Control circuit for an electric machine, electric drive system, and method for decelerating an electric machine
The invention relates to a circuit assembly for better decelerating a rotating electric machine by means of a three-point inverter. For this purpose, an electrical resistor is supplied between a central terminal and an outer terminal of the three-point inverter. This electrical resistor allows some of the electrical energy generated during the deceleration of the electric machine to be converted into thermal energy as needed.
1 . A control circuit ( 1 ) for an electric machine ( 2 ), comprising:
an electrical resistor (R);
a three-point inverter ( 10 ) having a DC voltage terminal ( 11 ) and an AC voltage terminal ( 12 ), wherein the DC voltage terminal ( 11 ) comprises a first connection point (A 1 ), a second connection point (A 2 ), and a central terminal (M), and the electrical resistor is located between the central terminal (M) and the first connection point (A 1 );
a control device ( 15 ) configured to supply electrical energy in a recuperation mode from the AC voltage terminal ( 12 ) at least partially at the electrical resistor (R) between the central terminal (M) and the first connection point (A 1 ); and,
at least one diode (D) arranged in an electrical path between the first connection point (A 1 ) and the electrical resistor (R),
wherein the three-point inverter includes a first intermediate circuit capacitor (C 1 ) between a central terminal (M) and the first connection point (A 1 ),
wherein the at least one diode (D) is configured to maintain a minimum intermediate circuit voltage (U 1 ) of the intermediate circuit capacitor (C 1 ),
wherein the three-point inverter ( 10 ) is configured to be connected to an electric machine ( 2 ) at the AC voltage terminal ( 12 ) and to be connected to a DC voltage source ( 3 ) at the DC voltage terminal ( 11 ) between the central terminal (M) and the second connection point (A 2 ), and
wherein the control device ( 15 ) is configured to transfer electrical energy from the AC voltage terminal ( 12 ) to the electrical resistor (R) when a rotation speed of an electric machine ( 2 ) connected at the AC voltage terminal ( 12 ) is greater than a predetermined limit value.
2 . The control circuit ( 1 ) according to claim 1 , with a switching element (SW) arranged in an electrical path between the first connection point (A 1 ) and the electrical resistor (R).
3 . The control circuit ( 1 ) according to claim 1 , wherein the control device ( 15 ) is configured so as to sense at least one operating parameter of a battery connected between the central terminal (M) and the second connection point (A 2 ) of the DC voltage terminal ( 11 ), and
to adjust an electrical voltage over the electrical resistor (R) using the at least one operating parameter of the battery.
4 . The control circuit ( 1 ) according to claim 3 , wherein the at least one operating parameter comprises at least one charge state or a temperature of the battery.
5 . An electric vehicle having an electric drive system according to claim 4 .
6 . An electric drive system comprising:
a control circuit ( 1 ) according to claim 1 ; and
an electric machine ( 2 ) electrically coupled to the AC voltage terminal ( 12 ) of the control circuit ( 1 ).
7 . A method for decelerating an electric machine ( 2 ), comprising the following steps:
supplying (S 1 ) a control circuit according to claim 1 ; and
rectifying (S 2 ) an AC voltage supplied by the electric machine ( 2 ) at the AC voltage terminal ( 12 ) and supplying the rectified AC voltage at the DC voltage terminal ( 11 ) of the control circuit ( 1 ),
wherein at least some of the energy of the rectified AC voltage is supplied at the electrical resistor (R) between the central terminal (M) and the first connection point (A 1 ),
wherein at least one diode (D) is arranged in an electrical path between the first connection point (A 1 ) and the electrical resistor (R),
wherein the three-point inverter includes a first intermediate circuit capacitor (C 1 ) between a central terminal (M) and the first connection point (A 1 ), and
wherein the at least one diode (D) is configured to maintain a minimum intermediate circuit voltage (U 1 ) of the intermediate circuit capacitor (C 1 ).
8 . A control circuit ( 1 ) for an electric machine ( 2 ), comprising:
an electrical resistor (R); and
a three-point inverter ( 10 ) having a DC voltage terminal ( 11 ) and an AC voltage terminal ( 12 ), wherein the DC voltage terminal ( 11 ) comprises a first connection point (A 1 ), a second connection point (A 2 ), and a central terminal (M), wherein the electrical resistor (R) is arranged between the central terminal (M) and the first connection point (A 1 ),
a control device ( 15 ) configured to supply electrical energy in a recuperation mode from the AC voltage terminal ( 12 ) at least partially at the electrical resistor (R) between the central terminal (M) and the first connection point (A 1 ),
wherein the three-point inverter ( 10 ) is configured so as to be connected to an electric machine ( 2 ) at the AC voltage terminal ( 12 ) and to be connected to a DC voltage source ( 3 ) at the DC voltage terminal ( 11 ) between the central terminal (M) and the second connection point (A 2 ),
wherein at least one diode (D) is arranged in an electrical path between the first connection point (A 1 ) and the electrical resistor (R),
wherein the three-point inverter includes a first intermediate circuit capacitor (C 1 ) between the central terminal (M) and the first connection point (A 1 ), and a second intermediate circuit capacitor (C 2 ) between the central terminal (M) and the second connection point (A 2 ),
wherein the at least one diode (D) is configured to maintain a minimum intermediate circuit voltage (U 1 ) of the intermediate circuit capacitor (C 1 ),
wherein the control device ( 15 ) is configured to transfer electrical energy from the AC voltage terminal ( 12 ) to the electrical resistor (R) when a rotation speed of an electric machine ( 2 ) connected at the AC voltage terminal ( 12 ) is greater than a predetermined limit value.
9 . The control circuit ( 1 ) according to claim 8 , with a switching element (SW) arranged in an electrical path between the first connection point (A 1 ) and the electrical resistor (R).
10 . The control circuit ( 1 ) according to claim 8 , wherein the control device ( 15 ) is configured so as to sense at least one operating parameter of a battery connected between the central terminal (M) and the second connection point (A 2 ) of the DC voltage terminal ( 11 ), and
to adjust an electrical voltage over the electrical resistor (R) using the at least one operating parameter of the battery.
11 . The control circuit ( 1 ) according to claim 10 , wherein the at least one operating parameter comprises at least one charge state or a temperature of the battery.