Isolation Capacitor Battery Voltage Sensing Circuit
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Solution Overview
Problem
Conventional battery cell voltage measuring apparatuses require high withstanding voltage switch devices, leading to increased production costs due to the need for expensive components to handle high voltages in electric or hybrid electric vehicles.
Innovation Solution
An apparatus and method using an isolation capacitor to measure battery cell voltage, employing a first and second switching unit, voltage charging units, and a cell voltage sensing unit with a voltage amplifier and A/D converter to isolate high voltage from the switching units, allowing measurement with low withstanding voltage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high voltage battery cells are directly connected to ground for voltage measurement, then voltage measurement can be performed, but high withstanding voltage switch devices are required which increases production costs
Solution Approach 1:
The patent introduces an isolation capacitor as an intermediary component between the high voltage battery cell and the voltage measurement circuit. The capacitor isolates the high voltage from the measurement circuit, allowing low withstanding voltage devices to be used while still enabling accurate voltage measurement through capacitive coupling.
Solution Approach 2:
The patent divides the voltage measurement system into separate stages: a first switching unit that handles high voltage battery cell selection, a second switching unit that handles low voltage measurement signals, and an isolation capacitor that bridges these stages. This segmentation allows each component to operate at appropriate voltage levels, reducing overall system cost.
2Reliability
If high withstanding voltage switch devices are used to handle high voltage in voltage measurement, then reliable voltage measurement is achieved, but device cost increases
Solution Approach 1:
The isolation capacitor serves as a mediator that transfers voltage information from the high voltage domain to the low voltage measurement domain without requiring the measurement circuit components to withstand high voltage, thus maintaining reliability while using cheaper low voltage rated devices.
Solution Approach 2:
The patent creates a low voltage copy of the high voltage battery cell voltage through capacitive coupling. The isolation capacitor and second switching unit generate a replicated voltage signal that mirrors the high voltage cell voltage but at safe, low voltage levels suitable for standard measurement devices.
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 stable measurement of high voltage battery cell voltages using low withstanding voltage devices, reducing production costs by isolating the high voltage from the voltage sensing unit.
Implementation Method 1
a first voltage charging unit connected between the first and second conductive lines to primarily charge a cell voltage; a second voltage charging unit for relaying the charged voltage stored in the first voltage charging unit
Data Source
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AI summary
An apparatus for measuring a battery cell voltage includes a battery having a cell group; a first switching unit for selectively connecting both terminals of each battery cell of the cell group to conductive lines; a first voltage charging unit connected between the conductive lines to primarily charge a cell voltage; a second voltage charging unit for relaying the charged voltage in the first voltage charging unit for secondary charging; a cell voltage sensing unit for sensing the voltage charged in the second voltage charging unit; and a second switching unit for inter¬ connecting the voltage charging units in the charged voltage relaying mode and isolating the voltage charging units in the charged voltage sensing mode. This apparatus realizes isolation between a high voltage battery and a voltage sensing unit, thereby allowing voltage sensing of each battery cell included in a high voltage battery using a part with low withstanding voltage.