Predriver Slope Control for EMI and Switching Loss Balance
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Solution Overview
Problem
Existing load drive control devices face challenges in reducing Electromagnetic Interference (EMI) noise and switching loss due to high switching speeds, which are exacerbated by varying wire harness configurations and heat dissipation structures in vehicles, requiring adaptable current and voltage waveforms to match each vehicle's specific conditions while maintaining commonality of integrated circuits (ICs).
Innovation Solution
A load drive control device comprising a driver circuit, a predriver circuit, and a controller that separately controls the inclination of current and voltage slopes using slope control circuits within the high-side predriver circuit, allowing for selection of suitable patterns for each vehicle configuration, stored in an IC or external controller, to minimize EMI noise and switching loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high switching speed is used to reduce switching loss, then switching loss is reduced, but EMI noise increases due to steep current change and parasitic inductance
Solution Approach 1:
The patent implements dynamic control of switching waveforms by providing multiple current slope patterns and voltage slope patterns that can be selected based on operating conditions. The controller dynamically switches between different slope combinations to optimize the balance between switching loss and EMI noise across varying load conditions and wire harness configurations.
Solution Approach 2:
The patent changes the parameters of current and voltage slopes by providing multiple predefined patterns with different slope inclinations. By selecting appropriate combinations of current slope patterns and voltage slope patterns, the system adjusts the rate of change of current and voltage to minimize both switching loss and EMI noise under different operating conditions.
2Object-affected harmful factors
If wire harness arrangement varies in different vehicles, then EMI noise characteristics change due to varying parasitic inductance, but using vehicle-specific driver circuits reduces commonality of ICs
Solution Approach 1:
The patent creates a universal driver circuit design that can adapt to different vehicle configurations and wire harness arrangements. By incorporating multiple current slope patterns and voltage slope patterns within a single IC, the circuit can handle various EMI noise characteristics without requiring vehicle-specific customization, thus maintaining IC commonality while effectively addressing different EMI conditions.
Solution Approach 2:
The system dynamically selects appropriate waveform patterns based on operating conditions and EMI requirements. The controller can adapt the current and voltage slope patterns in real-time to match different wire harness configurations and vehicle environments, allowing a single universal IC design to effectively serve multiple vehicle platforms with varying EMI characteristics.
3Loss of energy
If current slope and voltage slope are controlled separately, then both EMI noise and switching loss can be optimized, but device complexity increases
Solution Approach 1:
The patent pre-defines multiple current slope patterns and voltage slope patterns that have been optimized for different operating conditions. These patterns are stored in advance within the controller, eliminating the need for complex real-time calculations. The controller simply selects the appropriate pre-defined patterns based on operating conditions, reducing computational complexity while maintaining optimal control of both current and voltage slopes.
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 effectively reduces EMI noise and switching loss by allowing precise control of current and voltage slopes, enhancing the commonality of IC configurations and improving productivity by adapting to different vehicle arrangements without altering driver IC specifications.
Implementation Method 1
a slope control circuit configured to separately control inclination of a current slope indicating rising and falling of an output current output from at least either one of the high-side driver element or the low-side driver element, and inclination of a voltage slope indicating rising and falling of an output voltage output from the driver circuit
Implementation Method 2
the high switching speed causes an increase in the induced electromotive force due to a steep current change and the parasitic inductance and an increase in electro magnetic interface (EMI) noise
Data Source
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AI summary
A predriver circuit 20 that controls driver elements includes a slope control circuit that separately controls inclination of slope of current from the driver elements, and inclination of slope of voltage from a driver circuit. A controller 30 outputs, to the predriver circuit 20, a current control signal selected from a plurality of current control signals and a voltage control signal selected from a plurality of voltage control signals, to control the slope of current from the driver elements and the slope of voltage from the driver circuit.