Normally-ON Discharge Switch for High-Voltage Bus Energy Dissipation
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Solution Overview
Problem
Existing power inverter systems face challenges in efficiently discharging electrical energy stored on high-voltage buses, particularly when the system is not in operation, leading to potential over-discharge and energy loss due to residual power in bulk capacitors.
Innovation Solution
A power inverter system with a passive discharge circuit that includes a normally-ON discharge switch and a low-impedance discharge resistor, controlled by an ignition switch, which allows for rapid and automatic discharge of energy when the system is turned off, preventing over-discharge and energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a discharge circuit is added to discharge the high-voltage bus, then energy loss is reduced, but device complexity increases
Solution Approach 1:
The discharge switch is integrated into the existing power inverter circuitry, combining the discharge function with the bulk capacitor and inverter components. This merging approach enables the discharge circuit to share existing structural elements, thereby reducing the increase in device complexity while achieving effective energy discharge.
Solution Approach 2:
The discharge circuit is designed to automatically activate when the ignition switch transitions to the OFF state, without requiring external control or additional monitoring systems. The circuit self-regulates the discharge process through the normally-ON discharge switch, eliminating the need for complex control logic while reducing energy loss.
2Speed
If a normally-ON discharge switch is used, then discharge speed is improved, but control complexity increases
Solution Approach 1:
Instead of using a normally-OFF switch that requires active triggering to enable discharge, the invention employs a normally-ON discharge switch that is automatically turned off by the ignition switch signal. This inversion of the conventional approach allows rapid discharge activation without complex control circuitry, as the switch state is directly controlled by the existing ignition switch.
3Reliability
If the discharge switch is controlled by the ignition switch, then reliability is improved, but ease of operation is reduced
Solution Approach 1:
The ignition switch serves a dual function: it controls the normal operation of the power inverter system and simultaneously controls the discharge circuit activation. By making the ignition switch multi-functional, the system achieves reliable automatic discharge control without adding separate control mechanisms, maintaining ease of operation while improving reliability.
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 system effectively discharges high-voltage bus energy quickly and efficiently, reducing power loss and preventing over-discharge, even in scenarios like airbag deployment or high g-force events, while consuming minimal energy.
Implementation Method 1
a low-impedance discharge resistor arranged between the positive and negative conductors of the high-voltage bus
Data Source
AI summary
A power inverter including a multi-phase inverter circuit is electrically connected to a high-voltage DC power source, and includes a capacitor electrically connected between positive and negative conductors of a high-voltage bus. A normally-ON discharge switch is electrically connected in series with a discharge resistor between the positive and negative conductors of the high-voltage bus. The discharge switch includes a control gate, wherein the control gate of the discharge switch is in communication with an ignition switch. The discharge switch is controllable to an open state between the positive and negative conductors of the high-voltage bus when the ignition switch is in an ON state. The discharge switch achieves a closed state to provide a low-impedance electric current flow path through the discharge resistor between the positive and negative conductors of the high-voltage bus when the ignition switch is in an OFF state.