The Tandem Motion-Power 48 V Board contains a bidirectional DC-DC boost-buck converter to generate the DC link voltage and six half-bridge inverter outputs. The board sends three half-bridge outputs to each output connector to create two three-phase motor inverters. You can use the half bridges in alternative arrangements for motors with different numbers of phases. The board provides MOSFET power electronics for DC-DC conversion and DC Link inversion, current and voltage sensing for DC-DC and motor control feedback, and connections for motor position feedback. You can use the Tandem Motion-Power 48 V Board to develop a single or dual-axis motor control application that supports multiple motor types and multiple position feedback interfaces. The Tandem Motion-Power 48 V Board includes an HSMC interface connector for connection to a variety of Altera FPGA and SoC-FPGA development kits.
About Motor Control
Efficient control of torque and speed of AC motors requires corresponding control of voltage and current that you supply to the motor. In a typical motor control system, you generate a DC voltage known as the DC link or DC bus voltage. You then invert the DC voltage through switching of power electronics, such as insulated-gate bipolar transistors (IGBTs) or MOSFETs to create the appropriate variable AC voltages for the motor. Control algorithms such as field oriented control (FOC) require you to measure motor current and voltages, to provide the required feedback to the controller.
Multiaxis drives achieve either a high degree of coordination of control across motors or, in some applications, integrate control of multiple independent motors to reduce overall system cost. In servo drives, high-precision position feedback sensors, such as optical encoders, enable accurate position and speed control.
- Two motor axes, each with three-phase MOSFET power stages operating up to 125 kHz
- Input voltage range 9 to 16 V DC
- DC link voltage of 12 to 48 V from DC-DC boost-buck converter
- Variable 62.5 to 125 kHz switching frequency
- Two-phase conversion for smoother output
- Bidirectional, allowing regeneration with buck conversion to 12 V
- Enpirion® switch mode power supplies for logic, position sensors, MOSFET gate drives and regulated 12 V output
- Sigma-delta ADCs for sensing voltages and currents
- Direct analog connection to suitable development kits such as the MAX® 10M50 Development Kit
- Sensed motor phase currents and voltages to enable sensorless control
- Position feedback interfaces for each axis:
- Quadrature incremental encoder
- Resolver with Tamagawa resolver-to-digital converter (RDC)
- Hall effect (6-step position feedback)
- EnDat absolute encoder
- BiSS absolute encoder
The DC inputs are a 6-pin Molex (up to 200W), 4-pin DIN (up to 100W) or 6-pin pluggable terminal block to suit a range of standard power supplies. The board offers directly wired connection to other power supplies or batteries and a direct connection to the DC link, bypassing the DC-DC boost converter.
Signals connecting the Tandem Motion board to the development kit are buffered and level shifted for compatibility with a number of development kits. A configurable I/O power supply allows interfacing with common I/O standards implemented on Altera FPGAs.
MAX 10 ADC Connector
Analog signals are available on a 20-pin header for connection to a suitable development kit that includes ADCs. The pinout matches that of J20 on the Altera MAX 10 10M50 development kit.
DC-DC Boost Converter
The DC-DC boost converter hardware consists of two phases that both provide bidirectional power flow from a low voltage power source or battery (typically 12 V DC) to a DC bus (typically 48 V DC) that feeds the motor drive inverters. The DC-DC provides the boost function to increase the voltage of the DC link. It also provides a buck function during periods of regenerative braking to deliver power from the DC bus back to the low voltage source (i.e. battery in this case). Enable regeneration by pulling down pin 3 of the battery connector, J1. If you do not attach an energy storage element to the DC bus, disable regeneration.
The DC input voltage, DC link voltage, DC link current and the currents in each DC-DC phase are sensed and converted to digital signals which must be used to implement a control loop for the DC-DC boost function in the FPGA on the attached development kit. Altera reference designs targeting the Tandem Motion board contain a controller developed using Altera’s DSP Builder Advanced Blockset for Simulink, which enables model-based design, automatic HDL code generation and automatic ModelSim testbench generation.
A switch-mode buck-boost converter provides a 24 V supply, which drives a number of downstream regulators. This arrangement enables the board to operate with variable DC link voltages or with power input through the DC-DC bypass connector.
Multiple Enpirion ER3125 devices provide 12 V, 5 V and 3.3 V supplies to logic and other circuits on the board.
The board provides a configurable I/O voltage for the connections to the development kit. You configure I/O voltage by populating one or more zero-ohm resistors.
The board has six N-channel MOSFET half bridges, nominally arranged as two three-phase inverters for driving three-phase motors. You can use the half bridges in other arrangements, e.g. to drive stepper motors.
The encoder interfaces apply the appropriate voltage translation and buffering for each encoder type.
Quadrature and Hall sensor encoders use three differential pairs to connect to the board.
EnDAT and BiSS encoders are connected via an RS-485 serial bus.
A Tamagawa AU6805 Resolver-Digital Converter (RDC) provides the resolver interface for each drive axis. The AU6805 supports 12- and 16-bit absolute position over a serial interface together with quadrature equivalent and Hall sensor equivalent feedback signals in parallel.
Analog Signal Conditioning and Conversion
In addition to the analog connector for MAX10 ADCs, the board also includes sigma-delta modulators to support digital connections to FPGAs that do not have integrated ADCs. You must implement a suitable demodulator in the FPGA, as described in Altera application note AN 773 and datasheet DS-1038.
The board implements current sensing with low Ohmic value shunt resistors. The board connects the resulting sense voltage directly to the sigma-delta modulator or through a sense amplifier to the MAX10 ADC input.
You can add a low-pass filter to the inputs to the sigma-delta ADCs but in all cases the demodulator IP in the FPGA filters them.
