Over-current protection method and circuit for a DC inverter

Patent metadata

Field	Value
Publication number	US-9698591-B2
Application number	US-201514706284-A
Country	US
Kind code	B2
Filing date	May 7, 2015
Priority date	Sep 23, 2014
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

An over-current protection method and circuit for a DC Inverter is provided in the present invention. Said over-current protection circuit comprises: a sampling unit for sampling output currents from a power module to form a sampling signal; a signal-processing unit for amplifying with various magnification factors and low-pass filtering the sampling signal to generate a first over-current signal and a second over-current signal; a signal-generating unit for generating a first interrupt trigger signal based on the first over-current signal; a comparison unit for comparing the second over-current signal with a reference voltage corresponding to an over-current threshold of a motor, with a comparison result being a second interrupt trigger signal; and a control unit for controlling the power module based on the first interrupt trigger signal, and the motor based on the second interrupt trigger signal. The over-current protection method and circuit provided in the present invention are able to satisfy over-current protection of the power module and the motor of the inverter simultaneously.

First claim

The invention claimed is:

1. An over-current protection method for a DC Inverter, wherein said over-current protection method comprises:
sampling output currents from a power module to form a sampled signal;
amplifying with a plurality of magnification factors and low-pass filtering said sampling signal to generate a first over-current signal and a second over-current signal, wherein a first magnification factor, on the basis of which said first over-current signal is generated, is pertinent to an over-current threshold of said power module, and a second magnification factor, on the basis of which said second over-current signal is generated, is pertinent to an over-current threshold of a motor;
generating a first interrupt trigger signal based on said first over-current signal;
comparing said second over-current signal with a reference voltage corresponding to said over-current threshold of the motor, with a comparison result being a second interrupt trigger signal;
controlling said power module based on said first interrupt trigger signal; and
controlling said motor based on said second interrupt trigger signal.

2. The over-current protection method as defined in claim 1 , wherein said over-current threshold of the motor is dynamically adjustable.

3. An over-current protection circuit for a DC Inverter, wherein said over-current protection circuit comprises:
a sampling unit for sampling output currents from a power module to form a sampling signal;
a signal-processing unit for amplifying with a plurality of magnification factors and low-pass filtering said sampling signal to generate a first over-current signal and a second over-current signal, wherein a first magnification factor, on the basis of which said first over-current signal is generated, is pertinent to an over-current threshold of said power module, and a second magnification factor, on the basis of which said second over-current signal is generated, is pertinent to an over-current threshold of a motor;
a signal-generating unit for generating a first interrupt trigger signal based on said first over-current signal;
a comparison unit for comparing said second over-current signal with a reference voltage corresponding to said over-current threshold of the motor, with a comparison result being a second interrupt trigger signal; and
a control unit for controlling said power module based on said first interrupt trigger signal, and said motor based on said second interrupt trigger signal.

4. The over-current protection circuit as defined in claim 3 , wherein said over-current threshold of the motor is obtained via digital-to-analog conversion after calculation by said control unit on the basis of specifications and running states of said motor.

5. The over-current protection circuit as defined in claim 4 , wherein a digital-to-analog converter used for said digital-to-analog conversion is comprised inside said control unit.

6. The over-current circuit as defined in claim 3 , wherein said comparison unit is comprised inside said control unit.

7. The over-current circuit as defined in claim 3 , wherein dynamic adjustability of said over-current threshold of the motor is realized by a duty ratio generated from a pulse-width modulation output of said control unit together with a resistance-capacitance low-pass filter circuit.

8. The over-current protection circuit as defined in claim 3 , wherein said sampling unit comprises a sampling resistance.

9. The over-current protection circuit as defined in claim 3 , wherein said signal-processing unit comprises an operational amplifier and a low-pass filter, and said operational amplifier is a non-inverting amplifier.

10. The over-current circuit as defined in claim 3 , wherein said signal-generating unit is said power module.

Assignees

• Johnson Controls Tech Co
• Johnson Controls Air Conditioning And Refrigeration (Wuxi) Co Ltd
• York Guangzhou Air Conditioning And Refrigeration Co Ltd

Inventors

• Jiang Chenyi

Classifications

• H02H7/1227 Primary

  responsive to abnormalities in the output circuit, e.g. short circuit · CPC title

• H02H3/006

  Calibration or setting of parameters · CPC title

• H02H7/0811

  for DC motors (H02H7/0833 takes precedence) · CPC title