Vehicular AC Generator Voltage Control Mitigating Ripple
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Solution Overview
Problem
Existing output voltage control apparatuses for vehicular AC generators fail to maintain a generator output voltage close to a reference voltage due to ripple components in the detection voltage, resulting in insufficient voltage values.
Innovation Solution
An output voltage control apparatus that includes a control unit with a voltage detection circuit, comparison circuit, ON period counter, and memory, which compares detection voltage with a reference voltage, counts up during low output sections, and stores a final count value to determine the ON period in the next control period, effectively mitigating the impact of ripple components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed frequency type output voltage control apparatus is used to control the generator output voltage, then the control can be easily made by a microcomputer, but the generator output voltage cannot be made sufficiently large due to the ripple component in the detection voltage
Solution Approach 1:
The patent applies preliminary action by counting up the ON period counter only during low output sections (when detection voltage is lower than reference voltage) before the ripple component causes the voltage to exceed the reference. This anticipatory counting during the low periods compensates for the upcoming high periods, ensuring the average output voltage reaches the desired level without being limited by the ripple peaks.
2Difficulty of detecting and measuring
If the voltage detection circuit is connected to the output side of the rectifier unit to detect the generator output voltage, then the detection is straightforward, but the detection voltage includes a ripple component that causes the ON period to be controlled too short
Solution Approach 1:
The patent segments the control period into low output sections (when detection voltage is below reference voltage) and high output sections (when detection voltage exceeds reference voltage due to ripple). The ON period counter is configured to count up only during the low output sections, effectively separating the counting function from the ripple-affected high voltage periods. This segmentation allows the system to use the simple rectifier output for detection while achieving precise voltage control by ignoring the ripple-distorted portions.
3Speed
If the ON period is controlled based on the detection voltage including ripple component, then the control responds to instantaneous voltage changes, but the generator output voltage is controlled to be lower than the reference voltage
Solution Approach 1:
The patent implements periodic action by repeating the control process through multiple control periods, with the ON period counter accumulating counts of the low output sections over successive periods. The memory circuit stores the final count value from each control period, and this accumulated information is used to determine the ON period for the next control period. This periodic accumulation smooths out the ripple effects while maintaining responsive control.
Data Source
AI summary
There is provided an output voltage control apparatus for a vehicular AC generator in which a generator output voltage including a ripple component can be made to more approach a reference voltage. The control apparatus includes a comparison circuit to compare a detection voltage including a ripple component with a reference voltage and to output an effective comparison output in each of low output sections in which the detection voltage is lower than the reference voltage by the ripple component, an on period counter to count up, in a count enable period set in each of the control periods, a count value while adding the count value in each of the low output sections based on the effective comparison output, and a memory circuit to store a final count value in the count enable period in each of the control periods.