1. Profile

Electric vehicles are vehicles that use batteries (ie, “battery packs” in pic.1), driven by electric motor, and comply with the requirements of road traffic and safety regulations. DC power supply used in electric vehicle motor test, simulate automotive batteries for the motor to provide test conditions.


Test construction

SPD-PWM Series of digital, programmable electric vehicle testing DC power source is meet the Chinese standard ”GB/T 18488.1-2015  Drive motor system for electric vehicles”, designed for the manufacturer of electric motor, electric motor controller, electric vehicle for the product testing. The SPD-PWM uses IGBT technology and amorphous core as the core device which combined with “Soft-Switching,” provides superior performance and a high level of user control through the front panel and remote interfaces. It can simulate the battery on the electric vehicle to test input power, touch current, overload capability, hipot voltage for the motor controller, and test the performance of efficacy, stall current, maximum speed, over speed and feed current of the electric motor. Also, it could protect the electric motor and the controller by absorbing back electromotive force during over speed testing.


  1. Product Features

The output voltage and current value are pre-set, zero to certain value could be continuously adjusted. It has constant voltage (CV) and constant current (CC) mode automatic switching, indicate the working mode via LED light.

  • High accurate and low ripple

Using the peak current controlled to ensure high accurate of the output voltage and current, excellent regulation rate. Equipped multi-stage filter for low ripple output.

  • Full digital control

Full digital control, programmable output voltage and current. Full digital calibration, stable and reliable.

  • Remote testing control

Built-in RS485 and RS232 interface, MODBUS protocol supported. Multi-machine communication available, remote monitor the parameters and status of the power supply.

  • Discharge control system

Absorbing back electromotive force (BEMF) instantly during overspeed testing. Automatic discharge when voltage feedback is 5V-10V higher than the output voltage. Discharge power could be customized. Energy consuming time is 30s (count from brake to stop), voltage dropping time is 10s.

  • Discharge circuit independent

Discharge circuit maintains working when IGBT main circuit cut off the power. Control discharge circuit from the front panel.


 Testing DC power supply


  1. Power Supply
System Solution High-frequency convert technology base on ZVZCS + Resistance discharge
Power supply modular design, composed of four 500V50A power supply module.
Input Input Voltage Three phase 380V±15%
Frequency 47-63HZ
Single Module output Output Characteristics CV & CC
Voltage Setting Method Digital input or manual turning
Output Voltage Range 0-500V adjustable
Soft Start Function 2-5s
Rated Output Current 50A
Output Current Range 0-50A adjustable
Voltage Stability Source voltage effect (Variation ±10%): ≤0.5% rating value
Time-drift (over 8 hours continuously working): ≤0.5% rating value
Temperature-drift: ≤0.5% rating value/℃
Load effect (0 adjust to rating value): ≤1% rating value
Ripple Full load effective ripple: < 0.5% rating value +10mV
Full load ripple peak: < 5%
Efficiency >90% @ 100% load
Display LED Voltage Meter 4 digit LED display Accuracy: ±0.5%rdg+2digit Resolution: 0.1V
LED Current Meter 4 digit LED display Accuracy: ±0.5%rdg+2digit Resolution: 0.1A
Status Indication Working, standby, over voltage, over current, over heat, lack phase, short circuit status indication
Protection Lack Phase Protection Lack-phase protecting and warning
Over Voltage Protection Input voltage higher than 445±5 V, stop working and warning
Under Voltage Protection Input voltage lower than 323±5 V, stop working and warning
Output OVP Output voltage 5V higher than setting (Customizable), protect object and warning
Output OCP Output current higher than 200A (Customizable), limit current
Over Heat Protection >85℃ protect object and warning
Emergency Stop External emergency stop button
Alarm function Sound-light Alarm Warning display and noise alarm
Dry Contact Emergency stop with alarm and node signal output
Insulation Dielectric Strength Input against case: AC2500V/1min., leak current 10mA
Input against output: AC3000V/1min., leak current 10mA
Output against case: AC3000V/1 min., leak current 10mA
Insulation Resistance Input against case: DC1000V, >20MΩ
Input against output: DC1000V, >20MΩ
Output against case: DC1000V, >20MΩ
Working Condition Storage Temperature -20℃ to +50℃
Working Temperature -10℃ to +40℃
Relative Humidity ≤95% (no condensation)
Ingress Protection IP20
Atmospheric Pressure 80-106KPWM (2000m b.s.l.)
Noise < 65 dB at 1 meter
Cooling Device Forced air cooling
Working Time Enable long-term full loading continuous working
Computer Remote Control Provide RS485 and RS232 interface to remote and monitor power supply, setting output voltage, current, and protection
Three-proof Meet national standard
Impact resistance, Anti-vibration Meet national standard
  1. Resistive automatic discharge technical indicators
Discharge Voltage Feedback voltage 5V-10V higher than output voltage or pre-set discharge voltage (0-800V)
Control Method IGBT and PWM
Discharge Power 30KW (60KW shorter time)
Energy Consuming 30s (count from brakes to stop) voltage dropping time: 10s
Feature Discharge circuit independent control, circuit maintain working when the IGBT main circuit cut off the power. Control discharge circuit from the front panel.



SPD-PWM series high-frequency high power DC power source composite by the shown parts:

power supply construction

  1. Main Circuit

From the AC input DC output of the whole process, including input filter, rectifier filter, inverter and high-frequency rectifier and filter.

