# US 2014/0152215 A1 · Electric drive unit

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- Number: US 2014/0152215 A1
- Document ID: US20140152215A1
- Status: Published application
- Kind: A1
- Application number: 14/119,729
- Filed: 2012-06-13
- Published: 2014-06-05
- Earliest claimed: 2011-06-13
- Assignees: Spal Automotive S. r. I.
- Applicants: SPAL AUTOMOTIVE S.r.l.
- Inventors: Pietro DeFilippis
- Web page: https://patentgrep.com/patent/US20140152215A1

## CPC

- H02P 6/28: Arrangements for controlling current (H02P6/10 takes precedence)
- H02P 6/157: {wherein the commutation is function of electro-magnetic force [EMF]}
- H02P 23/0004: {Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control}
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

An electric drive unit includes an electric motor, an inverter supplying electricity to the motor, a continuous current stage supplying electricity to the inverter, a controller including a modulator for driving the inverter controlled by a first digital signal representing the amplitude of the phase voltages to be applied to the motor and by a second digital signal representing the electrical frequency of the phase voltages. An analogue/digital stage calculates the optimum value of the advance angle (δopt) of the voltage applied to the motor relative to the counter-electromotive force (“CEMF”) as a linear function of the peak value of the phase current and an analogue/digital stage for measuring the angle (100 act) between the voltage applied to the electric motor and the phase current. The controller is programmed for estimating the angle (γact) between the phase current and the CEMF as the difference between δopt and φact.

## Claims

### Claim 1

An electric drive unit comprising
an electric motor with permanent magnets,
an inverter supplying the electric motor,
a continuous current stage supplying the inverter
a modulator driving the inverter
a controller controlling the modulator by a first digital signal (Vs_act) representing the amplitude of the phase voltages (Vs) to be applied to the electric motor and by a second digital signal (freq_act) representing the electrical frequency of the phase voltages to be applied to the electric motor based on a reference frequency (freq_set) set outside or inside the controller; the drive unit comprising a first analogue/digital stage for
calculating an optimum value of the advance angle (δopt) of the voltage (Vs) applied to the electric motor relative to the counter-electromotive force (Es),
a second analogue/digital stage for measuring the angle (φact) between the voltage (Vs) applied to the electric motor and the phase current (Is).
the drive unit being characterised in that it comprises a temperature sensor positioned close to the permanent magnets and in communication with the first analogue/digital stage for providing to the first analogue/digital stage information relating to the temperature of the permanent magnets, the first analogue/digital stage being designed for calculating the optimum value of the advance angle (δopt) as a linear function of the peak value of the phase current (Is) according to the following equation:
δ
opt
=
π
·
Ls
·
p
K
corr
·
60
·
K
E


0
·
[
1
+
α
mag
·
(
T
mag
-
T
0

mag
)
]
·
Is
where “Ls” is the synchronous inductance of the electric motor expressed in Henry, “p” is the number of poles of the electric motor, “Kcorr” is a corrective coefficient with a value greater than 1 and less than 1.2, “KE0” is the counter-electromotive force constant at a reference temperature “T0mag” of the permanent magnets, “αmag” is the coefficient of variation with the residual induction temperature of the permanent magnets, “Tmag” is the temperature of the permanent magnets measured by the temperature sensor the controller being programmed for
estimating, with an electrical frequency sampling, the angle γact between the phase current (Is) and the counter-electromotive force (Es) as the difference between the aforesaid optimum value of the advance angle (δopt) and the angle (φact) measured between the voltage (Vs) applied to the electric motor and the phase current (Is).

### Claim 2 (depends on 1)

The electric drive unit according to claim 1, where the controller comprises an integrator for
integrating the angle (γact) between the phase current (Is) and the counter-electromotive force (Es) for determining the first digital signal (Vs_act).

### Claim 3 (depends on 1)

The electric drive unit according to claim 1, where the controller is programmed for calculating a frequency correction (Δfreq) proportional to the angle (γact) between the phase current (Is) and the counter-electromotive force (Es) and calculating the second digital signal (freq_act) as the difference between the value of the reference frequency (freq_set) and the frequency correction (Δfreq).

