Claims:I/We claim:
1. A method for charging at least one battery (107) in an electric vehicle, the method comprising:
receiving, by a microcontroller (101), from an Electronic Control Unit (ECU) (108), a reference voltage, a reference current, a maximum operating voltage of the battery (107) and a maximum operating current of the battery (107);
converting, by the microcontroller (101), the reference voltage to a set voltage;
converting, by the microcontroller (101), the reference current to a set current;
measuring, by the microcontroller (101), a value of voltage and a value of current at terminals of the battery (107);
generating, by a Constant Voltage-Constant Current (CC-CV) circuit (102), a control voltage based on the set voltage, the set current, the measured value of voltage at the terminals of the battery (107), and the measured value of current at the terminals of the battery (107); and
charging, by an isolated Direct Current-Direct Current (DC-DC) converter (104), the battery (107) through a signal, generated based on the control voltage, wherein the signal is generated by one of a Pulse Width Modulation (PWM) controller (103), a phase shift controller, and a frequency shift controller.
2. The method, as claimed in claim 1, wherein the signal is a PWM pulse with a duty cycle generated by the PWM controller (103), wherein the PWM pulse is generated based on a sawtooth waveform and the control voltage.
3. The method, as claimed in claim 1, wherein the method further comprises:
measuring, by the microcontroller (101), an updated value of voltage and an updated value of current at the terminals of the battery (107);
generating, by the microcontroller (101), an updated set voltage based on a difference between the set voltage and the measured updated value of voltage at the terminals of the battery (107);
generating, by the microcontroller (101), an updated set current based on a difference between the first set current and the measured updated value of current at the terminals of the battery (107);
generating, by the CC-CV circuit (102), an updated control voltage based on the updated set voltage, the updated set current, the measured updated value of voltage at the terminals of the battery (107), and the measured updated value of current at the terminals of the battery (107); and
charging, by the isolated DC-DC converter (104), the battery (107) through an updated signal generated based on the updated control voltage, wherein the updated signal is generated by one of the PWM controller (103), the phase shift controller and the frequency shift controller.
4. The method, as claimed in claim 3, wherein the updated signal is an updated PWM pulse with an updated duty cycle, wherein the updated PWM pulse is generated by the PWM controller (103) based on the sawtooth waveform and the updated control voltage.
5. The method, as claimed in claim 3, wherein the measured value of voltage at the terminals of the battery (107) and the measured updated value of voltage at the terminals of the battery (107) are measured by a voltage measurement circuit (106).
6. The method, as claimed in claim 3, wherein the measured value of current at the terminals of the battery (107) and the measured updated value of current at the terminals of the battery 107) are measured by a current measurement circuit (105).
7. The method, as claimed in claim 3, wherein the updated set voltage is equal to the maximum operating voltage of the battery (107) and the updated set current is equal to the reference current, wherein the updated value of voltage at the terminals of the battery (107) is less than the maximum operating voltage of the battery (107).
8. The method, as claimed in claim 3, wherein the updated set voltage is equal to the reference voltage and the updated set current is equal to the maximum operating current of the battery (107), wherein the updated value of voltage at the terminals of the battery (107) is equal to the maximum operating voltage of the battery (107).
9. The method, as claimed in claim 1, wherein the method further comprises calibrating at least one of the microcontroller (101) and the CC-CV circuit (102) based on a slope and an offset of instantaneous voltage and current at terminals of the battery (107).
10. A charging system (100) for charging at least one battery (107) in an electric vehicle, the charging system (100) configured to:
receive, by a microcontroller (101), from an Electronic Control Unit (ECU) (108), a reference voltage, a reference current, a maximum operating voltage of the battery (107) and a maximum operating current of the battery (107);
convert, by the microcontroller (101), the reference voltage to a set voltage;
convert, by the microcontroller (101), the reference current to a set current;
measure, by the microcontroller (101), a value of voltage and a value of current at terminals of the battery (107);
generate, by a Constant Voltage-Constant Current (CC-CV) circuit (102), a control voltage based on the set voltage, the set current, the measured value of voltage at the terminals of the battery (107), and the measured value of current at the terminals of the battery (107); and
charge, by a isolated Direct Current-Direct Current (DC-DC) converter (104), the battery (107) through a signal, generated based on the control voltage, wherein the signal is generated by one of a Pulse Width Modulation (PWM) controller (103), a phase shift controller, and a frequency shift controller.
