TW201931747A - A charge and discharge balance converter for UPS - Google Patents

Abstract

The present invention provides a charge and discharge balance converter for an UPS, which comprises a positive DC bus, a negative DC bus, a first capacitor and a second capacitor, wherein the charge and discharge balance converter comprises a first switching tube with an anti-parallel diode and a second switching tube with an anti-parallel diode, which are connected successively between the positive DC bus and negative DC bus and are connected to form a node; a first switch, a controllable unidirectional conductive device and an inductor, one terminal of which is connected to the node, and the other terminal of which is connected to the positive DC bus successively via the first switch and the controllable unidirectional conductive device; and a second switch connected between the other terminal of the inductor and an intermediate node formed by connecting the first capacitor and the second capacitor. The charge and discharge balance converter of the present invention has the advantages of fewer parts, smaller size and lower cost.

Description

Charge and discharge balance converter for uninterruptible power supply

The present invention relates to electronic circuits, and more particularly to a charge and discharge balancing converter for an uninterruptible power supply.

Uninterruptible power supplies are able to continuously power the load and have been widely used in various fields.

1 is a block diagram of a prior art uninterruptible power supply. As shown in FIG. 1, the bypass input terminal Bin is connected to the AC output terminal ACout through the static transfer switch 11, and the mains input terminal ACin is sequentially connected to the AC output terminal ACout through the rectified boost converter 12 and the inverter 13, the rechargeable battery The 14 is coupled to the positive DC bus 171 and the negative DC bus 172 by a DC/DC converter 15 that is capable of charging the rechargeable battery 14 with electrical energy on the positive DC bus 171 and the negative DC bus 172. The uninterruptible power supply 1 further includes a balancing circuit 18 connected between the positive DC bus 171 and the negative DC bus 172. When the DC/DC converter is in operation, the balancing circuit 18 is used to balance the positive DC bus 171 and the negative DC bus. The voltage at 172 is such that the voltage value on the positive DC bus 171 is equal to the absolute value of the voltage on the negative DC bus 172.

For a high-power uninterruptible power supply, the DC/DC converter 15 and the charger 16 are bulky and costly. If the DC/DC converter 15 and the charger 16 are removed from the uninterruptible power supply 1 to reduce their size and cost, the rechargeable battery 14 is directly connected to the positive DC bus 171 and the negative DC bus 172. between. Since there is no isolation of the DC/DC converter 15, in order to reduce the charging chopping current and the chopping voltage, it is necessary to connect a large number of capacitors between the positive DC bus 171 and the negative DC bus 172, even in the rechargeable battery 14. A filter inductor is connected to the positive and negative electrodes. This in turn increases the cost and size of the uninterruptible power supply 1.

In view of the above technical problems existing in the prior art, embodiments of the present invention provide a charge and discharge balance converter for an uninterruptible power supply, including a positive DC bus, a negative DC bus, and a connection. a first capacitor and a second capacitor between the positive DC bus and the negative DC bus, wherein the charge and discharge balance converter comprises: a first switch having a reverse parallel diode and two having an antiparallel a second switch of the pole body, the first switch and the second switch are sequentially connected between the positive DC bus and the negative DC bus and connected to form a node; an inductor, a first switch and a controllable unidirectional conductive device, One end of the inductor is connected to the node, the other end of the inductor is sequentially connected to the positive DC bus through the first switch and the controllable unidirectional conductive device; and the second switch, the second A switch is connected between the other end of the inductor and the intermediate node formed by the connection of the first capacitor and the second capacitor.

Preferably, the controllable unidirectional conductive device is a thyristor.

Preferably, the controllable unidirectional conductive device is a third switch and a diode in series.

Preferably, the controllable unidirectional conductive device comprises: a diode having an anode connected to the first switch and a cathode connected to the positive DC bus; a fourth switch having one end connected to the diode The other end of the body is connected to the positive terminal of the rechargeable battery in the uninterruptible power supply.

Preferably, a control device is further included for controlling an on state of the first switch, the second switch, and the controllable unidirectional conductive device, and controlling an operation mode of the first switch and the second switch.

Preferably, the control device is used to control the voltage between the positive DC bus and the negative DC bus from zero to no higher than the voltage of the rechargeable battery of the uninterruptible power supply. The first switch, the second switch and the controllable unidirectional conductive device are disconnected, and the first switch and the second switch are controlled to be in an off state; and when a voltage rises between the positive DC bus and the negative DC bus The control device is configured to control the controllable unidirectional conductive device to be in an on state when subjected to a forward voltage when the voltage of the rechargeable battery is higher than the voltage of the rechargeable battery.

