초록 ▼

A method is specified for controlling a multiphase motor that is commutated by an inverter-side bridge circuit, in the course of which a particularly precise and technically simple detection of a control-relevant variable of a considered motor phase, in particular of a motor phase current and/or a b

A method is specified for controlling a multiphase motor that is commutated by an inverter-side bridge circuit, in the course of which a particularly precise and technically simple detection of a control-relevant variable of a considered motor phase, in particular of a motor phase current and/or a back EMF voltage and/or a variable derived therefrom, takes place. It is provided here to determine the control-relevant variable with the aid of the current state of a freewheeling diode that is disposed in a phase half bridge, assigned to the respective motor phase, of the bridge circuit, the current state being detected during an on time in which a power switch, connected in parallel with the freewheeling diode, of the phase half bridge exhibits a conducting state, and a power switch connected in series with the freewheeling diode exhibits a blocking state.

대표청구항 ▼

We claim: 1. A method for controlling a motor being commutated by an inverter-side bridge circuit and having a number of motor phases, which comprises the steps of: determining a control-relevant variable of a respective motor phase by detecting a current state of a freewheeling diode disposed in a

We claim: 1. A method for controlling a motor being commutated by an inverter-side bridge circuit and having a number of motor phases, which comprises the steps of: determining a control-relevant variable of a respective motor phase by detecting a current state of a freewheeling diode disposed in a phase half bridge, associated with the respective motor phase, of the inverter-side bridge circuit, during an on time in which a first power switch, connected in parallel with the freewheeling diode, of the phase half bridge exhibits a conducting state, and a second power switch connected in series with the freewheeling diode exhibits a blocking state. 2. The method according to claim 1, which further comprises determining the current state of the freewheeling diode with an aid of a reference voltage dropping across the freewheeling diode. 3. The method according to claim 1, which further comprises disposing, the freewheeling diode whose current state is being determined, on a low-potential side with reference to a phase terminal within the phase half bridge associated with the respective motor phase. 4. The method according to claim 1, which further comprises determining a flow direction of a motor phase current flowing in the respective motor phase as the control-relevant variable with an aid of the current state. 5. The method according to claim 4, which further comprises monitoring the current state of the freewheeling diode continuously to determine zero crossings of the motor phase current, a zero crossing being recognized from a change in the current state. 6. The method according to claim 1, which further comprises determining a sign of a back EMF voltage induced by the motor in the respective motor phase as the control-relevant variable with an aid of the current state, this being done by producing a zero vector state with reference to a terminal potential applied to the respective motor phase, and with reference to further terminal potentials respectively applied to one of the further motor phases. 7. The method according to claim 6, which further comprises performing the determination of the sign of the back EMF voltage upon recognition of a zero crossing of a motor phase current in the respective motor phase. 8. The method according to claim 7, which further comprises: before a production of the zero vector state, for the purpose of an off-commutation of the motor phase current in the respective motor phase, bringing an off-commutation state about in which the phase half bridge associated with the respective motor phase is connected to a high impedance; and applying a terminal potential counteracting the motor phase current in the respective motor phase to the further motor phases. 9. The method according to claim 7, which further comprises determining a phase shift between the motor phase current and the back EMF voltage as a controlled variable with an aid of a change in a flow direction of the motor phase current and of the sign of the back EMF voltage at this instant. 10. A device for driving a multiphase, electronically commutated motor, the device comprising: an inverter-side bridge circuit having phase half bridges each associated with a motor phase, said phase half bridges each containing a phase terminal, a first power switch disposed on a high-potential side with reference to said phase terminal, a second power switch disposed on a low-potential side with reference to said phase terminal, and freewheeling diodes each connected in parallel with one of said first and second power switches, said inverter-side bridge circuit further containing a sensor circuit, one of said freewheeling diodes of at least one of said phase half bridges is connected to said sensor circuit configured to determine a current state of said respective freewheeling diode for detecting a control-relevant variable of a respective motor phase during an on time in which said second power switch connected in parallel with said respective freewheeling diode exhibits a conducting state, and said first power switch connected in series with said respective freewheeling diode exhibits a blocking state; and a control unit for driving said first and second power switches of said inverter-side bridge circuit. 11. The device according to claim 10, wherein said sensor circuit is disposed on said low-potential side with reference to said respective phase terminal. 12. The device according to claim 10, wherein said sensor circuit has a comparator receiving as an input potential an anode-side diode potential and a cathode-side diode potential of said freewheeling diode. 13. The device according to claim 10, wherein said sensor circuit contains a bipolar transistor having a base-emitter junction and connected in series through said base-emitter junction to said respective freewheeling diode. 14. The device according to claim 10, further comprising a common assembly, said sensor circuit, together with said respective freewheeling diode and said second power switch connected in parallel therewith, is integrated in said common subassembly. 15. The device according to claim 14, wherein said sensor circuit has a sensor output making available an output signal characterizing the current state of said respective freewheeling diode of said common subassembly, said sensor output having properties of an open-collector output.