Patent Description:
<CIT> provides an insulation detection method and device, control equipment and an automobile, the insulation detection method is applied to an insulation detection circuit of the automobile, and the insulation detection circuit comprises a main positive relay, a main negative relay and a high-voltage bus ground insulation resistor which are connected with a power supply of the automobile. The insulation detection circuit further comprises an insulation detection relay and a divider resistor used for insulation detection, and the insulation detection method comprises the steps: controlling the automobile to enter a corresponding sampling mode according to the working condition of the automobile, wherein different working conditions correspond to different sampling modes; controlling the insulation detection relay to be closed and opened periodically according to the sampling mode, and acquiring voltage data; and calculating the ground insulation resistance of the high-voltage bus according to the voltage data.

<CIT> discloses an insulation detection circuit, an electric vehicle and a charging pile. The insulation detection circuit is applied to the electric vehicle and the charging pile, the insulation detection circuit comprises a pile end detection circuit, a vehicle end detection circuit, a boost circuit and a balance circuit, the pile end detection circuit comprises a first pile end detection module and a second pile end detection module, the vehicle end detection circuit comprises a first vehicle end detection module and a second vehicle end detection module, one end of the balance circuit is connected with a direct connection circuit, the other end of the balance circuit is connected with the boost circuit or the vehicle end circuit, the insulation resistor of the second pile end detection module and the insulation resistor of the second vehicle end detection module are connected in parallel, and the balance circuit is used for dividing the voltage of the second vehicle end detection module so as to balance the voltage of the second pile end detection module.

<CIT> describes a power supply apparatus for a vehicle comprising a voltage detection circuit that detects voltages of a plurality of battery modules. The voltage detection circuit comprises a multiplexer that switches the battery modules voltages of which are detected in a time sharing manner, and a voltage detection portion that detects the voltages of the battery modules switched by the multiplexer. In the power supply apparatus, a particular point of the battery module is connected to a chassis through a leakage detection resistance, and the voltage detection circuit detects a chassis voltage that is inducted to the both ends of the leakage detection resistance by switching the multiplexer of the voltage detection circuit to detect a leakage resistance based on the chassis voltage.

The following presents a summary to provide a basic understanding of one or more embodiments described herein. This summary is not intended to identify key or critical elements, or to delineate any scope of the particular embodiments and/or any scope of the claims. The sole purpose of the summary is to present concepts in a simplified form as a prelude to the more detailed description that is presented later. In one or more embodiments described herein, systems and/or methods are described that can facilitate isolation resistance monitoring for high voltage systems.

An embodiment includes an isolation resistance monitoring system comprising an electrical circuit. The electrical circuit further comprises one or more resistors and a voltage meter which measures voltage, such that the voltage measurement assists with monitoring isolation resistance, simultaneously, between a battery system of an electric vehicle and an electrical chassis of the electric vehicle, and between a direct current (DC) charging source external to the electric vehicle and the electrical chassis, wherein the DC charging source comprises a high voltage Electric Vehicle Supply Equipment (EVSE) system which is an external charging station for the electric vehicle. The isolation resistance monitoring system further comprising a first plurality of switches which electrically integrate the isolation resistance monitoring system with the battery system of the electric vehicle and a second plurality of switches which electrically integrate the isolation resistance monitoring system with the high voltage EVSE system.

Another embodiment includes an isolation resistance monitoring method. The isolation resistance monitoring method comprises monitoring, by an isolation resistance monitoring system, isolation resistance, simultaneously, between a battery system of an electric vehicle and an electrical chassis of the electric vehicle, and between a DC charging source external to the electric vehicle and the electrical chassis, wherein a voltage meter measures voltage to assist with the isolation resistance monitoring, wherein the DC charging source comprises a high voltage Electric Vehicle Supply Equipment (EVSE) system which is an external charging station for the electric vehicle. Integrating, by the system, the isolation resistance monitoring system with the battery system of the electric vehicle using a first plurality of switches. Integrating, by the system, the isolation resistance monitoring system with the high voltage EVSE system of the electric vehicle using a second plurality of switches and monitoring, by the system, isolation resistance, simultaneously, for the high voltage EVSE system and for one or more high voltage buses of the battery system during DC charging.

