KR102433599B1 - System for recharging battery with motion sensor - Google Patents

Abstract

A battery with a battery management system can charge the battery with recaptured energy from an energy recovery device. The battery management system charges the battery with the energy recovery device when the output voltage from the energy recovery device is greater than the charging voltage of the battery.

Description

SYSTEM FOR RECHARGING BATTERY WITH MOTION SENSOR

This application is a continuation-in-part (CIP) patent application of U.S. Patent Application No. 16/685,255 for a 'lead-acid battery replacement system' filed on November 15, 2019, and the application was filed on January 15, 2019 As a regular application to U.S. Provisional Application No. 62/792,630 for 'Lithium Batteries for Golf Carts', all of these application specifications are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION The present invention relates to batteries, and in particular to recharging batteries with recharged energy.

When a moving vehicle is equipped with a battery, the energy from the battery is used to power various devices in the vehicle. When the vehicle is stopped, if the battery is equipped with a charger that can use the recharged energy, the kinetic energy can be captured and used to charge the battery.

Therefore, it is desirable to have a battery management system in which the battery can use the recharged energy to charge the battery.

In one embodiment of the present invention, the present invention provides a method for recharging a battery having a battery management system and connected to an energy regeneration device and a motion detection device. The battery recharging method of the present invention comprises the steps of receiving an output voltage from an energy regenerative device; receiving a motion indicator from a motion sensing device; comparing an output voltage from the energy recovery device to a charging voltage for the battery; and charging the battery with the energy regeneration device when the output voltage is greater than the charging voltage and the motion indicator indicates movement.

In another embodiment of the present invention, the present invention provides a battery connected to an energy regeneration device. The battery of the present invention includes a plurality of battery cells; a charger connected to the plurality of battery cells; a controller coupled to the plurality of battery cells and the charger; and a motion detection device coupled to the controller, wherein the controller receives a movement indicator from the motion detection device, and wherein the controller enables a connection between the energy regenerative device and the charger, such that the motion indicator indicates motion, the energy When the output voltage from the reproduction device is greater than the charging voltage for the plurality of battery cells, the plurality of battery cells are charged.

Accordingly, the systems and methods of the present invention are advantageous as they enable the recharging of batteries with renewable energy. Other advantages and features of the present invention will become apparent after review of the following brief description of the drawings, detailed description and claims.

The features and advantages of the embodiments of the present invention will become apparent from the following detailed description, and like reference numerals are used for similar components in the drawings.
1A shows a diagram 100 for battery replacement.
1B shows a battery exchange structure 150;
Figure 2 shows a circuit diagram 200 illustrating a charge and discharge circuit;
3 shows an architecture 300 of a controller chip.
4 shows a circuit diagram 400 with a motion detector;
5 is a flow diagram 500 for a charge transfer process;
6 is a flowchart 600 for a battery charging process;
7 is a flowchart 700 for protected mode.
8 is a flow diagram 800 for charging a battery with regenerated energy energy.
9 is a flowchart 900 for stopping the charging process.

In this specification, the term "application" is used to include executable and non-executable software files, raw data, aggregated data, patches, and other code segments. The term “exemplary” is intended by way of example only and does not indicate preference for the described embodiment or component. Also, like reference numbers refer to like elements throughout the drawings, and "a" and "the" include plural references unless otherwise specified in the specification. The terms lithium-based battery, lithium ion battery, lithium iron phosphate battery, lithium battery are used interchangeably, and "battery" and "battery pack" are used interchangeably. Lithium battery herein refers to any type of lithium battery. The protection mode used in the application of the present invention refers to either an under voltage protection mode or an over voltage protection mode, and the protection mode may also be referred to as a sleep mode.

In general, the present invention provides an intelligent system and method for charging parallel-connected rechargeable batteries. The recharge circuit is controlled by the voltage at the output port of the rechargeable battery. The battery voltage drop is used to control the recharge circuit. When the output port voltage is less than the maximum discharge of the battery, the charging circuit is turned off. When the output port voltage is greater than the maximum charging voltage of the battery, the recharge control circuit is turned on. The deviation of the maximum charge voltage and maximum discharge voltage is used to control the recharge circuit for the rechargeable batteries connected in parallel.

In addition to using voltage differential to control the recharge circuit, the recharge operation is further controlled by a motion sensor or displacement detection sensor. When movement of the vehicle with the rechargeable battery is detected by the displacement detection sensor, the displacement detection sensor provides a signal to the recharging circuit and the recharging circuit is turned on and the recharging operation is permitted.

The displacement detection sensor is located inside the battery controller and is connected to the MCU of the battery controller. The battery controller determines whether the rechargeable battery is in a moving state by detecting the vibration signal and displacement data provided by the displacement detection sensor. When the battery is in a mobile state, the battery controller can activate a recharge circuit to recharge the battery cells.

