Section 3: Control Power Supplies

Chapter 1 - Control Power Generation & Distribution

1.1 Control power generation ......................................................................... 3-11.1.1 AC-DC Power Supply Board ....................................................... 3-21.1.2 DC-DC Power Supply Board ....................................................... 3-2

1.2 Control power distribution ....................................................................... 3-2

Chapter 2 - AC-DC Power Supply

2.1 Chapter overview ..................................................................................... 3-5

2.2 General description ................................................................................... 3-52.2.1 Circuit board functions ................................................................ 3-52.2.2 Input/output connections .............................................................. 3-5

2.3 Circuit description .................................................................................... 3-5

2.4 Calibration details ..................................................................................... 3-6

Chapter 3 - DC-DC Power Supply

3.1 Chapter overview ..................................................................................... 3-7

3.2 General description ................................................................................... 3-73.2.1 Circuit board functions ................................................................ 3-73.2.2 Input/Output connections ............................................................. 3-7

3.3 Circuit description .................................................................................... 3-83.3.1 Introduction .................................................................................. 3-83.3.2 Series chopper and filter .............................................................. 3-83.3.3 Inverter and transformer sections ................................................. 3-93.3.4 Fault detection ............................................................................ 3-103.3.5 Indications .................................................................................. 3-10

3.4 Calibration details ................................................................................... 3-10S-3.FM5 - Issue 2 Dated 21/08/97 i

SECTION 3 - Control Power Supplies 7200 Series UPS Service Manualii S-3.FM5 - Issue 2 Dated 21/08/97

Section 3:

Chapter 1 - Control Power Generation & Distribution

1.1 Control power generation

Two Power Supply Boards are fitted to the 7200 series UPS module; the AC-DCPower Supply Board and the DC-DC Power Supply Board as illustrated inFigure 3-1 below.

Figure 3-1: Control Power primary supply

Q1

F11

F10 L1

T2

F8 F9

F6

Q2

F4 F5

F7

T3

F12

BypassSupply

InputMainsSupply

STATICSWITCH

RECTIFIER INVERTER

AC-DC PowerSupply Board

DC-DC PowerSupply Board

RectifierLogic Board

InverterLogic Board

From T3

Split

byp

ass

links

12Vdc

12Vdc Supplies to all other circuit boards

12Vdcs3-c1.fm5 - Issue 2 Dated 21/08/97 3-1

SECTION 3 - Control Power Supplies 7200 Series UPS Service ManualCHAPTER 1 - Control Power Generation & Distribution1.1.1 AC-DC Power Supply Board

The AC-DC Power Supply Board, which is described in detail in Chapter 2, is fedfrom both the input mains and bypass supplies via transformers T2 and T3 respec-tively, and is live when either of these two power sources are available (note thatthe split-bypass links are removed if a separate bypass supply is used).

This board produces 12V and 0V outputs which are directly connected to theRectifier Logic Board; and from this board these power rails are also connectedto the remainder of the control circuit boards (except the Inverter Logic Board) asdescribed in paragraph 1.2) .

Transformers T2 and T3 are identical and have tapped primary windings to caterfor a range of mains supply voltages. The taps used are A1/B (415V); A2/B(400V); A2/B (380V). The primary fuses (e.g. F6/F7 and F8/F9) are fitted inganged fuse-holders which also serves as an isolation switch to allow the trans-formers to be replaced without having to shut-down the entire UPS.

1.1.2 DC-DC Power Supply Board

The DC-DC Power Supply Board, which is described in detail in Chapter 3, is fedfrom the DC Busbar and is live whenever the rectifier is operative or the batterycircuit breaker is closed. The board therefore has to operate over a wide range ofinput voltages varying between the battery boost voltage to the battery undervolt-age trip level (approximately 240V to 700V).

This board produces 12V and 0V outputs which are connected to the InverterLogic Board; and from this board these power rails are also connected to the re-mainder of the control circuit boards.

The boards input fuses (F5/F5) are fitted in ganged fuse-holders which alsoserves as an isolation switch to allow the board to be replaced without having toshut-down the entire UPS. (Note: As the Inverter Logic Board is powered onlyfrom the DC-DC Power Supply, the inverter will shut-down and the load transferto bypass if these fuses are opened.)

1.2 Control power distribution

The 12V supply rails on the Rectifier Logic Board and Inverter Logic Board,from the AC-DC Power Board and DC-DC Power Board respectively, are con-nected together on the UPS Logic Board and distributed to the remaining controlboards as illustrated in Figure 1.2.