Another embodiment includes an isolation fault detection method. The isolation fault detection method comprises detecting, by an isolation resistance monitoring system, an isolation fault in a battery system, wherein one or more contactors of the battery system are configured to design an isolation test for detecting the isolation fault.

One or more exemplary embodiments are described below in the Detailed Description section with reference to the following drawings.

One or more embodiments are now described with reference to the drawings, wherein like referenced numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a more thorough understanding of the one or more embodiments. It is evident, however, in various cases, that the one or more embodiments can be practiced without these specific details.

The principal challenge addressed by the invention is that it can provide a system for simultaneously monitoring isolation resistance of two isolated high voltage systems, galvanically connected to one another, wherein one high voltage system can be the smartcell system of an electric vehicle and the other high voltage system can be an external DC charging source for the electric vehicle. The isolation resistance monitoring system can also detect isolation fault in different areas of the smartcell system, which can further assist with providing good drivability for the electric vehicle, even when an isolation fault can be present.

<FIG> illustrates a block diagram of an isolation resistance monitoring system integrated with two high voltage systems, in accordance with one or more embodiments described herein. The block diagram comprises electric vehicle <NUM>, isolation resistance monitoring system <NUM>, resistors <NUM> -<NUM>, voltage meter <NUM>, switches <NUM>-<NUM>, smartcell system <NUM>, high voltage EVSE system <NUM> and electrical chassis <NUM>.

In an embodiment, electric vehicle <NUM> can comprise an isolation resistance monitoring system <NUM>. Isolation resistance monitoring system <NUM> can be an electrical circuit comprising resistors <NUM>, <NUM>, and <NUM>, and voltage meter <NUM>. The isolation resistance monitoring system can monitor isolation resistance between the smartcell system <NUM> and the electrical chassis <NUM> of electric vehicle <NUM>, and it can simultaneously monitor isolation resistance between the high voltage Electric Vehicle Supply Equipment (EVSE) system and the electrical chassis <NUM>, wherein the EVSE system is an external DC charging station for electric vehicle <NUM>. Isolation resistance monitoring system <NUM> can be electrically integrated with the smartcell system <NUM> via switches <NUM> and <NUM>, wherein switches <NUM> and <NUM> can be respectively connected to each of the high voltage terminals of a high voltage bus of the smartcell system <NUM>. In a similar manner, isolation resistance monitoring system <NUM> can be electrically integrated with the high voltage EVSE system <NUM> via switches <NUM> and <NUM>. Switches <NUM> and <NUM> can further provide a connection between the isolation resistance monitoring system <NUM> and the electrical circuit of the smartcell system <NUM>, and they can allow the isolation resistance monitoring system to simultaneously monitor isolation resistance for the smartcell system and the high voltage EVSE system, during DC charging of electric vehicle <NUM>. Isolation resistance monitoring system <NUM> can be integrated with the electrical chassis <NUM> of the electric vehicle <NUM>, wherein the electrical chassis can be a reference point for the isolation resistance monitoring system <NUM>.

Voltage meter <NUM> can measure voltage through the smartcell system <NUM> and through the high voltage EVSE system <NUM> to assist the isolation resistance monitoring system <NUM> to monitor isolation resistance. Switches <NUM>, <NUM>, <NUM> and <NUM> can further assist the isolation resistance monitoring system <NUM> with measuring isolation resistance for electric vehicle <NUM>. Isolation resistance monitoring system <NUM> can be controlled by a software and it can be used to locate isolation fault in different areas of the smartcell system <NUM>, including isolation faults in cable harnesses, busbars, fuses, and other high voltage components of the smartcell system <NUM>.

<FIG> illustrates the architecture of the isolation resistance monitoring system, in accordance with one or more embodiments described herein. <FIG> comprises isolation resistance monitoring system <NUM>, resistors <NUM>-<NUM>, voltage meter <NUM>, smartcell system <NUM>, high voltage EVSE system <NUM>, electrical chassis <NUM>, and switches <NUM>-<NUM> of <FIG>, wherein resistors <NUM>, <NUM> and <NUM> are respectively represented as R1, R2 and R3, and switches <NUM>, <NUM>, <NUM> and <NUM> are respectively represented as S1, S2, S3 and S4.

