Battery systems with embedded cell monitors

A battery pack is disclosed. The battery pack includes a battery cell and a cell monitor. The cell monitor is embedded in the battery cell and is operable for monitoring the battery cell and for generating an alert signal indicative of a predetermined condition of the battery cell.

BACKGROUND

1. Field of the Invention

The present invention relates to power systems and more particularly to battery systems with embedded cell monitors.

2. Description of the Related Art

Batteries are widely used in electronic devices for providing power to electronic devices, such as notebook computers, mobile phones, etc. However, temperature of a battery can rise when the battery is in charging or discharging. Lithium-ion batteries, especially cobalt cathode chemistry type batteries can reach a critical temperature (e.g., between 135 degrees Celsius and 145 degrees Celsius) when exothermic reaction becomes self-sustaining. High temperature can deteriorate batteries.

In a conventional electronic system, a thermistor can be employed to monitor a temperature of the battery pack. However, the thermistor cannot respond quickly to a high temperature of a battery cell that is located far from the thermistor.

SUMMARY OF THE INVENTION

A battery pack is disclosed herein. The battery pack includes a battery cell and a cell monitor. The cell monitor is embedded in the battery cell and is operable for monitoring the battery cell and for generating an alert signal indicative of a predetermined condition of the battery cell.

DETAILED DESCRIPTION

Battery packs/systems with embedded cell monitors are disclosed herein in the present disclosure. Since embodiments shown in the drawings are for illustrative purposes, some sub-components and/or peripheral components generally incorporated in the disclosure are omitted herein for brevity and clarity. In describing embodiments in accordance with the present invention, specific terminologies are employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to selected terminologies and specified embodiments. It is understood that each specific element includes all technical equivalents that operate in a similar manner.

In one embodiment, a battery pack including one or more battery cells is provided. A cell monitor is embedded in each battery cell and is operable for monitoring a corresponding battery cell and for generating an alert signal indicative of a predetermined condition (e.g., an undesirable condition, or a fault condition) of the corresponding battery cell. Each cell monitor includes a sensing circuit operable for detecting the predetermined condition of the corresponding battery cell and for generating a detecting signal. Each cell monitor further includes a transmitter operable for generating the alert signal according to the detecting signal of the cell monitor. The battery pack further includes a receiver for receiving the alert signal and includes a battery management unit for triggering a protection action (e.g., terminating battery pack charging or terminating battery pack discharging) for the battery pack according to the alert signal.

FIG. 1illustrates a block diagram of a battery cell100with an embedded cell monitor101, in accordance with one embodiment of the present invention. The battery cell100is in a battery pack (not shown inFIG. 1for purposes of brevity and clarity). The cell monitor101is embedded in the battery cell100and is coupled between a positive terminal131and a negative terminal133of the battery cell100. The cell monitor101is operable for monitoring the battery cell100and for generating an alert signal191indicative of a predetermined condition (e.g., an undesirable condition) of the battery cell100. In one embodiment, the undesirable condition can include, but is not limited to, an over-voltage condition and an over-temperature condition. In one embodiment, the cell monitor101includes a sensing circuit104operable for detecting an undesirable condition of the battery cell100and for generating a detecting signal103indicative of the detected undesirable condition. The cell monitor101further includes a transmitter135operable for receiving the detecting signal103and for generating the alert signal191according to the detecting signal103from the sensing circuit104. Advantageously, the battery pack can obtain the alert signal191and perform a corresponding protection action (e.g., terminating battery pack charging or terminating battery pack discharging) to protect the battery pack from being deteriorated in the undesirable condition.

FIG. 2Aillustrates a detailed diagram of a battery cell100A with an embedded cell monitor101, in accordance with one embodiment of the present invention. Elements that are labeled the same as inFIG. 1have similar functions and hence any repetitive description of these elements is omitted herein for purposes of clarity and brevity. In one embodiment, the sensing circuit104is operable for detecting an undesirable condition of the battery cell100A and for generating a detecting signal103. The transmitter135A is operable for generating an alert signal191according to the detecting signal103from the sensing circuit104.