To prevent mutual interference between the batteries, an isolation circuit is designed for battery packs connected in parallel. The isolation circuit affects energy recovery by the battery pack. Energy that cannot be recovered can affect battery system operation.

The system of the present invention uses a displacement detection and displacement detection device to detect a change in movement of the battery system. When the movement of the entire battery system changes, the battery control system is notified by the displacement detection device. The battery control system determines whether there is enough recyclable energy to absorb based on the detected voltage at the output port. When there is enough recyclable energy, the recharge control circuit is turned on. By charging the rechargeable battery, the rechargeable battery absorbs the energy generated (recovered) by the motion control system. After the recovered energy is absorbed, the recharge control circuit is turned off to ensure isolation between the battery cells of the rechargeable battery system. For example, if the motion detection circuitry detects that movement of the battery system is decelerating, recoverable energy may be generated; The displacement detection unit notifies the battery control system that the movement state of the battery control system has changed, and the battery control system detects a change voltage change at an external port of the battery system. When the external port voltage changes to 58V (using a 48V battery system as an example), the battery control system turns on the recharge circuit to absorb the recovered energy of the motion system. At this time, the battery control system continuously monitors the voltage at the output port. After the recoverable energy has been absorbed, the recharge circuit is turned off when the port voltage drops to 54V to ensure isolation between the battery cells.

At the same time, the displacement detection module is used to determine whether the battery system is being charged by an external charger or by the recharging control module of the motion system, and this determination is made by the information from the displacement of the motion system. When an external charger is used to charge the battery system, the state of the motion system is static. The recharge control module can charge the battery system only when the state of the motion system is operating. In the static state, only an external charger may be used to charge the battery. Based on this difference, separate control of charging by an external charger and recharging based on a motion system is achieved.

The present invention is a further improvement of a system and method that enables easy replacement of a lead-acid battery by a lithium-based battery while maintaining the same charging system designed for the lead-acid battery. A system and method for replacing a lead-acid battery by a lithium-based battery has the following features and advantages. .

a. The rechargeable battery module of the present invention includes a main control module, a series and parallel rechargeable battery unit, a charge control switch, a discharge control switch, a discharge auxiliary switch, a single battery voltage acquisition module, a current acquisition module of the battery module, and a port capacitor and will be described with reference to FIGS. 2, 3 and 4 .

b. 2 to 4 , the rechargeable battery module is directly electrically connected to a lead-acid battery charger and/or a load connected to a lead-acid battery load through an output port.

c. The main control module enables the normal operating voltage of the lead-acid battery at the output port through the PWM output and the opening and closing of the discharge module controlled by the voltage smoothing function of C66, so as is evident from Fig. 4 and related description, the rechargeable battery module will enable the charging system of lead-acid battery systems to collaborate with

d. The main control module also controls the opening and closing of the discharge auxiliary switch through the partial load of the series load and the port load to enable the normal operating voltage of the lead-acid battery at the output port, as is clear from Fig. 2 and related description, the original lead-acid battery Enables the system to identify and accept rechargeable battery modules.

e. The basic control module simulates a rechargeable battery module to simulate the voltage and current characteristics of a lead-acid battery in the charging process, as described in FIG. 4 and related description, and the original lead-acid battery system is a rechargeable battery The charging and control switches on and off are controlled by PWM to identify and allow the module.

f. The discharge control switch of the secondary rechargeable battery module is connected in parallel with the diode as shown in FIG. 2 . In the charging mode, the discharge control switch is disconnected, allowing the charging current to flow through the diode to realize mutual isolation between the batteries used in parallel when the batteries are being charged. When the current is greater than the set diode operating current limit IREF, comparator U11A operates to open the discharge switch to prevent the diode current from flowing out of range; When the current is less than IREF, the discharge control switch is automatically turned off to prevent mutual charging between parallel-connected battery modules.

g. The charge control switch of the secondary rechargeable battery module is connected in parallel with the diode as shown in FIG. 2 . In the discharging mode, the charge control switch is disconnected, and the discharging current flows through the diode to realize mutual isolation between the batteries connected in parallel. When the battery module's discharge current is greater than the diode operating current limit (IREF), comparator U11B turns on the discharge switch so that the diode current does not exceed the allowable range. When the current is less than IREF, the charge control switch is automatically turned off to prevent discharge between paralleled battery modules.

The diagram 100 of FIG. 1A illustrates the purpose of the present invention. Connection diagram 100 shows charger 102 connected to a power source (not shown) and lead-acid battery 104, which is connected to a load (not shown). The system of the present invention allows the lead-acid battery 104 to be replaced with a lithium-ion battery 106 while the same charger 102 is in use. When replacing the lead-acid battery 104 with the lithium-ion battery 106, the replacement lithium-ion battery 106 must operate as the lead-acid battery 104 within its normal operating voltage, and the charger 102 and the load ( (not shown) is assumed to be interfacing with a lead acid battery.