In an embodiment, resistor R3 can be connected in parallel with voltage meter <NUM>. Resistors R1 and R2 can be connected in parallel with one another, and the parallel combination of resistor R3 and voltage meter <NUM> can be in series connection with the parallel combination of resistors R1 and R2. Switch S1 can be in series with resistor R1 and switch S2 can be in series with resistor R2 such that the isolation resistance monitoring system <NUM> can be galvanically connected with a high voltage bus of the smartcell system <NUM> via switches S1 and S2. The high voltage bus can be in parallel combination with one or more high voltage buses of smartcell system <NUM>. Similarly, switch S3 can be in series with resistor R1 and switch S4 can be in series with resistor R2 such that the isolation resistance monitoring system <NUM> can be galvanically connected with the smartcell system <NUM>, and with high voltage EVSE system <NUM>, wherein the high voltage EVSE system can be an external DC charging station, as discussed in one or more embodiments herein.

For measuring isolation resistance, switches S1, S2, S3 and S4 can be operated consecutively. Initially, all switches can be in the open position, switch S1 can be closed and the voltage through the circuit can be measured using the voltage meter <NUM>, switch S1 can be opened, and the procedure can be repeated for switch S2 to measure isolation resistance for the parallel combination of high voltage buses of smartcell system. The procedure of consecutively opening and closing the plurality of switches can be repeated for switches S3 and S4 to measure isolation resistance for the smartcell system and for the high voltage EVSE system, wherein the smartcell system and the high voltage EVSE system are galvanically connected during DC charging.

<FIG> illustrates the architecture of the isolation resistance monitoring system integrated with a smartcell system, in accordance with one or more embodiments described herein. <FIG> illustrates the architecture of the smartcell system, in accordance with one or more embodiments described herein. <FIG> and <FIG> comprise the smartcell system <NUM> and isolation resistance monitoring system <NUM> of <FIG>, contactors <NUM> - <NUM> of <FIG>, and smartcell battery pack <NUM>, smartcell board <NUM>, asynchronous motor (ASM) <NUM>, high voltage bus <NUM>, alternating current (AC) charging inlet <NUM>, and DC charging inlet <NUM> of <FIG>.

As discussed in one or more embodiments herein, the isolation resistance monitoring system <NUM> can be electrically integrated with the smartcell system <NUM> via switches S1 and S2 (also known as switches <NUM> and <NUM> per <FIG> and <FIG>), as well as via switches S3 and S4 (also known as switches <NUM> and <NUM> per <FIG> and <FIG>). The smartcell system topology comprises a smartcell battery pack <NUM> which can further comprise multiples of smartcell board <NUM>. Each smartcell board <NUM> can control a battery module comprising one or more cells. A master node can control each smartcell board <NUM> and their respective battery modules such that the smartcell battery pack can produce different levels of AC output voltage at the pack level and it can produce different levels of DC output voltage at the pack or module level. In the smartcell topology, a battery module can output up to <NUM> volts (V), and the one or more battery modules can be combined in series such that each series combination can be arranged to form three parallel strings of the battery modules. Each string can also comprise a combination of battery modules configured to form a high voltage bus <NUM> that can produce a galvanically isolated output of 400V. The <NUM> V battery modules on each string form the low voltage side of the smartcell system, which can be galvanically isolated from the high voltage buses on each string.

Due to the nature of the smartcell topology in conjunction with the architecture of the isolation resistance monitoring system <NUM>, the isolation resistance monitoring system <NUM> can be utilized for both AC and DC applications, for charging and non-charging use cases. The charging use cases can comprise DC charging of an electric vehicle via a high voltage EVSE system, during which the isolation resistance monitoring system can simultaneously monitor isolation resistance for the secondary circuit of the high voltage EVSE system and for the high voltage circuit of the smartcell system, including the high voltage buses and not including the low voltage, <NUM> V battery modules, by using switches S3 and S4. During DC charging, the isolated 400V bus, if alive, can also be monitored by using S1 and S2. Contactors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> can be closed for DC charging. The charging use cases can further comprise AC charging of the electric vehicle, during which isolation resistance can be monitored for the high voltage circuit of the smartcell system, including the high voltage buses and not including the low voltage, <NUM> V battery modules, by using switches S1 and S2. Contactors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> can be closed for AC charging. During either charging use case, the high voltage buses of the smartcell system can be energized to high voltage levels. Therefore, the solution can allow continuous isolation monitoring functionality for isolated high voltage buses with various voltage levels.

