Electric power steering apparatus and electricity supply system

1. An electric power steering apparatus installed in a vehicle having a primary power source that generates primary voltage, wherein the vehicle has a steering system and an in-vehicle network for communicating information, the electric power steering apparatus comprising:

a steering force assisting device that supplies assisting force for assisting steering operation to the steering system, wherein the assisting device has a steering motor serving as a driving source of the assisting force;

a transformer section that transforms the primary voltage and outputs secondary voltage; and

a control section that controls the steering force assisting device by supplying driving electricity based on the secondary voltage to the steering motor, wherein the control section inputs a first signal indicating a state of electricity supply of the primary power source through the in-vehicle network, wherein the control section supplies driving electricity to the steering motor based on the first signal, wherein the transformer section outputs a second signal indicating a state of electricity supply of the transformer section, and wherein, when the input of the first signal is disrupted, the control section limits the driving electricity supplied to the steering motor based on at least one of a value of the secondary voltage and the electricity supply state of the transformer section indicated by the second signal.

2. An electric power steering apparatus installed in a vehicle having a primary power source that generates primary voltage, wherein the vehicle has a steering system and an in-vehicle network for communicating information, the electric power steering apparatus comprising:

a steering force assisting device that supplies assisting force for assisting steering operation to the steering system, wherein the assisting device has a steering motor serving as a driving source of the assisting force;

a transformer section that transforms the primary voltage and outputs secondary voltage; and

a control section that controls the steering force assisting device by supplying driving electricity based on the secondary voltage to the steering motor, wherein the control section inputs a signal indicating a state of electricity supply of the primary power source through the in-vehicle network, wherein the control section supplies the driving electricity to the steering motor based on the signal, wherein the control section includes a detection section that detects a value of the secondary voltage and a determination section that determines a limiting rate of an amount of current supplied to the steering motor based on the value of the secondary voltage detected by the detection section, wherein, when the input of the signal is disrupted, the control section limits the driving electricity supplied to the steering motor based on the limiting rate determined by the determination section.

3. The electric power steering apparatus according to claim 2 ,

wherein, as the secondary voltage detected by the detection section becomes lower, the control section determines the limiting rate in such a manner that the current amount supplied to the steering motor becomes smaller.

4. The electric power steering apparatus according to claim 2 ,

wherein the signal is a first signal, and the transformer section outputs a second signal indicating a state of electricity supply of the transformer section,

wherein the determination section is a first determination section, and the limiting rate is a first limiting rate,

wherein the control section includes a second determination section that determines a second limiting rate of the current amount supplied to the steering motor based on the second signal, and

wherein, when the input of the first signal is disrupted, the control section limits the driving electricity supplied to the steering motor based on the first and second limiting rates.

5. The electric power steering apparatus according to claim 4 ,

wherein the control section limits the driving electricity supplied to the steering motor based on the product of the first and second limiting rates.

6. An electricity supply system installed in a vehicle having a primary power source that generates primary voltage, wherein the vehicle has a motor and an in-vehicle network for communicating information, the system comprising:

a transformer section that transforms the primary voltage and outputs secondary voltage;

a monitoring section that monitors a state of electricity supply of the primary power source, wherein the monitoring section outputs, to the in-vehicle network, a first signal indicating the electricity supply state of the primary power source; and

a control section that supplies driving electricity based on the secondary voltage to the motor, wherein the control section inputs a first signal through the in-vehicle network, wherein the control section supplies driving electricity to the motor based on the first signal, wherein the transformer section outputs a second signal indicating a state of electricity supply of the transformer section, and wherein, when the input of the first signal is disrupted, the control section limits the driving electricity supplied to the motor based on at least one of a value of the secondary voltage and the electricity supply state of the transformer section indicated by the second signal.