US 2009/0021278 A1 · Commutation failure detection circuit for back-to-back SCR circuit and controlling method thereof having relatively better efficiency

Abstract

The configurations of a commutation failure detection circuit for a back-to-back SCR circuit and the controlling methods thereof are provided. The proposed commutation failure detection circuit includes a first detecting signal generator coupled to the back-to-back SCR circuit for detecting a commutation at a negative half cycle of an AC input voltage and including a first non-conductive signal amplifier circuit generating a first non-conductive signal when the back-to-back SCR circuit is not conductive at the negative half cycle of the AC input voltage and a second detecting signal generator coupled to the back-to-back SCR circuit for detecting the commutation at a positive half cycle of the AC input voltage and including a second non-conductive signal amplifier circuit generating a second non-conductive signal when the back-to-back SCR circuit is not conductive at the positive half cycle of the AC input voltage.

Claims22

Dependent claims

A commutation failure detection circuit for a back-to-back silicon controlled rectifier (SCR) circuit, comprising:

a first detecting signal generator coupled to the back-to-back SCR circuit for detecting a commutation at a negative half cycle of an AC input voltage, comprising:
a first non-conductive signal amplifier circuit generating a first non-conductive signal when the back-to-back SCR circuit is not conductive at the negative half cycle of the AC input voltage;
a first non-conductive signal driver receiving and transferring the first non-conductive signal;
and
a first non-conductive signal isolator receiving the transferred first non-conductive signal for generating a first commutation detecting signal at a first status when the first non-conductive signal is absent;
and
a second detecting signal generator coupled to the back-to-back SCR circuit for detecting the commutation at a positive half cycle of the AC input voltage, comprising:
a second non-conductive signal amplifier circuit generating a second non-conductive signal when the back-to-back SCR circuit is not conductive at the positive half cycle of the AC input voltage;
a second non-conductive signal driver receiving and transferring the second non-conductive signal;
and
a second non-conductive signal isolator receiving the transferred second non-conductive signal for generating a second commutation detecting signal at the first status when the second non-conductive signal is absent.

8 more elements

A commutation failure detection circuit for a back-to-back SCR circuit, comprising:

a first detecting signal generator coupled to the back-to-back SCR circuit for detecting a commutation at a negative half cycle of an AC input voltage, comprising:
a first non-conductive signal amplifier circuit generating a first non-conductive signal when the back-to-back SCR circuit is not conductive at the negative half cycle of the AC input voltage, and comprising a first non-conductive signal amplifier amplifying the first non-conductive signal;
and
a second detecting signal generator coupled to the back-to-back SCR circuit for detecting the commutation at a positive half cycle of the AC input voltage, comprising:
a second non-conductive signal amplifier circuit generating a second non-conductive signal when the back-to-back SCR circuit is not conductive at the positive half cycle of the AC input voltage, and comprising a second non-conductive signal amplifier amplifying the second non-conductive signal.

2 more elements

A controlling method for a commutation failure detection circuit of a back-to-back SCR circuit, wherein the back-to-back SCR circuit comprises a first and a second SCRs each having a cathode, and the commutation failure detection circuit comprises a first and a second non-conductive signal amplifier circuits coupled to cathodes of the first and the second SCRs respectively, a first and a second non-conductive signal drivers coupled to the first and the second non-conductive signal amplifier circuits respectively and a first and a second non-conductive signal isolators coupled to the first and the second non-conductive signal drivers respectively, comprising the steps of:

(a) causing a forward voltage to present across the first and the second SCRs;
(b) causing the second non-conductive signal amplifier circuit to be turned on so as to turn on the second non-conductive signal driver such that the second non-conductive signal isolator outputs a commutation detecting signal having a first status when a first potential voltage of the cathode of the first SCR is higher than a second potential voltage of the cathode of the second SCR, neither of the first and the second SCRs is conducting and it is during a positive half cycle of an AC input voltage of the first and the second SCRs;
and
(c) causing the second non-conductive signal amplifier circuit to be turned off so as to turn off the second non-conductive signal driver such that the second non-conductive signal isolator outputs the commutation selecting signal having a second status when a difference between the first potential voltage and the second potential voltage equals to the forward voltage, one of the first and the second SCRs is conducting and it is during the positive half cycle of the AC input voltage.

1 more element

Dependencies are inferred from the claim text.

Commutation failure detection circuit for back-to-back SCR circuit and controlling method thereof having relatively better efficiency

Life of this patent

Commutation failure detection circuit for back-to-back SCR circuit and controlling method thereof having relatively better efficiency

Life of this patent

Abstract

Claims22