VOLTAGE BOOSTER APPARATUS FOR POWER STEERING SYSTEM
First Claim
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1. A voltage booster apparatus for a power steering system comprising:
- a booster power supply terminal for supplying a battery voltage;
a power supply relay;
a booster circuit including a coil, a step-up switching element, a backflow prevention element and an output capacitor, the coil having an input end connected in series with the booster power supply terminal through the power supply relay, the step-up switching element having one end connected to an output end of the coil and an other end connected to a ground, the backflow prevention element having one end connected to the output end of the coil in parallel with the step-up switching element to prevent backflow of a current from an other end thereof to the one end thereof, and the output capacitor having one end connected to the other end of the backflow prevention element and an other end connected to the ground;
a booster circuit control section connected to a control terminal of the step-up switching element to perform voltage boosting control by turning on and off the step-up switching element;
a power supply relay control section configured to supply or interrupt the battery voltage to the input end of the coil by turning on and off the power supply relay;
a voltage monitor section configured to check whether a short-circuit failure is present in the step-up switching element or the backflow prevention element by monitoring at least one of a coil input voltage developed at the input end of the coil, a coil output voltage developed at the coil output end and a boosted voltage developed at the one end of the output capacitor;
the voltage monitor section being configured to control, upon detection of the short-circuit failure, the power supply relay control section to turn off the power supply relay thereby stopping a power steering operation;
a charge power supply terminal provided to supply a reference voltage to the booster circuit;
a charge switching element connected between the output end of the coil and the charge power supply terminal; and
a charge circuit control section connected to a control terminal of the charge switching element for supplying or interrupting the reference voltage to the output end of the coil by turning on and off the charge switching element,wherein the charge circuit control section is configured to supply the reference voltage to the booster circuit by turning on the charge switching element after the power supply relay is turned off by the power supply relay control section, and the booster circuit control section or the relay control section is configured to perform a predetermined operation, so that the voltage monitor section checks whether the short-circuit failure is present, andwherein the power supply relay control section is configured to turn on the power supply relay again thereby restoring the power steering operation, when no short-circuit failure is determined.
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Abstract
In a voltage booster apparatus, a charge control transistor is turned on to charge a coil output capacitor and a booster output capacitor and then turned off, thereby confirming rise of a coil output voltage and a booster output voltage. A power supply relay is turned on to restore a booster operation thereby to check rise of the booster output voltage. If both of a step-up FET and a step-down FET are not in short-circuit failure, ON state of the power supply relay is fixed thereby to restore a power steering system operation.
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Citations
11 Claims
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1. A voltage booster apparatus for a power steering system comprising:
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a booster power supply terminal for supplying a battery voltage; a power supply relay; a booster circuit including a coil, a step-up switching element, a backflow prevention element and an output capacitor, the coil having an input end connected in series with the booster power supply terminal through the power supply relay, the step-up switching element having one end connected to an output end of the coil and an other end connected to a ground, the backflow prevention element having one end connected to the output end of the coil in parallel with the step-up switching element to prevent backflow of a current from an other end thereof to the one end thereof, and the output capacitor having one end connected to the other end of the backflow prevention element and an other end connected to the ground; a booster circuit control section connected to a control terminal of the step-up switching element to perform voltage boosting control by turning on and off the step-up switching element; a power supply relay control section configured to supply or interrupt the battery voltage to the input end of the coil by turning on and off the power supply relay; a voltage monitor section configured to check whether a short-circuit failure is present in the step-up switching element or the backflow prevention element by monitoring at least one of a coil input voltage developed at the input end of the coil, a coil output voltage developed at the coil output end and a boosted voltage developed at the one end of the output capacitor; the voltage monitor section being configured to control, upon detection of the short-circuit failure, the power supply relay control section to turn off the power supply relay thereby stopping a power steering operation; a charge power supply terminal provided to supply a reference voltage to the booster circuit; a charge switching element connected between the output end of the coil and the charge power supply terminal; and a charge circuit control section connected to a control terminal of the charge switching element for supplying or interrupting the reference voltage to the output end of the coil by turning on and off the charge switching element, wherein the charge circuit control section is configured to supply the reference voltage to the booster circuit by turning on the charge switching element after the power supply relay is turned off by the power supply relay control section, and the booster circuit control section or the relay control section is configured to perform a predetermined operation, so that the voltage monitor section checks whether the short-circuit failure is present, and wherein the power supply relay control section is configured to turn on the power supply relay again thereby restoring the power steering operation, when no short-circuit failure is determined. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A voltage booster apparatus for a power steering system comprising:
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a battery for supplying a battery voltage; a booster circuit including a coil, a step-up switching element, an output capacitor and a current flow control element, the coil having an input end for receiving the battery voltage, the step-up switching element being connected in series with the coil at an output end of the coil, the output capacitor being connected in series with the coil in parallel relation with the step-up switching element, and the current flow control element being connected between the output end of the coil and one end of the capacitor for preventing a current flow from the capacitor to the coil; a charge switching element connected to the output end of the coil for supplying a reference voltage to the output end of the coil when turned on; a control unit configured to control a voltage boosting operation of the booster circuit by turning on and off the step-up switching element so that the coil produces a coil output voltage at the coil output end a boosted voltage is produced from the output capacitor; the control unit being configured to interrupt supply of the battery voltage to the booster circuit upon detection of a short-circuit failure of the step-up switching element or the current flow control element; the control unit being configured to turn on the charge switching element to supply the reference voltage to the output end of the coil for charging the output capacitor by the reference voltage in response to interruption of the battery voltage; the control unit being configured to turn on the step-up switching element in a predetermined manner after the output capacitor is charged with the reference voltage; the control unit being configured to check whether the step-up switching element and the current flow control element have the short-circuit failure based on the coil output voltage and the boosted voltage produced after the charge switching element is turned on to supply the reference voltage; and the control unit being configured to restore the supply of the battery voltage to the booster circuit after both of the step-up switching element and the current flow control element are determined to have no short-circuit failure. - View Dependent Claims (9, 10, 11)
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Specification