Electroplating power supply apparatus

• US 20030035305A1
• Filed: 08/16/2002
• Published: 02/20/2003
• Est. Priority Date: 08/17/2001
• Status: Active Grant

• Current Assignee: Sansha Electric Manufacturing Company Limited
• Original Assignee: Sansha Electric Manufacturing Company Limited
• Inventors: Arai, Toru, Nishioka, Yoshiyuki, Sakurada, Makoto
• Granted Patent: US 6,754,090 B2
• Time in Patent Office: Days
• US Class Current: 363/17
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 1/0087 adapted for receiving as input a current source
• CPC Class Codes: H02M 3/28 using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
• CPC Class Codes: H02M 5/225 comprising two stages of AC-AC conversion, e.g. having a high frequency intermediate link
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode

Abstract

A power supply apparatus for use in electroplating includes an input-side rectifier (32). A rectifier output is converted into high-frequency signals in inverters (38a, 38b), which are transformed in transformers (48a, 48b). When the transformed high-frequency signals from the transformers are of positive polarity, they are rectified by a diode (50a or 50b) to cause a positive current to be supplied to a load (60). When the transformed high-frequency signals are of negative polarity, they are rectified by a diode (50c or 50d) to thereby cause a negative current to flow through the load. A first IGBT (54a) is connected in series with each of the diodes (50a, 50b) and is rendered conductive and nonconductive at a frequency lower than the high-frequency signal. Also, a second IGBT (54b) is connected in series with each of the diodes (50c and 50d) and is rendered nonconductive when the IGBT and nonconductive at the lower frequency. When the first IGBT is rendered conductive, the second IGBT is rendered nonconductive, and vice versa. The inverters (38a, 38b) are controlled in synchronization with the firs t and second IGBTs (54a, 54b) in such a manner that the high-frequency signal can have a larger magnitude when the second IGBT (54b) is conductive than when the first IGBT (54a) is conductive.

Claims

1. A power supply apparatus for use in electroplating, comprising:

an input-side rectifier adapted for rectifying commercial AC power;

a DC-to-high-frequency converter for converting an output of said input-side rectifier to a high-frequency signal;

a transformer for transforming a high-frequency signal from said DC-to-high-frequency converter and developing a high-frequency transformer output signal;

a first output-side rectifier connected between said transformer and a load in such a manner as to rectify said high-frequency transformer output signal of said transformer to cause a positive current to flow in said load when said high-frequency transformer output signal is of positive polarity;

a second output-side rectifier connected in parallel with said first output-side rectifier for rectifying said high-frequency transformer output signal of said transformer, when said high-frequency transformer output signal is of negative polarity, to cause a negative current to flow in said load;

a first semiconductor switching device connected in series with said first output-side rectifier and rendered conductive and nonconductive at a frequency lower than said high-frequency signal; and

a second semiconductor switching device connected in series with said second output-side rectifier, said second semiconductor switching device being nonconductive when said first semiconductor switching device is conductive, and conductive when said first semiconductor switching device is nonconductive;

said DC-to-high-frequency converter being controlled in synchronization with said first and second semiconductor switching devices in such a manner that said high-frequency signal has a larger magnitude when said second semiconductor switching device is conductive than when said first semiconductor switching device is conductive.

2. The power supply apparatus according to claim 1 further comprising:

first and second reactors connected respectively to said first and second semiconductor switching devices;

wherein said first and second reactors are wound on a same core in such a manner that when said second semiconductor switching device is nonconductive, a positive voltage to be applied to said load can be increased, and when said first semiconductor switching device is nonconductive, a negative voltage to be applied to said load can be increased.

3. The power supply apparatus according to claim 1 further comprising:

charge storage means charged when current is being applied to said load; and

discharging means responsive to turning on of one of said first and second semiconductor switching devices for discharging said charge storage means in such a manner that discharge current of the same polarity as the current flowing through said load can flow.

4. The power supply apparatus according to claim 1 wherein said DC-to-high-frequency converter includes a converting semiconductor switching device and control means for turning said converting semiconductor switching device on and off, said control means providing a control signal for ON-OFF controlling said converting semiconductor switching device in such a manner that a difference between a positive current flowing through said load and a positive-current reference value set for the positive current can become zero and that a difference between a negative current flowing through said load and a negative-current reference value set for the negative current can become zero;

wherein said power supply apparatus comprises further sample-and-hold means for sampling and holding said control signal provided by said control means when said negative current flows through said load, and for supplying the sampled and held control signal to said converting semiconductor switching device when the current flowing through said load changes from a positive current to a negative current.

5. The power supply apparatus according to claim 3 further comprising:

detecting for detecting when said load is open-circuited; and

short-circuiting semiconductor switching device for short-circuiting that one of said first and second reactors through which current is flowing when said detecting means detects the open-circuiting of said load.

6. The power supply apparatus according to claim 1 wherein said DC-to-high-frequency converter comprises two inverters connected in series between output terminals of said input-side rectifier, and said input-side rectifier is to be connected to such a commercial AC power supply that said input-side rectifier can provide a rectified output voltage which is about two times as large as the voltage which each of said inverters can handle.