The non-charging use cases can comprise isolation resistance measurement, as part of an isolation test, to detect isolation fault prior to AC and/or DC charging, during short-term and long-term parking, before every start-up, during every power-down, and before and after every service action of the electric vehicle. For isolation resistance measurement during non-charging use cases, the high voltage buses of the smartcell system can be energized to safe voltage levels by the smartcell battery pack <NUM>, wherein safe voltage levels can include voltage levels under <NUM> V for AC applications and voltage levels under <NUM> V for DC applications.

The isolation resistance monitoring system <NUM> can detect isolation fault in the smartcell system <NUM>, wherein the fault can be in cable harnesses, busbars, fuses, and other high voltage components of the smartcell system <NUM>. Energizing the high voltage buses to non-hazardous voltage levels, for isolation resistance measurement for detecting isolation fault, can further allow service technicians to troubleshoot isolation faults much easier. The fault detection sequence, which is described in greater detail in subsequent figures, can involve closing and opening several combinations of contactors <NUM> through <NUM> illustrated in the smartcell topology. This can facilitate isolation fault location in the smartcell system <NUM> prior to AC and/or DC charging, during short-term and long-term parking, before every start-up, during every power-down, before and after every service action, and before high voltage energization of the smartcell battery pack. The smartcell system <NUM> further comprises AC charging inlet <NUM> and DC charging inlet <NUM>, and it is integrated with an asynchronous motor <NUM> (ASM <NUM>). The ASM is also known as the electric front axle drive (EFAD) since it drives the front axle of the electric vehicle. The isolation resistance monitoring system can employ the isolation fault detection sequence such that depending on where an isolation fault is detected in the smartcell system, it can prevent AC charging, DC charging or front wheel drive of the vehicle, by opening the respective contactors to the AC charging inlet, DC charging inlet and the ASM, and it can prevent energization of the high voltage buses.

<FIG> illustrates an isolation resistance monitoring method that facilitates isolation resistance monitoring, in accordance with one or more embodiments described herein. Repetitive description of like elements and/or processes employed in respective embodiments is omitted for sake of brevity.

In an embodiment, environment <NUM> can comprise, at <NUM>, an isolation resistance monitoring method which can facilitate monitoring, by an isolation resistance monitoring system, isolation resistance, simultaneously, for a smartcell system of an electric vehicle, and for a DC charging source external to the electric vehicle, wherein a voltage meter measures voltage to assist with the isolation resistance monitoring.

<FIG> illustrates a flow diagram of an isolation resistance monitoring method that facilitates isolation resistance monitoring and isolation fault detection, in accordance with one or more embodiments described herein.

In an embodiment, environment <NUM> can comprise, at <NUM>, an isolation resistance monitoring method which can facilitate monitoring, by an isolation resistance monitoring system, isolation resistance, simultaneously, for a smartcell system of an electric vehicle, and for a DC charging source external to the electric vehicle, wherein a voltage meter measures voltage to assist with the isolation resistance monitoring. At <NUM>, the isolation resistance monitoring method can facilitate detecting, by an isolation resistance monitoring system, an isolation fault in the smartcell system, wherein one or more contactors of the smartcell system are configured to design an isolation test for detecting the isolation fault.

<FIG> illustrates a flow diagram of an isolation resistance monitoring method that facilitates isolation fault detection, in accordance with one or more embodiments described herein. Repetitive description of like elements and/or processes employed in respective embodiments is omitted for sake of brevity. <FIG> is to be understood in conjunction with <FIG> and <FIG> where the smartcell system architecture is addressed.

In an embodiment, one or more contactors of a smartcell system can be configured to design an isolation test for detecting isolation fault, using the isolation resistance monitoring system, due to one or more components in the smartcell system. The isolation test can comprise two isolation test sequences, respectively, for a first and a second use case. The first use case comprises isolation fault detection in the smartcell system prior to AC charging and/or DC charging. The second use case comprises isolation fault detection in the smartcell system during short-term and long-term parking, before every start-up, during every power-down, and before and after every service action of an electric vehicle.