Preferably, when the mains input of the uninterruptible power supply has a commercial power, the voltage of the rechargeable battery in the uninterruptible power supply is less than a predetermined voltage, and the positive DC bus and the negative DC bus When the voltage between the two is a target voltage, the control device is configured to: control the first switch to be turned on, the second switch to be turned off, and provide a pulse width modulation signal to the first switch, and control the second switch It is in the cutoff state.

Preferably, the control device is further configured to control the controllable unidirectional conductive device to be in an on state when subjected to a forward voltage.

Preferably, when the mains input of the uninterruptible power supply has a commercial power, the voltage of the rechargeable battery in the uninterruptible power supply reaches a predetermined voltage, and the positive DC bus and the negative DC bus When the voltage between the two is the target voltage, the control device is configured to: control one of the first switch and the second switch to be turned off, the other is turned on, and control the first switch and the second switch to be in an off state .

Preferably, the control device is further configured to control the controllable unidirectional conductive device to be in an on state when subjected to a forward voltage.

Preferably, the first switch is turned off and the second switch is turned on.

Preferably, when the mains input of the uninterruptible power supply has no mains, the control device is configured to: control the first switch to be turned off, the second switch to be turned on, and control the controllable one-way The conductive device is in an on state when subjected to a forward voltage, and provides the first switch and the second switch with a pulse width modulation signal having the same duty cycle, so that the first switch and the second switch are alternately turned on.

Preferably, after the mains input of the uninterruptible power supply is switched from having no mains to having mains, and when the voltage between the positive DC bus and the negative DC bus is higher than the uninterruptible power supply When the voltage of the rechargeable battery of the supplier is supplied, the control device is configured to: control the first switch to be turned on, the second switch to be turned off, and provide a pulse width modulation signal to the first switch, and control the second The switch is in the off state.

The charge-discharge balance converter of the present invention has a small number of components, a small volume, and a low cost, and it is not necessary to connect a large capacitor between the positive and negative DC bus bars to suppress the chopping current and the chopping voltage.

The present invention will be further described in detail below with reference to the accompanying drawings.

2 is a circuit diagram of a charge and discharge balance converter for an uninterruptible power supply according to a first embodiment of the present invention. As shown in FIG. 2, the charge and discharge balun 20 includes an insulated gate bipolar transistor (IGBT) T1 having an antiparallel diode D1, an IGBT T2 having an antiparallel diode D2, and an inductor L. The first switch S1, the second switch S2, and the thyristor SCR. The IGBT T1 and the IGBT T2 are sequentially connected between the positive DC bus 271 and the negative DC bus 272, and the IGBT T1 and the IGBT T2 are connected to form a node N. One end of the inductor L is connected to the node N, and the other end thereof is connected to the positive DC bus 271 through the first switch S1 and the thyristor SCR in turn, and the other end thereof is further connected to the capacitor C1 and the capacitor C2 through the second switch S2. On the middle node. In addition, the negative electrode of the rechargeable battery B is connected to the negative DC bus 272, and the positive electrode thereof is connected to the positive DC bus 271 through the thyristor SCR.

At the initial stage of the mains supply of the mains input terminal ACin, the voltage between the positive and negative DC bus bars 271, 272 is zero, and is less than the voltage of the rechargeable battery B, and the control thyristor SCR is in the off state (ie, no The gate of the thyristor SCR is supplied with a voltage), the first switch S1 and the second switch S2 are controlled to be turned off, and the IGBT T1 and the IGBT T2 are controlled to be in an off state. The commercial power charges the capacitor C1 and the capacitor C2 between the positive and negative DC bus bars 271 and 272 through the rectified boost converter 22, so that the voltage between the positive and negative DC bus bars 271 and 272 gradually rises to the peak and valley of the commercial power. The voltage difference is completed and the precharge process is completed. The rectified boost converter 22 is then controlled to operate such that the voltage between the positive and negative DC bus bars 271, 272 continues to rise, wherein the voltage between the positive and negative DC bus bars 271, 272 rises above the rechargeable battery B. At voltage, a voltage is applied to the gate of the thyristor SCR, which ultimately causes the voltage between the positive and negative DC busses 271, 272 to rise to a target voltage, wherein the target voltage is higher than the voltage of the rechargeable battery B. The inverter 23 is then controlled to operate to output the desired alternating current.

