Sequential Shutdown of Pulse-Controlled Inverter to Limit Current and Voltage Spikes
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Solution Overview
Problem
Conventional shutdown methods for pulse-controlled inverters in electric machines, such as short-circuit and disconnect modes, result in undesirable side effects like current or voltage rise, torque disruption, and overheating, which can lead to component damage and inefficiencies.
Innovation Solution
Implementing a sequential shutdown method where the electric machine is first switched to the disconnect mode and then to the short-circuit mode, with a predefined time threshold and optional criteria based on current, voltage, or rotational speed, to minimize adverse effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pulse-controlled inverter is switched to short-circuit mode to protect components, then component protection is improved, but phase current increases causing potential damage and overheating
Solution Approach 1:
The control unit preemptively switches off all switches in the pulse-controlled inverter before the malfunction can cause damage, transitioning to disconnect mode. This preliminary action prevents the harmful phase current increase that would otherwise occur in short-circuit mode, while still protecting components through subsequent monitoring and controlled transition to short-circuit mode if necessary.
2Reliability
If the pulse-controlled inverter is switched to short-circuit mode to protect components, then component protection is improved, but machine torque changes suddenly affecting vehicle performance
Solution Approach 1:
The control unit preemptively transitions to disconnect mode by switching off all inverter switches before the malfunction can cause damage, avoiding the sudden torque change that would occur with immediate short-circuit mode activation. This preliminary disconnect action maintains vehicle performance while protecting components, with the option to transition to short-circuit mode only if absolutely necessary.
3Reliability
If the pulse-controlled inverter is switched to disconnect mode to protect components, then component protection is improved, but d.c. link voltage increases by 50 V or more causing overload
Solution Approach 1:
The control unit continuously monitors the d.c. link voltage during disconnect mode operation. When the voltage rises by 50 V or more indicating potential overload, the control unit receives this feedback and automatically transitions from disconnect mode to short-circuit mode, thereby preventing energy loss and component damage while maintaining component protection.
Data Source
AI summary
A method for shutting down an electric machine having a pulse-controlled inverter in the event of a malfunction. Undesirable side effects during shut-down of the electric machine may be minimized and the regular machine operation may be maximized when the electric machine is first switched to a disconnect mode in which all switches of the pulse-controlled inverter are open and subsequently is switched to a short-circuit mode in which the switches connected to the high potential are open and the switches connected to the low potential are closed.