Lithium Ion Battery Simplified SPICE Behavioral Model. All Rights Reserved Copyright (C) Bee Technologies Corporation

Transcription

1 Lithium Ion Battery Simplified SPICE Behavioral Model All Rights Reserved Copyright (C) Bee Technologies Corporation 211 1

2 Contents 1. Benefit of the Model 2. Model Feature 3. Concept of the Model 4. Parameter Settings 5. Li-Ion Battery Specification (Example) 5.1 Charge Time Characteristic 5.2 Discharge Time Characteristic 5.3 V bat vs. SOC Characteristic 6. Extend the number of Cell (Example) 6.1 Charge Time Characteristic, NS=4 6.2 Discharge Time Characteristic, NS=4 Simulation Index All Rights Reserved Copyright (C) Bee Technologies Corporation 211 2

3 1. Benefit of the Model The model enables circuit designer to predict and optimize battery runtime and circuit performance. The model can be easily adjusted to your own battery specifications by editing a few parameters that are provided in the datasheet. The model is optimized to reduce the convergence error and the simulation time All Rights Reserved Copyright (C) Bee Technologies Corporation 211 3

4 2. Model Feature This Li-Ion Battery Simplified SPICE Behavioral Model is for users who require the model of a Li-Ion Battery as a part of their system. Battery Voltage(V bat ) vs. Battery Capacity Level (SOC) Characteristic, that can perform battery charge and discharge time at various current rate conditions, are accounted by the model. As a simplified model, the effects of cycle number and temperature are neglected. All Rights Reserved Copyright (C) Bee Technologies Corporation 211 4

5 3. Concept of the Model Li-Ion battery Simplified SPICE Behavioral Model [Spec: C, NS] + Output Characteristics Adjustable SOC [ -1(1%) ] - The model is characterized by parameters: C, which represent the battery capacity and SOC, which represent the battery initial capacity level. Open-circuit voltage (V OC ) vs. SOC is included in the model as an analog behavioral model (ABM). NS (Number of Cells in series) is used when the Li-ion cells are in series to increase battery voltage level. All Rights Reserved Copyright (C) Bee Technologies Corporation 211 5

6 4. Parameter Settings Model Parameters: C is the amp-hour battery capacity [Ah] e.g. C =.3, 1.4, or 2.8 [Ah] (Default values) TSCALE = 1 C = 1.4 SOC = 1 NS = 1 NS is the number of cells in series e.g. NS=1 for 1 cell battery, NS=2 for 2 cells battery (battery voltage is double from 1 cell) SOC is the initial state of charge in percent e.g. SOC= for a empty battery (%), SOC=1 for a full charged battery (1%) TSCALE turns TSCALE seconds into a second e.g. TSCALE=6 turns 6s or 1min into a second, TSCALE=36 turns 36s or 1h into a second, From the Li-Ion Battery specification, the model is characterized by setting parameters C, NS, SOC and TSCALE. All Rights Reserved Copyright (C) Bee Technologies Corporation 211 6

7 5. Li-Ion Battery Specification (Example) TSCALE = 6 SOC = 1 C = 1.4 NS = 1 Battery capacity is input as a model parameter Nominal Voltage 3.7V Nominal Capacity Charging Voltage Charging Std. Current Max Current Typical Charge Discharge 14mAh (.2C discharge) 4.2V±.5V 7mA 14mA 28mA Discharge cut-off voltage 2.75V The battery information refer to a battery part number LIR185 of EEMB BATTERY. All Rights Reserved Copyright (C) Bee Technologies Corporation 211 7

8 5.1 Charge Time Characteristic Measurement 1.V.8V.6V Simulation Capacity=1%.4V.2V 1 4.4V 4.2V 2 V 1.4A 1.2A V(X_.SOC) TSCALE = 6 C = 1.4 SOC = NS = 1 SOC= means battery start from % of capacity (empty) 4.V 3.8V 3.6V 3.4V 3.2V 3.V 1.A.8A.6A.4A Voltage=4.2V Current=7mA SEL>> A s 5s 1s 15s 2s 1 V(HI) 2 I(IBATT) (minute) Time Charging Voltage: 4.2V±.5V Charging Current: 7mA (.5 Charge) All Rights Reserved Copyright (C) Bee Technologies Corporation 211 8

9 IN+ IN- OUT+ OUT- 5.1 Charge Time Characteristic Simulation Circuit and Setting Input Voltage PARAMETERS: N = 1 CAh = 1.4 rate =.5 Vin 5V C1 1n HI IBATT D1 DMOD Over-Voltage Protector: (Charging Voltage*1) - VF of D1 Voch {(4.2*N)-8.2m} G1 Limit(V(%IN+, %IN-)/.1m,, rate*cah ) TSCALE = 6 C = 1.4 SOC = NS = {N} 1 minute in seconds *Analysis directives:.tran 2.5.PROBE V(*) I(*) W(*) D(*) NOISE(*) All Rights Reserved Copyright (C) Bee Technologies Corporation 211 9