The operation of the charge and discharge balance converter 20 will be described below with reference to FIGS. 3 to 5.

After the voltage between the positive and negative DC bus bars 271, 272 is boosted to the target voltage, the rechargeable battery B can be charged by controlling the charge and discharge balance converter 20 to be in the charging mode. 3 is an equivalent circuit diagram of the charge and discharge balance converter shown in FIG. 2 in a charging mode. As shown in FIG. 3, the control device 200 controls the first switch S1 to be turned on, the second switch S2 to be turned off, supplies a voltage to the gate of the thyristor SCR, provides a pulse width modulation signal to the IGBT T1, and controls the IGBT T2 to be in an off state. At this time, the IGBT T1, the inductor L and the diode D2 constitute a buck converter (or Buck circuit). The Buck circuit uses the power on capacitor C1 and capacitor C2 to depressurize rechargeable battery B. In the charging mode, the control mode of the rectification boost converter 22 and the control mode of the Buck circuit are independent of each other. Therefore, the existing control method can be used to control the operation of the Buck circuit to perform step-down charging of the rechargeable battery B. Increase the complexity of the control method.

In the charging mode, since the IGBT T1 is supplied with a high-frequency (for example, several tens of kilohertz) pulse width modulation signal, the inductor L can suppress the high-frequency chopping voltage and the chopping current very well, without being positive or negative. A large number of capacitors are connected between the DC bus bars 271 and 272.

If the voltage of the rechargeable battery B reaches a predetermined voltage and then stops charging, the charge/discharge balance converter is controlled to be in the sleep mode. 4 is an equivalent circuit diagram of the charge and discharge balance converter shown in FIG. 2 in a sleep mode. As shown in FIG. 4, the control device 200 controls the first switch S1 to be turned off, the second switch S2 to be turned on, to supply a voltage to the gate of the thyristor SCR, and to control the IGBT T1 and the IGBT T2 to be in an off state. Since the voltage on the positive DC bus 271 is greater than the voltage of the rechargeable battery B, the thyristor SCR is subjected to the reverse anode voltage, so that it is in the reverse blocking state, at which time the rechargeable battery B is neither charged nor discharged. .

In other embodiments of the present invention, the control device 200 may also control the first switch S1 to be turned on and the second switch S2 to be turned off.

FIG. 5 is an equivalent circuit diagram of the charge and discharge balance converter shown in FIG. 2 in a battery discharge mode. As shown in FIG. 5, the control device 200 controls the first switch S1 to be turned off, the second switch S2 to be turned on, and the thyristor SCR to be turned on (ie, to supply a voltage to the gate of the thyristor SCR), at which time the rechargeable battery B passes through the turned-on gate. The fluid SCR is connected between the positive and negative DC bus bars 271, 272 for supplying power to the capacitor C1 and the capacitor C2, wherein the voltage across the rechargeable battery B is higher than the voltage difference between the peak and the valley of the output voltage of the inverter 23. . At this time, the IGBT T1, the IGBT T2, the inductor L, and the turned-on second switch S2 constitute a balancing circuit. The IGBT T1 and the IGBT T2 are supplied with the same pulse width modulation signal of the duty cycle, and the IGBT T1 and the IGBT T2 are alternately turned on, thereby balancing the voltages on the positive DC bus 271 and the negative DC bus 272.

When the mains input terminal ACin is switched from having no mains to having mains, the rectification boost converter 22 is controlled to operate to increase the voltage between the positive and negative DC bus bars 271 and 272 to be higher than the voltage of the rechargeable battery B. . Then, the first switch S1 is controlled to be turned on, the second switch S2 is turned off, the pulse width modulation signal is supplied to the IGBT T1, and the IGBT T2 is controlled to be in an off state, thereby performing step-down charging of the rechargeable battery B.

In the charging mode and the sleep mode, the gate of the thyristor SCR is supplied with a voltage to be in a conducting state when subjected to the forward voltage. The advantage is that when the mains input terminal ACin fails, the thyristor SCR is subjected to the forward anode voltage. Immediately in the on state, the rechargeable battery B can immediately supply power to the capacitors C1 and C2 through the turned-on thyristor SCR, and the present invention avoids the delay caused by the detection compared to the detection of the mains abnormality.

