Link-Side Insulation Measurement With Dynamic Impedance Switching
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Solution Overview
Problem
Existing measurement systems face limitations in operational voltage range, accuracy, and speed due to high leakage currents and impedance, particularly in link-side insulation systems, which restrict measurements to below 200-300V and hinder high-speed insulation resistance calculations.
Innovation Solution
A low-impedance measurement circuit with a discharge circuit and switching mechanism using relays or stacked FETs to isolate from chassis ground, dynamically switching between circuits based on voltage levels to ensure safe and accurate high-speed measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-impedance circuit design is used, then voltage measurements can be performed, but the measurement speed is limited due to increased capacitor charging/discharging times
Solution Approach 1:
The patent applies dynamics by making the circuit impedance adjustable rather than fixed. The system dynamically switches between high-impedance mode (for voltage measurements) and low-impedance mode (for fast insulation measurements) based on the measurement type required, thereby resolving the contradiction between measurement speed and measurement capability
Solution Approach 2:
The patent changes the impedance parameter of the measurement circuit based on the measurement requirements. By switching the circuit configuration, the impedance parameter is adjusted to match the specific measurement needs, enabling both slow accurate voltage measurements and fast insulation measurements without compromise
2Adaptability or versatility
If the operational voltage range is extended above 200-300V, then broader voltage measurement capability is achieved, but accuracy deteriorates due to high leakage currents
Solution Approach 1:
The patent uses dynamic switching between different circuit configurations based on the voltage level and measurement type. For high-voltage insulation measurements, the system switches to a configuration optimized for that specific measurement, thereby maintaining accuracy across the extended voltage range while avoiding the leakage current problems that would affect continuous operation
3Reliability
If Y-capacitance is present in the system, then electrical isolation is provided, but measurement speed decreases due to increased capacitor charging/discharging times
Solution Approach 1:
The patent extracts the Y-capacitance effect from the measurement path during fast insulation measurements. By switching to a dedicated fast measurement configuration, the system temporarily bypasses the Y-capacitance charging/discharging bottleneck, thereby achieving high-speed measurements while maintaining electrical isolation when needed
Data Source
AI summary
A circuit for measuring and managing voltage in an electrical system includes a low-impedance measurement circuit configured to perform high-speed voltage measurements when the voltage is less than 60V. A discharge circuit is configured to rapidly discharge Y-capacitance when the voltage is greater than 60V. A voltage detection circuit configured to measure a link voltage and determine whether the voltage exceeds 60V. A switching mechanism comprising at least one of a relay, stacked field-effect transistors (FETs), or a combination thereof, is configured to selectively isolate the low-impedance measurement circuit from chassis ground to ensure compliance with working and withstanding voltage requirements. A control circuit is configured to activate the discharge circuit if the measured link voltage exceeds 60V to reduce the voltage below 60V and enable the low-impedance measurement circuit once the voltage is within the safe operating range.