11. The charging system (100), as claimed in claim 10, wherein the signal is a PWM pulse with a duty cycle generated by the PWM controller (103), wherein the PWM pulse is generated based on a sawtooth waveform and the control voltage.
12. The charging system (100), as claimed in claim 10, wherein the charging system (100) is further configured to:
measure, by the microcontroller (101), an updated value of voltage and an updated value of current at the terminals of the battery (107);
generate, by the microcontroller (101), an updated set voltage based on a difference between the set voltage and the measured updated value of voltage at the terminals of the battery (107);
generate, by the microcontroller (101), an updated set current based on a difference between the first set current and the measured updated value of current at the terminals of the battery (107);
generate, by the CC-CV circuit (102), an updated control voltage based on the updated set voltage, the updated set current, the measured updated value of voltage at the terminals of the battery (107), and the measured updated value of current at the terminals of the battery (107); and
charge, by the isolated DC-DC converter (104), the battery (107) through an updated signal generated based on the updated control voltage, wherein the updated signal is generated by one of the PWM controller (103), the phase shift controller and the frequency shift controller.
13. The charging system (100), as claimed in claim 12, wherein the updated signal is an updated PWM pulse with an updated duty cycle, wherein the updated PWM pulse is generated by the PWM controller (103) based on the sawtooth waveform and the updated control voltage.
14. The charging system (100), as claimed in claim 12, wherein the measured value of voltage at the terminals of the battery (107) and the measured updated value of voltage at the terminals of the battery (107) are measured by a voltage measurement circuit (106).
15. The charging system (100), as claimed in claim 12, wherein the measured value of current at the terminals of the battery (107) and the measured updated value of current at the terminals of the battery (107) are measured by a current measurement circuit (105).
16. The charging system (100), as claimed in claim 12, wherein the updated set voltage is equal to the maximum operating voltage of the battery (107) and the updated set current is equal to the reference current, wherein the updated value of voltage at the terminals of the battery (107) is less than the maximum operating voltage of the battery (107).
17. The charging system (100), as claimed in claim 12, wherein the updated set voltage is equal to the reference voltage and the updated set current is equal to the maximum operating current of the battery (107), wherein the updated value of voltage at the terminals of the battery (107) is equal to the maximum operating voltage of the battery (107).
18. The charging system (100), as claimed in claim 10, wherein the charging system (100) is further configured to calibrate at least one of the microcontroller (101) and the CC-CV circuit (102) based on a slope and an offset of instantaneous voltage and current at terminals of the battery (107).
, Description:TECHNICAL FIELD
[001] Embodiments disclosed herein relate to battery charging systems, and more particularly to methods and systems for supplying adequate voltage and current to a battery of an electric vehicle, while charging the battery of the electric vehicle.

BACKGROUND
[002] Currently, errors may be encountered while measuring and controlling voltage and current at terminals of a battery of an electric vehicle. An Electronic Control Unit (ECU) or another Control Unit (CU) can provide a charger of the battery with a reference voltage and a reference current that is to be maintained at the terminals of the battery. However, the charger may not be able to maintain the voltage and the current being driven in to the battery at the reference voltage level and the reference current level. This may be due to errors in offset and gains present in power circuits and signal conditioning circuits in the charger. The error can occur due to reasons such as, temperature variation, variance introduced during manufacturing, tolerance in the components of the circuits in the charger, and so on. As there is no precise control over the voltage and current driven in to the battery by the charger, an optimized charging profile with respect to battery characterization may not be possible.

OBJECTS
[003] The principal object of embodiments herein is to disclose methods and systems for controlling the voltage and current supplied by a charging system to a battery in an electric vehicle at a predetermined reference voltage level/value and a predetermined reference current level/value, when the battery is being charged.
[004] Another object of embodiments herein is to accurately measure voltage and current at the terminals of charging system connected to the battery by calibrating hardware elements of the charging system.
[005] Another object of embodiments herein is to measure actual voltage and current values at the terminals of the charging system connected to the battery and compare the measurements with the predetermined reference voltage and current values and ensure that the voltage and current supplied at the terminals of the battery follow the predetermined reference voltage and current values.
