With hybrid and electric vehicles finally making significant headway among consumers, sensors related to system electrification are on a fast track to solid market expansion, according to a new IHS Markit report on passenger-car-related electrification sensors.
Global revenue for vehicle-electrification sensors is projected to reach $2.8 billion in 2030, a remarkable fivefold increase from $526 million in 2018 that translates into a highly robust compound annual growth rate (CAGR) of 15.1% during the 12-year period. The solid growth in revenue, shown in the chart below, reflects both the low erosion rate of sensors for electric vehicles as well as their relatively high cost, compared to sensors for commoditized non-safety critical applications.
The most important devices in this market are current, temperature, and position sensors. Together, these three devices found their way into 34 new sensor slots in electric vehicles last year, with approximately half of those destined for monitoring the car’s electric battery—the heart of the electric vehicle. Multiple sensors are also being deployed in electric vehicles owing to the design imperative of redundancy, a deliberate measure undertaken to ensure the functional safety of electric vehicles.
The above findings can be found in the newly released Automotive electrification sensors special report – 2019, issued as part of the IHS Markit Automotive Sensor Intelligence Service.
Market and supply dynamics
Despite continued strong expansion, the market for electrification-related sensors will start to saturate after 2027, owing to the price erosion of sensors combined with a change in product mix in applications—such as the main traction motor—that will lean toward lower-cost solutions.
Suppliers of both resistive and magnetic current sensors will feel considerable market pull in the coming years, as will temperature sensor vendors. Position sensing supply will also become more dynamic as additional sensing technologies enter the market to compete with incumbent approaches.
Some of the leading companies for key sensing types are shown in the graphic below.
Suppliers of current sensors will benefit from the electric vehicle’s need to monitor all its key systems. Various solutions are available from a technology standpoint for current sensing, including shunt resistors, Hall ICs, xMR ICs, and fluxgate sensors. The application of a specific solution for current sensing depends on the range of the current being measured and other variables, such as the dimension of the current sensor as well as the accuracy and frequency of measurement.
In the low current range up to 10 amperes (A), shunt solutions will prevail because of their low cost and precision. As the current rises to above 10A, Hall IC-based devices can also be adopted.
Once the current range exceeds 100A, however, Hall-based sensors are mostly preferred since shunt solutions suffer from power-dissipation issues and difficulties with galvanic isolation at these levels of current. The main inverter, which is used to drive the main or propulsion electric motor, requires the highest current measurement range of up to 4000A. In general, switching frequencies will also increase, especially with the adoption of newer silicon carbide (SiC) or gallium nitride (GaN) power MOSFETs.
Fluxgate technology, meanwhile, has a higher precision and lower temperature drift compared to Hall and xMR sensors, but its bandwidth is much lower. The technology can be used for battery-pack busbars or on-board chargers requiring leak detection.
The encoder for the main traction motor makes for an interesting technological battleground for position sensing. Resolvers are the most popular approach today, with these bulky devices accurately measuring rotational angles as two-phase AC voltages with analog signals. However, resolvers do not lend themselves to redundancy, and in the future will allow other solutions based on magnetic or inductive technology to come into play.
Compared to resolvers, inductive and XMR devices are smaller and offer advantages in cost and flexibility when functional safety is being considered. It is easier to combine two sensors together in a small space, and there is an advantage in mixing two different types of sensors in a redundant system. Going forward, solutions based on resolvers, inductive sensors, and magnetic devices will all coexist in the market.
A factor influencing the choice of technology in position sensors is magnetic stray-field noise, the electromagnetic interference (EMI) incurred by big electric motors and the proximity of large current-carrying cables to magnetic sensors and their magnets. Typical EMI solutions today call for the use either shielding material or differential sensing to eliminate unwanted noise from the signal being measured.
To this end, inductive technology shows promise, as no magnets are involved that can be affected by stray fields. In fact, many companies are evaluating the technology as a potential route for high-stray-field environments in the powertrain of electrified vehicles.
Temperature sensors are a key protection device for the modules deployed in electric vehicles. Several technology types for temperature sensors exist, depending on the requirements for accuracy and the temperature for operation.
Typically, the applications needed for electric vehicles run up to a maximum of 150°C, and as a result are well served by negative temperature coefficient (NTC) thermistors—a set of devices that changes electrical resistance with temperatures based on a ceramic or polymer material, with an accuracy of ±2-3°C across the operating range.
NTCs, with their small size and low cost, make up most of the market for electrification applications today. However, NTCs suffer from non-linearities and require an analog digital converter (ADC) to turn analog signals to digital output.
Silicon-based ICs, on the other hand, cover a similar range of temperature from 90° to 130°C and possess higher accuracy—but at a price. These devices are used in applications such as the external air temperature probe placed in the front bumper; or as interface ICs for other temperature sensors, such as the thermocouples used on the exhaust.
For every electric motor, one to two NTC devices are used, depending on the number of electric motors in the propulsion system, to protect the motor from overheating. Prices for NTCs tend to be high because of the robust packaging requirements involved, such as a ceramic chip inside either the glass or epoxy package
The market for sensors is forecast for very strong growth given the need to monitor new systems in electrified vehicles. Suppliers of resistive and magnetic current sensors along with temperature sensor vendors will feel considerable market pull in the coming years, benefiting their prospects. Suppliers of position sensing, meanwhile, will become more dynamic as additional sensing technologies make their way into the market. Overall, companies aligned with these markets stand to profit greatly from the electrification trend for at least the next decade.