Contactor Coil Driving Circuit With Shared PWM and Redundant Shut-Off
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Solution Overview
Problem
Existing contactor coil driving circuits for high voltage applications in electric vehicles are complex, costly, and space-consuming due to the need for multiple control circuits to differentiate between pick-up and hold currents, and provide redundant shut-down paths for functional safety, leading to issues with electromagnetic interference and radio emissions.
Innovation Solution
A unified driving circuit design with a common power supply side switch and individual ground side switches, combined with a voltage converter, allows for unified power supply and individual control of coils, reducing the need for separate PWM circuits and minimizing components, while ensuring functional safety through redundant shut-down paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate PWM circuits are used for each contactor coil to control pick-up and hold currents, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple separate PWM circuits into a single shared PWM circuit that controls multiple contactor coils. The control unit generates a single PWM signal that is distributed to multiple coils through individual switching elements, eliminating the need for separate PWM circuits for each coil while maintaining precise control of pick-up and hold currents for each coil independently
Solution Approach 2:
The single PWM circuit is designed to serve multiple functions by controlling multiple different contactor coils with different current requirements. The control unit can independently adjust the duty cycle for each coil through individual switching elements, allowing one PWM circuit to perform the work of multiple separate circuits while maintaining coil-specific control characteristics
2Reliability
If multiple separate control circuits are provided for each contactor coil, then the reliability is improved through redundant shut-down paths, but the manufacturing cost increases
Solution Approach 1:
The patent merges multiple separate control circuits into a single integrated control unit that manages multiple contactor coils. The control unit contains a single PWM circuit that generates unified control signals, which are then distributed to individual coils through separate switching elements. This consolidation reduces component count and manufacturing cost while maintaining redundant shut-down paths through the control unit's ability to independently control each coil's switching elements
Solution Approach 2:
Instead of duplicating entire control circuits for each coil, the patent uses a single control unit that copies the PWM signal to multiple coils through individual switching elements. Each coil receives an identical PWM signal structure but can be independently controlled through its dedicated switching element, achieving coil-specific control without the cost of multiple separate control circuits
3Device complexity
If a single shared PWM circuit is used for multiple contactor coils, then the device complexity is reduced, but the control precision for individual coils may be compromised
Solution Approach 1:
The patent segments the control path by providing individual switching elements for each contactor coil within the shared PWM circuit. While the PWM signal generation is unified, each coil has its own dedicated switching element that can be independently controlled, allowing precise individual coil control while maintaining circuit simplicity. The control unit can adjust the duty cycle for each coil independently through these segmented switching paths
Solution Approach 2:
The individual switching elements act as intermediaries between the shared PWM circuit and the multiple contactor coils. These switching elements receive the unified PWM signal and translate it into coil-specific control actions, enabling precise individual coil control while maintaining the simplicity of a single shared PWM circuit. The intermediary switching elements preserve control precision by providing dedicated control paths for each coil
4Speed
If fixed voltage is applied directly to contactor coil for pick-up current, then the power supply speed is improved, but the electromagnetic interference increases
Solution Approach 1:
The patent replaces direct fixed voltage application with periodic PWM (pulse width modulation) signaling for contactor coil control. Instead of continuously applying fixed voltage, the system uses high-frequency periodic switching with variable duty cycles to deliver the required pick-up current. This periodic action achieves fast power supply response while significantly reducing electromagnetic interference by eliminating the need for direct connection between the power supply and the coil
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 solution simplifies circuit design, reduces costs and board space, enhances energy efficiency, and minimizes electromagnetic interference by using a DCDC voltage converter with higher switching frequencies, ensuring safe disconnection of coils even with single-point faults.
Implementation Method 1
a voltage converter circuit (112) which is electrically connected to the power supply side switch (108) and which is configured to convert an input voltage, which is provided by a power supply, into an output voltage
Implementation Method 2
a first terminal (102), which is connectable by the power supply side switch (108) to coils (21, 22, 23) of a plurality of electromagnetic switching devices
Data Source
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AI summary
The present disclosure relates to a driving circuit for driving coils (21, 22, 23) of a plurality of electromagnetic switching devices, a battery management system comprising the driving circuit and a driving method. The driving circuit (100, 200, 300) comprises a power supply side circuit, which comprises a power supply side switch (108, 308) for controlling power supply of the coils (21, 22, 23) of the plurality of electromagnetic switching devices, a ground side circuit, which comprises a plurality of ground side switches (110, 310), wherein each of the plurality of ground side switches (110, 310) is adapted to electrically connect one of the coils (21, 22, 23) of the plurality of electromagnetic switching devices to a ground potential, and a control circuit for controlling the switching of the power supply side switch (108, 308) and the switching of the plurality of ground side switches (110, 310) to individually supply the coils (21, 22, 23) of the plurality of electromagnetic switching devices at least with a pick-up current for switching the respective one of the plurality of electromagnetic switching devices from an open state into a close state, or a hold-on current for holding the respective one of the plurality of electromagnetic switching devices in the close state.