Patent ID: 6906484

Claim:
A method of limiting current in an electric motor which is implemented for connection to a DC power network, said motor comprising: a rotor ( 108 ); a stator having a stator winding arrangement ( 102 ); a full bridge circuit ( 137 ) for supplying current to the stator winding arrangement ( 102 ); an arrangement for sensing a current in the full bridge circuit ( 137 ) exceeding a predetermined value, one winding ( 102 ) of the stator winding arrangement comprising first and second terminals ( 104 , 106 ), and from the first terminal ( 104 ), a first semiconductor switch (HSL) of the full bridge circuit ( 137 ) leading to a first line ( 116 ) of the DC power network, and a second semiconductor switch (LSL) of the full bridge circuit ( 137 ) leading to a second line ( 122 ) of that DC power network; and from the second terminal ( 106 ), a third semiconductor switch (HSR) of the full bridge circuit ( 137 ) leading to the first line ( 116 ), and a fourth semiconductor switch (LSR) of the full bridge circuit ( 137 ) leading to the second line ( 122 ) of the DC power network; and the method comprises the steps of: a) after a current in the full bridge circuit ( 137 ) exceeding the predetermined value has been sensed, of the totality of first semiconductor switch (HSL) and third semiconductor switch (HSR), rendering the semiconductor switch conducting at that moment nonconductive, in order to interrupt the current flowing from the DC power network to the respective winding ( 102 ); b) after that semiconductor switch has opened, of the totality of second semiconductor switch (LSL) and fourth semiconductor switch (LSR), in addition to the semiconductor switch already made conductive, also rendering the semiconductor switch not conducting at that moment conductive, in order to connect the terminals ( 104 , 106 ) of the respective winding ( 102 ) to one another in low-resistance fashion via the second semiconductor switch (LSL) and fourth semiconductor switch (LSR), so that the current in the respective winding ( 102 ) can continue to flow through the second semiconductor switch (LSL) and the fourth semiconductor switch (LSR) and can decay; c) when that current has reached a lower value, once again switching on current delivery from the DC power network to the respective winding ( 102 ).