Electric power conversion systems – Current conversion – With condition responsive means to control the output...
Reexamination Certificate
2001-03-14
2002-12-17
Patel, Rajnikant B. (Department: 2838)
Electric power conversion systems
Current conversion
With condition responsive means to control the output...
C363S021060
Reexamination Certificate
active
06496395
ABSTRACT:
BACKGROUND OF THE INVENTION
A plurality of switching converters are used as a power supply of typically a disk array apparatus consuming a relatively large current. The switching converters are each used as a direct-current power supply and connected to each other in parallel to supply a voltage of several volts. It is necessary to efficiently control a load borne by each of the switching converters connected in parallel to constitute the power supply. The switching converter serving as such a direct-current power supply is disclosed in Japanese Patent Laid-open Nos. Hei 9-93929/1997 and Hei 9-233816/1997.
FIG. 12
is a diagram showing the configuration of a direct-current power supply based on the prior art. In the figure, reference numerals
2
and
3
denote a DC input and a switching converter (or a DC/DC converter) respectively. Reference numeral
31
denotes a main switch device, reference numeral
32
denotes a transformer and reference numeral
33
denotes a rectifying/smoothing circuit provided on the secondary side of the transformer
32
. Reference numerals
34
and
4
denotes a diode and a DC output voltage respectively. Reference numeral
5
denotes a voltage-detecting unit for detecting the DC output voltage
4
. Reference numeral
6
denotes a current-detecting unit for detecting an output current and reference numeral
7
denotes a voltage-stabilization control unit. Reference numerals
8
and
9
denote a photocoupler and a switching control unit respectively.
As shown in
FIG. 12
, the voltage-detecting unit
5
, the current-detecting unit
6
and the voltage-stabilization control unit
7
are provided on the output-potential side of the switching converter
3
. A control signal generated by the voltage-stabilization control unit
7
is supplied to the switching control unit
9
provided on the input-potential side of the switching converter
3
by way of the photocoupler
8
. The switching control unit
9
controls the main switch device
31
by using the control signal supplied through the photocoupler
8
serving as an isolator. The switching control unit
9
controls the main switch device
31
to adjust the DC output voltage
4
of the switching converter
3
and, hence, the load borne thereby.
In the direct-current power-supply apparatus shown in
FIG. 12
, the propagation speed of the control signal is determined by the propagation speed of the isolation means such as the photocoupler
8
. Thus, the control signal cannot be transmitted at a high speed, resulting in a poor response characteristic of the direct-current power-supply apparatus. Furthermore, in order to improve the efficiency of the switching converter
3
, the direct-current power-supply apparatus employs a synchronous-rectification circuit and/or a reverse-current-blocking switch to live or not to live a line. In this case, it is necessary to provide a circuit for controlling the synchronous-rectification circuit and/or the reverse-current-blocking switch. Since such a control circuit operates with a reference electric potential supplied by way of a signal-isolating means as a separate electric potential, however, improvement of the response characteristic of the direct-current power-supply apparatus cannot be expected. In addition, since there is also required a multi-function control circuit operating with a reference electric potential supplied as a separate electric potential, reduction of the size and the cost of the direct-current power-supply apparatus cannot be expected either.
SUMMARY OF THE INVENTION
A direct-current power-supply apparatus provided by the present invention comprises a switching converter for converting an input direct-current power into another direct-current power, a control circuit and an isolation means. The switching converter has a main switch device for generating a pulse voltage from the direct-current input, a synchronous-rectification circuit on the output side of the switching converter and a reverse-current-blocking switch. On the other hand, the control circuit employed in the direct-current power-supply apparatus comprises a PWM formation unit, a synchronous-rectification control unit and a driving control unit. The PWM formation unit is a unit for driving the main switch device. The synchronous-rectification control unit is a unit for controlling an operation to drive the synchronous-rectification circuit. The driving control unit is a unit for controlling an operation to drive the reverse-current-blocking switch. The control circuit operates by using an electric potential appearing on the output side of the switching converter as a reference electric potential.
The direct-current power-supply apparatus provided by the present invention applies a driving signal to the main switch device through the isolation means. The direct-current power-supply apparatus provided by the present invention is capable of executing control without exchanging the signal for driving the main switch device and a signal isolated between control devices including a switch for synchronous rectification.
REFERENCES:
patent: 5528480 (1996-06-01), Kikinis et al.
patent: 6184660 (2001-02-01), Hatular
Hayashi Katsunori
Onaka Takeshi
Onda Kenichi
Saga Ryohei
Takahashi Tadashi
Hitachi , Ltd.
Hogan & Hartson LLP
Patel Rajnikant B.
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