Method and device for adjusting a load current as a function of an internal resistance

• US 20150002104A1
• Filed: 06/26/2014
• Published: 01/01/2015
• Est. Priority Date: 07/01/2013
• Status: Abandoned Application

• Current Assignee: Bender GmbH & Co. KG
• Original Assignee: Bender GmbH & Co. KG
• Inventors: Moell, Winfried
• Application Number:
  US14/315,750
• Publication Number:
  US 20150002104A1
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: B60L 53/16 Connectors, e.g. plugs or sockets, specially adapted for charging electric vehicles
• CPC Class Codes: B60L 53/20 characterised by converters located in the vehicle
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: H02H 3/08 responsive to excess current responsive to abnormal temperature caused by excess current H02H5/04
• CPC Class Codes: H02H 3/20 responsive to excess voltage
• CPC Class Codes: H02H 3/44 responsive to the rate of change of electrical quantities
• CPC Class Codes: H02H 9/02 responsive to excess current current limitation for voltage regulators G05F1/573; disconnection after limiting H02H3/025
• CPC Class Codes: H02H 9/04 responsive to excess voltage lightning arrestors H01C7/12, H01C8/04, H01G9/18, H01T
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 2310/12 The local stationary network supplying a household or a building
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 3/10 Constant-current supply systems
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• 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 90/14 Plug-in electric vehicles

Abstract

The invention relates to a method and a device for adjusting a load current during operation of a load which is connected to a supply line of a power supply system via load connections. An internal resistance of the power supply system effective on the load connections is determined and used for adjusting the load current. The basic idea of the present invention is based on the determination and monitoring of the internal resistance of the supplying power grid so as to early recognize potential risks and to initiate appropriate measures. From the determined internal resistance value, a statement can be made with regard to the quality of the power supply system, such as a building installation, from the main power distribution to the supply line in the supplying cable outlet to the load connections.

Claims

1. A method for adjusting a load current (I_l) during the operation of a load (L) which is connected to a supply line (10) of a power supply system (2) via load connections (14),

characterized in that

an internal resistance (R_i) of the power supply system (2) which is effective on the load connections (14) is determined and used for adjusting the load current (I_l).

2. The method according to claim 1,

characterized in that

the internal resistance (R_i) is constantly monitored for an exceedance of a predefinable internal resistance limit during the load operation.

3. The method according to claim 1,

characterized in that

for determining the internal resistance (R_i), at least one terminal voltage (V_k) applied at the load connections (14) between an outer conductor (L1, L2, L3) and a neutral conductor (N) and the associated load current (I_l) flowing through the load connections (14) are measured.

4. The method according to claim 3,

characterized in that

the internal resistance (R_i) is determined through a load current change (Δ

I_l) while at the same time a voltage difference (Δ

V) is determined which results from the measured terminal voltage (V_k).

5. The method according to claim 4,

characterized in that

the load current change (Δ

I_l) for determining the internal resistance (R_i) occurs by way of a pulsed change of the load current (I_l) by a predefinable value.

6. The method according to claim 1,

characterized in that

the determination of the internal resistance (R_i) is triggered manually or in a time-controlled manner.

7. The method according to claim 1,

characterized in that

the determination of the internal resistance (R_i) is triggered during the load operation by an operation-related change of the load current (I_l).

8. The method according to claim 1,

characterized in that

a maximum load current (I_lmax) can be preset.

9. The method according to claim 8,

characterized in that

the maximum load current (I_lmax) is derived from a maximum permissible power dissipation (P_vmax) in the power supply system (2).

10. The method according to claim 2,

characterized in that

the load operation is shut down if the internal resistance limit is exceeded.

11. The method according to claim 2,

characterized in that

the load current (I_l) is reduced if the internal resistance limit is exceeded.

12. The method according to claim 2,

characterized in that

in combination with an electric protection device in the power supply system (2), a load circuit supplying the load (L) in the power supply system (2) is shut down if the internal resistance limit is exceeded.

13. The method according to claim 1,

characterized in that

in case an overcurrent protection device in the load circuit of the power supply system (2) supplying the load (L) is triggered, the associated load current (I_l) is recorded and used as a load current limit.

14. The method according to claim 1,

characterized in that

at least one threshold value is calculated for the internal resistance (R_i) whose exceedance triggers a warning.

15. The method according to claim 1,

characterized in that

a charging process of an electric energy storage unit (40) is performed by means of a charging current as load current (I_l).

16. The method according to claim 15,

characterized in that

in the charging process, the electric energy storage unit (40) of an electric vehicle (EV) provided with a charging device (20) is charged, the electric vehicle being connected to the supply line (10) of the power supply system (2) by a charging cable (16) via the load connections (14).

17. A device for adjusting a load current (I_l) during the operation of a load (L) which is connected to a supply line (10) of a power supply system (2) via load connections (14),

characterized by

a current measuring device (24) and a voltage measuring device (22) for determining an internal resistance (R_i) of the power supply system (2) effective on the load connections (14).

18. The device according to claim 17,

characterized by

a comparing device (26) for monitoring the internal resistance (R_i) for an exceedance of a predefinable internal resistance limit.

19. The device according to claim 17,

characterized by

an adjusting device (28) for changing the load current (I_l) to determine the internal resistance (R_i) and for reducing the load current (I_l) if the internal resistance limit is exceeded.

20. The device according to claim 17,

characterized by

a shutdown device (30) for shutting down the load operation if the internal resistance limit is exceeded.

21. The device according to claim 17,

characterized by

a calculating unit (32) for combining the measured and predefined values.

22. The device according to claim 17,

characterized by

a control unit (34) for controlling the sequence of the measuring and calculating tasks.