Note that the power rails on the Inverter Logic Board are isolated by blockingdiodes from the UPS Logic Board supply rails. This means that the Inverter LogicBoard is powered only by the DC-DC Power Supply Board, and loses its operat-ing power when this supply is not available i.e. without the DC Input (from theDC Bus) the inverter cannot operate. The remaining circuit boards, including theRectifier Logic Board, are powered when either the AC-DC or DC-DC PowerSupply Boards are active.

Most of the boards also require other stabilised voltages, such as +5V, for theircorrect operation. Where such voltages are required they are developed individu-ally on the board in question by appropriate voltage regulators. The exception tothis is the Operator Control Panel, which obtains its regulated +5V power from anisolated dc-dc converter circuit on the Operator Logic Board.3-2 s3-c1.fm5 - Issue 2 Dated 21/08/97

7200 Series UPS Service Manual SECTION 3 - Control Power SuppliesCHAPTER 1 - Control Power Generation & DistributionFigure 3-2: Control Power Supplies Distribution

3 4 5

5-8 1-4 9-12

5-8 1-4 9-12

345

5-81-49-12

5-81-49-12

+12V

0V

-12V

+12V

0V

-12V

+12V

0V

-12V

+12V -12V0V

5-8 1-4 9-12

5-8 1-4 9-12

+12V -12V0V

5-8 1-4 9-12

5-8 1-4 9-12

+12V -12V

1 3

1 3

30-31 4

30-31 4

1-4 5-8

1-4 5-8

0V +12V

0V +5V

RectifierLogicBoard

InverterLogicBoard

High VoltageInterface Board

UPS Logic Board

Static SwitchDriver Board

Operator LogicBoard

I/O InterfaceBoard

(Remote Options)

Operator ControlPanel

12V inputs fromAC-DC Power Supply

12V inputs fromDC-DC Power Supply

V45 V46

V15 V14

X2

X1

X4

X3

X2 X4X5 X8

X1 X9

X13 X1s3-c1.fm5 - Issue 2 Dated 21/08/97 3-3

SECTION 3 - Control Power Supplies 7200 Series UPS Service ManualCHAPTER 1 - Control Power Generation & Distribution3-4 s3-c1.fm5 - Issue 2 Dated 21/08/97

Section 3:

Chapter 2 - AC-DC Power Supply

2.1 Chapter overview

This chapter describes the AC-DC Power Supply Board and should be read inconjunction with circuit diagram SE-4503030-M.

2.2 General description

2.2.1 Circuit board functions

This board is responsible for providing the UPS control logic circuits, with the ex-ception of the Inverter Logic Board and Inverter Driver Interface Board, withtheir 12V low voltage operating power supplies. The board is itself poweredfrom two supply sources; the first is derived from the UPS input mains supply andthe second is from the bypass mains supply. This means that the board is activewhen either of these two supplies is present - see chapter 1.

Note: in installations not configured with a split-bypass supply, the static bypasssupply and UPS input supply are fed from a common mains power source andboth supply sources to this board will fail in the event of an input mains failure.

2.2.2 Input/output connections

The AC-DC Power Supply board has three connectors, described below:

M1 carries the boards input supply derived from the UPS input mainssupply.

M2 carries the boards input supply derived from the bypass mains supply. CN1 carries the boards output low voltage supplies (12V) to the UPS

control circuit boards. These are initially connected to the Rectifier LogicBoard and from there to the UPS Logic Board where they are coupledwith the outputs from the DC-DC Power Supply, which is connected to theUPS Logic Board via the Inverter Logic Board.

2.3 Circuit description

This board contains two straight-forward 3-phase rectifiers whose outputs areconnected in parallel, one being fed via M1 and the other by M2.

The supply to M1 is obtained via transformer T2 and FS8-FS9 (1A), connected tothe S-T phases of the input mains supply and present a nominal 30Vac input (seethe power schematics description in Section 1 Chapter 2). The transformer prima-ry is tap-selectable to suit the system voltage (see paragraph 1.1.1 on page 3-2).

The supply to M2 is obtained via transformer T3 and FS6-FS7 (1A), connected tothe R-S phases of the bypass mains supply. This transformer is identical to T2,and tapped in the same way as described above.

Note: the transformer supply fuses are fitted to ganged fuse-holders which enablethem to be used as a two-pole isolation switch.

The AC-DC Power Supply Board circuit diagram shows that each input supplypasses through a full-wave bridge rectifier, providing an unregulated DC powerS3-C2.FM5 - Issue 2 Dated 21/08/97 3-5

SECTION 3 - Control Power Supplies 7200 Series UPS Service ManualCHAPTER 2 - AC-DC Power Supplysource smoothed by C1 and C2. Two 3-terminal regulators are used to convert thisraw supply into regulated 12Vdc outputs at CN1 pins 3, 4 and 5.