The advantage of controlling the conduction of the second switch S2 in the sleep mode is that the IGBT T1, the IGBT T2, the inductor L and the turned-on second switch S2 have formed a balancing circuit that can be prepared for balancing in the discharge mode at any time. The voltages on the positive DC bus 271 and the negative DC bus 272 avoid the delay of the closing action of the second switch S2 when the discharge mode is activated.

With the charge and discharge balance converter 20 of the present embodiment, the uninterruptible power supply can eliminate the bulky and expensive DC/DC converter 15 and the charger 16.

In addition, the Buck circuit formed by the IGBT T1, the inductor L, and the diode D2 in the balancing circuit can perform step-down charging of the rechargeable battery B in the charging mode. By multiplexing the IGBT T1, the inductor L, and the diode D2, the charge and discharge balance converter 20 has fewer components, is small in size, and is low in cost.

Figure 6 is a circuit diagram of a charge and discharge balun for an uninterruptible power supply in accordance with a second embodiment of the present invention. As shown in FIG. 6, the charge-discharge balance converter 30 is basically the same as the charge-discharge balance converter 20 shown in FIG. 2, except that the controllable unidirectional conductive device composed of the third switch S3 and the diode D3 connected in series is used. Replace the thyristor SCR. Wherein during the pre-charging process, the third switch S3 is controlled to be turned off; in the charging mode, the sleep mode, and the discharging mode, the third switch S3 is controlled to be turned on.

Figure 7 is a circuit diagram of a charge and discharge balun for an uninterruptible power supply in accordance with a third embodiment of the present invention. As shown in FIG. 7, the charge-discharge balance converter 40 is basically the same as the charge-discharge balance converter 30 shown in FIG. 6, except that the fourth switch S4 is connected to the anode of the diode D4 and the anode of the rechargeable battery B. The cathode of the diode D4 is connected to the positive DC bus 471. The control mode of the fourth switch S4 is completely the same as that of the third switch S3, and details are not described herein again.

In other embodiments of the invention, a metal oxide semiconductor field effect transistor is used in place of the IGBT of the above embodiment.

While the present invention has been described in its preferred embodiments, the invention is not limited to the embodiments described herein, and the various changes and modifications may be made without departing from the scope of the invention.

1‧‧‧Uninterruptible power supply

11‧‧‧Static transfer switch

12‧‧‧Rectified Boost Converter

13‧‧‧Inverter

14‧‧‧Rechargeable battery

15‧‧‧DC/DC converter

16‧‧‧Charger

18‧‧‧Balance circuit

20‧‧‧Charge and discharge balance converter

22‧‧‧Rectified Boost Converter

23‧‧‧Inverter

30‧‧‧Charge and discharge balance converter

40‧‧‧Charge and discharge balance converter

171‧‧‧正 DC bus

172‧‧‧Negative DC bus

200‧‧‧Control device

271‧‧‧正 DC bus

272‧‧‧Negative DC bus

471‧‧‧正 DC bus

ACin‧‧ City power input

ACout‧‧‧AC output

B‧‧‧Rechargeable battery

Bin‧‧‧bypass input

C1‧‧‧ capacitor

C2‧‧‧ capacitor

D1‧‧‧ diode

D2‧‧‧ diode

L‧‧‧Inductors

N‧‧‧ node

S1‧‧‧ first switch

S2‧‧‧ second switch

S3‧‧‧ third switch

S4‧‧‧fourth switch

SCR‧‧‧ brake fluid

T1‧‧‧ insulated gate bipolar transistor (IGBT)

T2‧‧‧ insulated gate bipolar transistor (IGBT)

The embodiments of the present invention are further described below with reference to the accompanying drawings, in which: [FIG. 1] is a block diagram of a prior art uninterruptible power supply. Fig. 2 is a circuit diagram of a charge and discharge balance converter for an uninterruptible power supply according to a first embodiment of the present invention. FIG. 3 is an equivalent circuit diagram of the charge and discharge balance converter shown in FIG. 2 in a charging mode. FIG. FIG. 4 is an equivalent circuit diagram of the charge and discharge balance converter shown in FIG. 2 in a sleep mode. FIG. FIG. 5 is an equivalent circuit diagram of the charge and discharge balance converter shown in FIG. 2 in a discharge mode. Fig. 6 is a circuit diagram of a charge and discharge balance converter for an uninterruptible power supply according to a second embodiment of the present invention. Fig. 7 is a charge and discharge balance converter for an uninterruptible power supply according to a third embodiment of the present invention.

