converter unit.
2Adaptability or versatility
If the AC/DC converter is installed inside the motor, then the motor can accept AC power input, but the cost and size of the motor increase when DC power is supplied
Solution Approach 1:
The system is segmented into a motor unit and a converter unit. The converter unit houses the AC/DC converter, allowing the motor unit to remain simple and cost-effective. When DC power is supplied, only the motor unit is needed, eliminating the unnecessary AC/DC converter from the motor's internal structure and reducing manufacturing costs.
Solution Approach 2:
The converter unit serves as a universal interface that can convert AC power to DC power for the motor unit. This external converter unit can be used across different motor applications, making the motor unit itself more versatile and adaptable to different power sources without requiring the AC/DC converter to be built into each motor.
3Ease of operation
If the electric circuit board is enlarged to accommodate the microcomputer, then the rotation speed can be adjusted with digital signals, but the size of the motor increases
Solution Approach 1:
The microcomputer is extracted from the motor unit's electric circuit board and placed in the external converter unit. This allows the motor unit's circuit board to remain compact while the converter unit provides the digital speed control functionality through its own microcomputer, maintaining ease of operation without increasing motor size.
Solution Approach 2:
The control system is segmented between the motor unit and converter unit. The converter unit contains the microcomputer that receives digital control signals and generates analog control signals for the inverter drive circuit. This segmentation allows digital speed control capability to be maintained while the motor unit remains compact.
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 reduces the motor's size and manufacturing costs by eliminating the need for an internal microcomputer and AC/DC converter, enabling efficient AC input type motor devices with adjustable speed control.
Implementation Method 1
The AC/DC converter converts an AC voltage to a DC voltage to be supplied to the motor unit
Implementation Method 2
The inverter circuit supplies a drive current to the brushless DC motor. The motor is rotated by supplying the drive current to the motor
Implementation Method 3
The microcomputer receives a digital control signal and outputs an analog control signal
Data Source
AI summary
A motor device includes a motor unit and a converter unit. The motor unit includes an inverter circuit; an inverter drive circuit; a brushless DC motor comprising a rotor and a stator; a first shunt resistor; a first input terminal; a second input terminal; a third input terminal; a first output terminal; and a first ground terminal. The converter unit includes a case; a AC/DC converter; a microcomputer; a first output terminal; a second output terminal; a third output terminal; a first input terminal; a second shunt resistor; and a second grounding terminal. The microcomputer calculates a current value by using the terminal voltage and a resistance value of the second shunt resistor, compares the current value with a specified current value, and limit or cut off the output of the analog control signal when the current value exceeds the specified current value.