Trw Limited

Zf Automotive UK Limited

Tamas Terdy

Maciej Kudanowski

Charles Mahendhrarajah

Nathanael Rice

A method of controlling an electric power assisted steering (EPS) system includes the steps: During a first mode of operation of the EPS system driving a motor using two inverter bridges simultaneously, the nominal current that is applied to the motor at any time by each bridge being limited to a first value, and during a fault mode of operation driving the motor using only one of the two inverter bridges. The nominal current that is applied to the motor at any time in the fault mode is limited to a second value. The method varying the second value as a function of one or more operating parameters of the EPS system. The second value is set higher than the first value when it is deemed safe to do so.

Control for electric power steering

A control circuit for a multi-phase motor () comprises a plurality of inverter bridges, a plurality of outputs, and at least one isolation switch (). Each inverter bridge is arranged to provide an output voltage for a phase of the motor (). Each output is arranged to be coupled to one phase of the motor () to provide the output voltage to that phase of the motor (). Each isolation switch () 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 () comprises a Gallium Nitride (GaN) transistor.

Control circuit for a multi-phase motor

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.

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.

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, wherein each inverter comprises a plurality of switching elements each associated with a phase of the motor, the method comprising in response to detecting a predefined event affecting current flow in one or more of the inverter bridges, 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), wherein the switching elements are configured to conduct in the off-state when reverse biased beyond a reverse conduction threshold voltage, and wherein applying the gate-source voltage comprises applying a negative gate-source voltage to control the reverse conduction threshold voltage of the switching elements in the off-state only at a time when there is no current flowing in the direction drain to source through the switching device that exceeds a threshold value.

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.

Growing community of inventors

Birmingham, United Kingdom

Tamas Terdy