Sensor with self-supply negative rail for

Abstract

A battery management system configured to be coupled to at least one battery module, the battery management system comprising: a contact configured to be coupled between the at least one battery module and a machine; a sensor configured to sense an electrical parameter of the at least one battery module; and a control circuit configured to receive an output of the sensor and determine a value of the electrical parameter. The sensor includes: an inverting charge pump coupled to receive a positive supply voltage and generate a negative supply voltage; and a differential amplifier coupled to the at least one battery module and supplied with the positive supply voltage and the negative supply voltage, the differential amplifier configured to generate an output representative of the electrical parameter.

Description

Technical Field

[0001] This document relates generally to a battery management system for an electrified machine, and specifically to a technique for monitoring an electrical parameter of a battery. Background Art

[0002] Sensors that use operational amplifiers or differential amplifiers in their designs utilize a positive voltage supply (positive rail) and a negative voltage supply (negative rail) to be able to accurately output true zero volts. For example, operational amplifiers have voltage swing specifications that define how close the output voltage of the operational amplifier can be to the supply voltage. As a specific example, for an operational amplifier supplied with a positive supply of +15V and a negative supply of -15V and having a 0.3V voltage swing, the output can reach +14.7V and -14.7V. However, for an operational amplifier supplied with only a positive supply of +15V (with the negative supply input of the operational amplifier grounded) and having a 0.3V voltage swing, the output can reach +0.3V and +14.7V. Thus, it is impossible for an operational amplifier to output zero volts unless it is supplied with both a positive supply and a negative supply. A negative supply is required to force the output voltage toward the negative supply rail.

[0003] US7952327 describes an assembled battery total voltage detection and leakage detection device with reduced size and reduced manufacturing cost. By connecting the output of the positive electrode resistance voltage divider circuit composed of resistors to the + input of the differential amplifier and connecting the output of the negative electrode resistance voltage divider circuit composed of resistors to the - input of the amplifier, the total voltage detection is performed at the measurement time of the total voltage of the assembled battery, and by connecting the output of the positive electrode resistance voltage divider circuit to the + input of the amplifier and connecting the + input of the amplifier to the negative input of the differential amplifier to measure the output voltage of the amplifier, leakage detection is performed at the leakage detection time. The total voltage detection and leakage detection can be performed without the need for an isolation type voltage sensor, an isolation power supply, an optical coupler, etc. Summary of the invention

[0004] By using various techniques of the present disclosure, a sensor (e.g., part of a battery management system) can generate its own negative voltage supply so that the sensor's operational amplifier can generate a true zero volt output using the negative voltage supply and an externally provided positive voltage supply.

[0005] In some aspects, the present disclosure relates to a battery management system, which is configured to be connected to at least one battery module, the battery management system comprising: contacts, which are configured to be connected between the at least one battery module and a machine; a sensor, which is configured to sense an electrical parameter of the at least one battery module; and a control circuit, which is configured to receive an output of the sensor and determine a value of the electrical parameter, the sensor comprising: an inverting charge pump, which is connected to receive a positive supply voltage and generate a negative supply voltage; and a differential amplifier, which is connected to the at least one battery module and is supplied with the positive supply voltage and the negative supply voltage, and the differential amplifier is configured to generate an output representing the electrical parameter.

[0006] In some aspects, the present disclosure relates to a battery management system, the battery management system being configured to be coupled to at least one battery module, the battery management system comprising: a first contact, the first contact being configured to be coupled between the at least one battery module and a machine; a resistor, the resistor being coupled in series with a second contact, wherein the resistor and the second contact are coupled in parallel with the first contact; a first sensor, the first sensor being configured to sense a first electrical parameter of the at least one battery module; a second sensor, the second sensor being coupled to a second side of the first contact, the second sensor being configured to sense a second electrical parameter of the at least one battery module as seen by the machine; and a control circuit, the control circuit being configured to receive corresponding signals of the first sensor and the second sensor. Output, and determine the value of the first electrical parameter and the value of the second electrical parameter, the first sensor includes: an inverting charge pump, the inverting charge pump is connected to receive a positive supply voltage and generate a first negative supply voltage; and a differential amplifier, the differential amplifier is connected to the at least one battery module and is supplied with the positive supply voltage and the first negative supply voltage, the differential amplifier is configured to generate an output representing the first electrical parameter, the second sensor includes: an inverting charge pump, the inverting charge pump is connected to receive a positive supply voltage and generate a second negative supply voltage; and a differential amplifier, the differential amplifier is connected to the at least one battery module and is supplied with the positive supply voltage and the second negative supply voltage, the differential amplifier is configured to generate an output representing the second electrical parameter.