In <FIG>, the first isolation test sequence is described by steps <NUM> -<NUM> which address the first use case comprising isolation fault detection in the smartcell system prior to AC charging and/or DC charging. Initially, all contactors can be in the open position. At <NUM>, contactors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> (as illustrated in <FIG>) can be closed, and the system can be energized by the smartcell battery pack <NUM> to low DC voltage levels at <NUM>, followed by isolation resistance measurement of the smartcell system <NUM> at <NUM>. If an isolation failure is detected in the system, charging can be prevented at <NUM>. If no isolation fault is detected, the test can be concluded by opening contactors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, at <NUM>, and the smartcell battery pack can be allowed to be charged either via an AC charging source or a DC charging source, at <NUM>. Further isolation resistance monitoring of the smartcell system can operate upon a request.

The second isolation test sequence is described by steps <NUM>-<NUM> which address the second use case comprising isolation fault detection in the smartcell system <NUM> during short-term and long-term parking, before every start-up, during every power-down, and before and after every service action of an electric vehicle. Initially, all contactors can be in the open position. At <NUM>, contactors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> (as illustrated in <FIG>) can be closed, and the system can be energized by the smartcell battery pack <NUM> to low DC voltage levels at <NUM>.

At <NUM>, the isolation resistance of the smartcell system <NUM> can be measured by the isolation resistance monitoring system102. If no isolation faults can be detected, high voltage energization of the smartcell system <NUM> can be allowed at <NUM>, and if an isolation fault can be detected, contactors <NUM>, <NUM>, <NUM> and <NUM> can be disconnected at <NUM>.

If no isolation fault can be detected after step <NUM>, it can imply that the fault exists within the onboard section of the AC charging bus, since contactors <NUM>, <NUM>, <NUM>, and <NUM> can provide a connection between the smartcell system <NUM> and the AC charging inlet <NUM>. Thus, AC charging can be prevented, and high voltage energization of the smartcell system can be allowed at <NUM>. If an isolation fault can be detected after step <NUM>, contactors <NUM> and <NUM> can be opened at <NUM>.

If no isolation fault can be detected after step <NUM>, it can imply that the fault exists within the onboard section of the DC charging bus, since contactors <NUM> and <NUM> can provide a connection between the smartcell system <NUM> and the DC charging inlet <NUM>. Thus, DC charging can be prevented, and high voltage energization of the smartcell system can be allowed at <NUM>. If an isolation fault can be detected after step <NUM>, contactors <NUM> and <NUM> can be opened at <NUM>.

If no isolation fault can be detected after step <NUM>, it can imply that the fault exists with ASM <NUM>, since contactors <NUM> and <NUM> can provide a connection between the smartcell system <NUM> and ASM <NUM>. Thus, front wheel drive can be prevented, and high voltage energization of the smartcell system can be allowed at <NUM>. If an isolation fault can be detected after step <NUM>, high voltage energization can be prevented at <NUM>, and the test can be concluded.

Claim 1:
An isolation resistance monitoring system (<NUM>), comprising:
an electrical circuit, comprising:
one or more resistors (<NUM>, <NUM>, <NUM>); and
a voltage meter (<NUM>) which measures voltage, such that the voltage measurement assists with monitoring isolation resistance, simultaneously, between a battery system (<NUM>) of an electric vehicle (<NUM>) and an electrical chassis (<NUM>) of the electric vehicle (<NUM>), and between a direct current, DC, charging source external to the electric vehicle (<NUM>) and the electrical chassis (<NUM>), wherein the DC charging source comprises a high voltage Electric Vehicle Supply Equipment, EVSE, system (<NUM>) which is an external charging station for the electric vehicle (<NUM>),
the isolation resistance monitoring system (<NUM>) further comprising:
a first plurality of switches (<NUM>, <NUM>) which electrically integrate the isolation resistance monitoring system (<NUM>) with the battery system (<NUM>) of the electric vehicle (<NUM>); and
a second plurality of switches (<NUM>, <NUM>) which electrically integrate the isolation resistance monitoring system (<NUM>) with the high voltage EVSE system (<NUM>).