[006] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating at least one embodiment and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF FIGURES
[007] Embodiments herein are illustrated in the accompanying drawings, through out which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[008] FIG. 1 is a block diagram depicting a charging system for supplying voltage and current to a battery in an electric vehicle, while charging the battery, according to embodiments as disclosed herein;
[009] FIG. 2 depicts an example of a Constant Current-Constant Voltage (CC-CV) circuit and a Pulse Width Modulation (PWM) controller of the charging system, according to embodiments as disclosed herein;
[0010] FIG. 3 is an example graph depicting variations of voltage and current at the terminals of the battery while charging the battery, according to embodiments as disclosed herein;
[0011] FIG. 4 depicts an example arrangement for measurement of voltage and current values at the terminals of the charger connected to battery, according to embodiments as disclosed herein;
[0012] FIG. 5 depicts an example circuit to compensate for errors between a predetermined reference voltage and current values, and actual values of voltage and current measured at the terminals of the battery, according to embodiments as disclosed herein;
[0013] FIG. 6 depicts an example state machine for determining the mode of charging (CC or CV) of the battery, according to embodiments as disclosed herein; and
[0014] FIG. 7 is a flowchart depicting a method for controlling the voltage and current supplied to a battery in an electric vehicle at the predetermined reference voltage level/value and the predetermined reference current level/value, according to embodiments as disclosed herein.

DETAILED DESCRIPTION
[0015] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0016] The embodiments herein provide methods and systems for controlling the voltage and current supplied to a battery in an electric vehicle at a predetermined reference voltage level/value and a predetermined reference current level/value, when the battery is being charged. Referring now to the drawings, and more particularly to FIGS. 1 through 7, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0017] FIG. 1 is a block diagram depicting a charging system for supplying voltage and current to a battery in an electric vehicle, while charging the battery, according to embodiments as disclosed herein. An electric vehicle can include a battery 107, which can act as the main energy source; power electronic modules such as the charging system 100, an isolated DC-DC (Direct Current) 104, a motor and motor controller (not shown); and the embedded components such as vehicle controller unit or Electronic Control Unit (ECU) 108, a Battery Management System (BMS) (not shown), and so on. In an embodiment herein, the vehicle may comprise one or more battery cells, wherein the battery cells can be connected in a series and/or parallel connection. The battery cells can supply the energy requirements of the vehicle. In an embodiment herein, the vehicle may comprise one or more batteries, wherein the batteries can be charged in a combined manner.
[0018] The charging system 100 can comprise a plurality of sections, viz., an active power factor controlled Alternating Current-Direct Current (AC-DC) section and an isolated DC–DC section. Based on the involved power levels, different topologies can be used in AC-DC stage. For example, in the isolated DC-DC section, the commonly used topologies can be full bridge phase shifted or half-bridge/Full-bridge LLC (inductor/capacitor) resonant circuits.
[0019] As depicted in FIG. 1, the charging system 100 includes an Alternating Current (AC) grid 113, an Electro-Magnetic Interference (EMI) filter 109, a bridge rectifier 110, a Power Factor Correction circuit (PFC) 111, an isolated DC-DC converter 104, a current measuring circuit 105, a voltage measuring circuit 106, an isolated gate driver circuit 112, a microcontroller 101, a Constant Current-Constant Voltage (CC-CV) circuit 102, and a Pulse Width Modulation (PWM) controller 103.
[0020] The AC grid 113 can draw AC from at least one external source (such as power mains, regenerative braking systems, green sources of energy (such as solar power), another battery, and so on) and supply AC power to the charging system 100. The Electro-Magnetic Interference (EMI) filter 109 can filter unwanted or interfering EM waves. The bridge rectifier 110 can convert AC power into DC power,
[0021] The charging procedure of the battery involves the charger deriving power from the AC grid and converting the AC power into DC and delivering DC power to the battery. While delivering the DC power, the isolation architecture in the charging system 100 can isolate the load (Battery) 107 from the AC grid 113 in the event of a battery short circuit.