[0007] In some aspects, the present disclosure relates to a sensor configured to sense an electrical parameter of at least one battery module, the sensor comprising: an inverting charge pump connected to receive a positive supply voltage and generate a negative supply voltage; a differential amplifier connected to the at least one battery module and supplied with the positive supply voltage and the negative supply voltage, the differential amplifier being configured to generate an output representing the electrical parameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a perspective view of an example of an electrified machine in which the various techniques of the present disclosure may be implemented.

[0009] Figure 2 is a simplified block diagram of an example of a portion of a battery management system in which the various techniques of this disclosure may be implemented.

[0010] Figures 3A-3C A schematic diagram of an example of a sensor according to the present disclosure is depicted. DETAILED DESCRIPTION

[0011] Examples according to the present disclosure relate to methods and systems for a sensor (e.g., part of a battery management system) that can generate its own negative voltage supply so that an operational amplifier of the sensor can generate a true zero volt output using the negative voltage supply and an externally provided positive voltage supply.

[0012] The electrified machine is powered by a battery rather than an engine. A battery pack may include one or more battery modules, and a battery module may include one or more battery cells. A battery module may include a battery cell monitoring circuit to monitor, among other things, the voltage and temperature of the battery cells in the battery module.

[0013] The electrified machine includes a battery management system (BMS) to monitor, among other things, the status and health of the battery modules. The BMS may include an electronic control module (ECM) that communicates with various battery module monitoring circuits to receive and aggregate information from the various battery modules. The ECM may coordinate the operation of all battery modules. The battery modules may be connected to each other, such as in series and in parallel, using high voltage, high current electrical control contacts of contactors.

[0014] The battery module monitoring circuit may include a sensor that uses an operational amplifier or differential amplifier in its design that requires a positive voltage supply (positive rail) and a negative voltage supply (negative rail) to be able to accurately output true zero volts. For accuracy, it is desirable for the ECM to know when the voltage of the battery module is actually zero volts. However, for a sensor that includes an operational amplifier that is supplied with a positive voltage supply (with the negative voltage supply input of the operational amplifier being grounded) and has a voltage swing, it is impossible for the operational amplifier to output zero volts.

[0015] The negative voltage supply is used to force the output voltage of the operational amplifier towards the negative rail. If only the positive voltage supply is used, inaccurate measurements may occur at high voltages. Additionally, the ECM does not know if the voltage of the battery module is actually zero volts, or if, for example, the contacts of the contactor are open. The negative rail is needed to provide a differential signal and output true zero volts from the amplifier.

[0016] The inventors have recognized the need to provide a negative voltage supply to the sensors of the battery module monitoring circuit. The inventors have also recognized that adding the negative voltage supply to the ECM would be too expensive. To address this problem, the inventors have designed sensors to generate the negative voltage supply, rather than the ECM providing the negative voltage supply to the sensors. The negative voltage supply can be used as a negative rail for the operational amplifier and differential amplifier of the sensor.

[0017] Figure 1 is a perspective view of an example of an electrified machine in which the various techniques of the present disclosure may be implemented. Figure 1 A non-limiting example of an electrified machine 100 is shown in FIG. The electrified machine 100 may be at least partially powered by a battery (as will be referred to below). Figure 2 The electric machine 100 may be any machine or vehicle of the type described herein. The electric machine 100 may be a mining truck (as depicted), or any other on-road or off-road machine or vehicle. In some examples, the electric machine 100 may include a machine frame 102 that supports at least an operator control station 104 and a dump body 106. Ground engaging elements 108 (such as wheels and / or tires) may also be supported by the machine frame 102 and may be powered by a drive system discussed below that is supported by the machine frame 102.

[0018] Figure 2 2 is a simplified block diagram of an example of a portion of a battery management system 200 that can implement various techniques of the present disclosure. The battery management system 200 is configured to be coupled to at least one battery module 202A-202F. A battery module, such as battery module 202A, can include one or more battery cells 204A-204N. The battery modules can be coupled together to form a battery pack. For example, the battery modules 202A-202F can be coupled together to form a battery pack 206.

[0019] The battery modules may be arranged in strings. For example, the battery modules 202A, 202B may be connected in series to form a first string 208A. The battery modules 202C, 202D and the battery modules 202E, 202F may be similarly connected to form a second string 208B and a third string 208C, respectively.

