Power Supplies for DC Motor Evaluation
DC Power Supplies for Driving Motors
Here are some examples of DC-driven motor applications.
When running a DC motor, the power supply unit usually simulates an onboard battery. Depending on the type of evaluation, the use of the power supply and the required functions vary.
For the simplest evaluation, the DC power supply is set to the drive voltage of the motor to provide power. The required capacity of the power supply is determined based on the current needed to drive the motor.
The power supply can be used as a battery substitute. When a large current flows at startup, such as in a starter motor, it is necessary to select a power supply considering the inrush current (rush current).
The variable internal resistance function* is recommended when simulating a drop in battery voltage as specified in standards such as ISO 8856, JIS D1607, LV124, or LV148.
*Custom modifications are required for the PAT-T series.
Furthermore, the PXB series of bidirectional DC power supplies can be used for power fluctuation testing, back EMF, and variable internal resistance.
Key features to have are
variable internal resistance, large capacity, and compact size.
At this point, it is important to check the rush current generated at the motor startup.
Furthermore, when considering changes in internal resistance due to battery degradation, it is recommended to use a power supply with a variable internal resistance function. Since external resistors are not required, the testing process is significantly simplified.
Drive Power Supplies Built to Handle Back EMF
Here is an example of handling the back EMF generated during DC motor braking.
In DC motor testing, when a sudden stop or braking control generates a back EMF, power is regenerated to the power supply. If a general-purpose switching power supply is used, the back EMF causes stress on the power supply output side.
In such cases, usually, an electronic load or resistor is installed to absorb the reverse current flow.
Our products can be used as a battery replacement. When back EMF is generated from the motor, as in this example, the back EMF can be absorbed by combining an electronic load device (PLZ-5W, etc.) with the power supply.
If a large current must be generated in a short period of time, a high-capacity DC power supply is required. A bipolar power supply can be used if the capacity is up to 1,000 W.
For large capacities of 20 kW or more, a bi-directional DC power supply is recommended.
For Supplying and Absorbing Both Voltage and Current,
Bipolar Power Supplies with 4-Quadrant Operation
The PBZ series of bipolar power supplies can be used when the motor capacity is less than 1000 W.
Bipolar power supplies support four-quadrant operation, supplying and absorbing both voltage and current. This makes conducting tests with the power supply alone possible, even when back EMF is generated.
Power and Regenerate 20kW of Current in Just One 3U Supply
This product can be used for a large-capacity motor evaluation. One unit can handle ultra-large capacities of 20 kW and, when used in parallel, 200 kW. Three types of voltages (500V/1000V/1500V) are available.
PWM-Controlled Motor Evaluation
Here is an example of PWM speed control.
For DC motors, such as fan motors that require PWM control, we recommend using the PBZ series of bipolar power supplies.
In addition to the 12 volts constantly supplied by the battery, the fan speed is regulated by an external PWM-controlled voltage.
In some cases, the onboard PWM-controlled motor is constantly supplied with voltage from the battery.
Since the battery voltage is constant, a PWM signal source separate from the drive power supply is required to control the fan’s rotational speed.
Key features to have are
High speed, high voltage, and support for 0% duty cycle.
In fact, it’s not always possible to set the duty cycle of the PWM to 0%.
For example, only high-quality signal generators would have this capability. With the PBZ series of bipolar power supplies, it is possible to set the PWM duty cycle to 0% using the Wavy for PBZ sequence software.
PWM control can be achieved without an expensive external signal source.
The speed of the motor shown in the example increases as the duty ratio of the PWM signal rises, and when 0% Duty is reached, the FAN stops rotating.
At this moment, the output voltage of the PWM signal source must be equal to the constantly supplied battery voltage.