Electric power steering apparatus

Patent metadata

Field	Value
Publication number	US-11613304-B2
Application number	US-201616085641-A
Country	US
Kind code	B2
Filing date	Apr 8, 2016
Priority date	Apr 8, 2016
Publication date	Mar 28, 2023
Grant date	Mar 28, 2023

Abstract

A plurality of power supply circuits include a second power supply circuit for a CPU included in a control unit and a first power supply circuit for another circuit. An output voltage from the first power supply circuit is higher than an output voltage from the second power supply circuit. A range of input voltage is divided into three levels of voltage sub-ranges in accordance with a requirements specification. When the input voltage falls within a lower level voltage sub-range, both of an output function of the first power supply circuit and an output function of the second power supply circuit are stopped. When the input voltage falls within an intermediate level voltage sub-range, the output function of the first power supply circuit is stopped. When the input voltage falls within an upper level voltage sub-range, all circuits are controlled so as to operate.

First claim

The invention claimed is:

1. An electric power steering apparatus, comprising:
an electric motor to rotate a steering mechanism of a vehicle;
a control unit, which drives the electric motor, and includes a CPU and a plurality of power supply circuits; and
a power supply control circuit to output a stop signal for individually stopping output functions of the plurality of power supply circuits based on a result of reading an input voltage supplied in common to the plurality of power supply circuits,
the plurality of power supply circuits including:
a first power supply circuit to generate from the input voltage a first output voltage to be supplied to a circuit other than the CPU; and
a second power supply circuit to generate from the input voltage a second output voltage to be supplied to the CPU included in the control unit,

wherein the first output voltage is higher than the second output voltage, the first output voltage and the second output voltage being supplied at the same time,
wherein the power supply control circuit has at least three voltage sub-ranges being an upper level voltage sub-range, an intermediate level voltage sub-range, and a lower level voltage sub-range obtained by dividing a range of the input voltage, the at least three voltage sub-ranges being preset in accordance with a requirements specification, and
wherein the power supply control circuit controls the first power supply circuit and the second power supply circuit by, in accordance with the result of reading the input voltage, outputting the stop signal to both the first power supply circuit and the second power supply circuit when the input voltage falls within the lower level voltage sub-range, outputting the stop signal to the first power supply circuit when the input voltage falls within the intermediate level voltage sub-range, and preventing the stop signal from being output when the input voltage falls within the upper level voltage sub-range.

2. The electric power steering apparatus according to claim 1 ,
wherein the first power supply circuit generates from the input voltage the first output voltage to be supplied to a circuit other than a driver for the electric motor and the CPU,
wherein the plurality of power supply circuits further include a third power supply circuit to generate from the input voltage a third output voltage to be supplied to the driver for the electric motor,
wherein the third output voltage is higher than the first output voltage and the second output voltage,
wherein the power supply control circuit further has a first upper level voltage sub-range and a second upper level voltage sub-range higher than the first upper level voltage sub-range, which are preset as two upper level voltage sub-ranges obtained by dividing the upper level voltage sub-range of the range of the input voltage in accordance with the requirements specification, and
wherein the power supply control circuit controls the first power supply circuit, the second power supply circuit, and the third power supply circuit by, in accordance with the result of reading the input voltage, outputting the stop signal to all of the first power supply circuit, the second power supply circuit, and the third power supply circuit when the input voltage falls within the lower level voltage sub-range, outputting the stop signal to the first power supply circuit and the third power supply circuit when the input voltage falls within the intermediate level voltage sub-range, outputting the stop signal to the third power supply circuit when the input voltage falls within the first upper level voltage sub-range of the upper level voltage range, and preventing the stop signal from being output when the input voltage falls within the second upper level voltage sub-range of the upper level voltage range.

3. The electric power steering apparatus according to claim 2 , wherein the power supply control circuit is built into the CPU.

4. The electric power steering apparatus according to claim 3 , wherein the third power supply circuit has a step-up function to output a voltage higher than the input voltage.

5. The electric power steering apparatus according to claim 2 , wherein the third power supply circuit has a step-up function to output a voltage higher than the input voltage.

6. The electric power steering apparatus according to claim 2 , wherein each of the first power supply circuit and the second power supply circuit has a step-up function to output a voltage higher than the input voltage and a step-down function to output a voltage lower than the input voltage.

7. The electric power steering apparatus according to claim 2 , wherein each of the first power supply circuit and the second power supply circuit has a minimum operating voltage set to fall within a voltage range lower than a predicted decreased voltage, which is predicted based on a decrease in voltage of a battery being a supply source of the input voltage.

8. The electric power steering apparatus according to claim 2 , further comprising a voltage monitoring circuit to monitor the second output voltage to be supplied to the CPU, and to output a reset signal or an abnormality signal for informing of a power supply abnormality to the CPU when the second output voltage becomes less than a preset allowable minimum value.

9. The electric power steering apparatus according to claim 1 , wherein each of the first power supply circuit and the second power supply circuit has a step-up function to output a voltage higher than the input voltage and a step-down function to output a voltage lower than the input voltage.

10. The electric power steering apparatus according to claim 1 , wherein each of the first power supply circuit and the second power supply circuit has a minimum operating voltage set to fall within a voltage range lower than a predicted decreased voltage, which is predicted based on a decrease in voltage of a battery being a supply source of the input voltage.

11. The electric power steering apparatus according to claim 1 , further comprising a voltage monitoring circuit to monitor the second output voltage to be supplied to the CPU, and to output a reset signal or an abnormality signal for informing of a power supply abnormality to the CPU when the second output voltage becomes less than a preset allowable minimum value.

Assignees

• Mitsubishi Electric Corp

Inventors

• Iida Hajime

Classifications

• H02M7/53873

  with digital control · CPC title

• B62D5/0406

  including housing for electronic control unit · CPC title

• B62D5/0463

  calculating assisting torque from the motor based on driver input · CPC title

• H02P2201/11

  Buck converter, i.e. DC-DC step down converter decreasing the voltage between the supply and the inverter driving the motor · CPC title

• B62D5/0484 Primary

  for reaction to failures, e.g. limp home · CPC title