[0020] The string may include a manual disconnect switch toward or at the middle of the string.For example, string 208A may include a manual disconnect switch 210A between battery module 202A and battery module 202B.

[0021] In some examples, the string may include a first contact 212A and a second contact 212B, wherein the first contact 212A and the second contact 212B are contacts coupled between the battery module and the electrified machine. The first contact 212A and the second contact 212B may be a machine portion of a contactor that includes an operating coil and contacts that are actuated when the operating coil is energized or de-energized. By including, for example, the first contact 212A and the second contact 212B, the first string 208A may be isolated from the remaining strings 208B, 208C, for example, during a fault condition.

[0022] exist Figure 2 In the example shown in , each string may include a current sensor, such as current sensor 214 of string 208A, to sense the current through the string. Although depicted as being located on the negative side of the string, current sensor 214 may alternatively be located on the positive side of the string. In some examples, each string may include a fuse.

[0023] The strings 208A-208C may be connected in parallel to increase the available Figure 1 The capacity of the electrified machine 100. Can be connected to Figure 2 A non-limiting list of examples of battery management system 200 and battery-powered components include traction inverters, hydraulic inverters, and A / C compressors.

[0024] Battery management system 200 may be coupled to electrified machine 100 via contacts 216A, 216B. In some examples, it may be desirable to include resistor 218 coupled in series with contact 220, wherein resistor 218 and contact 220 are coupled in parallel with contact 216A. Resistor 218 may be a pre-charge resistor to control the flow of current from battery modules 202A-202F.

[0025] The battery management system 200 may include a sensor 222A configured to sense a representation of an electrical parameter of the battery modules 202A-202F. The sensor 222A may be coupled to a first side of the contact 216A. For example, the sensor 222A may be a voltage sensor configured to sense a representation of a voltage across the battery pack 206. The sensor 222A may measure a voltage, such as at a terminal of the battery pack 206.

[0026] In some examples, the battery management system 200 may include a sensor 222B configured to sense an electrical parameter of the battery modules 202A-202F. The sensor 222B may be coupled to a second side of the contact 216A and configured to sense an electrical parameter of at least one battery module as seen by the machine. For example, the sensor 222B may be a voltage sensor configured to sense an electrical parameter of the battery modules 202A-202F. Figure 1 The voltage across the battery pack 206 as seen by the electrified machine 100. In some examples, sensor 222B is used to determine the pre-charge level. Basically, the battery management system 200 can monitor the battery side voltage using sensor 222A, and then during pre-charge, sensor 222B can indicate the degree of charge of the machine side capacitor. The battery management system 200 will not close the +main contactor until the two voltages are within a certain voltage of each other.

[0027] As described above, the inventors have recognized the need to provide a negative voltage supply to the sensors of the battery module monitoring circuit. Figures 3A-3C As described, the inventors have designed a sensor to generate a negative voltage supply, rather than having the ECM provide the negative voltage supply to the sensor. The negative voltage supply can be used as a negative rail for the operational amplifier and differential amplifier of the sensor.

[0028] Figures 3A-3C A schematic diagram depicting an example of a sensor 300 according to the present disclosure. The sensor 300 is Figure 2 The sensor 300 may include an inverting charge pump circuit 302, the inverting charge pump circuit including an inverting charge pump U2, the inverting charge pump including pins connected to various components, such as Figure 3B As shown in Figure 3B As seen in FIG. 1 , an inverting charge pump U2 can be connected to receive a positive supply voltage at VIN, such as +15 V, and generate a negative supply voltage at VOUT, such as -15 V. In this way, the sensor 300 can generate the negative rail itself, rather than supplying the negative rail via an external circuit (e.g., by an ECM).

[0029] Both the positive voltage supply and the negative supply voltage are used by the operational amplifier circuit and the differential amplifier circuit of the sensor 300 to provide a true zero output. The supply voltages for the operational amplifiers U3, U4, and U6 are depicted at 304. Each of the operational amplifier circuits U3, U4, and U6 receives a positive supply voltage of +15V and a negative supply voltage of -15V generated by the inverting charge pump circuit 302.

[0030] The supply voltages for differential amplifier U1 are depicted at 306. Differential amplifier U1 receives a positive supply voltage of +15V and a negative supply voltage of -15V generated by inverting charge pump circuit 302. By using both a positive voltage supply and a negative voltage supply, the operational amplifier and the differential amplifier can accurately output true zero volts and improve the accuracy of sensor 300.