[0022] The microcontroller 101 can receive the actual voltage and current values at the terminals of the battery 107 (or the actual voltage and actual current values measured at the terminals of the charging system 100 connected to the battery 107) as inputs. The actual voltage and current values can be measured by the voltage and current measuring circuits (106, 105) respectively. The microcontroller 101 can use values of slopes and offsets of voltage and current values, measured by the voltage and current measuring circuits (106, 105) respectively. The values of the slopes and the offsets are stored in the non-volatile memory and retrieved by the microcontroller 101 to detect and rectify errors incurred by the voltage and current measuring circuits (106, 105) in measuring Vbatt and Ibatt, i.e., actual voltage and current values at the terminals of the charging system 100 connected to the battery 107.
[0023] The battery 107 can be charged using DC power using the isolated DC-DC converter 104 (isolated from the AC stages). The isolated DC-DC converter 104 can provide the DC power to the battery 107 on receiving a PWM pulse from the PWM controller 103, which in turn can generate the PWM pulse based on a control voltage Vc. This control voltage Vc can be utilized for PWM control DC-DC converters or for frequency controlled DC-DC converters.
[0024] In an embodiment, the isolated DC-DC converter 104 can provide the DC power to the battery 107 through a signal. The signal can be received from a frequency shift controller (not shown) or a phase shift controller (not shown). The frequency shift controller and the phase shift controller can receive the control voltage and generate the signal. With a modification of the control voltage, either the phase (if phase shift controller is used) or the frequency (if phase frequency shift controller is used) of the signal can be updated based on a power topology used, for controlling the values of voltage and current delivered to the terminals of the battery 107 by the charging system 100.
[0025] The control voltage Vc can be generated by the CC–CV circuit 102, which can operate in either a CC (Constant Current) mode or a CV (Constant Voltage) mode. The microcontroller 101 can use the CC-CV circuit 102 to ensure that Vbatt and Ibatt follow a predetermined reference voltage Vref and current Iref, received from an external ECU 108. The microcontroller 101 can convert the Vref and Iref into an initial set voltage Vset and initial set current Iset respectively. The initial values of Vset and Iset can ensure that Vbatt and Ibatt follow Vref and Iref respectively. The CC-CV circuit 102 can receive the initial values of Vset and Iset from the microcontroller 101, and the Vbatt and Ibatt from the voltage measuring circuit 106 and the current measuring circuit 105 respectively, as inputs. Based on the inputs the CC-CV circuit 102 can generate the control voltage Vc.
[0026] When the microcontroller 101 detects a difference (error) between Ibatt and the initial Iset, the microcontroller 101 can update the initial Iset, such that Ibatt follows Iref. This can be done in a continuous manner, to ensure that Ibatt follows Iref. The CC-CV circuit 102 can generate an updated control voltage Vc and the PWM controller 103 can generate an updated PWM pulse with a duty cycle. The pulse fed to the isolated DC-DC converter 104 can feed DC power to the battery 107 based on the updated pulse, to ensure that Ibatt follows Iref. Similarly, when an error is detected between Vbatt and the initial Vset, the microcontroller 101 can update the initial Vset, such that Vbatt follows Vref.
[0027] In the CC mode, the charging system 100 can be configured as a constant current source. When the State of Charge (SoC) of the battery 107 is at or below a pre-defined charge threshold, the CC-CV circuit 102 can operate in the CC mode, wherein the microcontroller 101 can compensate for an error between the current at the battery terminals Ibatt and the set current Iset. In the CC mode, the microcontroller 101 can attempt to set Iset as equal to Ireq and Vset as equal to Vmax. In the CC mode, the microcontroller 101 can compensate for the error between Ibatt and Iset by setting Iset as equal to a required current Ireq (Iref) and Vset as equal to a maximum operating voltage of the battery 107, i.e., Vmax. Once the microcontroller 101 detects that Vbatt is equal to Vmax, the CC-CV circuit 102 operates in the CV mode.
[0028] In the CV mode, the microcontroller 101 can attempt to set Vset as equal to Vreq and Iset as equal to Imax. In the CV mode, the charging system 100 can be configured as a constant voltage source. The microcontroller 101 can detect an error between the voltage at the terminals of the battery 107, Vbatt, and set voltage Vset. In the CV mode, the microcontroller 101 can compensate for the error between Vbatt and Vset by updating the initial Vset to Vreq, such that Vbatt follows Vref. This can be done in a continuous manner, to ensure that Vbatt follows Vref.