Leds LS1 (+12V) and LS2 (-12V) indicate the presence of the 12V outputs. Theseleds are turned on by transistor drivers and will begin to illuminate when thepower rails are greater than 10.5V (approximately).

2.4 Calibration details

This board is fully calibrated during the manufacturers bench testing procedureand should not require further adjustment when being fitted to the main equip-ment. The only adjustments are resistors TM1 and TM2, which are connected inthe voltage sense lines to the 3-terminal regulators and enable the output voltageto be trimmed.

Caution If you need to alter these potentiometers make all adjustments very slowly. Adjust TM2, the -12Vdc adjustment, first.

As the outputs from this board are effectively connected in parallel with the 12Voutputs from the DC-DC Power Supply, always ensure that the DC-DC PowerSupply is inoperative when adjusting the AC-DC Power Supply output voltages.This is achieved by opening the battery circuit breaker and turning off the rectifier.3-6 S3-C2.FM5 - Issue 2 Dated 21/08/97

Section 3:

Chapter 3 - DC-DC Power Supply

3.1 Chapter overview

This chapter describes the DC-DC Power Supply Board and should be read inconjunction with circuit diagram SE-4503028-K.

3.2 General description

3.2.1 Circuit board functions

This board is primarily responsible for providing the Inverter Logic Board and In-verter Driver Interface Boards with their 12V low voltage operating power sup-plies. It also provides a secondary power supply source for the remaining controllogic boards when the AC-DC Power Supply Board is inactive.

The DC-DC Power Supply Board is itself powered from the DC busbar, whichmeans that it is active at all times when the DC busbar is live: either via the recti-fier when the UPS input mains supply is healthy, or from the batteries in the eventof a mains failure.

3.2.2 Input/Output connections

The DC-DC Power Supply board has two connectors, described below:

The input power is connected via M1 (IDC Connector) and is at the nomi-nal DC busbar voltage.

The boards outputs at CN1 are connected to X5 on the Inverter LogicBoard.

CN1 pins 1 & 2 carry a 36Vac output which passes straight through the InverterLogic Board to the Inverter Driver Interface Board (to provide an internally iso-lated power supply for each inverter drive circuit).

CN1 pins 3, 4 and 5 carry the boards +12Vdc, 0V and -12Vdc outputs respec-tively. These are initially connected to the Inverter Logic Board and from there tothe UPS Logic Board where they are coupled with the 12V outputs from the AC-DC Power Supply, which is connected to the UPS Logic Board via the RectifierLogic Board.S3-C3.FM5 - Issue 2 Dated 21/08/97 3-7

SECTION 3 - Control Power Supplies 7200 Series UPS Service ManualCHAPTER 3 - DC-DC Power Supply3.3 Circuit description

3.3.1 Introduction

Figure 3-3: Block diagram

This board contains four major stages of operation:

1. A series-chopper circuit, working in conjunction with a filter, converts theboards input supply, from the DC busbar, into a Controlled DC supply rail. Note: The input supply is variable according to the battery voltage as itcharges and discharges i.e. over a working range of 240-700Vdc.

2. The Controlled (fixed) DC voltage is then converted into Controlled AC bymeans of a simple push-pull inverter circuit which has a transformer-coupledoutput stage for isolation.

3. The transformer provides two sets of outputs: one leaves the board as a lowvoltage ac supply (36Vac nominal) and is used to provide an isolated powersupply for the Inverter Base Driver Boards: the other is rectified to providethe general 12Vdc LV control power supplies.

Note: In the following description, the terms input voltage and output voltagerefer to the voltages entering and leaving the DC-DC power supply board and notthe UPS input and output voltages.

3.3.2 Series chopper and filter

Referring to the circuit diagram, the chopper section is designed around TR10,which is switched ON and OFF by a PWM signal produced by a purpose-de-signed integrated circuit (IC9). The PWM pattern produced by IC9 (and hence thecontrolled dc voltage) is determined by control inputs derived from the input volt-age, output voltage and output current, which are all monitored by error amplifierswithin IC9 whose outputs directly control its internal PWM pattern generator.

