Power supply device for charge/discharge device, and charge/discharge device

• US 8,072,188 B2
• Filed: 09/22/2008
• Issued: 12/06/2011
• Est. Priority Date: 03/19/2008
• Status: Active Grant

• Current Assignee: Sansha Electric Manufacturing Company Limited
• Original Assignee: Sansha Electric Manufacturing Company Limited
• Inventors: Okamoto, Shigeru, Katsushima, Hajime, Yorinobu, Masanori
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): Omar, Ahmed
• Application Number:
  US12/234,762
• Publication Number:
  US 20090237028A1
• Time in Patent Office: 1,170 Days
• Field of Search: 320/141, 320/139
• US Class Current: 320/141
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence

Abstract

This power supply device includes a series circuit of a first switching element and a second switching element connected in parallel with a DC power supply unit, and a smoothing filter circuit which includes a series circuit of an inductor and a smoothing capacitor connected in parallel with the second switching element. The power supply device also includes a control unit and a drive circuit for generating first and second PWM pulses by respectively driving the first and second switching elements ON and OFF, and for creating a dead time between those switching pulse signals. And this control unit changes the frequency of the switching pulse signal according to the pulse width of either the first PWM pulses or the second PWM pulses.

Claims

1. A power supply device, comprising:

a series circuit of a first switching element and a second switching element, connected in parallel with a DC power supply unit;

a smoothing filter circuit comprising a series circuit of an inductor and a smoothing capacitor, connected in parallel with said second switching element;

output terminals which are connected to the two sides of said smoothing capacitor;

a control unit which outputs a switching pulse signal, and controls the duty ratio thereof; and

a drive circuit which, based upon said switching pulse signal, generates first PWM pulses and second PWM pulses for turning said first switching element and said second switching element alternatingly ON and OFF respectively, and which moreover creates a dead time between these PWM pulses;

and wherein said control unit changes the frequency of said switching pulse signal corresponding to the pulse width of either said first PWM pulses or said second PWM pulses.

2. A power supply device according to claim 1, wherein said control unit reduces the frequency of said switching pulse signal corresponding to shortening of the pulse width of either said first PWM pulses or said second PWM pulses.

3. A power supply device according to claim 1, wherein said control unit reduces the frequency of said switching pulse signal when the pulse width of either said first PWM pulses or said second PWM pulses becomes less than or equal to a fixed pulse width.

4. A power supply device according to claim 1, wherein said drive circuit comprises a CR time constant circuit which takes the edge off of said switching pulse signal, and said dead time is created by waveform shaping the output of said CR time constant circuit.

5. A power supply device according to claim 4, wherein:

said drive circuit comprises a first drive circuit which generates said first PWM pulses and a second drive circuit which generates said second PWM pulses;

said first drive circuit comprises a first CR time constant circuit which takes the edge off said switching pulse signal;

said second drive circuit comprises a second CR time constant circuit which takes the edge off said switching pulse signal; and

the respective time constants of said first CR time constant circuit and said second CR time constant circuit are different.

6. A power supply device according to claim 1, further comprising an output current detection unit which detects output current, and wherein said control unit controls the duty ratio of said switching pulse signal so that the output current detected by said output current detection unit is constant.

7. A power supply device according to claim 6, wherein:

said output terminals are connected to a secondary battery;

said control unit can set a charge mode in which a charging current is flowed to said secondary battery, and a discharge mode in which a discharge current is flowed out from said secondary battery; and

during said charge mode, the duty ratio of said switching pulse signal is controlled so that the pulse width of said first PWM pulses becomes greater than the pulse width of said second PWM pulses, and, during said discharge mode, the duty ratio of said switching pulse signal is controlled so that the pulse width of said second PWM pulses becomes greater than the pulse width of said first PWM pulses.

8. A power supply device according to claim 7, wherein said control unit controls the duty ratio of said switching pulse signal in correspondence to the battery voltage of said secondary battery.

9. A charge/discharge device, comprising:

a series circuit of a first switching element and a second switching element, connected in parallel with a DC power supply unit;

a smoothing filter circuit comprising a series circuit of an inductor and a smoothing capacitor, connected in parallel with said second switching element;

output terminals which are connected to the two sides of said smoothing capacitor, and to which a second battery which is to be charged and discharged for testing is connected;

a control unit which outputs a switching pulse signal, and which controls the duty ratio thereof; and

a drive circuit which, based upon said switching pulse signal, generates first PWM pulses and second PWM pulses for turning said first switching element and said second switching element alternatingly ON and OFF respectively, and which moreover creates a dead time between these PWM pulses;

and wherein, during discharge of said secondary battery, said control unit lowers the frequency of said switching pulse signal corresponding to the OFF width, at which said second switching element is turned OFF by said second PWM pulses, becoming shorter.

10. A charge/discharge device according to claim 9, wherein said drive circuit comprises a CR time constant circuit which takes the edge off of said switching pulse signal, and said dead time is created by waveform shaping the output of said CR time constant circuit.

11. A charge/discharge device according to claim 10, wherein:

said drive circuit comprises a first drive circuit which generates said first PWM pulses and a second drive circuit which generates said second PWM pulses;

said first drive circuit comprises a first CR time constant circuit which takes the edge off of said switching pulse signal;

said second drive circuit comprises a second CR time constant circuit which takes the edge off of said switching pulse signal; and

the respective time constants of said first CR time constant circuit and said second CR time constant circuit are different.

12. A charge/discharge device according to claim 9, further comprising an output current detection unit which detects output current, and wherein said control unit controls the duty ratio of said switching pulse signal so that the output current detected by said output current detection unit is constant.

13. A charge/discharge device according to claim 12, wherein said control unit controls the duty ratio of said switching pulse signal in correspondence to the battery voltage of said secondary battery.

14. A charge/discharge device, comprising:

a series circuit of a first switching element and a second switching element, connected in parallel with a DC power supply unit;

a smoothing filter circuit comprising a series circuit of an inductor and a smoothing capacitor, connected in parallel with said second switching element;

output terminals which are connected to the two sides of said smoothing capacitor, and to which a second battery which is to be charged and discharged for testing is connected;

a control unit which outputs a switching pulse signal, and which controls the duty ratio thereof; and

a drive circuit which, based upon said switching pulse signal, generates first PWM pulses and second PWM pulses for turning said first switching element and said second switching element alternatingly ON and OFF respectively, and which moreover creates a dead time between these PWM pulses;

and wherein, during discharge of said secondary battery, said control unit lowers the frequency of said switching pulse signal when the OFF width at which said second switching element is turned OFF by said second PWM pulses shortens to less than or equal to a fixed pulse width.

15. A charge/discharge device according to claim 14, wherein said drive circuit comprises a CR time constant circuit which takes the edge off of said switching pulse signal, and said dead time is created by waveform shaping the output of said CR time constant circuit.

16. A charge/discharge device according to claim 15, wherein:

said drive circuit comprises a first drive circuit which generates said first PWM pulses and a second drive circuit which generates said second PWM pulses;

said first drive circuit comprises a first CR time constant circuit which takes the edge off of said switching pulse signal;

said second drive circuit comprises a second CR time constant circuit which takes the edge off of said switching pulse signal; and

the respective time constants of said first CR time constant circuit and said second CR time constant circuit are different.

17. A charge/discharge device according to claim 14, further comprising an output current detection unit which detects output current, and wherein said control unit controls the duty ratio of said switching pulse signal so that the output current detected by said output current detection unit is constant.

18. A charge/discharge device according to claim 17, wherein said control unit controls the duty ratio of said switching pulse signal according to the battery voltage of said secondary battery.