Control Unit Merging Safety and Discharge Circuits
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Solution Overview
Problem
Existing control units for electrical machines in motor vehicle drive technology require high technical complexity and cost due to separate control mechanisms for safety and discharge circuits, which are activated with different triggering criteria.
Innovation Solution
A control unit with a single control circuit that triggers both the safety and discharge circuits, reducing the need for separate controls, and featuring a safety circuit with a controllable switch connected to the high-voltage section to close the half-bridge switch and a discharge circuit with a resistor and controllable switch to dissipate energy stored in the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate control mechanisms are used for safety circuit and discharge circuit with different triggering criteria, then the system can provide comprehensive safety protection, but the technical complexity and cost increase
Solution Approach 1:
The patent combines the control of the safety circuit and discharge circuit into a single control mechanism. The control unit monitors system parameters and activates either the safety circuit (closing half-bridge switches) or the discharge circuit (connecting voltage terminals) based on the same control logic, eliminating the need for separate control mechanisms while maintaining comprehensive safety protection.
Solution Approach 2:
The control unit is designed to perform multiple functions: it monitors system parameters, determines fault conditions, and controls both the safety circuit and discharge circuit operations. This multi-functional approach allows a single control mechanism to replace what would traditionally require separate control systems, reducing complexity while maintaining reliability.
2Reliability
If separate control mechanisms are used for safety circuit and discharge circuit, then comprehensive safety protection is provided, but the installation space and cost increase
Solution Approach 1:
The control unit integrates the control functions for both safety circuit and discharge circuit into a single physical component, reducing the installation space required. Instead of having separate control mechanisms that would each require their own space, the unified control unit consolidates these functions, thereby reducing overall installation space while maintaining comprehensive safety protection.
3Reliability
If the discharge circuit is permanently switched on to discharge the intermediate circuit capacitor, then the capacitor is continuously protected, but energy is permanently converted to heat and efficiency is reduced
Solution Approach 1:
The discharge circuit is designed to operate periodically rather than continuously. The control unit activates the discharge circuit only when needed (e.g., during fault conditions or when the capacitor voltage exceeds a threshold), allowing the capacitor to be protected while minimizing the time during which energy is converted to heat, thereby maintaining system efficiency.
Solution Approach 2:
The discharge circuit transitions from a static permanently-on state to a dynamic switched state. The control unit dynamically controls the discharge circuit based on real-time system conditions, activating it only when protection is needed and deactivating it when the capacitor is at safe voltage levels, thus balancing protection requirements with energy efficiency.
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 solution simplifies the shutdown process, reduces costs and installation space, and allows for efficient dissipation of energy, enabling the control unit to be brought into a safe state quickly while minimizing energy conversion to heat.
Implementation Method 1
a capacitance which is connected between the voltage connections
Implementation Method 2
a discharge circuit which is designed to electrically connect the voltage terminals in the event of a fault
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a control unit (40) for driving an electric load, in particular an electric machine, having a first and a second voltage terminal (46, 48) in order to supply the control unit (40) with electrical energy, a capacitor (58), which is connected between the voltage terminals (46, 48), at least one half-bridge (15), which is connected between the voltage terminals (46, 48), wherein the half-bridge (50) has two controllable switches (52, 54), between which there is formed a half-bridge tap (50) for connecting the load, a safety circuit (66), which is designed to close one of the controllable switches (52, 54) of the half-bridge (50) in the event of a fault, a discharge circuit (68), which is designed to connect the voltage terminals (46, 48) electrically in the event of a fault, and having a control circuit (18) which is designed to provide a control signal (78) which triggers the safety circuit (66) and the discharge circuit (68) in the event of the detected fault.