[0029] FIG. 2 depicts example of the CC-CV circuit 102 and the PWM controller 103 of the charging system, 100 according to embodiments as disclosed herein. As depicted in the example in FIG.2, the CC-CV circuit 102 can be designed using operational amplifiers (OP Amps). The inputs to the OP Amp O1 are Vbatt and Vset. The inputs to the OP Amp O2 are Ibatt and Iset.
[0030] In the CC mode, the SoC of the battery 107 is low and Vbatt is less than Vset. Therefore, diode D1 is reverse biased. Also, Ibatt is greater than Iset and diode D2 is forward biased. Therefore the OP Amp O2 will define the control Voltage Vc such that the requested current is been delivered to battery. In order to charge the battery 107, the microcontroller 101 can set Vset as Vmax, such that the battery 107 can charge completely. The microcontroller 101 can set Iset as Ireq such that error between Ibatt and Iset can be minimized. At the end of the CC stage, the Ibatt current will start reducing.
[0031] When the battery is charging in CC mode, the O2 (current amplifier) can sink current from the +Vcc bus resulting in a minimum value of the control voltage Vc. The control voltage Vc can be compared, using a comparator in the PWM controller 103, with a sawtooth wave. A PWM pulse with required duty cycle (d) is generated at the output of the PWM controller 103. The PWM pulse can be fed to the isolated DC-DC converter 104 of the charging system 100 through the isolated gate driver section 112, thereby delivering a constant current to the battery 107. As the battery 107 keeps on charging, the battery voltage Vbatt keeps increasing.
[0032] As Vbatt increases, the battery current Ibatt starts decreasing as the O2 (current amplifier) starts sinking a lower value of current from the +Vcc bus. Therefore, an updated control voltage Vc will be generated such that Ibatt follows Iref. When the Vbatt is equal to Vset, i.e., Vmax, then the CC-CV circuit begins to operate in the CV mode. At this stage, if Vbatt is equal to or greater than Vset (i.e., Vmax) the diode D1 is forward biased and the diode D2 is reverse biased. The OP Amp O1 will define the control voltage such that Vbatt follows Vref.
[0033] At steady state, one or more parameters of the CC-CV circuit such as R1, R2...R6, Iset, Ibatt, Vbatt and Vset can be directly related (proportional) to the amount of energy being delivered to the battery 107 by the charging system 100. The compensated values of voltage and current can be directly related (proportional) to the dynamic performance of the charging system 100. Because of the tolerance of the components in the charging system 100, if there is any difference between Iset and Ibatt, and Vbatt and Vset, the difference remains till the battery is completely discharged.
[0034] FIG. 3 is an example graph depicting variations of voltage and current at the terminals of the battery 107 while charging the battery 107, according to embodiments as disclosed herein. When the SoC of the battery 107 is low, the microcontroller 101 can set Iset as Ireq and Vset as Vmax for charging the battery. As the SoC is low, the Vbatt can be lower than Vset (set as Vmax) and Ibatt can be greater than Iset (set as Ireq). The CC-CV circuit 102 can operate in the CC mode to compensate the error between Iset and Ibatt. As depicted in FIG. 3, with the charging of the battery 107, at time t1, the current Ibatt decreases and Vbatt increases. When the battery 107 is fully charged, the Vbatt can approach Vmax, i.e., V1.
[0035] FIG. 4 depicts an example arrangement for measurement of voltage and current values at the terminals of the charger connected to the battery 107, according to embodiments as disclosed herein. The actual value of current at the terminals of the battery 107 (Ibatt) can be measured using the current measurement circuit 105. Similarly, the actual value of voltage at the terminals of the battery 107 (Vbatt) can be measured using the voltage measurement circuit 106. In order to accurately measure/read the values of Ibatt and Vbatt using the hardware units of the charging system 100 (such as the current measurement circuit 105 and voltage measurement circuit 106) it may be necessary to calibrate the individual hardware units. The calibration can be performed in stages. In an example, the non-volatile memory can be an Electrically Erasable Programmable Read-Only Memory (EEPROM) is used to store slopes (M) and offsets (C) of current and voltage measuring circuits. The EEPROM can provide slopes (Mdv, Mdi), and offsets (Cdv, Cdi) to the microcontroller 101 to calculate the actual value of voltage and current accurately. Where Mdv is slope of voltage measurement circuit and Cdv is offset of voltage measurement circuit. Similarly Mdi, Cdi are slope and offset of current measurement circuits.