### Claim 4 (depends on 1)

The drive unit according to claim 1, where the second analogue/digital stage comprises an analogue unit generating as output a third digital signal (zc_E-I_phaseU) and having a first input in communication with the drain terminal of the low MOSFET (Q_low_U) of the supply branch of the inverter of a first phase (U) of the electric motor, a second input in communication with the source terminal of the low MOSFET (Q_low_U), a third input in communication with the gate terminal of the low MOSFET (Q_low_U), a fourth enabling input,
the drive unit comprising an enabling unit of the analogue unit generating a high or low enabling signal (zce_run_on_fly) and in communication with the fourth input for transmitting an enabling signal (zce_run_on_fly) to the analogue unit, the analogue unit being driven by the third input and designed for detecting the zero crossing of the current (Is) in a first phase (U) of the electric motor based on the voltage drop between the first and second inputs, the enabling signal (zce_run_on_fly) being high, the high-low transition of the third digital signal (zc_E-I_phaseU) identifying the zero crossing of the current in the first phase (U) when the inverter is switched ON.

### Claim 5 (depends on 1)

The drive unit according to claim 1, where the second analogue/digital stage comprises an analogue unit generating as output a third digital signal (zc_E-I_phaseU) and having a first input in communication with the drain terminal of the low MOSFET (Q_low_U) of the supply branch of the inverter of a first phase (U) of the electric motor, a second input in communication with the source terminal of the low MOSFET (Q_low_U), a third input in communication with the gate terminal of the low MOSFET (Q_low_U), a fourth enabling input,
the drive unit comprising
a resistor (Rzc_fcem_run_on_fly) on a second phase (W) with a 120 electrical degrees delay relative to the first phase (U)
an enabling unit of the analogue unit generating a high or low enabling signal (zce_run_on_fly) and in communication with the fourth input for transmitting the enabling signal (zce_run_on_fly) to the analogue unit, the analogue unit comprising
a resistor in series with the first input with a value equal to that of the resistor (Rzc_fcem_run_on_fly) on the second phase (W) and being
driven by the third input and
designed for detecting the zero crossing of the counter-electromotive force linked between the first phase (U) and the second phase (W) the control signal (zce_run_on_fly) being low and the inverter switched OFF.

### Claim 6 (depends on 5)

The electric drive unit according to claim 5, where the controller comprises
a first calculation unit in communication with the analogue unit for receiving as input the third digital signal (zc_E-I_phaseU) and calculating an electrical frequency (freq_fly) corresponding to the time between two successive high-low transitions of the third digital signal (zc_E-I_phaseU), the controller being programmed for imposing a value to the reference frequency (freq_set) equal to the electrical frequency (freq_fly) corresponding to the time between two successive high-low transitions of the third digital signal (zc_E-I_phaseU) when the inverter is switched OFF, the reference frequency (freq_set) being set inside the controller.

### Claim 7 (depends on 6)

The drive unit according to claim 6, where the controller is designed for generating a fifth digital signal (bridge_enabled) which assumes high logic level if the modulator controls at least one branch of the inverter and low logic level if all the branches of the inverter are switched OFF,
the enabling unit being controlled by the fifth digital signal (bridge_enabled) for imposing a high value to the enabling signal (zce_run_on_fly) when the fifth digital signal (bridge_enabled) has high logic level or for imposing a low value to the enabling signal (zce_run_on_fly) when the fifth digital signal (bridge_enabled) has low logic level,
the calculation unit (15) being controlled by the fifth digital signal (bridge_enabled) for imposing on the reference frequency (freq_set)
a value equal to the electrical frequency (freq_fly) corresponding to the time between two successive high-low transitions of the third digital signal (zc_E-I_phaseU) when the fifth digital signal (bridge_enabled) has low logic level or imposing on the reference frequency (freq_set) a preset frequency value (freq_set_run) when the fifth digital signal (bridge_enabled) has high logic level,
the reference frequency (freq_set) being set inside the controller when the fifth digital signal (bridge_enabled) has low logic level and
being set outside the controller when the fifth digital signal (bridge_enabled) has high logic level.