  1. Controller Circuit

In one hand from sampling the output power, compared with the setting values, control the DC power supply, change its frequency and pulse width, to achieve stable output; In other hand, according the data that provided by the circuit, the protection circuit will identify data and provide a variety of protective measures.

  1. Drive Circuit

Transfer the signal from the control circuit to do phase separation, isolation and amplification, drive DC power supply. And provide auxiliary power and a variety of protection signals.

  1. Setting Circuit

Detecting and display the output voltage, current. At the same time the operator can adjust the output voltage through this circuit.



  1. Panel Detail

power supply panel

Order Name Function
1 LED Display Display setting values and output voltage and current
2 Indication Light Indicate working model and status
3 Function Button See the following description
4 Voltage Regulation Turning button to adjust voltage under manual model
  1. Button Description
【Start】 Start output power
【Stop】 Stop output power
【Setting】 Setting currency display data, confirm by press again.
【Cancel/Mute】 Cancel data setting, Fault Sound cancel
【Up】 Selecting items and turn up value.
【Down】 Selecting items and turn down value.
【Left】 Selecting items
【Right】 Selecting items
  1. Setting Description

All parameters are defined in the following table, the variables in the table below can be viewed, modified, can also be operated by the host computer.


Order sign Parameter unit variable note
1 20.0  10.0 Display current power no Display values
2 OUP Limit voltage V yes Protection setting
3 Addr Communicate addr. yes 0~254
4 SrUn Power-on auto-run V yes 1 for true;

0 for false

5 ASEt Current setting A yes CC setting
6 USEt Voltage setting V yes CV setting
7 U1n Phase voltage V no Display values
8 Io Current A no Display values
9 Uo Voltage V no Display values
  1. Letters and Numbers Mapping

Because the seven-segment display has limit stroke, can’t exactly show all the letters and numbers, so some of using special strokes. The mapping table is as follows:


  1. Interface description


Order Name Function
1 Panel/manual switching Press down, manual mode; Press up, panel control.
2 Remote/local control Press down, host computer control; press up, panel control.
3 RS232
4 RS485 See firmware connection for remote control and test
Four-wire load-side compensated terminal Customized part



  1. Display
  • Display using industrial-grade touch screen, built-in WinCE OS
  • 7 inch TFT LCD screen, 800×480 resolution, 65535 true colors.
  • Cortex-A8 CPU.
  • Modular design, easy to install, easy to expand.
  • Automatic energy-saving design, automatic distribute each module’s output according to the setting value.
  • Safe and reliable host computer monitoring function, using the standard ModbusRTU protocol.
  1. Interface Function
  • Main interface

main interface

Data view: When system power on, it will display into the boot self-test program, when it was done, automatically into the main interface. It shows the current output and set value.

Output setting: click on the ‘setting’ can open the setting page, set the value you need. The output will change to the setting value when it is running; Or, you have to start running to get the setting output.

  • Power Module Info

power module info interface

The system built up by several modules, status and data could be viewed through this window. The status bar will show the status of power supply, easy to locate the malfunctioned module.

  • Logs

logs interface

Logs page record all the operations and module status, cycle record at least 1000 records. These records order in descending by time.

  • System Setting

setting interface

Enter setting page by input user account and password. Setting items including output, remote addr., short-circuit protection, time and password.

setting interface

The setting page also could select power module, enable/disable loading module. The default is selecting all the power module, the user could certain module to work, unload module will under ‘disable’ status.



  1. Profile

Using “SPD MONITOR” could remote control and testing.

“SPD MONITOR” is a managed software that monitors the SPD-PWM series of power supplies. The system is suitable for all SPD-PWM series power supplies of our company. Before implementing the SPD MONITOR software to monitor the power supply, you need to purchase or make a dedicated communication cable to connect the RS485 interface of the power supply to the computer. Through this software, you can complete all the functions that the front panel could operate, such as setting the voltage, setting the current, and the limit voltage for the work.

  1. Firmware Connection

As the following picture, the hosting computer connects testing system by RS232-RS485 converter,if computer no RS232 port, USB-RS232 converter also available.

remote connecting

Each RS485 converter could monitor at least 32 units power supply default. Customized 254 units power supply at most to connect.

  1. Software installation
  • Basic config of the computer

Pentium III, Pentium IV or above level.

Windows 98/2000/XP or Windows NT4.0 OS

  • Installation

Insert the disc of SPD MONITOR software into the CD-ROM drive of the computer and follow the prompts displayed step by step until the installation is complete.

  1. Software Function
  • Main interface

software main interface

View all the data and status through the main interface.

  • SPI setting

IPS port

Set the serial port for communication according to the actual physical connection. As shown below, select and click OK. Serial port as far as possible mapping in No.1 to 9 port, larger than no.10 will cause problems. The actual serial port address can be viewed and modified by the Device Manager.

  • Communicate address

comunicate addr

The communication address is the physical address of the DC power source, which can be viewed and modified by the panel of the DC power supply. The address and setting here refer to the physical address of the monitored power supply. By changing this parameter, the monitored power supply can be changed.

Set the address and press OK to confirm, press Cancel will continue to monitor the original address.

  • Communicate status

Through this state, you can check whether the communication is normal, the cause of the error.

  • Parameter setting

The monitored power supply in the remote state could be set the output parameters through the host computer: voltage setting, current setting. Could also start and stop the output of the monitored power supply.


Customize is available, here is a sample product: 100KVA Programmable DC Power Source for electric vehicle motor testing