SeriesChopper

Push PullInverter

OutputTransformer

FixedRectifier

Filter

Soft Start

PWM Control Logic

1

3

M1

Bus +

Bus -

CN1

12

345

FaultDetection

LS1

LS3

LS2

36Vac

+15Vdc0V-15Vdc

TM1

Cho

ppe

r P

WM

Inve

rter

Dri

ve

Vo

lts F

eedb

ack

Cu

rre

nt F

eed

bac

k

Variable DCControlled DC (fixed)

Controlled AC (fixed)

Input supply

present

Output supply

present

Fault

present3-8 S3-C3.FM5 - Issue 2 Dated 21/08/97

7200 Series UPS Service Manual SECTION 3 - Control Power SuppliesCHAPTER 3 - DC-DC Power SupplyThe input and output voltage sense signals are resistively coupled to provide acommon voltage control input to IC9 pin 1. The input voltage is monitoredthrough CV1, R16, R15, R51 and CV2; and the output voltage is monitored by adedicated winding on the output transformer (4-6) and connected to CV2 via arectifier bridge comprising D9 and D10. Thus the voltage at CV2 is sensitive tochanges in both input and output voltage.

Resistor TM1 is connected in parallel with the voltage sense input to IC9 pin 1and enables the output voltage to be calibrated.

When the UPS is first powered up the DC bus voltage is initially zero and increas-es at a controlled rate as the rectifier phases forward (due to the Rectifier LogicBoard control features). To prevent the sensed lack of DC voltage causing thePWM generator to surge forward, a soft-start circuit is incorporated into the cir-cuit design, built around TR9.

In addition to providing a control input to IC9 pin 1, the dc busbar voltage is alsoconnected to IC9 pin 12, which is its Vcc supply input. From this supply IC9 in-ternally generates a stable 5V rail which it outputs at pin 14 to provide operatingpower for the remaining integrated circuits. It also provide a stable reference volt-age at pins 2 and 15 for the use of the IC9s internal error amplifiers.

Note: IC9 can operate with its Vcc supply in the range 7-40Vdc, which more thancaters for the DC busbar voltage variation while the UPS is operating on batterypower i.e. the power supply operating window is 240Vdc to 700Vdc on the DCbusbar.

The power supplys output current is monitored by T1 which is a current trans-former connected in series with the output transformer (T2) primary. T1 second-ary is rectified by D15D18 and a current-proportional voltage is developedacross burden resistor R13 which is fed back to IC9 pin 16 as an input to its inter-nal current error amplifier where it alters the PWM output.

3.3.3 Inverter and transformer sections

The inverter circuit converts the controlled dc voltage rail into an alternatingwaveform and basically comprises transformer T1 and fets TR7 and TR8.

One end of T1 primary is connected to the junction of C3 and C4 (in series withthe current sense transformer T2), and the other to the junction of TR8 and TR7.When considering AC, these components effectively form a bridge, and currentwill flow through T1 in either direction depending on whether TR8 or TR7 isturned ON. The transistors drive signals are fixed at 20kHz and transformer cou-pled in such a way that only one device is allowed to turn on at a time (i.e. theyare switched in anti-phase) thus AC current is set up in T1 primary.

T1 has three secondary windings; one provides a nominal 36Vac (@20kHz) out-put, the second provides the 12 Vdc outputs (after rectification) and the thirdprovides an output voltage feedback signal to the chopper voltage regulation cir-cuit.

The 20kHz transistor drive signals are obtained from IC9. The frequency is con-stant and determined by R39 and C22, which are connected to IC9 pins 5 and 6.The oscillator output is applied to a phase splitter circuit (IC7) which providescomplementary signals through IC6, IC5, IC4 and driver transistors TR1TR4 tothe driver transformer T3 primary. The passage of these signals can be interruptedat IC6 by a logic low from the fault detection latch (IC8), in which case the powersupply outputs are immediately cut off.S3-C3.FM5 - Issue 2 Dated 21/08/97 3-9

SECTION 3 - Control Power Supplies 7200 Series UPS Service ManualCHAPTER 3 - DC-DC Power Supply3.3.4 Fault detection

Fault detection is achieved by IC10 which is configured as four comparator cir-cuits.

One input to each comparator is connected to a 2.5V reference voltage derivedfrom voltage regulator IC2.

IC10b/c output pins 1 and 14 go low in the event of an overvoltage or overcurrentcondition respectively. This trips the latch formed by IC8, making IC8 pin 11 gohigh to illuminate LS3 and pin 4 go low to inhibit the inverter driver signals. Thelogic low at IC8 pin 4 is also taken to IC8 pin 9 to force pin 10 high and turn onTR11. When this transistor is turned on it effectively short circuits C23 whichtakes IC9 pin 4 to logic high (5V ref) and shuts down the ic operation.

IC10a pin 11 monitors the input (dc bus) voltage at the junction of R15 and R51,and IC10d pin 5 monitors the output feedback voltage from T1 secondary. Thesecomparators operate for undervoltage conditions and their logic low output shutsdown IC9 via TR11 as described above.

IC10 pin 13 monitors the input voltage to detect an undervoltage (