More specifically, the sensing circuit104can include a voltage sensor111, a comparator117, and a logic OR gate121. In one embodiment, the voltage sensor111can be a resistor. The voltage sensor111is operable for monitoring a voltage of the battery cell100A. The voltage monitored by the voltage sensor111is compared with a reference voltage113by the comparator117. The reference voltage113can be a predetermined threshold voltage. If the voltage of the battery cell100A is greater than the reference voltage113, which may indicate an over-voltage condition, the comparator117generates a signal (e.g., with a high voltage level) to the logic OR gate121.

In one embodiment, the sensing circuit104also includes a temperature sensor115and a comparator119. In one embodiment, the temperature sensor115can be a thermistor. The temperature sensor115is operable for monitoring a temperature of the battery cell100A and for generating a signal indicative of the temperature of the battery cell100A. The signal indicative of the temperature of the battery cell100A has a voltage level Vt. The voltage level Vt is compared with the reference voltage113by the comparator119. If the voltage level Vt is greater than the reference voltage113, which may indicate an over-temperature condition, the comparator119generates a signal (e.g., with a high voltage level) to the logic OR gate121.

In one embodiment, the voltage sensor111and the temperature sensor115continuously monitor the voltage and the temperature of the battery cell100A respectively. If an undesirable condition (e.g., an over-voltage condition and/or an over-temperature condition) occurs, the logic OR gate121can generate a detecting signal103(e.g., with a high voltage level) to the transmitter135A. The transmitter135A can generate an alert signal191to the battery pack according to the detecting signal103if the undesirable condition occurs. More specifically, if the voltage of the battery cell100A is greater than a predetermined threshold and/or if the temperature of the battery cell100A is greater than a predetermined threshold, the alert signal191will be generated. Consequently, corresponding actions can be performed to protect the battery pack.

In one embodiment, the transmitter135A includes a pulse generator105, a resistor109, and a switch107(e.g., a transistor) coupled to the pulse generator105. When the pulse generator105receives the detecting signal103indicative of the undesirable condition, the pulse generator105can generate a series of pulses to the switch107according to the detecting signal103. In one embodiment, the pulse generator105can generate a series of high current pulses with a frequency f0(e.g., a pulse width modulation signal with a duty cycle of 1%) in response to the detecting signal103. The switch107is operable for receiving the series of pulses from the pulse generator105and for generating the alert signal191. In one embodiment, the switch107is switched on and off periodically by the pulses. Thus, the alert signal191is shown as an AC signal having a frequency f0, in one embodiment. The cell voltage of the battery cell100A drops when the switch107is on. Consequently, the cell voltage between terminals131and133can be shown as an AC voltage with the frequency f0in response to the alert signal191, in one embodiment.

FIG. 2Billustrates another detailed diagram of a battery cell100B with an embedded cell monitor101, in accordance with one embodiment of the present invention. Elements that are labeled the same as inFIG. 1andFIG. 1Ahave similar functions and will not be repetitively described herein for purposes of clarity and brevity. In one embodiment, the cell monitor101includes a transmitter135B for receiving the detection signal103and for generating the alert signal191according to the detection signal103. More specifically, the transmitter135B includes an oscillator205and a capacitor207coupled to the oscillator205, in one embodiment. In one embodiment, the oscillator205can be a radio frequency signal tone oscillator. In another embodiment, the oscillator205can be a radio frequency dual tone oscillator.

The oscillator205can receive the detecting signal103from the logic OR gate121. In one embodiment, the oscillator205has a frequency fosc and generates an oscillation signal, e.g., a sinusoidal AC waveform having a high frequency fosc (e.g., 10 MHz), as the alert signal191according to the detecting signal103. The capacitor207is operable for transferring the alert signal191having the frequency fosc to the battery cell100B. As a result, when the voltage sensor111detects an over-voltage condition, and/or the temperature sensor115detects an over-temperature condition, the cell voltage of the battery cell100B can be shown as an AC voltage with the frequency fosc in response to the alert signal191.

