EPS Motor Control Shield Plate Layout for PWM Noise Suppression
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Solution Overview
Problem
Existing motor control devices and electric power steering control devices face challenges in suppressing noise emission from the control unit, particularly due to PWM control by the inverter circuit, which is not adequately addressed by current noise suppression methods.
Innovation Solution
Incorporating a shield plate grounded to the motor case between the filter portion and the control board within the control unit, which is connected to the power supply connector, to effectively suppress noise emission from the circuit components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the control unit is arranged on the side opposite to the output side of the output shaft with separate power supply circuit unit, then the electronic control device is downsized, but noise emission from the control unit is not sufficiently suppressed
Solution Approach 1:
A shield plate is introduced as an intermediary component between the filter portion and the control board. The shield plate is grounded to the motor case and effectively blocks noise emission from the control unit while maintaining the downsized integrated structure. This mediator approach allows the control unit to remain compact without compromising noise suppression performance.
2Volume of moving object
If the power supply circuit unit is arranged separately from the control unit, then the electronic control device is downsized, but noise emission from the control board to the outside is not sufficiently reduced
Solution Approach 1:
The shield plate serves as a grounded intermediary barrier positioned between the filter portion and control board. This mediator structure blocks the propagation of noise from the control board to the outside while allowing the separate arrangement of power supply components that enables downsizing of the overall device.
Solution Approach 2:
The shield plate is extracted as a separate noise suppression component that can be independently positioned and grounded. This extracted shielding element specifically addresses the noise emission problem from the control board without interfering with the compact integrated design of the power supply circuit unit and control unit.
3Power
If PWM control is performed on large electric current with the inverter circuit, then motor control is achieved, but noise is emitted to the outside
Solution Approach 1:
The shield plate acts as a grounded mediator between the filter portion and control board, blocking the noise generated during PWM control of large currents. This allows the inverter circuit to maintain its high-power control capability while the shield plate prevents the associated electromagnetic noise from propagating to the outside.
Solution Approach 2:
The shield plate converts the harmful noise emission into a grounded electrical path. By providing a low-impedance ground connection to the motor case, the shield plate redirects the noise energy away from external propagation, effectively transforming the harmful electromagnetic radiation into a controlled electrical return path.
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
The shield plate significantly reduces noise emission from the control unit by grounding it to the motor case, enhancing noise suppression and heat dissipation properties.
Implementation Method 1
a shield plate, which is arranged between the filter portion and the control board and is grounded to the motor case
Data Source
AI summary
Provided are a motor control device including: a motor case including a motor; a housing, which is provided to have a power supply connector mounted thereon and cover an upper portion of the motor case; and a control unit, which is arranged on a side opposite to an output side on an output shaft of the motor in a space formed by the motor case and the housing, and an electric power steering control device. The control unit includes a filter portion, which is arranged in an upper portion of the control unit and is connected to the power supply connector, a control board, which is arranged below the filter portion and has mounted thereon circuit components configured to supply an electric current to the motor, and a shield plate, which is arranged between the filter portion and the control board and is grounded to the motor case.