Predriver Current and Voltage Slope Control for Vehicle Load Drivers
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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, and they require customization for different vehicle configurations, which complicates the design and reduces the commonality of integrated circuits (ICs).
Innovation Solution
A load drive control device with a driver circuit, a predriver circuit, and a controller that includes slope control circuits to separately manage current and voltage slopes, allowing for the selection of suitable patterns based on the vehicle configuration, thereby reducing EMI noise and switching loss while enhancing IC commonality.
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 current slope by switching between multiple current sources with different current values. The controller selectively activates current sources based on the required switching characteristics, enabling adaptive adjustment of current rise/fall rates to balance switching loss and EMI noise across different operating conditions
Solution Approach 2:
The patent changes the parameter of current slope by providing multiple current sources with different current values. By selecting appropriate current sources, the system can adjust the inclination of current rising and falling slopes to optimize the balance between switching speed (for reducing switching loss) and EMI noise generation
2Adaptability or versatility
If driver circuit arrangement varies to adapt to different vehicle configurations, then adaptability is improved, but EMI noise and heat dissipation characteristics change
Solution Approach 1:
The patent creates a universal driver circuit design that can adapt to different vehicle configurations through software control rather than hardware customization. The controller selects from multiple current sources and control patterns to accommodate various wire harness arrangements and heat dissipation conditions, eliminating the need for different IC designs for different vehicle models
3Loss of energy
If current slope is increased to reduce switching loss, then switching loss is reduced, but voltage waveform distortion increases due to parasitic inductance
Solution Approach 1:
The patent incorporates feedback control where the controller monitors the switching state and selectively activates current sources based on real-time conditions. This feedback mechanism allows the system to adjust current slope dynamically, preventing excessive voltage waveform distortion while maintaining efficient switching by selecting appropriate current sources for each switching event
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 effectively reduces EMI noise and switching loss by controlling current and voltage slopes independently, allowing for adaptable operation across various vehicle configurations while maintaining IC commonality, thus improving productivity and efficiency.
Implementation Method 1
A solenoid (load) mounted in a vehicle is generally driven by turning a driver transistor ON/OFF with a pulse width modulation (PWM) control
Implementation Method 2
the length of the wiring harnesses changes, thereby changing the induced electromotive force due to the parasitic inductance and the like of the wire harness
Implementation Method 3
an increase in electro magnetic interface (EMI) noise due to high frequency components of the output voltage
Data Source
AI summary
A predriver circuit 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 outputs, to the predriver circuit, 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.