Brushless Motor Control Circuit for High-Temperature Two-Wire Actuators
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Solution Overview
Problem
Existing electric actuators in the automotive sector face challenges with high-temperature resistance and electromagnetic compatibility due to the use of complex electronics in 'smart' systems, limiting their lifespan and efficiency, while 'dumb' systems with brushed DC motors are less efficient and compact compared to brushless DC motors.
Innovation Solution
A control system for polyphase brushless DC motors using a rudimentary electronic circuit with N probes for rotor position detection, allowing auto-switching and bidirectional control without a microprocessor, compatible with existing ECUs and resistant to temperatures above 125°C, using a two-wire electrical signal for simple logic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If complex electronics with microprocessor are used in smart actuators, then control precision and automation are improved, but temperature resistance and reliability deteriorate due to high temperature sensitivity of electronic components
Solution Approach 1:
The invention extracts the microprocessor and complex control electronics from the actuator, relocating intelligence to a remote ECU. The actuator retains only simple electronic components (power bridge, diodes, transistors) that can withstand high temperatures, thereby maintaining temperature resistance while preserving control functionality through the external ECU connection.
Solution Approach 2:
The invention replaces expensive, temperature-sensitive microprocessor-based electronics with inexpensive, rugged electronic components that can operate in harsh thermal environments. While the simple electronics have limited intelligence, they provide sufficient control for the actuator's basic functions and can operate reliably at temperatures above 125°C.
2Ease of manufacture
If brushed DC motors are used in dumb actuators, then cost and ease of control are improved, but efficiency, compactness and lifespan deteriorate
Solution Approach 1:
The invention replaces the mechanical commutator and brushes of traditional DC motors with an electronic commutation system. The brushless DC motor uses electronic switches (power bridge with transistors) to commutate the motor phases, eliminating mechanical wear components while maintaining simple control through the power bridge circuitry.
3Duration of action of stationary object
If brushless DC motors are used with simple electronics, then lifespan and temperature resistance are improved, but control complexity increases requiring microprocessor
Solution Approach 1:
The invention segments the control system into two parts: a simple local power bridge circuit in the actuator for basic commutation control, and a remote intelligent ECU for high-level control decisions. This segmentation allows the actuator to use temperature-resistant simple electronics while the complex control logic resides in the external ECU.
Solution Approach 2:
The invention introduces a power bridge circuit as an intermediary between the ECU and the brushless DC motor. The power bridge receives simple control signals from the ECU and performs the complex task of commutating the motor phases, thereby shielding the ECU from direct motor control complexity while enabling brushless motor operation.
4Device complexity
If two-wire electrical signal is used for control, then connection simplicity and cost are improved, but control precision and bidirectional control capability deteriorate
Solution Approach 1:
The invention makes the two-wire connection universal by designing the power bridge to interpret the same two-wire signal for multiple functions: forward motor control, reverse motor control, and braking. The direction control transistor and associated diodes enable the system to achieve bidirectional control and regenerative braking through the same simple two-wire interface.
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
Enables the use of brushless DC motors with increased lifespan, compact integration, reduced electromagnetic disturbances, and bidirectional control, while maintaining compatibility with existing systems and reducing costs.
Implementation Method 1
N probes for detecting the position of the rotor of said motor
Implementation Method 2
power switches capable of supplying the N phases of the motor from the two-wire electrical signal
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a mechatronic assembly for driving a member, including a control unit (1) and an actuator (2), the control unit (1) having a servo control algorithm and a power bridge, said algorithm controlling said power bridge, the power bridge outputting a bifilar electric signal (6) consisting of a power signal and a direction signal, the actuator (2) including a polyphase brushless electric motor (8) having n-phases, binary sensors (11) for detecting the position of the rotor of said motor (8), power switches (25) capable of powering the n-phases of the motor (8) using the bifilar electric signal (6), characterised in that the state of the power switches (25) is controlled directly by a signal from the detection sensors (11).