Noise filter

Patent metadata

Field	Value
Publication number	US-12294347-B2
Application number	US-202318378298-A
Country	US
Kind code	B2
Filing date	Oct 10, 2023
Priority date	May 7, 2021
Publication date	May 6, 2025
Grant date	May 6, 2025

Abstract

A noise filter includes: a ground-side power supply line detecting circuit that is connected to each of a power supply line and a power supply line and detects a power supply line connected to an electrode from among the power supply line and the power supply line; and a control circuit that determines whether the power supply line connected to the electrode is the power supply line or the power supply line on the basis of a detection result by the ground-side power supply line detecting circuit, controls a relay to short-circuit between a Y capacitor and an electrical device ground when determining that the power supply line connected to the electrode is the power supply line, and controls a relay to short-circuit between a Y capacitor and the electrical device ground when determining that the power supply line connected to the electrode is the power supply line.

First claim

The invention claimed is:

1. A noise filter of an electrical device connected to an AC power supply having a first electrode connected to a power supply ground and a second electrode not connected to the power supply ground, the noise filter comprising:
a first power supply line connected to one of the first electrode and the second electrode;
a second power supply line connected to the other of the first electrode and the second electrode;
a first Y capacitor connected to the first power supply line;
a second Y capacitor connected to the second power supply line;
a first relay connected between the first V capacitor and an electrical device ground;
a second relay connected between the second Y capacitor and the electrical device ground;
a ground-side power supply line detecting circuit that is connected to each of the first power supply line and the second power supply line, and detects a power supply line connected to the first electrode from among the first power supply line and the second power supply line; and
a control circuit to determine whether a power supply line connected to the first electrode is the first power supply line or the second power supply line on a basis of a detection result by the ground-side power supply line detecting circuit, controls the first relay to short-circuit between the first Y capacitor and the electrical device ground when determining that the power supply line connected to the first electrode is the first power supply line, and controls the second relay to short-circuit between the second Y capacitor and the electrical device ground when determining that the power supply line connected to the first electrode is the second power supply line.

2. The noise filter according to claim 1 , wherein
in a case where a capacitance value of each of the first Y capacitor and the second Y capacitor is C [F], an upper limit value of a leakage current in the noise filter is I [A], an angular frequency of the AC power supply is ω [rad/s], and a power supply voltage of the AC power supply is V [V] a capacitance value C [F] of each of the first Y capacitor and the second Y capacitor follows the following Formula (1)

C
≥

I

ω
×
V

(
1
)

3. The noise filter according to claim 1 , wherein
the ground-side power supply line detecting circuit detects a first voltage between the first power supply line and the electrical device ground and detects a second voltage between the second power supply line and the electrical device ground, and
the control circuit
determines whether the power supply line connected to the first electrode is the first power supply line or the second power supply line by determining which of the amplitude of the first voltage and the amplitude of the second voltage detected by the ground-side power supply line detecting circuit is smaller,
controls the first relay to short-circuit between the first Y capacitor and the electrical device ground when determining that the amplitude of the first voltage is smaller than the amplitude of the second voltage, and
controls the second relay to short-circuit between the second Y capacitor and the electrical device ground when determining that the amplitude of the second voltage is smaller than the amplitude of the first voltage.

4. The noise filter according to claim 1 , wherein
the ground-side power supply line detecting circuit detects a first voltage between the first power supply line and the electrical device ground and detects a second voltage between the second power supply line and the electrical device ground, and
the control circuit, when determining that the power supply line connected to the first electrode is the first power supply line, controls the first relay to short-circuit between the first Y capacitor and the electrical device ground at a timing when the first voltage detected by the ground-side power supply line detecting circuit reaches zero, and when determining that the power supply line connected to the first electrode is the second power supply line, controls the second relay to short-circuit between the second Y capacitor and the electrical device ground at a timing when the second voltage detected by the ground-side power supply line detecting circuit reaches zero.

5. The noise filter according to claim 3 , wherein
the ground-side power supply line detecting circuit includes:
a first analog-to-digital converter to detect a voltage between the first power supply line and the electrical device ground; and
a second analog-to-digital converter to detect a voltage between the second power supply line and the electrical device ground.

6. The noise finer according to claim 4 , wherein
the ground-side power supply line detecting circuit includes:
a first analog-to-digital converter to detect a voltage between the first power supply line and the electrical device ground; and
a second analog-to-digital converter to detect a voltage between the second power supply line and the electrical device ground.

7. The noise finer according to claim 1 , wherein
the ground-side power supply line detecting circuit
compares a first voltage between the first power supply line and the electrical device ground with a threshold voltage, and outputs a first signal when the first voltage is equal to or more than the threshold voltage, and
compares a second voltage between the second power supply line and the electrical device ground with the threshold voltage, and outputs a second signal when the second voltage is equal to or more than the threshold voltage, and
the control circuit,
when the first signal is not output from the ground-side power supply line detecting circuit and the second signal is output from the ground-side power supply line detecting circuit during a certain period of time, or
when the first signal and the second signal are output from the ground-side power supply line detecting circuit and an output time of the second signal is longer than an output time of the first signal during a certain period of time,
controls the first relay to short-circuit between the first Y capacitor and the electrical device ground, and
when the first signal is output from the ground-side power supply line detecting circuit and the second signal is not output from the ground-side power supply line detecting circuit during a certain period of time, or
when the first signal and the second signal are output from the ground-side power supply line detecting circuit and an output time of the first signal is longer than an output time of the second signal during a certain period of time,
controls the second relay to short-circuit between the second Y capacitor and the electrical device ground.

8. The noise filter according to claim 7 , wherein
the ground-side power supply line detecting circuit includes a first comparator, a second comparator, and a DC power supply,
the first comparator has an input terminal connected to each of the first power supply line and a positive terminal of the DC power supply, an output terminal connected to the control circuit, and a ground terminal connected to the electrical device ground,
the second comparator has an input terminal connected to each of th

Assignees

• Mitsubishi Electric Corp

Inventors

• Otsuka Kyota
• Hirose Kenji
• Akeboshi Yoshihiro

Classifications

• H03H2001/0014

  Capacitor filters, i.e. capacitors whose parasitic inductance is of relevance to consider it as filter · CPC title

• H02H7/26

  Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured (locating faults in cables G01R31/08) · CPC title

• H02H7/20

  for electronic equipment (for converters H02H7/10; for electric measuring instruments G01R1/36; for DC voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08) · CPC title

• H02H3/023

  by short-circuiting · CPC title

• H02H9/007

  avoiding or damping oscillations, e.g. fenoresonance or travelling waves · CPC title