[0031] The sensor 300 may also include a differential amplifier circuit 308 including a differential amplifier U1 coupled to a voltage divider circuit 310. The differential amplifier circuit 308 may be coupled to one or more battery modules (eg, Figure 2 The voltage divider circuit 310 may be coupled between the terminals of at least one battery module and the differential amplifier circuit. The differential amplifier U1 may be configured to generate an output representing an electrical parameter (eg, voltage) of the battery module.

[0032] The output of the differential amplifier circuit 308 may be applied to a clamp circuit 312 formed by operational amplifiers U3 and U4, wherein the clamp circuit 312 is configured to clamp the output of the differential amplifier. The clamp circuit 312 is supplied with a positive supply voltage and a negative supply voltage. The operational amplifiers U3 and U4 may be coupled to receive a reference voltage from a buffered voltage reference circuit 314, which may include a buffered voltage reference VR1 coupled to various components.

[0033] In some examples, sensor 300 can include protection circuit 316. Protection circuit 316 can include operational amplifier U6 coupled to various components.

[0034] The output of the sensor may be provided to the control circuit 318 via one or more connectors 320. The control circuit 318 may be configured to receive the output of the sensor and determine a value of an electrical parameter (e.g., voltage). For example, the voltage of at least one battery module sensed by the sensor 300 may be provided to the control circuit 318. In particular, the control circuit 318 may determine Figure 2 The voltage of one or more of the battery modules 202A-202F is too low and determines that the battery module should be recharged. Alternatively, the control circuit 318 may determine that a fault condition exists and determine that one or more contacts should be opened, such as Figure 2 The contacts 212A, 212B are connected to isolate one string (such as string 208A) from the other strings.

[0035] like Figure 3C As seen in FIG. 1 , the control circuit 318 may receive a first sensed electrical parameter, and in some instances, a second (or even more) sensed electrical parameter. For example, Figure 2 The battery management system 200 includes two sensors 222A and 222B. Each sensor can be similar to Figures 3A-3C The sensor 300 and outputs the sensed electrical parameters to the control circuit 318.

[0036] Industrial Applicability

[0037] Sensors that use operational amplifiers or differential amplifiers in their design require a positive voltage supply (positive rail) and a negative voltage supply (negative rail) to be able to accurately output true zero volts. Providing the positive and negative voltage supplies externally to the sensor can be expensive.

[0038] The present disclosure relates to a sensor for a battery management system. Using various techniques of the present disclosure, a sensor can generate its own negative voltage supply so that an operational amplifier of the sensor can generate a true zero volt output using the negative voltage supply and an externally provided positive voltage supply.

[0039] The above detailed description is intended to be illustrative rather than limiting.The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A battery management system (200), the battery management system being configured to be coupled to at least one battery module (202A), the battery management system (200) comprising: contacts (220) (216A) configured to couple between the at least one battery module (202A) and a machine; A sensor (300) (222B) (222A), the sensor being configured to sense an electrical parameter of the at least one battery module (202A), the sensor (300) (222B) (222A) comprising: an inverting charge pump coupled to receive a positive supply voltage and to generate a negative supply voltage; and a differential amplifier coupled to the at least one battery module (202A) and supplied with the positive supply voltage and the negative supply voltage, the differential amplifier being configured to generate an output representative of the electrical parameter; and A control circuit (302) (318) configured to receive the output of the sensor (300) (222B) (222A) and determine a value of the electrical parameter.

2. The battery management system (200) according to claim 1, wherein the electrical parameter of the at least one battery module (202A) is voltage.

3. The battery management system (200) according to claim 2, wherein the sensor (300) (222B) (222A) further comprises: A voltage divider circuit (302) (310) is coupled between terminals of the at least one battery module (202A) and the differential amplifier.

4. The battery management system (200) according to claim 2, wherein the sensor (300) (222B) (222A) further comprises: A clamp circuit (302)(312) is supplied with the positive supply voltage and the negative supply voltage, wherein the clamp circuit (302)(312) is configured to clamp an output of the differential amplifier.

