A battery system includes a battery pack including a plurality of battery cells a pressure sensor located inside the battery pack to measure an internal pressure of the battery pack every sampling cycle; and a battery management system calculating a reference pressure based on an average of internal pressures measured at sampling cycles for a sampling period, calculating a pressure fluctuation amount based on a difference of the internal pressure measured every sampling cycle from the reference pressure, and determining that a thermal event has occurred in the battery pack if the internal pressure measured every sampling cycle increases consecutively at least two times when the pressure fluctuation amount is greater than or equal to a predetermined threshold pressure.

A method for detecting an isolation fault in an isolation resistance between a positive and negative high-voltage bus rail and a vehicle chassis on a high-voltage propulsion side of a high-voltage system of an electric or hybrid-electric vehicle. The high-voltage system is split into a battery side and propulsion side by means of two high-voltage contactors located in the positive and negative high-voltage bus rails. The propulsion side includes first and second capacitors connected in series across the positive and negative bus rails, a common junction of the first and second capacitors connected to the chassis. The method supplies a low-voltage output to the positive and negative bus rails to charge the capacitors; and determines, based on charging current, voltage level or energy level of the capacitors, whether an isolation fault is present between the positive and/or negative high-voltage bus rail and the vehicle chassis on the propulsion side.

A method and device for monitoring insulation between a DC bus and protective earth, wherein the bus is connected with a DC source. Terminals of the source are connected to protective earth by a first electrical network during a first timespan, and transient first electrical values related to the first network at a plurality of time steps in the first timespan are measured. A first steady state value is calculated using a plurality of first measurement points at the plurality of first time steps. Further, the terminals of the source are connected to protective earth by a second electrical network, during a second timespan, and transient second electrical values related to the second network at a plurality of second time steps in the second timespan are measured. A second steady state value is calculated using a plurality of second measurement points at the plurality of second time steps. An indication of insulation resistances between the terminals of the source and protective earth is determined based on the calculated steady state values of the first electrical value and the second electrical value.

An apparatus for calculating battery resistance according to an embodiment of the present invention can include a measurement circuit connected between one terminal among a positive (+) terminal and a negative (−) terminal of a battery pack and a chassis, a voltage measurement unit that measures a voltage from the measurement circuit, and an insulation resistance calculation unit that calculates insulation resistance of the battery pack based on the voltage measured by the voltage measurement unit. When the calculated insulation resistance is less than a preset threshold, the insulation resistance calculation unit can recalculate the insulation resistance based on an amount of change in voltage of the battery pack over time.

An active isolation detection method may be used with an electrical system having a battery pack connected to a high-voltage bus. The bus has positive and negative bus rails, each having a respective rail-to-ground voltage. The method may include connecting variable resistance element to the high-voltage bus, and determining input information indicative electrical characteristics of the battery pack, the high-voltage bus, and/or a charging station. The method includes varying a bias resistance of the high-voltage bus, via control of the variable resistance element, e.g., via duty cycle control of a binary switch in series with a bias resistor, to produce a varied bias resistance based on the input information. A target voltage shift is achieved on the high-voltage bus as a target level of change in one of the rail-to-ground voltages. An isolation resistance of the electrical system is determined via the controller using the varied bias resistance.

Electrical circuits, systems, methods, and/or computer program products that can facilitate isolation resistance monitoring for high voltage buses are addressed. In one example, a system can comprise an electrical circuit further comprising one or more resistors and a voltage meter which measures voltage, such that the voltage measurement assists with monitoring isolation resistance, simultaneously, for a smartcell system of an electric vehicle, and for a direct current (DC) charging source external to the electric vehicle.

A series tee splitter comprises a primary electromagnetic transmission line and a secondary electromagnetic transmission line that is placed in a series path with the primary electromagnetic transmission line, wherein a load is attached to the end of the secondary electromagnetic transmission line and a network analyzer is connected to opposite ends of the primary electromagnetic transmission line to measure a load impedance. This configuration increases the high impedance measurement limit of the network analyzer normally seen for reflection measurements. The series tee splitter can be electrically small to provide broadband impedance information.

A method and device for monitoring insulation between a DC bus and protective earth, wherein the bus is connected with a DC source. Terminals of the source are connected to protective earth by a first electrical network during a first timespan, and transient first electrical values related to the first network at a plurality of time steps in the first timespan are measured. A first steady state value is calculated using a plurality of first measurement points at the plurality of first time steps. Further, the terminals of the source are connected to protective earth by a second electrical network, during a second timespan, and transient second electrical values related to the second network at a plurality of second time steps in the second timespan are measured. A second steady state value is calculated using a plurality of second measurement points at the plurality of second time steps. An indication of insulation resistances between the terminals of the source and protective earth is determined based on the calculated steady state values of the first electrical value and the second electrical value.

The present invention relates to an apparatus capable of measuring an insulation resistance of a battery, and according to the apparatus capable of measuring the insulation resistance of the present invention. A voltage measurement unit may measure a voltage with respect to a potential of a negative terminal of a battery rather than the ground, and thus parameters requiring a high precision may be measured using one device, thereby reducing cost, and, because a first sensing substrate and a second sensing substrate are separated, different potentials may be used as the ground, thereby securing a better insulation performance between the first sensing substrate that is an HV side and the second sensing substrate that is an LV side.

Disclosed is an insulation detection circuit for voltage balance, including a bus battery, a bus positive voltage dividing circuit, a bus negative voltage dividing circuit, a differential amplification circuit and a micro controller unit (MCU) module. The bus battery is respectively connected with the bus positive voltage dividing circuit and the bus negative voltage dividing circuit, the bus positive voltage dividing circuit and the bus negative voltage dividing circuit is respectively connected with the differential amplification circuit, and the differential amplification circuit being connected with the MCU module; the bus battery is configured for supplying power to each module; the bus positive voltage dividing circuit is configured for converting a positive voltage of the bus from high voltage to detectable low voltage; the bus negative voltage dividing circuit is configured for converting a negative voltage the bus from high voltage to detectable low voltage.