As discussed above in relation toFIG. 2AandFIG. 2B, the alert signal191can reflect an undesirable condition of the battery cell100, e.g., an over-temperature and/or an over-voltage condition. Consequently, an AC voltage can be shown across the battery cell in response to the alert signal191. Description will now be made with reference toFIG. 3with respect to detecting such alert signal and performing corresponding actions if an undesirable condition occurs.

FIG. 3shows a block diagram of a battery system300(e.g., a battery pack), in accordance with one embodiment of the present invention. The battery pack300includes one or more battery cells310coupled in series or in parallel, each of which can employ the configuration inFIG. 1, in one embodiment. A cell monitor is embedded in each of the battery cells310. Therefore, battery cells310are monitored by embedded cell monitors individually and respectively. The battery pack300further includes a positive terminal331, a negative terminal333, a receiver301, a battery management unit305, and a switch307controlled by the battery management unit305, in one embodiment. As described above in relation toFIG. 2AandFIG. 2B, when an undesirable condition (e.g., an over-temperature condition and/or an over-voltage condition) is detected in a battery cell, an AC voltage can be shown across the battery cell in response to the alert signal. Thus, an AC voltage can be shown between the positive terminal331and the negative terminal333of the battery pack300, in one embodiment. The receiver301is coupled to the positive terminal331and the negative terminal333of the battery pack300and is operable for receiving the alert signal from a cell monitor by detecting an AC voltage between the positive terminal331and the negative terminal333of the battery pack300, in one embodiment. The receiver301can also generate a driving signal303according to the alert signal.

In one embodiment, the receiver301includes a high pass filter shown as a capacitor313and a resistor315coupled in series for filtering noises associated with the battery pack300. In one embodiment, if the alert signal (e.g., an AC signal) from battery cells310has the frequency f0higher than a cutoff frequency of the high-pass filter, the receiver301can generate a driving signal303. The battery management unit305can receive the driving signal303from the receiver301and generate a switching signal391according to the driving signal303. Corresponding actions can be performed to protect the battery pack300in response to the switching signal391. For example, the switching signal391turns off the switch307to terminate battery charging/discharging in order to protect the battery pack300from deterioration.

In one embodiment, the battery management unit305includes a detection circuit340for detecting the driving signal303from the receiver301. Such configuration is for illustrative purpose and other configurations can also be employed in the battery management unit305. The detection circuit340includes a rectifier341and a comparator345, in one embodiment. The rectifier341can be a high frequency rectifier for receiving the driving signal303and for rectifying the driving signal303. In one embodiment, the rectifier341generates a voltage signal according to the driving signal303. Then the comparator345compares the voltage signal with a reference signal343. If the voltage level of the voltage signal from the rectifier341is greater than the voltage level of the reference signal343, the comparator345outputs a signal (e.g., with a high voltage level) to the battery management unit305, in one embodiment. Then the battery management unit305can generate a switching signal391according to a result of the comparison to trigger a protection action for the battery pack300. For example, the switching signal391can turn off the switch307, which is coupled to the positive terminal331of the battery pack300. Consequently, the battery pack300can be disconnected from a load or a charger (not shown inFIG. 3for purposes of brevity and clarity) and can be protected from being deteriorated in the over-temperature condition and/or over-voltage condition.

FIG. 4illustrates a block diagram of a battery system400(e.g., a battery pack), in accordance with another embodiment of the present invention. Elements that are labeled the same as inFIG.3have similar functions and will not be repetitively described herein for purposes of clarity and brevity. The battery pack400includes a receiver401similar to the receiver301inFIG. 3. The receiver401detects the alert signal from battery cells310and generates a driving signal303to the battery management unit305. In one embodiment, the receiver401includes a band-pass filter shown as a capacitor313, an inductor417and a resistor315in series for filtering noises associated with the battery pack400. In one embodiment, a resonant frequency of the band-pass filter can be set to be equal to the frequency of the alert signal191inFIG. 2AandFIG. 2B. Therefore, the alert signal can pass through the band-pass filter. Thus, the receiver401can receive the high frequency alert signal from battery cells310and generate the driving signal303. The battery management unit305can generate a switching signal391according to the driving signal303. The switching signal391can trigger a protection action for the battery pack400by controlling the switch307. For example, the switch307can be turned off by the switching signal391under the control of the battery management unit305. Consequently, the battery pack400can be disconnected from a load or a charger (not shown inFIG. 4for purposes of brevity and clarity) and can be protected from being deteriorated in undesirable conditions.