Claims (13)

A charge and discharge balance converter for an uninterruptible power supply, the uninterruptible power supply comprising a positive DC bus, a negative DC bus, and a first capacitor connected between the positive DC bus and the negative DC bus And a second capacitor, wherein the charge and discharge balance converter comprises: a first switch having an antiparallel diode and a second switch having an antiparallel diode, the first switch and the second switch Connected between the positive DC bus and the negative DC bus in turn and connected to form a node; an inductor, a first switch and a controllable unidirectional conductive device, one end of the inductor being connected to the node, the inductor The other end of the inductor is connected to the positive DC bus through the first switch and the controllable unidirectional conductive device; and the second switch is connected to the other end of the inductor and the first capacitor Between the intermediate nodes formed by the connection with the second capacitor. A charge-discharge balance converter for an uninterruptible power supply of claim 1, wherein the controllable unidirectional conductive device is a thyristor. A charge-discharge balance converter for an uninterruptible power supply according to claim 1, wherein the controllable unidirectional conductive means is a third switch and a diode in series. The charge-discharge balance converter for an uninterruptible power supply of claim 1, wherein the controllable unidirectional conductive device comprises: a diode having an anode connected to the first switch and a cathode connected thereto The positive DC bus; the fourth switch has one end connected to the anode of the diode and the other end connected to the positive pole of the rechargeable battery in the uninterruptible power supply. A charge and discharge balance converter for an uninterruptible power supply according to any one of claims 1 to 4, further comprising control means for controlling said first switch, said second switch, and Controlling a conduction state of the unidirectional conductive device and controlling an operation mode of the first switch and the second switch. A charge/discharge balance converter for an uninterruptible power supply according to claim 5, wherein a voltage between said positive DC bus and a negative DC bus rises from zero to not higher than said uninterruptible power supply During the voltage of the rechargeable battery of the supplier, the control device is configured to control the first switch, the second switch and the controllable unidirectional conductive device to be disconnected, and control the first switch and the second switch to be cut off a state; and when the voltage between the positive DC bus and the negative DC bus rises above a voltage of the rechargeable battery, the control device is configured to control the controllable unidirectional conductive device to be positive It is in the on state when the voltage is applied. The charge/discharge balance converter for an uninterruptible power supply of claim 5, wherein when the mains input of the uninterruptible power supply has a commercial power, the rechargeable power supply is rechargeable When the voltage of the battery is less than a predetermined voltage, and the voltage between the positive DC bus and the negative DC bus is the target voltage, the control device is configured to: control the first switch to be turned on, the second switch to be turned off, and give The first switch provides a pulse width modulation signal, and controls the second switch to be in an off state. The charge/discharge balance converter for an uninterruptible power supply of claim 7, wherein the control device is further configured to control the controllable unidirectional conductive device to be in an on state when subjected to a forward voltage. The charge/discharge balance converter for an uninterruptible power supply of claim 5, wherein when the mains input of the uninterruptible power supply has a commercial power, the rechargeable power supply is rechargeable When the voltage of the battery reaches a predetermined voltage, and the voltage between the positive DC bus and the negative DC bus is the target voltage, the control device is configured to: control one of the first switch and the second switch to be disconnected, The other is turned on, and the first switch and the second switch are controlled to be in an off state. The charge/discharge balance converter for an uninterruptible power supply of claim 9, wherein the control device is further configured to control the controllable unidirectional conductive device to be in an on state when subjected to a forward voltage. A charge-discharge balance converter for an uninterruptible power supply according to claim 9, wherein the first switch is turned off and the second switch is turned on. The charge/discharge balance converter for an uninterruptible power supply of claim 5, wherein when the mains input of the uninterruptible power supply does not have a mains supply, the control device is configured to: control the The first switch is turned off, the second switch is turned on, the controllable unidirectional conductive device is controlled to be in a conducting state when subjected to a forward voltage, and the first switch and the second switch are provided with the same pulse width of the duty cycle The signal is modulated such that the first switch and the second switch are alternately turned on. The charge/discharge balance converter for an uninterruptible power supply of claim 5, wherein after the mains input of the uninterruptible power supply is switched from having no mains to having mains, and when the integrity When the voltage between the bus bar and the negative DC bus is higher than the voltage of the rechargeable battery of the uninterruptible power supply, the control device is configured to: control the first switch to be turned on, the second switch to be turned off, and Providing a pulse width modulation signal to the first switch, and controlling the second switch to be in an off state.