H2W technologies LPAM-1 User manual

Linear Power
Amplifier
Module
User's Guide
Version 2.0

Table of Contents
Table of Contents
Technical Specifications.........................................................................................7
Absolute Maximum Ratings.....................................................................7
Amplifier Specifications...........................................................................7
Amplifier Board Layout.........................................................................................9
Pinouts....................................................................................................................11
User Connection Header........................................................................11
Amplifier Mode Select............................................................................13
Voltage / Current Selection Header..........................................13
Power Supply Monitor Enable..............................................................14
Integrator Reset Enable.........................................................................15
Amplifier Configuration Block..............................................................15
Voltage Mode Gain Setting .......................................................16
Current Mode Configuration ...................................................18
Power Supply...........................................................................................23
Load Connection.....................................................................................25
GND Lug..................................................................................................26
Offset Adjustment...................................................................................26
Offset Adjustment Procedure....................................................27
Current Limit Adjustment.....................................................................27
Current Limit Adjustment Procedure......................................29
Status Indicator LEDs............................................................................29
External Fault Indication.......................................................................30
Amplifier Enable Inputs.........................................................................30
Command Signal.....................................................................................31
Current Monitoring................................................................................32
Installation.............................................................................................................33
Mechanical Mounting.............................................................................33
Cooling Fans............................................................................................34
Determining the Dissipated Power............................................35
Determining the Required Airflow for Cooling...................................36
Electrical Connections............................................................................37
Selecting a Power Supply.......................................................................38
Operating Voltage.......................................................................38
Current Handling Capability....................................................39
Power Supply Type.....................................................................39
Connecting A Single Unit.......................................................................39
i

Table of Contents
Connecting Multiple Units.....................................................................41
Appendix A............................................................................................................45
Dimensions...............................................................................................45
ii

List of Figures
Table of Figures
Figure 1. Layout of the amplifier board and the various features................................9
Figure 2. amplifier mode selection jumper....................................................................13
Figure 3. Power supply monitor jumper location.........................................................14
Figure 4. Integrator reset jumper detail........................................................................15
Figure 5. Amplifier configuration block details............................................................16
Figure 6. Schematic representation of the amplifier....................................................17
Figure 7. Simulink diagram showing the user adjustable values................................23
Figure 8. Power connection details.................................................................................24
Figure 9. Load connection details...................................................................................25
Figure 10. GND connection.............................................................................................26
Figure 11. Offset adjustment..........................................................................................27
Figure 12. Current limit setting......................................................................................29
Figure 13. Amplifier status indicator LEDs..................................................................30
Figure 14. Mounting hole locations A (green) or B (blue)............................................33
Figure 15. Mounting locations for the small (twin) fans..............................................34
Figure 16. Mounting location of the large fan...............................................................35
Figure 17. Single amplifier connections.........................................................................41
Figure 18. Multiple amplifiers connected with a single power supply........................42
Figure 19. Multiple power supplies to drive multiple power amplifiers.....................43
iii

List of Tables
List of Tables
Table 1. User Connection Header signal names and pinout........................................12
Table 2. Details of the various configuration options...................................................17
Table 3. Recommend values for the forward gain in current mode...........................18
Table 4. Factory configuration of the integration components...................................18
Table 5. Power supply connection..................................................................................24
Table 6. Amplifier output terminals..............................................................................25
Table 7. Ground lug connection.....................................................................................26
Table 8. Typical current limit settings...........................................................................28
Table 9. Current limit output pinouts............................................................................29
Table 10. Amplifier enable truth table...........................................................................31
Table 11. Command signal pinouts................................................................................31
Table 12. Current output pins........................................................................................32
iv

Linear Power
Amplifier Module
LPAM-1
Key Features
•Linear - Designed for low noise
operation
•High Output Current:
7A Continuous output
9A Peak output
•Wide Power Supply Range:
27 Volts to 60 Volts
•Wide Bandwidth:
>10kHz in current mode
>10kHz in voltage mode
•Dual Mode Operation:
Voltage Mode
Current Mode
•Fully Protected:
Thermal Shutdown
Adjustable Current Limit
Power Supply Monitor
•Active High and Active Low
amplifier enable inputs
•Offset Trim Adjustment
•Fault Indicator Output
•Startup / Shutdown Circuitry
disables the amplifier until power
supplies stabilize
Applications
•Voice Coil Actuators
•X-Y Stages
•Robotics
•Magnetic Bearings
Description
The Quanser Power Amplifier is a linear power amplifier designed to drive loads in either voltage
mode or current mode.
In the current mode configuration, the amplifier is best suited for inductive loads such as dc-motors and
voice coil actuators. The unit displays low noise, wide bandwidth and an offset voltage adjustable to
zero.
Designed to run from a single supply, the amplifier's features include; accurate current sensing,
selectable fixed gain configurations, current limiting, and thermal protection.

Technical Specifications
Technical Specifications
Absolute Maximum Ratings
Parameter Value Units
Supply Voltage 60 V
Output Current
Continuous
Peak
7
9
A
A
Input (command) Voltage
supply voltage = 27 V
supply voltage = 48 V
+/- 10
+/- 20
V
V
Operating Temperature
(ambient temperature, natural convection cooling)
Power de-rating occurs beyond this temperature.
50 °C
Amplifier Specifications
Parameter min max typical Units
Power Supply Range 27 60 30 V
Input Voltage (Differential, max)
Supply voltage = 27 V
Supply voltage = 48 V
20
40
V
V
Input Impedance 1 MOhm
Output Impedance <0.2 Ohms
Bandwidth
Voltage Mode
Current Mode
>10
>10
kHz
kHz
Power Amplifier Module User's Guide 7

Amplifier Specifications
Parameter min max typical Units
Disable input signal
high TTL level, 5V
low TTL level, 0V
1
1
mA
mA
Amplifier Fault output
TTL compatible, with 200 ohm resistor inline
(current limited to 25 mA)
05 V
Current Sense output (buffered) 1 mA
Current Limit Output
reference voltage 0.5 V / A 0.5
V/A
Offset Adjust Adjusts output to zero for
zero command (input)
signal.
8Power Amplifier Module User's Guide

Amplifier Board Layout
Amplifier Board Layout
This section of the manual describes the general layout of the board, and the location of key
features. Refer to this diagram when making connections and when locating functions on
the board.
Power Amplifier Module User's Guide 9
Figure 1. Layout of the amplifier board and the various features.
Ground Lug
Power
Load Connection
Voltage / Current
Select
Integrator Reset
Enable
Power Supply Monitor
Enable
Current Limit
Adjust
Offset
Adjust
Amplifier Configuration
Block
Fault / Status
Indicator LEDs
User Connection
Header

Pinouts
Pinouts
This section explains the various connections that can be made to the amplifier module.
Note that all connections should be securely made with the proper connectors. Improper
connections may result in poor performance, or may possibly damage the amplifier and
other connected equipment.
User Connection Header
The user connection header is where the user will make the connections to the amplifier.
The command signal and the feedback signal (current measurement) are present on this
header
Power Amplifier Module User's Guide 11

User Connection Header
Pin Number Signal Comments
1 +5V Available for signal conditioning circuitry, 10mA
max.
2 GND Ground connection.
3 -5V Available for signal conditioning circuitry, 10mA
max.
4 REF - Command signal negative or ground reference.
5 REF + Command signal positive or signal.
6 Current Limit
Monitor
Output of current limit setting.
7 GND Ground connection.
8 Not used Do not make connections to this terminal.
9 Current Monitor Current measurement output, 0.5V/A
10 GND Ground connection.
11 /ENABLE Amplifier Enable input. This line must be at 0V for
the amplifier to operate.
12 GND Ground connection
13 ENABLE Amplifier Enable input. This line must be at 5V for
the amplifier to operate.
14 +5V Available for signal conditioning circuitry, 10mA
max.
15 FAULT OUTPUT Fault indication for the amplifier, external LED
connection
16 GND Ground connection
Table 1. User Connection Header signal names and pinout.
12 Power Amplifier Module User's Guide