Accordingly, when a predetermined condition (e.g., an over-temperature condition and/or an over-voltage condition) is detected by a cell monitor101embedded in a battery cell100from battery cells310, the cell monitor101can generate an alert signal. The alert signal can cause an AC voltage across the battery cell100, in one embodiment. Therefore, an AC voltage can be shown between the positive terminal331and the negative terminal333of the battery pack300(400) in response to the alert signal. Then the receiver301(401) can detect the alert signal and generate the driving signal303to the battery management unit305. The battery management unit305can generate a switching signal391which can control the switch307. The switch307is turned off under control of battery management unit305to protect the battery pack300(400) according to the driving signal303. Advantageously, each cell in battery cells310is monitored by an individual embedded cell monitor. If one of the battery cells310is undergoing an over-temperature and/or over-voltage condition, the cell monitor in that battery cell can transmit an alert signal to alert the battery pack300(400). Consequently, corresponding actions can be performed to protect the battery pack300(400) from being deteriorated in undesirable conditions.

As described inFIG. 2B, the transmitter135B includes the capacitor207for transferring the alert signal from the oscillator205to the positive terminal131of the battery cell100B. The following description made with reference toFIG. 5andFIG. 6describes an exemplary implementation of such capacitor in fabrication process.

FIG. 5shows a cross-section diagram of a die500, in which a cell monitor (e.g., the cell monitor101inFIG. 2B) is fabricated, in accordance with one embodiment of the present invention. Referring toFIG. 5, the die500includes a metal layer503, a metal layer505, and an insulator507. The metal layer503and the metal layer505are insulated by the insulator507. A circuit501including the sensing circuit104and the oscillator205inFIG. 2Bis coupled to the metal layer503and the metal layer505. During fabrication of the die500, the metal layer503and the metal layer505are formed when fabricating the sensing circuit104and the oscillator205. Advantageously, the insulator507can be formed between the metal layer503and the metal layer507, and thus the metal layer503, the insulator507and the metal layer505can constitute the capacitor207with a relatively large capacitance. Therefore, this configuration can avoid the formation of two extra metal layers for the purpose of the capacitor fabrication and the cost of the die500can be decreased.

FIG. 6shows another cross-section diagram of a die600, in which the cell monitor101is fabricated, in accordance with one embodiment of the present invention. The die600includes multiple metal layers, e.g., a metal layer603, a metal layer605, and a metal layer607. Metal layers are separated by an insulator615and an insulator617. In one embodiment, the metal layer603is coupled to the metal layer607through a via613. In one embodiment, a circuit601including the sensing circuit104and the oscillator205inFIG. 2Bis coupled to the metal layer605and the metal layer607. During fabrication of the die600, the metal layer603, the metal layer605, and the metal layer607are formed when fabricating the sensing circuit104and the oscillator205. Advantageously, multiple metal layers can extend the number of vertical layers of capacitors that can be provided. Therefore, the metal layer603, the metal layer605and the insulator615can constitute a first capacitor, the metal layer605, the metal layer607and the insulator617can constitute a second capacitor. The first capacitor and the second capacitor are coupled in parallel as shown inFIG. 6. Advantageously, the capacitor207can include the first capacitor and second capacitor in parallel. Thus, the capacitance of the parallel connected capacitors inFIG. 6can be twice as the capacitance of the capacitor inFIG. 5. In one embodiment, extra metal layers are saved to form the capacitor configuration and the cost of the die600can be reduced.

