Drive circuit for n contactors and a method for driving n contactors

1. A drive circuit for n contactors, n being a natural number, the drive circuit comprising:

a first input and a second input, the first input being configured to connect to a first terminal of an energy store and the second input being configured to connect to a second terminal of the energy store;

n first connections and n second connections, each first connection of the n first connections being configured to connect to a first terminal of a drive coil of one of the n contactors and each second connection of the n second connections being configured to connect to a second terminal of the drive coil of the one of the n contactors;

n first switches having a first terminal and a second terminal, the first terminal of each first switch of the n first switches being connected to the first input and the second terminals of i-th first switches of the n first switches being connected to i-th first connections of the n first connections, i being all natural numbers greater than zero and less than or equal to n;

n second switches having a first terminal and a second terminal, the first terminal of each second switch of the n second switches being connected to the second input and the second terminals of i-th second switches of the n second switches being connected to i-th second connections of the n second connections, i-th second connections of the n second connections being connected to (i+1)-th first connections of the n first connections; and

an adjustable holding voltage source having a first terminal connected to the second input and a second terminal connected to a first of the n first connections.

2. The drive circuit as claimed in claim 1 , further comprising:

a measurement and actuation unit connected to the adjustable holding voltage source and which is configured to (i) measure a first current flowing between the first terminal of the adjustable holding voltage source and the second input, and (ii) adjust a holding voltage of the adjustable holding voltage source based on a comparison of the first current with a predetermined setpoint current.

3. The drive circuit as claimed in claim 1 , further comprising:

n first diodes having an anode and a cathode, the anodes of i-th first diodes of the n first diodes being connected to the second terminals of i-th second switches of the n second switches and the cathodes of i-th first diodes of the n first diodes being connected to the second terminals of (i+1)-th first switches of the n first switches.

4. The drive circuit as claimed in claim 1 , further comprising:

n−1 second diodes, i-th second freewheeling diodes of the n−1 second diodes being connected in parallel with i-th second switches of the n switches for values of i less than n.

5. The drive circuit as claimed in claim 4 , wherein:

the n−1 second diodes are zener diodes; and

the drive circuit further comprises a further zener diode connected in parallel with an n-th second switch of the n second switches, an anode of the further zener diode being connected to the second input.

6. The drive circuit claimed in claim 1 , further comprising:

a third diode having an anode and a cathode, the anode of the third diode being connected to an n-th second connection of the n second connections and the cathode of the third diode being connected to the first input.

7. The drive circuit as claimed in claim 3 , further comprising:

n fourth diodes having an anode and a cathode, the cathode of each fourth diode of the n fourth diodes being connected to the first input and the anodes of i-th fourth diodes of the n fourth diodes being connected to the cathodes of i-th second diodes of the n−1 second diodes and to i-th second connections of the n second connections.

8. A method for driving n contactors comprising:

connecting a drive coil of a first contactor of the n contactors in parallel with an energy store using a first group two switches;

connecting the drive coil of the first contactor of the n contactors in series with an adjustable holding voltage source;

interrupting a parallel circuit comprising the drive coil of the first contactor of the n contactors and the energy store using the first group two switches in response to a predetermined duration elapsing; and

for each further contactor of the n contactors, in numerical order from a second contactor of the n contactors to an n-th contactor of the n contactors:

connecting a drive coil of the further contactor of the n contactors in parallel with the energy store using a further group of two switches;

connecting the drive coil of the further contactor of the n contactors in series with the adjustable holding voltage source and with the drive coil of the first of the n contactors;

interrupting a parallel circuit comprising the drive coil of the further contactor of the n contactors and the energy store using the further group two switches in response to a further predetermined duration elapsing; and

increasing a holding voltage of the adjustable holding voltage source.

9. The method for driving n contactors as claimed in claim 8 , wherein:

the predetermined duration is equal to the inductance of the drive coil of the first contactor of the n contactors divided by the equivalent resistance of the drive coil of the first contactor of the n contactors; and

for each of the further contactors of the n contactors, the further predetermined duration is equal to the inductance of the drive coil of the further contactor of the n contactors divided by the equivalent resistance of the drive coil of the further contactor of the n contactors.

10. The method for driving n contactors as claimed in claim 8 , the increasing further comprising:

increasing the holding voltage such that a current flowing through a series circuit comprising the adjustable holding voltage source and the further drive coil is equal to a predetermined setpoint current.

11. The method for driving n contactors as claimed in claim 8 , further comprising:

for each further contactor of the n contactors, in reverse numerical order from an n-th contactor of the n contactors to the second contactor of the n contactors:

decoupling a drive coil of the further contactor of the n contactors the adjustable holding voltage source by opening a switch of the further group of two switches; and

reducing the holding voltage of the adjustable holding voltage source; and

decoupling the first drive coil of the first contactor of the n contactors from the adjustable holding voltage source.

12. A battery comprising:

a drive circuit for n contactors, n being a natural number, the drive circuit comprising:

a first input and a second input, the first input being configured to connect to a first terminal of an energy store and the second input being configured to connect to a second terminal of the energy store;

n first connections and n second connections, each first connection of the n first connections being configured to connect to a first terminal of a drive coil of one of the n contactors and each second connection of the n second connections being configured to connect to a second terminal of the drive coil of the one of the n contactors;

n first switches having a first terminal and a second terminal, the first terminal of each first switch of the n first switches being connected to the first input and the second terminals of i-th first switches of the n first switches being connected to i-th first connections of the n first connections, i being all natural numbers greater than zero and less than or equal to n;

n second switches having a first terminal and a second terminal, the first terminal of each second switch of the n second switches being connected to the second input and the second terminals of i-th second switches of the n second switches being connected to i-th second connections of the n second connections, i-th second connections of the n second connections being connected to (i+1)-th first connections of the n first connections; and

an adjustable holding voltage source having a first terminal connected to the second input and a second terminal connected to a first of the n first connections.