Protective device for vehicle inverter

Patent metadata

Field	Value
Publication number	US-9692351-B2
Application number	US-201315022380-A
Country	US
Kind code	B2
Filing date	Nov 7, 2013
Priority date	Nov 7, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

This invention provides a protective device for a vehicle inverter, with which an inverter element can be protected from overheating while preventing a reduction in drivability. The protective device for a vehicle inverter includes a maximum element temperature calculation unit that calculates a maximum element temperature among respective element temperatures of the inverter, and an element temperature output limit coefficient calculation unit that calculates an output limit value corresponding to the maximum element temperature, sets a current output limit value as a current output limit coefficient when the current output limit value is smaller than a preceding output limit coefficient, and sets, as the current output limit coefficient, a value obtained by adding a predetermined value determined in advance to the preceding output limit coefficient when the current output limit value equals or exceeds the preceding output limit coefficient.

First claim

The invention claimed is:

1. A protective device for a vehicle inverter, which protects an inverter that drives a motor provided in a vehicle as a power source from overheating, comprising:
a maximum element temperature calculation unit that calculates a maximum element temperature among respective element temperatures of the inverter;
an element temperature output limit coefficient calculation unit that calculates an output limit value corresponding to the maximum element temperature, sets a current output limit value as a current output limit coefficient when the current output limit value is smaller than a preceding output limit coefficient, and sets, as the current output limit coefficient, a value obtained by adding a predetermined value determined in advance to the preceding output limit coefficient when the current output limit value equals or exceeds the preceding output limit coefficient;
a basic torque limit value calculation unit that calculates a basic torque limit value from a map on the basis of a motor rotation speed of the motor; and
a torque limit value determination unit that determines a torque limit value by multiplying the basic torque limit value by the element temperature output limit coefficient.

2. The protective device for a vehicle inverter according to claim 1 , further comprising:
a water temperature output limit coefficient calculation unit that calculates a water temperature output limit coefficient on the basis of a water temperature of cooling water in the inverter; and
a limit coefficient selection unit that selects and outputs a smaller output limit coefficient of the element temperature output limit coefficient and the water temperature output limit coefficient,
wherein the torque limit value determination unit determines the torque limit value by multiplying the basic torque limit value by the element temperature output limit coefficient or the water temperature output limit coefficient selected by the limit coefficient selection unit.

3. The protective device for a vehicle inverter according to claim 2 , wherein the water temperature output limit coefficient calculation unit calculates the water temperature output limit coefficient on the basis of a ratio between a value obtained by subtracting the water temperature of the cooling water from a predetermined upper limit element temperature and a value obtained by subtracting a design water temperature, which is a water temperature at which to start applying torque limitation, from the upper limit element temperature.

Assignees

• Mitsubishi Electric Corp

Inventors

• Enoki Keiichi

Classifications

• H02P29/032

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title

• H02H7/122

  for inverters, i.e. DC/AC converters · CPC title

• H02H6/00

  Emergency protective circuit arrangements responsive to undesired changes from normal non-electric working conditions using simulators of the apparatus being protected, e.g. using thermal images · CPC title

• H02P29/68 Primary

  based on the temperature of a drive component or a semiconductor component · CPC title

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title