1B shows the architecture 150 of a replacement lithium-ion battery 106 . The replacement lithium-ion battery 106 is comprised of a plurality of battery cells 152 coupled to a battery management system 154 . The battery management system 154 has a charge sensing unit 156 , a charge control unit 158 , and a discharge control unit 160 . The battery management system 154 also monitors the voltage and current at the output connectors 162 , 164 of the battery cell 152 and the voltage and temperature at each of the battery cells via the sensing unit 156 . Battery management system 154 also monitors the voltage delivered to output connectors 166 and 168 . The sensing unit 156 , the charging control unit 158 , and the discharging control unit 160 of the battery management system 154 are controlled by the controller.

During discharge, when the voltage of the lithium-ion battery drops below a certain level, the lithium-ion battery normally cuts off and stops the output of any voltage as part of the normal battery protection procedure, and the voltage drop of the lead-acid battery is continuous and Lead-acid batteries do not block the output voltage. For a lithium-ion battery to emulate a lead-acid battery, the lithium-ion battery needs to provide an output voltage even if the voltage level at the output connectors 162 and 164 is low. To achieve this emulation, when the output voltage at the output connectors 162, 164 drops below a threshold level, the discharge control unit 160 controls the output voltage at the output connectors 166, 168 to emulate the lead-acid battery output voltage. is activated to transmit

During the battery charging process, when the voltage at the output connectors 162 and 164 is above a certain level to prevent damage to the battery cells 152, the lithium-ion battery is charged by disconnecting the connection to the terminals 166 and 168. Stop the process, meanwhile the lead acid battery will continue to provide the connection between the battery cells 152 to the output terminal. For emulation purposes, when the voltage at the output connectors 162 and 164 exceeds a predetermined threshold level, this means that the battery cell is almost fully charged, and the charge control unit 158 determines that the battery cell 152 is large. It is activated to output a voltage and prevent charging neighboring battery cells.

When replacing a bank of lead-acid batteries with a bank of multiple lithium-ion batteries, the control of these lithium-ion batteries can be problematic. Because of the small internal resistance of lithium-ion batteries, it can be difficult to control the direct parallel connection of multiple lithium-ion batteries due to the difference in the state of charge between the batteries, and the charging and discharging currents of one battery can damage another. have. The battery management system of the present invention enables lithium-ion batteries to emulate the characteristics of lead-acid batteries, allowing direct replacement of lead-acid batteries by lithium-ion batteries and by reusing chargers and other devices.

The charger in a conventional lead-acid battery system usually first checks the battery voltage, and the charging sequence starts only when the battery voltage is in the normal range of the lead-acid battery. Because the lead-acid battery is directly connected to the charger, the lead-acid battery adopts the above approach as a way to protect the lead-acid battery and the charger. Lead-acid batteries must also be protected against overcharging and overdischarging, and a common method for such protection is to disconnect them from the charger and load. Overcharging and overdischarging of lithium-ion batteries pose similar safety concerns.

To ensure that lithium-ion batteries can be reliably used with conventional lead-acid battery chargers, the battery management system uses timing pulse control technology to control the charging of lithium-ion batteries. The battery management system of the present invention also uses a timing control mode that enables periodic voltage output at the output terminal to allow the charger to detect the battery. For example, the battery management system opens the discharge circuit for 10 seconds every 240 seconds. Enabling periodic output instead of continuous output when the battery's charge is low can prolong the life of the lithium-ion battery. The battery management system uses resistors and MOSFETs to emulate the output voltage through PWM (pulse-width-modulation) mode (pulse mode) so that an output voltage similar to that of a lead-acid battery is used at the output terminal of a lithium-ion battery. make it possible The battery management system controls lithium battery replacement by periodically activating the output voltage of the lithium battery in pulse mode when the lithium battery enters the low-voltage protection state, so that the lithium battery can save the charge and extend the allow it to work for hours.

The battery management system of the present invention uses a MOSFET charge control unit 158 and a MOSFET discharge control unit 160 connected in series with a battery cell of a lithium battery. When charging the lithium battery, only the MOSFET for the charge control unit 158 is turned on, so that charging of lithium-ion battery cells connected in parallel can be realized, and charging and discharging between lithium-ion batteries connected in parallel can be prevented. and ensure the independence of each lithium battery. Similarly, during the discharging process, only the MOSFET for the discharging control unit 160 is turned on in the series circuit, and charging and discharging between the batteries can be avoided.

