System for protecting a power semiconductor output stage that switches an inductive load
AssigneeRobert Bosch GmbH
InventorsMartin Kessler, Stefan Koch
Life of this patent
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Abstract
A system for protecting a power semiconductor output stage that, as a function of a control signal, connects an inductive load to a direct-current supply voltage and disconnects it therefrom. Protection from the induced voltages is achieved, without a freewheeling diode, in that the disconnection energy occurring at the inductive load upon disconnection can be transferred in transformer fashion to an additional inductance that is loaded with a resistance or is coupled in the countercurrent direction to the direct-current supply voltage.
Claims2
An electronically commutatable motor comprising:
- a plurality of excitation windings having a common magnetic circuit;
- a corresponding plurality of power semiconductor output stages, the output stages including low-side-connected N-channel MOSFETs,
- wherein each of the excitation windings is connected in a series circuit integrally with a respective one of the MOSFETs, the excitation windings being connected to a common direct-current supply voltage, the excitation windings being energized successively in a commutation cycle and being situated alternatingly in opposite directions into the series circuits with the MOSFETs,
- wherein, in the context of more than two excitation windings, the commutation cycle extends over an even number of successive, alternatingly oppositely polarized excitation windings, and
- wherein, in associated commutation phases, the MOSFETs are driven fully into a conductive state with uniform control signals;
- and
- a smoothing capacitor connected in parallel to the series circuits of the MOSFETs and windings between the voltage and ground for transferring back, in a countercurrent direction to the direct-current supply voltage, a disconnection energy transferred in a transformer fashion, upon disconnection of the excitation windings, to a respectively next energizable excitation winding.
An electronically commutatable motor comprising:
- a plurality of excitation windings having a common magnetic circuit;
- a corresponding plurality of power semiconductor output stages, the output stages including low-side-connected N-channel MOSFETs, each of excitation winding connected in a series circuit integrally with a respective one of the MOSFETs, the excitation windings connected to a common direct-current supply voltage, the excitation windings energizable successively in a commutation cycle and arranged alternatingly in opposite directions into the series circuits with the MOSFETs, in the context of more than two excitation windings, the commutation cycle extends over an even number of successive, alternatingly oppositely polarized excitation windings, in associated commutation phases, the MOSFETs drivable fully into a conductive state with uniform control signals;
- and
- a smoothing capacitor connected in parallel to the series circuits of the MOSFETs and windings between the voltage and ground arranged to transfer back, in a countercurrent direction to the direct-current supply voltage, a disconnection energy transferred in a transformer fashion, upon disconnection of the excitation windings, to a respectively next energizable excitation winding.
Dependencies are inferred from the claim text.