Estimation circuit for SOC and SOH of battery

• US 9,817,076 B2
• Filed: 11/21/2014
• Issued: 11/14/2017
• Est. Priority Date: 10/14/2014
• Status: Expired due to Fees

• Current Assignee: National Sun Yat-sen University
• Original Assignee: National Sun Yat-sen University
• Inventors: Wang, Chua-Chin, Lu, Wen-Je, Tseng, Min-Yu
• Primary Examiner(s): Rizkallah, Kimberly
• Assistant Examiner(s): Turner, Brian
• Application Number:
  US14/549,631
• Publication Number:
  US 20160103181A1
• Time in Patent Office: 1,089 Days
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health

Abstract

Estimation circuit for SOC and SOH of battery includes a control circuit, a current estimation circuit, an open-circuit voltage detection circuit, an optional multiplexer and an electrical-capacity calculation circuit. The control circuit operates under six modes based on a reset signal, a voltage signal and a current signal. The current estimation circuit comprises a current modification circuit and a Coulomb integral circuit, the current modification circuit receives the current signal and outputs a modifying current signal, the Coulomb integral circuit integrates the modifying current signal to obtain an estimating electrical-capacity value. The open-circuit voltage detection circuit receives the voltage signal and outputs an initial electrical-capacity value. The optional multiplexer receives an estimation optional signal, the estimating electrical-capacity value and the initial electrical-capacity value to output an estimating electrical-capacity signal. The electrical-capacity calculation circuit stores the estimating electrical-capacity signal to calculate battery-electrical-capacity remaining signal and state of health signal.

Claims

1. An estimation circuit for determining a State of Charge (SOC) and a State of Health (SOH) of a battery includes:

a control circuit configured for receiving a reset signal, a voltage signal and a current signal, wherein the control circuit is further configured to determine a voltage level of an electrical-capacity calculation reset signal, an estimation optional signal, an over voltage enable signal, a normal state enable signal, a low voltage enable signal and a current-estimated reset signal configured to be outputted from the control circuit according to the reset signal, the voltage signal and the current signal;

a current estimation circuit having a current modification circuit and a Coulomb integral circuit, wherein the current modification circuit is configured to receive the current signal and multiply the current signal by a modification parameter and output a modified current signal, the Coulomb integral circuit is configured to receive the modified current signal and the current-estimated reset signal of the control circuit and integrate the modified current signal to output an estimating electrical-capacity value;

an open-circuit voltage detection circuit configured for receiving the voltage signal, wherein the open-circuit voltage detection circuit is configured to output an initial electrical-capacity value according to the voltage signal;

a multiplexer configured for receiving the estimation optional signal of the control circuit, the estimating electrical-capacity value of the current estimation circuit and the initial electrical-capacity value of the open-circuit voltage detection circuit, wherein the multiplexer is configured to output an estimating electrical-capacity signal and determine the estimating electrical-capacity signal equal to the estimating electrical-capacity value or the initial electrical-capacity value according to the estimation optional signal; and

an electrical-capacity calculation circuit having an over voltage register, a normal state register and a low voltage register, wherein the over voltage register is configured to receive the estimating electrical-capacity signal, the electrical-capacity calculation reset signal and the over voltage enable signal, the normal state register is configured to receive the estimating electrical- capacity signal, the electrical-capacity calculation reset signal and the normal state enable signal, the low voltage register receives the estimating electrical- capacity signal, the electrical-capacity calculation reset signal and the low voltage enable signal, wherein the over voltage register, the normal state register and the low voltage register are configured to determine whether to store the estimating electrical-capacity signal controlled by the over voltage enable signal, the normal state enable signal and the low voltage enable signal respectively,

wherein the electrical-capacity calculation circuit is configured to determine the SOC of the battery using a signal stored in the normal state register and a signal stored in the low voltage register, and

wherein the electrical-capacity calculation circuit is configured to determine the SOH of the battery using a signal stored in the over voltage register and the signal stored in the low voltage register.

2. The estimation circuit in accordance with claim 1, wherein the current modification circuit comprises a current decoder, a comparison table, a first multiplexer and a first multiplier, the current decoder is configured to receive the current signal and decode the current signal to generate a symbol bit and a current decoding signal, the first multiplexer is configured to receive the current decoding signal and output the modifying parameter on the basis of the current decoding signal and the comparison table, the first multiplier is configured to multiply the current decoding signal with the modifying parameter to obtain the modified current signal.