When replacing a lead-acid battery bank with a lithium-ion battery bank, several lithium-ion batteries with a voltage level similar to that of lead-acid batteries are connected in parallel and an overcharge protection circuit is used, so that the lead-acid battery charger can be connected to the lithium-ion battery pack without overcharging. charging can be completed.

2 is an architecture 200 of a battery charge/discharge control system for one battery pack according to the present invention. Figure 2 shows the control for one battery, such that a plurality of batteries are combined to form a battery bank. Each battery consists of a plurality of battery cells 202 connected in series. These battery cells are individually monitored through a level shifter 204 , which transmits voltage and temperature information of each battery cell to a controller 216 . The controller 216 may designate a cell to be monitored through address selection. A plurality of batteries are connected in parallel to a charger (not shown) through two connectors 218 and 220 of each of the batteries. Since the batteries are connected in parallel and different batteries may have different voltages, special care must be taken to avoid charging one battery to another. This protection is achieved by the charge control unit MOSFET 210 and the discharge control unit MOSFET 212 . During the charging process, the charging control MOSFET 210 is ON or OFF depending on the state of the charging process, and the discharging control unit MOSFET 212 is always ON. When the charging current is small, the charging current passes through a diode connected in parallel to the charging control unit MOSFET 210; When the charging current is large, the charging control MOSFET 210 is turned on by the charging switch 208 so that the large charging current passes through the charging control MOSFET 210 and overheating of the diode 210 is prevented. The charging switch 208 compares the charging voltage to a reference voltage and turns on the charging control MOSFET 210 when the voltage difference exceeds a predetermined difference. After the charge control MOSFET 210 is turned on, a large charge current passes through the charge control MOSFET 210 . At the start of the charging operation, when the voltage at the battery cell 202 is low and the difference between the battery cell 202 and the reference voltage is large, the charging switch 208 turns on the MOSFET 210, so that a large charging current passes through. . As the battery cells 202 are charged, the voltage difference between the battery cells 202 and the reference voltage is small, the charging switch 208 turns off the MOSFET 210 , and a small charging current is drawn into the MOSFET 210 . It passes through diodes connected in parallel.

When the discharge current is small, the discharge current flows through a diode connected in parallel to the discharge control MOSFET 212 . When the discharge current is large, in order to prevent overheating and deterioration of the diode, the discharge control MOSFET 212 is turned on by the discharge switch 214 , and the discharge current flows through the discharge control MOSFET 212 . The discharge control MOSFET 212 is turned on when the voltage difference measured by the discharge switch 214 between the predefined reference voltage and the voltage from the battery cell 202 is greater than a predefined value.

The system of the present invention also prevents mutual charging between battery packs during discharge. During discharge, if the battery has a higher voltage and current than other neighboring batteries, the battery with the lower discharge current causes the discharge MOSFET 212 to turn off and a small discharge current is connected in parallel with the discharge MOSFET 212 . By passing through the diode, charging of the battery by another battery pack with a higher voltage is prevented.

3 shows an architecture 300 of a controller 216 . The controller 216 includes a status display unit 302 , an activation unit 304 , a level shifting unit 308 , a communication unit 312 , a shunt resistor 310 , a switching controller 314 , and a main controller 306 . has The controller 216 communicates with the outside world via a connection port 316 . The main controller 306 may use the communication unit 312 to receive commands and send data to other devices. The status display unit 302 may be an LED display or other suitable means. The activation unit 304 receives the command and sends the command to the main controller 306 . The level shifting unit 308 connects and controls the level shifter 204 . The shunt resistor unit 310 connects and controls the shunt resistor 206 . Main controller 306 controls charge control MOSFET 214 and discharge control MOSFET 208 via switching controller 314 . The user interface unit 318 allows a user to input a command to wake the battery from the protection mode or adjust the settings of the protection mode. The storage unit 320 stores software instruction programs and data. The main controller 306 executes a software command program to control the battery management system.

The battery charge/discharge control system of FIG. 2 is connected to the battery charger 412 as shown in FIG. 4 . Charger 412 is connected to a power source, such as an external power source 416 and/or power recovery system 418 . External power source 416 , which may be a plug-in power outlet, and power recovery system 418 may be systems that capture power regenerated by the driving system of the golf cart. When the lithium battery is connected to a load such as an electric motor, the transfer of current by the battery cell 202 is controlled by a discharge control MOSFET 212 . When charger 412 is connected to an external power source to charge battery cell 202 , the charging operation is controlled by charge control MOSFET 210 .

The battery charge/discharge control system of the present invention provides a smooth replacement of the lead-acid battery by the lithium battery, and in order to achieve this purpose, it is necessary that the lithium battery operates in a manner similar to that of the lead-acid battery during the charging and discharging operation. During normal lead-acid battery operation, the lead-acid battery's output voltage affects the charger operation and load. When a lithium battery replaces a lead-acid battery, the output voltage of the lithium battery should be similar.

