Analysis of the features of VFD frequency converter drivers from MEAN WELL

26.03.2024 |

One of the important categories of devices for controlling motors of various types and power is frequency converters for electric drives. MEAN WELL has developed several series of power modules (drivers) for frequency converters designed to control three-phase motors of various types: brushless DC motors (BLDC), asynchronous, and synchronous reluctance motors (SynRM).

To create a complete frequency converter based on the VFD driver, a control module is required. The control module is connected to the VFD series frequency converter driver through a set of inputs and outputs, which determine the set of functions of the power module. Currently, MEAN WELL does not have ready-made control module solutions, so users develop such solutions independently with the support of MEAN WELL partners.

For example, for VFD series connected to a 230V AC power supply, the complete scheme with a control module looks as follows:

Схема управления драйвером частотного преобразователя MEAN WELL VDF

Scheme of controlling the MEAN WELL VDF frequency converter driver

The inputs and outputs for controlling the frequency converter driver are connected to connector CN93.

 Разъем подключения модуля управления на драйвере VFD и его выводы

The connector for connecting the control module on the VFD driver and its outputs

Input control for power switches IGBT (three phases, upper and lower arms). The VFD power module contains three pairs of IGBT power switches. The switches are connected in a half-bridge configuration, forming a three-phase six-switch motor power supply scheme. All six IGBT switches are controlled by PWM signals PWM_UH / PWM_UL / PWM_VH / PWM_VL / PWM_WH / PWM_WL (pins 8-13). The input signals are compatible with TTL and CMOS levels with a voltage of 3.3V. Recommended connection:

Входы управления силовыми ключами драйвера VFD

Input control for power switches of the VFD driver

Control of current for each phase and overload protection. The VFD driver series includes three built-in current shunt resistors. The resistors are connected to the lower leg of each of the three phases, respectively. This signal can be used for internal protection of the VFD driver against current overload and/or fed to an external control module to determine the phase current. The recommended connection for this signal should be as short as possible to the operational amplifier of the reading circuit to most accurately determine the current value.

Выходы детекторов тока каждой фазы и защита от перегрузки драйвера VFD

Outputs of current detectors for each phase and overload protection of the VFD driver

Monitoring of the voltage on the DC bus of the VFD driver. VFD power modules have a built-in sensor for detecting the voltage on the DC bus – HV+ sensor. The output signal level is directly proportional to the voltage level on the DC bus of the VFD driver. When the bus voltage is 380V (for VFD models powered by AC) or 48V (for VFD models powered by DC), the HV+ signal will be at a level of 2.5V. Similar to the recommendations above for current monitoring of each phase, it is advisable to use an operational amplifier for the signal reading circuit of the HV+ sensor.

Контроль шины постоянного тока драйвера VFD

Monitoring the direct current (DC) bus of the VFD driver

Monitoring the temperature of the IGBT power switches. The VFD driver determines the temperature of the IGBT power switches using a built-in NTC resistor or temperature sensor. This signal can be used to design control functions or protection for the power switches and/or the VFD module as a whole. Below is the recommended connection diagram (except for the VFD-750C-230 model, which needs to be clarified in the specification).

Контроль температуры драйвера VFD

Monitoring the temperature of the VFD driver

VFD driver error signal. If there is an overload current in the VFD power module, a fault signal (active-low level) is generated. When the duration of the current overload exceeds tTripmin, the FAULT signal output changes state and notifies the external control scheme of the VFD driver error occurrence.

Формирование сигнала ошибки драйвера VDF

Generation of the VFD driver error signal.

Contact VD MAIS managers for more detailed information about the features of MEAN WELL VDF series frequency converter drivers.