3. The estimation circuit in accordance with claim 2, wherein the Coulomb integral circuit comprises a first register, a second register, a second multiplier, a first adder and a third register, wherein the first register is configured to receive the symbol bit of the current decoder and a first pulse signal, the second register is configured to receive the modified current signal and the first pulse signal and to store the modified current signal, the second multiplier is configured to receive the modified current signal stored in the second register and a sampling time and to multiply the modified current signal with the sampling time to obtain a product signal, the first adder is configured to add a former estimated electrical-capacity value to the product signal to obtain the estimating electrical-capacity value, the third register is configured to receive the estimating electrical-capacity value and the first pulse signal and to store the estimating electrical-capacity value, and the third register is configured to output the former estimated electrical-capacity value.

4. The estimation circuit in accordance with claim 3, wherein the over voltage register, the normal state register and the low voltage register are configured to receive a second pulse signal to make the over voltage register, the normal state register and the low voltage register store the estimating electrical-capacity signal via trigger of the second pulse signal.

5. The estimation circuit in accordance with claim 4 further includes a frequency divider configured to output the first pulse signal and the second pulse signal, wherein a frequency of the first pulse signal is less than that of the second pulse signal.

6. The estimation circuit in accordance with claim 1, wherein the open-circuit voltage detection circuit comprises a first operation unit, a second operation unit, a third operation unit, a comparator, a second multiplexer, a third multiplier and a second adder, wherein the first operation unit is configured to receive the voltage signal and calculate a first battery capacity state, the second operation unit is configured to receive the voltage signal and calculate a second battery capacity state, the third operation unit is configured to receive the voltage signal and calculate a third battery capacity state, the second multiplexer is configured to receive the first battery capacity state, the second battery capacity state, and the third battery capacity state, the comparator is configured to receive the voltage signal and control the second multiplexer to output the first battery capacity state, the second battery capacity state or the third battery capacity state to the third multiplier according to the voltage signal, the third multiplier is configured to multiply the received signal with a total battery capacity value and add the signal stored in the low voltage register via the second adder to obtain the initial electrical-capacity value.

7. The estimation circuit in accordance with claim 1, wherein the control circuit is configured to enter into a reset mode via the reset signal, wherein the electrical-capacity calculation reset signal and the current-estimated reset signal are high voltage level for resetting the current estimation circuit and the electrical-capacity calculation circuit.

8. The estimation circuit in accordance with claim 1, wherein the current signal received by the control circuit is smaller than a pre-determined value and the voltage signal is not able to maintain stabilization in a pre-determined time, wherein the control circuit is configured to enter an open circuit voltage (OCV) buffer mode, wherein the electrical-capacity calculation reset signal, the over voltage enable signal, the normal state enable signal and the low voltage enable signal are low voltage level for shutting down the over voltage register, the normal state register and the low voltage register.

9. The estimation circuit in accordance with claim 1, wherein the current signal received by the control circuit is smaller than a pre-determined value and the voltage signal maintains stabilization in a pre-determined time, wherein the control circuit is configured to enter an open circuit voltage (OCV) mode, wherein the estimation optional signal outputted from the control circuit is configured to enable the estimating electrical-capacity signal outputted from the multiplexer equal to the initial electrical-capacity value, and the normal state enable signal is configured to change to high voltage level for making the estimating electrical-capacity signal stored in the normal state register.

10. The estimation circuit in accordance with claim 1, wherein the voltage signal received by the control circuit is larger than a charging cut-off voltage, the control circuit is configured to enter an over voltage mode, wherein the estimation optional signal outputted from the control circuit is configured to enable the estimating electrical-capacity signal outputted from the multiplexer to be equal to the estimating electrical-capacity value, and the over voltage enable signal and the normal state enable signal is configured to change to high voltage level for making the estimating electrical-capacity signal stored in the over voltage register and the normal state register.

11. The estimation circuit in accordance with claim 1, wherein the voltage signal received by the control circuit is smaller than a discharge cut-off voltage, the control circuit is configured to enter a under voltage mode, wherein the estimation optional signal outputted from the control circuit is configured to enable the estimating electrical-capacity signal outputted from the multiplexer to be equal to the estimating electrical-capacity value, and the low voltage enable signal and the normal state enable signal is configured to change to high voltage level for making the estimating electrical-capacity signal stored in the low voltage register and the normal state register.

12. The estimation circuit in accordance with claim 1, wherein the voltage signal received by the control circuit is not less than a discharge cut-off voltage and not larger than a charge cut-off voltage, the control circuit is configured to enter a normal mode, wherein the estimation optional signal outputted from the control circuit is configured to enable the estimating electrical-capacity signal outputted from the multiplexer to be equal to the estimating electrical-capacity value, and the normal state enable signal is configured to change to high voltage level for making the estimating electrical-capacity signal stored in the normal state register.

13. The estimation circuit in accordance with claim 1, wherein the formula of the modification parameter is: