Sect-3

Section 3: Control Power Supplies

Chapter 1 - Control Power Generation & Distribution

1.1 Control power generation ................................................... ......................................................................... ...................... 3-1 1.1.1 AC-DC Power Supply Supply Board ..................................................... ....................................................... .. 3-2 1.1.2 DC-DC Power Supply Supply Board ..................................................... ....................................................... .. 3-2 1.2 Control Control power distribution ......................................... ................................................................. .............................. ...... 3-2 Chapter 2 - AC-DC Power Supply

2.1 Chapter overview ........................................ ............................................................. ........................................... ........................ .. 3-5 2.2 General description ........................................ .............................................................. ........................................... ..................... 3-5 2.2.1 Circuit board board functions ............................................. ................................................................ ................... 3-5 2.2.2 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 ........................................ .............................................................. ........................................... ..................... 3-7 3.2.1 Circuit board board functions ............................................. ................................................................ ................... 3-7 3.2.2 Input/Output connections connections ............................................................. ............................................................. 3-7 3.3 Circuit description ........................................ ............................................................... ............................................ ..................... 3-8 3.3.1 Introduction ....................................... .............................................................. ........................................... .................... 3-8 3.3.2 Series Series chopper and filter ........................................... .............................................................. ................... 3-8 3.3.3 Inverter and transformer sections .......................................... ................................................. ....... 3-9 3.3.4 Fault detection .................................................... ........................................................................... ......................... 3-10 3.3.5 Indications ............................................................ .................................................................................. ...................... 3-10 3.4 Calibration details ............................................................... ................................................................................... .................... 3-10

S-3.FM5 - Issue 2 Dated 21/08/97

i

SECTION 3 - Control Power Supplies

ii

7200 Series UPS Service Manual

S-3.FM5 - Issue 2 Dated 21/08/97

Section 3:

Chapter 1 - Control Power Generation & Distribution

1.1

Contro l power generatio n Two Power Supply Boards are fitted to the 7200 series UPS module; the AC-DC Power Supply Board and the DC-DC Power Supply Board – as illustrated in Figure 3-1 below. Figure 3-1: Control Power – primary supply Q2

Bypass Supply

STATIC SWITCH F6

F7

s k n i l s s a p y b t i l p S

T3

Q1

Input Mains Supply

F10

L1

F11

RECTIFIER

INVERTER

F12 F8

F9

F4

F5

T2

From T3

AC-DC Power Supply Board

DC-DC Power Supply Board

±12Vdc

Rectifier Logic Board

±12Vdc

Inverter Logic Board

±12Vdc Supplies to all other circuit boards

s3-c1.f m5 - Issu e 2 Dated 21/08/97

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SECTION 3 - Control Power Supplies CHAPTER 1 - Contro l Power Generation & Distribut ion

1.1.1


AC-DC Power Supp ly Bo ard The AC-DC Power Supply Board, which is described in detail in Chapter 2, is fed from both the input mains and bypass supplies via transformers T2 and T3 respectively, and is live when either of these two power sources are available (note that the ‘split-bypass links’ are removed if a separate bypass supply is used). This board produces ±12V and 0V outputs which are directly connected to the Rectifier Logic Board; and from this board these power rails are also connected to the remainder of the control circuit boards (except the Inverter Logic Board) as described in paragraph 1.2) . Transformers T2 and T3 are identical and have tapped primary windings to cater for 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 in ‘ganged’ fuse-holders which also serves as an isolation switch to a llow the transformers to be replaced without having to shut-down the entire UPS.

1.1.2

DC-DC Power Supp ly Bo ard The DC-DC Power Supply Board, which is described in detail in Chapter 3, is fed from the DC Busbar and is live whenever the rectifier is operative or the battery circuit breaker is closed. The board therefore has to operate over a wide range of input voltages varying between the battery boost voltage to the battery undervoltage trip level (approximately 240V to 700V). This board produces ±12V and 0V outputs which are connected to the Inverter Logic Board; and from this board these power rails are also connected to the remainder of the control circuit boards. The board’s input fuses (F5/F5) are fitted in ‘ganged’ fuse-holders which also serves as an isolation switch to allow the board to be replaced without having to shut-down the entire UPS. (Note: As the Inverter Logic Board is powered only from the DC-DC Power Supply, the inverter will shut-down and the load transfer to bypass if these fuses are opened.)