Amplifier Mode Select
Amplifier Mode Select
Voltage / Current Selection Header
The amplifier is designed to function either as a voltage amplifier or a current amplifier.
Selection of what mode the amplifier operates in is by way of a jumper. Placing jumper J1
in the 1-2 position selects voltage mode. Placing the jumper in the 2-3 position selects
current mode. The default configuration for the amplifier is current mode, with the
jumper in the 2-3 position.
Voltage Mode
In this configuration, the amplifier accepts a command signal and outputs a voltage
proportional to the command signal. The signal can be amplified by the configurable gain
setting of the amplifier. See the section titled, “Amplifier Configuration Block” for details
on this procedure. Power is provided to the load at increased current driving capability, up
to a maximum of 7A continuous output.
In voltage mode, the commanded signal will correspond to an output voltage related by the
gain setting of the amplifier. For example, with a gain setting of 1, a 1 volt input signal will
produce a 1 volt output signal at the output terminals of the amplifier. Similarly, with a gain
setting of 4, a 1 volt command would provide 4 volts at the output of the amplifier. The
units of the gain are therefore expressed in terms of volts per volt (V/V).
The amplifier will be able to provide an output voltage approaching the supply voltage of
the amplifier. See the Technical Specifications section for details.
Current Mode
In the current mode configuration, the amplifier outputs the commanded current to the load.
Despite changes in the load, the amplifier will output the commanded current. The
Power Amplifier Module User's Guide 13
Figure 2. amplifier mode selection jumper.
Voltage / Current
Select Jumper

Amplifier Mode Select
amplifier uses a built in current feedback loop to continuously change the voltage applied to
the load so the commanded current is always applied to the load. The maximum continuous
current available is 7A. Consult the section titled, “Amplifier Configuration Block” for
details on matching the amplifier to your load.
In current mode, the input signal corresponds to a commanded current. Therefore the
output current of the amplifier is related to the input voltage by the current gain of the
amplifier implemented using external components. For example, with a current gain setting
of 1, a 1 volt input signal will produce a 1 amp output signal at the output terminals of the
amplifier. Similarly, with a gain setting of 4, a 1 volt command would provide 4 amps at the
output of the amplifier. The units of the gain are therefore expressed in terms of amps per
volt (A/V). The factory configuration is 2 Amps / Volt.
It is important to consider that the voltage at the output terminals is automatically adjusted
by the amplifier to provided the commanded current. For this reason, care must be taken to
ensure that the amplifier is being asked to do something that it can accomplish based on the
available power supply. The maximum current that the amplifier can provide is limited by
the supply voltage and the impedance of the load.
Power Supply Monitor Enable
The power amplifier employs a voltage monitoring system to ensure that safe startup and
shutdown conditions for the amplifier are met. This feature limits surge currents that may
be sent to the load at startup or shutdown. A delay of approximately 0.5 seconds is used
during turn on of the amplifier, and the amplifier will not be enabled until the power supply
has reached the minimum voltages. At voltages under the specified 27 volts minimum
operating voltage, the amplifier will not be enabled with this jumper in the 1-2 position. To
disable this feature install the jumper in the 2-3 position. The factory configuration is
with the power supply monitor enabled, with the jumper in the 1-2 position.
14 Power Amplifier Module User's Guide
Figure 3. Power supply monitor jumper location.
Power Supply
Monitor Jumper

Integrator Reset Enable
Integrator Reset Enable
Along with the power supply monitoring feature of this amplifier, an integrator reset feature
is provided. Jumper SW EN enables / disables resetting of the integrator of the amplifier.
With this jumper in the 1-2 position, the integrator used for the current feedback loop is
cleared or reset to zero when the amplifier is first powered up, or when the amplifier is
disabled. In the 2-3 position, this feature is disabled. The factory default configuration is
with the jumper in the 1-2 position, enabling the integrator reset feature.
Amplifier Configuration Block
The amplifier configuration block allows customization of the amplifier to the user's needs.
These customizable features include:
•gain setting
•amplifier tuning
These features allow the user to customize the amplifier to suit a specific application.
Table 2 provides a description of the components used in the configuration block and the
functions that they serve. Figure 6 shows the schematic details of how the components
operate in the configuration of the amplifier.
Power Amplifier Module User's Guide 15
Figure 4. Integrator reset jumper detail.
Integrator Reset
Enable Jumper

