EPS Motor Control Unit Shield 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 in 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
1Device complexity
If the control unit integrates the inverter circuit and control board without additional noise suppression structures, then the device complexity is reduced, but noise emission from PWM control increases
Solution Approach 1:
A shield plate is introduced as an intermediary component between the control board and filter portion. This shield plate serves as a mediator to block electromagnetic noise generated by PWM control circuits from radiating outward, while maintaining the integrated structure of the control unit.
Solution Approach 2:
The shield plate is strategically positioned only in the specific region where noise emission occurs (between the control board and filter portion), providing localized noise suppression rather than requiring comprehensive shielding throughout the entire control unit, thus balancing noise reduction with structural simplicity.
2Volume of moving object
If the power supply circuit unit is arranged separately from the control unit, then the electronic control device size is reduced, but noise emission from the control unit increases
Solution Approach 1:
The shield plate acts as an intermediary barrier that allows the control unit to maintain its compact integrated design while internally suppressing noise generation. This enables the power supply circuit unit to remain separate (maintaining size benefits) while the shield plate prevents noise from the control board from emanating outward.
3Power
If PWM control is implemented with large electric current, then the motor control performance is improved, but noise emission to the outside increases
Solution Approach 1:
The shield plate converts the harmful electromagnetic noise generated by high-power PWM control into contained energy that can be directed toward the filter portion. By blocking the noise propagation path, the shield plate allows the high-power PWM control to maintain its performance benefits while the noise is redirected and filtered rather than radiated outward.
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
Implementation Method 2
a filter portion, which is arranged in an upper portion of the control unit and is connected to the power supply connector
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided are a motor control device including: a motor case (25, 225) including a motor (2); a housing (40, 400), which is provided to have a power supply connector (42) mounted thereon and cover an upper portion of the motor case; and a control unit (1), 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 (17), which is arranged in an upper portion of the control unit and is connected to the power supply connector, a control board (4a), which is arranged below the filter portion and has mounted thereon circuit components (4, 35a, and 35b) configured to supply an electric current to the motor, and a shield plate (50, 500), which is arranged between the filter portion and the control board and is grounded to the motor case.