1.2

Control power distri bution 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 connected together on the UPS Logic Board and distributed to the remaining control boards as illustrated in Figure 1.2. Note that the power rails on the Inverter Logic Board are isolated by blocking diodes from the UPS Logic Board supply rails. This means that the Inverter Logic Board is powered only by the DC-DC Power Supply Board, and loses its operating power when this supply is not a vailable – i.e. without the DC Input (from the DC Bus) the inverter cannot operate. The remaining circuit boards, including the Rectifier Logic Board, are powered when either the AC-DC or DC-DC Power Supply Boards are active. Most of the boards also require other stabilised voltages, such as +5V, for their correct operation. Where such voltages are required they are developed individually on the board in question by appropriate voltage regulators. The exception to this is the Operator Control Panel, which obtains its regulated +5V power from an isolated dc-dc converter circuit on the Operator Logic Board.

3-2

s3-c1.f m5 - Issu e 2 Dated 21/08/97



Figure 3-2: Control Power Supplies Distribution ±12V inputs fro m AC-DC Po wer Sup pl y 3

4

±12V inputs fro m DC-DC Power Sup ply

5

V45

5

V46 0V -12V

+12V

Rectifier Logic Board

4

3

-12V

Inverter Logic Board

+12V 0V

V15 5-8

1-4

9-12

5-8

1-4

9-12

X2

X4

X1

X3

V14

9-12

1-4

5-8

9-12

1-4

5-8

-12V 0V +12V UPS Logic B oard +12V

5-8

0V 1-4

-12V

9-12

+12V

5-8

0V 1-4

-12V

9-12

X2

+12V

-12V

1

3

X5

1-4

+12V

1-4

5-8

X4

X1 5-8

0V

X8

X9

9-12

1

3

Operator Logic Board +5V 0V

High Voltage Interface Board

30-31 X13

5-8

1-4

4

9-12

1-4

5-8

X1

I/O Interf ace Board (Remote Options )

Static Switch Driver Board

30-31

4

Operator Contr ol Panel

s3-c1.f m5 - Issu e 2 Dated 21/08/97

3-3


3-4


s3-c1.f m5 - Issu e 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 in conjunction with circuit diagram SE-4503030-M.

2.2 2.2.1

General descri pti on Circuit board functio ns This board is responsible for providing the UPS control logic circuits, with the exception of the Inverter Logic Board and Inverter Driver Interface Board, with their ±12V low voltage operating power supplies. The board is itself powered from two supply sources; the first is derived from the UPS input mains s upply and the second is from the bypass mains supply. This means that the board is active when either of these two supplies is present - see chapter 1. Note: in installations not configured with a ‘split-bypass’ supply, the static bypass supply and UPS input supply are fed from a common mains power source and both supply sources to this board will fail in the event of an input mains failure.

2.2.2

Input/out put con nectio ns The AC-DC Power Supply board has three connectors, described below: • • •

2.3

M1 carries the board’s input supply derived from the UPS input mains supply. M2 carries the board’s input supply derived from the bypass mains supply. CN1 carries the board’s output low voltage supplies (±12V) to the UPS control circuit boards. These are initially connected to the Rectifier Logic Board and from there to the UPS Logic Board where they are coupled with the outputs from the DC-DC Power Supply, which is connected to the UPS Logic Board via the Inverter Logic Board.

Circuit description This board contains two straight-forward 3-phase rectifiers whose outputs are connected 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 to the S-T phases of the input mains supply and present a nominal 30Vac input (see the power schematics description in Section 1 Chapter 2). The transformer primary 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 to the 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 fitt ed to ganged fuse-holders which enable them to be used as a two-pole isolation switch.

The AC-DC Power Supply Board circuit diagram shows that each input supply passes through a full-wave bridge rectifier, providing an unregulated DC power

S3-C2.FM5 - Iss ue 2 Dated 21/08/97

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SECTION 3 - Control Power Supplies CHAPTER 2 - AC-DC Power Supply


source smoothed by C1 and C2. Two 3-terminal regulators are used to convert this raw 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. These leds are turned on by transistor drivers and will begin to illuminate when the power rails are greater than 10.5V (approximately).

2.4

Calib ration details This board is fully calibrated during the manufacturer’s bench testing procedure and should not require further adjustment when being fitted to the main equipment. The only adjustments are resistors TM1 and TM2, which are connected in the voltage sense lines to the 3-terminal regulators and enable the output voltage to 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 ±12V outputs from the DC-DC Power Supply, always ensure that the DC-DC Power Supply is inoperative when adjusting the AC-DC Power Supply output voltages. This is achieved by opening the battery circuit breaker an d turning off the rectifier.

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S3-C2.FM5 - Issu e 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 in conjunction with circuit diagram SE-4503028-K.

3.2 3.2.1

General descri pti on Circuit board functio ns This board is primarily responsible for providing the Inverter Logic Board and Inverter Driver Interface Boards with their ±12V low voltage operating power sup plies. It also provides a secondary power supply source for the remaining control logic boards when the AC-DC Power Supply Board is inactive. The DC-DC Power Supply Board is itself powered from the DC busbar, which means that it is active at all times w hen the DC busbar is live: either via the rectifier when the UPS input mains supply is healthy, or from the batteries in the event of a mains failure.

3.2.2

Input/Outpu t con nectio ns The DC-DC Power Supply board has two connectors, described below: • •

The input power is connected via M1 (IDC Connector) and is at the nominal DC busbar voltage. The board’s outputs at CN1 are connected to X5 on the Inverter Logic Board.

CN1 pins 1 & 2 carry a 36Vac output which passes straight through the Inverter Logic Board to the Inverter Driver Interface Board (to provide an internally isolated power supply for each inverter drive circuit). CN1 pins 3, 4 and 5 carry the board’s +12Vdc, 0V and -12Vdc outputs respectively. These are initially connected to the I nverter Logic Board and from there to the 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 Rectifier Logic Board.


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SECTION 3 - Control Power Supplies CHAPTER 3 - DC-DC Power Sup pl y

3.3


Circuit description

3.3.1

Introduction Figure 3-3: Block diagram M1

Bus +

1

Bus -

3

Variable DC

Controlled DC (fixed) Controlled AC (fixed) CN1

Series Chopper

Soft Start

Filter

Push Pull Inverter

M W P r e p p o h C

e v i r D r e t r e v n I

LS2 Input supply present

1 36Vac 2 Output Transformer k c a b d e e F s t l TM1 o V

PWM Control Logic

k c a b d e e F t n e r r u C

3 +15Vdc 4 0V 5 -15Vdc

Fixed Rectifier

Output supply

LS1

Fault Detection

present

LS3

Fault present

This board contains four major stages of operation: 1. A series-chopper circuit, working in conjunction with a filter, converts the board’s input supply, from the DC busbar, into a Controlled DC supply rail. Note: The input supply is variable according to the battery voltage as it charges and discharges – i.e. over a working range of 240-700Vdc. 2. The Controlled (fixed) DC voltage is then converted into Controlled AC by means of a simple push-pull inverter circuit which has a transformer-coupled output stage for isolation. 3. The transformer provides two sets of outputs: one leaves the board as a low voltage ac supply (36Vac nominal) and is used to provide an isolated power supply for the Inverter Base Driver Boards: the other is rectified to provide the general ±12Vdc LV control power supplies. Note: In the following description, the terms ‘input voltage’ and ‘output voltage’ refer to the voltages entering and leaving the D C-DC power supply board and not the UPS input and output voltages.

3.3.2

Series chop per and fil ter 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-designed integrated circuit (IC9). The PWM pattern produced by IC9 (and hence the controlled dc voltage) is determined by control inputs derived from the input voltage, output voltage and output current, which are all monitored by error amplifiers within IC9 whose outputs directly control its internal PWM pattern generator.

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SECTION 3 - Control Power Supplies CHAPTER 3 - DC-DC Power Sup ply

