Vehicle Intermediate Circuit Discharge Using Discrete PWM Pulses
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Solution Overview
Problem
Existing active discharge circuits for vehicle intermediate circuits, which use resistors switched by semiconductor switches, result in excessive heating and require larger components, and are prone to failure due to reliance on microprocessors, posing safety risks during high-voltage discharges.
Innovation Solution
A discrete PWM (Pulse-Width Modulation) controlled discharge circuit that adjusts switching states using a discrete circuit without microprocessor control, employing a wave-shaped sawtooth voltage to evenly distribute power, reducing component size and heat generation, and ensuring safety through redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If continuous discharge with semiconductor switches is used, then discharge speed is improved, but heat generation increases and component size must be larger
Solution Approach 1:
The patent applies periodic action by using PWM (pulse-width modulation) to switch the discharge element on and off in discrete pulses rather than continuous operation. The control unit generates PWM signals that periodically activate the discharge element, allowing the intermediate circuit to be discharged at high speed while the periodic off-states allow heat dissipation, thereby reducing overall heat generation in the discharge element.
Solution Approach 2:
The patent employs dynamics by making the discharge process adaptive through PWM duty cycle adjustment. The control unit dynamically adjusts the duty cycle of the PWM signal based on the instantaneous voltage of the intermediate circuit, applying higher power when voltage is high and reducing power as voltage decreases, optimizing both discharge speed and thermal management throughout the discharge process.
2Measurement precision
If microprocessor control is used, then control precision is improved, but reliability decreases due to failure points
Solution Approach 1:
The patent applies self-service by implementing a discrete PWM control circuit that autonomously generates control signals without requiring a microprocessor. The discrete circuit uses voltage detection and comparison mechanisms to automatically regulate the discharge process, eliminating the single point of failure represented by the microprocessor while maintaining adequate control precision through analog voltage comparison and PWM generation.
Solution Approach 2:
The patent replaces the expensive and complex microprocessor with a simpler, more robust discrete circuit implementation. While discrete components have shorter individual lifetimes, their redundancy and simplicity make the overall system more reliable and cost-effective, particularly in safety-critical applications where failure of a single complex component could compromise the entire system.
3Power
If larger discharge elements are used, then discharge capability is improved, but device complexity and cost increase
Solution Approach 1:
By using periodic PWM switching, the patent enables smaller discharge elements to achieve the same effective discharge capability as larger continuous-discharge elements. The periodic on/off operation with appropriate duty cycle allows the discharge element to handle high power demands during pulses while having time to cool down between pulses, effectively reducing the required size and complexity of the discharge component.
Solution Approach 2:
The patent changes the operational parameters of the discharge element from continuous high-power operation to pulsed operation with variable duty cycle. This parameter change allows the use of smaller, less complex discharge elements that can withstand the intermittent high-power pulses while maintaining the overall discharge capability required for safety applications.
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 achieves safer, more efficient discharge with reduced component size and lower heat generation, ensuring reliable operation even in fault conditions, thereby enhancing safety and cost-effectiveness.
Implementation Method 1
a discrete discharge circuit, wherein the discrete discharge circuit is designed to adjust the switching states in the switching element by pulse-width modulation (PWM) during discharging of the at least one intermediate circuit element
Implementation Method 2
active discharge circuits use one or more resistors which are switched on in parallel with an intermediate circuit capacitor
Data Source
AI summary
An active discharge circuit for a vehicle discharge device; for discharging a vehicle intermediate circuit, includes a connector for connection to an intermediate circuit element of the vehicle intermediate circuit; a circuit arrangement parallel-connected to the connector and having at discharge element and at switching element, the switching element being designed to electrically contact the discharge element to the connector in a closed switching state and not to electrically contact the discharge element to the connector in an open switching state; and a discrete discharge circuit being designed to adjust the switching states in the switching element by pulse width modulation during discharging of the at least one intermediate circuit element.