5. The battery management system (200) of claim 1, wherein the contact (220) (216A) is a first contact (220) (216A) (212A), wherein the negative supply voltage is a first negative supply voltage, wherein the electrical parameter is a first electrical parameter, and wherein the sensor (300) (222B) (222A) is a first sensor (300) (222B) (222A) coupled to a first side of the first contact (220) (216A) (212A), the battery management system (200) further comprising: a resistor (218) coupled in series with a second contact (220) (216A) (212B), wherein the resistor (218) and the second contact (220) (216A) (212B) are coupled in parallel with the first contact (220) (216A) (212A); and a second sensor (300) (222B) (222A), the second sensor coupled to a second side of the first contact (220) (216A) (212A), the second sensor (300) (222B) (222A) being configured to sense a second electrical parameter of the at least one battery module (202A) as seen by the machine, the second sensor (300) (222B) (222A) comprising: an inverting charge pump coupled to receive the positive supply voltage and to generate a second negative supply voltage; and A differential amplifier is coupled to the at least one battery module (202A) and is supplied with the positive supply voltage and the second negative supply voltage, the differential amplifier being configured to generate an output representative of the second electrical parameter.

6. The battery management system (200) according to claim 1, comprising: A plurality of battery modules (202F) (202E) (202B) are coupled together to form a battery pack (206), wherein the sensor (300) (222B) (222A) is configured to sense an electrical parameter of the battery pack (206).

7. A battery management system (200), the battery management system being configured to be coupled to at least one battery module (202A), the battery management system (200) comprising: a first contact (220)(216A)(212A) configured to be coupled between the at least one battery module (202A) and a machine; a resistor (218) coupled in series with a second contact (220) (216A) (212B), wherein the resistor (218) and the second contact (220) (216A) (212B) are coupled in parallel with the first contact (220) (216A) (212A); A first sensor (300) (222B) (222A), the first sensor being configured to sense a first electrical parameter of the at least one battery module (202A), the first sensor (300) (222B) (222A) comprising: an inverting charge pump coupled to receive the positive supply voltage and to generate a first negative supply voltage; and a differential amplifier coupled to the at least one battery module (202A) and supplied with the positive supply voltage and the first negative supply voltage, the differential amplifier being configured to generate an output representative of the first electrical parameter; a second sensor (300) (222B) (222A), the second sensor coupled to a second side of the first contact (220) (216A) (212A), the second sensor (300) (222B) (222A) being configured to sense a second electrical parameter of the at least one battery module (202A) as seen by the machine, the second sensor (300) (222B) (222A) comprising: an inverting charge pump coupled to receive the positive supply voltage and to generate a second negative supply voltage; and a differential amplifier coupled to the at least one battery module (202A) and supplied with the positive supply voltage and the second negative supply voltage, the differential amplifier being configured to generate an output representative of the second electrical parameter; and A control circuit (302)(318) configured to receive corresponding outputs of the first sensor (300)(222B)(222A) and the second sensor (300)(222B)(222A) and determine a value of the first electrical parameter and a value of the second electrical parameter.

8. The battery management system (200) according to claim 7, wherein the first electrical parameter and the second electrical parameter of the at least one battery module (202A) are voltages.

9. The battery management system (200) according to claim 8, wherein the first sensor (300) (222B) (222A) further comprises: A voltage divider circuit (302) (310) is coupled between terminals of the at least one battery module (202A) and the differential amplifier.

10. The battery management system (200) according to claim 8, wherein the first sensor (300) (222B) (222A) further comprises: A clamp circuit (302)(312) is supplied with the positive supply voltage and the negative supply voltage, wherein the clamp circuit (302)(312) is configured to clamp an output of the differential amplifier.

11. A sensor (300) (222B) (222A), the sensor being configured to sense an electrical parameter of at least one battery module (202A), the sensor (300) (222B) (222A) comprising: an inverting charge pump coupled to receive a positive supply voltage and to generate a negative supply voltage; A differential amplifier is coupled to the at least one battery module (202A) and is supplied with the positive supply voltage and the negative supply voltage, the differential amplifier being configured to generate an output representative of the electrical parameter.

12. The sensor (300) (222B) (222A) of claim 11, wherein the electrical parameter of the at least one battery module (202A) is voltage.

13. The sensor (300) (222B) (222A) of claim 11, wherein the sensor (300) (222B) (222A) further comprises: A voltage divider circuit (302) (310) is coupled between terminals of the at least one battery module (202A) and the differential amplifier.

14. The sensor (300) (222B) (222A) of claim 11, wherein the sensor (300) (222B) (222A) further comprises: A clamp circuit (302)(312) is supplied with the positive supply voltage and the negative supply voltage, wherein the clamp circuit (302)(312) is configured to clamp an output of the differential amplifier.

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