One of the distinctive features of the intelligent flexible platform’s soft control functionality: synchronous motor drive.
2022-06-06
STEP Next-generation EP/ET/EH smart flexible actuators Having been launched for nearly a year, the unique application features of our product have already played an important role at multiple user sites. Starting today, we’ll introduce the firmware functions of our intelligent flexible drives in several installments, giving everyone a deeper understanding of the new capabilities of Xindata’s drives.
As is well known, dual-carbon energy conservation has become one of the primary guiding principles for current industrial development. Many customers are no longer satisfied with traditional squirrel-cage three-phase induction motors; instead, permanent-magnet synchronous motors and synchronous reluctance motors—offering higher energy efficiency and greater control precision—have become the preferred choice in numerous industries.
When the original frequency converter directly controls permanent-magnet or reluctance motors, many problems arise. For example:
1. The back EMF generated when the permanent magnet motor is powered on causes the motor to reverse rotation.
2. The motor’s self-tuning cannot be completed; the motor crawls at low speed and fails to reach the set frequency (cannot accelerate).
3. Motor vibration, whining, overheating, and failure to operate normally, etc.
Therefore, conventional variable-frequency drive algorithms cannot effectively control the operation of synchronous motors, and using V/F control to drive synchronous motors simply fails to unleash the motor’s full potential. STEP is a well-established manufacturer of complete elevator electrical control systems with over 20 years of experience in the application of synchronous motors in the elevator industry—experience that it has long mastered.
The parameters of intelligent flexible actuators in synchronous motor control fully demonstrate their product advantages. The synchronous motor reverses direction upon startup because, under the influence of the salient-pole effect, the permanent magnets’ magnetic pole positions are uncertain, leading to an incorrect input current phase. Therefore, before starting the motor, it’s essential first to estimate the initial position of the magnetic poles and accurately detect their actual locations.
Internal parameters of the intelligent flexible actuator:
This function is used to set the control operating mode of the inverter:
0: GVC Control
Suitable for most application scenarios, and compatible with synchronous motors, induction motors, and synchronous reluctance motors.
1: SVC Control
Sensorless vector control, suitable for both synchronous and asynchronous motors.
Motor type options:
0: Asynchronous motor
1: Synchronous motor
2: Reluctance Motor
Moreover, the drive can support a second motor, which is widely used in applications such as logistics shuttles and stackers.
0: No judgment
No-load starting capability, requiring a relatively long acceleration time.
1: DC Injection Start-up
Incrementally inject a DC current up to (P15.05 × motor rated current), thereby dragging the motor’s magnetic poles into the excitation direction.
2: Pulse Voltage Injection Start-up
Inject a voltage pulse to perform initial magnetic pole detection.
By setting the parameters described above and combining them with the motor’s self-tuning function, you can achieve smooth starting of synchronous motors while fully leveraging the characteristics of both permanent-magnet synchronous motors and synchronous reluctance motors. Therefore, if someone claims that their VFD can also drive synchronous motors, you should take a closer look at the parameter table in their user manual to see whether the aforementioned parameters are included. If these parameters are absent, driving a synchronous motor will inevitably lead to some abnormal phenomena as described earlier in this article, making it impossible to drive the synchronous motor effectively and fully realize its optimal energy efficiency.
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