Auxiliary power supply device and electric power steering system

Patent metadata

Field	Value
Publication number	US-2020207404-A1
Application number	US-201916717284-A
Country	US
Kind code	A1
Filing date	Dec 17, 2019
Priority date	Dec 27, 2018
Publication date	Jul 2, 2020
Grant date	—

Abstract

An auxiliary power supply device includes an auxiliary power source and a booster circuit. The auxiliary power supply device is configured to be switched among a charging state, a holding state, and a discharging state. The auxiliary power source is configured to be switched between a serial connection mode and a parallel connection mode. The auxiliary power source is configured to perform boosting to supply power to the power supply target when the auxiliary power source is switched to the serial connection mode, and perform backup when the auxiliary power source is switched to the parallel connection mode.

First claim

What is claimed is:

1 . An auxiliary power supply device comprising:
an auxiliary power source; and a booster circuit for boosting input voltage, wherein: the auxiliary power supply device is provided in a power supply path extending from a main power source to a power supply target, and configured to be switched among a charging state for charging the auxiliary power source, a holding state for holding a charge voltage of the auxiliary power source, and a discharging state for discharging power from the auxiliary power source; the auxiliary power source is configured to be switched between a serial connection mode and a parallel connection mode, the serial connection mode being a mode in which a first terminal is connected to the main power source and a second terminal is connected to the power supply target, and the auxiliary power source is connected in series between the main power source and the power supply target, the parallel connection mode being a mode in which the first terminal is connected to a part between the main power source and the power supply target, at which the main power source and the power supply target are connected in series; and the auxiliary power source is configured to boost a voltage supplied from the main power source by a discharge voltage of the auxiliary power source to supply power to the power supply target when the auxiliary power source is switched to the serial connection mode, and the auxiliary power source is configured such that the second terminal is connected to an input terminal of the booster circuit, the discharge voltage of the auxiliary power source, which is an input voltage of the booster circuit, is boosted, and backup to supply the boosted discharge voltage to the power supply target is performed when the auxiliary power source is switched to the parallel connection mode.

2 . The auxiliary power supply device according to claim 1 , wherein the auxiliary power source is configured to be switched to the parallel connection mode, when power is supplied from the main power source to the power supply target, such that the second terminal is connected to an output terminal of the booster circuit, the input terminal of the booster circuit is connected to the main power source, an output voltage of the main power source, which is the input voltage of the booster circuit, is boosted, and the auxiliary power source is charged by the boosted output voltage.

3 . An electric power steering system comprising:
a motor serving as a power supply target; a main power source; an auxiliary power supply device provided in a power supply path extending from the main power source to the motor and including an auxiliary power source and a booster circuit for boosting an input voltage; and an electronic control unit, wherein: the electronic control unit is configured to
i) switch the auxiliary power source between a serial connection mode and a parallel connection mode, the serial connection mode being a mode in which a first terminal is connected to the main power source and a second terminal is connected to the motor, and the auxiliary power source is connected in series between the motor and the main power source, the parallel connection mode being a mode in which the first terminal is connected to a part between the main power source and the power supply target, at which the main power source and the power supply target are connected in series,
ii) switch among a charging state for charging the auxiliary power source, a holding state for holding a charge voltage of the auxiliary power source, and a discharging state for discharging power from the auxiliary power source, and
iii) switch the auxiliary power source between the serial connection mode and the parallel connection mode,
the auxiliary power source is configured to boost a voltage supplied from the main power source by a discharge voltage of the auxiliary power source to supply power to the motor when the electronic control unit switches the auxiliary power source to the serial connection mode; and the auxiliary power source is configured such that the second terminal of the auxiliary power source is connected to an input terminal of the booster circuit, the discharge voltage of the auxiliary power source, which is an input voltage of the booster circuit, is boosted, and backup to supply the boosted discharge voltage to the motor is performed when the electronic control unit switches the auxiliary power source to the parallel connection mode.

4 . An electric power steering system according to claim 3 , wherein the electronic control unit is configured to switch the auxiliary power source to the parallel connection mode, when the auxiliary power source supplies power from the main power source to the power supply target, such that the second terminal is connected to an output terminal of the booster circuit, the input terminal of the booster circuit is connected to the main power source, an output voltage of the main power source, which is the input voltage of the booster circuit, is boosted, and the auxiliary power source is charged by the boosted output voltage.

Assignees

• Jtekt Corp

Inventors

• Sugiyama Toyoki
• Shinoda Satoshi

Classifications

• H02J7/90

  Regulation of charging or discharging current or voltage · CPC title

• H02J7/865

  Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence) · CPC title

• H02J7/575

  Parallel/serial switching of connection of batteries to charge or load circuit · CPC title

• H02J7/345

  using capacitors as storage or buffering devices · CPC title

• H02J7/1423

  with multiple batteries · CPC title