To further reduce the weight and size, DENSO improved the packaging by repositioning the ecompressor 's inverter in-line with the motor as opposed to the current integrated inverter that is stacked above the compressor 's motor. (Fig. 7) Nissan Figure 2: Nissan Leaf has an optional heat pump that uses a control unit to control the direction of refrigerant flow leaving the HV (High Voltage) electric compressor (via pins 6 & 7). Temp sensors on both suction and discharge ports of the compressor (pins 8 & 11) provide feedback to the control unit regarding the status of flow. The bus communicates with the HVAC amp (programmer) via a LIN bus signal. velop a new cooling method using air conditioning refrigerant in the compressor, because the conventional main DC-AC inverter is cooled by a dedicated liquid cooling system. Dave Hobbs Shop Key Pro / Mitchell ferable to the cabin just by the power consumption of the pump. 2-way and 3-way valves are electrically controlled by the heat pump controller (Fig. 2) and in the case of EVs and PHEVs, the BCM gets involved with a serial bus message between the HVAC control head / amplifier and the heat pump control module. Figures 6 and 7: The Ford Focus Electric came out in 2011 with the newer more compact design Denso compressor that moved the AC inverter from the top of the compressor (Fig. 6 left) into the compressor housing. (Fig. 7 right) The newer design contains the integrated inverter in the end housing of the electric compressor (makes it even smaller) and is used on newer Fusion and C-MAX models that have the Energi Plug-in option. Nissan's updated electric A/C compressors Leaf's Heater Not Hot Enough? The original GEN II Prius (2004-2009) was fed high voltage 3-phase AC power courtesy of the vehicle's main inverter. (Figs 3-5) In 2005, Denso came out with a compressor that had the two DC HV (High Voltage) cables attached leading into mini DC-AC inverter (Fig. 6) mounted directly on top of the electric compressor. Because power electronics (inverters & DC-DC converters) normally require liquid cooling systems, housing the inverter to create 3-phase AC from DC on the compressor required some new technologies. They had to de- Dave Hobbs Automotive research engineers are looking beyond the current, range-limiting HVAC systems on EV's. Gas engines produce a lot of free heat that becomes useful for heating passenger cabins when the temps are cold outside. EVs and PHEVs on the other hand only produce a little heat in the way of PE (Power Electronics) systems (DC-AC inverters / DC-DC converters), so there's no free ride to produce heat. An electric heater even using the advantage of higher voltages can reduce an EV's driving range by as much as 40%. Figures 3, 4 and 5: The original A/C compressors for hybrids looked like this Denso compressor (Fig. 3 left) off of a GEN II Prius (2004-2009). Note the three terminals in the orange connector. One terminal for each of the three phases of AC high voltage created by an inverter circuit dedicated for the A/C compressor located within the vehicle's main Power Electronics inverter. (Fig. 4 center) A permanent magnet rotor turns the inner scroll mechanism that all electric compressors are using. Failure to use the correct refrigerant oil in the system can not only void the warranty but also have the potential to set a high voltage DTC that would eventually shut down the A/C system as the stator windings begin to break down. (Fig. 5 right) December 2017 2 MACS Service Reports