Method and apparatus for controlling an electric pump of a hydraulic braking circuit
AssigneeTRW Inc.
InventorKenneth Vincent
Life of this patent
Estimating the term…
Abstract
A drive circuit for an electric motor of the type which forms part of a pump in a hydraulic braking circuit of a vehicle comprises an input node, an output node and a voltage and current regulating circuit which connects the nodes and which varies the voltage and current supplied to the output node from the input node in response to a modulation strategy, the input node in use being connected to a battery supply of a vehicle and the output node connected to one side of the electric motor. The voltage and current regulating circuit comprises a switch mode power supply circuit capable of providing at the output node a voltage that is either above or below the battery supply voltage at the input node.
Claims15
A drive circuit for an electric motor of the type which forms part of a pump in a hydraulic braking circuit of a vehicle, the drive circuit comprising:
- an input node, an output node and a voltage and current regulating circuit which connects the input node and the output node and which varies voltage and current supplied to the output node from the input node in response to a modulation strategy,
- the input node in use being connected to a battery supply of the vehicle and the output node connected to one side of the electric motor,
- in which the voltage and current regulating circuit comprises a switch mode power supply circuit capable of providing at the output node a voltage that is either above or below a battery supply voltage at the input node,
- in which the switch mode power supply comprises a buck-boost circuit which comprises a boost converter followed by a buck converter, with the buck converter and boost converter sharing common components,
- in which the switch mode power supply circuit includes a PWM controller which is adapted to supply pulse width modulated control that controls the voltage and current supplied to the output node, and
- in which the PWM controller provides PWM signals, in use, which cause the drive circuit to perform:
- (a) during a first period of time following a start-up of the electric motor cause the drive circuit to maintain a voltage supplied to the electric motor at a boosted voltage which exceeds a voltage present at the input node for a second period of time that is within the first period of time;
- and
- (b) after the first period of time has lapsed the PWM signals cause the drive circuit to provide a reduced voltage to the electric motor which is less than the voltage present at the input node.
A method of operating an electric motor of a pump of a hydraulic braking circuit during an initial period commencing with the start-up of the electric motor following a request for an increase of pressure in the hydraulic braking circuit, the electric motor being connected by a drive circuit to a battery of a vehicle, the battery having a nominal supply voltage, the method comprising steps of:
- (a) during a first predetermined period of time following start-up of the electric motor causing the drive circuit to apply a boosted voltage to the electric motor which exceeds a voltage present at the input node for a second period of time that is within the first period of time;
- and
- (b) after the first predetermined period of time has lapsed causing the drive circuit to provide a reduced voltage to the electric motor which is less than the voltage present at the input node.
Dependencies are inferred from the claim text.