[0036] As shown in FIG. 4, the microcontroller 101 can fetch the slope (Md) and offset (Cd) values from the EEPROM to accurately compute actual values of Vbatt and Ibatt. The ECU 108 can send the reference values of current (Iref) and voltage (Vref) to the microcontroller 101. In order to ensure that Vbatt follows Vref, and Ibatt follows Iref; the microcontroller 101 can convert Vref and Iref into Vset and Iset respectively. The values of Vset and Iset can be delivered to the CC-CV circuit 102 to generate the control voltage Vc. The PWM controller 103 can compare Vc with the sawtooth waveform to generate the PWM pulse. The PWM pulse can trigger the switching device (i.e., the isolated DC-DC converter 104) to deliver the required DC power to the battery such that Vbatt follows Vref and Ibatt follows Iref.
[0037] FIG. 5 depicts example voltage and current compensator circuits to compensate for the error between the predetermined reference voltage (Vref) and actual voltage (Vbatt) measured at the terminals of the battery 107, and the error between the predetermined reference current (Iref) and actual current (Ibatt) measured at the terminals of the battery 107, according to embodiments as disclosed herein. The microcontroller 101 can convert Vref and Iref into Vset and Iset respectively. The voltage and current compensator circuits can be included in the microcontroller 101. The voltage and current compensator circuits include limiters (501, 504), compensators (502, 505), and summers (503, 506). The voltage and current compensator circuits include closed feedback loops to minimize errors between inputs (Vbatt or Ibatt) and outputs (Vset or Iset). If there is a difference between Iset and Ibatt, an error signal Ei(s), representing the difference, can be computed. The error signal is passed through the compensator 502 and the limiter 501. An updated value of Iset can be computed by the compensator 502 to minimize the error signal. The new value of Iset can adjust the duty cycle of the PWM pulse fed to the isolated DC-DC converter 104 through the CC-CV circuit 102 and the PWM controller 103, which can change the actual value of current (Ibatt) being delivered to the battery 107 to ensure that the updated Ibatt follows Iref.
[0038] Similarly, if there is a difference between Vset and Vbatt, the microcontroller 101 can compute an error signal Ev(s), representing the difference between Vset and Vbatt. The error signal is passed through the compensator 505 and the limiter 504. An updated value of Vset can be computed by the compensator 505 to minimize the error signal. The new value of Vset can adjust the duty cycle of the PWM pulse fed to the isolated DC-DC converter 104 through the CC-CV circuit 102 and the PWM controller 103, which can change the actual value of voltage (Vbatt) at the terminals of the battery 107 to ensure that the updated Vbatt follows Vref.
[0039] FIG. 6 depicts an example state machine indicating the transitions between CV and CC modes of operation of the CC-CV circuit 102, according to embodiments as disclosed herein. The CC-CV circuit 102 can operate either in the CC mode or the CV mode based on the values of Vbatt, Ibatt, Vset, and Iset. The microcontroller 101 can receive the Vref, Iref, Vmax and Imax from the ECU 108 (external to the charging system 100). If Vbatt is less than the Vmax, then the state machine can operate in the CC mode to minimize the error between the Ibatt and the Iset. If Vbatt is equal to Vmax then the state machine can operate in the CV mode to minimize the error between the Vbatt and the Vset.
[0040] FIG. 7 is a flowchart 700 depicting a method for controlling the voltage and current supplied to a battery 107 in an electric vehicle at the predetermined reference voltage level/value and the predetermined reference current level/value, according to embodiments as disclosed herein. At step 701, the method includes receiving the reference current value Iref, the reference voltage value Vref, the maximum operational voltage Vmax of the battery 107 and the maximum operational current Imax from the ECU 108.
[0041] At step 702, the method includes converting Iref into the initial set current Iset and Vref to the initial set voltage Vset. The initial set current Iset and the initial set voltage Vset can ensure that Ibatt and Vbatt follow Iref and Vref respectively.
[0042] At step 703, the method includes reading the actual values of current Ibatt and voltage Vbatt at the terminals of the battery 107. The actual values of current Ibatt and voltage Vbatt can be determined using the current measurement circuit 105 and voltage measurement circuit 106 respectively. The actual values of current Ibatt and voltage Vbatt can also be measured by the microcontroller 101 and the CC-CV circuit 102.
