Motor Control Trends in Electric Vehicles (EVs)

Electric Vehicle Component Market

The Electric Vehicles (EV) industry has been developing rapidly in recent years. Global sales of EVs have reached 6.7 million. Looking forward to CY2030, global sales of EVs are expected to reach 47.8 million, which will account for about 50 percent of new passenger vehicles sold. China’s EV sales volume was 3.33 million units in CY2021 and it is expected to exceed 6 million units in CY2022.

EVs need more electric motors than a traditional vehicle for several reasons. They need to replace any belt or crank/cam shaft-driven accessories such as pumps, compressors and actuators. They also require motors for new systems such as electronic control coolant pumps. While lower cost Brushed DC (BDC) motors could be used, Brushless DC (BLDC) motors provide key benefits which are particularly important to EVs: 

• Better energy efficiency
• Quieter operation using sinusoidal control
• Improved reliability and prolonged motor life

Taking vehicle electronic water pumps as an example, an EV needs more than a traditional combustion engine vehicle. An EV needs to implement temperature controls for three new systems: the high-voltage battery pack, the traction motors and the traction motor inverter electronic control boards. An average of three electronic water pumps are required per EV, and the cost of an electronic water pump is more expensive than a traditional belt-driven mechanical pump.

Cooling Fans in an Electric Vehicle

Another example is the cooling fans in a vehicle. Traditional fuel vehicles typically provide one BLDC engine cooling fan for the up-front radiator, but some models with larger engines come equipped with two. EVs have up to three radiator fans. Although there is no engine to cool, they help cool the high-voltage battery pack and traction motor inverter electronic control boards. You can hear these fans continuing to run after the EV is turned off or when recharging its high-voltage battery pack.

There can be additional BLDC motors used in the EV HVAC system. Traditional fuel vehicles drive the HVAC compressor using an engine belt, but an EV needs an electronic motor to drive the compressor directly. The HVAC system also requires a BLDC motor-based fan to circulate the air flow.

Heat Pump in an Electric Vehicle

In addition, the structure of most modern electric compressors supports the function of a heat pump (one more BLDC motor) and some EVs include one. The heat pump is a system which includes solenoid expansion valves and refrigerant lines for heat exchange, working like an A/C in reverse. The advantage of the heat pump system is that the operating efficiency can be 3 to 4 times higher than a resistive element Positive Temperature Coefficient (PTC) heater. However, it only works well in an environment  >-20 °C.

PTC heating is also commonly used for EV cabin heating and works at any temperature. Although it is nearly 100 percent efficient at converting energy to heat, the big disadvantage of a PTC is that it consumes a lot of battery energy. Using a PTC heater can significantly reduce the distance that an EV can be driven before needing to recharge its battery in a cold environment.

Thermal Management Systems (TMSs) are a new trend in EVs. They combine and coordinate the controls for the HVAC system, including heating and cooling compressors, air circulation fans, expansion valves and actuators with the high-voltage battery pack and traction motor inverter boards temperature control, including heat recovery and reuse. A TMS can significantly enhance the overall function of an EV and the market potential for a TMS is very big. Such complex control systems also require ISO26262 functional safety and AUTOSAR® support.

In summary, there are more BLDC motors in EVs, and consequently more motor control MCUs are required. As everyone knows, the requirements for semiconductors in EVs is very high, including motor control MCUs. The following are some basic requirements:

• High CPU clock frequency
• Motor control dedicated peripherals
• AEC Q100 grade 0 certification (-40°C to +150°C)
• Functional safety and AUTOSAR support

dsPIC33CK Digital Signal Controllers (DSCs) for Motor Control

Microchip’s dsPIC33CK Digital Signal Controllers (DSCs) are specifically designed for motor control. They feature a unique hybrid core (MCU and DSP components), supporting efficient DSP instruction execution without having to bear the high cost of DSP chips. The DSCs integrate internal high-precision RC oscillators and many high-performance analog peripherals, including 12-bit ADCs (3.5 Msps) with 10.5 ENOBs, fast 15ns analog comparators with 12-bit DACs for the voltage reference and high-precision operational amplifiers. These reduce external components on the customer's motor control board, thereby saving space and cost.

The dsPIC DSCs operate over a wide ambient temperature range of -40°C to +150°C. In addition, their AEC Q-100 grade 0 automotive qualification makes them very suitable for automotive and industrial motor control applications. Many safety features, such as DMT, WWDT, FLASH OTP and more, are included in the design to enhance functional safety. Combined with Microchip’s function safety manual, FMEDA report and dynamic diagnostic code, dsPIC33CK DSCs can help customers simplify the process of obtaining functional safety ISO 26262 certification.

In addition, Microchip provides a very comprehensive ecosystem of motor control hardware development tools and software algorithm support. For example, a free software Graphical User Interface (GUI) called motorBench® Development Suite enables you to start up and run a BLDC motor in minutes using a Field Oriented Control (FOC) algorithm. Another free tool called X2C-Scope is an electronic oscilloscope, which greatly facilitates debugging motor operation or any application code from a PC.

dsPIC33CH Dual-Core DSCs for Motor Control

Microchip’s dsPIC33CH dual-core DSCs are ideal for combining the control of multiple BLDC motor-based water pumps and/or cooling fans into one controller to save money and space. These DSCs have two independent cores running up to 100 MHz each with all the motor control peripherals needed to support two or three BLDC motors.  

Learn more about dsPIC® DSCs and motor control and drive for more information about Microchip’s motor control solutions.