Patent ID: 6940243
Filing Date: 2005-09-06
Classification: H02P

Abstract:
1. A method of commutating an electronically commutated motor which is configured for connection to a DC power network and comprises: a permanent-magnet rotor ( a full bridge circuit ( a stator that comprises a drive winding ( from a second winding terminal ( a sensor for sensing a variable (t_HALL) characterizing angular velocity of the rotor ( a calculating means for calculating a future time for switching off motor current at the beginning of a commutation procedure; a controlling means for selectively rendering said semiconductor switches conductive or non-conductive; and a current sensing means; the method comprising the steps of: a) automatically sensing said variable (t_HALL) characterizing the angular velocity of the rotor ( b) based on that variable (t_HALL), automatically calculating said future time for switching off the current at the beginning of a commutation procedure; c) after that time is reached, of the set consisting of first semiconductor switch (HSL) and third semiconductor switch (HSR), automatically rendering the semiconductor switch conductive at the moment nonconductive, in order to interrupt the current flowing from the DC power network in the first direction to the drive winding ( d) after that semiconductor switch has been made nonconductive, of the set consisting of second semiconductor switch (LSL) and fourth semiconductor switch (LSR), in addition to the semiconductor switch conductive at the moment, automatically changing the semiconductor switch not conductive at the moment into a conductive state, in order to connect the winding terminals of the drive winding to one another in low-resistance fashion via the second semiconductor switch (LSL) and fourth semiconductor switch (LSR), so that the current can continue to flow through the drive winding ( e) when that current has reached a reduced value, automatically switching the winding terminals of the drive winding into a high-resistance state so that substantially no further current can flow between them; f) at a time subsequent to the end of step e), automatically switching the delivery of current from the DC power network to the drive winding, by controlling the full bridge circuit (