Method for operating a charging device for single-phase and multi-phase charging of an energy store in a motor vehicle and charging device

Abstract

A method for operating a charging device of an electrical energy store for a motor vehicle, wherein a dedicated rectifier device for generating a charging voltage for the electrical energy store is associated with each phase of an AC power supply, includes determining for each rectifier device a usage variable descriptive of its prior usage for charging the electrical energy store; when performing a multi-phase charging operation with the charging device, using for each phase a corresponding rectifier device for generating the charging voltage for the electrical energy store; and when performing a single-phase charging operation with the charging device, using the hitherto most underused rectifier device for generating the charging voltage for the electrical energy store based on the usage variable.

Claims

1. A method for operating a charging device of an electrical energy store for a motor vehicle, wherein a dedicated rectifier device for generating a charging voltage for the electrical energy store is associated with each phase of an AC power supply, the method comprising: determining for each rectifier device a usage variable descriptive of its prior usage for charging the electrical energy store, when performing a multi-phase charging operation with the charging device, using for each phase a corresponding rectifier device for generating the charging voltage for the electrical energy store, when performing a single-phase charging operation with the charging device, using the hitherto most underused rectifier device for generating the charging voltage for the electrical energy store based on the usage variable, and determining a utilization factor indicative of an operating time of the rectifier device or prior work hitherto performed by each rectifier device, wherein in a charging device designed for a three-phase charging, two most underused rectifier devices based on the utilization factor are used for a charging process during a two-phase charging.

2. The method of claim 1, comprising: connecting a first rectifier device connected for single-phase charging to a first connecting cable and a switching device for selectively connecting to the first connecting cable at least one second rectifier device that is different from the first rectifier device, closing at a start of each charging process a switch of the switching device to thereby connect a least-used second rectifier device to the first connecting cable, and deactivating the first rectifier device.

3. The method of claim 2, wherein the switch comprises a relay or a semiconductor switch.

4. The method of claim 1, and further measuring a voltage at all connecting cables that connect the respective rectifiers to the AC power supply, in order to distinguish between single-phase charging and multi-phase charging.

5. A charging device for an energy store of a motor vehicle, comprising a respective rectifier device connected via a respective connecting cable with each phase of an AC power supply in one-to-one correspondence for generating a charging voltage for the energy store, wherein a first connecting cable connected to a first rectifier device is used in single-phase charging of the energy store, a respective counting device determining for each rectifier device a utilization factor indicating prior usage of the respective rectifier device, and a control device configured to use in a single-phase charging process the most underused rectifier device that has in accordance with contents of the counting devices the hitherto lowest utilization factor, wherein in a charging device designed for a three-phase charging, two most underused rectifier devices based on a utilization factor are used for a charging process during a two-phase charging.

6. The charging device of claim 5, further comprising a switching device controllable by the control device and configured to selectively connect to the first connecting cable a second rectifier device different from the first rectifier device.

7. The charging device of claim 6, wherein at least one switch of the switching device is constructed as a relay or a semiconductor switch.

8. The charging device of claim 5, further comprising a voltage measuring device associated with each connecting cable for transmitting measurement data to the control device.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawings, which show in:

(2) FIG. 1 a charging device according to the invention, and

(3) FIG. 2 a schematic diagram of a motor vehicle.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(4) FIG. 1 shows a schematic functional circuit diagram of a charging device 1 according to the invention. It will be understood that the illustrated components may be disposed in a common housing; however, the modules for the various phases may also be implemented as individual units.

(5) The present charging device 1 is designed for three-phase charging, i.e. means it has three connecting cables 2, 3, 4 for the different phases and a grounded neutral conductor 5. The charging device 1 supplies as output at the terminals 6 a high-voltage DC voltage as a charging voltage for an unillustrated electric energy store of a motor vehicle. To generate the charging voltage from the corresponding AC input voltages, a rectifier device 7, 8, 9 is provided for each phase, which may also comprise, in addition to a rectifier with at least one rectifier stage, other components, for example filters and the like. When the charging device 1 is connected to electric power, i.e. in particular to a power grid, which provides only a single-phase AC voltage, the charging device 1 can still be used for charging the energy store, as will be set forth in more detail below.

(6) When connected to only one phase, the voltage is applied to the first connecting cable 2, which, as shown, is connected directly to the first rectifier device 7. However, a switching device is provided which includes the switches S1 and S2. The respective second rectifier devices 8, 9 can be selectively connected with their associated second connecting cables 3, 4 or with the first connecting cable 2 via the switches S1, S2. In this way, the first connecting cable 2 can also be connected with the second rectifier devices 8, 9 that are not the first rectifier device 7.

(7) In order to detect whether single-phase load or multi-phase, here three-phase, charging is to be performed, voltage measuring devices V1, V2 and V3 are provided that measure the voltages at the respective connecting cables 2, 3, 4. When a voltage is present at the first connecting cable 2, single-phase charging is performed; when a voltage is present at all three connecting cables 2, 3, 4, a three-phase charging is performed. The operation of the charging device 1 is controlled by a control device 10, which is capable of controlling in addition to the rectifier devices 7, 8, 9 also the switches S1 and S2 and also receives data from the voltage measuring devices V1, V2 and V3. The control device 10 is designed to carry out the method according to the invention, for which purpose it also has three associated counting devices 11, 12 and 13. The counting device 11 measures the usage of the first rectifier device 7, the counting device 12 measures the usage of the second rectifier device 8, and the counting device 13 measures the usage of the second rectifier device 9. The counting devices 11, 12, 13 are configured to measure the electric work of the rectifier device 7, 8, 9 (watt-hour meter) or the operating time (operating hours counter).

(8) When the control device 10 determines based on the measurement results of the voltage measuring devices V1, V2 and V3 that single-phase charging is imminent, the utilization factors describing usage of the rectifier devices 7, 8, 9 are recalled in the counting devices 11, 12, 13 and evaluated as to which rectifier device 7, 8, 9 has thus far been used the least, i.e. in particular, which utilization factor is the lowest. If this is the first rectifier device 7, then the switches S1 and S2 is not operated and the rectifier device 7 is activated and used. It this is one of the second rectifier devices 8, 9, then the first rectifier device 7 is deactivated, the corresponding switches S1, S2 are closed, and the respective second rectifier device 8, 9 is activated and used. In this way, usage with the single-phase charging is evenly distributed among the various rectifier devices 7, 8, 9.

(9) The switches S1, S2 are in this case designed as relays, but may also be implemented as semiconductor switches. In principle, more functions, for example, a rectifier stage or a power factor correction filter may be integrated in such switches.

(10) It should also be noted that the concept presented here can of course also be used in two-phase charging with a charging device 1 designed for three-phase charging, wherein the switching device is to be adapted accordingly, as is readily apparent to those skilled in the art.

(11) FIG. 2 illustrates schematically a case where the charging device 1 is integrated in a motor vehicle 14, so that the charging device 1 is connected to one side with a high-voltage terminal 15 of the motor vehicle 14, and to the other side with an electrical energy store 16 of the motor vehicle 14, here a high-voltage battery, which is to be loaded by way of the charging device 1. Other embodiments are also conceivable where the charging device 1 is only partially integrated into the motor vehicle 14 or is even realized as an external device, for example as a charging station or the like.