Vehicle Rotary Electric Machine Synchronous Rectification Start Control
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Solution Overview
Problem
Existing power generators for vehicles cannot reliably determine whether switching elements are short-circuited before starting synchronous rectification, leading to potential short-circuit faults and power generation disruptions.
Innovation Solution
A rotary electric machine with a multi-phase armature winding and a switching element set that forms a bridge rectification circuit, using an on/off-timing setter and driver to control switching elements, ensuring no short-circuit faults by detecting alternate upper-arm and lower-arm on-periods before initiating synchronous rectification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If synchronous rectification is started immediately after engine start or after suspension, then power generation can resume quickly, but short-circuit faults may occur due to undetected switching element abnormalities
Solution Approach 1:
The system performs preliminary detection of switching element abnormalities by monitoring diode energization periods before allowing synchronous rectification to start. The control device checks whether each switching element is abnormal during the diode conduction period, and only permits synchronous rectification operation after confirming all switching elements are normal, thus preventing short-circuit faults before they can occur.
Solution Approach 2:
The control device continuously monitors the operational state of switching elements by detecting diode energization periods and provides feedback control. When abnormalities are detected, the system adjusts the synchronous rectification operation accordingly, stopping or preventing operation until switching elements are confirmed normal, thereby ensuring reliable operation while enabling quick resumption when conditions are satisfied.
2Measurement precision
If switching element abnormalities are detected during diode energization period, then switching element status can be monitored, but abnormalities occurring prior to synchronous rectification start cannot be reliably detected
Solution Approach 1:
The system uses the diode as an intermediary element to detect switching element abnormalities. By monitoring the diode's energization period, which occurs naturally during the power generation cycle, the system can indirectly detect switching element status without requiring separate detection circuits or extending detection into periods when switching elements are definitely abnormal, thus achieving reliable detection within the available time window.
3Productivity
If synchronous rectification is started when phase voltage waveform is disturbed or switching element is short-circuited, then immediate power generation is achieved, but short-circuit fault between battery terminals occurs through upper-arm and/or lower-arm circuit sections
Solution Approach 1:
The control device applies preliminary anti-action by detecting switching element abnormalities during the diode energization period before synchronous rectification starts. When abnormalities are detected, the system prevents synchronous rectification operation from commencing, thereby counteracting the potential harmful effect of short-circuit faults before they can occur through the upper-arm and lower-arm circuit sections to the battery terminals.
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
Enables reliable start of synchronous rectification after verifying the absence of short-circuit faults, preventing power generation disruptions and ensuring safe operation by alternately controlling the on-periods of switching elements.
Implementation Method 1
a switching element set that rectifies a voltage induced in the armature winding, including a plurality of pairs of upper-arm and lower-arm switching elements
Implementation Method 2
a synchronous control start determiner that determines timing when an upper-arm on-period and a lower-arm on-period for each pair of the switching elements occur alternately as start timing of synchronous rectification
Data Source
AI summary
A rotary electric machine for a vehicle that is capable of starting synchronous rectification through switching elements after having ensured absence of a short circuit fault. The rotary electric machine includes a multi-phase armature winding, a switching element set that includes a plurality of pairs of upper-arm and lower-arm switching elements to form a bridge rectification circuit together with the armature winding, an on/off-timing setter that sets on/off-timing of each switching element, a switching element driver that drives each switching element at the on/off-timing set by the on/off-timing setter; and a synchronous control start determiner that determines timing when an energization period for the upper-arm switching element and an energization period for the lower-arm switching element occur alternately as start timing of the synchronous rectification.