• Mazda M Hybrid is a regenerative braking system which consists mainly of three parts, a integrated starter generator (ISG), a capacitor (Mazda M Hybrid), and a DC-DC converter (Mazda M Hybrid). Kinetic energy occurring when the vehicle decelerates in the fuel cut range during deceleration is converted to electrical energy by the integrated starter generator and stored in the capacitor (Mazda M Hybrid). The stored electricity is used as power for the vehicle’s electrical devices (such as A/C, audio unit), and reduced fuel consumption can be expected by the minimized loss of engine output (integrated starter generator operation loss). Mazda M Hybrid uses the ISG with excellent power generation efficiency to generate electricity from the kinetic energy generated when the vehicle decelerates.The system uses the electrical power stored in the capacitor, which is a battery to improve driveability and fuel economy by reducing engine load and providing motor assist. In addition, the ISG provides quiet engine restarting after the engine is stopped by after the i-stop function (idling stop).
• A integrated starter generator has been adopted which can generate 12—24.3 V according to the vehicle and capacitor (Mazda M Hybrid) conditions. Using the characteristic of electricity in which current flows to the low electrical potential from the high electrical potential, electricity can be stored in the capacitor (Mazda M Hybrid) by generating higher voltage than the capacitor (Mazda M Hybrid) voltage.
• A capacitor (Mazda M Hybrid) has been adopted as a condenser which can instantaneously store large amounts of electricity generated by the integrated starter generator. A characteristic of the capacitor (Mazda M Hybrid) is its ability to supply electricity quickly when it is used. The capacitor (Mazda M Hybrid) stores the voltage generated by the integrated starter generator (maximum of 24.3 V).
• A DC-DC converter (Mazda M Hybrid) has been adopted which supplies electricity to the vehicle’s electrical devices by lowering the voltage (maximum of 24.3 V) stored in the capacitor (Mazda M Hybrid).
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Structural View
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• Mazda M Hybrid consists mainly of the following parts.
• The regenerative braking mode generates electricity at the integrated starter generator in the fuel cut (deceleration regeneration) range during deceleration and stores electricity in the capacitor (Mazda M Hybrid). The PCM determines the integrated starter generator power generation amount according to the capacitor (Mazda M Hybrid) voltage and stores the electricity in the capacitor (Mazda M Hybrid). When the capacitor (Mazda M Hybrid) voltage reaches 24.3 V during deceleration regeneration, the PCM determines that the capacitor (Mazda M Hybrid) is fully charged and limits the integrated starter generator output.
• Although the regenerative braking mode is mainly for the purpose of storing electricity in the capacitor (Mazda M Hybrid), the electricity generated by the integrated starter generator is supplied to the vehicle’s electrical devices and battery via the voltage reduction circuit in the DC-DC converter (Mazda M Hybrid).
Note
• The electricity output from the voltage reduction circuit is supplied to the vehicle's electrical devices and battery because the voltage after the voltage reduction circuit in the DC-DC converter (Mazda M Hybrid) is higher than the voltage applied to the battery voltage and vehicle's electrical devices.
Operation condition
• During fuel-cut by release of accelerator pedal and TCC
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2. Conventional power generation mode (no regenerative braking)
Purpose
• If the capacitor (Mazda M Hybrid) voltage is the specified value or less while the engine is running, electricity generated by the conventional power generation mode (non-regenerative braking) is supplied to the vehicle’s electrical devices. Because the capacitor (Mazda M Hybrid) at this time lacks sufficient electricity to supply power to the vehicle’s electrical devices, fuel is consumed and electricity is generated by the integrated starter generator for the purpose of assuring a power supply to the vehicle’s electrical devices.
• Although the integrated starter generator generates constant voltage the same as that of the previous-type power generation mode, it can actually generate between 12 and 24.3 V. The integrated starter generator remains on stand-by so that reduction regeneration is performed as soon as the operation condition of the regenerative braking mode is met.
Note
• Although the relay operation condition in the DC-DC converter (Mazda M Hybrid) is the same as the regenerative braking mode, engine drive force is used for generating electricity in this mode.
• The conventional power generation mode cannot store electricity sufficiently in the capacitor (Mazda M Hybrid) because the generated power amount is lower compared to the regenerative braking mode.
Operation condition
• Capacitor (Mazda M Hybrid) voltage is specified value or less with engine running.
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3. Capacitor (Mazda M Hybrid) power supply mode
Purpose
• If the capacitor (Mazda M Hybrid) voltage is higher than the battery voltage, the capacitor (Mazda M Hybrid) power supply mode lowers the voltage stored by the capacitor (Mazda M Hybrid) using the DC-DC converter (Mazda M Hybrid) to supply power to the vehicle’s electrical devices.
• The integrated starter generator does not generate electricity while in the capacitor (Mazda M Hybrid) power supply mode and power is supplied to the vehicle’s electrical devices using the capacitor (Mazda M Hybrid) electricity regardless of the driving conditions (such as during acceleration) as long as the capacitor (Mazda M Hybrid) voltage is higher than the battery voltage.
