ELECTRIC CONSTRUCTION MACHINE

• US 20140117934A1
• Filed: 08/07/2012
• Published: 05/01/2014
• Est. Priority Date: 08/08/2011
• Status: Abandoned Application

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Kurikuma, Hajime, Takishita, Tatsuo, Yunoue, Masayuki
• Application Number:
  US14/127,025
• Publication Number:
  US 20140117934A1
• Time in Patent Office: Days
• US Class Current: 320/109
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 2210/12 Buck converters
• CPC Class Codes: B60L 2210/30 AC to DC converters
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 2250/10 by alarm
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/04 Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: E02F 9/207 of the type electric propulsion units, e.g. electric motors or generators
• CPC Class Codes: E02F 9/2075 : of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: H01M 10/441 : for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2010/4278 : Systems for data transfer from batteries, e.g. transfer of battery parameters to a controller, data transferred between battery controller and main controller
• CPC Class Codes: H02J 5/00 : Circuit arrangements for transfer of electric power between ac networks and dc networks H02J3/36 takes precedence
• CPC Class Codes: H02J 7/0047 : with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/0048 : Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/007182 : in response to battery voltage
• CPC Class Codes: H02J 7/04 : Regulation of charging current or voltage
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/12 : Electric charging stations
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles

Abstract

An electric construction machine is capable of increasing a battery device charging rate in a short charging time. The battery device includes a plurality of battery systems and an inverter device which has a motor driving control function of selectively connecting one of the battery systems, converting DC power supplied from the connected battery system into AC power, and supplying the AC power to an electric motor. The inverter has a battery charging control function of selectively connecting one of the battery systems and supplying electric power from an external commercial power supply to the connected battery system. When the voltages of the battery systems are less than an upper limit value V₁ at the start of the charging, constant-current charging of one battery system is started. Before the one battery system reaches the fully charged state, the connection is switched to another battery system to start constant-current charging thereof.

Claims

1. An electric construction machine comprising:

an electric motor (31);

a hydraulic pump (33) driven by the electric motor (31);

a plurality of hydraulic actuators (13A, 19) driven by hydraulic fluid delivered from the hydraulic pump (33);

a battery device (7) including a plurality of battery systems (56A, 56B) each having a plurality of batteries (55) connected in series;

connection switching means (32, 58A, 58B) for selectively connecting one of the battery systems (56A, 56B); and

an inverter (51) for converting DC power supplied from the battery system selectively connected by the connection switching means (32, 58A, 58B) into AC power and supplying the AC power to the electric motor (31), wherein;

the electric construction machine comprises charging control means (32) which supplies electric power from an external power supply (48) to the battery system selectively connected by the connection switching means (32, 58A, 58B), performs constant-current charging when the voltage of the battery system is less than a preset upper limit value, and performs constant-voltage charging when the voltage of the battery system has reached the upper limit value, and

when the voltages of one battery system and another battery system included in the plurality of battery systems (56A, 56B) are less than the upper limit value, the charging control means (32) makes the connection switching means (32, 58A, 58B) selectively connect the former battery system, starts the constant-current charging of the former battery system, thereafter makes the connection switching means (32, 58A, 58B) switch the connection to the latter battery system before the former battery system reaches a fully charged state, and then starts the constant-current charging of the latter battery system.

2. The electric construction machine according to claim 1, wherein when the voltages of one battery system and another battery system included in the plurality of battery systems (56A, 56B) are less than the upper limit value, the charging control means (32) makes the connection switching means (32, 58A, 58B) selectively connect the former battery system, charges the former battery system by the constant-current charging, makes the connection switching means (32, 58A, 58B) switch the connection to the latter battery system immediately after the voltage of the former battery system reaches the upper limit value, and then starts the constant-current charging of the latter battery system.

3. The electric construction machine according to claim 2, wherein when the voltages of one battery system and another battery system included in the plurality of battery systems (56A, 56B) are less than the upper limit value, the charging control means (32) makes the connection switching means (32, 58A, 58B) selectively connect the former battery system, charges the former battery system by the constant-current charging, makes the connection switching means (32, 58A, 58B) switch the connection to the latter battery system immediately after the voltage of the former battery system reaches the upper limit value, charges the latter battery system by the constant-current charging, and charges the latter battery system by the constant-voltage charging when the voltage of the latter battery system has reached the upper limit value.

4. The electric construction machine according to claim 2, wherein the charging control means (32) makes the connection switching means (32, 58A, 58B) selectively connect one of the former and latter battery systems, charges the connected battery system by the constant-voltage charging, thereafter makes the connection switching means (32, 58A, 58B) switch the connection to the other one of the former and latter battery systems before the connected battery system reaches the fully charged state, and charges the other one of the former and latter battery systems by the constant-voltage charging.

5. The electric construction machine according to claim 3, wherein the charging control means (32) makes the connection switching means (32, 58A, 58B) selectively connect one of the former and latter battery systems, charges the connected battery system by the constant-voltage charging, thereafter makes the connection switching means (32, 58A, 58B) switch the connection to the other one of the former and latter battery systems before the connected battery system reaches the fully charged state, and charges the other one of the former and latter battery systems by the constant-voltage charging.