Amplifier Configuration Block
Voltage Mode Gain Setting
In voltage mode, the total gain of the amplifier is determined by the components A, C, and
D in the configuration block. From the description in Table 2 and the schematic diagram in
Figure 6, the total gain can be calculated as the product of G1G2GF, where GFis the final
gain stage of the amplifier and is fixed to a value of 20.
G
T
= G
1
× G
2
× G
F
It is important to note that when choosing resistor values to set the gains G1 and G2, that
the values chosen do not cause the amplifier to saturate. This means that the gains used
must keep the voltages below 11 volts.
16 Power Amplifier Module User's Guide
Figure 5. Amplifier configuration block details.
A B C D E F G H

Amplifier Configuration Block
Row Part Name Function Default Value
A R36 This resistor with D sets the first gain stage of the
amplifier. The resulting gain is G1= D/A.
10k
B R33 Current loop feedback gain resistor. 1k
C R22 Sets the gain in voltage mode for the amplifier. The
resulting gain for this stage is G2= C/1k.
10k
D R55 With A, this resistor value sets the first gain stage
for the amplifier. The resulting gain for this stage is
G1= D/A.
10k
E C10 Current loop error feedback integration capacitor 22nF
F C9 Current loop feedback compensation capacitor –
typically use factory value of 2.2nF.
2.2nF
G - Do not make connections in this position. open
H - This enables the integrator clearing circuitry and
must be installed for it to function properly.
short
Table 2. Details of the various configuration options.
Power Amplifier Module User's Guide 17
Figure 6. Schematic representation of the amplifier.
Shutdown
and
Enable Logic
/Enable
Enable
Power
Monitor
Output Disable
Ref+
Ref-
Differential
Input
A
D
C
1k
1k
Voltage
Current
H
F
EB
Gain = 20
Current Monitor
J1
J2
SW1 - Integrator Reset
SW1 Differential
Output
500mV / A
1k

Current Mode Configuration
In order to set the gain of the amplifier, you need to select components D and A. These set
the forward gain such that the amplifier delivers G Amps/V.
The equation for the forward gain of the amplifier is
G = 2
D
A
Table 3 shows recommended values
G – Amps / V D – Ohms A - Ohms D / A
1 5000 10000 0.5
2 10000 10000 1
4 20000 10000 2
Table 3. Recommend values for the forward gain in current mode.
The bolded text shows the factory configuration.
Tuning the Amplifier
In current mode the amplifier must be tuned to the load inductance and resistance. This is
important to optimize its performance for the load.
The tuning components as configured at the factory are:
Component Purpose Value Units
E Integration gain capacitor 2.20E-008 Farads
B Loop gain resistor 1000 Ohms
Table 4. Factory configuration of the integration components.
By changing the above components you can adjust the current loop proportional and
integral gains.
18 Power Amplifier Module User's Guide

Do You Want an Integrator?
First you need to determine whether you want integration or not. The capacitor E will
introduce an integrator in the feedback loop in order to assure zero steady state error in
current independent of load resistance and back EMF. The disadvantage of using an
integrator in the current loop is the following: if you are using an actuator driving a load
with very little friction, the slightest offset in the input may cause a runaway in the motor
unless you are operating a stable closed loop externally. It is recommended that you first try
with an integrator and adjust the offset to zero. If the motor runs away in open loop with the
expected load, then you may want to completely eliminate the integrator by shorting
component E.
The drawback of removing the integrator is that the forward gain will now be load
dependent. The expected forward gain, with an integrator is:
G = 2
D
A
With no integration however, the gain in the system now becomes:
G = 2
D
A
10 Kp
R
load
 10 Kp
where Kp is determined by the equation:
K
p
=
B
1000
where B is the value of component B in ohms.
With Kp = 1 (B = 1 KOhm) , the gain will decrease as the load resistance increases as in
the following table:
Power Amplifier Module User's Guide 19