Method for charging an intermediate circuit capacitor

• US 9,531,211 B2
• Filed: 11/17/2011
• Issued: 12/27/2016
• Est. Priority Date: 01/13/2011
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH, Samsung SDI Company Limited
• Original Assignee: Robert Bosch GmbH, Samsung SDI Company Limited
• Inventors: Schmidt, Ralph, Butzmann, Stefan, Fink, Holger
• Primary Examiner(s): Santana, Eduardo Colon
• Assistant Examiner(s): AGARED, GABRIEL T
• Application Number:
  US13/979,239
• Publication Number:
  US 20140042937A1
• Time in Patent Office: 1,867 Days
• Field of Search: 318/139
• US Class Current: 1/1
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

The disclosure relates to a method for charging an intermediate circuit capacitor in an electric drive unit comprising an electric motor. The intermediate circuit capacitor is charged by an intermediate circuit current that is supplied by a battery. The output voltage of the battery is settable to one or more voltage values. A target value of the intermediate circuit current is determined, and an actual value of the intermediate circuit current is ascertained. The actual value of the intermediate circuit current is then compared with the target value of the intermediate circuit current. An optimal output voltage of the battery is determined on the basis of the comparison of the actual value of the intermediate circuit current with the target value of the intermediate circuit current. Then, the optimal output voltage of the battery is set.

Claims

1. A method for charging an intermediate circuit capacitor of an electric drive unit including an electric motor, comprising:

charging the intermediate circuit capacitor with an intermediate circuit current provided by a battery having an output voltage configured to be adjusted to one of a plurality of voltage values, the battery including at least one battery module string with a plurality of battery modules connected in series, each battery module including at least one battery cell and a coupling unit, the at least one battery cell being connected between a first input and a second input for the coupling unit, the coupling unit being configured (i) to connect the at least one battery cell between a first terminal of the battery module and a second terminal of the battery module in response to a first control signal, and (ii) to connect the first terminal to the second terminal in response to a second control signal, as a result of which the output voltage of the battery is adjustable stepwise;

fixing a setpoint value for the intermediate circuit current;

determining an actual value for the intermediate circuit current;

comparing the actual value for the intermediate circuit current with the setpoint value for the intermediate circuit current;

determining an optimum output voltage of the battery based on the comparison of the actual value for the intermediate circuit current with the setpoint value for the intermediate circuit current; and

adjusting the optimum output voltage of the battery.

2. The method as claimed in claim 1, wherein the method is implemented using a first controller configured to determine a manipulated variable provided by the optimum output voltage of the battery from a control difference between the actual value and the setpoint value for the intermediate circuit current.

3. The method as claimed in claim 1, wherein the setpoint value for the intermediate circuit current is fixed based on a comparison of an actual value for an intermediate circuit voltage which is present at the intermediate circuit capacitor with a setpoint value for the intermediate circuit voltage.

4. The method as claimed in claim 3, wherein the method is implemented using a second controller configured to determine a manipulated variable provided by the setpoint value for the intermediate circuit current from a control difference between the actual value and the setpoint value for the intermediate circuit voltage.

5. The method as claimed in claim 1, further comprising:

charging the intermediate circuit capacitor via an inductance.

6. A control unit associated with an intermediate circuit capacitor of an electric drive unit including an electric motor comprising:

a charging device configured to charge the intermediate circuit capacitor with an intermediate circuit current provided by a battery having an output voltage configured to be adjusted to one of a plurality of voltage values, the battery including at least one battery module string with a plurality of battery modules connected in series, each battery module including at least one battery cell and a coupling unit, the at least one battery cell being connected between a first input and a second input for the coupling unit, the coupling unit being configured (i) to connect the at least one battery cell between a first terminal of the battery module and a second terminal of the battery module in response to a first control signal, and (ii) to connect the first terminal to the second terminal in response to a second control signal, as a result of which the output voltage of the battery is adjustable stepwise;

a fixing device configured to fix a setpoint value for the intermediate circuit current;

a determining device configured to determining an actual value for the intermediate circuit current;

a comparing device configured to compare the actual value for the intermediate circuit current with the setpoint value for the intermediate circuit current, wherein the determining device is further configured to determine an optimum output voltage of the battery based on the comparison of the actual value for the intermediate circuit current with the setpoint value for the intermediate circuit current; and

an adjusting device configured to adjust the optimum output voltage of the battery.

7. A battery, comprising:

a control unit configured to (i) determine an actual value for an intermediate circuit current used to charge an intermediate circuit capacitor in a drive unit including an electric motor, and (ii) to adjust an output voltage of a battery to one of a plurality of voltage values;

at least one battery module string including a plurality of battery modules connected in series, each battery module having at least one battery cell and a coupling unit, and the at least one battery cell being connected between a first input and a second input of the coupling unit, and the coupling unit being configured (i) to connect the at least one battery cell between a first terminal of the battery module and a second terminal of the battery module in response to a first control signal, and (ii) to connect the first terminal to the second terminal in response to a second control signal, as a result of which the output voltage of the battery is adjustable stepwise,

wherein the control unit is further configured to implement a method of charging the intermediate circuit capacitor,

wherein the method includes

charging the intermediate circuit capacitor with the intermediate circuit current provided by the battery,

fixing a setpoint value for the intermediate circuit current,

determining the actual value for the intermediate circuit current,

comparing the actual value for the intermediate circuit current with the setpoint value for the intermediate circuit current,

determining an optimum output voltage of the battery based on the comparison of the actual value for the intermediate circuit current with the setpoint value for the intermediate circuit current, and

adjusting the optimum output voltage of the battery.

8. The battery of as claimed in claim 7, wherein the battery is included in a drive unit having an electric motor.

9. The battery as claimed in claim 8, wherein the drive unit is included in a motor vehicle and is configured to drive the motor vehicle.