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Jinxin Electronics launches solutions for stepper motor valve applications
Valve components such as water valves, oil valves, and expansion valves play an important role in regulation and control in automotive thermal management systems. Valve applications need to have high reliability, precise control and other performances, and at the same time, it is easy to use and reasonably priced. Stepper motors are very suitable for valve control due to their high precision, high cost performance, and simple circuits.
Based on the above market demand, Jinxin Electronics has launched a series of valve solutions suitable for small low-power stepper motor control, which is based on the development and design set of Jinxin 16-bit fixed-point DSP chip ADM16F03A2Q s, which has become LDO, pre-drive and LIN modules, with small starting and running current, adjustable speed, and constant current operation, which can simplify the customer development process and accelerate product launch.
The main control chip of this solution ADM16F03A2Q a special chip developed by Jinxin Electronics for motor applications, integrating ADP16F03 controller, complete signal acquisition chain, intelligent power management unit, 6NMOS pre-driver, LIN driver intelligent motor control driver chip, external power NMOS can form a single chip to form a brushed/brushless motor actuator, and realize single-wire control and networking at the same time. The following table is an introduction to ADM16F03A2Q motor control resources:
Master architecture | 16-bit fixed-point DSP |
Frequency | 150MHz |
Storage resources | 8KB SARAM、64KB Flash |
Single power supply | 4.5-40V |
Communication interface | SCI (Configured as LIN Interface) |
peripheral |
|
Simulate peripherals | OPA+3PGA+5 comparator + temperature sensor |
Integrated configuration | 12V-LDO、6NMOS预驱、LIN-PHY |
Motor drive method | Sensive/non-inductive square waves Sensible/non-inductive string waves |
encapsulation | QFN56 package |
Temperature range Vehicle Regulation Certification | -40-125°C AEC-Q100 |
Table 1 ADM16F03A2 Motor control related resources
As shown in the block diagram below, the integrated 5V LDO and 12V LDO can connect the bus directly to the LDO_IN pin without the need for additional step-down or divider devices; At the same time, the built-in 6NMOS pre-driver only needs to be used by simply configuring the boost device on the periphery; The integrated LIN driver is also convenient and fast when communication with other LIN masters (slaves) is required. Combined with the software and hardware resources of our company's self-developed three-half-bridge drive two-phase four-wire stepper motor, it can realize the same excellent stepper motor control with less chip resource occupation and lower cost hardware.
Figure 1 Block diagram of ADM16F03A2 stepper motor valve application
Software modules
On the basis of the three-way half-bridge, the software adopts vector control to connect one end of the different coils of the stepper motor in parallel as the common end, and drives the stepper motor to run through the open-loop SVPWM.
Figure 2 Software control logic
Hardware modules
The circuit modules mainly include: ADM16F03A2 chip minimum system, H-bridge circuit, ADC sampling circuit.
1) ADM16F03A2 the smallest system of chips
The ADM16F03A2 minimum system is shown in the figure below, including JTAG interface, SPI communication interface, serial port, PWM module, ADC module, etc. The system's built-in op amp PGA can be configured in differential mode via peripheral resistors for phase current sampling. When SPI debugging is required, SPI communication debugging can be carried out through the SPI interface with the help of the core SPI communication debugging tool. When an offline programming program is required, the pad is tested with 3V3, TX, RX, and GND signals, and fast offline programming can be achieved with the help of the core input offline programming tool.
Figure 3 ADM16F03A2 the smallest system
2) H-bridge circuit
The H-bridge circuit adopts the configuration of NMOS for both upper and lower tubes, and a total of 6 NMOS form a three-phase H-half-bridge drive circuit.
The three-phase half-bridge gate driver chip is integrated inside the ADM16F03A2, and only a simple BOOST circuit needs to be built to increase the on-tube NMOS gate drive voltage, and the rest of the driver parts have been integrated into the DSP, which greatly simplifies the space requirements and layout difficulty of PCB hardware layout, and significantly reduces costs.
The phase current sampling resistor 200mR is placed on any two phases of the low-side three-phase and connected to the peripheral amplification circuit of the PGA of the ADM16F03A2 by differential traces.
Figure 4 H-bridge and BOOST circuit
3) ADC sampling circuit
The ADC sampling circuit includes sampling of the arm phase current of the two bridges and sampling of the bus voltage. The phase current is used for stall position detection, and can also be used for current loop bus voltage detection, in addition to protection, it also provides voltage parameters for the calculation of software algorithms
Figure 5 ADC sampling circuit
Physical objects and waveforms
Based on the above application introduction, our company designed a control DEMO board for driving an electronic water valve for driving a 12V two-phase four-wire stepper motor. The physical and measured waveform diagrams of the board are shown in the following figure:
Fig.6 12V electronic water valve drive board
Fig.7 Waveform diagram of the phase current of the whole stroke of the stepper needle valve
Fig.8 LIN communication waveform diagram
Technical support
Jinxin Electronics can provide customers with the schematic diagram, PCB reference board diagram, source code, and software and hardware development technical support corresponding to the above solution, if you need to know more about the details of the solution, please call 0731-88731027.