As the lead-acid battery continues to supply current to the load, the lead-acid battery's output voltage drops. For lead-acid battery 48V, the normal operating range is 36V to 57.6V, and for lead-acid battery 24V, the normal operating range is 18V to 28.8V. Therefore, replacement lithium batteries also operate within this range. However, when the output voltage of the lithium battery falls below a certain threshold, the lithium battery goes into undervoltage protection (UVP) mode, turning off the output when the output voltage or current falls below a certain level. In general, when a lithium battery is switched to UVP mode and the output is cut off, the load or charger cannot sense the output voltage, and as a result, the charger or load cannot operate normally. Similarly, if the voltage at the lithium battery exceeds a certain threshold during the charging operation, the lithium battery goes into overvoltage protection (OVP) mode to turn off the input. The voltage level at which each lithium battery enters the UVP mode or OVP mode depends on the characteristics of each lithium battery.

In order for the lithium battery to operate in a manner compatible with the lead-acid battery system, the battery management system of the present invention requires the lithium battery to generate an output voltage that is within the lead-acid battery normal operating range, which means that the lithium battery This is achieved by the battery management system, which makes it possible to adapt the output voltage of the lithium battery while in protection mode. The controller 216 enables a simulated output voltage in the normal operating range of the lead-acid battery through the circuit shown in FIG. By providing the simulated output voltage, a charging operation is enabled and the charger 412 will be able to charge the lithium battery cell 202 . The charging operation is the same as described above. Similarly, the controller 216 will also enable a simulated output voltage that allows a lithium battery to be discharged in a manner similar to a lead acid battery.

When the lithium-ion battery enters the protection mode and stops outputting the voltage between the connectors 218 and 220, the controller 216 allows the battery to intermittently deliver a predefined output voltage according to the principle of PWM. will make it The predefined output voltage is adjusted according to the characteristics of the battery. For example, during discharge, when the output voltage of the battery cell 202 drops below a predetermined level measured by the current through the resistor 206, the battery enters a low voltage protection mode, so that the battery cell 202 It will not be completely depleted and thus will not be damaged. When in undervoltage protection mode, MOSTFET 212 is shut down (closed) and no voltage is output. Controller 216 controls emulator MOSFET 402 and periodically opens emulator MOSFET 402 so that a voltage is available at terminals 218 and 220 . Current from battery cell 202 passes through emulator MOSFET 402 and resistor 404 in pulsed mode. Capacitor 410 is used to attenuate voltage fluctuations between terminals 218 and 220 . The controller 216 coordinates the control of the emulator MOSFET 402, so the appropriate voltage and duration of the delivered voltage can be adjusted according to the characteristics of the lead-acid battery that the lithium-ion battery is emulating. The duration and level of the output voltage may be adjusted by the controller 216 . The controller 216 adjusts the control function according to the following equation.

Control(F) = (voltage of battery cell, temperature of battery cell, external voltage, current of battery cell)

Battery cell voltage - the voltage of each battery cell

Temperature of the battery cells - the temperature of each of the battery cells

External Voltage - Voltage at the output terminal of the battery

Battery cell current - current measured in resistor 206

By providing a simulated output voltage between output terminals 218 and 220, the battery will make the battery part of a battery bank and be detectable by the charger, conserving charge.

In another example, during the charging process, when the voltage of the battery cell 202 reaches a predefined level, the battery enters the overvoltage protection mode, and the battery cell 202 is not overcharged and not damaged. When in overvoltage protection mode, MOSTFET 210 is shut down (closed) and no voltage is output. Controller 216 controls emulator MOSFET 402 and periodically opens emulator MOSFET 402 so that voltage is available at terminals 218 and 220 . Current from battery cell 202 passes through emulator MOSFET 402 and resistor 404 in pulsed mode. Capacitor 410 is used to attenuate voltage fluctuations between terminals 218 and 220 . The controller 216 adjusts the control of the emulator MOSFET 402 in a manner similar to that described above, so that an appropriate voltage can be detected by the charger, and the battery continues to be part of the battery bank.

5 is a flowchart 500 of a discharging operation. When the battery is connected to the load, the battery transfers the charge to the load (step 502). As the battery drives the load, charge is transferred to the load and the battery's voltage drops. The discharge control unit of the battery management of the battery continuously monitors the output voltage in step 504 . When the output voltage falls below a predetermined threshold level (step 506), the discharge control unit of the battery management system stops the charge (charge) transfer process (step 508), and the battery cell will not be completely depleted and will not be damaged. As the battery stops driving the load, the battery management system causes the battery to enter the low voltage protection mode (step 510). In this low voltage protection mode, the battery will output a predetermined voltage in pulsed mode for a short time, allowing the battery life to be extended for a long time, and when the battery is later connected to the charger, the charger will detect the presence of the battery. It will detect and then start the charging process.