FIG. 7illustrates a cell monitor die700of the cell monitor101, in accordance with one embodiment of the present invention. In one embodiment, the cell monitor101is fabricated on the cell monitor die700. The cell monitor die700includes a bottom705(e.g., a substrate) and a top703(e.g., metal layer503inFIG. 5or metal layer603inFIG. 6). Because the bottom705is ground, the bottom705can be coupled to the negative terminal of the battery cell100, in one embodiment. The top703is a positive contact, which can be coupled to the positive terminal131of the battery cell100by a single wire, in one embodiment. Therefore, a single wire can embed the cell monitor die into the battery cell100. Advantageously, the cell monitor die700can be integrated in the top cap of the battery cell100in one embodiment, or in the center of the battery cell100in another embodiment.

The battery pack300(400) can be used in many kinds of electronic systems.FIG. 8illustrates an electronic system800, such as an electronic vehicle, a computer, etc., in accordance with one embodiment of the present invention. In one embodiment, the electronic system800can include a battery pack804and a load806coupled to the battery pack804. In one embodiment, the load806can include, but is not limited to, a vehicle motor, a computer system, etc. In one embodiment, the electronic system800includes an input terminal802that can be coupled to an adapter (not shown inFIG. 8for purposes of brevity and clarity). The adapter can charge the battery pack804in a certain condition. The battery pack804can supply power to the load806. In one embodiment, the battery pack804employs the configuration as shown in FIG.3/FIG. 4. The battery pack804includes one or more battery cells, each of which is embedded with a cell monitor to monitor the battery cell. Therefore, the battery pack804can be monitored accurately and be protected from any undesirable conditions of each battery cell thereof, in one embodiment.

FIG. 9illustrates a flowchart900of operations performed by a battery system, in accordance with one embodiment of the present invention. The battery system can employ the configuration as shown in FIG.3/FIG. 4, in one embodiment.FIG. 9is described in combination withFIG. 1,FIG. 2A, andFIG. 2B. In block902, each battery cell in a battery pack is monitored respectively by a corresponding cell monitor101and thus an alert signal191indicative of a predetermined condition of the associated battery cell can be generated. The cell monitor101is embedded in each battery cell. In one embodiment, a temperature sensor115can monitor a temperature of the battery cell and thus the cell monitor101generates the alert signal191if the temperature of the battery cell is greater than a predetermined threshold. A voltage sensor111can monitor a voltage of the battery cell and thus the cell monitor101generates the alert signal191if the voltage of the battery cell is greater than a predetermined threshold. In block904, the cell monitor101generates an alert signal191indicative of a predetermined condition of the battery cell. In one embodiment, the predetermined condition can be an undesirable condition (e.g., over-voltage and/or over-temperature condition). In block906, a protection action (e.g., terminate battery charging/discharging) can be triggered according to the alert signal191. In one embodiment, the battery cell can be disconnected from a load or a charger in response to the alert signal.

Accordingly, a battery pack is provided in the present disclosure. A cell monitor is embedded in each battery cell of the battery pack for monitoring the corresponding battery cell. When an undesirable condition (e.g., over-temperature condition and/or over-voltage condition) is detected in a battery cell, the corresponding cell monitor can generate an alert signal to the battery pack. A receiver in the battery pack can receive the alert signal and generate a driving signal to a battery management unit. The battery management unit can take corresponding action to protect the battery pack from being deteriorated in the undesirable condition, e.g., disabling connection between the battery pack and other circuitry.

As disclosed hereinabove, each battery cell in a battery pack includes a cell monitor for monitoring a corresponding battery cell individually. Once an undesirable condition is detected by a cell monitor in the corresponding battery cell, the battery pack can be notified about the undesirable condition. Thus, the cell monitoring can be relatively accurate and the speed of responding to the undesirable condition can be relatively quick.

The embodiments that have been described herein, however, are some of the several that utilize this invention and are set forth here by way of illustration but not of limitation. It is obvious that many other embodiments, which will be readily apparent to those skilled in the art, may be made without departing materially from the spirit and scope of the invention as defined in the appended claims. Furthermore, although elements of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.