For the direct MAX10 inputs, sense amplifiers scale and offset the inputs to allow bipolar signals (e.g., bidirectional current flow) to be sampled with the MAX 10 ADC that can only convert signals between 0 V and its reference voltage. Remove the offset during processing of the samples in software. The sense amplifier circuit has a low-pass filter, scaled by five times and offset by 1.25 V.The input current and DC bus current are only available via sigma-delta ADCs. Both sense circuits employ analog anti-aliasing circuitry with cut-off frequencies around 7 kHz before the sigma-delta ADC, for consistency with other DC-DC converter signals that are sampled at 16 kHz.
The board implements voltage sensing with voltage dividers connected directly to the sigma-delta or MAX 10 ADC inputs, with low pass filtering.
The input current and DC bus current are not available as analog signals to the MAX 10 ADCs, so do not have filter cut-off frequencies. The board samples motor phase currents at the quiet points of the PWM waveforms (refer to Altera applicaztion notes AN669, AN773, and datasheet DS-1038). The filtering inherent in the sigma-delta demodulation is sufficient, so the board uses no additional analog anti-aliasing filters.
|Signal||Anti-aliasing cut-off frequency forAnti-aliasing cut-off frequency for|
|Sigma-delta ADCs (kHz)||MAX 10 ADCs (kHz)|
|Motor phase voltages||0.73||754|
|DC bus voltage||7.3||6.2|
|Boost inductor current||7.7||6.8|
|DC bus current||7.7||N/A|
|Motor phase currents||N/A||14|
- Remove all power from the Tandem Motion-Power 48 V Board.
- Unplug the existing motor and encoder cables.
- Configure the jumpers to select the encoder power supply.
- Configure the jumpers for the encoder type and signal connections.
- Prepare the motor cable with the 4-way pluggable screw terminal block.
- Prepare the encoder cable with the 8- or 20-way push fit pluggable terminal block.
- Plug in the motor and encoder cables.
|J8||DRV0||Encoder power supply selection|
|J10||DRV0||Quadrature encoder A source|
|J11||DRV0||Hall sensor U source|
|J12||DRV0||Serial encoder Rx source|
|J13||DRV0||Quadrature encoder B source|
|J14||DRV0||Hall sensor V source|
|J15||DRV0||Serial encoder Tx source|
|J16||DRV0||Quadrature encoder Z source|
|J17||DRV0||Hall sensor W source|
|J18||DRV0||Serial encoder CLK source|
|J22||DRV1||Encoder power supply selection|
|J24||DRV1||Quadrature encoder A source|
|J25||DRV1||Hall sensor U source|
|J26||DRV1||Serial encoder Rx source|
|J27||DRV1||Quadrature encoder B source|
|J28||DRV1||Hall sensor V source|
|J29||DRV1||Serial encoder Tx source|
|J30||DRV1||Quadrature encoder Z source|
|J31||DRV1||Hall sensor W source|
|J32||DRV1||Serial encoder CLK source|
|J40||DRV0||Resolver excitation voltage|
|J43||DRV1||Resolver excitation voltage|
Quadrature Encoder and Hall Sensor Operation
You can select quadrature encoder and Hall sensor motor feedback operation by populating these six jumpers, per axis. You can set up the Tamagawa RDC to emulate a quadrature encoder.
J10, J13 and J16 select the A, B and Z quadrature paths for DRV0 motor.
J11, J14 and J17 select the U, V and W Hall sensor paths for DRV0 motor.
J24, J27 and J30 select the A, B and Z quadrature path for DRV1 motor.
J25, J28 and J31 select the U, V and W Hall sensor path for DRV1 motor.
RDC Quadrature Encoder Emulation Operation
You can setup the Tamagawa RDC to emulate a quadrature encoder and or Hall sensor encoder.
J10, J13 and J16 select the A, B and Z paths for DRV0 Resolver.
J11, J14 and J17 select the U, V and W paths for DRV0 Resolver.
J24, J27 and J30 select the A, B and Z paths for DRV1 Resolver.
J25, J28 and J31 select the U, V and W paths for DRV1 Resolver.
BiSS and EnDAT Operation
You can select BiSS or EnDAT position feedback data coming from the motor.
J12, J15 and J18 select the RX, TX and CLK paths for the DRV0 motor.
J26, J29 and J32 select the RX, TX and CLK paths for the DRV1 motor.
J6 and J7 select EnDAT for DRV0.
J20 and J21 select EnDAT for DRV1.
RDC Serial Feedback Operation
The Tamagawa RDC can be set up to provide serial feedback data.
J12, J15 and J18 select the RX, TX and CLK paths for the DRV0 Resolver serial data.
J26, J29 and J32 select the RX, TX and CLK paths for the DRV1 Resolver serial data.
Encoder Power Supply Selection
You can select the power supply voltage connected for the encoder interface. The available options are 24V, 12V, 5V and 3.3V.
J8 selects the voltage for encoders on DRV0.
J22 selects the voltage for encoders on DRV1.
Tamagawa RDC Built-In Self Test (BIST)
The Tamagawa RDC has a BIST feature that you can access.
the population of the no BIST position is not required as the board has an internal pull-down resistor in the RDC to disable BIST.
Altera reference designs do not support the RDC BIST feature.
J39 Selects BIST operation for DRV0 RDC. (DRV0) and J42 (DRV1).
J42 Selects BIST operation for DRV1 RDC.
Resolver Excitation Voltage Selection
You can select the resolver circuitry excitation voltage to be either 12V or 24V.
J40 selects the excitation voltage for DRV0.
J43 selects the excitation voltage for DRV1.
I/O Voltage Supply
R378, R377, R376