6 is a flowchart 600 for a charging operation. The charger detects the battery and verifies that the battery has the expected electrical characteristics before starting the charging operation (step 602). The charge control unit of the battery management system includes a step 604 of continuously monitoring the battery cells and checking the battery cell voltage. When the battery cell voltage exceeds a predefined threshold voltage (step 606), the charge control unit of the battery management system stops the charging process (step 608), disconnects the battery cell from the output terminal and emulates the voltage at the output terminal By including the step, the overvoltage protection mode is entered. When the output terminal is connected to the charger and the charging voltage is high, the battery goes into overvoltage protection mode, preventing the battery cell from outputting voltage, thus preventing charging of other batteries connected in parallel.

When the battery runs out of charge and enters the undervoltage protection mode, the battery management system allows the battery to periodically output a low voltage at the output terminals. A timer may be set by the user via the user interface unit 318 to control the duration of the undervoltage protection mode. When the timer expires, the battery exits protection mode and the battery management system shuts down the battery so that the battery cells are not damaged. The user can set the frequency of the output voltage using the user interface unit, so that the charge of the battery can be preserved for a longer time. Optionally, the user may shut down the battery using the user interface unit 318 . The user can also wake the battery from the low voltage protection mode using the user interface unit. The user can check the status of each individual battery cell by selecting through the user interface unit, and the status of the selected battery cell will be displayed by the status display unit 302 .

7 depicts an exemplary operation 700 of a battery management system. When the battery management system detects the output voltage at terminals 218 and 220 is below a predetermined threshold voltage (step 702), the battery management system enters the battery into a low voltage protection mode (step 706). If the terminal voltage is above a predetermined threshold voltage, the normal operation of the battery will continue (step 704). While in low voltage protection mode, the battery management system will cause the battery to emulate a lead acid battery by periodically outputting a low voltage. This burst undervoltage is important because it allows the charger to detect the presence of the battery. When the battery management system detects that the battery is connected to the charger, i.e., the voltage at the output terminal is higher than the predetermined voltage (step 708), the battery management system causes the battery to exit the low voltage protection mode (step 714) ). Charging starts. A timer starts when the battery goes into undervoltage protection mode. When the timer expires (step 710), the battery management system will cease operation (step 712). The timer is used to avoid complete depletion of the battery cells, thus avoiding damage to the battery cells. The frequency of the timer and voltage output can be adjusted by the user through the user interface. The user can choose to use the output voltage less frequently and extend the timer, so the battery will provide the output voltage at the terminal less often but for a longer period of time.

While in low voltage protection mode, the battery management system will indicate that the battery is in protection mode. A user may “wake up” the battery by entering a command via user interface unit 318 . The wake-up command will instruct the battery management system to stop protection mode.

The status display unit 302 is connected to the LED display and will display the battery status, charging stage, operating mode, charging status and error code.

In use, a lithium battery equipped with the battery management system of the present invention can be connected in parallel to an external load through the respective output connectors 218 and 220, and thus can deliver a large combined current. During the charging process, charger 412 delivers a charging current to each of the lithium batteries.

Charge current flows through output connector 218 , battery cell 202 , shunt resistor 206 , MOSFETs 210 , 212 and exits output connector 220 . When the battery cell is depleted, the charging current is a constant current and the charging current gradually decreases as the battery cell is charged. The charging current is detected by shunt resistor 206 and the voltage drop across the shunt resistor is compared to a reference voltage at comparator 208 controlling MOSFET 210 . When the charging current is large and the voltage drop is greater than the reference voltage, MOSFET 210 turns on and a charging current flows through MOSFET 210 .

When the battery cell is charged and the charging current is small, the comparator 208 detects that the voltage drop across the shunt resistor 206 is small and turns off the MOSFET 210 . When MOSFET 210 is OFF, a small charging current flows through the diode connected in parallel to MOSFET 210 . During the charging process, MOSFET 212 is ON. Since MOSFET 210 is OFF and a small charge current continues to flow through the diode, such a lithium battery is prevented from accidentally discharging and damaging a similarly connected adjacent lithium battery.

During the discharge process, the discharge current flows in the reverse direction. Discharge current flows from battery cell 202 through output connector 218 , an external load, back output connector 220 , MOSFETs 212 , 210 and shunt resistor 206 . The discharge current is initially large and gradually decreases. MOSFET 212 will be ON when the discharge current is large, and will be turned OFF by comparator 214 when the discharge current detected by shunt resistor 206 decreases. During the discharge process, MOSFET 210 is on.

