Power output management apparatus of battery and managment method thereof

A power output management apparatus of a battery and a management method thereof are provided. The management method includes: enabling a power output mode and discharging a battery to a load via a discharge circuit in the power output mode; calculating the output power of the discharge circuit during the discharge; comparing the output power and a target power to generate a comparison result; and setting the output power being adjusted step by step by a unit compensation amount via the discharge circuit according to the comparison result.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application no. 201610669809.2, filed on Aug. 15, 2016. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a power output management apparatus of a battery and a management method thereof, and more particularly, to a power output management apparatus of a battery adjusting output power via adaptation and a management method thereof.

Description of Related Art

In the field of modern technology, a general lithium battery management system uses the open-circuit voltage as the basis for the estimation of the initial capacity of a battery. However, based on the electrochemical properties of the battery, the state of battery capacity decline is hard to learn. In prior art, after a plurality of charge-discharge cycles is formed for the battery, one estimation of an open-circuit voltage curve can be performed. The estimation of the battery initial capacity is performed via the open-circuit voltage curve. This estimation result often produces error in battery capacity due to the battery capacity decline.

To solve the issue of estimation error, the prior art adopts a method of battery learning and estimates the capacity decline by comparing the difference in battery charge-discharge Ampere-hour (AH). After the method is applied and used in the battery for a certain period, battery learning is performed to correct the size of remaining capacity. In prior art, when the battery is learning, the system needs to shut down due to the learning, and therefore the work efficiency of the system is reduced.

SUMMARY OF THE INVENTION

The invention provides a battery management apparatus and a battery power output management method to effectively control the power output benefit of a battery.

The power output management method of a battery of the invention includes: enabling a power output mode and discharging a battery to a load via a discharge circuit in the power output mode; calculating an output power of the discharge circuit during the discharge; comparing the output power and a target power to generate a comparison result; and adjusting the output power step by step via the discharge circuit according to a unit compensation amount and the comparison result.

The battery management apparatus of the invention includes a battery, a discharge circuit, and a controller. The discharge circuit is coupled to the battery and coupled to a DC bus, the DC bus is coupled to a load, and the discharge circuit discharges the battery to the load in a power output mode. The controller is coupled to the discharge circuit, the controller calculates the output power of the discharge circuit during the discharge and compares the output power and a target power to generate a comparison result, and adjusts the output power step by step via the discharge circuit according to a unit compensation amount and the comparison result.

Based on the above, in the invention, by adjusting the output power of the discharge circuit step by step during discharge, the output power of the discharge circuit can meet system requirements. As a result, the DC bus in an embodiment of the invention can receive power supplied by the battery and another external DC power at the same time without sharing current by backing up each other, and therefore the stability of the power supply is increased.

DESCRIPTION OF THE EMBODIMENTS

Referring toFIG. 1,FIG. 1shows a flow chart of a power output management method of a battery of an embodiment of the invention. In step S110, a power output mode of a battery is enabled, and a discharge operation is operated on a battery to a load via a discharge circuit in the power output mode. Moreover, in step S120, during a time period of the discharge operation, the output power of the discharge circuit is calculated. Next, step S130is performed to compare the calculated output power and a target power and accordingly generate a comparison result. Then, in step S140, the discharge circuit sets the output power being adjusted step by step by a unit compensation amount via the discharge circuit according to the comparison result, wherein, the unit compensation amount and the comparison result are generated in step S130.

In detail, in the power output management method of the invention, before entering the power output mode, whether the storage capacity of the battery is greater than a first preset value can be first determined, and whether the battery is in a discharged state at this point is determined. If the storage capacity of the battery is detected to be greater than the first preset value and the battery is not in the discharged state at this point, then the battery can enter the power output mode. In contrast, if the storage capacity of the battery is not greater than the first preset value and/or the battery is in the discharged state, then the battery cannot enter the power output mode.

It should be mentioned that, the power output mode can also be a battery learning mode, and can also be a normal power supply mode for driving the battery. Moreover, the first preset value can be 98% of the total storage capacity of the battery.

Moreover, in step S120, during the discharge operation, the output voltage and the output current generated by the discharge circuit can be sampled, and the output voltage and the output current can be computed to obtain the output power provided by the discharge circuit (equal to about the output power of the battery at this point).

The output power obtained in step S120is compared with the target power set in step S130and the difference of the output power and the target power is calculated. The unit compensation amount can be set according to the calculated difference of the output power and the target power. In particular, the unit compensation amount can be direct proportion to the difference of the output power and the target power. For instance, if the difference of the output power and the target power is 100 W, then the unit compensation amount can be set to 50 W, and if the difference of the output power and the target power is 50 W, then the unit compensation amount can be set to 15 W.

Moreover, the target power is not necessarily a fixed value. The target power can be dynamically adjusted according to load requirements.

In step S140, when the difference is greater than a critical difference, the output power of the discharge circuit is adjusted. In particular, the adjustment of the output power in an embodiment of the invention is not a compensation occurring in one step. In an embodiment of the invention, the output power can be increased or decreased step by step according to the unit compensation amount and accordingly reduce the occurrence of ripples. Moreover, the unit compensation amount can be set according to the size of the difference, wherein when the difference is greater, the set unit compensation amount is greater, and when the difference is smaller, the set unit compensation amount is smaller. As a result, the adjustment speed of the output power can also be taken into account.

It should be mentioned that, the adjustment method of the output power can be performed in a digital manner. Referring to bothFIG. 1andFIG. 2A,FIG. 2Ashows a schematic of an output power adjustment method of an embodiment of the invention. In the present embodiment, the output power of the discharge circuit can be controlled according to one pulse-width modulation signal PWM1. In particular, the pulse-width modulation signal PWM1can be inputted to a filter210. The filter210generates a reference voltage Vref corresponding to the pulse-width modulation signal PWM1. By sending the reference voltage Vref to the discharge circuit, the discharge circuit can adjust the size of the output power according to the voltage level of the reference voltage Vref.

When the output power of the discharge circuit is to be adjusted step by step, the number of pulses in the unit time of the pulse-width modulation signal PWM1can be increased or decreased according to the set unit compensation amount. It can be known from the relationship of the number of pulses and the reference voltage Vref shown inFIG. 2Bthat, when the number of pulses in the unit time of the pulse-width modulation signal PWM1is increased, the voltage value of the reference voltage Vref can be correspondingly increased, and at the same time, the output power of the discharge circuit can be increased according to the increased reference voltage Vref. In contrast, when the number of pulses in the unit time of the pulse-width modulation signal PWM1is reduced, the voltage value of the reference voltage Vref can be correspondingly reduced, and at the same time, the output power of the discharge circuit can be reduced according to the reference voltage Vref.

The power output mode of the above embodiments can be a battery learning mode. Accordingly,FIG. 3shows a flow chart of a battery learning mode of an embodiment of the invention. In particular, after the learning is started, step S310can detect whether the battery can currently meet the learning conditions. In particular, step S310can detect whether the storage capacity of the battery is greater than a first preset value and whether the battery is currently in a discharged state. If the test result shows that the storage capacity of the battery is greater than the first preset value and the battery is not in the discharged state, then the battery currently meets the learning conditions, and step S330can be performed. On the other hand, if the storage capacity of the battery is not greater than the first preset value and/or the battery is currently in the discharged state, then the battery does not meet the learning conditions, and step S320is performed to show learning failure.

Next, step S330is performed to discharge the battery. In particular, the battery is discharged to a load via a discharge circuit, and the output voltage and the output current generated by the discharge circuit at this point are sampled at the same time. Step S340calculates the output voltage and the output current and obtains an output power. The compensation amount is adjusted according to the output power. Here, the compensation amount can be the unit compensation amount in the above embodiments, and the size of the unit compensation amount can be adjusted according to the difference of the output power and a target power.

In step S340, the pulse-width modulation signal is adjusted according to the compensation amount, and the pulse-width modulation signal is filtered to generate a reference voltage. The adjustment of the pulse-width modulation signal according to the compensation amount can include increasing or decreasing the number of pulses in the unit time of the pulse-width modulation signal according to the compensation amount. The filtering of the pulse-width modulation signal can be completed by a low-pass filter.

Next, in step S370, the reference voltage is sent to the discharge circuit and the size of the output power is adjusted by the discharge circuit according to the change in the reference voltage.

In step S380, whether the discharge amount of the battery is sufficient is determined, wherein in step S380, whether the storage capacity of the battery is less than a second preset value can be determined to determine whether the discharge amount of the battery is sufficient. In particular, the second preset value can be 30% to 40% of the total storage capacity of the battery.

In step S380, when the storage capacity of the battery is determined to be less than the second preset value, the discharge amount of the battery is sufficient, and learning can be ended (step S390). Moreover, in step S380, when the storage capacity of the battery is determined to not be less than the second preset value, the discharge amount of the battery is insufficient, and step S340is repeated and the discharge of the battery is sustained.

It should be mentioned that, when another power supply providing power to the load is present, the battery and another power supply can provide power to the load together or alternately for operation when the battery is learning. In other words, the load does not need to stop when the battery is learning, and normal operation can be maintained.

Referring toFIG. 4,FIG. 4shows a schematic of a battery management apparatus of an embodiment of the invention. The battery management apparatus410is coupled to a battery BAT and a load420. The battery management apparatus410includes a discharge circuit411and a controller formed by a core circuit412and a filter413. The discharge circuit411is coupled to the load420and coupled to the filter413. The core circuit412is coupled between the filter413and the load420.

In the present embodiment, the core circuit412includes an operator4121, a compensation adjuster4122, a limiter4123, and a signal generator4124. In the power output mode, the core circuit412samples an output voltage SV and an output current SI via the output terminal of the discharge circuit411. The operator4121receives the output voltage SV and the output current SI and performs calculations to calculate the output power, and calculates the comparison result of the output power and the target power. The compensation adjustor4122receives the comparison result and adjusts the unit compensation amount according to the comparison result. The compensation adjustor4122adjusts the resulting unit compensation amount to be sent to the limiter4123. The limiter4123can make the value adjusted by the unit compensation amount not too large or too small and be limited in a certain range, and output the limited unit compensation amount to the signal generator4124. The signal generator4124is used to generate the pulse-width modulation signal PWM1, wherein the signal generator4124controls the number of pulses in the unit time of the pulse-width modulation signal PWM1according to the output of the limiter4123.

