Abstract: A control circuit for a multi-phase motor (57) comprises a plurality of inverter bridges, a plurality of outputs, and at least one isolation switch (62, 63). Each inverter bridge is arranged to provide an output voltage for a phase of the motor (57). Each output is arranged to be coupled to one phase of the motor (57) to provide the output voltage to that phase of the motor (57). Each isolation switch (62, 63) is coupled between one of the inverter bridges and one of the outputs, so as to selectively isolate the output from the inverter bridge. Each isolation switch (62, 63) comprises a Gallium Nitride (GaN) transistor.

Abstract: A method of controlling an electric power assisted steering (EPS) apparatus comprises a plurality of inverter bridges each connected to a multi-phase motor configured to provide power assist to steering of a vehicle. After detection of a failure within one of said inverter bridges, the current flow within the faulty inverter bridge is controlled, and one or more of the other inverter bridges is used to provide power assistance. A control system for an electric power assisted steering (EPS) apparatus comprises a plurality of inverter bridges each connected to a multi-phase motor configured to provide power assist to steering of a vehicle, selection means for selectively operating switches in an inverter bridge in which a failure has been detected to control the current flow within the faulty inverter bridge, and control means for controlling one or more of the other inverter bridges to provide power assistance in accordance with the method.

Abstract: A method of controlling an electric power assisted steering (EPS) system comprising one or more inverter bridges each connected to a multi-phase motor configured to provide power assist to steering of a vehicle, each inverter comprising a plurality of switching elements each associated with a phase of the motor, is provided. The method comprises, preventing current flow in said one or more affected inverters by applying a gate-source voltage to one or more of the switching elements of the affected inverter bridge(s) in response to detecting a predefined event affecting current flow in one or more of the inverter bridges. A control system for an electric power assisted steering apparatus comprising one or more inverter bridges and a control means configured to control the switching elements in accordance with the method is also provided.

Abstract: A control circuit for a multi-phase motor (57) comprises a plurality of inverter bridges, a plurality of outputs, and at least one isolation switch (62, 63). Each inverter bridge is arranged to provide an output voltage for a phase of the motor (57). Each output is arranged to be coupled to one phase of the motor (57) to provide the output voltage to that phase of the motor (57). Each isolation switch (62, 63) is coupled between one of the inverter bridges and one of the outputs, so as to selectively isolate the output from the inverter bridge. Each isolation switch (62, 63) comprises a Gallium Nitride (GaN) transistor.

Abstract: A monitoring system for an electric power-assisted steering system comprising a DC power supply; an inverter bridge including a plurality of bridge switches selectively connecting phases of a multi-phase electric motor to the DC power supply, the multi-phase electric motor being configured to provide power-assistance to a steering system of a vehicle; a bridge driver circuit for providing control signals to the inverter bridge; and a DC link capacitor circuit interposed between the DC power supply and the inverter bridge, the DC link capacitor circuit at least one DC link capacitor. The monitoring system comprises a monitoring circuit configured to monitor the integrity of the DC link capacitor circuit, and outputting a ripple value indicative of a ripple voltage in an output of the DC power supply; and comparison means for comparing the ripple value with at least one ripple parameter indicative of a fault in the DC link capacitor circuit and determining whether a fault is present.

Abstract: A monitoring system for an electric power-assisted steering system comprising a DC power supply; an inverter bridge including a plurality of bridge switches selectively connecting phases of a multi-phase electric motor to the DC power supply, the multi-phase electric motor being configured to provide power-assistance to a steering system of a vehicle; a bridge driver circuit for providing control signals to the inverter bridge; and a DC link capacitor circuit interposed between the DC power supply and the inverter bridge, the DC link capacitor circuit at least one DC link capacitor. The monitoring system comprises a monitoring circuit configured to monitor the integrity of the DC link capacitor circuit, and outputting a ripple value indicative of a ripple voltage in an output of the DC power supply; and comparison means for comparing the ripple value with at least one ripple parameter indicative of a fault in the DC link capacitor circuit and determining whether a fault is present.

Abstract: A method of controlling an electric power assisted steering (EPS) system comprising one or more inverter bridges each connected to a multi-phase motor configured to provide power assist to steering of a vehicle, each inverter comprising a plurality of switching elements each associated with a phase of the motor, is provided. The method comprises, preventing current flow in said one or more affected inverters by applying a gate-source voltage to one or more of the switching elements of the affected inverter bridge(s) in response to detecting a predefined event affecting current flow in one or more of the inverter bridges. A control system for an electric power assisted steering apparatus comprising one or more inverter bridges and a control means configured to control the switching elements in accordance with the method is also provided.