When the discharge current drops to a low level, to prevent damage to the battery cell 202 , the MOSFET 212 is turned off and a small discharge current is passed through a diode connected in parallel to the MOSFET 212 . This small current allows charger 412 to detect the presence of a lithium battery. As described above, a small current can be output in the PWM mode or the PFM mode, so that the storage life of the lithium battery can be extended.

MOSFETs 210 and 212 control the path of current flowing through the lithium battery and its operation is controlled by controller 216 and comparators 208 and 214 . MOSFET operation can be summarized in the table below.

At the end of the discharging process, when each of the battery cells is depleted, the MOSFET 210 will be turned off. As MOSFET 210 is turned off, emulator MOSFET 402 is periodically turned on in pulsed mode as described above, and resistors 404, 406, 408 are paralleled to apply voltage to output connectors 218, 220 forward to By choosing an appropriate resistor, a lithium battery can be designed to emulate a specific voltage that the charger will sense before starting the charging process.

When the battery is shipped after it has been manufactured, the battery can be set to shipping mode and there is no output voltage at terminals 218 and 220 . When the battery is connected to the charger 412 it will exit the shipping mode. When the battery goes out of the shipping mode, the emulator MOSFET 402 is periodically turned on in a pulsed mode as described above, and the frequency of the pulsed mode can be adjusted through a user command. Adjusting the pulse mode can extend the life of the battery. By making the voltage available at the output terminal, the availability of the battery can be detected by the load or charger when the battery is in use. The period for outputting the voltage in the pulse mode may be adjusted by a timer as described above.

The battery management system of the present invention may further be coupled to an energy recovery unit 418 that captures energy recaptured during a stoppage of the mobile vehicle or golf cart as shown in FIG. 4 . Energy regeneration unit 418 may be assembled into any system that dissipates energy in a particular cycle of operation. The dissipated energy can be recovered by the energy recovery unit 418 and used to charge the rechargeable battery. Charger 412 may use energy from an external power source 416 (not shown) or energy recovery unit 418 to charge the rechargeable battery. Energy regeneration unit 418 may optionally be connected to a separate charger and a switch (not shown) may use a charger connected to external power source 416 or use recaptured energy from energy regeneration unit 418 to the battery. Used to select whether to recharge or not.

The determination of whether to connect the energy regeneration unit 418 to the charger 412 is controlled by a controller 216 , which controls the information received from the motion detector 414 (motion indicator) and the energy regeneration unit. It makes such a determination based on the voltage detected at the output port of 418 . Motion detector 414 and controller 216 may be implemented as a single chip or alternatively as separate devices. The motion detector 414 may indicate whether the vehicle on which it is mounted is moving.

8 is a flow diagram 800 of a recharge operation for a battery management system equipped with a motion detector 414 and coupled to an energy regeneration unit 418 . The controller 216 receives data from the motion detector 414 indicating whether the vehicle or golf cart is moving. Controller 216 also monitors the output voltage from energy recovery unit 418 (step 804). If the output voltage from the energy regeneration unit 418 is less than (not greater than) the charging voltage of the battery (step 806), it indicates that there is no recaptured energy, and then no charging operation is required (step 808). If the output voltage from the energy regeneration unit 418 is greater than the battery, then the recharge circuit is activated (step 810 ), and the energy regeneration unit 418 is connected to the charger 412 . A recharge circuit is within the charger 412 . It is checked whether the vehicle is moving (step 812). When the vehicle is moving, the energy recovery unit 418 is connected to the charger 412 (step 814), and energy from the energy recovery unit 418 is used to charge the battery (step 818). If the vehicle is not moving, charger 412 is connected to an external power source (step 816) and uses voltage from this power source to charge the battery. The steps shown in Figure 8 may be executed in a different order to achieve the same result. Information about the battery charging voltage may be retrieved from a storage unit connected to the controller 216 or retrieved from the battery.

9 is a flow diagram 900 for the operation of stopping a charging process. While the battery is being charged with the recaptured energy from the energy recovery unit 418 , the controller 216 continuously monitors the output voltage from the energy recovery unit 418 . As energy is consumed, the output voltage from the energy recovery unit 418 drops. If the output voltage is higher than the charging voltage of the battery, the charging operation continues (step 904). When the output voltage drops below the charging voltage (step 902 ), the controller 216 breaks the recharge circuit to the charger 412 and the energy recovery unit 418 is disconnected from the charger 412 (step 906 ). When the connection between the battery and the energy regeneration unit 418 is cut off, the charging operation is stopped.

During the recharging process using energy from the energy regeneration unit 418, the same protection of the battery cells against overcharging is provided as described above by way of the accompanying description.

While the present invention has been shown and described with reference to the preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as set forth in the following claims. Also, although elements of the invention may be described or claimed in the singular, the plural may be contemplated unless limitations to the singular are explicitly stated. Combinations of different features described in different embodiments herein are foreseeable and are within the scope of the present invention.

5-8, the steps described above do not require or imply any specific order of operations. The operations may be executed sequentially or in parallel. Such a method may be implemented by a controller executing a series of machine readable instructions. The instructions may reside in various types of signal bearing or data storage media.

Claims (17)

A lithium battery (106) comprising a plurality of output terminals, comprising:
a plurality of battery cells 202 to which the lithium batteries are connected in series; and a battery management unit 154, wherein the battery management unit 154 comprises:
controller 216; a plurality of battery cells (202) and a sensing unit (156) connected to the controller (216);
a charge control unit (158) having a first MOSFET (210) and a first diode connected in parallel with the first MOSFET and connected to the controller (216);
a discharge control unit (160) having a second MOSFET (212) and a second diode connected in parallel with the second MOSFET and connected to the controller (216);
The sensing unit (156, 208, 214) senses the first voltage drop across the shunt resistor (206) connected to one of the output terminals of the lithium battery (106),
When the first voltage drop exceeds the first threshold voltage, the first MOSFET 210 is turned on, and when the first voltage drop falls below the first threshold voltage, the first MOSFET 210 is turned off ,
An emulator MOSFET 402 is connected to a controller 216 which periodically turns the emulator MOSFET 402 in pulsed mode when both the discharge control unit 160 and the charge control unit 158 are turned off. A lithium battery comprising a plurality of output terminals characterized by turning on. The lithium battery of claim 1, wherein when the first voltage drop is below the first threshold voltage drop and the first MOSFET (210) is off, current flows through the first diode. 2. The method of claim 1, wherein a second MOSFET (212) is on when the first voltage drop is greater than or equal to a second threshold voltage, and
wherein the second MOSFET (212) is off when the first voltage drop is less than or equal to a second threshold voltage. 4. The lithium battery of claim 3, wherein when the second voltage drop is below the second threshold voltage drop and the second MOSFET (212) is off, current flows through the second diode. The lithium battery according to claim 1, further comprising a status indication unit (302) in communication with a battery management system (154), wherein the status indication unit displays a status of the battery management system. The lithium battery of claim 1, further comprising a user interface unit (318) in communication with a battery management system (154), the user interface unit receiving commands from a user. The method according to claim 6, wherein the lithium battery outputs a first output voltage of a pulse mode with a command received from the user, so as to mimic a rechargeable battery module;
A lithium battery that simulates the voltage and current characteristics of a lead-acid battery (104) during a charging process and allows the battery system to identify and accept a rechargeable lithium battery (106) module. The lithium battery of claim 7 , wherein a command received from a user changes the frequency of the first output voltage. The lithium battery of claim 1, wherein the frequency of the pulsed mode is adjusted by the controller (216). 2. The method of claim 1, further comprising a timer, the timer being started when the emulator MOSFET (402) is turned on and off by the controller (216), and the controller (216) is configured to activate the control of the emulator MOSFET (402) when the timer expires. Lithium battery to stop on and off. The lithium battery according to claim 1, wherein the sensing unit (156) senses the temperature and voltage of each of the battery cells. A method of recharging a lithium battery (106), comprising:
a plurality of battery cells (202) for the lithium battery to emulate a lead-acid battery (104); controller 216; sensing units (156, 208, 214); a charge control unit 158 having a first MOSFET 210; and a discharge control unit 160 having a second MOSFET 212,
sensing a first voltage drop across a shunt resistor (206) connected to an output terminal of the lithium battery (106) by the sensing unit (156, 208, 214);
turning off the first MOSFET (210) by the charge control unit (158) if the first voltage drop is higher than a first threshold voltage;
turning on the first MOSFET (210) by the charge control unit (158) when the first voltage drop is lower than the first threshold voltage;
turning on the second MOSFET (212) by the discharge control unit (160) when the first voltage drop is higher than a second threshold voltage; and
turning off the second MOSFET (212) by the discharge control unit (160) if the first voltage drop is lower than the second threshold voltage;
When the first MOSFET (210) and the second MOSFET (212) are turned off by the emulator MOSFET (402), one output voltage is output in a pulsed mode. 13. The method of claim 12, further comprising: receiving a command by a user interface unit (318); and stopping the output voltage output in the pulsed mode by the controller (216). 13. The method of claim 12, further comprising: receiving a command by a user interface unit (318); and changing a pulse mode frequency of the output voltage by the controller (216). 13. The method of claim 12, further comprising: receiving status information from the plurality of battery cells (202) by the sensing unit (156); and displaying the status information by a status display unit (302). 13. The method of claim 12, further comprising: starting a timer when the output voltage of the pulsed mode starts; and when the timer expires, stopping the output voltage of the pulse mode. 13. The method of claim 12, further comprising sensing the temperature and voltage of each battery cell (202).

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