Note
• The capacitor (Mazda M Hybrid) voltage lowers gradually because the electricity stored in the capacitor (Mazda M Hybrid) is used while in the capacitor (Mazda M Hybrid) power supply mode. If the capacitor (Mazda M Hybrid) voltage is the specified value or less, the DC-DC converter (Mazda M Hybrid) stops the operation of the capacitor (Mazda M Hybrid) power supply mode.
Operation condition
• Capacitor (Mazda M Hybrid) voltage is specified value or more.
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4. Battery power supply mode
Purpose
• The battery power supply mode supplies power to the vehicle’s electrical devices from the battery.
• The same as in conventional vehicles, battery electricity is supplied to the vehicle’s electrical devices and the starter during cranking (except when engine is restarted by i-stop). Battery electricity is supplied to the vehicle’s electrical devices in the same way whether the ignition is switched to ACC or ON (engine off).
• The battery power supply mode operates even while the engine is stopped by i-stop control. The electricity stored in the capacitor (Mazda M Hybrid) is supplied to the vehicle’s electrical devices while the engine is stopped by i-stop control (capacitor (Mazda M Hybrid) power supply mode). After that, if the capacitor (Mazda M Hybrid) voltage is the specified value or less, battery electricity is supplied to the vehicle’s electrical devices to stop the capacitor (Mazda M Hybrid) power supply mode and continue to stop the engine by i-stop control.
Operation condition
• Under any of the following conditions:
― During engine cranking
― Ignition is switched to ACC or ON (engine off)
― When capacitor (Mazda M Hybrid) voltage is specified value or less while engine is stopped by i-stop control.
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5. Motor assist
Purpose
• The ISG is driven using the charged electrical power in the capacitor (Mazda M Hybrid) during acceleration. Fuel economy is improved by suppressing the load applied to the engine.
Operation condition
• The charge state of the capacitor (Mazda M Hybrid) is a certain value or more during engine rotation.
Operation content
• The ISG is driven using the charged electrical power in the capacitor (Mazda M Hybrid) to assist the engine. Also, electrical power is supplied to the vehicle’s electrical devices through the DC-DC converter (Mazda M Hybrid).
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6. Engine restarting by ISG
Purpose
• The ISG is driven and the engine restarts quietly and quickly.
Operation condition
• Engine restart by i-stop control (engine stop control)
Operation content
• The ISG is driven using the charged electrical power in the capacitor (Mazda M Hybrid) to restart the engine. Also, electrical power is supplied to the vehicle’s electrical devices through the DC-DC converter (Mazda M Hybrid).
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7. By-pass mode
Purpose
• When the power consumption of the vehicle’s electrical devices exceeds the output limit of the voltage reduction circuit in the DC-DC converter (Mazda M Hybrid), or the capacitor (Mazda M Hybrid) voltage is low, the bypass mode turns the bypass relay on and supplies electricity generated by the integrated starter generator directly to the vehicle’s electrical devices via the bypass relay.
Caution
• i-stop control is inhibited in the bypass mode because the vehicle’s electric load is high.
Note
• Because the electricity generated by the integrated starter generator is supplied directly to the vehicle’s electrical devices and battery without passing through the voltage reduction circuit in the bypass mode, the voltage generated by the integrated starter generator is controlled by the PCM at the rated voltage of the vehicle’s electrical devices.
Operation condition
• When any one of the following conditions is met:
― Vehicle electric load is high (current consumption is 75 A or more)
― Any one of Mazda M Hybrid parts (capacitor (Mazda M Hybrid)/DC-DC converter (Mazda M Hybrid)) is malfunctioning.
― Capacitor (Mazda M Hybrid) voltage when ignition is switched ON (engine off): Less than 7.5 V
― Battery charge condition: Less than 65%
― Voltage reduction circuit temperature: 131 °C {268 °F} or more
― Bypass relay temperature: 125 °C {257 °F} or more
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*1: If the vehicle electric load is high (current consumption is 75 A or more), the electricity generated by the integrated starter generator is supplied to the capacitor (Mazda M Hybrid) with the capacitor (Mazda M Hybrid) relay ON.
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8. Pre-charge mode
Note
• If the capacitor (Mazda M Hybrid) continues to self-discharge (vehicle left for long periods with engine not started)/excess back-up current consumption, the pre-charge mode may operate due to the decrease in capacitor (Mazda M Hybrid) voltage.
• If the vehicle is jump started, leave the jumper connected until the warning message is no longer displayed.
• If vehicle is driven while the warning is displayed, a warning sound will be heard and power steering assist will be limited.
Purpose
• The capacitor (Mazda M Hybrid) charges for the following two reasons.
― If the capacitor (Mazda M Hybrid) voltage is low, the excitation current to the generator lowers and the generator may not be able to generate power.
― To supply power to the battery from the capacitor (Mazda M Hybrid), a higher electrical load than the battery is required.
Operation condition
• If the capacitor (Mazda M Hybrid) voltage is a certain value or less (stops operation when capacitor (Mazda M Hybrid) voltage reaches certain value or more.)
Operation content
• Depending on each type of condition, the method for charging the capacitor (Mazda M Hybrid) varies.