10 5.2 Discharge Time Characteristic Battery voltage vs. time are simulated at.2c,.5c, and 1C discharge rates. PARAMETERS: rate = 1 CAh = V sense 4.2V HI IN+ IN- OUT+ OUT- G1 limit(v(%in+, %IN-)/.1m,, rate*cah ) C1 1n TSCALE = 6 C = 1.4 SOC = 1 NS = 1 TSCALE turns 1 minute in seconds, battery starts from 1% of capacity (fully charged) 4.V 3.8V 3.6V 3.4V 3.2V 3.V 1C.2C.5C 2.8V *Analysis directives:.tran 3.5.STEP PARAM rate LIST.2,.5,1.PROBE V(*) I(*) W(*) D(*) NOISE(*) 2.6V s 1s 2s 3s 4s V(HI) (minute) Time All Rights Reserved Copyright (C) Bee Technologies Corporation 211 1

11 Discharge Capacity (%vs..2c) Voltage (V) 5.3 V bat vs. SOC Characteristic Measurement Simulation.8.2C 1C.6.4 Capacity (%).2.5C -.2 TSCALE = 6 C = 1.4 SOC = 1 NS = 1 Nominal Voltage: 3.7V Capacity: 14mAh (.2C discharge) Discharge cut-off voltage: 2.75V Simulation Mesurement Simulation Battery Discharge Current (vs. C Rate) All Rights Reserved Copyright (C) Bee Technologies Corporation

12 5.3 V bat vs. SOC Characteristic Simulation Circuit and Setting PARAMETERS: rate =.2 CAh = 1.4 sense HI IN+ IN- OUT+ OUT- G1 limit(v(%in+, %IN-)/.1m,, rate*cah ) C1 1n TSCALE = 6 C = 1.4 SOC = 1 NS = 1 1 minute in seconds *Analysis directives:.tran PROBE V(*) I(*) W(*) D(*) NOISE(*) All Rights Reserved Copyright (C) Bee Technologies Corporation

13 6. Extend the number of Cell (Example) TSCALE = 6 SOC = 1 C = 4.4 NS = 4 Basic Specification Output Voltage Capacity of Approximately DC 12.8~16.4V 44mAh Li-ion needs 4 cells to reach this voltage level The number of cells in series is input as a model parameter Input Voltage DC 2.5V Charging Time About 5 hours The battery information refer to a battery part number PBT-BAT-1 of BAYSUN Co., Ltd. All Rights Reserved Copyright (C) Bee Technologies Corporation

14 6.1 Charge Time Characteristic, NS=4 1.V.8V Capacity=1% The battery needs 5 hours to be fully charged.6v.4v.2v 1 18V SEL>> V 2.4A 2 V(X_.SOC) 17V 2.A 16V 15V 1.6A 1.2A Voltage=16.8V 14V 13V 12V.8A Current=88mA >> A s 1s 2s 3s 4s 5s 6s 7s 8s 9s 1s 1 V(HI) 2 I(IBATT) (hour) Time Input Voltage: 2.5V Charging Voltage: 16.8V Charging Current: 88mA (.2 Charge) All Rights Reserved Copyright (C) Bee Technologies Corporation

15 IN+ IN- OUT+ OUT- 6.1 Charge Time Characteristic, NS=4 Simulation Circuit and Setting Input Voltage PARAMETERS: N = 4 CAh = 4.4 rate =.2 Vin 2.5V C1 1n HI IBATT D1 DMOD Over-Voltage Protector: (Charging Voltage*4) - VF of D1 Voch {(4.2*N)-8.2m} G1 Limit(V(%IN+, %IN-)/.1m,, rate*cah ) TSCALE = 36 C = 4.4 SOC = NS = {N} 1 Hour in seconds *Analysis directives:.tran 1.5.PROBE V(*) I(*) W(*) D(*) NOISE(*) All Rights Reserved Copyright (C) Bee Technologies Corporation

16 6.2 Discharge Time Characteristic, NS=4 18V 16.4V 17V 16V Output voltage range 15V 14V.5C 12.8V 13V 12V 1C 11V 1V s.4s.8s 1.2s 1.6s 2.s V(HI) Time (hour) Charging Voltage: 16.8V Charging Current: 88mA (.2 Charge) All Rights Reserved Copyright (C) Bee Technologies Corporation

17 6.2 Discharge Time Characteristic, NS=4 Simulation Circuit and Setting Parametric sweep rate PARAMETERS: rate = 1 CAh = 4.4 sense HI IN+ IN- OUT+ OUT- G1 limit(v(%in+, %IN-)/.1m,, rate*cah ) C1 1n TSCALE = 36 C = 4.4 SOC = 1 NS = 4 1 Hour in seconds *Analysis directives:.tran 3.5.STEP PARAM rate LIST.5,1.PROBE V(*) I(*) W(*) D(*) NOISE(*) All Rights Reserved Copyright (C) Bee Technologies Corporation

18 Simulation Index Simulations 1. Charge Time Characteristic Discharge Time Characteristic V bat vs. SOC Characteristic Charge Time Characteristic, NS= Discharge Time Characteristic, NS=4... Folder name Charge_Time Discharge_Time Discharge_SOC Charge_Time(NS) Discharge_Time(NS) All Rights Reserved Copyright (C) Bee Technologies Corporation