Working machine

• US 9,550,431 B2
• Filed: 06/19/2014
• Issued: 01/24/2017
• Est. Priority Date: 07/30/2013
• Status: Expired due to Fees

• Current Assignee: Sumitomo Heavy Industries Limited
• Original Assignee: Sumitomo Heavy Industries Limited
• Inventors: Yumura, Masanori
• Primary Examiner(s): GARBOWSKI, LEIGH M
• Application Number:
  US14/309,052
• Publication Number:
  US 20150039151A1
• Time in Patent Office: 950 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 2200/42 Fork lift trucks
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An electric motor drives a drive target and generates electricity. A charge-discharge control circuit controls charging and discharging of a power storage device. A controller controls a charge-discharge control circuit. The controller obtains a calculation value of an internal resistance of the power storage device based on a measured value of an open circuit voltage of the power storage device, and a measured value of an inter-terminal voltage and a measured value of a charge-discharge current when the power storage device is charged and discharged, and obtains a correction value of the internal resistance by correcting the calculation value of the internal resistance based on the measured value of the open circuit voltage.

Claims

1. A working machine comprising:

an electric motor configured to drive a drive target and generate electricity;

a power storage device;

a charge-discharge control circuit which is configured to control charging and discharging of the power storage device and is connected to the electric motor; and

a controller configured to control the charge-discharge control circuit,

wherein the controller obtains a calculation value of an internal resistance of the power storage device based on a measured value of an open circuit voltage of the power storage device, and a measured value of an inter-terminal voltage and a measured value of a charge-discharge current when the power storage device is charged and discharged, and obtains a correction value of the internal resistance by correcting the calculation value of the internal resistance based on the measured value of the open circuit voltage.

2. The working machine according to claim 1, further comprising:

an inverter configured to drive the electric motor; and

a DC bus line which is connected to the charge-discharge control circuit and the inverter.

3. The working machine according to claim 1,

wherein the controller performs a control using the correction value of the internal resistance.

4. The working machine according to claim 1,

wherein the controller stores correction information to obtain the correction value of the internal resistance from the measured value of the open circuit voltage and the calculation value of the internal resistance, and obtains the correction value of the internal resistance based on the calculation value of the internal resistance, the measured value of the open circuit voltage, and the correction information.

5. The working machine according to claim 4,

wherein correction information at the time of charging and correction information at the time of discharging are stored as the correction information, the correction information at the time of charging is used in a case where the power storage device is charged when the calculation value of the internal resistance is obtained, and the correction information at the time of discharging is used when the power storage device is discharged.

6. A working machine comprising:

an electric motor configured to drive a drive target and generate electricity;

a power storage device configured to supply electric power to the electric motor;

a charge-discharge control circuit which is configured to control charging and discharging of the power storage device and is connected to the electric motor; and

a controller configured to control the charge-discharge control circuit,

wherein the controller stores a value of an internal resistance at the time of a reference voltage of the power storage device,

wherein the controller obtains a charging state of the power storage device based on a measured value of an inter-terminal voltage and a measured value of a charge-discharge current when the power storage device is charged and discharged, and the value of the internal resistance at the time of the reference voltage, and

wherein the controller obtains a correction value which is obtained by correcting the value of the internal resistance at the time of the reference voltage based on a calculation value of the last open circuit voltage of the power storage device, obtains the calculation value of the open circuit voltage at the present time based on the correction value, and obtains the charging state of the power storage device based on the calculation value of the open circuit voltage at the present time.

7. The working machine according to claim 6,

wherein the controller controls the electric motor and the charge-discharge control circuit based on the obtained charging state of the power storage device.