The pulse-width modulation signal PWM1is sent to the filter413and the filter413filters the pulse-width modulation signal PWM1to generate the reference voltage Vref.

In the present embodiment, the operator4121, the compensation adjuster4122, the limiter4123, and the signal generator4124can be formed by hardware circuits or completed via software executed by a processor. In terms of hardware implementation, for instance, the operator4121can include a multiplier (multiplying the output voltage SV and the output current SI), and the compensation adjuster4122can calculate the difference of the output power and the target power using a subtractor and find the compensation amount according to the difference via a built-in search table. The limiter4123can be formed via a comparator, and the signal generator4124can generate a triangular wave compared to the output of the limiter4123to generate the pulse-width modulation signal PWM1.

Of course, the hardware implementation of the operator4121, the compensation adjuster4122, the limiter4123, and the signal generator4124is only exemplary, and is not intended to limit the scope of the invention.

Moreover, in the present embodiment, the discharge circuit411can be a DC-DC voltage transformer and include a drive and controller4111. The drive and controller4111receives the reference voltage Vref and generates a control signal according to the reference voltage Vref to control transistor switching in the DC-DC voltage converter, so as to control the output power of the discharge circuit411.

Referring toFIG. 5,FIG. 5shows a schematic of a power supply system built by a battery management apparatus according to an embodiment of the invention. The power supply system500includes a battery BAT, a power management apparatus510, and a power supply520. The power supply520and the power management apparatus510are both coupled to a DC bus DC_BUS and provide power to a load530. In particular, the power supply520can receive an AC power VAC (such as mains electricity) and perform AC-DC voltage conversion on the AC power VAC to generate DC power and provide the resulting DC power to the DC bus DC_BUS.

Moreover, the power management apparatus510includes a controller511, a discharge circuit512, and a charge circuit513. The controller511, the discharge circuit512, and the charge circuit513are all coupled to the battery, and the controller511, the discharge circuit512, and the charge circuit513are all coupled to the DC bus DC_BUS.

In the present embodiment, the discharge circuit512can receive the DC power provided by the battery and perform DC-DC voltage conversion, and provide the converted DC power to the DC bus DC_BUS. As a result, the power supply520and the power management apparatus510can provide power to the load530at the same time or separately in parallel. Regarding the details of the power supply of the power supply system500,FIG. 6AtoFIG. 6Cshow waveforms of a power supply system of an embodiment of the invention. In the embodiment ofFIG. 6AtoFIG. 6C, the output power needed for the load530is fixed.

Before a time point t1, the power supply520supplies power normally and provides a stable output voltage V1(such as 12.5 V) to the load530. At the same time, the power management apparatus510provides a relatively-low output voltage V2(such as 12.3 V) to the load530. Therefore, the power needed for the load530at this point is mainly provided by the power supply520, and the power supply520provides a non-zero output current I1and the power management apparatus510provides a zero output current I2.

Next, at the time point t1, the power management apparatus510enables the power output mode (learning mode) and increases the outputted voltage V2to, for instance, 12.8 V (greater than the voltage V1) and discharges the battery BAT from the time point t1. Moreover, from the time point t1to a time point t2, since the voltage V2is greater than the voltage V1, the power needed for the load530at this point is mainly provided by the battery BAT. Therefore, the power supply520provides a zero output current I1and the power management apparatus510provides a non-zero output current I2.

At the time point t2, the power management apparatus510puts the battery BAT in constant power discharge mode. Moreover, from the time point t2to a time point t3, the power management apparatus510enables the compensation of the output power and adjusts the output power to reach a target power. In the present embodiment, the output power is greater than the target power, and therefore the compensation of the output power of the power management apparatus510reduces the value of the output current I2to reduce the output power. At the same time, the output current I1provided by the power supply520is increased to complement the output power of the battery reduced by the power management apparatus510.

From the time point t3to a time point t4, the output power of the battery BAT is adjusted to be equal to the target power, and therefore the output power generated by the battery BAT and the power supply520is constant. At the time point t4, the discharge of the battery BAT is complete and the power management apparatus510stops the battery BAT from discharging, and the power needed for the load530is provided by the power supply520.

Of course, the output power needed for the load in the embodiments of the invention is not limited to be fixed and invariable. In actual application, the output power needed for the load can be adjusted with time or environmental temperature.

Based on the above, the battery management apparatus and the power output management method provided by the invention allow a battery to supply power to a load when the battery is discharged. In other words, when the battery is learning, the load can continue to operate without shutting down, thus increasing production efficiency. Moreover, in the invention, by compensating the output power step by step, ripples generated when the output power is adjusted can be effectively reduced, and therefore the quality of the power output is maintained.