Condition
Power supply method
Instrument cluster display
Negative battery cable is connected
Power supplied from battery to capacitor (Mazda M Hybrid)
Not applicable
Ignition switched ON (engine off) while engine is stopped
Power supplied from battery to capacitor (Mazda M Hybrid)
Not applicable
Engine is started
Power supplied from generator to capacitor (Mazda M Hybrid)
Applicable
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*1:Audio unit (without center display), tuner and amp unit (with center display), parking sensor control module (with parking sensor system), climate control unit (full-auto A/C), auto light sensor/rain sensor, instrument cluster, rear mount camera (with rear mount camera/predicted vehicle path assist lines display type), commander switch (with center display), clock (manual A/C)
*2:Electrical devices other than electrical device
*1
• The PCM sends a message display request signal to the instrument cluster during capacitor (Mazda M Hybrid) pre-charge when the engine is started.
• If the vehicle is driven while “Mazda M Hybrid charging” is displayed in the multi-information display, the PCM sends an Mazda M Hybrid warning light to the instrument cluster.
• A message display request signal is sent for a maximum of 3 min and if the message display request condition continues for 3 minutes or more, the PCM sends a master warning light request and message display request to the instrument cluster or the connectivity master unit (CMU).
9. Capacitor (Mazda M Hybrid) power generation mode
Purpose
• When the capacitor (Mazda M Hybrid) voltage is the specified value or more with the ignition switched OFF, the capacitor (Mazda M Hybrid) discharging mode charges the battery using the surplus power stored in the capacitor (Mazda M Hybrid). The electricity stored in the capacitor (Mazda M Hybrid) is lowered by the DC-DC converter (Mazda M Hybrid) and power is supplied to the battery.
• If the battery voltage is high and power cannot be supplied from the capacitor (Mazda M Hybrid) to the battery, the discharge relay is turned on and the capacitor (Mazda M Hybrid) voltage is discharged until it is the specified value or less.
Note
• If a condition continues for a long period in which the capacitor (Mazda M Hybrid) is close to being fully charged, the capacitor (Mazda M Hybrid) performance (such as internal resistance, capacitance) may decrease. Therefore, when the ignition is switched OFF, the capacitor (Mazda M Hybrid) performance is maintained by charging the battery using the surplus power in the capacitor (Mazda M Hybrid) and discharging the capacitor (Mazda M Hybrid) electricity.
• To assure safety for servicing, if the DC-DC converter (Mazda M Hybrid) detects that the hood is open, it stops supplying power from the capacitor (Mazda M Hybrid) to the battery, turns the discharge relay on, and discharges the capacitor (Mazda M Hybrid) voltage until it is the specified value or less.
Operation condition
• When any one of the following conditions is met:
― Capacitor (Mazda M Hybrid) voltage is the specified value or more with ignition switched OFF
― Hood is open
When power is supplied to battery
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When power cannot be supplied to battery
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• The following are examples of the Mazda M Hybrid operation in each mode.
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• The following are the relay conditions for each operation mode.
×: Relay ON—: Relay OFF
Operation mode
Capacitor (Mazda M Hybrid) relay
Discharge relay
Pre-charge relay
By-pass relay
i-stop relay
1.Regenerative braking mode
×
—
—
—
×
2. Conventional power generation mode (no regenerative braking)
×
—
—
—
×
3. Capacitor (Mazda M Hybrid) power supply mode
×
—
—
—
×
4. Battery power supply mode
×
—
—
—
×
5. Motor assist
×
—
—
—
×
6. Engine restarting by ISG
×
—
—
—
×
7. By-pass mode
×
*1/—
*2
—
—
×
×
8. Pre-charge mode
Negative battery cable is connected
—
—
×
—
×
Pre-charge after ignition switched OFF
Ignition switched ON
(Replacement of capacitor (Mazda M Hybrid) only/capacitor (Mazda M Hybrid) self-discharge (vehicle left unattended for long periods) or decrease in capacitor (Mazda M Hybrid) voltage due to back-up current consumption)
—
—
×
×
×
Ignition switched ON
(Capacitor (Mazda M Hybrid) voltage is low (ex. capacitor (Mazda M Hybrid) replacement) during replacement of DC-DC converter (Mazda M Hybrid))
×
—
—
—
×
9. Capacitor (Mazda M Hybrid) power generation mode
When power is supplied to battery
×
—
—
—
×
When power cannot be supplied to battery or hood is opened
—
×
—
—
×
*1:If vehicle electrical load is high or when voltage reduction circuit is overheated
*2:At the time except for *1
Mazda M Hybrid status verification
• The energy generation status can be verified using the center display (with center display) or Mazda M Hybrid indicator light (green) (without center display). For the message content and verification method, refer to the [CENTER DISPLAY] or [Mazda M Hybrid INDICATOR LIGHT (GREEN)].(See
CENTER DISPLAY [WITH CENTER DISPLAY].)
• The Mazda M Hybrid status can be verified using the indicator/warning light. For the Mazda M Hybrid indicator/warning light, refer to the [Mazda M Hybrid INDICATOR LIGHT (GREEN)]/[Mazda M Hybrid WARNING LIGHT (AMBER)].