[0043] At step 704, the method includes determining whether the state machine is operating in CC or CV mode. The mode of operation can be determined based on the initial set current Iset, the initial set voltage Vset, and the actual values of current (Ibatt) and voltage (Vbatt) measured at the terminals of the battery 107.
[0044] If the state machine is operating in the CC mode, then the embodiments can determine that Ibatt is greater than Iset and Vbatt is less than Vref. At step 705, the method includes determining the difference (error) between the initial set current Iset and the actual current value Ibatt. At step 706, the method includes compensating the error by updating the value of the initial set current Iset. The updated set current is Ireq. At step 707, the method includes updating the initial set voltage Vset. The updated set voltage is Vmax.
[0045] If the state machine is operating in the CV mode, then the embodiments can determine that Vbatt is equal to Vmax. At step 708, the method includes determining the difference (error) between the initial set voltage Vset and the actual voltage value Vbatt. At step 709, the method includes compensating the error by updating the value of the initial set voltage Vset. The updated set voltage is Vreq. At step 710, the method includes updating the initial set current Iset. The updated set current is Imax.
[0046] At step 711, the method includes feeding the updated values of set current Iset and set voltage Vset to the CC-CV circuit 102. At step 712, the method includes generating a control voltage based on the updated set current Iset, updated set voltage Vset, and the actual values of current Ibatt and voltage Vbatt at the terminals of the battery 107. At step 713, the method includes generating a PWM pulse with a duty cycle. At step 714, the method includes charging the battery using the PWM pulse, wherein the charging involves providing adequate DC power to the battery 107, based on the duty cycle of the PWM pulse such that Ibatt follows Iref and Vbatt follows Vref.
[0047] The various actions in the flowchart 700 may be performed in the order presented, in a different order, or simultaneously. Further, in some embodiments, some actions listed in FIG. 7 may be omitted.
[0048] In an embodiment herein, the microcontroller 101 can be a dedicated unit. In an embodiment herein, the microcontroller 101 can be integrated with a control unit present in the vehicle, such as the ECU 108.
[0049] Embodiments herein account for offset, gain errors present in power circuit, signal conditioning circuits by minimizing the error between the set values of voltage and current with the actual values of voltage and current respectively. Embodiments herein can ensure control over voltage and current sent to the battery 107, thereby enabling optimized charging based on battery characterization. Embodiments herein compensate errors between set voltage, current with actual voltage, current at the terminals of the battery at the micro controller 101 to deliver the set (reference) value of current and voltage from the isolated DC-DC converter 104 to the battery 107. Embodiments herein ensure that an efficient and accurate value of current and voltage are being fed to battery 107 from the charging system 100, thereby achieving full utilization of the charger capacity. Embodiments herein achieve efficient tracking of CC-CV profile set by the ECU 108. Embodiments herein can be applied to any type of DC-DC converter stage in the charging system.
[0050] The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the network elements. The network elements shown in FIG. 1 include blocks which can be at least one of a hardware device, or a combination of hardware device and software module.
[0051] The embodiment disclosed herein describes methods and systems for supplying adequate voltage and current while charging a battery of an electric vehicle. Therefore, it is understood that the scope of the protection is extended to such a program and in addition to a computer readable means having a message therein, such computer readable storage means contain program code means for implementation of one or more steps of the method, when the program runs on a server or mobile device or any suitable programmable device. The method is implemented in at least one embodiment through or together with a software program written in e.g. Very high speed integrated circuit Hardware Description Language (VHDL) another programming language, or implemented by one or more VHDL or several software modules being executed on at least one hardware device. The hardware device can be any kind of portable device that can be programmed. The device may also include means which could be e.g. hardware means like e.g. an ASIC, or a combination of hardware and software means, e.g. an ASIC and an FPGA, or at least one microprocessor and at least one memory with software modules located therein. The method embodiments described herein could be implemented partly in hardware and partly in software. Alternatively, the invention may be implemented on different hardware devices, e.g. using a plurality of CPUs.
[0052] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments and examples, those skilled in the art will recognize that the embodiments and examples disclosed herein can be practiced with modification within the spirit and scope of the embodiments as described herein.