The input and output voltage sense signals are resistively coupled to provide a common voltage control input to IC9 pin 1. The input voltage is monitored through CV1, R16, R15, R51 and CV2; and the output voltage is monitored by a dedicated winding on the output transformer (4-6) and connected to CV2 via a rectifier bridge comprising D9 and D10. Thus the voltage at CV2 is sensitive to changes in both input and output voltage. Resistor TM1 is connected in parallel with the voltage sense input to IC9 pin 1 and enables the output voltage to be calibrated. When the UPS is first powered up the D C bus voltage is initially zero and increases at a controlled rate as the rectifier phases forward (due to the Rectifier Logic Board control features). To prevent the ‘sensed’ lack of DC voltage causing the PWM generator to surge forward, a soft-start circuit is incorporated into the circuit design, built around TR9. In addition to providing a control input to IC9 pin 1, the dc busbar voltage is also connected to IC9 pin 12, which is its Vcc supply input. From this supply IC9 internally generates a stable 5V rail which it outputs at pin 14 to provide operating power for the remaining integrated circuits. It also provide a stable reference voltage at pins 2 and 15 for the use of the IC9’s internal error amplifiers. Note: IC9 can operate with its Vcc supply in the range 7-40Vdc, which more than caters for the DC busbar voltage variation while the UPS is operating on battery power – i.e. the power supply operating window is 240Vdc to 700Vdc on the DC busbar.

The power supply’s output current is monitored by T1 which is a current transformer connected in series with the output transformer (T2) primary. T1 secondary is rectified by D15–D18 and a current-proportional voltage is developed across burden resistor R13 which is fed back to IC9 pin 16 as an input to its internal current error amplifier where it alters the PWM output.

3.3.3

Inverter and transfo rmer section s The inverter circuit converts the controlled dc voltage rail into an alternating waveform 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 with the current sense transformer T2), and the other to the junction of TR8 and TR7. When considering AC, these components effectively form a bridge, and current will flow through T1 in either direction depending on whether TR8 or TR7 is turned ON. The transistors’ drive signals a re 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. they are 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 third provides an output voltage feedback signal to the chopper voltage regulation circuit. The 20kHz transistor drive signals are obtained from IC9. The frequency is constant 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 provides complementary signals through IC6, IC5, IC4 and driver transistors TR1–TR4 to the driver transformer T3 primary. The passage of these signals can be interrupted at IC6 by a logic low from the fault detection latch (IC8), in which case the power supply outputs are immediately cut off.


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SECTION 3 - Control Power Supplies CHAPTER 3 - DC-DC Power Sup pl y

3.3.4


Fault detect ion Fault detection is achieved by IC10 which is configured as four comparator circuits. One input to each comparator is connected to a 2.5V reference voltage derived from voltage regulator IC2. IC10b/c output pins 1 and 14 go low in the event of a n overvoltage or overcurrent condition respectively. This trips the latch formed by IC8, making IC8 pin 11 go high to illuminate LS3 and pin 4 go low to inhibit the inverter driver signals. The logic low at IC8 pin 4 is also taken to IC8 pin 9 to force pin 10 high and turn on TR11. When this transistor is turned on it effectively short circuits C23 which takes IC9 pin 4 to logic high (5V ref) and shuts down the ic operation. IC10a pin 11 monitors the input (dc bus) voltage a t the junction of R15 and R51, and IC10d pin 5 monitors the output feedback voltage from T1 secondary. These comparators operate for undervoltage conditions and their logic low output shuts down IC9 via TR11 as described above. IC10 pin 13 monitors the input voltage to detect an undervoltage (<230Vdc). In such an event it latches OFF the drive signals and illuminates LS3. If CV2 is opened the minimum operating voltage is increased to 290Vdc. IC10 pin 2 monitors the output voltage to detect when the supply goes above 14.5V (approx.). In such an event it latches OFF the drive signals and illuminates LS3. During start-up these devices ‘enable’ the inverter driver logic by placing a logic low at IC8 pin 6 when the input voltage rises above its ‘undervoltage’ threshold.

3.3.5

Indications There are three leds on this board. LS3 is red and illuminates when a shutdown signal has been generated by the fault detection logic. The other leds are both green and are both lit during normal operation. LS1 signifies the presence of the 12Vdc outputs and LS2 shows the presence of the input supply.

3.4

Calib ration details This board is fully calibrated during the manufacturer’s final bench testing procedure and should not require further adjustment when being fitted to the main equipment. The only adjustment is TM1 which is used to calibrate the ±12V output supply rails.

Caution

3-10

If you need to alter this potentiometer make all adjustments very slowly. As a parallel voltage source is applied to the control logic boards from the AC-DC power supply board, when adjusting TM1 you should always monitor the DC-DC Supply Board’s output voltage across the board’s output diode bridge and not at the supply rails on the control logic boards.


Sect-3

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