elecric motor humming

sounds like your A/C compressor and not your electric motor. I wouldnt' worry about the radio in ACC mode. I've ran my radio for over an hour with no worry. I gradualy tested it to that time. First i would run for 20 mins. Then half an hour incrimated. Go into run mode and check the battery. It's fine. You could probably run the radio between an hour or two. I dought you have it blasting really high. Even if you do, it will still last a long time.

check to make sure your Air Conditioning is off when you leave the car. From what i've heard/experianced, it's only the electric compressor that makes noise when the car is sitting while on. Unless it's off.. then it's the coolant pumps.

 

Also what about the pump for the coolant going into the "thermos". It seems that the process goes on forever.

 

I hear a rapid clicking noise up front that lasts for 30-45 seconds. It starts 10-15 seconds after Power is shut off and I am outside the car with the door shut. It occurs regardless of the air conditioning having been on or off. I doubt if it's the cooling water pump because it even occurs after the car has been running on electric power only for the few minutes coming up the street and entering the garage.

It would be great if someone from the Prius design team would contribute to Prius Chat. We might get many of our questions answered.

 

Thanks Evan, I had assumed the coolant was transferred immediately upon each ICE shutdown.

I was a member of a Miata Forum where many of the original California design team participated openly. The Japanese Chief Engineer even participated occasionally. It made for a very interesting and informative Forum. A large number of the Miata Gen-2 design changes originated from discussions within the Forum. Also many design confusions, similar to those discussed in Prius Chat, became readily apparent when explained from the design team perspective.

 

some cars hum like that. I think it's the computers. Maybe with this car it's the inverter along with everything else. It's very slight right? I heard it a few times but i wouldn't say it's loud enough to bug me. Maybe you realized it because you have it on in your garage. I remember when the SUV's used to make a humming noise. I'm guessing it's the same thing, whatever that may be. So my final opinion is electronics. Unless somoene knows of Mg2 spinning when the system is supposed to be off.. I don't see why it would though.

 

This is just a guess, but I believe I heard (read?) that there is an inverter within the Hybrid system for converting DC to AC to support some of the electronics? If so, then that may be what you're hearing. Inverters generally hum at twice the frequency of the AC they are generating. I don't know what frequency(ies) would be required within the Hybrid system, so I can't say what frequency(ies) to listen for to confirm this guess.

 

if the car is stopped, MG1 and MG2 don't turn. MG2,(main drive motor) is connected to the differential with a chain thru an intermediate reduction gear, and MG1 is connected to MG2 thru the gear set in the PSD and as such can't rotate if the car is motionless. What you are probably hearing is the inverter assy with the 12 volt converter singing happily making 12 volts from 200+ volts. And if the car is really warm there is a water pump (electric) to circulate coolant thru the inverter.

 

<div class='quotetop'>QUOTE(Frank Hudon\";p=\"51285)</div>

I would love to see some technical information on the Hybrid drive, showing electronic, electrical, and mechanical system interaction and control schemes. The Energy screen is nice eye-candy, but give me schematics, block diagrams, mechanical drawings, and control logic descriptions, and I'll be happy for months! 8)

 

Re: electric motor humming

Is not the inverter responsible for converting the 200 or so volts DC from that batteries to 500 or so volts 'AC' (actually I wonder if it's more of a pulsed DC)? I could see that could make noise easily. The miniature version of such things in PC's etc you can occasional here a bit or a whine out of.

I too would love to see some schematics, or at least some block diagrams.

 

the function of the inverter is to convert the DC to AC, and under the instructions of the main computer to drive the car. The HV main battery is 200 nominal volts but probably about 245Volts at a 60% state of charge. As the car starts off it's under battery power so the main drive motor can't put out max power, as soon as the ICE starts it drives MG1 to produce up to 500 volts and I'm not sure of the amperage but probably in the order of 80 amps and sends it to the inverter to up the drive motors power output. Off the inverter is a converter to take the HV power and step it down to the 13.8 volts required to charge the aux battery and power the 12volt side of the car. One of the best sites to understand the relationship of the MG's and the ICE is this site.
http://homepage.mac.com/inachan/prius/planet_e.html
it does both the THS1 and 2 just push the slider and see what the rpm are for the MG's and the car and the ICE also note that the MG's are permanent magnet motor/generators and are capable of running in either direction at the wishes of the computer by starting and stopping the ICE. Hope this helps in your understanding of the car.

 

<div class='quotetop'>QUOTE(efusco\";p=\"51054)</div>

There is a good presentation on John's site...
http://john1701a.com/prius/presentations/2...entation_41.htm
The page 38 through 41 is the thermos related ones.

Anyway, this presentation is worth to read to understand 2004 Prius.

Regards,
Ken@Japan

 

Ken, thank you for the link to John's presentation. The information is just what I wanted for an overview of the Hybrid design concept.

 

Let me clarify some misconceptions.

The HV battery is only connected (through the power relays) in Ready mode. Thus the inverter, converter, and MG's are NOT in play in ACC or IG-On modes. I proved this by hooking up a voltmeter across the battery (jumper) terminals, and checked voltage in all modes. In all modes but ready, I was getting about 12V or less. In ready, I was getting 14V, which would be the converter providing charging/system power. So the inverter is not causing the whine. The A/C compressor can't be whining either, as it requires the HV battery also.

Now some would say, "well, the SOC is displayed in IG-On mode". This is true. However the Battery ECU is located in the HV battery assembly, and can read the voltages of the individual 7.2V packs, and give the results to the MFD through the gateway ECU. It is not at this time reading current coming out of the HV battery.

The whine can come from the cooling systems, of which there are 2. One is the inverter, the other is the engine. The engine coolant circulation is primarily mechanical, but is also provided electrically for cabin heating, and to transfer coolant from/to the thermos. The inverter coolant is circulated through an electric motor. You may be hearing this, as it does operate in IG-On. I do not believe it normally runs in ACC.

The cabin fan motor is another source of noise, though it would be obvious if this was the source, and would stop with the HVAC turned completely off.

Another source of noise is the brake hydrolic comressor. You normally only hear this if pressing the brake pedal.

The radiator cooling fan could also be a source, but again, this should be obvious.

In conclusion, I believe you are hearing the inverter coolant cirulation motor, but you shouldn't be hearing this in ACC mode (one push of power without brake pedal pressed).

Let me also clarify another misconception that was mentioned. The MG's run at 500V, powered by HV battery or each other. There is a voltage booster to double the HV battery voltage, so that less current is required for the same amount of power. This reduces resistance power losses.

 

have you put an AC volt meter on the motor terminals at start off? No hey? try it.

 

<div class='quotetop'>QUOTE(Frank Hudon\";p=\"52358)</div>

Have you? Doubt you would get anything without driving. Except for the voltmeter test, I am only going by the service manual (for the relay info) and the New Car information (for the 500V).

Now the coolant motor is a guess, but I am certain that the inverter is 'dead' (no high voltage) outside of READY mode. It might be possible the Hibrid ECU could be sending control signals to the inverter (I doubt it though), but without high voltage to the battery, not much the inverter could do about it.